Asymmetric porous membranes formed by coagulation-induced phase separation in poly(ether sulfone)/poly(vinyl pyrrolidone)/genistein blends

Development of asymmetric channel morphology driven by coagulation-induced phase separation of genistein (G) modified poly(ether sulfone)/poly(vinyl pyrrolidone) (PES/PVP) blends has been examined in relation to their miscibility phase diagram. PES/G pairs turned out to be miscible in the amorphous state, whereas solid–liquid phase separation occurred at high genistein compositions. The solid–liquid phase diagram involving the liquidus and solidus lines were computed self-consistently in the framework of the combined free energy of Flory-Huggins for liquid–liquid phase separation and phase field free energy for crystal solidification. The ternary phase diagram of PES/PVP/G blends was subsequently established that consisted of various coexistence regions. The actual amounts of genistein incorporated in the PES/PVP membranes were determined as a function of weight percent of genistein in feed. On the basis of UV-vis spectroscopy, the extent of genistein leaching during incubation in human blood was evaluated in conjunction with the PVP leaching from the blend membrane.     

Scalable and Selective β-Hydroxy-α-Amino Acid Synthesis Catalyzed by Promiscuous l-Threonine Transaldolase ObiH

Enzymes from secondary metabolic pathways possess broad potential for the selective synthesis of complex bioactive molecules. However, the practical application of these enzymes for organic synthesis is dependent on the development of efficient, economical, operationally simple, and well-characterized systems for preparative scale reactions. We sought to bridge this knowledge gap for the selective biocatalytic synthesis of β-hydroxy-α-amino acids, which are important synthetic building blocks. To achieve this goal, we demonstrated the ability of ObiH, an l -threonine transaldolase, to achieve selective milligram-scale synthesis of a diverse array of non-standard amino acids (nsAAs) using a scalable whole cell platform. We show how the initial selectivity of the catalyst is high and how the diastereomeric ratio of products decreases at high conversion due to product re-entry into the catalytic cycle. ObiH-catalyzed reactions with a variety of aromatic, aliphatic and heterocyclic aldehydes selectively generated a panel of β-hydroxy-α-amino acids possessing broad functional-group diversity. Furthermore, we demonstrated that ObiH-generated β-hydroxy-α-amino acids could be modified through additional transformations to access important motifs, such as β-chloro-α-amino acids and substituted α-keto acids.     

含纳米CeO2,Cu混合物添加剂润滑油摩擦学性能研究

本文中将纳米二氧化铈与铜粒子混合物应用于润滑油添加剂,使润滑油具有优良的减摩、抗磨性能.纳米二氧化铈与铜粒子用适当的表面活性剂进行表面改性处理,经表面改性的纳米粒子在润滑油中具有良好的分散、稳定性.采用透射电镜(TEM)观察与测量纳米二氧化铈、铜粒子的形貌和平均直径.应用四球摩擦磨损试验机测定添加纳米二氧化铈、铜粒子的润滑油的极压性能(PB)、磨痕直径(WSD)和摩擦因数(μ)等.研究结果表明,最佳的纳米二氧化铈、铜粒子的总添加量为0.6%左右、纳米二氧化铈、铜粒子的质量分数之比为1∶1.该润滑油具有最佳的的减摩、抗磨作用.文中还探讨了纳米二氧化铈、铜粒子混合物具有优良摩擦学性能的机理.     

Toughening of thermoset/thermoplastic composites via reaction‐induced phase separation: Epoxy/phenoxy blends

Phase morphology and phase separation behavior of amine‐cured bisphenol‐A diglycidyl ether epoxy and phenoxy mixtures have been investigated by means of time‐resolved small angle light scattering, optical microscopy, and scanning electron microscopy. The starting reactant mixtures composed of epoxy, phenoxy, and curing agents such as diaminodiphenyl sulfone (DDS) and methylene dianiline (MDA) were found to be completely miscible. Upon curing with DDS at 180°C, phase separation took place in various epoxy/phenoxy blends (compositions ranging from 10–40% phenoxy), whereas the MDA curing showed no indication of phase separation. The mechanical and physical properties of single‐phase and two‐phase networks were examined, in that the DDS‐cured epoxy/phenoxy blends having a two‐phase morphology showed improved ductility and toughness without significantly losing other mechanical and thermal properties such as modulus, tensile strength, glass transition and heat deflection temperatures. The energy absorbed to failure during the drop weight impact event was also found to improve relative to those of the single‐phase MDA‐cured blend as well as of the neat epoxy. Such property enhancement of the DDS‐cured blends has been discussed in relation to the two‐phase morphology obtained via scanning electron microscopy micrographs of fractured surfaces. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1257–1268, 2000     

Rheo-optical studies on the deformation mechanism of semi-crystalline polymers. IX. Dynamic birefringence behaviour of a high-density polyethylene film having row nucleated crystalline texture of c-axis orientation

The dynamic birefringence behaviour of a high-density polyethylene film having a row-nucleated crystalline texture of cylindrites oriented along the machine direction of fabrication was investigated over frequency and temperature ranges covering the α mechanical dispersion of this material. The results are discussed in combination with the dynamic X-ray diffraction behaviour of the material so as to explore the structural origins of the α mechanical dispersion, not only for this particular material, but also for bulk-crystallized polyethylene having a spherulitic texture. Two deformation processes contribute to the α₁ mechanism, corresponding to the lower temperature relaxation process in the α mechanical dispersion; i.e. (i) a lamellar detwisting process involving the rotation of crystal grains within the crystal lamellae or of lamellar segments around the crystal b-axis or the lamellar axis, which predominates in the MD (machine direction) specimen, and (ii) lamellar shearing associated with the rotation of the crystal grains or the lamellar segments around the crystal a-axis, which is accentuated in the TD (transverse direction to fabrication) specimen. An additional deformation process, lamellar bending, is also observed in the MD specimen as being likely elastic in the dynamic response, and its contribution is found to be substantial, not to the α dispersion, but rather to the β dispersion of this material. The α₂ mechanism corresponding to the higher temperature relaxation process in the α mechanical dispersion is observed to be more pronounced in the TD than in the MD specimen. The apparent dynamic crystal lattice compliance shows a definite dispersion during activation of the α₂ mechanism, but a slight dispersion during activation the α₁ mechanism, suggesting that the α₂ mechanism must be related to an intracrystal relaxation process whereas the α₁ mechanism must be associated with an intercrystal relaxation process at their boundaries.     

Elastic quadrilateral plates

A method is proposed for the solution of elastic quadrilateral plates supported in any manner (except elastically) along the four edges. The procedure employs eigenfunctions for angular regions together with a collocation—least squares technique. Good agreement is found with other solutions for rectangular and parallelogram plates. An electronic computer is a necessary adjunct to the proposed method of solution.     

Forensic Investigation Through Data Remnants on Hadoop Big Data Storage System

Forensic examiners are in an uninterrupted battle with criminals in the use of Big Data technology. The underlying storage system is the main scene to trace the criminal activities. Big Data Storage System is identified as an emerging challenge to digital forensics. Thus, it requires the development of a sound methodology to investigate Big Data Storage System. Since the use of Hadoop as Big Data Storage System continues to grow rapidly, investigation process model for forensic analysis on Hadoop Storage and attached client devices is compulsory. Moreover, forensic analysis on Hadoop Big Data Storage System may take additional time without knowing where the data remnants can reside. In this paper, a new forensic investigation process model for Hadoop Big Data Storage System is proposed and discovered data remnants are presented. By conducting forensic research on Hadoop Big Data Storage System, the resulting data remnants assist the forensics examiners and practitioners for generating the evidences.     

The economic feasibility of sugar beet biofuel production in central North Dakota

This study examines the financial feasibility of producing ethanol biofuel from sugar beets in central North Dakota. Under the Energy Independence and Security Act (EISA) of 2007, biofuel from sugar beets uniquely qualifies as an “advanced biofuel”. EISA mandates production of 21 billion gallons of advanced biofuels annually by 2022. A stochastic simulation financial model was calibrated with irrigated sugar beet data from central North Dakota to determine economic feasibility and risks of production for 0.038 hm³y⁻¹ (or 10 MGY (Million Gallon per Year) and 0.076 hm³y⁻¹ (or 20 MGY) ethanol plants. Study results indicate that feedstock costs, which include sugar beets and beet molasses, account for more than 70 percent of total production expenses. The estimated breakeven ethanol price for the 0.076 hm³y⁻¹ plant is $400 m⁻³ ($1.52 per gallon) and $450 m⁻³ ($1.71 per gallon) for the 0.038 hm³y⁻¹ plant. Breakeven prices for feedstocks are also estimated and show that the 0.076 hm³y⁻¹ plant can tolerate greater ethanol and feedstock price risks than the 0.038 hm³y⁻¹ plant. Our results also show that one of the most important factors that affect investment success is the price of ethanol. At an ethanol price of $484.21 m⁻³ ($1.84 per gallon), and assuming other factors remain unchanged, the estimated net present value (NPV) for the 0.076 hm³y⁻¹ plant is $41.54 million. By comparison, the estimated NPV for the 0.038 hm³y⁻¹ plant is only $8.30 million. Other factors such as changes in prices of co-products and utilities have a relatively minor effect on investment viability.     

Genetics of Hb F/F cell variance in adults and heterocellular hereditary persistence of fetal hemoglobin

Hb F and F cell values in normal adults vary considerably with a continuous distribution that is substantially skewed to the right implicating a polygenic influence. The high values of Hb F and F cells are transmitted in the condition referred to as heterocellular hereditary persistence fetal hemoglobin which should be regarded as a multifactorial quantitative trait, quite distinct from the classical pancellular hereditary persistence of fetal hemoglobins. Several factors have been shown to influence F cell/Hb F levels in normal adults including age, gender, genetic determinants linked and unlinked to the beta-globin locus on chromosome 11p. Two trans-acting quantitative trait loci for F cell variance have been mapped, one on 6q and the other on Xp, with at least one other implicated. As an initial step towards hunting for the other quantitative trait loci we have carried out a preliminary analysis of F cell variance in 182 pairs of monozygotic and 373 pairs of dizygotic twins. The correlation coefficient of F cell variance in monozygotic twins was 0.89, while that in the dizygotic twins was 0.51. Overwhelming evidence for a strong genetic component in the control of Hb F/F cell levels is provided by a heritability of 0.87. However, the role and extent of contribution from the quantitative trait loci on 6q and Xp are still not known.     

Miscibility studies on blends of Kraton block copolymer and asphalt

Miscibility phase behavior in blends of SBS copolymers (Kraton 1101) and asphalt has been investigated through establishment of thermodynamic phase diagrams. The observed phase diagram of the SBS/asphalt blend is an upper critical solution temperature (UCST) type with a maximum at about 20% copolymer and around 200 °C. The study on kinetics of phase decomposition has been carried out by means of time resolved light scattering at the 6/94 Kraton 1101/asphalt composition. Time-evolution of structure factor has been analyzed in the context of temporal scaling laws. The growth regime is seemingly dominated by the late stage of phase decomposition where the hydrodynamic effect is dominant. As typical for a deep off-critical quench, the cessation of domain growth occurs presumably through physical pinning.