Vital parameters for high gamma-aminobutyric acid (GABA) production by an industrial soy sauce koji Aspergillus oryzae NSK in submerged-liquid fermentation

Food Science and Biotechnology - In submerged-liquid fermentation, seven key parameters were assessed using one-factor-at-a-time to obtain the highest GABA yield using an industrial soy sauce koji...     

Morphology and property changes in PLA/PHBV blends as function of blend composition

PLA/PHBV blends were prepared by melt mixing. The morphology and physical properties of the blends and neat polymers were investigated. Scanning electron microscopy (SEM) studies provided evidence of interfacial cavities and weak interfacial interaction between the two polymers, and no obvious co-continuous morphology was observed in any of the investigated blends. Positron annihilation lifetime spectroscopy (PALS) indicated the presence of open-volume cavities with sub-nanometre diameters; far smaller than observed from the SEM images. The mean size and relative concentration of these cavities increased with increasing PHBV content. A weak negative deviation in the mean size for low PHBV content possibly indicates some degree of partial miscibility. The glass transition temperature of PLA in the blends decreased with increasing PHBV content, and offers support to some PHBV being miscible with the PLA. The degree of crystallinity in the blends show interesting behaviour that may be explained in terms of the complex morphology observed for these blends. The thermal conductivity of the samples varied with composition, but increased with increasing PHBV content, which was probably related to the increasing crystallinity. Both the tensile strength and Young’s modulus decreased with increasing PHBV content for the sequence of blends, and both parameters exhibited maximum values for 10 wt.% PHBV. For samples between 50/50 and 10/90 PLA/PHBV the tensile strength and Young’s modulus were comparable to or lower than those for both the neat polymers.     

One-line measurement of the residence time distribution in screw extruders

A fluorescence monitoring device was constructed to measure in real time the residence time distribution (RTD) function in screw extruders. Its centerpiece was an optical fiber probe capable of transmitting optical excitation energy to the processed flow stream and detecting the subsequent fluorescence emission. The source of fluorescence emission was an anthracene-bearing substance that was injected to the flow stream as a pulse (tracer) in very small amounts. This device was validated against an off-line ultraviolet spectrophotometer and self-checked as well. In addition to its great sensitivity to fluorescence emission and ease of implementation on an extrusion line, this device could be used to monitor in real time subtle variations of an extrusion operation. The influence of the nature of anthracene-bearing compounds on the measured distribution and the effects of processing parameters on the RTD function were also investigated.     

Arabic stop consonants characterisation and classification using the normalized energy in frequency bands

In general, speech is made with sequences of consonants (fricatives, nasals and stops), vowels and glides. The classification of the stop consonants remains one of the most challenging problems in speech recognition. In this paper, we propose a new approach based on the normalized energy in frequency bands in the release and closure phases in order to characterize and classify the Arabic stop consonants (/b/, /d/, /t/, /k/ and /q/) and to recognize the CV syllable. Classification experiments were performed using decision algorithms on stop consonants C and CV syllables extracted from an Arabic corpus. The results yielded to an overall stop consonants classification of 90.27% and syllables CV recognition upper than 90% for all stops.     

Anti-Corrosive Properties of (1-benzyl-1H-1,2,3-triazol-4-yl) Methanol on Mild Steel Corrosion in Hydrochloric Acid Solution: Experimental and Theoretical Evidences

Protection of Metals and Physical Chemistry of Surfaces - The corrosion inhibitory effect of (1-benzyl-1H-1,2,3-triazol-4-yl) methanol (BTM) for mild steel in 1 M HCl at (298–328 K) was...     

Preparation of macromolecular tracers and their use for studying the residence time distribution of polymeric systems

In this study, an easy route was developed to incorporate antracene moieties in polymer chains. It consisted of copolymerizing the monomer of a polymer of interest with 3-isopropenyl-α, α'-dimethylbenzyl isocyanate (TMI) and then reacting the isocyanate-bearing polymer with 9-(methylamino-methyl)anthracene. Such an antracene-bearing polymer was then used as a tracer (macrotracer) to determine the RTD function of polymers in a twin screw extruder and compared with an antracene as a microtracer. As long as the tracers were well mixed with a polymer of interest and the resulting mixture had the same geometrical form as the polymer before they were charged to the flow stream, the differences between the microtracer and the macrotracer were not reflected in the measured RTD distribution. A variation in the feed rate (Q) or screw speed (N) changes both the RTD and the intensity of axial mixing. On the other hand, for a given but small Q/N, commonly called specific throughput, variations in Q and N change the RTD but not the intensity of axial mixing. When it is small, Q/N can be used as an operating parameter to separate the effect of the residence time from that of mixing for a small Q/N.     

基于RBF网络的自适应熔焊插补容错算法

为使非均匀有理B样条插补(NURBS插补)过程中速度变化平稳,设计了一种步长可控的实时插补算法. 推导了参数曲线的一般求值方法,并通过递推矩阵快速计算,能够根据曲线形状的变化,主动调整加工速度,并通过速度再修正模块保证微段曲线中加速度恒定,在满足机床启停能力的基础上平稳加工. 将径向基网络(RBF)和模糊控制相结合,实时筛选故障参数进行再训练,并编写可视化软件进行成形试验,对成形质量、成形速度加速度和预测精度进行分析评价. 试验结果表明,该算法与RBF网络和模糊控制相配合,能够在保证成形精度和设备稳定性的基础上使软件具有一定的容错能力.     

New process for catalyst-free biodiesel production using subcritical acetic acid and supercritical methanol

The production of glycerol as a by-product is unavoidable in the current conventional biodiesel manufacturing processes. Since biodiesel production is expected to increase in the near future, effective utilization of glycerol will become an issue of interest. In this study, therefore, a process consisting of subcritical acetic acid treatment to convert rapeseed oil to fatty acids and triacetin followed by conversion of the obtained fatty acids to their fatty acid methyl esters in supercritical methanol treatment was investigated. The obtained results clearly revealed that this two-step reaction could proceed effectively at a high reaction rate, and that fatty acid methyl esters and triacetin could be obtained under milder reaction condition than the one-step process utilizing supercritical methyl acetate and supercritical methanol.     

Impact Resistance of Annealed Glass Panels

Annealed glass is by far the most commonly used glazing material in building construction. The resistant properties of glazing panels to wind loading has been studied for a long time based on quasistatic modeling. More recently, the vulnerability of infrastructure and its protection against acts of terrorism has been receiving a great deal of attention, as pioneered by the work of Wu and Hao from within Australia, whereas vulnerability studies by Stewart were specific to glass fa?ades in terrorism scenarios. Emphasis has been on modeling the blast induced pressure and impulses, as they are applied to the panels while the resistant properties of the glazing materials have been based on assumptions used currently in design. Research undertaken by the writers over the past two to three?years have revealed scopes of possible improvements to the current models that have been used in defining the resistant properties of glazing materials. Models based on the well known Weibull distribution, although widely assumed in practice, have been found to be not fully consistent with evidence produced experimentally or by analytical simulations. The interaction of the principal stresses surrounding the crack tip and higher mode effects have also been found to have significant effects on the ultimate behavior of the panel. The accurate modeling of these phenomena is particularly important for large panels. This paper provides an update of the redevelopment of a realistic behavioral model for annealed glazing panels subject to impact action. A new simulation procedure that takes various described phenomena into account is presented in this paper.