Novel polyoxometalates: Is antimony the new molybdenum?

Polyoxometalates based on Mo, W or V have been known for a long time and present a diverse range of structures, with the [XMo₁₂O₄₀]ⁿ⁻ Keggin ions (X = P, Si ,…) perhaps the best known.¹ They are still subject to intense research with >4000 papers published in the past five years. Following on from our study² of aryl arsonic acids RAsO₃H₂, which are straightforward molecular species based on four-coordinate As(V), we became interested in the corresponding antimony compounds. Although aryl stibonic acids of nominal formula RSbO₃H₂ have been known for over 100 years,³ their composition has remained uncertain, as they form only amorphous solids, have complicated titration behaviour and only limited solubility. The presumption has been that they are polymeric, based on 5- or 6-coordinate Sb with Sb-O-Sb linkages, though direct evidence is sparse.⁴ Recently, it has been shown by Beckman that if very bulky R groups are used, then relatively simple dimers such as (2,6-Mes₂C₆H₃Sb₂O₂(OH)₄(Mes=mesityl) can be isolated, but these represent a special case.

Arylstibonic acids [H₈(RSb)₁₂O₂₈]; precursors to organometallic isopolyoxostibonates [Na₂H₉(RSb)₁₂O₃₀]-, (R = aryl).

Electrospray ionisation mass spectrometry shows that arylstibonic acids, RSbO₃H₂, give rise to oxo-bridged clusters derived from [H₈(RSb)₁₂O₂₈] which act as inorganic crown ligands towards Na+ cations; structure determination of one derivative revealed a cage-like anion [Na₂H₉(p-O₂NC₆H₄Sb)₁₂O₃₀.4H₂O]-

Profitability and risk evaluation of novel perennial pasture systems for livestock producers in the high rainfall zone: Context, Approach and Preliminary Results

The decision to invest in pasture improvement raises various questions for the livestock grazier, with the most pertinent being about the potential returns and risks. In the high rainfall zone of south-west Victoria, researchers have trialled novel perennial pasture systems with the aim of substantially increasing on-farm profits whilst simultaneously improving environmental outcomes. Results from the Hamilton EverGraze® proof site have shown potential to greatly improve livestock production. Promotion of the pasture technology is the next step. Key to this process is developing information about profitability and risk regarding the decision to invest in the new pasture. To help meet this need a model of a representative mixed livestock farm system for the region has been developed to generate information about profit, cash wealth and risk to aid extension and help inform decisions. The farm is comprised of a wool and meat producing sheep system and a beef enterprise. Using the model, the performance of two of the novel pasture systems can be evaluated against current practice, and compared to determine which of the two is the most beneficial EverGraze® option for the future. The risk associated with the pasture decision is assessed by considering different price structures and seasonal outcomes, and evaluating these effects on net benefits. Discounted cash flows, net present values and internal rates of return are estimated for the alternative systems, which include the effects of this price and seasonal variability. Preliminary results have been calculated, however further work is needed to confirm these. The method and results of the analysis provide information that is valuable for farm decisions about investing in a new pasture system and provide a basis for future economic analyses at the case study site and elsewhere.Farm Management,

Identifying Sources of Fecal Pollution in the Roanoke River, Roanoke County, Virginia

Antibiotic Resistance Patterns (ARPs) of Enterococcus spp. were used as a phenotypic fingerprint to compare and categorize unknown-source isolates in an impaired segment of the Roanoke River, Roanoke County, Virginia. Antibiotic resistance analysis (ARA) of enterococci has been effectively used to differentiate among sources of fecal contamination in many geographic regions in the United States. Enterococcus spp. were used as a fecal indicator in a library consisting of 1,562 known-source isolates. Two-way analysis indicated that approximately 95% of the unknown-source isolates collected were of animal origin. A 3-way analysis indicated that 61% of the unknowns were of livestock origin while 34% were of wildlife origin. Of the isolates determined to be of wildlife origin, almost all were from raccoons and geese while enterococci from deer were present at low percentages. For one sample date, 20% of the isolates at one site were of human origin. This bacterial source tracking (BST) data will prove valuable for the development of TMDLs for this impaired waterway

In vitro aerodynamic characterization of the dose emitted during nebulization of tobramycin high strength solution by novel and jet nebulizer delivery systems

YesBackground: Chronic infections with Pseudomonas aeruginosa are a leading cause of morbidity in patients with cystic fibrosis (CF). The aim of tobramycin inhalation therapy in CF patients with chronic pulmonary infection is to deliver high amounts of drug directly to the site of infection. TOBI® is a tobramycin nebulizer solution (300 mg/5 ml) approved by FDA for maintenance therapy for patient with CF. The 20% tobramycin sulfate solution was reported as the optimal and maximal concentration. Methods: Nebulization of high strength tobramycin solution (20% tobramycin sulfate) (HSTS) has been assessed in this study by using different selected high performance nebulizer delivery systems: two different designs of jet nebulizers, and three new nebulizers based on vibrating mesh technology. The aerosol particle size distribution and output characteristics were measured for in vitro performance assessment of the nebulizer systems. The methodology was adapted from the current European standard, EN 13544-1:2001E. Results: The particle size distribution characteristic measurements showed that all tested nebulizers may be suitable for inhalation of HSTS. The mean (SD) of highest percentage of fine particles (<5 mm) was 77.64 (2.3) % for Sidestream®, at flow rate 16 L/min. The highest respirable inhaled mass was for Pari LC Plus® combined with PariBoyN® compressor, with mean (SD) 90.85 (8.6) mg. The mean (SD) of highest drug wastage percentage was 63.9 (3.9) % for Sidestream® jet nebulizer combined with compressed air cylinder at flow rate 16 L/min, while the lowest was 2.3 (0.26) % for NE-U22 Omron® (high frequency). Conclusions: The HSTS can be nebulized by all tested nebulisers but the high frequency NE-U22 Omron® and Aeroneb Go® are more efficient. When the HSTS compared to TOBI®, the respirable inhaled dose was increased to more than 73%

In vitro Performance Assessment of Recent Nebuliser Delivery Systems for Nebulisation of Approved Aerosolised Tobramycin (TOBI)®

YesTOBI® is a recently marketed preservative and sulphate free tobramycin formulation approved by FDA for maintenance therapy for patient with cystic fibrosis. The performance of selected recent nebuliser delivery systems has been assessed using the developed method to determine the optimum combinations to deliver approved tobramycin inhaled solution (TOBI)®. A simple, sensitive and specific high performance liquid chromatographic method has been developed and used to quantitative determination of the aminoglycoside tobramycin following pre-column derivatisation with phenylisocyanate (PIC). The reaction time was 10 min at 80º C and the resulting derivative was stable for five days at room temperature. The quantitative performance of the assay was further improved by using another aminoglycoside (neomycin) as internal standard. The stable resulting PIC-tobramycin derivative was separated using a HPLC 5μm Columbus C18 column (150x4.60 mm i.d, Phenomenex). The mobile phase was consisted of acetonitrile-glacial acetic acid-water (450:5:545, v/v/v) and ultraviolet detection at (240 nm). The proposed method showed good validation data. The standard curve was linear (n=5) at seven different concentrations, ranging from 20 to 140μg/ml and the correlation coefficient (R2) of the regression line was 0.9995. The limit of detection (LOD) and limit of quantitation (LOQ) were 0.86μg/ml and 2.62μg/ml, respectively. The relative standard deviation (RSD %) was less than 0.6% for intra-day assay (n=5) and 2.5% for inter-day assay (n=5). A number of nebuliser performance comparison studies have been demonstrated for aerosolise TOBI® to choice the optimum combination produces high repirable inhaled mass of tobramycin. The objective of this study was to evaluate the performance of recent nebuliser delivery systems to nebulise approved tobramycin inhaled solution (TOBI)®

Physiological Response to Feeding in Little Penguins

© 2006 by The University of Chicago.Specific dynamic action (SDA), the increase in metabolic rate above resting levels that accompanies the processes of digestion and assimilation of food, can form a substantial part of the daily energy budget of free-ranging animals. We measured heart rate (fH) and rate of oxygen consumption ( ) in 12 little penguins while they digested a meal of sardines in order to determine whether they show specific dynamic action. In contrast to some studies of other penguin species, little penguins showed a substantial SDA, the magnitude of which was proportional to the size of the meal. The energy utilized in SDA was equivalent to 13.4% of the available energy content of the fish. Furthermore, animals such as penguins that forage in a cold environment will probably expend further energy in heating their food to body temperature to facilitate efficient digestion. It is estimated that this additional energy expenditure was equivalent to 1.6%-2.3% of the available energy content of the fish, depending on the time of year and therefore the temperature of the water. Changes in fH during digestion were qualitatively similar to those in , implying that there were no substantial circulatory adjustments during digestion and that the relationship between fH and in penguins is unaffected by digestive state

Social patterns and differentials in the fertility transition in the context of HIV/AIDS: evidence from population surveillance, rural South Africa, 1993 - 2013.

BACKGROUND: Literature is limited on the effects of high prevalence HIV on fertility in the absence of treatment, and the effects of the introduction of sustained access to antiretroviral therapy (ART) on fertility. We summarize fertility patterns in rural northeast South Africa over 21 years during dynamic social and epidemiological change. METHODS: We use data for females aged 15-49 from the Agincourt health and socio-demographic surveillance system (1993-2013). We use discrete time event history analysis to summarize patterns in the probability of any birth. RESULTS: Overall fertility declined in 2001-2003, increased in 2004-2011, and then declined in 2012-2013. South Africans showed a similar pattern. Mozambicans showed a different pattern, with strong declines prior to 2003 before stalling during 2004-2007, and then continued fertility decline afterwards. There was an inverse gradient between fertility levels and household socioeconomic status. The gradient did not vary by time or nationality. CONCLUSIONS: The fertility transition in rural South Africa shows a pattern of decline until the height of the HIV/AIDS pandemic, with a resulting stall until further decline in the context of ART rollout. Fertility patterns are not homogenous among groups

Parametric study of solar thermal rocket nozzle performance

This paper details a numerical investigation of performance losses in low-thrust solar thermal rocket nozzles. The effects of nozzle geometry on three types of losses were studied; finite rate dissociation-recombination kinetic losses, two dimensional axisymmetric divergence losses, and compressible viscous boundary layer losses. Short nozzle lengths and supersonic flow produce short residence times in the nozzle and a nearly frozen flow, resulting in large kinetic losses. Variations in geometry have a minimal effect on kinetic losses. Divergence losses are relatively small, and careful shaping of the nozzle can nearly eliminate them. The boundary layer in these small nozzles can grow to a major fraction of nozzle radius, and cause large losses. These losses are attributed to viscous drag on the nozzle walls and flow blockage by the boundary layer, especially in the throat region. Careful shaping of the nozzle can produce a significant reduction in viscous losses