Work Surfaces Research Articles

Analysis of the radiation accidents prevalence in nuclear medicine in the Russian Federation

Radiation events (accidents) appearance is an integral part of the use of ionizing radiation sources in medicine in general and nuclear medicine in particular. To minimize the negative impact on patients, workers, and public due to such events, it is necessary to have reliable information about real prevalence of the radiation events (accidents). The current work presents the analysis of the radiation accidents with medical ionizing radiation sources registered in the “Data bank of radiation accidents and incidents” of the Rospotrebnadzor Information and Analytical Centre for Radiation Safety and the results of workers questionnaires conducted in 25 nuclear medicine departments (about 30% of all nuclear medicine departments in the Russian Federation). The results of the analysis showed that the most common registered radiation accidents in the “Data bank of radiation accidents and incidents” are identification of passengers with high external dose rate as well as identification of waste contaminated by medical radionuclides. The results of the questionnaire showed that the most common radiation accidents (events) in nuclear medicine are contamination of work clothes or work surfaces with radionuclides, or patient fluids containing radionuclides; conducting examination without proper referral; extravasation of radiopharmaceutical. Existing systems of identification and registration of radiation accidents do not allow to identify radiation events (accidents) specific to nuclear medicine. The further research aimed at developing a classification of radiation events (accidents) in medicine and methods for responding to such events are feasible.

Efficacy of Virucidal Treatments against Poliovirus Type 1 Deposited on Stainless-Steel Carriers.

Safe containment of infectious poliovirus (PV) within Poliovirus-Essential Facilities (PEFs) will require the implementation of reliable PV-inactivation approaches for decontaminating work surfaces. Such approaches should be demonstrated empirically to display adequate efficacy at the use temperature, and the contact times required should be characterized to ensure efficacy. Such efficacy is judged by the ability of the inactivation approach to completely inactivate any PV deposited, with the demonstrated total log10 reduction in PV titer being as high as empirically achievable. We screened several approaches for their efficacy in inactivating wild-type PV type 1 Chat strain experimentally deposited on stainless-steel carriers at room temperature. On the basis of the results, we selected two approaches (5000 ppm sodium hypochlorite in water and 95% v/v ethanol in water) for further characterization for repeatability of efficacy (log10 reduction in PV titer) and time kinetics of inactivation. We now report that both PV-inactivation approaches, which should be readily available to all PEF laboratories globally, fulfill the expectations expressed above, with 5000 ppm sodium hypochlorite reproducibly causing ≥5.38 log10 inactivation and 95% ethanol reproducibly causing ≥4.46 log10 inactivation of PV on stainless-steel surfaces within a 5 min contact time at room temperature.

Monitoring foodborne pathogens of food served at an institutional cafeteria

The provision of food by cafeterias is an opportunity to promote health through a balanced diet and safe food, offering the prospect of sustainably developing the well-being a community and the local economy. This study assessed the hygiene conditions of an institutional cafeteria. The presence of foodborne pathogens and indicators of general hygiene in 143 food and environmental samples were analyzed using the TEMPO and VIDAS food safety testing machines. All food samples tested negative for Salmonella sp., and Staphylococcus aureus counts were below the GCC Standardization Organization (GSO) limit. Escherichia coli was detected at level above the set limit in six food samples. Sixteen food samples showed aerobic bacterial counts above the set limit. Total coliforms and Enterobacteriaceae were each detected above the set limits in eight food samples. Yeasts and molds were detected above the set limit in 14 food samples. Coliform bacteria, S. aureus, and mold were detected on the hands and white coats of cafeteria workers and on work surfaces, machines, and cutting boards. The hygiene conditions of the cafeteria are not suitable for food preparation, and to improve hygienic conditions in cafeterias, regular inspection of food and food preparation facilities is strongly recommended.

Construction simulation and scheme optimisation of complex underground cavities

Underground cavities have complex spatial structures and geological settings, their arrangement is dense and crisscrossed. The construction system involves multiple work surfaces, levels, and processes. The close integration of construction simulation with actual production conditions is crucial for enhancing the guidance that simulation results provide for practical engineering. Therefore, from the perspective of optimizing construction organization and management, this article comprehensively considers various factors in the construction process, innovatively introduces the principle of production line balance and the concept of rule cycle, and combines technology and management, an underground cavities construction simulation system (UCCSS) is developed. In UCCSS, a hierarchical model is built and calculation are performed on models with different construction methods by modifying the parameters as per the actual engineering characteristics. The simulation results are comprehensively analysed to determine the optimal construction programme. An application case is proposed based on the construction organisation design of the long and parallel diversion tunnels at the CB Hydropower Station. The results show that the system has good practicality and credibility and can provide guidance for the construction organisation design of underground cavities with various features.

Dynamics of microbiome and resistome in a poultry burger processing line

Traditionally, surveillance programs for food products and food processing environments have focused on targeted pathogens and resistance genes. Recent advances in high throughput sequencing allow for more comprehensive and untargeted monitoring. This study assessed the microbiome and resistome in a poultry burger processing line using culturing techniques and whole metagenomic sequencing (WMS). Samples included meat, burgers, and expired burgers, and different work surfaces.Microbiome analysis revealed spoilage microorganisms as the main microbiota, with substantial shifts observed during the shelf-life period. Core microbiota of meat and burgers included Pseudomonas spp., Psychrobacter spp., Shewanella spp. and Brochothrix spp., while expired burgers were dominated by Latilactobacillus spp. and Leuconostoc spp. Cleaning and disinfection (C&D) procedures altered the microbial composition of work surfaces, which still harbored Hafnia spp. and Acinetobacter spp. after C&D. Resistome analysis showed a low overall abundance of resistance genes, suggesting that effective interventions during processing may mitigate their transmission. However, biocide resistance genes were frequently found, indicating potential biofilm formation or inefficient C&D protocols.This study demonstrates the utility of combining culturing techniques and WMS for comprehensive of the microbiome and resistome characterization in food processing lines.

Evaluation of clinical efficacy of scaling and root planing with copper nanoparticles gel and/or chlorhexidine gel in patients with periodontitis: A randomized control trial

Antibiotic resistance of bacteria to medications can be resolved using nanotechnology. Resistance to antibiotic mechanisms, such as regulation of permeability, multi-drug efflux pumps, antibiotic disintegration, and target area attraction, are dealt with by nanoparticles. These NPs are composed of Ag and Cu as heavy metals. Being both an essential nutrient as well as an especially hazardous matter, copper represents the two poles of the survival range for microorganisms. Because copper fittings and work surfaces are capable of eliminating methicillin-resistant S. aureus (MRSA) to prevent cross-contamination,they act as an additional obstacle. Additional research is needed, as the mode of action of nanoparticles is not fully understood. Existing information concerning NPs encourages further research to explore their use in the control of dental infections.

Wearing a Surgical Vest With a Sterile Surgical Helmet System Decreases Contamination of the Surgical Field

BackgroundSterile surgical helmet systems are frequently utilized in total knee arthroplasty procedures to protect the surgeon while maintaining a comfortable working environment. However, common helmet systems pressurize the space between the surgical gown and the surgeon’s skin. In gowns with a back seam, this may allow contaminated skin particles to escape into the surgical field. By measuring bacterial colony-forming units (CFUs), this study sought to determine if occlusion of the open back seam reduced the risk of potential contamination. MethodsFirst, qualitative analysis depicting airflow variations between gown configurations was performed using the Schlieren Spherical Mirror imaging system. Each gown configuration consisted of a sterile surgical helmet and one of 3 gown configurations: a standard gown with rear-tied closure, a standard gown with a surgical vest, and a zippered Toga-style gown. Next, a surgeon then performed simulated surgical activities for 60 minutes within a 1.4 m3 isolation chamber with work surfaces and controllable filtered air exchanges. During each procedure, contaminated particles were collected on sets of agar settle plates positioned directly behind the surgeon. Upon completion, the agar plates were incubated in a biolab, and the number of bacterial and fungal CFUs was counted. The experimental procedure was repeated 12 times for each gown configuration, with sterilization of the chamber between runs. Contamination rates were expressed as CFUs/m2/h. ResultsThe mean contamination rate measured with the standard gown was 331.7 ± 52.0 CFU/m2/h. After the addition of a surgical vest, this rate decreased by 45% to 182.2 ± 30.8 CFU/m2/h (P = .02). Similarly, with the Toga-style gown, contamination rates dropped by 49% to 170.5 ± 41.9 CFU/m2/h (P = .01). ConclusionsWhen used in conjunction with surgical helmet systems, conventional surgical gowns do not prevent potential contamination of the surgical field. We recommend that staff within the surgical field cover the back seam of standard gowns with a vest or don a zippered Toga-style gown.

Co-designing learning spaces with learners: Lessons from a Welsh primary school classroom

This research presents a case study of one class’s reflections on how they redesigned their classroom to suit the diverse needs of the teacher and learners, and how learners continue to adapt their learning space to better suit their individual needs. The findings of this paper illuminate how learners value agency and choice in their classrooms, something which can be achieved by offering them various work surfaces and spaces to complete learning activities. Learners suggested that flexible learning environments enabled them to choose where and how to complete their work, but also enabled them to position themselves in social environments that suit their learning needs. This work provides further context and insight into the implementation of the new Curriculum for Wales from September 2022 onwards, as well as the wider education system-level reforms currently taking place in Wales.

Improving Working Conditions in Retail During the COVID-19 Pandemic

The COVID-19 pandemic has significantly changed the patterns of employees’ behaviour, especially in the retail sector, which requires continuous contact with consumers. The anti-pandemic measures based on physical distance, wearing medical and protective equipment, application of barriers, frequent disinfection of work surfaces and space, use of strict protocols, and safety standards significantly complicate working conditions. This paper aims to analyse and define incentives for upgrading work and working conditions in retail during the COVID-19 pandemic. The scientific importance of the paper is reflected in the fact that analytically and systematically, it defines incentives that will support the behaviour of employees during crises affecting the retail sector. Unlike existing research in trade and retail, which indicated the importance of individual incentives for improving working conditions in periods of crisis, the contribution of this paper is in the comprehensive analysis, systematization, and definition of the importance of all incentives for improving the working conditions of employees in the retail sector. In this context, empirical research was conducted on a sample of 255 employees and it tested the importance of incentives to improve working conditions such as: maintaining a safe and healthy working environment, how to treat infected workers and workers in contact, the existence of detailed instructions for employees and consumers, organizing transportation for workers, financial incentives for employees, reduction of the scope of business activities, shortening of working hours of facilities, security protocols and digitalization of work processes. The survey was conducted among employees in SMEs and large retail chains. The set hypotheses were tested using the Path Analysis or Structural Modeling (SEM) method. The correlation between the retailer size and the differences in the incentives’ impact was assessed by employing Multiple Regression Analysis. The research results showed significant deviations in the mentioned incentives depending on the size of the retailer. Based on the obtained results, a set of measures was proposed that social policymakers and retail facility management should implement to improve working conditions in retail and establish a social safety net that will support employees in times of crisis. Guidelines for future research are provided in the paper. Keywords: working conditions, work incentives, position of workers, retailing, COVID-19 pandemic.

ИЗУЧЕНИЕ ЭФФЕКТИВНОСТИ ДЕЗИНФИЦИРУЮЩИХ СРЕДСТВ ПРИ АСКОСФЕРОЗЕ ПЧЕЛ

Ascospherosis of bees is an infectious disease that leads to the weakening and death of bee colonies and causes serious economic damage to the beekeeping industry. The purpose of this work was to study the effectiveness of modern environmentally friendly disinfectants for ascospherosis of bees in laboratory and apiary conditions. The studies were carried out in accordance with wellknown instructions, methodological requirements and methods. Based on literature data, a number of preparations were selected that have fungicidal and sporicidal effects, decompose on work surfaces to non-toxic compounds, penetrate into porous materials, are easily washed off with water and do not leave a persistent odor. At the same time, the final commercial beekeeping products must remain sanitary and biologically safe and suitable as food raw materials and products. Based on the results of laboratory studies and apiary tests of selected preparations, effective regimes were selected that ensure reliable disinfection of beekeeping objects in case of ascospherosis of bees.

INCREASING THE EFFICIENCY OF FUEL-FIRED PLANTS WITH DUSTY WASTE GASES

The results of a set of thermal calculations of the air-heating heat exchanger of the dusty waste gases of the thermal disposal of household waste are given. The initial data for the calculations were taken in the practical range when incinerating 1t/h of household waste from the experience of using the specified installations. The heat-recovery unit is designed to heat air for combustion by recovering the heat of the exhaust gases leaving after the turbine of this installation. Its design solution is characterized by the possibility of cleaning work surfaces from deposits of technological dust. The thermal indicators (temperatures of coolants and heat productivity) of the proposed heat-recovery unit under the conditions of its use for waste incineration plants were investigated. Calculations were performed in different modes of operation of the heat-recovery unit during the year, namely: at inlet temperatures of air and exhaust gases in the range from -20 to +20 ºС and from 200 to 300 ºС, respectively, the coefficient of excess air in waste gases from 1.5 to 2, 5 and different levels of dust on the heating surface. The influence of dustiness on the thermal parameters was characterized by the coefficient k, which determined the level of reduction in the thermal efficiency of the heat exchanger as a result of dust deposits on the specified surface and varied in the range from 1 to 0.5. Under the considered conditions was established, that use of the proposed air heater it provides heat output of 72 ÷ 263 kW, cooling of flue gases to a temperature of 107 ÷ 245 °С and heating of air to 96 ÷ 220 °С. At such levels of flue gas cooling, the efficiency of the thermal disposal of household waste increases by 2 ÷ 5%. In the case of a decrease in the heat-recovery capacity of the heat-recovery unit to technologically unacceptable levels, it is necessary to carry out its forced cleaning with compressed air, as provided for in the technical solution of such an air heater.

Monitoring contamination of hazardous drug compounding surfaces at hospital pharmacy departments. A consensus Statement. Practice guidelines of the Spanish Society of Hospital Pharmacists (SEFH)

ObjectiveTo establish a series of recommendations based on available evidence for monitoring surface contamination in the areas devoted to compounding hazardous drugs in pharmacy departments. MethodBased on a literature search in the Medline and Embase databases (search period: January 2009 to July 2019), as well as on a review of standards and recommendations issued by different healthcare organines a committee of experts from the Spanish Society of Hospital Pharmacists defined a series of safe practices for handling hazardous drugs and monitoring compounding work surfaces. Recommendation decisions were adopted by consensus among the members of the expert group, considering the recommendations reviewed, the monitoring situation in Spanish hospital departments, and the associated costs. ResultsTen recommendations were formulated, structured into eight sections. They include aspects related to the drugs to be monitored; the areas to be monitored; when samples should be taken; risk determination and preparation of a sampling protocol; analytical techniques; contamination thresholds; and design of an action plan based on the sampling and decontamination results obtained. ConclusionsSurface monitoring allows hazardous drugs detection and evaluation of the effectiveness of current protocols for the safe handling of such drugs in hospital pharmacy departments. The evaluation should include an analysis of the efficacy of engineering controls, work practices and cleaning and decontamination processes.

Numerical simulation of dust control technology for longwall working face with convective air curtain.

A convection-type air curtain dust control system and method were proposed to effectively control the high dust concentrations generated during the operation of coal miners and hydraulic supports and to reduce the dust concentration in the entire working space of longwall work surfaces, and the effectiveness of air curtain dust control during single process operation was investigated through numerical simulation. The results showed that when the miner was working alone, there was a significant difference in the concentration distribution inside and outside the dust-proof air curtain, with significantly lower dust concentrations in the area where the miner drivers were operating compared to both sides, with an average dust mass concentration of around 420 mg/m3. Dust concentrations increased to about 700 mg/m3, but large amounts of dust were prevented from diffusing downwind. This indicates that the dust reduction effect is more pronounced after the equipment is opened, which can improve the working environment and reduce the probability of dust combustion and explosion accidents.

Prevention of contamination after endotracheal intubation using a dedicated sleeve.

Contamination of work surfaces by used laryngoscopes after endotracheal intubation is a serious infection control concern but no strategies are available to address it. We assessed if contamination of the surfaces after endotracheal intubation would be reduced when providers used a dedicated, self-erected, disposable plastic sleeve (BladePouch) to store the used laryngoscope as compared to using single gloves or double gloves and sheathing the laryngoscope with the outer gloves. Twenty participants were recruited including attending physicians, trainees and allied health care professionals. They performed endotracheal intubation on a mannequin with oral cavity coated with a dye and stored the used laryngoscope blade using single gloves, double gloves or BladePouch. Each participant used both direct and video laryngoscopes. Following intubation, dye contamination of gloves, gown and work surface was evaluated. There was no difference in the contamination of gloves or gowns between the single gloves, double gloves or BladePouch groups. However, work surface contamination was significantly reduced when using BladePouch compared to single or double gloves (13% vs. 100% vs. 80% respectively, P<0.001). The odds of work surface contamination were significantly lower with BladePouch vs. single or double gloves, even when adjusted for intubation device, role and experience of participants with an adjusted odds ratio of 0.0054 (95% confidence interval: 0.0009-0.0314), P<0.001. In conjunction with standard precautions, the use of a dedicated plastic sleeve to store contaminated laryngoscope blade after endotracheal intubation may reduce the work surface contamination, independent of intubation device, role and experience of providers.

Strategies on Uniformity Lighting in Office Space under Energy-Saving Environment

In this study, our focus was on exploring the changing illuminance of work surfaces in different ambient uniformity spaces in the office, with a specific emphasis on sustainability and energy-saving considerations. To investigate this, we conducted a comprehensive study in a laboratory setting that replicated an office environment. The study involved the participation of 20 adults as subjects. The findings of our study revealed a strong correlation between the uniformity of ambient lighting illuminance within the indoor space and the illuminance levels observed specifically at the task plane. Notably, when the surrounding illuminance exhibited uniformity, we observed a significant reduction in the EH as adjusted by participants during VDT operation. Interestingly, the task illuminance adjusted by the subjects was lower than the usual standard. However, we did not find any significant correlation between the uniformity of indoor ambient lighting illuminance and the appropriate VDT screen luminance. In situations where energy-saving measures are required, it is crucial to maintain an even luminance in the surrounding space to ensure that the minimum lighting level in the office is upheld. Future discussions should delve into task-ambient lighting models, exploring beyond task illuminance standards alone.

An approach to quantify ortho-phthalaldehyde contamination on work surfaces.

Ortho-phthalaldehyde (OPA) is used as a high-level disinfectant for reusable medical devices in healthcare settings. The ACGIH recently adopted a Threshold Limit Value-Surface Limit (TLV-SL; 25 µg/100 cm2) for OPA surface contamination to prevent induction of dermal and respiratory sensitization following dermal exposure. However, there is no current validated method to measure OPA surface contamination. This study aimed to develop a standardized approach for sample collection and quantitative determination of OPA from work surfaces for use in risk assessment practices. The reported method utilises readily available commercial wipes to collect surface samples coupled with direct detection of OPA via liquid chromatography time of flight mass spectrometry (LC-ToF-MS). This approach avoided complex derivatization steps commonly required for the analysis of aldehydes. Method evaluation was conducted in accordance with the Occupational Safety and Health Administration (OSHA) surface sampling guidelines. Overall recoveries of 25 µg/100 cm2 of OPA from stainless steel and glass surfaces were 70% and 72%, respectively. The reported LOD for this method was 1.1 µg/sample and the LOQ was 3.7 µg/sample. OPA remained stable on the sampling medium for up to 10 days, when stored at 4 °C. The method was demonstrated in a workplace surface assessment at a local hospital sterilising unit, successfully detecting OPA on work surfaces. This method is intended to supplement airborne exposure assessment and provide a quantitative assessment tool for potential dermal exposure. When used in conjunction with a thorough occupational hygiene program that includes hazard communication, engineering controls, and personal protective equipment, skin exposure and consequent sensitization risks in the workplace can be minimized.

ВОЗМОЖНЫЕ МЕРЫ ПОВЫШЕНИЯ СРОКА СЛУЖБЫ ОСНОВНЫХ ЭЛЕМЕНТОВ ТОПЛИВОВПРЫСКИВАЮЩЕГО НАСОСА ДИЗЕЛЯ

During the operation of a high-pressure fuel injection pump, the friction surfaces of the main elements are subjected to various mechanical, thermophysical and hydroabrasive effects, which increases the wear rate of precision elements and reduces the cyclic fuel supply through the cylinders. The purpose of the research is to increase the resource of the main elements of in-line high-pressure fuel pumps by modernizing the power supply system. The main factor affecting the performance of precision elements is the presence of carbovalt in hydrocarbon fuel, that is, mechanical impurities in the form of an abrasive that circulate throughout the entire circuit of the power supply system, can pass through the filter element and get into the junction of precision elements during the injection cycle, where they are pinched and abraded work surfaces. In addition to mechanical impurities, hydrocarbon fuels may contain surfactants such as sulfur, phosphorus, etc. Under certain conditions, this also accelerates the wear rate of friction pairs, especially at temperatures above 50°C. With an increase in temperature, the lubricity of hydrocarbon fuels decreases, since sulfur compounds are activated, which destroy the structured surface at the boundary of friction pairs. To reduce this effect, it is proposed to limit the increase in temperature in the diesel power system by installing a radiator with a fan. With temperature limitation in the diesel fuel system, the wear intensity will be lower, the viscosity will be consistently higher by 2 times or more, which will reduce fuel leakage in mating surfaces. The above analytical expressions indicate that the size of the fuel leakage depends on the Reynolds number. With an increase in viscosity, the Reynolds number decreases several times, while the consumption coefficient and fuel leakage through the gaps of the friction pairs are significantly reduced. The proposed measure makes it possible to preserve the lubricity of the fuel, reducing wear and increasing the service life of the main elements of the fuel injection pump.

MICROBIOLOGICAL PURITY IN FOOD CHAIN

In addition to microbiological criteria for food (food safety criteria and hygiene criteria in the production process), microbiological purity criteria are a very important link in the microbiology of the food chain. Swab samples of equipment, devices, accessories, work surfaces, work clothes and hands of workers engaged in production, processing and traffic in facilities and vehicles that come into contact with food, and where there is a risk of the appearance and spread of an infectious disease, were used for testing. The examined samples originated from facilities for the production, processing and distribution of food, restaurants and other catering facilities where food is served, educational and social protection facilities (accommodation facilities) and vehicles that come into contact with food. The study was carried out during year 2020 and included 2,958 samples. Laboratory analysis of swab samples was performed using BAS EN ISO 4833-1:2014, BAS EN ISO 21528-2:2018, BAS EN ISO 11290-1:2018 and BAS EN ISO 6579-1:2018 methods. The aim of the study is to assess the microbiological purity in the food chain. Of the total number of analyzed swab samples, 94.22% were satisfactory, and 5.78% were unsatisfactory. Observed in relation to the total number of analyzed samples, 77.19% of the samples were unsatisfactory due to the increased number of aerobic microorganisms at 30°C, and 22.81% due to the increased number of Enterobacteriaceae. Pathogens Salmonella spp. and Listeria monocytogenes were not isolated in any swab sample. The obtained results indicate that the general level of hygiene in the production and distribution of food is at a high level, especially due to the absence of pathogens Salmonella spp. and Listeria monocytogenes, but that there is still a risk of contamination by Enterobacteriaceae, which are indicators of the hygiene of the production process.

Sports medicine methodologies applied in occupational medicine: analyzing the workstations of video terminal operators

BACKGROUND: Three-dimensional movement reconstruction systems, based on the use of infrared cameras capable of recognizing and capturing 3-D movement, are the standard in the biomechanical study of sporting actions. In this study, the knowledge and expertise inherent in sports medicine and engineering applied to sport were used for occupational risk assessment. In Italy, in 2020, muscularticular problems accounted for 69% of the problems reported to INAIL: these pathologies are correlated with bad posture. Using a methodology peculiar to sports medicine applied in the study of postural adjustment and gait analysis, therefore, the different working postures assumed at the video terminal typically employed by the staff of the leading international “E-commerce company” were subjected to analysis.METHODS: Four subjects (2 males and 2 females; age: 33.0± 12.9 years; stature 175.6± 0.07 cm; body weight 70.8± 8.87 kg) were evaluated in the laboratory of the Institute of Sports Medicine and Science of CONI by a three-dimensional optoelectronic system (SMART-DX 7000, BTS Bioengineering, Milan, Italy).RESULTS: The video terminal stations were characterized by three work surfaces of different heights: 73 cm for “sitting” positions, 100cm and 110cm for “standing” positions. The postures for the “sitting” position: 1) standard: correct posture as per D.Lgs.81/08; 2) leaning: with head bent forward towards the monitor; 3) slouching: “tired at the end of the day” and for the “standing” positions: 4) standard: correct posture; 5) leaning: with head bent forward towards the monitor. The angles (at knee, elbows, ankles, back created between C7-sacro-knee, head, visual, head-shoulder) and distances (forehead-monitor; acromion-monitor) were measured.CONCLUSIONS: Analysis of the data collected compared the different postures with the standard sitting position, the normative term of reference. The best “standing” posture is the one that also includes a rest under one of the feet, which brings the angles studied closer to those of the standard position. The standing position alone, however, exposes the back to “overload” and, therefore, the use of a bar stool of between about 72 to 85 cm high is suggested. This paper demonstrates how the methodology of movement analysis typical of sports medicine integrates with the ergonomic assessment needs of occupational medicine, needs that are and will become increasingly important in the management of workers who are called upon to extend their careers well beyond the age of 60.

Enhanced internal condensation of R1233zd(E) on micro- and nanostructured copper and aluminum surfaces

In-tube condensation of refrigerants is an important process which affects thermal efficiency in many applications, ranging from refrigeration and air conditioning to electronics thermal management. In-tube heat transfer and pressure drop are important to heat exchanger sizing and design. In this work, micro- and nanostructured surfaces are applied to the internal wetted areas of copper and aluminum mini-channels to enhance the condensation heat transfer coefficient of hydrofluorocarbon R1233zd(E) refrigerant. To achieve scalable nanomanufacturing, surfaces were uniformly structured by relying on hydrochloric acid etching of aluminum and chemical oxidation of copper. The etched aluminum surfaces exhibited a 150% increase in heat transfer coefficient compared to smooth aluminum channels at specific qualities, with a 66% heat transfer coefficient improvement for complete phase change from saturated vapor to saturated liquid. Copper oxide structures showed no discernable difference in thermal-hydraulic performance when compared to smooth copper channels. Critical dimensionless parameters governing the heat transfer enhancement were identified by varying the tube internal diameter (2.3 mm to 4.7 mm), refrigerant mass flux (50 to 300 kg/(m2·s)), and refrigerant quality (0 to 1). The dimensionless parameters include the Bond number normalized to the condensate film thickness, and the Weber number modified by the vapor friction factor. The relatively small increase in pressure drop (< 10%) associated with these surface enhancements further supports the promise of this method. The scalable and cost-effective techniques used to create these aluminum microstructures may reduce manufacturing cost when compared with current enhancement approaches such as extrusion, drawing, and welding.