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Benzodiazepines (BZDs) represent a diverse class of bicyclic heterocyclic molecules. In the last few years, benzodiazepines have emerged as potential therapeutic agents. As a result, several mild, efficient and high yielding protocols have been developed that offer access to various functionalized benzodiazepines (BZDs). They are known to possess a wide array of biological activities such as anxiolytic, anticancer, anticonvulsant, antipsychotics, muscle relaxant, anti-tuberculosis, and antimicrobial activities. The fascinating spectrum of biological activities exhibited by BZDs in various fields has prompted the medicinal chemist to design and discover novel benzodiazepine-based analogs as potential therapeutic candidates with the desired biological profile. In this review, an attempt has been made by to summarize (1) Recent advances in the synthetic chemistry of benzodiazepines which enable their synthesis with desired substitution pattern; (2) Medicinal chemistry of BZDs as therapeutic candidates with promising biological profile including insight of mechanistic studies; (3) The correlation of biological data with the structure i.e. structure-activity relationship studies were also included to provide an insight into the rational design of more active agents.

In the present investigation, finite volume method is applied for the thermal performance prediction of a hybrid earth to air tunnel heat exchanger whereas process parameters are optimized using response surface methodology. A commercial CFD based software-ANSYS Fluent is used to simulate the heat exchanger. RNG k – ɛ turbulence model was selected to carry out a two-dimensional simulation modelling. Moreover, response surface methodology is applied to analyse the results of finite volume method and to optimize the process parameters of hybrid earth to air tunnel heat exchanger (HEAHX). The numerical results obtained from HEAHX are compared with that of individual EAHX. It is found that performance of HEAHX is about three times higher than as compared to individual EAHX. In addition, the theoretical results of present study are validated with theoretical results obtained from previous works and a good agreement is achieved. The maximum difference between the outlet and inlet air temperatures of hybrid and individual earth to air heat exchangers at the optimum value of input parameters are found to be 49.83 K and 14.4 K, respectively.

In the present work, analytical models to predict the thermal and thermohydraulic efficiencies of two different designs of double pass packed bed solar air heater under external recycle have been proposed. It is predicted that Model A with the single air pass through the first channel as well as the recycle of the air exiting from the second channel through the third channel can enhance the heat transfer rate more as compared to Model B. The wire mesh screen as an absorbing media above the absorber plate is used in both of the solar air heater models. The recycle ratio and the mass flow rate are varied from 0.1 to 1 and 0.01–0.025 kg/s, respectively. The results of the study depict that the recycle ratio and the mass flow rate substantially increases the heaters efficiencies by increasing the fluid velocity. The maximum value of the thermal efficiency of Model A is found to be about 6.6% higher than that of Model B. The optimum values of the recycle ratio and the mass flow rate, at which the heaters yield maximum values of thermo-hydraulic efficiencies, are identified and presented. In addition, the effect of the channel depth ratio on the thermal performance improvement is also delineated.

In the modern scenario, the quinolone scaffold has emerged as a very potent motif considering its clinical significance. Quinolones possess wide range of pharmacological activities such as anticancer, antibacterial, antifungal, antiprotozoal, antiviral, anti-inflammatory, carbonic anhydrase inhibitory and diuretic activity etc. The versatile synthetic approaches have been successfully applied and several of the resulted synthesized compounds exhibit fascinating biological activities in numerous fields. This has prompted to discover quinolone-based analogues among the researchers due to its great diversity in biological activities. In the past few years, various new, efficient and convenient synthetic approaches (including green chemistry and microwave-assisted synthesis) have been designed and developed to synthesize diverse quinolone-based scaffolds which represent a growing area of interest in academic and industry as well as to explore their biological activities. In this review, an attempt has been made by the authors to summarize (1) One of the most comprehensive listings of quinolone-based drugs or agents in the market or under various stages of clinical development; (2) Recent advances in the synthetic strategies for quinolone derivatives as well as their biological implications including insight of mechanistic studies. (3) Further, the biological data is correlated with structure-activity relationship studies to provide an insight into the rational design of more active agents.

A design of a parallel flow solar air heater with packed material in its upper channel and capable of providing a higher heat flux compared to the conventional non-porous bed double flow systems is presented. An analytical model describing the various temperatures and heat transfer characteristics of such a parallel flow packed bed solar air heater (PFPBSAH) has been developed and employed to study the effects of the mass flow rate and varying porosities of the packed material on its thermal performance. The model employs an iterative solution procedure to solve the governing energy balance equations describing the complex heat and mass exchanges involved. To validate the proposed analytical model, comparisons between theoretical and experimental results showed that good agreement is achieved with reasonable accuracy. Also, PFPBSAH is found to perform more efficiently than the conventional non-porous double flow solar air heaters with 10–20% increase in its thermal efficiency. Furthermore, the effect of the fraction of mass flow rate in the upper or lower flow channel of PFPBSAH device on its performance, has also investigated theoretically. The fraction of the mass flow rate in the respective channels of the PFPBSAH is shown to be dominant parameter in determining the effective thermal efficiency of the heater.

In the present study, the thermal and effective thermal efficiencies of a double-flow packed-bed solar air heater with an external recycle are investigated theoretically. An analytical model capable of predicting the thermal and effective thermal performances of the heater is presented. The effects of the mass flow rate, the recycle ratio, and the bed porosity on the thermal and effective thermal efficiencies of the heater are investigated. It is indicated that the recycle ratio significantly improves the thermal performance of a double-pass packed-bed solar air heater. The results revealed that the thermal and effective thermal efficiencies of the heater are about 21.3 and 25.4% higher when compared to a conventional-type solar air collector of the same size with an external recycle. The optimum values of the recycle ratio, the mass flow rate, and the bed porosity, at which the heater yields the maximum value of effective thermal efficiency, are identified and presented. The results of the therma...