A micro flow cell cytometry based on MEMS technologies using silicon and optical fibers

In this paper, we tested multi-mode optical fibers to select a suitable fiber for effective flow of cell cytometry. In order to align micro nozzle and multi-mode optical fibers, a guide channel was fabricated by silicon wafer etching with MEMS (Micro Electro-Mechanical System) technologies. The fabricated system is advantageous due to its low cost and simplicity in construction. It is possible because multi-mode optical fibers replace many optical lenses and expensive equipment. As a result of the flow cell cytometry using multi-mode optical fibers for both input and output, it is easy to align and we can reduce power consumption. The sensitivity of the micro flow cell cytometry is much better than other cytometries. The output voltage was as high as 300 mV. We injected various cells through the designed and fabricated flow cell cytometry, and we were able to detect cells. Every cell has its own cellulose and wall which cause different light permeability; therefore, we could get different voltage characteristics according to different cells. From the experimental results, we were able to count the number of cells and differentiate the relative size of the injected cells; therefore, we can use the micro flow cell cytometry for analyzing cells [1, 2].     

Stress and strain partition in elastic and plastic deformation of two phase alloys

A stress and strain partition theory for two phase alloys was developed on the basis of the modified rules of mixtures. The extreme value condition of macroscopic strain energy density was found through Lagrangian multiplier method. Expressions for macroscopic elastic constants of two phase alloys were derived from the extreme value condition by assuming the strain linearity between constituent phases. Governing equation for stress and strain partition in plastic deformation was also obtained from the extreme value condition. The calculated elastic constants of WC-Co alloys fell invariably within the Hashin and Shtrikman's bounds. According to the governing equation the stress ratio between constituent phases was plotted as a function of strain increment ratio. By applying the governing equation to spheroidized carbon steel and duplex stainless steel, it was shown that the stress ratios, strain ratios, macroscopic stress-strain curves, and internal stresses could be evaluated from thein situ stress-strain curves of constituent phases.     

Functional foods with antiviral activity

Food Science and Biotechnology - Viruses are known to cause a variety of diseases, ranging from mild respiratory diseases, such as the common cold, to fatal illnesses. Although the development of...     

Effect of gamma-irradiation on pathogens inoculated into ready-to-use vegetables

Three ready-to-use vegetables, cucumber, blanched and seasoned spinach, and seasoned burdock were selected and the effects of an irradiation treatment for eliminating pathogens were investigated. The pathogens tested were Salmonella Typhimurium, Escherichia coli, Staphylococcus aureus, and Listeria ivanovii. Inoculated viable cells of S. Typhimurium and L. ivanovii into cucumber and blanched and seasoned spinach were reduced about 4 decimal points by 2 kGy of irradiation and that of S. aureus inoculated into burdock showed about 4-decimal point reduction by 1 kGy. E. coli inoculated into burdock was not detected by 1 kGy. All the bacterial contents of test pathogens into the samples were reduced to below the limit of detection by 3 kGy irradiation. The range of the D10 value was 0.28-0.42 among the four pathogens. A Salmonella mutagenicity assay (Ames test) indicated that the 10 kGy-irradiated ready-to-use vegetables did not cause any increase. The studies indicated that a low-dose irradiation (3 kGy or less) can improve the microbial safety of ready-to-use vegetables.     

Effects of gamma irradiation on color characteristics and biological activities of extracts of Lonicera japonica (Japanese honeysuckle) with methanol and acetone

Effects of gamma irradiation on the color characteristic and biological activities of methanol and acetone extracts of Lonicera japonica (Japanese honeysuckle) irradiated at 0, 10, 20, and 30 kGy were investigated. Hunter color L^*- and a^*-value increased by irradiation in a dose-dependent manner, resulting in it being lighter than the nonirradiated, while Hunter color b^*-values decreased by irradiation (P<0.05). The extracts from L. japonica showed an inhibition effect against tyrosinase, xanthine oxidase and the nitrite scavenging ability. Tyrosinase inhibition effect of L. japonica was higher in the irradiated sample than the nonirradiated, and the effect was increased by irradiation doses. The L. japonica extracts had a higher inhibitory effect against xanthine oxidase, and the effect was not changed by irradiation. Nitrite scavenging activity was the highest in L. japonica extract at pH 1.2. The difference between solvents used was not detected. Thus, gamma irradiation may have no influence on the biological activities of the L. japonica extracts except for the tyrosinase inhibition effect when irradiated up to 30 kGy.     

On-site crosslinked quaternized poly(vinyl alcohol) as ionomer binder for solid alkaline fuel cells

Water-soluble polyvinyl alcohol functionalized with quaternary ammonium groups and crosslinked quaternized polyvinyl alcohol were synthesized and used to prepare an ionomer binder solution having a low boiling point and high dielectric constant solvent to be used in electrodes for solid alkaline fuel cells. The polyvinyl alcohol was quaternized to have anion-conducting ability using glycidyltrimethylammonium chloride. To prevent washing-out of the water-soluble anion-conducting ionomer during fuel cell operations, the quaternized poly(vinyl alcohol) was successfully crosslinked by using an on-site crosslinking method. The highest ionic conductivity of the ionomer was 2.3 × 10⁻² S cm⁻¹, and its ion exchange capacity was 1.2 meq g⁻¹ at room temperature. The electrodes were fabricated by a spray method on anion-exchangeable membranes, and membrane-electrode assemblies were operated at 50 °C in ambient pressure and were characterized by voltage–current relationship and cyclic voltammetry. The highest performance of the membrane-electrode assemblies having the electrode with the ionomer of 25 wt.% in dry weight basis was 172.8 mW cm⁻² at 0.485 V. As a result, the anionic binder electrodes introduced by the on-site crosslinking were successfully functioned both to conduct OH⁻ ions between electrodes and an electrolyte and to move electron to an external circuit by forming three phase boundary at the electrode of the membrane-electrode assemblies.     

Refrigerant Distribution in a Minichannel Evaporator Having Vertical Headers

Refrigerant R-410a flow distribution is experimentally studied in a test section simulating a minichannel heat exchanger having vertical headers with two pass configuration. Tubes are heated to yield a test section outlet superheat of 5°C with inlet quality of 0.3. Mass flux is varied from 60 kg/m²-s to 70 kg/m²-s. Effects of outlet locations are investigated in a search for an optimum configuration. The effect of varying the number of tubes of each pass is also investigated. Results show that significant liquid flows through bottom channels, and less liquid is supplied to top channels. For the outlet location, a bottom outlet is better than a middle or top outlet. In addition, assigning a lower number of tubes to inlet pass yields better flow distribution. Correlations are developed for the fraction of liquid or gas taken off by the downstream channel as a function of header gas Reynolds number immediately upstream. The correlations may be used to predict the liquid or gas distribution in a parallel-flow heat exchanger havin vertical headers.