4-(2,5-Dioxo-2,5-dihydro-1H-pyrrol-1-yl)benzoic acid: X-ray and DFT-calculated structure

In the title compound, C(11)H(7)NO(4), there is a dihedral angle of 45.80 (7)degrees between the planes of the benzene and maleimide rings. The presence of O-H...O hydrogen bonding and weak C-H...O interactions allows the formation of R (3) 3(19) edge-connected rings parallel to the (010) plane. Structural, spectroscopic and theoretical studies were carried out. Density functional theory (DFT) optimized structures at the B3LYP/6-311 G(d,p) and 6-31++G(d,p) levels are compared with the experimentally determined molecular structure in the solid state. Additional IR and UV theoretical studies allowed the presence of functional groups and the transition bands of the system to be identified.

Validation of a Brazilian Portuguese Version of the Walking Estimated-Limitation Calculated by History (WELCH)

Abstract Background: The Walking Estimated-Limitation Calculated by History (WELCH) questionnaire has been proposed to evaluate walking impairment in patients with intermittent claudication (IC), presenting satisfactory psychometric properties. However, a Brazilian Portuguese version of the questionnaire is unavailable, limiting its application in Brazilian patients. Objective: To analyze the psychometric properties of a translated Brazilian Portuguese version of the WELCH in Brazilian patients with IC. Methods: Eighty-four patients with IC participated in the study. After translation and back-translation, carried out by two independent translators, the concurrent validity of the WELCH was analyzed by correlating the questionnaire scores with the walking capacity assessed with the Gardner treadmill test. To determine the reliability of the WELCH, internal consistency and test–retest reliability with a seven-day interval between the two questionnaire applications were calculated. Results: There were significant correlations between the WELCH score and the claudication onset distance (r = 0.64, p = 0.01) and total walking distance (r = 0.61, p = 0.01). The internal consistency was 0.84 and the intraclass correlation coefficient between questionnaire evaluations was 0.84. There were no differences in WELCH scores between the two questionnaire applications. Conclusion: The Brazilian Portuguese version of the WELCH presents adequate validity and reliability indicators, which support its application to Brazilian patients with IC.

Tenofovir use is associated with a reduction in calculated glomerular filtration rates in the Swiss HIV Cohort Study.

BACKGROUND: A growing number of case reports have described tenofovir (TDF)-related proximal renal tubulopathy and impaired calculated glomerular filtration rates (cGFR). We assessed TDF-associated changes in cGFR in a large observational HIV cohort. METHODS: We compared treatment-naive patients or patients with treatment interruptions > or = 12 months starting either a TDF-based combination antiretroviral therapy (cART) (n = 363) or a TDF-sparing regime (n = 715). The predefined primary endpoint was the time to a 10 ml/min reduction in cGFR, based on the Cockcroft-Gault equation, confirmed by a follow-up measurement at least 1 month later. In sensitivity analyses, secondary endpoints including calculations based on the modified diet in renal disease (MDRD) formula were considered. Endpoints were modelled using pre-specified covariates in a multiple Cox proportional hazards model. RESULTS: Two-year event-free probabilities were 0.65 (95% confidence interval [CI] 0.58-0.72) and 0.80 (95% CI 0.76-0.83) for patients starting TDF-containing or TDF-sparing cART, respectively. In the multiple Cox model, diabetes mellitus (hazard ratio [HR] = 2.34 [95% CI 1.24-4.42]), higher baseline cGFR (HR = 1.03 [95% CI 1.02-1.04] by 10 ml/min), TDF use (HR = 1.84 [95% CI 1.35-2.51]) and boosted protease inhibitor use (HR = 1.71 [95% CI 1.30-2.24]) significantly increased the risk for reaching the primary endpoint. Sensitivity analyses showed high consistency. CONCLUSION: There is consistent evidence for a significant reduction in cGFR associated with TDF use in HIV-infected patients. Our findings call for a strict monitoring of renal function in long-term TDF users with tests that distinguish between glomerular dysfunction and proximal renal tubulopathy, a known adverse effect of TDF.

How does the body-scale model affect back-calculated growth: the example of arctic charr Salvelinus alpinus (L.) of Lake Geneva (Switzerland)

When back-calculating fish length from scale measurements, the choice of the body-scale relationship is a fundamental step. Using data from the arctic charrSalvelinus alpinus (L.) of Lake Geneva (Switzerland) we show the need for a curvilinear model, on both statistical and biological grounds. From several 2-parameters models, the log-linear relationship appears to provide the best fit. A 3-parameters, Bertalanffy model did not improve the fit. We show moreover that using the proportional model would lead to important misinterpretations of the data.

Basicities of primary arylamines and calculated amine nitrogen electronic charges

Mülliken charges on nitrogen atoms were calculated for several arylamines, utilizing the AM1 Quantum Chemistry method, relating their values to experimental amine pKa . Direct relation between pKa and nitrogen charges was found. The amines energies of protonation, calculated by the same method, also correlate directly with these charges.

Chemical indexes calculated for 8,11,13-trien-abietane diterpenoids isolated from Swartzia species

The disparity found in the molecular structures of compounds isolated from nine plants of the Swartzia genus indicates that the Swartzia species that furnished cassane diterpenoids and triterpenoidal saponins are more recent, since these metabolites have adopted the mevalonic acid route of formation, abandoning the shikimic acid/acetate route that produces the isoflavonoids found in the remaining species. Chemical indexes calculated from the molecular structure diversities of sixteen 8,11,13-trien-abietane diterpenoids isolated from Swartzia langsdorffii and S. arborescens indicate that S. arborescens is more recent than S. langsdorffii. The results suggest a more evolved position in Swartzia species of the section Possira.

Map illustrating the site of the harbours for the proposed Obi-railway : the soundings are all calculated in feet and are based upon the data of the Russian Marine Ministry : the underlined figures are soundings taken by the scooner Bakan, 1887

Kartta kuuluu A. E. Nordenskiöldin kokoelmaan

The Columbian Orator : containing a variety of original and selected pieces ; together with rules ; calculated to improve youth and othersin the ornamental and useful art of eloquence

UANL

Can climate trends be calculated from reanalysis data?

Several global quantities are computed from the ERA40 reanalysis for the period 1958-2001 and explored for trends. These are discussed in the context of changes to the global observing system. Temperature, integrated water vapor (IWV), and kinetic energy are considered. The ERA40 global mean temperature in the lower troposphere has a trend of +0.11 K per decade over the period of 1979-2001, which is slightly higher than the MSU measurements, but within the estimated error limit. For the period 1958 2001 the warming trend is 0.14 K per decade but this is likely to be an artifact of changes in the observing system. When this is corrected for, the warming trend is reduced to 0.10 K per decade. The global trend in IWV for the period 1979-2001 is +0.36 mm per decade. This is about twice as high as the trend determined from the Clausius-Clapeyron relation assuming conservation of relative humidity. It is also larger than results from free climate model integrations driven by the same observed sea surface temperature as used in ERA40. It is suggested that the large trend in IWV does not represent a genuine climate trend but an artifact caused by changes in the global observing system such as the use of SSM/I and more satellite soundings in later years. Recent results are in good agreement with GPS measurements. The IWV trend for the period 1958-2001 is still higher but reduced to +0.16 mm per decade when corrected for changes in the observing systems. Total kinetic energy shows an increasing global trend. Results from data assimilation experiments strongly suggest that this trend is also incorrect and mainly caused by the huge changes in the global observing system in 1979. When this is corrected for, no significant change in global kinetic energy from 1958 onward can be found.

Is the OECD acute worm toxicity test environmentally relevant? The effect of mineral form on calculated lead toxicity

In a series of experiments the toxicity of lead to worms in soil was determined following the draft OECD earthworm reproduction toxicity protocol except that lead was added as solid lead nitrate, carbonate and sulphide rather than as lead nitrate solution as would normally be the case. The compounds were added to the test soil to give lead concentrations of 625-12500 pg Pb g-1 of soil. Calculated toxicities of the lead decreased in the order nitrate > carbonate > sulphide, the same order as the decrease in the solubility of the metal compounds used. The 7-day LC50 (lethal concentration when 50% of the population is killed) for the nitrate was 5321 +/- 275 mug Pb g(-1) of soil and this did not change with time. The LC50 values for carbonate and sulphide could not be determined at the concentration ranges used. The only parameter sensitive enough to distinguish the toxicities of the three compounds was cocoon (egg) production. The EC50S for cocoon production (the concentration to produce a 50% reduction in cocoon production) were 993, 8604 and 10 246 mug Pb g(-1) of soil for lead nitrate, carbonate and sulphide, respectively. Standard toxicity tests need to take into account the form in which the contaminant is present in the soil to be of environmental relevance. (C) 2002 Elsevier Science Ltd. All rights reserved.

Calculated rotational and rovibrational spectra of D2S and HDS

Rovibrational energy levels, transition frequencies, and linestrengths are computed variationally for the sulfur hydrides D2S and HDS, using ab initio potential energy and dipole surfaces. Wave-numbers for the pure rotational transitions agree to within 0.2 cm−1 of the experimental lines. For the fundamental vibrational transitions, the band origins for D2S are 860.4, 1900.6, and 1912.0 cm−1 for ν2, ν1, and ν3, respectively, compared with the corresponding experimental values of 855.4, 1896.4, and 1910.2 cm−1. For HDS, we compute ν2 to be 1039.4 cm−1, compared with the experimental value of 1032.7 cm−1. The relative merits of local and normal mode descriptions for the overtone stretching band origins are discussed. Our results confirm the local mode nature of the H2S, D2S, and HDS system.

The influence of carbon surface oxygen groups on Dubinin–Astakhov equation parameters calculated from CO2 adsorption isotherm

We present the results of a systematic study of the influence of carbon surface oxidation on Dubinin–Astakhov isotherm parameters obtained from the fitting of CO2 adsorption data. Using GCMC simulations of adsorption on realistic VPC models differing in porosity and containing the most frequently occurring carbon surface functionalities (carboxyls, hydroxyls and carbonyls) and their mixtures, it is concluded that the maximum adsorption calculated from the DA model is not strongly affected by the presence of oxygen groups. Unfortunately, the same cannot be said of the remaining two parameters of this model i.e. the heterogeneity parameter (n) and the characteristic energy of adsorption (E0). Since from the latter the pore diameters of carbons are usually calculated, by inverse-type relationships, it is concluded that they are questionable for carbons containing surface oxides, especially carboxyls.