Tooth Count Research Articles

Design and Stress Analysis of Bevel Line Gears with Vertical Flank Suitable for Micro Machining

The line gear (LG) exhibits promising applications in micromachinery owing to its simple structure and minimal teeth count. This paper aims to advance the meshing theory of LG and introduce a conical LG tooth configuration specifically tailored for micro-machining that is capable of driving with high performance. Based on the meshing principle of LG, a conical line gear pair with vertical flank (VFLG) of the driving gear was designed. Subsequently, adhering to the curvature non-interference principle that no local interference occurs in the meshing process and the specified range of fitting error in one direction, the design parameters for LG were determined. A comparison of the contact stress between two sets of different contact line types revealed the distinct advantage of VFLG with parameters identical to those of traditional LG. The experimental results conclusively demonstrate a transmission ratio error of 0.004, affirming the feasibility of the design. The curvature non-interference design formula proposed in this paper refines the LG design theory, and the novel LG design method presented holds significant implications for subsequent micromachining.

Association and relevant factors between objective masticatory performance and subjective masticatory ability among community-dwelling older adults

Background/purposeDentists often focus on masticatory performance (MP) rather than masticatory ability (MA) and treatment expectations when evaluating older adults. This study aimed to determine if MA aligns with MP and to explore influencing factors. Materials and methodsThis cross-sectional study utilized a multi-stage stratified cluster sampling, including one thousand community-dwelling adults aged 60 and older. Participants underwent oral exams and questionnaire interviews, assessing tooth count and Eichner index (EI) levels. MP and MA were quantified using a standard gummy jelly test and a 14-food group questionnaire, respectively. Multivariable linear regressions analyzed correlations between MP, MA, and related factors. ResultsApproximately 25 % of participants exhibited poor MP. Factors contributing to poor MP included increased age rise, low education, number of chronic diseases, tooth loss, without the assistance of removable dentures, and being in EI group C (all P < 0.05). Tooth count showed a significant negative correlation with MP (P < 0.001). Participants' MP declined significantly from good to poor, with MA scores decreasing from 11.96 to 7.52 (P < 0.001). The tooth number was a common factor influencing MA across food groups (all P < 0.05). The decline in MA among older adults was linked to age rise, tooth loss, lack of assistance of removable dentures, and being in EI group C. ConclusionSelf-rated MA in older adults effectively reflects their MP. Maintaining a high tooth count to meet occlusal support and the use of dentures to assist with tooth loss in older adults help to improve their MA.

Volatile sulfur compounds, biofilm, and salivary parameters in patients with periodontal disease: a cross-sectional study.

This cross-sectional study aimed to evaluate the interplay between volatile sulfur compounds (VSC), biofilm, salivary parameters, and periodontal status in patients with and without periodontal disease. Sixty-four subjects diagnosed with periodontitis and 60 periodontally healthy individuals were included. Probing depth, clinical attachment level, bleeding on probing, tongue coating index, plaque index, number of teeth, spinnability of unstimulated whole saliva, and salivary flow rate were evaluated. The concentrations of VSC were quantified using a portable gas chromatograph. The mean differences in hydrogen sulfide, methyl mercaptan, salivary flow, spinnability, and plaque index did not exhibit statistically significant variances between the two groups. However, a pronounced tongue coating index and a diminished tooth count showed statistical significance in the periodontitis group (p = 0.039; p < 0.001). Unstimulated salivary flow rate less than 0.25mL/min was statistically significant in the periodontitis group (p = 0.032). After controlling for confounding factors, bleeding on probing remained significant. A positive correlation between periodontal parameters and VSC concentration was found. An inverse correlation was also noted between the spinnability of saliva and tongue coating index (-0.34; p < 0.001). Salivary parameters may contribute to the formation of tongue coating and are correlated with periodontal status. Bleeding on probing, clinical attachment level, and probing depth were identified as potential contributors to VSC formation.

Parallel phenotypic evolution of two independent cavefish lineages of Astyanax mexicanus (De Filippi, 1854) (Characiformes: Characidae)

Abstract Astyanax mexicanus offers a unique model for studying parallel evolution, with cave-dwelling forms arising from at least two distinct surface lineages. Here, we examined repeated evolution in the two cave-adapted lineages across four phenotypic datasets: (i) meristic data; (ii) ecomorphological data; and geometric morphometric data for (iii) head and (iv) premaxillary bone shape. Additionally, we assessed the association of these phenotypes with their phylogenetic history. Certain traits exhibited evidence of parallel evolution for the cave ecotype across lineages, such as increased maxillary tooth count, reduced lateral line scale count, and shorter ascending process of the premaxillary bone. Geometric morphometric data showed a phenotypic divergence gradient in head shape between cave and surface populations, with the strongest divergence between Sierra de El Abra and surface populations and with less differentiation between surface populations and caves from Sierra de Guatemala and Micos. Cave populations that hybridize with surface populations (e.g. Micos) displayed the greatest overlap with the surface ecotype. There was a similar divergence gradient for premaxillary bone shape, but with weaker differentiation between cave and surface ecotypes. This evidence of repeated evolution in several cave traits emphasizes the significance of selective pressures exerted by the environment on the evolution of cave ecotypes.

Radiologic Evaluation of Oral Health Status in Patients Admitted to the Intensive Care Unit: A Multi-Institutional Retrospective Study.

Introduction: Surveys distributed among intensive care unit (ICU) nurses reveal a significant need for dental care, with many acknowledging poor oral hygiene management. Poor oral health in ICU patients is linked to systemic problems, including aspiration pneumonia, necessitating pre-intervention assessments for bacterial diseases and dental risks. This study aims to evaluate the oral health status of ICU patients across three institutions through retrospective analysis. Methods: This retrospective study assessed the oral health status of ICU patients, using computed tomography (CT) images from three institutions over ten years. Through CT images, the oral status was evaluated in terms of total and lost tooth count and the presence of oral lesions (periapical lesions, cysts and tumors, caries, tartar, moderate to severe periodontal bone loss, tooth fractures). Variables included gender, age, the duration of ICU stay, and types of ICU. Statistical analysis was performed using chi-square tests, independent-sample t-tests, and logistic regression analysis. Results: Of the 450 participants, 430 were analyzed, revealing a prevalence of oral lesions in 67.0% of subjects. The prevalence of oral lesions was higher in males (71.5%) than females (57.7%, p = 0.006), and higher in those aged 40 and above (72.1%) compared to those under the age of 40 (47.8%, p < 0.001). This study found significant differences in oral health status based on gender, age, and ICU type, with surgical ICU patients generally having better oral health. Risk factors for oral lesions included gender, age, and duration of ICU stay. Conclusions: Most ICU patients have at least one oral lesion, regardless of the reason for their ICU admission. In particular, male ICU patients aged 40 and above have a higher prevalence of oral lesions, necessitating careful oral health assessment and treatment.

Comparison of osteological characters of juveniles of freshwater and anadromous Black Sea trout Salmo trutta labrax and Atlantic salmon S. salar (Salmoniformes: Salmonidae)

A comparative analysis of juvenile anadromous and freshwater (stream) forms of the Black Sea brown trout Salmo trutta labrax Pallas, 1814 was conducted using 10 meristic and 62 morphometric characters of cranial bones. This analysis included the counts of teeth and pores in the bones, as well as measuring of their shape characters. As a basis for comparison, data on juvenile anadromous and freshwater Atlantic salmon Salmo salar Linnaeus, 1758 were used. The osteological differences between ecological forms were more pronounced in the brown trout than in the Atlantic salmon. In the brown trout, a greater number of meristic characters differentiated the forms compared to the salmon. However, for morphometric characters, the reverse pattern was observed. The freshwater forms exhibited characteristics intermediate to the anadromous forms of the two species, being more similar to the anadromous form of their species than to each other. Juvenile anadromous Black Sea trout typically had the fewest teeth, while juvenile Atlantic salmon had the most, with freshwater forms showing intermediate values. The most significant differences in the shape of cranial bones were also observed between the juvenile anadromous forms of two species. The characteristics pertaining to the number of pores in cranial bones did not reveal clear patterns when comparing the samples. Among the studied bones and characteristics, those showing the most significant differences between Black Sea trout and Atlantic salmon were identified, and species-specific features were noted. The results obtained show that juveniles of different ecological forms within the same species of the genus Salmo exhibit statistically significant osteological differences, suggesting a high genetic determination of these traits and the influence of selection within river systems on the divergence between freshwater and anadromous forms. Despite this, the variability in all studied characteristics indicates plasticity, resulting in the differences between the species and ecological forms within the genus Salmo typically not reaching the threshold for subspecies differentiation. These results align with previous studies on adult individuals and indicate that the freshwater form of the Atlantic salmon displays osteological characteristic of a more ancestral species, namely the brown trout.

Study on Spline Stress of Separator Plates in a Wet Multi-Plate Clutch

The spline teeth fracture of separator plates in wet multi-plate clutches compromises driving safety and the vehicle’s lifespan. Tooth fracture is mainly caused by stress concentration at the tooth root and uneven circumferential load distribution. This paper considers parameters such as torque, teeth count, tooth profile, and misalignment errors, establishing the corresponding finite element (FE) model to analyze the impact of the above-mentioned parameters on the strength of the separator plates. Analysis under even and biased load circumstances demonstrated that an optimum tooth count and profile can significantly increase the strength of the separator plates, offering advice for the optimized design of wet multi-plate clutch separator plates.

Exploring the link between tooth loss, cognitive function, andbrain wellness in the context of healthy aging.

The aim of this study was to evaluate the utility of using MRI-derived tooth count, an indirect and nonspecific indicator of oral/periodontal health, and brain age gap (BAG), an MRI-based measure of premature brain aging, in predicting cognition in a population of otherwise healthy adults. This retrospective study utilized data from 329 participants from the University of South Carolina's Aging Brain Cohort Repository. Participants underwent neuropsychological testing including the Montreal Cognitive Assessment (MoCA), completed an oral/periodontal health questionnaire, and submitted to high-resolution structural MRI imaging. The study compared variability on cognitive scores (MoCA) accounted for by MRI-derived BAG, MRI-derived total tooth count, and self-reported oral/periodontal health. We report a significant positive correlation between the total number of teeth and MoCA total scores after controlling for age, sex, and race, indicating a robust relationship between tooth count and cognition, r(208) = .233, p < .001. In a subsample of participants identified as being at risk for MCI (MoCA <= 25, N = 36) inclusion of MRI-based tooth count resulted in an R2 change of .192 (H0 = 0.138 → H1 = 0.330), F(1,31) = 8.86, p = .006. Notably, inclusion of BAG, a valid and reliable measure of overall brain health, did not significantly improve prediction of MoCA scores in similar linear regression models. Our data support the idea that inclusion of MRI-based total tooth count may enhance the ability to predict clinically meaningful differences in cognitive abilities in healthy adults. This study contributes to the growing body of evidence linking oral/periodontal health with cognitive function.

玉米内充气压式高速精量排种器推种轮设计与试验

In order to improve the uniformity and stability of seed delivery and meet the requirements of precision sowing operation, a kind of seed push wheel designed to mesh with the seed discharging disk was developed. The wheel underwent theoretical analysis and experimental optimization regarding parameters such as tooth profile, tooth count, and tooth height. Using a pneumatically inflated maize precision seed-metering device as the seeding carrier, a full-factorial experiment was conducted with operational speed and tooth height as the experimental variables, and qualification rate, reseeding rate, and leakage rate as the performance indicators. A multivariate quadratic regression model was established to assess the relationships between the factors and indicators. The results indicated that optimal seed guiding performance was achieved when the seed push wheel had 9 teeth, a tooth height of 5.2–6.2 mm, and an operational speed of 9.0–12.6 km/h. This study provides a theoretical foundation and data support for the development of precision seeding technology and corresponding seed guiding devices.

Association of rotating night shift work with tooth loss and severe periodontitis among permanent employees in Japan: a cross-sectional study.

The modern 24/7 society demands night shift work, which is a possible risk factor for chronic diseases. This study aimed to examine the associations of rotating night shift work duration with tooth loss and severe periodontitis. This cross-sectional study used data from a self-administered questionnaire survey conducted among 3,044 permanent employees aged 20-64 years through a Japanese web research company in 2023. The duration of rotating night shift work was assessed using a question from the Nurses' Health Study. Tooth loss was assessed based on self-reported remaining natural teeth count. Severe periodontitis was assessed using a validated screening questionnaire comprising four questions related to gum disease, loose tooth, bone loss, and bleeding gums. We employed linear regression models for tooth loss and Poisson regression models for severe periodontitis, adjusting for demographic, health and work-related variables and socioeconomic status. Among participants included, 10.9% worked in rotating night shifts for 1-5 years, while 11.0% worked in such shifts for ≥6 years. In fully adjusted models, rotating night shift work duration of 1-5 years was associated with tooth loss (beta -0.74, 95% confidence interval (CI) [-1.55 to 0.08]) and severe periodontitis (prevalence ratio 1.80, 95% CI [1.33-2.43]); however, the association with tooth loss was not statistically significant. This study supports that employees who work short-term rotating night shifts may experience poor oral conditions. Further research is needed to determine whether long-term rotating night shift work is associated with deteriorated oral health.

Tooth Loss and Chronic Pain: A Population-based Analysis of the National Health and Nutrition Examination Survey

Poor oral health conditions in adults are associated with chronic pain. A nationwide cross-sectional study was conducted to investigate the link between tooth loss and chronic pain. The study involved 8,662 participants from the National Health and Nutrition Examination Survey. Tooth count was categorized into 4 groups, and chronic pain was defined as persistent pain lasting over 3 months despite treatment. Location of the chronic pain, demographics, comorbidities, lifestyle determinants, and dietary intake were retrieved. Univariate and multivariate logistic regression were used to explore cross-sectional associations between tooth count and chronic pain. Compared to participants with more than 20 teeth, those with severe tooth loss presented greater odds of chronic pain (adjusted odds ratio [aOR] = 2.111, 95% confidence intervals (CI) = 1.213–3.676 for patients with 1–8 teeth). Edentulous participants presented with significantly higher odds of chronic pain in the lower extremities (78.4%) and buttocks (49.5%). In the multivariate model, apart from rheumatic arthritis (aOR = 4.004, 95% CI = 2.766–5.798), variables of higher chronic pain included smoking (aOR = 1.518, 95% CI = 1.228–1.878), and hypertension (aOR = 1.463, 95% CI = 1.013–2.112). On the contrary, being Mexican American (aOR = .603, 95% CI = .414–.880) was associated with lower odds of chronic pain. The findings suggested a significant link between chronic pain and tooth loss, independent of ethnicity, lifestyle determinants, and immune-mediated inflammatory diseases including rheumatoid arthritis. PerspectiveA U.S. nationwide study examined tooth loss and chronic pain. Those with severe tooth loss had increased odds of chronic pain. Edentulous individuals presented higher odds of pain in lower extremities and buttocks. This study highlighted the link between tooth loss and chronic pain, independent of comorbidities and lifestyle factors.

Oral paleopathological investigation of the Avar period (6–7th c. CE) population from Nagykőrös

The main goal of the research is to widen our knowledge about oral health during the Early Avar Period (6–7th c. CE). We used the individual and tooth count method to record abrasion, caries, antemortem tooth loss, periapical lesions, linear enamel hypoplasia, calculus and dental trauma of 26 individuals from the Nagykőrös-Kovács tanya site (9 males, 6 females, 11 subadults). The examination of the remains showed the noteworthy presence of dental abrasion and calculus among subadults, which increased with age. Only the tooth count analysis revealed a significant difference between the adults, as females had more teeth with caries and hypoplasia, while for calculus males had increased intensity in their dentition. The comparison with Late Avar Period skeletal assemblages from other geographic regions indicated possible spatial or temporal trends of oral health.

Association between poor periodontal health and 15‐year risk of incident dementia

AbstractBackgroundPoor oral health, particularly tooth loss, has been highlighted as a potential modifiable risk factor for dementia. However, longitudinal evidence concerning the association of poor periodontal health with dementia is limited. This study examines the impact of poor periodontal health on 15‐year risk of incident dementia.MethodThis study included 4596 dementia‐free and dentate (i.e., having ≥1 teeth remaining) participants, aged 30‐93 years, from population‐based Finnish Health 2000 Survey. Periodontal health at baseline was evaluated through bleeding on probing (BOP), periodontal pocket depths (PPD), and alveolar bone loss (ABL). BOP for each sextant and PPD for each tooth (excluding third molars and residual roots) were recorded clinically during oral examination. Based on BOP, participants were dichotomized into having ≥1 sextant with BOP versus no BOP.Tooth with PPD of ≥4mm was considered as having deepened periodontal pocket. Based on PPD, participants were dichotomized into having ≥1 teeth with deepened PPD versus no PPD. ABL for each tooth was examined through orthopantomographs and defined as vertical bone loss extending apically to at least the middle third of tooth root. Based on ABL, participants were dichotomized into having ≥1 teeth with ABL versus no ABL. Dementia diagnosis until 2015 was retrieved from national health registers.Cox proportional regression was conducted and adjusted for age, gender, education, cardiovascular risk, socioeconomic status, depression, alcohol consumption, c‐reactive protein, and overall tooth count. Sensitivity analysis accounting for potential reverse causality bias was conducted by excluding incident dementia during the first five years of follow‐up.Result183 participants developed dementia over 15 years. Fully adjusted hazard ratio among participants with ≥1 sextant with BOP was 1.15 (CI:0.80‐1.65), with ≥1 teeth having deepened PPD was 0.94 (CI:0.67–1.31), and with ≥1 teeth having ABL was 0.97 (CI:0.64–1.49). Findings from sensitivity analysis for potential reverse causality bias corroborated with results for main analyses.ConclusionPreliminary findings indicate no association of BOP, PPD, or ABL with 15‐year dementia risk. However, further well‐designed longitudinal studies with more comprehensive periodontal assessment (e.g., clinically diagnosed periodontitis and severity of periodontitis) are warranted to conclusively assess its impact on dementia risk.

A novel APC mutation associated with Gardner syndrome in a Chinese family

Gardner syndrome (GS) is a specific form of familial adenomatous polyposis (FAP), which manifests as colorectal polyps, multiple osteomas and soft tissue tumors, and in the oral cavity as osteomas of the jaws, odontomas, and abnormal tooth counts. The underlying cause of GS is attributed to mutations in the APC gene. Mutations in this gene disrupt the normal functioning of the protein and lead to the development of GS. To further investigate GS, a family affected by the syndrome was selected from Dongguan, Guangdong Province. The family members underwent a comprehensive survey, which involved collecting clinical data and peripheral venous blood samples. The samples were then used for genetic analysis. Whole exome sequencing (WES) and Sanger sequencing techniques were utilized to screen and identify specific mutation sites in the APC gene. The clinical findings for the GS family included the presence of gastrointestinal polyps and odontomas. After analyzing the genetic sequencing results, a novel mutation site c.4266dupA on the APC gene was found in the patients, which leading to the APC protein truncation. As a result of this study, it is suggested that odontoma may be an early indicator of GS. Additionally, the identification of this novel mutation site in the APC gene expands the known spectrum of genetic mutations associated with the disease. This discovery has significant implications for the early diagnosis of GS, thus enabling timely intervention to reduce the risk of developing colon cancer and other related diseases.

Experimental observation of stimulated Raman scattering enabled localized structure in a normal dispersion FP resonator

Dissipative Kerr nonlinear cavities attract intense interest due to their rich dynamics and capability to generate broadband, low-noise, mode-locked optical frequency combs for applications in optical communications, dual-comb spectroscopy, photonic lidar, etc. Different from the Kerr effect, which is an electronic response, stimulated Raman scattering (SRS) is a delayed response to molecular vibrations in materials. In microcavities, when driven in an anomalous group velocity dispersion (GVD) regime, SRS typically leads to a self-frequency shift of solitons and generation of breather solitons, which have been verified both theoretically and experimentally. However, when driven in a normal GVD regime, recent theoretical work predicts that SRS can cause the locking of switching waves (SWs) and thus support bright moving localized structure (LS), which we term as SRS enabled localized structure (SRS-LS). Limited by the design of suitable experimental parameters, experimental observation of this SRS-LS is not achieved yet. Here, we provide numerical investigation and, to our knowledge, the first experimental observation of the SRS-LS in a fiber Fabry–Perot (FP) resonator with ultra-low normal GVD. Such SRS-LS exhibits localized temporal features with strong oscillations at ∼13THz local frequency on the top of a flat-top pulse. The corresponding spectrum is a low-noise and broadband Kerr comb with a typical platicon-like spectrum in the center and two Raman Stokes and anti-Stokes peaks located near ±13THz away from the center. With such an SRS enabled broadband Kerr comb, we have achieved an SRS-LS spectrum with a repetition rate of ∼3.68GHz and a −30dB spectral width of 255 nm. The corresponding comb tooth count is &gt;8500, covering the S + C + L telecommunication bands. Moreover, the formation process of such SRS-LS is also revealed, and it is found that the GVD plays a key role in its generation. Our work will help to advance the study of the dynamics of optical frequency combs under the influence of SRS, as well as provide a broadband coherent mode-locked optical source for wide applications.

Validity of self-reported number of teeth among Saudi older adults: A public health perspective

ObjectivesThis study aimed to evaluate the agreement between self-reported and clinically measured numbers of teeth in older adults from Almadinah Almunawwarah, KSA, and to identify factors associated with self-reporting accuracy. MethodsThis study included 337 older adults (≥60 years). Participants completed a survey assessing sociodemographic characteristics, self-rated oral and general health, and the self-reported number of teeth. Clinical examination was conducted using the 2013 criteria published by the World Health Organization. Bland–Altman plots and correlation coefficients were used to assess the agreement between self-reported and clinically measured teeth. ResultsThe mean age of the study participants was 67.1 (SD = 6.5) years, and the majority were males (71.2%). The self-reported teeth count was higher than the clinically measured number, and only 47.7% (n = 161) of the sample showed complete agreement between the two measures. The mean difference between the self-reported and clinically recorded number of teeth was 0.41 teeth, and almost two-thirds of the study participants reported their number of teeth within an error margin of two teeth (p < 0.001). Both Spearman's and Pearson's correlation methods revealed a significant positive correlation between the two measures. Specifically, the Spearman's rho was 0.91, while Pearson's r coefficient was 0.96. ConclusionAmong Saudi older adults, the self-reported number of teeth correlated with the clinically measured numbers of teeth. This suggests that self-reports can be a reliable and cost-effective method for assessing oral health in large-scale surveys, potentially guiding health policies and interventions for older adults.

Do Nutritional Status Parameters such as Body Mass Index &amp; Mid Upperarm Circumference Need to be Taken into Account when Estimating Dental Age? A Cross-sectional study with Tooth Count as Variable

Context: Age estimation is playing a very important role in the criminal justice system and also in the forensic human identifi cation process. Over the past several decades, the scientifi c community has done extensive work on age estimation from biological markers of growth, the dental structure being one among them. The routine dental age estimation methods usually apply the mineralization and/or the eruption parameters of the developing dentition. Certain factors like the nutritional status and the socio-economic status of the individual also may infl uence dental development and eruption. Aim: The objective of the study was to assess the link between the nutritional status and the dentition status of children and adolescents in the age range of 12 to 18 years. Settings and Design: This is a cross-sectional population based, descriptive study. Materials and Methods: The body mass index (BMI) and the mid-upper arm circumference (MUAC) values were measured to assess the nutritional status of the children with a mean age of 14.35 years (± 1.36). The oral examination was done to count the number of teeth present. The tooth count was compared with the BMI and the MUAC values of the children. Results: The mean BMI of the study population was 17.36 Kg/m2 ± 3.40 and the mean MUAC value was 21.53cm ± 2.93. There was a strong positive correlation between BMI and MUAC and a signifi cant diff erence in the deciduous tooth count among the BMI categories. (2 =12.161, df 3, p&lt;0.05). Conclusion: There is no signifi cant association between BMI and deciduous tooth count in the study sample. Key Messages: The BMI and MUAC values are markers of nutritional status in growing children. Though nutritional status has a link with the tooth development, the present study could not establish a signifi cant association between BMI and deciduous tooth count in children in the age range of 12 to 18 years.

Development of a multiple masticatory function model based on the evaluation of sarcopenia: A cross-sectional survey of the Otassha study

ObjectiveThe masticatory function is intricately linked to several factors like natural teeth count, occlusion, masticatory muscles, and tongue coordination. This study's goal was to formulate a comprehensive masticatory function model, considering sarcopenia's conceptual structure, and subsequently validate its measurement efficacy. DesignThe study encompassed 753 participants (59.1 % women; mean age: 73.0 ± 5.1 years) from an urban community. The model amalgamated masseter muscle mass, occlusal force, and mixing ability. Based on the Asian Working Group for Sarcopenia 2019 classification, participants were categorized into a multiple masticatory dysfunction (MMD) or severe MMD (S-MMD) group. Logistic regression analysis gauged the model's validity, using serum albumin levels and self-reported chewing difficulties as dependent variables. ResultsOf the total, 61 (8.1 %) participants exhibited MMD, while 24 (3.2 %) had S-MMD. S-MMD was correlated with low serum albumin levels (odds ratio: 3.62; 95 % confidence interval: 1.07–12.29) and heightened self-reported chewing difficulties (odds ratio: 2.82; 95 % confidence interval: 1.09–7.28). ConclusionsOur multiple masticatory function model offers a straightforward approach for assessing MMD. Furthermore, the study establishes a link between S-MMD, nutritional vulnerability, and self-reported chewing challenges, thus affirming the model's credibility.

A new species of the genus Rhabdophis Fitzinger, 1843 (Squamata: Colubridae) from the Hoang Lien range, northwest Vietnam.

We describe a new species of the Natricinae genus Rhabdophis Fitzinger, 1843 from the Hoang Lien range, northwest Vietnam. The new species is distinct from all congeneric species on the grounds of morphometric and molecular data. The new species is most similar to Rhabdophis leonardi in terms of morphology but can be distinguished from it based on differences in maxillary tooth count, scalation, and genetic data. A sequence on GenBank from a Rhabdophis specimen collected in Honghe, Yunnan, China was identical to the species we describe, and it is likely that the new species is not restricted to Vietnam. As a priority, future work should focus on determining the distribution of this species, as well as understanding population and life history traits such as reproductive rate.

Numerical investigation of the impact of toothed fins on the heat transfer performance of a shell-and-tube exchanger during phase change material melting process

The poor thermal conductivity of phase transition materials hampers the development of latent heat energy storage devices. There is much scholarly interest in enhancing heat transmission in these materials. Using a finned shell-and-tube exchanger is a traditional strategy for improving the effectiveness of latent thermal energy storage devices. However, the storage systems' actual working volume decreases when many fins are added. Numerous studies have shown that toothed fins are more efficient in transferring heat than regular fins. As a result, it is anticipated that toothed fin latent heat energy storage systems will produce better thermal effects. Unfortunately, the impact of toothed fins on the melting of phase transition materials has only been briefly discussed in published literature. To close this important knowledge gap, this paper thoroughly studies two regularly used fins, namely the annular fin and longitudinal fin with toothed apertures. The impact of different toothed-opening volumes and tooth spacing on the melting process of phase transition materials are examined using numerical simulations. The results show that toothed fins have a 20% lower fin volume than traditional circular and longitudinal fins, which has a marginally less positive impact on phase change material melting times of 1.09% and 0.98%, respectively. The recommended toothed-opening volume and tooth count for the annular fin are 10%–20% and 16 teeth, respectively, whereas the recommended toothed-opening volume and tooth spacing for the longitudinal fin are 10%–20% and 1 mm, respectively. Additionally, the tooth spacing affects heat transfer, in one investigation, decreasing the tooth spacing by 2.5 and 2 times led to reductions in the melting periods of phase change materials of 60 and 70 s, respectively.