Sheath formation in the presence of non-extensive electron distribution

The main aim of this article is to recognize the sheath formation in the presence of non-extensive electron distribution. The role of ion–neutral collision parameter K and the non-extensive parameter “q” has been discussed. Existing literature suggests that the presence of non-extensive electrons potentially modifies the plasma sheath behaviour. However, numerical calculations over the full plasma range, jointly addressing the sheath and presheath, are rare. Sheath formation, being a very fundamental phenomenon, deserves enough investigation in the region of non-extensive distribution of particles. This study attempts to bridge the gap in understanding the formation of the sheath in collisional plasma in the light of both Boltzmann and q-distributed non-extensive electrons.     

Different approaches in thin-layer chromatography for enantioresolution of acebutolol using colistin sulfate as chiral selector

JPC – Journal of Planar Chromatography – Modern TLC - This work reports the enantioresolution of (RS)-acebutolol (ACB) by a thin-layer chromatographic method involving colistin sulfate...     

Self-assembled ultra-thin coatings of octadecyltrichlorosilane (OTS) formed at the surface of iron oxide nanoparticles

In a series of experiments, we coated iron oxide nanoparticles, which were originally stabilized with lauric acid, with a polymer layer of Octadecyltrichlorosilane (OTS). Characterization of the different coated nanoparticles was accomplished by Static and Dynamic Light Scattering, acoustic spectroscopy, and Atomic Force Microscopy. In various experiments, we systematically investigated the effect of different parameters such as the OTS concentration and iron oxide content on the particle size of the coated nanoparticles. It was recognized that the size of the coated nanoparticles mainly depend on the concentration of OTS (C _OTS) measured with respect to the concentration of the iron oxide particles (C _mag.). Below a well-defined threshold value of C _OTS /C _mag, we did not observe any adsorption of OTS on the surface of iron oxide nanoparticles. The particle size of OTS-coated iron oxide nanoparticles increased rapidly at concentration ratios above the threshold concentration and reached a typical plateau value for long periods of time.     

A feature vector integration approach for a generalized support vector machine pairwise homology algorithm

Due to the exponential growth of sequenced genomes, the need to quickly provide accurate annotation for existing and new sequences is paramount to facilitate biological research. Current sequence comparison approaches fail to detect homologous relationships when sequence similarity is low. Support vector machine (SVM) algorithms approach this problem by transforming all proteins into a feature space of equal dimension based on protein properties, such as sequence similarity scores against a basis set of proteins or motifs. This multivariate representation of the protein space is then used to build a classifier specific to a pre-defined protein family. However, this approach is not well suited to large-scale annotation. We have developed a SVM approach that formulates remote homology as a single classifier that answers the pairwise comparison problem by integrating the two feature vectors for a pair of sequences into a single vector representation that can be used to build a classifier that separates sequence pairs into homologs and non-homologs. This pairwise SVM approach significantly improves the task of remote homology detection on the benchmark dataset, quantified as the area under the receiver operating characteristic curve; 0.97 versus 0.73 and 0.70 for PSI-BLAST and Basic Local Alignment Search Tool (BLAST), respectively.     

Amitriptyline overdose treatment by pegylated anionic liposomes

Liposomes composed of DOPG, 50:50 DMPC:DOPG, 95:5 and 85:15 DOPG:DPPE-mPEG-2000, and 55:15:30 DMPC:DPPE-mPEG-2000:CH were studied for their ability to sequester amitriptyline in human serum. The effects of lipid type and loading, liposome size, PEG inclusion, protein interaction and storage were considered. Liposome size had no effect on drug uptake, as 40, 100, and 284 nm liposomes bound similar amounts of drug in buffer. The optimal amount of PEG-modified lipid incorporated into liposomes was found to be 5%. 95:5 DOPG:DPPE-mPEG-2000 liposomes loaded at 1.44 mg lipid/mL were most effective at shielding protein interactions while still allowing amitriptyline to diffuse to the bilayer surface and bind. Absolute reductions of 99% in buffer and human serum samples were observed, while the free drug concentration reduction relative to binding in serum without liposomes was nearly 90% across a drug concentration range of 1-20 muM. With such reductions, serum drug concentrations could be rapidly reduced from toxic to therapeutic levels. Furthermore, storage tests revealed that such liposomes may be stored for at least one month without a change in drug binding ability. These findings strongly suggest that predominantly anionic liposomes incorporated with PEG are excellent candidates for amitriptyline overdose treatment.     

Electrochemical response and separation in cyclic electric field-flow fractionation

Electric field-flow fractionation (EFFF) is a separation technique that couples a lateral electric field with axial Poiseuille flow to separate particles on the basis of size and/or mobility. In unidirectional EFFF, the field rapidly decreases in time due to charging of the double layer. The field strength could be increased by performing EFFF with cyclic electric fields. In cyclic electric field-flow fractionation (CEFFF), a periodic voltage, which can be either sinusoidal or square-wave, is applied in the lateral direction. In this paper, we measure the electrochemical response of CEFFF, i.e., the current-time response for a given time-dependent voltage and then utilize this electrochemical response in a transport model to predict separation. The CEFFF device studied here comprises two gold-coated glass plates separated by a spacer. The transient current profiles are measured for a step change and cyclic square-shaped voltage. The current profile is compared with the equivalent circuit model, and is fitted to a sum of two decaying exponentials. The dependence of the electrochemical response on voltage, frequency, channel thickness, and salt concentration is studied. Next, the electrochemical data are utilized in the convection-diffusion equation to develop a model for separation by CEFFF. The equations are solved by using a combination of analytical and numerical techniques to determine the mean velocity and the dispersion coefficient of molecules, and to determine the effect of various parameters on the separation efficiency of the EFFF device. Also, the model predictions are compared with experimental data available in the literature.     

Phenolate- and acetate (both mu(2)-1,1 and mu(2)-1,3 mode)-bridged face-shared trioctahedral linear Ni(II)(3), Ni(II)(2)M(II) (M = Mn, Co) complexes: ferro- and antiferromagnetic coupling

The complexes [(L)(2)Ni(II)(2)M(II)(mu(2)-1,3-OAc)(2)(mu(2)-1,1-OAc)(2)(S)(2)] x xMeOH [HL = N-methyl-N-(2-hydroxybenzyl)-2-aminoethyl-2-pyridine; M = Ni, S = MeOH, x = 6 (1); M = Mn, S = H(2)O, x = 0 (2); M = Co, S = MeOH, x = 6 (3)] have been synthesized. Crystal structures reveal that three octahedral MII ions form a linear array with two terminal moieties {(L)Ni(II)(mu(2)-1,3-OAc)(mu(2)-1,1-OAc)(MeOH/H(2)O)}(-) in a facial donor set and a central MII ion which is connected to the terminal ions via bridging phenolate and two types of bridging acetates. Magnetic measurements reveal that the Ni(II)(3) and Ni(II)(2)Co(II) centers are ferromagnetically and Ni(II)(2)Mn(II) center is antiferromagnetically coupled. An attempt has been made to rationalize the observed magneto-structural behavior.     

Are Methylaluminoxane Activators Sheets?

Density functional theory calculations on neutral sheet models for methylaluminoxane (MAO) indicate that these structures, containing 5-coordinate and 4-coordinate Al, are likely precursors to ion-pairs seen during the hydrolysis of trimethylaluminum (Me₃Al) in the presence of donors such as octamethyltrisiloxane (OMTS). Ionization by both methide ([Me]⁻) and [Me₂Al]⁺ abstraction, involving this donor, were studied by polarizable continuum model calculations in fluorobenzene (PhF) and o-difluorobenzene (DFB) media. These studies suggest that low MW, 5-coordinate sheets ionize by [Me₂Al]⁺ abstraction, while [Me]⁻ abstraction from Me₃Al-OMTS is the likely process for higher MW 4-coordinate sheets. Further, comparison of anion stabilities per mole of aluminoxane repeat unit (MeAlO)_n, suggest that anions such as [(MeAlO)₇(Me₃Al)₄Me]⁻=[ 7,4 ]⁻ are especially stable compared to higher homologues, even though their neutral precursors are unstable.