150 research outputs found
Competition between In-Plane vs Above-Plane Configurations of Water with Aromatic Molecules: Non-Covalent Interactions in 1,4-Naphthoquinone-(H2O)1-3Complexes
Non-covalent interactions between aromatic molecules and water are fundamental in many chemical and biological processes, and their accurate description is essential to understand molecular relative configurations. Here we present the rotational spectroscopy study of the water complexes of the polycyclic aromatic hydrocarbon 1,4-naphthoquinone (1,4-NQ). In 1,4-NQ-(H2O)1,2, water molecules bind through O-H···O and C-H···O hydrogen bonds and are located on the plane of 1,4-NQ. For 1,4-NQ-(H2O)3, in-plane and above-plane water configurations are observed exhibiting O-H···O, C-H···O, and lone pair···π-hole interactions. The observation of different water arrangements for 1,4-NQ-(H2O)3 allows benchmarking theoretical methods and shows that they have great difficulty in predicting energy orderings due to the strong competition of C-H···O binding with πand π-hole interactions. This study provides important insight into water interactions with aromatic systems and the challenges in their modeling
Numerical simulation of failure mechanisms of a typical dead end anchorage of post-tensioned suspended slabs
The post-tensioning loads in suspended slabs are transferred to concrete mass via an anchorage
assembly that consists in a strand and anchor component. Many failures have occurred in the
dead-end anchors of post-tensioned (PT) suspended slabs during the post-tensioning process
which need a closer study. This study attemps to simulate the crack propagation near the deadend
anchors of PT suspended slabs. The bond behaviour of strand and wire is develioped using
experimental test. Interface element is used to model the bond between concrete and strand/
wire. The analysis is conducted using displacement controlled procedure. The result shows that
the crack on the concrete is concentrated near the dead-end anchors
Use of recycled concrete aggregates in sustainable structural concrete applications
The increasing difficulty in securing natural coarse and fine aggregates for the production of concrete coupled with the environmental issues and social costs of unlimited extraction of natural aggregates makes the usage of recycled aggregate concrete (RCA) in the construction industry of prime importance. However the full use of the material can be justified only through structural applications. Engineers are reluctant to use RCA in structural applications due to lack of design information. A brief review of the recent literature on Recycled Aggregate Concrete (RCA) used as a structural material is reported in this paper. It is found that the most of the research studies conducted up to now are mostly based on material properties rather than investigation of the RCA and its performance as a structural material. Major issues and problems associated with RCA concrete compared to normal concrete are identified in the paper
Isolation of Bacillus producing Chitinase from Soil: Production and Purification of Chito-oligosaccharides from Chitin Extracted from Fresh Water Crustaceans and Antimicrobial Activity of Chitinase
In the present investigation Bacillus sp. strain was isolated and screened from the red soil collected from Doiwala region of Dehradun (U.K), India. Serial dilution technique was adopted to isolate the organism and was screened for its chitinolytic activity. The biochemical tests were performed to prove its validity. The microorganism was also screened by inoculating a loop full of the isolated strain in basic cresol red dye and incubated for about 18- 24 h. The conversion of colour of the red dye into purple (pH, 6.5- 8.8) was taken as an indication for the presence of Bacillus sp. Amylase production by the organism was also screened by introduction of iodine in the broth/agar culture having starch. The broth/agar medium having starch but no bacterial strain was used as the control. The disappearance of color confirmed the presence of Bacillus strain producing amylase which degrades the starch. The chitinous wastes were collected from fresh water crustaceans viz. fresh water crab (Potamon sp.) and fresh water prawn (Palaemon sp.) and the chitin extracted was used as the substrate for chitinase. The yield of chitin extracted from fresh water prawn (Palaemon sp.) was found to be comparatively higher than that of chitin extracted from fresh water crab (Potamon sp.). Standard colloidal chitin was used as the reference control. The enzyme activity of chitinase for degradation of chitin extracted from crab and prawn was compared. The results confirmed that chitinase activity for degradation of crab chitin was comparatively higher than that of degradation of prawn chitin. The enzyme activities were found to be 0.11 µg/ml/minute and 0.09 µg/ml/minute for degradation of crab and prawn chitin respectively. The antimicrobial activity of chitinase extracted was determined against the bacterial and fungal cultures. Potent antibacterial activity of chitinase was observed against the bacterial cultures but no antifungal activity was observed. The chitinase produced by the species was able to degrade the chitin and chito-oligosaccharides produced was separated by TLC and purified by HPLC
Increased Expression of RUNX1 in Liver Correlates with NASH Activity Score in Patients with Non-Alcoholic Steatohepatitis (NASH)
Given the important role of angiogenesis in liver pathology, the current study investigated the role of Runt-related transcription factor 1 (RUNX1), a regulator of developmental angiogenesis, in the pathogenesis of non-alcoholic steatohepatitis (NASH). Quantitative RT-PCRs and a transcription factor analysis of angiogenesis-associated differentially expressed genes in liver tissues of healthy controls, patients with steatosis and NASH, indicated a potential role of RUNX1 in NASH. The gene expression of RUNX1 was correlated with histopathological attributes of patients. The protein expression of RUNX1 in liver was studied by immunohistochemistry. To explore the underlying mechanisms, in vitro studies using RUNX1 siRNA and overexpression plasmids were performed in endothelial cells (ECs). RUNX1 expression was significantly correlated with inflammation, fibrosis and NASH activity score in NASH patients. Its expression was conspicuous in liver non-parenchymal cells. In vitro, factors from steatotic hepatocytes and/or VEGF or TGF-beta significantly induced the expression of RUNX1 in ECs. RUNX1 regulated the expression of angiogenic and adhesion molecules in ECs, including CCL2, PECAM1 and VCAM1, which was shown by silencing or over-expression of RUNX1. Furthermore, RUNX1 increased the angiogenic activity of ECs. This study reports that steatosis-induced RUNX1 augmented the expression of adhesion and angiogenic molecules and properties in ECs and may be involved in enhancing inflammation and disease severity in NASH
Effect of sonication on the reactivity of silica fume in portland cement mortars
Permission is granted by ICE Publishing to print one copy for personal use. Any other use of these PDF files is subject to reprint fees.Currently, the use of silica fume for the production of mortars and high-performance concrete is of great importance
to the construction materials sector. Different applications of silica fume have generated extensive studies about its
high reactivity as a pozzolanic material, in addition to its effect on the properties of some materials within which it is
incorporated. In this study a sonication process was applied by means of which the deagglomeration of the larger
particles of densi¿ed silica fume (CSF) was achieved. The result is a CSF treated with the ultrasound probe, which is
obtained for different tests where the parameters of sonication such as sonication power level and sonication time
are varied. This treatment makes it possible to increase the quantity of submicrometric particles in the sample. The
effect of sonication process on CSF produces a greater quantity of very ¿ne particles, which improve the pozzolanic
reactivity of silica fume and increase the ¿xation of hydrated lime. This behaviour also produces higher mechanical
strength in mortars manufactured with sonicated silica fume (SSF). The mechanical strengths of SSF mortars were
greater than those for control and CSF mortar. Different percentages of cement were substituted (between 0 and
15% by weight), and in all cases the SSF mortars showed important differences from the CSF mortar. It was observed
that for the longest sonication times and highest sonication power levels, mechanical strengths were increased.The authors are grateful to the Spanish company Ferroatlantica S.L. for their financial support; to the Spanish Agency of International Cooperation and Development (AECID) for the doctorate grant to D.M.-V.; to the Spanish government for their support to the project BIA 2007-63252; and to FEDER for its financial support to our research projects.Martínez Velandia, DA.; Paya Bernabeu, JJ.; Monzó Balbuena, JM.; Borrachero Rosado, MV. (2011). Effect of sonication on the reactivity of silica fume in portland cement mortars. Advances in Cement Research. (1):23-31. https://doi.org/10.1680/adcr.8.00027S2331
Comparing pregnancy, childbirth, and neonatal outcomes in women with different phenotypes of polycystic ovary syndrome and healthy women: a prospective cohort study
The aim of this study was to compare pregnancy, childbirth, and neonatal outcomes in women with different phenotypes of polycystic ovary syndrome (PCOS) with healthy women. A prospective cohort study from the beginning to the end of pregnancy for 41 pregnant women with PCOS (case) and 49 healthy pregnant women (control) was completed. Based on the presence or absence of menstrual dysfunction (M), hyperandrogenism (HA), and polycystic ovaries (PCO) on ultrasound, the PCOS (case) group were divided into three phenotypes (HA + PCO ( = 22), M + PCO ( = 9), HA + M+PCO ( = 10). Pre-eclampsia, gestational diabetes, and lower birth weight among newborns were significantly higher in the PCOS case group compared to the control group especially in the phenotype HA + M+PCO ( < .05). High BMI ( = 2.40; =.03) was the strongest predictor of pre-eclampsia in patients with PCOS. High androgen levels (free androgen index) ( = 13.71, 3.02; < .05), was the strongest predictor of developing diabetes during pregnancy and reduced birth weight baby, respectively.These results suggest that PCOS, particularly in phenotype HA + M+PCO ( < .05), is a risk factor for adverse pregnancy and neonatal outcomes including gestational diabetes, pre-eclampsia, and reduced weight babies
Crystal engineering of HIV-1 reverse transcriptase for structure-based drug design
HIV-1 reverse transcriptase (RT) is a primary target for anti-AIDS drugs. Structures of HIV-1 RT, usually determined at ∼2.5–3.0 Å resolution, are important for understanding enzyme function and mechanisms of drug resistance in addition to being helpful in the design of RT inhibitors. Despite hundreds of attempts, it was not possible to obtain the structure of a complex of HIV-1 RT with TMC278, a nonnucleoside RT inhibitor (NNRTI) in advanced clinical trials. A systematic and iterative protein crystal engineering approach was developed to optimize RT for obtaining crystals in complexes with TMC278 and other NNRTIs that diffract X-rays to 1.8 Å resolution. Another form of engineered RT was optimized to produce a high-resolution apo-RT crystal form, reported here at 1.85 Å resolution, with a distinct RT conformation. Engineered RTs were mutagenized using a new, flexible and cost effective method called methylated overlap-extension ligation independent cloning. Our analysis suggests that reducing the solvent content, increasing lattice contacts, and stabilizing the internal low-energy conformations of RT are critical for the growth of crystals that diffract to high resolution. The new RTs enable rapid crystallization and yield high-resolution structures that are useful in designing/developing new anti-AIDS drugs
- …