Search

Hot spot engineering in plasmonic nanostructures plays a significant role in surface-enhanced Raman scattering (SERS) for bioanalysis and cell imaging. However, creating stable, reproducible, and strong SERS signals remains challenging due to the potential interference from surrounding chemicals and locating SERS-active analytes into hot-spot regions. Herein, we developed a straightforward approach to synthesize intra-gap nanoparticles encapsulating 4-nitrobenzenethiol (4-NBT) as a reporter molecule within these gaps to avoid outside interference. We made three kinds of intra-gap nanoparticles using nanorods, bipyramids, and nanospheres as cores, in which the nanorods based intra-gap nanoparticles exhibit the highest SERS activity. The advantage of our method is the ease of preparation of high-yield and stable intra-gap nanoparticles characterized by a short incubation time (10 min) with 4-NBT and quick synthesis without requiring an additional step to centrifuge for the purification of core nanoparticles. The intense localized field in the synthesized hot spots of these plasmonic gap nanostructures holds great promise as a SERS substrate for a broad range of quantitative optical applications. [ABSTRACT FROM AUTHOR]

The separation and purification of chemical raw materials, particularly neutral compounds with similar physical and chemical properties, represents an ongoing challenge. In this study, we introduce a class of water-soluble macrocycle compound, calix[2]azolium[2]benzimidazolone (H), comprising two azolium and two benzimidazolone subunits. The heterocycle subunits form a hydrophobic binding pocket that enables H1 to encapsulate a series of neutral guests in water with 1:1 or 2:1 stoichiometry, including aldehydes, ketones, and nitrile compounds. The host-guest complexation in the solid state was further confirmed through X-ray crystallography. Remarkably, H1 was shown to be a nonporous adaptive crystal material to separate valeraldehyde from the mixture of valeraldehyde/2-methylbutanal/pentanol with high selectivity and recyclability in the solid states. This work not only demonstrates that azolium-based macrocycles are promising candidates for the encapsulation of organic molecules but also shows the potential application in separation science. The separation and purification of particularly neutral compounds with similar physical and chemical properties remains challenging. Here, the authors introduce a water-soluble macrocyclic calixarene compound as nonporous adaptive crystalline material to separate valeraldehyde from the mixture of valeraldehyde/2-methylbutanal/pentanol with high selectivity and recyclability in the solid state. [ABSTRACT FROM AUTHOR]

As genomic databases expand and artificial intelligence tools advance, there is a growing demand for efficient characterization of large numbers of proteins. To this end, here we describe a generalizable pipeline for high-throughput protein purification using small-scale expression in E. coli and an affordable liquid-handling robot. This low-cost platform enables the purification of 96 proteins in parallel with minimal waste and is scalable for processing hundreds of proteins weekly per user. We demonstrate the performance of this method with the expression and purification of the leading poly(ethylene terephthalate) hydrolases reported in the literature. Replicate experiments demonstrated reproducibility and enzyme purity and yields (up to 400 µg) sufficient for comprehensive analyses of both thermostability and activity, generating a standardized benchmark dataset for comparing these plastic-degrading enzymes. The cost-effectiveness and ease of implementation of this platform render it broadly applicable to diverse protein characterization challenges in the biological sciences. [ABSTRACT FROM AUTHOR]

Structural and physicochemical properties of two types of bacterial cellulose (BC) produced by Komagateibacter sucrofermentans strain DSM 15973T after 7 days through either immobilized bacteria (solid inoculum) forming BCS7 or free bacteria (liquid inoculum) forming BCL7, followed by a water-based purification as a chem-free alternative treatment, were investigated in this study. SEM verifies the effectiveness of the water-based purification on BC network and reveals the insufficient interfibrillar space of BCS7 compared to BCL7. BCL7 was generally proved to be superior to BCS7 regarding degree of purification, BC yield, overall higher porosity, water swell ability, and water holding capacity (WHC), exhibiting higher hydrophilicity. However, thermally resistant BCS7 reveals a 35% residual up to 800 ºC compared to BCL7 (15%) and prevailed in terms of water retention rate. Both water-treated BC7 were proved to be Iα-rich cellulose type and exhibited a typical type IV(a) isotherm with an H3 type of hysteresis loop, a similar pore distribution, crystallinity index (~77%), crystallite size (~7.5 cm), same levels of moisture content (~98%) and the same poor levels of rehydration after the freeze-drying process. During BCL kinetics in 20 mL of HS medium over 7 days, K. sucrofermentans, 2D pellicle formation was observed until day 3 and then 3D. The highest WHC was obtained on day 4 (116 g water/g cellulose), while the lowest on day 1 (19 g water/g cellulose). Overall, we discussed the preparation and characterization of two different BCs water-treated for purification as an eco-friendly alternative method towards functional, and sustainable application. [ABSTRACT FROM AUTHOR]

A hydrothermal synthesis method was developed to produce high crystallinity ZSM-5 zeolite using coal gasification coarse slag (CGCS) as the raw material. Instead of the expensive NaOH(s.), Na2SiO3(s.) was utilized to activate, depolymerize, and recombine Si and Al elements in the CGCS. The mother liquor circulation technology was employed to recover and reuse raw materials and residual reagents (Na2SiO3(aq.) and TPABr), reducing waste emissions and enhancing resource utilization efficiency. The synthesized ZSM-5 had a specific surface area of 455.675 m2 g−1, pore volume of 0.284 cm3 g−1, and pore diameter of 2.496 nm. The influence of various factors on the morphology and crystallinity of ZSM-5 was investigated, resulting in the production of ZSM-5 with higher specific surface area and pore volume. Adsorption experiments showed that WU-ZSM-5 exhibited a removal efficiency of 85% for ammonia nitrogen (NH4+-N(aq.)), validating its effectiveness in coal chemical wastewater purification. The mother liquor recycling technology enabled zero-emission utilization of solid waste resources and improved the utilization rate of alkali and template to 90%. These results demonstrate the potential application of the developed method in the efficient treatment of coal chemical wastewater. [ABSTRACT FROM AUTHOR]

As a non-metallic material, high-purity graphite has been widely used in many high-tech fields and has become an important raw material for its production and processing. As the purity of graphite increases, its application value will also increase. Therefore, it is necessary to purify graphite. In this study, the natural flake graphite is purified by the additive-assisted alkali melting-acid leaching process to produce high-purity graphite. Alkali melting is the main process in the alkali-acid process. Therefore, this paper is mainly to explore the removal mechanism of impurities in the alkali melting process. First, the influence of various factors on the purification efficiency in the process of alkali melting is investigated. The fixed carbon content of graphite can reach 99.9815% and 99.9569%, respectively, when 4% (accounting for graphite mass) of sodium metaborate and potassium pyrosulfate is added as additives under the best process conditions. The results show that the crystal structure and morphology of graphite have no obvious changes. Compared with the traditional alkaline melting-acid leaching process, the carbon content of natural flake graphite can be increased to a higher level by an auxiliary alkaline melting-acid leaching process. [ABSTRACT FROM AUTHOR]

A flexible technology for the production of high purity inorganic acids has been developed, which includes the stages of chemical purification, rectification, desorption, adsorption, absorption, composition correction, and microfiltration. It is shown that one of the most important stages of the technology is chemical purification, which makes it possible to convert volatile impurities into non-volatile ones, and also to carry out deep purification of acids from arsenic impurities. A pilot installation for studying the process has been created. Based on the conducted research, a chemical purification module has been was developed. [ABSTRACT FROM AUTHOR]

High-purity tellurium is a supporting material for contemporary high-tech industries. Zone refining is commonly used as a reliable final purification step to achieve higher purity levels of tellurium. However, the removal of Selenium (Se)—the most troublesome impurity in tellurium often occurring in quite high amounts—stays as the challenge during zone refining, due to its very unfavorable distribution coefficient. In addition, there is an important factor, essential to predict the zone refining efficiency (required number of passes), which is still seldom explored. Therefore, in the present work, the effect of different number of passes on the purification effect of tellurium was investigated by using 4N tellurium as raw material. Firstly, the possibility of removing vaporized Se through introducing an reductive gas flux was studied by testing initial concentrations of Se (13 ppm) and undergoing different process parameters. The experimental results showed that when the number of passes was 3, the impurity removal rate was low and the purification effect was poor; when the number of zone refining reached 9, the removal rate of most impurities in tellurium reached 100 pct, the removal rate of impurity Se reached 80.15 pct, and the total removal rate reached 89.49 pct, and the purity of tellurium ingot was 5N7. [ABSTRACT FROM AUTHOR]

Millions of people across the globe are severely afflicted because of water potability issues, and to proffer a solution to this crisis, efficient and cost-effective desalination techniques are necessitated. Membranes, in particular Graphene-derived membranes, have emerged as a potential answer to this grave problem because of their tunable ionic and molecular sieving capability, thin structure, and customizable microstructure. Among graphene-derived membranes, Graphene Oxide membranes have been the most promising, given the replete presence of oxygen-containing functional groups on its surface. However, the prospects of commercial applicability of these membranes are currently plagued by uneven stacking, crossflow delamination, flawed pores, screening and pH effects, and horizontal defects in the membrane. In addition, due to the selectivity–permeability trade-off that commonly exists in all membranes, the separation efficiency is negatively influenced. This review, while studying these challenges, aims to outline the most recent ground-breaking developments in graphene-based membrane technology, encompassing their separation mechanism, selectivity, adjustable mechanical characteristics, and uses. Additionally, we have covered in detail how several process variables such as temperature, total oxygen concentration, and functional groups affect the effectiveness of membrane separation with the focal point tilted toward studying the currently used intercalation techniques and effective nanomaterial graphene oxide membranes for water desalination [ABSTRACT FROM AUTHOR]

Hexavalent chromium (Cr(VI)) is still a common contaminant in water. In this work, we studied the Cr(VI) adsorption by polyphenol-rich bacterial cellulose(BC) gel, synthesized by the Komagataeibacter rhaeticus K15 using wine pomace. The results showed that the equilibrium removal capacity was 473.09 ± 1.41 mg g−1 (dry weight). The quasi-second-order kinetics model and the Langmuir removal isotherm model was the most suitable for describing the Cr(VI) removal process. Toxic Cr(VI) was converted to the low toxic Cr(III) during the removal process via the reduction of Cr(VI) to Cr(III) by polyphenols released into the solution by the BC gel. The FTIR, XRD, XPS, SEM-EDX results indicated the physical adsorption on the surface of BC and the reduction reaction between polyphenol groups and Cr(VI) is the critical mechanism of Cr(VI) removal by BC. The finding of this study demonstrates that polyphenols-rich BC gel produced from wine pomace has a superior feature for future Cr(VI)-wastewater purification. [ABSTRACT FROM AUTHOR]

Improving the quantum coherence of solid-state systems is a decisive factor in realizing solid-state quantum technologies. The key to optimize quantum coherence lies in reducing the detrimental influence of noise sources such as spin noise and charge noise. Here we demonstrate that we can utilize highly-excited Rydberg excitons to neutralize charged impurities in the semiconductor Cuprous Oxide - an effect we call purification. Purification reduces detrimental electrical stray fields drastically. We observe that the absorption of the purified crystal increases by up to 25% and that the purification effect is long-lived and may persist for hundreds of microseconds or even longer. We investigate the interaction between Rydberg excitons and impurities and find that it is long-ranged and based on charge-induced dipole interactions. Using a time-resolved pump-probe technique, we can discriminate purification from Rydberg blockade, which has been a long-standing goal in excitonic Rydberg systems. Charged impurities are a major source of charge noise in semiconductors. Here, using pump-probe time-resolved relative transmission measurements on cuprous oxide, the authors demonstrate a strategy for mitigating charged impurities by injection and subsequent breakdown of Rydberg excitons. [ABSTRACT FROM AUTHOR]

Purification of valuable engineered proteins and enzymes can be laborious, costly, and generating large amount of chemical waste. Whilst enzyme immobilization can enhance recycling and reuse of enzymes, conventional methods for immobilizing engineered enzymes from purified samples are also inefficient with multiple-step protocols, regarding both the carrier preparation and enzyme binding. Nickel ferrite magnetic nanoparticles (NiFe2O4 MNPs) offer distinct advantages in both purification and immobilization of enzymes. In this work, we demonstrate the preparation of NiFe2O4 MNPs via a one-step solvothermal synthesis and their use in direct enzyme binding from cell lysates. These NiFe2O4 MNPs have showed an average diameter of 8.9 ± 1.7 nm from TEM analysis and a magnetization at saturation (Ms) value of 53.0 emu g–1 from SQUID measurement. The nickel binding sites of the MNP surface allow direct binding of three his-tagged enzymes, d-phenylglycine aminotransferase (d-PhgAT), Halomonas elongata ω-transaminase (HeωT), and glucose dehydrogenase from Bacillus subtilis (BsGDH). It was found that the enzymatic activities of all immobilized samples directly prepared from cell lysates were comparable to those prepared from the conventional immobilization method using purified enzymes. Remarkably, d-PhgAT supported on NiFe2O4 MNPs also showed similar activity to the purified free enzyme. By comparing on both carrier preparation and enzyme immobilization protocols, use of NiFe2O4 MNPs for direct enzyme immobilization from cell lysate can significantly reduce the number of steps, time, and use of chemicals. Therefore, NiFe2O4 MNPs can offer considerable advantages for use in both enzyme immobilization and protein purification in pharmaceutical and other chemical industries. [ABSTRACT FROM AUTHOR]

The use of heavy actinide targets, including 243Am, 240,242,244Pu, 245,248Cm, 249Bk, and 249Cf, irradiated by intense heavy ion beams of 48Ca has resulted in a significant expansion of the periodic table since 2000, including the discovery of five new heaviest elements and more than 50 new isotopes. These actinide materials can only be produced by intense neutron irradiation in very high flux reactors followed by chemical processing and purification in specialized hot cell facilities available in only a few locations worldwide. This paper reviews the reactor production of heavy actinides, the recovery and chemical separation of actinide materials, and the preparation of actinide targets for superheavy element experiments. The focus is on 248Cm, 249Bk, mixed 249−251Cf, and 254Es, including current availabilities and new production processes. The impacts of new facilities, including the Superheavy Element Factory at Dubna, accelerator and separator upgrades at RIKEN, and proposed upgrades to the High Flux Isotope Reactor at Oak Ridge are also described. Examples of recent superheavy element research are discussed as well as future opportunities for superheavy research using actinide targets. [ABSTRACT FROM AUTHOR]

Macroporous-interconnected cryostructures are prepared via a cryo-process, where polymerization and internal crosslinking are primarily conducted at the sub-freezing temperature of the medium. Due to their unique and desirable properties, the potential of cryostructures has been examined in tissue engineering, cancer research, drug delivery, and sensors/biosensors. The macroporous cryostructures assist in trafficking cells, and the interconnected macropores provide a favorable environment for attaching cells during transplantation. These properties make such structures a great candidate for the preparation of three-dimensional (3D) systems suitable for the delivery of drugs, cell culture and tissue engineering, successive production of biomolecules, and purification of macromolecules such as proteins. Cryostructures have also been studied to improve the physical, chemical, mechanical, and release properties of controlled-release pharmaceutical dosage forms. In this review, we provide deep insights into the preparation and characterization of 3D cryostructures, discuss the factors affecting their properties, and elaborate on their contemporary biomedical and pharmaceutical applications. [ABSTRACT FROM AUTHOR]

The effect of acoustic low-intensity oscillations in a homogeneous tube and in a tube with a conical extension is experimentally investigated for the same resonator volumes. The resonator shape is shown to have an effect on the oscillation spectrum and intensity and the pressure wave shape at constant values of the resonance frequency and the piston displacement amplitude. An increase in the resonator Q-factor is observable, when the resonator has a conical extension. An accelerated aerosol sedimentation in tubes is revealed in the case of acoustic oscillation with the resonance frequency. In the presence of a conical extension the aerosol drop concentration is reduced by a factor of 1.2 more rapidly than in the case of a uniform tube and three times more rapidly as compared with natural sedimentation. The results obtained can be used for increasing the efficiency of acoustic methods of gas purification from the disperse phase. [ABSTRACT FROM AUTHOR]

Samples with porosities of 2–3 and 13% consisting of fine-grained quartz dispersed in a silver matrix were subjected to shock compression up to 28, 33, and 37 GPa in planar recovery ampoules. In samples with a porosity of 2–3%, after purification from silver, along with amorphized quartz, a crystalline high pressure silicon dioxide phase was detected by powder X-ray diffraction, which differs from stishovite and presumably has a monoclinic lattice. [ABSTRACT FROM AUTHOR]

Due to the complex porous structure, biochar usually has good adsorption capacity. Therefore, compared with direct combustion, conversion of peanut shell into biochar by pyrolysis is considered to be an environmentally friendly and efficient method for agricultural solid waste disposal. In this study, biochar production from microwave-assisted pyrolysis of peanut shell was detailed. The yields, surface topographies, and pore structures (pore size distribution and micropore volume) of biochars prepared at different pyrolysis temperatures (700, 750, 800, 850, 900, and 950 °C), microwave powers (350, 400, 450, 500, and 550 W), and residence times (0.5, 1.0, 1.5, 2.0, and 3.0 h) were elaborated. The results showed that the biochar yield gradually decreased and finally stabilized to around 30% while the specific surface area improved within the range of 4.68–67.29 m2/g when the pyrolysis temperature, microwave power, or residence time increased. Biochar with micropore was first obtained at pyrolysis temperature of 800 °C, microwave power of 500 W, and residence time of 2.0 h. This study further proposed quantitative relationships between the pore structures of peanut shell based biochars and experimental conditions (pyrolysis temperature, microwave power and residence time). The results presented in this study can provide guidance for the reuse of peanut shell and the production of porous biochar. The peanut shell biochar prepared in this study can be used in soil remediation, air purification, liquid purification and other fields for its porous structural characteristics. Highlights: • Peanut shell based biochar was produced using microwave-assisted pyrolysis. • Effects of pyrolysis operating parameters, such as pyrolysis temperature, microwave power, and residence time on the biochar yields, surface topographies, and pore structures were detailed. • The biochar yields were in the range of 30.04–43.38 wt. %. • The maximum specific surface area was 67.29 m2/g at 950 °C, 500 W, and 2.0 h. • Biochar with micropore appeared at pyrolysis temperature of 800 °C, microwave power of 500 W, and residence time of 2.0 h for the first time. • Quantitative relationships between the pore structures of peanut shell based biochars and experimental conditions were proposed. [ABSTRACT FROM AUTHOR]

Background This paper reports the preparation of a new family of spiked gold nanoparticles, spiked gold nanobipyramids (SNBPs). This protocol includes the process to synthesize gold nanobipyramids (NBPs) using combined seed-mediated and microwave-assisted method and procedure to form spikes on whole surface of gold nanobipyramid. We also evaluated the antibacterial activity against both methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA) in various concentrations of SNBPs and NBPs by well diffusion assay, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) determination. The effect of SNBPs on exposed bacteria was observed by scanning electron microscopy. Results The UV-Vis of purified NBPs exhibited two absorption bands located at 550 nm and 849 nm with yield of bipyramidal particles more than 90%. The average size of NBPs was 76.33 ± 10.11 nm in length and 26.57 ± 2.25 nm in diameter, respectively, while SNBPs were prolongated in length and achieved 182.37 ± 21.74 nm with multibranches protruding whole surface areas. In antibacterial evaluations, SNBPs and NBPs showed antibacterial activity with MIC of 6.25 μl/ml and 12.5 μl/ml, respectively, for MSSA while 12.5 μl/ml and 25 μl/ml, respectively, for MRSA. Besides, MBC values of SNBPs and NBPs were found to be 12.5 μl/ml and 25 μl/ml, respectively, against MSSA while 25 μl/ml and 50 μl/ml, respectively, against MRSA. Furthermore, scanning electron microscopy observation showed the mechanism that SNBPs damaged the outer membrane, released cytoplasm, and altered the normal morphology of MRSA and MSSA, leading to bacterial death. Conclusions This report suggests that these SNBPs are potential antibacterial agents that can be applied as antibacterial materials to inhibit the growth of human bacterial pathogen infections related to antibiotic-resistant bacteria. [ABSTRACT FROM AUTHOR]

The quest for efficient non-Pt/Pd catalysts has proved to be a formidable challenge for auto-exhaust purification. Herein, we present an approach to construct a robust catalyst by embedding single-atom Ru sites onto the surface of CeO2 through a gas bubbling-assisted membrane deposition method. The formed single-atom Ru sites, which occupy surface lattice sites of CeO2, can improve activation efficiency for NO and O2. Remarkably, the Ru1/CeO2 catalyst exhibits exceptional catalytic performance and stability during auto-exhaust carbon particle oxidation (soot), rivaling commercial Pt-based catalysts. The turnover frequency (0.218 h−1) is a nine-fold increase relative to the Ru nanoparticle catalyst. We further show that the strong interfacial charge transfer within the atomically dispersed Ru active site greatly enhances the rate-determining step of NO oxidation, resulting in a substantial reduction of the apparent activation energy during soot oxidation. The single-atom Ru catalyst represents a step toward reducing dependence on Pt/Pd-based catalysts. Here, the authors report a study exploring surface lattice-confined single-atom ruthenium sites which demonstrate remarkable stability and exceptional catalytic performance for auto-exhaust purification, making them a promising alternative to costly Pt/Pd-based catalysts. [ABSTRACT FROM AUTHOR]

Abstract—Layered double zinc and aluminum hydroxide modified with hexacyanoferrate(II) ions was synthesized for the first time by reverse deposition. The obtained samples were studied by X-ray phase analysis, scanning electron microscopy, and low-temperature nitrogen adsorption, and their sorption characteristics with respect to uranium U(VI) were studied. The sorption capacity for the modified material under static conditions, determined by the Langmuir equation, was = 156.70 ± 12.38 mg/g (at phase ratio V/m = 1000 mL/g, in a monocomponent solution of uranyl nitrate UO2(NO3)2 at a temperature T = 25°C and sorption time t = 24 h). Layered double zinc and aluminum hydroxide modified with hexacyanoferrate(II) ions is a promising sorbent for purification of liquid media from uranium U(VI) due to its high capacity and specific surface area, the possibility of effective use in a wide range of pH [4, 10], and low cost. [ABSTRACT FROM AUTHOR]

Technologies of membrane-based gas separation can be integrated into existing industrial processes for low-temperature helium recovery from natural gas at the stages of crude helium separation from the N2/He mixture and its purification. The effectiveness of these processes is most affected by the properties of the materials from which the membrane is made. Due to their unique properties, metal-organic framework are promising materials for use in gas separation. In the present work, both the Monte Carlo and equilibrium molecular dynamics methods were employed to examine the temperature dependence of membrane selectivity and nitrogen permeability for separation of an equimolar mixture of N2 and He by a HKUST-1-based membrane at a pressure drop of 0.1, 0.3, and 1 MPa. It was shown that the selection of optimal temperature conditions made it possible to obtain a significant increase in membrane selectivity and permeability for nitrogen compared to corresponding parameters at room temperature. [ABSTRACT FROM AUTHOR]

Nano-scale extracellular vesicles are lipid-bilayer delimited particles that are naturally secreted by all cells and have emerged as valuable biomarkers for a wide range of diseases. Efficient isolation of small extracellular vesicles while maintaining yield and purity is crucial to harvest their potential in diagnostic, prognostic, and therapeutic applications. Most conventional methods of isolation suffer from significant shortcomings, including low purity or yield, long duration, need for large sample volumes, specialized equipment, trained personnel, and high costs. To address some of these challenges, our group has reported a novel insulator-based dielectrophoretic device for rapid isolation of small extracellular vesicles from biofluids and cell culture media based on their size and dielectric properties. In this study, we report a comprehensive characterization of small extracellular vesicles isolated from cancer-patients' biofluids at a twofold enrichment using the device. The three-fold characterization that was performed using conventional flow cytometry, advanced imaging flow cytometry, and microRNA sequencing indicated high yield and purity of the isolated small extracellular vesicles. The device thus offers an efficient platform for rapid isolation while maintaining biomolecular integrity. [ABSTRACT FROM AUTHOR]

Electrocatalytic oxidation offers opportunities for sustainable environmental remediation, but it is often hampered by the slow mass transfer and short lives of electro-generated radicals. Here, we achieve a four times higher kinetic constant (18.9 min−1) for the oxidation of 4-chlorophenol on the reactive electrochemical membrane by reducing the pore size from 105 to 7 μm, with the predominate mechanism shifting from hydroxyl radical oxidation to direct electron transfer. More interestingly, such an enhancement effect is largely dependent on the molecular structure and its sensitivity to the direct electron transfer process. The spatial distributions of reactant and hydroxyl radicals are visualized via multiphysics simulation, revealing the compressed diffusion layer and restricted hydroxyl radical generation in the microchannels. This study demonstrates that both the reaction kinetics and the electron transfer pathway can be effectively regulated by the spatial confinement effect, which sheds light on the design of cost-effective electrochemical platforms for water purification and chemical synthesis. Understanding oxidation processes in reactive electrochemical membranes is essential for addressing environmental concerns. The authors highlight that microchannel pore size can profoundly impact not only the reaction kinetics but also the electron transfer pathways. [ABSTRACT FROM AUTHOR]

An optimized synthesis method for 6-[18F]fluoropiperonal (6-[18F]FP) via nucleophilic substitution of the nitro group in the precursor molecule (nitropiperonal, 6-NP) with [18F]fluoride in the presence of tetrabutylammonium tosylate has been proposed. Using this weakly basic phase transfer catalyst, the amount of initial 6-NP in the reaction was reduced from 4.0 to 0.2 mg with negligible amounts after subsequent treatment of the reaction mixture with a strong base (potassium methoxide). In turn, this made it possible to separate 6-[18F]FP and 6-NP with similar physicochemical properties by a simple and efficient solid-phase extraction technique on disposable cartridges. 6-[18F]FP was fabricated with 99% radiochemical purity and a radiochemical yield of 10%. The content of unreacted 6-NP did not exceed 1 µg/mL, which is comparable to the results of laborious semi-preparative HPLC purification. [ABSTRACT FROM AUTHOR]

Intrinsic 40 K radioactive backgrounds from impurities of natural K in liquid scintillation cocktails have previously been demonstrated to limit their use in ultra-sensitive applications. This work explores two methodologies in parallel for the reduction of 40 K backgrounds in the cocktails, and lays the groundwork for use in ultra-sensitive applications. In one method, alternative low-K liquid scintillation matrix constituents were identified and in the other, a simple purification method for single components and finished cocktails was developed. Both methods were verified via ICP-MS analysis. Liquid scintillation counting of selected purified cocktails demonstrated background reduction, improved stability, and enhanced performance. The best performing purified cocktail was also counted on a custom-built ultra-low background liquid scintillation counter, with results below the detector background. [ABSTRACT FROM AUTHOR]

The development of highly efficient separation technology for the purification of natural gas by removing ethane (C2H6) and propane (C3H8) is a crucial but challenging task to their efficient utilization in the chemical industry and social life. Here, we report three isomorphic ultra-microporous metal-organic frameworks (MOFs), M-pyz (M = Fe, Co, and Ni, and pyz = pyrazine) referred to as Fe-pyz, Co-pyz, and Ni-pyz, respectively, which possess high density of open metal sites and suitable pore structure. Compared with the benchmark materials reported, M-pyz not only has high adsorption capacities of C2H6 and C3H8 at low pressure (up to 51.6 and 63.7 cm3·cm−3), but also exhibits excellent C3H8/CH4 and C2H6/CH4 ideal adsorption solution theory (IAST) selectivities, 111 and 25, respectively. Theoretical calculations demonstrated that the materials' separation performance was driven by multiple intermolecular interactions (hydrogen bonding interactions and van der Waals effect) between gas molecules (C2H6 and C3H8) and the M-pyz binding sites. And, dynamic breakthrough experiments verified the superior reusability and practical separation feasibility for the ternary CH4/C2H6/C3H8 mixtures. Furthermore, M-pyz can be synthesized rapidly and on a large scale at room temperature. This work presents a series of promising MOFs adsorbents to efficiently purify natural gas and promotes the industrial development process of MOFs materials. [ABSTRACT FROM AUTHOR]

The addition of rare earth elements has a strong purification ability because it reduces the number of inclusions with size greater than 10 µm in rare earth magnesium alloys. However, the residual small inclusions are difficult to separate due to Brownian motion, which seriously reduces the mechanical property of magnesium alloys. In this study, using the conductivity difference between the inclusion and the melt, the electric driving force for purifying rare earth magnesium alloy, which is not affected by the size of the inclusion, is introduced. Compared with the static precipitation method, the pulsed electric current purification method can remove up to 63 pct of the inclusions in 10 minutes. The electromagnetic purification technology has the advantages of fast, efficient and environmental protection, which provides a new idea for further optimizing the property of rare earth magnesium alloys. [ABSTRACT FROM AUTHOR]

The versatile manipulation of cross-scale droplets is essential in many fields. Magnetic excitation is widely used for droplet manipulation due to its distinguishing merits. However, facile magnetic actuation strategies are still lacked to realize versatile multiscale droplet manipulation. Here, a type of magnetically actuated Janus origami robot is readily fabricated for versatile cross-scale droplet manipulation including three-dimensional transport, merging, splitting, dispensing and release of daughter droplets, stirring and remote heating. The robot allows untethered droplet manipulation from ~3.2 nL to ~51.14 μL. It enables splitting of droplet, precise dispensing (minimum of ~3.2 nL) and release (minimum of ~30.2 nL) of daughter droplets. The combination of magnetically controlled rotation and photothermal properties further endows the robot with the ability to stir and heat droplets remotely. Finally, the application of the robot in polymerase chain reaction (PCR) is explored. The extraction and purification of nucleic acids can be successfully achieved. Current droplet manipulation techniques have limitations such as applying to a large scale of volume or of on-demand droplet release. Here using a magnetic actuated Janus origami robot, Jiang et al. present a strategy to achieve omni-manipulation of micro and nanoliter droplets. [ABSTRACT FROM AUTHOR]

Silicon is identified as the most prospective anodes candidate material for lithium-ion batteries (LIBs). However, its commercialization is restricted by the large volume variation and high-cost. In this study, the silicon powders from the kerf slurry wastes are used as raw materials for the preparation of silicon/carbon anodes. An effective pretreatment process that combines the sand milling and a chemical cleaning method is utilized to prepare the purified silicon powders. Then, a facile one-step hydrothermal method is used to prepare the purified silicon/carbon composites. The results demonstrate that the chemical purification can effectively remove the organic contaminants and metal impurities on the surface of raw silicon powders. It also renders hydrophilic surfaces for the silicon powders, which improves the bonding of carbon layer and results in the improvement of the electrical performance correspondingly. The as-prepared purified silicon/carbon anode shows a high specific discharge capacity of 2099 mAh g−1 in the first cycle at the current density of 0.2 A g−1. The capacity still maintains a value of 1010 mAh g−1 after 148 cycles at the current density of 0.5 A g−1. This work not only provides a reasonable and facile solution for recycling silicon wastes from the kerf slurry but also provides a strategy for the preparation of advanced anodes for high-performance lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Carbon, tried and tested adsorbent of the industrial age still dominates the process industries for purification and benefaction of mass-based separation. In this manuscript, the feasibility of utilizing the steel industries by-product coal tar sludge (CTS) for carbon products was studied. CTS, a hazardous waste, due to its carcinogenicity was largely un-regarded as carbon precursor due to the presence of polyaromatic hydrocarbons. The sludge is pre-processed with organic solvent followed by membrane separation aided by vacuum to extract the pristine carbon which is then treated thermally with an oxidizing agent in an inert atmosphere. The yielded activated carbon (AC) is surface characterized for the structural evaluation of the pore networks within. The surface area of the synthesized ACs lies within the range between 1600 and 1800 m2/gm and the values are compared with the commercially available ACs and ACs synthesized from other carbon precursors. Further, the utilization of the synthesized ACs towards dye removal has also been explored. [ABSTRACT FROM AUTHOR]

Due to the presence of impurity ions, the current efficiency of zinc electrowinning is reduced, and the quality of zinc products is affected. Therefore, before zinc production, impurity ions must be removed from the electrolyte. Zinc powder cementation is the most commonly used purification method, which has problems with agglomeration and wrapping. These problems cause fluctuations in the purification effect and poor adaptability. In this article, ultrasound was introduced into the zinc powder cementation purification process, strengthening it, so that a deeper purification effect was obtained. Electrochemical experiments were used to reveal the electrochemical behavioral process of ultrasonic-enhanced purification. The kinetics of the was explored, and it was found that the activation energy under ultrasound conditions was lower, which is conducive to the occurrence of deep purification. Through XRF, XRD, SEM–EDS, XPS, and other characterization methods, the behavior of the ultrasound purification process was analyzed. Ultrasonic-enhanced zinc powder cementation purification is indeed a method that can achieve deep purification, and can meet the strict purification requirements due to increasingly complex mineral raw materials and electrolysis processes. [ABSTRACT FROM AUTHOR]

Indoor air pollution directly threatens human health, with prolonged exposure to pollutants leading to respiratory problems, immune system issues, and even cancer. Thus, implementing advanced air purification technologies is crucial to effectively mitigate indoor pollutants. The current common air purifiers have low removal efficiency for pollutants, a high cost of replacing adsorption materials, and a single function. Therefore, a novel air purification system that provides high-efficiency and rapid air purification and enhances the reusability of adsorption materials is in demand. This study evaluated the purification effect of the New Air Purification System under the internal circulation mode using computational fluid dynamics. The results showed that (1) the air exchange rates of the New Air Purification System were adjusted to 42.6, 85.2, and 127.8 h−1, respectively, when the release rates of 222Rn were 2.268, 4.536, 6.804, and 9.072 Bqm−2h−1. The indoor 222Rn concentration was reduced to < 21% of the background 222Rn concentration. (2) The initial concentration of indoor formaldehyde was 0.1 mg/m3 and increased to 0.0204, 0.0181, and 0.0174 mg/m3, respectively. These values were less than the World Health Organization's recommended limits. This study provides a solid foundation for designing and optimising the New Air Purification System, provides technical guidance for the next step in its design, and would substantially help in improving indoor air quality and living conditions. [ABSTRACT FROM AUTHOR]

Nickel-zinc ferrites, which have pronounced ferrimagnetic and semiconductor properties, can be used as promising magnetically controlled photocatalysts for the purification of aqueous media from organic pollutants. The value of the specific surface area largely affects the photocatalytic properties of the material; therefore, the possibility of its control and variation at the stage of synthesis is of great scientific and technical interest. In this study, nanocrystalline ferrite of the Zn0.5Ni0.5Fe2O4 composition is obtained under conditions of solution combustion using various types of organic fuel as the main factor affecting the formation of the specific surface area, and subsequent heat treatment in air at a temperature of 500°C for 2 h. The crystal structure, chemical composition, and morphology of Zn0.5Ni0.5Fe2O4 are studied by methods of X‑ray phase analysis, X-ray spectral microanalysis, and scanning electron microscopy. The values of the specific surface area of the synthesized nanopowders are calculated based on the method of liquid-phase adsorption from a Methylene Blue solution and the low-temperature adsorption-desorption of nitrogen. The results of the X‑ray phase analysis show that a single-phase nanocrystalline product with a spinel structure is formed, where the average crystallite size varies within 11–23 nm and is inversely related to the value of the specific surface area, respectively, after the reaction with succinic acid (39.1 m2/g) and with glycine (20.2 m2/g). It is established that the choice of the fuel largely affects the formation of nanocrystals and the specific surface area of the samples, and the approach used makes it possible to control its values. [ABSTRACT FROM AUTHOR]

GaSb-based thin films are expected to be applicable to biomedical and environmental devices requiring efficient operation in the near-infrared region. In this study, the effects of dilute Bi doping on the structural properties and chemical stability of GaSb thin films were examined. GaSb and GaSb1−xBix (x = 0.011, 0.013, or 0.032) thin films were grown at 320 °C on quartz substrates and PI films by multi-cathode RF magnetron sputtering. The crystallinity of the GaSb/quartz was superior to that of the GaSb/PI. Bi doping improved the crystallinity of the GaSb thin films with the exception of GaSb0.968Bi0.032/quartz, for which the crystallinity deteriorated owing to abnormal growth due to Bi cluster formation. In addition, the crystallinity of GaSb1−xBix/PI was drastically improved at x = 0.032. The increases in grain size and hole concentration caused by Bi doping indicate that Bi assists the growth of GaSb thin films. Furthermore, elution tests revealed that Bi doping suppresses the elution of highly toxic Sb under simulated physiological conditions. These findings have the possibility to hasten the development of flexible GaSb-based biomedical and environmental devices with improved safety and lower environmental burden. [ABSTRACT FROM AUTHOR]

Carbon dots (CDs) are renowned for their unique properties with numerous and growing applications in various fields and industries. Although several methods are available to prepare CDs, low conversion yield, tedious purification processes and poor color purity remain major drawbacks. To address these issues, a cooling stage for full protonation prior to direct heating has been developed. This innovative method produces high-color purity solid-state CDs with a conversion yield of up to 99.5% in less than 6 min. The CDs synthesized by this method exhibited a highly crystalline structure, as confirmed by HRTEM, Raman and XRD analyses. In addition, the emission profile of the CDs could be effectively tuned by reducing the amount of concentrated sulfuric acid, resulting in a shift of the emission from 484 to 650 nm. The high-color purity of the CDs is postulated to be due to the solvent cage effect. Overall, this study presents a simple, efficient and rapid method for the preparation of high-quality CDs with excellent color purity and crystallinity. [ABSTRACT FROM AUTHOR]

The rise of residues derived from hydrometallurgical processes of zinc production has made this industry face numerous challenges. Residues contain elements whose reclamation is of high significance due to the economic improvement of the whole process and the removal of environmental consequences. The previous study examined the selective extraction of Zn and As from hot purification filter cakes of the zinc process and found that the dominant species in arsenic-bearing solution was AsO43−. With a Zn2(AsO4) (OH) composition containing As 23.1 wt pct, As was precipitated with an 95 pct efficiency by adding zinc sulfate under the following conditions: Molar ratio Zn/As = 1, pH 6.5, time = 4 hours, temperature = 80 °C, and stirring velocity = 500 rpm. The zinc arsenate hydroxide was successfully used as an activator of the zinc powder in the cobalt cementation process. The examination of the precipitate revealed that As increased the anodic and cathodic reactions potential difference. Thus, thermodynamic driving force of the reaction increased and cementation improved by forming intermediate compounds, like CoAs, with higher stability and more positive reduction potential. [ABSTRACT FROM AUTHOR]

The use of affinity peptide displaying on the surface of M13 phage has emerged as a promising alternative to antibody-based detection methods owing to its diverse structure, mass production, easy purification, and genetic manipulation, as well as excellent stability. In this study, we aimed to identify highly selective and sensitive peptide-displayed M13 phage for thrombin detection using phage display technology. Phage display was conducted using two different phage libraries (linear and cyclic forms of peptides), which displayed affinity peptides capable of binding specifically to thrombin. Throughout the biopanning process, two phage clones that displayed both peptides (WGQSFWGYQHYS and CWKLLTPWC) were selected. After the characterization of their binding abilities using enzyme-linked immunosorbent assay, whole phage particles were covalently attached to a gold electrode using MUA-EDC/NHS coupling chemistry. The thrombin detection mechanism was based on signal inhibition, and the results revealed that the specific interactions between the phage-tethered gold electrode and thrombin are critical factors affecting the decrease in the peak current of the sensor. In addition, under optimal conditions, the fabricated phage-based electrochemical sensors were capable of highly sensitive and specific thrombin detection with a good binding affinity (Kd = 17 nM for 12mer 3–17 and 14 nM for C7C 3–5) and limit of detection (4 nM for 12mer 3–17 and 10 nM for C7C 3–5), resulting in good reproducibility, even in artificial human plasma samples. This study may provide an alternative and more efficient method of detecting thrombin with desirable sensitivity, selectivity, and feasibility for the diagnosis and prognosis of coagulation disorder-related diseases. [ABSTRACT FROM AUTHOR]

The tailings and fluorine-containing sludge were produced during the physical and chemical purification of natural crystalline graphite, containing heavy metals in different occurrence forms. To evaluate the threat of different heavy metals to the environment, this work uses the modified sequential extraction method (BCR) to study the presence of heavy metals in two solid wastes and their dissolution characteristics in different environments. The results show that the pollution risk of heavy metals in graphite tailings to the environment is ranked as Mn > Cr > Ni > Zn, and the pollution risk of Mn in fluorine-containing sludge is higher than that of Cr. This is because the Mn in the two solid wastes mainly exists in the form of weak acid extraction. The leaching number of heavy metals in the two solid wastes is directly proportional to the soaking time and soaking temperature, and inversely proportional to the pH value and the solid-to-liquid ratio. The number of heavy metals dissolved in solid waste landfills is significantly higher than that of acid rain and surface water environments. Based on the above results and the distribution of graphite solid waste, solidification agent was suggested to prevent heavy metal dissolution and reduce environmental risks. [ABSTRACT FROM AUTHOR]

Phosphomevalonate kinase (PMK) catalyzes the phosphorylation of phosphomevalonate via the mevalonate pathway to form diphosphomevalonate, an essential isoprenoid precursor. Fungal PMK, also known as Erg8p, is an essential enzyme with no orthologs found in animals, making it an attractive target for antifungal drug development. As Erg8p has only 16–17% sequence homology with previously reported PMKs structures, its reaction mechanism remains unclear due to the lack of structural information. Here, we present preliminary crystallographic studies of Saccharomyces cerevisiae Erg8p (SceErg8p). We expressed SceErg8p in Escherichia coli, purified, and obtained the protein crystals using the sitting-drop vapor-diffusion method. The best crystal exhibited a diffraction pattern with a resolution of 1.42 Å and belonged to the orthorhombic space group P21212, with unit cell parameters a = 87.2 Å, b = 110.0 Å, c = 55.7 Å. The structure of SceErg8p was solved using the AlphaFold2-predicted model. Structural refinement and characterization are currently in progress. [ABSTRACT FROM AUTHOR]

Cancer continues to be a leading cause of global death despite decades of research on its prevention and cure. In the mid-twentieth century, anecdotal evidence began to accumulate that certain chemicals might be cancer-causing and this was followed up with animal model studies. These suspected substances were termed carcinogens and among those investigated were N-nitrosamines (or simply nitrosamines). Interest in nitrosamines is now more than a century old and research continues to explore their biology. Since the 1950's, steady progress has been made in perfecting chemistry techniques to label interesting compounds with 14C or tritium. However, there have been relatively few reports concerning the synthesis of nitrosamines with these radioisotopes, providing substances which could be valuable in advancing key nitrosamine biology research. Most of the previous literature examples of 14C or tritium labelled nitrosamines related to very specific compounds lacking wider interest and relevance. Also, the resulting products were usually of low specific activity. This paper outlines strategies to accomplish the labelling of more broadly relevant nitrosamines with 14C or tritium at high specific activity. Particularly, a library of 14C labelled nitrosamines with diverse structures was created. Exemplary experimental details are provided for the synthesis of [14C] N-nitrosodiethanolamine as well as the repurification of [ethyl-1-14C] N-nitroso-N-ethylurea. The storage and general stability of 14C nitrosamines is also discussed. Finally, as an example of a typical strategy to prepare a nitrosamine labelled with tritium, the synthesis of [3, 4-3H] N-nitrosopyrrolidine is described in detail. [ABSTRACT FROM AUTHOR]

In this contribution, we report a general method for the synthesis of 3D graphene/Fe3O4 NPs aerogels (GA-Fe3O4-EDA) with high porosity and Fe3O4 nanoparticles (NPs) are stably loaded on a graphene substrate, representing several-fold improvements compared to the chemical method in the literature. Graphene/Fe3O4 NPs aerogels with a continuous network are fabricated via γ-ray irradiation method induced reduction of Graphene oxide/Fe3O4 in EDA/H2O mixed solution. There is no doubt that they possess stronger magnetism with the increase of Fe3O4 content. According to the above characteristics of GA-Fe3O4-EDA, the composites can be used for aqueous-organic phase separation and adsorption of magnetic substances. This work paves the way for aqueous phase purification and magnetic material adsorption. [ABSTRACT FROM AUTHOR]

Fibroblast growth factor 21 (FGF21) has pharmaceutical potential against obesity-related metabolic disorders, including non-alcoholic fatty liver disease. Since thermal stability is a desirable factor for therapeutic proteins, we investigated the thermal behavior of human FGF21. FGF21 remained soluble after heating; thus, we examined its temperature-induced structural changes using circular dichroism (CD). FGF21 showed inter-convertible temperature-specific CD spectra. The CD spectrum at 100 °C returned to that at 20 °C when the heated FGF21 solution was cooled. Through loop swapping, the connecting loop between β10 and β12 in FGF21 was revealed to be associated with the unique thermal behavior of FGF21. According to surface plasmon resonance (SPR) experiments, in vitro cell-based assays, and model high-fat diet (HFD)-induced obesity studies, heated FGF21 maintained biological activities that were comparable to those of non-heated and commercial FGF21s. Based on sequence comparison and structural analysis, five point-mutations were introduced into FGF21. Compared with the wild type, the heated FGF21 variant displayed improved therapeutic potential in terms of body weight loss, the levels of hepatic triglycerides and lipids, and the degree of vacuolization of liver in HFD-fed mice. [ABSTRACT FROM AUTHOR]

Problems of the development of liquid organic scintillators are discussed from the point of view of the content of radioactive impurities in detectors for recording rare events. The results of investigations of various methods for purifying individual scintillator components from U, Th, and K are presented. It is shown the PPO (2,5-Diphenyloxazole) scintillation additive, where the concentration of potassium may range between 0.8 and 7.1 g/g, is the main source of contamination with potassium ( K). In linear alkylbenzene (LAB, Russia), which is viewed as a promising dissolver for creating a large-scale neutrino detector, the measured concentration of potassium is about 10 g/g. [ABSTRACT FROM AUTHOR]

Although methods for the chemical separation of samarium from a rock matrix are well established, chemical separation of samarium from non-natural isotopic impurities for the purpose of 146Sm half-life measurement requires modifications to these procedures, as well as additional checks for effective separation. This work describes the chemical purification procedures associated with the 146Sm source and the results from gamma spectroscopy. The purification procedure allowed for the quantitative determination of the number of 146Sm atoms using a modified isotope dilution technique. Alpha-decay counting of the sample will be applied in the future to determine the half-life of 146Sm. [ABSTRACT FROM AUTHOR]

This paper examines key features of the preparation of high-purity Ga from electronic and electrical engineering industry waste. The decrease in the melting point of impurity-containing Ga is assessed thermodynamically in the ideal solution approximation. It is proposed that the purity of gallium in the final crystallization purification step can be monitored via precision measurement of the temperature of the melt with a pyrometer. [ABSTRACT FROM AUTHOR]

Gallium isotope is a potential geochemical tool for understanding planetary processes, environmental pollution, and ore deposit formation. The reported Ga isotope compositions (δ71GaNIST994 values) of some international geological standards, such as BCR-2 and BHVO-2 basalts, exhibit inconsistencies between different laboratories. During mass spectrometry analysis, we found that δ71GaNIST994 values of geological standards with or without the correction of the interference of 138Ba2+ (mass/charge ratio = 69) on 69Ga show significant isotope offsets, and thus efficient separation of Ba and correcting the interference of 138Ba2+ are both crucial to obtain accurate δ71Ga values. By comparing δ71GaNIST994 values (relative to NIST SRM 994 Ga) of the same geostandards from different laboratories, we suggest that the isotopic heterogeneity from NIST SRM 994 Ga is one of the key reasons for the inconsistencies in δ71GaNIST994 values of BCR-2 and BHVO-2. To facilitate inter-laboratory comparisons, we measured the Ga isotopic compositions of 11 geological reference materials (including Pb-Zn ore, bauxite, igneous rocks, and loess) and two Ga solution standards (NIST SRM 3119a and Alfa Aesar). The δ71GaNIST994 and δ71GaIPGP values of these reference materials vary from 1.12 ‰ to 2.63 ‰ and − 0.13 ‰ to 1.38 ‰, respectively, and can be used to evaluate the precision and accuracy of Ga isotope data from different laboratories. [ABSTRACT FROM AUTHOR]

Prof. Dr. Panne's ambition as an editor for ABC is to demonstrate that good analytical chemistry is at the core of many fundamental and applied scientific problems and innovations and will contribute to solving the grand challenges of our times. We continue to have a dynamic team of editors at ABC. [Extracted from the article]

This paper describes a detailed study aimed at developing technological principles of the preparation of 99.99995%-pure Cd, Zn, and Te by crystallization purification methods. We have analyzed the thermophysical properties of Cd, Zn, Te, and structural materials of the equipment involved; substantiated the choice of graphite as a crucible material; and determined its engineering features. We have studied impurity distributions in Cd, Zn, and Te in crystallization processes and determined effective performance parameters of the materials refining process in horizontal directional solidification and zone melting steps. The results have allowed us to obtain 99.99995 to 99.99999%-pure Cd, Zn, and Te in terms of 30 major impurities, with a maximum product yield of up to 85%. [ABSTRACT FROM AUTHOR]

A technique of induction smelting followed by directional solidification to recover and purify silicon from diamond wire saw waste silicon powder without the use of additives is presented herein. The silicon reaction and the effect of smelting time on the removal of impurities from silicon powder waste were investigated using a simple induction smelting and directional solidification method. Through the detection of byproducts and condensed volatiles, it is inferred that Si is volatilized and removed as silicon monoxide during smelting. Byproducts containing Si, SiC, or SiO2 phases can be generated by the reaction between silicon monoxide and graphite crucible after volatilization. Because the crucible is sealed with byproducts, the flow of volatile materials in the crucible disrupts the mass transfer balance in the silicon melt. The amount of residual impurities in silicon ingot trends downwards with the extension of smelting time. A 99 pct oxygen removal rate was obtained after the material was smelted three times. The silicon ingot achieved the lowest impurity content after smelting for 4 hours. The silicon powder waste can be potentially used as a metallurgical-grade silicon product after a simple one-step induction smelting process. Further purification of the silicon ingot by directional solidification can reduce residual impurities to 74 ppmw. [ABSTRACT FROM AUTHOR]

Selective isolation of soil Actinobacteria was undertaken to isolate a new class of antibiotics and bioactive molecules. A Streptomyces sp. PSAA01 (= MTCC 13,157), isolated from soil of Eastern Himalaya foothill was cultivated on a large scale for the production of the antimicrobial SM02. It has been found that the maximum amount of SM02 produced while PSAA01 was grown in ISP-2 medium (pH 7.0) for 7 days at 30 °C in shaking (180 rpm) condition. A significant zone of inhibition against Staphylococcus aureus MTCC 96 has been found with the crude cell-free culture media (50 µL) of 7 days grown PSAA01. After the purification and chemical structural characterization, we found that SM02 is a new antimicrobial having 746 dalton molecular weight. The compound SM02 contains pyrimidine moiety in it and is produced by a species of Streptomyces and thus we have named this antibiotic pyrimidomycin. The antimicrobial spectrum of pyrimidomycin has been found to be restricted in Gram-positive organisms with a MIC of 12 µg/mL. SM02 was found active against Mycobacterium sp. and also multi-drug resistant Gram-positive bacteria with similar potency and found to disrupt the bacterial cell wall. Pyrimidomycin also showed significant impairment in the biofilm formation by S. aureus. Furthermore, pyrimidomycin showed synergy with the most used antibiotic like ampicillin, vancomycin and chloramphenicol. Pyrimidomycin did not have cytotoxicity towards human cell lines indicating its limited activity within bacteria. [ABSTRACT FROM AUTHOR]