Tensile Strength Prediction of Short Fiber Reinforced Composites.

Essentially, every failure of a short fiber reinforced composite (SFRC) under tension is induced from a matrix failure, the prediction of which is of fundamental importance. This can be achieved only when the homogenized stresses of the matrix are converted into true values in terms of stress concentration factors (SCFs) of the matrix in an SFRC. Such an SCF cannot be determined in the classical way. In this paper, a closed-form formula for the longitudinal tensile SCF in the SFRC is derived from the matrix stresses determined through an elastic approach. The other directional SCFs in an SFRC are the same as those in a continuous fiber composite already available. A bridging model was used to calculate the homogenized stresses explicitly, and a failure prediction of the SFRC with arbitrary fiber aspect ratio and fiber content was made using only the original constituent strength data. Results showed that the volume fraction, the aspect ratio, and the orientation of the fiber all have significant effect on the tensile strength of an SFRC. In a certain range, the tensile strength of an SFRC increases with the increase in fiber aspect ratio and fiber volume content, and the strength of the oriented short fiber is higher than that of the random short fiber arrangement. Good correlations between the predicted and the available measured strengths for a number of SFRCs show the capability of the present method.

Dehydrogenation of Alcohols to Carboxylic Acid Catalyzed by in Situ-Generated Facial Ruthenium-CPP Complex.

A selective catalytic system for the dehydrogenation of primary alcohols to carboxylic acids using a facial ruthenium complex generated in situ from the [Ru(COD)Cl2]n and a hybrid N-heterocyclic carbene (NHC)-phosphine-phosphine ligand (CPP) has been first reported. The facial coordination model was unveiled by NMR analysis of the reaction mixture. Such a fac-ruthenium catalyst system exhibited high catalytic activity and stability, and a high turnover number of 20 000 could be achieved with catalyst loading as low as 0.002 mol %. The exceedingly high catalyst stability was tentatively attributed to both the anchoring role of NHC and the hemi-lability of phosphines. The catalytic system also features a wide substrate scope. In particular, the facial coordination of CPP ligands was found to be beneficial for sterically hindered alcohols, and ortho-substituted benzylic alcohols and bulky adamantanyl methanol as well as cholesterol were all found to be viable dehydrogenation substrates.

Identification of 3-substituted-6-(1-(1H-[1,2,3]triazolo[4,5-b]pyrazin-1-yl)ethyl)quinoline derivatives as highly potent and selective mesenchymal-epithelial transition factor (c-Met) inhibitors via metabolite profiling-based structural optimization.

c-Met/HGF signaling pathway plays an important role in cancer progression, and it was considered to be related to poor prognosis and drug resistance. Based on metabolite profiling of (S)-7-fluoro-6-(1-(6-(1-methyl-1H-pyrazol-4-yl)-1H-imidazo[4,5-b]pyrazin-1-yl)ethyl)quinoline (1), a series of 2-substituted or 3-substituted-6-(1-(1H-[1,2,3]triazolo[4,5-b]pyrazin-1-yl)ethyl)quinoline derivatives was rationally designed and evaluated. Most of the 3-substituted derivatives not only exhibited potent activities in both enzymatic and cellular assays, but also were stable in liver microsomes among different species (human, rat and monkey). SAR investigation revealed that introducing of N-methyl-1H-pyrazol-4-yl group at the 3-position of quinoline moiety is beneficial to improve the inhibitory potency, especially in the cellular assays. The influence of fluorine atom at 7-position or 5, 7-position of quinoline moiety and substituents at the 6-position of triazolo[4,5-b]pyrazine core on overall activity is not very significant. Racemate 14, an extremely potent and exquisitely selective c-Met inhibitor, demonstrated favorable pharmacokinetic properties in rats, no significant AO metabolism, and effective tumor growth inhibition in c-Met overexpressed NSCLC (H1993 cell line) and gastric cancer (SNU-5 cell line) xenograft models. Docking analysis indicated that besides the typical interactions of most selective c-Met inhibitors, the intramolecular halogen bond and additional hydrogen bond interactions with kinase are beneficial to the binding. These results may provide deep insight into potential structural modifications for developing potent c-Met inhibitors.

A Comprehensive Assessment of the Value of Laboratory Indices in Diagnosing Kawasaki Disease.

OBJECTIVE: Kawasaki disease (KD) is the primary cause of heart disease among children, but because its clinical symptoms are nonspecific, it is difficult to diagnose. The purpose of this study was to evaluate laboratory indices for possible use in the early diagnosis of KD and to determine which indices are predictive of a response to intravenous immunoglobulin (IVIG) and can be used to monitor the effects of treatment. METHODS: Three hundred thirty KD patients, 330 age-matched children with KD-like febrile disease, and 330 age-matched healthy children (controls) were enrolled in this prospective study. Levels of N-terminal pro-brain natriuretic peptide (NT-proBNP), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and cytokines were determined in all study subjects. RESULTS: In the derivation cohort, 181 patients in the KD group were compared with 181 patients in the KD-like febrile group. The following indices were found to be useful in the diagnosis of KD: NT-proBNP (area under the curve [AUC] 0.923), ESR (AUC 0.909), CRP (AUC 0.834), and interleukin-6 (IL-6; AUC 0.678). The diagnostic efficiency of each index demonstrated in the derivation cohort was repeated in the 149 KD patients in the validation cohort. There were significant differences in NT-proBNP levels between IVIG-responsive KD patients (n = 270) and IVIG-nonresponsive KD patients (n = 60), with higher NT-proBNP levels in IVIG-nonresponsive KD patients. The NT-proBNP level can effectively distinguish IVIG-responsive KD patients from IVIG-nonresponsive patients, and its AUC was 0.73. There were also significant differences in the NT-proBNP levels before and after treatment, with a significant decline after treatment. CONCLUSION: Serum levels of NT-proBNP can be used in the diagnosis of KD, the prediction of a patient's sensitivity to IVIG treatment, and the monitoring of the effects of IVIG treatment, but more attention must be paid to the scope of its application.