Spin States of Homochiral and Heterochiral Isomers of [Fe(PyBox)2]2+ Derivatives

The following iron(II) complexes of 2,6-bis(oxazolinyl)pyridine (PyBox; LH) derivatives are reported: [Fe(LH)2][ClO4]2 (1); [Fe((R)-LMe)2][ClO4]2 ((R)-2; LMe=2,6-bis{4-methyloxazolinyl}pyridine); [Fe((R)-LPh)2][ClO4]2 ((R)-3) and [Fe((R)-LPh)((S)-LPh)][ClO4]2 ((RS)-3; LPh=2,6-bis{4-phenyloxazolinyl}pyridine); and [Fe((R)-LiPr)2][ClO4]2 ((R)-4) and [Fe((R)-LiPr)((S)-LiPr)][ClO4]2 ((RS)-4; LiPr=2,6-bis{4-isopropyloxazolinyl}pyridine). Solid (R)-3⋅MeNO2 exhibits an unusual very gradual, but discontinuous thermal spin-crossover with an approximate Tmath formula of 350 K. The discontinuity around 240 K lies well below Tmath formula , and is unconnected to a crystallographic phase change occurring at 170 K. Rather, it can be correlated with a gradual ordering of the ligand conformation as the temperature is raised. The other solid compounds either exhibit spin-crossover above room temperature (1 and (RS)-3), or remain high-spin between 5–300 K [(R)-2, (R)-4 and (RS)-4]. Homochiral (R)-3 and (R)-4 exhibit more twisted ligand conformations and coordination geometries than their heterochiral isomers, which can be attributed to steric clashes between ligand substituents [(R)-3]; or, between the isopropyl substituents of one ligand and the backbone of the other ((R)-4). In solution, (RS)-3 retains its structural integrity but (RS)-4 undergoes significant racemization through ligand redistribution by 1H NMR. (R)-4 and (RS)-4 remain high-spin in solution, whereas the other compounds all undergo spin-crossover equilibria. Importantly, Tmath formula for (R)-3 (244 K) is 34 K lower than for (RS)-3 (278 K) in CD3CN, which is the first demonstration of chiral discrimination between metal ion spin states in a molecular complex

A versatile electrolyte system for electrodeposition of p-block elements from single ohase supercritical CH2F2

For the first time, a versatile electrolyte bath is described that can be used to electrodeposit a wide range of p-block elements from supercritical difluoromethane (scCH2F2). The bath comprises the tetrabutylammonium chlorometallate complex of the element in an electrolyte of 50×10−3 mol dm−3 tetrabutylammonium chloride at 17.2 MPa and 358 K. Through the use of anionic ([GaCl4]−, [InCl4]−, [GeCl3]−, [SnCl3]−, [SbCl4]−, and [BiCl4]−) and dianionic ([SeCl6]2− and [TeCl6]2−) chlorometallate salts, the deposition of elemental Ga, In, Ge, Sn, Sb, Bi, Se, and Te is demonstrated. In all cases, with the exception of gallium, which is a liquid under the deposition conditions, the resulting deposits are characterised by SEM, energy-dispersive X-ray analysis, XRD and Raman spectroscopy. An advantage of this electrolyte system is that the reagents are all crystalline solids, reasonably easy to handle and not highly water or oxygen sensitive. The results presented herein significantly broaden the range of materials accessible by electrodeposition from supercritical fluid and open up the future possibility of utilising the full scope of these unique fluids to electrodeposit functional binary or ternary alloys and compounds of these elements

Diagnostics and the challenge of antimicrobial resistance: a survey of UK livestock veterinarians’ perceptions and practices

This is the author accepted manuscript. The final version is available from BMJ Publishing Group via the DOI in this recordBackground This paper explores the current role and place of diagnostic tests in the treatment of farm animal disease. With the growing focus on reduced reliance on antibiotic medicines in both animal and human patient care, attention is increasingly being focused on the practice, the technology and the function of diagnostic tests and how these can support responsible antimicrobial use. Emerging diagnostic technologies offer the possibility of more rapid testing for bacterial disease, while food chain actors and others are increasingly seeking to make diagnostic tests mandatory before the use of critically important antibiotics. Method This paper reports the findings of a recent large-scale online survey of UK farm animal veterinarians (n=153) which investigated current veterinary diagnostic practice with particular attention to the relationship between diagnostic test use and antibiotic treatment. Results Results revealed a range of factors that influence veterinary diagnostic practice and demonstrate the continuing importance of clinical observation and animal/herd knowledge in the selection of antibiotic treatment. Conclusion The findings identify a considerable ambivalence on the part of farm animal veterinarians regarding the current and future uses of rapid and point-of-care diagnostic tests as a means of improving clinical diagnosis and addressing inappropriate antibiotic medicine use.Economic and Social Research Council (ESRC

The Speciation of Homochiral and Heterochiral Diastereomers of Homoleptic Cobalt(II) and Zinc(II) PyBox Complexes

Homochiral [M((R)-LR)2]2+ and heterochiral [M((R)-LR)((S)-LR)]2+ isomers of [Zn(LPh)2][BF4]2, [Zn(LiPr)2][BF4]2, [Co(LPh)2][BF4]2, and [Co(LiPr)2][BF4]2 (LPh = 2,6-bis(4-phenyloxazolinyl)pyridine; LiPr = 2,6-bis(4-isopropyloxazolinyl)pyridine) have been prepared and characterised. Six of the eight compounds were crystallographically characterised, showing that steric repulsions between ligand substituents lead to more distorted coordination geometries in the homochiral isomers, especially in the LiPr complexes. Heterochiral [M((R)-LiPr)((S)-LiPr)]2+ (M = Zn or Co) undergoes partial racemisation in CD3CN through ligand redistribution reactions, whereas [M((R)-LPh)((S)-LPh)]2+ does not (in agreement with previous reports). This may be a consequence of intramolecular π... π - interactions in [M((R)-LPh)((S)-LPh)]2+, whereby each pyridyl group is sandwiched between two phenyl substituents from the other LPh ligand. These π... π -interactions are disrupted in homochiral [M((R)-LR)2]2+, owing to the aforementioned steric clash between phenyl substituents in that isomer

Factor Xa Generation by Computational Modeling: An Additional Discriminator to Thrombin Generation Evaluation

Factor (f)Xa is a critical enzyme in blood coagulation that is responsible for the initiation and propagation of thrombin generation. Previously we have shown that analysis of computationally generated thrombin profiles is a tool to investigate hemostasis in various populations. In this study, we evaluate the potential of computationally derived time courses of fXa generation as another approach for investigating thrombotic risk. Utilizing the case (n = 473) and control (n = 426) population from the Leiden Thrombophilia Study and each individual's plasma protein factor composition for fII, fV, fVII, fVIII, fIX, fX, antithrombin and tissue factor pathway inhibitor, tissue factor-initiated total active fXa generation was assessed using a mathematical model. FXa generation was evaluated by the area under the curve (AUC), the maximum rate (MaxR) and level (MaxL) and the time to reach these, TMaxR and TMaxL, respectively. FXa generation was analyzed in the entire populations and in defined subgroups (by sex, age, body mass index, oral contraceptive use). The maximum rates and levels of fXa generation occur over a 10- to 12- fold range in both cases and controls. This variation is larger than that observed with thrombin (3–6 fold) in the same population. The greatest risk association was obtained using either MaxR or MaxL of fXa generation; with an ∼2.2 fold increased risk for individuals exceeding the 90th percentile. This risk was similar to that of thrombin generation(MaxR OR 2.6). Grouping defined by oral contraceptive (OC) use in the control population showed the biggest differences in fXa generation; a >60% increase in the MaxR upon OC use. FXa generation can distinguish between a subset of individuals characterized by overlapping thrombin generation profiles. Analysis of fXa generation is a phenotypic characteristic which may prove to be a more sensitive discriminator than thrombin generation among all individuals

Identification of p.A684V missense mutation in the WFS1 gene as a frequent cause of autosomal dominant optic atrophy and hearing impairment

Optic atrophy (OA) and sensorineural hearing loss (SNHL) are key abnormalities in several syndromes, including the recessively inherited Wolfram syndrome, caused by mutations in WFS1 . In contrast, the association of autosomal dominant OA and SNHL without other phenotypic abnormalities is rare, and almost exclusively attributed to mutations in the Optic Atrophy-1 gene ( OPA1 ), most commonly the p.R445H mutation. We present eight probands and their families from the US, Sweden, and UK with OA and SNHL, whom we analyzed for mutations in OPA1 and WFS1 . Among these families, we found three heterozygous missense mutations in WFS1 segregating with OA and SNHL: p.A684V (six families), and two novel mutations, p.G780S and p.D797Y, all involving evolutionarily conserved amino acids and absent from 298 control chromosomes. Importantly, none of these families harbored the OPA1 p.R445H mutation. No mitochondrial DNA deletions were detected in muscle from one p.A684V patient analyzed. Finally, wolframin p.A684V mutant ectopically expressed in HEK cells showed reduced protein levels compared to wild-type wolframin, strongly indicating that the mutation is disease-causing. Our data support OA and SNHL as a phenotype caused by dominant mutations in WFS1 in these additional eight families. Importantly, our data provide the first evidence that a single, recurrent mutation in WFS1 , p.A684V, may be a common cause of ADOA and SNHL, similar to the role played by the p.R445H mutation in OPA1 . Our findings suggest that patients who are heterozygous for WFS1 missense mutations should be carefully clinically examined for OA and other manifestations of Wolfram syndrome. © 2011 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/84383/1/33970_ftp.pd

Polyphenoloxidase activity and total phenolic content as related to browning of minimally processed ‘Jonagored’ apple

Phenolic content, polyphenoloxidase (PPO) activity and browning have been reported by different authors to vary in different ways, depending on cultivar, picking maturity, storage conditions, etc. Numerous authors have attempted to correlate browning results with the phenolic content and/or enzymatic activity of apples, but data published in the literature are divergent as to which of the two factors, ie the enzyme or the substrate, plays the decisive role in the overall phenomenon of enzymatic browning. The aim of this work was to follow the PPO activity and phenolic content of minimally processed apple (cv ‘Jonagored’) during cold storage and to establish a potential relationship with enzymatic browning. Increasing storage time of minimally processed apple seemed to result in an increase in PPO activity. No changes (P > 0.05) in total phenolic content were observed during storage. Colour degradation of apple cubes, as indicated by changes in colour parameters, was found to be highly correlated with PPO activity. Browning of ‘Jonagored’ apple cubes during storage was found to be moderately correlated with PPO activity. No correlation was found between the browning index and the total phenolic content

Can precursors improve the transmission of energy at optical frequencies?

The recent interest in precursors has been fuelled by the possibility of using them for the efficient transmission of information through absorbing media at radio or optical frequencies. Here we demonstrate that the low attenuation experienced by the Brillouin precursor is attributed to the inherently low absorption of dispersive media near DC, a characteristic already exploited with communications systems using the extremely low frequency (ELF) band. Pulses, regardless of their temporal width and carrier frequency, always obey Beer's law as long as they propagate in the linear time invariant regime. We conclude with an FDTD simulation of the Maxwell–Bloch equations that shows how optical coherent bleaching effects, which take place in the linear time variant regime of the Lorentz oscillator model, can cause sustained deviations from Beer's law over relatively long distances of water

The negative association between pre-eclampsia and breast cancer risk may depend on the offspring's gender

If the negative association between pre-eclampsia and subsequent breast cancer risk differs by gender, this would strengthen the hypothesis that factors intrinsic to the particular pregnancy may explain the association. The study included 701 006 parous Norwegian women with follow-up for breast cancer through the Cancer Registry of Norway. Breast cancer risk was lower in women with pre-eclampsia/hypertension in their first pregnancy, compared to other women (relative risk, 0.86, 95% CI, 0.78–0.94), after adjustment for age at first birth, maternal birth year, length of gestation, marital status, and parity. The risk reduction was slightly greater if the woman delivered a son as opposed to a daughter (relative risks of 0.79 vs 0.94, P-value for interaction, 0.06), and if pre-eclampsia/hypertension was combined with pre-term delivery, these differences were more pronounced (relative risks, 0.62 vs 1.07, P-value for interaction 0.03). A subanalysis among 176 036 primiparous women showed a substantial risk reduction if the mother delivered a son (relative risk, 0.62, 95% CI, 0.47–0.82), but essentially null if she delivered a daughter (relative risk, 0.92, 95% CI, 0.72–1.18; P-value for interaction, 0.05). These results suggest that the effect of pre-eclampsia/hypertension may be attributed to factors associated with the particular pregnancy rather than an underlying biological trait of the mother. The stronger risk reduction related to having a son suggests a role for sex-dependent hormones in pregnancy

Stability and error analysis for a diffuse interface approach to an advection-diffusion equation on a moving surface

In this paper we analyze a fully discrete numerical scheme for solving a parabolic PDE on a moving surface. The method is based on a diffuse interface approach that involves a level set description of the moving surface. Under suitable conditions on the spatial grid size, the time step and the interface width we obtain stability and error bounds with respect to natural norms. Furthermore, we present test calculations that confirm our analysis