Addition reactions of Hypohalous acids and halogens with halogen-substituted - olefins

The reaction between hypochlorous acid and 2-chloropropene was studied. The products were analysed as chloroacetone (85^t) and 2,3-dicliloropropene (15%). The absence of any 2, 2-dich.loropropanol, formed by nucleophilic attack of water at the terminal carbon atom, is discussed in terms of polarisation of the molecule caused by electron-release from the 2-ciiloro substituent. The formation of 2,3-dichloropropene by proton-loss in the carbonium ion from C-3 (rather than of 1,2-dichloropropene formed by loss from C-l) is explained in terms of steric strain. The effect of silver ions on the course of the reaction was also studied. A product analysis revealed no change in the yield of chloroacetone, nor any sign of any unusual products. The kinetics were also unaffected by the presence of silver ions. This behaviour contrasts with that of 2,3-dichloropropene, where silver ions have been found to cause autocatalytic behaviour, and to be responsible for abnormal products. The kinetics of 2-chloroprop-2-en-l-ol were studied, and found to show characteristics midway between the other 2-chloro compounds. When radioactively labelled hypochlorous acid was used in the addition reaction, the chloroacetone produced was found to contain less than the full activity, showing that some chlorine exchange takes place. The extent of the exchange was found to be reduced by the presence of increasing concentrations of silver ions. In a series of experiments in aqueous acid solution chloride, bromide and iodide ions were added to hypochlorous acid in the presence of silver ions. Exchange was found to occur, to an increasing extent along the series chloride - bromide - iodide, and to a decreasing extent with increasing silver ion concentration. The rate of exchange between hypochlorous acid and silver chloride was found to be slow, of the same order as that between chloride ion and silver chloride. There was very little exchange between chloride ion and hypobromous acid. The 2,3-dichloropropene produced in the reaction between hypochlorous acid and 2-chloropropene was found to be of the same specific activity the chloroacetone, and to be exclusively 3-labelled, The conclusion was reached that the chlorine exchange in the addition reaction proceeded by an inter- rather than an intra-molecular mechanism. The addition of hypochlorous acid to 2-bromopropene resulted in the production of some broooacetone, as expected. The kinetics of the addition of iodine in aqueous solution t6 the series of terminally substituted 1- alkenes CH(_2) = CH(CH(_2)(_n)Br were followed, A rate maximum at n = 3 appeared to indicate bromine participation in a 5_membered ring, although calculations based on the fall-off of inductive effect with the progressive removal of the bromo substituent from the reaction centre showed the effect not to be very large

Algal dynamics in tropical riverine water holes

Microalgae are key components of many aquatic food webs and of aquatic biodiversity, yet little is known of the dynamics of algal assemblages in tropical systems, where diversity is likely to be very high. This study investigated algal assemblages of remnant riparian water holes in the seasonal Australian tropics, and the natural and human influences on them. Phytoplankton and water sample sand in situ physico-chemical data were collected from sites in the Burdekin River catchment, one of the largest in tropical Australia. Sites in the catchment were chosen based on differing water chemistry and turbidity. Samples were collected at three times during the day (dawn, midday, afternoon) in two microhabitats within the waterhole (open water and macrophytes) at varying times within the year representing the wet and dry seasons and the change between seasons. Multivariate analyses demonstrated compositional differences between assemblages between seasons and rivers and showed that conductivity and turbidity were major physico-chemical determinants of the differences. Majority of the sites showed dominance in Chlorophyta, followed by Cyanophyta and Heterokontophyta (Bacillariophyceae). The differences related both to natural geological and edaphic factors and to land management regimes in the catchment. The results provide improved understanding of algal dynamics in seasonal tropical rivers and will be used to create models for site-specific assessment of water quality in a regional monitoring program

An automotive engine charge-air intake conditioner system: analysis of fuel economy benefits in a gasoline engine application

A combination of analytical techniques has been used to quantify the potential fuel economy benefits of an automotive engine charge-air intake conditioner system applied to a spark-ignited gasoline engine. This system employs a compressor, intercooler, and expander to provide increased charge density with the possibility of reducing charge-air temperature below sink temperature. This reduction in charge-air temperature provides the potential for improved knock resistance at full load; thereby allowing the possibility of increasing compression ratio with corresponding benefits in thermodynamic cycle efficiency and part-load fuel economy. The four linked and interfaced models comprised a first-law thermodynamic model of the charge-air conditioner system, a one-dimensional engine cycle simulation, a two-zone combustion model, and a knock criterion model. An analysis was carried out under full load at 3000 r/min and showed that a charge-air conditioner system - with compressor, intercooler, and expander efficiencies of 0.8 - allowed the compression ratio to be increased by approximately half a ratio, which gave up to 1.5 per cent reduction in brake specific fuel consumption at 2000 r/min 2 bar brake mean effective pressure when compared with a conventional pressure charger intercooler system with no expander

An automotive engine charge-air intake conditioner system: thermodynamic analysis of performance characteristics

A first law thermodynamic model has been developed and used to characterize the performance of an automotive engine charge-air intake conditioner system. This system employs a compressor, intercooler, and expander to provide increased charge density with the possibility of reducing, the charge-air temperature below the sink temperature. The model was validated against experimental measurements. The variation of system effectiveness with compressor, intercooler, and expander efficiency was quantified and system operating limits were identified. While the expander was found to have a greater effect than the compressor, the performance of the system was shown to be most dependent upon intercooler effectiveness

Micro-computed tomographic analysis of the radial geometry of intrarenal artery-vein pairs in rats and rabbits: Comparison with light microscopy

We assessed the utility of synchrotron-radiation micro-computed tomography (micro-CT) for quantification of the radial geometry of the renal cortical vasculature. The kidneys of nine rats and six rabbits were perfusion fixed and the renal circulation filled with Microfil. In order to assess shrinkage of Microfil, rat kidneys were imaged at the Australian Synchrotron immediately upon tissue preparation and then post fixed in paraformaldehyde and reimaged 24 hours later. The Microfil shrank only 2-5% over the 24 hour period. All subsequent micro-CT imaging was completed within 24 hours of sample preparation. After micro-CT imaging, the kidneys were processed for histological analysis. In both rat and rabbit kidneys, vascular structures identified in histological sections could be identified in two-dimensional (2D) micro-CT images from the original kidney. Vascular morphology was similar in the two sets of images. Radial geometry quantified by manual analysis of 2D images from micro-CT was consistent with corresponding data generated by light microscopy. However, due to limited spatial resolution when imaging a whole organ using contrast-enhanced micro-CT, only arteries ≥100 and ≥60 μm in diameter, for the rat and rabbit respectively, could be assessed. We conclude that it is feasible and valid to use micro-CT to quantify vascular geometry of the renal cortical circulation in both the rat and rabbit. However, a combination of light microscopic and micro-CT approaches are required to evaluate the spatial relationships between intrarenal arteries and veins over an extensive range of vessel size

The Five Factor Model of personality and evaluation of drug consumption risk

The problem of evaluating an individual's risk of drug consumption and misuse is highly important. An online survey methodology was employed to collect data including Big Five personality traits (NEO-FFI-R), impulsivity (BIS-11), sensation seeking (ImpSS), and demographic information. The data set contained information on the consumption of 18 central nervous system psychoactive drugs. Correlation analysis demonstrated the existence of groups of drugs with strongly correlated consumption patterns. Three correlation pleiades were identified, named by the central drug in the pleiade: ecstasy, heroin, and benzodiazepines pleiades. An exhaustive search was performed to select the most effective subset of input features and data mining methods to classify users and non-users for each drug and pleiad. A number of classification methods were employed (decision tree, random forest, $k$-nearest neighbors, linear discriminant analysis, Gaussian mixture, probability density function estimation, logistic regression and na{\"i}ve Bayes) and the most effective classifier was selected for each drug. The quality of classification was surprisingly high with sensitivity and specificity (evaluated by leave-one-out cross-validation) being greater than 70\% for almost all classification tasks. The best results with sensitivity and specificity being greater than 75\% were achieved for cannabis, crack, ecstasy, legal highs, LSD, and volatile substance abuse (VSA).Comment: Significantly extended report with 67 pages, 27 tables, 21 figure

Atenolol versus losartan in children and young adults with Marfan's syndrome

BACKGROUND : Aortic-root dissection is the leading cause of death in Marfan's syndrome. Studies suggest that with regard to slowing aortic-root enlargement, losartan may be more effective than beta-blockers, the current standard therapy in most centers. METHODS : We conducted a randomized trial comparing losartan with atenolol in children and young adults with Marfan's syndrome. The primary outcome was the rate of aortic-root enlargement, expressed as the change in the maximum aortic-root-diameter z score indexed to body-surface area (hereafter, aortic-root z score) over a 3-year period. Secondary outcomes included the rate of change in the absolute diameter of the aortic root; the rate of change in aortic regurgitation; the time to aortic dissection, aortic-root surgery, or death; somatic growth; and the incidence of adverse events. RESULTS : From January 2007 through February 2011, a total of 21 clinical centers enrolled 608 participants, 6 months to 25 years of age (mean [+/- SD] age, 11.5 +/- 6.5 years in the atenolol group and 11.0 +/- 6.2 years in the losartan group), who had an aorticroot z score greater than 3.0. The baseline-adjusted rate of change (+/- SE) in the aortic-root z score did not differ significantly between the atenolol group and the losartan group (-0.139 +/- 0.013 and -0.107 +/- 0.013 standard-deviation units per year, respectively; P = 0.08). Both slopes were significantly less than zero, indicating a decrease in the degree of aortic-root dilatation relative to body-surface area with either treatment. The 3-year rates of aortic-root surgery, aortic dissection, death, and a composite of these events did not differ significantly between the two treatment groups. CONCLUSIONS : Among children and young adults with Marfan's syndrome who were randomly assigned to losartan or atenolol, we found no significant difference in the rate of aorticroot dilatation between the two treatment groups over a 3-year period

phosphorus and potassium fertilizer effects on alfalfa and soil in a non limited soil

Fertilization strategies for high-yielding alfalfa (Medicago sativa L.) should take in account the increase in soil nutritional status that occurred during the last decades in areas with intensive agricultural use. A field study was conducted at the University of Padova, northeastern Italy, to determine the response of alfalfa yield and nutritive value to various combinations of P and K rates in a soil lacking nutrient deficiency. Alfalfa cultivar Delta was seeded in March 2005 on a silt loam soil having 38 mg kg -1 available P and 178 mg kg -1 exchangeable K. Nine treatments deriving from the combination of three P fertilization rates (0, 100, and 200 kg ha -1 P 2 O 5 ) and three K rates (0, 300, and 600 kg ha -1 K 2 O) were compared in a randomized complete block design. Plots were harvested at bud stage during three growing seasons (2005-2007) and dry matter (DM) yield, forage nutritive value, P and K contents, canopy height, and stem density were measured at each harvest. Soil samples were collected at the end of the research period for determination of available P and exchangeable K. The results demonstrated that P application had no impact on yield and did not interact with K in determining productivity, while K had a positive effect on yield. However, the 300 kg ha -1 K 2 O rate appeared sufficient to maximize yield, without adverse effects on the forage nutritive value. Data from soil analyses showed that alfalfa has a high K uptake even when it is fertilized at high rates

Attempted suicide in Sri Lanka –An epidemiological study of household and community factors

An individual's suicide risk is determined by personal characteristics, but is also influenced by their environment. Previous studies indicate a role of contextual effects on suicidal behaviour, but there is a dearth of quantitative evidence from Asia.Individual and community level data were collected on 165,233 people from 47,919 households in 171 communities in rural Sri Lanka. Data were collected on individual (age, sex, past suicide attempts and individual socioeconomic position (SEP)) and household (household SEP, pesticide access, alcohol use and multigenerational households) level factors. We used 3-level logit models to investigate compositional (individual) and contextual (household/community) effects.We found significant variation between households 21% (95% CI 18%, 24%) and communities 4% (95% CI 3%, 5%) in the risk of a suicide attempt. Contextual factors as measured by low household SEP (OR 2.37 95% CI 2.10, 2.67), low community SEP (OR 1.45 95% CI 1.21, 1.74), and community 'problem' alcohol use (OR 1.44 95% CI 1.19, 1.75) were associated with an increased risk of suicide attempt. Women living in households with alcohol misuse were at higher risk of attempted suicide. We observed a protective effect of living in multigenerational households (OR 0.53 95% CI 0.42, 0.65).The outcome was respondent-reported and refers to lifetime reports of attempted suicide, therefore this study might be affected by socially desirable responding.Our study finds that contextual factors are associated with an individual's risk of attempted suicide in Sri Lanka, independent of an individual's personal characteristics

Archaeological signatures of landscape and settlement change on the Isle of Harris

Between 2004 and 2011, a programme of archaeological investigation by the University of Birmingham on the Isle of Harris, a distinctive island forming part of the Western Isles of Scotland, has allowed the archaeological remains of this enigmatic place to be further characterised and understood. Despite intensive archaeological interest in the archipelago for a number of decades, the Isle of Harris has been overlooked and only now are we beginning to identify the archaeological resource and make comparisons to the wealth of published data from islands such as the Uists, Barra and Lewis. This paper highlights some generic overall patterns of archaeological signatures on the Isle which has been identified through a range of archaeological methods including field walking, intrusive excavation, aerial reconnaissance, geophysical and topographical survey, and documentary research. Several key case studies will be introduced including upland shieling complexes and mulitperiod settlement sites on the west coast machair systems. The purpose of the paper is not to present a gazetteer of the results of the work to date, but to highlight some of the key findings with a view to demonstrating that the Isle of Harris is directly comparable with the archaeologically rich landscapes of the other islands