Effects of UV irradiation time on the molecular structure of typical engineering plastics and tribological properties under heavy load

Exposing engineering plastics to UV irradiation can easily destroy the original molecular structure of the materials and consequently affect their tribological properties. This study investigated the effects of UV irradiation on the molecular structure of typical engineering plastics, such as polytetrafluoroethylene (PTFE) and polyether ether ketone (PEEK), and on their tribological properties under heavy loads (20 MPa). The surface morphology results showed that the appearance of PEEK changed significantly under UV irradiation. However, the change in PTFE was negligible. Under micromorphology, the processing lines of the two materials gradually became lighter with increasing UV irradiation time. The resulting infrared spectra showed that the molecular chains of both materials were broken, and new functional groups were formed under UV irradiation. Tribology testing demonstrated that with prolonged UV irradiation, the average PTFE coefficient of friction remained relatively stable, whereas that of PEEK was approximately 0.55. As the UV irradiation time increased, the wear rate of PTFE increased significantly, whereas that of PEEK showed no significant change.

Improved Outcomes with Concurrent Instrumentation and Fusion of the Sacroiliac Joint in Patients with Long Lumbosacral Constructs

Study Design Retrospective Cohort Study Objective Spinal fusion, specifically constructs connected to pelvic bones, has been consistently reported as a predisposing factor to sacroiliac joint (SIJ) pain. The aim of this study is to compare SIJ outcomes in patients with constructs to the pelvis following instrumentation vs instrumentation plus fusion of the SIJ. Methods Data of study subjects was extracted from a prospectively maintained database as well as retrospectively collected from records at a tertiary academic medical center in the United States between 2018 and 2020. Results A cohort of 103 patients was divided into 2 groups: 65 in Group 1 [S2AI screw without fusion device] and 38 in Group 2 [S2AI screw with fusion device]. None of the patients in Group 2 developed postoperative SIJ pain compared to 44.6% in Group 1. Sacroiliac joint fusion occurred in all Group 2 but none of Group 1 patients. The postoperative Visual Analogue Scale (VAS) for lower extremity (LE) pain (.8 vs .5; P = .03) and postoperative Oswestry Disability Index (ODI) (18.7 vs 14.2; P < .01) were significantly higher in Group 1. The rate of distal junctional break, failure, and/or kyphosis (DJBFK) and time to DJBFK were not significantly different between the two groups, and the rate of DJBFK did not change in the presence of multiple covariates. Conclusion The SIJs carry the heavy load of long lumbosacral fusion constructs extending to the pelvis. Simultaneous SIJ instrumentation and fusion decreases the risk of disability, prevents the development of postoperative SIJ pain, and may also protect the S2AI screw from loosening and failure.

The Application of DOMS Mechanism and Prevention in Physical Education and Training

To analyze the causes of muscle soreness and injury during precompetition training in university sports meet and taking the DOMS mechanism as the main line to find a reasonable way to deal with the muscle pain and prevent the injury, 125 college students participating in stadium games training were randomly selected. The muscle pain and injury during the training were obtained through interviews, mathematical statistics, and literature review. The information of exercise load, pain and injury type, exercise ability, pain degree, and recovery time was comprehensively analyzed to study the mechanism of pain and injury formation. Muscle pain and injury occurred in precompetition training, especially in freshmen. After heavy load, muscle soreness occurred, causing DOMS and developing into muscle injury. Affected by the external climate environment, sudden muscle soreness and injury are a gradual transformation process with DOMS as the boundary, which is the comprehensive result of exercise load, water, energy, and material metabolism; control load intensity, water supplement, and energy and material supplement can effectively prevent the occurrence of DOMS, and timely recovery after DOMS symptoms can effectively avoid the occurrence of sports injury. According to the different intensity of exercise, it is of great significance to clarify the mechanism of DOMS and explore effective prevention methods for physical education and sports training.

Task-Induced Mental Fatigue and Motivation Influence Listening Effort as Measured by the Pupil Dilation in a Speech-in-Noise Task

Objectives: Listening effort and fatigue are common complaints among individuals with hearing impairment (HI); however, the underlying mechanisms, and relationships between listening effort and fatigue are not well understood. Recent quantitative research suggests that the peak pupil dilation (PPD), which is commonly measured concurrent to the performance of a speech-in-noise task as an index of listening effort, may be informative of daily-life fatigue, but it remains unknown whether the same is true for task-induce fatigue. As fatigue effects are known to manifest differently depending on motivation, the main aim of the present study was to experimentally investigate the interactive effects of task-induced fatigue and motivation on the PPD. Design: In a pre-/post- fatigue within-subject design, 18 participants with normal hearing (NH) engaged in a 98-trial-long speech-in-noise task (i.e., a load sequence, approximately 40 min. long), which either excluded or included additional memory demands (light vs. heavy load sequence). Before and after the load sequence, baseline pupil diameter (BPD) and PPD were measured during shorter probe blocks of speech-in-noise tasks. In these probe blocks, if participants correctly repeated more than 60% of the keywords, they could win vouchers of either 20 or 160 Danish krones worth (low incentive vs. high incentive). After each probe block, participants reported their invested effort, tendency for quitting, and perceived performance. Results: The BPD in anticipation of listening declined from pre- to post-load sequence, suggesting an overall decrease in arousal, but the decline did not scale with the magnitude of the load sequence, nor with the amount of monetary incentive. Overall, there was larger pre- to post-load sequence decline in PPD when the load sequence was heavy and when the monetary incentives were low. Post-hoc analyses showed that the decline in PPD was only significant in the heavy-load sequence-low reward condition. The speech-in-noise task performance, self-reported effort, and self-reported tendency to quit listening did not change with the experimental conditions. Conclusions This is the first study to investigate the influence of task-induced fatigue on BPD and PPD. Whereas BPD was not sensitive to the magnitude of previous load sequence and monetary incentives, the decline in PPD from pre- to post- load sequence was significant after the heavy load sequence when the offered monetary incentives were low. This result supports the understanding that fatigue and motivation interactively influence listening effort.

Exceeding the Recommended Energy Limits Due to Age and Gender in Occupational Aerobic Workloads

The purpose of this chapter is to analyze the physical aerobic work in terms of the metabolic expenditure and compare it with the recommended boundaries of energy found in literature, proposing an alternative to the potential work overload through a compensatory equation introduced in the standard time of the workstation. To support the study, information considering the estimated metabolic expenditure in workers was applied to a novel procedure to reduce the metabolic demand of the task according to age and gender. Results of the study indicated that women older than 30 years exceeded the energy limits from moderate to very heavy load activities, and men older than 40 years exceeded the energy limits in heavy and very heavy workloads. The proposal of compensatory equation statistically reduced the energy loads below the recommended limits of energy. The aerobic workload is a sensitive factor for age and gender groups and can be potential risks for developing cardiovascular diseases as well as some musculoskeletal disorders.

An Ergonomic Analysis on Working Postures of Construction Site Workers

Risk factors related to work activity and ergonomics can enhance the probability that some persons may develop a MSD (musculoskeletal disorder). Usually the MSD develops due to high task repetition, forceful exertion, and repetitive/sustained awkward postures. MSD is also found in some cases where workers are engaged with working in awkward postures, cold temperatures, contact stress, heavy load, static postures, and vibration, etc. Many studies explain the problems for MSD, but in this chapter an effort is taken to rank the maximum body movement and body parts as per the different types of work flow system such that ergonomics design can be planned. Physical disorders can be avoided by finding and ranking the difficult task and the affected body part due to that kind of work. The prioritization of task will help the organization to think of sustainable designs of working procedure or instruments or machines to provide maximum comfort to humankind. It may also help to frame policies for occupational safety and hazards in workplace.

Students’ Perceptions on Participating in Remote Learning Activities in the Time of Covid-19 Pandemic

The present study aimed to assess Sri Lankan school students’ perceptions on the experience of participating in remote learning activities (RLA) available to them during the time of COVID-19 pandemic. This study was conducted as a survey. Using the exponential non-discriminative snowball sampling technique, data were collected from 613 school students through a questionnaire administered as a Google Form. Data were analyzed as mean values, standard deviations, and percentages. Analysis of data revealed that majority of respondents (92%) were well aware of the various RLA. Majority of the respondents (62.6%) used mobile internet and 69.5% used prepaid services. The main challenges they faced were related to affordability, heavy load of educational content presented through RLA, and concerns on cyber security when engaging with RLA. To make opportunities for learning more accessible to learners, it is recommended that mobile data be made available to school students at low costs and all educational programs should be made available to them free of charge. In addition, devices such as tablets should be provided to all students in order to ensure equality of access to education. Further, studies on parents’ and teachers’ experiences with their children’s and students’ learning through RLA would complement the findings of this study.

Hubungan Pengetahuan dan Stigma pada Keluarga dengan Beban Keluarga Dalam Merawat Pasien Skizofrenia di Wilayah Kerja Puskesmas Nanggalo Padang

Families have a heavy burden in caring for ODS. Heavy load perceived by the family due to the level of family knowledge and family stigma. This study aims to determine the relationship knowledge and stigma on families with family burdens in caring schizophrenia patient in the working area of ​​Puskesmas Nanggalo Padang. Types of research this is correlation with the approach cross sectional. The population in this study is a family who cares for ODS in the working area of ​​Puskemas Nanggalo Padang and a sample of 87 people taken withPurposive Sampling. Data collection using a questionnaire Family Interview Scale / Stigma Items, questionnaire knowledge, and a questionnaire Zarit Burden Interview (ZBI). Research result It was found that more than half (59.8%) of the families experienced a heavy burden, more than half (57.5%) of families have a lower or higher level of knowledge half (52.9%) of families experienced high stigma. There is a relationship meaning between the stigma in the family and the family burden (p =0,000). There is no significant relationship between the level of family knowledge with family burden (p =0.110). It is expected that health workers, especially nurses soul in society to provide health education to the community regarding Schizophrenia. So that society no longer gives stigma to families who will make the family embarrassed in caring for ODS.

Parameter Calibration on Replacement Manipulator for UHV Valve-Side Bushing Based on Spinor Theory

In this paper, a structure design scheme of intelligent replacement device for the ultrahigh voltage (UHV) converter transformer valve-side bushing is put forward, and its size is determined according to the actual size of domestic converter station valve hall and UHV converter transformer valve-side bushing. Moreover, the weak links in its working state are analyzed by finite element method to ensure the safety and reliability of the structure. Based on the spinor theory, the forward kinematics and Jacobian matrix model of the manipulator are established, and the analytical solution of inverse kinematics is derived. In order to analyze the accuracy of the intelligent replacement manipulator for the UHV converter transformer valve-side bushing, considering that the end actuator of the robot arm is under heavy load, the absolute positioning accuracy and repeated positioning accuracy are analyzed. In addition, the corresponding error model is established, the least square method is proposed to identify the error model, and the influence of the error caused by the load on the repetition accuracy is analyzed. Finally, the whole process simulation in ROS provides data support for the calculation of repetitive precision and verifies the feasibility of the intelligent replacement device for the UHV converter valve-side bushing.

A family of novel compliant linear-motion mechanisms based on compliant rolling-contact element pivot

Compliant linear-motion mechanisms are of great use in precision machines, due to their excellent performances such as infinite resolution and low cost. The accuracy of the mechanisms is an important consideration for mechanical design in applications, especially in the case of large working load. Considering that COmpliant Rolling-contact Element (CORE) pivot is characterized with high bearing capacity, the paper adopts it as a building block to design a family of compliant linear-motion mechanisms for applications of heavy load. These mechanisms are achieved by replacing four rigid pivots in a parallel four-bar mechanism with CORE pivots, and the motion accuracy is improved by means of contacting surfaces design of four CORE pivots. Firstly, structures of CORE pivot are introduced and five extended arrangements for bearing heavy load are presented. Meanwhile, motion for the CORE pivot is analyzed and preconditions for achieving a pure roll are discussed. Then, configuration of the compliant linear-motion mechanisms constructed by CORE pivots is obtained, and kinematics of the mechanisms is analyzed and parametric design condition for rectilinear motion is modeled. Based on the condition, detailed topological structures of the mechanisms are designed. Finally, motion simulations and experiment tests are implemented to verify accuracy of the proposed mechanisms. The results demonstrate that the mechanisms proposed in this paper are capable of offering a high-precision linear motion and providing a promising application prospect in precision machines.