Swelling behavior of butyl and chloroprene rubber composites with poly(sodium acrylate) showing high water uptake

Water-swellable rubber (WSR) comprises super absorbent polymer (SAP) embedded in a rubber matrix and has been commonly used as sealants and caulks, in which high water uptake and sufficient mechanical strength are required. In this work, we investigated the swelling behavior and mechanical properties of rubber composites comprising SAP powders. A reinforcement effect is caused by the SAP particles, which are described using a modified Guth–Gold equation up to the semi-dilute region. The complex modulus shows upper deviation at high SAP content owing to network formation between SAP particles. The swelling force of the WSR is explained by the amount of SAP particles in the surface layer of the matrix up to the semi-dilute region. The formation of the SAP network leads to an appreciable increase in the swelling force of WSR, as SAP particles embedded in the matrix also contribute to the swelling of WSR. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48535.     

Morphology and mechanical properties in the binary blends of isotactic polypropylene and novel propylene-co-olefin random copolymers with isotactic propylene sequence 1. Ethylene-propylene copolymers

The additive effects of the novel ethylene-propylene random (EP) copolymers with high isotacticity in propylene sequence on the morphology and mechanical properties of isotactic polypropylene (iPP) were investigated using polarized optical microscopy, transmission electron microscopy, dynamic mechanical analysis and tensile behavior. According to these results, the EP copolymers with a propylene content of more than 84 mol% were miscible with iPP, in which the crystallizable PP sequences in these EP copolymers were incorporated in crystal lattice of iPP and the other portions in the EP chains were excluded to the amorphous phases. Consequently, they act as tie molecules linking between adjacent lamellae, leading to enhancement of yield toughness of iPP. On the other hand, the EP copolymers with a propylene-unit content of less than 77 mol% were incompatible with iPP. The iPP/EP blends showed the phase-separated morphology.     

A high-dynamic-range CMOS image sensor for automotive applications

In this paper, a 256×256 pixel CMOS imager is described that exhibits 120 dB dynamic range, 56 dB signal-to-noise ratio (SNR), 65% fill factor, and an effective frame rate of 50 Hz. This has been achieved using a unique combination of a multiexposure and a multigain linear readout. The imager has been integrated in 1 μm double-metal CMOS technology. The intended application is for driver's assistant systems, but the imager can be used for a wide range of applications requiring high dynamic range     

Comparison of tensile properties in the pre-yield region of metallocene-catalyzed and Ziegler-Natta-catalyzed linear polyethylenes

The mechanical nonlinear behaviour of metallocene- and Ziegler-Natta catalyzed polyethylenes with various contents of short chain branching was investigated using a nonlinear constitutive equation in which the plastic deformation and the anharmonicity of elastic response are taken into account. It is suggested that the mechanical behaviour is governed by the plastic deformation for the Ziegler-Natta catalyzed polyethylenes, whereas the anharmonicity strongly affects the mechanical behaviour for metallocene-catalyzed polyethylenes.     

Calorimetric study of mutant human lysozymes with partially introduced Ca2+ binding sites and its efficient refolding system from inclusion bodies

During the process of evolution, ancestral lysozymes evolved intocalcium-binding lysozymes by acquiring three critical aspartate residues atpositions 86, 91 and 92. To investigate the process of the acquisition ofcalcium-binding ability, two of the aspartates were partially introducedinto human lysozyme at positions 86, 91 and 92. These mutants (HLQ86D,HLA92D and HLQ86D/D91Q/A92D), having two critical aspartates incalcium-binding sites, were expressed in Escherichia coli as non-activeinclusion bodies. For the preparation of lysozyme samples, a refoldingsystem using thioredoxin was established. This system allowed for effectiverefolding of wild-type and mutant lysozymes, and 100% of activity wasrecovered within 4 days. The calcium ion dependence of the meltingtemperature (Tm) of wild-type and mutant lysozymes was investigated bydifferential scanning calorimetry at pH 4.5. The Tm values of wild-type,HLQ86D and HLA92D mutants were not dependent on calcium ion concentration.However, the Tm of HLQ86D/D91Q/A92D was 4 degrees higher in the presence of50 mM CaCl2 than in its absence, and the calcium-binding constant of thismutant was estimated to be 2.25(+/-0.25)x10(2) M(-1) at pH 4.5. Moreover,the calcium-binding ability of this mutant was confirmed by the resultusing Sephadex G-25 gel chromatography. These results indicate that it isindispensable to have at least two aspartates at positions 86 and 92 foracquisition of calcium-binding ability. The process of the acquisition ofcalcium-binding site during evolution of calcium-binding lysozyme isdiscussed.     

Energetics of three-state unfolding of a protein: canine milk lysozyme

Thermodynamics of thermal transitions of a calcium-binding lysozyme,canine milk lysozyme (CML), was studied using differential scanningcalorimetry and compared with those for homologous proteins,human     

Automated flow quantification for spin labeling MR imaging

Objective

The Time-Spatial Labeling Inversion Pulse (Time-SLIP) technique enables tracing of regional fluid flows without the use of contrast medium. The objective of this study is to quantify automatically slow and complex fluid flows using the Time-SLIP technique.

Materials and methods

Series images were acquired with a 1.5-T MRI scanner using the Time-SLIP technique with half-Fourier fast spin-echo (FSE) and balanced steady-state free precession (bSSFP) sequences. In this method, labeled fluid regions in images were automatically detected based on image processing techniques for a given point. The flow velocity of the labeled fluid region was calculated using regression fitting for the region’s position. To evaluate our method, constant and non-constant laminar flows in a water phantom were studied. In addition, volunteer experiments were conducted to quantify the flow of cerebrospinal fluid.

Results

In the constant flow experiments the correlation factor r ² between the flow velocity calculated from our method and the laminar peak velocity calculated from the volumetric flow rate was 0.9992 for the FSE sequence and 0.9982 for the bSSFP sequence. In the non-constant flow study, the flow velocity was calculated accurately for any period inversion time even when the flow velocity was changed, and the quantification error was negligible. In the volunteer experiments, r ² between the flow velocity calculated by the proposed method and that obtained by manual annotation was 0.9383.

Conclusion

The experimental results showed that our proposed method can quickly and accurately provide information on flow velocities especially for slower and complex flows. Our method is, therefore, expected to be useful in diagnostic support systems.     

Carrier transport properties in highly ordered smectic liquid crystal phase

We have designed and synthesized a new liquid crystalline phenylbenzothienobenzothiphene derivative, Ph‐BTBT‐4S‐3, in order to investigate the carrier transport properties in highly ordered smectic liquid crystal phase at a wide temperature range lower than room temperature enough to analyze them. Ph‐BTBT‐4S‐3 exhibits smectic E (SmE) phase, which is the one of highly ordered smectic liquid crystal phases, at the wide temperature range from 200°C to under ?130°C. Thanks to its wide temperature range of SmE phase, we could reveal the carrier transport properties in the low temperature range, which were well explained on the basis of Gaussian disorder model having a Gaussian width, σ, of 87 meV, which was larger than those of typical nonpolar liquid crystals of 40?60 meV and was attributed to additional dipole of a thioether group in the side chain.     

Effect of pore size distribution on compressive behavior of moderately expanded low‐density polyethylene foams

We investigated the effect of the pore size distribution on the compressive behavior for moderately expanded elastic polymer foams. Unlike well‐expanded foams, moderately expanded foams have heterogeneous cellular structures and their mechanical properties can depend on the heterogeneity of cellular structures. To clarify the effect of the pore size distribution on mechanical properties, we prepared a series of low‐density polyethylene (LDPE) foams with different pore size distributions and relative densities as models of moderately expanded elasitc polymer foams. We performed the microscope observations and the uniaxial compression tests of the moderately expanded LDPE foams. The compressive behavior of a foam was primarily determined by the relative density, but we found that the compressive behavior also depends on the pore size distribution, especially in the collapse region. In the collapse region, the compressive stress–strain curves showed clear dependence on the heterogeneities of cellular structures. The broader cell distribution resulted in the stronger strain dependence of the stress in the collapse region. We show that we can reasonably predict the compressive stress–strain curves from the pore size distributions. POLYM. ENG. SCI., 59:510–518, 2019. © 2018 Society of Plastics Engineers