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Biodiesel is generally obtained by transesterification and esterification of appropriate feedstocks facilitated by a catalyst. It has emerged to be one of the most potential alternatives for the conventional fuels gaining worldwide attention. Heterogeneous catalysts are usually preferred than homogeneous for biodiesel synthesis due to facile separation and insignificant soap formation. However, the separation still possesses difficulty leading to mass transfer hindrance. Therefore, these catalysts can be further modified using magnetic separation techniques to develop magnetically separable catalysts. The magnetic nanoparticles (MNPs) are notable appealing catalysts due to huge surface area, high activity, amicable functional groups and structures, adaptable properties, conformity in pore size, and facile separation have made them desirable catalyst carriers for biodiesel synthesis. The MNPs are modified via functionalization to construct magnetically recoverable heterogeneous nanocatalysts. Magnetic catalysts can be utilized as a befitting option for biodiesel synthesis as these are environmentally benign, highly reusable and economically viable. The current review article discusses different magnetic solid catalysts such as magnetic base, acid, biocatalysts and bifunctional of acid base catalysts for efficient biodiesel synthesis. The prime focus of this paper rest on the catalytic performances of various magnetically recoverable catalysts, mechanisms and recyclability for biodiesel production processes. The synthesis methods of magnetic heterogeneous base and acid nanocatalysts, magnetic properties, functionalization and their reciprocity on the catalytic activity are reviewed in this article.

Graphene oxide (GO), a 2-dimensional (2-D) monolayer of graphite, has drawn a lot of importance due to its accessibility and material compatibility. It can be produced by mechanically stirring or sonicating graphite oxide to exfoliate it into layered sheets. Due to high stability, 2-D planar structure, huge surface area, easy chemical adaptation via its functionalities, efficient surface loading with many biomolecules, and optical, electrical, and mechanical capabilities, GO and its derivatives are quickly emerging as the most intensely studied carbon-based materials in a number of fields. In this review, we provided a thorough overview of GO, synthesis of pristine and GO-based composites as well as their applications in the field of biodiesel synthesis, adsorption, photodegradation, electrochemical applications along with biological significance and their antimicrobial efficiency. Owing to their distinctive features, GO has garnered interest in the realm of catalyst. The synthesis of biodiesel via the process of transesterification using GO-based supported catalyst is highlighted herein. Similarly, the adsorption and photodegradation of several organic dyes and effluents are also discussed in this article. Finally, the electrochemical and biological importance of GO and its derived materials is discussed in relation to attractive materials trends by highlighting its future scope and commercial implications.

Abstract In a thin Weyl semimetal, a thickness dependent Weyl-orbit quantum oscillation was proposed to exist, originating from a nonlocal cyclotron orbit via electron tunnelings between top and bottom Fermi-arc surface states. Here, magneto-transport measurements were carried out on untwinned Weyl metal SrRuO3 thin films. In particular, quantum oscillations with a frequency F s1 ≈ 30 T were identified, corresponding to a small Fermi pocket with a light effective mass. Its oscillation amplitude appears to be at maximum for thicknesses in a range of 10 to 20 nm, and the phase of oscillation exhibits a systematic change with film thickness. The constructed Landau fan diagram shows an unusual concave downward curvature in the 1/μ 0 H n -n curve, where n is the Landau level index. From thickness and field-orientation dependence, the F s1 oscillation is attributed to be of surface origin. Those findings can be understood within the framework of the Weyl-orbit quantum oscillation effect with non-adiabatic corrections.

In this article, we propose a MADM-strategy based on hyperbolic cosine similarity measures under the single valued neutrosophic set environment. Further, we also give some properties of the similarity measures by giving some suitable examples. We also solve a numerical example to validate our proposed MADM-model.

Abstract The growth of SrRuO $$_3$$ 3 (SRO) thin film with high-crystallinity and low residual resistivity (RR) is essential to explore its intrinsic properties. Here, utilizing the adsorption-controlled growth technique, the growth condition of initial SrO layer on TiO $$_2$$ 2 -terminated SrTiO $$_3$$ 3 (STO) (001) substrate was found to be crucial for achieving a low RR in the resulting SRO film grown afterward. The optimized initial SrO layer shows a c(2 $$\times $$ × 2) superstructure that was characterized by electron diffraction, and a series of SRO films with different thicknesses (ts) were then grown. The resulting SRO films exhibit excellent crystallinity with orthorhombic-phase down to $$t \approx $$ t ≈ 4.3 nm, which was confirmed by high resolution X-ray measurements. From X-ray azimuthal scan across SRO orthorhombic (02 ± 1) reflections, we uncover four structural domains with a dominant domain of orthorhombic SRO [001] along cubic STO [010] direction. The dominant domain population depends on t, STO miscut angle ( $$\alpha $$ α ), and miscut direction ( $$\beta $$ β ), giving a volume fraction of about 92 $$\%$$ % for $$t \approx $$ t ≈ 26.6 nm and $$(\alpha , \beta ) \approx $$ ( α , β ) ≈ (0.14 $$^{\mathrm{o}}$$ o , 5 $$^{\mathrm{o}}$$ o ). On the other hand, metallic and ferromagnetic properties were well preserved down to t $$\approx $$ ≈ 1.2 nm. Residual resistivity ratio (RRR = $$\rho ({\mathrm{300 K}})$$ ρ ( 300 K ) / $$\rho ({\mathrm{5K}})$$ ρ ( 5 K ) ) reduces from 77.1 for t $$\approx $$ ≈ 28.5 nm to 2.5 for t $$\approx $$ ≈ 1.2 nm, while $$\rho ({\mathrm{5K}})$$ ρ ( 5 K ) increases from 2.5 $$\upmu \Omega $$ μ Ω cm for t $$\approx $$ ≈ 28.5 nm to 131.0 $$\upmu \Omega $$ μ Ω cm for t $$\approx $$ ≈ 1.2 nm. The ferromagnetic onset temperature ( $$T'_{\mathrm{c}}$$ T c ′ ) of around 151 K remains nearly unchanged down to t $$\approx $$ ≈ 9.0 nm and decreases to 90 K for t $$\approx $$ ≈ 1.2 nm. Our finding thus provides a practical guideline to achieve high crystallinity and low RR in ultra-thin SRO films by simply adjusting the growth of initial SrO layer.

Biodiesel is a renewable alternative biofuel to conventional fossil fuel. Biodiesel can be produced through esterification and transesterification reactions mainly catalyzed by acid, alkali, and enzyme catalysts. Among all of these catalysts, enzyme catalysts are more advantageous than chemical catalysts (alkali and acid catalysts) due to their high selectivity, mild reaction conditions, lower energy consumption, and yielding of good quality of products with no side reactions. However, because of the high costs of enzymes, there is a limit on the use of enzymatic operation on an industrial scale. The cost of enzymes can be reduced by improving the lifespan of catalysts. Over the last few decades, significant developments in enzyme-based biodiesel synthesis have been attained both on the laboratory and industrial scale, and production costs are also reduced. This review gives an overview of immobilized lipase-catalyzed and lipase-inorganic hybrid nanoflowers catalyzed biodiesel production, including the economic viability of enzyme catalysts and idea about different reactors which is used for enzymatic transesterification reaction.

Biodiesel is considered eco-friendly, biodegradable, non-toxic, and carbon-neutral fuel. It is made from edible or non-edible oil feedstocks including other triglyceride sources. The production of biodiesel depends on the availability of a particular feedstock and the cost of desired raw materials. Biodiesel is mainly produced by the transesterification process using a suitable catalyst preferably a heterogeneous catalyst as it is more beneficial in terms of reusability, recovery, product purity, and production cost as well. Various reactors are developed to produce cost-effective biodiesel at the commercial level. The latest trend in biodiesel synthesis is the application of the machine learning (ML) technique to optimize the process parameters. The application of a mixture of two or more oils as feedstock either non-edible or edible oil is emphasized for biodiesel synthesis and is presently getting more importance. In this paper, the production of biodiesel from various mixed oil (hybrid oil) is reviewed and the effects of mixed oil on the reaction, physicochemical properties, fatty acid composition, and fuel quality of the product are discussed. The study highlighted the activity of various catalysts in the reaction of mixed oil and the economic feasibility. It was found that the ratio of mixed oil is an important factor in terms of conversion and quality of biodiesel. It is also revealed that the application of the ML technique is essentially useful to optimize production efficiency. The utilization of mixed oils will overcome the issues related to the non-availability of feedstocks and reduce the overall cost with improved quality of biodiesel. This approach enhances the production possibility of biodiesel at a large-scale and may boost the biorefinery sector satisfying the future energy demand if the research at the advanced level goes in the right direction.

Research work presented in this study has the primary target of exploring joint attributes of AZ31 magnesium alloys using friction stir welding process with a modified tool referred as bobbin tool. Effects of inert and open atmosphere on mechanical properties are evaluated over a wide range of welding speed and tool rotation speed. Comparison of the research findings from the inert atmosphere bobbin tool were made with the traditional process of friction stir welding. The results depicted improved joint properties for inert atmosphere welding. Low and intermediate range of tool rotational speed is found to be favorable for bobbin tool friction stir welding without and with an inert medium, respectively. Controlled atmosphere due to inert medium leads to less oxidation of the AZ31 Mg alloy leading to superior joint properties. Microstructural investigations are also made with the aim of evaluating the impact of bobbin tool and inert medium on joint properties. In each aspect for joining of AZ31 Mg alloy, bobbin tool with inert medium is found to be an effective solution for joining with improved mechanical properties compared to without inert bobbin tool as well as conventional tool friction stir welding. Keywords: Mg FSW, Bobbin tool, Process parameters, Mechanical properties, Fractography, Microstructural characterization

In the present work, a solid catalyst has been derived by calcination (550 ​°C, 2 ​h) of waste sugarcane bagasse ash and applied for the production of jatropha seed oil methyl esters (JSOME). The prepared catalyst was well-characterized by using Brunauer–Emmett–Teller (BET) method, Fourier transform infrared spectrometer (FT-IR), X-ray diffractometer (XRD), Field emission scanning electron microscope (FESEM), Energy dispersive X-ray (EDX), High resolution transmission electron microscope (HRTEM) and X-ray photoelectron spectrometer (XPS). The analysis revealed that the catalyst is composed of various metal oxides and carbonates. The catalyst could produce 92.84 ​wt. % yield of JSOME (biodiesel) at 9:1 methanol to oil ratio (MTOR), 10% catalyst and at 65 ​°C in 285 ​min, and found to be reusable. The polycrystalline catalyst with a surface area of 7.66 m2 g-1 and basic strength within 10.1 < H_ < 18.4 possesses good efficacy for the reaction with turnover frequency (TOF) of 6.59 h−1. The kinetic and thermodynamic parameters of the reaction were studied. JSOME was characterized by 1H NMR and GC-MS techniques, and fuel properties were also assessed. Biodiesel synthesis with such a renewable catalyst will add value to waste sugarcane bagasse and is considered sustainable for material development.

A female Mandarin Duck Aix galericulata was sighted in Saatvoini Beel on February 10, 2014. The female of this species was characterized by grey head, with a white ring around the eye which continued as a streak behind it. In India Mandarin Duck is vagrant and there were very few reported records from India. In 1902, Baker reported six individuals Mandarin Duck on the Subansiri River, Assam. The present sighting of this species from Baksa district is the first reliable record of this species in Assam after a gap of 112 years.