Purification and properties of β-amylase produced by bacillus polymyxa

1,4-α-D -glucan maltohydrolase (β-amylase, EC.3.2.1.2.) produced by Bacillus polymyxa was isolated and purified. Some of its properties were examined and compared with those of a typical plant β-amylase. Hydrolysis of periodate oxidised amylose demonstrated an exo mechanism of substrate attack similar to that of sweet potato β-amylase. The effect of sulphydryl reagents on enzyme activity was similar to that reported for plant β-amylases. Consistent with the observation that the enzyme has an exo mechanism of action, it also failed to degrade Schardinger cyclodextrins. These latter compounds acted as inhibitors of the enzyme. The optimum temperature for activity was 37 °C. The enzyme was quite stable at temperatures up to and including 37 °C; 90% of the original activity remained after storage at 37 °C for 6 days. However, the stability decreased rapidly when exposed to temperatures above 37 °C; only 20% of the activity remained after 1 h at 45 °C. The hydrolase exhibited a rather sharp optimum at pH 6.8 for stability at 37 °C. However, the enzyme was quite stable in the pH range 6.4–7.2 at 20 °C but it was shown to be less stable in acidic conditions than the corresponding plant enzymes.     

Validation of the MEDFICTS dietary questionnaire: A clinical tool to assess adherence to American Heart Association dietary fat intake guidelines

Background  

Dietary assessment tools are often too long, difficult to quantify, expensive to process, and largely used for research purposes. A rapid and accurate assessment of dietary fat intake is critically important in clinical decision-making regarding dietary advice for coronary risk reduction. We assessed the validity of the MEDFICTS (MF) questionnaire, a brief instrument developed to assess fat intake according to the American Heart Association (AHA) dietary "steps".     

Seeded Growth from Twinned and Untwinned Abnormal Grains of Pb(Mg1/3Nb2/3)O3–35 mol% PbTiO3 in a Matrix Containing PbO Additions

The growth of abnormal grains of PMN–35PT containing Σ3 twin boundaries was compared with that of untwinned abnormal grains of PMN–35PT. It was thought that the twinned abnormal grains might have a growth advantage because of the presence of reentrant edges. The aforementioned types of grains were embedded in a PMN–35PT polycrystalline matrix with 3 vol% excess PbO, and grown by annealing in an oxygen atmosphere at 1150°C for varying times. It was found that abnormal grains containing Σ3 boundaries showed a comparable degree of growth to that of the untwinned grains. Furthermore, for the twinned seed crystals, the extent of growth was independent of whether there was any initial entrapped porosity within the abnormal grain.     

Fiber Single-Crystal Growth from the Melt for Optical Applications

The micro-pulling-down technique has been applied to produce undoped and 0.1% Nd³⁺-doped Y₃Al₅O₁₂ garnet single-crystal fibers with controlled diameter. The hot zone construction and fiber-pulling conditions have been optimized. As a result, growth of transparent and homogeneous fiber crystals has been achieved. The crystals have been grown under 10⁵ Pa (1 atm) of argon atmosphere, with the pulling rate varied in the range of 0.3–2.0 mm/min. One hundred percent of the starting melt has been normally transformed into a crystalline material, with an empty crucible ready for the next growth procedure. The as-produced fibers demonstrate promising optical properties.     

Adaptive wavelet transform for vibration signal modelling and application in fault diagnosis of water hydraulic motor

There has been an increasing application of water hydraulics in industries due to growing concern on the environmental, health and safety issues. The fault diagnosis of water hydraulic motor is important for improving water hydraulic system reliability and performance. In this paper, fault diagnosis of water hydraulic motor in water hydraulic system is investigated based on adaptive wavelet analysis. A novel method for modelling the vibration signal based on the adaptive wavelet transform (AWT) is proposed. The linear combination of wavelets is introduced as wavelet itself and adapted for the particular vibration signal, which goes beyond adapting parameters of a fixed-shape wavelet. The AWT procedure based on the parametric optimisation by genetic algorithm (GA) is developed. The model-based method by AWT is applied to extract the features in the fault diagnosis of the water hydraulic motor. This technique for de-noising the corrupted simulation signal shows that it can improve the signal-to-noise ratio of the vibration signal. The results of the experimental signal demonstrate the characteristic vibration signal details in fine resolution. The magnitude plots of the continuous wavelet transform (CWT) show the characteristic signal's energy in time and frequency domain which can be used as feature values for fault diagnosis of water hydraulic motor.     

Characterizing plasma mirrors near breakdown

Experiments dedicated to the characterization of plasma mirrors with a high energy, single shot short-pulse laser were performed at the 100 TW target area of the Z-Backlighter Facility at Sandia National Laboratories. A suite of beam diagnostics was used to characterize a high energy laser pulse with a large aperture through focus imaging setup. By varying the fluence on the plasma mirror around the plasma ignition threshold, critical performance parameters were determined and a more detailed understanding of the way in which a plasma mirror works could be deduced. It was found, that very subtle variations in the laser near field profile will have strong effects on the reflected pulse if the maximum fluence on the plasma mirror approaches the plasma ignition threshold.     

Valorization of waste thermoset material as a filler in thermoplastic: Mechanical properties of phenolic molding compound waste‐filled PP composites

As most thermoset material, phenolic molding compound (PMC) wastes are an environmental problem. Very few recycling solutions have been proposed so far for this type of material. A mechanical recycling method to valorize these materials is proposed in this work. It relies on the use of phenolic waste as filler in thermoplastic. Such phenolic filler can increase mechanical properties (tensile, flexural) of the matrix, and be used in substitution of traditional particulate fillers such as calcium carbonate or talc. In this study, several morphological parameters influencing the final mechanical properties of a PMC‐filled polypropylene (PP) micro‐composite are studied, such as filler loading rate, particles size distribution of the filler, and interfacial adhesion between the filler and the matrix. Some structural parameters are also studied and linked with mechanical properties, such as dispersion of the filler and crystallinity of the matrix. Finally, the properties of PMC‐filled PP are compared with CaCO₃‐ and talc‐filled PP. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45849.     

Synthesis,Bioassays and Field Evaluation of Hydroxycoumarins and their Alkyl Derivatives as Repellents or Kairomones for <Emphasis Type="Italic">Aedes albopictus</Emphasis> Skuse (Diptera: Culicidae)

In recent years, a significant increase in mosquito-borne diseases has been recorded worldwide. Faced with the limitations of existing methods for controlling the vector mosquito population, the development of attractants to bait traps and repellents to limit host-vector contacts could be promising and environmentally-friendly control strategies. The purpose of this study was to evaluate the effect of hydroxycoumarins and their alkyls derivatives against Aedes albopictus, the main vector of several arboviruses. Synthesis, bioassays and field trials were carried out in Madagascar. The results showed that 3, 4 and 6-hydroxycoumarins are attractive to this mosquito, 4-hydroxycoumarin being the most effective both in the laboratory and under field conditions. In addition, a good synergistic effect was found with octenol to attract mosquitoes and especially Ae. albopictus in comparison to other mosquito species living in sympatry. On the contrary, the 4-s-butoxycoumarin and 4-s-pentoxycoumarin derivatives had a repellent effect with the former showing the most significant effect. Further optimization of the dose and structure of these products will be carried out in order to maximize their utility for the control of Ae. albopictus and other mosquitoes.     

3D Printed Stem‐Cell Derived Neural Progenitors Generate Spinal Cord Scaffolds

A bioengineered spinal cord is fabricated via extrusion‐based multimaterial 3D bioprinting, in which clusters of induced pluripotent stem cell (iPSC)‐derived spinal neuronal progenitor cells (sNPCs) and oligodendrocyte progenitor cells (OPCs) are placed in precise positions within 3D printed biocompatible scaffolds during assembly. The location of a cluster of cells, of a single type or multiple types, is controlled using a point‐dispensing printing method with a 200 µm center‐to‐center spacing within 150 µm wide channels. The bioprinted sNPCs differentiate and extend axons throughout microscale scaffold channels, and the activity of these neuronal networks is confirmed by physiological spontaneous calcium flux studies. Successful bioprinting of OPCs in combination with sNPCs demonstrates a multicellular neural tissue engineering approach, where the ability to direct the patterning and combination of transplanted neuronal and glial cells can be beneficial in rebuilding functional axonal connections across areas of central nervous system (CNS) tissue damage. This platform can be used to prepare novel biomimetic, hydrogel‐based scaffolds modeling complex CNS tissue architecture in vitro and harnessed to develop new clinical approaches to treat neurological diseases, including spinal cord injury.