A convenient synthetic route to new bis(arenediazo) complexes of molybdenum and tungsten

Complexes of the type [(C₅H₅)Mo(N₂Ar)(N₂Ar′)(PPh₃)] [PF₆] have been prepared and shown to be useful starting materials for the synthesis of a variety of neutral, cationic or anionic compounds containing [cis-Mo(N₂Ar)(N₂Ar′)]²⁺ units.     

Generation and characterization of phenylsulfanylcarbene

A photosensitive precursor (1) to phenylsulfanylcarbene 2 has been synthesized. Laser flash photolysis (308 nm) of 1 and chemical trapping studies of 2 are reported. [structure: see text]     

Age determination of a 75Se gamma radiography source for nuclear forensics

Journal of Radioanalytical and Nuclear Chemistry - Two methods were used to evaluate the age of 75Se sealed source material. Both methods utilized gamma spectroscopy to determine the quantity of...     

Peptide conjugated cellulose nanocrystals with sensitive human neutrophil elastase sensor activity

In chronic wounds, elevated human neutrophil elastase (HNE) is a destructive protease that has been proposed as a biomarker. Numerous wound dressing designs have been introduced in an effort to lower HNE levels. The clinical detection of HNE as a point of care biomarker or an in situ colorimetric adjuvant to chronic wound dressings presents potential advantages in the management of chronic wounds. A colorimetric approach to the detection of HNE using peptide conjugated cotton cellulose nanocrystals (CCN) is reported here. For this purpose a HNE tripeptide substrate, n-Succinyl-Alanine–Alanine-Valine-para-nitroanilide (Suc-Ala–Ala-Val-pNA), was covalently attached to glycine esterified CCN and compared with a similar tetrapeptide analog for colorimetric HNE sensor activity. Visible HNE activity was significantly higher on CCN tripeptide conjugates when compared with similar analogs synthesized on paper. Upon enzymatic release of para-nitroaniline (pNA) from the Glycine-CCN conjugate of succinyl-Ala–Ala-Val-pNA, amplification of the colorimetric response from pNA with reactive dyes enhanced visible absorption of the chromogen. Two color amplifying dyes that react with pNA were compared for their ability to enhance the visual sensor response to HNE activity. The colorimetric detection of HNE with CCN tripeptide conjugates was sensitive at HNE levels previously reported in chronic wound fluid (0.05 U/mL HNE). The HNE sensor and the chromogen amplifying dyes were interfaced with 50 and 10 kD dialysis cellulose membranes (DCM) to model filtration of HNE and chromogen (pNA) from a model wound dressing surface before and after sensor reactivity. The detection sensitivity to HNE activity was assessed with the CCN-tripeptide conjugate interfaced at the DCM surface distal and proximal to a dressing surface. The HNE sensor interfaced proximal to the dressing surface was most efficient with 10 kD membrane filtration of pNA and subsequent reaction with amplifying dyes. When interfaced with the 10 kD cellulose membrane, elastase sensor activity remained sensitive to 0.05 U/mL HNE. The nanocellulose surface properties, performance and design issues of the biosensor approach are discussed.     

QUADRATURE METHODS FOR HIGHLY OSCILLATORY SINGULAR INTEGRALS

We address the evaluation of highly oscillatory integrals,with power-law and logarithmic singularities.Such problems arise in numerical methods in engineering.Notably,the evaluation of oscillatory integrals dominates the run-time for wave-enriched boundary integral formulations for wave scattering,and many of these exhibit singularities.We show that the asymptotic behaviour of the integral depends on the integrand and its derivatives at the singular point of the integrand,the stationary points and the endpoints of the integral.A truncated asymptotic expansion achieves an error that decays faster for increasing frequency.Based on the asymptotic analysis,a Filon-type method is constructed to approximate the integral.Unlike an asymptotic expansion,the Filon method achieves high accuracy for both small and large frequency.Complex-valued quadrature involves interpolation at the zeros of polynomials orthogonal to a complex weight function.Numerical results indicate that the complex-valued Gaussian quadrature achieves the highest accuracy when the three methods are compared.However,while it achieves higher accuracy for the same number of function evaluations,it requires signi cant additional cost of computation of orthogonal polynomials and their zeros.     

Analysis of pp → K+K− π+π− around 1 GeV/c

Approximately 100 000 four-prong antiproton annihilations in hydrogen were measured. A clean, unbiased sample of 842 K⁺K^?π⁺π^? events was obtained. This reaction is dominated by $\text{K}{}^1\text{(～45\%)}$ and ?⁰(～20%) production, with smaller amounts of A₂⁰(～15%) and ?(～5%) production. 25% of the reactions involved double resonance production. No significant three-body resonance production is observed.     

Assessment of bone calcium and phosphorus content using micro X‐ray fluorescence spectrometry (μ‐EDXRF): effects of long‐term cadmium poisoning

This study assesses whether the concentrations of biologically important elements in bones are altered by long‐term consumption of cadmium (Cd)‐contaminated water. Heavy metal poisoning has significant impact on humans, and pollutants such as Cd are often found at high concentrations in waterways. Twelve Sprague Dawley rats consumed water with 50 p.p.m. Cd (Cd group), and another 12 consumed normal water (control group). Six subjects from each group were sacrificed after 2 weeks and the others after 4 weeks. Spectra were acquired from the femur by using the EDAX Eagle III micro‐XRF setup, and quantitative calculations were performed by using the fundamental parameter method to determine the concentrations of elements. A bone calcium/phosphorus concentration ratio (Ca/P) of 2.07 ± 0.001 is observed in the spectra from control subjects after 2 weeks and 2.07 ± 0.001 after 4 weeks. In Cd subjects, Ca/P after 2 weeks is 2.04 ± 0.001 and after 4 weeks is 1.97 ± 0.003. Statistically significant differences are obtained when comparing controls with Cd subjects at both time points and when comparing Cd subjects at both time points. Cadmium poisoning significantly affects bone Ca and P concentrations, increasing the likelihood of osteoporosis and other bone diseases. Copyright © 2016 John Wiley & Sons, Ltd.     

Algorithms for graph partitioning on the planted partition model

The NP‐hard graph bisection problem is to partition the nodes of an undirected graph into two equal‐sized groups so as to minimize the number of edges that cross the partition. The more general graph l‐partition problem is to partition the nodes of an undirected graph into l equal‐sized groups so as to minimize the total number of edges that cross between groups. We present a simple, linear‐time algorithm for the graph l‐partition problem and we analyze it on a random “planted l‐partition” model. In this model, the n nodes of a graph are partitioned into l groups, each of size n/l; two nodes in the same group are connected by an edge with some probability p, and two nodes in different groups are connected by an edge with some probability r<p. We show that if p−r≥n^−1/2+ϵ for some constant ϵ, then the algorithm finds the optimal partition with probability 1− exp(−n^Θ(ε)). © 2001 John Wiley & Sons, Inc. Random Struct. Alg., 18: 116–140, 2001     

Nanomolar Inhibitors for Two Distinct Biological Target Families from a Single Synthetic Sequence: A Next Step in Combinatorial Library Design?

One common synthetic route creates small-molecule libraries directed toward two functionally distinct target families. The novel structural template 1 can independently display the necessary pharmacophore patterns for inhibition of members of two different biomolecular target families, the matrix metalloproteinases (MMPs) or the phosphodiesterases (PDEs). The incorporation of multiple target family directed design elements into combinatorial library design could help expedite the pharmaceutical lead discovery process. Z=OR′ (PDE4), H (MMPs).     

Positively and negatively charged ionic modifications to cellulose assessed as cotton-based protease-lowering and hemostatic wound agents

Recent developments in cellulose wound dressings targeted to different stages of wound healing have been based on structural and charge modifications that function to modulate events in the complex inflammatory and hemostatic phases of wound healing. Hemostasis and inflammation comprise two overlapping but distinct phases of wound healing wherein different dressing material properties are required to bring pathological events under control when they present as a result of trauma or chronic wounds. Thus, we have designed cellulose wound dressings with properties that function through modified fiber surface properties to lower protease levels in the chronic wound and promote clotting in hemorrhaging wounds. With this in mind three finishing chemistries utilizing traditional pad-dry-cure approaches were explored for their potential to confer charged properties to cotton dressings. Cellulose dressings designed to remove cationic serine proteases from highly exudative chronic wounds were created to present negatively charged fibers as an ion exchange mechanism of protease-lowering. Phosphorylated cotton and polycarboxylic acid crosslinked cotton were prepared to examine their ability to remove human neutrophil elastase (HNE) from surrogate wound fluid. A cellulose phosphorylation reaction utilizing sodium hexametaphosphate: urea was explored to optimize cellulose phosphorylation as a function of HNE sequestration efficacy. Acid catalyzed cross linking of cellulose with butane-tetracarboxylic acid also resulted in a negatively charged dressing that removed HNE from solution more effectively than phosphorylated cellulose. Collagenase sequestration was also assessed with phosphorylated cellulose and polycarboxylic acid cross linked cellulose derivatives. Butanetetracarboxylic acid and phosphorylated cellulose functioned to remove collagenase from solution most effectively. Cellulose dressings designed to accelerate thrombosis and aggregation of blood platelets were prepared with a view to examining derivatized cotton fibers bearing a net positive charge to promote hemostasis. Cellulose and chitosan dressings bearing an aminoglucan functionality were created by grafting chitosan on cotton and preparing aminized cotton. The preparation of chitosan-grafted cotton dressings was completed with a citric acid grafting onto cellulose. Aminized cotton was functionalized as an ethylamino-ether cellulose derivative. The chitosan-grafted and aminized cotton demonstrated a dose response gelling of citrated sheep blood.