Flower Extracts and Their Essential Oils as Potential Antimicrobial Agents for Food Uses and Pharmaceutical Applications

Abstract: Plants with potential therapeutic value have been used from time immemorial to cure various ailments and infectious diseases. Secondary metabolites or the bioactive compounds (phytochemicals) present in plants have been reported to be accountable for various observed biological activities. Consumer awareness of the possible side effects of using chemical‐based antimicrobial agents has forced researchers to identify and explore natural plant‐based antimicrobial agents (or preservatives) that are toxicologically safe, especially when used in food applications. Of late, scientific evidence has been provided on the potential antimicrobial activities exhibited by certain traditionally used flower extracts or their essential oils (edible and wild). This review focuses on providing and updating available information on the antimicrobial activities exhibited by flowers, which are envisaged to find potential applications as natural preservatives for foods or applications in the pharmaceutical industries to develop new and economical herbal‐based products for treating various diseases.     

In vitro degradation behavior of M1A magnesium alloy in protein-containing simulated body fluid

Magnesium alloys possess unique advantages to be used as biodegradable implants for clinical applications. In this study, in vitro cells responses and degradation behaviors of magnesium alloy M1A in simulated body fluid (SBF) and albumin-containing SBF (A-SBF) were systematically investigated. Cell responses, in terms of Cell morphology and cell proliferation, imply that M1A possesses good viability for MG63 cells. The corrosion behaviors of M1A are strongly affected by the addition of albumin through the combined effects of adsorption and chelation. Electrochemical testing indicates that such an absorbed albumin layer makes M1A to be more noble with a smaller corrosion current. Corrosion rate monitored by hydrogen evolution rate suggests that the quickly adsorbed albumin serves as an effective protective layer, resulting in a much slower hydrogen release rate at initial stage. With increasing immersion time, a higher corrosion rate is observed since the chelation effect exerts more significant acceleration effects on the removal of the passivation layer. The corrosion mode evaluated by surface morphology of the samples changes from a nonuniform-anisotropic mode for M1A in SBF to a uniform-isotropic mode for M1A in A-SBF.     

Wave propagation velocities in integrated PLS based control of a simulated moving bed process

The simulated moving bed (SMB) is a continuous chromatography process for separation of chemical mixtures. It has been used in large-scale industrial production of cheap specialty products like sugar separation, as well as small-scale production of high value products like enantiomer separation in the pharmaceutical industry. Physical models can be employed in control of SMB processes, but it can be difficult to obtain accurate physical parameters. Empirical models do away with the need to obtain parameters, but without physical representation, they may not be suitable for control applications. In this research paper, wave propagation is linked with the empirical model to enhance the physical constraint on designing SMB. However, there is an interaction between the zonal wave velocities and process outputs; thus, control strategies based on the partial least squares (PLS) are proposed in this work. PLS decoupling of the system to achieve pairs of SISO (single input single output) in the subspace is useful because the conventional SISO can be directly applied to the control design. The use of wave propagation allows the application of the constraints in Zones II and III based on the shifting of the wave fronts. Two modes of control are proposed: cycle to cycle and within cycle. The performance of these control strategies is assessed by implementation on a virtual eight-column SMB unit for set-point tracking and disturbance rejection.     

The influence of die geometry and workpiece mechanical properties in T-Shape friction test

In this study, T-Shape friction test was redesigned to make it more suitable for application to microforming processes. Workpiece with aspect ratio (length/diameter) of 5 was proposed in order to ease workpiece handling. The die geometry was also modified from the original test to improve friction sensitivity especially within the range of friction factors commonly observed in metal forming. Geometric deviation of the die was simulated using Deform-2D to establish the acceptable tolerance for the fabrication. The effect of variation in workpiece mechanical properties on the test behavior was also investigated through Deform-2D simulation. Based on simulations on a 1 mm diameter copper workpiece, a tolerance of 0.01 mm (1% of workpiece diameter) was found to be the most suitable for the die fabrication. In addition, it was shown that variations in workpiece mechanical properties of up to 10% do not significantly influence the friction test results. Ultimately, T-Shape test experiment was conducted using copper workpieces to examine how the test complied with the friction behavior observed in the experiment.     

采用CoolSETTM-ICE2B265的30W开关电源设计

引言 CoolSETICE2B265是内带CoolMOS的集成脉宽调制器.它含有控制器和CoolMOS功率开关,价格便宜.设计者可以用它来实现当前各种新型开关电源,例如要求待机功耗低、外部元件少,电路板面积最小等等.     

The modeling and determination of dynamic elastic modulus of magnesium based metal matrix composites

The aim of the present study was to determine elastic modulus of the magnesium-based composites containing different volume fraction of SiC particulates using an innovative free-free beam type impact based technique. This technique is based on classical vibration theory, by which the geometry and material properties of the metal matrix composites are related to resonant frequency of the test specimen. With the fundamental resonant frequency obtained from the experiment and density determined by the Archimedes' principle, the elastic modulus values were determined. In addition, a finite element model is proposed for different SiC weight percentage samples for the determination of dynamic elastic modulus using the first natural frequency corresponding to the flexural mode. The elastic modulus values obtained using finite element method were found to be in close agreement with the values obtained from the impact based experiments and in better agreement when compared to theoretical methods such as Halpin-Tsai method. Both the theoretical approaches, in common, exhibit the increasing trend of elastic modulus value with an increase in weight percentage of SiC particulates.     

Intersubband optics in parabolic quantum dots

The infrared intersubband optical properties of parabolic cylinder and parabolic rotational quantum dots are studied using a single-band effective-mass theory. This allows us to study the impact of shape and size on the transition energies and polarization selection rules. Contrary to earlier work on spheroidal dots, we predict that the change in the polarization of intersubband optical transitions as a function of the parabolic quantum dot height and cross section is here due to level crossing.