Large‐Area,Periodic, Hexagonal Wrinkles on Nanocrystalline Graphitic Film

Sinusoidal wrinkles develop in compressively stressed film as a means to release stored elastic energy. Here, a simple way to fabricate large‐area, periodic, hexagonal wrinkled pattern on nanocrystalline graphitic films grown on c‐plane sapphire (<50 nm thick) by the spontaneous delamination–buckling of the as‐grown film during cooling is reported. According to the continuum mechanics calculation, strain‐relief pattern adopting the hexagonal wrinkled pattern has a lower elastic energy than that of the telephone cord wrinkle at thickness regime below 50 nm. A high‐fidelity transfer method is developed to transfer the hexagonal wrinkled films onto arbitrary substrates. Nanoindentation studies show that hexagonal wrinkle film engineered this way may act as shock absorber. The hexagonal wrinkled carbon film is able to selectively promote the differentiation of human mesenchymal stem cell toward the osteogenic lineage in the absence of osteogenic inducing medium.     

Characterization of mouse sperm TMEM190, a small transmembrane protein with the trefoil domain: evidence for co-localization with IZUMO1 and complex formation with other sperm proteins

TMEM190, a small transmembrane protein containing the trefoil domain, was previously identified by our proteomic analysis of mouse sperm. Two structural features of TMEM190, 'trefoil domain' and 'small transmembrane protein', led us to hypothesize that this protein forms a protein-protein complex required during fertilization, and we characterized TMEM190 by biochemical, cytological, and genetic approaches. We showed in this study that the mouse Tmem190 gene exhibits testis-specific mRNA expression and that the encoded RNA is translated into a 19-kDa protein found in both testicular germ cells and cauda epididymal sperm. Treatment of the cell surface with proteinase K, subcellular fractionation, and immunofluorescence assay all revealed that mouse TMEM190 is an inner-acrosomal membrane protein of cauda epididymal sperm. During the acrosome reaction, TMEM190 partly relocated onto the surface of the equatorial segment, on which sperm-oocyte fusion occurs. Moreover, TMEM190 and IZUMO1, which is an immunoglobulin-like protein required for gamete fusion, co-localized in mouse sperm both before and after the acrosome reaction. However, immunoprecipitates of TMEM190 contained several sperm proteins, but did not include IZUMO1. These findings suggest that a mouse sperm protein complex(es) including TMEM190 plays an indirect role(s) in sperm-oocyte fusion. The role(s), if any, is probably dispensable since Tmem190-null male mice were normally fertile.     

Prediction of transient pressure change during natural gas hydrate formation

Abstract

The increasing demand for fossil fuels and diminishing natural energy reserves have necessitated the exploration of gas hydrates. Gas hydrates find importance in oil and gas industries where the formation and dissociation of gas hydrate become important. Thus, the proper understanding of formation, decomposition and properties of gas hydrates is a required. In this work, a macroscopic kinetic model is analyzed and modified to predict the pressure change with time during the hydrate formation based on the chemical affinity of compounds. With the help of experimental data, the degree of parity of the modified and unmodified models are explained. The dependency of the chemical affinity of the gas hydrate reformers is explained based on the kinetic model validation with the experimental results. The modified model predict the transient pressure during gas hydrate formation with an average absolute error of 3.6%.     

Influence of TiO2 nanofiller geometry on the rheological and optical properties of poly(acrylic acid)-based nanocomposite hydrogels

The properties of macroscopic polymer nanocomposites are highly dependent on the nanoparticle–polymer interfacial region, which varies with the morphology of the nanoparticles. Herein, we used TiO₂ nanofillers with very low aspect ratio, the same chemical composition, and surface functions, but different geometries (nanospheres and nanoplates) dispersed in a poly(acrylic acid) matrix to analyze the influence of the nanoparticle geometry on the properties of nanocomposite hydrogels. The geometry was found to affect the swelling and rheological properties of the nanocomposite polymers. Particularly, the yield strain (from 25% to 130%), modulus (from 17,500 to 25,000 Pa), and brittleness of nanoplates based nanocomposite increased more significantly. Finite-difference time-domain simulations demonstrated that nanoplates increased the wavelength of the absorption maxima (224 nm for NS to 240 nm for NP) and charge distribution. The results obtained in this research indicate that the nanofiller shape markedly influences the rheological properties of the nanocomposite polymers, opening the door to further research focused on polymer–nanofiller interactions, and their effect on the macroscopic properties of the nanocomposites.     

Fine-tuning of phase behavior of oxazoline copolymer-based organic–inorganic hybrids as solid-supported sol–gel materials

Silica-supported organic–inorganic polymer hybrids were synthesized via in situ sol–gel condensation of silica monomer in the presence of oxazoline copolymer. A stable copolymer of 2-ethyl-2-oxaoline and 2-isopropyl-2-oxazoline was prepared using methyl p-tosylate as the living polymerization initiator with molecular mass of 4200 g mol⁻¹. Lower critical solution temperature (LCST) of this copolymer was thermally found to be at 77 °C. The copolymer was mixed with tetramethoxysilane (TMOS) in different amounts (0.039:1 to 0.158:1 weight ratios) via in situ sol–gel condensation to produce organic–inorganic hybrids including thermosensitive copolymer. Tuning of these solid-supported materials showed sharp phase transitions changes in a temperature range from 42 to 58 °C, which was confirmed using differential scanning calorimetry. Enthalpy of the phase transition was also calculated using the area above the endothermic peak. A typical concave curve was obtained for LCST-type phase diagram suggesting the dependence of phase transition temperature on the concentration of the copolymer in the hybrid. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48163.     

Epidermal Electronic Systems for Measuring the Thermal Properties of Human Skin at Depths of up to Several Millimeters

Monitoring the composition, blood flow properties, and hydration status of human skin can be important in diagnosing disease and tracking overall health. Current methods are largely limited to clinical environments, and they primarily measure properties of superficial layers of the skin, such as the stratum corneum (10–40 µm). This work introduces soft, skin‐like thermal depth sensors (e‐TDS) in designs that seamlessly couple with human skin and measure its thermal properties with depth sensitivity that can extend up to 6 mm beneath the surface. Guidelines for tailoring devices to enable measurements through different effective depths follow from a systematic set of experiments, supported by theoretical modeling. On‐body testing validates the physiological relevance of measurements using the e‐TDS platform, with potential to aid the diagnosis of deep cutaneous and systemic diseases. Specific demonstrations include measurements that capture responses ranging from superficial changes in skin properties that result from application of a moisturizer, to changes in microvascular flow at intermediate depths induced by heating/cooling, to detection of inflammation in the deep dermis and subcutaneous fat in an incidence of a local bacterial infection, cellulitis.     

Current-Mode Multiphase Sinusoidal Oscillator Using Current Differencing Transconductance Amplifiers

This paper describes a simple current-controlled current-mode multiphase sinusoidal oscillator based on current differencing transconductance amplifiers (CDTAs) as active components. The proposed oscillator circuit, which employs only one CDTA and one grounded capacitor for each phase, can generate arbitrary n current-output signals (n being even or odd) equally spaced in phase, all at high output impedance terminals. The oscillation condition and the oscillation frequency can be controlled electronically and independently through the bias current of the CDTA. The oscillator has low-component count, low-sensitivity performance, and is highly suitable for monolithic implementation. PSPICE simulation results are given to confirm the operation of the proposed oscillator.     

A simple viscometric test for number average and weight average molecular weight of 12.6% N pyro nitrocellulose

In the poor solvent acetone/ethanol the viscosity of a 3% solution of 12.6% N pyro nitrocellulose is found to be related to the geometric mean of the number average and weight average molecular weights. The fractional increase in the viscosity of such a solution on the addition of lead ß-resorcylate is a function only of number average molecular weight. Once calibration has been made against osmotic pressure measurements and intrinsic viscosity, both number and weight average may be measured rapidly with an accuracy which is no less than that of the osmotic pressure and intrinsic viscosity measurements themselves.     

Size‐controlled preparation of nanosoy for potential biomedical applications

Soy protein isolate nanoparticles (nanosoy) have significant applications in drug delivery, wound care systems and tissue engineering. We report an optimum technique named nanoprecipitation which enabled one‐step formation of near‐monodisperse nanosoy based on solvent displacement. Excellent control over protein aggregation was achieved, producing nanoparticles in the size range of 5–15 nm. The effect of various process parameters such as temperature, solvent/non‐solvent ratio, crosslinker content and type of surfactant on the particle size was investigated. The structural and morphological features were analysed using dynamic light scattering, X‐ray diffraction and high‐resolution transmission electron microscopy. The morphological examination indicated that the particles formed were spherical in shape and further reduction in the average particle diameter was achieved by reducing the temperature and solvent/non‐solvent ratio of the reaction medium. Surface charge and stability of nanosoy dispersions were analysed using zeta potential measurements. Further, ciprofloxacin release was monitored using nanosoy as a drug carrier. This technique provides an effective and straightforward approach offering considerable advantages in terms of economic, technical and environmental performance. © 2016 Society of Chemical Industry