Formulation and characterisation of nanosuspensions of BCS class II and IV drugs by combinative method

Drug nanocrystals are known to increase the solubility of Biopharmaceutics Classification System (BCS) class II and IV drugs. SmartCrystals are the second generation nanocrystals with particle size of less than 100 nm and increased the stability and solubility of drug and drug product. The combinative methods adopted for the preparation of SmartCrystals are reported to shorten the processing time to reduce the particle size of the drug. This study was carried out with the aim to prepare nanosuspensions of aprepitant and ibuprofen using two pretreatment methods, precipitation and ball milling in a combination of high-pressure homogenisation (HPH). Ball milling and precipitation resulted in nanosuspensions having a particle size less than 1 µ, which were subjected to high HPH. HPH further led to a reduction in the particle size. However, the precipitation method failed to reduce the size of ibuprofen particles to 1 µ.     

Performance of Recalibrated Equations for the Estimation of Daily Reference Evapotranspiration

An accurate estimation of reference evapotranspiration (ET₀) is of paramount importance for many studies such as hydrologic water balance, irrigation system design and management, crop yield simulation, and water resources planning and management. In the present study, Blaney-Criddle, Jensen-Haise and Hargreaves (temperature based), Priestley-Taylor, Radiation and Makkink (radiation based) and, Pan Evaporation and Christiansen (pan evaporation based) methods have been evaluated and recalibrated with respect to FAO-56 Penman-Monteith method for estimating daily ET₀ in the semi-arid Tirupati, Nellore, Rajahmundry, Anakapalli and Rajendranagar sites of Andhra Pradesh, India. Recalibrated Blaney-Criddle (temperature based), Radiation (Radiation based) and Christiansen (Pan evaporation based) methods showed a satisfactory performance at the sites. Further, recalibrated Blaney- Criddle method showed relatively better performance than Radiation and Christiansen methods in the daily ET₀ estimation. Recalibrated Blaney- Criddle method may therefore be adopted at the sites selected for the present study and also at the sites with similar climatic conditions for satisfactory daily ET₀ estimation.     

Quantifying arsenic-induced morphological changes in spinach leaves: implications for remote sensing

Arsenic (As) is a common soil contaminant that can be accumulated into plant parts. The ability to detect As in contaminated plants is an important tool to minimize As-induced health risks in humans. Near-infrared (NIR) spectra are strongly affected by leaf structural characteristics. Therefore, quantitative analyses of structural changes in the arrangement of mesophyll cells caused by As will help to explain spectral responses to As. The objectives of this study were to use stereological methods to quantify internal structural changes in leaves with As treatment in spinach plants, and to relate these changes to leaf spectral properties in NIR spectra. Hydroponically grown spinach was treated with 0, 5, 10 and 20 μmol l^?1 for four weeks in a growth chamber. Spectral properties of leaves were obtained for visible and infrared frequencies. Leaf structural properties, such as mesophyll thickness and mesophyll surface area, were measured using stereological methods. Quantitative analysis of leaf structure showed that total leaf thickness and intercellular spaces in spongy mesophyll cells decreased with increasing As treatment. Changes in leaf reflectance in NIR wavelengths were strongly correlated with leaf As concentration and leaf structural changes. Multiple linear regression of leaf reflectance values at the highest correlated wavelengths (1048, 1098 and 1080 nm) generated an R ² value of 0.69. Results from this study support the hypothesis that relationships between leaf structure and reflectance may be useful in the interpretation of spectral data to detect plant leaf As concentration.     

Influence of plant pigments on spectral reflectance of maize,groundnut and soybean grown in semi-arid environments

Abstract. Spectral reflectance of leaves is influenced primarily by plant pigments, chlorophyll and carotenoids. Such reflectance can be used to study the changes in chlorophyll content and nitrogen status and in turn measures the amount of biomass accumulation. A field experiment was laid out at the Research Farm of ANGR Agricultural University, Hyderabad. The reflectance observations were taken using a hand-held ground radiometer at an interval of 15 days beginning from 30 days after sowing (DAS) until harvest of the crops. The plant pigments were determined simultaneously using DMSO (dimethyl sulphoxide) method in the laboratory. The experimental results revealed the influence of plant pigments on spectral reflectance of maize, groundnut and soybean. It was observed that there was an increase in chlorophyll- a, chlorophyll- b, total chlorophyll and carotenoid content up to flowering and thereafter chlorophyll- a content declined at a faster rate than chlorophyll- b towards physiological maturity. With the increase in concentrations of chlorophyll and carotenoids, there was a decline in spectral reflectance of the blue band (450-520 nm) and the red band (620-680 nm). Whereas, NIR (near-infrared) reflectance in the case of soybean and groundnut was found to be higher than that of maize by 11% and 2%, respectively. This was attributed to canopy cover of soybean and groundnut crops, where the soil was fully covered with vegetation. In case of maize, due to wider spacing, the soil exposure is greater, which results in low reflectance values of the NIR band. Normalized Difference Vegetation Index (NDVI) is linearly related to total chlorophyll content and the growth stages of a crop up to flowering. The NDVI differs significantly during the peak vegetative growth period among the three crop types. The study revealed that the significant differences in reflectance of maize, groundnut and soybean in the red and NIR bands were influenced by concentrations of chlorophyll- a, chlorophyll- b and carotenoids, which indicates the photosynthetic behaviour of the crops.     

Technical note Monitoring the Oil & Natural Gas Corporation (ONGC) oil well fire at Pasarlapudi,Andhra Pradesh,India

Methods used to infer sea surface temperatures (SSTs) from satellite have traditionally been based on regression-tuned split-window fixed-coefficient algorithms. These can give inaccurate SST results when local atmospheric conditions are significantly different from those encapsulated by the regression averaging. The new generation of SST algorithms attempts to correct for atmospheric variability. These approaches include the R₅₄ transmittance-ratio methods of other workers, and the dynamic water vapour (DWV) correction method of the authors. The relative performances of the various methods are compared by applying each to an ocean and satellite dataset obtained off the west coast of Tasmania, Australia in 1987. We also investigate the performance of the NESDIS operational multi-channel, cross-product, and nonlinear formulas for NOAA-9, -11, -12, and-14 when applied to the same dataset. We find the DWV method gives SST retrievals which have significantly smaller bias errors than those returned by the three transmittance-ratio methods. The best overall performance was returned by the NESDIS multichannel (MCSST) formula for NOAA-9, indicating that in low water vapour loading situations, the standard regression-based algorithms work well.     

Conductivity study of polyethylene oxide (PEO) complexed with sodium bicarbonate

Ion conducting thin film polymer electrolytes based on polyethylene oxide (PEO) complexed with NaHCO₃ salt has been prepared using solution-cast technique. The complexation of NaHCO₃ salt with PEO is confirmed by XRD and IR studies. DC conductivity in the temperature range 303–368 K has been evaluated. The conductivity is found to increase in the PEO complex with the NaHCO₃ salt and also with an increase in temperature. Using this polymer electrolyte, an electrochemical cell with the configuration Na/(PEO + NaHCO₃)/(I₂ + C + electrolyte) has been fabricated and its discharge characteristics studied. Open Circuit Voltage (OCV) and Short Circuit Current (SCC) are found to be 2.69 V and 1.28 mA, respectively. Other parameters associated with the cell are evaluated and presented in this paper.     

Finite element simulation of internal flows with heat transfer using a velocity correction approach

This paper enumerates finite-element based prediction of internal flow problems, with heat transfer. The present numerical simulations employ a velocity correction algorithm, with a Galerkin weighted residual formulation. Two problems each in laminar and turbulent flow regimes are investigated, by solving full Navier-Stokes equations. Flow over a backward-facing step is studied with extensive validations. The robustness of the algorithm is demonstrated by solving a very complex problem viz. a disk and doughnut baffled heat exchanger, which has several obstructions in its flow path. The effect of wall conductivity in turbulent heat transfer is also studied by performing a conjugate analysis. Temporal evolution of flow in a channel due to circular, square and elliptic obstructions is investigated, to simulate the vortex dynamics. Flow past an in-line tube bank of a heat exchanger shell is numerically studied. Resulting heat and fluid flow patterns are analysed. Important design parameters of interest such as the Nusselt number, Strouhal number, skin friction coefficient, pressure drop etc. are obtained. It is successfully demonstrated that the velocity correction approach with a Galerkin weighted residual formulation is able to effectively simulate a wide range of fluid flow features.     

The role of apoptosis in the modulation of colon carcinogenesis by dietary fat and by the organoselenium compound 1,4-phenylenebis(methylene)selenocyanate

Studies in laboratory animals have demonstrated that dietary supplements of organoselenium, 1,4-phenylenebis(methylene)selenocyanate (p-XSC) inhibit colon carcinogenesis. Diverse chemopreventive agents and clinically used anticancer drugs have been shown to induce apoptosis in colonic tumors. Inducing apoptosis is a key mechanism for the effectiveness of some chemopreventive agents; however, failure of apoptosis is now believed to contribute to the development of human cancer. In this study, we determined the number of apoptotic bodies in the colon tumors of rats fed a low-fat (LF) or a high-fat (HF) diet with or without p-XSC treatment. At 5 weeks of age, male F344 rats were divided into four groups, which were then maintained on one of the following diets: LF, 5% corn oil; HF, 23.5% corn oil; and LF and HF supplemented with 20 ppm p-XSC. In addition, the LF or HF diet with p-XSC supplements was administered either during the initiation stage or postinitiation. At 7 weeks of age, all rats except those intended for vehicle (normal saline) treatment were given 15 mg/kg of body weight of azoxymethane once weekly for 2 weeks. The animals were sacrificed 38 weeks after carcinogen treatment, and their colonic tumors were examined for appearance of apoptosis. The LF diet significantly increased the percentage of apoptosis as compared to the HF diet; the percentage of apoptosis in LF and HF diets were 12.4 and 2.9. The colon tumors that were present in the groups fed p-XSC together with a LF or a HF diet after carcinogen administration (postinitiation period) had a higher number of apoptotic bodies than those that were present in the animals fed p-XSC before carcinogen treatment (initiation period). The extent of apoptosis was weak when p-XSC was given with a HF diet (4.4%) during the initiation phase, but it was high significant when p-XSC was administered with LF diet (25.2%). Taken together, our data suggest that administration of LF diet supplemented with p-XSC increases apoptosis as compared to a HF diet alone.