Separation of Cholesterol from other Steroids Using Molecularly Imprinted Polymer Prepared by Seeded Suspension Polymerization

Micron-sized particles of cholesterol-imprinted polymers were synthesized by seeded suspension polymerization in a mixture of 2-propanol and water using polystyrene microbeads as the seeds. Methacrylic acid was employed as the functional monomer to form complexes with template (cholesterol), along with ethylene glycol dimethacrylate as the crosslinker. After removal of template molecules, the columns ( H=15 cm, Di= 0.46 cm ) packed with cholesterol-imprinted polymers were effective for the chromatographic separation of cholesterol from other steroids. When the sample of steroids was eluted isocratically at a flow-rate of Q = 0.5 mL min-1, using a mixture of acetonitrile and water (Ψ= 95:5) as the mobile phase, the retention times for estrone, -estradiol and cholesterol were respectively τ = 5.3, 12.3 and 17.2 min. The average retention times were = 5.3, 10.9 and 16.7 min respectively for estrone, progesterone and cholesterol in samples. The separation was based on the specific binding of cholesterol to recognition sites formed on the imprinted polymers. A separation factor of 1.6 for cholesterol and -estradiol was obtained. The chromatographic efficiency was dependent on the mobile phase composition. Reducing the water content in the non-polar mobile phase to zero could significantly enhance the separation. Compared with particles from bulk polymerization, the column packed with cholesterol-imprinted particles from seeded suspension polymerization had a higher chromatographic efficiency and the advantage of microanalysi

Robust variance-constrained H∞ control for stochastic systems with multiplicative noises

This is the post print version of the article. The official published version can be obtained from the link below - Copyright 2007 Elsevier Ltd.In this paper, the robust variance-constrained H∞ control problem is considered for uncertain stochastic systems with multiplicative noises. The norm-bounded parametric uncertainties enter into both the system and output matrices. The purpose of the problem is to design a state feedback controller such that, for all admissible parameter uncertainties, (1) the closed-loop system is exponentially mean-square quadratically stable; (2) the individual steady-state variance satisfies given upper bound constraints; and (3) the prescribed noise attenuation level is guaranteed in an H∞ sense with respect to the additive noise disturbances. A general framework is established to solve the addressed multiobjective problem by using a linear matrix inequality (LMI) approach, where the required stability, the H∞ characterization and variance constraints are all easily enforced. Within such a framework, two additional optimization problems are formulated: one is to optimize the H∞ performance, and the other is to minimize the weighted sum of the system state variances. A numerical example is provided to illustrate the effectiveness of the proposed design algorithm.This work was supported in part by the Engineering and Physical Sciences Research Council (EPSRC) of the UK under Grant GR/S27658/01, the Nuffield Foundation of the UK under Grant NAL/00630/G, and the Alexander von Humboldt Foundation of Germany

Validity and reliability of questionnaires measuring physical activity self-efficacy, enjoyment, social support among Hong Kong Chinese children

AbstractBackgroundPhysical activity (PA) correlates have not been extensively studied in Hong Kong children.ObjectiveThe aim of this study is to assess the validity and reliability of translated scales to measure PA related self-efficacy, enjoyment and social support in Hong Kong Chinese children.MethodsSample 1 (n=273, aged 8–12years) was recruited (May–June, 2013) from two primary schools. Confirmatory factor analyses (CFA) were conducted to assess factorial validity. Criterion validity was assessed by correlating measured constructs with self-reported PA. Cronbach's alpha was computed to assess scale internal consistency. The intraclass correlation coefficient (ICC) was performed to assess scale test–retest reliability. Criterion validity was further examined in Sample 2 (n=84, aged 8–12years) from a third school by correlating measured constructs with objectively measured PA collected in September 2013 and February 2014.ResultsThe CFA results supported the one-factor structure of the scales. All PA correlates were significantly (p<0.01) associated with self-reported PA in Sample 1. Self-efficacy and enjoyment were significantly (p<0.05) correlated with objectively measured PA in Sample 2. All the scales demonstrated acceptable internal consistency. All ICC values of the scales suggested acceptable test–retest reliability.ConclusionThe results provide psychometric support for using the scales to measure PA correlates among Hong Kong Chinese children

Plasticity of a critical antigenic determinant in the West Nile virus NY99 envelope protein domain III

West Nile virus (WNV) is a mosquito-borne flavivirus that causes febrile illness, encephalitis, and occasionally death in humans. The envelope protein is the main component of the WNV virion surface, and domain III of the envelope protein (EIII) is both a putative receptor binding domain and a target of highly specific, potently neutralizing antibodies. Envelope E-332 (E-332) is known to have naturally occurring variation and to be a key determinant of neutralization for anti-EIII antibodies. A panel of viruses containing all possible amino acid substitutions at E-332 was constructed. E-332 was found to be highly tolerant of mutation, and almost all of these changes had large impacts on antigenicity of EIII but only limited effects on growth or virulence phenotypes

Robust H∞ control for a class of nonlinear discrete time-delay stochastic systems with missing measurements

This is the post print version of the article. The official published version can be obtained from the link - Copyright 2009 Elsevier LtdThis paper is concerned with the problem of robust H∞ output feedback control for a class of uncertain discrete-time delayed nonlinear stochastic systems with missing measurements. The parameter uncertainties enter into all the system matrices, the time-varying delay is unknown with given low and upper bounds, the nonlinearities satisfy the sector conditions, and the missing measurements are described by a binary switching sequence that obeys a conditional probability distribution. The problem addressed is the design of an output feedback controller such that, for all admissible uncertainties, the resulting closed-loop system is exponentially stable in the mean square for the zero disturbance input and also achieves a prescribed H∞ performance level. By using the Lyapunov method and stochastic analysis techniques, sufficient conditions are first derived to guarantee the existence of the desired controllers, and then the controller parameters are characterized in terms of linear matrix inequalities (LMIs). A numerical example is exploited to show the usefulness of the results obtained.This paper was not presented at any IFAC meeting. This paper was recommended for publication in revised form by Associate Editor Dragan Nešic under the direction of Editor Hassan K. Khalil. This work was supported in part by the Engineering and Physical Sciences Research Council (EPSRC) of the U.K. under Grant GR/S27658/01, the City University of Hong Kong under Grant 7001992, the Royal Society of the U.K. under an International Joint Project, the Natural Science Foundation of Jiangsu Province of China under Grant BK2007075, the National Natural Science Foundation of China under Grant 60774073, and the Alexander von Humboldt Foundation of Germany

Recovery of West Nile Virus Envelope Protein Domain III Chimeras with Altered Antigenicity and Mouse Virulence

ABSTRACT Flaviviruses are positive-sense, single-stranded RNA viruses responsible for millions of human infections annually. The envelope (E) protein of flaviviruses comprises three structural domains, of which domain III (EIII) represents a discrete subunit. The EIII gene sequence typically encodes epitopes recognized by virus-specific, potently neutralizing antibodies, and EIII is believed to play a major role in receptor binding. In order to assess potential interactions between EIII and the remainder of the E protein and to assess the effects of EIII sequence substitutions on the antigenicity, growth, and virulence of a representative flavivirus, chimeric viruses were generated using the West Nile virus (WNV) infectious clone, into which EIIIs from nine flaviviruses with various levels of genetic diversity from WNV were substituted. Of the constructs tested, chimeras containing EIIIs from Koutango virus (KOUV), Japanese encephalitis virus (JEV), St. Louis encephalitis virus (SLEV), and Bagaza virus (BAGV) were successfully recovered. Characterization of the chimeras in vitro and in vivo revealed differences in growth and virulence between the viruses, with in vivo pathogenesis often not being correlated with in vitro growth. Taken together, the data demonstrate that substitutions of EIII can allow the generation of viable chimeric viruses with significantly altered antigenicity and virulence. IMPORTANCE The envelope (E) glycoprotein is the major protein present on the surface of flavivirus virions and is responsible for mediating virus binding and entry into target cells. Several viable West Nile virus (WNV) variants with chimeric E proteins in which the putative receptor-binding domain (EIII) sequences of other mosquito-borne flaviviruses were substituted in place of the WNV EIII were recovered, although the substitution of several more divergent EIII sequences was not tolerated. The differences in virulence and tissue tropism observed with the chimeric viruses indicate a significant role for this sequence in determining the pathogenesis of the virus within the mammalian host. Our studies demonstrate that these chimeras are viable and suggest that such recombinant viruses may be useful for investigation of domain-specific antibody responses and the more extensive definition of the contributions of EIII to the tropism and pathogenesis of WNV or other flaviviruses

Application of antagonistic rhizobacteria for control of Fusarium seedling blight and basal rot of lily

Three antagonistic bacteria, Streptomyces misionensis strain PMS101, Bacillus thermoglucosidasius strain PMB207, and S. sioyaensis strain PMS502, were tested for sensitivity to the foliar fungicide Sporgon (a.i. 50% prochloraz-Mn complex) and for efficacy in controlling Fusarium diseases of lily. Results showed that the growth of all three antagonistic strains of bacteria was completely suppressed by Sporgon at a concentration of 500 mu g/mL, but B. thermoglucosidasius strain PMB207 and S. misionensis strain PMS101 were unaffected at concentrations of 100 mu g/mL or lower. A large-scale trial in an automated and environment-controlled commercial greenhouse showed that treatment of scale bulblets of lily with Sporgon (100 mu g /mL) and B. thermoglucosidasius strain PMB207 (1-1.2 x 10(7) cfu/mL) or 100 mu g/mL Sporgon and S. misionensis strain PMS101 (1-1.4 x 10(7) cfu/mL) resulted in a significant reduction (P 0.05). Results of the greenhouse and field experiments showed that treatment of scale bulblets or one-year-old bulbs of lily with B. thermoglucosidasius strain PMB207 (1-1.2 x 10(8) cfu/mL) or S. misionensis strain PMS101 (1-1.4 x 10(8) cfu/mL) without Sporgon was also effective in the control of basal rot caused by F. oxysporum f. sp. lilii. These studies reveal that B. thermoglucosidasius strain PMB207 and S. misionensis strain PMS101 are biocontrol agents which have potential for use in the commercial production of lily bulbs, as they can be used alone or in combination with the fungicide Sporgon at low concentration (< 100 mu g/mL)

Synthesis and trans-ureation of N,N '-diphenyl-4, 4 '-methylenediphenylene biscarbamate with diamines: a non-isocyanate route (NIR) to polyureas

A non-isocyanate route (NIR) of making polyureas of high molecular weight has been found through transureation of N,N'-diphenyl-4,4'-methylenediphenylene biscarbamate (4,4'-DP-MDC) with a variety of diamines and mixed diamines. The preparation of 4,4'-DP-MDC was achieved readily by carbonylation of 4,4'-methylenedianiline (4,4'-MDA) with diphenyl carbonate (DPC) using organic acids as catalysts. It was found that the highest yield (99%) of pure 4,4'-DP-MDC can be isolated in a toluene solution under mild conditions co-catalyzed by benzoic acid and tertiary amine. Trans-ureation of 4,4'-DP-MDC with aliphatic amines indicated that the process is a highly solvent dependent process and was found to be extremely facile in dimethyl sulfoxide (DMSO) at 80 C and in tetramethylene sulfone (TMS) at 140 C in absence of any catalyst. Particularly, the most effective polymerization process was developed using tetramethylene sulfone (TMS) as the solvent under reduced pressure for concurrently distilling off phenol from the reaction mixture during the polymerization in a shifting equilibrium towards polyurea. However, this solvent-assisted transureation was found to be in-efficient when N, N'-dimethyl-4,4'- methylenediphenylene biscarbamate (4,4'-DM-MDC) was used in a similar condition for comparison. Thus, an efficient green-chemistry process has been developed based on 4,4'-DP-MDC in making urea prepolymers, urea elastomers and urea plastics all in excellent yields without using reactive methylenediphenylene diisocyanate (MDI) or any catalysts in the trans-ureation polymerizations

Construction and one-step purification of Bacillus kaustophilus leucine aminopeptidase fused to the starch-binding domain of Bacillus sp strain TS-23 alpha-amylase

The starch-binding domain of Bacillus sp. strain TS-23 alpha-amylase was introduced into the C-terminal end of Bacillus kaustophilus leucine aminopeptidase (BkLAP) to generate a chimeric enzyme (BkLAPsbd) with raw-starch-binding activity. BkLAPsbd, with an apparent molecular mass of approximately 65 kDa, was overexpressed in Escherichia coli M15 cells and purified to homogeneity by nickel-chelate chromatography. Native PAGE and chromatographic analyses revealed that the purified fusion protein has a hexameric structure. The half-life for BkLAPsbd was 12 min at 70 degrees C, while less than 20% of wild-type enzyme activity retained at the same heating condition. Compared with the wild-type enzyme, the 60% decrease in the catalytic efficiency of BkLAPsbd was due to a 91% increase in K-m value. Starch-binding assays showed that the K-d and B-max values for the fusion enzyme were 2.3 mu M and 0.35 mu mol/g, respectively. The adsorption of the crude BkLAPsbd onto raw starch was affected by starch concentration, pH, and temperature. The adsorbed enzyme could be eluted from the adsorbent by 2% soluble starch in 20 mM Tris-HCl buffer (pH 8.0). About 49% of BkLAPsbd in the crude extract was recovered through one adsorption-elution cycle with a purification of 11.4-fold