Optical properties of amorphous SixGe1−x(H) alloys prepared by R.F. Glow discharge

Amorphous alloys of Si and Ge have been prepared over the entire composition range by r.f. plasma decomposition of mixed gases of SiH₄ and GeH₄. The optical absorption edge is found to have a linear dependence on alloy composition given by: E_g = 0.95 + 0.70x (eV).     

Identification of Acepromazine and Its Metabolites in Horse Plasma and Urine by LC–MS/MS and Accurate Mass Measurement

Acepromazine maleate (Sedalin^®) was administered orally to six thoroughbred horses at a dose of 0.15 mg kg⁻¹. Urine and blood samples were collected up to 412 h post-administration. Plasma and urine were hydrolysed; plasma samples were then processed using liquid–liquid extraction and urine samples using solid-phase extraction. A sensitive tandem mass spectrometric method was developed in this study, achieving a lower limit of quantification for acepromazine of 10 pg mL⁻¹ in plasma and 100 pg mL⁻¹ in urine. Acepromazine, hydroxyethylpromazine, hydroxyacepromazine, hydroxyethylpromazine sulphoxide, hydroxyethylhydroxypromazine, dihydroxyacepromazine and dihydroxyhydroxyethylpromazine were detected in the post-administration samples. The parent drug and its metabolites were identified using a combination of UPLC–MS/MS and accurate mass measurement. Separation of the structural isomers hydroxyethylpromazine sulphoxide and hydroxyethylhydroxypromazine was another significant outcome of this work and demonstrated the advantages to be gained from investing in chromatographic method development.

     

A self-powered, one-step chip for rapid, quantitative and multiplexed detection of proteins from pinpricks of whole blood

We describe an automated, self-powered chip based on lateral flow immunoassay for rapid, quantitative, and multiplex protein detection from pinpricks of whole blood. The device incorporates on-chip purification of blood plasma by employing inertial forces to focus blood cells away from the assay surface, where plasma proteins are captured and detected on antibody "barcode" arrays. Power is supplied from the capillary action of a piece of adsorbent paper, and sequentially drives, over a 40 minute period, the four steps required to capture serum proteins and then develop a multiplex immunoassay. An 11 protein panel is assayed from whole blood, with high sensitivity and high reproducibility. This inexpensive, self-contained, and easy to operate chip provides a useful platform for point-of-care diagnoses, particularly in resource-limited settings.     

Graphical balanced allocations and the (1 + β)‐choice process

Suppose m balls are sequentially thrown into n bins where each ball goes into a random bin. It is well‐known that the gap between the load of the most loaded bin and the average is , for large m. If each ball goes to the lesser loaded of two random bins, this gap dramatically reduces to independent of m. Consider a constrained setting where not all pairs of bins can be sampled. We are given a graph where each node corresponds to a bin. The process sequentially samples an edge from the graph and places a ball in the lesser loaded of its endpoints. We show the gap is at most where σ is the edge expansion of the graph. Our results extend naturally to the hypergraph version of this question. Our technique involves a tight analysis of what we call the “‐choice” process for some parameter : each ball goes to a random bin with probability and the lesser loaded of two random bins with probability β. For this process we show that the gap is , irrespective of m. Moreover the gap stays at in the weighted case for a large class of weight distributions. No non‐trivial bounds were previously known in the weighted case, even for the 2‐choice case. © 2014 Wiley Periodicals, Inc. Random Struct. Alg., 47, 760–775, 2015     

Routing complexity of faulty networks

One of the fundamental problems in distributed computing is how to efficiently perform routing in a faulty network in which each link fails with some probability. This article investigates how big the failure probability can be, before the capability to efficiently find a path in the network is lost. Our main results show tight upper and lower bounds for the failure probability, which permits routing both for the hypercube and for the d‐dimensional mesh. We use tools from percolation theory to show that in the d‐dimensional mesh, once a giant component appears—efficient routing is possible. A different behavior is observed when the hypercube is considered. In the hypercube there is a range of failure probabilities in which short paths exist with high probability, yet finding them must involve querying essentially the entire network. Thus the routing complexity of the hypercube shows an asymptotic phase transition. The critical probability with respect to routing complexity lies in a different location than that of the critical probability with respect to connectivity. Finally we show that an oracle access to links (as opposed to local routing) may reduce significantly the complexity of the routing problem. We demonstrate this fact by providing tight upper and lower bounds for the complexity of routing in the random graph G_n,p. © 2007 Wiley Periodicals, Inc. Random Struct. Alg., 2008     

Water-soluble photoinitiators: Primary processes in hydroxy alkyl phenyl ketones

Photopolymerization of acrylamide in water has been investigated in the presence of watersoluble hydroxy alkyl phenyl ketones. The processes involved in the excited states (α-cleavage, electron transfer, monomer quenching) have been studied by time-resolved laserspectroscopy. Substitution at the para position of the phenyl ring changes drastically the reactivity and influences the possibility of synergistic effects when combining these photoinitiators with thioxanthone derivatives.     

Surface-modified hemispherical polystyrene/polybutyl methacrylate composite particles

Micrometer-sized polystyrene/poly(n-butyl methacrylate) composite particles of hemisphere morphology and narrow size distribution were prepared by a process of single-step swelling of uniform polystyrene template microspheres with emulsion droplets of the monomer n-butyl methacrylate containing the initiator benzoyl peroxide in the presence, or absence, of the co-swelling agent toluene. Butyl methacrylate was then polymerized at 73 degrees C within the template microspheres. Surface and bulk characterization of the particles were performed by methods such as FTIR, elemental analysis, XPS, advancing contact angle, light microscope, SEM, and cross-sectional TEM. Selective surface functionalization of the poly(n-butyl methacrylate) phase of the composite particles was performed by carrying out a similar swelling and polymerization process in the presence of a water-soluble vinylic monomer such as acrylamide.     

Novel monolithic poly(p-methylstyrene-co-bis(p-vinylbenzyl)dimethylsilane) capillary columns for biopolymer separation

Hydrophobic organo-silane based monolithic capillary columns were prepared by thermally initiated free radical polymerisation within the confines of 200 microm i.d. fused silica capillaries. A novel crosslinker, namely bis(p-vinylbenzyl)dimethylsilane (BVBDMS), was copolymerised with p-methylstyrene (MS) in the presence of 2-propanol and toluene, using alpha,alpha'-azoisobutyronitrile (AIBN) as initiator. Monolithic capillary columns, differing in the total monomer, microporogen content and microporogen nature were fabricated and the chromatographic efficiency of each monolith, regarding the separation of proteins, peptides and oligonucleotides, was evaluated and compared. Changes in monolith morphology were monitored by scanning electron microscopy (SEM). Porosity and specific surface areas of the supports were studied by means of mercury intrusion porosimetry and BET measurements, respectively. Pressure drop vs. flow rate measurements proved the prepared poly(p-methylstyrene-co-bis(p-vinylbenzyl)dimethylsilane) (MS/BVBDMS) monoliths to be mechanically stable and swelling propensity (SP) factors of 0.78-1.10 indicate high crosslinking homogeneity.