The study aimed to obtain scientific data useful for the development of methodologies and standardized protocols for welfare donkey monitoring during animal-assisted interventions (AAIs). For this purpose, on thirteen donkeys, ethological tests and physiological parameters (heart rate (HR), heart rate variability (HRV), and root mean square of successive differences (rMMSD)) were assessed during AAI sessions. The AAI sessions determined modifications of tested parameters. These preliminary results can be considered as a starting point for the investigation of the welfare in donkeys used in AAIs.Background: Few studies have been performed to identify objective indicators for the selection of therapeutic donkeys or to assess their welfare during animal-assisted interventions (AAIs) Objective: This study aimed to evaluate the response to the ethological test and the modifications of physiological parameters in donkeys subjected to AAI sessions. Methods: Thirteen donkeys were subjected to a behavioral evaluation during an AAI session. Heart rate, heart rate variability, and root mean square of successive difference values were detected. Results: Statistically significant changes in the tested parameters were observed during AAI sessions. Conclusions: In donkeys, there was a neurovegetative involvement during AAI sessions. Our data give a contribution to the evaluation of donkey welfare during AAIs. In the area of social and health interventions, animal-assisted interventions (AAIs) can be useful from a therapeutic and educational point of view to improve the living conditions of patients affected by various degrees of neurological and mental disabilities, as a part of the treatment plan. In particular, in children with an autism spectrum disorder, an improvement in social functioning and interaction, with reductions in stress, anxiety, and loneliness, has been observed. Meanwhile, in subjects affected by multiple sclerosis, spinal cord injury, and stroke, a decreased spasticity with improved balance has been recorded. In addition, in adolescents affected by mental health, an increase in engagement and socialization behavior, and a reduction in disruptive behavior has been observed ,2,3,4,5.Nevertheless, in the United States and most European countries, AAIs have begun to be implemented in an objective way ,19,20; iThe scientific interest in AAIs is concentrated upon the identification, quantification, and validation of ethological and physiological parameters ,23 for tEquus caballus L. is not always reflected in that of Equus asinus L. [Studies on the use of horses for the AAIs were directed to establish the suitability of the horses rather than the effects on horses’ welfare. For example, a standardized model for the management (housing and training) of horses specifically used for AAT has been formulated . Biometrsinus L. ,37,38,39Biomechanical and kinematic characteristics of the horse’s gait promote the improvement of psychomotor skills, whereas donkeys do not promote benefits in the kinematic aspects. Thanks to their greater empathic sensitivity, donkeys have the potential to improve socialization behaviors and mental health. The more general ethological knowledge on the influence of management conditions on the quality of the animal’s life allows us to believe that animals used for AAIs should express their normal behavior. In particular, as a social and gregarious species, they should express their empathic abilities in the care relationship ,41.In AAIs, the evaluation of the empathic abilities of animals is based on the measurement of their emotional responses. ln different experimental contexts and mainly concern, changes in the level of arousal—mediated through the autonomic nervous system (ANS), the hypothalamic–pituitary axis and the adrenal gland (HPA)—can be monitored through adaptive physiological responses to heart rate (HR), blood pressure (BP), breath frequency (BF), pupil diameter, sweat, corticosteroid levels and neurochemicals . These nIn animals, the research into neuroethology and cognitive ethology concerns the possibility of distinguishing between positive and negative emotions , together with measures of intensity (excitation). In horses, for example, the generic behavioral response of “stress” formed the basis for measuring how they “feel” the modalities of management and training ,48.The paradigm of the novel object test is considered highly stressful, with a consequent surprise effect, short-term responses to fear, and avoidance, together with a significant increase in HR and a decrease in heart rate variability (HRV) ,49. A poHR is considered as a measure of stress in animals because it reflects the ratio between the vagal (which reduces HR) and the sympathetic tone of ANS (which increases HR) ,53,54,55This change can be studied with time-domain analysis or frequency-domain analysis. Time-domain analysis is adopted to quantify changes in R-R intervals (in milliseconds) over time through the assessment of the average R-R interval, the standard deviation of all R-R intervals (SDNNs), and the square root of the sum of the square of differences between successive R-Rs (root Mean Square of Successive Differences—rMSSD). The rMSSD is the time domain parameter that measures the high frequency of beat-to-beat variations that stand for the vagal regulatory activity .The heterogeneous terminology of therapeutic activity descriptions and the lack of standardized protocols of AATs and AAEs suggest the need to adopt validated methodologies and tools for the objective evaluation of the changes induced by the care relationship with equids.The aim of the study was monitoring ethological and physiological parameters which could be useful for the future development of methodologies and contributing to the development of a standardized protocol for welfare donkey monitoring during AAIs.All procedures were performed in full accordance with Italian legal regulations  and the guidelines for the treatment of animals in behavioral research and teaching of the Association for the Study of Animal Behavior (ASAB).the “AWIN welfare assessment protocol for donkeys” [-Body Condition Score-Skin tent test-Absence of injuries: integument alterations, swollen joints, lameness, prolapse-Absence of disease Prior to the acquisition of the ethological data, all animals were subjected to donkeys” , perform1 - EG2). Diurnal ethograms were compilated for all groups.All donkeys included in this present study presented a 3/5 point-score, negative skin tent test and absence of injuries, and later the donkeys were divided into two groups: control groups (CG) and experimental groups  and commercial concentrate feed  and they were free to graze at all times, while water was available ad libitum. The data were collected from April to September 2018. The control group (CG) was made up of 8 healthy Sardinian breed subjects: six females and two stallions, 6 ± 2.20 years old, housed in a milk production farm located in Ragusa , without any experience in AAIs. All animals were housed in a paddock of about 2000 m1 consisted of six Sardinian breed females, with an average age of 8 ± 3.7 years old, housed in the same farm, and subjected to the same management conditions of CG. They were used for AAT, and data recording was performed in the same period of CG. EG2 consisted of seven Amiata breed donkeys, with an average age of 6 ± 3.25 years , housed in a rehabilitation center of a therapeutic community, located in Reggio Calabria , used for AAE. The daily ratio included a single distribution of hay  and commercial concentrate feed , grazing on alternate days, and water was available ad libitum. The study was conducted during the period of April–August 2019. Donkeys were housed in a fenced paddock (800 m2), with a ground floor with a collective box (about 40 m2) located in a corner. All animal care was performed by the guests of the rehabilitation community.The experimental group was divided into two subgroups: EGwww.meteoblu.com).In both areas of study, the environmental conditions followed the normal seasonal pattern for the location  and schizoid forms (F20), according to the tenth revision of the World Health Organization (WHO) international classification of diseases (ICD-10), ex ICD-9 code, diagnostic code 295.8, according to the classifier International Classification of Functioning, Disability and Health (ICF). During the work sessions, the therapist himself modulated the human–animal interaction.EG2 donkeys carried out a working session with 4 adult subjects, 3 males, aged between 16 and 24 years old, guests of the therapeutic community and one male, 42 years old, a long-term care guest of the community, in a nosographic picture like that of EG1.EG1 05:00 a.m.–07:00 p.m.; EG2 05:00 a.m.–05:00 p.m.) was developed to select behavioral states or behavioral events according to the available scientific literature [The donkeys’ full time diurnal ethogram  was examined in 30 min datasheets following the checklist of Continuous recording was performed by means of Hard Disk Drive (HDD) digital video camera systems by the same operator using the focal animal technique  for eachThe evaluation of animals’ temperament is a necessary condition to establish the suitability of animals used for AAIs. Whereas there is a well-known and widespread literature regarding temperament assessment tests on horses ,59,60, o(A) Avoidance Test(a1) Starting PositionThe examiner was in front of the donkey that we wanted to assess. The distance between the examiner and the donkey was approximately 3.5 m, then he moved laterally (right or left) by 45° and observed the animal without moving his arms. If the donkey remained in attention position looking at him for 10–15 s. the observer moved his arm, and if the donkey did not take the avoidance position, the test was passed.(a2) Testing PhaseThe operator standing at the side of the animal (1.5–2.0 m away) approached it at the shoulder and gently placed a hand on it, once with the palm and once with the back of it, going through the withers, and observed the attitude of the auricles, and the position of the head and tail. If the animal did not show responses of avoidance, flight, or fear, the temperament test was passed.(B) Novel Object TestsWe placed an unknown object (tripod) in the center of the collective habitual box and a known person invited the subject to enter and to achieve the center of it; if the subject followed without delay and did not stop, the test was passed.(C) Unknown Person TestA second evaluator, unknown to the donkey tested, entered into the collective box, where the donkey had previously been brought, remaining still; if the donkey approached the unknown person within 3 min, the test was passed; however, if the donkey stopped in the position and pointed to the evaluator, the test was negative.The temperament evaluation test performed on 11 female subjects from the two EGs allowed us to select four subjects for each group, for their evaluation during the AAI sessions. (a)Interaction Animal-Patient monitoring(b)Interaction Animal-Animal monitoring The AAI sessions lasting between 30 and 40 min were taped, and each of these consisted of the animal approach, presentation, contact (see avoidance test a1 and a2), hand control activity (brusque and curry), hand conduct , detachment .(a)Interaction Animal-Patient monitoring1 and EG2 were used individually. The analysis of video setting sequences in a frame to frame through the compilation of an ethological check-list -tactile donkey-patient tactics,-the postural attitudes of the donkeyThe four subjects of the EGeck-list  was doneThe expression level of each indicator was expressed in an arbitrary scale, with a range between a minimum of 0 (very low) and a maximum of 4 (very high), according to Based on the interpretation of the multiple postures, we assigned a score of 0 to the posture of threat, 1 to the posture of indifference, 2 to the posture of submission, 3 to the posture of appeasement, and 4 to the posture of curiosity . The evaTotal score between 0 and 10 = not suitable;Total score between 11 and 15 = to be used in controlled conditions;Total score between 16 and 20 = suitable.The attribution of value to the expected behavioral frameworks provided a preliminary evaluation of the animal’s suitability, according to the following scale:(b)Interaction Animal-Animal Monitoring Social interaction was evaluated by grooming; moreover, we observed other ethological indicators considered as an expression of animal welfare, such as nibbling self-grooming, rubbing self-grooming, bathing/rolling. All observations were performed when all donkeys were in the paddock .® telemetric heart rate monitor for real-time recording, with scanning every 5 s, heart rate monitor activity . The Polar S610i heart rate monitor was placed with a health check band in the auscultation area of the cardiac ichthys, while the Polar V800S with Bluetooth technology was worn by the operator, and the polar belt equine chest strap was placed on the donkey. The obtained data were transferred, through an infrared or Bluetooth port, to a PC equipped with Polar Horse SW 4.0 or Polar FlowSync software Polar® and edited graphically according to preset macros. The entire temporal session of the heart rate monitor data was transferred and edited on a spreadsheet for the processing of descriptive statistics . In EG1 and EG2, HR was monitored during an AAI session; for 10 min before the session (T0); during the session for 10–20 min (T1), and only in EG2 for 10 min after the session (T2).The HR values were detected using both a Polar S610i and Polar V800S Polar®) for recording time of about 40 min (10’ T0 + 20’ T1 + 10’ T2) in each animal of the EG2. For the analysis of the cardiac variability signal, rMSSD obtained by the Polar FlowSync® was considered as a statistical variable derived from the square root of the average of the sum of the squares of the differences between adjacent R-R inter-series. These data were assessed because through the trend of cardiac dynamics it is possible to acquire a series of quantitative and qualitative information to understand the level of activity of the ANS. The different types of heart rate time domain provide specific multiple valence indicators. The rMSSD estimates the activity of the parasympathetic system in a specific period of time. Low rMSSD values indicate a low parasympathetic tone, as in the case of situations with high emotional stress [The data of the R-R interval were acquired using the Polar V800S  of the entire recording period set equal to 100.p > 0.05). Mann–Whitney-U tests for the comparison between not normally distributed data were applied to compare the HR values recorded in EG1. One-way analysis of variance (ANOVA) for repeated measurement was applied to the normally distributed data , using software STATISTICA 7.0 .The Kolmogorov–Smirnov test was applied to verify the normal distribution of data  in this kind of behavioral study is not required in Italy. All procedures were performed in full accordance with Italian legal regulations  and the guidelines for the treatment of animals in behavioral research and teaching of the Association for the Study of Animal Behavior (ASAB). A consent to video-record and use data in an anonymous form was obtained by the parents and health personnel prior to study.(a)The Diurnal Ethogram (05:00 a.m.–08:00 p.m.) of the CG(b)1 (05:00 a.m.–07:00 p.m.) and EG2 (05:00 a.m.–05:00 p.m.)The Diurnal Ethogram of the EG1 and EG2 confirmed the clear prevalence of grazing and feeding of the Sardinian breed of donkey, as well as the Amiata donkey, compared to all the other behavioral categories  (p < 0.05), compared to T0 HR mean values (58.60 ± 2.0)  .2 donkeys are reported in Mean HR values of EG2 showed statistically significant differences at the time T1 vs. T0, calculated by an ANOVA test of repeated measurements (p < 0.05)  .2 are extremely interesting. The parasympathetic tone prevailed over the sympathetic tone at the T0, the rMSSD showed the highest value, indicating low or absent stress. In the EG2-T1 during the AAIs session, HR showed the highest value, and the rMSSD showed the lowest value, confirming the activity of the sympathetic tone and the conditions of emotional discomfort.We believe that the obtained data regarding the rMSSD values in the EGIn the post session, the rMSSD average values were 18.75 ms, although not statistically substantially different from the basal ones (22.26 ms), which demonstrated that the refreshment times must be commensurate with the nosographic pictures of patients. It must be individualized to the donkey subject and, last but not least, cannot be understood only as no working time but must have connotations of emotional refreshment that is possible only in large paddocks and with an adequate period of time.1 and EG2 subjects scored in the range 16–20  of the emotional involvement of donkeys used for AAIs represent a starting point for the definition of a standardization protocol for donkeys used in AAIs.At least, regarding the statistically significant differences in the average HR values in the subjects of the EG, and in the average rMSSD values, particular attention should be paid to the duration of the AAIs sessions and, above all, to the number of sessions with the same subject, providing for a suitable refreshment time between one session and another, represented by the return to the social group and suitable spaces for self-grooming activities (dust bathing). Moreover, in the HRV analysis, it is of special interest to evaluate the power and the frequency of the signal within certain pre-defined frequency bands . VLF banThe benefits achievable through the human–animal relationship have been largely investigated for several categories of patients, such as, for example, children with autism spectrum disorder ,72,73, eScientific studies on AAT, particularly those involving dogs, have shown an openness to and acceptance of this strategy by medical teams ,85,86,87The results of studies on AAT are promising despite the lack of standardization of the number, duration, and frequency of sessions, the executed activities, and the safety measures for the animals and patients.From the social point of view, the growing interest in the topic by families or disabled people and therapist and educators has raised the necessity to regulate and structure the sector, taking into account many issues about the involvement of animals in activities related to human health and wellbeing and stressing ethical , safety Considering that the assigned subjects to the AAIs setting had been selected by temperament and that the social level checklist proved the suitability of the relationship, we must take into account, first of all, the risk for the operator and the patient to work with unsuitable subjects and, last but not least, the demonstrated stress that the AAI session causes to the donkey.On the basis of the scientific evidence discussed in this article, it is possible to highlight the fundamental elements for the definition of a protocol to evaluate the donkey’s behavioral suitability to be used for AAIs, as a tool to support the judgment on the basis of the set of factors–parameters: management, experiential level, the setting of employment risks and type and level of relationship with the patient. Procedurally, the suitable and treated elements to outline a donkey’s ability to be used for AAIs can be identified in the evaluation of the level of reactivity/sociability, which, together with the results of the test for the evaluation of donkey’s welfare and the management conditions, is established by the presence of specific infrastructure and management requirements, as previously treated, which are suitable elements for the responsible use of donkeys in AAIs.


The integration and dispersion capability of the reinforcement into the Al alloy (3xxx Series) matrix was evaluated, using a phase angle difference and surface roughness analyses by atomic force microscopy operated in both the contact mode (CM-AFM) and tapping mode (TM-AFM), respectively. The distribution profile of both rugosity and the phase angle shift was used to statically quantify the integration and dispersion of the reinforcement into the extruded samples, by using the root mean square (RMS) parameter and phase shift coupled with the events number (EN) parameter. Results from Atomic Force Microscopy (AFM) analyses were corroborated by X-ray diffractometry and scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Microhardness tests were conducted to identify the mechanical properties of the composites in the extruded condition and their correlation with the microstructure. A close relationship was found between the microstructure obtained from the AFM and X-ray diffractometry (XRD) analyses and mechanical properties. Among all, the C reinforcement produced the major changes in the microstructure as well as the best integration and dispersion into the Al-alloy coupled with the best mechanical properties.In the present work, nanocomposites-based 3XXX series Al alloy with three different types of hard nanoparticles, including TiO The industrial sector has been interested in new materials as composites, particularly the nanoparticulate-reinforced metal matrix composites (nano-MMC’s). These materials offer some key advantages, including: relatively lower production costs, isotropic properties, and the possibility of using a conventional metal forming process such as rolling, extrusion, and forging for manufacturing different components or products ,2,3. TheThe most cost-effective technique of all existing routes for the manufacture of metal matrix compounds is the liquid metallurgy technique, and it is divided into four main categories: pressure infiltration, stir casting, spray deposition, and in situ processing. The stir casting process has several important advantages compared to other routes, e.g., selection of different types of materials (matrix and hard nanoparticles) and a better control of particle-matrix interfacial bonding and matrix structure. The process is simple, low-cost, and flexible and can be applied in large-scale production processes and is suitable in manufacturing processes for near-net shape components ,11,12,132, C, and CeO2 nanoparticles were fabricated using two techniques such as mechanical grinding and stir-casting, using Mg as an auxiliary element in the incorporation and dispersion of the reinforcing phase [2 is an excellent option because of its good hardness, low density, high melting point, high wear resistance, and good chemical stability [4C3 during the as cast and extrusion process, significantly improve mechanical properties such as yield strength, tensile strength, and Young’s modulus [2 addition greatly increase the hardness, tensile strength, yield strength, and ductility of composites in the as-cast condition [The aluminum beverage cans are globally one of the most critical recycled products, and the process of recycling takes only 5% of the energy needed to produce new aluminum . In ordeng phase . This kitability ,20. On t modulus . Lastly,ondition ,23.2, C, and CeO2 with an average size of about 30 to 50 nm were used as a reinforcing material to increase the recycled Aluminum  matrix strength obtained from beverage cans. Mg powder was used as an auxiliary element the in introduction and dispersion of hard nanoparticles. Using a Spex 8000 mixer/mill in the argon atmosphere, a mixture of 0.5 g of Mg powder, and 6 g of powder in a weight ratio of metallic pure Al/hard nanoparticles of 3:1, were mixed during 5 min and milled using a milling ball to the powder weight ratio of 5:1 for 2 h. The ball mill and vial used were made from hardened steel. The powder mixtures were pressed at a pressure of 10 MPa under uniaxial loading in a hydraulic press during 20 s to get consolidated master compound packets.Different types of hard nanoparticles of TiO2, Alp-C, and Alp-CeO2, were added in the form of a packet into the molten metal when the vortex was formed every 20 s. The aluminum melted was stirred for 10 min, at the constant rate of 650 rpm, at 800 °C, and poured into cast iron cylinder molds. The final content of Mg and the reinforcement particle in Al-alloy was 0.5 wt.% and 1 wt.%, respectively. Each cylinder was hot extruded by using indirect extrusion at 550 °C where the work metal is forced to flow through a circular die. An extrusion relation of 25 was used under high pressure to produce bars of 10 mm in diameter and 500 mm of length. The samples were polished by sand papers with different grades . Then, for obtaining a mirror finish, samples were polished using 1 µm and 0.5 µm alumina slurry. After that, samples were cleaned with distilled water using an ultrasonic cleaner for 5 min before studying under AFM.An electric resistance furnace equipped with an agitator system of the graphite stirrer impeller was used for melting 200 g of a recycled Al beverage can. The master compound packets composed of pure Al and nanoparticles labeled as Alp-Mg, Alp-TiO2, and Al/TiO2. The extruded samples were labeled as Al/Ref, Al/C, Al/CeO2, and TiO2. The diffraction peak width broadening observed is a consequence of the decrease in the size of both crystallite of the Al matrix and reinforcement phase during the milling process. The average size of the reinforcement phase (integrated into the Al matrix of the master compound) was estimated from the Rietveld refinement, which is a detail of the diffraction pattern of the Alp-TiO2 sample from Rietveld refinement analysis is shown in 2 reinforcement phase was around 65 and 40 nm, respectively. The TiO2 phase’s average size was ~18 nm.The XRD patterns from master compound samples after 2 h of milling are shown in 2 sample showed the highest micro-strain lattice value, which suggests the TiO2 reinforcement has a strong effect on the aluminum alloy matrix microstructure.During the extrusion process, at higher rates of deformation, the rearrangement of dislocations during the recovery process coupled with the fine-sized reinforcement dispersion, induce the formation of a nanostructured state with a high presence of micro-strains (or high dislocations density) and reduced crystallite size. The reduction in grain size with increased content of reinforcement can be attributed to its distribution and the pinning effect ,26,27. X2, Al/TiO2, and Al/C composite samples show a more uniform and refined topographic image with a distribution profile located at lower topography values. The height distribution profile of surface roughness was quantified by the RMS (Root Mean Square) roughness parameter, which is the square root of the distribution of surface height topography [2 composite showed the smallest RMS and SD values, which results in uniform dispersion of fine particles of a similar size coupled with the presence of more uniform distribution of small crystallites.The influence of particle dispersion on surface roughness is shown in AFM topography images and height distribution profiles of surface roughness see . In genepography . Accordi2 master compound samples. 2 master compound sample’s phase image shows a topography with uniform, finely rounded grains and the presence of a phase (clear zone) that could correspond to the TiO2 phase located at the limit of grains . The solid line that crosses some specific clear zones in phase images coupled with the corresponding distribution profile of the phase shift  shows the type of particle that produces an angle of about 30° . The event number (EN) of the phase shift produced around 30° of the phase angle difference between the Al alloy and the reinforcement phase, which was used as a quantitative parameter of the dispersion of the reinforcement phase into the Al alloy matrix. The EN and the standard deviation SD of composites are shown in 2 composite, which shows the highest value of EN and the lowest SD. This corresponds to a higher number of fine particles between ~50 to ~80 nm dispersed into the Al alloy matrix and with less presence of agglomerates, respectively , which means the reinforcing phase is mainly agglomerated. This is manifested in a high standard deviation value (~3.88). Precipitates in the form of fiber seen in 4C3 phase. The other phase, which produces a small signal at around 60°  and rounded particles of around 120 nm in size (see the close-up inset in the figure). Fine particles of the Al-Mg phase of about 80 nm were found in the TEM bright-field image into the aluminum matrix of the Al/C composite microstructure  from beverage cans has been produced by combining the powder metallurgy and the stir casting method. The microstructure of the extruded samples evaluated by XRD revealed a nanostructured state and the presence of a lattice micro-strain product of the combined effect of the extrusion process and dispersion of the hard particles into Al alloy. The study conducted to estimate the roughness on the surface revealed a roughness surface at a nanoscale level in all the samples. However, for the composites, the presence of the reinforcement further decreased the roughness level displacing the peak of the height distribution profile to the left. The level of the roughness surface was in concordance with lattice micro-strain values found in XRD analyses. The AFM phase analyses revealed the presence of agglomerates and coarse precipitates (quantified by EN and SD parameters), which negatively affected the microhardness values. A close correlation between microhardness and micro-strain lattice values, together with roughness surface analyses, was observed. Among all, the Al–C composite showed the best mechanical properties, which showed better integration and dispersion of the reinforcement coupled with the presence of fine precipitation of Al


To compare two different fat-saturated magnetic resonance imaging (MRI) techniques-STIR and T2 SPAIR-in terms of image quality, as well as in terms of their diagnostic performance in detecting sacroiliac joints (SIJ) active inflammation.We included 69 consecutive patients with suspected spondyloarthritis undergoing MRI between 2012 and 2014. The signal-to-noise ratio (SNR) was calculated with the method recommended by the American College of Radiology. Two readers evaluated SIJ MRI following ASAS criteria to assess diagnostic performance regarding the detection of active SIJ inflammation. T1 SPIR Gd+ sequence was used as the reference standard.The mean SNR was 72.8 for the T1 SPIR Gd+ sequence, compared with 14.1 and 37.6 for the STIR and T2 SPAIR sequences, respectively. The sensitivity and specificity of STIR and SPAIR T2 sequences did not show any statistically significant differences, for the diagnosis of sacroiliitis with active inflammation.Our results corroborate those in the recent literature suggesting that STIR sequences are not superior to T2 SPAIR sequences for SIJ evaluation in patients with suspected spondyloarthritis. On 1.5-T MRI, T2-weighted SPAIR sequences provide better SNRs than do STIR sequences, which reinforces that T2 SPAIR sequences may be an advantageous option for the evaluation of sacroiliitis. On MRI, active inflammation is characterized by the presence of subchondral bone marrow edema in fluid-sensitive sequences or by contrast enhancement of bone marrow.Early diagnosis is essential for the treatment of axial spondyloarthritis. More recently, the ASAS MRI working group began to recommend the use of T2-weighted fluid-sensitive sequences, such as STIR sequences, as well as T2-weighted sequences with fat suppression, for that purpose.Previously, the Assessment of SpondyloArthritis International Society (ASAS) MRI working group recommended the use of short-tau inversion-recovery (STIR) sequences to identify the bone marrow edema that is indicative of active inflammation of the subchondral tissue,6.In 2017, two different groups of researchers compared STIR sequences with other fluid-sensitive sequences in terms of their ability to detect active inflammation of the sacroiliac joints and found no superiority of the STIR sequences over T2-weighted spectral attenuated inversion-recovery (T2 SPAIR) sequences and T2-weighted Dixon sequences, respectively, being one of the parameters used in the American College of Radiology (ACR) MRI accreditation program. The SNR is a measure of the relationship between the pure signal coming from the studied tissue, which is the signal we truly want to detect, and the background noise. A higher SNR corresponds to a lower effect of background noise on signal detection or measurement. A lower SNR results in an image with a grainy aspect that makes it difficult to analyze the original signal.The signal-to-noise ratio (SNR) is an important parameter in the objective assessment of MRI image qualityTo our knowledge, there have been no studies comparing the SNR of STIR sequences with that of T2 SPAIR sequences in the evaluation of the sacroiliac joints in 1.5-T MRI scanners. Therefore, the objective of this study was to perform a comparative analysis of T2 SPAIR and STIR sequences in terms of the SNR in the sacroiliac region and in terms of their diagnostic performance in the detection of active inflammation of the sacroiliac joints.This was a retrospective, cross-sectional study in which we included consecutive patients undergoing MRI of the sacroiliac joints at our institution between 2012 and 2014. We included patients between 18 to 65 years of age who were under clinical suspicion of having spondyloarthritis. A total of 69 patients were considered eligible. The images were evaluated in accordance with the ASAS criteria for the diagnosis of axial spondyloarthritis. We also calculated sensitivity and specificity. The study was approved by the local research ethics committee (Ref. 30607314.9.0000.5440). Because of the retrospective nature of the study, the requirement for written informed consent was waived.The images were anonymized and evaluated with the open-source software Horos, version 2.1.1 (The Horos Project) to determine the SNR. Because the sample size calculation indicated that at least 30 examinations would be necessary in order to carry out the SNR assessment with adequate statistical power, we selected the MRI examinations of 60 patients. In ten of those examinations, the field of view did not include the air space necessary to perform the reading, all of those examinations consequently being excluded from the assessment. Therefore, the final sample comprised 50 MRI examinations of patients under clinical suspicion of having spondyloarthritis.All MRI examinations were performed in a 1.5-T scanner , with a 17-channel spine coil and the patients in the supine position. The protocol employed for evaluating sacroiliitis includes the following: T1-weighted coronal sequences; coronal STIR sequences; coronal T2 SPAIR sequences; and T1-weighted gadolinium-enhanced spectral presaturation with inversion recovery (T1 SPIR Gd+) sequences. The acquisition parameters for the sequences are shown in . In brief, the SNR is obtained by dividing the mean signal for a region of interest (ROI), designated the signal ROI, by the standard deviation obtained in another ROI positioned over the signal-free air space, designated the background ROI.The SNR was calculated by using the method recommended by the ACRTo measure the signal, the ACR recommends the use of an ROI of at least 50 pixels, positioned over the tissue of interest. Because radiologists evaluate spondyloarthritis by looking for changes in the subchondral bone marrow, it was decided that the signal ROI should be positioned over the bone marrow. As a reference standard for subchondral bone marrow evaluation, we chose to position the signal ROI over the central region of the sacrum. The placement of the signal ROI over the subchondral bone of the sacroiliac joint would be subject to variations related to patient pathological status , although determining that status was not within the scope of this study, which was focused on the SNR of the sequences, regardless of the presence or absence of disease.To obtain the background noise value, the ACR suggests the creation of an ROI in the external air space surrounding the patient, in an area free of artifacts. In the 50 patients evaluated here, an air ROI with a minimum of 300 pixels (a background ROI) was selected for each sequence, the Horos software being used in order to collect the standard deviation from the background ROI .The SNR was obtained by dividing the mean signal of the signal ROI by the standard deviation of the background ROI. That calculation was performed for all three MRI sequences  in each the 50 patients separately, and the data were subsequently placed in a table for statistical evaluation.. According to the ASAS criteria, examinations showing subchondral bone edema in two consecutive images or at two different sites within the sacroiliac joints are considered positive for inflammatory sacroiliitis.Two musculoskeletal radiologists with 15 years and 4 years of experience in evaluating MRI scans of the musculoskeletal system, respectively, evaluated each sequence and classified the examination as positive or negative for sacroiliitis, according to the diagnostic criteria of the ASAS working groupIn the assessment of diagnostic performance, the results of the reading of the T1 SPIR Gd+ sequences were used as a reference. The positivity or negativity for inflammatory activity in the T1 SPIR Gd+ sequence was determined by consensus between the two readers. In cases of disagreement, a third radiologist, with 14 years of experience in interpreting MRI scans of the musculoskeletal system, made the final decision.p < 0.05 were considered statistically significant.In the evaluation of the SNR, the correlation between sequences was performed by paired t-tests, the differences in SNRs identified for each sequence in each patient serving as the dependent variables. Sensitivity and specificity measurements were performed for each reader and for each study sequence (STIR and T2 SPAIR) in comparison with the gold standard (T1 SPIR Gd+). The level of interobserver agreement was determined by calculating the kappa statistic. Values of In the evaluation of image quality, the mean SNR was 72.8 for the T1 SPIR Gd+ sequence, 37.6 for the T2 SPAIR sequence, and 14.1 for the STIR sequence. The distribution of the SNR values can be seen in p < 0.000). Comparing the signal of the T2 SPAIR sequence with that of the T1 SPIR Gd+ sequence, we found a difference between the two mean SNRs of 35.2 (95% CI: 42.4-28.1), the mean SNR also being significantly higher for the T1 SPIR Gd+ sequence (p < 0.000). The difference in the mean SNR between the STIR and T2 SPAIR sequences was 23.4 (95% CI: 17.2-29.6), the mean SNR being significantly higher for the T2 SPAIR sequence (p < 0.000). The diagnostic performance of the T2 SPAIR and STIR sequences is shown in The comparative evaluation of the mean SNRs between the sequences, performed in a paired manner, patient by patient, by the paired t-test, revealed a difference of 58.7 (95% CI: 68.0-49.4) between T1 SPIR Gd+ and STIR, the mean SNR being significantly higher for the T1 SPIR Gd+ sequence  score. The STIR sequence is just one of the many possible methods of fat suppression, which makes it possible to identify bone edema,13. Currently, there are several MRI fat-saturation techniques available. The various techniques are based on the frequency of precession in the electron cloud surrounding the hydrogen proton, which is different in water than in fat. That difference makes it possible to create techniques based on the chemical shift. For fat saturation, there are techniques based on chemical shift, such as chemical-shift selective saturation, water excitation, and Dixon techniques; techniques based on inversion, such as STIR; and hybrid techniques, such as SPAIR and SPIR,15.The identification of sacroiliac joints inflammation is of great importance for the diagnosis of axial spondyloarthritis. The relevant findings in the evaluation of the sacroiliac joints include enthesitis, synovitis, capsulitis, and erosions, the technique has been widely used. It is not very sensitive to field heterogeneity and has good fat saturation, even outside the central region of the magnetic field. It also has satisfactory fat saturation, even in the presence of metal implants. The disadvantage of the STIR sequence is its low SNR. That disadvantage could be mitigated by shortening the echo time, although that also reduces the T2 weighting of the image.Since the STIR sequence was first described by Bydder et al.. In contrast, the Dixon techniques have low sensitivity to field heterogeneity and excellent SNRs, even in areas near metallic implants, those advantages being most pronounced in the three-point water-fat decomposition method.Hybrid sequences, such as SPAIR, combine an inversion-recovery pulse with an adiabatic radiofrequency pulse. Studies have shown that SPAIR sequences are relatively insensitive to field heterogeneity and tend to have better SNRs than do STIR sequences,9,13. In our study, the T2 SPAIR sequence showed a mean SNR 2.66 times greater than that of the STIR sequence and the mean examination time was comparable between the two. This can be considered the greatest advantage of the T2 SPAIR sequence and one of the reasons for its use. Even when using similar examination times, slice thickness, and T2-weighting parameters, we found a higher SNR for the T2 SPAIR sequence. The SPAIR sequence has more options with respect to slice thickness, T2 weighting, and matrix, without substantially impairing the image quality, because it has a higher SNR.The image quality assessment performed in the present study also confirmed previous findings showing that the SNR is higher for SPAIR sequences than for STIR sequences,18,19.Our study has some limitations, including those inherent to its retrospective design. Another limitation is that the T1 SPIR Gd+ sequence with fat suppression was used as a reference to calculate the diagnostic performance of the STIR and T2 SPAIR sequences. Although subchondral tissue biopsy would probably be the ideal reference, it would be unethical to subject patients to an invasive procedure in order to validate a concept of comparing MRI sequences. Therefore, we decided to use the reference that has been most widely employed in the evaluation of active inflammation of the sacroiliac joints,6,10. We found no difference between the STIR and T2 SPAIR sequences in terms of their diagnostic performance in identifying active inflammation of the subchondral bone tissue of the sacroiliac joints. Our results also indicate that, on 1.5-T sacroiliac joints MRI, the T2 SPAIR sequence provides a better SNR than does the STIR sequence, which reinforce that the use of T2 SPAIR sequences is a viable option for the evaluation of inflammatory sacroiliitis, with some advantage over STIR sequence.Our findings support those reported recently in the literature, suggesting that there is no superiority of the STIR sequence over other fluid-sensitive sequences for the evaluation of subchondral bone edema of the sacroiliac joints in patients with spondyloarthritis


By recycling used glass containers, we are able to recover and reuse their valuable properties, which is a way to preserve the relevant natural resources and lessen environmental burdens. For example, recycled waste glass (in the form of powder) can be used in the production of concrete. This article analyses the effect of waste glass addition on the properties of C12/15, which is used, for example, as concrete bedding material to support road drainage gutters and kerbs. Ground waste glass was used as a filler in the mix, i.e., without decreasing the amount of cement. Brown glass collected as municipal solid waste was used in this research. The research comprised an experiment prepared on the basis of the central composite design. The independent variables included water/cement ratio and the amount of glass powder, expressed as the glass to cement ratio by weight. The adopted research program mainly included the definition of the concrete compressive strength, water absorption and freeze–thaw resistance after 25 and 100 cycles of freezing and thawing. For selected systems, the characteristics of air voids in hardened concrete were also defined. The beneficial effect of ground waste glass added as a filler to the concrete mixture on the strength and durability of concrete was confirmed by the obtained test results. The aspects related to the reuse of waste materials, such as waste glass, in the field of construction have become an increasingly widely explored subject of scholarly articles. Although the amount of waste glass collected and recycled in the EU increases year by year, as demonstrated by the most recent data , there aCurrently, waste glass is used as a raw material for the production of glass fibres used in production of thermal and sound insulation panels, mats, and lagging. For example, a very fine-grained waste glass powder is used to produce expanded glass beads added to wall coatings and mortars. Another waste glass material, namely waste flat glass, is used for the production of glass microspheres .Numerous studies have been conducted on the possibility of using finely ground waste glass as a partial replacement for cement in concrete. A smaller glass particle size led to a higher compressive strength in concrete and compared to fly ash concrete, concrete containing ground glass exhibited a higher strength at both early and late ages . The comThe results of studies on the impact of glass granulate as a substitute for natural aggregate in concrete are known. The addition of 25% and 50% of crushed waste glass sand promotes a significant improvement in strength, and the optimum glass content should be 25% for the production of sustainable eco-concrete . With thResearchers expect that fly ash and slag may soon become scarce due to their increasing reuse in the production of energy, similarly to other renewable sources. It is, therefore, justified to search for alternative fine-grained materials that could be successfully used in the production of concrete. Ground waste glass can be an option of choice in these circumstances. Other than fly ash or slag, this additive is not a combustion by-product. Moreover, due to the high cost of segregating small-size waste glass items (advanced sorting systems are needed in the process), coloured waste glass seems to be a very promising option in this application. This applies in particular to lower strength classes of concrete , in which various types of waste/by-products coming from various industries have been successfully used for a number of years. The primary applications of this material include bedding under road gutters and kerbs and as a road-base material. It is related to a very wide range of infrastructural investments, which are and will be implemented in Poland for many years.In Poland, road engineers use in the design process the so-called catalogues of standard constructions ,24, whicThe review of the mix specifications of concrete types currently used on the national roads in the West Pomerania province of Poland showed that C12/15 and C16/20 are the prevalent types of concrete mixes. C12/15 concrete is used to support precast gutters at the edges of road pavements and kerbs around the roundabout overrun areas and traversable roundabout islands. C16/20 concrete, in turn, is used much less frequently, predominantly as the base course of pavements in bus lay-by areas. This gives a chance to utilise in this way at least a part of the waste glass sent to landfill. With a vast majority of the research project carried out so far dealing with the use of waste glass as a partial substitute to cement and fine aggregate, the authors have decided to investigate the use ground waste glass as a filler, without decreasing the content of cement in the concrete mixture.As part of the project, an experiment plan was generated in the statistical program Statistica (the “Design of Experiments” module) . A centr1  and x2 . The input values were W/C, in the range of 0.73–0.87 and GP/C, which was in the range of 0% to 45%. Nine series of specimens were produced, differentiated by the concrete mix composition. The studies were carried out for five intermediate values of input data x1 and x2 determined for standardised values equal to 0, ±1 and ±1.414. The standardised values resulting from the adopted plan were calculated into real values of variables. The coded variables and the compositions of the respective series of specimens in the adopted experiment plan are compiled in The tests were carried out on concrete mixes based on natural aggregate for five intermediate input values xThe constants were the type and class of cement, fine and coarse aggregate types, method of adding the ingredients, mixing method and time and method of compacting fresh concrete, curing time, and curing conditions and, last but not least, the test apparatus.3 and the density of cement was 3.102 g/cm3. The Blain air permeability test was used to measure the specific surface area and ground glass was found to have a greater specific surface than cement (4737 cm2/g compared to 3728 cm2/g).Brown glass was chosen for this experimental research. It was cleaned and dried and then crushed and powdered . The iniThe compositions of prepared mixes are given in The mix included 200 kg of Portland cement CEM I 42.5R manufactured by Cemex Gdynia, in which cement clinker was the only cementitious material . Fine-grained aggregate was 0/2 mm sand from Bielinek sand and gravel pit. The percentage of sand contained in the aggregate mix was 50.6%. Additionally, 2/8 mm and 8/16 mm gravels from Ognica pit were used as coarse aggregate.Consistency, determined with the slump cone test according to EN 12350-2 ;Air content determined with the pressure gauge method according to EN 12350-7 ;Density according to EN 12350-6 .The prepared concrete mixes were tested for the basic properties including:The results of concrete mix tests are given in 3 and 2273 kg/m3. Taking into consideration the measurement uncertainties, one can conclude that the addition of glass powder with an identical water/cement ratio does not impact the concrete mix air content and its consistency. The differences in the results of air content and concrete mix density are comparable and smaller than the measurement uncertainty.The consistency and air content were measured once, 15 minutes after water was added to the mix. Two of the tested mixes, namely PW4 and PW6, attained S2 consistency and the other ones fell in the consistency class S1. The total air content in the mixes ranged from 4.0–5.1%. The density of concrete mix oscillated between 2219 kg/m1 (W/C) and x2 (GP/C) are given in parentheses next to the concrete mix symbol.Out of each concrete mix, a series of six specimens was created for determining the compressive strength. To determine the strengths of the specimens, compression testing machines  were used. Compressive strength was determined after 7 and 28 days of curing the specimens in water at the temperature of 20 ± 2 °C. The tests were carried out on three 150 mm cubes, according to the procedure described in EN 12390-3 . The FigThe compressive strength results varied strongly, in the range of 18.1–29.9 MPa. The assumed compressive strength to satisfy the requirement of the C12/15 strength class according to EN 206 after curing for 28 days  was obtaFrom the analysis of the 7 day and 28 day compressive strength values, it follows that the increase in strength of the control concrete mix by 25.1% was much smaller than that obtained for the mix containing waste glass. The highest levels of strength increase, viz. from 30.5% to 51.9%, were noted for the mixes containing waste glass. As we have observed, with the same water-to-cement ratio, the higher the proportion of waste glass, the higher the increase in the compressive strength of the mix.Water absorption of the tested mixes was determined according to PN-B-06250:1988 . Four 10According to the obtained water absorption test results, the absorption criterion, as per PN-S-96014:1997 , was satFreeze–thaw resistance of concrete was tested according to PN-B-06250:1988  with theBased on the frost resistance criteria of PN-B-06250:1988 , the weiThe freeze–thaw resistance criteria were satisfied by all the mixes subjected to a standard procedure  comprisiOther than in the case of 25 freeze–thaw cycles, 100 cycles caused an average increase in the specimen weight by 0.3%. Furthermore, the higher number of cycles caused a greater decrease in the compressive strength, namely by 3.0 to 45.0%. Only two mixes showed no observable distress: PW2 and PW5 b. By satDefining the characteristics of air voids in hardened concrete was carried out in accordance with the EN 480-11:2008 standard . SpecimeL (the average distance to the nearest air void), which should not be larger than 0.2 mm. Another, also important parameter is the minimum air content in air voids smaller than 0.3 mm, marked as 300A, which should equal at least 1.5%. The data obtained as a result of the automatic analysis of the image from four specimens of the surface from each spacing of concrete air voids selected for the analysis allowed for calculating the total content of air (A), the specific surface area of the air voids (α), the air void spacing factor (L) and the content of micro-air-voids with a diameter lower than 0.3 mm (300).A The obtained average values of the analysed parameters, defined according to the standard [Concretes marked as PW5, PW8 and PW9 contain the addition of glass powder and demonstrate significant compressive strength and resistance to cyclical freezing and thawing. Concrete marked as PW7, in turn, is control concrete, which does not include the addition of glass powder. It meets the minimum requirements associated with the concrete strength class, but it does not meet the requirement of the F100 degree of freeze–thaw resistance. The most frequently adopted parameter for the assessment of the freeze–thaw resistance of concretes is the air void spacing factor standard , in part−1. Differentiated results were obtained for the total air content, unlike the results of the analysis of air content in the concrete mix, defined using the pressure method (from 5.8% to 13.2%). The total air content in the hardened concrete fits within the range of 10.9–18.2%. Such a high air content is probably the result of the insufficient compacting of the specimens. The highest value of the air void spacing factor (L) and the lowest content of micro-air-voids (300A) were demonstrated by the concrete marked as PW8, which included the highest amount of the addition of glass powder. In the case of an identical water/cement ratio equal to 0.80, one can notice that in concrete PW8, along with the increase in the amount of glass powder (from 22.5% to 45.0%), there was a decrease in the total content of air and micro-air-voids (300A); whereas in concrete marked as PW5, with the water/cement ratio lower than in concrete PW9 , one observes lower total content of air and of air voids with a diameter lower than 0.3 mm and a lower specific surface area of the air voids (α). While analysing the achieved results of marking the characteristics of the air void spacing in selected concretes , it is possible to conclude that they meet the requirements in reference to concrete utilized in XF conditions. According to the standard , concretFor the purpose of designating the spacing of air voids, a calculation model was adopted, which assumes the occurrence of air voids of a certain determined diameter. It is a transitional model between the actual state and Powers’ model. The measured chords are classified into appropriate length ranges, and subsequently, the number of chords in a given length class is determined and multiplied by the volume of a single air void with the diameter equal to the top limit of a given class. The size distribution of air voids recorded during the study conducted on four specimens has been presented in As was demonstrated in the distribution of air content as a function of the air void diameter  in hardep). The variance equality hypothesis was also found to be true through the Levene and Brown–Forsyth tests. The analysis of data also included checking the significance of the effect of input data (W/C and GP/C) on the values of the output variable (28 day compressive strength). The Fisher–Snedecor test was employed for this. The values of significance levels p below 0.05 indicate a significant effect of the water–cement ratio and the amount of added glass powder (in relation to the weight of cement) on the 28 day compressive strength of the tested mixes. In the further part of the statistical analysis, a model representing the effect of independent variables on the 28 day compressive strength was built on the basis of the output data of the experiment carried out according to the central composite design. A linear-quadratic model with two-way interactions was adopted in the first place. Insignificant components were then left out one by one through the analysis of the results in Statistica [The results were subjected to a statistical analysis in the software program Statistica . First, atistica . FinallyThe regression function was verified on the standardised values iA (regression coefficient) of this equation were obtained with the Gauss–Newton method of estimation. Using the t-Student test factors, 2A, 4A and 5A were excluded as insignificant at the significance level of 0.05. The correlation factor R was 0.96. In the case of two input data values (W/C and GP/C), it is possible to develop the contour diagram that presents the response surface of the object of studies. The values of the predicted 28 day compressive strength are given in The constants Linear relationships were obtained between the 28 day compressive strength and both of the analysed parameters, i.e., waste glass to cement ratio by weight and the water–cement ratio. From the results of the statistical analysis of the mechanical parameters obtained in the tests, it can be seen that the compressive strength increased with the increasing proportion of glass powder and the decreasing level of the water–cement ratio. The tests confirm how strongly the compressive strength depends on the water–cement ratio of the concrete mix. Within the analysed ranges, the effects of glass powder and water–cement ratio on the freeze–thaw durability of concrete are not statistically significant.Improves the 28 day compressive strength by ca. 20% and 40% when added at the proportions of 22.5% and 45%, respectively;Does not increase water absorption;Improves the freeze–thaw durability of concrete (without the presence of de-icing agents), which is testified by compliance with the requirements given for F100 concretes designated PW8–PW10.Glass powder changes the properties of low-strength concrete mixes (as compared to the control mix PW7 with the same water–cement ratio and without ground waste glass addition) as follows:Except for PW3 and PW6, all of the tested mixes satisfied the requirements of  in termsMixes PW2 and PW5, in addition to the above-mentioned requirements, also satisfy the compressive strength, water absorption and freeze–thaw resistance criteria defined for concrete class F25 in the Polish standard no. PN-S-96014:1997 , and thuThe average parameters of the microstructure of air voids according to the standard  in speciThe tests carried out as part of this research and the analysis of the obtained result allow us to draw the following conclusions:Therefore, it is possible to produce lower strength concrete mixes containing ground waste glass in the role of filler, i.e., not as a partial substitute to cement. It remains to say, based on the study results, that the prospects for recycling waste glass as a component of concrete mixes are promising. This opinion must, however, be verified by further testing, especially using higher strength mixes. Such verification should cover, in particular, the durability of concrete, including resistance to the action of de-icing salts.


Carbon fiber significantly enhances the mechanical, thermal and electrical properties of rubber composites, which are widely used in aerospace, military, national defense and other cutting-edge fields. The preparation of a high-performance carbon fiber rubber composite has been a research hotspot, because the surface of carbon fiber is smooth, reactive inert and has a poor adhesion with rubber. In this paper, a high-performance rubber composite is prepared by mixing dopamine-modified staple carbon fiber with natural latex, and the mechanisms of modified carbon fiber-reinforced natural latex composite are explored. The experimental results show that the surface-modified staple carbon fiber forms uniform and widely covered polydopamine coatings, which significantly improve the interface adhesion between the carbon fiber and the rubber matrix. Meanwhile, when the concentration of dopamine is 1.5 g/L and the staple carbon fiber is modified for 6h, the carbon fiber rubber composite shows excellent conductivity, thermal conductivity, and dynamic mechanical properties, and its tensile strength is 10.6% higher than that of the unmodified sample. Carbon fiber (CF) is formed by the thermal conversion of organic fibers, and has a high strength, high modulus, high thermal conductivity, chemical corrosion resistance and other excellent properties ,2. At prThe surface modification of CF has become the main method to enhance the interfacial adhesion, which can be divided into physical modification and chemical modification ,8,9,10. The processing method of CFRC is also an important factor affecting the interfacial adhesion. In the traditional processing, the natural rubber (NR) subdivision, CF incorporation, agglomeration of CF and uniform distribution of CF successively occurs, which mainly depends on the strong shear force provided by the internal mixer in order to realize the uniform dispersion of CF in the rubber matrix, as shown in The present work investigates the difference in the properties of CFRC prepared by NRL or NR and verifies the advantages of wet mixing NRL and CF to prepare NRL/CF composites. Consequently, the mechanisms of dopamine surface-modified carbon fiber-reinforced natural rubber latex composites are systematically studied. Furthermore, the effects of dopamine concentration and modification time on the properties of composites are studied.The interface behavior between the CF and the rubber matrix is a key factor affecting the performance of composite materials. A polydopamine layer was grown on the surface of CF, after being modified by dopamine, which was covered by a latex film formed by natural latex, and then bonded with the rubber matrix to produce good interfacial interaction. Dopamine surface-modified carbon fiber can enhance the bonding effect between the CF and the rubber matrix. Dopamine can be oxidized and self-polymerized in alkaline aqueous solution, forming a polydopamine layer and a covalent bond with double bond groups in rubber molecules, while binding with CF through intermolecular interaction, which involves a Van der Waals interaction, hydrogen bond, and other non-covalent interactions, thus forming a good interface effect. The formation process of the polydopamine layer is shown in (1) Impregnate CF with NRL:Use ultrasound  to vibrate the NRL to destroy the protein layer and phospholipid layer of the latex particles. Clean the CF with deionized water and add it to the treated NRL. Use the high-speed disperser  to mix the composite for 10 min, and then pour it into a large tray and tile it for drying in order to prepare the NRL/CF masterbatch.(2) Modify CF with different concentrations of dopamine:Prepare dopamine solutions with concentrations of 0.5, 1, 1.5 and 2 g/L. Add the Tris  to the dopamine solution and adjust the pH to around 8.5. Clean the CF with deionized water, and add it into different concentrations of dopamine, heating for 2 h in a water bath. Then, clean the modified CF by deionized water again, in order to mix it with the NFL treated by ultrasound.(3) Modify CF with different processing times of dopamine:Clean the CF with deionized water and add the CF into four dopamine solutions with a concentration of 1.5 g/L, heating for 2 h in a water bath. Then, clean the modified CF by deionized water again, in order to mix it with the NFL treated by ultrasound.(1) NR/CF composite:CF, NR and other fillers were incorporated into the mixer for mixing. The mixing process was as follows: the rotating speed was 60 rpm, the filling coefficient of the mixer was 0.7, and the cooling water temperature was 60 °C. Sulfur and accelerant were incorporated into the open mill to prepare the compound of NR/CF composites.(2) NRL/CF composite:(a) The mixture of modified CF and NRL treated by ultrasound was mixed by the high-speed disperser for 10 min, and then drying to prepare NRL/CF masterbatch;(b) The masterbatch and other fillers were incorporated into the mixer according to the mixing process of the compound of NRL/CF composites. Sulfur and accelerant were incorporated into the open mill to prepare the compound of NRL/CF composites.The rubber compounds were cured at 150 °C at a pressure of 10 MPa for an optimum cure time (t90) + 3 min.Curing Characterization. The curing characterization of rubber compounds was evaluated using a moving-die rheometer (M-2000-AN) from GOTECH TESTING MACHINES CO., Ltd. The specimens were tested according to ISO 6502-2: 2018. The Mooney viscosity values of the rubber compounds were evaluated using a Mooney viscometer  according to ISO 289-2: 2016.Physical and Mechanical Properties. The hardness of the rubber vulcanizate was evaluated using Shore Hardmeter  according to ISO 7619-2: 2004, three points were measured for each sample and the final result produced the median [Dynamic Mechanical Thermal Analysis. The viscoelastic mechanical properties of the vulcanizates were evaluated using a dynamic thermomechanical analyzer , in which the test temperature range was −65 to 65 °C, the heating rate was 2 K/min, the vibration frequency was 10 Hz, the static strain was 5%, the static force was 70 N, the dynamic strain was 0.25%, and the dynamic stress was 60 N. Morphology Analysis. The cross-section of the sample after tensile fracture, which adhered to the conductive adhesive and was fixed on the sample table for gold spraying, was observed under a scanning electron microscope .Payne effect. The Payne effect of the composites was tested by the rubber processing analyzer, in which the scanning conditions were set at 60 °C, the scanning frequency was 1 Hz, and the scanning range was 0.28%–40%.The cohesion interaction between the CF and the rubber matrix can be seen clearly from the electron microscope image, which is important for the evaluation of surface-modified CF by dopamine. The CF is impregnated with NRL to form an adhesive film on its surface, which strengthens the adhesion between the CF and NRL from The CF modified by dopamine adheres closely to the rubber matrix, and there is no difference from When CF is separated from the rubber matrix, the surface morphology of NRL/CF composite prepared under different modification times is different from ML), maximum torque (MH), degree of crosslinking (MH − ML) decreased, and the Mooney viscosity (ML(1 + 4)) increased from group A to B in The processing properties of the NRL/CF composition were improved by CF impregnated by NFL, meaning that the value of scorching time (tc10), curing time (tc90), minimum torque , tensile stress at 300% elongation (TS 300%), tensile strength, elongation at break, resilience and DIN abrasion compared with the NR/CF composite, whereas volume resistivity is prominently improved from A to B in The hardness of the composite of NRL/CF is basically unchanged, TS 100% and TS 300% tend to grow with the increase in dopamine concentrations from groups B, C, D, E and to group F in The hardness, resilience and abrasion of NRL/CF composites were less affected by the processing time of dopamine-modified carbon fiber. The comprehensive properties of NRL/CF composites were the best when carbon fibers were modified by the dopamine solution for 6 h. The main reason is that, before the optimal modification time is reached, the longer the time is, the larger the coverage area of the polydopamine coating on the surface of the CF is and the more uniform the thickness is, which is conducive to the interfacial adhesion between the CF and the rubber matrix. When the modification time exceeds the optimal value, the thickness of the polydopamine coating on the surface of the carbon fiber will be too thick or uneven, which will lead to a decline in the interfacial adhesion between the carbon fiber and the rubber matrix, thus reducing the mechanical properties of the rubber composite. The volume resistivity of the NRL/CF composite increases with the increase in modification time, indicating that the conductivity of the rubber sample decreases. Because of the poor conductivity of dopamine, the formation of polydopamine growing on the surface of carbon fiber will hinder the conduction pathway of the carbon fiber, thus reducing the conductivity of the NRL/CF composite.CF has good thermal conductivity, which is dispersed evenly in the rubber matrix and overlaps to form a thermal conduction channel, enabling the NRL/CF composite to have a strong thermal conductivity. The thermal conductivity coefficient of the composite presents the tendency of rising first and then decreasing at temperatures of 60, 90 and 120 °C with the increase in the dopamine concentration from The effect of CF modification time on NRL/CF composite is the same as that of modification concentrations. This is mainly because the modification time also affects the uniformity of the dopamine layer on the surface of the carbon fiber. The dopamine layer cannot be distributed evenly under either a shorter or longer modification time. When the modification time is 6 h, the dopamine layer distributes evenly on the surface of CF, and the thermal conductivity coefficient of the composite is high.The Payne effect  can evalGenerally speaking, the better the dispersion of the filler is, the lower the Payne effect is. The shear modulus The The value of The dynamic viscoelasticity of vulcanized rubber includes rolling resistance, wear resistance and wet-skid resistance. Rolling resistance reflects fuel economy, wear-resistance reflects the durability and service life of the tire, and the anti-skid performance is directly related to the safety of the tires, which attracts much attention.The curves of the loss factors with the temperature changes in the NRL/CF composites basically overlap with the curves of the NR/CF composites from The loss factor of the composite of NRL/CF modified by dopamine of different concentrations is lower than that of the unmodified one at temperatures of 0 and 60 °C . The intThe loss factor of the composite of NRL/CF modified by dopamine of different modification times changes slightly at a temperature of 0 °C, and decreases gradually at 60 °C . A polyd(1) Impregnated by the natural latex, the adhesion between staple carbon fiber and rubber matrix is reinforced, and the material properties of the composite are better than those prepared by the traditional method;(2) When the concentration of dopamine was 1.5 g/L and the modification time was 6 h, the properties of the composites modified by dopamine were the best. The main reason is that when the concentration and modification time reaches an optimal value, dopamine forms a uniform polydopamine coating with a wide coverage on the surface of the carbon fiber, which significantly improves the interface adhesion between the carbon fiber and rubber matrix.


The fluorescence spectra were obtained within 400–600 nm and treated by principal component analysis (PCA). No fluorophore allowed for the discrimination of all samples. To evaluate the discrimination performance of fluorophores, we introduced crossing number (CrN) calculated as the number of mutual intersections of confidence ellipses in the PCA scores plots, and relative position (RP) characterized by the pairwise mutual location of group centers and their most distant points. CrN and RP parameters correlated with each other, with total sensitivity (TS) calculated by Mahalanobis distances, and with the overall rating based on all metrics, with coefficients of correlation over 0.7. Most of the considered parameters gave the first place in the discrimination performance to Ru(bpy)32+ fluorophore.In this study we develop a variant of fluorescent sensor array technique based on addition of fluorophores to samples. A correct choice of fluorophores is critical for the successful application of the technique, which calls for the necessity of comparing different discrimination protocols. We used 36 honey samples from different sources to which various fluorophores were added ( Fluorescence spectrum of a sample comprises a specific fingerprint, which can be used for classification purposes. Most fluorimetric fingerprinting classification methods use intrinsic fluorescence of samples ,2. A lesA key issue in the development of the “add-a-fluorophore” strategy is selection of fluorophores, since their chemical nature determines the possibility of fluorescence quenching/dequenching by the sample components. To make a proper selection of fluorophore(s), a method of comparing the discrimination results is quite necessary. In case for incomplete discrimination, the simplest characteristic of performance is the number of discriminated groups. However, sometimes it does not reveal the difference between various added fluorophores. It is important to develop new techniques for assessing discrimination performance: effective, convenient, and at the same time simple.In this work we are suggesting two measures of discrimination: first is calculation of the number of intersections of confidence ellipses in the principal component analysis scores plots , and second is relative position (RP) characterizing the pairwise mutual location of group centers and their most distant points. The suggested parameters are compared with the standard metrics for the multiclass classification: total sensitivity (TS), that equals the ratio of correctly classified samples to the total number of samples, calculated using various methods , and also the number of discriminated groups of samples in the PCA scores plots (No of groups).In this study we classified 36 samples of honey of different origin. A number of examples of successful application of fluorescent fingerprinting technique to the discrimination of honeys is published ; honeys In an attempt to improve the discrimination of honeys with respect to using only their intrinsic emission, we added several fluorophores to the samples. No complete discrimination in one step was achieved with any fluorophore because of a large number of samples of similar nature. A large number of non-discriminated samples complicated the selection of the fluorophore allowing for the most complete discrimination. To solve this problem, we applied the suggested performance criteria.−1 each), and trisdichlororuthenium(II) (Ru(bpy)32+) (Aldrich) . DNA-1 and DNA-2 solutions were diluted to 7.2 × 10−5 mol·L−1 with water prior to use. Thiazole orange  was used to prepare all solutions.We used the metal complexes proved efficient in the previous fingerprint studies as fluorophores for the middle-wave part of the visible spectrum : zincIIc obtaineAldrich) a dissolvating it  into deoe orange b was useChamaenerion angustifolium) honeys 17, 18, 19, 28, 31; linden (Tilia) honeys 20, 21, 22, 23, linden and raspberries honey 24; hippophae (Rhamnus) honey 25; white acacia honey 26; lavender honey 29; honey with galipot 30. The samples from the stores included polyfloral honeys 5, 6, 7, 8, 9, 12, 13, linden (Tilia) honey 10, and buckwheat (Fagopyrum esculentum) honey 11. Honeys were dissolved at 0.1 g/mL in water in 10-mL vials and stored at 4°C until analysis.The honey samples (Nos 1–36) were produced in Russia between 2016 and 2018. The information on the botanical origin of honeys was obtained from the label  or conveyed by the farmer (for the farm honey samples). The farm samples included polyfloral honeys 1, 2, 3, 4, 27, 32, 33, 34, 35, 36; clover (trefoil) honeys 14, 15, 16; fireweed  were placed in the wells of a 96-well polystyrene plate  and one of the following fluorophore solutions see  was addeAgilent Cary Eclipse spectrofluorimeter with a microplate reader accessory was used to obtain emission spectra upon excitation at different wavelength for each fluorophore. Typically, we excited samples at 320 and 360 nm. The emission range was 400 to 800 nm, and both the excitation and emission slits were set at 10 nm.Complexity of choosing most efficient fluorophore is related with multidimensionality of initial data . To simplify the task, a dimension reduction method is applied to each dataset . After this each data set can be represented by a set of points on a plane (each point is corresponded one measurement) and the task might be reduced to assessment of relative position of groups of points (which corresponded one type of samples). Besides, we have proposed to use special indexes, as described below.0)/I0, where I0 is the average emission intensity of the blank at the corresponding wavelength. Before application of each statistical method, the data were decomposed into two principal components.The raw spectral data were normalized, which involved the calculation of the formal degree of quenching (Q) as (I − Ihttps://www.camo.com/unscrambler). Typically, two PCs were sufficient to reach a residual dispersion of ≤5%. The result was visualized as the scores plot (PC1 vs. PC2) constructed using Origin 8.1 spreadsheet . Each experiment (an emission spectrum of a well) yielded one point in the scores plot. Different points belonging to the same sample were similarly shaped and colored in the Figures.In the data matrix for each of the 36 studied honeys  and 6 blanks, each row contained 301 intensities corresponding to wavelengths of the spectrum. The data matrix was centered and subjected to PCA using the Unscrambler X  value equal to 4, which corresponded to visual non-intersection of the ellipses. The DM were calculated using the R language-based software.Confidence ellipses for each individual honey were constructed according to the Student’s distribution using the results of the five parallel measurements with a confidence level of 80% and plotted on the scores plots. The criterion for the separation of two honey samples was Mahalanobis distance . The samples were considered separated if their confidence ellipses did not intersect.Another technique involves manual counting the number of intersections of the confidence ellipses. We considered the number of such intersections as a measure of discrimination performance. The ellipses may intersect in a number of ways, for which the crossing numbers were postulated . If one Let us consider two classes each of which is characterized by its center and boundary. Above we described the data set by an ellipse covering 95% of samples; in practical situations, when the distribution law is unknown, we suggest using the simplest method of constructing the border: a convex polygon built on the boundary points of the group. For illustration , we use RP parameter is calculated using four key points: the center of the first group C1; the center of the second group C2; point D1, characterizing the first group scattering with respect to the location of the second group; point D2, characterizing the second group scattering relatively the location of the first group .The ratio of the lengths of the segments C1D2 to C1D1 has the following property: In case of separation of groups, this ratio exceeds unity; in the case of intersection it is less than unity. In order to take into account the case of group merging b, the vaPoints C1 and C2 are calculated by taking the average value; points D1 and D2 are selected from the following conditions: vector C1D1 is the projection of vector C1A1 onto C1C2, where A1 is the boundary point of the first class with the smallest projection of C2A1 onto C2C1. D2 point is chosen similarly with respect to the second class. To assess the relative position of the first group relative to the second, it is proposed to use the following RP value (formula 1):12 value is greater than 1. The larger is RP, the further the groups are located. In case of intersection, the RP value will be more than 0, but less than 1. A value less than 0 corresponds to the case of merging groups. This representation is intuitive and easy to use.In case of separation of groups, the RP12 and RP21.If the groups have a different level of significance, then the RP value can be calculated for the most significant group. If the groups have the same significance level, then use the smallest value from RPIn an ideal case, when the boundaries of the groups set the boundary to only uniformly located points, the case of merger differs from the intersection by the number of points lying inside the intersection region. In case for crossing, the number of such points is greater than zero, but (approximately) less than half of the class volume. When the classes merge, more than approximately half of the points lie in the intersection area.To extend the measure to N groups, the measure value for each pair of groups can be calculated and the average value taken (Formula 2):Validity index, or total sensitivity, was calculated as number of correctly identified samples from the training dataset  divided by the number of all samples [ samples . The croDiscriminant analysis (DA) and support vector machine (SVM) methods. Linear discriminant analysis (LDA), as the name suggests, produces a linear decision boundary between two classes. In this paper, the distance from the center of the groups is calculated using the Mahalanobis distance (LDA-Mah). This metric is only valid if the two classes have similar variance–covariance matrices, otherwise the pooled covariance matrix would be inaccurate. Quadratic discriminant analysis (QDA) is another distance metric similar to the LDA; however, the distance to each class is calculated using the sample variance–covariance matrix of each class. The boundary produced by QDA is a quadratic curve, which may consist of two separate sections of boundary lines [ry lines . SVM is ry lines . In thisWe studied 36 samples of honey, purchased from local supermarkets or from apiary farmers. The samples had different consistency and color, supposing different spectral features. The fluorescence spectra of all samples are shown in 32+ [The method of “fluorescent eye” is based on the interaction of fluorophores with the components of the samples. Previously, we studied a number of fluorophores in this method and found those showing favorable results include metal complexes: 8-Ox-Zn and Ru(bpy)32+ . In this32+ . Moreovewhole emission spectrum, the best discrimination in terms of the number of discriminated groups was achieved by only adding DNA without the dye to the honey  classes a. The di classes b.32+ were studied in Camag visualizer, and the resulting images were treated to obtain the scores plots es plots . The numIn this study we tried to reach most complete discrimination of individual samples by adding fluorophores. When using that strategy, it is desirable to have a method of comparing fluorophores by their efficiency of discrimination. This is a challenging task when not all samples are discriminated. We counted the groups of points in the scores plots whose confidence ellipses did not intersect  to obtaiAs can be seen from the above, it is complicated to assess the discrimination performance when the samples are not well separated, or only a part of the samples forms individual classes. In an attempt to overcome these difficulties, we have suggested two characteristics of discrimination performance.overlap areas of the confidence ellipses, but such calculations would require sophisticated programming work. Another parameter is relative position (RP) of groups (The first one is based on counting the crossing number (CrN) of the confidence ellipses over the entire scores plot . Lesser f groups . Higher Total sensitivity (TS). This metric shows whether the point belongs to a given class and may serve as a measure of the classification performance. Having calculated the distances between each vector and each class, each sample was either assigned to a single class, marked as belonging to multiple classes or left unowned. A point was considered belonging to a class if the Mahalanobis distance DM from the point to the class was less than or equal to 4. Based on that information, TS values by Mahalanobis distance were calculated  is only applicable to classes with similar-looking covariance matrices; therefore, we used the discriminant analysis methods applicable for independent covariance matrix estimation: quadratic discriminant analysis (QDA) and LDA-Mah, based on the calculation of the Mahalanobis distances between classes. The support-vector machine (SVM) method is widely used to classify objects with different predefined algorithms; we used linear, 3rd degree polynomial, and radial basis function [function . DiscrimAdding fluorophores to samples proved to be an efficient way of improving the discrimination performance using fluorescent fingerprinting when the samples are not intensely fluorescent or are not well discriminated by their intrinsic fluorescence ,20,21,2232+ takes the top positions among other fluorophores, judging by CrN and RP parameters , the number of groups, and many variants of TS ts of TS . Next ef32+.To account for all metrics and compare the fluorophores quantitatively, we calculated the overall rating of fluorophores. To obtain the rating value, the individual places of fluorophores with respect to all metrics were summed up . The besr = 0.87) and RP (r = 0.89). Other metrics show a lower correlation with CrN and RP (r = 0.5–0.7). On the whole, all considered metrics show moderate correlation with each other, which implies that the best way of choosing the most efficient discrimination should involve using the greatest possible number of metrics. The proposed parameters CrN and RP have shown their efficiency and require further evaluation when assessing the discrimination performance.It is also useful to know how the calculated parameters relate to each other. As can be seen from tris- dichlororuthenium(II)) as the most efficient. However, the classification model developed in this study for the honey samples was only used to demonstrate the feasibility of using the suggested CrN and RP parameters for the evaluation of the discrimination efficiency. Correlation coefficients between the metrics confirmed that they are essentially independent and can be used together or in combination with standard metrics .Intrinsic fluorescence of 36 honey samples did not allow for their complete discrimination using PCA. Adding various fluorophores to these samples seemingly improved the discrimination; however, a quantitative assessment of the discrimination performance was needed. The task was complicated by the incomplete separation of classes. We used multiple metrics for evaluation of the discrimination performance, including standard ones  and the parameters suggested in this study . Those allowed for choosing one of the fluorophores (


This NTP system generates a high-voltage discharge that not only responds to the ion chemical reaction to eliminate NOx and CO, but that also generates a combustion reaction at the local high temperature of plasma to reduce HC. The NTP system was designed on both the front and rear of the exhaust pipe to analyze the difference of different exhaust flow rates under the specified frequency. The results indicate that the NTP system can greatly reduce toxic contaminants. The NTP reactor placed in the front of exhaust pipe gave HC and CO removal efficiency of about 34.5% and 16.0%, respectively, while the NTP reactor placed in the rear of exhaust pipe gave NOx removal efficiency of about 41.3%. In addition, the voltage and material directly affect the exhaust gases obviously. In conclusion, the proposed NTP system installed in the exhaust system can significantly reduce air pollutants. These results suggest that applying NTP to the combustion engine should be a useful tool to simultaneously reduce both emissions of NOx and CO.Industries’ air pollution causes serious challenges to modern society, among them exhaust gases from internal combustion engines, which are currently one of the main sources. This study proposes a non-thermal plasma (NTP) system for placement in the exhaust system of internal combustion engines to reduce the toxic contaminants (HC, CO, and NO In addition, when methanol and ethanol were used in the combustion engine, the emissions of NOx, CO, and HC were reduced by 49% and 47.6%, 22.6% and 21.25%, and 21.6% and 19.13%, respectively on is the exhaust emission value with the NTP system.The conversion efficiency of pollutants (CE) for CO2, NOx, SO2, and PM2.5, etc. But the instrument used in this article can only measure HC, CO, CO2, and NOx. Therefore, the major reactions in the exhaust gas reduction by the NTP reactor are listed below [The spark is generated by the electrode gap of the NTP reactor. . The comed below ,21,22,23x generation.The short high current spark with excited atomic radicals, excited molecules, and ions are generated, and the temperature during the spark phase can be as high as 3000 K. Therefore, we considered the Zeldovich thermal mechanism (see the equations below) of NOOxygen molecules are broken down into oxygen radicals by the free electrons. The reactions of these oxygen molecules are listed below ,21,22,232 transforms into N radicals and the water molecules partially dissociate to form active species, such as OH and H radicals. The results of H2O and N2 molecules at higher energy electron collision reactions are listed below [Under a higher energy electron collision, Ned below ,23.(10)2 in a non-thermal plasma involves the electron-induced dissociation of CO2 to give CO and O followed by recombination of the oxygen atoms to give the final products, CO and O2. CO can also recombine with atomic oxygen to reform CO2. The reactions are listed below [The mechanism for the destruction of COed below ,20.(17)x removal mainly occurs through the oxidation pathway. Once N and O radicals are formed, the most important reactions of the oxidation of NO to NO2 are listed below [The process of NOed below ,22,23. at 4000 rpm and for reactor in the front of the exhaust system (model A). The results show that CO2 conversion efficiency increases with decreasing voltage. This is because decreasing voltage leads to a smaller shape of spark and this reduction causes a decline in the production of free radicals. Ultimately, this reduces the dissociation probability of CO2 exhaust gas.2 emission value and conversion efficiency at control voltage 5 V using different materials and at various locations of the NTP reactor. 2 conversion efficiency at control voltage 5 V using different materials and at various locations of the NTP reactor. The maximum CO2 conversion efficiency was 0.6% for platinum (type one) at 4000 rpm and for reactor in the front of the exhaust system (model A). The minimum CO2 conversion efficiency was −0.3% for iridium alloy (type two) at 4000 rpm and for reactor in the rear of the exhaust system (model B). Most of the NTP reactor materials of type one and type two increase CO2 exhaust gas concentration, while the type one exhibits a better effect than the type two. The reduced production of free radicals causes the dissociation probability of CO2 exhaust gas to decrease. CO2 is also obtained from the combination of CO and oxygen atoms. The dissociation of CO2 is divided into two parts. The first part involves the dissociation of CO2 to give CO and oxygen atoms. In the second part, the dissociation of CO2 gives carbon and oxygen atoms. Carbon atoms get deposited on the surface of the NTP reactor  at 3000 rpm and for reactor in the front of the exhaust system (model A). The minimum NOx removal efficiency was 4.7% at the control voltage 2 V for platinum (type one) at 6000 rpm and for reactor in the rear of the exhaust system (model B). The results show that NOx removal efficiency increased with increasing voltage, however, NOx removal efficiency began decreasing after reaching control voltage 4 V. This is because the change in the spark of control voltage 5 V to the control voltage 4 V was small. The free radicals and exhaust gas degradation appeared to be similar, but the combustion reaction temperature increased. With the increase in combustion reaction temperature, the amount of diatomic nitrogen dissociated from the monatomic nitrogen increased and finally resulted in high NOx.x emission value and removal efficiency at control voltage 5 V using different materials and at various locations of the NTP reactor. x removal efficiency at control voltage 5 V using different materials and at various locations of the NTP reactor. The maximum NOx removal efficiency was 37.6% for iridium alloy (type two) at 4000 rpm and for reactor in the front of the exhaust system (model A). The minimum NOx removal efficiency was 7.5% for platinum (type one) at 6000 rpm and for reactor in the rear of the exhaust system (model B). The results show an increase in NOx exhaust gas concentration with an increase in engine speed, which then causes the temperature of the combustion chamber to increase. At high temperatures, nitrogen and oxygen atoms easily recombine to form NOx. The NTP reactor materials of type one and type two reduce the NOx exhaust gas concentration. The effect of type two material was found to be better than type one. The production of free radicals increased by increasing the spark size and the area of contact between the free radicals and NOx exhaust gas also increased. This enhanced the probability of dissociation of NOx exhaust gas to give nitrogen and oxygen atoms. The NTP reactor location in models A and B reduced the NOx exhaust gas concentration. Moreover, the NOx removal efficiency increased with decreasing engine speed because of the slower the flow rate of exhaust gas and the lower temperature of exhaust gas. The NOx removal efficiency of model A was better among the two models because the products of NOx dissociation can easily recombine to form the NOx at high temperatures. The combination possibility of nitrogen and oxygen atoms is lower at the faster flow rate of the exhaust gas. Therefore, the NOx exhaust gas emissions are reduced.In this study, a motorcycle engine was examined using the NTP system to measure exhaust gas emission using different materials, voltage, and locations of the NTP reactor.Considering the HC exhaust gas emissions, the NTP system re-burns HC exhaust gas to reduce the HC exhaust gas concentration. The HC removal efficiency increases with increasing voltage. The shapes and density of the spark approached critical values at the control voltage 4 V. The HC exhaust gas emissions of model B were lower than model A. The effect of type two NTP reactor material was better than that of type one. The maximum reduction of HC removal efficiency obtained with the NTP system reached 34.5%, while the minimum HC removal efficiency was 1.2%.2. The CO removal efficiency increases with the increase in voltage. The CO removal efficiency of model B was found to be higher than that of model A. The effect of the type two NTP reactor material was better than type one. The maximum reduction of CO removal efficiency obtained with the NTP system reached 16.0%, while the minimum CO removal efficiency was 1.2%.Considering the CO exhaust gas emissions, the reaction between free radicals and CO exhaust gas gates mainly dissociated to obtain carbon and oxygen atoms. Carbon gets deposited on the surface of the NTP reactor and affects the life of the NTP reactor. Furthermore, CO and oxygen atoms also recombine to form CO2 exhaust gas emissions, the CO2 exhaust gas dissociates to form CO and oxygen atoms, and the dissociation of CO2 obtains carbon atoms and oxygen atoms. Like CO, carbon gets deposited on the surface of the NTP reactor. However, most of the amount of dissociation was found to be less than the amount of HC re-burning and CO reduction. Therefore, the total amount of CO2 increased and the CO2 conversion efficiency increased with decreasing voltage. The CO2 conversion efficiency of model A was higher than that of model B. The effect of type one NTP reactor material was better than that of type two. The maximum CO2 conversion efficiency obtained with the NTP system reached 0.9%, while the minimum CO2 conversion efficiency was −0.3%.In terms of the COx exhaust gas emissions, the NOx gets dissociated by the NTP system to reduce the NOx exhaust gas concentration. The removal efficiency NOx increased with increasing voltage, but the NOx exhaust gas removal efficiency began to decrease after reaching control voltage 4 V. As the combustion reaction temperature increased, the amount of diatomic nitrogen dissociated from the monatomic nitrogen increased and finally resulted in high NOx. The NOx exhaust gas emissions of model A were lower than that of model B. The effect of type two NTP reactor material was better than that of type one. The maximum reduction of NOx exhaust gas emissions removal efficiency obtained with the NTP system reached 41.3%, while the minimum NOx removal efficiency was 4.7%.Considering the NO2, and NOx emission removal. The effect of the NTP reactor in the rear of the exhaust system is better than in the front of the exhaust system for HC, CO, and CO2 emission removal. However, the NOx emission removal for the reactor in front of the exhaust system is better than that in the rear of the exhaust system.Finally, according to the above discussion, the effect of iridium alloy is better than platinum for HC, CO, COTaiwan Patent M526623.