A Systematic Study towards the Synthesis, Isolation, and Recrystallization of Atovaquone, an Antimalarial Drug: A Sustainable Synthetic Pathway

In the present work, studies were conducted towards the synthesis of 2-[trans-4-(4-chlorophenyl) cyclohexyl]-3-hydroxy-1 ,4-naphthoquinone 5 with systematic reaction and recrystallization condition optimization to isolate 5 in high yield with better purity. Synthesis of 5 was done by the hydrolysis of 2-[trans-4-(4-chlorophenyl) cyclohexyl]-3-chloro-1, 4-naphthoquinone 4, which was isolated by the decarboxylative condensation of trans-4-(4-chlorophenyl) cyclohexanecarboxylic acid 3 with naphthoquinone moiety. After the hydrolysis of 4, isolation of crude 5 was done by the use of acetic acid instead of dilute hydrochloric acid, product 5 was isolated in good purity with very less polar impurities. The study extends to provide the polymorphic form I of 5 by the useof solvent combination for the recrystallization, prior artreports the use of a large volume of solvent for theisolation of polymorphic form I of 5. The use of a largevolume of solvent becomes a bottleneck for thecommercial synthesis of 5

Anthropogenic impact on diazotrophic diversity in the mangrove rhizosphere revealed by nifH pyrosequencing

Diazotrophs in the mangrove rhizosphere play a major role in providing new nitrogen to the mangrove ecosystem and their composition and activity are strongly influenced by anthropogenic activity and ecological conditions. In this study, the diversity of the diazotroph communities in the rhizosphere sediment of five tropical mangrove sites with different levels of pollution along the north and south coastline of Singapore were studied by pyrosequencing of the nifH gene. Bioinformatics analysis revealed that in all the studied locations, the diazotroph communities comprised mainly of members of the diazotrophic cluster I and cluster III. The detected cluster III diazotrophs, which were composed entirely of sulfate-reducing bacteria, were more abundant in the less polluted locations. The metabolic capacities of these diazotrophs indicate the potential for bioremediation and resiliency of the ecosystem to anthropogenic impact. In heavily polluted locations, the diazotrophic community structures were markedly different and the diversity of species was significantly reduced when compared with those in a pristine location. This, together with the increased abundance of Marinobacterium, which is a bioindicator of pollution, suggests that anthropogenic activity has a negative impact on the genetic diversity of diazotrophs in the mangrove rhizosphere

Intensification of Acidogenic Fermentation for the Production of Biohydrogen and Volatile Fatty Acids—A Perspective

Utilising ‘wastes’ as ‘resources’ is key to a circular economy. While there are multiple routes to waste valorisation, anaerobic digestion (AD)—a biochemical means to breakdown organic wastes in the absence of oxygen—is favoured due to its capacity to handle a variety of feedstocks. Traditional AD focuses on the production of biogas and fertiliser as products; however, such low-value products combined with longer residence times and slow kinetics have paved the way to explore alternative product platforms. The intermediate steps in conventional AD—acidogenesis and acetogenesis—have the capability to produce biohydrogen and volatile fatty acids (VFA) which are gaining increased attention due to the higher energy density (than biogas) and higher market value, respectively. This review hence focusses specifically on the production of biohydrogen and VFAs from organic wastes. With the revived interest in these products, a critical analysis of recent literature is needed to establish the current status. Therefore, intensification strategies in this area involving three main streams: substrate pre-treatment, digestion parameters and product recovery are discussed in detail based on literature reported in the last decade. The techno-economic aspects and future pointers are clearly highlighted to drive research forward in relevant areas

Mixing regime simulation and cellulose particle tracing in a stacked frame photocatalytic reactor.

To sustainably meet the global energy demand, unconventional methods to produce renewable energy must emerge. Biofuels from cellulose (via fermentable sugar production) mediated via photocatalysis provides an alternative to conventional fossil fuels. In order to effectively drive photocatalytic processes an effective reactor design is required, the design of which is influenced by a number of key factors such as the catalyst to reactant ratio and residence time, catalyst illumination time, light penetration and distribution for the system, mass transfer limitations (mixing) and product recovery. In this study we use COMSOL Multiphysics® to simulate and assess one of the mentioned parameters – mixing regime of cellulose particles in a Stacked Frame Photocatalysis Reactor (SFPR). In the reactor design, we compare two mixers: a ‘plus’ shaped magnetic stirrer bar and an 8 blade Rushton impeller. The simulations reveal that the Rushton impeller offers a radial mixing pattern with a higher fluid velocity of 1.2m/s when compared to the stirrer bar that offers a fluid velocity of 0.9m/s. Cellulose particle tracing simulations confirm that the particle dispersion is superior in the case of the Rushton impeller as the vorticity generated during the mixing push the particles to the reactor's walls. Since the particles are forced towards the walls, there is a probability of more particles being illuminated than in the case of no or improper mixing

Cellulose II as bioethanol feedstock and its advantages over native cellulose.

Alternative renewable energy must emerge to sustainably meet the energy demands of the present and future. Current alternatives to fossil fuels are electricity from solar, wind and tidal energies and biofuels. Biofuels, especially bioethanol could be produced from lignocellulosic feedstock via pre-treatment and fermentation. The cellulose I content of most lignocellulosic feedstock is significant, yet its highly crystalline amphiphilic structure interlinked with the lignin network makes it difficult to process for bioethanol production. Processing lignocellulosic biomass via a range of physico-chemical, mechanical and biological pre-treatment methods have been well established, however a relatively new area on the use of cellulose II (a polymorph of native cellulose obtained via mercerisation or regeneration) for the production of bioethanol is still in its early stages. Hence, this review discusses in detail the advantages of using cellulose II over cellulose I as feedstock for bioethanol production. Furthermore, current green and sustainable methods for cellulose II production and the advantages and disadvantages of each method are discussed. In addition, examples from literature reporting higher fermentable sugar and bioethanol yields using cellulose II as feedstock are reviewed, thereby highlighting its importance in the field of bioethanol production. The conclusion from this review suggests that, in all the cases studied, fermentable sugar and/or bioethanol production was found to be higher when cellulose II was used as feedstock instead of native cellulose/lignocellulosic biomass. This higher yield could be attributed to the modified structural and lattice arrangement of cellulose II, its porous volume and degree of polymerisation

Sugarcane bagasse based biorefineries in India: potential and challenges

Sugarcane bagasse (SCB) is one of the world's most abundant agricultural residues and in an Indian context, ∼100 million tonnes per annum is produced. The current use of SCB is restricted to the cogeneration of steam and power; however considering its potential, cogeneration is not the best valorisation route. Furthermore, with falling electricity prices and reducing global sugar prices due to excess sugar stock, it is inevitable that the waste generated (SCB) by sugar mills are utilised for generating revenue sustainably. With this background, this review aims to put forth a biorefinery perspective based on SCB feedstock. Biogas and bioethanol are the Government of India's current focus with policies and subsidies clearly pointing towards a sizeable future market. Therefore, alongside these biofuels, high-value chemicals such as xylitol, succinic acid and lactic acid were identified as other desired products for biorefineries. This review firstly discusses SCB pre-treatment options based on end applications (saccharification or anaerobic digestion, AD). Next, state-of-the-art for each of these aspects was reviewed and our perspective on a profitable biorefinery is presented. We propose an AD based biorefinery where vortex-based hydrodynamic cavitation was found to be the best choice for pre-treatment. AD is considered not only a bioprocess for energy production here but also a ‘pre-treatment’, where partial conversion of holocellulose leads to a digestate rich in a loosened fibre matrix. This digestate rich in cellulose can be enzymatically hydrolysed and further valorised biochemically. This approach would be cost effective and provide a sustainable waste management route for sugar mills

Routing of Network Traffic on a Per-Application Basis

Wireless applications in certain domains, e.g., automotive, Internet-of-Things (IoT), etc., consume substantial amounts of bandwidth. A user accustomed to data consumption on a mobile device may be surprised to find the substantially larger amounts of data consumed via telemetry by wireless devices and sensors on their automobile. Reciprocally, a car manufacturer may not want a customer to pay for telemetry. This disclosure describes techniques to route network traffic to specific network interfaces on a per-application basis. The techniques can be implemented in a device operating system, and provide mechanisms for users and original equipment manufacturers (OEMs) to separate data costs for usage of various applications, thereby enabling a robust, secure, and connected experience

High-Level fermentative production of Lactic acid from bread waste under Non-sterile conditions with a circular biorefining approach and zero waste discharge

Bread waste (BW) is a severe solid waste management problem in Europe. The current study demonstrates an environment-friendly solution by valorising BW into lactic acid (LA) and the corresponding solid residues generated during hydrolysis and fermentation to biogas. To this end, BW was saccharified through acidic and enzymatic hydrolysis, and the hydrolysate obtained was used for LA fermentation under non-sterile conditions using thermophilic Bacillus coagulans DSM1. Maximum glucose concentration achieved during acid hydrolysis with 2% (v/v) acid loading and 20% (w/v) solid loading was 67.9 g/L glucose, with a yield of 0.34 g/g BW. The LA accumulated with concentrated BW acid hydrolysate was 102.4 g/L with yield and productivity of 0.75 g/g and 1.42 g/L. h, respectively. For enzymatic hydrolysis, three commercial amylase preparations (Amyloglucosidase, Spirizyme, Dextrozyme) were employed. The highest glucose release (98.6 g/L) and yield (0.49 g glucose/g BW) was attained with Dextrozyme from Novozymes. The fed-batch fermentation by B. coagulans was conducted, using commercial glucose and glucose-rich BW hydrolysate from Dextrozyme. The LA titer, yield and productivity obtained with pure glucose were 222.7 g/L, 0.92 g/g and 1.86 g/L.h, respectively, whereas BW hydrolysate (BWH) resulted in 155.4 g/L LA, with a conversion yield and productivity of 0.85 g/g glucose and 1.30 g/L. h, respectively. Further to the LA biosynthesis, the solid residues generated during hydrolysis and fermentation were subjected to biogas generation, resulting in 553 mL CH4/g volatile solids under batch mode. This massive LA titer amassed under non-sterile conditions and integrated biogas production using fermented residues demonstrates a high potential for an integrated biorefinery based on BW

Comparative assessment of visible light and UV active photocatalysts by hydroxyl radical quantification.

A simple method for determining hydroxyl radical yields on semiconductor photocatalysts is highly desirable, especially when comparing different photocatalyst materials. This paper reports the screening of a selection of visible light active photocatalysts such as Pt-C3N4, 5% LaCr doped SrTiO3, Sr0.95Cr0.05TiO3 and Yellow TiO2 and compares them against WO3 and ultra violet (UV) light activated TiO2 P25 (standard commercial catalysts) based on their oxidative strengths (OH radical producing capability) using a well-studied chemical probe–coumarin. 7-hydroxycoumarin, the only fluorescent hydroxylation product of this reaction can then be measured to indirectly quantify the OH radicals produced. P25 under UV light produced the highest concentration of OH radicals (16.9μM), followed by WO3 (0.56μM) and Pt-C3N4 (0.25μM). The maximum OH radical production rate for P25, WO3 and Pt-C3N4 were also determined and found to be 35.6μM/hr, 0.28μM/h and 0.88μM/h respectively. The other visible light activated photocatalysts did not produce any OH radicals primarily as a result of their electronic structure. Furthermore, it was concluded that, if any visible light absorbing photocatalysts are to be fabricated in future for the purpose of photocatalytic oxidation, their OH radical producing rates (and quantities) should be determined and compared to P25