Microalgal Biorefinery Concepts’ Developments for Biofuel and Bioproducts: Current Perspective and Bottlenecks

Microalgae have received much interest as a biofuel feedstock. However, the economic feasibility of biofuel production from microalgae does not satisfy capital investors. Apart from the biofuels, it is necessary to produce high-value co-products from microalgae fraction to satisfy the economic aspects of microalgae biorefinery. In addition, microalgae-based wastewater treatment is considered as an alternative for the conventional wastewater treatment in terms of energy consumption, which is suitable for microalgae biorefinery approaches. The energy consumption of a microalgae wastewater treatment system (0.2 kW/h/m³) was reduced 10 times when compared to the conventional wastewater treatment system (to 2 kW/h/m³). Microalgae are rich in various biomolecules such as carbohydrates, proteins, lipids, pigments, vitamins, and antioxidants; all these valuable products can be utilized by nutritional, pharmaceutical, and cosmetic industries. There are several bottlenecks associated with microalgae biorefinery. Hence, it is essential to promote the sustainability of microalgal biorefinery with innovative ideas to produce biofuel with high-value products. This review attempted to bring out the trends and promising solutions to realize microalgal production of multiple products at an industrial scale. New perspectives and current challenges are discussed for the development of algal biorefinery concepts.     

Facile green synthesis approach for the production of chromium oxide nanoparticles and their different in vitro biological activities

Green synthesis of nanoparticles using plants has become a promising substitute for the conventional chemical synthesis methods. In the present study, our aim was to synthesize chromium oxide nanoparticles (Cr₂O₃NPs) through a facile, low‐cost, eco‐friendly route using leaf extract of Rhamnus virgata (RV). The formation of Cr₂O₃NPs was confirmed and characterized by spectroscopic profile of UV–Vis, EDX, FTIR, and XRD analyses. The UV‐visible spectroscopy has confirmed the formation of Cr₂O₃NPs by the change of color owing to surface plasmon resonance. The bioactive functional groups present in the leaf extract of RV involved in reduction and stabilization of Cr₂O₃NPs were determined by FTIR analysis. Based on XRD analysis, crystalline nature of Cr₂O₃NPs was determined. The morphological shape and elemental composition of Cr₂O₃NPs were investigated using SEM and EDX analyses, respectively. With growing applications of Cr₂O₃NPs in biological perspectives, Cr₂O₃NPs were evaluated for diverse biopotentials. Cr₂O₃NPs were further investigated for its cytotoxicity potentials against HepG2 and HUH‐7 cancer cell lines (IC₅₀: 39.66 and 45.87 μg/ml), respectively. Cytotoxicity potential of Cr₂O₃NPs was confirmed against promastigotes (IC₅₀: 33.24 μg/ml) and amastigotes (IC₅₀: 44.31 μg/ml) using Leishmania tropica (KMH₂₃). The Cr₂O₃NPs were further evaluated for antioxidants, biostatic, alpha‐amylase, and protein kinase inhibition properties. Biocompatibility assay was investigated against human macrophages which confirmed the nontoxic nature of Cr₂O₃NPs. Overall, the synthesized Cr₂O₃NPs are biocompatible and nontoxic and proved to possess significant biopotentials. In future, different in vivo studies are needed to fully investigate the cytotoxicity and mechanism of action associated with these Cr₂O₃NPs.     

Comparison of Mechanical Properties of Acid and UV Ozone Treated Nanodiamond Epoxy Nanocomposites

Nanodiamond（ND） powder was successfully activated by wet chemical method and by exposure of UV/O3 in a chamber followed by mixing in triethylenetetramine（TETA） solution.The reinforcement role of activated ND in the mechanical properties of epoxy matrix was studied.Both treatments,i.e.acid and UV/O3 provide ND surface with chemical functionalities for adhesion with epoxy resin.Fourier transform infrared spectroscopy was utilized to confirm the attachment of surface groups to the ND particles.The low content of acid and UV/O3 activated ND was dispersed ultrasonically in the epoxy matrix separately to make nanocomposites.The mechanical properties of the nanocomposites were investigated under three point bending.The strong interactions among activated ND particles and the epoxy resin provide efficient load transfer interfaces,which enhances the mechanical properties of the composites.It was found that the flexural strength,modulus,and toughness of 0.1 wt%ND loaded nanocomposites have been enhanced up to 85%,57%,and 39%,respectively for UV/O3 treated ND powder.It is also found that the optimum ND concentration to achieve maximum reinforcement is 0.1 wt%while higher concentrations lead to decrease in mechanical properties.The significant improvement of the mechanical properties of the ND/epoxy nanocomposites is attributed to the good dispersion of the functionalized ND in epoxy matrix.     

Glucose Detection Devices and Methods Based on Metal–Organic Frameworks and Related Materials

Assessment of glucose concentration is important in the diagnosis and treatment of diabetes. Since the introduction of enzymatic glucose biosensors, scientific and technological advances in nanomaterials have led to the development of new generations of glucose sensors. This field has witnessed major developments over the last decade, as the novel nanomaterials are capable of efficiently catalyzing glucose directly (i.e., act as artificial enzymes, therefore defined nanozymes) or to entrap enzymes that are able to oxidize glucose. Among other nanomaterials, metal–organic frameworks (MOFs) have recently provided a tremendous basis to construct glucose sensing devices. MOFs are large porous crystalline compounds with versatile structural and tuneable chemical properties. In addition, they possess catalytic, peroxidase-like, and electrochemical redox activity. This review comprehensively summarizes the general characteristics of MOFs, their subtypes, and MOF composites, as well as MOF-derived materials employed to construct electrochemical, optical, transistor, and microfluidic devices for the detection of glucose. They include enzymatic, nonenzymatic, wearable, and flexible sensing devices and methods. The review also outlines the design and synthesis of MOFs and the working principles of the different transduction-based glucose sensors and highlights the current challenges and future perspectives.     

Error Detection and Pattern Prediction Through Phase II Process Monitoring

The continuous monitoring of the machine is beneficial in improving its process reliability through reflected power function distribution. It is substantial for identifying and removing errors at the early stages of production that ultimately benefit the firms in cost-saving and quality improvement. The current study introduces control charts that help the manufacturing concerns to keep the production process in control. It presents an exponentially weighted moving average and extended exponentially weighted moving average and then compared their performance. The percentiles estimator and the modified maximum likelihood estimator are used to constructing the control charts. The findings suggest that an extended exponentially weighted moving average control chart based on the percentiles estimator performs better than exponentially weighted moving average control charts based on the percentiles estimator and modified maximum likelihood estimator. Further, these results will help the firms in the early detection of errors that enhance the process reliability of the telecommunications and financing industry.     

Strong interfacial charge transfer between hausmannite manganese oxide and alumina for efficient photocatalysis

Well crystalline manganese oxide(Mn_3O_4) nanoparticles anchored on gamma alumina(γ-Al_2O_3) have been successfully tailored via a proficient and cost effective chemical process as an efficient material for photo catalysis. XRD indicated the composite formation of γ-Al_2O_3 and hausmannite structure of Mn_3O_4. SEM and TEM revealed that hetero structure of Mn_3O_4/γ-Al_2O_3 exhibits an amalgam of aggregated nanoparticles and nanorods. XPS demonstrated the chemical states of binary nanocomposite.The band gap tuning has been performed with γ-Al_2O_3 nanoparticles by assimilating hausmannite Mn_3O_4 particles into flower like microstructure of Al_2O_3. The photoluminescence spectra affirmed the enhancement in charge separation in Mn_3O_4/γ-Al_2O_3 binary hybrid photocatalyst. The band gap becomes narrow with the increase in concentrations of Mn_3O_4. The narrowing of band gap is concorded with crystalline domains of primary aggregated particles. To elucidate the mechanism of the photocatalytic activity linear sweep voltammetry was performed. The results showed that Mn_3O_4/γ-Al_2O_3 nanocomposite revealed the enhancement in current density as compared to pure γ-Al_2O_3 which confirmed the electron transfer from Mn_3O_4 to γ-Al_2O_3 through the interfacial potential gradient in conduction bands. The optimum concentration of 6.0% Mn_3O_4/γ-Al_2O_3 for hybrid structure showed an excellent photocatalytic activity under visible light due to narrow band gap energy. High degree distribution of Mn_3O_4 nano architects overlying on γ-Al_2O_3 induces a significant synergic effect between γ-Al_2O_3 and hausmannite phase of manganese oxide(Mn_3O_4). This strong interfacial contact between γ-Al_2O_3 and Mn_3O_4 endures the quick transfer of photo generated charge carriers across interface.     

Fabrication and evaluation studies of novel polyvinylpyrrolidone and 2-acrylamido-2-methylpropane sulphonic acid-based crosslinked matrices for controlled release of acyclovir

Polymer Bulletin - The aim of the present study was to fabricate chemically crosslinked matrix system of polyvinylpyrrolidone (PVP)-co-poly 2-acrylamido-2-methylpropane sulphonic acid (AMPS)...     

Effect of crosslinker feed content on catalaytic activity of silver nanoparticles fabricated in multiresponsive microgels

We investigated the effect of crosslinking density of poly(N-isopropyl acrylamide-co-acrylic acid) microgels on catalytic activity of silver nanoparticles fabricated hybrid microgels. Multiresponsive poly(N-isopropyl acrylamide-co-acrylic acid) microgels with 2, 4, 6 and 8 mole percentage of N,N-methylene-bis-acrylamide were synthesized by emulsion polymerization. These microgels were characterized by dynamic light scattering and were used as microreactors to synthesize silver nanoparticles. Hybrid system was characterized by ultraviolet-visible spectroscopy. The catalytic activity of hybrid microgels with different crosslinker content was compared by studying the reduction of pnitrophenol as a model reaction. Kinetics of reaction was monitored by spectrophotometry. The value of the apparent rate constant decreases from 0.568 to 0.313min^?1, when content of crosslinker are increased from 2 to 8 mole percentage respectively. This decreases in value of apparent rate constant is due to increase in diffusional barrier offered by high crosslinking of polymer network at high mole percentages of N,N-methylene-bis-acrylamide.