Convective heat transfer in liquid microchannels with hydrophobic and hydrophilic surfaces

Experiments were performed to study the heat transfer characteristics of channel flows of deionized (DI) water, methanol, 50 wt% DI water/50 wt% methanol mixture, and ethanol solution in asymmetrically (one sided heating) heated rectangular microchannels with an aspect ratio (H/W) of 0.56 and the corresponding hydraulic diameters (D) of 129 μm at 5 ? Re ? 240. Local heat transfer coefficients distribution were recorded with both isothermal (273 K) and isoflux (12.6, 18.1, 32.3, 50.5 mW/mm²) heating. The influences of test liquid mass flow rates, test fluids, heating condition (isothermal vs isoflux), and surface condition (hydrophilic vs hydrophobic) on heat transfer behavior were examined. Thermal entrance length were also found and correlated in terms of the relevant parameters.     

Applying the one-column, many pencil local scanning maskless lithography technology to micro-RP system

This paper introduces an innovative one column, many pencil local scanning maskless lithography technology used in dynamic mask and applies it to rapid prototyping (RP) system. By using this technology in micro RP system, the resolution of the 3-D microstructures can be upgraded remarkably. In addition, some relevant experiments are conducted on this micro rapid prototyping system. In the experiment, light beam is projected onto a digital mirror device (DMD) chip [Hornbeck LJ. Digital light processing: A new MEMS-based display, 4th Sensor Symp, p. 297–304 (1996)], and the image is reflected through a micro mirror. Meanwhile, by making use of zoom lens and pins array mask (PAM), the continuing pixels can be scattered. Moreover, in order to project scattered pixels onto the resin surface, the optical system is exploited. Additionally, by using a micro-stage, it is able to control the micro X-Y movement between the scattered pixels. Furthermore, this paper makes use of the spray coating technology to improve the build up capability of the overhand structures of the traditional deep dip liquid-type RP system. Finally, combining the fore-mentioned technologies, one can produce 3-D prototypes with overhand structures in higher resolution.     

Free radical-scavenging phytochemicals of hot water extracts of Acacia confusa leaves detected by an on-line screening method

Acacia confusa Merr. (Leguminosae), a species native to Taiwan, is widely distributed on the hills and lowlands of Taiwan, and has been traditionally used as a medicine. In this study, phytochemicals and antioxidant activities of hot water extracts from A. confusa leaves were investigated for the first time. Among all the fractions from hot water extracts of leaves, the EtOAc-soluble fraction exhibits the best DPPH radical-scavenging activity, superoxide radical-scavenging activity, and reducing power. In addition, a rapid screening method, on-line RP-HPLC-DPPH system, for individual antioxidants in the EtOAc-soluble fraction was developed. Furthermore, following solid phase extraction (SPE) and reverse-phase high-performance liquid chromatography 12 pure phenolic compounds, including five major compounds (gallic acid, (+)-catechin, (−)-epicatechin, myricetin 3-glucopyranoside, and myricetin 3-rhamnopyranoside) were detected using the developed screening method. These results demonstrated that hot water extracts of A. confusa leaves have excellent antioxidant activities and thus have great potential as a source for natural health products.     

Updating the research on the chemopreventive and therapeutic role of the peptide lunasin

Chronic diseases have become the medical challenge of the 21st century because of their high incidence and mortality rates. Modulation of diet and lifestyle habits is considered as the best strategy for the prevention of these disorders. Health promoting benefits beyond their nutritional effects have been described for multiple dietary compounds. Among these compounds, the peptide lunasin is considered as one of the most promising. Naturally present in soybean, lunasin has been extensively studied in the last two decades because of its potential against chronic diseases such as cancer, cardiovascular and immunological disorders. The purpose of this article is to summarise the evidence on the presence of lunasin in soybean and derived foods, and its bioavailability once it is orally ingested. The protective and therapeutic effects of this peptide against cancer, oxidative stress, inflammation, and high cholesterol levels as well as the molecular mechanisms of action involved in these effects are also described in this review. © 2017 Society of Chemical Industry     

Speciation of animal fat: Needs and challenges

The use of pork fat is a concern for Muslims and Jews, who for religious reasons avoid consuming anything that is pig-derived. The use of bovine materials, including beef fat, is prohibited in Hinduism and may also pose a risk of carrying the infectious agent for bovine spongiform encephalopathy. Vegetable oils are sometimes adulterated with animal fat or pork fat with beef fat for economic gain. The development of methods to determine the species origin of fat has therefore become a priority due to the complex and global nature of the food trade, which creates opportunities for the fraudulent use of these animal fats as food ingredients. However, determining the species origin of fats in processed foods or composite blends is an arduous task as the adulterant has a composition that is very similar to that of the original fat or oil. This review examines some of the methods that have been developed for fat speciation, including both fat-based and DNA-based methods, their shortcomings, and the need for additional alternatives. Protein-based methods, specifically immunoassays targeting residual proteins in adipose tissue, that are being explored by researchers as a new tool for fat speciation will also be discussed.     

Effects of Duplex Nitriding and TiN Coating Treatment on Wear Resistance,Corrosion Resistance and Biocompatibility of Ti6Al4V Alloy

Ti6Al4V alloy substrates were nitrided at 900 °C. TiN coatings were then deposited on the nitrided substrates using a closed-field unbalanced magnetron sputtering system. The microstructure, hardness and adhesion properties of the TiN-N-Ti6Al4V substrates were evaluated and compared with those of an untreated Ti6Al4V sample, a nitrided Ti6Al4V sample and a TiN-coated Ti6Al4V sample, respectively. The tribological properties of the various samples were investigated by means of reciprocating sliding wear tests performed in 0.9 wt.% NaCl solution against 316L, Si₃N₄ and Ti6Al4V balls, respectively. In addition, the corrosion resistance was evaluated using potentiodynamic polarization tests. Finally, the biocompatibility of the samples was investigated by observing the attachment and growth of purified mouse leukemic monocyte/macrophage cells (Raw 264.7) on the sample surface after culturing periods of 24, 72 and 120 h, respectively. Overall, the results showed that the duplex nitriding/TiN coating treatment significantly improved the tribological, anti-corrosion and biocompatibility properties of the original Ti6Al4V alloy.     

SiCO-doped carbon fibers with unique dual superhydrophilicity/superoleophilicity and ductile and capacitance properties

Silicon oxycarbide (SiCO) glass-doped carbon fibers with an average diameter of 163 nm were successfully synthesized by electrospinning polymer mixtures of preceramic precursor polyureasilazane (PUS) and carbon precursor polyacrylonitrile (PAN) into fibers then converting to ceramic/carbon hybrid via cross-linking, stabilization, and pyrolysis at temperatures up to 1000 °C. The transformation of PUS/PAN polymer precursors to SiCO/carbon structures was confirmed by EDS and FTIR. Both carbon and SiCO/carbon fibers were amorphous and slightly oxidized. Doping with SiCO enhanced the thermal stability of carbon fibers and acquired new ductile behavior in the SiCO/carbon fibers with significantly improved flexibility and breaking elongation. Furthermore, the SiCO/carbon fibers exhibited dual superhydrophilicity and superoleophilicity with water and decane absorbing capacities of 873 and 608%, respectively. The cyclic voltammetry also showed that SiCO/carbon composite fibers possess better capacitor properties than carbon fibers.     

Effects of Cu content on microstructure and mechanical properties of Al–14.5Si–0.5Mg alloy

This study elucidates how Cu content affects the microstructure and mechanical properties of Al–14.5Si–0.5Mg alloy, by adding 4.65 wt.% and 0.52 wt.% Cu. Different Fe-bearing phases were found in the two alloys. The acicular β-Al₅FeSi was found only in the high-Cu alloy. In the low-Cu alloy, Al₈Mg₃FeSi₆ was the Fe-bearing phase. Tensile testing indicated that the low-Cu alloy containing Al₈Mg₃FeSi₆ had higher UTS and elongation than the high-Cu alloy containing the acicular β-Al₅FeSi. It is believed that the presence of the acicular β-Al₅FeSi in the high-Cu alloy increased the number of crack initiators and brittleness of the alloy. Increasing Cu content in the Al–14.5Si–0.5Mg alloy also promoted solution hardening and precipitation hardening under as-quenched and aging conditions, respectively. The hardness of the high-Cu alloy therefore exceeded that of low-Cu alloy.