Paper-based diagnostic devices for evaluating the quality of human sperm

Male infertility, which amounts to half of all infertility cases, is a serious problem worldwide. The percentage of fertility-related patients in sub-Saharan African countries is higher than that for the developed countries. In low-resource countries, examination of sperm characteristics for male infertility cannot be undertaken because of poor clinical access. To evaluate male fertility in assisted reproductive medicine laboratories, the numbers of motile human sperm, the degree of sperm motility, and sperm morphology have been commonly analyzed using a microscope. It is challenging to monitor the health status of human sperm in resource-limited or remote settings for two primary reasons: (1) high capital cost (equipment for currently accepted procedural standard), and (2) complexity of the currently accepted procedural standard used to simultaneously measure human sperm concentration and motility by skillful embryologists. Determining the health status of human sperm in order to evaluate fertilization capacity using various types of low-cost, easy-to-use, and rapid devices (or systems) is a longstanding but interesting biotechnologically relevant issue in various scientific communities such as male reproduction. Furthering such efforts will inherently influence birth rate in both developed and developing nations. We have demonstrated an inexpensive but robust and easy-to-handle device for monitoring the health status of human sperm made by patterning a piece of paper and measuring the activity of a specific enzyme—a simple and elegant solution. After applying semen to the hydrophilic center circle of our patterned paper, a thiazine assay can be used to suggest sperm concentration in semen, and a tetrazolium-based colorimetric assay (MTT assay) data can be used to help estimate the percentage of motile human sperm (sperm motility) in semen based on the character that motile human sperm moved in and on the paper. Using this paper-based device, we can evaluate fertility levels without consulting doctors and use our assay to compare results with World Health Organization (WHO) reference values for sperm concentration (>2×10⁷) and motility (>50 %). The duration and cost of one entire test are 30 min and 0.1 USD, respectively. We believe that this paper-based assay system would be useful for fertility checks based on WHO references, without need of a microscope, at home. Using this assay method, males in developed or developing countries who are reluctant or unable to consult assisted reproductive technologies clinics can self-analyze their sperm characteristics. We further note that our approach adheres to WHO regulations, especially in regard to in vitro diagnostic device performance with an associated diagnostic algorithm to enhance diagnostic accuracy (compared with just one diagnostic output), and we wish to emphasize that our research could significantly advance a broad range of diagnostic developments including paper-based diagnostic devices, in vitro diagnostic devices, and diagnosis of other diseases in various divisions of translational medicine. These results, we believe, will be of interest to a wide scientific audience working in materials science (biomaterials), chemistry (analytical and clinical), lab-on-a-chip technologies (the development of diagnostic tools), reproductive medicine, bioengineering, and translational medicine.     

Composition Regulation by Flow Copolymerization of Methyl Methacrylate and Glycidyl Methacrylate with Free Radical Method

It is important to match the feeding ratio of comonomers to the composition ratio in the resulting copolymers as closely as possible in industrial production, where the goal is often to produce more a homogeneous composition in copolymers. In this study, a flow copolymerization system with a conventionally initiated free radical method, together with randomly selected polymerization conditions is investigated. It is succeeded in achieving a closer match between the composition ratio and feeding ratio than previously reported in the copolymerization of styrene with methyl methacrylate and of glycidyl methacrylate with methyl methacrylate, which will widen the range of applications, by precisely controlling the mixing and heating in a flow polymerization apparatus. This is confirmed by the fact that the estimated values of reactivity ratios, r₁ and r₂, which are used in the reaction kinetics of copolymerization, are close to 1.     

Pseudo bond graph model of thermal transfers sustained by ice quantity of a domestic refrigerator for energy saving application

This paper presents a study on the use of ice to improve the energy efficiency of a domestic refrigerator by applying a pseudo bond graph model that describes the thermal transfers sustained by a quantity of ice introduced inside the cavity of refrigeration. The use of ice resulted in a global energy saving of 4.68%. The effect of ice was found to be more significant during the transitional regime. It reduced the response time to reach the stable average temperature from 15 h to only 3.5 h compared to when not using ice. This achievement did not cost additional electrical power, but rather allowed a saving of electrical energy of 76.73%. However, during the steady state, a reduction in the energy efficiency was noted. An improvement in the cooling by keeping the temperature inside the refrigerator more homogeneous is also proved. The model has two inputs: the outside temperature, and the modulated temperature of the evaporator. This latter determines the functioning of the compressor cycle. The model describes the thermal transfers by natural convection inside the refrigerator. Two experiments were carried out to make a performance comparison and to prove the influence of ice in cooling and energy saving. We used real measurements to modulate the evaporator temperature source in the pseudo bond graph model. The simulation results show the effectiveness of the proposed approach. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Deformation behaviors and fracture strength of β$\ubeta$-Si3N4 single crystals

In this study, the yield stress and fracture strength of $\beta$-Si₃N₄ single crystals were directly measured by bending tests of microcantilever beam specimens that were prepared by a focused ion beam method. The $\beta$-Si₃N₄ single crystals were plastically deformed at room temperature under high bending stress, and the yield stress depended on the crystal orientation. Transmission electron microscopy observation of the specimens after bending tests indicates that the plastic deformation resulted from dislocations in the primary slip system $\{10\overline{1}0\}$<0001>, and the critical resolved shear stress of this slip system determined from the yield stress was 1.34 GPa. The fracture strength of $\beta$-Si₃N₄ single crystals ranged approximately up to 20 GPa, depending on the crystal orientation as with the yield stress. The fracture behavior of $\beta$-Si₃N₄ single crystals was discussed in terms of the accumulation of dislocations.