Direct catalytic enantioselective alpha-aminomethylation of aldehydes

The direct catalytic asymmetric alpha-aminomethylation of aldehydes is presented. The chiral amine and amino acid catalyzed reactions between unmodified aldehydes and a formaldehyde-derived imine precursor were fast and proceeded with high chemo- and enantioselectivities. The corresponding dibenzyl-protected gamma-amino alcohols were isolated in high yields with up to 98% ee after in situ reduction. The reaction is a novel entry to valuable beta(2)-amino acid derivatives.     

Energy Based Logic Mining Analysis with Hopfield Neural Network for Recruitment Evaluation

An effective recruitment evaluation plays an important role in the success of companies, industries and institutions. In order to obtain insight on the relationship between factors contributing to systematic recruitment, the artificial neural network and logic mining approach can be adopted as a data extraction model. In this work, an energy based k satisfiability reverse analysis incorporating a Hopfield neural network is proposed to extract the relationship between the factors in an electronic (E) recruitment data set. The attributes of E recruitment data set are represented in the form of k satisfiability logical representation. We proposed the logical representation to 2-satisfiability and 3-satisfiability representation, which are regarded as a systematic logical representation. The E recruitment data set is obtained from an insurance agency in Malaysia, with the aim of extracting the relationship of dominant attributes that contribute to positive recruitment among the potential candidates. Thus, our approach is evaluated according to correctness, robustness and accuracy of the induced logic obtained, corresponding to the E recruitment data. According to the experimental simulations with different number of neurons, the findings indicated the effectiveness and robustness of energy based k satisfiability reverse analysis with Hopfield neural network in extracting the dominant attributes toward positive recruitment in the insurance agency in Malaysia.     

Thermoelastic problem for shells of revolution exhibiting temperature dependent properties

Summary Analysis of the axially symmetric steady state thermoelastic problem for thin shells of revolution is given, assuming temperature dependent elastic and thermal properties of the material. Three governing equations are established involving components of the displacement along and normal to the meridian as well as the shearing force.A multi-parameter perturbation scheme is used with two perturbation parameters, one associated with the shear modulus and the other with Poisson's ratio.Illustrative examples are solved concerning cylindrical, conical and spherical shells as well as compound shells, such as spherico-conical, conicocylindrical and conico-conical.The results presented in this paper are taken from a thesis by the first author submitted in partial fulfilment of the requirements for the Ph. D. degree at the University of Delaware. The research was supported by a grant of the National Science Foundation.     

Sol–gel synthesis of ZnO–SiO2 thin films: impact of ZnO contents on its photonic efficiency

Highly crystalline ZnO–SiO₂ films obtained by a sol–gel method at different ZnO contents were deposited on silicon substrate (P(100)) using spin coating process. The XRD results revealed that the strong ZnO(100) peak is grown with highly c-axis oriented film and the crystallinity is progressively improved with increasing ZnO contents. SEM micrographs of the films deposited on silicon substrate show a homogeneous and uniformity structure at different ZnO content. The prepared ZnO–SiO₂ films are compared with either a film prepared from a commercial photocatalysts Hombikat UV-100 or Pilkington Glass Activ? by the determination of their photonic efficiencies for degradation of methylene blue. The photocatalytic efficiency of the 10 wt% ZnO–SiO₂ film was found to be about four times higher than film prepared from UV-100 or Pilkington Glass Activ?. The photocatalytic efficiencies of ZnO–SiO₂ films are increased with increasing ZnO content from 1 wt% to 10 wt% ZnO and then decreased at 15 wt% ZnO. The order of photocatalytic efficiencies of ZnO–SiO₂ films at different ZnO content and commercial photocatalysts after 6 h illumination were as following: 10 wt% ZnO > 15 wt% ZnO > 1 wt% ZnO > as-prepared 10 wt% ZnO–SiO₂ film > UV-100 > Pilkington Glass Activ?, which suggested that the ZnO–SiO₂ films are photoactive than commercial photocatalysts. The improved efficiency and potentially the low-cost synthesis suggest that this material might be practically useful as a photocatalyst film.     

Elevation of charring level of polyamide-6,6 films via ionic introduction of phosphoric acid and boric acid esters

Phosphorus and boron containing materials have the feature of increasing char formation, which can be effectively used as flame retardants especially in textiles. This paper discusses the ionic addition of phosphorus and boron esters to polyamide-6,6 (PA66), and its effect on the charring level. A mixture of phosphoric acid–boric acid ester at different degrees of esterification (ED) was prepared and two theoretical mechanisms for the esterification reaction were suggested. Ionically grafted polymer films were prepared by introducing the ester of highest ED to PA66–formic acid solution via three different processes: open air (cold) grafting, ultraviolet irradiation grafting, and hot vacuum oven grafting. Thermogravimetry was conducted for all synthesized esters and films, and the formation of new bonds between the ester and PA66 was verified using Fourier transform infrared spectroscopy.     

Overexpression,Purification and Validation of Antigenic Salmonella enterica Serovar Typhi Proteins Identified from LC-MS/MS

In our earlier study, an immunoblot analysis using sera from febrile patients revealed that a 50-kDa band from an outer membrane protein fraction of Salmonella enterica serovar Typhi was specifically recognized only by typhoid sera and not sera from other febrile illnesses. Here, we investigated the identities of the proteins contained in the immunogenic 50-kDa band to pinpoint antigens responsible for its immunogenicity. We first used LC-MS/MS for protein identification, then used the online tool ANTIGENpro for antigenicity prediction and produced recombinant proteins of the lead antigens for validation in an enzyme-linked immunosorbent assay (ELISA). We found that proteins TolC, GlpK and SucB were specific to typhoid sera but react to antibodies differently under native and denatured conditions. This difference suggests the presence of linear and conformational epitopes on these proteins.     

Oleate Ester-Derived Nonionic Surfactants: Synthesis and Cloud Point Behavior Studies

The synthesis and cloud point behavior of high oleate ester-derived nonionic surfactants are now reported. The effect of various polyethoxylate chain lengths (polyethylene glycol with 7, 11, and 16 units of ethylene oxide (EO) monomer) as the surfactant's hydrophilic head on the cloud point was investigated. The effect of varying amounts of sodium chloride and five different ionic surfactants on the cloud points of the synthesized nonionic surfactants were also presented. When the chain length of polyethoxylate increased, the cloud point of the synthesized nonionic surfactant also increased, ranging from 16°C, 43°C, and 64°C for 7, 11, and 16 EO units, respectively. Increments in sodium chloride concentration depressed the cloud point values of the synthesized nonionic surfactants linearly. The addition of ionic surfactants elevated the cloud points of the synthesized nonionic surfactant. However, in the presence of sodium chloride, the cloud point of the mixed ionic-nonionic solution was suppressed and anincrease in ionic surfactant concentration was required to elevate the cloud point. It was also found that the cloud points of synthesized surfactants can be raised up to 95°C in the presence of 4wt% NaCl solution.     

Gamma-ray spectrometry for the self-attenuation correction factor of the sand samples from Antalya in Turkey

In this paper, we attempt to determine the self-attenuation correction factor for 37 different sand samples collected from Antalya region of Turkey with densities changing from 2.205 to 2.679 g  \(\hbox {cm}^{-3}.\) Transmission method has been used in order to obtain self-attenuation correction factor in comparison with the air and ultrapure water samples for each case. Self-attenuation correction factor versus energy fit curve is obtained. While the self-attenuation correction factor has large values at low energies, it becomes smaller at high energies and tends to become constant thereafter.     

聚乙烯基胺包裹Fe3O4@SiO2磁性微球用于Knoevenagel缩合（英文）简

Polyvinyl amine coated Fe₃O₄@SiO₂ composite microspheres with a core-shell structure were prepared and employed as a magnetic catalyst for Knoevenagel condensation under mild conditions. The catalyst can be readily recovered using a magnet and reused several times without loss in activity or selectivity. The performance of the magnetic base catalyst was compared with that of polyvinyl amine functionalized mesoporous SBA-15, which showed that the magnetic nanoparticles gave improved reaction rate and yield.     

Peleg and Weibull models for water absorption of copolymer gels crosslinked on polyethylene glycol dimethacrylates

In this study, the super-absorbent copolymer gels were obtained from the aqueous solution of monomers dispersed in a continuous organic phase. The inverse suspension polymerization was accomplished with the use of aqueous solutions of partly neutralized acrylic acid with a predetermined crosslinker agent, polyethylene glycol dimethacrylates (PEGDMA)/monomer ratio in cyclohexan. The copolymer gels synthesized using PEGDMA crosslinker with three different molecular weights (PEGDMA₃₃₀, PEGDMA₅₅₀, and PEGDMA₇₅₀) were characterized by ?nfrared spectroscopy and scanning electron microscopy. Water absorption capacities of the copolymer gels were determined. The water absorption capacity of 1 g copolymer gels in water was respectively obtained as 232, 255, and 316 g water/g polymer gel for PEGDMA₃₃₀, PEGDMA₅₅₀, and PEGDMA₇₅₀, respectively. The Peleg and Weibull models were used to describe the water absorption behavior of the copolymer gels. The highest values of R ² and the lowest values of χ ² and RMSE for copolymer gels were observed with the Weibull model.