Optimization of Air Preheater Design for the Enhancement of Heat Transfer Coefficient

This paper presents an approach for the optimization of air preheater design with inline tube arrangement. The poor performance of an air preheater in the modern power plants is one of the main reason for higher unit heat rate & is responsible for deterioration in boiler efficiency. The main problem of air preheater is the leakage of air to the flue gas side & thereby resulting in poor thermal performance. The higher ash content in Indian coal also adds to the problems associated with tubular air preheater. Air preheaters are designed to meet performance requirements with consideration of highly influencing parameters viz. heat transfer, leakage and pressure drop. In the present work the performance of tubular air preheater is evaluated with the help of Computational Fluid Dynamics (CFD) analysis for In-line tube arrangement for evaluating influence of various parameters viz. Gas flow rate, Gas temperature, tube pitch, etc. The model can also be used while selecting a new type of surface geometry for optimizing the design of air-preheater

Evaluation of some Methods for Preparing Gliclazide-&#946-Cyclodextrin Inclusion Complexes

Purpose: Gliclazide has been found to form inclusion complexes with β- cyclodextrin (β-CD) in solution and in solid state. The present study was undertaken to determine a suitable method for scaling up gliclazide-β-CD inclusion complex formation and to evaluate the effect of some parameters on the efficiency of complexation. Method: The solid inclusion complexes of gliclazide and β-cyclodextrin were prepared at a molar ratio of 1:1 and 1:2 by mixing, kneading, and coprecipitation methods both on small and large scales. The effect of parameters such as kneading time and temperature on complexation was also studied. Characterization was performed using infrared spectroscopy, X-ray diffractometry, and dissolution studies. In vitro release studies were carried out in phosphate buffer (pH 6.8). Result: All the methods of preparation of complexes were found to be useful in increasing the solubility of gliclazide except mixing method where the rise in solubility was not significant. Both kneading and co-precipitation methods in 1:2 molar ratios were found to be equally effective in improving the solubility of gliclazide. The formation of inclusion complexes was evident in these formulations as shown by IR and XRD studies. But when carried out on a large scale, co-precipitation method was found to be more tedious and time-consuming than kneading method. Moreover percent recovery of complexes in the kneading method was found to be 98.76% as compared to 92.05% in case of co-precipitation method. Conclusion: Drug content studies, IR spectroscopic studies, X-Ray diffractometry studies and in vitro dissolution study data indicated that inclusion complexes prepared by kneading method in 1:2 molar ratios were suitable for improving the solubility of gliclazide. The same formulation was prepared at large scale and optimum formulation conditions were established. Keywords: Gliclazide, Inclusion complexes, β-cyclodextrin, Kneading Tropical Journal of Pharmaceutical Research Vol. 6 (4) 2007: pp. 833-84

STUDIES ON EFFECT OF FORMULATION AND PROCESSING PARAMETERS ON STABILITY OF KETOROLAC TROMETHAMINE ORALLY DISSOLVING FILMS

Objective: The objective of the proposed work was to study the effect of various formulation and process parameters of solvent casting method on the physical and chemical stability of Ketorolac Tromethamine (KT) in the orally dissolving film dosage form. Methods: KT-excipient interaction study was carried out both in solid state and by processing samples through the solvent casting technique. The samples were evaluated using IR spectroscopy (IR) and X-ray diffractometry (XRD). Solvent casting method was used to prepare KT films using different film-forming polymers, and solvents. The drying temperature and pH of the dispersion were also varied to study the effect of these parameters on the stability of KT. All the formulations were analysed chemically initially and after one month of storage at 40 °C/75% RH. Results: During KT-excipient interaction study in solid state KT was found to be stable. No significant changes were observed in its impurity profile. Interaction between different polymers and KT was observed after the solvent casting process as revealed by IR and XRD analysis. The interaction was further confirmed in the film formulations upon chemical analysis. The polymers showing interaction with KT in XRD and IR were making it unstable chemically and were responsible for its chemical degradation as revealed by chemical analysis. It was also revealed that KT is most stable when processed using water as the solvent. KT was found to be stable when processed at a higher temperature and at acidic pH during film formation. It was found that chemical stability is more when Polyethylene oxide (PEO) and water under acidic pH are used and films are dried at a higher temperature. Conclusion: Both formulation parameters and processing conditions of the solvent casting technique affects the stability of drugs and hence should be studied as part of pre-formulation studies while developing orally dissolving films of drugs

Enteroviruses in Patients with Acute Encephalitis, Uttar Pradesh, India

An outbreak of viral encephalitis occurred in northern India in 2006. Attempts to identify an etiologic agent in cerebrospinal fluid by using reverse transcription–PCR showed positivity to enterovirus (EV) in 66 (21.6%) of 306 patients. Sequencing and phylogenetic analyses of PCR products from 59 (89.3%) of 66 specimens showed similarity with EV-89 and EV-76 sequences

Enteroviruses in Patients with Acute Encephalitis, Uttar Pradesh, India

An outbreak of viral encephalitis occurred in northern India in 2006. Attempts to identify an etiologic agent in cerebrospinal fluid by using reverse transcription–PCR showed positivity to enterovirus (EV) in 66 (21.6%) of 306 patients. Sequencing and phylogenetic analyses of PCR products from 59 (89.3%) of 66 specimens showed similarity with EV-89 and EV-76 sequences

De novo identification of viral pathogens from cell culture hologenomes

<p>Abstract</p> <p>Background</p> <p>Fast, specific identification and surveillance of pathogens is the cornerstone of any outbreak response system, especially in the case of emerging infectious diseases and viral epidemics. This process is generally tedious and time-consuming thus making it ineffective in traditional settings. The added complexity in these situations is the non-availability of pure isolates of pathogens as they are present as mixed genomes or hologenomes. Next-generation sequencing approaches offer an attractive solution in this scenario as it provides adequate depth of sequencing at fast and affordable costs, apart from making it possible to decipher complex interactions between genomes at a scale that was not possible before. The widespread application of next-generation sequencing in this field has been limited by the non-availability of an efficient computational pipeline to systematically analyze data to delineate pathogen genomes from mixed population of genomes or hologenomes.</p> <p>Findings</p> <p>We applied next-generation sequencing on a sample containing mixed population of genomes from an epidemic with appropriate processing and enrichment. The data was analyzed using an extensive computational pipeline involving mapping to reference genome sets and <it>de-novo </it>assembly. In depth analysis of the data generated revealed the presence of sequences corresponding to <it>Japanese encephalitis </it>virus. The genome of the virus was also independently <it>de-novo </it>assembled. The presence of the virus was in addition, verified using standard molecular biology techniques.</p> <p>Conclusions</p> <p>Our approach can accurately identify causative pathogens from cell culture hologenome samples containing mixed population of genomes and in principle can be applied to patient hologenome samples without any background information. This methodology could be widely applied to identify and isolate pathogen genomes and understand their genomic variability during outbreaks.</p

Comparison of immune response generated against Japanese encephalitis virus envelope protein expressed by DNA vaccines under macrophage associated versus ubiquitous expression promoters

<p>Abstract</p> <p>Background</p> <p>Japanese encephalitis virus (JEV) is the leading cause of viral encephalitis, with ~50,000 cases reported annually worldwide. Vaccination is the only measure for prevention. Recombinant vaccines are an efficient and safe alternative for formalin inactivated or live attenuated vaccines. Nowadays, incorporation of molecular adjuvants has been the main strategy for melioration of vaccines. Our attempt of immunomodulation is based on targeting antigen presenting cells (APC) "majorly macrophages" by using macrosialin promoter. We have compared the immune response of the constructed plasmids expressing JEV envelope (E) protein under the control of aforesaid promoter and cytomegalovirus (CMV) immediate early promoter in mouse model. Protection of immunized mice from lethal challenge with JEV was also studied.</p> <p>Results</p> <p>The E protein was successfully expressed in the macrophage cell line and was detected using immunofluorescence assay (IFA) and Western blotting. APC expressing promoter showed comparable expression to CMV promoter. Immunization of mice with either of the plasmids exhibited induction of variable JEV neutralizing antibody titres and provided protection from challenge with a lethal dose of JEV. Immune splenocytes showed proliferative response after stimulation with the JEV antigen (Ag), however, it was higher for CMV promoter. The magnitude of immunity provided by APC dominant promoter was non-significantly lower in comparison to CMV promoter. More importantly, immune response directed by APC promoter was skewed towards Th1 type in comparison to CMV promoter, this was evaluated by cytokine secretion profile of immune splenocytes stimulated with JEV Ag.</p> <p>Conclusions</p> <p>Thus, our APC-expressing DNA vaccination approach induces comparable immunity in comparison to ubiquitous promoter construct. The predominant Th1 type immune responses provide opportunities to further test its potency suitable for response in antiviral or anticancer vaccines.</p