Including X-ray Diffraction Analysis Research Articles

Amino-functionalized graphene quantum dots as a photoluminescent probe for in vitro cellular imaging of human lung cancer cell lines

Graphene-based fluorescent materials, particularly graphene quantum dots (GQDs), have emerged as a new class of biomedical agents. In the present study, functionalised GQDs have a better chance of being employed in a broader range of bioapplications because of their proven low toxicity, outstanding biocompatibility, and enhanced fluorescence properties. For this purpose, amino-functionalised GQDs (AF-GQDs) were synthesised via hydrothermal treatment by treating graphene oxide in ammonia with heat and water. The as-prepared AF-GQDs samples were characterised using a variety of techniques, including x-ray diffraction analysis (XRD), high-resolution transmission electron microscopy (HR-TEM), and photoluminescence (PL) spectroscopy. The results show that AF-GQDs are merely hexagonal, with an average size of about 8 nm. Also, AF-GQDs are highly soluble in water and display excellent luminescence behaviour. After 48 h of incubation, the MTT results showed that more than 63% of the cells were still alive, even at high concentrations (500 g ml−1) of AF-GQDs. In addition, the AO/EB staining results also showed that the AF-GQDs had the most robust green fluorescence (viable cells). This makes them a promising agent for biomedical imaging because they have good optical properties, are readily soluble in water, are biocompatible, and are not toxic.

Valorisation of microalga Chlorella sp. into furans in the presence of Nb2O5 catalysts

Despite the interest in niobia-based catalysts and the importance of biomass valorisation, studies on these catalysts typically utilize model substrates like simple sugars. In this study, a series of niobium oxide-based catalysts was prepared for the application in aqueous phase catalytic conversion of sugars extracted from Chlorella sp. microalga into value-added furans. The solid catalysts were firstly characterized by various techniques including X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Raman and X-ray photoelectron (XPS) spectroscopy as well as low-temperature N2 physisorption. Moreover, the acidity of the catalysts was assessed by using the temperature-programmed NH3 desorption (NH3-TPD), by titration of water suspended catalyst with NaOH solution, and by P-bearing molecular probes loaded catalysts through 31P and 1H solid-state nuclear magnetic resonance (NMR) techniques. Herein, we focused on the catalytic transformation of Chlorella sp. and glucose solution as model molecule into furans. The best Nb2O5 catalysts for valorizing Chlorella sp. into furans exhibited a larger number of Brønsted acid sites, achieving conversion yields to 5-HMF and furfural of ca. 20–22 % with respect to the extracted sugars from algae. The results showed a discernible dependence of the conversion yields to 5-HMF and furfural on catalyst acidity, specific surface area, and the presence of the Brønsted acid sites. Conversely, when using the glucose solution as substrate is concerning, the highest yield to 5-HMF was reached by using a catalyst that showed also the presence of Lewis acid sites. A systematic investigation of the structure–activity relationships in niobium oxide application for aqueous phase dehydration using real biomass substrates to obtain furanic derivatives has not been documented thus far. Therefore, the current research is significant as it demonstrates the feasibility of transforming the carbohydrate content in microalgal biomass into furans by identifying the best catalyst to use.

K2CO3-Modified Smectites as Basic Catalysts for Glycerol Transcarbonation to Glycerol Carbonate.

A novel and cost-effective heterogeneous catalyst for glycerol carbonate production through transesterification was developed by impregnating smectite clay with K2CO3. Comprehensive structural and chemical analyses, including X-ray diffraction Analysis (XRD), Scanning Electron Microscopy (SEM)-Electron Dispersion Spectroscopy (EDS), Fourier Transform Infrared Spectroscopy (FTIR), and Brunauer-Emmett-Teller (BET) surface area analysis measurements, were employed to characterize the catalysts. Among the various catalysts prepared, the one impregnated with 40 wt% K2CO3 on smectite and calcined at 550 °C exhibited the highest catalytic activity, primarily due to its superior basicity. To enhance the efficiency of the transesterification process, several reaction parameters were optimized, including the molar ratio between propylene carbonate and glycerol reactor loading of the catalyst and reaction temperature. The highest glycerol carbonate conversion rate, approximately 77.13% ± 1.2%, was achieved using the best catalyst under the following optimal conditions: 2 wt% reactor loading, 110 °C reaction temperature, 2:1 propylene carbonate to glycerol molar ratio, and 6h reaction duration. Furthermore, both the raw clay and the best calcined K2CO3-impregnated catalysts demonstrated remarkable stability, maintaining their high activity for up to four consecutive reaction cycles. Finally, a kinetic analysis was performed using kinetic data from several runs employing raw clay and the most active K2CO3-modified clay at different temperatures, observing that a simple reversible second-order potential kinetic model of the quasi-homogeneous type fits perfectly to such data in diverse temperature ranges.

Sustainable Synthesis of Green Cu2O Nanoparticles using Avocado Peel Extract as Biowaste Source

In recent years, there has been a significant shift towards the production of advanced nanomaterials using sustainable methods, reflecting a heightened focus on reducing environmental impact and optimizing resource utilization. This growing interest stems from the necessity to address environmental concerns and embrace eco-friendly practices in material synthesis. The primary objective of this study is to explore the eco-friendly synthesis of novel metal oxide nanoparticles (NPs) by utilizing bio-waste as a sustainable precursor. The central theme revolves around employing ultrasound-assisted techniques for Cu2O NP synthesis, with a specific emphasis on utilizing avocado peel waste as an effective phytochemical compound for capping. Through systematic process optimization, we conducted a comprehensive assessment of the resulting NPs, delving into their chemical, thermal, and surface properties. Advanced characterization techniques, including X-ray Diffraction analysis (XRD), Transmission Electron Microscopy (TEM), Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), and Fourier-transform Infrared Spectroscopy (FT-IR), were employed to gain profound insights into the attributes of the synthesized NPs. Our experimental results conclusively demonstrate the successful synthesis of spherical Cu2O NPs, each with a diameter of 25 ± 2 nm. This was achieved by utilizing avocado peel waste (APW) and ultrasound-assisted cavitation at room temperature. The study significantly contributes to our understanding of the potential applications of green synthesis methods, paving the way for environmentally friendly and cost-effective Cu2O NPs.

Origin of quartz and its implications for different phase fluids in lacustrine shales from the Qingshankou Formation, southern Songliao Basin, China

Quartz, an important mineral that occurs in lacustrine shales, can be of different types and origins. Yet, only few studies have investigated how quartz from different sources contribute to phase fluids, such as adsorbed and free fluids present within shale matrix pores. This study integrates various experimental techniques, including X-ray diffraction analysis, geochemical analysis, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and high-frequency two-dimensional nuclear magnetic resonance analysis to quantitatively characterize the different phase fluids associated with various types of quartz occurring in the Qingshankou Formation shale. The characterization results indicated four distinct quartz types: silt-sized quartz, microcrystalline quartz linked with clay minerals, organism-skeletal quartz, and quartz aggregates comprising multiple crystals. The Fe–Al–Mn ternary diagram and SiO2 versus Zr scatter plot indicate that terrigenous clastic material is the primary source of SiO2 in shale quartz. Smectite-to-illite transition plays a pivotal role in authigenic quartz formation. Based on quartz concentration data obtained using major element analysis, we estimated the ranges of terrigenous clastic quartz, diagenetic quartz formed by the smectite-to-illite transition, and biogenic quartz concentrations to be from 55.49% to 92.03% (average 84.70%), 6.67%–20.30% (average 13.12%), and 0%–24.21% (average 2.17%), respectively. The solid organic matter in shale is affected by both terrigenous detrital quartz and authigenic quartz transformed from the clay in the basin. Authigenic quartz, formed by the smectite-to-illite transition, considerably enhances the development of solid organic matter in the Qingshankou Formation. By contrast, an abundance of terrigenous detrital quartz can lead to a dilution of the solid organic matter. Thus, this study provides the first direct evidence that along with a high value of bio-organic matter yield factor, the source of quartz plays a significant role in controlling organic matter abundance.

Growth and Characterization of p-Type and n-Type Sb2Se3 for Use in Thin-Film Photovoltaic Solar Cell Devices

In this study, a two-electrode electrodeposition technique was employed to grow thin films of antimony selenide (Sb2Se3) on glass/fluorine-doped tin oxide (FTO) substrates. The highest quality thin films were consistently obtained within the range of 1600 mV to 1950 mV. Subsequent electrodeposition experiments were conducted at discrete voltages to produce various layers of thin films. Photoelectrochemical cell (PEC) measurements were performed to characterize the semiconductor material layers, leading to the identification of both p-Type and n-Type conductivity types. Optical absorption spectroscopic analysis revealed energy bandgap values ranging from 1.10 eV to 1.90 eV for AD-deposited Sb2Se3 samples and 1.08 eV to 1.68 eV for heat-treated Sb2Se3 samples, confirming the semiconducting nature of the Sb2Se3 material. Additionally, other characterization techniques, including X-ray diffraction analysis, reveal that the AD-deposited layers are almost amorphous, and heat treatment shows that the material is within the orthorhombic crystalline system. Heat-treated layers grown at ~1740 mV showed highly crystalline material with a bandgap nearing the bulk bandgap of Sb2Se3. Raman spectroscopy identified vibrational modes specific to the Sb2Se3 phase, further confirming its crystallinity. To explore the thin-film morphology, Scanning Electron Microscopy (SEM) was employed, revealing uniformly deposited material composed of grains of varying sizes at different voltages. Energy Dispersive X-ray analysis (EDX) confirmed the presence of antimony and selenium in the material layers.

A comparative study between the use of nanoparticles of magnesium oxide and zinc oxide as coating for polymeric surfaces a flame retardant and corrosion resistance

This study deals with the preparation of magnesium oxide nanoparticles (MgO NPs) and zinc oxide nanoparticles (ZnO NPs) by the co-precipitation method. The prepared metal oxide was characterized by X-ray diffraction analysis, scanning electron microscope, transmission electron microscope, element analysis examination, and UV–Visible and IR spectroscopies. The results of these tests showed the nano size, uniform distribution, and purity of the prepared powders. They proved the appearance of cubic and hexagonal phases of MgO NPs and ZnO NPs, respectively. These NPs have 4.2 eV and 3.12 eV energy gap values, respectively. The preparation of a coating consisting of MgO NPs and ZnO NPs involves combining them separately with epoxy in ratios of 3 %, 6 %, and 9 %. This mixture is then used to cover the polymeric surface using the immersion method. The nanocomposites have been examined before and after applying a coating via different techniques including X-ray diffraction analysis, infrared spectrum, atomic force microscopy, combustion test, thermal gravimetric decomposition, thermal conductivity, corrosion rate, hardness, and tensile strength. According to the results, it is found that the immersion coating method gives good dispersion of the NPs within the polymer matrix. Moreover. When comparing the use of MgO NPs and ZnO NPs, it is found that the use MgO NPs has given better results for flame retardancy, thermal gravimetric analysis and reduction of corrosion compared to the use of ZnO NPs, which has given better mechanical properties and thermal conductivity than MgO.

Oxidation-driven auto-conversion of Ti3C2Tx MXene to TiO2 nanoparticles for photocatalytic applications

Ti3C2Tx MXene, a recently discovered 2D material, possesses unique properties; however, its lack of stability against oxidation poses a significant challenge to its application. This study leverages the auto-oxidation of Ti3C2Tx MXene to synthesize TiO2 (termed as m-TiO2) nanoparticles, addressing MXene susceptibility to oxidation as an advantage. This study enhances the utilization of remaining MXenes, minimizing waste and maximizing resource efficiency. The Ti3C2Tx MXene was allowed to oxidize in deionized water under ambient conditions for an extended period of one year, resulting in a transformation from dark black Ti3C2Tx MXene to milky white m-TiO2, indicating Ti3C2Tx MXene degradation. The size of the Ti3C2Tx MXene nanoflakes under investigation is ∼500 nm, while the resulting high surface area porous m-TiO2 nanoparticles have an average size of ∼40 nm. The transformation of Ti3C2Tx MXene into m-TiO2 nanoparticles was assessed through a combination of analytical techniques, including X-ray diffraction analysis (XRD), UV-Vis absorbance analysis, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) analysis. The specific surface areas (SSA) of 7.2 m2/g and 39.1 m2/g for Ti3C2Tx MXene and m-TiO2 nanoparticles, respectively, signify the presence of micro/nanopores in the latter. The m-TiO2 nanoparticles exhibit promising photocatalytic properties, efficiently degrading methylene blue (MB) dye under UV light.

Easy access to strongly fluorescent higher homologues of BODIPY.

We present the easy and high yield synthesis of several group 13 MesDPM compounds (Al-In) with alkyl substituents at the metal atom. All these compounds were fully characterized using techniques including X-ray diffraction analysis and photoluminescence measurements. It shows that for aluminium and gallium pronounced green fluorescence is observed, which is absent for indium. DFT calculations confirm that the first electronic transition corresponds to a ligand-based π-π* transition.

Highly efficient removal of trace heavy metals by high surface area ordered dithiocarbamate-functionalized magnetic mesoporous silica.

The study describes synthesizing and characterizing a novel dithiocarbamate-functionalized magnetic nanocomposite. This nanocomposite exhibits several desirable properties, including a large pore diameter of 2.55 nm, a high surface area of 1149 m2/g, and excellent capturing capabilities. The synthesis process involves the preparation of highly porous magnetic nanocomposites, followed by functionalization with dithiocarbamate functional groups through a reaction with carbon disulfide and amine. The synthesized nanocomposite was thoroughly characterized using various techniques, including X-ray diffraction analysis, transmission electron microscopy, scanning electron microscopy, Fourier-transform infrared spectroscopy, and thermogravimetric analysis. The performance of the mesoporous nanocomposite as an adsorbent for removing Pb(II), Cd(II), and Cu(II) cations from contaminated water was evaluated. The study finds that the maximum removal efficiency for Pb(II), Cd(II), and Cu(II) cations is achieved at pH values above 4. The optimal contact time for achieving 100% removal efficiency of the mentioned cations ranged between 60 and 120 min. Within this time range, the adsorbent exhibited efficient capture of the heavy metal cations from contaminated water. Additionally, the appropriate amount of adsorbent required for complete elimination of the heavy metal cations is determined. For Cd(II), the optimal dosage was found to be 50 mg of the adsorbent. For Cu(II), the optimal dosage was determined to be 40 mg. Finally, for Pb(II), the optimal dosage was 30 mg. The adsorbent's regeneration capability was demonstrated, showing that it could be reused for five consecutive runs.

Enhancement of adhesion strength and in-vivo evaluation of electrodeposited calcium phosphate/chitosan biocoatings on titanium substrate

Chitosan/calcium phosphate nanocomposites are widely used as a biocompatible coatings for titanium bioimplants in the fields of dentistry and orthopedics to enhance the integration between the implants and the hard bone. However, the poor adhesion strength between the coating and the metal substrate was found to be one of the major problems in the clinical application of these implants. In the current study, we reported the formation of Ca/P coating on titanium (Ti) substrate using electrodeposition. The key factor of the bath ingredients is the change of chitosan's solvent from a commonly used acetic acid to acrylic acid in the electrolyte. The structural analysis including X-ray diffraction (XRD), Raman spectroscopy, and attenuated total reflectance (ATR) confirmed the formation of three phases of Ca/P octacalcium phosphate (OCP), dicalcium phosphate dihydrate (DCPD) brushite, and hydroxyapatite (HA). The bond strength was performed by the tape test (ASTM D3359-09) which showed that nearly 65% of the coatings were removed in the case of using 2, 4, and 6% (v/v) acetic acid as chitosan solvent, while only 5% of the coatings were removed when high concentrations (4 and 6%) of acrylic acid is used in addition to increasing of the surface wettability. Furthermore, the morphology and thickness of the calcium phosphate layer coated on the surface of Ti metal were inspected by scanning electron microscopy (SEM). Finally, an in vivo application was conducted on the optimized coating by surgically placing the coated and control discs into rats’ clavicular bones for 2-weeks healing period. Then biomechanical evaluation was performed to verify the effect of treatment on the interface resistance to shear force, and histological analysis was performed to evaluate the bone tissue reactions to coated discs. The results showed that using acrylic acid instead of acetic acid to dissolve chitosan before in-situ electrodeposition might be an innovative approach to enhance the adhesion strength between chitosan/calcium phosphate-based coatings and titanium metal to be used in orthopedic and dental implant technology.

Hyaluronic acid/cellulose acetate polymeric mixture containing binary metal oxide nano-hybrid as low biodegradable wound dressing

Wound dressing from a polymeric mixture of cellulose acetate (CA) and hyaluronic acid (HA) embedded with copper oxide (CuO) and magnesium oxide (MgO) nanoparticles as a scaffold was successfully fabricated. Several methods, including X-Ray diffraction analysis (XRD), contact angle, Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM), were employed to characterize the prepared nanocomposite samples. The data obtained from XRD showed that pure HA with diffraction peaks at 2θ = 20.8°, 46.7°, and 63.2° that assigned to the semi-crystalline nature of HA. At the same time, the XRD pattern of the CuO@CA nanocomposites revealed the presence of a sharp crystalline peak at 2θ = 36°, representing the presence of the CuO nanomaterial. In addition, the typical cubic MgO peaks in the MgO@CA showed the pattern at 2θ = 43.1° and 62.5°. Furthermore, the diffraction pattern of CuO/MgO@HA/CA film shows strong crystallinity since its diffraction peaks are stated at 2θ = 8.8°, 13.01°, 29.6°, and 53.5° which represents CuO nanoparticles and the polycrystalline cubic structure of MgO nanoparticles exhibit several peaks at 2θ = 29.4°, 31°, 38.7°, 42.2°, and 63°. FTIR spectra of CuO/MgO@HA/CA displayed bands at 657 cm−1 and 843 cm−1 which correspond to the broadening vibration mode for the Mg-O-Mg and the existence of Mg-O vibrations, while the single band for CuO was shown at 1556 cm−1. SEM analysis revealed that the nanoparticles of copper oxide and magnesium oxide are evenly distributed throughout the polymer mass with the clean surface of the polymer with the appearance of nanoparticles with rough size and distribution in regions of varied densities by adding binary metal oxide nanoparticles (CuO/MgO@HA/CA). Furthermore, swelling rate percent, contact angle, and degradation behavior studies showed that the swelling rate percent of the polymer mixture film decreased when adding nanometal oxide. Contact angle was increased by incorporating the metal oxide nanoparticles in the polymeric mixture structure. Moreover, the degradation behavior of prepared samples showed lower rates of deterioration and the sample containing a mixture of metal oxide nanoparticles (CuO/MgO@HA/CA) exhibits a lower weight loss value when compared to HA, HA/CA, and CA samples. Human osteosarcoma MG-63 cells were used in in-vitro cytotoxicity tests. CuO/MgO@HA/CA sample treatment on cells suggests a non-cytotoxic impact, in contrast to the MTT test, which yields cell viability values of between 70% and 80% (72 h).

Artificial intelligence optimization and experimental procedure for the effect of silicon dioxide particle size in silicon dioxide/deionized water nanofluid: Preparation, stability measurement and estimate the thermal conductivity of produced mixture

Recent studies for nanofluids, did not pay enough attention to the effect of the nanoparticle size and nanofluid stability on the heat transfer rate. In this study, the thermal conductivity (TC) coefficient of silica/deionized water (DW) nanofluid with various sizes of nanoparticles and various rates of nanofluid stability was investigated. Validation experiments, including X-Ray diffraction analysis (XRD), FE-Scanning Electron Microscopy (FE-SEM), Dynamic Light Scattering (DLS), and Zeta Potential (Zp), were carried out to examine the particle sizes and the nanofluid stability. The results illustrated that increasing the temperature leads to the augmentation of the TC coefficient of the SiO2/deionized water in all nanoparticle sizes and all volume concentrations. Also, increasing the volume concentration of the nanofluid leads to the augmentation of the TC coefficient of the nanofluid in all nanoparticle sizes and all temperatures. Eventually, increasing the nanoparticle sizes causes the TC coefficient of the nanofluid to be decreased in all volume concentrations. For the 11 nm nanoparticle size, the amount of the Relative TC (RTC) coefficient enhancement by increasing the temperature was 1.2%, 2.5%, 4.7%, and 6.8% for concentrations of 0.0.1%, 0.1%, 0.5%, and 1%, respectively. For the 50 nm nanoparticle size, this enhancement was from 0.7% to 6.5%, and for the 70 nm nanoparticle size, it was from 0.5% to 5.7%. Finally, Artificial Intelligence (AI) optimization was done to find the optimized size and stability.

Development of ZnO-GO-NiO membrane for removal of lead and cadmium heavy metal ions from wastewater

The presence of heavy metal (HM) ions, such as lead, cadmium, and chromium in industrial wastewater discharge are major contaminants that pose a risk to human health. These HMs should separate from the wastewater to ensure the reuse of the discharged water in the process and mitigate their environmental impacts. The distinctive mechanical properties of 2D graphene oxide (GO), and the antifouling characteristics of metal oxides (ZnO/NiO) nanoparticles combined to produce composites supporting special features for wastewater treatment. This study employed solution casting and phase inversion methods to synthesize PSF-based GO, ZnO-GO, and ZnO-GO-NiO mixed matrix membranes and the effects of variation in composition on the removal of lead (Pb2+) and cadmium (Cd2+) ion was examined. Several characterization techniques including X-ray diffraction analysis, scanning electron microscopy, energy dispersive X-ray, and Fourier transform infrared spectroscopy were applied to analyze the synthesized NPs and MMMs. The composite membranes were also analyzed in terms of their porosity, permeability, hydrophilicity, surface roughness, zeta potential, thermal stability, mechanical strength, and flux regeneration at various transmembrane pressures (2–3 kgcm−2), and pH value (5.5). The highest adsorption capacities were measured to be 308.16 mg g−1 and 354.80 mg g−1 for Pb (II) and Cd (II), respectively, for membrane (M4_A) having 0.3 wt% of ZnO-GO-NiO nanocomposite, at 200 mg L−1 of feed concentration and 1.60 mL min−1 of permeate flux. The Pb (II) and Cd (II) adsorption breakthrough curves were created, and the results of the experiment were compared with the data of the Thomas model.

Carbon quantum dots: synthesis and applications as turn-off fluorescence sensors for detection of Co2+ ions in water and eco-friendly catalysts for treatment of wastewater

Carbon quantum dots (CQDs) are a new generation of QDs that have unique and interesting optical and structural properties. Fluorescence methods are useful, simple, and rapid for the detection of heavy metal ions in water, which has attracted great attention. In this research, a simple and rapid fluorescence method for the detection of cobalt (Co2+) ions in water is introduced. CQDs were synthesized by using pistachio as a precursor for the first time by a hydrothermal method. The QDs were characterized by structural analyses including x-ray diffraction, tunneling and scanning microscopies, energy-dispersive x-ray spectroscopy, infrared spectroscopy, BET surface area measurements, zeta potential measurements, and Raman spectroscopy. The Raman spectroscopy results showed a 3.54 value for the G/D ratio and this result confirmed that synthesized CQDs possess a graphitic crystalline structure. Zeta potential measurements confirmed the presence of a negative surface charge, resulting in high stability. These CQDs had blue photoemission with a broad PL peak between 300 to 600 nm. TEM images showed that CQDs are spherical with diameters of ∼7 nm. Their photocatalytic activities were studied with different dyes under both sun and UV light. Methylene blue had better degradation by the CQDs than methylene orange and Rhodamine B. The scavenger results indicate that radicals play a key role in the photocatalytic degradation of methylene blue under UV irradiation.

Competitive incorporation of Mn and Mg in vivianite at varying salinity and effects on crystal structure and morphology

Vivianite, a ferrous phosphate mineral, can be an important phosphorus (P) sink in non-sulfidic, reducing coastal sediments. The Fe in the crystal structure of vivianite can be substituted by other divalent metal cations such as Mn2+ or Mg2+. Since Mg is much more abundant in coastal porewaters than Mn, the more frequent reports of Mn substitution in vivianites of coastal sediments has been suggested to indicate a preferential incorporation of Mn over Mg into the crystal structure of vivianite. However, although both Mn and Mg substitution in vivianite are environmentally relevant, it is yet unknown whether Mn or Mg is preferentially incorporated and how these isomorphic substitutions alter the crystal structure and morphology of vivianite, parameters which may influence vivianite reactivity. Here, we studied the incorporation of Mn and/or Mg in vivianites formed by co-precipitation at pH 7 in the presence of varying dissolved Mn and/or Mg concentrations and solution salinities resembling an estuarine gradient from 0 to 9 psu. In total, 19 different vivianites were synthesized, with up to 50% of Fe substituted by Mn and Mg. Thermodynamic equilibrium calculations showed that aqueous Mg speciation was altered with increasing salinity, while Mn speciation was less affected, likely explaining the preferential incorporation of Mn in the vivianite structure at higher salinities. 57Fe-Mössbauer spectroscopy revealed that both Mn and Mg were preferentially incorporated in the double-octahedral Fe position, at which intervalence charge transfer is possible during the oxidation of vivianite. In contrast to Mg, which is redox inactive, incorporated Mn can participate in heteronuclear intervalence charge transfer with Fe. Thus, incorporation of either cation may impact the reactivity of vivianite under oxidizing conditions in element specific ways. Results of complementary analyses including X-ray diffraction, electron microscopy and Fe K-edge X-ray absorption spectroscopy further showed that incorporation of Mn and/or Mg led to smaller particle size, increased crystal roughness and thinner crystals, as well as systematic changes in unit cell parameters. These observed changes in crystal morphology might impact the reactivity of vivianite in natural environments and thus the effect of cation incorporation in vivianite should be considered when studying Fe and P cycling in coastal sediments.

Biogenic Synthesis of CuO, ZnO, and CuO-ZnO Nanoparticles Using Leaf Extracts of Dovyalis caffra and Their Biological Properties.

Biogenic metal oxide nanoparticles (NPs) have emerged as a useful tool in biology due to their biocompatibility properties with most biological systems. In this study, we report the synthesis of copper oxide (CuO), zinc oxide (ZnO) nanoparticles (NPs), and their nanocomposite (CuO–ZnO) prepared using the phytochemical extracts from the leaves of Dovyalis caffra (kei apple). The physicochemical properties of these nanomaterials were established using some characterization techniques including X-ray diffraction analysis (XRD), ultraviolet-visible spectroscopy (UV-vis), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDX). The XRD result confirmed the presence of a monoclinic CuO (Tenorite), and a hexagonal ZnO (Zincite) nanoparticles phase, which were both confirmed in the CuO–ZnO composite. The electron microscopy of the CuO–ZnO, CuO, and ZnO NPs showed a mixture of nano-scale sizes and spherical/short-rod morphologies, with some agglomeration. In the constituent’s analysis (EDX), no unwanted peak was found, which showed the absence of impurities. Antioxidant properties of the nanoparticles was studied, which confirmed that CuO–ZnO nanocomposite exhibited better scavenging potential than the individual metal oxide nanoparticles (CuO, and ZnO), and ascorbic acid with respect to their minimum inhibitory concentration (IC50) values. Similarly, the in vitro anticancer studies using MCF7 breast cancer cell lines indicated a concentration-dependent profile with the CuO–ZnO nanocomposite having the best activity over the respective metal oxides, but slightly lower than the standard 5-Fluorouracil drug.

Self-Assembled Interwoven Nanohierarchitectures of NaNbO3 and NaNb1–xTaxO3 (0.05 ≤ x ≤ 0.20): Synthesis, Structural Characterization, Photocatalytic Applications, and Dielectric Properties

Dependence on fossil fuels for energy purposes leads to the global energy crises due to the nonrenewable nature and high CO2 production for environmental pollution. Therefore, new ways of nanocatalysis for environmental remediation and sustainable energy resources are being explored. Herein, we report a facile surfactant free, low temperature, and environmentally benign hydrothermal route for development of pure and (5, 10, 15, and 20 mol %) Ta-doped horizontally and vertically interwoven NaNbO3 nanohierarchitecture photocatalysts. To the best of our knowledge, such a type of hierarchical structure of NaNbO3 has never been reported before, and changes in the microstructure of these nanoarchitectures on Ta-doping has also been examined for the first time. As-synthesized nanostructures were characterized by different techniques including X-ray diffraction analysis, electron microscopic studies, X-ray photoelectron spectroscopic studies, etc. Ta-doping considerably affects the microstructure of the nanohierarchitectures of NaNbO3, which was analyzed by FESEM analysis. The UV–visible diffused reflectance spectroscopy study shows considerable change in the band gap of as-synthesized nanostructures and was found to be ranging from 2.8 to 3.5 eV in pure and different mole % Ta-doped NaNbO3. With an increase in dopant concentration, the surface area increases and was equal to 5.8, 6.8, 7.0, 9.2, and 9.7 m2/g for pure and 5, 10, 15, and 20 mol % Ta-doped NaNbO3, respectively. Photocatalytic activity toward the degradation of methylene blue dye and H2 evolution reaction shows the highest activity (89% dye removal and 21.4 mmol g–1 catalyst H2 evolution) for the 10 mol % NaNbO3 nanostructure which was attributed to a change in the conduction band maximum of the material. At 100 °C and 500 kHz, the dielectric constants of pure and 5, 10, 15, and 20 mol % Ta-doped NaNbO3 were found to be 111, 510, 491, 488, and 187, respectively. The current study provides the rational insight into the design of nanohierarchitectures and how microstructure affects different properties of the material upon doping.

Microbial removal of zinc by a zinc resistant bacterium: potential in industrial waste remediation

Bioremediation, the use of living or dead microorganism to degrade or remove the waste, has been practised since humans first populated the world and had to dispose of their trash. Heavy metals can be extremely toxic as they damage organs and block functional groups of vital enzymes. Zinc is one of the most important heavy metals often found in effluents discharged and travels via bioaccumulation. The study was aimed in screening of zinc resistant/accumulator bacterial strains isolated from metal contaminated sites and determining the Zn (II) resistance/accumulation performance of selected bacterial strain as a new biosorbent. The maximum removal of Zn (II) at pH 7.0 was found to be 607 nmol/mg proteins at initial Zn (II) ion concentration of 1.0 mM and the Km value was 0.76mM. Competitive uptake experiments were performed with zinc in the presence of copper, cadmium, chromium, cobalt and nickel ions simultaneously and the zinc uptake was not much affected by these ions. Sensitivity of Zn (II) towards sodium azide, zinc cyanide 0.5% glucose and heat suggested that the process was metabolically inactive. The nature of the possible cell–metal ions interactions was evaluated by chemical and instrumental analysis including X-Ray diffraction and FTIR spectroscopy and revealed the involvement of cellular phosphate and carboxyl groups in zinc binding by the bacterial biomass. Almost 61% of biomass-bound Zn could be recovered using H2SO4 as the desorbing agent. In natural environment some bacterial strains develop resistance mechanisms that lead to the selection of metal resistant strains tolerating high zinc concentration.

Mineralogy and elemental geochemistry of Permo-Carboniferous Li-enriched coal in the southern Ordos Basin, China: Implications for modes of occurrence, controlling factors and sources of Li in coal

As the decisive element promoting the battery industry and a raw material in aerospace Al-Li alloys, the demand for Li is increasing daily. At present, the exploitation and utilization of lithium resources mainly originates from brine (salt lake) deposits and pegmatite deposits. Emerging sediment hosts, including coal-hosted Li deposits, provide a potential source of lithium resources. Based on proximate analyses, including X-ray diffraction analysis (XRD), energy dispersive X-ray spectroscopy (SEM-EDX), X-ray fluorescence spectroscopy (XRF), and inductively coupled plasma mass spectrometry (ICP-MS), the petrological, mineralogical and geochemical characteristics were determined in Permo-Carboniferous Li-enriched coal and Jurassic coal in the southern margin of the Ordos Basin. The results show that Li concentrations in Permo-Carboniferous coal seams range from 16.2 μg/g to 521 μg/g. The maximum Li concentrations occur in parting samples of the Permo-Carboniferous coal seam and are as high as 1822 μg/g. The correlation coefficient of Li with other mineralogical and geochemical parameters shows that clay minerals are the main carriers of Li in coal seams. The discovery of high-temperature minerals (pyroclastic quartz and zircon) and vermicular kaolinite with good crystalline form provide direct evidence for the contribution of volcanic ash to coal. The enrichment of lithium in coal-measure strata is dominated by a Li-enriched source, sealing layer and enrichment place. Li originated from felsic volcanic ash, was captured by clay minerals, sealed in by the coal seam, and preferentially enriched in the coal seam parting. The coal seam itself can also cause some aluminosilicate minerals to be enriched in Li by ionic isomorphism.