Applied Chemistry

This paper presents an experimental investigation on the effect of ? -irradiation dose, polyvinyl alcohol content and nano-calcined clay ratios of PVA-NCC-cement mortar composite. PVA-NCC-cement mortar composite was prepared by the addition of PVA on blended cement mortar with different percentages namely 2, 4, 6 and 8% by wt. of blended cement. The fresh composites were first cured at 100% relative humidity for 24 hours and then subjected to ? -irradiation dose namely 10, 20, 30 and 50 KGy. The irradiated composites were cured in water for 28 days. Physico-mechanical properties such as compressive strength, bulk density, total porosity and water absorption were tested according to standard specifications. XRD, SEM, TGA were carried out on some selected samples to evaluate the effect of different factors on crystallinity, microstructural and thermal behaviour of the composites. Results showed that, compressive strength and bulk density of the composites increased with increasing the absorbed dose and PVA contents for certain values and then decreased while, total porosity and water absorption behave in an opposite direction. XRD, SEM, TGA confirmed these conclusions.

Chemometrics is the application of statistical and mathematical methods, in particular multivariate methods, to handle chemical or process data. In this study, the global and reactivity descriptors with multivariate methods have been utilized as a potential tool for grouping of cyanuric acid. The global and reactivity descriptors of cyanuric acid tautomers were analyzed using Principal component analysis (PCA) and hierarchical cluster analysis (HCA) in different solvents. The tautomers constitute groups are similar in three solvents namely THF, DMF and water, but in ethanol solvent show different groups. In three solvents (THF,DMF and water), five tautomers, CA2, CA4, CA5, CA6 and CA7 constitute one group, but CA4, CA5, CA6 and CA7 unique well distinguished from the rest. The CA8, CA9 and CA1 tautomers constitute second group and CA10, CA11 and CA3 constitute a cluster of three tautomer types. In ethanol solvent , three tautomers, CA5, CA6 and CA7 constitute one group, the CA8, CA9 and CA1 tautomers constitute second group and CA10 and CA11 constitute a third group and CA2,CA3 and CA4 constitute a fourth group. The HCA results are very similar to those obtained with the PCA results.

The main aim of science and technology is to better man’s life and his environment. Every learning situation in science based courses, subjects or areas requires a repertoire of essentials skills to achieve success. Success is built in every learning and learner but demands the right skills. Since no learner is perfect, such skills in learning make the learner more proficient as he continues to study and practice. One of such skills is the rightful and positive attitudes. Attitude can distort the perception of information and affect the degree of their retention. This paper examines what constitutes students’ positive learning attitudes, habits, behaviours and qualities that are predictors to positive attitudes which in turn beget positive results in science learning. Factors which beget negative learning attitudes and their implications to learning are also considered.

To understand the structural and electrical characteristics of Au and thiol substituted tetracene, a quantum chemical calculation has been carried out with Density Functional Theory (DFT) coupled with the Bader’s AIM theory. The various levels of applied electric field (0 – 0.21 VÅ-1) altered the geometrical conformation as well as the electronic energy levels of the molecule. Variations in MPA and NPA atomic charges of the molecule for the applied fields have been compared. The field polarizes the molecule and hence the dipole moment of the molecule increases from 0.0002 to 14.65 D. For the zero bias, the HOMO–LUMO gap is1.752 eV, as the field increases this gap decreases to 1.03 eV, which reveals that it exhibits charge transfer ability for the applied field.

Nanocrystalline PbS thin films were prepared by chemical bath deposition (CBD) method by varying synthesis temperatures. The influence of the synthesis temperature on the structure and optical properties of PbS nanostructures were investigated. The X-ray diffraction (XRD) pattern of the PbS nanostructures correspond to the various planes of a single phase cubic PbS. It was observed that the decrease in the synthesis temperature resulted into extra diffraction peaks which may be due to the presence of the impurity phases. The morphological properties of the films are observed by scanning electron microscopy (SEM) characterization. UV-Visible spectroscopy is done to measure the absorption and transparent properties of all the prepared systems. The optical band gap of all the prepared systems is also calculated and correlated with the structural properties.

The most important aspect of organic chemical reactivity is the chemistry of carbonyl group (>C=O) .It directly undergoes nucleophilic attack by different substrates and yields a series of compounds.The prostereogenic carbon gets converted to stereogenic carbon by a nucleophilic attack on either side of the plane of carbonyl group. Different organic compounds containing >C=O group undergo photocyclisation or photoreduction reactions and result a variety of compounds of both chemical and mechanistic interest. ?-diketones an important class of carbonyl compounds afford stable ylides and Aldol adducts when interacted with different reagents under varying conditions.

Interaction of various process parameters like initial chromium concentration (VI) (5-30 mg/l), pH (1-10), and adsorbent dosage (6-10 g/l) for chromium adsorption using custard apple powder were evaluated using central composite design (CCD) in response surface methodology. The CCD design in response surface methodology has been applied for designing the experiments as well as for full response surface estimation and 19 experimental data as per the model were used. The optimum conditions for better percentage removal of chromium from waste water with the concentration of 20 mg/l were as adsorbent dosage (9.9966 g/l), pH (2.7877) and initial chromium concentration (15.18693 mg/l). The high correlation coefficient (R2 =0.98929) between the model and the experimental data showed that the model was able to predict the better percentage removal of chromium (VI) from waste water using custard apple peel powder efficiently

The present study is aimed to analyze the statistical relationship among various water quality parameters and water quality index (WQI). For this, observed results of physico-chemical analysis of 71 ground water samples of study area in pre- and post-monsoon season and calculated water quality index values for each respective sample were taken into consideration. Correlation coefficient between every water quality parameter and WQI values is calculated and for the pairs having highly significant correlation coefficient (0.8<r<1.0) values; regression model is applied and scatter plots are drawn. The systematic correlation and regression study suggested the perfect linear relationship between Fluoride and WQI Values. The analysis provides essential information regarding the dependency of water quality rating on each water quality parameter.

Presently a stability indicating RP-HPLC method was developed for the estimation of Sitagliptin Phosphate monohydrate in pharmaceutical dosage forms . A 0.1 M KH2 PO4 solution was used as the buffer solution .Buffer and acetonitrile were mixed in the ratio 50:50 ,the resulting solution was sonicated to dissolve and degassed by vacuum filtration through 0.4 µ membrane filter and the resulting solution was used as mobile phase and diluent. Chromatograms were recorded using Inertsil ODS, C18 ,150 mm x 4.6 mm , 5 µ column at a temperature of 300 C with isocratic elusion .The detection wave length was 268 nm at a flow rate of 1.0 mL per minute .Each injection volume was 20 µL. The retention times for Sitagliptin Phosphate standard and sample were 3.613 and 3.618 min respectively. Linear calibration curve was obtained over the concentration range of 2.5 -15.0 µg /mL with a slope, intercept, Standard deviation and correlation coefficient of respectively 35792,10262,669649.4 and 0.999 respecively. The present method was validated as per ICH guidelines for Specificity, Linearity, Accuracy ,Precision, Ruggedness and found suitable for the determination of Sitagliptin Phosphate .The stability indicating studies under different stress conditions revealed that the drug was stable and the % of degradation of the drug was in the range 4.75 -11.57 % .The limit of detection was 61.74 µg-mL and limit of quantification was187.09 µg – mL . The present method was rapid and sensitive for the determination of Sitagliptin Phosphate monohydrate.