It is well known that the DCM patients having Late Gadolinium Enhancement at Mid-layer of LV septal wall (Mid-LGE) shows poor prognosis compared to the case not having Mid-LGEHowever, about the other histopathological differences by the existence of Mid-LGE, it is not clear.On the other hand, in recent years, it became possible to calculate ECV from measurement of T1 value of the myocardium before and after of enhanced imaging which used the Modified Look-Locker Inversion Recovery(MOLLI) method, and the usefulness in the quantitative evaluation of histopathological changes, such as diffuse fibrosis observed in hypertrophic cardiomyopathy, has been reported.We will study about the difference of extra cellular volume(ECV) calculated with T1mapping in DCM with and without LGETwenty-one cases diagnosed as DCM by cardiac MRI and eleven normal controls from October, 2012 to December, 2013 were examined.T1 value of each area of midventricular slice and blood pool in the left ventricle was measured for every case, and T1 value of a septum area, areas other than a septum, and all the sections were computed.In measurement of T1 value, MOLLI 8-2 supported by Siemens, Erlangen, Germany was used.ECV was computed from T1 value and hematocrit value of each area on before and after enhancement, and were taken as the median value of each measured value of a septum area, areas other than a septum, and all the sections were calculated.1) DCM was divided into LGE (+) group ;10 cases and DCM LGE(-) ;11 cases in the visual assessment of the LGE CMR imaging.2) Between two DCM groups with and without LGE, age, a hematocrit, EF and other cardiac parameters, significant differences were not recognized.3) Native T1 value of the LGE(+) group was intentionally high only in the septal area as compared with LGE(-) group and normal group.Native T1 Value of areas other than a septum and a total section, there was no significant difference between 3 groups.4) The median value of ECV in total slice of LGE (+) group was significantly higher than that of LGE(-) group and the normal group. The median value of ECV of LGE (+) was higher than that of LGE(-) group and normal group even in the areas other than a septum.The median value of ECV of LGE(+) group was higher than that of LGE(-) group even in the areas other than a septum not showing LGE. Calculation of ECV by T1mapping may be used for evaluation of the stage of illness with DCM.None.


In Romania, health and social workers were prioritized for COVID-19 vaccination. We aimed to describe the vaccine adverse events identified through an active survey (using an electronic questionnaire) conducted among the staff of a pediatric hospital from Bucharest, vaccinated with the mRNA Pfizer-BioNTech vaccine. Data on the frequency and duration of adverse events were collected and analyzed using Microsoft Excel, Epi Info, and MedCalc. The questionnaire was sent to 426 persons. The participation rate was 81.2% after 1st dose and 63.8% after the 2nd dose. Overall, 81.9% were women, median age 42 (IQR 32–50 years). A total of 48 respondents (14.8%) reported no adverse event after the 1st dose and 35 (14.1) after the 2nd dose. No anaphylaxis was reported. The most frequent adverse event was pain at injection site, being reported by 261 responders (80.3%) after 1st dose and 187 (75.1%) after 2nd dose. Fatigue and headache were reported significantly less frequently in our study compared with data provided by the vaccine manufacturer. The current study has shown higher local reactogenicity after the first dose of the vaccine and higher systemic reactogenicity after the second dose. This real-world knowledge of the reactogenicity and safety profile may increase the vaccine’s acceptance rate among healthcare workers. The COVID-19 pandemic is one of the most significant challenges of the 21st century because of its morbidity, mortality, and significant economic and social impact.Since the beginning of the pandemic, the efforts of physicians, researchers, pharmaceutical companies and regulatory agencies have focused on fast development and approval of safe and efficient vaccines. Thus, in December 2020, one year after the identification of the first cases of pneumonia of unknown etiology in Wuhan, China, the first vaccine against COVID-19 was granted conditional marketing authorization by the European Medicines Agency. This mRNA-based vaccine produced by Pfizer-BioNTech New York, United States of America, was initially approved by the US Food and Drug Administration. Shortly afterwards, other vaccines against COVID-19 also received approval .The availability and access to COVID-19 vaccines were limited in the initial phases of the vaccination campaign, due to the insufficient production capacity and due to the very high demand. For this reason, the World Health Organization (WHO) and the European Centre for Disease Control and Prevention (ECDC) issued a series of recommendations in order to prioritize vaccination for certain risk groups. Thus, in Romania, as in other European countries, the vaccination was implemented in phases  ,5,6,7. The COVID-19 vaccination campaign started in Romania on 27 December 2020, medical staff being the first category planned for vaccination. The vaccination process took place in the initial phases only in dedicated vaccination centers, and the vaccination was based on appointment ,7. The fAscertaining the real time status of administered vaccinations and of vaccine adverse events is extremely useful for the proper implementation of any vaccination campaign or program, guiding each decision of the public health authorities ,7,9.Vaccine hesitancy is one of the main issues that public health authorities have faced, being the main cause of low vaccination coverage and the driver of epidemics of vaccine-preventable diseases. There is a general hesitancy in using a new vaccine, a vaccine which people consider that insufficient information exists in terms of safety and efficacy ,10.According to the Centre for Diseases Control, one of the most efficient methods through which the authorities can improve the confidence of the population in a vaccine is the transparent communication of information concerning its safety and efficacy . In Romania adverse events following vaccination are passively recorded according to a surveillance methodology through filling-in the reporting form and an event investigation report (only for serious adverse events) to the National Centre for Surveillance and Control of Communicable Diseases. Furthermore, the pharmacovigilance system managed by the National Agency for Medicines might be used. Furthermore, there is a protocol for collaboration and exchange of information between the institutions supervising undesirable vaccine adverse events ,12,13. We aimed to describe the adverse events following COVID-19 immunization identified through an active survey conducted among healthcare workers of a Bucharest pediatric hospital, vaccinated during the first phase of the national vaccination campaign in Romania. An active survey of vaccine adverse events was performed in January and February 2021 and involved the hospital staff vaccinated against COVID-19 with the mRNA Pfizer-BioNTech vaccine with two doses of vaccine, 21 days apart. The two doses (1st and 2nd) were identical, 0.3 mL (30 mcg), as recommended by the vaccine manufacturer, and were administered in the same vaccination center.The appointment for vaccination was organized by the hospital, through the online platform of the Ministry of Health, based on the lists of the staff having opted for vaccination. A specifically designed Google Forms questionnaire was sent by the Hospital Department of Infections Control together with the invitation to the survey to all the persons appointed to be vaccinated with their first doses in January. The contact details  for the vaccination appointment list were used. The questionnaire was sent once for both doses at the beginning of the vaccination campaign.The participants were asked to answer the questionnaire regarding the adverse events noticed in the first 3 days after the administration of each vaccine dose, without specifying a due date for submission. The time required for filling the questionnaire was estimated to be about 2 min.The adverse events listed in the questionnaire were those of vaccine leaflet . AdditioThe survey protocol was approved by the Hospital Ethics Commission, with the registration number 1176/15 January 2021.The adverse events data were collected on behalf of the hospital in a database managed by the Department of Infections Control, apart from the national database for adverse events ,13. For The vaccination started on 4 January 2021. The questionnaire was sent to 426 persons scheduled for vaccination during January–February. During the study period (18 January–25 February), 656 answers were collected .The participation rate, calculated after having eliminated only duplicates, was 81.2% for the 1st dose and 63.8% for the 2nd dose.The group of participants consisted mainly of women (81.9%), both for 1st dose (80.9%), and for 2nd dose (83.1%), corresponding to the gender structure of the hospital staff.The median age was 42 (IQR 32–50 years); for the 1st dose the median age was 42 (IQR 31–49 years) and for the 2nd dose the median age was 43 (IQR 33–50 years). For comparison with the data of the vaccine manufacturer , the parThe median interval from vaccination and response was 8 days (IQR 5–14 days); for the 1st dose this was 9 days (IQR 5–15 days) and for the 2nd dose it was 7 days (IQR 4–13 days).The analysis of vaccine adverse events was based on the valid questionnaires for each specific vaccine dose. Overall, 48 participants (14.8%) for the 1st dose and 35 participants (14.1%) for the 2nd dose did not report any vaccine adverse event. For the 2nd dose, 164 participants (65.9%) reported more than one adverse event, a statistically significant higher value than those for the 1st dose, 121 participants (37.2%).The most frequent local adverse event was pain at the injection site, reported by 261 participants (80.3%) for the 1st dose and 187 participants (75.1%) after the 2nd dose. Redness was reported by 17 participants (5.2%) for the 1st dose and 13 participants (4.8%) after the 2nd dose. Swelling was reported by 26 participants (8.0%) for the 1st dose and 20 participants (5.6%) after the 2nd dose. There was no statistically significant difference between the frequency of the local adverse events reported for the 1st dose and for the 2nd dose.The most frequent systemic adverse events were fatigue, reported by 60 participants (18.5%) for the 1st dose and 114 participants (45.8%) for the 2nd dose, headache, reported by 56 participants (17.2%) for the 1st dose and 85 participants (34.1%) for the 2nd dose, respectively, and muscle pain, reported by 39 participants (12.0%) for the 1st dose and 80 participants (32.1%) for the 2nd dose. The digestive symptoms were extremely rare . A statistically significant higher frequency of systemic adverse effects after the 2nd dose was observed for most adverse events: fever, fatigue, headache, chills, nausea, muscle pain, joint pain, insomnia, and lymphadenopathy .No anaphylactic reaction was reported by any participant.The data obtained based on the survey for the 18–55 years age group were compared to those of the vaccine manufacturer for each dose . The oveComparing our results with the vaccine manufacturer data, there were no statistically significant differences with respect to the frequency of the local adverse events reported for both the 1st dose and the 2nd dose . Regarding the frequency of the systemic adverse events, in the surveyed group a significantly lower frequency was observed for fever, headache, fatigue, chills, and myalgia after the 1st dose . For theAn extremely small number of participants  reported having required medical examination and treatment following the adverse events (2 after the 1st dose and 3 after the 2nd dose). A case of brachial paresis was reported after the 2nd dose. The paresis fully recovered under non-steroidal anti-inflammatory and cortisone treatment.Knowing the real-world incidence of vaccine adverse events is essential for a proper implementation of a vaccination campaign. Knowing and transparently communicating the information concerning the reactogenicity of a vaccine can increase the confidence in vaccines, which is particularly important for a newly-introduced vaccine . A good Although the need to know the real frequency of COVID-19 vaccine adverse events is high, the implementation of an active surveillance system concerning vaccine adverse events is difficult, due to the specific constraints, high cost, and higher human resources requirements.Within the survey, our aim was to actively observe the real-world rate of occurrence of vaccine adverse events among the healthcare workers vaccinated during the first COVID-19 vaccination phase in the country.During the survey, the Department of Infections Control provided feedback to the staff about the survey participation, with regards to the reported adverse events, through daily staff meetings. To avoid the risk of influencing future answers to the questionnaire, only general information was provided. Open communication was considered essential for the staff and a factor driving the vaccination rate increase.The frequency of systemic adverse events was lower among our respondents when compared with those reported by the vaccine manufacturer, but in line with other studies  ,19,20.This study has a set of limitations. First, a certain degree of recall bias cannot be excluded, although the timespan from vaccination to survey completion  was generally short enough to ensure reliability of the recalled data. Second, our study is limited by the fact that the questionnaire was not reapplied in September 2021, when the vaccine booster dose started to be administered, and thus we were unable to assess the reactogenicity of the 3rd vaccine dose. This was not possible due to the overall low uptake of the booster dose in Romania (8.8% according to the data reported to the European Centre for Disease Control on 7 April 2022) [The strengths of this survey include the high quality of the data, the healthcare workers being able to recognize and describe the symptoms observed easily and precisely. At the same time, the data were collected immediately after the start of the vaccination campaign using a new vaccine, obtained through a novel technology, and the concern of the healthcare workers in terms of reactogenicity has been important, as indicated by the high rate of participation (over 80%) for the 1st dose. The lower response rate for the 2nd dose can be explained by a drop of interest, as well as by the long-time interval between the receipt of the questionnaire and the moment of vaccination (the questionnaire was sent only once for both doses). The 3-day interval for the observation of the adverse events was chosen based on the observation in the survey of the vaccine manufacturer, which showed that most systemic adverse events were reported (both for the 1st dose and for the 2nd dose) in the first two days after vaccination, and persisted for one more day.The high share of women in the surveyed group reflects the gender distribution among the hospital staff. The results reported in the survey refer to the adult population .The active surveillance study has shown the highest frequency of the adverse events for pain at the injection site. Fatigue and headache followed, but at a much lower level. The digestive symptoms were extremely rare.There was no difference between the frequency of the local adverse events reported for the 1st dose and the 2nd dose. A higher frequency of systemic adverse events after the 2nd dose was observed for most reactions: fever, fatigue, headache, chills, nausea, muscle pain, joint pain, insomnia, and lymphadenopathy. There were no anaphylactic reactions or other severe adverse events requiring hospitalization or causing after-effects or invalidity.The reactogenicity among the healthcare workers was similar to that specified in the summary of the product characteristics in the same age group for local adverse events. For some systemic adverse events it was lower, for both doses. The higher systemic adverse events frequency after the administration of the 2nd dose is consistent with the vaccine manufacturer data. The active surveillance provides useful information concerning the post-authorization safety of the vaccines administered in real-world settings.The data collection through the online questionnaire method allowed real-time monitoring of the vaccine adverse events. This method of online questionnaire was brief and straightforward for the responders, particularly important when surveying healthcare workers during the COVID-19 pandemic, leading to a good uptake.


Baricitinib is a treatment authorized by the FDA for the treatment of moderate to severe COVID-19, despite this there are few approved drugs; polymerized type I collagen (PTIC) is a drug that has been used in Mexico with great potential for treating moderate to severe cases of COVID-19.Comparative, descriptive and retrospective analysis of two populations of adult patients affected by COVID-19 confirmed by antigen test or RT-PCR as well as CO-RADS 6 CT, who consented to be treated between 2020 and 2021, a population using oral baricitinib at a dose of 4mg/day/14 days and another using polymerized type I collagen intramuscularly at a dose of 1.5ml every 12 hours for 3 days, followed by 1.5ml every 24 hours for 4 days; The most affected age and gender, comorbidities and laboratory abnormalities are analyzed, as well as improvement in inflammatory and oxygenation indices measured by pulse oximetry and SAFI (SpO2/FiO2), finally the outcome of the patients and the presence of adverse events.80 patients for each group, the most affected gender was male; the average age in the PTIC group was 51 years and in the baricitinib group it was 56 years; the main comorbidities were obesity, diabetes and hypertension in both groups; the decrease in acute phase reactants such as CRP, D-dimer and ferritin was greater in the PTIC group compared to the baricitinib group, the latter drug requiring a regimen of more days to achieve the objectives of the first drug (PTIC 7 days and baricitinib 14 days); Similarly, in oxygenation measured, the PTIC group reached goals in less time compared to the baricitinib group, which required twice as many days of treatment to achieve adequate oxygenation; Regarding the outcomes, there was a higher mortality in the baricitinib group compared to the PTIC group (6.25% vs 3.75%). Regarding adverse events reported for the PTIC group, they were minor and related to the intramuscular administration of the drug in 7 patients, while in the baricitinib group, 5 patients were reported with added bacterial pneumonia.Polymerized type I collagen has anti-inflammatory and immunomodulatory potential similar to baricitinib in cases of moderate to severe COVID-19, even reaching treatment goals in less time both in inflammatory indices and in oxygenation indices.All Authors: No reported disclosures.


Long latency auditory evoked potentials (LLAEP) alterations in individuals with tinnitus are suggestive of dysfunction in the central auditory pathways at a cortical level.to characterize the LLAEP in individuals with and without tinnitus exposed to occupational noise.Cross-sectional contemporary cohort, prospective study. Sixty subjects exposed to occupational noise, ranging in age from 29 to 50 years underwent LLAEP assessment; 30 of them had tinnitus complaint and 30 did not have tinnitus.we observed significant statistical difference regarding the mean values of latencies of waves N1 (p<0.001), P2 (p=0.002) and P300 (p=0.039) when we compared individuals with and without tinnitus. In individuals with tinnitus we also noticed a greater number of altered results concerning components N1 (60%) and P2 (66.7%), although only component P2 presented significant statistical difference (p=0.010). For the LLAEP, the latency increase was the only type of alteration found (p=1.000). We found a greater association between bilateral tinnitus and bilateral alteration for all components N1(73%), P2(73%) and P300(50%).It is relevant to study LLAEP in individuals with tinnitus exposed to high occupational sound pressure levels. Some people experience a sound sensation which is not related to any external source of stimulation or noise. This auditory phenomenon, defined by the hearing of sounds on one or on both ears, as well as in one's head is known as tinnitus.Usually, these people perceive tinnitus so strongly that they have impairments in their quality of life, which could impact their work, sleep and communication. Often times, tinnitus exceeds the person's tolerance and adaptive capacity, which may cause physical, mental and/or emotional exhaustion.Tinnitus is being discussed in writings since the ancient Egyptian civilization. Although present in the lives of people for almost five thousand years, this complaint, especially subjective, remains obscure in many of its aspects, especially regarding its originIn an attempt to explain some of the aspects associated with this phenomenon, many authors have raised hypothesis on the possible causes for it. Until the early 80′s, it was believed that tinnitus was a phenomenon which would happen in the cochlea only. Later studies showed that such symptom may involve not only the cochlea, but also the auditory pathways and the cerebral cortex.HazellAiming at studying the CNS participation in tinnitus in individuals with and without this symptom, Attias et al. (1993),Another theory which can be considered to explain the mechanism responsible for the development of tinnitus is habituation, which is defined as a process of adaptation in the CNS which reduces or eliminates the perception of a stimulus introduced continuously and repeatedly. Thus, authors have suggested that individuals with frequent negative associations with tinnitus reinforce this perception and, as a consequence, do not get used to tinnitus, thus becoming chronic cases. Consequently, the high emotional background of severe tinnitus could lead to a high level of selective attention guided towards tinnitus, which could increase the lack of attention and/or prevent habituation from this symptom. Studies have reported that an attention-filled process can be involved in the delay or prevention of a habituation mechanism,,The specialized literature shows that alterations in the central auditory tests and electrophysiological abnormalities in the Long Latency Auditory Evoked Potential (LLAEP) Therefore, the goals of the present study were to characterize the results from long latency auditory evoked potentials (LLAEP), comparing the results obtained from these potentials from individuals with and without tinnitus, and to check the existence of association between the side with LLAEP alteration and the tinnitus location in individuals complaining of tinnitus exposed to high sound pressure levels in their jobs.The present study was designed as a contemporary cross-sectional cohort, done in the Laboratory of Speech and Hearing Investigations in Auditory Evoked Potentials at the Speech and Hearing Therapy program of the Medical School of the University of São Paulo (FMUSP), approved by the Ethics Committee of the University of São Paulo Hospital, as well as by the Ethics Committee for Research Projects Analysis of the University of São Paulo Medical School Hospital - CAPPesq, under protocols # 712/06 and # 1278/06, respectively.Such research protocols were based on Resolutions 196/96 and 251/97, from the National Health Board and Department of Health (CNS/MS), and the Free and Informed Consent Form had to be signed by the patient, consenting with the tests and use of the information obtained by the investigator. The material collected was stored in the institution's database.The procedures were carried out only after the individuals signed the Free and Informed Consent Form.The material from the present study was based on the results from the basic audiological evaluation and the Long Latency Auditory Evoked Potentials  from 60 individuals exposed to occupational noise with high sound pressure levels (higher than 85 dBH), both from males and females, in the age range between 27 and 50 years of age, 30 with tinnitus (study group) and 30 without tinnitus (control group).The selection of individuals complied with the following inclusion criteria: constant or intermittent tinnitus, uni or bilateral ; exposure to occupational noise with high sound pressure levels (higher than 85 dBH), and the noise level measurement was carried out by the Hygiene Division of Work Safety and Medicine Department of the University of São Paulo ((DHSMT USP); auditory thresholds within normal levels, in other words, lower than or equal to 25 dBHL in all the frequencies (0.25 kHz to 8 kHz) in both ears; Speech Recognition Threshold (SRT) equal to or up to 10 dB HL above the tritone average We took off the study those individuals complaining of neurological, psychiatric and behavioral dysfunctions, and this data was obtained during the medical interview and the medical chart of the worker.In order to select the subject to participate in the study, meeting the previously established inclusion criteria, we carried out the following procedures: interview; a questionnaire about tinnitus characteristicsAfter audiological evaluation, the selected individuals were submitted to electrophysiological evaluation of hearing (LLAEP) in order to obtain the latencies from components N1, P2, Cognitive Potential (P300) and N1-P2 latency. The individuals were placed in a reclining chair, in a poorly lighted room and were instructed to keep their eyes closed during the test, however being alert so as to perform the required cognitive activities. In order to carry out with this evaluation, we used the Traveler Express portable system from Bio-Logic, with the EP317 softwareAll the tests were carried out in the morning, before the individual went to work, thus preventing the individual from being tired at the time of the test and guaranteeing that he/she would keep the same attention during LLAEP recording.The results from the latency of components N1, P2 and P300 were initially classified in normal or altered, according to the normality criteria proposed by Williams et al.In analyzing results from the N1-P2 amplitude we only characterized the values obtained for not having in the literature a normality criterion established for this parameter.The results from the electrophysiological evaluation, both in the study group and in the control group, who did not match the normality criteria aforementioned, were classified as altered. The individual was deemed altered when at least one of the ears or one of sides presented some alteration.The altered latency results found from waves N1, P2 and P300 were classified in: “increase”, as to wave latency, it was increased if compared to the normal values; “absent”, when no wave was found; “both” when increase and absent alterations were found in the same individual.After analyzing the scores assigned to tinnitus severity, the individuals were placed in three subgroups: group 1 - mild tinnitus; group 2 - moderate tinnitus; group 3 -severe tinnitus. Tinnitus severity was analyzed by means of the visual-analogue scale. According with such method, the individual was asked to provide a score from 1 to 10 to his tinnitus, considering that 1 would be mild tinnitus and 10 the worst tinnitus imaginable. The scores were then classified as: from 1 to 3 - mild tinnitus; from 4 to 6 - moderate tinnitus, and from 7 to 10 - severe tinnitus.We used the Wilcoxon, Mann-Whitney, and Equality between two proportions and Chi-Squared tests. The values from the statistical analysis were considered statistically significant when p£0.05 and, all the confidence intervals were built with 95% statistical confidence.In the present study, the study group (SG) and the control group (CG) were made up of 30 individuals each, four women (13.33%) and 26 men (86.67%).The age of the individuals in the study varied between 27 and 50 years with a mean of 41 years, and in the control group it varied between 27 and 50 years, with a mean of 41.6. We did not find statistically significant differences between the groups in relation to the mean age (p = 0.563).Following, we will present the results obtained in relation to the tinnitus localization in the individuals from the study group (n=30). The data was evaluated as to laterality to the right ear (RE), left ear (LE), or both ears (BE). We noticed that of those individuals complaining of tinnitus, 66.7% had bilateral tinnitus, observing a statistically significant difference as to tinnitus location in the left and right ears .Figure 1As far as tinnitus severity in individuals from the study group (n=30), the data was evaluated as to the level of discomfort caused by tinnitus into: mild, moderate and severe. We noticed that 56.7% of the individuals complaining of tinnitus had it in a moderate level, and we can see a statistically significant difference as to the mild (p < 0.001) and severe levels (p = 0.037) .Figure 2The quantitative results obtained from comparing the mean latency values from components N1, P2, P300 (in ms) and the N1-P2 amplitude (in μV) between the right and left ears, in the control and study groups, which are depicted on Later on, we carried out a qualitative analysis of the results obtained from the LLAEP. For each potential we analyzed the occurrence of normal and altered results, as well as the types of alterations found in the study and control groups.We observed statistically significant differences between the study and control groups as to the occurrence of normal and altered results regarding the latencies of components N1, P2 and P300 in LLAEP, respectively . Within The study of the association between the side harboring the alteration in auditory evoked potentials and tinnitus location was carried out in the study group, yielding a deeper association between the side of the N1, P2 and P300 components' alterations and tinnitus location, especially when the tinnitus is bilateral, although we did not see statistically significant differences regarding this association .Table 4AThe long latency auditory evoked potentials (LLAEP), also known as late potentials or event-related potentials, were first studied by Picton et al.In the present study, we analyzed the N1, P2, P300 components from the LLAEP. Wave N1 presents as possible generators the primary auditory cortex , which can be associated to the attention given to the sound stimulus, and secondary auditory cortex Initially, we compared the mean latency values of components N1, P2, P300 and N1-P2 amplitude between the study and control groups. We also noticed that the study group presented higher mean values in all the components assessed when compared to the control group, with statistically significant differences for latencies from waves N1 (p<0.001), P2 (p=0.002) and P300 (p=0.039), except for N1-P2 amplitude (p=0.392) .As it happened in the present study, Jacobson et al.Despite the lack of a significant difference for N1-P2 amplitude in the comparison between the study and control groups , we noti,,,In the literature studied, we found some studies which used different types of LLAEP to assess individuals with tinnitus, and these found latency and/or amplitude alterations in the potentialsIn the quantitative analysis of normal and altered result occurrence distribution regarding N1, P2 and P300 components latency from the LLAEP, in the control and study group, it was noticed that the study group had a higher percentage of altered results  when compared to the control group, which presented 100%, 73.3% and 96.7% of normal results, respectively . When co,The large number of altered results seen in components N1 and P2 in individuals with tinnitus suggest that the presence of alterations in different areas of the primary auditory cortex.Considering the types of alterations present in components N1, P2 and P300 we noticed that the only type of alterations present, for both groups, was the increase in N1, P2 and P 300 component latencies.,These findings corroborate those from Jacobson et al.,,,,Picton (1992)Other possible factors which can be associated to the changes seen in the LLAEP in individuals with tinnitus are: the possibility of reduction in the number of working neurons, reduction in neural activity and/or a greater mismatch of the firings of the involved neuronsVery little is known about the electrophysiological characteristics of individuals with tinnitus, as well as on the interaction of the attention and tinnitus mechanismAccording with Coelho et al.Because of this analysis we notice that the LLAEP alterations seen in individuals with tinnitus show an involvement of the CANS, suggesting a participation of the auditory cortex in the generation and/or tinnitus maintenance. Thus, the LLAEP is a useful tool to investigate the mechanism responsible for this symptom.In studying the association between the altered side of the auditory evoked potentials and tinnitus location, we noticed a greater association between the bilateral tinnitus and the bilateral alteration in N1, P2 and P300 LLAEP components, and the differences were not significant .We did not find in the literature studies associating the side of tinnitus with the side of the LLAEP alteration in individuals with hearing thresholds within normal values, complaining of tinnitus exposed to high sound pressure levels, thus making it difficult to compare the results from the present paper with those from other studies. The fact that this study showed a positive association between tinnitus localization and LLAEP alteration provides clues as to CNAS in the generation of tinnitus.We noticed a greater occurrence of LLAEP alterations in individuals with tinnitus when compared to individuals without tinnitus. The most commonly found type of alteration in this population was the increase in latency values, suggesting the existence of a possible CNAS dysfunction at a cortical level in individuals with tinnitus exposed to occupational noise. We also noticed a greater association between the side of LLAEP N1, P2 and P300 component alteration and the tinnitus localization when the individuals had bilateral tinnitus.


A 3.5 tonne forklift containing proton exchange membrane fuel cells (PEMFCs) and lithium-ion batteries was manufactured and tested in a real factory. The work efficiency and economic applicability of the PEMFC forklift were compared with that of a lithium-ion battery-powered forklift. The results showed that the back-pressure of air was closely related to the power density of the stack, whose stability could be improved by a reasonable control strategy and membrane electrode assemblies (MEAs) with high consistency. The PEMFC powered forklift displayed 40.6% higher work efficiency than the lithium-ion battery-powered forklift. Its lower use-cost compared to internal engine-powered forklifts, is beneficial to the commercialization of this product. The global goal of decarbonization has prompted the exploration of hydrogen energy. Electricity can be generated through renewable energy, however, renewable energy sources are unstable and intermittent during generation which leads to electricity being difficult to apply continuously and stably ,2. To taHowever, lithium-ion batteries and lead-acid batteries also have problems such as short run time, long charging time, and unstable working efficiencies , etc. ByIn addition to cost, the application of PEMFCs in forklifts must contend with diesel internal combustion engines and charging batteries from the perspective of efficiency, stability, and durability . This isLearning from hybrid vehicles (which combine combustion engines and batteries), a good engineering idea that combines PEMFCs and batteries was also proposed, where PEMFCs and batteries behave as complementary partners rather than competitors . The batAs for research about application of PEMFC forklifts, most research focuses on the thermal, fluid modeling simulation calculations and model analyses ,20,21,22In this paper, a PEMFC power system was made based on the Zoomlion FB35Z 3.5 tonne electric counter-balance forklift. To ensure the PEMFC-powered forklift could adapt to different application environments, a homemade liquid-cooled PEMFC stack was integrated into the PEMFC power system that was combined with lithium-ion batteries to test the economic and work efficiencies. The handling capacity and mileage of the PEMFC forklift with a full tank of hydrogen was investigated; the operational cost and cost recovery cycle was also compared to that of a diesel internal engine forklift.2 and air (air stoichiometric ratio: 2.5) were first set at 140 kPa and 130 kPa, respectively. The polarization curve of the stack displayed a typical pattern and reached an output power of 15.8 kW. After decreasing the backpressures of H2 and air to 60 kPa and 50 kPa (air stoichiometric ratio: 1.8), respectively, there was a decrease in stack performance  at 75 °C, with 80% relatively humidity (RH) under different backpressure. The backpressure of Hformance , where tThe schematic of the PEMFC power system is presented in Since the response of the current output is in the microsecond range, air starvation would occur during drastic load fluctuation without a load change prediction, due to hysteresis of the air pump. In order to avoid this, when the FCU received signal to increase the output power, the FCU sent signals to the air pump and valves to responsd in advance, initializing an increase in the output current when the flow of the reactors reaches the demand. The electricity was converted to 80 V by the main DCDC, and was supplied to the motor through a high voltage box and a high voltage management unit. The lithium-ion batteries were charged when the output power of the PEMFC stack was greater than the power consumption of the forklift. In the contrast, the lithium-ion batteries were discharged when the output power of the PEMFC stack was insufficient to thus meet the demand for the instantaneously larger power consumption of the forklift. The PEMFC system stopped working when the SOC of the lithium-ion battery was greater than 90%, wherein the lithium-ion batteries became the main power to drive the motor. The PEMFC system started to work when the SOC of the lithium-ion batteries was less than 30% untill the SOC reached 90%. The main power dissipation of the PEMFC system was the air pump and radiator fan, while that of the water pump and valves was negligible. single cell > 0.6 V) for better energy conversion efficiency. The I-E curve of the PEMFC stack was converted to the polarization curves of a single fuel cell. As shown in 2.Since the air pressure ratio was only 1.2, the flow of air was greatly decreased by the fluid resistance of the air supply sub-systems . The maximum flow rate was measured to be 49.96 kg/h, at which the maximum output currents of the PEMFC stack were 171 A and 238 A under air stoichiometric ratio of 2.5 and 1.8, respectively. However, there was a pressure drop caused by the humidifier, air filter, and stack, which caused a decrease in air back-pressure to a level lower than 10 kPa, and eventually contributed to a degradation of the PEMFC stack performance. The single cell voltage was close to 0.6 V when the PEMFC stack output current was 160 A. The hydrogen consumption rate increased when if the single cell discharged below 0.6 V. Therefore, a corresponding air stoichiometric ratio of 2.68 was applied to maintain a higher discharging voltage .To evaluate the consistency of single cells, the voltage of a single cell at 165 A was recorded. As shown in In the practical operation of the PEMFC stack, differences in batch quality and operation status of MEAs may result in different lifetimes of MEAs. Replacement of those degraded MEAs is necessary to ensure the stable operation of the PEMFC stack. In order to investigate the influence of replacing old MEAs with new MEAs on the performance of PEMFC stack, a stack was assembled using different batches of used MEAs. As shown in Water management of the PEMFC stack was necessary to prevent flooding of the catalyst layer, while the accumulation of inert gases also required timely venting during operation. Since an improper venting cycle would lead to fierce fluctuation of the voltage, the interval of hydrogen venting (1800 A·s) was set considering both time and current. It can be seen from the chronoamperometry  that theAs shown in (1)Lifting 1 tonne load to 2.5 m and then lowering it to 0.3 m;(2)Driving the loaded forklift at a distance of 160 m;(3)Repeating stage (1);(4)Driving the loaded forklift back to the starting point.The PEMFC stack was subsequently installed in a Zoomlion counterbalance forklift  for field testing. The on-site test was conducted according to the following standards that involved four stages until exhausting all of the hydrogen:3) from 1.3 MPa to 20 MPa by a gas-driven hydrogen compressor. The inlet of the hydrogen storage tank was equipped with a stop valve, which was used to block the hydrogen of the compressor from entering the hydrogen storage tank in the case of a leakage. At the same time, a pressure relief valve was installed in the hydrogen storage tank, which was used to discharge overcharged hydrogen when the hydrogen pressure exceeded the set pressure. The hydrogen in the storage tank was further pressurized to 45 MPa by an electric compressor in the mobile hydrogen refueling station. Additionally, during refueling, high pressure hydrogen was filled into the 35 MPa carbon fiber-wound aluminum alloy tank of the PEMFC-powered forklift.The water electrolyzer worked 16 h a day, during which an 8 h power supply came from the photovoltaic plant . The power from another 8 h power supply came from an electric power supply during mid-night, whose price was 4 cent per kilowatt. 3/h. The total cost of all of the equipment which includes the water electrolyzer, hydrogen storage tank, mobile refueling station and PEMFC forklift is about USD 1.437 million. The cost of the PEMFC stack is about 15.6% of the total cost of the PEMFC-powered forklift. The cost of the PEMFC powered forklift accounts for about 60% of the total cost of all equipment.Assuming the prepared hydrogen is supplied to 20 forklifts, which work for 8 hours a day and 250 days a year , each forklift needs 3.06 kg of hydrogen per day. The daily hydrogen consumption of 20 forklifts will be 61.2 kg, and the hydrogen production rate of the electrolytic water hydrogen production system should exceed 42.84 NmThe use-cost of this scheme can be subdivided into the expenditures on water and electricity during the valley period, the annual use-cost was estimated to be~19,466 dollars per year. All of the facilities were esimated to depreciate according to a 10-year service life. The total cost of hydrogen production and hydrogenation would be about USD 337,420, including the water electrolyzer, the hydrogen storage tank and the mobile hydrogen refueling station. Considering that maintenance costs are 2% of the total cost of hydrogen production and the hydrogenation equipment, the total equipment cost is USD 344,168.4. That means the total cost of hydrogen production for 10 years is about USD 538,828.4. The total hydrogen consumption of the forklifts for 10 years is 153,000 kg, so the cost of hydrogen is about USD 3.52 per kilogram. Compared with the diesel engine forklift, the annual fuel cost saved by the PEMFC forklift with this scheme is USD 289017. Considering the cost saved by fuel, the total cost of the PEMFC forklift, the full set of hydrogen production and the refueling system can be recovered in 4.9 years. The total cost of the forklifts  driven by two different power sources for 10 years was compared. The total cost of the PEMFC forklift over 10 years is USD 1631600, while that of the diesel engine forklift over 10 years is USD 3610045.6. Twenty PEMFC forklifts can save USD 1978385.6 over 10 years and reduce emissions of carbon dioxide by about 6838 tonne compared to 20 diesel internal combustion engine-powered forklifts. The PEMFC hybrid power system combining a PEMFC system and lithium-ion batteryies was tested on a forklift. The venting cycle considering both current and time minimized the fluctuation of voltage. The work efficiency and mileage of the PEMFC-powered forklift and diesel engine forklift were compared, with the result showing that the PEMFC powered forklift has higher work efficiency and longer mileage. The comparison of economic efficiency of the two different power systems showed that the PEMFC-powered forklift has great advantages in terms of the use-cost. A remarkable reduction in exhaust gas emissions is not only significant for environmental protection, but also brings great benefits for customers in future carbon trading.


Steel corrosion is the main cause of reinforced concrete cracking. Conventionally, concrete is considered to crack when the circumferential tensile stress reaches the tensile strength of the concrete. However, few analyses have considered the fracture criteria of the internal cross-section of concrete. Based on the von Mises distribution of angle probabilities, this paper proposes a new probability distribution function for investigating the distribution law of corrosion products. The cracking process of experimental samples was numerically analyzed, and the results were consistent with those of the theoretical model. The effect of the dry–wet cycle ratio on the corrosion products was preliminarily investigated by microscopic observation of the reinforced concrete under different dry–wet cycle corrosion environments. Reinforcement corrosion increases the volume of corrosion products, causing internal pressure in concrete. Internal pressure leads to concrete cracking, structural damage, and economic losses ,2,3,4,5;In a conventional view, the concrete will crack when the circumferential tensile stress reaches the tensile strength of the concrete ,14,15. Tsettings ,18. Zhimsettings  measuredsettings  observedHowever, the aforementioned studies assumed that the materials exhibited linear elastic tensile behaviors, and did not consider the actual characteristics of the materials. Smarzewski  recentlyThe present paper develops a theoretical model of nonuniform corrosion cracking of steel bars. This model is based on a probability distribution function and considers the fracture criteria of the internal cross-section of concrete, which has rarely been considered.The corrosion products include the corrosion products filling the void area, in the corroded part of the reinforcement, and beyond the void area see .In the following, The total amount of corrosion products (mg) is expressed using the following geometric relationship:3), 3), and In the planar problems, the thickness can be taken as one unit, and the corrosion products filling the voids are given by3).According to the geometric relationship in Beyond the void area, the amount of rust products is calculated as:W1—is the filling amount of the rust products extending beyond the void area corresponding to W2—is the filling amount of the rust products extending beyond the void area corresponding to dV is the volume of the corrosion products outside the filling void area (mm3).Substituting Equations (2)–(4) into Equation (1), the total amount of the corrosion products is obtained as:Some scientists have demonstrated that the thickness of the void zone  omitted . Accordin of the corrosion products. Using this ratio, the total volume of the corrosion products (mm3) can be related to the volume versus the reinforcement consumed as follows:The volume ratio of all the corrosion products to the reinforcement consumed is called the expansion ratio The total volume of the corrosion products is the sum of three parts:In the planar problems, the filling volume of the corrosion products can be obtained by calculating the per-unit thickness as follows:Combining Equations (7) and (8), the total volume of the corrosion products is given bySubstituting Equations (9) and (10) into Equation (11) yieldsAfter simplification, the volume 3), and 3).From Equation (13), the corrosion rate is obtained as follows:Zhao et al. and Wong et al. ,26,27 stThe general Gaussian distribution function is given byk is the nonuniformity coefficient, Notably, the Gaussian function of the corrosion thickness given by Equation (15) has the same form as the general Gaussian distribution function given by Equation (16). The von Mises distribution function  models aThe total thickness of the corrosion products is obtained by summing the consumed thickness of the steel reinforcement, the void-area thickness and the thickness outside the void area, as illustrated in Combining Equations (18) and (19), the relationship between Substituting Equation (20) into Equation (19), the total thickness of the corrosion products is given bySimplifying Equation (21), the thickness outside the void area is calculated as:In the planar problems, the volume of the corrosion products outside the filling void area When the thickness loss of the steel bars is sufficiently smaller than the diameter of the steel bars, In Equation (24), the integral term From Equations (9) and (11), the following equation is obtained:When substituting Equation (25) into Equation (26), the total volume of the corrosion products From Equation (27), the correction coefficient Substituting Equation (28) into Equation (17), the total thickness of the corrosion products is calculated as:From Equation (14), the reinforcement corrosion rate is given bySubstituting Equation (30) into Equation (29) yields the following relationship between the total thickness of the corrosion products and the corrosion rate of the steel bars:When substituting Equation (31) into Equation (22), the thickness outside the void area From Equation (32), the maximum filling thickness of the corrosion products is given as:q = q0sinθ, where π/2. Additionally, as the boundary stress changes with A and B are the coefficients determined by the boundary conditions and constraints.The thickness distribution of the rust layer is assumed to be a semi-ellipse along the upper half-circle, which can be approximately represented using a sine function see . As the R is the radius of the steel bars (mm), and l is the maximum radius of the ring (mm).In the elastic mechanics theory, the stress component can be represented by the radial normal, circumferential normal, and shear stresses in the plane, respectively, given byA and B are obtained as follows:When substituting the boundary condition into Equation (35), the coefficients From Equations (35) and (36), the hoop stress at When the maximum tensile stress at the interface of the reinforced concrete When substituting Equation (38) into Equation (37), the maximum rust expansion force is given byA and B at the critical cracking state are obtained as:By substituting Equation (39) into Equation (36), the coefficients The radial strain is obtained using the following physical equation:The radial strain is related to the radial displacement by the geometric equationWhen substituting Equation (41) into Equation (42), the radial displacement is given as:Finally, when substituting Equation (40) into Equation (43), the maximum radial displacement of concrete at the critical state of interface cracking  and (44), the limit state equation of concrete cracking is expressed as:In the limit state equation proposed in rmaxR = u and d(θ)S = u, the performance function of concrete cracking described using Equation (45) is newly defined asSetting R and S, respectively (in mm).If different nonuniformity coefficients have different effects on corrosion cracking, the corresponding reliability index can be expressed as follows:fc, cover thickness c, reinforcement diameter d, and corrosion rate ρ in the existing data [The averages and standard deviations of the concrete compressive strength ing data  are provβ for the different nonuniformity coefficients was calculated using the aforementioned formulas, and the results are plotted in K, the smaller the β. This trend is reasonable because K represents the filling degree of the rust products around the reinforcement; therefore, as K increases, the rust products become more concentrated. When 0 ≤ K ≤ 1, the rate of the reliability index was at the maximum, indicating a clear influence of the nonuniformity coefficient on the reliability index during the filling process. When K exceeded 1, the influence of the nonuniformity coefficient on the reliability index was reduced.From the statistical data in the relevant literature ,32,33, tTo improve the accuracy of the experimental results, no active agent, except the sodium chloride solution, was added when pouring the concrete. After trial-and-error and adjustments of the mix proportion following the relevant methods specified by the Regulation of Common Concrete Mix Design (JGJ55-2011), the final concrete mix for the test was determined see .After 28 days of moist curing, the specimens were exposed to an artificial environment to accelerate the steel corrosion. The artificial environment was introduced in two stages: corrosion initiation and corrosion propagation. Corrosion initiation involved exposing the specimens to a cyclic dry–wet environment for 1–3 months. Each dry–wet cycle included wetting in a 7% (by mass) NaCl solution and oven-drying at 65 °C . To ensure a similar amount of chloride around the surface of each cross-section, each specimen was placed vertically in a container. The details of the sample groups are provided in The cracking process of concrete through dry–wet cycling is a long-term process, requiring over 1–3 months. The cracking times of the samples are listed in Influence of the thickness of the concrete cover on the cracking timeIn the specimens with the same reinforcement diameter and concrete strength, the cracking time of the specimens increased with the increasing thickness of the concrete cover . As the Influence of the reinforcement diameter on the cracking timeAs illustrated in Effect of the ratio of dry–wet cycles on the cracking timeAs illustrated in The specimens were observed using optical microscopy (OM), environmental scanning electron microscopy (SEM), energy-dispersive spectrometry, and X-ray diffraction (XRD). SEM only observes the surface morphology of the rust layer and cannot depict the true color of the material. Therefore, the sections of reinforced concrete were observed using both the environmental SEM and OM. For convenience, we inserted the test block along the crack with a slotted screwdriver and then pried the test block to remove the inner rust layer. To avoid further oxidation in the air, the test block was quickly transferred to the X-ray diffractometer for observation.The distributions of the corrosion products in the cracks and interfaces were observed and analyzed using OM. The development mode of the rust pits on the reinforcement surface in the dry–wet cycle environment, inferred from the aforementioned analysis, is illustrated in The energy spectrum in As shown in The XRD patterns of eight samples in this experiment were compared with the standard XRD pattern of iron oxide. The results are displayed in The peaks attributable to the corrosion products appeared at the same positions in the diffraction patterns of each specimen, and the strongest peak appeared at approximately The reinforcement in concrete actually corrodes via an electrochemical process ,37,38,39Corrosion proceeds in four basic stages , as depi2O3, and Fe3O4. Among these products, γ-FeO(OH) is a transitional hydroxyl iron oxide that assists the formation of the most stable hydroxyl iron oxide, α-FeO(OH). When concrete exists in a long-term immersion state, its oxygen supply is limited. On the contrary, when the concrete dries over a long period of time, its interior is relatively dry and the oxygen supply is abundant. During the dry–wet cycles in the present experiment, the internal pores were never completely dry or wet; thus, the comprehensive ability of the oxygen supply and diffusion was better than that of those of the fully dry and fully moist states.From the XRD pattern, the major corrosion products in each specimen were discerned as α-FeO(OH), β-FeO(OH), γ-FeO(OH), FeWhen the rust expansion cracks penetrate the concrete cover, the steel bars inside the concrete become oxygen-enriched. In such an oxygen-enriched environment, the rebars produce more high-valence corrosion products, such as γ-FeO(OH) during the dry–wet cycle see .On the basis of the composition and contents of the eight samples and the transformation process of the iron oxidation products, it was concluded that when the dry-to-wet ratio was reduced, the γ-FeO(OH) and β-FeO(OH) contents increased and the α-FeO(OH) content decreased. When the other conditions were identical, reducing the dry-to-wet ratio lengthened the corrosion cracking time and facilitated the formation of β-FeO(OH) and its intermediate product γ-FeO(OH) through the large impact of chloride ions.The main conclusions of this paper are summarized as follows:(1) A theoretical model of nonuniform corrosion cracking of steel bars was proposed. In this model, when the maximum filling thickness of the corrosion products exceeds the radial displacement of concrete, the concrete cracks.K ≤ 1.(2) An analysis of the relationship between the nonuniformity coefficient and reliability index demonstrated that the larger the nonuniformity coefficient, the smaller the reliability index. The reliability index decreased most rapidly in the range of 0 ≤ (3) The development mode of the rust pits on the surfaces of the steel bars did not depend on the wet–dry cycling environment of the concrete.(4) The Fe and O distributions in the energy spectrum of the corroded reinforced concrete were divisible into five areas: reinforcement, rust layer, oxide skin, polluted concrete, and unpolluted concrete.2O3, and Fe3O4. The further comparative analysis indicated that a reduction in the dry–wet ratio of the dry–wet cycles increased the γ-FeO(OH) and β-FeO(OH) contents.(5) Based on the corrosion principle of reinforced concrete and the XRD results, the main corrosion products that were under the different dry and wet cycles were α-FeO(OH), β-FeO(OH), γ-FeO(OH), Fe


In this paper, the influence of the contact resistance between the conductive fluid and the metal electrode on the output characteristics of the magnetic fluid micro-angular vibration sensor (MHD sensor) is theoretically analyzed. The contact resistance models based on the solid-solid electric contact theory are established based on the resistivity, temperature, pressure and angular vibration of the materials between the conductive fluid and the metal electrode. The contact resistance was tested by setting up an experimental platform and making conductive fluid rings with electrode materials of Ag, Cu and Ti. The results show that the static contact resistance between the conductive fluid and the metal electrode is positively correlated with the material resistivity and temperature, and negatively correlated with the surface roughness and contact pressure of the metal electrode. The dynamic contact resistance fluctuation is proportional to the amplitude of the input voltage of the angle shaker and inversely proportional to the square of the input frequency. At the same time, reducing contact resistance can improve the MHD sensor’s performance. A magnetohydrodynamic micro-angle vibration sensor (MHD sensor) is a kind of measuring high frequency, lower value angular vibration sensor, with wide band, lower noise, impact and characteristics of small volume, and it is widely used in high-precision deep space spacecraft, such as relay satellite mirror RME , land suThe fluid ring is the core sensitive element of MHD sensors ,5, whichMost of the research on contact resistance has focused on solid-solid contact resistance, and there has been less research on liquid-solid contact resistance. Indeed, ref.  proposedThis paper studies the influential factors of liquid-solid contact resistance of a fluid ring based on the solid-solid electric contact theory, and verifies the influence of different electrode materials on liquid-solid contact resistance through simulation and experimentation. The paper is organized as follows: ZΩ is generated relative to the sensitive axis Z of the MHD sensor, due to the large inertia of the conductive fluid and the static relative to the shell, the relative motion between the conductive fluid and the permanent magnet magnetic field is generated, and the magnetic field line is cut, and the potential difference zV is generated between the upper and lower conductive surfaces. The potential difference zV is proportional to the input angular vibration ZΩ, and the outV can be detected by the coil amplifier and subsequent circuit amplification processing. The relevant information of the angular vibration can be solved by analyzing the collected signal.The working principle of the MHD sensor is based on Faraday’s law of electromagnetic induction. As shown in rB is the magnetic induction intensity at the conductive fluid; H is fluid ring height; rmsr is the root mean square radius of the fluid ring. ρ is the density of conductive fluid; w is the width of the fluid ring, w = o-rir, or and ir are the outer radius and inner radius of the fluid ring, respectively; Ha is Hartmann constant; fμ is the kinematic viscosity of conductive fluid.According to Faraday’s law of electromagnetic induction and the principle of magnetohydrodynamics, the fluid ring model can be expressed as:zV of the fluid ring output signal of high frequency weak signal is one of the key problems of the MHD sensor. In order to obtain the higher amplification ratio as far as possible, it is also necessary to consider the bandwidth. Simple circuit amplification cannot meet the requirements, so the signal amplification process uses a passive device coil amplifier for primary amplification to suppress noise. Then comes the second stage of amplification and filtering, and other post-processing. The section diagram of the fluid ring cavity is shown in zV of the fluid ring is equivalent to a voltage source, the resistance of the conductive fluid and the metal electrode and their contact resistance, and the primary composition loop of the coil amplifier. Due to the small number of primary turns of the coil amplifier, eddy current loss resistance and parasitic capacitance are not considered; only the copper loss of the primary coil is considered, which is equivalent to the series of resistance and inductor. Due to the large number of turns of the secondary coil, copper loss of the secondary coil and parasitic capacitance between the windings of the secondary coil should be considered. Therefore, the secondary coil is equivalent to a series of resistance and inductor, and then a parallel connection with the capacitor. Then, the equivalent resistance of the coil amplifier primary loop can be expressed as:R is the total resistance of the primary coil; sR1 is upper electrode resistance; sR2 is the lower electrode resistance; flR is conductive fluid resistance; cR1 is the contact resistance between the conductive fluid and the upper electrode; cR2 is the contact resistance between the conductive fluid and the lower electrode; R1 is the coil amplifier resistance.The detection of According to Kirchhoff’s law, the equivalent circuit equation of the coil amplifier is:It can be obtained from Equation (3):outV can be obtained:Therefore, the output voltage Thus, the transfer function between the input and output of the coil amplifier is obtained as follows:sE can be calculated according to the resistance thermal noise spectral density formula:κ = 1.38 × 10−23 J/K is Boltzmann’s constant; T is absolute temperature (K); N is the amplification ratio of the coil amplifier.The noise source of the MHD sensor mainly includes external noise and internal noise. Due to the imperfect electromagnetic shielding of the sensor, the external electromagnetic interference will affect the output of the sensor, and the impedance of the equivalent electrical components inside the sensor is the main source of internal noise. The MHD sensor’s internal resistance thermal noise voltage noise spectral density cR1 and cR2, the other resistance values are all composed of the resistance values of the metal materials themselves. When the structure of the fluid ring is determined, the resistance value is fixed. There are many factors, such as conductivity, temperature, pressure, etc., affecting the contact resistance cR1 and cR2. Therefore, reducing the contact resistance value is beneficial to reduce the primary resistance R.According to Equations (6) and (7), the smaller the primary resistance R is, the smaller the impact on the output of the MHD sensor will be, and the more stable the coil amplifier system will be. In Equation (2), the primary resistance is the sum of the resistance values of all materials in the primary loop and the contact resistance values between adjacent materials. In addition to the contact resistances Similar to the solid-solid contact resistance, the factors affecting the liquid-solid contact resistance of the fluid ring mainly include resistivity and wettability of conductive fluid and metal electrode, contact area, surface roughness, contact pressure, vibration, etc.cR is the contact resistance; ρ1 and ρ2 are the resistivity of conductive fluid and metal material electrode; n is the number of conductive spots on the contact surface between conductive fluid and metal electrode; ir is the equivalent radius of conductive spots. According to Equation (8), the resistivity has a great influence on the contact resistance. A small resistivity can not only reduce the contact resistance, but also help to reduce the resistance of the metal electrode. The greater the number of conductive spots, the smaller the contact resistance. The larger the surface roughness of the metal electrode, the more discontinuous contact points, the fewer conductive spots, the smaller the ratio of the actual contact area to the apparent contact area, and the higher the contact resistance.(1) Material conductivity: According to the Holm contact resistance model , the consTρ and lTρ are the resistivity of the metal electrode and conductive fluid at temperature T °C; Sρ0, lρ0 are the resistivity of the metal electrode and conductive fluid at 0 °C; Sγ and lγ are the resistivity temperature coefficients of the metal electrode and conductive fluid.(2) Temperature: The resistivity of conductive materials changes with temperature ,17, whicTherefore, substitute Equation (9) into Equation (8) to obtain:In Equation (10), with the increase in temperature, the resistivity of conductive fluid and metal electrode increases, and the contact resistance accordingly increases.Y1, Y1, which is called the wetting depth [Y1 will actually make contact with the conductive fluid. When the current passes through the contact interface between the conductive fluid and the metal electrode, the contact resistance is related to the shape of the conical convex point.(3) Pressure: When the conductive fluid wets the rough surface of the metal electrode, according to the Cassie-Baxter model , the conng depth ,20. OnlyY1 can be expressed as:bp is the pressure applied on the conductive fluid; wp is the liquid column pressure generated by the conductive fluid on the microcavity. rp is the capillary pressure at the interface between electrode surface and conductive fluid. σ′ is the standard deviation of surface roughness height.As shown in bP increases, the average height of the microcavity Y1 decreases, the depth of the conductive fluid wetting the surface of the metal electrode increases [According to Equation (11), as the external pressure ncreases , the actrU and rf, respectively. Angle vibration excitation, input voltage amplitude and frequency K for the parameters are associated with the high frequency vibration table. The relationship between the output angular vibration of the high frequency shaking table and the input voltage can be expressed as follows:K1 is the constant related to the high frequency shaking table; a is angular acceleration; θ is the angle position.(4) Angular vibration excitation: Under the angular vibration excitation, the conductive fluid and the metal electrode have relative motion, which causes the change in contact area and the change in contact resistance ,24,25,26cR is the contact resistance; S is the static contact area between the conductive fluid and the metal electrode; ΔS is the change of contact area during angular vibration, as shown in Therefore, in the process of angular vibration excitation, the fluctuation of fluid ring contact resistance can be expressed as:K2 is the parameter related to angular vibration. According to Equation (15), when the fluid ring is excited by the high-frequency shaking table, the fluctuation of the contact resistance of the fluid ring is proportional to the amplitude of the angular vibration voltage and inversely proportional to the square of the angular vibration frequency.The fluid ring contact resistance fluctuation can be expressed as:The contact resistance test platform was composed of hardware and software. The hardware mainly included fluid ring 8, high-frequency shaking table 6, resistance meter 5, acquisition card 1, temperature control circuit 14, air source and pressure regulating valve 11, etc. Software mainly included temperature control and monitoring program 15, contact resistance acquisition program 16, high-frequency shaking table control program 17, etc., as shown in 7 S/m), silver (6.3 × 107 S/m) and titanium (2.3 × 106 S/m), respectively, with high conductivity and no magnetism for the MHD working principle. Due to the soft texture of pure silver, a copper electrode was used for overall silver plating, so that the electrode surface and conductive fluid contact material were silver. Four groups of fluid rings were made for the contact resistance test. The upper and the lower electrode materials were 1#: Ag-Ag, 2#: Cu-Ag, 3#: Cu-Cu and 4#: Ti-Ti, respectively. The fluid rings were cleaned with petroleum ether and acetone before assembly and bonded with epoxy resin . The copper electrode lead wire was welded with the upper electrode and the lower electrode by lead-free solder paste  to draw out the contact resistance for convenient measurement.Fluid ring 8 was the experimental object of contact resistance, and its upper and lower electrodes were made of copper (5.7 × 10−7 Ω)~120 MΩ, and could achieve a high resolution 7-bit display. The air source was dry compressed air and the maximum atmospheric pressure was 0.85 MPa. The pressure regulating valve adopted was a SMC precision pressure regulating valve; range was 0.6 MPa, accuracy was 0.002 MPa. The temperature control circuit adopted was a temperature control module TCM-X107 , and control accuracy was ±0.01 °C.The high-frequency shaking table 6 used 105-AVT-I/M from ACUTRONIC, Switzerland, and could provide a stable angular vibration output from 25 Hz to 2.5 kHz. Acquisition card 1 adopted the NI PCI-6289 board from NI Company, United States, which had a 24-bit A/D acquisition card, 32 analog inputs and 4 analog outputs. Resistance meter 5 used RM3542-01 from HIOKI, Japan, through the DC four terminal method to test the contact resistance, measurement range: 0 Ω  Static pressure experiment: the contact resistance of the fluid ring is measured by the DC four-terminal method. The two Kelvin clips of the resistance meter RM3542-01 are respectively clamped to the leading wire of the upper electrode and the lower electrode of the fluid ring, and the air pressure is applied to the conductive fluid through the filling port. Revision: The electrode material of the conductive fluid ring used in the experiment is 3#: Cu-Cu, in which the conductive fluid is carried out by automatic vacuum perfusion and atmospheric pressure manual perfusion. The ambient temperature was 25 °C ± 1 °C.(2) Static temperature experiment: a PI thin film resistance heater is wrapped on the cylindrical surface outside the fluid ring cavity, and the thin film Pt resistance CRZ-1632 was pasted on the metal electrode. The temperature of the conductive fluid in the fluid ring is controlled by the TCM-X107 temperature control module, and the static resistance of the fluid ring at different temperatures is measured using the four-wire resistance experiment method.(3) Static experiment of electrodes of different metal materials: the fluid ring is fixed on the 105-AVT-I/M high-frequency vibration table by special tooling, as shown by No. 13 in (4) Dynamic experiment: input the specified amplitude and frequency through the LabView program to control the output angle vibration of the high-frequency shaking table. Meanwhile, the fluid ring moves with the high-frequency shaking table, and the contact resistance and corresponding temperature changes of the fluid ring in the vibration process are recorded.(5) Static noise and frequency response experiment: different metal electrodes are assembled into the MHD sensors, except the fluid ring, the rest of the parts are the same as the static noise and frequency response experiment of the MHD sensor.rU is greater than 0.1 V, the fluctuation of contact resistance is linearly related to the input voltage amplitude; (2) when the input voltage rU is less than 0.05 V, the resistance fluctuation during vibration is small, which is close to the resistance fluctuation before and after vibration. If the input voltage amplitude continues to be reduced, the contact resistance fluctuation will not accurately reflect the angular vibration.This paper analyzed the influencing factors of the contact resistance between conductive fluid and metal electrode in the fluid ring of the MHD sensor, and an experimental study on the static and dynamic contact resistance between different metal electrodes of Ag, Cu, Ti and conductive fluid. The following conclusions were drawn:(1) The static contact resistance between the conductive fluid and the metal electrode decreases with the increase of pressure, and increases with the increase of temperature.(2) Static and dynamic contact resistances of different materials are related to the resistivity of the material and the wettability between them. The lower the resistivity of the material, the better the wettability of the conductive fluid to the metal electrode, and the smaller the contact resistance.(3) The contact resistance of the fluid ring oscillates with angular vibration, and the amplitude of contact resistance fluctuation is proportional to the amplitude of angular vibration input voltage, and is inversely proportional to the square of angular vibration frequency.(4) The contact resistance has a great influence on the static noise PSD curve and frequency response characteristic curve of the MHD sensor, and the MHD sensor with low contact resistance has a better performance.In conclusion, by selecting electrode materials with low resistivity and good wettability, or improving the wettability between conductive fluid and electrode materials, the fluid ring contact resistance can be reduced and the performance of MHD sensor can be improved.


In this context, the aim of this study was to evaluate the effect of different modified packaging atmospheres on the shelf-life of sourdough bread. Slices of bread were stored individually in plastic bags at 23 °C in five different atmospheres (Ar (100%), N2 (100%), CO2 (100%), Mix CO2/N2 , Mix CO2/Ar ), and Air was selected as a control. To select the best storage conditions, both chemical-physical, rheological, and organoleptic features were evaluated. Results showed that pure gases  displayed good qualities as storage atmospheres compared to Air. In contrast, both Mix CO2/N2 and Mix CO2/Ar were the best in slowing down the staling process, thus doubling the shelf-life of bread, compared to other atmospheres. In conclusion, argon, as a preservation atmosphere, seems to be the best solution to extend the shelf-life of PDO Tuscan bread.The short shelf-life of PDO Tuscan bread limits its distribution to markets close to the production area, affecting its commercial success and the economic return by supply chain operators. While the application of MAP to store bread is widely accepted, the suitability of this technique to extend the shelf life of the PDO Tuscan bread is still to be explored. Furthermore, to the best of our knowledge no data are available in the literature about the use of argon as filling gas neither in pure atmosphere nor in combination with CO Over the last decades, European consumer behavior in the baked goods category has changed and an increasing demand for products with reduced environmental impact together with symbolic features with ethical values such as naturalness, healthiness, distinctiveness, and consistency has been observed . These nAcross Italy, in the last years, a re-localization process based on the establishment of Protected Designations of Origin (PDO) and Protected Geographical Indications (PGI) for bread was aimed at closing the gap between producers, processors, and consumers. The actuation of innovative, localized bread supply chains based on different assumptions such as variety, production method, baking process, zero-miles consumption models, etc. represents a possible strategy to sustain the cereal sector giving an economically viable alternative for Italian smallholders to compete on the market ,3.As in many other Italian regions, in Tuscany, bread has evolved as a basic consumption item in relation to the local history and culture. In order to foster and protect Tuscan bread, the process for the recognition of the “PDO Tuscan Bread” was promoted from 2002 by baker and farmer associations, the milling industry, and other local stakeholders . The oriSome crucial aspects differentiate PDO Tuscan bread supply chains from conventional ones: (a) wheat must belong to a set of soft wheat varieties cultivated in Tuscany; (b) sourdough leavening is compulsory; (c) no salt can be added to the recipe; (d) flour must include wheat germ; (e) the final weight must range between 0.45 and 1.10 kg; and (f) the Consortium label is compulsory.Thanks to the use of sourdough as leavening agent , the PDONevertheless, despite the improved shelf-life shown by PDO Tuscan bread, the geographic area of its supply chain appears still limited and a huge quantity of waste is generated with a consequent loss of economic resources together with a significant environmental impact ,12.As the refrigeration of freshly baked bread is not applicable as its texture and taste are negatively affected by low temperatures , the use2) with nitrogen (N2) acting as a filler gas [2 can dissolve in the water of the bakery products to form carbonic acid, leading to a lowering of the pH. As reported by Smith et al. 1986 [2 and/or CO2. In particular, a necessary condition to prevent mold growth was to maintain the level of O2 below 0.4%, in accordance with the results showing the reliance between O2 content and fungi growth on other types of products under MAP [2 may determine an increase in the perceived acidity to the taste [2 in the MAP on the bread quality appears still contradictory [Generally, when MAP is utilized to store bakery products, the gas mixture consists of 60% or more carbon dioxide , CO2 (100%), Mix CO2/N2 , Mix CO2/Ar ) and Air was utilized as control. To the best of our knowledge, no data are yet available in the literature concerning the feasibility to use Argon (Ar) as filling gas in MAP for sourdough bread storage. To select the best storage conditions, chemical-physical, rheological, and organoleptic features were evaluated.In this context, the aim of this study was to evaluate the effect of different MAP on the shelf-life of the PDO Tuscan bread. Slices of bread were stored individually in plastic bags at 23 °C in five different atmospheres (Ar (100%), NTriticum aestivum) produced by the Department of Agriculture, Food, Environment, and Forestry of the University of Florence during the 2021 crop season. The milling process was carried out at the Department of Agricultural, Food, and Environment (DAFE) of the University of Pisa using a commercial mill .The flour (type 0) was obtained by a mix of four varieties  of common wheat ; bread making was carried out from a pre-ferment leavening agent, according to the two-step method of “biga” , as repoAll the tests were conducted at the Food Technology laboratory of the Department of Agriculture Food and Environment of Pisa University; moreover, for each formulation, three replications were performed.2 (100%), CO2 (100%), Mix CO2/N2 , Mix CO2/Ar ); storage atmosphere composed by 100% Air was utilized as control.After baking, bread loaves were cooled for 2 h at room temperature, then sliced with an automatic slicing machine to 20 mm thickness. Each slice was packed individually in plastic bags , by an industrial packing machine . During packaging, the composition of the internal atmosphere was modified to obtain 5 different MAP conditions (Ar (100%); NEach pack was stored at a controlled temperature (T = 23 °C) during the whole observation period.To determine the bread shelf-life as a function of storage conditions, a total of 50 loaves (1 kg each) were prepared, 1500 slices were packed separately as described above, and divided into 6 groups as a function of MAP composition (5 different MAPs and Air 100% as control). To follow both the chemical-physical and sensory evolution of the packed bread during storage, as well as visible mold appearance on bread surface, four sliced samples for each storage condition were opened daily and analyzed as described below.® CheckPoint 3 CO2 (infrared sensor) and O2   was used to measure the gas composition inside each pack during storage. The handheld non-destructive gas analyzer is easy to use, fast at processing data, and uses an optical sensor to provide the highest level of accuracy among similar products.A DansensorThe moisture content of bread crumbs, taken from the center of each slice, was determined on approximately 5 g sample drying at 105 °C until constant weight, while the pH value was measured according to the AACC  standard method, as previously reported . Total tFor each experimental run, the slices were weighed daily to assess the weight loss associated to water evaporation from the slices during storage; the value was expressed as a percentage reduction compared to the starting value.w was measured by a HygroPalm HP23-AW-A equipment . The results were expressed as a percentage reduction in water activity compared to the starting value [ang value .To measure the softness of the crumb, its compressibility was determined by a penetrometer PNR-12 , Italy) as described by Al Omari et al. (2016)  with somAll the samples were checked daily for the presence of mold; each experimental run was stopped when 5% of the samples showed mold spoilage.The sensory profiles of the bread samples were evaluated by a panel of 8 trained judges (aged between 23 and 60 years). All the people involved were members of the “Committee of Experts” of the Department of Agriculture, Food, and Environment Sciences of the University of Pisa. The tasting was carried out according to the previously developed protocol . Before The research obtained the approval of the ethical committee of the University of Pisa .The data obtained were processed by statistical analysis and the significance of differences among means was determined by one-way ANOVA .p ≤ 0.05 significance was used for the separation of the samples.Chemical evaluations were performed at least in triplicate and the data are reported as average values. Tukey’s HSD test at The trend of the parameters over time was elaborated with the JMP software package version 17 .The results of the sensory analysis were processed by the Big Sensory Soft 2.0 software (version 2018). Sensory data were analyzed by two-way ANOVA with panelists and samples taken as main factors .After baking, the moisture redistribution from the crumb to the crust and the water loss that causes the decrease of softness of the crumb represent two critical issues deeply affecting bread shelf-life .2/N2 as well as Mix CO2/Ar were used, regardless of MAP composition.As reported in 2, and CO2) exhibited an intermediate quality decay rate when compared to Air and both Mix, and very similar performances were observed regardless of the pure gas used for storage.Bread preserved with the three pure gas MAPs  increasing inside the bag with consequent higher opportunity for mold development.Panel tests were carried out on the slices of bread before packaging (t = 0) and daily, to evaluate the impact of different MAPs on the organoleptic profile of stored bread.Given that the experimental run with Air as preserving atmosphere was stopped at day 8 because of mold development, data related to the panel test made at day 8 for all the storage conditions were reported in 2 was utilized as preserving atmosphere, closely followed by Air. These results are consistent with what was previously observed [2 in the storage atmosphere can significantly increase the sourness of the stored food with a negative impact on its taste. Furthermore, in all the other conditions , the value of the acid taste did not increase if compared to the value of bread at t = 0, regardless of the composition of filling atmosphere. In the case of sliced bread, the olfactory parameters were also affected, showing the highest decay. At last, the bread stored with pure Ar best retained its organoleptic profile when compared with bread at t = 0.After 8 days of storage, the organoleptic profile of bread was significantly affected by the different MAPs, with the worst results observed when pure COobserved ,26: the The hedonic quality level of a product is fundamental in determining its acceptability and overall pleasantness of the product. A value of 6 was taken as a reference point for the acceptability limit.The hedonic indexes of bread samples, at time zero and after 8 days of storage in the different experimental conditions, are reported in 2 were clearly the least appreciated, while those preserved in pure argon were described as the most pleasant, closely followed by samples stored in pure N2. Furthermore, the presence of CO2 in the storage atmosphere, even in mix with N2 and Ar, reduced the pleasantness of the stored bread.The slices of bread preserved in Air and COSimilar to what was reported for the sensory characterization of stored bread, the chemical composition of the bread samples was reported and discussed at time zero and after 8 days of storage under different MAPs .2. Therefore, we can assume a dissolution of CO2 in the matrix, that, on a sourdough bread where the acidity is high results in a sum effect and determines an unacceptability from the sensory point of view. No significant differences were detected between N2 and Ar. Furthermore, after 8 days of storage, the evolution over time of the main chemical-physical parameters fully confirmed what was highlighted by the sensory analysis.The time evolution of the chemical-physical parameters of the stored bread was significantly affected by the composition of the atmosphere inside the pack. In fact, as seen in the 2 or N2).While the application of MAP to store bread is widely accepted, the suitability of this technique to extend the shelf life of PDO Tuscan bread is yet to be explored. Furthermore, to the best of our knowledge, no data are available in the literature on the use of argon as filling gas nor in pure atmosphere nor in mixture with other filling gas .2 inside the package significantly affected the taste of the stored bread by increasing the perceived acidity. Given that the PDO Tuscan bread is a sourdough bread, the above-mentioned increase was even more evident due to the high acidity that characterized the bread before packaging.According to the literature ,24,25,262, to identify also the best economic solution.All in all, the slowest quality decay rate was observed when 100% argon was utilized as filling gas. Thanks to the promising results obtained with pure argon, subsequent industrial-scale experiments will be carried out with different mixtures of Ar/N