Dynamics of soil organic carbon of jhum agriculture land-use system in the heterogeneous hill of Arunachal Pradesh, India.

Land-use conversion affects soil organic carbon (SOC) dynamics. Therefore, an in-depth study of change in SOC, SOC pool, fractions of SOC and enzymatic activities of soil microbial biomass carbon (SMBC) and dehydrogenase (DHA) with the conversion of forest land to jhum, fallow jhum and settle cultivation use has been undertaken on the hills of Arunachal Pradesh of India. Geo-referenced soil samples from eight different locations, each from different land uses were collected at three depth. One part of the soil sample had been used for the analysis of SOC and its carbon fraction. The second portion was kept in a deep freezer for determining SMBC and DHA. The third part was used for the analysis of bulk density. The result revealed that the highest loss of SOC pool was recorded in jhum land (41.8 to 13.4%), and the labile carbon was also found to decrease in jhum land. The highest SMBC was observed on the surface soil of the natural forest; the highest DHA was found in the natural forest; and the lowest DHA was recorded in jhum land. This study found that the converting natural forest to jhum reduces SOC storage, enzymatic activities and C fractions significantly whereas fallow jhum shows sign of recovery because all of these parameters improved when compared to the jhum land-use system. This study also confirms that the fallow period helps restore the initial situation.

Impact of sequential herbicides application on crop productivity, weed and nutrient dynamics in soybean under conservation agriculture in Vertisols of Central India.

Adoption of conservation agriculture (CA) is very slow due to weed infestations. The application of herbicides is the only viable option to deal with problem of weed management to adhere with basic principles of CA. A field experiment was carried out for three years to evaluate the expediency of different herbicides and their sequential applications under CA. In this study, seven treatments comprised of either alone or sequential application of pre-emergence (PE) and post-emergence (PoE) herbicides, hand weeding and weedy check were tested in soybean. Result indicated that sequential application of glyphosate at 1 kg ai ha-1 + pendimethalin at 1 kg ai ha-1as PE followed by PoE application of imazethapyr at 100 g ai ha-1 at 30 days after sowing (DAS) proved to be the best economical option in terms of plant growth parameters, crop biomass, seed yield, weed index and carbon and nutrient recycling. Pearson's correlation coefficients matrix revealed that grain yield was significantly (P<0.0001) related to weed density at harvest (r = -0.84), (WDH) (r = -0.63), weed dry biomass (WDB) (r = -0.52), weed nitrogen (N), phosphorus (P) and potassium (K) uptake (r = -0.56, r = -0.59 and r = -0.66), respectively and weed index (WI) (r = -0.96). The bivariate linear regression study of grain yield on weed control efficiency (WCI) biomass, N, P and K uptake by grain showed a clear significant (P<0.0001) dependence with R2 value of 0.53, 0.99, 0.95 and 0.98, respectively. The fitted stepwise multiple regression model also revealed that N and P uptake in grain, weed density at 20 DAS and K uptake in weed were actual predictor for grain yield. We concluded that, effective and economical weed control under CA in soybean can be achieved through sequential application of glyphosate along with pendimethalin at 1 kg ai ha-1 each PE followed by PoE use of imazethapyr at 100 g ai ha-1 at 30 DAS.

Effect of Kollidon VA®64 particle size and morphology as directly compressible excipient on tablet compression properties.

The study evaluates use of Kollidon VA®64 and a combination of Kollidon VA®64 with Kollidon VA®64 Fine as excipient in direct compression process of tablets. The combination of the two grades of material is evaluated for capping, lamination and excessive friability. Inter particulate void space is higher for such excipient due to the hollow structure of the Kollidon VA®64 particles. During tablet compression air remains trapped in the blend exhibiting poor compression with compromised physical properties of the tablets. Composition of Kollidon VA®64 and Kollidon VA®64 Fine is evaluated by design of experiment (DoE). A scanning electron microscopy (SEM) of two grades of Kollidon VA®64 exhibits morphological differences between coarse and fine grade. The tablet compression process is evaluated with a mix consisting of entirely Kollidon VA®64 and two mixes containing Kollidon VA®64 and Kollidon VA®64 Fine in ratio of 77:23 and 65:35. A statistical modeling on the results from the DoE trials resulted in the optimum composition for direct tablet compression as combination of Kollidon VA®64 and Kollidon VA®64 Fine in ratio of 77:23. This combination compressed with the predicted parameters based on the statistical modeling and applying main compression force between 5 and 15 kN, pre-compression force between 2 and 3 kN, feeder speed fixed at 25 rpm and compression range of 45-49 rpm produced tablets with hardness ranging between 19 and 21 kp, with no friability, capping, or lamination issue.

Simultaneous determination of metronidazole benzoate, methylparaben, and propylparaben by high-performance liquid chromatography.

The simultaneous determination of metronidazole benzoate (MB), methylparaben (MP), and propylparaben (PP) in an oral suspension formulation was developed using high-performance liquid chromatography (HPLC). The method was developed using a Novapak C18 (3.9 x 150 mm, 4 microns) column, methanol-water (50:50, v/v) as the mobile phase and an ultraviolet (UV) detector at 254 nm. The peak area response versus concentration was linear in a concentration range from 40 to 400 micrograms/ml of MB, 0.8 to 8.0 micrograms/ml of MP, and 0.2 to 2.0 micrograms of PP. The correlation coefficients were 0.9997 for MB, 0.9987 for MP, and 0.9983 for PP, with relative standard errors of 1.12%, 1.28%, and 1.67%, respectively.

Dissolution test method for rifampicin-isoniazid fixed dose formulations.

A dissolution procedure for a rifampicin-isoniazid combination formulation was evaluated using 0.1 N hydrochloric acid solution and 0.4% (w/v) sodium lauryl sulphate solution as dissolution media. Rifampicin and isoniazid along with degradation components were chromatographed using reversed-phase liquid chromatography on a 10 microns octadecylsilica column using methanol-0.01 M disodium hydrogen phosphate (70:30, v/v; pH 4.6 +/- 0.1) as mobile phase. The detection was carried out at 254 nm. The data obtained indicate that the dissolution medium consisting of 0.4% (w/v) sodium lauryl sulphate solution is suitable for such a combination. The degradation observed in dissolution medium consisting of 0.1 N hydrochloric acid was 10-23%.

Determination of diltiazem hydrochloride in human serum by high-performance liquid chromatography.

A simple and sensitive reversed-phase high-performance liquid chromatographic method for the determination of diltiazem in human serum has been developed. The method involves a one-step deproteinization of serum for sample clean-up using acetonitrile. A LiChrosorb RP-8 column (30 cm x 4.1 mm I.D.) was eluted isocratically with acetonitrile-0.01 M dibasic sodium phosphate (40:60, v/v) containing 0.01% triethanolamine. Diltiazem was monitored at 237 nm and 0.1 a.u.f.s. The completion time for assay was less than 15 min, and the lower limit of quantitation was 10 ng/ml for a 100-microliters injection volume. Using this method, the pharmacokinetic parameters were calculated from a serum concentration versus time profile of diltiazem.

Reversed-phase high-performance liquid chromatography of ketorolac and its application to bioequivalence studies in human serum.

A reversed-phase high-performance liquid chromatographic assay was used to study the bioequivalence of the anti-inflammatory drug (+/-)-ketorolac in human volunteers. Following deproteinization of human serum with 5% zinc sulphate solution, ketorolac was chromatographed on a 10-microns octadecylsilica column using acetonitrile-water as mobile phase and ultraviolet detection at 313 nm. Under these conditions the method was reproducible with a coefficient of variation of less than 5%. The assay procedure was linear in the range 0.25-1.5 micrograms/ml, with a sensitivity of 0.01 micrograms/ml ketorolac. The recovery of ketorolac from serum ranged from 90 to 95%.

Viral aetiology of acute respiratory infections in children in north India.

Two hundred and thirty children clinically diagnosed as suffering from acute respiratory infection were tested for four major groups of viral aetiological agents, i.e. influenza para-influenza, respiratory syncytial virus (RSV) and adenoviruses using indirect immunofluorescence technique. At least one of the respiratory viruses was identified in 51 (22 per cent) specimens, which included influenza A in 6 (3 per cent), influenza B in 3 (1 per cent), para-influenza type 1 in 3 (1 per cent), para-influenza type 3 in 13 (6 per cent), RSV in 11 (5 per cent) adenovirus in 12 (5 per cent), and dual virus infections in 3 (1 per cent) cases. Maximum number of virus identification was noted in children below 1 year of age, particularly infection with RSV followed by para-influenza and adenoviruses. Value of rapid diagnosis by indirect immunofluorescence technique is stressed.