Phenylalanine Ammonia‐Lyase‐Catalyzed Deamination of an Acyclic Amino Acid: Enzyme Mechanistic Studies Aided by a Novel Microreactor Filled with Magnetic Nanoparticles

Phenylalanine ammonia‐lyase (PAL), found in many organisms, catalyzes the deamination of l ‐phenylalanine (Phe) to (E)‐cinnamate by the aid of its MIO prosthetic group. By using PAL immobilized on magnetic nanoparticles and fixed in a microfluidic reactor with an in‐line UV detector, we demonstrated that PAL can catalyze ammonia elimination from the acyclic propargylglycine (PG) to yield (E)‐pent‐2‐ene‐4‐ynoate. This highlights new opportunities to extend MIO enzymes towards acyclic substrates. As PG is acyclic, its deamination cannot involve a Friedel–Crafts‐type attack at an aromatic ring. The reversibility of the PAL reaction, demonstrated by the ammonia addition to (E)‐pent‐2‐ene‐4‐ynoate yielding enantiopure l ‐PG, contradicts the proposed highly exothermic single‐step mechanism. Computations with the QM/MM models of the N‐MIO intermediates from l ‐PG and l ‐Phe in PAL show similar arrangements within the active site, thus supporting a mechanism via the N‐MIO intermediate.     

Integration of PV system with SMES based on model predictive control for utility grid reliability improvement.

This paper describes the integration of a photovoltaic (PV) renewable energy source with a superconducting magnetic energy storage (SMES) system. The integrated system can improve the voltage stability of the utility grid and achieve power leveling. The control schemes employ model predictive control (MPC), which has gained significant attention in recent years because of its advantages such as fast response and simple implementation. The PV system provides maximum power at various irradiation levels using the incremental conductance technique (INC). The interfaced grid side converter of the SMES can control the grid voltage by regulating its injected reactive power to the grid, while the charge and discharge operation of the SMES coil can be managed by the system operator to inject/absorb active power to/from the grid to achieve the power leveling strategy. Simulation results based on MATLAB/Simulink® software prove the fast response of the system control objectives in tracking the setpoints at different loading scenarios and PV irradiance levels, while the SMES injects/absorbs active and reactive power to/from the grid during various events to improve the voltage response and achieve power leveling strategy.     

Changes in the size and docosahexaenoic acid content of adipocytes during chick embryo development

The development of adipose tissue in the chick embryo was investigated using two groups of fertile eggs which differed by 1.7-fold in their initial yolk lipid levels. The triacylglycerol content of the subcutaneous adipose depot in both groups increased dramatically from day 12 of the 21-day embryonic period, attaining a maximal value just prior to hatching. During this period, the amount of triacylglycerol deposited in the adipose tissue was very highly correlated with the amount of lipid transferred from the yolk. The triacylglycerol content of the depot was also dependent on the initial yolk lipid content. During the hatching period, the amount of adipose triacylglycerol remained approximately constant in the group with the higher initial yolk lipid content but, in the case of the group with the lower initial yolk lipid levels, decreased by approximately 25%. The size distribution of adipocytes isolated from the tissue was determined by computerized image analysis microscopy. The mean adipocyte diameter increased from approximately 6 to 35 μm between days 12 and 19, irrespective of the initial yolk content, although development within the eggs with the lower initial yolk content resulted in a decrease in cell size over the hatching period. Both the triacylglycerol and phospholipid fractions of the isolated adipocytes contained substantial proportions (approximately 6%, w/w) of docosahexaenoic acid (DHA) at days 12 and 14, and lower levels of this fatty acid at the later stages. The amount (mg/depot) of DHA in adipose triacylglycerol decreased dramatically over the hatching period. The amount (mg/brain) of DHA in brain phospholipid increased by more than 5-fold between day 12 of development and hatching. A possible explanation for the data may be that DHA is preferentially mobilized from adipose tissue in order to deliver the fatty acid to the developing neural tissues in a form suitable for uptake.     

使用.NET Framework 2．0安全承载不受信任的外接程序

通过使用动态程序集加载和反射，托竹代码提供了通过外接程序轻松扩展直用程序的方法。但是，当允许应用程序通过外接程序模型运行任意代码时，就将用户计算机暴露在潜住的未知代码之下，有很大风险，恶意代码可能会使用您的应用程序作为进入用户数据的入口点。可以采用若干方法缩小应用程序的攻击面，防止恶意代码或不稳定代码破坏用户计算机——戒者防止敏感数据被窃取。     

Minimum cost design of a cellular plate loaded by uniaxial compression

Cellular plates are constructed from two base plates and an orthogonal grid of stiffeners welded between them. Halved rolled I-section stiffeners are used for fabrication aspects. The torsional stiffness of cells makes the plate very stiff. In the case of uniaxial compression the buckling constraint is formulated on the basis of the classic critical stress derived from the Huber’s equation for orthotropic plates. The cost function contains the cost of material, assembly and welding and is formulated according to the fabrication sequence. The unknown variables are the base plate thicknesses, height of stiffeners and numbers of stiffeners in both directions. The cellular plate is lighter and cheaper than the plate stiffened on one side. The Particle Swarm Optimization and the IOSO techniques are used to find the optimum. PSO contains crazy bird and dynamic inertia reduction criteria, IOSO is based on a response surface technology.     

Quantum dot light emitting devices for photomedical applications

While OLEDs have struggled to find a niche lighting application that can fully take advantage of their unique form factors as thin, flexible, lightweight and uniformly large‐area luminaire, photomedical researchers have been in search of low‐cost, effective illumination devices with such form factors that could facilitate widespread clinical applications of photodynamic therapy (PDT) or photobiomodulation (PBM). Although existing OLEDs with either fluorescent or phosphorescent emitters cannot achieve the required high power density at the right wavelength windows for photomedicine, the recently developed ultrabright and efficient deep red quantum dot light emitting devices (QLEDs) can nicely fit into this niche. Here, we report for the first time the in‐vitro study to demonstrate that this QLED‐based photomedical approach could increase cell metabolism over control systems for PBM and kill cancerous cells efficiently for PDT. The perspective of developing wavelength‐specific, flexible QLEDs for two critical photomedical fields (wound repair and cancer treatment) will be presented with their potential impacts summarized. The work promises to generate flexible QLED‐based light sources that could enable the widespread use and clinical acceptance of photomedical strategies including PDT and PBM.     

Effects of dietary vitamin e supplementation and packaging on the quality of minced beef

Friesian cattle, aged 26-27 months, were fed a diet supplemented with 2000IU α-tocopheryl acetate/kg feed/day and another group was fed a basal diet (20IU/kg feed/day) for approximately 50 days prior to slaughter. Following frozen storage (-20°C for 8 weeks) semimembranosus muscles from basal and α-tocopheryl acetate supplemented cattle were minced and vacuum packaged, aerobically packaged or packaged under modified atmospheres (MAP) (30% O(2): 70% CO(2); 70% O(2): 30% CO(2); 80% O(2): 20% CO(2)). Samples were held under refrigerated (4°C) display (fluorescent lighting, 616 lux) for eight days. Vacuum-packaged samples were held under similar conditions but in complete darkness and allowed to bloom for a minimum of 4hr prior to taking colour readings. TBARS values and Hunter a values in minced beef were measured every two days. α-Tocopherol concentrations were significantly (p<0·05) higher in minced meat samples from the supplemented group than in the basal group. Significant (p<0·05) reductions in α-tocopherol concentrations in supplemented meat samples were observed with increased concentrations of oxygen in different packaging systems after eight days of refrigerated storage. TBARS values were reduced over the whole retail display period for all packaging systems when α-tocopheryl acetate supplemented beef was used. TBARS values increased as oxygen levels increased in MAP. Hunter a values showed that vitamin E supplementation in combination with vacuum packaging and MAP improved the colour stability of meat during the first 4 days of storage, however, the failure of MAP to extend meat colour for longer periods of time was probably the result of prior storage at -20°C for 8 weeks.     

Moving the goal posts: a reply to Dawson and Piercey

Berkeley [Minds Machines 10 (2000) 1] described a methodology that showed the subsymbolic nature of an artificial neural network system that had been trained on a logic problem, originally described by Bechtel and Abrahamsen [Connectionism and the mind. Blackwells, Cambridge, MA, 1991]. It was also claimed in the conclusion of this paper that the evidence was suggestive that the network might, in fact, count as a symbolic system. Dawson and Piercey [Minds Machines 11 (2001) 197] took issue with this latter claim. They described some lesioning studies that they argued showed that Berkeley’s (2000) conclusions were premature. In this paper, these lesioning studies are replicated and it is shown that the effects that Dawson and Piercey rely upon for their argument are merely an artifact of a threshold function they chose to employ. When a threshold function much closer to that deployed in the original studies is used, the significant effects disappear.     

Single Soybean Seed NMR Calibration for Oil Measurement Using Commercial Cooking Oils

Development of high oil soybeans would reduce the cost of soybean oil production for biodiesel or edible oil applications. An accurate determination of soybean seed oil concentration is essential especially when developing superior cultivars with increased seed oil content. The objective of this study was to develop an oil measurement method for single seeds using NMR spectrometry. An NMR spectrometer was calibrated using commercial cooking oil. Fifteen cultivars of known mean oil content were used to evaluate the calibration curves. The calibration curves developed had a correlation coefficient of 0.99. It was found that soybean and corn oil gave identical results over the calibrated interval.     

Betulinic Acid in Complex with a Gamma-Cyclodextrin Derivative Decreases Proliferation and in Vivo Tumor Development of Non-Metastatic and Metastatic B164A5 Cells

Betulinic acid, a very promising anti-melanoma agent, has very low water solubility that causes low bioavailability. To overcome this inconvenience, a highly water-soluble cyclodextrin was used (octakis-[6-deoxy-6-(2-sulfanyl ethanesulfonic acid)]-γ-cyclodextrin). The complex was physico-chemically analyzed using differential scanning calorimetry (DSC), X-ray and scanning electron microscopy (SEM) methods and then in vitro tested for its antiproliferative activity by the MTT assay and by cell cycle analysis. Finally, the complex was tested in vivo using an animal model of murine melanoma developed in C57BL/6J mice, where it caused a reduction in tumor volume and weight. The study revealed the beneficial influence of betulinic acid inclusion into the cyclodextrin in terms of antiproliferative activity and in vivo tumor development.