Electron Microscopy-energy Dispersive X-ray Research Articles

The Victoria and Albert Museum Plaster Casts by the Nineteenth-Century Workshops of the Notre-Dame Cathedral: Scientific Analysis and Conservation

Four nineteenth-century casts of the decoration on the north side of the exterior of the apse of the Notre-Dame Cathedral in Paris are held in the plaster casts collection at the Victoria and Albert Museum in London. The casts were manufactured by two different nineteenth-century workshops, one run by Jean Pouzadoux and the other by Auguste Malzieux. After an assessment of the condition of the casts, a scientific analysis allowed the characterization of the manufacturing materials and subsequent conservation treatments aimed at ensuring the stability of the casts and removing dirt and grime from the casts’ surfaces. Optical microscopy of the samples taken from the casts allowed the stratigraphy to be studied, which largely consisted of gypsum plaster and a coating layer (oxidized diterpenic resin or shellac) containing silicon and aluminium partially diffused in the porous substrate. These materials were identified by a range of techniques, including X-ray diffraction, scanning electron microscope–energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and gas chromatography/mass spectrometry. The conservation works returned stability to the panels for redisplay in the galleries and achieved a closer comparative study between the two workshops. The two sets of panels showed numerous differences in manufacturing processes that corresponded to their observed deterioration.

EPR Analysis of Cu2+ ion Doped Potassium borodicitrate Single Crystal

In our present investigation single crystals of Potassium borodicitrate (KBDC) (for a fixed content- host lattice) with Cu2+, a guest species, as a dopant (at four 0.2, 0.5, 1 and 2 g) in weight ratio have been synthesized at room temperature by using slow evaporation method. These as-synthesized 4 crystals have been subjected to Electron Paramagnetic Resonance (EPR) studies. The EPR spectrum shows that 0.5 g dopant KBDC give a 4 equidistant hyperfine lines with the perfect symmetry confirms that the localization of Cu2+, a paramagnetic impurity, within it reveals that the maximum absorption of EPR signals happens at 0.5 g Cu2+ than any other concentrations with reference to 20° in horizontal plane than the normal and vertical recording in the same angular projection. The Spin Hamiltonian calculations are used to obtain spectroscopic field splitting factor g-tensor values, gxx = 2.0421, gyy = 2.1962, gzz = 2.2827 and hyperfine splitting factor A-tensor values Axx = 150, Ayy = 112 and Azz = 134. The K–O bond length associated with directional cosines of gzz tensor reveal that the Cu2+ is located interstitially. This optimized single crystal has furtherance been subjected to Single cystal X-ray diffraction (SXRD), Fourier transform infrared Spectrascopy (FTIR). Scanning electron microscope (SEM) Energy dispersive X-ray analysis (EDAX) and compared with pure KBDC single crystal. The XRD unit cell crystalline parameter variations reveal that there is doping effect of Cu2+ into the host lattice brings forth structural coordination of Cu2+ with KBDC. The FTIR confirms that complexation of host and guest through molecular interactions in the finger print region. The EDAX mapping shows Cu2+ presence in the crystal. HIGHLIGHTS SXRD are taken to confirm that structure of pure KBDC and Cu2+ doped KBDC are same The spin Hamiltonian parameters of KBDC-Cu2+ single crystal are calculated through EPR spectra On analyzing the spectra, it is found that the doped ion site location symmetry is identified as interstitial and experience orthorhombic local field symmetry In addition to the above studies FTIR and EDX confirms the presence of Cu2+ ion GRAPHICAL ABSTRACT

Application of artificial neural network for prediction of fluoride removal efficiency using neutralized activated red mud from aqueous medium in a continuous fixed bed column.

The present research work approaches the removal of fluoride from aqueous medium using neutralized activated red mud (NARM) in a continuous fixed bed column. Artificial neural network (ANN) technique was applied effectively for optimization of the model for the practicability of the removal process. The consequences of various experimental variables, like bed length, adsorbate concentration, experimental time, and adsorbate solution flow rate are studied to know the breakthrough point and saturation times. The highest removal potentiality of NARM was considered to be 3.815mgg-1 of F- in the bed height of 15cm, starting concentration 1ppm, susceptible time 120min, adsorbate solution flow rate 0.5mLmin-1, and constant room temperature, respectively. Bohart-Adams and Thomas models were considered to describe the fixed bed column effect to the bed height and adsorbate concentrations. The experimental data were applied to a back propagation (BP) learning algorithm programme with a four-seven-one architecture model. The artificial neural network model was considered to be functioning correctly as absolute relative percentage error throughout the learning period. Differentiation between the predicted outcomes from ANN model and actual results from experimental analysis affords a high degree of correlation (R2 = 0.998) stipulating that the model was able to predict the adsorption efficiency. Experimented adsorbent materials were characterized using different instrumental analysis that is scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD).

Enhanced durability of round bamboo treated with copper naphthenate under heat-cold impregnation.

Round bamboo has aroused much interest in construction for its mechanical properties, but poor biological durability seriously restricts its application. In order to develop a suitable and effective preservative treatment method for round bamboo, copper naphthenate (CuN) was adopted and impregnated into round bamboo using heat-cold procedure. The distribution and retention of copper naphthenate in round bamboo were studied, and the biological durability represented by the mould and decay resistance were investigated. The results showed that the retention and fixation of copper reached 0.39 kg⋅m-3 and 85.3%, respectively. Scanning electron microscopy-energy dispersive X-ray spectrometry further disclosed an increasing trend in the composition of CuN from the end inward. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy analyses later revealed that CuN could be fixed on bamboo in the form of hydrogen bond or complex reaction. Statistical analysis showed that the increasing concentration of CuN from 0.3% to 0.5% and 0.8% (calculated as Cu2+ content) has significant contribution against Trametes versicolor and Gloeophyllum trabeum in comparison with the untreated bamboo. Meanwhile, when the concentration of treating solution increased to 0.8 wt%, the resisting efficacy for Aspergillus niger, Penicillium citrinum and Trichoderma viride soared as high as 85.9%, 94.8% and 70.3%, respectively.

Using zeolite and Fe3O4@zeolite composites in removal of Reactive Red 120 from wastewater: Isotherm, kinetic, thermodynamic and adsorption behaviors

It is a well-known fact that the release and dispersion of complex organic dyestuffs into the environment adversely affect human health and other living organisms. Due to industrial activities, pollution of water resources, which are vital for living organisms, is one of the most critical environmental problems nowadays. It is essential to remove the pollutants before they are discharged into the environment to eliminate environmental damage. In this study for the removal of Reactive Red 120 (RR120) dyestuff from an aqueous solution, we employed natural zeolite and iron oxide-zeolite (Fe3O4@Z) as adsorbents. The adsorbents were characterized by Fourier transform infrared spectroscopy, X-ray diffractometry, X-ray fluorescence spectrometry, Scanning electron microscopy energy dispersive X-ray spectroscopy, and Brunauer–Emmett–Teller analysis. The effects of parameters such as pH, contact time, and temperature on RR120 adsorption were also investigated. In addition, the adsorption equilibrium was analyzed with kinetic, isotherm, and thermodynamic parameters. It was found that the adsorption of RR120 on natural zeolite and Fe3O4@Z followed the Langmuir and Freundlich isotherm, respectively, and the adsorption process for both adsorbents proceeded spontaneously (ΔG∘ <0) and exothermic (ΔH∘ <0) with a pseudo-second-order kinetic model. Zeolite and Fe3O4@Z adsorption capacities for RR120 were 145.9 and 154.3 mg/g at 20 °C, respectively. It was determined that no significant matrix effect occurs in adsorption with synthetic wastewater prepared to evaluate the potential performance of adsorbents. According to the results obtained, Fe3O4@Z composite was found more effective adsorbent than natural zeolite for RR120 removal.

Analysis of Phase and Energy Band Gap Width of Corncob Carbon-PEG 4000

This study aims to identify and analyze the band gap width of the carbon phase produced from corncobs mixed with PEG-4000 to see the surface area of the corncob carbon phase. First, the characterization test was carried out using Scanning Electron Microscope Energy-Dispersive X-ray (SEM-EDX) spectroscopy to determine the morphology and Ultraviolet–Visible (UV-Vis) spectroscopy to determine the band gap width of corncob carbon. Then, adding Polyethylene Glycol (PEG) 4000 at a specific concentration to develop the potential of corncob carbon. Finally, the corncob-PEG 4000 carbon reduction process was sifted through and tested by UV-Vis spectroscopy, and the energy gap value was 0.954 eV. DOI: 10.17977/um024v7i22022p142

Laser cleaning on severely corroded steel members: Engineering attempt and cleanliness assessment

A highly effective, environmentally friendly, high-power continuous-wave laser (CWL) transmitter was newly developed to remove corrosion products from severely corroded steel structures. In this regard, treatment conditions of dry laser cleaning (DLC) and wet laser cleaning (WLC) of the drench, soak, and rinse methods are adopted, and the cleanliness effect is compared with that of conventional abrasive blasting treatment. The morphologies and chemical compositions of untreated and treated surfaces are analyzed using three-dimensional digital microscopy, laser confocal microscopy, and scanning electron microscopy–energy dispersive X-ray spectrometry. The results show that laser cleaning can efficiently remove corrosion products and salts that severely corrode steel members, as well as prolong the re-corrosion time of the cleaned surfaces. WLC can achieve excellent microscopic cleaning and reduce the effect of high-temperature inputs on the surface via laser irradiation. Further mechanistic analysis indicates that ablation, melting, and evaporation during laser cleaning primarily contribute to the removal of corrosion products and salts. As a result, the WLC drench method yields the best surface cleanliness and is suitable for practical engineering applications. This study provides a basis for maintaining severely corroded structures via laser-cleaning techniques.

Enamel biomineralization under the effects of indomethacin and celecoxib non-steroidal anti-inflammatory drugs

The aim of this study was to explore the effects of nonsteroidal anti-inflammatory drugs on biomineralization of enamel. Sixty C57Bl6 male mice were used, which were assigned into three groups: celecoxib (n = 20) or indomethacin (n = 20) treatment for a period of 28 days or received no medication (control group, n = 20). Visual inspection and microcomputed tomography were used to analyze enamel morphology. Scanning electron microscopy–Energy dispersive X-ray and Knoop microhardness test were used to quantify chemical element content (Ca, P, C, O) and enamel microhardness, respectively. Tissues were collected to investigate the synthesis, activity or nuclear translocation of metalloproteinase-20, transcription factor Runx2, dentin sialoprotein and cyclooxygenase-2 enzyme by means of immunohistochemistry, in situ zymography and indirect immunofluorescence. Treatment with indomethacin and celecoxib reduced the Ca and P content, microhardness and mineral density in enamel. Treatment with nonsteroidal anti-inflammatory drugs caused an accumulation of metalloproteinase-20 and overall increased enzymatic activity in enamel matrix, while the synthesis of the transcription factor Runx2 was inhibited by these drugs. Interestingly, indomethacin inhibited Runx2 translocation to the nucleus whereas celecoxib did not. Those findings show that non-steroidal anti-inflammatory drugs impact the enamel biomineralization and could be involved in the etiology tooth enamel defects if used during the period of tooth formation and mineralization.

Casein phosphopeptide-calcium chelate: Preparation, calcium holding capacity and simulated digestion in vitro

In this work, CPP-Ca chelate was synthesized by chelating casein phosphopeptide (CPP) and calcium and characterized by Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) Energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The antioxidant activity and calcium holding capacity of CPP-Ca were evaluated and its secondary structure transition was monitored during gastrointestinal digestion by in situ Raman spectroscopy. The results demonstrated that calcium chelating rate reached 40 % and calcium ion was bound to CPP mainly through the interaction of carboxyl and amino groups. The result of calcium holding capacity confirmed the formation of calcium phosphate precipitates could be delayed by 10–15 min with increasing CPP concentration. In vitro simulated digestion revealed CPP-Ca exhibited excellent calcium solubility and its secondary structural changes occurred, especially α-helix and β-sheet content. These findings provided significant insights into enhancing bioavailability of calcium supplements and developing of calcium functional foods for human and animals.

Foliar-applied nanoscale zero-valent iron (nZVI) and iron oxide (Fe3O4) induce differential responses in growth, physiology, antioxidative defense and biochemical indices in Leonurus cardiaca L

The impacts of nZVI and iron oxides on growth, physiology and elicitation of bioactive antioxidant metabolites in medicinal aromatic plants must be critically assessed to ensure their safe utilization within the food chain and achieve nutritional gains. The present study investigated and compared the morpho-physiological and biochemical changes of Leonurus cardiaca L. plants as affected by various concentrations (0, 250, 500 and 1000 mg L−1) of nZVI and Fe3O4. The foliar uptake of nZVI was verified through Scanning Electron Microscopy (SEM) images and Energy Dispersive X-ray (EDX) analytical spectra. Plants exposed to nZVI at low concentration showed comparatively monotonic deposition of NPs on the surface of leaves, however, the agglomerate size of nZVI was raised as their doses increased, leading to remarkable changes in anatomical and biochemical traits. 250 mg L−1 nZVI and 500 mg L−1 Fe3O4 significantly (P < 0.05) increased plant dry matter accumulation by 37.8 and 27% over the control, respectively. The treatments of nZVI and Fe3O4 at 250 mg L−1 significantly (P < 0.01) improved chlorophyll a content by 22.4% and 15.3% as compared to the control, and then a rapid decrease (by 14.8% and 4.1%) followed at 1000 mg L−1, respectively. Both nZVI and Fe3O4 at 250 mg L−1 had no significant impact on malondialdehyde (MDA) formation, however, at an exposure of 500–1000 mg L−1, the MDA levels and cellular electrolyte leakage were increased. Although nZVI particles could be utilized by plants and enhanced the synthesis of chlorophylls and secondary metabolites, they appeared to be more toxic than Fe3O4 at 1000 mg L−1. Exposure to nZVI levels showed positive, negative and or neutral impacts on leaf water content compared to control, while no significant difference was observed with Fe3O4 treatments. Soluble sugar, total phenolics and hyperoside content were significantly increased upon optimum concentrations of employed treatments-with 250 mg L−1 nZVI being most superior. Among the extracts, those obtained from plants treated with 250–500 mg L−1 nZVI revealed the strong antioxidant activity in terms of scavenging free radical (DPPH) and chelating ferrous ions. These results suggest that nZVI (at lower concentration) has alternative and additional benefits both as nano-fertilizer and nano-elicitor for biosynthesis of antioxidant metabolites in plants, but at high concentrations is more toxic than Fe3O4.

Gadolinium enrichment in association with the magnetic fraction of fly ash: Real or an illusion?

Gadolinium, and possibly praseodymium, are relatively enriched in the magnetic fractions of Class F fly ashes from Central Appalachian coal sources. Although the enrichment is evident in the inductively coupled plasma–atomic emission spectroscopy (ICP-AES) determinations of the rare earth content, transmission electron microscopy–energy dispersive x-ray spectroscopy (TEM-EDS) examination of the fly ash fails to show the sites of the Gd or Pr. This apparent lack of correlation could be due to the inability of the EDS to detect low concentrations of the rare earth elements definitively; interferences in the analytics, leading to false positives in the chemical analysis; or the overlap of the energies of Gd and/or Pr with more abundant elements, leading to inaccurate negative results.

Efficient environmental recovery of Au(I) from thiosulfate solution on triphenylphosphine-oxide-modified vermiculite

Natural materials that are economical and environmentally benign are being explored as adsorbent bases for recovering Au(I) from thiosulfate solution via an efficient grafted functional group. In this work, natural vermiculite (VE) modified with triphenylphosphine oxide (TPPO) was used to adsorb Au(I) from thiosulfate solution, and it's gold recovery performance and adsorption mechanism. Fourier transform infrared spectroscopy, scanning electron microscopy–energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and nitrogen adsorption were used to characterize the adsorbents. TPPO-modified VE (VE-TPPO) showed improved gold adsorption ability at a pH of approximately 10, thiosulfate concentration of approximately 0.1 mol/L and temperature of approximately 25 °C. More than 95% of Au(I) could be recovered, and the loading capacity of Au on VE-TPPO increased with decreasing adsorption temperature, reaching an amount of 4.22 kg/t after once adsorption. TPPO was adsorbed on vermiculite through cationic-π bonds. Au(I) was adsorbed on VE-TPPO by a ligand-exchange mechanism involving charge transfer between PO groups and Au(I). Moreover, the interaction mechanism between TPPO and Au(I) was further validated by density functional theory calculations. The use of natural materials with low cost and environmental impact can make the process of leaching gold with thiosulfate safer and cleaner.

Petrological, mineralogical, and geochemical compositions of coal in the Ombilin Basin, West Sumatra, Indonesia

Coal deposits have received considerable attention in recent years owing to their by-product waste being a promising alternative source of critical elements. The Ombilin Basin is well known as one of the largest coal-producing basins in Indonesia. This study investigated the petrological, mineralogical, and geochemical compositions of four Eocene coal seams in Ombilin Basin basement rock, and their relevance regarding critical element enrichment. Samples of coal and basement rock from the Ombilin Basin were analyzed using thin- and polished-section scanning electron microscope energy-dispersive X-ray spectroscopy, inductively coupled plasma atomic emission spectroscopy, and inductively coupled plasma mass spectrometry. Coals from the Ombilin Basin are high-volatile bituminous C coals with mean random vitrinite reflectance values of 0.58%–0.66%. Vitrinite content is the most dominant maceral (61.06 vol% mmf), followed by liptinite (24.95 vol% mmf), and inertinite (13.75 vol% mmf). Minerals observed in the coal samples comprised pyrite, quartz, and clay. Pyrite was present as discrete crystals, massive crystals, framboidal pyrite, and cell-filling on other macerals. Both syngenetic and epigenetic pyrite was found in the Ombilin coal. Based on the petrological and mineralogical analyses, basement rock in the Ombilin Basin can be divided into four groups: granodiorite, andesite-basaltic, marble, and meta-sediment. In comparison with World Hard Coal and common Chinese coals, some layers/partings in the coal seams in the Ombilin Basin are enriched in U (37.6 ppm), V (175 ppm), and total rare earth elements and yttrium (REY; 126.15 ppm). REY-bearing minerals in the Ombilin coal samples were attributed to clay and sulfide minerals, while others were found as dispersed and scattered, indicating that REY are organically bound. Inorganic materials in Ombilin coal deposits have mainly intermediate-felsic provenance, are derived from Cretaceous granitoid rocks and andesite intrusions, and have been subjected to freshwater conditions.

Characterization and optimization of eco-friendly cementitious materials based on titanium gypsum, fly ash, and calcium carbide residue

• Cementitious materials was prepared by FA, TG, CCR based on RSM under ambient curing. • The influences of FA, TG, CCR or their interaction on different ages was analyzed. • The transformation behavior of Fe 3+ in FTC system was observed. • The hydration mechanism, environmental performance of FTC materials was investigated. Titanium gypsum (TG), fly ash (FA) and calcium carbide residue (CCR) are harmful industrial by-products that need to be addressed. In this study, TG, FA and CCR were selected to prepare the eco-friendly FA-TG-CCR (FTC) cementitious materials. Respond surface methodology (RSM) was undertaken to optimize and understand the influence of design factors of m(TG/FA), m(CCR/FA) and W/B on compressive strength, and the mechanical properties, microstructure, hydration mechanism and environmental performance of FTC cementitious materials were investigated. The morphology and structure were characterized by X-ray diffraction (XRD), thermogravimetry- differential scanning calorimetry (TG-DSC) and Scanning electron microscopy energy dispersive X-ray (SEM-EDX), the concentration of hazardous elements was determined via inductively coupled plasma optical emission spectrometer (ICP-OES). The results show that the optimal mixture with RSM methodology (m(TG/FA) = 30.80 %, m(CCR/FA) = 27.85 %, W/B = 0.62) reached 18.93 MPa at 28 days of curing, which confirmed via experimental verification. The FTC cementitious materials are mainly consist with C-(A)-S-H, ettringite; the existence of Fe 3+ was disadvantageous to early age strength, however partial Fe 3+ participated in the formation of Fe-ettringite as the curing time increased, which is beneficial to later age strength. The leaching results indicate that the FTC materials can effectively consolidate the heavy metal ions in raw materials, and the leaching concentration of ions all meet the Chinese Standard for Pollution Control on the Landfill Site of Municipal Solid Waste. Therefore, the synergistic of FTC material offers a novel approach to the efficient utilization of original TG and other industrial by-product wastes.

A comparison between TGA, SEM-EDX and Raman spectroscopy to assess PVC plasticizer loss

The migration of DINP and ESO plasticizers from PVC in contact with different wrapping materials was studied during artificial aging by combining three analysis methods. Silk paper, LDPE and PET were selected since these materials are widely used to protect PVC in heritage collections. First, Scanning Electron Microscopy (SEM) images and Energy Dispersive X-ray (EDX) analyses confirmed the presence of a plasticizer film at the surface of aged PVC whatever the wrapping material. Plasticizer loss during aging was then investigated after PVC surface cleaning. The overall loss of plasticizers was determined from Thermogravimetric Analysis (TGA) however it appeared to be skewed by the dehydrochlorination state. EDX analysis allowed to follow the plasticizer loss through the oxygen to carbon ratio although an external contamination was detected for some samples. Raman spectroscopy was the only technique providing the quantification of both ESO and DINP plasticizers across aging time. The combination of the three techniques to study the aging of PVC under different conditions thus highlighted the strengths and limits of each one. Finally, the relative mass loss speed was similar for both plasticizers but strongly dependent on the wrapping material. Whereas silk paper and LDPE slowed down the plasticizer loss, acceleration was evidenced in presence of PET.

Nanostructured PbS-Doped Inorganic Film Synthesized by Sol-Gel Route.

IV-VI semiconductor quantum dots embedded into an inorganic matrix represent nanostructured composite materials with potential application in temperature sensor systems. This study explores the optical, structural, and morphological properties of a novel PbS quantum dots (QDs)-doped inorganic thin film belonging to the Al2O3-SiO2-P2O5 system. The film was synthesized by the sol-gel method, spin coating technique, starting from a precursor solution deposited on a glass substrate in a multilayer process, followed by drying of each deposited layer. Crystalline PbS QDs embedded in the inorganic vitreous host matrix formed a nanocomposite material. Specific investigations such as X-ray diffraction (XRD), optical absorbance in the ultraviolet (UV)-visible (Vis)-near infrared (NIR) domain, NIR luminescence, Raman spectroscopy, scanning electron microscopy–energy dispersive X-ray (SEM-EDX), and atomic force microscopy (AFM) were used to obtain a comprehensive characterization of the deposited film. The dimensions of the PbS nanocrystallite phase were corroborated by XRD, SEM-EDX, and AFM results. The luminescence band from 1400 nm follows the luminescence peak of the precursor solution and that of the dopant solution. The emission of the PbS-doped film in the NIR domain is a premise for potential application in temperature sensing systems.

Consequences of anthropogenic activities and beach dynamics on vertical distribution of microplastics in the mid-intertidal sediments of Donghai Island, China.

Microplastic accumulation and resulting degradation are significant threats to the coastal ecosystems around the world. Baseline information on microplastics and their sources is of great importance for a permanent waste management system. The present study focused on the vertical distribution and characteristics of microplastics in the mid-intertidal zone of Donghai Island, China. At eight locations, sediment samples were collected from surface to a depth of 30 cm at intervals of 5 cm. Overall, we found five different polymer types, and vertical distributions of microplastics varied ranging from 0 to 200 particles/kg, with the mean value of 32.92±41.35 particles/kg. Sediment samples collected from all stations contained microplastics with high contribution of fibres. Intruded microplastic materials recorded in sediment samples at a depth of 30 cm demonstrate that microplastics may be present at depths greater than 30 cm. Scanning electron microscopy-energy dispersive X-ray (SEM-EDAX) analysis revealed presence of common elements in the microplastics surface (silicon, aluminium, magnesium, copper, and calcium). Based on the observations and results from this study, we suggest implementing a robust microplastic removal management program in Donghai Island to avoid serious microplastic intrusion effects on benthos and environmental contamination.

The Influence of Concentration on the Formation of Chemical Bath Deposited Copper Tin Sulphide Thin Films: SEM and EDX Studies

Nanostructured copper tin sulphide films have been deposited on the substrate (soda lime glass) via an economical chemical bath deposition method. The scanning electron microscopy (SEM) technique and energy dispersive X-ray analyzer (EDX) method were employed in this work to study the films’ morphology and composition. The EDX data and SEM images confirmed that the content of elements (sulfur, tin, and copper), the shape, and the grain size strongly depended on the concentration of the precursors during the formation of films. Experimental results revealed that a higher atomic percentage of the element could be observed for the films prepared using a higher concentration of solution during the experiment.

Diagnostic kit based on halloysite nanoclay-ionic liquid nanocomposite modified electrode for electrochemical determination of cancer biomarker

Nucleic acid hybridization is occurred between the selective single-stranded nucleic acid sequence and its target sequence, which is one of the essential procedure for electrochemical detection of nucleic acid. microRNA-21 (miRNA-21) is known as a biomarker in various cancers. The determination of miRNA-21 was attained through by hybridization of inosine substituted miRNA-21 specific DNA probe (Pinosine) with its target miRNA-21. In this study, the surface of pencil graphite electrode (PGE) was firstly modified with halloysite nanoclay-ionic liquid (HNT/IL) nanocomposite. The characterization of surface was performed by Scanning Electron Microscope (SEM) images and Energy Dispersive X-Ray Analysis (EDX) analysis, and the differences at surface modifications were also shown by electrochemical methods with electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). For sensitive and selective determination of miRNA-21, Pinosine and target miRNA concentration, immobilization and hybridization time were optimized by using HNT/IL modified PGE in combination with differential pulse voltammetry (DPV). The detection limit was achieved as 0.17 μg/mL (equals to 23.69 nM) in the linear range of 0.25–2 μg/mL miRNA-21. The selectivity of voltammetric method based on HNT/IL-PGE developed for miRNA-21 was examined in the presence of mismatch (MM) and non-complementary (NC) sequences. Because miRNA-21 is over-expressed in cancer cells, it has been tested in total RNA samples isolated from cancer cell line (breast cancer cell line, MCF-7). In the total RNA samples obtained from MCF-7, the detection limit was calculated as 0.28 μg/mL in the linear range of 1–4 μg/mL. Besides, the healthy cell line (human embryonic kidney cell line, HEK-293) was used as a control group and the results obtained by MCF-7 total RNA samples were compared to the results using HEK-293 total RNA samples in terms of miRNA-21 level.

Highly efficient and stable catalysts-covalent organic framework-supported palladium particles for 4-nitrophenol catalytic hydrogenation

A covalent organic framework (COF) was used as the support of the catalyst in this work in order to obtain an environmentally friendly catalyst with high catalytic performance, selectivity and stability for 4-nitrophenol hydrogenation. Pd tiny particles are fixed in the cavity of COF to obtain Pd/COF catalysts, which has a quite narrow particle size distribution (5.09 ± 1.30 nm). As-prepared Pd/COF catalysts (Pd loading-2.11 wt%) shows excellent catalytic performance (conversion - 99.3%, selectivity >99.0% and turnover frequency (TOF)-989.4 h−1) for 4-nitrophenol hydrogenation under relatively mild reaction conditions of reaction temperature-40 °C and reaction pressure-3.0 MPa H2, and Pd/COF catalysts have high stability. Pd/COF catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope energy-dispersive X-ray spectroscopy (SEM-EDS), transmission electron microscope (TEM), high resolution TEM (HRTEM), Brunauer-Emmett-Teller (BET), scanning TEM energy-dispersive X-ray spectroscopy (STEM-EDS) elemental analysis techniques to prove that the Pd nanoparticles are highly dispersed on the COF. Pd/COF catalysts have good stability and reusability hence with certain industrial application value.