147 research outputs found
Factors influencing patientâs medical choice behavior on Internet Medical: The perspective of trust
Based on the source credibility model and trust transfer theory, this study examined the influence of physicianâs personal attributes and word-of-mouth on patientsâ medical choice in online healthcare communities, and explored trust transfer from online to offline channel as well as the moderating effect of disease risk on the influence of ability trust and honest trust. Using data from Good Doctor Online, the results revealed that ability trust, benevolence trust, honest trust, and transference trust based on word-of-mouth all had a positive impact on the patientsâ medical choice despite slight differences between channels in terms of specific proxies and degree of influence. Disease risk moderated the relationship between ability trust and honest trust and patientsâ medical choice. Trust transfer from online channel to offline channel had not been verified
Bacterial Anti-Adhesion of Coated and Uncoated Thin-Film-Composite (TFC) Polyamide (PA) Membranes
This study investigates the bacterial anti-adhesion performance of uncoated and coated reverse osmosis (RO) membranes. All the membranes were commercially available fully-aromatic thin-film-composite (TFC) polyamide (PA) membranes. Two of the TFC PA membranes (SW30 and BW30) were coated using polyvinyl alcohol (PVA) coating, while the other three membranes (LE, XLE and NF90) were uncoated. Among the characterised TFC PA membranes, the PVA coated were more hydrophilic and their surface energy was higher in comparison to uncoated. In addition, the PVA coated membranes had lower surface roughness. AFM interaction force measurement demonstrated higher repellence performance for the more polar surface. Bacteria attachment test showed differences between the coated and the uncoated membranes. Indeed, the increase in hydrophilicity and surface polarity showed decrease in the attachment of Pseudomonas aeruginosa cells. Moreover, the results demonstrated that the surface polarity showed better correlation with the attachment of the bacteria. In addition, the type of the surface roughness may somehow contribute to the bacteria repellence
Membrane module design and dynamic shear-induced techniques to enhance liquid separation by hollow fiber modules: a review
Membrane-based separation processes have found numerous applications in various industries over the past decades. However, higher energy consumption, lower productivity, and shorter membrane lifespan due to polarization and membrane fouling continue to present severe technical challenges to membrane-based separation. Improved membrane module design and novel hydrodynamics offer strategies to address these challenges. This review focuses on hollow fiber membrane modules which are well suited to membrane contactor separation processes. Attempts to improve membrane module design should begin with a better understanding of the mass transfer in the hollow fiber module; therefore, this review provides a summary of prior studies on the mass transfer models related to both the shell-side and tube-side fluid dynamics. Based on the mass transfer analysis, two types of technique to enhance hollow fiber membrane module performance are discussed: (1) passive enhancement techniques that involve the design and fabrication of effective modules with optimized flow geometry or (2) active enhancement techniques that uses external energy to induce a high shear regime to suppress the undesirable fouling and concentration polarization phenomena. This review covers the progress over the past five years on the most commonly proposed techniques such as bubbling, vibrations, and ultrasound. Both enhancement modes have their advantages and drawbacks. Generally, the passive enhancement techniques offer modest improvement of the system performance, while the active techniques, including bubbling, vibrating, and ultrasound, are capable of providing as high as 3â15 times enhancement of the permeation flux. Fundamentally, the objectives of module design should include the minimization of the cost per amount of mass transferred (energy consumption and module production cost) and the maximization of the system performance through optimizing the flow geometry and operating conditions of the module, scale-up potential, and expansion of niche applications. It is expected that this review can provide inspiration for novel module development
Validation and analysis of forward osmosis CFD model in complex 3D geometries
In forward osmosis (FO), an osmotic pressure gradient generated across a semi-permeable membrane is used to generate water transport from a dilute feed solution into a concentrated draw solution. This principle has shown great promise in the areas of water purification, wastewater treatment, seawater desalination and power generation. To ease optimization and increase understanding of membrane systems, it is desirable to have a comprehensive model that allows for easy investigation of all the major parameters in the separation process. Here we present experimental validation of a computational fluid dynamics (CFD) model developed to simulate FO experiments with asymmetric membranes. Simulations are compared with experimental results obtained from using two distinctly different complex three-dimensional membrane chambers. It is found that the CFD model accurately describes the solute separation process and water permeation through membranes under various flow conditions. It is furthermore demonstrated how the CFD model can be used to optimize membrane geometry in such as way as to promote the mass transfer
Corporate social responsibility: Mapping its social meaning
Purpose â The purpose of this paper is to address the social meaning of corporate social responsibility
(CSR) and improve understanding of this concept.
Design/methodology/approach â A free association task was completed by a sample of
275 individuals, mostly employees from different industries, who were given âsocially responsible
corporationâ as the stimulus.
Findings â The results elicit three distinct views of a socially responsible corporation. Some
individuals consider a socially responsible corporation to be one that undertakes its business
operations in an efficient and ethical manner. Others see it as an organisation that takes an active role
in contributing to the well being of society and behaves in an ecologically friendly way and acts in the
field of social solidarity. For yet another set of participants a socially responsible corporation is one
that adopts human resources practices that demonstrate respect and concern for the well being of
employees and their families.
Research limitations/implications â The social meaning of CSR includes ideas that to some extent
mirror the conceptualisation introduced by previous theoretical models. However, this paper suggests
that the translation of the theoretical models into instruments addressing stakeholdersâ perceptions of
CSR requires closer scrutiny and validation through contextual (e.g. national) adaptations.
Originality/value â The paper contributes by providing additional knowledge on the social meaning
of CSR in a European country, Portugal, and not only on Anglo-Saxon countries, therefore, introducing
specific situational challenges
Stability of layer-by-layer nanofiltration membranes in highly saline streams
Layer-by-layer (LBL) assembly is an essential method for the preparation of nanofiltration (NF) membranes, offering tunable charge and pore size, high water permeability, and good anti-fouling properties, making them highly suitable for resource recovery, seawater desalination, and other fields. Despite their advantages, LBL NF membranes suffer from salinity instability, limiting their use in highly saline streams. This perspective review provides a summary of the fundamental physical and chemical principles of LBL assembly related to the salinity stability of LBL NF membranes. We critically analyze the driving force of LBL assembly, the binding strength of polyelectrolyte (PE) pairs, and the overcompensation of LBL membranes. We also discuss the factors affecting overcompensation level with respect to two different time scales. Furthermore, we examine the relationship between overcompensation level and salinity stability of LBL membranes, considering physical (osmotic pressure) and chemical (Le Chatelier's principle) aspects. Our analysis demonstrates that the salinity stability of LBL NF membranes in highly saline solutions can be improved by selecting PEs with stronger binding strength, increasing the overcompensation level, and chemical crosslinking. These methods not only enhance the salinity stability of LBL NF membranes but also offer greater potential for their future application in highly saline streams
Potable Water Reuse through Advanced Membrane Technology
© 2018 American Chemical Society. Recycling water from municipal wastewater offers a reliable and sustainable solution to cities and regions facing shortage of water supply. Places including California and Singapore have developed advanced water reuse programs as an integral part of their water management strategy. Membrane technology, particularly reverse osmosis, has been playing a key role in producing high quality recycled water. This feature paper highlights the current status and future perspectives of advanced membrane processes to meet potable water reuse. Recent advances in membrane materials and process configurations are presented and opportunities and challenges are identified in the context of water reuse
Contracepção: Conhecimentos e atitudes em jovens universitårios
O aumento da percentagem de gravidez na adolescĂȘncia (Portugal regista
19/1000 na faixa etĂĄria dos 15 aos 19 anos), juntando-se a outros riscos ligados Ă
actividade sexual, tornam os jovens um grupo vulnerĂĄvel em termos de saĂșde sexual e
reprodutiva. Esta investigação avaliou os conhecimentos e atitudes sobre os métodos
contraceptivos em jovens estudantes universitĂĄrios. Administraram-se 436 questionĂĄ -
rios a 113 rapazes e 323 raparigas, entre os 18 e os 24 anos. Aplicaram-se medidas de
conhecimento (CKI; Delcampo e Delcampo, 1976) e de atitudes (CAS; Kyes, 1987)
acerca dos métodos contraceptivos. Os resultados obtidos demonstram que a maioria
tem pouco conhecimento acerca dos métodos contraceptivos mas revelou uma forte
atitude preventiva face a uma gravidez indesejada. Encontraram-se diferenças estatis -
tica mente signficativas entre indivĂduos de sexo diferentes: as raparigas apresent am
mais conhecimentos e preocupação preventiva face à contracepção. ------ ABSTRACT ------The increase in unplanned pregnancies (the rate in Portugal is 19/1000
in 15-19 year-olds), is responsible for ranking young people as an important target
group in terms of sexual health prevention. This study tested knowledge and attitude
towards contraceptive methods in 18-24 year old college students. Structured selfreported
questionnaires were responded by 436 participants (113 college men and 323
college women). Questionnaires assessed knowledge (CKI; Delcampo e Delcampo,
1976) and attitude (CAS; Kyes, 1987) towards contraceptive methods. The findings
show the majority has insufficient contraceptive knowledge although they have a
strong preventive attitude towards unwanted pregnancy.
The results reveal significant variation in responses by gender: college women
demonstra ted better knowledge and preventive attitude in relation to contraception
Fouling of reverse osmosis and nanofiltration membranes by biological macromolecules - probing the foulant-membrane and foulant-foulant interactions
This study investigated the fouling of pressureâdriven membranes (reverse osmosis, nanofiltration, and ultrafiltration) and osmoticallyâdriven forward osmosis (FO) membrane by organic macromolecules. Protein and humic acid, two types of ubiquitous identified membrane organic foulants, were chosen as the model foulants. It was found that the hydrodynamic conditions (initial flux and crossâflow velocity) and feedwater composition (foulant concentration, pH, ionic strength, and divalent ions concentration) played a significant role on the organic fouling of these two types of membranes. A limiting flux model is developed for predicting the fouling behavior of pressure driven membranes by organic macromolecules. The project investigated the dependence of limiting flux on intermolecular interaction between foulant molecules. It was observed that the limiting flux was directly proportional to the intermolecular electrostatic repulsive force and that conditions enhancing foulantâdepositedâfoulant repulsion resulted in greater limiting flux values. Such observations agree well with a theoretical model capturing both hydrodynamic and DLVO interactions. Interaction force measurements by atomic force microscopy (AFM) were also performed. The limiting flux correlated reasonably well with AFM interaction force between the model foulant and the fouled membrane surface.SUG 4/0
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