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The advancement of economical and readily available electrocatalysts for the oxygen reduction reaction (ORR) holds paramount importance in the advancement of fuel cells and metal‐air batteries. Recently, 2D non‐metallic materials have obtained substantial attention as viable alternatives for ORR catalysts due to their manifold advantages, encompassing low cost, ample availability, substantial surface‐to‐volume ratio, high conductivity, exceptional durability, and competitive activity. The augmented ORR performances observed in metal‐free 2D materials typically arise from heteroatom doping, defects, or the formation of heterostructures. Here, the authors delve into the realm of electrocatalysts for the ORR, pivoting around metal‐free 2D materials. Initially, the merits of metal‐free 2D materials are explored and the reaction mechanism of the ORR is dissected. Subsequently, a comprehensive survey of diverse metal‐free 2D materials is presented, tracing their evolutionary journey from fundamental concepts to pragmatic applications in the context of ORR. Substantial importance is given on the exploration of various strategies for enhancing metal‐free 2D materials and assessing their impact on inherent material performance, including electronic properties. Finally, the challenges and future prospects that lie ahead for metal‐free 2D materials are underscored, as they aspire to serve as efficient ORR electrocatalysts. [ABSTRACT FROM AUTHOR]

The corrosion environment of offshore carbon capture, utilization and storage(CCUS) is harsher compared to onshore conditions, with pipelines and facilities exposed to marine environments externally and containing supercritical CO2 and corrosive impurities internally. In this paper, the corrosion risks and material selection for offshore facilities in CCUS were reviewed. The corrosion risks of metals included those induced by CO2-H2O phases, gas-phase impurities and Cl-. Material selection for metals mainly involved carbon steel, low-alloy steel and corrosion-resistant alloys, which were chosen according to different CCUS conditions. Additionally, non-metallic materials underwent chemical corrosion and physical degradation in supercritical CO2 environments. Increased permeability and expansion rates, and decreased mechanical properties were observed after supercritical CO2 testing. There was a risk of aging in non-metallic pipelines after long-term service. At present, further improvement was needed in understanding the corrosion failure mechanisms of materials in supercritical CO2 systems. Material selection for CCUS offshore facilities was still immature, especially under complex conditions involving multiple impurity gases, requiring more research to refine the selection system of CCUS offshore facility materials and support the large-scale application of CCUS offshore technology.

Copyright of China Mining Magazine is the property of China Mining Magazine Co., Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract The advancement of economical and readily available electrocatalysts for the oxygen reduction reaction (ORR) holds paramount importance in the advancement of fuel cells and metal‐air batteries. Recently, 2D non‐metallic materials have obtained substantial attention as viable alternatives for ORR catalysts due to their manifold advantages, encompassing low cost, ample availability, substantial surface‐to‐volume ratio, high conductivity, exceptional durability, and competitive activity. The augmented ORR performances observed in metal‐free 2D materials typically arise from heteroatom doping, defects, or the formation of heterostructures. Here, the authors delve into the realm of electrocatalysts for the ORR, pivoting around metal‐free 2D materials. Initially, the merits of metal‐free 2D materials are explored and the reaction mechanism of the ORR is dissected. Subsequently, a comprehensive survey of diverse metal‐free 2D materials is presented, tracing their evolutionary journey from fundamental concepts to pragmatic applications in the context of ORR. Substantial importance is given on the exploration of various strategies for enhancing metal‐free 2D materials and assessing their impact on inherent material performance, including electronic properties. Finally, the challenges and future prospects that lie ahead for metal‐free 2D materials are underscored, as they aspire to serve as efficient ORR electrocatalysts.

As a kind of energy conversion equipment with high energy conversion efficiency and green pollution-free characters, fuel cells are expected to improve the current situation of high fossil energy consumption and promote green development. The high cost and poor electrochemical performance of cathode oxygen reduction catalysts in fuel cells limit their commercialization. At present, researchers are actively developing new oxygen reduction catalysts with high catalytic activity and stability. The research progress of cathodic oxygen reduction catalysts is reviewed, and its future development direction and research progress are prospected. [ABSTRACT FROM AUTHOR]

Developing highly conductive, stable, and active hydrogen evolution reaction (HER) catalysts is a critical step towards establishing the hydrogen economy. However, there are few catalysts, except for noble metals, that can meet all the requirements. Recently, two-dimensional (2D) transition metal carbon/nitride (MXene) materials have shown excellent performance in catalysis, and have attracted wide attention from researchers. In this study, the effectiveness of non-metal element (B, C, N, P, and S)-doped Ti3C2O2 MXene in the electrocatalytic hydrogen evolution reaction was investigated using density functional theory (DFT) calculations. Non-metal atoms as electron donors can provide additional electrons to the O functional group on the catalyst surface, thereby reducing charge transfer from H to O and the interaction between H and O. The Gibbs free energy (∆GH) of non-metal element-doped Ti3C2O2 is closer to 0 than that of pristine Ti3C2O2, demonstrating better hydrogen evolution performance. Furthermore, in the hydrogen evolution path, the desorption process is more inclined to the Heyrovsky mechanism, and doping greatly reduces the energy barrier of the reaction, thereby improving the catalytic efficiency. The present results prove that doping with non-metallic elements is an effective means of improving the catalytic activity of Ti3C2O2 for hydrogen evolution.

Numerous catalysts have been widely investigated for accelerating hydrogen production from NaBH 4 hydrolysis. However, these catalysts are usually complicated in structures, costly in fabrication, and hazardous for environment. In this work, cheap and environment-friendly acetic acid, CH 3 COOH, is employed to promote NaBH 4 hydrolysis to produce hydrogen in a considerable rate. The experimental results demonstrate that the addition of suitable amount of CH 3 COOH into NaBH 4 solutions stabilized with NaOH could dramatically accelerate the hydrolysis reaction. Additionally, the start/stop of NaBH 4 hydrolysis could be controlled by adding acid or base into the solution to realize "go-as-you-please" on-site hydrogen production. [Display omitted] • CH 3 COOH is used to promote NaBH 4 hydrolysis to produce hydrogen rapidly. • The mechanism of CH 3 COOH-promoted NaBH 4 hydrolysis is provided based on the characterizations of products. • The production of hydrogen can be controlled in the way "go-as-you-please" by adding acid or base. [ABSTRACT FROM AUTHOR]

Abstract With the increasing demand to reduce emissions and save energy, hydraulic reservoirs require new architecture to optimize their weight, space, and volume. Conventional open reservoirs are large, heavy, and easily polluted, and threaten the operation of hydraulic systems. A closed reservoir provides the advantages of small volume and light weight, compared to open reservoirs. In this study, a non-metallic pressure reservoir with variable volume is designed and manufactured for closed-circuit hydraulic systems. The reservoir housing is made of rubber, and the Mooney-Rivlin model is chosen based on the rubber strain properties. The FEA simulation for the reservoir is performed using ANSYS Workbench to obtain the structural stiffness. The major contribution is the establishment of mathematical models for this reservoir, including the volume equation changing with height, flow equation, and force balance equation, to explore the output characteristics of this reservoir. Based on these results, simulation models were built to analyze the output characteristics of the reservoir. Moreover, the test rig of a conventional hydraulic system was transformed into a closed-circuit asymmetric hydraulic system for the reservoir, and preliminary verification experiments were conducted on it. The results demonstrate that the designed reservoir can absorb and discharge oil and supercharge pump inlet to benefit system operation. The changes in the volume and pressure with displacements under different volume ratios and frequencies were obtained, which verified the accuracy of the mathematical models. Owing to its lightweight design and small volume, the reservoir can replace conventional open reservoirs, and this lays a foundation for future theoretical research on this reservoir.

The deposition and distribution of impurities on a series of fixed bed residue hydrotreating spent catalysts were studied by elemental analyzer, electron microprobe, etc. Results indicated that along the flow direction,the amount of coke on spent catalysts increased which was basically within the range of 7%~14% except HG-1 and the nitrogen amount was positively related to the amount of coke, while sulfur amount declined in spent catalysts; The amount of metal deposition along the flow direction of the reaction bed increased first and then decreased, and was mainly deposited on the catalyst in the form of Ni3S4 and NiV2S4; Iron and calcium were mainly deposited on the outer surface of the catalyst particles, the radial distribution of nickel was relatively uniform along the cross section of the catalyst particles, meanwhile, vanadium easily deposited on the near surface of the catalyst, showing "M"-shaped like pattern with more at the edge of the catalyst and lower in center; The pore structure of protective agents and demetallization agents was damaged badly due to the combined action of coke deposition and metal deposition and the recovery ratio of pore structure was relatively low after heat treatment; Coke deposition seriously affected the pore structures of both desulfurization agents and carbon residue removal agents and the pore structure was greatly recovered due to the elimination of coke deposition. [ABSTRACT FROM AUTHOR]

Perovskite oxides, with structural and compositional flexibility, have been extensively used as electrocatalysts in alkaline solutions for the oxygen evolution reaction (OER) which is a key factor in determining the overall efficiency of metal-air batteries or hydrogen evolution from electrochemical water splitting. The cation-doping approach is widely used to generate novel perovskite oxides with boosted electrocatalytic activity, while non-metal and metalloid modifications have received far less attention. Herein, we show a simple non-metal/metalloid alteration method to make efficient OER electrocatalysts with low overpotential and good stability. The developed SrCo 0.95 M 0.05 O 3−δ (M = P, S, and Si) catalysts exhibit greatly improved OER activity and stability in comparison to the pristine hexagonal SrCoO 3−δ. SrCo 0.95 Si 0.05 O 3−δ achieves the lowest OER overpotential of 0.41 V at 10 mA cm disk − 2 and the lowest Tafel slope of 63 mV dec−1, while SrCoO 3−δ exhibits 0.46 V and 95 mV dec−1 under identical conditions. SrCo 0.95 Si 0.05 O 3−δ further demonstrates improved stability when compared to SrCoO 3−δ. The creation of a stable cubic perovskite structure with an increased amount of oxygen vacancy facilitates oxygen diffusivity, thus maximizing the lattice oxygen participation. Furthermore, the surface evolution and the enhanced room-temperature electrical conductivity jointly contribute to the improvement of the electrocatalytic OER activity of SrCo 0.95 M 0.05 O 3−δ. Our present findings offer a simple and viable strategy for creating highly efficient perovskites for OER. [Display omitted] • The non-metal/metalloid modification was applied to perovskite electrocatalysts. • SrCo 0·95 Si 0·05 O 3−δ exhibited a low overpotential of 0.41 V at 10 mA cm disk − 2 . • The cubic structure and increased oxygen vacancies facilitated oxygen diffusivity. • The surface evolution and high conductivity also contributed to the activity. [ABSTRACT FROM AUTHOR]

Developing highly conductive, stable, and active hydrogen evolution reaction (HER) catalysts is a critical step towards establishing the hydrogen economy. However, there are few catalysts, except for noble metals, that can meet all the requirements. Recently, two-dimensional (2D) transition metal carbon/nitride (MXene) materials have shown excellent performance in catalysis, and have attracted wide attention from researchers. In this study, the effectiveness of non-metal element (B, C, N, P, and S)-doped Ti3 C2 O2 MXene in the electrocatalytic hydrogen evolution reaction was investigated using density functional theory (DFT) calculations. Non-metal atoms as electron donors can provide additional electrons to the O functional group on the catalyst surface, thereby reducing charge transfer from H to O and the interaction between H and O. The Gibbs free energy (ΔG H) of non-metal element-doped Ti3 C2 O2 is closer to 0 than that of pristine Ti3 C2 O2, demonstrating better hydrogen evolution performance. Furthermore, in the hydrogen evolution path, the desorption process is more inclined to the Heyrovsky mechanism, and doping greatly reduces the energy barrier of the reaction, thereby improving the catalytic efficiency. The present results prove that doping with non-metallic elements is an effective means of improving the catalytic activity of Ti3 C2 O2 for hydrogen evolution. [ABSTRACT FROM AUTHOR]

The buffering Cadmium–Imidazole Coordination Polymer (Cd–Im-CP) was synthesized hydrothermally from cadmium chloride and imidazole at 70 °C and then was subjected to doping- by the non-metal sulfur using Na2S solution as a novel modification strategy to produce S–Cd–Im CPs. To investigate doping nature and its effects, Cd–Im CP and S–Cd–Im CPs were characterized applying different analyses techniques, FTIR, Raman, PXRD, SEM/EDX, TGA, and UV–Vis DRS analyses. Characterizations showed the successful chemical doping of sulfur. The inclusion of sulfur within chemical CP structure caused narrowing of material's bandgap from 4.55 and 3.4 eV to 4.25 and 2.35 eV for S–Cd–Im CPs allowing it for photoresponse towards Visible-light. Both Cd–Im CP and S–Cd–Im CPs were applied for photocatalytic degradation of the selected dyes methylene blue (MB),and methyl orange (MO) employing visible and UV irradiations considering three different initial pH levels to investigate the consequence of sulfur doping. After eliminating the photolysis effect, the best degradation by S–Cd–Im CPs was recorded for MB at initial pH 4 being 13 fold that is for Cd–Im CP. The highest apparent turnover frequencies are 1.2 × 10−3 h−1 for MB at initial pH 10 and 1.03 × 10−4 h−1 for MO at initial pH 4 are given by 10S–Cd–IM CP under Visible-light. Generally, S–Cd–Im CPs remarkably improved photocatalysis degradation of both the dyes for all initial pH levels under Visible-light. [ABSTRACT FROM AUTHOR]

Copyright of Balikesir Health Sciences Journal / Balıkesir Sağlık Bilimleri Dergisi is the property of Balikesir Health Sciences Journal (BAUN Health Sci J) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Nine kinds of non-metal atoms adsorbed into germanium carbide (NM-GeC) systems wereare investigated by first-principles calculations. The results show that the most stable adsorption positions vary with the NM atoms, and C-GeC exhibits the strongest adsorption. The adsorption of NM atoms causes changes in the electronic, optical and magnetic properties of the GeC system. F- and Cl-GeC turn into magnetic metals, P-GeC becomes a half-metal and H- and B-GeC appear as non-magnetic metals. Although C- and O-GeC remain non-magnetic semiconductors, N-GeC presents the behaviors of a magnetic semiconductor. Work function decreases in H-, B- and N-SiC, reaching a minimum of 3.37 eV in H-GeC, which is 78.9% of the pristine GeC. In the visible light region, redshifts occur in the absorption spectrum of C-GeC , with strong absorption in the wavelength range from 400 to 600 nm. Our analysis shows that the magnetism in semiconducting NM-GeC is attributed to the spinning state of the unbonded electrons of the NM atoms. Our study demonstrates the applications of NM-GeC in spintronics, optoelectronics and photovoltaic cells, and it provides a reference for analyzing magnetism in semiconducting NM materials. [ABSTRACT FROM AUTHOR]

With the increasing demand to reduce emissions and save energy, hydraulic reservoirs require new architecture to optimize their weight, space, and volume. Conventional open reservoirs are large, heavy, and easily polluted, and threaten the operation of hydraulic systems. A closed reservoir provides the advantages of small volume and light weight, compared to open reservoirs. In this study, a non-metallic pressure reservoir with variable volume is designed and manufactured for closed-circuit hydraulic systems. The reservoir housing is made of rubber, and the Mooney-Rivlin model is chosen based on the rubber strain properties. The FEA simulation for the reservoir is performed using ANSYS Workbench to obtain the structural stiffness. The major contribution is the establishment of mathematical models for this reservoir, including the volume equation changing with height, flow equation, and force balance equation, to explore the output characteristics of this reservoir. Based on these results, simulation models were built to analyze the output characteristics of the reservoir. Moreover, the test rig of a conventional hydraulic system was transformed into a closed-circuit asymmetric hydraulic system for the reservoir, and preliminary verification experiments were conducted on it. The results demonstrate that the designed reservoir can absorb and discharge oil and supercharge pump inlet to benefit system operation. The changes in the volume and pressure with displacements under different volume ratios and frequencies were obtained, which verified the accuracy of the mathematical models. Owing to its lightweight design and small volume, the reservoir can replace conventional open reservoirs, and this lays a foundation for future theoretical research on this reservoir. [ABSTRACT FROM AUTHOR]

• High-quality GOQDs were prepared by an improved one-step hydrothermal method. • GOQDs decorated on multi-dimensional carbon skeleton to obtained a novel N,S-GOQD-RGO/CNT electrocatalysts. • Significantly enhanced limiting current density and higher half-wave potential than commercial Pt/C. • The zinc-air battery exhibits a better maximum power density than Pt/C+Ru/C. For the design of electrocatalysts, the combination between components and the regulation of material structures tend to be neglected, giving rise to the constraint of catalytic performance and durability. Herein, we developed a graphene oxide quantum dots (GOQDs) with enhanced oxygen content by a one-step cutting method. Then, one-dimensional (1D) carbon nanotubes and two-dimensional (2D) reduced graphene oxide are crosslinked and self-assembled, thus attracting unsaturated-bond-riches GOODs (0D) to uniformly attach to the skeleton, simultaneously achieving nitrogen and sulfur co-doping. To the best of our knowledge, there is no report to prepare bifunctional electrocatalyst with GOQDs. Electrochemical tests show that even without metal-doping, the novel non-metal bifunctional electrocatalyst (N,S-GOQD-RGO/CNT) exhibits a higher half-wave potential (0.84 V) and enhanced limiting current density (5.88 mA cm−2) than commercial Pt/C catalyst. The density functional theory is implemented to reveal the coordination of nitrogen and sulfur co-doping on GOQDs, which results in the improvement of overall catalytic active sites. Furthermore, the rechargeable zinc-air battery based on N,S-GOQD-RGO/CNT exhibits a maximum power density of 134.3 mW cm−2, open circuit potential of 1.414 V, which is better than Pt/C+Ru/C mixed material. The obtained N,S-GOQD-RGO/CNT will provide a perspective application in fuel cells. [ABSTRACT FROM AUTHOR]

Nine kinds of non-metal atoms adsorbed into germanium carbide (NM-GeC) systems wereare investigated by first-principles calculations. The results show that the most stable adsorption positions vary with the NM atoms, and C-GeC exhibits the strongest adsorption. The adsorption of NM atoms causes changes in the electronic, optical and magnetic properties of the GeC system. F- and Cl-GeC turn into magnetic metals, P-GeC becomes a half-metal and H- and B-GeC appear as non-magnetic metals. Although C- and O-GeC remain non-magnetic semiconductors, N-GeC presents the behaviors of a magnetic semiconductor. Work function decreases in H-, B- and N-SiC, reaching a minimum of 3.37 eV in H-GeC, which is 78.9% of the pristine GeC. In the visible light region, redshifts occur in the absorption spectrum of C-GeC , with strong absorption in the wavelength range from 400 to 600 nm. Our analysis shows that the magnetism in semiconducting NM-GeC is attributed to the spinning state of the unbonded electrons of the NM atoms. Our study demonstrates the applications of NM-GeC in spintronics, optoelectronics and photovoltaic cells, and it provides a reference for analyzing magnetism in semiconducting NM materials.

The demarcation of the chemical elements into metals and non-metals dates back to the dawn of Dmitri Mendeleev's construction of the periodic table; it still represents the cornerstone of our view of modern chemistry. In this contribution, a particular emphasis will be attached to the question 'Why do the chemical elements of the periodic table exist either as metals or non-metals under ambient conditions?' This is perhaps most apparent in the p-block of the periodic table where one sees an almost-diagonal line separating metals and non-metals. The first searching, quantum-mechanical considerations of this question were put forward by Hund in 1934. Interestingly, the very first discussion of the problem--in fact, a prequantum- mechanical approach--was made earlier, by Goldhammer in 1913 and Herzfeld in 1927. Their simple rationalization, in terms of atomic properties which confer metallic or non-metallic status to elements across the periodic table, leads to what is commonly called the Goldhammer-Herzfeld criterion for metallization. For a variety of undoubtedly complex reasons, the Goldhammer-Herzfeld theory lay dormant for close to half a century. However, since that time the criterion has been repeatedly applied, with great success, to many systems and materials exhibiting non-metal to metal transitions in order to predict, and understand, the precise conditions for metallization. Here, we review the application of Goldhammer-Herzfeld theory to the question of the metallic versus non-metallic status of chemical elements within the periodic system. A link between that theory and the work of Sir Nevill Mott on the metal-non-metal transition is also highlighted. The application of the 'simple', but highly effective Goldhammer-Herzfeld and Mott criteria, reveal when a chemical element of the periodic table will behave as a metal, and when it will behave as a non-metal. The success of these different, but converging approaches, lends weight to the idea of a simple, universal criterion for rationalizing the instantly-recognizable structure of the periodic table where . . . the metals are here, the non-metals are there . . . The challenge of the metallic and non-metallic states of oxides is also briefly introduced. [ABSTRACT FROM AUTHOR]

At Fraunhofer IWS Dresden, different, partially prototypic high-power continuous wave (cw) beam sources for the remote laser processing of nonmetals with galvanometric-driven scanner systems are available. The emitted wavelengths of the lasers cover the range from visible light to mid-infrared. A spectroscopic analysis was performed to gain insight into the processability of typical nonmetal materials with single wavelengths. The wavelength-depending absorption was calculated based on the measured reflectivity and transmissivity of the selected materials. Relating to these results, the theoretic potential of the beam sources was verified in a comparable cutting research. The investigated work pieces are representatives of the groups of thermoplastics and thermosets, fiber-reinforced polymers, glasses, natural fiber textiles, and cellulosic based materials. The laser systems were divided in two groups for the investigation. To get a reference of the processability with state-of-the-art cw systems, a CO2 laser with a wavelength of 10.6 μm and a solid-state Yb:YAG fiber laser with 1.07 μm were used. The new prototypic beam sources were a green laser with a wavelength of 0.515 μm, a CO laser with a range of 5.3–5.8 μm, and a CO2 laser with 9.3 μm in a power range from 1 to 1.5 kW. Differences in the possible focusability are caused by the wavelengths and given beam qualities. For a direct comparison, these differences needed to be compensated. To get comparable intensities, the spot diameter in the working distance for each laser was set to 250 μm. This allows to process the materials with almost the same intensities. Since the laser sources with the short wavelengths offer a better focusability, experiments with the smallest possible focus diameters for the used optics were performed to get an optimized ablation result. Finally, the aim of the research was to evaluate the suitability of the available beam sources for new fields of application. The latest results of experimental and theoretical investigations on the remote laser processing of nonmetals with a wide range of laser wavelength will be presented and discussed. [ABSTRACT FROM AUTHOR]

Ni-Co-B catalyst consisting of different ratios of Ni and Co was successfully synthesized via a simple electroless deposition method on stainless steel (SS) gauze substrate. Among various ratios, the Ni-Co-B of the ratio (0.09 M/0.01 M, designated as Ni-Co-B-MR1) exhibited higher electrochemical response towards methanol oxidation in alkaline medium with a highest current density about 11.3 mA/cm2 at a potential of − 0.65 V. The electrode exhibited improved CO tolerance for methanol oxidation reaction (MOR) in alkaline medium. The surface morphology and composition of the SS gauze coated with Ni-Co-B-MR1 catalyst was analysed using SEM and energy dispersive X-ray analysis. XRD confirms the presence of orthorhombic nickel boride and cobalt boride structure. The XPS analysis confirms the active presence of nickel boride and cobalt boride on SS gauze coated with Ni-Co-B-MR1 catalyst. The BET surface area of SS gauze coated with Ni-Co-B-MR1 catalyst was 1.21 m2 g−1. The single direct methanol fuel cell with SS gauze coated with Ni-Co-B-MR1 electrode produces a current density of about 0.1 mA/cm2 and power density about 10 mW/cm2, respectively. [ABSTRACT FROM AUTHOR]

With the advancement of additive manufacturing technologies in their material processing methodologies and variety of material selection, 3D printers are widely used in both academics and industries for various applications. It is no longer rare to have a portable and small desktop 3D printer and manufacture your own designs in a few hours. Desktop 3D printers vary in their functions, prices, materials used, and applications. Among many desktop 3D printers with various features, it is often challenging to select the best one for target applications and usages. In this paper, commercially available and carefully selected thermoplastic and photopolymer desktop 3D printers are introduced, and some representative models’ specifications and performances are compared with each other for user selection with respect to instructional applications. This paper aims to provide beginner-level or advanced-level end-users of desktop 3D printers with basic knowledge, selection criteria, a comprehensive overview of 3D printing technologies, and their technical features, helping them to evaluate and select the right 3D printers for a wide range of applications.

There exists a relationship between stock returns and trading volume in the world capital market and the changes in stock return does impact trading volume or trading volume does impact stock return. Some studies show that there is high degree relationship and some research studies show moderate or low or no relationship between stock return and trading volume. The present research paper attempts to examine empirical status of selected companies from non-metal, real estate and mining industries in India for finding out relationship between stock returns and trading volume. Hence, changes in returns and volume do reflect a relationship in non-metal industry but not in mining and real estate. Therefore, there is no randomness in the behaviour of stock return and trading volume changes in this study of non-metal industry in India. But in case of empirical analysis of three industries at firm level the result shows moderate degree of relationship between returns and volume of all 81companies from non-metal, real estate and mining industries.

Herein, we report the synthesis of novel nitrogen doped reduced graphene oxide/ BiVO 4 photo catalyst by single step hydrothermal method. The physicochemical properties of the catalysts were characterized using XRD, N 2 adsorption-desorption, Raman, XPS, SEM TEM, DRS-UV and EIS techniques. The synthesized catalysts were tested for their catalytic activity in the photo degradation of some harmful textile dyes (methylene blue & congo red) and antibiotics (metronidazole and chloramphenicol) under visible light irradiation. Reduced charge recombination and enhanced photocatalytic activity were observed due to the concerted effect between BiVO 4 and nitrogen-rGO. The degradation efficiency of BiVO 4 /N-rGO in the degradation of CR and MB was remarkably high i.e 95% and 98% under visible light irradiation. Similarly 95% of MTZ and 93% of CAP were degraded under visible light irradiation. HPLC studies implied that both the dyes and antibiotics were degraded to the maximum extent. The plausible photocatalytic mechanism on the basis of experimental results was suggested. [ABSTRACT FROM AUTHOR]

Titanium dioxide is a well-known photoactive semiconductor with a variety of possible applications. The procedure of pollutant degradation is mainly performed using TiO 2 powder suspension. It can also be exploited an immobilized catalyst on a solid support. Morphology and chemical doping have a great influence on TiO 2 activity under illumination. Here we compare photoactivity of titania nanotube arrays doped with non-metal atoms: nitrogen, iodine and boron applied for photodegradation of organic dye - methylene blue and terephtalic acid. The doped samples act as a much better photocatalyst in the degradation process of methylene blue and lead to the formation of much higher amount of hydroxyl radicals (•OH) than undoped TiO 2 nanotube arrays. The use of a catalyst active under solar light illumination in the form of thin films on a stable substrate can be scaled up for an industrial application. [ABSTRACT FROM AUTHOR]

Developing clean and renewable energy to replace fossil fuels becomes an urgent task. Especially, direct methanol fuel cells (DMFC) are considered as the potential candidate. The large-scale application of Pt-based electrocatalysts as the most active electrocatalysts towards methanol oxidation is limited by the cost and scarcity. Therefore, exploring low-cost electrocatalysts with higher catalytic activity has been focused on by scientists from different countries. In this work, we have prepared the N doped Co 3 O 4 hollow microspheres as highly efficient electrocatalysts towards methanol oxidation in basic solution. The electrocatalytic activity of N-Co 3 O 4 toward methanol oxidation in the mixture of KOH (1 M) and CH 3 OH (1 M) is evaluated by cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. In comparison with that of the existing non-metallic doped metal oxide modified electrodes, the prepared N-Co 3 O 4 demonstrates higher electrocatalytic activity together with higher stability toward methanol oxidation. The current density of N-Co 3 O 4 is 23.87 mA cm−2 toward methanol oxidation, which is 3.2 times higher than that of Co 3 O 4 (7.47 mA cm−2). The current retention rate of N-Co 3 O 4 and Co 3 O 4 is 65.7% and 58.3% after 500 cycles, respectively. Methanol oxidation was catalyzed by doping Co 3 O 4 with nitrogen. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: Anatase TiO2 doping with boron, carbon, nitrogen, and fluorine atoms has been considered in a systematic study by performing periodic DFT calculations with the hybrid B3LYP functional and large supercells. The effect on the electronic structure of replacing lattice O atoms with B, C, N, or F dopants, or to include the same atoms in interstitial positions has been considered. Clear trends emerge as a function of the atomic number of the doping element. B, C, and N atoms in substitutional positions result in magnetic impurities whose energy levels fall in the energy gap of the material. The position of these gap states closely follows the effective nuclear charge of the dopant, with B that gives states high in the gap and N which introduces states just above the top of the valence band. Fluorine, being very electronegative, has filled states below the O 2p valence band and leads to the formation of Ti3+ ions due to charge compensation. Interstitial impurities have a quite different electronic structure, which again depends on the nuclear effective charge. B acts as a net electron donor with formation of B3+ and three Ti3+ ions; C donates only two electrons to the lattice with formation of a C2+ ion; N forms a direct bond with a lattice O, and does not donate electrons to the host lattice. We also discuss possible internal charge transfers between high-lying electronic states in the gap (Ti3+ 3d1 states) and low-lying acceptor states of the dopant. The interplay between substitutional and interstitial dopants, between dopants and oxygen vacancies or titanium interstitials, and between co-dopants (B,N; N,F) are discussed in view of their beneficial effects for photocatalytic processes. [Copyright &y& Elsevier]

The oxidation of organic compounds is of extreme importance in synthetic chemistry. The catalysts provide high selectivity towards the oxidation products employing with the oxidants. This review is not intended to give a complete survey of all oxidation catalysis reactions by different catalysts but rather to give a summary of some important catalytic oxidation reactions by different metal and non-metal based catalysts. [ABSTRACT FROM AUTHOR]

Abstract: The inversion degree of a series of nanocrystalline samples of CoFe2O4 ferrites has been evaluated by a combined study, which exploits the saturation magnetization at 4.2K and 57Fe Mössbauer spectroscopy. The samples, prepared by sol–gel autocombustion, have different thermal history and particle size. The differences observed in the saturation magnetization of these samples are explained in terms of different inversion degrees, as confirmed by the analysis of the components in the Mössbauer spectra. It is notable that the inversion degrees of the samples investigated are set among the highest values reported in the literature. [Copyright &y& Elsevier]

• Review of graphene-assisted construction strategies of both metal and non-metal based electrocatalysts. • Discussion of CO 2 RR electrocatalytic performances of various graphene − metal composites. • Overview of enhancement approaches of the graphene-based non-metal CO 2 RR catalytic activities. • Challenges and perspectives for the future development of graphene-based CO 2 RR electrocatalysts. The electrochemical conversion of the greenhouse gas, carbon dioxide (CO 2), to energy fuels and value-added chemicals presents one of the most valuable approaches to harvest pollutants and produce renewable energy. However, the stable molecular structure of CO 2 and the sluggish reaction kinetics make CO 2 reduction reaction (CO 2 RR) formidably challenging to achieve reaction rate and selectivity practical in industry. Graphene and its derivatives have been considered a group of intriguing materials to develop advanced CO 2 RR electrocatalysts due to their large specific surface area, remarkable electron transfer ability, superior stability, and easy tunability of the structure and surface properties. Herein, we comprehensively discuss the state-of-the-art electrocatalysts constructed with graphene and derivatives for active and selective CO 2 RR within the recent five years, mainly including the electrocatalysts with both metal-based (e.g., noble, non-noble, or combined thereof) and non-metal (e.g., doped, modified, defected, or composited) catalytic sites. To present the versatile, high-performance metal-based CO 2 RR electrocatalysts constructed with graphene, we further subdivide them according to the sizes, oxidation states, metal species synergies, dimensionalities, and versatility. Finally, we provide the challenges and perspectives in this emerging area of utilising CO 2 to produce various carbon-based fuels and chemicals via graphene chemistry. [ABSTRACT FROM AUTHOR]

With the advancement of additive manufacturing technologies in their material processing methodologies and variety of material selection, 3D printers are widely used in both academics and industries for various applications. It is no longer rare to have a portable and small desktop 3D printer and manufacture your own designs in a few hours. Desktop 3D printers vary in their functions, prices, materials used, and applications. Among many desktop 3D printers with various features, it is often challenging to select the best one for target applications and usages. In this paper, commercially available and carefully selected thermoplastic and photopolymer desktop 3D printers are introduced, and some representative models' specifications and performances are compared with each other for user selection with respect to instructional applications. This paper aims to provide beginner-level or advanced-level end-users of desktop 3D printers with basic knowledge, selection criteria, a comprehensive overview of 3D printing technologies, and their technical features, helping them to evaluate and select the right 3D printers for a wide range of applications. [ABSTRACT FROM AUTHOR]

The demarcation of the chemical elements into metals and non-metals dates back to the dawn of Dmitri Mendeleev's construction of the periodic table; it still represents the cornerstone of our view of modern chemistry. In this contribution, a particular emphasis will be attached to the question 'Why do the chemical elements of the periodic table exist either as metals or non-metals under ambient conditions?' This is perhaps most apparent in the p-block of the periodic table where one sees an almost-diagonal line separating metals and non-metals. The first searching, quantum-mechanical considerations of this question were put forward by Hund in 1934. Interestingly, the very first discussion of the problem-in fact, a pre-quantum-mechanical approach-was made earlier, by Goldhammer in 1913 and Herzfeld in 1927. Their simple rationalization, in terms of atomic properties which confer metallic or non-metallic status to elements across the periodic table, leads to what is commonly called the Goldhammer-Herzfeld criterion for metallization. For a variety of undoubtedly complex reasons, the Goldhammer-Herzfeld theory lay dormant for close to half a century. However, since that time the criterion has been repeatedly applied, with great success, to many systems and materials exhibiting non-metal to metal transitions in order to predict, and understand, the precise conditions for metallization. Here, we review the application of Goldhammer-Herzfeld theory to the question of the metallic versus non-metallic status of chemical elements within the periodic system. A link between that theory and the work of Sir Nevill Mott on the metal-non-metal transition is also highlighted. The application of the 'simple', but highly effective Goldhammer-Herzfeld and Mott criteria, reveal when a chemical element of the periodic table will behave as a metal, and when it will behave as a non-metal. The success of these different, but converging approaches, lends weight to the idea of a simple, universal criterion for rationalizing the instantly-recognizable structure of the periodic table where … the metals are here, the non-metals are there … The challenge of the metallic and non-metallic states of oxides is also briefly introduced. This article is part of the theme issue 'Mendeleev and the periodic table'.

Background: A wide variety of biological activities are exhibited by N, O and S containing heterocycles and recently, many reports appeared for the synthesis of these heterocycles. The synthesis of heterocycles with the help of metal and non-metal catalyst has become a highly rewarding and important method in organic synthesis. This review article concentrated on the synthesis of S-heterocylces in the presence of metal and non-metal catalyst. The synthesis of five-membered S-heterocycles is described here., Objective: There is a need for the development of rapid, efficient and versatile strategy for the synthesis of heterocyclic rings. Metal, non-metal and organocatalysis involving methods have gained prominence because traditional conditions have disadvantages such as long reaction times, harsh conditions and limited substrate scope., Conclusion: The metal-, non-metal-, and organocatalyst assisted organic synthesis is a highly dynamic research field. For ßthe chemoselective and efficient synthesis of heterocyclic molecules, this protocol has emerged as a powerful route. Various methodologies in the past few years have been pointed out to pursue more sustainable, efficient and environmentally benign procedures and products. Among these processes, the development of new protocols (catalysis), which avoided the use of toxic reagents, are the focus of intense research., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Herein, we report the synthesis of novel nitrogen doped reduced graphene oxide/ BiVO 4 photo catalyst by single step hydrothermal method. The physicochemical properties of the catalysts were characterized using XRD, N 2 adsorption-desorption, Raman, XPS, SEM TEM, DRS-UV and EIS techniques. The synthesized catalysts were tested for their catalytic activity in the photo degradation of some harmful textile dyes (methylene blue & congo red) and antibiotics (metronidazole and chloramphenicol) under visible light irradiation. Reduced charge recombination and enhanced photocatalytic activity were observed due to the concerted effect between BiVO 4 and nitrogen-rGO. The degradation efficiency of BiVO 4 /N-rGO in the degradation of CR and MB was remarkably high i.e 95% and 98% under visible light irradiation. Similarly 95% of MTZ and 93% of CAP were degraded under visible light irradiation. HPLC studies implied that both the dyes and antibiotics were degraded to the maximum extent. The plausible photocatalytic mechanism on the basis of experimental results was suggested., (Copyright © 2018 Elsevier Inc. All rights reserved.)