Sugar palm fiber/polyester nanocomposites: Influence of adding nanoclay fillers on thermal,dynamic mechanical,and physical properties

In this research, nanoclay used as filler in sugar palm‐reinforced composites was investigated by the physical, thermal, and dynamic mechanical properties. Various concentrations of nanoclay were used to fabricate composites by using hand lay‐up technique, followed by hot compression molding with naturally woven sugar palm fiber‐reinforced in polyester matrix. Among various weight concentrations such as 1–5% of nanoclay, it was found that 2% nanoclay‐filled composite (NC) demonstrated the best balance of thermomechanical properties and significantly enhanced the composite. DMA demonstrated that 2% nanoclay content resulted in improved viscoelastic behavior and higher glass transition temperature (T_g) of the composites. TGA also showed improvement in properties, whereas 3% nanoclay‐filled composite showed superior onset temperature, and 5% nanoclay‐filled composite exhibited highest remaining residue. The nanoclay filler was very effective to fill the porous structure and maintain the thickness stability. The thickness swelling was reduced with increasing amount of nanoclay in composites. Overall, the addition of nano clay improved thermal and physical properties of sugar palm‐reinforced polyester composite. J. VINYL ADDIT. TECHNOL., 26:236–243, 2020. © 2019 Society of Plastics Engineers     

Natural and Synthetic Macrocyclic Inhibitors of the Histone Deacetylase Enzymes

Inhibition of histone deacetylase (HDAC) enzymes has emerged as a target for development of cancer chemotherapy. Four compounds have gained approval for clinical use by the Food and Drug Administration in the US, and several are currently in clinical trials. However, none of these compounds possesses particularly good isozyme selectivity, which would be a highly desirable feature in a tool compound. Whether selective inhibition of individual HDAC isozymes will provide improved drug candidates remains to be seen. Nevertheless, it has been speculated that using macrocyclic compounds to target HDAC enzymes might hold an advantage over the use of traditional hydroxamic‐acid‐containing inhibitors, which rely on chelation to the conserved active‐site zinc ion. Here we review the literature on macrocyclic HDAC inhibitors obtained from natural sources and on structure–activity relationship studies inspired by these molecules, as well as on efforts aimed at fully synthetic macrocyclic HDAC inhibitors.     

Effects of kenaf contents and fiber orientation on physical,mechanical, and morphological properties of hybrid laminated composites for vehicle spall liners

The aim of this work is to study the effect of kenaf volume content and fiber orientation on tensile and flexural properties of kenaf/Kevlar hybrid composites. Hybrid composites were prepared by laminating aramid fabric (Kevlar 29) with kenaf in three orientations (woven, 0^o/90^o cross ply uni‐directional (UD), and non‐woven mat) with different kenaf fiber loadings from 15 to 20% and total fiber loading (Kenaf and Kevlar) of 27–49%. The void content varies between 11.5–37.7% to laminate with UD and non‐woven mat, respectively. The void content in a woven kenaf structure is 16.2%. Tensile and flexural properties of kenaf/Kevlar hybrid composites were evaluated. Results indicate that UD kenaf fibers reinforced composites display better tensile and flexural properties as compared to woven and non‐woven mat reinforced hybrid composites. It is also noticed that increasing volume fraction of kenaf fiber in hybrid composites reduces tensile and flexural properties. Tensile fracture of hybrid composites was morphologically analysed by scanning electron microscopy (SEM). SEM micrographs of Kevlar composite failed in two major modes; fiber fracture by the typical splitting process along with, extensive longitudinal matrix and interfacial shear fracture. UD kenaf structure observed a good interlayer bonding and low matrix cracking/debonding. Damage in composite with woven kenaf shows weak kenaf‐matrix bonding. Composite with kenaf mat contains the high void in laminates and poor interfacial bonding. These results motivate us to further study the potential of using kenaf in woven and UD structure in hybrid composites to improve the ballistic application, for example, vehicle spall‐liner. POLYM. COMPOS., 36:1469–1476, 2015. © 2014 Society of Plastics Engineers     

Residual amylopectin structures of amylase-treated wheat starch slurries reflect amylase mode of action

Some amylases can delay bread staling and/or starch (amylopectin) retrogradation, but the molecular basis of this effect remains little understood. In order to increase our insight in these aspects of amylase functionality, several amylases were added in a pure wheat-starch-containing model system and subjected to a heating step corresponding to that in the baking phase in bread making. Next, the effects of the limited amylolytic degradation on the rapid visco analyser (RVA) rheological properties of starch were studied and the accompanying changes in the amylopectin molecular properties (such as chain length distribution) investigated. The different amylases clearly affected the molecular structure of amylopectin to a different extent, which could be related to their mode of action and the enzyme activity levels added. Bacillus subtilis and Aspergillus oryzae α-amylases had only a limited impact on the side chain distribution of the amylopectin molecules, presumably due to their preferential hydrolysis of internal chain segments and the low enzyme activity added in the RVA. In contrast, porcine pancreatic α-amylase and Bacillus stearothermophilus maltogenic α-amylase, both with higher degree of multiple attack and used at higher enzyme activity levels, had a marked influence on the amylopectin molecular structure. More in particular, under the test conditions, the maltogenic α-amylase reduced the average chain length of the outer chains by 50%. Presumably, this will affect amylopectin retrogradation to a large extent. The results contribute to a better understanding of amylase functionality in starchy foods.     

Experimental Characterization of Space Charge in IZIP Detectors

Interleaved ionization electrode geometries offer the possibility of efficient rejection of near-surface events. The CDMS collaboration has implemented this interleaved approach for the charge and phonon readout for our germanium detectors. During a recent engineering run with negligible ambient radiation, the detectors were found to lose ionization stability more quickly than expected. This paper summarizes studies done in order to determine the underlying cause of the instability, as well as possible running modes that maintain stability without unacceptable loss of livetime. Additionally, first results are shown for the new version IZIP mask which attempts to improve the overall stability of the detectors.     

Validation of Phonon Physics in the CDMS Detector Monte Carlo

The SuperCDMS collaboration is a dark matter search effort aimed at detecting the scattering of WIMP dark matter from nuclei in cryogenic germanium targets. The CDMS Detector Monte Carlo (CDMS-DMC) is a simulation tool aimed at achieving a deeper understanding of the performance of the SuperCDMS detectors and aiding the dark matter search analysis. We present results from validation of the phonon physics described in the CDMS-DMC and outline work towards utilizing it in future WIMP search analyses.     

Geant4 Simulations of the SuperCDMS iZIP Detector Charge Carrier Propagation and FET Readout

The SuperCDMS experiment aims to directly detect dark matter particles called WIMPs (weakly interacting massive particles). The detectors measure phonon and ionization energy due to nuclear and electron recoils from incident particles. The SuperCDMS Detector Monte Carlo group uses Geant4 to simulate electron-hole pairs ( \(e^-/h^+\) ) and low temperature phonons. We use these simulations in order to study energy deposition in the detectors. Phonons and electron-hole pairs are tracked in a crystal detector. Because of the band structure of the crystals, the electrons undergo oblique propagation. The charge electrodes on each side of the detector are biased at different voltages while the phonon sensors are grounded. This creates a nearly uniform electric field through the bulk of the detector, with a complex shape near the surfaces. The electric field is calculated from interpolating on a tetrahedral mesh. The resulting TES phonon readout, as well as the FET charge readout are simulated. To calculate the FET readout, the Shockley-Ramo theorem is applied to simulate the current in the FET. The goal of this paper is to describe the theory and implementation of calculating the electric field, performing the charge carrier propagation, and simulating the FET readout of the SuperCDMS detectors.     

USSR State Standards Commission precision time-standard synchronization system based on meteor radar

Translated from Izmeritel'naya Tekhnika, No. 4, pp. 22–24, April, 1989.     

Simulations of Noise in Phase-Separated Transition-Edge Sensors for SuperCDMS

We briefly review a simple model of superconducting-normal phase-separation in transition-edge sensors (TESs) in the SuperCDMS experiment. After discussing some design considerations relevant to the TESs in the experiment, we study noise sources in both the phase-separated and phase-uniform cases. Such simulations will be valuable for optimizing the critical temperature and TES length of future SuperCDMS detectors.     

Video-assisted thoracoscopic repair of an intercostal pulmonary hernia

Pulmonary hernias are extremely rare. They are usually treated with open surgical procedures. We describe a case in which a large, spontaneously acquired intercostal pulmonary hernia was successfully repaired by video-assisted thoracoscopic surgery (VATS).