Search results

This study examines the construction of essential labour during the early months of the COVID-19 pandemic in the United States. Research questions include: (1) How have government policies shaped designations of essential versus non-essential labour? (2) What are the consequences of these designations for essential workers? To address these questions, the author employs a case study of custodial services employees at Prairie University, a large public university in a major Texas city (Prairietown). The author begins with an examination of federal, state, and municipal guidelines about COVID-19 safety and critical infrastructure in order to understand the policy landscape within which custodial employees at Prairie University were formally deemed essential. Drawing on theories of non-nurturant care work, the author shows how government guidelines for essential work released during the early period of the COVID-19 pandemic discursively invisibilized cleaning labourers. The author then demonstrates how this invisibilization contributed to Prairie University custodial services staff members’ exposure to COVID-19. The author concludes by considering the implications of the findings for future research on care work and the construction of essential labour.

Metal laser-powder-bed-fusion using laser-beam parts are particularly susceptible to contamination due to particles attached to the surface. This may compromise so-called technical cleanliness (e.g. in NASA RPTSTD-8070, ASTM G93, ISO 14952 or ISO 16232), which is important for many 3D-printed components, such as implants or liquid rocket engines. The purpose of the presented comparative study is to show how cleanliness is improved by design and different surface treatment methods.

Convex and concave test parts were designed, built and surface-treated by combinations of media blasting, electroless nickel plating and electrochemical polishing. After cleaning and analysing the technical cleanliness according to ASTM and ISO standards, effects on particle contamination, appearance, mass and dimensional accuracy are presented.

Contamination reduction factors are introduced for different particle sizes and surface treatment methods. Surface treatments were more effective for concave design features, however, the initial and resulting absolute particle contamination was higher. Results further indicate that there are trade-offs between cleanliness and other objectives in design. Design guidelines are introduced to solve conflicts in design when requirements for cleanliness exist.

This paper recommends designing parts and corresponding process chains for manufacturing simultaneously. Incorporating post-processing characteristics into the design phase is both feasible and essential. In the experimental study, electroless nickel plating in combination with prior glass bead blasting resulted in the lowest total remaining particle contamination. This process applied for cleanliness is a novelty, as well as a comparison between the different surface treatment methods.

The purpose of this study is to evaluate the effectiveness of nanocontainer solutions in removing deteriorated and aged polymers commonly used in coating and consolidating archaeological glass.

This study focused on characterizing glass surfaces coated with two commonly used polymeric materials in archaeological glass preservation. Furthermore, the study evaluates the elimination of these coatings from the surfaces by using innovative aqueous systems composed of micellar solutions (MS) and oil-in-water (O/W) Texapon-P microemulsions (TEX). Glass samples coated with selected polymers were subjected to thermal and photochemical aging to simulate natural degradation conditions. This study aimed to evaluate the effectiveness of nanocontainer aqueous systems compared to acetone (Ac), a conventional solvent commonly used for removal procedures. The characterization procedures involved transmission electron microscopy, USB digital microscopy, scanning electron microscopy, color alteration and gravimetric measurement.

The findings indicate that the effectiveness of novel techniques using aqueous nanocontainer systems is quite promising when considering a “green approach” to preserving cultural heritage. Microscopic examination demonstrated the efficacy of MS in effectively removing acrylic and vinyl polymers from the glass surface. Furthermore, TEX proved effective in removing polyvinyl acetate (PVA) over Paraloid B72 (B-72). In addition, the measurement of color alteration values revealed a decrease after using MS compared to the standard sample before applying the polymers, with values of ΔE = 1.48 and 1.82 for B-72 polymer and PVA, respectively.

This research provides nanocontainer solutions for removing aged polymers from the glass surface. This makes the current study a promising step for treating archaeological glass.

The success of sharing economy (SE) platforms has made it attractive for many firms to adopt this business model. However, the inherent weaknesses of these platforms, such as their unstandardized service quality, the burden of maintenance on resource owners and the threat of multi-homing, have become increasingly apparent. Previous prescriptions for addressing these weaknesses, however, are limited because they do not account for factors such as compliance costs and information asymmetry, and tend to solve the problem on only one side of the platform at the expense of the others. By exploring the strategies deployed and actions undertaken across the development of Xbed, a successful accommodation-sharing platform in China, this study aims to explore an alternative solution that would overcome the aforementioned weaknesses without the corresponding compromises.

The authors conducted a case study consisting of secondary data and interviews with 15 informants who were representatives of Xbed's top management, organizational IT functions and its various business units.

The authors identified three inherent weaknesses that may be found in SE business models and how these weaknesses can be overcome without compromising other stakeholders through an auxiliary platform. The authors also discuss the advantages, characteristics, deployment and nature of auxiliary platforms.

This model contributes an in-depth view of establishing and nurturing auxiliary platforms to complement a primary SE platform. Owners and managers of SE platforms may use our model as the basis of guidelines for optimizing their platforms' development, thereby extending the benefits of SE to more stakeholders.

Providing student housing designed to support students living with a disability is a global challenge. This study assesses buildings' physical health condition systems and drivers of physical health condition effects on students living with disability (SWD) in purpose-built university housing in Ghana.

The study used quantitative design and methods based on the theory of supportive design premises. Using the partial least square structural equation model, a survey of 301 students living with a physical disability, mild visual disability and mild hearing disability was collected in 225 student housings.

The study found that insect control and cleaning services are a priority in off-campus building design and management and directly positively affected the sense of control and physical health of SWD. The nature of lightning systems, noise and thermal comfort directly negatively affected SWD disability learning and discomfort.

Reviewing and enforcing student housing design drawings at the preliminary development stage by university management is critical. More broadly, physical health systems that control cleaning, noise and thermal comfort are essential for SWD health in student housing.

Studies on all-inclusive building designs have consistently focused on lecture theaters and libraries with limited attention on the physical health condition systems in student housing that support the quality healthcare of university campuses. Research on physical health condition systems in student housing is significant for all-inclusiveness and student housing management.

This comparative book review is concerned with two recent studies of essential workers in Germany: Jana Costas’ Dramas of Dignity and Peter Birke’s Grenzen aus Glas [literally ‘borders made from glass’]. While Costas is interested in studying how individual cleaners preserve their sense of dignity despite their widely believed stigmatizing work roles, Birke is interested in the power resources migrant workers can potentially mobilize for improving their working conditions despite the multi-dimensional (inter-sectional) precarity they confront in their life situation. In the context of German industrial and organizational sociology, both studies represent comparatively rare exemplars of detailed qualitative and ethnographic work that illuminate the labour process from taking a workers’ perspective. Using different approaches to fieldwork, both studies reveal the precarious nature of being an essential worker in areas such as meat packing, warehouse work, and cleaning. This general observation gives rise to some concluding speculations about the emancipatory potential of ethnographic research, in labour studies and beyond.

This study aims to design and implement a multimaterial system for printing multifunctional specimens suitable for various sectors, with a particular focus on biomedical applications such as addressing mandibular bone loss.

To enhance both the mechanical and biological properties of scaffolds, an automatic multimaterial setup using vat photopolymerization was developed. This setup features a linear system with two resin vats and one ultrasonic cleaning tank, facilitating the integration of diverse materials and structures to optimize scaffold composition. Such versatility allows for the simultaneous achievement of various characteristics in scaffold design.

The printed multimaterial scaffolds, featuring 20 Wt.% hydroxylapatite (HA) on the interior and poly-L-lactic acid (PLLA) with 1 Wt.% graphene oxide (GO) on the exterior, exhibited favorable mechanical and biological properties at the optimum postcuring and heat-treatment time. Using an edited triply periodic minimal surface (TPMS) lattice structure further enhanced these properties. Various multimaterial specimens were successfully printed and evaluated, showcasing the capability of the setup to ensure functionality, cleanliness and adequate interface bonding. Additionally, a novel Gyroid TPMS scaffold with a nominal porosity of 50% was developed and experimentally validated.

This study demonstrates the successful fabrication of multimaterial components with minimal contaminations and suitable mechanical and biological properties. By combining PLLA-HA and PLLA-GO, this innovative technique holds significant promise for enhancing the effectiveness of regenerative procedures, particularly in the realm of dentistry.

The purpose of this study was to improve the overall equipment effectiveness (OEE) of the production process of the shredder operation of ABC company, an industrial waste management company which supplies pre-processed industrial waste as alternative fuel to a cement plant.

This case study investigated all possible availability and performance losses that caused the shredder system’s OEE and various problem-solving techniques, such as root cause analysis and Pareto analysis, were used to find the root cause of the reduced OEE.

After analysing this case study, three significant loss factors were identified from all the availability and performance losses, which caused the shredder system’s OEE losses. Practical solutions were found for the effect of those loss factors to improve the machine’s OEE and productivity.

This case study has been concentrated on only analysing of losses and improvement of OEE in the production process and not about cost analysis between loss and improvements.

This paper shows how to improve the OEE of a production process through various problem-solving techniques by identifying its losses and how to achieve the best solutions for those losses in a practical manner.

The main purpose of this paper was to evaluate the validation process of food safety control measures.

The validation of control measures has been analyzed at 50 food companies in Serbia. The sample included companies that produce food of both plant and animal origin and have certified food safety management systems. A total of 156 control measures that combat physical hazards (41.6%), followed by microbial hazards (34.0%) and chemical hazards (24.4%), have been analyzed. To enable quantification of the validation protocols, each control measure was assigned a score.

The validation scores showed that the highest level of validation was observed in large companies, as opposed to small and medium-sized companies (p < 0.05). The type of food safety hazards and the food sector did not reveal any statistical differences in-between the scores. The main approach to validating control measures was referring to the technical documentation of equipment used (52.6%), followed by scientific and legal requirements (30.7%). Less than 20% of the analyzed control measures were validated with operational data collected on-site. No mathematical modeling was observed for the sampled food companies. Future steps should include the development of validation guides for different types of control measures and training modules.

This study can serve as an improvement guide for food safety consultants, food safety auditors, certification bodies, inspection services, food technologists and food managers.

This study is one of the first to provide an insight into how food companies validate their control measures to combat microbial, chemical and physical food safety hazards.

This study aimed to review various existing methods for improving the quality of recycled concrete aggregates (RCAs) as a possible substitution for natural aggregates (NAs) in concrete. It is vital as the old paste attached to the RCA weakens its structure. It is due to the porous structure of the RCA with cracks, weakening the interfacial transition zone (ITZ) between the RCA and binding material, negatively impacting the concrete's properties. To this end, various methods for reinforcement of the RCA, cleaning the RCA's old paste and enhancing the quality of the RCA-based concrete without RCA modification are studied in terms of environmental effects, cost and technical matters. Furthermore, this research sought to identify gaps in knowledge and future research directions.

The review of the relevant journal papers revealed that various methods exist for improving the properties of RCAs and RCA-based concrete. A decision matrix was developed and implemented for ranking these techniques based on environmental, economic and technical criteria.

The identified methods for reinforcement of the RCA include accelerated carbonation, bio deposition, soaking in polymer emulsions, soaking in waterproofing admixture, soaking in sodium silicate, soaking in nanoparticles and coating with geopolymer slurry. Moreover, cleaning the RCA's old paste is possible using acid, water, heating, thermal and mechanical treatment, thermo-mechanical and electro-dynamic treatment. Added to these treatment techniques, using RCA in saturated surface dry (SSD) mixing approaches and adding fibres or pozzolana enhance the quality of the RCA-based concrete without RCA modification. The study ranked these techniques based on environmental, economic and technical criteria. Ultimately, adding fibres, pozzolana and coating RCA with geopolymer slurry were introduced as the best techniques based on the nominated criteria.

The study supported the need for better knowledge regarding the existing treatment techniques for RCA improvement. The outcomes of this research offer an understanding of each RCA enrichment technique's importance in environmental, economic and technical criteria.

The practicality of the RCA treatment techniques is based on economic, environmental and technical specifications for rating the existing treatment techniques.