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In the current global scenario, the world is under a serious dilemma due to the increasing human population, industrialization, and urbanization. The ever-increasing need for fuels and increasing nutritional problems have made a serious concern on the demand for nutrients and renewable and eco-friendly fuel sources. Currently, the use of fossil fuels is creating ecological and economic problems. Microalgae have been considered as a promising candidate for high-value metabolites and alternative renewable energy sources. Microalgae offer several advantages such as rapid growth rate, efficient land utilization, carbon dioxide sequestration, ability to cultivate in wastewater, and most importantly, they do not participate in the food crop versus energy crop dilemma or debate. An efficient microalgal biorefinery system for the production of lipids and subsequent byproduct for nutraceutical applications could well satisfy the need. But, the current microalgal cultivation systems for the production of lipids and nutraceuticals do not offer techno-economic feasibility together with energy and environmental sustainability. This review article has its main focus on the production of lipids and nutraceuticals from microalgae, covering the current strategies used for lipid production and the major high-value metabolites from microalgae and their nutraceutical importance. This review also provides insights on the future strategies for enhanced microalgal lipid production and subsequent utilization of microalgal biomass. Graphical abstract

Lymphatic filariasis is one of the major diseases that belong to the category of neglected tropical illness. Filarial nematodes are the cause of the disease and are transmitted to humans via blood-feeding arthropod vectors. Drugs such as Albendazole, Ivermectin and diethylcarbamazine are administered either individually or in combination to overcome the progress of the lymphatic filariasis. These drugs have some minor side effects like temporary hair loss, dizziness, nausea etc. The filarial parasites have multifunctional proteins including the Glutathione-s-transferase (GST) enzyme. This study aims at the identification of a natural molecule that has the potential to bind with the GST enzyme, which plays a major role in detoxification of endogenous electrophilic compounds. Thus the binding interrupts the detoxification process within the filarial parasite, Brugia malayi. A medicinal plant Calotropis procera, owing to its anthelmintic properties was searched for the presence of potential phytocompounds. The phytocompounds were docked against the homology modeled GST enzyme using the MOE software. The results were screened and analyzed based on the Lipinski rule of 5. N-octanoate was the phytocompound obtained based on molecular docking, subjected to molecular dynamics. These results require further in vitro and in vivo validation to consider n-octanoate as a potential drug candidate for lymphatic filariasis treatment.

Severe acute respiratory syndrome coronavirus 2 (SARS‐Cov-2), a global pandemic, affected the world, increasing every day. A mutated variant D614G, showing more virulence and transmission, was studied for forecasting the emergence of more virulent and pathogenic viral strains. This study focuses on structure modeling and validation. Characterization of proteins homologous to wild spike protein was done, and homology models of the mutated variant were modeled using these proteins. Validation of models was done using Ramachandran plot and ERRAT plot. Molecular dynamics simulation was used to validate the stability of the models, and binding affinity of these models were estimated by molecular docking with an approved antiviral drug. Docked complexes were studied and the best model was selected. Molecular dynamics simulation was used to estimate the stability of the docked complex. The model of 6VXX, a homologous of wild spike protein, was found to be stable with the interaction of the antiviral drug from this study.

In the current outbreak of COVID-19, various studies have been conducted all over the world to develop effective drugs against the virus. Recent studies have shown that hydroxychloroquine, chloroquine (antimalarial drugs), isoflavones, flavonoids, etc. have potent antiviral properties, and few have been proven as effective drugs for the preventive treatment of COVID-19. But their exact action against SARS-CoV-2 is still unknown. The strategy of this study is the virtual screening of quinoline analogues, design new ligand molecules, perform molecular interaction analysis, their MD validation against multi targets (Spike-ACE2, TMPRSS2, and Spike Protein) of SARS-CoV-2, and to suggest the most promising and effective drug molecule. Hydroxychloroquine and chloroquine were considered as the reference molecules in this study. A ligand N-[4-(3-Benzylideneazetidine-1-carbonyl)phenyl]quinoline-8-sulfonamide interacting with TMPRSS2 shows better interaction among the list even after MD validation. Further in-vitro and in-vivo analysis of this study is needed for future validation.

In this pandemic condition, a drug candidate which is effective against COVID-19 is very much desired. This study initiates an in silico analysis to screen small molecules such as phytochemicals, drug metabolites, and natural metabolites against Nsp12 (a catalytic unit for RNA transcription and replication). Molecular interaction analysis of 6M71 was carried out against 2,860 ligands using Schrodinger Glide software. After docking analysis, the top 10 molecules (Glide score) were subjected to MD simulation for validating the stability. It resulted in top 10 compounds with high binding affinities with the target molecule NSP 12. Out of these, top 3 compounds including PSID_08_LIG3 (HMDB0133544), PSID_08_LIG4 (HMDB0132898), and PSID_08_LIG9 (HMDB0128199) show better Glide scores, better H-bond interaction, better MMGBSA value and stability on dynamic simulation after analysis of the results. The suggested ligands can be postulated as effective antiviral drugs against COVID-19. Further in vivo analysis is needed for validating the drug efficacy.

The COVID-19 pandemic wave has recommenced and is spreading like wildfire across the globe. The well-reported antiviral potency of phyto compounds could offer potential drug molecules for the current predicament. The present study analyses the molecular interaction of selected phyto compounds and SARS-CoV-2 molecular target proteins, namely spike protein, RNA-dependent RNA polymerase, 3C-like proteases, and papain-like protease. Ten newly modeled ligands were also considered for the study. Molecular docking analysis was carried out independently using MOE, AutoDock Vina, Schrodinger-Glide, and the stability of protein-ligand interaction was validated through molecular dynamics simulation. Petunidin interacts with spike protein resulting in a good Gscore, binding energy, and H-bond interaction. Also, alions, letestuianin-A, (+)-pinitol show better interaction with RdRp, 3CL-protease, and papain-like protease, respectively. The presented work screens through 2314 ligands to yield top-ranked molecules which could be taken up to develop potential lead molecules via in-vivo analysis.

Microalgae are unicellular photosynthetic organisms that have been recently attracted potential interests and have applications in food, nutraceuticals, pharmaceuticals, animal feed, cosmetics, and biofertilizers industry. Microalgae are rich in a variety of high-value bioactive compounds which have potential benefits on human health and can be used for the prevention and curing of many disease conditions. But scale-up and safety issues remain a major challenge in the commercialization of microalgal products in a cost-effective manner. However, techniques have been developed to overcome these challenges and successfully selling the products derived from microalgae as food, cosmetics and pharmaceutical industries. Microalgae are rich in many nutrients and can be used for the production of functional food and nutraceuticals, safety and regulatory issues are major concerns and extensive research is still needed to make microalgae a commercial success in the future. Many practical difficulties are involved in making the microalgal food industry commercially viable. The present review focuses on the industrial applications of microalgae and the challenges faced during commercial production.

Microalgae are unicellular photosynthetic organisms capable of producing high-value metabolites like carbohydrates, lipids, proteins, polyunsaturated fatty acids, vitamins, pigments, and other high-value metabolites. Microalgal biomass gained more interest for the production of nutraceuticals, pharmaceuticals, therapeutics, food supplements, feed, biofuel, bio-fertilizers, etc. due to its high lipid and other high-value metabolite content. Microalgal biomass has the potential to convert trapped solar energy to organic materials and potential metabolites of nutraceutical and industrial interest. They have higher efficiency to fix carbon dioxide (CO2) and subsequently convert it into biomass and compounds of potential interest. However, to make microalgae a potential industrial candidate, cost-effective cultivation systems and harvesting methods for increasing biomass yield and reducing the cost of downstream processing have become extremely urgent and important. In this review, the current development in different microalgal cultivation systems and harvesting methods has been discussed.

Lymphatic filariasis is one of the major diseases that belong to the category of neglected tropical illness. Filarial nematodes are the cause of the disease and are transmitted to humans via blood-feeding arthropod vectors. Drugs such as Albendazole, Ivermectin and diethylcarbamazine are administered either individually or in combination to overcome the progress of the lymphatic filariasis. However, these drugs have some disadvantages like temporary hair loss, dizziness, nausea etc. The filarial parasites have multifunctional proteins including the Glutathione-s-transferase (GST) enzyme which plays a major role in detoxification of endogenous electrophilic compounds. This study aims at the identification of a natural molecule that has the potential to bind with the GST enzyme and thus interrupt the detoxification process within the filarial parasite, Brugia malayi. A medicinal plant Calotropis procera, owing to its anthelmintic properties was searched for the presence of potential phytocompounds. The phytocompounds were docked against the homology modeled GST enzyme using the MOE software. The results were screened and analyzed based on the Lipinski rule of 5. N-octanoate was the phytocompound obtained based on molecular docking, subjected to molecular dynamics. These results require further in vitro and in vivo validation to consider n-octanoate as a potential drug candidate for lymphatic filariasis treatment.

Unchecked release of toxic heavy metals in industrial effluents and its environmental and public health implications have opened up a huge opportunity for environment biotechnological applications. Pollutants may be assimilated by the organism, disintegrated into less toxic compounds, or concentrated by adsorption onto the surface of dead biomass. Microalgae, rightly named as a “wonder organism,” are capable of accomplishing bioremediation efficiently by two mechanisms, namely, bioassimilation and biosorption. They have the capability to grow in polluted water as “algal blooms” and assimilate various pollutants. The algal biomass, after harvesting and lipid/protein extraction, could be used as an efficient biosorbent. Careful consideration of parameters such as growth conditions, cellular structure, pretreatment of biomass, etc. can result in development of a low-cost microalgae-based biomass with high bioremediation potential to neutralize and adsorb heavy metal ions. Hence, this chapter discusses the various avenues for bioremediation of toxic heavy metals using the biomass of microalgae.

Microalgae have been recommended as superior candidate for fuel production because of their advantages of higher photosynthetic efficiency, biomass & lipid productivity, and faster growth rate as compared to other energy crops. To meet up all these criteria, we have developed a continuous outdoor micro-algal raceway pond reactor (RPR) and a lab scale indoor tubular photo bioreactor (PBR) for biofuel production. An attempt to utilise indigenous sources of nutrients to improve the economics also revealed that micro-algal culturing can also be used as a mode of nutrient removal and water treatment. The photosynthetic rate and lipid production were enhanced by arresting daytime cell division and promoting night-time cell division. A 50% lipid improvement was observed for the particular algal consortia. Microscopic studies revealed that temporal phase separation could be achieved by adjusting nutrient distribution pattern. To monitor temporal phase separation, it is required to know DNA multiplication model. Quantification of gDNA in RPR confirmed that cell division happens during the night which positively affects the photosynthetic efficiency and lipid productivity of microalgae.

After decades of ‘living dangerously’, the human kind has paused to think of Mother Nature. Alternate energy sources are being developed as a part of this realization. The use of indigenous sources of nutrients would considerably bring down the cost of production. A mixed consortium of Chlorella vulgaris, Arthrospira platensis, and tap water-originated Scenedesmus dimorphus was cultured using natural seawater, anaerobic digester sludge, and its growth was compared with synthetic commercial media like Zarrouk’s media, NaNO3 media, and NH4Cl media. A spectrophotometric method was standardized for regular biomass estimation. The dry biomass of a 15-day pure, batch culture of Arthrospira was found to yield around 600 mg/L in anaerobic digester sludge, whereas the pure batch culture of chlorella’s growth was hindered mainly due to the presence of bacteria and grazers. Regular microscopic observation and biomass monitoring revealed a drastic reduction in grazing activity, with the use of autoclaved AD sludge, resulting in a strong and stable microalgal mixed consortia. The consortia growth in AD sludge was found to be better than with the synthetic media with no cost of nutrient. The mixed consortia yielded a biomass up to 600 mg/L and lipid of 21.18%. The lipid generated from AD sludge had around 95% unsaturates and contained around 5% omega-3 fatty acids. The use of anaerobic digester sludge in a non-sterile condition reduces the total cost of the biodiesel production process as a whole and introduces a decentralized system for waste water treatment as well.

Increasing textile industries in the last few decade has resulted in the discharge of very large quantities of complex chemical dye to the water system. This has affected the ecological and biological balance causing immense destruction to the nature. In this work, azo dye (Orange G 16) degradation studies by Pseudoalteramonas sp. were investigated. From the experiments, Pseudoalteromonas species degraded the Orange G 16 azo dye at a short time span within 3 h. The assay time for azoreductase activity was standardized, and maximum activity was observed at 24th. The protein concentration was estimated at three different stages of dye degradation. First stage is before addition of dye, second stage is 3 h after addition of the dye during which the dye had completely decolourized, and the third stage is 18 h after the addition of dye. From the study, it was observed that protein concentration was higher in the 24-h sample which has been induced with Orange G 16 azo dye having a concentration of 0.92 mg/ml. While comparing the total activity and specific activity of the enzyme for three samples, it was observed that the activity was higher at the 24th s and then subsided gradually. Thus, Pseudoalteromonas sp. is found to be efficient in degrading azo dyes because of its potential to degrade the dyes rapidly which also has a higher azoreductase activity.

Mass transfer is a basic phenomenon behind many processes like reaction, absorption, extraction etc. Mass transfer plays a significant role in microfluidic systems where the chemical / biological process systems are shrinkened down to a micro scale. Micro reactor system, with its high compatibility and performance, gains a wide interest among the researchers in the recent years. Micro structured reac-tors holds advantages over the conventional types in chemical processes. The significance of micro re-actor not limited to its scalability but to energy efficiency, on-site / on-demand production, reliability, safety, highly controlled outputs, etc. Liquid-liquid two phase reaction in a microreactor system is highly demandable when both reactants are liquids or when air medium cannot be suitable. This arti-cle overviews various liquid-liquid flow regimes in a microchannel. Discussions on the hydrodynamics of flow in micro scale are made. Considering the importance of mass transfer in liquid-liquid systems and the advantage of slug regime over other regimes, the article focuses especially on the mass trans-fer between two liquid phases in slug flow and the details of experimental studies carried out in this area. The advantages of slug flow over other flow regimes in micro structured reactor applications are showcased. © 2014 BCREC UNDIP. All rights reservedReceived: 31st May 2014; Revised: 6th August 2014; Accepted: 14th August 2014How to Cite: Antony, R., Giri Nandagopal, M.S., Sreekumar, N., Rangabhashiyam, S., Selvaraju, N. (2014). Liquid-liquid Slug Flow in a Microchannel Reactor and its Mass Transfer Properties - A Review. Bulletin of Chemical Reaction Engineering & Catalysis,9(3): 207-223. (doi:10.9767/bcrec.9.3.6977.207-223)Permalink/DOI: http://dx.doi.org/10.9767/bcrec.9.3.6977.207-223

Transdermal drug delivery has given cardinal contribution to medical practices. First-generation transdermal delivery of small, lipophilic, low-dose drugs and second-generation delivery systems using chemical enhancers, non-cavitational ultrasound and iontophoresis have also resulted in various clinical products provides added functionality. Third-generation delivery systems using microneedles, thermal ablation, microdermabrasion, electroporation and cavitational ultrasound targeting skin's barrier layer of stratum corneum. Microneedles acquire pronounced intrigue in recent days. Currently, microneedles are advancing through clinical trials for delivery of macromolecules and vaccines, such as insulin, parathyroid hormone and influenza vaccine. The review explains about the concept of transdermal drug microneedle system comprising of microreservoir, micropumps, flow sensors, types of microneedles. Various researches carried out on these components of microneedle system is elaborately discussed in this review.

Microfluidic sensor converts a physical quantity to useful signal with the help of microfluidic platform. Microfluidic sensors have got a wide attention in the last decade because of the increased demands from the automation and control in microsystems. This review on microfluidic sensors focuses on various types of sensors which have been developed for the microfluidic systems or applications based on the research contributions in the last decade. We start with a detailed comparison on the research developments in the last decade on microfluidic sensors with the help of year and country wise statistical charts on published works in the area. The review continues with the basics of microfluidic sensors and the working principles of microfluidic sensors by classifying various microfluidic sensors based on the parameter to be sensed. This review concludes with the attempt to provide an idea on research gap in the area of microfluidic sensors.

In the present scenario, petroleum sourced fuel consumption is unsustainable; therefore, there is a high demand for the development of renewable transport fuels for environmental and economic sustainability. Microalgal fuel, with the significant feature of being carbon neutral, serves as one of the potent tools for tackling the fuel crisis. Enormous researches have been explored using fresh water species on biodiesel production; nevertheless, marine species are still in a grey area, even though reported to have higher lipid content. The current review focuses on a wide spectrum of marine microalgal sources with phycology under the criteria of open pond systems for algal oil production. The discussion on the lipid expression in the marine species have been critically analysed through the vital parameters such as solar irradiation, temperature, pH, nutrient pressure, agitation, CO2 supply, culture depth, aeration, etc. The parameters are interdependent and, if scrutinized wisely, could result in enhanced lipid productivity. Therefore, the open pond culture of marine microalgae with top prioritized parameters such as nitrogen stress, pH, and light penetration will be a suitable combination for the efficient and effective biodiesel production.