2,794,417 research outputs found
An electron-deficient triosmium cluster containing the thianthrene ligand: Synthesis, structure and reactivity of [Osâ(CO)â(Îź3-Ρ2-CââHâSâ)(Îź-H)]
Reaction of [Osâ(CO)ââ(CHâCN)â] with thianthrene at 80 °C leads to the nonacarbonyl dihydride compound [Osâ(CO)â(Îź-3,4-Ρ²-CââHâSâ)(Îź-H)â] (1) and the 46-electron monohydride compound [Osâ(CO)â(Îźâ-Ρ²-CââHâSâ)(Îź-H)] (2). Compound 2 reacts reversibly with CO to give the CO adduct [Osâ(CO)ââ(Îź-Ρ²-CââHâSâ)(Îź-H)] (3) whereas with PPhâ it gives the addition product [Osâ(CO)â)(PPhâ)(Îź-Ρ²-CââHâSâ)(Îź-H)] (4) as well as the substitution product 1,2-[Osâ(CO)ââ ((PPhâ)â] (5) Compound 2 represents a unique example of an electron-deficient triosmium cluster in which the thianthrene ring is bound to cluster by coordination of the sulfur lone pair and a three-center-two-electron bond with the C(2) carbon which bridges the same edge of the triangle as the hydride. Electrochemical and DFT studies which elucidate the electronic properties of 2 are reported
Asymptotically scale-invariant occupancy of phase space makes the entropy Sq extensive
Phase space can be constructed for equal and distinguishable subsystems
that could be (probabilistically) either {\it weakly} (or {\it "locally"})
correlated (e.g., independent, i.e., uncorrelated), or {\it strongly} (or {\it
globally}) correlated. If they are locally correlated, we expect the
Boltzmann-Gibbs entropy to be {\it
extensive}, i.e., for . In particular, if
they are independent, is {\it strictly additive}, i.e., . However, if the subsystems are globally correlated, we
expect, for a vast class of systems, the entropy (with ) for some special value of to be the
one which extensive (i.e., for ).Comment: 15 pages, including 9 figures and 8 Tables. The new version is
considerably enlarged with regard to the previous ones. New examples and new
references have been include
Cleavage of GeâS and CâH bonds in the reaction of electron-deficient [Osâ(CO)â(Îź-H)(Îźâ-PhâPCHâP(Ph)CâHâ)] with PhâGeSPh: Generation of thiophenol derivatives [Osâ(CO)â(Îź-H)(Îź-SPh)(Îź-dppm)] and [Osâ(CO)â(Îź-H)(Îź-SPh)(Îźâ-SCâHâ)(Îź-dppm)]
Heating the electron-deficient [Osâ(CO)â(Îź-H)(Îźâ-PhâPCHâP(Ph)CâHâ)] (1) and PhâGeSPh in benzene at 80 °C led to the thiolato bridged compounds, [Osâ(CO)â(Îź-H)(Îź-SPh)(Îź-dppm)] (2) and [Osâ(CO)â(Îź-H)(Îź-SPh)(Îźâ-SCâHâ)(Îź-dppm)] (3), formed by cleavage of GeâS and CâS bonds of the ligand, in 40% and 17% yields, respectively. Both compounds 2 and 3 have been characterized by a combination of elemental analysis, infrared and šH NMR spectroscopic data together with single crystal X-ray crystallography. Compound 3 contains an open triangle of osmium atoms bridged by a SPh and SCâHâ ligands on opposite sides of the cluster with a dppm ligand bridging one of the OsâOs edges. Compound 2 consists of a closed triangular cluster of osmium atoms with a bridging SPh, and a bridging hydride ligand on the same OsâOs edge, and a dppm ligand bridging one of the remaining OsâOs edges
MRI radiomic features are independently associated with overall survival in soft tissue sarcoma
Purpose: Soft tissue sarcomas (STS) represent a heterogeneous group of diseases, and selection of individualized treatments remains a challenge. The goal of this study was to determine whether radiomic features extracted from magnetic resonance (MR) images are independently associated with overall survival (OS) in STS.
Methods and Materials: This study analyzed 2 independent cohorts of adult patients with stage II-III STS treated at center 1 (N = 165) and center 2 (N = 61). Thirty radiomic features were extracted from pretreatment T1-weighted contrast-enhanced MR images. Prognostic models for OS were derived on the center 1 cohort and validated on the center 2 cohort. Clinical-only (C), radiomics-only (R), and clinical and radiomics (C+R) penalized Cox models were constructed. Model performance was assessed using Harrell\u27s concordance index.
Results: In the R model, tumor volume (hazard ratio [HR], 1.5) and 4 texture features (HR, 1.1-1.5) were selected. In the C+R model, both age (HR, 1.4) and grade (HR, 1.7) were selected along with 5 radiomic features. The adjusted c-indices of the 3 models ranged from 0.68 (C) to 0.74 (C+R) in the derivation cohort and 0.68 (R) to 0.78 (C+R) in the validation cohort. The radiomic features were independently associated with OS in the validation cohort after accounting for age and grade (HR, 2.4;
Conclusions: This study found that radiomic features extracted from MR images are independently associated with OS when accounting for age and tumor grade. The overall predictive performance of 3-year OS using a model based on clinical and radiomic features was replicated in an independent cohort. Optimal models using clinical and radiomic features could improve personalized selection of therapy in patients with STS
Effect of anti-retroviral therapy on oxidative stress in hospitalized HIV-infected adults with and without TB.
BackgroundHIV infection and opportunistic infections cause oxidative stress (OS), which is associated with tissue damage. Anti-retroviral therapy (ART) is used to treat HIV and decrease the risk of opportunistic infections, but it is unclear whether ART reduces OS. Association of ART with OS was investigated.MethodsWe stratified a convenience sample of frozen serum or plasma from HIV-infected, ART-naĂŻve (n=21); HIV-infected, ART-treated (n=14); HIV and PTB co-infected, ART-naĂŻve (n=21); HIV and PTB co-infected, ART-treated (n=25) patients. Controls (n=21) were HIV-negative adults without TB symptoms. Concentration of OS markers namely: transaminases (ALT and AST), gamma glutamyl transpeptidase (GGT), albumin, total protein, malondialdehyde (MDA), vitamin C, and total anti-oxidant status (TAS) were determined.ResultsAST (p<0.001), GGT (p<0.001), total protein (p=0.001) and MDA (p<0.001) were higher in HIV patients compared to controls. Vitamin C (P<0.0001) and albumin (p<0.01) were lower in HIV-patients relative to controls. ART was only associated with higher albumin (p=0.001), higher GGT (p=0.02) and lower vitamin C (p=0.009). HIV and PTB co-infection was only significantly associated with higher GGT (p=0.01) and AST (p=0.03).ConclusionWe identified severe OS among HIV-patients. ART was associated with both increased and reduced markers of OS hence suggesting that ART may not attenuate OS
Preclinical Toxicity Study of the Phytomedicine - Bee Honey and Musa paradisiaca Extract- in Rodents
This study was designed to evaluate the safety of the phytomedicine â bee honey and M. paradisiaca drug, through acute and subchronic toxicity studies in rodents. Acute toxicity of the phytomedicine was evaluated in Swiss albino mice using graded oral-doses of the drug in the range of 1.0 to 20.0 g/kg b.wt orally and observed continuously; first for 4hrs, hourly for the next 24hrs and then 6-hourly for 48hrs. Subchronic toxicity was investigated with different concentrations of the drug for 30 days and the effects on biochemical and hematological parameters evaluated. The median acute toxicity value (LD50) of the phytomedicine was 18.840g/kg b.wt. The drug significantly reduced (p<0.05) plasma glucose and low density lipoprotein levels, but increased high density lipoprotein in the treated groups compared to the control. Aspartate aminotransferases and creatinine levels were significantly increased especially in the group treated with highest dose of the drug while significant decrease in alanine aminotransferases level was observed. The high LD50 value of the drug implies the drug could be safe for use. The study revealed that the drug had good reducing effects on hypoglycemia and the cardiovascular risk factors but that long term use can cause kidney problems.Keywords: Acute toxicity, Sub-chronic toxicity, Musa paradisiaca, Bee honey____________________________________________________________________
Intermolecular C-H...N and C-H...O interactions in (2S,4S,5R)-(-)-3,4-dimethyl-5-phenyl-2-(1,3-thiazol-2-yl)-1,3-oxazolidine
The title compound, CââHââNâOS, prepared from
(1R,2S)-(-)-ephedrine, contains the oxazolidine ring
in an envelope conformation, with the nitrogen atom
0.623 (2) Ă
from the plane of the other four oxazolidine ring
atoms. Intermolecular C--H...N and C--H...O interactions
generate a two-dimensional hydrogen-bonded
network, with shortest C...N and C...O distances of
3.403 (3) and 3.463 (2) Ă
, respectively
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