Publications by authors named "George S Chen"

Objectives: Hospitalized community-acquired pneumonia (CAP) patients are admitted for ventilation, vasopressors, and renal replacement therapy (RRT). This study aimed to develop a machine learning (ML) model that predicts the need for such interventions and compare its accuracy to that of logistic regression (LR).

Design: This retrospective observational study trained separate models using random-forest classifier (RFC), support vector machines (SVMs), Extreme Gradient Boosting (XGBoost), and multilayer perceptron (MLP) to predict three endpoints: eventual use of invasive ventilation, vasopressors, and RRT during hospitalization.

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Platinum(II) and palladium(II) complexes are well-known to catalyze the partial oxidation of alkanes. Herein, we present experimental evidence that tunneling occurs in the protonolysis of M(II)-CH(3) (M = Pt, Pd) model systems. We propose that there may be a connection between the observation of tunneling and a protonolysis mechanism involving direct protonation of the M-C bond and that tunneling may also be expected for electrophilic C-H activation of methane by Pt(II) and Pd(II) that proceeds via direct proton loss from a sigma complex.

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The rates of C H bond activation for various alkanes by [(N-N)Pt(Me)(TFEd(3))](+) (N N = Ar N C(Me) C(Me) N Ar; Ar = 3,5-di-tert-butylphenyl; TFE-d(3) = CF(3)CD(2)OD) were studied. Both linear and cyclic alkanes give the corresponding alkene-hydride cation [(N-N)Pt(H)(alkene)](+) via (i) rate determining alkane coordination to form a C H sigma complex, (ii) oxidative cleavage of the coordinated C H bond to give a platinum(IV) alkyl-methyl-hydride intermediate, (iii) reductive coupling to generate a methane sigma complex, (iv) dissociation of methane, and (v) beta-H elimination to form the observed product. Second-order rate constants for cycloalkane activation (C(n)H(2n)), are proportional to the size of the ring (k approximately n).

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Glucose-6-phosphate dehydrogenase (G6PD) is the initial enzyme in the hexose monophosphate pathway of glucose metabolism. Deficiency of G6PD has been linked to increased sensitivity of red cells to hemolytic anemia due to certain oxidant drugs, infectious agents or fava beans. It is an inherited error in metabolism and has a high incidence in certain ethnic groups.

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