Search Results (768)

Background: Clear aligners have become a common alternative to fixed appliances for tooth movement, and thermoplastic retainers hold the outcome. The prolonged intraoral contact of these devices has made the materials a focus of biocompatibility research. Objectives: This paper aims to summarize laboratory evidence on the biocompatibility of clear aligners and thermoplastic retainers. Materials included thermoformed polyethylene terephthalate glycol-modified (PETG), multilayer polyurethane, and directly printed resins. Primary outcomes were cytotoxicity, endocrine activity, and chemical or particle release. Methods: We systematically searched PubMed, the Cochrane Library, and Google Scholar through 31 May 2025, and we followed the PRISMA 2020 statement (Preferred Reporting Items for Systematic Reviews and Meta-Analyses). We applied predefined eligibility criteria. Two reviewers screened records and extracted data in duplicate, including study design, extraction conditions, surface-area-to-volume ratio (SA/V), cell models, endpoints, and analytical sensitivity as the limit of detection (LOD) and limit of quantification (LOQ). We assessed the risk of bias across seven domains and graded certainty by outcome. The Supplementary File provides full search strategies, data, and the extraction workbook. We did not register a protocol prospectively. Results: Seventeen studies met the inclusion criteria. Materials spanned multilayer polyurethanes (SmartTrack, Clarity), PETG sheets (Essix ACE, Duran), and directly printed resins (Graphy TC-85DAC); a subset tested zinc-oxide (ZnO) nanoparticle coatings. Typical extractions immersed 0.1–1 g of material in cell-culture medium or artificial saliva at 37 °C for 24 h to 30 days. Cell viability usually remained ≥80%. Mild cytotoxicity (about 60–70% viability) appeared with harsher extractions, extended soaks, or an inadequate post-curing of printed parts. The estrogen-sensitive proliferation assay (E-Screen) returned negative results. In saliva-like media, bisphenol A (BPA) and related leachables were undetectable or in the low ng/mL range. In printed resins, urethane dimethacrylate (UDMA) sometimes appeared in water extracts, and amounts varied with curing quality. Evidence for chemical leaching and endocrine outcomes is sparse. We found no eligible in vitro study that quantified particle or microplastic release while also measuring a biological endpoint; we discuss particle findings from mechanical wear simulations only as the external context. Limitations: The evidence base is limited to in vitro studies. Many reports incompletely described extraction ratios and processing parameters. Risk of bias and certainty: Most studies used appropriate cell models and controls, but the reporting of surface-area-to-volume ratios, LOD/LOQ, and detailed post-processing parameters was often incomplete. Sample sizes were small, and dynamic wear or enzymatic conditions were uncommon. The overall risk of bias was moderate, and the certainty of evidence was low to moderate due to heterogeneity and in vitro indirectness. Conclusions: Under standard laboratory conditions, clear aligners and thermoplastic retainers show a favorable biocompatibility profile. For printed resins, outcomes depend mainly on processing quality, especially thorough washing and appropriate light-curing parameters. To improve comparability and support clinical translation, we recommend harmonized test protocols, transparent reporting, interlaboratory ring trials, and targeted clinical biomonitoring. Full article

The widely used oximeter design was adopted and improved as the configuration mainframe in this study to acquire PPG signals. When users wear a finger probe and input their height, the device acquires PPG signals through the probe circuit, then filters and amplifies the signals to remove unnecessary noise, and uses an ARM-M4 to analyze the main peak, dicrotic wave, and wave valley of the PPG waveform to calculate related indexes for the final assessment. After 100 s, the HRV, sine wave ratio, and SI results are estimated, and a cardiovascular disease risk assessment is presented using a risk level from 0 to 5. This study uses the stiffness index (SI), sine wave ratio (SIN), and heart rate variability (HRV) to assess cardiovascular status. The SI is derived from PPG signal characteristics and reflects vascular stiffness based on blood flow rebound time. However, some PPG signals lack a dicrotic wave (sine waves), which is often caused by severe arterial stiffness. These waveforms lead to errors in SI calculation due to misidentification of the dicrotic wave. The appearance of a sine wave indicates that blood pulsation is abnormal; however, it will make the SI calculation algorithm produce a seemingly normal health performance. To address this, the auxiliary line method was introduced to identify sine waves, and the SIN ratio occurring in contiguous PPG waves was incorporated to calculate their proportion in PPG signals, aiding SI analysis and arterial stiffness evaluation. The total power (TP) value obtained via HRV frequency-domain analysis reflects autonomic nervous activity. As reduced autonomic function may relate to cardiovascular diseases, TP is included as an evaluation indicator. By analyzing PPG signals, calculating SI and SIN, and integrating the HRV indicator, this study evaluates arterial stiffness and cardiovascular health, helping participants understand their physical condition more quickly and conveniently, and potentially preventing cardiovascular diseases at an early stage. Full article

The oil and gas sector encounterssignificant material problems during acid stimulation, particularly under high temperatures, high pressures, and corrosive conditions with CO₂ and H₂S. This study focused on corrosion and erosion failures of tungsten carbide jetting nozzles in coiled tubing bottom hole assemblies. While tungsten carbide is durable, its high price, restricted machinability, and scarcity necessitate the search for viable alternatives. This study sought to identify and validate a low-cost, readily available, and easily machinable alloy with equivalent performance. A rigorous material selection approach took into account thermochemical stability, mechanical strength, and corrosion resistance under simulated downhole circumstances. Candidate alloys, both coated and uncoated, were subjected to extensive laboratory testing, including acid compatibility, high-temperature corrosion, erosion resistance, and mechanical integrity assessments. The majority failed due to pitting or surface deterioration. However, one coated alloy system was very resistant to chemical and thermal damage. To support long-term performance, a machine learning model relying on Gradient Boosting was created to forecast corrosion behavior using operational factors; demonstrating effective prediction characteristics compared with four other models. This AI-powered tool allows for accurate prediction of corrosion risks and aids decision-making by determining whether the material will maintain integrity under harsh acidic conditions. Field tests proved the selected alloy’s durability and jetting efficiency during many acid stimulation cycles. The corrosion and wear performance of coated 4145 material demonstrates a validated, cost-effective alternative to tungsten carbide with only four times lower corrosion resistance than carbide, outperforming other alloy combinations with up to 35 times higher corrosion rates. These results reveal tremendous opportunities for improving material design in corrosive energy applications. Full article

With the continuous increase in high-speed train operation speeds, lightweight bogie design has become a key means to enhance dynamic performance, which also increases the risk of structural fatigue. High-frequency wheel–rail excitations are transmitted to the bogie frame and couple with its higher-order modes at around 200 Hz, inducing local high-frequency resonance. This coupling markedly increases the stress amplitude within the affected frequency range and accelerates vibration-induced fatigue damage. This study investigates the vibration fatigue characteristics of a bogie frame with an inner axle box under high-speed operation and wheel polygon wear conditions. Using a high-speed wheel–rail interaction test rig, dynamic stresses and the vibration acceleration of the bogie frame are measured under different speeds and polygon orders. Based on modal analysis and vibration fatigue methods, a high-frequency vibration fatigue assessment method for the bogie is developed. Wheel polygon significantly amplifies mid-to-high-frequency vibration energy, and for the bogie frame with an inner axle box, pronounced modal coupling is observed at around 200 Hz. In particular, under the 11th-order polygon condition, the equivalent stress at critical locations such as the traction motor seat weld seam exceeds the fatigue limit, while the effect of the 20th-order polygon is relatively mitigated. The proposed vibration fatigue assessment method provides a theoretical basis for the safe design and operational maintenance of high-speed trains with bogie frames with inner axle boxes. Full article

Clear aligners have gained popularity in orthodontics due to their aesthetics, comfort, and removability; however, their prolonged intraoral wear and frequent removal–reinsertion cycles create favorable conditions for microbial colonization. This in vitro study evaluated the efficacy of seven commercially available mouthwash formulations in inhibiting biofilms of Streptococcus mutans, Streptococcus oralis, and Candida albicans formed on four different clear aligner materials. Standardized aligner fragments were incubated for 24 h with microbial suspensions to allow biofilm formation, treated for 1 min with one of the mouthwashes, and then assessed for residual viability through spectrophotometric optical density measurements after a further 24 h incubation. Biofilm inhibition varied according to both mouthwash composition and aligner material. The chlorhexidine-based rinse (MW-D) consistently showed the highest inhibition across microorganisms, while the fluoride–cetylpyridinium chloride rinse (MW-B) performed strongly for S. oralis and C. albicans. An essential oil-based formulation with xylitol (MW-G) showed notable antifungal activity against C. albicans. Monolayer polyurethane aligners generally achieved higher inhibition rates than multilayer or copolyester-based materials. These findings indicate that antimicrobial efficacy on aligners depends on both mouthwash type and material, supporting a tailored approach to biofilm management in clear aligner therapy to reduce the risk of caries, periodontal disease, and candidiasis. Full article

This study examines the modernization of the 61-4179 TVZ passenger coach for transporting light automobiles up to 3 tons, addressing the efficiency of multifunctional rail use. The objective was to assess how additional mass–dimensional loading influences strength, load distribution, and the dynamic stability of the vehicle–track system. Finite element simulations in ANSYS Workbench 2021 R2 determined stress distribution, deformations, and safety margins, while multibody dynamics modeling in Universal Mechanism evaluated wheel–rail contact forces, carbody accelerations, and stability coefficients. Field tests on curves with radii of 350 m and 300 m at 60 km/h validated the models. Carbody accelerations were 0.65–0.68 m/s², below the 0.7 m/s² regulatory limit; wheelset attack angles remained under 0.01 rad; and derailment safety coefficients were 1.6–1.8, all meeting international standards. Uniform load distribution maintained stability and suppressed oscillations. However, critical scenarios (wheel wear, extreme flange clearance, higher speeds) produced parameters approaching threshold values. To mitigate risks, clearance adjustment per δ₀ standards, a 1:20 guard-rail inclination, and optimized crossing profiles are proposed. These measures reduced lateral dynamic forces by 12–15% and raised the strength coefficient by 1.2–1.3. The results confirm technical feasibility, operational safety, and extended service life, supporting sustainable multimodal transport development. Full article

In the context of Industry 4.0 and smart manufacturing, predicting cutting tool remaining useful life (RUL) is crucial for enabling and enhancing the reliability and efficiency of CNC machining. This paper presents an innovative predictive model based on the data fusion architecture of Graph Neural Networks (GNNs) and Transformers to address the complexity of shallow multimodal data fusion, insufficient relational modeling, and single-task limitations simultaneously. The model harnesses time-series data, geometric information, operational parameters, and phase contexts through dedicated encoders, employs graph attention networks (GATs) to infer complex structural dependencies, and utilizes a cross-modal Transformer decoder to generate fused features. A dual-head output enables collaborative RUL regression and health state classification of cutting tools. Experiments are conducted on a multimodal dataset of 824 entries derived from multi-sensor data, constructing a systematic framework centered on tool flank wear width (VB), which includes correlation analysis, trend modeling, and risk assessment. Results demonstrate that the proposed model outperforms baseline models, with MSE reduced by 26–41%, MAE by 33–43%, R² improved by 6–12%, accuracy by 6–12%, and F1-Score by 7–14%. Full article

Background/Objectives: Children who have received hematopoietic cell transplants (HCTs) often face complex clinical courses and complications that increase their risk of functional impairments. Because of this, pediatric HCT recipients may benefit from early mobilization efforts to reduce long-term functional issues. However, early ambulation can be limited by clinical complexity and concerns about infectious transmission in HCT patients. Some patients are under contact precautions due to colonization with bacteria that produce extended-spectrum beta-lactamase (ESBL) enzymes. Our goal was to significantly increase ambulation in pediatric HCT recipients at our institution within three months of the intervention. We aimed to raise the number of ambulation events per day, the number of physical therapy (PT) visits per week, and the distance patients walked with PT per session. Methods: From January to October 2022, data on mobilization, demographics, and clinical characteristics were retrospectively collected from electronic health records. Starting in June 2022, we permitted ESBL-colonized patients to leave their rooms while wearing personal protective equipment (PPE), and we trained clinical staff about this in our QI initiative. Results: In Group 1, the ambulation rate was 1.36 times higher before the intervention than after, with an effect size of 0.3042 (p = 0.004 *). The ambulation rate in Group 2, admitted before the intervention, was 1.33 times higher than in Group 3, admitted after the intervention, with an effect size of 0.2856 (p = 0.016 *). Conclusions: The initiative did not increase ambulation among the targeted group. Patients ambulated more before the intervention, though these results lack statistical power. The lack of success of the intervention may be due to various factors, including the short monitoring period, retrospective data collection, difficulties with PPE use among young patients, and uncollected confounding variables related to clinical status. Full article

Corneal nerves play a crucial role in maintaining ocular surface homeostasis by supporting the functional integrity of corneal epithelial, stromal, and endothelial cells; modulating tear secretion; and facilitating sensory responses essential for overall ocular health. With advancing age, these highly specialized peripheral sensory fibers undergo progressive attrition and morphologic distortion driven by the canonical hallmarks of aging including genomic instability, impaired proteostasis, mitochondrial dysfunction, and chronic low-grade inflammation. The resulting neuro-immune dysregulation reduces trophic support, delays wound healing, and predisposes older adults to dry-eye disease, neurotrophic keratopathy, and postsurgical hypoesthesia. Age-exacerbating cofactors including diabetes, dyslipidemia, neurodegenerative disorders, topical preservatives, chronic contact-lens wear, herpes zoster ophthalmicus, and ocular-surface hypoxia further accelerate sub-basal nerve rarefaction and functional decline. This review provides an overview of age-related physiological alterations in ocular surface nerves, with a particular emphasis on corneal innervation. It also discusses risk factors that speed up these changes. Given the inherently limited regenerative capacity of corneal nerves and their inability to fully restore to baseline conditions following injury or degeneration, it is critical to identify and develop effective strategies aimed at mitigating or delaying physiological nerve degeneration and promoting nerve regeneration. This review also brings up emerging therapeutic strategies, including regenerative medicine, neuroprotective agents, and lifestyle interventions aimed at mitigating age-related corneal nerve degeneration. Full article

Introduction: Purpureocillium lilacinum (formerly Paecilomyces lilacinus) is an emerging, saprophytic fungus known to cause severe, treatment-refractory ocular infections. It is notoriously clinically resistant to several common antifungal agents, including amphotericin B. Risk factors for Purpureocillium lilacinum (P. lilacinum) keratitis include contact lens wear, ocular trauma, and local or systemic immunosuppression. Case Presentation: We describe the clinical course of a 70-year-old male with type 2 diabetes mellitus and a history of long-term soft contact lens use who presented with a right corneal ulcer. Despite initial treatment with topical voriconazole, the infection progressed over two months to involve the entire globe, resulting in intractable endophthalmitis. Microbiological analysis of corneal scrapings identified P. lilacinum, confirmed by MALDI-TOF mass spectrometry and ITS sequencing. Despite the addition of systemic voriconazole, the patient’s condition deteriorated, leading to a painful blind right eye which ultimately needed enucleation. Conclusions: This case highlights the aggressive potential of P. lilacinum in a host with multiple risk factors. It underscores the critical need for a high index of suspicion, rapid and accurate mycological diagnosis, and immediate, aggressive management. The therapeutic challenges, including intrinsic and emerging antifungal resistance, often necessitate early surgical intervention to prevent catastrophic outcomes. Full article

Background: Patients with diabetes mellitus are at increased risk of foot ulcerations. Prevention and timeous treatment of diabetic foot ulcer requires a multidisciplinary team, including patients and healthcare workers. The study investigated levels of knowledge regarding foot care and prevention of diabetic foot ulcer in patients with diabetes mellitus. Methods: We conducted a cross-sectional descriptive study using structured face-to-face interviews of patients seen at the outpatient department. Interviews covered socio-demographic and clinical characteristics, and foot care practices. Statistical analysis was performed using STATA 15. Results: The study involved 245 participants with a mean age of participants was 53.7 (SD) years, and 69% were female. The majority, 77.6%, had Type 2 diabetic mellitus (DM). Mean score of appropriate knowledge on diabetic foot ulcer (DFU) was 73.5%, lower scores were 44.9% and 45.7% for moisturizing between toes and wearing slippers outdoors, respectively. Knowledge of foot care was significantly influenced by age (p = 0.0033), duration of DM (p = 0.047), treatment type (p = 0.002), prior education on foot care (p < 0.0001), and existence of foot complications (p = 0.030). Conclusions: Younger patients and those with Type 1 diabetes mellitus had less knowledge of appropriate foot care and prevention of DFU. We recommend the implementation of structured and targeted educational interventions. Full article

Fluoride prophylaxis is a cornerstone in preventing dental caries, a disease for which orthodontic patients are at high risk due to the reduced effectiveness of home oral hygiene and increased plaque accumulation. Recent evidence defines caries as polymicrobial, involving Streptococcus mutans, Lactobacilli, and emerging species such as Selenomonas sputigena. This prospective, randomized, controlled study evaluated professional topical fluoride in the form of gel and varnish in 68 patients aged 8–17 years wearing fixed orthodontic appliances. Participants were divided into three equal groups: two intervention groups and one control group. Clinical parameters (DMFT, salivary pH, PCR%) and microbiological analyses of plaque and saliva (oral Streptococci, S. mutans, S. sputigena, Lactobacilli, total bacterial count) were assessed at baseline (T0) and after 4 months (T1), following professional hygiene and fluoride application for the intervention groups. At T1, salivary pH increased in the gel group, and PCR% decreased significantly in all groups, with the most pronounced decrease observed in the varnish group. PCR analysis showed a higher rate of S. mutans and S. sputigena negativization in intervention groups. Culture-based analyses revealed reductions in oral Streptococci and Lactobacilli in intervention groups, while levels increased in controls. Overall, both clinical and microbiological variables indicated improvements in the fluoride-treated groups compared to controls, highlighting the efficacy of professional fluoride prophylaxis in orthodontic patients. Full article

Acne is a multifactorial skin condition characterized by an infection in the pilosebaceous units in the skin. Patients with acne suffer from comedones, papules, pustules and nodules or cysts in severe cases. These clinical features might cause disfigurmentation, depression, anxiety and significantly impact the quality of life of patients. Systemic and continuous exposure of antibiotics put patients at risk of developing systemic toxicity, bacterial resistance and gut dysbiosis. Microneedles offer an innovative approach of providing targeted topical delivery of minocycline while insuring efficient permeation through skin layers. Methods: minocycline microneedles were formulated using casting method and characterized for insertion ability, mechanical strength, drug content, antibacterial activities, deposition and dissolution behavior using ex vivo full-thickness rat skin. Results: Insertion tests confirmed effective skin penetration and mechanical integrity with only 9.5% height reduction. Drug content was 673.06 ± 5.34 µg/array. Dissolution occurred within 2 min in skin, indicating user-friendly wear time. Ex vivo Franz diffusion studies showed 26% of the drug deposited into the skin, significantly higher (p = 0.0068) than the 18.3% that permeated through it. Antibacterial testing revealed strong activity against S. aureus, S. epidermidis, and C. acnes, with MIC values < 0.146 µg/mL and MBC values ranging from 9.375–18.75 µg/mL. Conclusions: The result of this research demonstrate that minocycline microneedles effectively deliver minocycline into the skin highlighting their potential as a safer and more efficient alternative for acne therapy. Full article

Background/Objectives: Acanthamoeba keratitis (AK) is a rare but sight-threatening corneal infection, often associated with contact lens wear and resistant to conventional therapies. Preventive strategies capable of reducing Acanthamoeba adhesion to corneal epithelium may represent an important tool for infection control. This study aimed to evaluate the amebicidal and preventive activity of CORNEIAL MED eye drops against Acanthamoeba castellanii adhesion and early adhesion layer on human corneal epithelium (HCE). Methods: Reconstructed HCE models were exposed to A. castellanii under four experimental conditions: negative control (HCE only), positive control (HCE + A. castellanii), co-incubation with CORNEIAL MED and A. castellanii (Study 1), and treatment with CORNEIAL MED after initial A. castellanii adhesion (Study 2). Adherent amoebae were quantified using EDTA detachment and Neubauer chamber counting. The early adhesion layer was characterized by scanning electron microscopy (SEM). Statistical analysis considered p < 0.05 as significant. Results: In Study 1, simultaneous application of CORNEIAL MED with A. castellanii reduced amoeba adhesion by 33.0 ± 11% compared with controls (p = 0.0529). In Study 2, when the product was applied 3 h after amoeba inoculation, adhesion was significantly reduced by 51.9 ± 6.5% (p < 0.05). SEM confirmed a decrease in amoebic colonization and biofilm density in treated samples. Conclusions: CORNEIAL MED demonstrated a measurable inhibitory effect on A. castellanii adhesion to HCE, particularly when applied after initial pathogen contact. These findings suggest a potential preventive role of CORNEIAL MED in reducing AK risk, although further in vivo studies are warranted. Full article

The machining of highly abrasive sand–polymer composites pose significant challenges due to rapid tool wear directly associated with the tool’s stress–strain state. This study provides a detailed analysis of the stress and strain distribution in a T15K6 carbide turning insert under contact loads generated during the cutting of SPCs with varying quartz content. The approach combines analytically derived contact stress distributions on the rake and flank faces with numerical modeling using the finite element method (ANSYS). This hybrid methodology enables the accurate evaluation of stress localization in critical tool regions without performing full-scale cutting simulations. A parametric series of simulations was carried out by varying the mass fraction of quartz in the composite. The results demonstrate an almost linear increase in the maximum equivalent (von Mises) stress with rising quartz content, described by σ_eq = 9.61·C_quartz + 232.41. For the base composition with 60% quartz, the maximum equivalent stress is approximately 812 MPa, corresponding to about 50% of the flexural strength of the T15K6 alloy and ensuring a safety margin of roughly two. However, as the quartz fraction approaches 85%, the stress level becomes close to the critical limit, indicating an elevated risk of tool failure. The proposed analytical-numerical approach provides an effective framework for assessing the stress–strain state of carbide cutting tools and can support the optimization of machining conditions for highly abrasive composite materials. Full article