Gold and silver nanoparticles functionalized with known numbers of oligonucleotides per particle for DNA detection

The biospecificity of gold and silver nanoparticles, functionalized with known numbers of oligonucleotides, is demonstrated in colorimetric microbead assays for complementary and mismatch sequences.     

Comparison of sampling methods for 1,6-hexamethylene diisocyanate, (HDI) in a commercial spray box

In this study three different types of samplers for the determination of 1,6-hexamethylene diisocyanate in air were compared. The experimental set up was a simulation of real life conditions with spray painting operations performed inside a commercial, full sized, spray box. The sampling methods were 1-(2-methoxyphenyl)-piperazine impregnated on glass fibre filter, and the same reagent in impinger, and also dibutylamine in impinger. All analyses were performed by LC-MS-MS. The determined concentrations varied between 20 and 90 microg m(-3) with relative standard deviations from 7 to 17% for each method. No significant difference was found between the three methods using ANOVA with a significance level of alpha = 0.05.     

Chemical nucleation for CVD diamond growth.

A new nucleation method to form diamond by chemically pretreating silicon (111) surfaces is reported. The nucleation consists of binding covalently 2,2-divinyladamantane molecules on the silicon substrate. Then low-pressure diamond growth was performed for 2 h via microwave plasma CVD in a tubular deposition system. The resulting diamond layers presented a good cristallinity and the Raman spectra showed a single very sharp peak at 1331 cm(-1), indicating high-quality diamonds.     

Linear and cyclic aminomethanephosphonic acid esters derived from benzaldehyde derivatives, 3‐aminopropanol,and diethyl phosphite

A series of four diethyl {[(3‐hydroxy‐ propyl)amino](aryl)methyl}phosphonates have been prepared and characterized. In one case, the phosphonate was transformed to a seven‐membered 1,4,2‐ oxazaphosphepane heterocycle through a one‐pot intramolecular esterification. The analogous reaction with formaldehyde gave the six‐membered diethyl (1,3‐oxazinan‐3‐ylmethyl)phosphonate, which could be transformed in a posterior reaction to the corresponding aminomethanephosphonic acid. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:75–80, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20178     

Well modeling in the multi-scale finite-volume context

An extension of the multi-scale finite-volume (MSFV) method is devised, which allows to simulate flow and transport in reservoirs with complex well configurations. The new framework fits nicely into the data structure of the original MSFV method and it has the important property that no large patches covering the whole well are required. For each well, an additional degree of freedom is introduced. While the treatment of pressure-constraint wells is trivial, since the well-bore reference pressure is explicitly specified, additional equations have to be solved to obtain the unknown pressure values of rate-constraint wells. Numerical simulations of a difficult test case with multiple complex wells demonstrate the ability of the new framework to capture the interference between the various wells and the reservoir accurately. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Extended flamelet model and improved interaction of chemistry and turbulence for modeling partially premixed combustion with a joint PDF method

Turbulent combustion is commonly categorized into premixed, non-premixed and partially premixed combustion. For nonpremixed combustion simulations the laminar flamelet concept proved to be very valuable while for the more complex case of partially premixed combustion this model shows considerable deficiencies. Here, the classical laminar flamelet approach is extended to the partially premixed combustion regime. For that, the joint statistics of mixture fraction, scalar dissipation rate and a progress variable, calculated with a joint probability density function (PDF) method, is used to get the statistics of the compositions and of the chemical energy source term from pre-processed flame tables. This approach can be compared with the unsteady flamelet concept; the main differences consists of the way the progress variable evolution is computed and in the pre-computed flame tables. The progress variable describes the point of time a fluid parcel is consumed by a flame front. The fluid parcels are represented by computational particles, which are used for PDF methods. The pre-computed flame tables are computed from steady solutions 2D stabilized flames propagating into an unburnt mixture with varying mixture fraction. The corresponding position of a fluid particle in such a 2D laminar flame is determined by its mixture fraction and a burning time; both to be modeled for each computational particle in the PDF simulation. Numerical experiments of turbulent diffusion jet flames demonstrate that this approach can be employed for challenging test cases. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Improvements in titer,productivity, and yield using solka-floc for cellulase production

Researchers studying cellulase enzymes for the economical production of fuel ethanol envision cellulose as the carbon source. However, submerged Trichoderma reesei cultures grown on cellulose exhibit high run-to-run variability. Thus, an investigation of 30 batch cellulase production experiments was instrumental in determining fermentation conditions that improved enzyme titers, yields, and productivities. Eighteen of the 30 batch experiments experienced minimal process upsets and were classified into eight groups based on agitation rate, gas sparge rate, and the use of oxygen supplementation. Comparing corn steep liquor with yeast extract/peptone also tested the effect of different sources of nitrogen in the media. Average 7-d enzyme titers were doubled from 4 to 8 FPU/mL primarily by increasing aeration.     

Thermal Restructuring of Silica‐Grafted TiClx Species and Consequences for Epoxidation Catalysis

TiCl₄ grafted to dehydrated silica is an industrially applied catalyst for the epoxidation of propylene. As with many heterogeneous catalysts, the precise nature of the surface species is not yet fully known, prohibiting reliable structure–activity correlations. In this study, the speciation and restructuring of site‐isolated Ti^IV Lewis acid centers was carefully investigated by using a variety of techniques. The initially formed ?SiOTiCl₃ species were found to restructure upon heating through the transfer of Cl ligands to the silica surface, eventually leading to tripodal (?SiO)₃TiCl species. The superior activity and stability of such tripodal species is demonstrated for catalytic olefin epoxidation under continuous flow conditions.     

A green capillary zone electrophoresis method for the simultaneous determination of piperacillin,tazobactam and cefepime in pharmaceutical formulations and human plasma

A green, novel, rapid, accurate and reliable capillary zone electrophoresis method was developed and validated for the simultaneous determination of piperacillin, tazobactam and cefepime in pharmaceutical preparations. Separation was carried out using fused silica capillary (50 µm i.d. × 48.6 cm and 40.2 cm detection length) and applied potential of 20 kV (positive polarity) and a running buffer containing 15 m m sodium borate buffer adjusted to pH 9.3 with UV detection at 215 nm. Amoxicillin was used as an internal standard. The method was suitably validated according to International Conference on Harmonization guidelines. The method showed good linearity in the ranges of 10–100, 20–400 and 10–400 µg/mL with limits of quantitation of 1.87, 3.17 and 6.97 µg/mL and limits of detection of 0.56, 0.95 and 2.09 µg/mL for tazobactam, piperacillin and cefepime, respectively. The proposed method was successfully applied for the analysis of these drugs in their synthetic mixtures and co‐formulated injection vials. The method was extended to the in vitro determination of the two drugs in spiked human plasma. It is considered a ‘green’ method as it consumes no organic solvents. Copyright © 2015 John Wiley & Sons, Ltd.