Biomechanics and Remodelling for Design and Optimisation in Oral Prosthesis and Therapeutical Procedure

The purpose of dental prostheses is to restore the oral function for edentulous patients. Introducing any dental prosthesis into mouth will alter biomechanical status of the oral environment, consequently inducing bone remodelling. Despite the advantageous benefits brought by dental prostheses, the attendant clinical complications and challenges, such as pain, discomfort, tooth root resorption, and residual ridge reduction, remain to be addressed. This thesis aims to explore several different dental prostheses by understanding the biomechanics associated with the potential tissue responses and adaptation, and thereby applying the new knowledge gained from these studies to dental prosthetic design and optimisation. Within its biomechanics focus, this thesis is presented in three major clinical areas, namely prosthodontics, orthodontics and dental implantology. In prosthodontics, the oral mucosa plays a critical role in distributing occlusal forces a denture to the underlying bony structure, and its response is found in a complex, dynamic and nonlinear manner. It is discovered that interstitial fluid pressure in mocosa is the most important indicator to the potential resorption induced by prosthetic denture insertion, and based on this finding, patient-specific analysis is performed to investigate the effects caused by various types of dentures and prediction of the bone remodelling activities. In orthodontic treatments, a dynamic algorithm is developed to analyse and predict potential bone remodelling around the target tooth during orthodontic treatment, thereby providing a numerical approach for treatment planning. In dental implantology, a graded surface morphology of an implant is designed to improve osseointegration over that of a smooth uniform surface in both the short and long term. The graded surface can be optimised to achieve the best possible balance between the bone-implant contact and the peak Tresca stress for the specific clinical application need

Effects of different structure parameters on skidding of high-speed roller bearing considering bearing whirling

Severe skidding of high-speed roller bearings (HSRBs) in a whirling squeeze film damper often leads to vibration and failure of rotor-bearing systems or even entire machines. In this manuscript, the skidding failure of HSRBs, especially considering bearing whirl, was studied. Analytical models were built by taking bearing whirl into account, and the skidding mechanism was investigated systematically in terms of various factors such as whirl orbit, radial load, lubricating oil viscosity, roller diameter, diametral clearance, roller length, and number of rollers. The results showed that whirl might lead to unstable movements, which can exacerbate skidding damage to the bearing, and the degree of skidding is directly correlated with the whirl radius. As radial load and diametral clearance increase, the degree of skidding and the influence of whirl motion on bearing skid decrease. In contrast, as the roller diameter, roller length, and number of rollers decrease, the degree of skidding and the influence of whirl motion on bearing skid decrease. Furthermore, the analysis results show that the viscosity of lubricating oil has both positive and negative effects on bearing skid. Therefore, for reducing bearing skid to improve HSRB service life and stability, the whirl radius, roller diameter, roller length, and number of rollers should be decreased, whereas the radial load and diametral clearance should be increased moderately

A Simplified Identification Method of Dynamic Stiffness for the Heavy-Load and Low-Speed Journal Bearings

Journal bearing is an essential part of the propulsion shafting system, whose performance directly affects the safety and performance of the shaft and even the entire ship. It is an important, but also a difficult task to obtain the accurate dynamic stiffness values. In order to determine the dynamic characteristics of the journal bearing with specific structural characteristics under specific working conditions, an inverted test platform with multiple sensors for the dynamic stiffness of the heavy-load, low-speed journal bearings (HLLSJBs) was developed, and a novel dynamic test system calibration method was proposed to obtain accurate baseline data, and then the effective characteristic frequency response was gotten based on a refined fast Fourier transform method (RFFT). The present study proposed a simplified identification method to analyze the constitutive relationships between the oil film dynamic parameters and the dynamic stiffness under different rotation and loading conditions in the journal bearing, and then the accurate values of the oil film dynamic stiffness of HLLSJBs were obtained. Furthermore, the values of the structural dynamic stiffness of HLLSJBs were also obtained using a hammer impact method. A comparison with the classic theoretical analysis results reveals that the method proposed is more accurate and effective

Effects of oil film properties on roller bearing with light loads under various slip factors

In this paper, ideal and general kinematics and models of roller bearing were built, and the oil film thickness for a roller bearing under a light load was analyzed with different slip factors. And then a new method to calculate the oil film thickness by considering a double slip ratio was developed, and the effects of different slip factors such as the slip ratio, inner ring speed, and radial load on the oil film thickness were investigated systematically. Under a zero slip ratio, the results showed that the film thickness increases with the inner ring speed. The radial load shows the reverse trend, and different slip factors affect the oil film properties differently. In the case with double slip ratio, the results showed that the film thickness slightly decreases as the roller slip ratio increases, whereas the cage slip ratio shows the reverse trend. The roller and cage slip ratios have different effects on the oil film thickness. The oil film distribution is affected by the combined action of the two slip ratios, the inner ring speed, and the radial load. The cage slip ratio can often be considered to be the main factor for calculating the oil film thickness

Enrollment-stage Backdoor Attacks on Speaker Recognition Systems via Adversarial Ultrasound

Automatic Speaker Recognition Systems (SRSs) have been widely used in voice applications for personal identification and access control. A typical SRS consists of three stages, i.e., training, enrollment, and recognition. Previous work has revealed that SRSs can be bypassed by backdoor attacks at the training stage or by adversarial example attacks at the recognition stage. In this paper, we propose TUNER, a new type of backdoor attack against the enrollment stage of SRS via adversarial ultrasound modulation, which is inaudible, synchronization-free, content-independent, and black-box. Our key idea is to first inject the backdoor into the SRS with modulated ultrasound when a legitimate user initiates the enrollment, and afterward, the polluted SRS will grant access to both the legitimate user and the adversary with high confidence. Our attack faces a major challenge of unpredictable user articulation at the enrollment stage. To overcome this challenge, we generate the ultrasonic backdoor by augmenting the optimization process with random speech content, vocalizing time, and volume of the user. Furthermore, to achieve real-world robustness, we improve the ultrasonic signal over traditional methods using sparse frequency points, pre-compensation, and single-sideband (SSB) modulation. We extensively evaluate TUNER on two common datasets and seven representative SRS models. Results show that our attack can successfully bypass speaker recognition systems while remaining robust to various speakers, speech content, e

Research on ride comfort and safety of vehicle under limited conditions based on dynamical tire model

During driving of a vehicle on road, the tires are undertaking load conversion of the vehicle under various driving conditions and various road conditions within contact patches. As for the contact condition between tire and road, it is often deemed as composed by spring and damping element. The contact with road is always simplified as point contact. Besides, static friction model is adopted, which has ignored physical property of friction and dynamic process of establishment of friction force. It is far from sufficient for current vehicle and road safety design. In this paper, ADAMS software is applied to establish a multi-body dynamics model of heavy vehicle, actual vehicle data was adopted to check virtual sample vehicle, and the Strikbeck dynamical friction property is introduced to tire model during rolling contact between tire and payment, interface of Simulink with ADAMS is applied to put forward a complete vehicle dynamic model truly reflecting the process of dynamic contact between tire and road, and furthermore the correctness and availability of dynamic tire model are verified through comparison with classic Pac2002 tire model. As for dynamic behaviors of heavy vehicle in special sections, finite element method (FEM) is applied to put forward a new 3D complicated road model construction method to construct roads of different classes and long-downhill paths of different S-curves. Simulated analysis of the influence of different speeds, different classes of random roads, different slopes and different adhesion road models on ride comfort of vehicle driving was implemented through utilization of event editor and drive control file, and speed limit standards under different conditions are put forward, so as to provide theoretical basis for road alignment design and reasonable driving speed. Finally, the influence and changing rules of different speeds, different classes of random roads and different slopes on driving safety are discussed from the perspectives of each radial force of tire, alignment torque, sideslip angle and roll angle

Habitual snoring, adiposity measures and risk of type 2 diabetes in 0.5 million Chinese adults:a 10-year cohort

OBJECTIVES: The present study aimed to examine whether habitual snoring was independently associated with risk of type 2 diabetes among Chinese adults, and to assess the role that adiposity measures play in the snoring-diabetes association, as well as to evaluate the joint influence of snoring and adiposity measures on diabetes. RESEARCH DESIGN AND METHODS: The China Kadoorie Biobank study recruited 512 715 adults aged 30-79 years from 10 regions in China during 2004 and 2008. Data from 482 413 participants without baseline diabetes were analyzed in the present study. Autoregressive cross-lagged panel analysis was used to assess the longitudinal relationship between adiposity measures and habitual snoring. Cox proportional hazards models were used to examine the association between habitual snoring and diabetes risk. RESULTS: Both higher body mass index and waist circumference were associated with higher risks of subsequent habitual snoring, whereas no reverse association was detected. A total of 16 479 type 2 diabetes cases were observed during a 10-year follow-up. Habitual snoring was independently associated with 12% (95% CI 6% to 18%) and 14% (95% CI 9% to 19%) higher risks of diabetes among men and women, respectively. Habitual snorers who had general obesity or central obesity were about twice as likely to develop diabetes as non-snorers at the lowest levels of adiposity measures. CONCLUSION: Habitual snoring was independently associated with a higher risk of type 2 diabetes among Chinese adults. It is important to maintain both a healthy weight and a normal waist circumference to prevent or alleviate habitual snoring and ultimately prevent diabetes among Chinese adults

Metabolomics-based discovery of XHP as a CYP3A4 inhibitor against pancreatic cancer

Background: Xihuang Wan (XHW), a purgative and detoxifying agent, is commonly utilized in modern medicine as a treatment and adjuvant therapy for various malignancies, including breast cancer, liver cancer, and lung cancer. A clinical study demonstrated the potential usefulness of the combination of XHW and gemcitabine as a therapy for pancreatic cancer (PC), indicating that XHW’s broad-spectrum antitumor herbal combination could be beneficial in the treatment of PC. However, the precise therapeutic efficacy of XHW in treating pancreatic cancer remains uncertain.Aim: This study assessed the biological activity of XHW by optimizing the therapeutic concentration of XHW (Xihuang pills, XHP). We performed cell culture and developed an animal test model to determine whether XHP can inhibit pancreatic cancer (PC). We also applied the well-known widely targeted metabolomics analysis and conducted specific experiments to assess the feasibility of our method in PC therapy.Materials and Methods: We used UPLC/Q-TOF-MS to test XHP values to set up therapeutic concentrations for the in vivo test model. SW1990 pancreatic cancer cells were cultured to check the effect the anti-cancer effects of XHP by general in vitro cell analyses including CCK-8, Hoechst 33258, and flow cytometry. To develop the animal model, a solid tumor was subcutaneously formed on a mouse model of PC and assessed by immunohistochemistry and TUNEL apoptosis assay. We also applied the widely targeted metabolomics method following Western blot and RT-PCR to evaluate multiple metabolites to check the therapeutic effect of XHP in our cancer test model.Results: Quantified analysis from UPLC/Q-TOF-MS showed the presence of the following components of XHP: 11-carbonyl-β-acetyl-boswellic acid (AKBA), 11-carbonyl-β-boswellic acid (KBA), 4-methylene-2,8,8-trimethyl-2-vinyl-bicyclo [5.2.0]nonane, and (1S-endo)-2-methyl-3-methylene-2-(4-methyl-3-3-pentenyl)-bicyclo [2.2.1heptane]. The results of the cell culture experiments demonstrated that XHP suppressed the growth of SW1990 PC cells by enhancing apoptosis. The results of the animal model tests also indicated the suppression effect of XHP on tumor growth. Furthermore, the result of the widely targeted metabolomics analysis showed that the steroid hormone biosynthesis metabolic pathway was a critical factor in the anti-PC effect of XHP in the animal model. Moreover, Western blot and RT-PCR analyses revealed XHP downregulated CYP3A4 expression as an applicable targeted therapeutic approach.Conclusion: The results of this study demonstrated the potential of XHP in therapeutic applications in PC. Moreover, the widely targeted metabolomics method revealed CYP3A4 is a potential therapeutic target of XHP in PC control. These findings provide a high level of confidence that XHP significantly acts as a CYP3A4 inhibitor in anti-cancer therapeutic applications

A Community-Based Addiction Rehabilitation Electronic System to Improve Treatment Outcomes in Drug Abusers: Protocol for a Randomized Controlled Trial

Introduction: Relapse is very common in drug abusers and contributes to a series of negative consequences. Effective addiction treatment exists but there are some problems in the implementation process. Mobile health (mHealth) offers a potential solution to improving recovery outcome for drug abusers in the community. The research team developed a community-based addiction rehabilitation electronic system (CAREs). The primary aim of this study is to explore whether the integrated rehabilitation based on program CAREs promotes drug abusers to keep abstinence. The secondary aim is to evaluate the impact of CAREs on interaction between drug users and service providers, and on addiction-related physical and social functions.Method and analysis: A randomized controlled trial (RCT) will be conducted. The study is a superiority trial with parallel group design. Seventy drug abusers who are newly ordered to undergo community rehabilitation will be recruited from the community in Shanghai. Participants will be 1:1 randomly assigned to receive integrated community rehabilitation by using CAREs or only receiving routine community rehabilitation for 6 months. Corresponding social workers will provide service and monitor their drug use behavior in accordance with the routine work-flow. Outcomes will be assessed at baseline and in the 6th month. The primary outcome is the performance on illicit drug urine test which will be carried out regularly twice per week during the study period. Secondary study outcomes include longest duration of sustained abstinence, days that participants interact with social workers, and the decrease rate of addiction-related issues severity index. Chi-square tests and ANOVAs will be used to compare characteristics of the members of the two groups. GEE will be used to compare the seven dimensions scores of the ASI between groups.Discussion: The study provides evidence for the feasibility and effectiveness of the “CAREs” system through comparing the results of the intervention group with the control group. This paper describes the design and methodology of the study.Ethics and dissemination: The Ethical Board of SMHC approved the study protocol. All participants will present for the informed consent process. After study completion, the results will be published.Trial Registration: ClinicalTrials.gov NCT03451344, https://clinicaltrials.gov/ct2/show/NCT0345134

Effect of pyrolysis condition on the adsorption mechanism of heavy metals on tobacco stem biochar in competitive mode

Abstract(#br)To clarify the adsorption mechanism of multi-ions on biochars in competitive environment is very important for the decontamination of co-existed heavy metals. Herein, tobacco stem was pyrolyzed in different temperatures with selected residences to obtain biochars with various surface chemistry. Then the adsorption of co-existed typical heavy-metal ions like lead, cadmium, and copper was studied, followed with systematic analysis of surface properties of the post-adsorption biochars. After carefully examining the adsorption performance and surface property alteration of the demineralized biochars, the adsorption mechanism of multi-ions in competitive environment was discovered. Lead showed the most competitive nature with co-existence of cadmium and copper, but the adsorption..