Furthermore, lithium orthosilicate has the advantages of low activation characteristics, low thermal expansion coefficient, high thermal conductivity, high density and stability. Even if they are far from the industrial standard, a variety of industrial processes have been proposed for making orthosilicate pebbles with diameters of 0.1–1 mm. However, some manufacturing problems have been observed, such as in the chemical stability (agglomeration phenomena). The aim of this study is to provide a new methodology for the production of pebbles based on the drip casting method, which was jointly developed by the DICI-University of Pisa and Industrie Bitossi. Using this new  manufacturing technology, in the field of fusion reactors, appropriately sized ceramic pebbles could be produced for use as tritium breeders.An open issue for the fusion power reactor is the choice of breeding blanket material. The possible use of Helium-Cooled Pebble Breeder ceramic material in the form of pebble beds is of great interest worldwide as demonstrated by the numerous studies and research on this subject. Lithium orthosilicate (Li The blanket  is one oThus, the major technical efforts in this framework are focused on tritium breeders, which are lithium-containing materials. To identify the most suitable candidate material, a variety of breeding blanket concepts have been considered, such as lithium ceramic breeders, liquid breeders, etc. ,2,3,4.In particular, the use of lithium ceramic material in the form of pebble beds attracted considerable interest worldwide, as demonstrated by the numerous studies and research investigating the feasibility of stable fabrication methods and the characterization of pebbles  ,11,12,134SiO4). This is of interest because lithium has a high density, low thermal expansion coefficient, high stability and high thermal conductivity [4SiO4 based on the drip casting is presented and discussed.In this study, the attention is focused on lithium orthosilicate , have been proposed for making orthosilicate pebbles with diameters of 0.1–1 mm. The diameter of 0.1–1 mm is an acceptable production characteristic for pebbles to fill the breeder volume of 30–100 mDel Serra et al.  analyzed2SiO3) and dendrites [As for the melt-spraying process, this process was demonstrated to be unsatisfactory due to the formation on the pebble surface of a second phase  characteristics and the ceramic production process parameters, it is possible to directly modify the properties of pebbles, including mechanical properties, such as compressive resistance, fracture toughness, hardness and abrasion resistance. This process allows the production of stable and well-sized ceramic pebbles, which at the same time also guarantees the sphericity and surface smoothness, the theoretical density and the other properties, such as the resistance, the hardness and fracture toughness, etc., which are traditionally desirable.In this study, the forming method used to produce LiThe innovative character of the new methodology under development at the Department of Civil and Industrial Engineering (DICI) of the University of Pisa jointly with Industrie Bitossi is based on the drip casting method  was used as the starting material. First, the process involved the preparation of a Li4SiO4 aqueous suspension with sodium alginate ((C6H7NaO6)n purchased from Sigma-Aldrich, Darmstadt, Germany). After this, the suspension was forced to pass through a nozzle plate to form droplets. Finally, the droplets were dropped into an aqueous solution of calcium chloride  where they coagulated in solid spheres  that ensures a colloidal suspension without the precipitation phenomena, which allows us to obtain a homogeneous dispersion of particles. Second, 5 wt % of sodium alginate was dissolved in deionized water at 80 °C for 2 h using a magnetic stirrer. This temperature helps the dissolution of sodium alginate in water, reducing the viscosity of the solution. After this, the alginate solution was added to Li4SiO4 suspension in order to obtain a slurry with a global concentration of sodium alginate of 3 wt % . The slurry was mixed with a magnetic stirrer for 30 min. Finally, 5 wt % calcium chloride solution was prepared by mixing CaCl2 in deionized water for 30 min.For the slurry preparation, a sodium alginate solution was added to the Li4SiO4 suspension, a diffuser disk, a multiple-nozzle plate  and a collection tank containing the saline solution.The experimental test facility shown in The feeding tank was connected to a compressed air line and equipped with a pressure regulator in order to ensure the dripping of the slurry through the nozzles. A pressure of around 2 atm was used for dripping.4SiO4 suspension was controlled by a manual ball valve. An elevator under the collection tank allowed the regulation of the distance between the nozzles and the reacting solution surface.The outlet flow of the LiSince the device operated at an ambient temperature and at about atmospheric pressure, no particular criteria were required for its design.The nozzles’ dimension was of a particular size in order to obtain pebbles of 1-mm diameter as optimum after sintering. In fact, the radius of the pebbles is dictated by the requirements for tritium release characteristics and the packing factor of the blanket.The prepared suspension contained in the suspension vessel was forced towards the ducts, which connected the former to the dripping sub-system by applying a slight pressure.2 solution, forming semi-rigid gelled spheres. This could be due to the polymerization of sodium alginate monomers, which creates a three-dimensional network and leads to the solidification of the ceramic slurry.Therefore, the mixture was conveyed to the diffusion system, the truncated conical shape of which facilitated the transfer to the dripping system. As the slurry ran through the nozzles, droplets formed and fell into the CaCl2 solution for 2 h in order to ensure complete gelation, before being collected with a metallic mesh.After dripping, the obtained spheres were kept in the CaCl4SiO4 suspension by the formation of cross-links among the alginate polymeric chains. When the suspension drops into the saline solution, the alginate sodium cations are replaced by divalent cations (Ca2+), before immediate irreversible gelation takes place.The principle of the drip casting technique involves the solidification of the Li4SiO4 particles are maintained in a three-dimensional network. The gelation reaction scheme is shown in Equation (1) and represented in LiThe obtained spheres were dried at 40 °C for 4 h, before being sintered in air at 600 °C for 2 h with a heating rate of 10 °C/min. Finally, they were left to cool at room temperature. During sintering, the calcium alginate network was combusted.4SiO4 pebbles obtained with this fabrication process seem full and densely packed. As shown in The LiIn the future, we plan to perform the thermo-mechanical characterization of the obtained pebbles according to the methodological procedure given in the flow diagram of the previous The improvement of the breeding material is essential for the design and development of the fusion reactor, which requires a high tritium breeding capability of the blanket.4SiO4 with more accurate and controlled spheroidal particle sizes . The drip casting technology is an efficient manufacturing process since it permits the modification of the initial setting of suspension to suit specific purposes and accordingly, to produce pebbles of different properties. The proposed process allows us to control not only the geometry, but also the density, coherence and chemical stability of the pebbles (responsible for the detriment of pebbles properties).In this study, we proposed the drip casting process as the alternative technology to the high-temperature methods for producing ceramic pebbles to be used in the fusion reactor. This fabrication method allowed us to obtain stable Li4SiO4, sodium alginate and water into an aqueous solution of CaCl2, which was sintered afterwards. The obtained pebbles were all of a similar size, with a diameter of about 1 mm. They showed regular roundness, without macroscopic defects.Ceramic pebbles were produced by dripping a suspension of LiThe present work suggests that the drip casting process can be adapted for producing ceramic pebbles. Nevertheless, process optimization and characterization of pebble properties  are necessary. Both these two activities are planned to be performed in the forthcoming future.


Unexpected results highlighted that the amount of particles reaching the vulnerable shorelines of both northern and southern bays accounted for 21.2% and 46.3% of the WWTP initial patch, in June 2008 and October 2011, respectively. Finally, a conceptual diagram is proposed to highlight the mechanisms of dispersion within the bays of Marseille of the fine particles released at the WWTP outlet that have long been underestimated.Our study highlights the Lagrangian transport of solid particles discharged at the Marseille Wastewater Treatment Plant (WWTP), located at Cortiou on the southern coastline. We focused on episodic situations characterized by a coastal circulation pattern induced by intrusion events of the Northern Current (NC) on the continental shelf, associated with SE wind regimes. We computed, using MARS3D-RHOMA and ICHTHYOP models, the particle trajectories from a patch of 5.10 Using the same method, and in order to compare our results with those described in [-term peak values reaching about 0.38 Sv. In addition, these 2 events presented different intensities and directions of velocity field. At the station located close to the southern coastline near the WWTP outlet (43.203°N / 5.362°E), the current velocity was greater in October 2011, with maximum values of 0.49 m.s-1 at 20 m depth, whereas maximum current velocities were 0.13 m.s-1 at 20 m depth in June 2008.Authors in  used theThese results confirm that the intensity of NC intrusions are not directly driven by SE winds conditions as shown by the authors of . In factOn the contrary, in June 2008, the intrusion of the NC is related to a downwelling induced by S-SE winds as described above and in the literature. Authors in  suggesteResults highlight that the northern and the southern bays of Marseille are not impacted in the same way, revealing that the connections of particles from the WWTP effluent result from the complex interaction between SE wind induced current fields and the circulation induced by intrusions of the NC on the shelf.Firstly, as seen in Figs Inversely, as seen in Figs Secondly, our results in In addition, the results in Figs Therefore, all these results should be displayed in the form of a conceptual diagram to present 2 modes of particle connectivity from the WWTP outlet to the inner shorelines of the bays, in both cases under periods of intrusion of the NC on the shelf, but depending on the S-SE or E-SE wind direction.black path), as studied in October 2011, which is characterized by higher angles of incidence (60°-90°) relative to the orientation of the southern coastline, locally induces a coastal circulation characterized by northwesterly currents , as studied in June 2008, which is characterized by lower angles of incidence (0°-40°) relative to the orientation of the southern coastline, locally induces a coastal circulation characterized by northward currents , along trajectories passing south of the Frioul archipelago without entering the inner bays [Firstly, under a SE wind regime but in the absence of intrusion of the NC on the continental shelf, the particles are directly and rapidly transported at the surface to the north-west , sink slightly deeper (< 10 m depth) under the effect of the wind induced downwelling that prevails along the southeastern coastline of the Frioul archipelago (thick black arrow). Then these particles continue to move rapidly northwards, passing west (east) of the Frioul archipelago to the extreme (inner) shorelines of the northern (southern) bay, which are reached in less than 30 hours .In a period of intrusion of the NC associated with a E-SE 80°-110° wind regime, as studied in October 2011, particles reaching the Frioul archipelago at the surface (red path) continue to move northwards at the same depth (about 20 m depth) on both sides of the Frioul archipelago, either to disperse throughout the southern bay according to the local anticyclonic circulation, or to reach the distant shorelines of the northern bay within approximately 8 days .By contrast, in a period of intrusion of the NC associated with a S-SE 130°-170° wind regime, as studied in June 2008, particles reaching the Frioul archipelago sub-surface (solid black path), sink deeper in the water column to about 20m depth (thick black arrow) that leads them to join the sub-surface (about 20 m depth) northward circulation of the intrusion of the NC, which enters deeper into the southern bay .Note that a fraction of the patch of particles that reach the southeastern end of the Frioul archipelago at the surface .In addition, as shown in Figs -surface depths, according to the angle of incidence of the SE winds, and resulting surface currents, with respect to the orientation of the southern coastline at the site of the WWTP outlet. In summary, an E-SE wind with higher incidence (direction < 120°) will induce delayed particle sinking and shallower and faster connectivity, especially effective in reaching the distant shorelines of the northern bay, while a S-SE wind with lower incidence (direction > 120°) will induce immediate particle sinking and deeper and slower connectivity, especially effective in reaching the inner shorelines of the southern bay.Although these 2 proposed modes of particle transport from the WWTP outlet to the bays of Marseille present a similar pattern, since they are both controlled by the intrusion of the NC within the bays, they differ essentially in the depth at which the particles are transported, and the resulting speed of their transport. In addition, it is interesting to note that our results identify 2 specific locations of downwelling, where particles from the WWTP outlet sink to sub13C stable isotope ratio, the sea surface POM, which arrived at Somlit on October 17, 2011, was probably constituted by a mixture of marine phytoplankton transported by the NC and detritus particles from the WWTP effluent. Moreover, the δ15N stable isotope ratio of POM at Somlit was particularly influenced by the POM from the WWTP plume. These particles are consumed by the zooplankton and integrate the pelagic food web particularly during the cold season  [13C = -25.23±1.16 ‰, δ15N = 1.77±0.25 ‰) is rather close to values of the POM from the WWTP effluent at Cortiou . The results of the present paper, relating to intrusions of the NC on the shelf and the high resulting impact of the particles from the WWTP effluent in the artificial reefs zone (Récifs), support this hypothesis.On the basis of the measurements of stable isotopes, our results confirmed that the POM at Somlit is partially constituted of particles transported from the WWTP effluent. As suggested by the δ winter) . These p winter) . A mixtu winter) . In factInterestingly, hydrodynamic circulation and stable isotope ratios could be used at the same time to better identify the respective contributions of the different seawater sources of POM. For example, in October 2001, at Somlit: 40% and 60% of the sampled POM may be attributed to particles from the WWTP effluent and marine phytoplankton, respectively. Thus, Lagrangian trajectories computed in this study confirm that a significant part of the particles from the WWTP effluent are effectively connected to Somlit (3–7%), and furthermore the study published by  showed tFrom a health point of view, Niolon is a diving and bathing site that is potentially at risk of being contaminated by the particles from the WWTP outlet. Finally, it is crucial that Rouet, which is the site of a Protected Marine Area, is almost never impacted by the potentially polluted particles. Joliette is a commercial harbour that is more likely to be polluted by vessel traffic than by particles from the WWTP effluent.In the southern bay, it should be noted that the sites the most impacted by the WWTP effluent are SE Frioul  and Récifs, each characterized by vulnerable human activities such as fish farming (SE Frioul) and a zone of artificial reefs for production (Récifs). In addition, we highlighted that the sites Récifs , and also Somlit , both located in the middle of the southern bay, were highly impacted by particles from the WWTP effluent, especially in June 2008. This result reveals that the particles from the WWTP can potentially be integrated into the pelagic and the benthic food webs within the southern bay, where professional and recreational fishing is highly developed. Finally, bathing areas such as Prophète, Prado and Madrague, located at the southeastern limit of the anticyclonic sub-surface circulation induced by the intrusion of the NC within the southern bay, remain weakly impacted by particles from the WWTP effluent.-surface circulation is too often under-estimated compared to the surface circulation, more intuitively considered, but very different from the deeper circulation and, in our case, ineffective in connecting sites located in the inner bays of Marseille. Our study highlights that the transport of particles from the WWTP effluent towards the inner shorelines of the bays of Marseille is not negligible. For each studied event, if we take together all the amounts of particles having connected the 10 vulnerable sites chosen around the northern and southern bays  and sub-surface (about 20 m depth) modes of particle transport, induced by intrusions of the NC on the continental shelf, associated with SE wind regimes. These modelling results are quite new and unexpected. In fact, the present study is of interest because the importance of the subays Figs , 7 and 8ays Figs  reveal tS1 DatasetS1A and S1B (netcdf) correspond to the ICHTHYOP computations of June 2008 and October 2011, respectively.(ZIP)Click here for additional data file.


The senescence-accelerated mouse prone 8 (SAMP8) model is characterized by accelerated, progressive cognitive decline as well as Alzheimer’s disease (AD)-like neurodegenerative changes, and resembles the etiology of multicausal, sporadic late-onset/age-related AD in humans. Our aim was to find whether these AD-like pathological features, together with the cognitive deficits present in the SAMP8 strain, are accompanied by disturbances in cortical network activity with respect to control mice  and, if so, how the alterations in cortical activity progress with age. For this purpose, we characterized the extracellular spontaneous oscillatory activity in different regions of the cerebral cortex of SAMP8 and SAMR1 mice under ketamine anesthesia at 5 and 7 months of age. Under these conditions, slow oscillations and fast rhythms generated in the cortical network were recorded and different parameters of these oscillations were quantified and compared between SAMP8 and their control, SAMR1 mice. The average frequency of slow oscillations in SAMP8 mice was decreased with respect to the control mice at both studied ages. An elongation of the silent periods or Down states was behind the decreased slow oscillatory frequency while the duration of active or Up states remained stable. SAMP8 mice also presented increased cycle variability and reduced high frequency components during Down states. During Up states, the power peak in the gamma range was displaced towards lower frequencies in all the cortical areas of SAMP8 with respect to control mice suggesting that the spectral profile of SAMP8 animals is shifted towards lower frequencies. This shift is reminiscent to one of the principal hallmarks of electroencephalography (EEG) abnormalities in patients with Alzheimer’s disease, and adds evidence in support of the suitability of the SAMP8 mouse as a model of this disease. Although some of the differences between SAMP8 and control mice were emphasized with age, the evolution of the studied parameters as SAMR1 mice got older indicates that the SAMR1 phenotype tends to converge with that of SAMP8 animals. To our knowledge, this is the first systematic characterization of the cortical slow and fast rhythms in the SAMP8 strain and it provides useful insights about the cellular and synaptic mechanisms underlying the reported alterations. Sin vitro . The analysis of SO provides information about different parameters of the cortical function  and has been used before for the characterization of different mouse models of disease  and 7-month-old  adult female mice were included in the study of cortical electrophysiology. Mice were cared for and treated in accordance with Spanish regulatory laws , which comply with the European Union guidelines on protection of vertebrates used for experimentation (Strasbourg 3/18/1986). All experiments were approved by the Ethics Committee at the Hospital Clinic . Mice were kept under standard conditions , with food  and water available ad libitum throughout the study.The SAM mouse was originally generated from AKR/J mice at the University of Kyoto by Dr. Takeda Takeda, . The mic−1 · h−1) was delivered subcutaneously with a pump to maintain a constant level of anesthesia  and medetomidine (1.3 mg/kg). Atropine (0.3 mg/kg) and methylprednisolone (30 mg/kg) were administered subcutaneously to prevent respiratory secretions and inflammation, respectively. A tracheotomy was performed to increase stability during the recordings. After this procedure, the mouse was placed in a stereotaxic frame, and air enriched with oxygen was delivered to the mouse through a thin silicon tube placed at 0.5–1 cm from the tracheal cannula. Continuous infusion of ketamine  of the Up-Down state period, the population FR and the non-linear sample entropy (SampEn). Detection of Up and Down states from the recorded signals was based on three main fingerprints of the Up states: the slow LFP deflection, the gamma rhythm and the neuronal firing. These three features are reflected in three different time series: (1) the SO envelope; (2) the envelope of the variance of the gamma-filtered LFP  and waves involving less than 10 channels were rejected. The average of the onset times of the same wave was taken as reference to compute the array of relative time lags. In some cases, highly noisy channels were not included in the analysis. However, in all the experiments we used at least 10 electrodes. We explored the possible existence of different patterns of activity propagation by clustering the arrays of relative time lags in five groups using k-means. For each group of waves and for each electrode, we carried out the average time lag and its standard error mean (SEM). For each recording and for each group the speed of wave propagation was computed by dividing the distance between electrodes showing maximum and minimum average time lags by their time lag difference. For each recording, the speed of wave propagation was the mean of the five groups, weighted by the proportion of Up states contained in each of them.m, r, N) is the negative natural logarithm of the conditional probability that two sequences of length N, similar for m points, remain similar, that is, within a tolerance r, at the next point, where self-matches are not included in calculating the probability .Comparisons between groups and ages were performed separately for each cortical area with the Student’s top). As has been previously described . Different parameters of the oscillatory activity were quantified  and 7 months of age , the differences between groups being larger in primary cortical areas  at 5 months old. Expanded raw LFP traces , the difference with respect to control mice was of greater magnitude for Down state duration , and persisted and was emphasized at 7 months, being statistically significant in all the cortical areas separately  and 7 months of age , differences between groups when considering each cortical area separately were only significant in the S1 cortex of 7 month-old animals  and 7 months of age . This increase in cycle variability was driven by the primary cortices, while it remained rather constant in PrL cortex, which displayed the maximal regularity among the studied areas and showed no differences between and within groups at any of the studied ages. Conversely, the CV of the SO in primary cortical areas was higher in SAMP8 than in control animals, and increased in the transition from 5 months to 7 months of age in both groups, although this increase was of higher magnitude in SAMP8 mice  and 7 months of age , the differences between groups being larger in 7-month-old animals. Smaller differences were observed in the FR during the Up state . However, these differences were less consistent than those occurring in the Down state. Furthermore, the FR during the Down state decreased in the transition from 5 months to 7 months of age in both groups , while it presented no differences at 7 months old , as this synchronization has been widely linked to cognitive and perceptual processes Wang, . This ansolid lines), SAMP8 mice presented an overall increase of power in the lower range of the beta-gamma band compared to control mice. This increase was also accompanied by a trend towards reduced power in the upper range, thus giving the impression that the spectral profile of SAMP8 mice was shifted towards lower frequencies. In fact, the power peak in the excess power of the Up states appeared displaced towards lower frequencies in SAMP8 compared to control mice at both studied ages and all the four cortical areas . Modulations in the beta-gamma band could be observed in both groups of animals in PrL cortex but, unlike control mice, the synchronization of the cortical activity in the beta-gamma range did not form a distinguishable modulation in the primary cortical areas of the SAMP8 group, suggesting reduced beta-gamma rhythmicity in these animals. Furthermore, control animals showed another modulation in the upper gamma range during both Up and Down states that was highly attenuated in the transition from 5 months to 7 months old, a modulation that was not present in the SAMP8 group at any of the studied ages. As mice got older, high frequencies during the Up states displayed different behaviors in PrL and primary cortices depending on the group. The power peak in PrL increased in both control and SAMP8 animals, and shifted to lower frequencies in the second ones . Conversely, the displacement to lower frequencies occurred in the primary cortical areas for the control group, while the peak in these areas tended to remain stable in SAMP8 mice. Special attention to the accentuated overall larger power in the S1 area of 5-month-old SAMP8 mice is warranted . Furthermore, SAMR1 and SAMP8 animals exhibited significant reductions of power in the transition from 5 months to 7 months of age, even though the power of high frequencies during the Down state was always lower in SAMP8 than in control mice  rhythms were quantified and compared between SAMP8 mice and its control, SAMR1. Our experiments show that SAMP8 mice present disturbances in the cortical network activity when compared with SAMR1 mice, and that the electrophysiological phenotype of SAMR1 at 7 months old tends to approach that of SAMP8 at 5 months old.SO recorded in the cerebral cortex of SAMP8 mice were slower than those of control mice. Although both Up and Down states tended to be longer in the SAMP8 strain, Down state elongation was the most robust and consistent difference across ages, a finding coincident with SO alterations reported in a mouse model of tauopathy  abnormalities in AD patients is a shift of the power spectrum to lower frequencies Jeong,  and thisAn increase in cortical excitability has been extensively described in mouse models of AD, which have a marked tendency to suffer epileptic seizures  mice and that the electrophysiological phenotype of control mice at 7 months of age tends to approach the phenotype of SAMP8 mice at 5 months of age. To our knowledge, this is the first systematic characterization of the cortical slow and fast rhythms in the SAMP8 model of early aging. We find that this approach is valuable to identify alterations in the cortical emergent activity of SAMP8 mice and, more generally, can provide useful insights about the cellular and synaptic transformations associated with aging and neurodegenerative diseases such as AD. The detected alterations may contribute to the SAMP8’s accelerated, progressive cognitive decline and may be related to other AD-like neurodegenerative changes previously reported in this mouse model. Despite the differences between the SAMP8 model and patients with Alzheimer’s disease, our findings highlight the electrophysiological similarities and therefore emphasize the value of the SAMP8 strain as a model for studying AD.PC-P, MVS-V and RME designed the study. PC-P carried out the experiments, participated in the analysis and wrote the article. LP-M, MP-Z and PC-P carried out the data analysis. MVS-V supervised experiments and analysis. All authors participated in the scientific discussion and in the article writing.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Early-life respiratory tract infections (RTIs) and dental caries are among the most common infectious diseases worldwide. The relations between early RTIs and development of caries in permanent teeth have not been studied earlier. We assessed childhood RTIs as potential predictors of caries in young adulthood in a 20-year prospective population-based cohort study (The Espoo Cohort Study). Information on lower respiratory tract infections (LRTIs) that had required hospitalization was retrieved from the National Hospital Discharge Registry (n = 1623). Additional information on LRTIs and upper RTIs (URTIs) was assessed based on the questionnaire reports that covered the preceding 12 months. Caries was measured as the number of teeth with fillings  reported in the 20-year follow-up questionnaire. The absolute and relative excess numbers of FT were estimated applying negative binomial regression. The mean number of FT in young adulthood was 1.4 greater among subjects who had experienced LRTIs requiring hospitalization before the age of 2 years (SD 4.8) compared to those without any such infections (SD 3.4), and the adjusted relative excess number of FT was 1.5 (95% CI 1.0–2.2). LRTIs up to 7 years were associated with an absolute increase of 0.9 in the mean FT number, the adjusted relative excess being 1.3 (1.0–1.8). Also the questionnaire-based LRTIs  and URTIs  before the age of 2 years predicted higher occurrence of FT. Findings suggest that early RTIs have a role in the development of dental caries in permanent teeth. Dental caries is an infectious disease which affects most of the people during at least some point in their life ,2. In thThere is some evidence suggesting that the occurrence of middle ear and respiratory tract infections (RTIs) during the early childhood increases the risk of developing childhood caries  and/or dThe primary objective of the present study was to assess the relations between the occurrence of RTIs before the eruption of the permanent teeth (from birth up to the age of 7 years) and the development of caries, measured as the number of FT in young adulthood. The secondary objective was to elaborate whether a more specific timing of RTIs plays a role in the magnitude of the studied relations i.e. modifies this effect.The source population included all children in the city of Espoo who were born between January 1, 1984, and March 31, 1990. Espoo, located near the western border of Helsinki, is the second largest municipality in Finland, with a population of 269 500 in 2015. A baseline questionnaire was mailed in March 1991 to all parents of a random sample of children drawn from the roster of Finland’s Statistical Center ,13. The The health outcome of interest was caries, measured as the number of FT in young adulthood. In the 20-year follow-up this was determined based on the study subject’s answer to the question: “Estimate, how many teeth with a filling you have?”The information on LRTIs leading to hospitalization, from birth to the age of 7 years, was retrieved from the National Hospital Discharge Register using a computerized record linkage, with the Finnish personal identification number as the key. This register includes the dates and causes of all hospitalizations  of Finnish citizens that have occurred since January 1969. The diagnoses were coded applying the International Classification of Diseases (ICD), Eight Revision, between 1969 and 1986, and the Finnish version of the ICD-9 between 1987 and 1995 while the ICD-10 was applied since 1996. RTIs requiring hospitalization included all the main diagnoses of LRTIs, including pneumonia and acute bronchitis . The subth percentile cut-off point of at least 4 infections (coded 1), while less than 4 infections formed the reference category (coded 0). For acute otitis media, the corresponding cut-off point was at least 2 infections (coded 1) versus fewer than 2 infections (coded 0). For other RTIs, the cut-off point was at least 1 infection (coded 1) versus no infection (coded 0). RTIs were broken down to LRTIs (including acute bronchitis and pneumonia) and URTIs .At the baseline questionnaire, the information on RTIs was acquired by asking: “How often did the child experience the following infections during the past 12 months?” The list of infections included common cold, tonsillitis, sinusitis, acute otitis media, acute bronchitis, and pneumonia. To judge the relative frequency of common cold, we used the 75The following variable were included in the analyses as potential confounders: family socioeconomic status at baseline , age, geOur overall aim was to assess the relations between the experience of childhood RTIs and the occurrence of caries in young adulthood. This was performed by comparing the mean FT values among subjects with RTIs to the mean FT among subjects with no such infections. The absolute difference in the mean FT values as well as the relative excess number of FT, along with 95% confidence interval (CI), were estimated by negative binomial regression . In this analysis, the number of FT was used as the response variate and identity and logarithmic links to produce estimates of absolute and relative excess, respectively. The potential confounders described above were adjusted for in the multivariable models.In the main analyses (n = 1623), we estimated the absolute and relative excess numbers of FT among children with LRTIs requiring hospitalization vs children with no such LRTIs. We studied two age periods (i.e. less than 2 years and 2 to 7 years) separately to elaborate potential difference in the influence of hospitalized RTIs in different age periods on the risk of caries later in life. In the multivariable model, we were able to consider the independent effect of LRTIs in a certain age period by including the occurrence of LRTIs later and/or before the time period under consideration in the model.In additional analyses (n = 268), we estimated the absolute and relative excesses of FT among subjects with questionnaire reported LRTIs and/or more than the cut-off point of URTIs (exposure categories) and compared those to no LRTIs and fewer than the cut-off point of URTIs (reference category) during the 12 months preceding the baseline data collection. We restricted these analyses to children less than 2 years of age at baseline to minimize the influence of missing information on infections before the data collection started.There were no substantial differences between the baseline population, this study population, and those lost to follow-up . The meaWhen we studied two different age periods see , the greThe role of questionnaire-reported RTIs during the first 2 years of life was assessed among children who were less than 2 years old at baseline (n = 268) . The meaThe results of our population-based prospective 20-year cohort study suggest that the occurrence of RTIs in the early childhood has a role in the development of an increased number of FT detectable in young adulthood. The increased FT number in young adulthood was found to be related to the LRTIs leading to hospitalization up to the age of 7 years. Especially in early childhood up to 2 years of age, a significant association was found, as the occurrence of LRTIs requiring hospitalization increased the mean FT number by 1.5. The association was detected especially in relation to the experience of acute bronchitis requiring hospitalization, which increased the mean FT number to >7. In addition, questionnaire-reported LRTIs and URTIs before the age of 2 years were associated with 0.8 to 0.9 higher mean FT. These findings provide evidence that early-life RTIs are associated with the number of FT in young adulthood, and therefore, may affect the development of dental caries in permanent teeth.RTIs have earlier been linked to the developmental enamel defects , and sucThe strengths of our study include the prospective follow-up of a large population-based cohort from early childhood to the ages of 20–27 years. The response rate at baseline was high (80.3%), and in the 20-year follow-up it was relatively high (63.2% of the baseline study population). There were no substantial differences between the baseline population and the present study population based on the 20-year follow-up , suggestUsing a questionnaire-reported FT number rather than medical records as a source of information on dental caries may have introduced some measurement error and therefore, could be a weakness of this study. However, the questionnaire-reported FT frequencies in our study are remarkably consistent with those reported by another study of 13819 Finnish military recruits aged 19 to 21 years, whose oral health was screened by dentists in a garrison . In thatInformation on the frequency and type of LRTIs was based on the National Hospital Discharge Register database. It has been consistently evaluated to maintain highly complete and reliable data ,29. In aStreptococcus mutans [We were able to adjust our analyses for a number of potential confounders. For example, socioeconomic status has been reported to be one of the most important determinants of dental caries . We deals mutans  and diets mutans . In addis mutans  and the s mutans , have bes mutans , and ours mutans  (i.e. ass mutans . Future According to our systematic literature search, only two previous studies have directly assessed the relation between RTIs and caries of non-permanent teeth. Alaki et al. examined the risk of early childhood caries up to age of 3 years in children who had experienced respiratory or middle ear infections during the first year of life. They found as increased risk of deciduous caries in children who were diagnosed with acute otitis media or RTI before the age of 1 year . A case-Our finding showing that the experience of RTIs during early childhood is associated with the number of FT up to 20 to 27 years of age is first of its kind. These results are important from the public health perspective, as RTIs and dental caries are the two most common infectious diseases in middle and high income countries and common also in low income countries. The results suggest that early-life RTIs may be relevant for the development of permanent teeth, and therefore, may affect the development of dental caries.


The AER was used as a partial replacement for sand in the mortar specimen. The mortar specimen was coated with epoxy, except for an exposed surface, and then immersed in a NaCl solution for 140 days. The chloride content in the mortar specimen was characterized by energy dispersive X-ray fluorescence analysis and electron probe microanalysis. The results showed that the AER could adsorb the chloride ions from the solution rapidly but had a relatively low performance when the pH of its surrounding environment increased. When the AER was mixed in the cement mortar, its chloride content was higher than that of the cement matrix around it, which confirms the chloride ion adsorption capacity of the AER.This paper presents the effect of anion exchange resin (AER) on the adsorption of chloride ions in cement mortar. The kinetic and equilibrium behaviors of AER were investigated in distilled water and Ca(OH) There are concerns with respect to the durability of reinforced concrete structures in marine environments. In marine environments with high chloride contents, chloride ions actively penetrate into the reinforced concrete, which induces corrosion in the reinforcing bars inside the concrete. Therefore, many discussions and studies have been conducted to prevent the penetration of chloride ions into concrete and inhibit the corrosion of reinforcing bars .The diffusion of chloride ions into concrete is largely dependent on permeability, which is governed by porosity and pore size distribution ,3,4. Fur− and SO42− and/or CO32− are combined between two layers of the AFm phases, which are formed by the hydration of Portland cement. In environments with a high chloride ion concentration, the chloride ions can be exchanged with the internal anions and combined between the layers [The AFm phases belong to a family of layered double hydroxide compounds in which anions are combined between two positively charged layers . Generale layers ,11. There layers ,13,14,15+ cation exchange resin on the hydration of C3S were reported in [This study was focused on the applicability of anion exchange resin (AER) to adsorb chloride ions. Ion exchange resin is widely used for the removal of harmful ions in the water treatment field and in the production of ultrapure water for semiconductor and liquid crystal display (LCD) cleaning ,17. In torted in . The AERorted in . Moreoveorted in . However+(CH3)2C2H4OH functional group and a polystyrene-divinylbenzene polymer. The OH− is bound to the functional group. The density of the AER is approximately 1.13, and the diameter is 300–1000 μm. The total ion exchange capacity of the AER is 1.3 eq·L−1.The structure of ion exchange resin typically has a functional group that is combined with a polymer. Depending on the charge of the functional group, it is necessary to determine whether a cation or an anion is combined with the ion exchange resin. As shown in 3 potentiometric titration method.The direct evaluation of ion exchange reaction of the AER is challenging when it is mixed with cement mortar. If the evaluation of the reaction behavior and the equilibrium relation between the AER and chloride ions in solution is prioritized, the principle of the AER reaction in cement mortar can be inferred from the solution test. In this study, the ion exchange reaction of the AER was performed in chloride solutions. The reaction of the AER in the chloride solutions was evaluated using kinetic equations and isotherm adsorption equations. All solutions were prepared at a water-to-solid ratio of 40. The solution was stirred to a homogenous condition using a magnetic stirrer. After each reaction under the experimental conditions, the solution and ion exchange resin were separated using a vacuum filtration apparatus. The chloride concentration of the reacted solution was measured with a titrator  using the AgNO2 saturated solution. The Ca(OH)2 saturated solution represented the environment of concrete pore solution. The pH of Ca(OH)2 saturated solution was measured using a pH meter . The initial pH of Ca(OH)2 saturated solution was 12.34. The chloride concentrations of the solution were measured after the AER reacted with the chloride solution for 1, 3, 10, 30, 60, and 120 min, respectively. The chloride concentration adsorbed on the AER was calculated by subtracting the measured chloride concentration in the reacted solution from the initial chloride ion concentration. The concentration of adsorbed chloride ion over time was curve-fitted using a pseudo first-order reaction equation (Equations (1) and (2)) and a pseudo second-order reaction equation (Equations (3) and (4)) to evaluate the kinetic property of the AER ,25,26,27t (mg Cl−/g resin), −/g resin), t is the reaction time (min).Equations (1) and (2) are given as follows:t (mg Cl−/g resin), −/g resin), − min) and t is the reaction time (min).Equations (3) and (4) are given as follows:2 saturated solution were used again as solvents. The reaction time between the AER and the chloride solution for the equilibrium test was 120 min. The reaction time was considered on the basis of the results of the kinetic test. Two hours was considered to be sufficient time to reach the equilibrium state in the distilled water and Ca(OH)2 saturated solution. The adsorbed chloride ions were curve-fitted depending on the free chloride ions using the Langmuir adsorption isotherm equation (Equations (5) and (6)) and the Freundlich adsorption isotherm equation (Equations (7) and (8)) to evaluate the equilibrium property of the AER [ the AER ,26,27,28−/g resin), −/g resin), Equations (5) and (6) are given as follows:−/g resin), n), n is the experimental parameter which represent the heterogeneity of the adsorption sites.Equation (4) is given as follows:3. The mortar specimens were demolded after one day and then cured for another 27 days in an environmental chamber with constant temperature and humidity, 20 °C and 60% RH, respectively.Type 1 Portland cement , Korea standard (KS) sand, and the AER were used to prepare mortar specimens according to the ASTM C 1329 standard. A NaCl solution was prepared for an immersion test by mixing 3.2 wt % CP-grade NaCl  in distilled water. The mortar specimen was coated with epoxy after 28 days of curing, except for the surface where the NaCl solution penetrates into, as shown in EDXRF analysis was conducted to investigate the major atoms in the mortar specimens according to the depth from the exposed surface using a Thermo Scientific ARL QUANT’X EDXRF spectrometer . The oxide contents of Na, Al, Si, S, Cl, K, and Ca were measured in a vacuum condition. The excitation of low Za  was performed at 4 kV, and that of low Zb  was performed at 8 kV. The Za and Zb are the nuclear charge numbers of the cation and anion, respectively. The diameter of the X-ray spot was approximately 1 mm. The measured spots were 2, 6, 10, 14, 18, 22, 26, 30, and 34 mm from the exposed surface, as shown in −1. An area of 12 × 12 mm was scanned, and then the scanned image was electronically stitched together to create a composite image [EPMA was conducted to supplement the EDXRF results and obtain an image of the chloride profile. Cl and K were only analyzed to reduce the measurement time. The EPMA instrument was a Shimadzu EPMA-1720 . The mortar specimen was cut to a size of 20 × 40 mm, as shown in te image .2 saturated solution. After the equilibrium was reached, the chloride contents adsorbed on the AER were lower in the Ca(OH)2 saturated condition than in the distilled water condition. The kinetic property of the AER can be easily seen in the 2 saturated solution. In the physisorption, the binding energy was dependent on the polarizability and, therefore, a weak Van der Waals interaction appeared. On the other hand, electron transfer or electron sharing occurred between the ions to form a strong bond in the chemisorption [+(CH3)2C2H4OH functional group and anions were bonded by an electrostatic force; however, as the polarity of the organic molecule was not as strong as that of the inorganic molecule, the reversible and fast reaction characteristic of physisorption appeared to exist. Moreover, OH− acted as a competing ion of Cl− in the Ca(OH)2 saturated solution, and, thus, the time to reach the equilibrium state was delayed and the adsorbed Cl− content could decrease. The linear equation was investigated further.The pseudo first-order reaction could be observed in the polarization-dependent physisorption, whereas the pseudo second-order reaction could be observed in the chemisorption, in which strong chemical bonding occurs ,22. ThusK1 is clearly distinguished between the types of the solution. The K1 in the distilled water and the Ca(OH)2 saturated solution is 0.5412 and 0.0380, respectively, which shows the kinetic performance is more predominant in the distilled water than the Ca(OH)2 saturated solution. When the ion adsorption is interfered with the pore diffusion, it may not be linear curve in the pseudo first reaction [− can interfere with the Cl− adsorption in the Ca(OH)2 saturated solution, the linear curve may have little agreement with pseudo first reaction. The coefficient of determination (R2) of the curve fitted by Equation (1) was similar to that of the curve fitted by Equation (3) in the distilled water; however, it was lower in the Ca(OH)2 saturated solution. − decreases in the Ca(OH)2 saturated solution unlike the reaction . Since t2 saturated condition, the ion exchange reaction of the AER could be more dependent on the chemisorption. In this study, the ion exchange reaction of the AER is as follows:Therefore, if there was a competing ion like in the Ca(OH)2 saturated solution than in the distilled water across the most range of chloride concentration. The R2 of the curve fitted by non-linear Langmuir isotherm (Equation (5)) was higher than that of the curve fitted by non-linear Freundlich isotherm (Equation (7)). Considering the only R2 of the fitted curve, we can conclude that the ion exchange reaction of the AER to be more consistent with the Langmuir adsorption isotherm than with the Freundlich adsorption isotherm. However, the fitted curve (Langmuir-) appeared to underestimate at the highest chloride condition. It is showed that the fitted curve (Langmuir-) may be proper at the low chloride concentration (below 4000 mg/L) whereas the fitted curve (Freundlich-) may be suitable at the high chloride concentration (above 4000 mg/L). The linear equation was investigated further.The amount of adsorbed chloride ions was lower in the Ca(OH)− ion may affect the homogenous adsorption. − ion on the Freundlich isotherm. The R2 of the fitted curve in the Ca(OH)2 saturated solution was relatively higher than that of the fitted curve in distilled water. Since the OH− ion may give rise to the heterogeneity on the surface of the AER, the Freundlich isotherm may show the good agreement in the Ca(OH)2 saturated solution. However, the amount of adsorbed chloride ion was low in all ranges of Ca(OH)2 saturated solution than distilled water although Freundlich isotherm shows the increase in the amount of adsorbate as the concentration at equilibrium increases. It is why the OH− ion acts as a competing ion which is affected by the ion selectivity coefficient [fficient .In conclusion, when the AER is used in the cement mortar, the adsorption of chloride ions by the AER is expected to occur more rapidly because the time to reach the adsorption equilibrium in the reaction between the AER and the chloride ions is faster than in the reaction between hydration products of cement and chloride ions ,12. Howe2. Additionally, the sulfur content of the matrix was considered for the reliability of the EDXRF results because the initial sulfur content of the matrix is not influenced by the chloride ingress [ ingress . Although the chloride ion content of PC and AC did not exhibit a large difference, the chloride ion content of AR was higher than those of PC and AC at the same depth. Moreover, the chloride content of AR was much higher than that of the cement matrix (PC and AC) as it became closer to the exposed surface. The chloride ion content of the AR could be high because the AER has a higher driving force than that of the cement matrix, thus reducing the time to reach the adsorption equilibrium and increasing the chloride binding capacity ,12,22,23The chloride ion contents of PC and AC were similar. However, the chloride ion content of AR was higher than that of the cement matrix (PC and AC). This indicates that the AER could adsorb the chloride ion from the pore solution and that it had a better performance in the chloride adsorption than in the hydration products in the matrix. However, it should be noted that the total chloride content that penetrated into the specimen could be higher in AC than in PC. Since the mortar specimens were immersed in the chloride solution for 140 days, the pore solutions were fully saturated. Chloride ions can be easily diffused owing to the driving force caused by concentration gradients . In the As the EDXRF results were obtained from manually selected spots, which makes their representativeness questionable, an image analysis of the entire area was performed using EPMA to supplement the EDXRF results. 2 saturated solution—both containing chloride ions. The effects of the AER on the chloride adsorption in the mortar specimen were investigated as well. The adsorption of chloride ion around the AER was dependent on the driving force induced by an electrostatic force of the AER and a concentration gradient of chloride ion. 2 saturated solution. Since the hydroxyl ions could act as competing ions in the Ca(OH)2 saturated solution, which represent alkaline environments, the equilibrium time for adsorbing chloride ions was delayed and the adsorbed chloride ion content was reduced. The AER could adsorb chloride ions in both the distilled water and the Ca(OH)The chloride ion content was higher in the AER than in the matrix around the AER. However, the chloride ion content of the matrix was not largely different in the mortar specimens with and without the AER. The chloride ion content in the AER was higher than that in the matrix because the AER had a higher driving force than that of the cement matrix, thus reducing the time to reach the adsorption equilibrium and increasing the chloride binding capacity. The AER could successfully reduce the free chloride ions in the pore solution.This study has demonstrated the kinetic and equilibrium behaviors of the AER in distilled water and a Ca(OH)


This study aimed to evaluate the influence of the NiTi wire in Conventional NiTi  and Controlled Memory NiTi (ProTaper Gold PTG) instrument systems on the quality of root canal preparation. Twelve mandibular molars with separate mesial canals were scanned using a high-definition microcomputed tomography system. The PTU and PTG instruments were used to shape twelve mesial canals each. The canals were scanned after preparation with F2 and F3 instruments of the PTU and PTG systems. The analyzed parameters included the remaining dentin thickness at the apical and cervical levels, root canal volume and untouched canal walls. Data was analyzed for statistical significance by the Friedman and Dunn’s tests. For the comparison of data between groups, the Mann-Whitney test was used. In the pre-operative analysis, there were no statistically significant differences between the groups in terms of the area and volume of root canals (P>.05). There was also no statistically significant difference between the systems with respect to root canal volume after use of the F2 and F3 instruments. There was no statistical difference in the dentin thickness at the first apical level between, before and after instrumentation for both systems. At the 3 cervical levels, the PTG maintained centralization of the preparation on the transition between the F2 and F3 instruments, which did not occur with the PTU. Conclusion The Conventional NiTi (PTU) and Controlled Memory NiTi (PTG) instruments displayed comparable capabilities for shaping the straight mesial root canals of mandibular molars, although the PTG was better than the PTU at maintaining the centralization of the shape in the cervical portion. The aim of this step is to remove vital or necrotic pulp tissue while simultaneously increasing the root canal volume to facilitate the decontamination of the root canal system by irrigants and medicaments18. Because of the known limitations of hand-held, stainless steel instruments , nickel-titanium (NiTi) instruments have been widely used in endodontic practice due to their relatively greater accuracy and efficiency compared to hand-held instruments24. NiTi rotary files have significantly better flexibility and cutting abilities and provide higher quality in the preparation of root canals with low risk of deviation5and higher fracture resistance to cyclic and torsional fatigue25.Several types of instruments and techniques for root canal preparations have been described20. Among the new NiTi wires now available on the market with the above-mentioned modifications, the CM wire is highlighted in the present study.NiTi wires have undergone various modifications in fabrication, including different types of thermic treatments that have been employed during the manufacturing process, which are designed to optimize physical characteristics that favor greater elasticity as well as increased flexibility and resistance22. Additionally, because of the thermic treatments used during the manufacturing process, CM wire instruments do not bounce (rebound) to their original shape after being flexed. This characteristic, which is associated with greater flexibility, can improve the quality of the root canal preparation by reducing the risk of deviation, instrument fracture, and perforations15.According to the manufacturers, CM wire instruments have a lower percentage of Nickel (by weight) than other NiTi instruments24. It has a variable taper along the length of the instrument, a convex triangular cross-section, and a sharp tip13. Another system, the PTG , was recently introduced to the market and has characteristics that are generally similar to those of the PTU, except that the PTG uses CM wire, while the PTU uses conventional NiTi wire. Because of this distinction, the PTG exhibits higher flexibility and greater resistance to cyclic fatigue than the PTU system13.Among the NiTi systems, the PTU  is a rotary system of conventional NiTi wire that has been widely used and studiedThe aim of the present study was to evaluate the influence of the NiTi wire in PTU and PTG instruments on the quality of root canal preparation, as assessed by microcomputed tomography (micro CT). The null hypothesis evaluated was that the type of NiTi wire has no influence on the root canal preparation.23, with distinct main foramens, and maximum curvature of 5°19.One hundred extracted human mandibular molars with complete apexes were selected. The teeth were scanned using a high-definition micro CT system . Twelve teeth were selected based on the following attributes: root canal anatomy classified as Vertucci type IVThe teeth were scanned as follows: 19 µm voxel size, 50 kV, 800 µA, and 0.8° step-size rotation using a 1024x1304 resolution. The obtained images were reconstructed with dedicated software  and saved in axial sections in BMP format. The images were used to observe the root canal configuration and its initial volume.A single operator performed all procedures. The access cavities were conventionally performed, and the root canal lengths were determined by the insertion of #10 K-files  until visualization in the apical foramen with a stereomicroscope . The working length (WL) was established as being 1 mm shorter than the real root canal length (RL). The #10 and #15 K-Files  were used in the WL before instrumentation with the rotary systems. Next, 6 mesio-buccal and 6 mesio-lingual canals in different teeth (n=12) were instrumented using the PTU system as follows: S1 (18/.02) and SX (19/.035) instruments in the cervical preparation and the S1 (18/.02), S2 (20/.04), F1 (20/.07), and F2 (25/.08) instruments were used in the WL, according to the manufacturer’s instructions.The remaining root canals (n=12) were instrumented using the PTG system in the same sequence as the one used for the PTU group. Subsequently, the roots were scanned again as in the initial evaluation. After scanning, the root canals were prepared with the F3 (30/.09) instrument of each system. The X-Smart Plus motor  was used with a specific torque and velocity for each instrument, in accordance with the manufacturer’s instructions, and the instrumentation was performed with in-and-out motion strokes in an apical direction. For the irrigation procedure, a 2.5% sodium hypochlorite solution was used; the root canals were irrigated before, during, and after instrumentation. Two milliliters of solution were used between each instrument change. The final irrigation was made with 3 mL of 17% EDTA for 3 minutes, and then with 3 mL of saline solution. Next, a new scan of the roots was performed using previously set parameters.The CTAn v.1.12 software (Bruker-microCT) was used to measure the canal volumes as well as the dentin thickness in the mesial and distal walls in the cervical and apical portions. For pre- and post-operative measurements, images of 3 different slices of the cervical third were evaluated; the first slice was 1 mm below the level of bifurcation, and the other 2 slices followed apically at intervals of 1 mm. In the apical third, the first slice was obtained at 1 mm from the apical foramen and the other 2 slices followed cervically at 1 mm intervals. The minimal dentin thickness of the mesial and distal walls of the root canals was measured in millimeters. The CTAn v.1.12 software was used to measure the canal volume between the 1 mm apical level and at 1mm below the root furcation.11. The data was then converted and presented as: (a) percentage (%) of dentinal removal, (b) un-instrumented area, and (c) relative volume increase between groups.For analysis of the un-instrumented area, 3D models were created with color codes, and the pre- and post-operative images were recorded using automatic image registration. Prepared areas and stripes of the canals were compared using the CTVol v. 2.2.1 software (Bruker-microCT). The intact surface area of the canal was determined based on the number of static objects; i.e., markings present in the same position on the surface of the root canal before and after instrumentationP<0.05).The Shapiro-Wilks test was used to assess normality of the non-parametric data. Results of the volume increase, dentin thickness, and un-instrumented areas were compared using the Friedmann and Dunn’s tests for the intra-group analyses. For analysis of the percentage of dentinal wear, un-instrumented areas, and volume increase between the groups, the Mann-Whitney test was used. The level of significance was established at 5% (P>0.05), indicating adequate pairing of the root canals. 3) and surface area (mm2) before and after use of the F2 and F3 instruments. Also presented in P>0.05). However, upon intra-group analysis of the PTU group, a statistically significant difference was observed between the pre-operative and post-operative volumes, but only after use of the F3 instrument (P<0.05). For the PTG group, a statistically significant difference was found between the volumes before and after use of the F2 and F3 instruments (P<0.05). In the pre-operative analysis, there were no statistically significant differences in the area or volume of root canals between the PTU and PTG groups (P>0.05). At the 3 cervical levels, the PTG system maintained centralization of the preparation on transition between the F2 and F3 instruments, in contrast to the PTU system where this did not occur.For all segments that were evaluated, a dentin thickness of less than 0.4 mm was found regardless of the instrument and system used .With respect to the specific root canal anatomy that was targeted for analysis in the present study, the data supports the null hypothesis because there were no statistically significant differences between the PTU and PTG instruments with respect to root canal enlargement or un-instrumented areas.23. This experimental model allowed us to compare the capabilities of two instrument systems based on the same anatomical condition18.After a micro-CT evaluation, the mandibular molars to be examined were selected based on whether they: (a) had two canals in the mesial roots, (b) presented distinct foramens and (c) had no isthmuses related to type IV of Vertucci’s classification8; however, these methods compromise the integrity of the samples because they require the cutting of the specimens, which limits specimen use to a single analysis. By contrast, micro-CT is a nondestructive method that allows for the progressive evaluation and observation of the preparation instruments with different kinetics18. The evaluations conducted in the present study were made after the use of the F2 and F3 instruments.Several methodologies such as histologic sections, serial axial sections, and scanning electron microscopy have been used to evaluate root canal preparations14. With technological advancement, however, new generations of instruments have been developed with different cross sections, diameters, tapers, and blades that have various cutting angles. Interestingly, the most recent advances have been directed towards improvements of the NiTi wire, whereby subtle changes in the proportion of metals, and in thermomechanical treatments have enabled the development of instruments with greater flexibility and fracture resistance when compared to their previous generations13. For instance, the CM wire is widely used in rotary instruments because it has greater flexibility than conventional NiTi wires22. The CM wire is manufactured using a complex heat treatment, with variations in wire composition; i.e., it has a lower percentage (52% by weight) of nickel than the most commonly used wire, which is composed of 54.5 to 57% of nickel (by weight)21. The PTU and PTG systems share a similar design, but they vary in the composition of the NiTi wire. One study assessed the shaping ability of these two systems, and found that the PTG produced less transportation and maintained more dentin than the PTU11.Although rotary NiTi instruments are flexible, they can suffer flexural and/or torsional fatigue3, better infection control and improved quality of the root canal filling9. A previous report showed that, in the mesial roots of mandibular molars, the increase of apical preparation before use of the 0.40 mm instrument significantly increased the root canal volume without significantly reducing the dentin thickness in the danger zone18. In the present study, the apical preparation was performed until use of the F3 (30.09) instrument, which promoted a significant increase in the root canal volume. In both groups the preparation was centralized at the last apical millimeter; however, in the 3 cervical levels evaluated, the PTG system maintained centralized shaping on transition between the F2 and F3 instruments, which did not occur with the PTU. Nonetheless, both systems maintained significant degrees of mesial and distal dentin wall thicknesses.Apical preparations with larger diameters have been suggested based on studies that showed that this approach facilitates more efficient irrigation in the apical region11(2015) showed that the PTG was associated with less deviation than the PTU, which could be explained by the curvature of the specimens, as that study used moderately curved (25°–35°) mesial canals of mandibular molars, in contrast to the present study that used straight root canals. Therefore, the degree of curvature of the root canals appears to be a key determinant of the performance of the NiTi CM wire.Another study by Gagliardi, et al.26. The post-preparation percentage of un-instrumented areas prior to use of the F2 instrument was comparable to that obtained in a previous study that employed similar instruments and methodologies11; however, in the present study, the root canals were enlarged before use of the F3 instrument, which promoted a significant reduction in un-instrumented areas. This increase in diameter after preparation may be associated with better mechanical cleaning. The dentin thickness at the cervical levels was significantly reduced with the use of the F3 instrument in the PTU group, and the distal wall thickness appeared to be the most at risk. However, after use of the F3 instrument, the dentin thickness at the distal wall, in the cervical portion, was, on average, larger than 0.4 mm in both groups.For both groups, un-instrumented areas of the root canals were observed in all specimens, demonstrating that the PTU and the PTG instruments are not as capable of performing a complete mechanical cleaning of the dentin walls as other NiTi rotary instrumentsThe ProTaper Universal and ProTaper Gold systems exhibited similar capabilities for shaping the straight mesial root canals of mandibular molars. In the specific anatomical condition examined here, the final preparation with the F3 instrument, regardless of the system, enhanced the root canal volume and reduced the un-instrumented area. In conclusion, theControlled Memory NiTi ProTaper Gold PTG system was better at maintaining the centralization of shape in the cervical portion of the straight mesial root canals of mandibular molars than the conventional NiTi ProTaper Universal PTU system.


Nowadays improving the accuracy and enlarging the measuring range of six-axis force sensors for wider applications in aircraft landing, rocket thrust, and spacecraft docking testing experiments has become an urgent objective. However, it is still difficult to achieve high accuracy and large measuring range with traditional parallel six-axis force sensors due to the influence of the gap and friction of the joints. Therefore, to overcome the mentioned limitations, this paper proposed a 6-Universal-Prismatic-Universal-Revolute (UPUR) joints parallel mechanism with flexible joints to develop a large measurement range six-axis force sensor. The structural characteristics of the sensor are analyzed in comparison with traditional parallel sensor based on the Stewart platform. The force transfer relation of the sensor is deduced, and the force Jacobian matrix is obtained using screw theory in two cases of the ideal state and the state of flexibility of each flexible joint is considered. The prototype and loading calibration system are designed and developed. The K value method and least squares method are used to process experimental data, and in errors of kind Ι and kind II linearity are obtained. The experimental results show that the calibration error of the K value method is more than 13.4%, and the calibration error of the least squares method is 2.67%. The experimental results prove the feasibility of the sensor and the correctness of the theoretical analysis which are expected to be adopted in practical applications. With the ability of measuring three force components and three torque components, the six-axis force sensor is one kind of the most important and challenging sensors, used widely in many research areas such as wind tunnel balances, thrust stand testing of rocket engines, and in robotics, the automobile industry, aeronautics, etc. . CompareSince the Stewart platform was applied to the measurement of space six-axis forces by measuring the forces in the six legs with convection elements in 1983 , stimulaxF, yF and zF  as well as the cutting moments xM, yM and zM  simultaneously. Unfortunately, most of the sensors mentioned above are used in a small range of applications. Nowadays, the large measurement range six-axis force sensor is more and more widely needed in applications such as aircraft landing gear momentum tests, rocket thrust tests, spacecraft docking and wind tunnel tests, whose precision requirements are also getting increasingly higher. However, when the parallel six-axis force sensor is used in large measurement range occasions, the traditional joints are difficult to be processed into flexible joints, and the improvement of measurement accuracy will be affected, so parallel six-axis force sensors with large measurement range and high accuracy are urgently required.Although research on the traditional Stewart platform-based six-axis force sensor is quite mature, the sensor with common joints has a lower precision, and the performance of each direction is different. In comparison, the sensor with flexible joints has features of compact structure, fast response, small accumulated error, no mechanical friction, and high measurement accuracy because of the use of integrated design, so it has broad application prospects ,12,13,14When the force transmission relation of the sensor is established, the stiffness of each flexible joint and the whole stiffness which has a direct impact on the measuring accuracy, bearing capacity and dynamic performance, and is one of the important indexes to measure the performance of sensors must be considered. Research on stiffness of the sensors based on parallel mechanism began in the 1990s  proposedIn this paper, a kind of six-axis force sensor based on 6-UPUR parallel mechanism with flexible joints, which has large measurement range and high accuracy is proposed. Meanwhile, the complete mathematical model considering the flexibility of the joints is established, and the calibration experiment is completed. The structure of this paper is as follows: after the introduction, Considering the traditional spherical joints are difficult to processed into flexible joints in a large measurement range situation, and the measurement accuracy will be affected, which restricts its application in six-axis force sensors based on flexible parallel mechanism, this paper proposes a kind of structure model of six-axis force sensor based on a parallel 6-UPUR mechanism. As shown in R of the measuring platform, radius r of the lower platform, the positioning angle A, B, C, the center distance 1l of the U joint and location center distance 2l of the R joint, as shown in The characteristic parameters of the parallel 6-UPUR six-axis force sensor include radius if represents the reacting force on the measuring legs; iS represents the unit line vector along the ith measuring leg; F and M, respectively, represent the ith loaded force vector and toque vector on the center of the measuring platform; There are reacting forces on measuring legs when an external force loaded on the measuring platform of the parallel sensor whose surface is assumed to be friction-less and continuous, and the reacting force is considered along the axis of each measuring leg. According to the space static balance conditions of the measuring platform, the following equation can be obtained on screw theory :(1)∑i=1ωF and f is:Equation (1) can be rewritten in the form of matrix expression as:Each leg of the parallel 6-UPUR mechanism can be seen as a series open-chain mechanism which is composed of six links and six joints, and the U joint is equivalent to two joints whose axes are vertical and intersect. The base is called link 0, which is not included in the six links. The first link is connected to the base by the first rotational joint; the second link is connected to the first link by the second rotational joint, and so on. The coordinate system attached to the base fixedly is referred to as {0}; the coordinate system on the reference point of the end of the leg is referred to as {P}; coordinate system attached to the ith link fixedly is referred to as{i}, as shown in P which is on the measuring platform is:jT is rotational transformation matrix:P in coordinate at the end of the leg, and the left leg and the right leg are separately expressed as:The differential motion vector of central reference point According to the above equations, z axis of the fixed coordinate system O-xyz which is on the center of the lower platform is the direction of S1, and selection of coordinate system has a direct impact on the first-order static influence coefficient matrix, so it is necessary to take the symmetry of the load platform structure into account, thus:Because the When movement of the upper platform is known, movement of the joints in each leg can be written:α-th line of the inverse matrix When six active members of the mechanism are determined, equations of the six active movements from the above equations are taken out and expressed as:Combining the above six equations to constitute a matrix expression, like this: OOFurthermore, the first-order static influence coefficient matrix can be obtained:Thus, the force Jacobi matrix is The six-axis force sensor adopts the structure that all joints are flexible joints with single degree of freedom, and its 3D model is shown in k1 = 8.592 × 104 (N·m/rad).The upper positioning block is composed of two flexible rotation joint, which form a flexible spherical joint with composite flexible universal joint by assembling relationship. Its front view and graphic model are shown in k2 = 4.0852 × 104 (N·m/rad).The lower positioning block is an integral structure, which is composed of two symmetrical flexible universal joints, with the same structure as the flexible universal joint in the upper part of the leg. Its front view and graphic model of a single joint are shown in Considering the effect of elastic deformation of joints on O-xyz is the fixed coordinate system, i1-xi1yi1zi1, i =O 1,2,3,…,6 is the local coordinate system which is established on the reference point of the lower positioning block, i2-xi2yi2zi2O is the local coordinate system which is established on the reference point of the standard one-axis force sensor, i3-xi3yi3zi3O is the local coordinate system which is established on the reference point of the flexible U joint, i4-xi4yi4zi4O is the local coordinate system which is established on the reference point of the integrated positioning block, ip-xipyipzipO is the reference coordinate system which is established on the reference point of the end of a flexible series leg.Xj is deformation vector of the end of leg’s reference point, Xj is the elastic deformation vector of the end of the j-th basic flexible unit, Jj is the pose transformation matrix, Fj = T is the six-axis non-coplanar force, j-th basic flexible unit, JFj is the force transformation matrix.When there is the six-axis external force loaded on the end of the flexible series leg, by the principle of virtual work, the following equation can be obtained:According to the deformation superposition principle of series leg, the total deformation vector of the end of flexible series leg’s reference point caused by movement and rotation deformation vector of every basic flexible unit can be obtained:K is the stiffness matrix of the end of flexible series leg.It can be known by the definition of the stiffness matrix, the relationship between the six-axis external force at the end of the leg reference point and the end deformation of the leg is:Kj  is the stiffness matrix of the jth basic flexible element. The end reference point and the coordinate system of each flexible series leg are established as shown in p-xpypzpO is the reference coordinate system established on the center point of the upper platform. ip-xipyipzipO, i = 1,2,…, 6 is the reference coordinate system which is established on the reference point of the end of the flexible series leg.Substituting Equations (17) and (20) into Equation (21), the following equation can be obtained:ith flexible series leg:X is displacement vector at the reference point of the upper platform.On the assumption that the stiffness of the upper platform and all of branches is infinite, neglecting the minor deformation caused by force and the thickness of upper platform, when there is a six-axis external force, the geometric compatibility conditions between the end reference point and the reference point of the upper platform of the According to the synthesis principle of the space force system, the relationship between the external force vector at the reference point of the upper platform and the reaction force vector on the six flexible series branches is established by the following expression:According to the definition of stiffness matrix of flexible parallel mechanism, there is:The stiffness matrix of the upper platform reference point can be obtained by the above equation:The relationship between the end force of each flexible element and the end force of the leg is:The relationship between the end force of each flexible element and the six-axis external force acting on the sensor’s upper platform is:i = 1,2,…,6; j = 1,…,4.The relationship between the six forces expressed in the local coordinate system and the six external forces acting on the sensor platform is:j = 2, it can be obtained:By extracting equations when f = [That is F1 = [5000 0 0 0 0 0 ]T, F2 = [0 5000 0 0 0 0]T , F3= [0 0 5000 0 0 0]T , F4 = [0 0 0 5000 0 0]T, F5 = [0 0 0 0 5000 0]T, F6 = [0 0 0 0 0 5000]T are respectively loaded in the geometry center of the measuring platform in the three-dimensional model of the sensor, and the size of the force produced on the six elastic legs are obtained by the simulation calculation. The accuracy comparison of the theoretical values and simulation values is shown in In the above two sections, the mathematical models of the two cases are obtained. By using the ANSYS finite element simulation software platform, the external force As shown in In order to prove the superiority of the proposed sensor structure and prove the correctness of the theoretical analysis, a prototype of the large measurement range six-axis force sensor of 6-UPUR parallel mechanism with flexible joints was manufactured, as shown in x, y, z separately. In this paper the calibration system, which mainly included a hydraulic loading system, calibration platform, parallel 6-UPUR six-axis force sensor with flexible joints, signal processing device, data acquisition device, data processor, calibration software system and so on, as shown in To measure the loaded external force accurately, the sensor should be calibrated by using a special calibration system, which can generate forces and torques in directions of Considering that the structure of the six-axis force sensor of 6-UPUR parallel mechanism with flexible joints is very complex and the presence of measuring error can’t be ignored because of the influence of these factors such as the design principles, manufacturing and processing errors, so multiple point loading in the sensor range and the method of least squares linear fit are needed in calibration experiments. Thus, the linear relationship between inputs and outputs of the large measurement range 6-axis force sensor of 6-UPUR parallel mechanism with flexible joints can be calculated.(1)Each axis force/torque within the sensor range is divided into 10 load points in two positive and negative directions, as shown in (2)Select the force/torque component of the load. The load unit is installed in the corresponding position, and connect the calibration hardware system, as shown in (3)At each loaded point, conduct loading and unloading experiments in turn, and record the output voltage of each measuring leg corresponding to each load point;(4)Repeat Steps (2) and (3), conduct loading and unloading experiments in the opposite direction and record the experimental data;(5)Repeat Steps (2)–(4), the calibration experiments of the six axis force sensor are carried out and all the experimental data are obtained;(6)Check and process the data. The calibration matrix of the sensor is obtained, and the linearity of the sensor is determined.Detailed experimental steps are described are as follows:In the analysis of experimental data, the forces that are loaded on the prototype during the experiment can be described as six linearly independent vectors, denoted as:G is the calibration matrix between the loaded forces and the output voltages; V is the output voltage matrix.When the external forces are loaded on the measuring platform of the sensor, the six single-axis force sensors will sense the force produced on the measuring legs, and then the change of output voltage of the Wheatstone bridges can be measured out. We can get a set of relationships:Thus the calibration matrix between the loaded forces and the output voltages of the six measuring legs can be calculated:FFS is the full range of the sensor, F6×6 can be calculated based on the mapping matrix between the loaded force and the output voltage by Equation (32); the error matrix Err is a comprehensive evaluation. The diagonal components of the error matrix separately represent the measurement errors of the six different directions of the loaded external force, and other components represent the interference errors between different directions.Besides, the error matrix evaluating the accuracy of the six-axis force sensor is defined as follows:GK, GC2 and the error matrix ErrK, ErrC2 can be obtained by the analysis and process of the experimental data, therefore, the performance of force-measuring of the sensor is obtained:Through the calibration system described above, the calibration experiments based on the sensor prototype are carried out, and the data of the six measuring legs are obtained. Taking a complete static calibration experimental data and using the K value method and least square method to substitute the loading forces and the voltages data which are collected from six measuring legs into the corresponding equation, the static calibration matrix Fx (4.31%), Fy (2.64%), Fz (3.33%), Mx (2.08%), My (1.63%), Mz (0.76%). The maximum error of the I kind is 4.31%, which appears in Fx ; the maximum error of the II kind is 13.40%, which is appears in Fy, when loaded in My. So the calibration error obtained by this method is 13.40%.From Equation (34), it can be noted that when the K value method is used to decouple, the calibration error of each axis is: Fx (1.22%), Fy (0.66%), Fz (0.89%), Mx (0.39%), My (0.59%), Mz (0.42%).The maximum error of the I kind is 1.22%, which appears in Fx; the maximum error of the II kind is 2.68%, which appears in Fy, when loaded in My, so the calibration error obtained by this method is 2.68%.From Equation (36), it can be noted that when the least squares method is used to decouple, the calibration error of each axis is: From the results of the calibration experiment, the calibration error comparison of the two kinds of decoupling methods is as shown in The input signal and the output signal of the sensor are not completely linear, and there is always an error. The ratio of the error to the measurement range is called the linearity of the sensor. When a certain force/torque is loaded to one direction of the sensor, the output voltage of the six legs will change with the change of the loading force/torque. In this paper, to overcome the influence of the gap and friction of the traditional joints on the parallel six-axis sensors’ precision and stability, we have successfully demonstrated a kind of six-axis force sensor based on 6-UPUR parallel mechanism with flexible joints, which has large measurement range and high accuracy. The force mathematical model of the sensor is established on the screw theory; according to the relations of the stiffness and deformation compatibility condition, the stiffness matrix considering flexibility of each flexible joint is built up; then the complete mathematical model is established. The sensor prototype and the calibration system are manufactured and static calibration experiments were carried out on the sensor. The results show that the measurement error is less than 2.68%, which shows that the sensor has high measuring accuracy and good linearity. The experimental results prove the feasibility of the large measurement range six-axis force sensor of 6-UPUR parallel mechanism with flexible joints. The design and loaded research of the parallel six-axis force sensor has reference significance.


AbstractWandogaridacanaliculagen. n et sp. n.  is described from the southern coast of Korea (NW Pacific). The genus is included in the subfamily SphyrapodinaeGuţu, 1980 by having a mandible lacking a palp. It has a close affinity with the genus Poligarida Bamber & Marshall, 2013 in the third pereonite having lateral pointed apophyses, the antennule of males with fringes of aesthetascs on articles 1 and 2 of the outer flagellum and the antenna with an elongate article 2. However, it is distinguished from Poligarida by having a maxillular palp. Wandogaridagen. n. can be differentiated from other genera within the subfamily Sphyrapodinae by the unique shape characterised by the male’s antennule article 1 with its rough denticles and a deep groove, pleonites each with a ventral hyposphenium, the maxillule with uniarticulate palp and the presence of prominent sexual dimorphism in the mouthparts. An identification key to the five genera of the subfamily Sphyrapodinae is presented. Apseudomorpha Sieg, 1980 includes about 460 species and is widely distributed in various shallow marine benthic habitats, being quite abundant in coral reefs, estuaries and mangrove swamps, from the tropics to temperate regions . However, the suborder and superfamily were not accepted and Metapseudoidea was synonymised with Apseudoidea Leach, 1814 by The suborder  regions . Althoug regions . Guţu  in October 2015 using an epi-sledge net. The specimens were extracted by filtering the substrates through a 350 μm sieve and the residue from each sieve was preserved in a 99% alcohol solution. Later, the animals were identified and counted in the laboratory. The specimens were dissected under a dissection microscope (Nikon SMZ745T) in CMC-10 aqueous mounting medium , mounted on slides and then sealed with high-quality nail varnish. Drawings were generated using a differential interference contrast microscope (Nikon Y-IM) that was equipped with a drawing tube. The total body length was measured from the tip of the rostrum to the pleotelson apex in the dorsal view. Scale bars are given in mm. The morphological terminology follows MABIK), Seocheon, South Korea.The materials were obtained from the sandy bottom off Wando Island on the southern coast of South Korea: .The name refers to Wando, a port city near the type locality and Wandogaridacanalicula sp. n.Wandogarida gen. n. is classified in the subfamily Sphyrapodinae following Ansphyrapus Guţu, 2001, Poligarida Bamber & Marshall, 2013, Sphyrapoides Guţu & Iliffe, 1998 and Sphyrapus Sars, 1882, including the new genus Wandogarida.The subfamily is now composed of five genera: Wandogarida resembles Poligarida in the absence of an antennal squama, antennule with a biarticulate inner flagellum, pereonite 3 with anterolateral pointed apophyses and outer flagellum of the male antennule with fringes of aesthetascs. However, Wandogarida can be differentiated from Poligarida by the following: in both sexes, the number of antenna articles is different (8 vs. 7); the maxillule has a uniarticulate palp (vs. absence); the carpus and propodus of pereopods 2–3 and propodus of the pereopod 4 have ventral spiniform setae (vs. absence); in females, the mandible molar has several setulose distal setae and sharp, spinose distal margin ; in males, sexual dimorphism exists in the antennule article 1 with a vertical row of rough denticles and concave distolateral margin, in reduced and simplified mandibles, maxillule, maxilla and maxilliped endite, in the larger and more robust cheliped and in the shape of ventral margin of the pereopod 1 dactylus, while it exists only in the antennule, cheliped and pereopod 1in Poligarida.Taxon classificationAnimaliaORDOFAMILIAhttp://zoobank.org/BBEE7CE0-F2C4-42A4-ABD6-DD3D12A836EEHolotype: (MABIK CR00240685) female dissected and mounted on five slides. Allotype: (MABIK CR00240686) male dissected and mounted on five slides; from the same locality as the holotype. Paratypes: Four females partly dissected on one slide (MABIK CR00240687) and in 3 vials (MABIKCR00235359–MABIKCR00235361); from the same locality as the holotype. Four males partly dissected on one slide (MABIK CR00240688) and in 2 vials ; from the same locality as for holotype.34°31.02'N, 128°33.11'E, mud-sandy bottom at a depth of 41 m.Wando, South Korea (North West Pacific), canalicula, meaning a groove and refers to the conspicuous groove formed on the distal margin of the male antennule.The specific name is derived from Latin Female (with oostegites). Body  were partly dissected and the cheliped, the pereopod 1 and a ventral hyposphenium of pleonite were examined for different sizes and some variations were found: 1) in the cheliped, the dactylus and fixed finger of the males were modified in size: in the cheliped of the large sized males (over 2 mm), the cutting edge of the dactylus is extended and strongly curved and the processes on the proximal margin are prominently developed; 2) the number and size of setae on the pereopod 1 propodus increased with size; 3) a ventral hyposphenium of the male pleonite is modified from a rounded shape to a subrectangular shape, with body length reaching over 2 mm.Ansphyrapus and Sphyrapoides affects only their chelipeds, while in Sphyrapus and Poligarida, it affects their antennule, cheliped and pereopod 1. However, Wandogaridacanalicula gen. n., sp. n. exhibits a greater level of sexual dimorphism: 1) the female body is wider than males, 2) in the antennule, the distal surface of the article 1 is round and naked in females, while that of the male has a vertical row of rough denticles and a deep groove; the outer flagellum of males is 5-articulate and the first and second articles have fringes of aesthetascs, but that of the female is 3-articulate and bears only one aesthetasc each on the first and second articles, 3) in the mandible, the incisor and lacinia mobilis of the left mandible of the female have distal denticles, but those of the male are distally pointed and naked and the setae of the setal row are shorter and more slender than those of the female. The setal row of the right mandible also differs , 4) in the maxillule, the distal setae on the outer and inner endites of males are shorter than those of females, 5) the setae on the maxilla of males are PageBreakdiminished in size, as compared to those of the female, 6) the maxilliped endite of the male lacks inner setae and the distal margin has six naked and reduced spiniform setae, while that of the female has four plumose setae along the inner margin and eight distal spiniform setae, 7) in the cheliped, the basis, fixed finger and dactylus show dimorphism: the basis of the male is more robust than in the female, the cutting edge of the fixed finger has slender and pointed denticles and processes, but that of the female has distally broad denticles; the dactylus of the male has several denticles and processes along the cutting edge, but that of the female is naked and 8) the pereopod 1 of the male is longer than that of the female and the dactylus also shows a different shape in the both sexes: the ventral margin has small denticles in the male but spines in the female.Sexual dimorphism within the genera W.canalicula can be used as an important tool to divide easily and precisely males and females of the sphyrapodid species and upgrade our understanding how their life cycle or morphological function adapts to diverse environments.These results in the sexual dimorphism and morphological variation with body size shown in