Modelling of heat transfer for progressive freeze concentration process by spiral finned crystallizer

This study presents a novel design for a spiral finned crystallizer which is the primary element of progressive freeze concentration (PFC) system,which simplifies the setup of the conventional system.After the crystallizer has been designed,the research experiments have been conducted and evaluated through a thorough analysis of its performance by developing a mathematical model that can be used to predict the productivity of ice crystal at a range of coolant temperature.The model is developed based on the basic heat transfer equation,and by considering the solution's and the coolant's convective heat transfer coefficient (h) under the forced flow condition.The model's accuracy is verified by making comparison between the ice crystal mass' experimental value and the values predicted by the model.Conseouentiv,the study found that the model helos in enhancing the PFC system.     

Review: Parametric Study on the Performance of Progressive Cryoconcentration System

Progressive cryoconcentration (PC) is gaining acceptance in solution concentration process as it could provide an easy separation and ice purification with relatively low energy. In fact, the advantages of PC process as compared to the other concentration methods have led the growth of related studies that aim to provide the best system or condition for the separation process involved. Apart from the provision of appropriate equipment, the PC process should also be conducted at its optimum conditions of operating parameters involved, which could give the highest separation efficiency. Hence, relationship between the parameters, which covers both manipulated and determinant parameters should be studied first. This review summarizes the previous conducted studies on the effect of various operating parameters on the PC performance, which includes effect of coolant temperature, solution flowrate, initial solution concentration, freezing time, ice crystal front growth rate, and stirring rate.     

Critical assessment of medical devices on reliability,replacement prioritization and maintenance strategy criterion: Case study of Malaysian hospitals

The Biomedical Engineering Maintenance Services (BEMS) is a comprehensive maintenance program that ensures the safety and reliability of medical devices. Significant and crucial devices are identified and prioritized for best practice prior to the equipment life cycle to mitigate functional problems, alarmed by the Fourth Industrial Revolution (4IR) underlying the modernization agenda. A model of multi-criteria decision-making (MCDM) to prioritize medical devices according to their criticality is presented in this paper, with the utilization of quality function deployment (QFD) and fuzzy logic in the development of the model through a quantitative survey of experts from all regions in Malaysia. As a result, a customized version of the Asset Criticality Assessment (ACA) is developed and is recommended for use in more than 144 Ministry of Health (MOH) hospitals. Subsequently, real data of four selected devices are pulled from the Asset and Services Information System (ASIS) to demonstrate a relevant and comparable end-result using the QFD and fuzzy logic. In essence, the key contribution of the customized ACA model is that it assesses a promising evaluation with a broader range on both the performance of medical devices and the appropriate asset replacement choices. This leads to an effective maintenance strategy for each device and the modernization of reliability computation metrics.     

pH effects on collagen fibrillogenesis in vitro: Electrostatic interactions and phosphate binding

Collagen self-assembly in vitro was conducted in the pH range from 6.0 to 10.5 at 30 °C in order to investigate the electrostatic interactions that occur during fibril formation. A sigmoidal curve was observed in the growth rate of fibrils. Collagen fibril morphologies imaged by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) present bundling of fibrils with a small amount of non-fibrillar collagen. At a low pH of 6.6, collagen molecules form small fibrils with a diameter of 85 nm. In the pH range from 6.9 to 8.0, they form fibrils with a diameter of approximately 200 nm, even though the rate of fibrillogenesis accelerates with increasing pH in this range. Zeta potential measurements of soluble collagen indicate that the net surface charge of collagen molecules is not only affected by the pH of medium but also by the presence of added salts. The acceleration of fibrillogenesis rate with increasing pH from 6.6 to 9.2 is consistent with a reduction of surface net charge since the isoelectric point of soluble collagen is approached. The native D-periodicity of 62 nm was found except at pH 7.1 where collagen molecules form short banding of 50–60 nm in the early stage of fibrillogenesis which might be caused by an unusual alignment of collagen molecules in fibrils.     

Beta-cyclodextrin adsorbents to remove water pollutants—a commentary

Beta-cyclodextrin-based adsorbent is a promising adsorbent because it has unique characteristics and able to form host-guest complexes with various organic compounds. Adsorption using beta-cyclodextrin-based adsorbent has continuously improved by various preparation strategies and crosslinking agents. This commentary aims to highlight the preparation strategies, properties, and adsorption mechanisms of beta-cyclodextrin-based adsorbents. The adsorbents can be generally classified according to the preparation methods and display high adsorption capacity especially for dyes. Particularly, composite/nanocomposite beta-cyclodextrin-based adsorbents exhibit outstanding adsorption capacity even though the surface area is lower than that of porous and magnetic beta-cyclodextrin-based adsorbents. The beta-cyclodextrin/chitosan functionalized graphene oxide hydrogel with specific surface of 17.6 m²·g^–1 yields an extraordinarily maximum adsorption capacity of 1499 mg·g^–1 methylene blue, while beta-cyclodextrin/chitosan modified with iron(II, III) oxide nanoparticles displays a much greater maximum adsorption capacity at 2780 mg·g^–1. The hydrophobic interaction, functional groups, hydrogen bonding, and electrostatic interaction govern the adsorption to a greater capacity. Although this commentary is not exhaustive, the preparation strategies and illustrated mechanisms provide useful insights into the adsorbent–adsorbate interactions, cost-effective analysis, challenges, and future directions of beta-cyclodextrin-based adsorbents in wastewater treatment.     

Benefits of Facebook fan/brand page marketing and its influence on relationship commitment among Generation Y: Empirical evidence from Malaysia

This study aims to understand the influence of relational benefits of Facebook brand/fan page towards relationship commitment among Generation Y. Additionally, this study also investigates the mediating effect of customer satisfaction on the relationship between relational benefits and relationship commitment. A total of 195 sets of online questionnaire were collected using snowball sampling method for the statistical data requirement of SmartPLS. The analysis found significant positive relationships between relational benefits and relationship commitment, however, only on social, functional, and special treatment benefits. Surprisingly, the findings also showed an insignificant mediation effect of customer satisfaction on the relationship between relational benefits and relationship commitment. The research findings are valuable to both the theoretical and businesses adopting social media as a marketing strategy. Marketers employing the Facebook or other social media in catering and reacting to the Generation Y needs will benefit the most; securing their confidence and loyalty towards purchasing a certain brand.     

Comparison of foam core sandwich panel and through‐thickness polymer pin–reinforced foam core sandwich panel subject to indentation and flatwise compression loadings

Through‐thickness polymer pin–reinforced foam core sandwich (FCS) panels are new type of composite sandwich structure as the foam core of this structure was reinforced with cylindrical polymer pins, which also rigidly connect the face sheets. These sandwich panels are made of glass fiber–reinforced polyester face sheets and closed‐cell polyurethane foam core with cylindrical polymer pins produced during fabrication process. The indentation and compression behavior of these sandwich panels were compared with common traditional sandwich panel, and it has been found that by reinforcing the foam core with cylindrical polymer pins, the indentation strength, energy absorption, and compression strength of the sandwich panels were improved significantly. The effect of diameter of polymer pins on indentation and compression behavior of both sandwich panels was studied and results showed that the diameter of polymer pins had a large influence on the compression and indentation behavior of through‐thickness polymer pin–reinforced FCS panel, and the effect of adding polymer pins to FCS panel on indentation behavior is similar to the effect of increasing the thickness of face sheet. The effect of strain rate on indentation behavior of FCS panel and through‐thickness polymer pin–reinforced FCS panel were studied, and results showed that both types of composite sandwich panels are strain rate dependent structure as by increasing strain rate, the indentation properties and energy absorption properties of these structures are increased. POLYM. COMPOS., 37:612–619, 2016. © 2014 Society of Plastics Engineers     

Influence of catalytic particle size on the performance of fluidized-bed chemical vapor deposition synthesis of carbon nanotubes

In this paper, the impacts of catalytic particle size on the overall reactor performance for carbon nanotubes (CNTs) production using a fluidized-bed chemical vapor deposition (FBCVD) process have been studied. Six different particle size fractions (10-20 μm, 20-53 μm, 53-75 μm, 75-100 μm, 100-200 μm, and 200-300 μm) were selected. It was observed that the smaller the catalytic particle diameter, the greater the carbon deposition efficiency and the greater CNT synthesis selectivity. The 10-20 μm catalytic particles exhibited 30% higher carbon deposition efficiency than the 200-300 μm catalytic particles. The selectivity toward CNTs formation was also approximately 100%. These observations could be explained by the fact that when the diameter of the catalytic particle gets smaller, the breakthrough capacities during frontal diffusion will be bigger due to a shorter diffusion path length within the particle. Moreover, the fine particles ensured high interstitial velocity which subsequently enhances the heat and mass transfer, and consequently improves the CVD reaction.     

Biochar production from microalgae cultivation through pyrolysis as a sustainable carbon sequestration and biorefinery approach

Microalgae cultivation and biomass to biochar conversion is a potential approach for global carbon sequestration in microalgal biorefinery. Excessive atmospheric carbon dioxide (CO₂) is utilized in microalgal biomass cultivation for biochar production. In the current study, microalgal biomass productivity was determined using different CO₂ concentrations for biochar production, and the physicochemical properties of microalgal biochar were characterized to determine its potential applications for carbon sequestration and biorefinery. The indigenous microalga Chlorella vulgaris FSP-E was cultivated in photobioreactors under controlled environment with different CO₂ gas concentrations as the sole carbon source. Microalgal biomass pyrolysis was performed thereafter in a fixed-bed reactor to produce biochar and other coproducts. C. vulgaris FSP-E showed a maximum biomass productivity of 0.87 g L^?1 day^?1. A biochar yield of 26.9% was obtained from pyrolysis under an optimum temperature of 500 °C at a heating rate of 10 °C min^?1. C. vulgaris FSP-E biochar showed an alkaline pH value of 8.1 with H/C and O/C atomic ratios beneficial for carbon sequestration and soil application. The potential use of microalgal biochar as an alternative coal was also demonstrated by the increased heating value of 23.42 MJ kg^?1. C. vulgaris FSP-E biochar exhibited a surface morphology, thereby suggesting its applicability as a bio-adsorbent. The cultivation of microalgae C. vulgaris FSP-E and the production of its respective biochar is a potential approach as clean technology for carbon sequestration and microalgal biorefinery toward a sustainable environment.