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•Facile synthesis Bi2O3–TiO2 composites by a hydrothermal method.•Visible light response and high surface area.•Efficient photocatalyst for degradation of ofloxacin drug.•Excellent ...results (92% degradation efficiency in 120min).•No use of any template or oxidizing agent at normal pH of the drug.
In an attempt to synthesize efficient visible light responsive photocatalyst, we have prepared Bi2O3/TiO2 hetero-structures using a simple hydrothermal technique. The detailed characterization has been carried out using XRD, FESEM, TEM, XPS, UV–vis DRS and BET surface area analyzer. It was observed that hetero–nanostructures composed of crystalline anatase TiO2 and monoclinic α-Bi2O3 have been synthesized, with high visible light response and surface area. Photocatalytic degradation for a widely used antibiotic drug, ofloxacin was further studied in solar light illumination and it was found that complete degradation took place in 120min of photocatalytic reaction using synthesized Bi2O3/TiO2 catalyst. The photocatalytic degradation rates were also compared with that of commercially available photocatalysts such as TiO2 P25 (Degussa), PC 50 and PC 500. The plausible mechanism for photocatalytic degradation reaction taking place on the Bi2O3/TiO2 heterojunction was also studied.
A high energy content (∼122 MJ/kg H2) and presence of hydrogen-bearing compounds abundance in nature make hydrogen forth runner candidate to fulfill future energy requirements. Biomass being abundant ...and carbon neutral is one of the promising source of hydrogen production. In addition, it also addresses agricultural waste disposal problems and will bring down our dependency on fossil fuel for energy requirements. Biomass-derived bio-oil can be an efficient way for hydrogen production. Acetic acid is the major component of bio-oil and has been extensively studied by the researchers round the globe as a test component of bio-oil for hydrogen generation. Hydrogen can be generated from acetic acid via catalytic steam reforming process which is thermodynamically feasible. A number of nickel-based catalysts have been reported. However, the coke deposition during reforming remains a major challenge. In this review, we have investigated all possible reactions during acetic acid steam reforming (AASR), which can cause coke deposition over the catalyst surface. Different operating parameters such as temperature and steam to carbon feed ratio affect not only the product distribution but also the carbon formation during the reaction. Present review elaborates effects of preparation methods, active metal catalyst including bimetallic catalysts, type of support and microstructure of catalysts on coke resistance behavior and catalyst stability during reforming reactions. The present study also focuses on the effects of a combination of a variety of alkali and alkaline earth metals (AAEM) promoters on coke deposition. Effect of specially designed reactors and the addition of oxygen on carbon deposition during AASR have also been analyzed. This review based on the available literature focuses mainly on the catalyst deactivation because of coke deposition, and possible strategies to minimize catalyst deactivation during AASR.
•Discuss the production of hydrogen from biomass derived acetic acid and detailed mechanism of coke deposition.•This review consider all the possible way to minimize the coke deposition during the AcOH steam reforming.•The detail discussion of correlation of operating parameters with carbon generation.•The contributions of different active metal and support material are also discussed to reduce coke deposition.•Catalyst deactivation via active metal sintering also discussed briefly.
It has been known for a long time that thyroid hormones have prominent effects on hepatic fatty acid and cholesterol synthesis and metabolism. Indeed, hypothyroidism has been associated with ...increased serum levels of triglycerides and cholesterol as well as non-alcoholic fatty liver disease (NAFLD). Advances in areas such as cell imaging, autophagy and metabolomics have generated a more detailed and comprehensive picture of thyroid-hormone-mediated regulation of hepatic lipid metabolism at the molecular level. In this Review, we describe and summarize the key features of direct thyroid hormone regulation of lipogenesis, fatty acid β-oxidation, cholesterol synthesis and the reverse cholesterol transport pathway in normal and altered thyroid hormone states. Thyroid hormone mediates these effects at the transcriptional and post-translational levels and via autophagy. Given these potentially beneficial effects on lipid metabolism, it is possible that thyroid hormone analogues and/or mimetics might be useful for the treatment of metabolic diseases involving the liver, such as hypercholesterolaemia and NAFLD.
Carbon dioxide (CO2) injection, in form of a viscous foam, is one of the effective techniques to control premature CO2 breakthrough in subsurface carbon storage and utilization (CSU). Polysaccharides ...are often used in oilfield and its use for developing viscous CO2 foam will make the process reservoir compatible and economic. However, their efficacy should be tested at real conditions to promote better CO2 utilization in oilfield projects. This study aims to quantify the role of subsurface conditions viz., pressure, temperature, and salinity on CO2-foams prepared by non-ionic polymer (guar gum, 4000 ppm) and surfactant (TX-100, 0.25 mM). Salts i.e. potassium chloride (KCl) and magnesium sulfate (MgSO4) of varying concentration (0–8 wt%) were used. Increasing salt concentration were found to significantly affect foam stability (maximum fall of 88.88%) and CO2 molality in surfactant-polymer (SP) solution (by 73.1% at 70 bar pressure). KCl showed a greater reduction (≈8–15%) than MgSO4 (6–12%) however, increasing surfactant amount had negligible impact on CO2 molality. Additionally, microscopic analysis was performed in which initial bubble size (i.e. 40-60 μm) due to coalescence phenomenon was observed to increase to (400–460 μm) after 1 h. CO2 foams exhibited non-Newtonian shear thinning behavior where foam viscosity and elasticity were positively influenced by increase in pressure, which suggested foam potential for enhanced oil recovery (EOR) and carbon storage in subsurface environment. Foam viscosity decreased with increasing salt concentration (fall of maximum 55% when compared to zero salt content) and temperature resulting at 90 °C, foam viscosity reduces to a value of 0.05 Pa s at pressure≈ 70 bar. Finally, dynamic rheological measurements were reported to visualize viscoelastic response of foams. The viscoelastic response of CO2 foams by strain sweep measurements reported a maximum fall of 60% while 40% reduction in case of frequency sweep measurements was observed. Also, foams exhibited both elastic and viscous effects with clear cross-over between G′ and G″ at each test pressure and temperature.
•Polysaccharide based CO2 foams were investigated for carbon storage in saline conditions.•CO2 foams showed adequate stability at high pressure and temperature conditions.•CO2 foaming and foam viscosity were found dependent on temperature and salinity.•Foams exhibited solid and liquid like nature at low and high strain levels, respectively.•Proposal of CO2 foams for moderate field conditions of salinity, pressure, and temperature.
Significant advances in nanoparticle-related research have been made in the past decade, and amelioration of properties is considered of utmost importance for improving nanoparticle bioavailability, ...specificity, and catalytic performance. Nanoparticle properties can be tuned through in-synthesis and post-synthesis functionalization operations, with thermodynamic and kinetic parameters playing a crucial role. In spite of robust functionalization techniques based on surface chemistry, scalable technologies have not been explored well. The coordination enhancement
via
surface functionalization through organic/inorganic/biomolecules material has attracted much attention with morphology modification and shape tuning, which are indispensable aspects in the colloidal phase during biomedical applications. It is envisioned that surface amelioration influences the anchoring properties of nano interfaces for the immobilization of functional groups and biomolecules. In this work, various nanostructure and anchoring methodologies have been discussed, aiming to exploit their full potential in precision engineering applications. Simultaneous discussions on emerging characterization strategies for functionalized assemblies have been made to gain insights into functionalization chemistry. An overview of current advances and prospects of functionalized nanoparticles has been presented, with an emphasis on controllable attributes such as size, shape, morphology, functionality, surface features, Debye and Casimir interactions.
Significant advances in nanoparticle-related research have been made in the past decade, and amelioration of properties is considered of utmost importance for improving nanoparticle bioavailability, specificity, and catalytic performance.
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•A new method for CdS/rGO photocatalyst for hydrogen from water has been developed.•It showed a better activity compared to photocatalyst of same composition prepared by hydrothermal ...technique.•The better activity is due to an efficient charge separation.•Coupling of CdS and rGO at the interface through sulfur and a greater light absorption have been attributed to better activity.
rGO supported CdS photocatalysts has been prepared by a two steps method, i.e. impregnation of GO/rGO with CdSO4 followed by a high temperature reaction with H2S gas. Activity of this catalyst was superior to a catalyst of same composition prepared by commonly reported hydrothermal technique. Detailed microstructure studies were carried out using FTIR, PL, DRS, XRD, TEM, SAED, TPO and XPS. A much greater chemical interaction at the interface of CdS and rGO and also a higher absorption of visible light were observed in the reported catalyst. It has been concluded that the high temperature reaction with H2S has imparted n-type semiconductivity to CdS which with p-type rGO and synergy of chemical interaction at the interface has resulted into formation of a p-n hetrojunction. The formation of hetrojunction and high electron mobility of rGO has given a superior activity due to an efficient charge separation to the catalyst prepared by the technique reported in this paper.
Closed-loop recyclable and biodegradable aliphatic covalent adaptable networks (CANs) based on dynamic β-CO thioester linkages that exhibit a service temperature beyond 100 °C are reported. These ...CANs possessing tensile strength and modulus values of up to 0.3 and 3 MPa, respectively, effectively undergo stress relaxation above 100 C. The samples exhibit creep resistance ability and low hysteresis loss, and are repeatedly reprocessable at 120 C. These CANs are depolymerizable to monomers under mild conditions and lose notable mechanical strength (92.4%) and weight (76.5%) within 35 days under natural biodegradation conditions.
Suitable tailoring of the chemical environment enables the thioester linkage to be exchangeable above 100 C in the presence of Sn(Oct)
2
, which may be utilized to develop closed-loop recyclable and biodegradable covalent adaptable networks.
Thyroid hormones (THs) exert a strong influence on mammalian lipid metabolism at the systemic and hepatic levels by virtue of their roles in regulating circulating lipoprotein, triglyceride (TAG), ...and cholesterol levels, as well as hepatic TAG storage and metabolism. These effects are mediated by intricate sensing and feedback systems that function at the physiological, metabolic, molecular, and transcriptional levels in the liver. Dysfunction in the pathways involved in lipid metabolism disrupts hepatic lipid homeostasis and contributes to the pathogenesis of metabolic diseases, such as nonalcoholic fatty liver disease (NAFLD) and hypercholesterolemia. There has been strong interest in understanding and employing THs, TH metabolites, and TH mimetics as lipid-modifying drugs.
THs regulate many processes involved in hepatic TAG and cholesterol metabolism to decrease serum cholesterol and intrahepatic lipid content. TH receptor β analogs designed to have less side effects than the natural hormone are currently being tested in phase II clinical studies for NAFLD and hypercholesterolemia. The TH metabolites, 3,5-diiodo-l-thyronine (T2) and T1AM (3-iodothyronamine), have different beneficial effects on lipid metabolism compared with triiodothyronine (T3), although their clinical application is still under investigation. Also, prodrugs and glucagon/T3 conjugates have been developed that direct TH to the liver.
TH-based therapies show clinical promise for the treatment of NAFLD and hypercholesterolemia. Strategies for limiting side effects of TH are being developed and may enable TH metabolites and analogs to have specific effects in the liver for treatments of these conditions. These liver-specific effects and potential suppression of the hypothalamic/pituitary/thyroid axis raise the issue of monitoring liver-specific markers of TH action to assess clinical efficacy and dosing of these compounds.
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•A novel photocatalyst Ag/AgBr/BiOBr microplates have been synthesized by precipitation method.•The obtained band gap for Ag/AgBr/BiOBr microplates was to be 2.33eV which is ...significant in enhancing the visible light induced photocatalysis.•Degradation of a pharmaceutical drug viz. levofloxacin was obtained in a shorter duration.
Ag/AgBr/BiOBr microplates have been synthesized by precipitation method. The phase, structure, morphology and optical properties were explored by the XRD, XPS, FT-IR, FESEM, DRS and PL techniques. The band gap for Ag/AgBr/BiOBr microplates has been found to be 2.33eV which is significant in enhancing the visible light induced photocatalysis. The synthesized catalyst was consisted of tetragonal phase of BiOBr with diffraction peaks of Ag/AgBr. About 74% of levofloxacin (10mg/L, pH 8) was degraded with Ag/AgBr/BiOBr (1g/L) under 90min of irradiation. The photocatalytic degradation of levofloxacin was found to be fit with pseudo first order kinetics. The results revealed that modification of BiOBr with Ag/AgBr leads to an increase in the photocatalytic activity under visible light which may be ascribed to less e−-h+ recombination.
Synthesizing dual single-atom catalysts (DSACs) with atomically isolated metal pairs is a challenging task but can be an effective way to enhance the performance for electrochemical oxygen reduction ...reaction (ORR). Herein, well-defined DSACs of Co–Mn, stabilized in N-doped porous carbon polyhedra (named CoMn/NC), are synthesized using high-temperature pyrolysis of a Co/Mn-doped zeolitic imidazolate framework. The atomically isolated Co–Mn site in CoMn/NC is recognized by combining microscopic as well as spectroscopic techniques. CoMn/NC exhibited excellent ORR activities in alkaline (E 1/2 = 0.89 V) as well as in acidic (E 1/2 = 0.82 V) electrolytes with long-term durability and enhanced methanol tolerance. Density functional theory (DFT) suggests that the Co–Mn site is efficiently activating the O–O bond via bridging adsorption, decisive for the 4e– oxygen reduction process. Though the Co–Mn sites favor O2 activation via the dissociative ORR mechanism, stronger adsorption of the intermediates in the dissociative path degrades the overall ORR activity. Our DFT studies conclude that the ORR on an Co–Mn site mainly occurs via bridging side-on O2 adsorption following thermodynamically and kinetically favorable associative mechanistic pathways with a lower overpotential and activation barrier. CoMn/NC performed excellently as a cathode in a proton exchange membrane (PEM) fuel cell and rechargeable Zn–air battery with high peak power densities of 970 and 176 mW cm–2, respectively. This work provides the guidelines for the rational design and synthesis of nonprecious DSACs for enhancing the ORR activity as well as the robustness of DSACs and suggests a design of multifunctional robust electrocatalysts for energy storage and conversion devices.
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