Search Results (131)

Background: Charcot–Marie–Tooth (CMT) is a group of inherited diseases impairing the peripheral nervous system. CMT originates from genetic variants that affect proteins fundamental for the myelination of peripheral nerves and survival. Moreover, environmental and humoral factors can impact disease development and evolution. Currently, no therapy is available. Metabolomics is an emerging field of biomedical research that enables the development of novel biomarkers for neurodegenerative diseases by targeting metabolic pathways or metabolites. This study aimed to evaluate the metabolomics profile of CMT disease by comparing patients with healthy individuals. Methods: A total of 22 CMT patients (CMT) were included in this study and were demographically matched with 26 healthy individuals (C). Serum samples were analyzed through Nuclear Magnetic Resonance spectroscopy, and multivariate and univariate statistical analyses were subsequently applied. Results: A supervised model showed a clear separation (R²X = 0.3; R²Y = 0.7; Q² = 0.4; p-value = 0.0004) between the two classes of subjects, and nine metabolites were found to be significantly different (2-hydroxybutyrate, 3-hydroxybutyrate, 3-methyl-2-oxovalerate, choline, citrate, glutamate, isoleucine, lysine, and methyl succinate). The combined ROC curve showed an AUC of 0.94 (CI: 0.9–1). Additional altered metabolic pathways were also identified within the disease context. Conclusion: This study represents a promising starting point, demonstrating the efficacy of metabolomics in evaluating CMT patients and identifying novel potential disease biomarkers. Full article

This study presents an analysis of the electromagnetic noise and vibration in a surface-mounted permanent magnet synchronous machine (SPMSM), focusing on their excitation sources. To investigate this, the excitation sources were identified through an analytical approach, and their effects on electromagnetic noise and vibration were evaluated using a finite element method (FEM)-based analysis approach. Additionally, an equivalent curved-beam model based on three-dimensional shell theory was applied to determine the deflection forces on the stator yoke, accounting for the tooth-modulation effect. The stator’s natural frequencies were derived through the characteristic equation in free vibration analysis. Modal analysis was performed to validate the analytically derived natural frequencies and to investigate stator deformation under the tooth-modulation effect across various vibration modes. Furthermore, noise, vibration, and harshness (NVH) analysis via FEM reveals that major harmonic components align closely with the natural frequencies, identifying them as primary sources of elevated vibrations. A comparative study between 8-pole–9-slot and 8-pole–12-slot SPMSMs highlights the impact of force variations on the stator teeth in relation to vibration and noise characteristics, with FEM verification. The proposed method provides a valuable tool for early-stage motor design, enabling the rapid identification of resonance operating points that may induce severe vibrations. This facilitates proactive mitigation strategies to enhance motor performance and reliability. Full article

Background/Objectives: Prolonged use of denosumab in patients with metastatic breast cancer has raised concerns about the development of medication-related osteonecrosis of the jaw (MRONJ). However, the threshold at which the risk increases remains unclear. Methods: This retrospective cohort study analyzed patients with breast cancer and bone metastases who received denosumab between May 2012 and August 2024. Associations between cumulative denosumab administration and MRONJ were evaluated using univariate and multivariate logistic regression analyses. A receiver operating characteristic (ROC) analysis was used to determine the optimal cutoff for cumulative doses. Results: MRONJ developed in 101 patients (31.2%). Multivariate analysis identified cumulative denosumab administration (odds ratio [OR]: 1.05, 95% confidence interval [CI]: 1.03–1.06; p < 0.001) and a history of tooth extraction (OR: 4.40, 95% CI: 2.23–8.71; p < 0.001) as independent risk factors for MRONJ. ROC analysis determined an optimal cutoff of 32 cumulative doses, with an area under the curve of 0.83 (95% CI: 0.78–0.88; p < 0.0001). Conclusions: Cumulative denosumab administration and history of tooth extraction were independent risk factors for MRONJ in patients with breast cancer and bone metastases. The risk of MRONJ increased after 32 cumulative doses, providing a clinically actionable threshold for risk assessment and patient monitoring. Full article

Background: Intraoral scanners have become increasingly popular for final dental prostheses due to their precision, efficiency, and patient-friendly approach. However, their use for capturing final impressions of highly esthetic and thin restorations, such as ceramic veneers, presents unique challenges. Veneer preparations differ significantly from traditional full-coverage crowns, with their smaller and more delicate margins often located at or below the gingival level. This complexity may lead to hesitancy among clinicians regarding the routine use of intraoral scanners in such cases. Methods: A comprehensive literature review was performed to evaluate the effectiveness of intraoral scanners for final digital impressions in ceramic veneer restorations within the esthetic zone. Studies published between January 2010 and January 2025 were included in the review. Additionally, a case illustration was provided, detailing the use of an intraoral scanner to capture final impressions for a patient requiring 10 ceramic veneers in the esthetic zone. Results: The review demonstrated that intraoral scanning is a reliable technique for veneer impressions, delivering clinically acceptable outcomes. The benefits include enhanced patient comfort, improved workflow efficiency, and a reduction in chairside time. Nonetheless, clinicians must overcome a learning curve with digital technologies and ensure optimal conditions, such as maintaining a dry tooth surface during scanning. The presented case successfully illustrated the use of intraoral scanning, resulting in precise impressions and the fabrication of highly esthetic and functional veneers. Conclusions: Intraoral scanning is a predictable and effective method for capturing final impressions for veneer restorations. It offers results comparable to traditional methods while enhancing patient experience and enabling the fabrication of high-quality restorations within an efficient workflow. Full article

Recently, with policies aimed at strengthening domestic manufacturing and technological innovation, the robotics industry has been growing rapidly, and its applications are expanding across various industrial fields. Accordingly, the importance of high-performance speed reducers with flexibility and precision is gradually increasing. The tooth profiles used in conventional harmonic reducers have structural limitations, such as meshing discontinuity, restrictions on the radius of curvature of the tooth base, and distortion of the contact trajectory, especially when the number of teeth is small. These problems limit the design freedom of the reducer and make it difficult to secure contact stability and durability under precision driving conditions. To solve these problems, this paper proposes a new tooth profile design equation, the IH (Involute Harmonic) tooth profiles and the HTPs (Hybrid Tooth Profiles), using the cycloid curve to overcome the structural limitations of the conventional harmonic tooth profile, which is difficult to design under small-tooth-number conditions, and to enable tooth design without restrictions on the number of teeth. HTP tooth profile is a new gear tooth profile design method that utilizes IH tooth profile and cycloid curve to optimize the meshing characteristics of gears. A tooth profile design tool based on the HTP equation was developed using Python 3.13.3. The tool’s effectiveness was validated through simulations assessing tooth meshing and interference. Using the tool, an R21_z3 reducer with a single-stage high reduction ratio was designed to evaluate practical applicability. A prototype was fabricated using 3D printing with PLA material, and experimental testing confirmed the absence of meshing or interference issues, consistent with simulation results. Through this study, we verified the usefulness of the HTP tooth profile design formula and design tool using the IH tooth profile and cycloid curve, and it is expected that the proposed HTP tooth profile can be utilized as a tooth profile applicable to various reducer designs. Full article

Chiggers (chigger mites) and gamasid mites are two groups of ectoparasites on rodents, and they can be the vectors or potential vectors of scrub typhus and hemorrhagic fever with renal syndrome (HFRS), while Bower’s white-toothed rat (Berylmys bowersi) can serve as the reservoir host of the diseases. Based on field investigations at 117 survey sites of southwest China, a total of 2512 mites were collected from 55 B. bowersi rats. Under a microscope, these mites were taxonomically identified as 56 distinct species, comprising 37 chigger mite species and 19 gamasid mite species. The mite infestation burdens on B. bowersi were heavy, with a high prevalence (P_M = 85.45%), mean abundance (MA = 45.67), and intensity (MI = 53.45). Of 56 mite species identified, 7 are vectors of scrub typhus and HFRS. Of the seven vector mite species, Leptotrombidium scutellare was one of dominant chigger species, with a higher infestation index on rats (P_M = 21.82%, MA = 7.76) than the other six vector mite species. The sex ratio of female gamasid mites was higher than that of males. The number and infestation of adult gamasid mites were higher than those of immature mites. The infestation indexes of mites on B. bowersi hosts varied with the host’s sex and age and fluctuated along different environmental gradients. The association coefficient (V) showed a slight positive association between chiggers and gamasid mites, suggesting that these two groups of mites may coexist on B. bowersi rats. Spearman correlation coefficients showed positive correlations among some dominant and vector mite species, indicating that some mite species tend to select the same hosts. A total of 69 mite species (47 chigger mite species and 22 gamasid mite species) on B. bowersi were estimated by species rarefaction and extrapolation curves. In conclusion, Berylmys bowersi has a high susceptibility to mite infestation, and it has the potential to harbor abundant mites, with heavy mite burdens. The occurrence of vector mite species, especially L. scutellare (the dominant species), increases the potential risk of transmission and the focus persistence of scrub typhus and HFRS in southwest China. Full article

(1) Background: The aim of this in vitro study was to evaluate the success of indirect pulp capping (IPC) procedures over a period of 40 years. (2) Methods: The investigation of 1412 dental records included 159 patients with 366 IPC teeth having been treated from 1969 to 1980. The teeth revealed caries within the inner third of dentin, were symptom-free, and showed no pulp exposure. The caries were excavated thoroughly and teeth with accidentally exposed pulp were excluded. Zinc–oxide–eugenol was used for the IPC procedures. The posterior teeth were restored with amalgam, and the anterior teeth received direct resin composite fillings. The gathered parameters with possible influences on survival rates were age, gender, tooth locations/positions, dates of vital therapy, the number of filled surfaces, types of primary restoration material, successional treatments on each tooth, and the last dates of surveillance. Data collection and statistical analysis were performed using Excel sheets and DataTab. Significant differences among groups were computed by cox regression analysis and the significance level was set at p = 0.05. Kaplan–Meier curves were utilized to illustrate the survival rates. (3) Results: Treatment success was measured by the maintenance of vitality beyond 365 days. The loss of vitality within 365 days was determined as treatment failure. Treatment outcomes were assessed after different time periods (1 and 6 months; 1, 2, 5, 10, 20, and 40 years). Pulp vitality dropped from 95% after 3 months to 32% after 40 years. Cavity size had a significant influence on the survival of pulp, but tooth position did not; however, third molars at least initially showed a better outcome. Beyond the 1-year recall, no differences for the evaluated parameters were present. (4) Conclusions: IPC showed excellent long-term success rates, revealing a 1.7% annual failure rate after 40 years of clinical service. Larger defects suffer more pulp damage in the long run. Full article

In order to study the breaking mechanism of rock of high-speed PDC drill bits, improve the cutting efficiency of cutting teeth, and reduce the wear of cutting teeth, the rock-breaking process of PDC cutting teeth is simulated based on mechanical theory knowledge and experiments in this paper. And the influence of changes in PDC tooth rake angle, cutting depth, and diameter of the cutting tooth was studied by changing the different structural and cutting parameters of the cutting teeth, as well as the changes in cutting force, frictional resistance stress, and contact pressure on PDC teeth during the cutting process. The simulated results show that the total energy of the system increases, and the total energy of the system is the largest when cutting at 45°, which coincides with the maximum contact pressure on the teeth at this time. At the same time, it also shows that the impact resistance of PDC teeth is the strongest when chamfered at 45°. The contact area is also smaller, so the cutting is more conducive to the cutting tooth eating into the formation and prolonging the service life of the cutting tooth when the tooth rake angle is 20°. The experimental results showed that, in the actual design of PDC drill bits, an appropriate smaller side angle is not only beneficial for chip removal, but also helps to prevent lateral vibration and does not have a significant impact on cutting load. Finally, obtaining the relationship curve between structural parameters and rock properties is of great significance for guiding the design of PDC drill bits, understanding the intrinsic mechanism of rock fragmentation, and revealing the macroscopic nonlinear mechanical behavior of rocks. Full article

The classical approach for the preparation of an endodontically treated molar with a post and core involves widening the anatomically complex system of canals, which may be narrow or curved with variable angulation. The aforementioned along with the fact that restorative dentistry stands against the wastage of tooth tissue make endocrowns an appealing alternative. Bindl and Mörmann first described an all-ceramic crown anchored to the internal portion of the pulp chamber and on the cavity margins, thus obtaining macromechanical retention provided by the axial opposing pulpal walls and microretention attained with the use of adhesive cementation. The purpose of this report is to describe the protocol for the treatment plan selection, preparation, impression, and adhesive cementation of an endocrown with a follow-up of 5 years. A 56-year-old male patient presented to the Postgraduate Clinic of Prosthodontics seeking rehabilitation for tooth No. #36. A clinical examination revealed multiple immediate composite resin restorations with unacceptable morphology and adaptation to the remaining tooth as well as a lack of a contact point but, rather, a large, concave contact area facilitating food entrapment. Since the tooth was endodontically treated, the proposed treatment plan included the fabrication of an all-ceramic endocrown. The steps of preparation, attribution of the correct shape, impression, and adhesive luting under rubber dam isolation are thoroughly described. The final functional and aesthetic result, patient’s satisfaction, and the 5-year follow-up render restorations such as endocrowns, which draw their retention from adhesive luting, a viable alternative to conventional approaches. Full article

Form grinding is a precision machining method for the modified ZI worms, and the grinding accuracy mainly depends on the dressing accuracy of the grinding wheel’s profile. A mathematical model of the modified involute helicoid of ZI worms is established based on the curve superposition method. Subsequently, the normal vector of the tooth surface is derived. After that, space meshing theory and matrix transformation methods are applied. Thus, the meshing equation between the grinding wheel and the tooth surface during the form grinding is constructed. Based on the equal error principle, an interpolation algorithm for the modified involute is proposed. The nonlinear meshing equations are solved using MATLAB R2019b software to obtain the discrete point coordinates of the worm end section profile and the grinding wheel axial section profile. The derivative of the discrete points is calculated by using the difference method, and the motion trajectory of the diamond wheel during the grinding wheel dressing process is solved based on the equidistant curve theory. The proposed methods holds certain reference value for calculating the profile of grinding wheels used in the form grinding of modified ZI worms. Full article

Objectives: To determine the extent to which anteroposterior head inclination influences smile arc curvature assessment on frontal photographs. Materials and Methods: Sixty-three young adults participated in this study. Each had five standardized frontal-view photographs captured with posed smiles at five anteroposterior head inclinations (−20°, −10°, 0°, +10°, +20°) using a cervical range of motion device. Two curves were traced per photograph: one following the shape of the lower lip and the other the incisal edge of the maxillary anterior teeth from canine to canine (smile line). These curvatures were approximated by quadratic function and compared for concordance based on the maximum curvature of the obtained functions. A score was calculated, with 0 denoting a consonant smile (perfect concordance) and 2 a non-consonant smile. Results: Among the sixty-three participants, fifty-nine were included in the analysis after excluding those with insufficient tooth exposure in the photographs for the smile line assessment. The analysis revealed that the perceived smile line was more consonant (concordant with lower lip curvature) with a −20° head anteroposterior inclination (score: 0.146), and the least consonant with +20° anteroposterior inclination (score: 1.326), with statistically significant differences (p < 0.05). Conclusions: The smile arc curvature assessment on frontal photographs may be influenced by the anteroposterior inclination of the head on frontal photographs. However, due to the two-dimensional nature of this study, further investigations incorporating three-dimensional imaging are recommended. Full article

Innovating seal structures and optimizing size parameters are effective ways to enhance the leakage characteristics of labyrinth seals (LSs). Inspired by the ecological fishways with high flow resistance on dam sides, a novel bio-inspired staggered labyrinth seal is proposed. The leakage characteristics of both the curved-edged bio-inspired labyrinth seal (CELS) and the straight-edged bio-inspired labyrinth seal (SELS) at different tooth-incline angles are studied numerically and experimentally. The influence of key geometrical parameters on the leakage characteristics and flow field parameters of the CELSs are investigated, and the leakage control mechanism of bio-inspired LSs is revealed via analyzing flow field parameter distribution. The results indicate that, compared to conventional double-sided staggered straight-tooth labyrinth seals, the leakage rate reduction in CELSs is up to 30% when the incline angle is equal to 25°, outperforming that of the SELS in leakage control. This improvement is mainly attributed to the flow path bending and jet contraction effects at the tooth-tip entrance, along with the thermodynamic effects of the high-turbulence dissipation zone adjacent to the tooth top. The optimum leakage characteristics can be achieved when seal clearance h < 0.5 mm, aspect ratio δ < 0.6, and tooth thickness t < 1.5 mm. This work provides new insights into the structural design of high-resistance and low-leakage labyrinth seals. Full article

Considering the elasticity of gear solid bodies, the load applied to gear teeth will force theoretically separated gear teeth to get into engaging state in advance. This phenomenon is named as the extended tooth contact (ETC). Effects of the ETC directly influence the time-varying mesh stiffness of gear pairs and subsequently alter nonlinear dynamic characteristics of gear transmission systems. Time-vary mesh stiffness, considering effects of the ETC, is thus introduced into the dynamic model of the gear transmission system. Periodic motions of a gear transmission system are discussed in detail in this work. The analytical model of time-varying mesh stiffness with effects of the ETC is proposed, and the effectiveness of the analytical model is demonstrated in comparison with finite element (FE) results. The gear transmission system is simplified as a single degree-of-freedom (DOF) model system by employing the lumped mass method. The correctness of the dynamic model is verified in comparison with experimental results. An incremental harmonic balance (IHB) method is modified to obtain periodic responses of the gear transmission system. The improved Floquet theory is employed to determine the stability and bifurcation of the periodic responses of the gear transmission system. Some interesting phenomena exist in the periodic responses consisting of “softening-spring” behaviors, jump phenomena, primary resonances (PRs), and super-harmonic resonances (SP-HRs), and saddle-node bifurcations are observed. Especially, effects of loads on unstable regions, amplitudes, and positions of bifurcation points of frequency response curves are revealed. Analytical results obtained by the IHB method match very well with those from numerical integration. Full article

This study presents a novel method for calculating the stress and bending moment in reinforced concrete (RC) beams strengthened with prestressed near-surface-mounted (NSM) carbon fiber-reinforced polymer (CFRP), focusing specifically on separation failure at the end concrete cover. By characterizing the geometry of the failure body and integrating it with the concrete tooth model, a comprehensive theoretical framework has been developed. This framework utilizes sectional strain distribution characteristics to establish the bending moment–curvature relationship and the load–deflection curve during loading. Comparisons with experimental data confirm the accuracy and applicability of this analytical model. The results demonstrate that the model is capable of accurately predicting the load–deflection behavior of the strengthened beam. Additionally, this study underscores the substantial impact of the CFRP prestress level on the concrete cover separation failure, showing that optimizing prestress settings can effectively enhance the ductility and bearing capacity of the strengthened beam. Full article

This paper investigates the design methodologies of pure rolling helical gear pumps with various tooth profiles, based on the active design of meshing lines. The transverse active tooth profile of a pure rolling helical gear end face is composed of various function curves at key control points. The entire transverse tooth profile consists of the active tooth profile and the Hermite curve as the tooth root transition, seamlessly connecting at the designated control points. The tooth surface is created by sweeping the entire transverse tooth profile along the pure rolling contact curves. The fundamental design parameters, tooth profile equations, tooth surface equations, and a two-dimensional fluid model for pure rolling helical gears were established. The pressure pulsation characteristics of pure rolling helical gear pumps and CBB-40 involute spur gear pumps, each with different tooth profiles, were compared under specific working pressures. This comparison encompassed the maximum effective positive and negative pressures within the meshing region, pressure fluctuations at the midpoints of both inlet and outlet pressures, and pressure fluctuations at the rear sections of the inlet and outlet pressures. The results indicated that the proposed pure rolling helical gear pump with a parabolic tooth profile exhibited 42.81% lower effective positive pressure in the meshing region compared to the involute spur gear pump, while the maximum effective negative pressure was approximately 27 times smaller than that of the involute gear pump. Specifically, the pressure pulsations in the middle and rear regions of the inlet and outlet pressure zones were reduced by 33.1%, 6.33%, 57.27%, and 69.61%, respectively, compared to the involute spur gear pump. Full article