SEM-EDAX Analysis Research Articles

SEM-EDAX and ICP-OES analysis of Rasa Bhasma along with its Physico-chemical characterization

Abstract- Rasa Bhasma is a Herbo-Mineral preparation mentioned by Shri Anantadeva Soori in his textbook Rasa Chintamani in the context of Parada Marana. Owing to its Hepato-protective indication, it was prepared as per the conventional method and was subjected to various physico-chemical parameters, assessment of inorganic elements, SEM EDAX and ICP-OES for the determination of Mercury. Results revealed that Rasa Bhasma was tasteless, grey coloured smooth powder having alkaline nature insoluble in water and alcohol but sparingly soluble in Chloroform with values total ash- 88.10%, acid insoluble ash- 83.03%, loss on drying-0.675%. Amongst inorganic elements, sodium, chlorides and sulphates were found to be present in the Bhasma. SEM/EDAX spectra show the results of Mercury, Sulphur, Carbon, Oxygen, in various spectrums. The % of Mercury is maximum i.e., between 65-75% each. Sulphur varies from 25-30%. Carbon is rich in quantity varying from 25-30%. In all the Spectrums, Mercury is associated with Sulphur, forming a major peak and small Mercurial peaks are also seen along with small peaks of carbon. 98.3% mg/kg Mercury was found to be present in the Rasa Bhasma by ICP-OES analysis. Physico- chemical parameters of Rasa Bhasma were found to be within normal limits concluding that the prepared Rasa Bhasma was of standard quality.

Development of Nano-Hydroxyapatite Polymer Composite and it's in vitro Activity for Biomedical Applications

In present work, the composites of hydroxyapatite with polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) were prepared and analyzed for its biodegradability and hemocompatibilty. The individual and the combined combination of polymers with hydroxyapatite (HAP-PVA, HAP-PVP and HAP/PVA-PVP) were characterized by FT-IR, XRD, SEM-EDAX and TGA-DSC analysis. The crystallinity and functional groups of hydroxyapatite (HAP) was confirmed by XRD and FT-IR analysis. The SEM analysis displayed rod shaped morphology and the formation of apatite layer was confirmed by simulated body fluid (SBF) immersion. The Ca/P ratio of the SBF immersed composite was found to be increased to 1.71. This reveals that the polymer in the composite acts as a nucleating site for the development of carbonated hydroxyapatite which chemical composition resembles with natural bone. The hemolysis rate for the composite consisting of HAP/PVA-PVP was found to be less than 3% than the composite consisting of HAP with PVP. Based on these results, it can be concluded that the HAP/PVA-PVP nanocomposite offers superior alternatives in the field of biomedicines.

Nitrates Removal from Simulated Groundwater Using Nano Zerovalent Iron Supported by Polystyrenic Gel.

The main objectives of this present paper were to indicate the immobilization of nano zerovalent iron (nZVI) onto a polymeric material (Purolite A400) and the synthesis of the polymeric material (A400-nZVI) through sodium borohydride (NaBH4) reduction. The obtained polymeric material (A400-nZVI) was used for the nitrate ions removal from a simulated groundwater at different conditions. The polymeric materials, without and with nano zerovalent iron (A400 and A400-nZVI), were characterized trough the FTIR, SEM-EDAX, XRD, and TGA analysis. The analysis confirmed the presence of nano zerovalent iron (nZVI) onto the polymeric material (A400). The adsorption capacity of A400-nZVI, used as polymeric adsorbent, was evaluated by kinetic and thermodynamic studies. The obtained experimental results indicated that the nitrate ions reduction was fitted well by models: pseudo-second-order kinetic and Freundlich isotherm. According to the kinetic model results, a reaction mechanism could exist in the stage of reactions. The higher value of removal nitrate (>80%) was obtained under acidic condition. The results indicated that the obtained polymeric material (A400-nZVI) can be considered as a potential polymeric adsorbent for different pollutants from groundwater and wastewater.

The cadCA and cadB/DX operons are possibly induced in cadmium resistance mechanism by Frankia alni ACN14a

BackgroundCadmium (Cd2+) is one of the highly toxic heavy metals and is considered as a carcinogenic agent. Our aim was to confirm the ability of Frankia alni ACN14a to resist Cd2+ and to determine the genes involved in the resistance mechanism. ResultsF. alni ACN14a and Frankia casuarinae CcI3 hyphae showed up to 10 and 22 times Cd2+ accumulation when exposed to 1 mM Cd2+, respectively. Scanning electron microscopy (SEM) exhibited a stable Cd2+ precipitate on the cell surface, and the increase in Cd2+ weight level reached 16.45% when evaluated with SEM-EDAX analysis. The following two potential Cd2+ operons were identified: 1. cadCA operon, which encodes a copper-transporting P-type ATPase A (cadA, FRAAL0989) and an ArsR family regulator (cadC, FRAAL0988), with 37- and 70-fold increase in their expression by qRT-PCR, respectively and 2. cadB/DX, which encodes a putative cobalt-zinc-cadmium resistance protein (cadD, FRAAL3628) and heavy metal-associated domain protein (cadX, FRAAL3626), with 22- and 16-fold upregulation when exposed to Cd2+ stress. ConclusionsCd2+ tolerance by F. alni ACN14a involved efflux of Cd2+ outside the cells and binding it to the membrane surface. Our results indicate the existence of two cadmium-resistance mechanisms in Frankia strains, which support the idea of using them as a bioremediation agent.How to cite: Rehan M, Alhusays A, Serag AM, et al. The cadCA and cadB/DX operons are possibly induced in cadmium resistance mechanism by Frankia alni ACN14a. Electron J Biotechnol 2022;60. https://doi.org/10.1016/j.ejbt.2022.09.006.

PbS/graphene hybrid nanostructures coated glassy carbon electrode for the electrochemical sensing of copper ions in aqueous solution.

In this research, we have studied the electrochemical sensing of Cu(II) ions in aqueous solution using PbS/Graphene composite nanostructure coated glassy carbon electrode (GCE). The SEM-EDAX analysis revealed that the lead sulphide nanocrystals are homogeneously embedded on the graphene nanosheets with an uniform particle size of 100nm, and the elements presents 92.32% and Lead content of 5.45% and Sulfur content of 0.91%. Raman spectra exhibits G with respect to the E2g sp2 hybridized C-C and D band with respect to the A1g mode in the disordered edge region of the GNS. The composite nanostructure coated GCE (PbS/Graphene/GCE) was prepared and its performance in the existence of metal ions such us Cd(II),Pb(II), Mg(II), Cu(II) and Ni(II) was studied using the current voltage curves in double distilled water within the scan rates of 25 to 300mVs-1. The PbS/Graphene coated carbon electrode exhibited the higher anodic and cathodic peak current for copper solution than the other metal ions studied, which various linearly proportional to concentration. The electrochemical sensing characteristics PbS/GNS/GCE was found to be significant towards detecting Cu2+ ion within the concentration range of 1×10-4 to 1×10-8M, with a lowest sensing detection limit of 1×10-8M.

Anti-Dengue Activity of ZnO Nanoparticles of Crude Fucoidan from Brown Seaweed S.marginatum.

Dengue fever is a rapidly spreading infection that affects people all over the tropics and subtropics, posing a significant public health threat. The brown seaweed Stoechospermum marginatum was found all over the world, from South Africa (Indian Ocean) to Australia (Pacific Ocean), among other places. In India, it is only available along the coast of the Bay of Bengal, which is a small region. Various metal oxides were proved to be successful in the formation of nanoparticles and zinc is one among them. In this present study, an attempt was made to study the anti-dengue activity of green synthesized zinc oxide nanoparticles of crude fucoidan isolated from brown seaweed S. marginatum. The fucoidan was isolated from the seaweed by acid extraction method and then characterized by UV, HPLC, and Fourier Transform Infra-Red (FT-IR) Spectroscopy. Then it was biosynthesized into ZnO nanoparticles and characterized by SEM-EDAX analysis. The results showed the formation of fucoidans and SEM studies showed the crystalline nature of the synthesized nanoparticles. The size of nanoparticles was in the range of 80-126nm. The synthesized nanoparticles were tested with the C6/36 cell line and it was shown 99.09% of anti-dengue activity against the tested cell line. As an antiviral agent, the ZnO nanoparticles of fucoidans have been shown to be an excellent lead molecule for the treatment of dengue fever.

Composite Materials Based on Gelatin and Iron Oxide Nanoparticles for MRI Accuracy.

The majority of recent studies have focused on obtaining MRI materials for internal use. However, this study focuses on a straightforward method for preparing gelatin-based materials with iron oxide nanoparticles (G–Fe2O3 and G–Fe3O4) for external use. The newly obtained materials must be precisely tuned to match the requirements and usage situation because they will be in close touch with human/animal skin. The biocompatible structures formed by gelatin, tannic acid, and iron oxide nanoparticles were investigated by using FTIR spectroscopy, SEM-EDAX analysis, and contact angle methods. The physico-chemical properties were obtained by using mechanical investigations, dynamic vapor sorption analysis, and bulk magnetic determination. The size and shape of iron oxide nanoparticles dictates the magnetic behavior of the gelatin-based samples. The magnetization curves revealed a typical S-shaped superparamagnetic behavior which is evidence of improved MRI image accuracy. In addition, the MTT assay was used to demonstrate the non-toxicity of the samples, and the antibacterial test confirmed satisfactory findings for all G-based materials.

Green Synthesis of Silver Nanoparticles using Plant Extracts and Their Applications for Water Purification and Anti-Diabetic Properties

The study reports the synthesis of silver nanoparticles (AgNPs) using green method where plant extracts of Turmeric, curry-leaves, Ashwagandha, Arjun, Aloe vera and Tulsi were used as reducing agents. Characterization was done using UV-Visible spectroscopy and Scanning electron microscopy. UV-Visible spectrum showed peak absorbance around 420nm and SEM-EDAX analysis confirmed the presence of AgNPs in a size range of 50-80nm. Ability of the synthesized AgNPs as an antimicrobial agent was studied and their use was extended to the treatment of contaminated water. It was found that 30μL of AgNPs effectively decontaminated water containing 103 CFU/mL E. coli within 10 minutes. The study also focuses on the effect of the nanoparticles on the growth of Saccharomyces cerevisiae as a model organism for eukaryotic cells. No significant effect on the growth of S. cerevisiae was observed. Effect of AgNPs on advanced glycation end-products (AGEs) was also studied. AGEs are formed due to non-enzymatic glycation in hyperglycemic conditions leading to secondary complications in diabetes. AgNPs synthesized using Ashwagandha, curry-leaves and Aloe vera showed anti-glycating properties in a concentration dependent manner. This suggests that these properties of AgNPs may be used in many environmental and therapeutic applications but their use should be regulated and studied in detail.

PROFICIENT PHOTOCATALYTIC DEGRADATION OF METHYLENE BLUE DYE USING Ti-DOPED CdSe NANOPARTICLES UNDER SOLAR LIGHT IRRADIATION

The present analysis explores the photocatalytic activity of Ti-doped CdSe and undoped CdSe nanoparticles towards Methylene Blue (MB) dye degradation under solar light irradiation. The as prepared Ti-CdSe and mere CdSe nanoparticles were characterized using XRD, UV, FTIR, TGA, SEM and TEM analysis. TEM micrographs confirm the synthesized samples are in nanometer regime. The insertion of Titania onto CdSe lattice was confirmed by XRD and SEM-EDAX analysis. The absorption spectrum of Ti doped CdSe nanoparticles showed blue shift (lower wavelength) than mere CdSe. Ti-CdSe nanoparticles have greater thermal stability than mere CdSe nanoparticles. The photocatalytic activity of the Ti-CdSe nanoparticles photocatalyst was determined by degrading a MB dye under solar light irradiation. Ti-CdSe nanoparticles maintain high photocatalytic activity under solar light irradiation in comparison to mere CdSe nanoparticles. Low electron-hole pair recombination with increased efficiency was observed under solar light due to the strong absorption by the photocatalyst under solar light. The main active species responsible for catalytic degradation are H+ and OH˙. The probable catalytic mechanism was proposed from the experimentally derived results.

Dielectric, impedance spectroscopy and hydroelectric phenomena in lanthanum doped bismuth ferrite (Bi0.85La0.15FeO3)

Multiferroic materials are fascinating to discover due to presence of more than two ferroic orderings in the same phase. The lanthanum doped bismuth ferrite (Bi0.85La0.15FeO3) multiferroic nanoparticles are synthesized by sol–gel technique. This 15 % substitution of La in BiFeO3 is chosen due to its improved structural and electrical properties. The structural and impedance properties of Bi0.85La0.15FeO3 has been reported successfully. X-ray diffraction studies and EDX analysis are done to investigate the structural properties. X-ray powder diffraction patterns confirm the formation of single-phase perovskite structure of Bi0.85La0.15FeO3 (BLFO). SEM-EDAX analysis indicates the circular grains in Bi0.85La0.15FeO3 with extensive agglomeration. The dielectric studies display conventional Maxwell-Wagner Polarization in the nanoparticles. Impedance spectroscopy confirms high resistance of BLFO as well as contribution of grains and grain boundaries in BLFO. The hydroelectric cell fabricated using BLFO nanoparticles display improved potential. These properties are owing to improved structural stability and suggest their use in hydroelectric cell application.

The Influence of Silica Nanoparticles on the Thermal and Mechanical Properties of Crosslinked Hybrid Composites.

This paper presents the synthesis and physicochemical characterization of a new hybrid composite. Its main goals are evaluating the structure and studying the thermal and mechanical properties of the crosslinked polymeric materials based on varying chemical properties of the compounds. As an organic crosslinking monomer, bisphenol A glycerolate diacrylate (BPA.GDA) was used. Trimethoxyvinylsilane (TMVS) and N-vinyl-2-pyrrolidone (NVP) were used as comonomers and active diluents. The inorganic fraction was the silica in the form of nanoparticles (NANOSiO2). The hybrid composites were obtained by the bulk polymerization method using the UV initiator Irqacure 651 with a constant weight ratio of the tetrafunctional monomer BPA.GDA to TMVS or NVP (7:3 wt.%) and different wt.% of silica nanoparticles (0, 1, 3%). The proper course of polymerization was confirmed by the ATR/FTIR spectroscopy and SEM EDAX analysis. In the composites spectra the signals correspond to the C=O groups from NVP at 1672–1675 cm−1, and the vibrations of Si–O–C and Si–O–Si groups at 1053–1100 cm−1 from TMVS and NANOSiO2 are visible. Thermal stabilities of the obtained composites were studied by a differential scanning calorimetry DSC. Compared to NVP the samples with TMVS degraded in one stage (422.6–425.3 °C). The NVP-derived materials decomposed in three stages (three endothermic effects on the DSC curves). The addition of NANOSiO2 increases the temperature of composites maximum degradation insignificantly. Additionally, the Shore D hardness test was carried out with original metrological measurements of changes in diameter after indentation in relation to the type of material. The accuracy analysis of the obtained test results was based on a comparative analysis of graphical curves obtained from experimental tests. The values of the changes course of similarity in the examined factors, represented by those of characteristic coefficients were determined based on the Fréchet’s theory.

Assessment of proton conductivity, dielectric relaxation and other physicochemical properties of LTA zeolite blended chitosan composites for membrane applications

Novel chitosan biopolymer based solid electrolyte system consisting of surfactant-modified zeolite A are fabricated via simple solvent-casting technique to yield thin film proton exchange membrane. The zeolite LTA (Linde type-A) is synthesized and then it is impregnated with a surfactant, sodium dodecyl sulfate. The interfacial compatibility as well as the strong interaction in the polymer-filler system, modification of zeolite-A as well as its elemental composition is confirmed using FTIR, XRD and SEM-EDAX analysis. The physicochemical characteristics of the prepared membranes such as water uptake, IEC, hydration number and dimensional stability found to increase with increasing concentrations of the doped zeolitic filler. The appreciable mechanical as well as oxidative stability displayed by the membranes is due to the strong H-bond interaction between the polymer and modified zeolite. Overall, CSA-1.0 composite membrane showed the highest proton conductivity of 4.45 mS cm−1 at 80 °C, good thermal stability with Tmax = 217 °C and lesser gas permeability around 5 barrer. By determining the bound water content of the membranes using TGA analysis, the self-humidification characteristics were investigated. Good compatibility and interfacial interaction in the composite membranes has resulted in the creation of non-tortuous pathways for efficient proton transfer predominantly through Grotthus type mechanism. The relevant mechanism for the proton transfer along the membranes is evaluated in terms of complex impedance analysis, dielectric permittivity and electric modulus spectra. On the whole, the results obtained from various analysis suggests that the fabricated composite membranes are good alternatives as proton exchange membranes for fuel cell applications.

Development and performance evaluation of quaternary blended concrete incorporating industrial waste

In the present study, waste from the tiles factory, in the form of vetrified tiles powder in addition to which fly ash and micro silica were incorporated in different proportions in formulating the mix proportions. Compressive strength was calculated for all specimens casted with different proportions. From the analysed results, the mix with 60% cement, 25% tiles powder, 7% silica fume and 8% fly ash was found to be an optimum mix. The flexural strength value for the optimum mix was obtained to be 5.45 MPa, 6.83 MPa at 7 and 28 days of curing age. Similarly the values of 2.5 MPa and 4.08 MPa were observed for split tensile strength for the optimum mix at 7 and 28 days of curing age. XRD analysis of the obtained optimum mix was carried out to determine the intensities of the crystalline phases and compared with that of the control mix. SEM-EDAX analysis to determine the morphology and elemental variability of the mixes was carried out. The percentage weight loss of the matrix due to the decomposition of the hydration products when exposed to different temperature ranges was investigated using Thermogravimetric analysis (TGA). From the results obtained, the developed concrete mix can be utilised for commercial purposes of construction activities owing to the strength in terms of compressive, flexural and split tensile. The developed concrete also meets the criteria of sustainability where in the natural resources like cement has been saved, there by reducing the Carbon foot print.

Enhancement in photostability of betalain dye from basella Alba fruits using zinc oxide nanoparticles

Recently environmental pollution due to industrial effluents is a major concern for researchers, so the development of natural dyes is widely accepted due to their low cost, biodegradability, low toxicity, and non -carcinogenic nature and also replaces existing hazardous chemicals in industries. Many plants and fruit extracts can be used as natural dyes, but their efficiency depends on photostability and photo degradation activity. Herein reported extraction of natural dye fromBasella Alba fruit using different solvents and photo stability was investigated under UV and visible light. To enhance the stability of extracted pure dye, zinc oxide nanoparticles were added and it acts as an excellent photostabilizer that shows better performance over betalain dye. UV visible spectrum of pure dye shows an absorbance peak of 480 nm and functional groups of both dye and zinc oxide were identified by FTIR spectrum. The structure and surface morphology of the synthesized nanoparticle was confirmed by UV–Visible, XRD, SEM-EDAX and TEM analysis. The crystalline structure of zinc oxide was confirmed by XRD and composition was analyzed by EDAX studies. The wurtzite type structure of zinc nanoparticle was confirmed by XRD. The external morphology of prepared zinc oxide nanoparticles is captured using FESEM. The HRTEM and SAED images are confirmed the crystalline structure of the synthesized material. The photostability and photodegradation studies were performed under UV light and at various temperatures like 40 °C, 50 °C, 60 °C, 70 °C, and 80 °C. These results clearly show a piece of evidence for the usage of nanoparticles for enhancing photostability of natural dyes.

Calcium Pretreated Pinus Roxburghii Wood Biochar for Adsorptive Removal of Fluoride from Aqueous Solution

Fluorosis due to consuming an elevated amount of fluoride-containing groundwater is believed to be a serious public health-related issue. A calcium pretreated wood of Pinus roxburghii was converted into biochar and examined for fluoride uptake from an aqueous solution. Further characterization of biochar was performed using FT-IR and SEM EDAX analysis. Results suggested the involvement of different functional groups of biochar in the sorption process. Scanning microscopy and elemental analysis showed the porous structure of biochar with an appreciably high loading of fluoride ions. Sorption of fluoride occurred due to chemical interaction between functional groups that existed over the surface of biochar. Sorption was found to be spontaneous and exothermic. The prepared adsorbent holds good promises to be used as an agent for defluoridation.

Biofabrication and characterization of cyanobacteria derived ZnO NPs for their bioactivity comparison with commercial chemically synthesized nanoparticles

Due to unique properties of the nanoparticles (NPs) with biocompatibility, their application as drug in drug delievery and diagnostics, the recent scientific branch nanotechnology has emerged as hope in modern medicine. Zinc oxide nanoparticles (ZnO NPs) have gained tremendous interest due to their potential use as chemotherapeutic and antimicrobial agents. They are included in the category of “generally recognized as safe (GRAS) metal oxide”. There is an urgent need for developing additional sources of ZnO NPs. Therefore, in the present study 30 cyanobacterial extracts were screened for ZnO NPs synthesis.. The color change of the reaction mixture from blue to pale white indicated the synthesis of ZnO NPs. It was further confirmed by UV–Visible spectroscopy that showed the absorption peak at 372 nm. The SEM analysis during screening revealed that Oscillatoria sp. synthesized smallest ZnO NPs (~40 nm) that were further optimized for their higher yield by altering reaction conditions (pH, temperature, reaction time, concentration of extract and metal precursor). Best conditions for ZnO NPs synthesis are (0.02 M zinc nitrate, 10 ml of extract volume, pH 8, at 80 °C for 3 h). The NPs were purified through calcination at 350°C and characterized by UV–Vis, FTIR, XRD, SEM-EDAX, TEM, Zeta potential and DLS analysis. The comparative analysis of purified biogenic ZnO NPs with commercial chemically synthesized ZnO NPs (CS), exhibited their superior nature as antioxidant and anti-bacterial agent against both gram-positive and gram-negative bacteria. Synergistic effects of biogenic ZnO NPs and streptomycin additionally favored for their future use as a potential biomedical agent.

Distribution of scandium in red mud and extraction using Gluconobacter oxydans

The aim was to study bioleaching of rare earth elements from red mud by a chemoorganotrophic microorganism, and to investigate the microbe-mineral interactions. Red mud is a promising resource for scandium, whose concentration was 92 and 54 mg/kg in two samples from Germany and India, respectively; however, both showed appreciably high concentration of zirconium. A gluconic acid-producing bacterium, Gluconobacter oxydans (DSMZ 46616), was used in the bioleaching experiments under parametric variation of inoculum concentration, pulp density, and culture adaptation. At a solid load of 10% (w/v) red mud with 10% (v/v) bacterial inoculum at 37 °C, a maximum solubilisation of 83% and 94% Sc was observed after 18–20 d of incubation for Indian and German red mud, respectively. The total amount of gluconic acid excreted by the bacteria increased with an increase in pulp density up to 10% (w/v). After bioleaching, SEM-EDAX analysis of the solid residue depicted enrichment of zirconium associated with the silicate matrix, and the bacterial cells were adhered to the major mineral matrix.

Trace elements distribution in stream sediments of an abandoned U mining site in the Eastern Carpathians, Romania, with particular focus on REEs

Trace elements distribution, including rare earth elements (REEs), in stream sediments of an abandoned U mining site in the Eastern Carpathians, Romania, were of high concern of interest in the present work. A total number of 40 riverbed sediments samples collected from the Bistricioara River and local tributaries (Primatar, Bradul, Prisacani, Barasau, Grintiesul Mare and Valea Seaca) were analyzed by inductively coupled plasma mass spectrometry (ICP-MS) and energy dispersive X-ray fluorescence spectrometry (XRF). All REEs including La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu were identified and quantified in the present work using ICP-MS technique. For other 24 elements (Ti, V, Cr, Co, Zn, Li, Be, Rb, Sr, Y, Sc, Zr, Nb, Sb, Ba, Ta, W, Pb, U, Ni, Cu, Mo, As, Th) similar information was obtained either by ICP-MS or XRF techniques. The impact and the relevance of the obtained data base might be significant at a local scale of about 50 km2.Enrichments of some trace elements of interest in comparison to the upper continental crust allowed discrimination between various mineralization processes specific for the investigated areas. Uranium mineralization and Paltin-type (Pb, Zn) mineralization seems to be specific for the NW area of the investigated region. Negative anomaly characteristic for the upper crustal rocks was identified for Eu and Ce elements. Evidences were obtained also for the existence of ultramafic rocks (Ni, Cr, Co and V) in the investigated riverbed sediments. The observation was also confirmed by the binary plots analysis of Th/Cr vs. Th/Co and Cr/V vs. Y/Ni pairs. From the investigated tributaries to Bistricioara River, Barasau seems to exert the highest influence on the abundances of REEss in the entire area. Most probably some chemical parameters such as the pH of the water streams influence leaching and depletions of some chemical constituents in various minerals specific for the region.The existence of magnetite, garnets, pyrite and sillimanite minerals was confirmed by SEM-EDAX and XRF analysis, as well by optical microscopy. Principal Component Analysis runs confirmed the association of some chemical elements in the riverbed sediments in close connection with the minerals from which they originate.The present work reports for the first time upon the authors knowledge clear scientific evidence and chemical information concerning the geology and geochemistry, i.e. transition metals, high field strength elements, alkali and alkaline earth elements, rare earth elements (REEs) and others, in stream sediments crossing the Tulghes-Grinties mining area (Eastern Carpathians, Romania). For the analysed REEs this is the first study reporting consistent information on the concentrations of the entire array of both light REEs (six elements) and heavy REEs (ten elements) in Bistricioara Basin stream sediments. Relevant scientific data related to geochemical characteristics of ultramafic rocks existent in the investigated area were also generated. Moreover, data reported in the present work might be considered as a reference geochemical database relevant for the investigated area, which can be used as a trustworthy input for a systematic national geochemical atlas.

Physicochemical and Antibacterial Evaluation of Poly (Vinyl Alcohol)/Guar Gum/Silver Nanocomposite Films for Food Packaging Applications

In this study, we prepared Poly (vinyl alcohol) (PVA)/Guar gum (GG) based nanocomposite films with a different weight ratio of silver nanoparticles (AgNPs) via in situ approach using GG itself as a reducing agent and PVA as a capping as well as stabilizing agent at room temperature. The in situ synthesized AgNPs in the PVA/GG matrix was confirmed by surface plasmon resonance (420–450 nm) and SEM-EDAX analysis. The average size of AgNPs was found to be 10 nm determined by XRD. The light transmittance is greatly influenced by the AgNPs. At an optimal concentration of AgNPs (6.8 mg), PVA/GG/Ag nanocomposite films showed improved tensile properties (Ts—23.93 MPa) and the water vapor transmission rate. The incorporation of AgNPs has significantly enhanced the hydrophobicity (~ 77%) as well as the thermal stability (~ 61.39%) of the PVA/GG film. The overall migration rate of the nanocomposite films with the three food simulants was shown significantly below the permitted limit of 10 mg/dm2. Further PVA/GG/Ag nanocomposite films showed a lower soil burial degradation rate than PVA/GG film and good antibacterial properties against environmental microorganisms such as S. aureus and E. coli bacteria. The results suggest that the prepared films can be used as promising food packaging materials.

Effect of drying rate on the performance of Pt-Sn-K/γ-Al2O3 catalyst for propane dehydrogenation

The dehydrogenation of propane to propylene over Pt-Sn-K/γ-Al2O3 catalysts prepared by sequential impregnation was studied. Three drying rates, that is, 5, 10 and 15 °C/min were applied after incipient wetness impregnation of the support (1.6–1.8 mm in diameter) with KNO3. The obtained catalysts were characterized by N2 physisorption, SEM-EDAX analysis and XRF for textural and chemical properties. Catalytic performance tests were performed in a fixed-bed quartz reactor under kinetically controlled conditions for proper catalyst screening. The EDAX measurement results illustrated that the potassium concentration profile changed with drying rate with the catalyst prepared by lower drying rate exhibited highest K concentration at the center as well as highest propylene yield. These were attributed to the retraction of impregnation solution during drying at slow rates which results in lower concentration of acidic sites in catalyst center, thereby reducing the contact time of the propylene product with strong acid sites during reaction.