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A nickel-boron (Ni-B)/graphene composite coatings were produced using chemical reduction method on a steel substrate. These composites were compared to Ni-B coatings without graphene embedded into the matrix. Graphene in the form of an aqueous suspension of graphene oxide flakes was used. Graphene was characterized by single-layered flakes about 0.5 µm in size. The coatings produced were characterized by an amorphous structure. The incorporation of graphene into the Ni-B matrix affects the surface topography and morphology of the coatings produced. The addition of graphene strengthened the coating material. An increase in the hardness (~ 1100 HK0.025) was noted for Ni-B/graphene composite coatings compared to the hardness (~ 950 HK0.025) of the Ni-B coatings without a built-in dispersion phase. Composite coatings also exhibited a better corrosion resistance than the coatings without embedded graphene. [ABSTRACT FROM AUTHOR]

A prior method of mass labeling ketone-/aldehyde-containing species in natural dissolved organic matter (DOM) is further developed and applied. This application involved the treatment of Suwannee River fulvic acid (SRFA) with increasing concentrations of sodium borodeuteride (NaBD4), followed by detection of reduced species via negative mode electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FTICR MS). The extent of reduction, as determined by ESI FTICR MS, resulting from increasing concentrations of NaBD4 correlated well with changes in the absorption and emission spectra of the corresponding untreated and borodeuteride-reduced samples, providing evidence that ketone/aldehyde functional groups contribute substantially to the bulk optical properties of SRFA. Furthermore, the differences in the reactivity and abundance of ketone-/aldehyde-containing species for various regions in Van Krevelen plots were revealed, thus showing how this mass labeling method can be used to provide more detailed structural information about components within complex DOM samples than that provided by the determination and analysis of molecular formulae alone. [ABSTRACT FROM AUTHOR]

The current study aimed to investigate the antibacterial activity of different anisotropic structures of silver nanoparticles in the hexagon and spherical shapes against MDR-bacteria isolated from water sources in Egypt. The water samples collected from four different dairy farm-related sites were tested bacteriologically, followed by identification of the antibiotic-resistant profile for the isolates. The result revealed that Enterococcus spp, Proteus spp, and E. coli spp are the most common organisms in all tested water samples, and the antibiotic-resistant profile identified 11/13 waterborne isolates as MDR-bacteria. Herein, spherical and hexagonal silver nanoparticles were prepared with an average size of 26 ± 6 nm and 375 ± 80 nm, respectively, through the chemical reduction method. Further, MDR gram-positive (Enterococcus) and MDR gram-negative (E. coli) were selected for studying the antibacterial property of the synthesized AgNPs using agar well diffusion method. In another experiment, microdilution broth assay coupled with XTT assay is optimized for facilitating the testing of a broad range of AgNPs concentrations efficiently without the need for laborious preparation of the colony counting method. Our results indicated that AgNPs in spherical and hexagonal shapes are potent antibacterial against the MDR-waterborne bacteria in a dose and shape-dependent manner. The hexagonal AgNPs (h-AgNPs) express higher bactericidal activity when compared to spherical AgNPs (AgNSs) against the two tested MDR-bacteria, but the E. coli isolate more sensitive to both tested shapes of AgNPs than the Enterococus isolate. The results recommend that AgNPs can be used as efficient growth inhibitors for water-borne bacterial pathogens, making them applicable to various water filters and antimicrobial applications. [ABSTRACT FROM AUTHOR]

Cellulose-supported on Pd nanoparticles (Pd/cellulose) were successfully prepared by chemical reduction technique and characterized by various experimental tools. The Pd/cellulose catalyst was found to effectively promote the oxidation of glucose into gluconic acid under mild conditions. The base played a crucial role in the oxidation of glucose into gluconic acid. Glucose was fully converted at room temperature after 3 h by the use of stoichiometric amount of Na2CO3 to neutralize gluconic acid, and gluconic acid was obtained in a high yield of 91.2%. The catalyst was recovered from product and reused up to five times without significant loss in its catalytic activity. [ABSTRACT FROM AUTHOR]

Olive mill wastewater (OMW) is characterized as a high-strength effluent due to the high organic load, low biodegradability, and presence of phytotoxic compounds. Most of the OMW treatment methods proposed, including adsorption, focus mainly on the reduction of chemical oxygen demand and recovery of polyphenols. Adsorption studies aiming at nutrient removal from OMW are very limited. In the present work, Ca(OH)2-treated zeolite (CaT-Z) in a granular form was used for simultaneous recovery of phosphate (PO43−) and potassium (K+) ions from two samples of anaerobically digested OMW. Nutrient adsorption was investigated as a function of contact time, pH and dilution of OMW with deionized water. The lower removal efficiency of phosphorus (P) by CaT-Z was observed at higher dilution ratios consisted of 3.125–6.25% OMW-1 and 5% OMW-2. The maximum P removal was 73.9% in 25% OMW-1 and 85.9% in 10% OMW-2. Potassium removal, as the predominant cation of OMW samples, increased from 17.3 to 46.1% in OMW-1 and from 15.1 to 57.7% in OMW-2 with increasing dilution. The maximum experimental adsorption capacities were 15.8 mg K and 2.14 mg P per gram of CaT-Z. Five sequential treatments of 50% OMW-2 with fresh CaT-Z at each stage ensured a cumulative removal of 87.5% for P and 74.9% for K. Adsorption kinetics were faster for K than for P. The plant-available P was found to be the predominant fraction on the loaded CaT-Z. Electron Probe Micro-analysis confirmed the enhanced content of K and P on the loaded CaT-Z, whereas X-ray mapping revealed the co-distribution of Ca and P. This study demonstrates the potential usage of CaT-Z as an immobilization medium of P and K from anaerobically treated OMW. [ABSTRACT FROM AUTHOR]

In this paper, silicon nanoparticles (Si-NPs) were prepared using silica (SiO2) mineral stone as raw material using magnesium-thermic chemical reduction method. The synthesis process involves extraction of silica (SiO2) powder from the raw material and then Si-NPs was prepared by chemical reduction of silica (SiO2) powder using the magnesium-thermic process. Two processes were done for synthesis: (a) magnesium-thermic reaction and annealing at T = 500 °C, 600 °C and 700 °C at N2 gas and (b) acid washing via HCl and HF. The stoichiometric ratio of Mg/SiO2 = 1:1, 1.5:1, 2:1 and 2.5:1 was also investigated in the chemical reduction conditions. To study the structure and morphology of nanoparticles, X-ray Diffraction (XRD) and Field Emission-Scanning Electron Microscope (FE-SEM) were used. Grown nanoparticles have a polycrystalline structure with spherical form with crystalline size of 20–40 nm. To study the optical band gap of Si-NPs and type of direct or indirect semiconductor, energy gap and absorption behavior of nanoparticles was investigated using the UV–Vis spectroscopy. The indirect band gap and blue shift comparison to bulk was observed at 3.62 eV, 3.47 eV and 3.43 eV for the samples synthesized in the temperatures of T = 500 °C, T = 600 °C and T = 700 °C, respectively. Also, the direct band gap was determined for nanopowders. [ABSTRACT FROM AUTHOR]

Functionalized multiwalled carbon nanotubes (F-MWCNTs)/Co–Ti oxide nanocomposites and neat Co–Ti oxide nanoparticles were synthesized by chemical reduction method. The scanning electron microscopy micrographs show that the bimetallic NPs in F-MWCNTs/Co–Ti are present in dispersed form while the neat Co–Ti nanoparticles were found in agglomerated form. The formation of nanocomposites and neat Co–Ti nanoparticles was also confirmed by energy-dispersive X-ray. Both types of nanocomposites were employed as photocatalyst for the photodegradation of Rhodamine B in aqueous medium under UV light irradiation. The photodegradation study was performed via UV–Vis spectrophotometer. The photodegradation results show that F-MWCNTs/Co–Ti oxide NPs degraded about 93.35% dye within 150 min irradiation time while the neat Co–Ti oxide NPs degraded about 91.76% dye within same irradiation time. The F-MWCNTs/Co–Ti can be easily removed and recycled due to its bulky composite nature as compared to neat Co–Ti oxide NPs. The effect of dye concentration, catalyst dosage, pH of medium and activity of recycled catalyst was also evaluated. [ABSTRACT FROM AUTHOR]

To overcome the problem that ferrous complexes are easily oxidized by O2 and then lose NO binding ability in the chemical absorption-biological reduction (CABR) process, cobalt(II)-histidine [Co(II)His] was proposed as an alternative. To evaluate the applicability of Co(II)His, the effects of CoHis absorbent on the aerobic denitrification by Paracoccus versutus LYM were investigated. Results indicated that His significantly promoted nitrite reduction. The inhibition effects of CoHis absorbent could be substantially alleviated by increasing the initial His/Co2+ to 4 or higher. CoHis with concentrations of 4, 8, 12, 16 and 20 mM presented no distinct effect on nitrite reduction, but slightly inhibited the reduction of nitrate, resulting in longer lag of nitrate reduction, and obviously promoted the growth of strain LYM. In the presence of 5, 10, 15 and 20 mM CoHis absorbent, the main denitrification product was N2 (not less than 95.0%). This study is of significance in verifying the applicability of Co(II)His in the CABR process, and provides a referable CoHis absorbent concentration as 20 mM with an initial His/Co2+ of 4 for the future experiments. [ABSTRACT FROM AUTHOR]

In this work, a series of flower-like Bi/BiOClxBr(1−x) heterojunction photocatalysts have been developed. Bi nanoparticles were grown on the BiOClxBr(1−x) nanosheets via an in situ chemical reduction with the assistance of cetyltrimethylammonium chloride and cetyltrimethylammonium bromide aqueous solution. The in situ growth of Bi nanoparticles on the BiOClxBr(1−x) nanosheets could not only give rise to the optical absorption in the visible region, but also promote the photocatalytic performance of BiOClxBr(1−x). Bi/BiOCl0.8Br0.2 exhibited the highest photocatalytic performance, which could completely degrade RhB in 12 min under the UV light irradiation and 6 min under visible light irradiation, respectively. Moreover, holes and superoxide radicals were verified to be the primarily active species in the photocatalytic process. [ABSTRACT FROM AUTHOR]

China promulgated the Air Pollution Prevention and Control Action Plan (the Action Plan) in 2013 and developed stringent control measures to mitigate fine particulate matter (PM2.5) pollution. Here, we investigated the PM2.5 chemical composition changes over eastern China associated with the Action Plan during 2013–2017 using satellite-based PM2.5 chemical composition data derived using CMAQ simulations and satellite inputs. The PM2.5 concentrations decreased considerably during this time as a result of the reductions in all chemical species in PM2.5. The population-weighted mean concentrations over eastern China decreased from 11.1 to 6.7 μg m-3 for S O 4 2 − , 13.8–13.1 μg m-3 for N O 3 − , 7.4–5.8 μg m-3 for N H 4 + , 9.9–8.4 μg m-3 for OM, 4.6–3.8 μg m-3 for BC and 12.9–9.6 μg m-3 for other species in PM2.5. S O 4 2 − had the largest reduction of 40%, while N O 3 − had the lowest reduction of 5%, resulting in a greater fraction of N O 3 − and a smaller fraction of S O 4 2 − in PM2.5. Among the three key regions, Beijing-Tianjin-Hebei had the largest reduction in PM2.5 and its chemical compositions. The decrease in SO4 2 concentrations was in line with the reduction of SO2 emissions, and the major driver of the SO2 emission reductions was the industrial sector. The decrease in N O 3 − concentrations was limited because the decrease in SO2 emissions and the stable NH3 emissions facilitated the formation of N O 3 − from HNO3, which partially offset the reduction in NOx emissions driven by the power sector. To mitigate PM2.5 pollution more effectively, future efforts are needed to reduce NH3 emissions. [ABSTRACT FROM AUTHOR]

Combustion simulations involve the modeling of chemical kinetics, and due to the complexity of detailed mechanisms, chemistry reduction techniques are necessary. One model reduction strategy is the reaction-diffusion manifold (REDIM) method, and to obtain the REDIM, an evolution equation must be solved till its stationary solution and a gradient estimation is needed, provided e.g. from flamelet solutions with detailed chemistry. In this work, the REDIM technique is applied to simulate methane/air turbulent flames based on a simplified gradient estimation. This strategy uses less information in constructing the REDIM, increasing computational efficiency while reducing computational costs. Validation is performed for non-premixed laminar flames. A RANS/transported-PDF framework for the simulation of turbulent reacting flows is presented and used to validate the proposed model. Results show that the simplified gradient estimation is enough to simulate turbulent flames at moderate Reynolds number, which demonstrates the suitability of REDIM as reduced kinetic model in reactive flows. [ABSTRACT FROM AUTHOR]

The Co1−xNixFe2O4 (x = 0.2, 0.5, 0.8) spinel ferrites were synthesised by sol–gel auto combustion method. The Co1−xNixFe2O4/RGO composites were prepared by in situ chemical reduction method and XRD, FTIR, Raman spectroscopy, SEM, VSM and VNA were investigated for crystalline structure and electromagnetic properties. The crystallite size decreases with addition of RGO in ferrites. Magnetization saturation, coercivity and remnant magnetisation decreases with increase of Ni content in the composite with lowest remnant of 9.41 emu/g for 80% of Ni in Co1−xNixFe2O4/RGO showing ferromagnetic nature. The complex permittivity and complex permeability of the composites were measured at X-band frequency which shows significant change with addition of RGO. The maximum reflection loss of − 19.56 dB at 10.04 GHz with bandwidth (RL < 10 dB) 2.49 GHz was obtained for Co0.2Ni0.8Fe2O4/RGO composite with the thickness of 2 mm. The investigations present easy composite preparation of spinel ferrites with graphene oxide and comparison of electromagnetic studies imply the use of Co0.2Ni0.8Fe2O4/RGO composite as microwave absorber in shielding and communications. [ABSTRACT FROM AUTHOR]

In the presence of semicarbazide hydrochloride (SCH) and traces of AgI, the tetrazolium salt 2,5-diphenyl-3-(1-naphmyl)-2H-tetrazolium chloride (Tetrazolium violet, TV) is reduced in alkaline medium to intensely colored chloroform-extractable 3,5-diphenyl-1-(1-naphthyl)formazan (Tetrazolium violet formazan, TVF). The following experimental parameters have been examined for finding optimal conditions for color development and extraction-spectrophotometric determination of AgI: concentration of reagents, extraction time, volume of the two phases, presence of dissolved oxygen, and light. Under the optimal conditions (cTV = 4.0 × 10−5 mol/dm3, cSCH = 2.4 × 10−3 mol/dm3, cNaOH = 4 × 10−1 mol/dm3, Vaq.phase = 25 cm3, Vchloroform = 4 cm3, extraction time t = 5 min) an isomer of TVF with λmax = 511–512 nm is predominantly extracted. The calibration curve (at 512 nm) is linear in the concentration range of 0.013–0.028 µg cm−3 of AgI. The following ions do not interfere in determination of 0.65 µg of AgI; Li+, Na+, K+, N H 4 + , H 2 P O 4 − , F−, Cl−, S O 4 2 − , B 4 O 7 2 − , R e O 4 − , tartrate, and citrate (5000-fold excess); MgII and EDTA (1000-fold excess); PbII and BaII (500-fold excess); AlIII (300-fold excess); ZnII and CaII (100-fold excess); VV (50-fold excess); HgII, HgI, MoVI and FeIII (25-fold excess); and CuII and WVI (10-fold excess). CrIII interferes in the process at a mass ratio of 1 : 1, however small amount of this cation (1.5-fold excess) can be masked by EDTA. [ABSTRACT FROM AUTHOR]

A magnetic photocatalyst containing TiO2 supported on the composite surface (C/Fe) was prepared from red mud, tar and TiO2 (herein identified as TiO2/C/Fe). Characterization by elementary analysis, X-ray diffraction and scanning electron microscopy confirmed the presence of TiO2, Fe3O4 and carbon in TiO2/C/Fe. TiO2 P25 was used to determine the best conditions (catalyst weight, pH, dissolved oxygen—DO, radiation intensity—I and radiation incidence area—A) in photocatalysis reactions for discoloration of the textile dye Remazol Black (RB, 40 mg L−1). The best observed condition (240 mg TiO2, pH 10, DO 7.6 mg L−1, I = 1.20 mW cm−2 and A = 143 cm2) was applied in order to degrade organic matter in both an actual textile wastewater and a synthetic solution of 40 mg L−1 RB using TiO2/C/Fe. The magnetic photocatalyst showed that the reaction rate constant increased seven times when the best conditions were used for the RB discoloration. In the tests with the textile wastewater, TiO2 and TiO2/C/Fe showed 99 and 46% of discoloration, respectively. Moreover, there was reduction in the chemical oxygen demand, soluble solids and turbidity, which was more efficient than common physicochemical industrial treatments. Thus, TiO2/C/Fe was photoactive and presented magnetic properties. [ABSTRACT FROM AUTHOR]

Two methods for the synthesis of hybrid organic-inorganic nanocomplexes comprising chymotrypsin and silver nanoparticles have been developed based on the chemical reduction of silver nitrate by sodium borohydride. In the first method, the enzyme is added to the reaction mixture simultaneously with other reagents. In the second method, it is added to the reaction mixture at certain intervals after the start of the reduction reaction. Chymotrypsin immobilized on nanocomplexes stabilizes silver nanoparticles. As compared to the native enzyme, the immobilized enzyme prepared by the both methods exhibits an increased proteolytic activity in acidic and strongly alkaline media. At the same time, chymotrypsin immobilized on silver nanoparticles by the second method exhibits the highest level of proteolytic activity. [ABSTRACT FROM AUTHOR]

Catalysis holds a very important and promising place in chemical industry. In a typical chemical transformation, the use of a catalyst reduces the reagent-based waste and enhances the reaction selectivity, thereby minimizing the chances of getting any side product. In the recent years, the introduction of nanotechnology in the field of catalysis has further revolutionized it. It is the extremely small size, shape and remarkably large surface-area-to-volume ratio which sets apart a nanocatalyst from its ordinary bulk form and imparts it unique catalytic properties. In the present work, we report the application of heterogeneous nickel nanoparticles in the synthesis of some biologically important heterocyclic compounds. In brief, we doped titania nanostructures with nitrogen and then used them as a support material for immobilizing nickel nanoparticles onto them. The nanoparticles of nickel were prepared by the chemical reduction of nickel acetate. The catalyst thus prepared, i.e., nickel nanoparticles loaded over nitrogen-doped titania (nickel NPs @N-doped TiO2), was then explored for its catalytic activity toward the synthesis of pyrano[2,3-d]pyrimidines and 1,8-dioxo-octahydroxanthenes. The surface and the elemental composition of the catalyst was studied by SEM–EDX analysis. TEM analysis was done to study the internal morphology and the size of the nanostructures formed. The other studies included TGA, FTIR and XPS which gave information regarding thermal stability, presence of nitrogen in the titania framework and oxidation state of the nickel nanoparticles, respectively. [ABSTRACT FROM AUTHOR]

Today, dendrimers (D) were introduced as a versatile template for the synthesis of nanoparticles (NPs). In this work, the stable silver nanoparticles (AgNPs) is successfully synthesized through the chemical reduction of AgNO3 using NaBH4 as a reducing agent. Synthesis of AgNPs was performed in the presence of different generations of citric acid-based dendrimers (G1, G2 and G3) and hydroxyl-terminated citric acid-based dendrimers (G1-OH, G2-OH and G3-OH). High-resolution transmission electron microscopy, electron diffraction and energy-dispersive X-ray analysis were used to characterize the synthesized AgNPs. UV–Vis results were used for the qualitative study of the synthesized AgNPs properties. With varying the molar ratio of dendrimer/Ag+, generations of dendrimers and the pH of the solution, the size and size distribution of AgNPs could be easily controlled at room temperature. The average diameter of the synthesized AgNPs in the presence of Gn-OH was in the range of 8–20 nm. Results show that G1-OH alkaline medium with 1:1 molar ratio of D/Ag is the optimum condition for the synthesis of AgNPs. All the obtained results from this study showed that controlling the medium conditions allows AgNPs with the desired size to be obtained. [ABSTRACT FROM AUTHOR]

Direct methanol fuel cells are promising electrochemical energy conversion devices. But, more efficient and stable and less expensive catalysts are still required. Here, we successfully synthesized Pt/C and Pt0.5–Ir0.5/C, Pt0.6–Ir0.4/C, Pt0.7–Ir0.3/C, and Pt0.8–Ir0.2/C nanowires by the chemical reduction of the metallic precursors by formic acid and tested them towards methanol electro-oxidation in acidic media. Neither surfactants nor templates were used during the syntheses. The nanowires catalysts were compared with a commercial state-of-art catalyst aiming the observation of the properties improvements derived from both alloying Pt with Ir and morphology change from nanoparticles to nanowires. Well-defined and slightly agglomerated over the carbon nanowires (diameters and lengths of approximately 5 and 20 nm, respectively) were obtained, the fact that is ascribed to the 40 wt% metal loading. In addition, accelerated degradation tests showed that Pt0.6–Ir0.4/C, Pt0.7–Ir0.3/C and Pt0.8–Ir0.2/C catalysts are more stable than commercial Pt/C. All synthesized nanowires catalysts were more active towards methanol electro-oxidation than the commercial Pt/C. The Pt0.5–Ir0.5/C sample shows Pt mass activities 7 times that of commercial Pt/C. However, the Pt0.8–Ir0.2/C catalyst presented the best specific activity (6 times that of commercial Pt/C), have the highest currents in the derivative voltammetry and the oxidation potential shifts negatively 100 mV in comparison with the commercial Pt/C catalyst. Hence, the nanowires developed in this study are indicated as potential promising catalysts and can be applied successfully as direct methanol fuel cell anodes. [ABSTRACT FROM AUTHOR]

The Z-scheme Se/BiVO4 photocatalysts were successfully prepared by chemical reduction and hydrothermal methods. Ethanol had the effect of solubilizing a-Se and insoluble t-Se during aging, which was critical for the rapid growth of t-Se rods. Compared with pure Se rods and BiVO4, the Z-scheme Se/BiVO4 exhibits enhanced photocatalytic activity for rhodamine B (RhB) degradation under visible-light irradiation. The photoluminescence detection technology of terephthalic acid spectra shows that ·OH is the major active radical in the degradation of RhB by Se/BiVO4. Based on the transient photocurrent measurements and band structures, it can be concluded that the Z-scheme structure of Se/BiVO4 not only enhances the photogenerated electrons and holes migration rates but also to provide higher redox ability. With the enhanced photocatalytic performance, Se/BiVO4 can be potentially applied for the environmental remediation. [ABSTRACT FROM AUTHOR]

The agro-environmental policies included in rural development plans are getting increasing importance in European Community strategies. These policies represent the meeting point between demand and supply of positive externalities. The difficulty of assessing real environmental efficiency is one of the elements characterizing agro-environmental measures. This difficulty is related to the identification of suitable parameters for evaluating farms according to their impact on the territory. This impact is mainly related both to chemical inputs and to the territorial characteristics of the farm. Different types of fertilizers, pesticides and herbicides are currently used in production processes; however, the analysis has focused only on nitrates, as they represent the most critical types of chemicals related to soil pollution. A case study is provided by analysis of agro-environmental measures in Tuscany for the reduction of nitrates in organic and integrated farms. Using spatial multicriteria analysis, integrated and organic farms were classified according to their geographical locations and their release of nitrates into the soil. This classification permits the highlighting of farms that make the greatest economic efforts to reduce pollution and therefore it could determine environmental benefits. Considering that the trend of policy strategies is toward a reduction of monetary resources, the classification could help decision makers choose the right allocation of future resources. [ABSTRACT FROM AUTHOR]

The zinc nanoparticle bridged with aminoclay has been synthesized by complexation followed by chemical reduction method. The prepared material has been characterized by various analytical tools. The high-resolution transmission electron microscope image confirms the size of Zn nanoparticle as 2–8 nm. The Zn nanoparticle-bridged aminoclay has been used as a catalyst for the reduction of the mixture of effluents such as hexavalent chromium, p-nitrophenol and fluorescein dye. The apparent rate constant value confirms that the Flur dye exhibited an enhanced value in the mixture of pollutants. The Schiff base formation in chitosan has been carried out in order to prove the catalytic effect of zinc nanoparticle-bridged aminoclay. The experimental results have been carefully analyzed and compared with the literature reports. [ABSTRACT FROM AUTHOR]

Disulfide bonds are critical linkages for maintaining protein structure and enzyme activity. These linkages, however, can limit peptide sequencing efforts by mass spectrometry (MS) and often require chemical reduction and alkylation. Under such conditions, information regarding cysteine connectivity is lost. Online partial disulfide reduction within the electrospray (ESI) source has recently been established as a means to identify complex cysteine linkage patterns in a liquid chromatography-MS experiment without the need for sample pre-treatment. Corona discharge (CD) is invoked as the causative factor of this in-source reduction (ISR); however, evidence remains largely circumstantial. In this study, we demonstrate that instrumental factors—nebulizing gas, ESI capillary material, organic solvent content, ESI spray needle-to-MS distance—all modulate the degree of reduction observed for the single disulfide in oxytocin, further implicating CD in ISR. Rigorous analysis of solution conditions, however, reveals that corona discharge alone can induce only minor disulfide reduction. We establish that CD-ESI of peptide solutions containing formic acid or its conjugate base results in a dramatic increase in disulfide reduction. It is also determined that ISR is exacerbated at low pH for complex peptides containing multiple disulfide bonds and possessing higher-order structure, as well as for a small protein. Overall, our results demonstrate that ESI of formate/formic acid–containing solutions under corona discharge conditions facilitates disulfide ISR, likely by a similar reduction pathway measured in γ-radiolysis studies nearly three decades ago. [ABSTRACT FROM AUTHOR]

Metal nanoparticles are considered intriguing to academic society, due to a wide spectrum of applications in electronics, biomedical engineering, optics, and medicine. In this study, effective methods of decorating cellulose nanofibers (CNFs), deacetylated from cellulose acetate nanofibers, with silver nanoparticles (AgNPs) via ultraviolet radiation and copper nanoparticles (CuNPs) via chemical reduction were reported. The formation of metal nanoparticles was confirmed by scanning electron microscopy and transmission electron microscopy. The sizes and the metal contents of AgNPs incorporated CNFs (Ag/CNFs) were demonstrated to correlate well with the concentrations of immersion solutions; whereas sizes of CuNPs decorated CNFs, denoted as Cu/CNFs, did not change significantly upon the increased concentrations of wetting solutions. Bacterial inhibition zones and the bactericidal efficacy were investigated against both gram-negative and gram-positive bacteria; interestingly, the results revealed superior bactericidal activity against E. coli for Ag/CNFs and better antibacterial properties against B. subtilis for Cu/CNFs. [ABSTRACT FROM AUTHOR]

We propose here a one-pot synthetic approach to prepare sol–gel graphite electrodes containing gold nanoparticles (AuNPs). At variance with the traditional synthesis, in which AuNPs are prepared in advance with respect to the silica matrix, they were here obtained directly inside the sol–gel, during its formation. Two reduction methods, namely chemical and thermal reduction, were used to achieve AuNPs starting from a suitable gold precursor, either consisting of NaAuCl4 or HAuCl4. Different experimental parameters were tested in order to direct the synthesis of the material to the characteristics sought, namely Si/Au molar ratio, graphite (g): silane precursor (mL) ratio, chemical nature of the gold precursor and of the reductant, duration and temperature of thermal treatment. Sol–gel was prepared by means of sonocatalysis, in order to reduce the amount of solvent and time necessary for the hydrolysis step. Composition of the material, as well as shape, size and distribution of AuNPs inside the silica matrix was evaluated by spectroscopic and microscopic techniques. Furthermore, electrochemical tests allowed us to ascertain the good conductivity of the composite material and the electrocatalytic activity of AuNPs with respect to glucose and ascorbic acid oxidation. These tests demonstrated that the electrodes obtained by thermal reduction show the best performance in terms of sensitivity for the detection of these analytes, suggesting the possible application of this composite in the field of amperometric sensing. [ABSTRACT FROM AUTHOR]

In this paper, the TeMo5O16 ternary and MoO3-TeO2 binary compounds were prepared by using the solid-state reaction method and with MoO3-TeO2 oxide precursor solutions. The effect of pH and annealing temperature on the structure especially formation of TeMo5O16 ternary phase and optical properties of nanoparticles have been investigated. Ammonia (NH3) and nitric acid were used to adjust low and high pH, respectively. Synthesis and the formation of TeMo5O16 ternary compound were carried out at two processes: (A) chemical reduction with NaBH4 under nitrogen atmosphere and (B) annealing at temperatures T = 350 °C and 400 °C in air. These two temperatures were chosen because of the proximity to Te's melting point. The results of X-ray diffraction showed that with increasing the annealing temperature, the MoO3-TeO2 binary composition is increased and an additional Te2O5 phase is observed. Also, with decreasing pH, the TeMo5O16 ternary phase is increased. The field emission scanning electron microscope (FE-SEM) images showed that the morphology of the nanoparticles is sphere-like, polyhedral forms, which indicates the presence of particles in different phases. The UV–Vis spectroscopy results showed that the energy gap of nanoparticles is varied in the range of 2.83–2.94 eV. The bonding structure of nano-particle was also studied by FT-IR spectroscopy. Highlights: The TeMo5O16 ternary and MoO3-TeO2 binary compounds were prepared by solid-state reaction method. Effect of pH and annealing temperature on TeMo5O16 ternary phase formation has been investigated. Synthesis and the formation of TeMo5O16 ternary compound were carried out at two processes. With increasing the annealing temperature, the MoO3-TeO2 binary composition is increased. With decreasing pH, the TeMo5O16 ternary phase is increased. [ABSTRACT FROM AUTHOR]

Electrochemical reduction is currently one of promising methods for nitrate removal from water, yet most treatment approaches have problems of high cost and energy consumption. In this work, a low current density was applied in electrochemical reduction of nitrate. Copper-modified titanium (Cu/Ti) electrodes with optimal electrochemical activity and fastest kinetics were firstly screened. Thirty minutes of electrodeposition time and neutral pH were found to have the greatest nitrate reduction rate of 83.14%. To further improve the removal of nitrate, activated carbon (AC) and copper-modified activated carbon (Cu/AC) particles were applied to construct three-dimensional reaction systems, with removal rates of nitrate of 88.72% and 96.05%, respectively. The average conversion rates of nitrate to ammonia nitrogen increased from 15.28% to 42.68% and 62.64% in AC- and Cu/AC-based reaction systems, respectively. Oxidation of Cu(0) on surfaces of Cu/Ti cathode and Cu/AC particles to Cu(I) was revealed by X-ray photoelectron spectroscopy (XPS) and Cu LMM spectra analysis. Besides, results of water chemistry characteristics indicated the conversion of AC to carbonate ion. It could be concluded that enhanced nitrate reduction of Cu/Ti-based reaction system was attributed by Cu particle- and AC-mediated electron transfer. This study provided a reference for low-cost electrochemical reduction of nitrate. [ABSTRACT FROM AUTHOR]

In this work, the Fe60Pt40 nanoparticles were synthesized through the chemical reduction method by using the Fe(CO)5 and the Pt(acac)2 as the metallic precursor. The particle size of the synthesized FePt nanoparticles was controlled by adjusting the reaction conditions involving of the Fe(CO)5-injecting temperature and the soak time of reaction. The structure, morphology, and magnetic properties of the synthesized FePt nanoparticles were characterized by XRD, TEM, and vibrating sample magnetometer (VSM), respectively. The synthesized nanoparticles exhibit uniform size and good dispersity. The magnetization behaviors indicate that the nanoparticles present the core-shell magnetic structure including the ferromagnetic core part and the spin-disorder shell part. There exists a spin pinning effect of the shell part on the core part. The increase of particle size weakens the spin pinning effect. [ABSTRACT FROM AUTHOR]

Nanosized particles of zinc oxide have gained much attention due to several applications which includes bacterial inhibition. Therefore, this work evaluates zinc oxide properties synthesized using reduction (chemical) and bio-reduction (green) processes and their corresponding inhibition potentials. The bio-reduction process was achieved using Amaranthus spinosus at 70°C while the reduction process was initiated in the chemical process using sodium hydroxide. The optical measurement of ZnO was carried out using an UV–Vis spectrophotometer. The structural and morphological properties of the synthesized ZnO were evaluated using Fourier transform infrared spectroscopy, X-ray diffractometry and scanning electron microscopy. The elemental composition was carried out using energy dispersive X-ray spectroscopy. The antimicrobial activity property of the nanoparticles was tested against Pseudomonas aeruginosa, Salmonella typhi and Shigella dysenteriae. The degree of susceptibility of ZnO nanoparticles was higher in the bio-reduction process than chemically synthesized for selected microorganisms. A sustainable pathway for development of bio-antibiotic is presented. [ABSTRACT FROM AUTHOR]

Here we report a simple and cost-effective approach for the electroless plating of platinum onto mesoporous cellulosic structures to obtain catalytically active free-standing hybrid materials. Pt nanoparticles are reduced onto native cellulosic supports through wet chemical reduction of cis-[PtCl2(sty)2] (sty = styrene). The decoration of solid cellulosic films by Pt nanoparticles was followed by Fourier transform infrared spectroscopy, reflectance mode ultraviolet–visible spectroscopy, thermogravimetric analysis, X-ray powder diffraction and scanning electron microscopy. An induction period is observed for the reduction of cis-[PtCl2(sty)2] to spherical Pt nanoparticles onto cellulosic supports, after which the amount of deposited Pt increases rapidly. Upon coating a commercially available cellulose fabric with Pt, the Brunauer–Emmett–Teller surface area increases by a factor of 4. Catalytic properties of obtained materials are examined for two model reactions; the reduction of 4-nitrophenol to 4-aminophenol and the hydrosilylation of styrene with triethylsilane. Catalysis was particularly efficient using previously synthesized mesoporous cellulose nanocrystal films as supports due to their high specific surface area up to 177 m2 g−1. Free-standing Pt-decorated mesoporous cellulose films could be potentially used in catalytic applications for the production of industrially relevant compounds and wastewater treatment. An approach for the electroless plating of platinum onto mesoporous cellulosic structures to obtain catalytically active free-standing hybrid materials is here reported. Obtained materials show a potential application for novel production procedures applied to industrially relevant compounds. [ABSTRACT FROM AUTHOR]

In the present work, silver nanoparticles (AgNPs) synthetized with Cryptocarya alba (Peumo) leaf extract were studied. The fabrication method was fast, low cost, and eco-friendly, and the final properties of AgNPs were determined by experimental parameters, such as AgNO3 and Peumo extract concentrations used. Setting suitable experimental conditions, crystalline AgNPs with apparent spherical forms and average diameter around 3.5 nm were obtained. In addition, the capability of synthesized Peumo-AgNPs to remove methylene blue dye (MB) in aqueous solution as well as their catalytic effectiveness was also investigated. The results showed that green synthesized AgNPs can remove fast and effectively the MB dye from aqueous medium by itself, but better results were found acting like catalyst by using sodium borohydride (NaBH4) in the reaction. In addition, this green nanomaterial can be recycling several times maintaining initial properties for removal of MB. Thus, AgNPs synthetized with Peumo leaf extracts could be an excellent catalyst candidate for degradation of blue methylene dye in chemical industries. [ABSTRACT FROM AUTHOR]

In order to ameliorate the capacitance and energy density of supercapacitors in aqueous electrolytes, nitrogen- and phosphorus-codoped carbon microspheres/reduced graphene oxide nanocomposites are obtained by hydrothermal treatment of graphite oxide and N,P-doped carbon microsphere. The as-prepared nanocomposites display a high specific surface area of 604.3 m2 g−1 and hierarchical pore structure composed of micropores, mesopores, and macropores. N,P-codoped carbon microspheres/reduced graphene oxide are used as electrode materials in the redox electrolyte of H2SO4 and KI aqueous solution, exhibiting a excellent capacitance performance of up to ~ 654 F g−1 at 2 A g−1, corresponding to the energy density of 14.53 Wh kg−1 at power density of 402 W kg−1. Even at a high current of 20 A g−1, the electrode can keep a capacitance of 318 F g−1, showing an energy density of 7 Wh kg−1 at power density of 3984 W kg−1. This study indicates the potential of nitrogen- and phosphorus-codoped carbon microspheres/reduced graphene oxide in high energy density supercapacitor. [ABSTRACT FROM AUTHOR]

This study gold (Au) and gold–platinum (Au–Pt) colloids were synthesized by borohydride reduction method in the presence of poly(N-vinyl-2-pyrrolidone) as a stabilizing agent. Besides, pristine polyaniline (PANI), PANI-Au nanocomposites, and PANI-Au–Pt nanocomposites were prepared. The synthesized nano-composites characterized by UV–Vis, FT-IR, XRD, and HR-TEM with energy dispersive X-ray techniques. Au and Au–Pt NPs were spherical in shape with particle sizes at 8 and 3 nm, respectively. PANI-Au and PANI-Au–Pt nanocomposites were also spherical in shape with particle sizes at 3 and 2 nm, respectively. Pristine PANI, PANI-Au, and PANI-Au–Pt nanocomposites were subjected to antibacterial activity against gram-positive (Bacillus subtilis and Staphylococcus aureus) and gram-negative (Escherichia coli and Vibrio cholerae) bacterial pathogens. PANI-Au–Pt nanocomposite showed significant antibacterial activity (33 ± 1.10 mm dia) against B. subtilis. Besides, the MIC of pristine PANI, PANI-Au, and PANI-Au–Pt nanocomposites were found to be 75, 50 and 25 µg/mL, respectively. Besides, the in vitro anticancer investigations against HepG2 liver cancer cells revealed the highest cytotoxicity for PANI-Au–Pt nanocomposite (21.25 µg/mL) followed by PANI-Au nanocomposite (32 µg/mL) and pristine PANI (49 µg/mL). Overall, the present study showed considerable antibacterial and anticancer activity and suggested their potential use in pharmaceuticals after completing successful clinical trials for safety and affordability. [ABSTRACT FROM AUTHOR]

We have successfully observed Faradaic current in cyclic voltammetry of an amorphous Ge2Sb3.4Te6.2 film with Ag electrodes. The Faradaic current peak was attributed to a non-reversible redox process limited by diffusion of Ag cations. The Ag cations can be generated by anodic dissolution under applied bias voltage or may exist before the voltage application as "ready-made" ions. The cyclic voltammetry demonstrated the existence of ready-made Ag cations. The concentration of the ready-made cations was 0.008 mol/cm3, which was about one-tenth of the cations formed by a voltage sweep at 3.6 V/s, and was about one-hundredth of those formed at 0.3 V/s. [ABSTRACT FROM AUTHOR]

In this paper, silver nanoparticles (Ag NPs) were successfully prepared in situ by chemical pulp fiber (CPF) without any additional reductants. In the green synthesis of Ag NPs, CPF acted as both a weak reductant and a stable carrier. The effect of different synthesis conditions was investigated, and the Ag NP load rate was up to 28.12 wt%. The size of the Ag NPs followed a standard Gaussian distribution, ranging from 10 to 50 nm, and a face-centered cubic structure was identified by XRD and TEM. In addition, the AgNPs/CPF composites exhibited good thermostability below 280 °C according to TG analysis. Owing to the high load rate and large specific surface area of Ag NPs, AgNPs/CPF composites exhibited excellent catalytic performance in the reduction of 4-nitrophenol to 4-aminophenol by NaBH4. The conversion rate was up to 95.91% after recycling 50 times, and the catalyst was easily separated from the reaction system. Based on the advantages of high conversion rate, excellent catalytic activity and reusability, AgNPs/CPF composites hold tremendous potential in eliminating nitrophenol and its derivatives from industrial pollution. [ABSTRACT FROM AUTHOR]

The reduction of Fe and Cu oxides by H2 in the Fe-Cu-O system was investigated by thermogravimetric analysis. The results showed that the reduction process of Fe3O4 can be divided into two stages under nonisothermal conditions: When the temperature is less than 570°C, the reduction reaction is Fe3O4 → Fe; when the temperature is above 570°C, the reduction process is Fe3O4 → FeO → Fe. The fundamental aspects are discussed, as well as the effect of Cu and Cu2O on the reduction behavior of Fe3O4. The ease of reduction in the three systems decreases in the order Fe3O4-Cu > Fe3O4-Cu2O > Fe3O4. The reactions were conducted under nonisothermal conditions within two regimes, viz. less than and greater than 570°C. The combined activation energies corresponding to the reduction of Fe3O4-Cu, Fe3O4-Cu2O, and Fe3O4 within the two regimes were found to be 209 kJ mol−1, 257 kJ mol−1, and 442 kJ mol−1, respectively. [ABSTRACT FROM AUTHOR]

The Hall effect and thermoelectric properties of impurity-doped semiconducting Mg2Sn, fabricated using a process combining chemical reduction and spark plasma sintering, were investigated. A small amount of the oxides, hydroxide, or carbonate of IA, IIIA, IB, IIIB, and VB group elements [Al2O3, Bi2O3, Sb2O3, La(OH)3, Li2CO3, Ag2O, CuO, Ga2O3, In2O3, Na2CO3, or Y2O3] were added to improve the thermoelectric performance of Mg2Sn. X-ray diffraction was used for phase identification, and the patterns revealed that the major phase was cubic Mg2Sn, while the minor phases were orthorhombic and trigonal Mg2Sn, MgO, Sn, and intermetallics obtained by the chemical reduction of the additives. The doping of Bi, Sb, Li, Na, and Ga elements into Mg2Sn was found to significantly affect the carrier transport properties. The maximum values of the dimensionless thermoelectric figure-of-merit (ZT) for the p-type Mg2Sn fabricated using Li2CO3 and Na2O3 were 0.25 at 674 K and 0.11 at 577 K, respectively. However, the ZT values for the n-type Mg2Sn fabricated using Bi2O3 and Sb2O3 were 0.057 at 476 K and 0.058 at 574 K, respectively. [ABSTRACT FROM AUTHOR]

There is an important demand for cheap and efficient photocatalysts for dual functional applications. In the study, we report novel 1D MoO3−x/g-C3N4 composite using ethanol as a reducing agent to introduce oxygen vacancy (Ov). The presence of oxygen vacancy has been confirmed by X-ray photoelectron (XPS), electron spin resonance spectra and redox experiments. Compared with MoO3−x, g-C3N4 and fully oxidized MoO3/g-C3N4, the proposed MoO3−x/g-C3N4 composite exhibited a higher photoactivity, effectively degrading methyl orange in 100 min and completely inactivating Escherichia coli in 15 min under visible light-emitting diode irradiation. Trapping experiments demonstrated that holes (h+) and superoxide radicals (·O2−) were the major active species involved in the photocatalytic process. The enhanced photoactivity was attributed to: (1) broadening of the light absorption range associated with the oxygen vacancy, which also served as electron mediators, facilitating the separation of electron-hole pairs, and (2) the 1D nanostructure of MoO3−x, which increased the lifetime of charge carriers. The results provide evidence of the advantages of the introduction of oxygen vacancy with a view to broadening the applications of this photocatalyst. [ABSTRACT FROM AUTHOR]

The problem of the reduction of chemistry to physics has been traditionally addressed in terms of classical structural chemistry and standard quantum mechanics. In this work, we will study the problem from the perspective of the Quantum Theory of Atoms in Molecules (QTAIM), proposed by Richard Bader in the nineties. The purpose of this article is to unveil the role of QTAIM in the inter-theoretical relations between chemistry and physics. We argue that, although the QTAIM solves two relevant obstacles to reduction by providing a rigorous definition of chemical bond and of atoms in a molecule, it appeals to concepts that are unacceptable in the quantum–mechanical context. Therefore, the QTAIM fails to provide the desired reduction. On the other hand, we will show that the QTAIM is more similar to Bohmian mechanics and that the basic elements of both theories are closely related. [ABSTRACT FROM AUTHOR]

This study investigated the sulfidation and sulfur fixation of jarosite residues during reduction roasting in the presence of carbon. The effects of roasting temperature and carbon dosage were investigated based on thermodynamic calculation. The results indicated that more than 98 pct of zinc contained in the residue was converted into zinc sulfides, and more than 91 pct of sulfur was fixed in the roasted residue. Carbon addition promoted not only the sulfidation of zinc but also the fixation of sulfur, thereby eliminating SO2 emission. The growth of sulfide particles was strongly influenced by roasting temperature. The size of sulfide particles significantly increased when the temperature was above 1173 K (900 °C) because of the formation of a liquid phase during the roasting process. However, high temperature could increase the consumption of carbon powder. [ABSTRACT FROM AUTHOR]

Alkyl phosphate modified graphene oxide (GON-DDP) was successfully synthesized using dodecanol, ethanol amine and self-made graphene oxide (GO) as precursors. The structure and morphology of GON-DDP were characterized by FT-IR, XPS, TG/DSC, SEM and TEM. The characterization results indicate that long alkyl phosphate chains were successfully grafted on GO surface, which guaranteed the dispersibility of GON-DDP in hydroisomerization dewax base oil (VHVI8). Then the tribology properties of GON-DDP as friction reduction and anti-wear additive in VHVI8 were evaluated on four-ball machine and SRV test system. The results show that the friction coefficient and wear scar diameter were reduced by 22.7% and 30.3% compared with bare VHVI8 base oil. Moreover, the non-seizure load of VHVI8 was significantly raised by adding GON-DDP. Finally, the lubrication mechanism was proposed according to Raman analysis on the worn surfaces of steel balls. [ABSTRACT FROM AUTHOR]

Reduced graphene oxide/molybdenum disulfide composites (RGO/MoS2s) with steric structures were directly synthesized via a hydrothermal approach using a redox reaction between MoO3 and thiourea. Such RGO/MoS2s were examined by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The electrochemical performances of RGO/MoS2 hybrid electrodes were then assessed by cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical impedance spectrometry (EIS) in 1 M Na2SO4 aqueous solutions. RGO/MoS2 hybrid materials exhibit a high specific capacitance of 243.4 F/g at 0.5 A/g, a superior cycling stability (92% retention after 2000 cycles at 1 A/g) and a distinctively high coulombic efficiency (near 100% after 2000 cycles) as well. Such excellent electrochemical behaviors could be ascribed to the steric structure of bending MoS2 nanosheets decorated on the surfaces of RGO, which favors facilitating the fast ion diffusion and the high conductivity in pseudocapacitive electrodes. Our findings suggested that the resulting morphologies and electrochemical performances of RGO/MoS2 hybrid materials could be tuned via varying steric structures of pseudocapacitive materials, which may render an alternative strategy to improve the electrochemical performance as supercapacitive electrodes. [ABSTRACT FROM AUTHOR]

Local cathodic polarizations of yttria-stabilized zirconia were carried out with a PtIr probe as the working electrode in a controlled atmosphere high temperature scanning probe microscope to investigate the reduction of zirconia. Impedance spectroscopy was performed at 650 °C during increasing and decreasing polarization, in a range between 0.5 and − 2 V in 9% H2 in N2 saturated with water vapor at room temperature (25 °C). With increased polarization, the impedance spectra changed from a simple suppressed arc at low polarizations into two capacitive arcs separated by an inductive loop and followed by an inductive loop at low frequencies. Areas with high conductance as well as significantly decreased high-frequency resistances resulted from the polarizations and indicate the introduction of electronic conductivity in YSZ. Near the probe|YSZ contacts, areas with very low conductance and accumulation of Si-containing particles were observed, pointing to additional migration of silica impurities towards the probe. [ABSTRACT FROM AUTHOR]

Nickel cobalt bimetallic nanoparticles (NiCo NPs) with different molar ratios were stabilized over three-dimensional nitrogen-doped graphene [3D-(N)G] by a chemical coreduction method. Various spectroscopic and microscopic analysis techniques were employed to characterize the resulting NiCo@3D-(N)G samples. The catalytic activity of as-synthesized material was examined for thermal decomposition of ammonium perchlorate (AP) using differential scanning calorimetry (DSC) and thermogravimetry analysis (TGA). In presence of NiCo@3D-(N)G nanocomposite, the decomposition temperature was decreased by 140.9 °C and the high-temperature decomposition peak of AP disappeared. Also, the total heat release during decomposition of AP was significantly increased to about 1176.6 J g−1. The presented catalyst exhibits an impressive catalytic effect for thermal decomposition of AP, due to its unique properties including porous structure, good dispersion of NiCo NPs over 3D-(N)G, consolidated interaction between 3D-(N)G and NiCo NPs, and synergistic effect between two metals. [ABSTRACT FROM AUTHOR]

Supported ruthenium nanoparticles were prepared through the chemical reduction of aqueous Ru(III) species previously loaded (1 or 5 wt%) onto DD3 kaolin through an ion-exchanged pathway. Resulting nanoporous materials were characterized by XRF, XRD, TEM, EDX, and N2 sorption measurements, and then used as catalysts in the liquid phase aerobic oxidation of benzyl alcohol. Benzaldehyde was obtained as the main product with a 97% yield at 100% alcohol conversion at 100 °C in the presence of Ru-DD3 (5%) using 10 mL/min O2 flow and 10 mol% of tert-butyl hydroperoxide with respect to the substrate. Oxidation tests were more efficient in the case of Ru-DD3 (5%) than with other Ru-based solids such as Ru-HZSM-5 (5%). It was also shown that, in the presence of Ru-DD3 (5%), the aerobic oxidation of benylalcohol in the presence of an amine (aniline) gives rise to the imine instead of the aldehyde through a one-pot oxidation and condensation process. [ABSTRACT FROM AUTHOR]

The synthesis of (6-ethyl-1,6-dihydropyrrolo[3,2-c]carbazol-2-yl)methanol 5 and (6-ethyl-6,11-dihydro-1H-dipyrrolo[3,2-c:2′,3′-g]carbazole-2,10-diyl)dimethanol 6 were achieved via the reduction of methyl pyrrolo carbazole carboxylate 3 and methyl dipyrrolo carbazole carboxylate 4, respectively. The structures of hydroxymethyl-pyrrolocarbazoles 5 and 6 were supported by FT-IR, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, 1H and 13C NMR spectroscopy. The photophysical properties of the targeted compounds 3-6 were investigated by employing absorption and fluorescence spectroscopy in different common organic solvents. Also, the fluorescence lifetime (τF) of the compounds was measured utilizing a time-correlated single-photon counting technique in tetrahydrofuran. Antioxidant activities of compounds 3-6 were determined by employing three different assays, namely DPPH radical scavenging, ABTS cation radical decolarization and cupric reducing antioxidant capacity. The results revealed that the ABTS cationic scavenging activity assay was found to be the most sensitive method for the determination of inhibition values. [ABSTRACT FROM AUTHOR]

Complexes [Co(NH3)6][PdCl4]Cl (I) and [Co(NH3)6]2[PtCl4]3 (II) are synthesized and characterized. Complex I is isolated for the first time. The compositions and structures of the complexes are confirmed by X-ray structure analysis (CIF file CCDC no. 1830657), X-ray diffraction analysis, IR spectroscopy, and elemental analysis. The thermal decomposition of complex I in air gives the three-phase product: Pd (space group Fm3m), PdO (space group P n2), and Co3О4 (space group Fd3m). The two-phase product consisting of metallic platinum Pt (space group Fm3m) and cobalt oxide Co3О4 (Fd3m) is formed as a result of the thermal decomposition of complex II is revealed that the single-phase product (a solid solution based on the noble metal and cobalt) can be obtained by the thermal decomposition of the corresponding binary complexes in a hydrogen flow or by chemical reduction using a solution of N2H4 · HCl. [ABSTRACT FROM AUTHOR]

Nanocomposites based on TiO2 nanotube arrays (TiO2-NTA) have received increasing attention for photoconversion and photocatalytic reactions. Here, TiO2-NTA were prepared by an anodic oxidation process. ZnO and ZnCr2O4 nanoparticles were further anchored on the surface of the pre-synthesized TiO2-NTA to form a ternary ZnO/ZnCr2O4@TiO2-NTA (Zn-Cr-O@TiO2-NTA) nanocomposite by an electrochemical reduction-oxidation strategy. Compared to bare TiO2-NTA, the Zn-Cr-O@TiO2-NTA nanocomposite shows remarkably higher photovoltaic conversion efficiency (nine times greater) under visible light irradiation, and photocatalytic H2 evolution activity (2.8 times greater) under simulated sunlight irradiation, respectively. The construction of ternary nanocomposite is beneficial to enhancing the absorption of simulated sunlight irradiation. Moreover, the Type-II semiconductor heterojunction facilitates separation of electron-hole pairs and interfacial charge transport. As a result, improvement of photoconversion efficiency has been obtained. This work may have fundamental importance to designing complex and efficient photoelectrodes for energy-harvesting applications, including photovoltaic solar cells and water splitting. [ABSTRACT FROM AUTHOR]

Methods for the synthesis of copper nanoparticles in a micellar solution of an anionic surfactant, sodium dodecyl sulfate, are improved by optimizing the molar ratios of the precursor and the reductant, Cu(II): N2H4 of 1 : 4, 1 : 8, 1 : 20, 1 : 40, 1 : 100, and 1 : 150 at a pH of 11.1 and pH values of the reaction medium of 10.9, 11.0, 11.2, and 11.9 at the optimum Cu(II): N2H4 molar ratio of 1 : 150. The effect of increasing the Cu(II) : N2H4 molar ratio on the growth in the absorbance of suspensions of copper nanoparticles is established. The stability of solutions over time is studied using the spectrophotometric analysis of colloidal dispersions of copper nanoparticles obtained at a Cu(II) : N2H4 molar ratio of 1 : 150 and values of pH of 10.9, 11.0, 11.2, and 11.9. The process of the aggregation of copper particles accompanied by a hypsochromic shift of the absorption band of surface plasmon resonance towards larger wavelengths is studied by dynamic light scattering. Scanning electron microscopy has shown that copper particles obtained at a Cu(II) : N2H4 molar ratio of 1 : 150 and pH values of 10.9, 11.0, and 11.2 have a spherical shape with dimensions in the range from 12 to 176 nm. [ABSTRACT FROM AUTHOR]

Hexavalent chromium contamination of groundwater is a worldwide problem caused by anthropogenic and natural processes. We report the rate of Cr(VI) removal by two humic acids (extracted from Miocene age lignite and younger peat soil) in aqueous suspensions across a pH range likely to be encountered in terrestrial environments. Cr(VI) was reduced to Cr(III) in a first-order reaction with respect Cr(VI) concentration, but exhibited a partial order (~ 0.5) with respect to [H+]. This reaction was more rapid with the peat humic acid, where Cr(VI) reduction was observed at all pH values investigated (3.7 ≤ pH ≤ 10.5). 13C NMR and pyrolysis GC-MS spectroscopy indicate that the reaction results in loss of substituted phenolic moieties and hydroxyl groups from the humic acids. X-ray absorption spectroscopy indicated that at all pH values the resulting Cr(III) was associated with the partially degraded humic acid in an inner-sphere adsorption complex. The reaction mechanism is likely to be controlled by ester formation between Cr(VI) and phenolic/hydroxyl moieties, as this initial step is rapid in acidic systems but far less favourable in alkaline conditions. Our findings highlight the potential of humic acid to reduce and remove Cr(VI) from solution in a range of environmental conditions. [ABSTRACT FROM AUTHOR]

Magnetic Fe3O4 assembled on nanoscale zero-valent iron (nZVI) supported on an activated carbon fiber (ACF) to form nanoscale magnetic composites (nZVI-Fe3O4/ACF) for removing Cr(VI) and Cu(II) from aqueous solution through a permeable reactive column was synthesized via an in situ reduction method. The nZVI-Fe3O4/ACF composites and the interaction between nZVI-Fe3O4/ACF and both Cr and Cu ions were characterized by field emission scanning electron microscopy (FESEM) with EDX, TEM, XRD, and XPS. Batch experiments were used to analyze the effects of main factors on Cr(VI) removal and investigate the simultaneous removal of Cr(VI) and Cu(II) through a permeable reactive column. The results indicated that the ACF and Fe3O4 can inhibit the agglomeration and enhance the dispersibility of nZVI, and Fe3O4 and nZVI displayed good synergetic effects. The removal efficiency of Cr(VI) improved with the increase amount of Fe3O4 in the nZVI-Fe3O4/ACF composites. With low initial concentration of Cr(VI) and acidic conditions, ~ 90% of 20.0 mg·L−1 Cr(VI) in the solution was removed after 60 min. The removal of Cr(VI) was also affected by coexisting ions. The removal efficiency of 10.0 mg·L−1 Cu(II) was ~ 100% after 45 min of reaction, and the presence of Cu(II) can accelerate the reduction of Cr(VI). The simultaneous removal mechanisms of Cr(VI) and Cu(II) by the nZVI-Fe3O4/ACF composites also were proposed. [ABSTRACT FROM AUTHOR]