Hydrothermal synthesis and electrochemical sensing properties of copper vanadate nanocrystals with controlled morphologies

Morphology-controlled synthesis of copper vanadate nanocrystals is of great significance in electrochemical sensing applications.A facile hydrothermal process for synthesizing copper vanadate nanocrystals with various morphologies(e.g.,nanoparticles,nanobelts and nanoflowers)was reported.Phase,morphology and electrochemical performance of the as-synthesized copper vanadate nanocrystals were characterized by X-ray diffraction(XRD),scanning electron microscope(SEM)and cyclic-voltammogram(CV)techniques.The results revealed that the morphologies of the Cu3V2O7(OH)2·2H2O(CVOH)nanocrystals could be controlled by changing copper salts,surfactants and pH values.The CVOH samples showed enhanced electrochemical response to ascorbic acid.Comparatively,the CVOH nanobelts had the higher electrochemical sensing performance than those of CVOH nanoparticles and nanoflowers.The CVOH-nanobelts-modified GCEs had a linear relationship between the peak currents in their CVs and ascorbic acid concentration.The CVOH nanocrystals can be used as potential electrochemical active materials for the determination of ascorbic acid.

Effects of Bio-organic Fertilizer with Antagonistic Bacteria against Tobacco Bacterial Wilt on Soil Microbial Communities and Disease Resistance of Tobacco

In this study, the effects of bio-organic fertilizer with antagonistic bacteria against tobacco bacterial wilt on soil microbial communities and disease resist- ance of tobacco were investigated by field experiment. The results showed that the incidence of tobacco bacterial wilt in bio-organic fertilizer treatments （T3 and T4） decreased remarkably among four treatments in the field. Compared with the local conventional fertilization group, the incidence of tobacco bacterial wilt was re- duced by 21.9% and 25.0% in T3 and T4, respectively ; the yield of flue-cured tobacco was improved by 5.7% and 5.3%, respectively ; the proportion of mid- high grade tobacco leaves increased by 2.3% and 2.6%, respectively. After application of bio-organie fertilizer with antagonistic bacteria against tobacco bacterial wilt, rhizosphere soil microbial communities exhibited vast amount and abundant species ; the amount of rhizosphere soil bacteria of infected tobacco plants was im- proved by 218.5% with fewer species. It could be concluded that the application of bio-organic fertilizer with antagonistic bacteria against tobacco bacterial wilt could improve the ecological environment of tobacco field, inhibit the growth of pathogenic bacteria, decrease the incidence of tobacco bacterial wilt, and enhance the quality of flue-cured tobacco. This study laid the foundation for further ecological prevention and control of soil-borne diseases of tobacco.

Thermal Stability and Decomposition Kinetics of Polysuccinimide

The thermal stability and decomposition kinetics of polysuccinimide (PSI) were investigated using analyzer DTG-60 under high purity nitrogen atmosphere at different heating rates (3, 6, 9, 12 K/min). The thermal decomposition mechanism of PSI was determined by Coats-Redfern method. The kinetic parameters such as activation energy (E), pre-exponential factor (A) and reaction order (n) were calculated by Flynn-Wall-Ozawa and Kissinger methods. The results show that the thermal decomposition of PSI under nitrogen atmosphere mainly occurs in the temperature range of 619.15-693.15 K, the reaction order (n) was , the activation energy (E) and pre-exponential factor (A) were obtained to be 106.585 kJ/mol and 4.644 × 109 min-1, the integral and differential forms of the thermal decomposition mechanism of PSI were found to be and , respectively. The results play an important role in understanding the thermodynamic properties of polysuccinimide.

Synthesis,Crystal Structure,and Luminescent Property of One New Quinoxaline-substituted Nitronyl Nitroxide Complex[Ni(acac)_2(NITQ)_2]·2CH_2Cl_2

A new complex, [Ni（acac）2（NITQ）2]-2CH2C12 1 （acac = acetylacetone, NITQ = 2-（2＂-quinoxalinyl）-4,4,5,5-tetramethylimidazoline-l-oxyl-3-oxide）, was synthesized and charac- terized by elemental analysis, IR spectroscopy, UV-Vis absorption spectrum, and single-crystal X-ray diffraction. The crystal belongs to the monoclinic system, space group P21/c with a = 9.6970（19）, b = 20.410（4）, c = 12.166（2） A, β = 93.89（3）°, Mr = 997.43, V= 2402.3（8） A3, Z = 2, Dc = 1.379 g/cm3, F（000） = 1040,μ = 0.684 mm-1, the final R = 0.0423 and wR = 0.1197 for 2884 observed reflections （1 〉 2σ（I））. Compound 1 is found to assume a mononuclear structure, which is further linked into a three-dimensional （3D） supramolecular network by hydrogen-bonding, C1...O weak contact and π...π stacking interactions. Moreover, the luminescent properties of the ligand and compound 1 were further investigated in detail.

Investigation on specific heat capacity and thermal behavior of sodium hydroxyethyl sulfonate

The thermal decomposition process was studied by the TG–DTA analyzer. The results show that the decomposition process of sodium hydroxyethyl sulfonate consisted of three stages: the mass loss for the first, the second and third stages may be about the groups of CH_3CH_2OH, CH_3CHO and SO_2 volatilized, respectively. The decomposition residuum of three stages was analyzed by FT-IR, and the results of FT-IR agreed with the decomposition process predicted by theoretical weight loss. The specific heat capacity of sodium hydroxyethyl sulfonate was determined by differential scanning calorimetry(DSC). The melting temperature and melting enthalpy were obtained to be 465.41 K and 25.69 kJ·mol^(-1), respectively. The molar specific heat capacity of sodium hydroxyethyl sulfonate was determinated from 310.15 K to 365.15 K and expressed as a function of temperature.

Ionic liquid catalyzed solvent-free synthesis of chalcone and its derivatives under mild conditions

An ionic liquid(IL)catalyzed solvent-free process was developed for the direct synthesis of chalcone and its derivatives by using substituted acetophenones and benzaldehydes via aldol reaction under mild conditions.A series of acidic and basic ILs were selected and screened.The influences of cations and reaction conditions on product yield and selectivity were systematically investigated.The[Bmim]OH was identified as the optimal IL,with the highest yield and selectivity reaching up to 96.7% and 100%,respectively.A reaction mechanism-based kinetic model was established and regressed with experimental data,revealing the β-Hydroxylketone dehydrolysis with activation barrier of 37.8 kJ·mol^(-1) was observed as the ratecontrolling step.

Hydrolysis of cellobiose catalyzed by zeolites—the role of acidity and micropore structure

The roles of acidity and micropore structure of zeolite were studied in the hydrolysis of the model oligosaccharide of cellulose–cellobiose. HZSM-5, HY, HMOR and Hβ zeolites were selected as model catalysts for the hydrolysis of cellobiose. The effect of acidity of zeolite, including the strength, type and location, on its catalytic activity was investigated. The strong Br？nsted acid sites located in micropores are the active sites for the hydrolysis of cellobiose to glucose. Meanwhile, the catalytic performance of zeolite is also dependent on the micropore size of zeolite.

Synthesis and Crystal Structure of a Novel 14,20-Annulated Pentacyclic Steroid 17(S)-Methyl-13β-hydroxyl-14(R),20(S)-epoxy-pregn-4-en-3-one

The title compound 17（S）-methyl-13β-hydroxyl-14（R）,20（S）-epoxy-pregn-4-en-3-one was synthesized by an improved tandem reaction, and its structure was determined by IR, NMR, HR MS and X-ray single-crystal diffraction. The crystal belongs to orthorhombic, space group P212121 with a = 10.55248（15）, b = 12.14700（16）, c = 14.56841（18） ？, V = 1867.39（4） ？3, Z = 4, Dc= 1.175 g/cm3, μ= 0.604 mm-1, F（000） = 720, the final R = 0.0400 and w R = 0.1072 for 3610 observed reflections with I 〉 2σ（I）.

Preparation and Characterization of Tri-channel Hollow Fiber Nanofiltration Membrane

Improvement strength is beneficial to the popularization of hollow fiber nanofiltration(NF) membrane.The tri-channel hollow fiber NF membrane was prepared by interfacial polymerization(IP).The high strength tri-channel hollow fiber ultrafiltration(UF) membrane were used as the support membrane,m-phenylenedianline(m-PDA),and polyethylenimine(PEI) were used as aqueous phase monomer,and trimesoyl chloride(TMC) was used as organic phase monomer.Fourier transform infrared spectroscopy(FTIR),scanning electron microscope(SEM),and gas sorption analyzer(GSA) were applied in structural analysis of NF membrane.Polymer FTIR illustrates the IP occurrence between aqueous phase monomer and organic phase monomer.The SEM images of NF membrane show the formation of a thin dense layer on surface of support membrane after IP.The flux(J) of optimal NF membrane is 11.2 L·m-2· h-1 at the 0.35 MPa operating pressure.Its retention(R) for NaCl,Na2SO4,MgCl2,Xylenol orange,and Neutral red is 17.4%,30.2%,16.1%,94.3%,and 51.0%,respectively.The NF membrane is on negative charge and its pore radius distributes between 0.3-2.0 nm.

Measurement and Correlation of Vapor-Liquid Equilibrium of the 1,2-Epoxycyclohexane-Cyclohexanone Binary System at 101.3kPa

Many by-products are generated in the process of oxidizing cyclohexene to produce 1,2-epoxycyclohexane by hydrogen peroxide, including cyclohexanol, cyclohexanone, etc. To obtain high-purity 1,2-epoxycyclohexane, the by-products must be removed through rectification. Refining 1,2-epoxycyclohexane through rectification requires vapor-liquid equilibrium(VLE) data of the related system. Therefore, the VLE data of 1,2-epoxycyclohexane- cyc-lohexanone system were measured at 101.3 kPa using an improved EC-2 VLE still. The thermodynamic consistency of the data was then tested by Herington's method and the rigorous point-to-point method. The results obtained were exemplary. The VLE data were correlated by the Wilson and non-random two-liquid(NRTL) equations, using the error sum squares of the vapor composition as the objective function to obtain the model parameters. The difference between the calculated values and the experimental data is minor, indicating that the VLE data are suitable for engineering design.

Measurement and Correlation of Vapor-Liquid Equilibrium for a Cyclohexene-Cyclohexanol Binary System at 101.3 kPa

Many by-products are generated in the process of oxidizing cyclohexene to produce 1,2-epoxycyclohexane by hydrogen peroxide,including cyclohexanol,cyclohexanone,etc.To obtain high-purity 1,2-epoxycyclohexane, the by-products and unreacted cyclohexene must be removed through rectification,in which the vapor-liquid equilibrium(VLE)data of the system are needed.In this study,the VLE data of cyclohexene-cyclohexanol system were studied at 101.3 kPa using an improved EC-2 VLE still.The thermodynamic consistency of the data was examined by Herington's method.The results obtained were exemplary.The VLE data were correlated by the Wilson equation. The difference between the calculated values and the experimental data is minor,indicating that the VLE data are suitable for engineering design.

Experimental and Numerical Investigation on the Mechanical Behaviors of the Velcro^(■) and Dual-Lock Fasteners

In order to characterize the mechanical behaviors of the Velcro~? and Dual-lock fasteners, a series of tests including the butt-joint(BJ) monotonic tensile and shear, mixed tensile-shear with various loading angles, the loading rates effects, the double cantilever beam(DCB) fracture and 180° peel experiments were performed. The tensile and shear tests results showed that the mechanical behaviors of Velcro~? fastener separation are analogous to ductile materials, and those of Dual-lock fasteners are more like brittle ones. The mixed tensile-shear with various loading angles tests results demonstrated that magnitudes of the peak stresses in 30°, 45°, and 60° have no significant differences, which are lower than those in the monotonic tensile or shear tests for the two fasteners. The effects of the loading rate tests show that the peak stresses of the Velcro~? fastener manifested good performance at the loading rate of 10 to 20 mm/min in the tensile and shear conditions, and the Dual-lock did it well around the loading rates of 10 to 20 mm/min in the tensile condition. The cohesive zone model(CZM) is employed to numerical predict the DCB fracture and the 180° peel tests. The CZM predictions results are proven to commendably capture the two tests separation processes, of the tow fasteners, and the numerical results agreed well with the peeling tests data of the Dual lock fasteners. The results and discussions in this study are expected to bring more understanding to engineers and designers about the performance of Velcro~? and Dual lock fasteners.

Determination and Correlation of Solubility for D-Xylose in Volatile Fatty Acid Solvents

The solubility of D-xylose in formic acid and binary solvents of formic acid with formic acid and acetic acid, propionic acid, n-butyric acid or isobutyric acid was measured in the temperature range from 300.35 to 325.05 K using the synthetic method by a laser monitoring technique at atmospheric pressure. The solid-liquid equilibrium data will provide essential support for industrial design and further theoretical study. The experimental data show that the solubility of D-xylose in formic acid and in the mixtures of formic acid + acetic acid(1︰1), formic acid + propionic acid(1︰1), formic acid + n-butyric acid(1︰1), and formic acid + isobutyric acid(1︰1) increases with temperature. The Apelblat equation, the λh model, and the ideal solution equation correlate the solubility data well.

Synthesis and characterization of a ladder-like structure compound formed by cadmium (II) and anionic nitronyl nitroxide

A ladder-like structure compound formed by cadmium (II) and anionic nitronyl nitroxide, [Cd2(NITpBA)4(H2O)4] (where NITpBA = 2-(4-carboxyphenyl)4,4,5,5-tetramethyl-4,5-dihydro-imidazol-1-oxyl-3-oxide), has been synthesized and characterized. X-ray analysis reveals that the compound 1 crystallizes in the monoclinic P21/c (No. 14) space group, and [Cd2(NITpBA)4(H2O)4] units are linked into infinite chains by radical bridging ligands.

Synthesis, structures, and properties of two new binuclear complexes based on carboxyl-substituted nitronyl nitroxide: [M₂(NITpBA)₄(H₂O)₂] (M = Zn and Cu)

Two new binuclear complexes, [M2(μ-NITpBA)4(H2O)2] (M = Zn 1 and Cu 2) [where NIpBA =?2-(4-carboxyl-phenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-1-oxyl-3-oxide], were stylized and characterized. Magnetic susceptibility measurements revealed antiferromagnetic exchange interactions in two complexes.

Investigation on molar heat capacity, standard molar enthalpy of combustion for guaiacol and acetyl guaiacol ester

The molar heat capacities(C_p) of guaiacol(CAS 90-50-1) and acetyl guaiacol ester(AGE, CAS 613-70-7) were determinated from 290 K to 350 K by differential scanning calorimetry(DSC), and expressed as a function of temperature. Two kinds of group contribution models were used to estimate the molar heat capacities of both guaiacol and AGE, the average relative deviation is less than 10%. The standard molar enthalpies of combustion of guaiacol and AGE were- 3590.0 k J·mol^(-1)and- 4522.1 k J·mol^(-1) by a precise thermal isolation Oxygen Bomb Calorimeter. The standard molar enthalpies of formation of guaiacol and AGE in a liquid state at298.15 K were calculated to be- 307.95 k J·mol^(-1) and- 448.72 k J·mol^(-1), respectively, based on the standard molar enthalpies of combustion. The thermodynamic properties are useful for exploiting the new synthesis method, engineering design and industry production of AGE using guaiacol as a raw material.

Promotional effects of Sb on Pd-based catalysts for the direct synthesis of hydrogen peroxide at ambient pressure

TiO2‐supported Pd‐Sb bimetallic catalysts were prepared and evaluated for the direct synthesis of H2O2 at ambient pressure.The addition of Sb to Pd significantly enhanced catalytic performance,and a Pd50Sb catalyst showed the greatest selectivity of up to 73%.Sb promoted the dispersion of Pd on TiO2,as evidenced by transmission electron microscopy and X‐ray diffraction.X‐ray photoelectron spectroscopy indicated that the oxidation of Pd was suppressed by Sb.In addition,Sb2O3 layers were formed and partially wrapped the surfaces of Pd catalysts,thus suppressing the activation of H2 and subsequent hydrogenation of H2O2.In situ diffuse reflection infrared Fourier transform spectroscopy for CO adsorption suggested that Sb homogenously located on the surface of Pd‐Sb catalysts and isolated contiguous Pd sites,resulting in the rise of the ratio of Pd monomer sites that are favorable for H2O2 formation.As a result,the Sb modified Pd surfaces significantly enhanced the non‐dissociative activation of O2 and H2O2 selectivity.

Efficient one-pot synthesis of n-butyl levulinate from carbohydrates catalyzed by Fe_2(SO_4)_3

Butyl levulinate（BL） is a promising new candidate as diesel fuel and fuel additive. In this study, an efficient process for a one-pot synthesis of BL from biomass-derived carbohydrates in butanol medium with the catalysis of metal sulfates was developed. The catalytic activity of a series of metal sulfates for the synthesis of BL from fructose was investigated. Among various metal sulfates, ferric sulfate Fe（SO）was found to be the most efficient catalyst, which gave a remarkably high BL yield of 62.8 mol% under the conditions of 463 K, 3 h, a catalyst dosage of 5.0 g/L, and fructose concentration of 25 g/L. Different carbohydrates including glucose, cellulose, inulin and sucrose were also used for one-pot synthesis of BL with the catalysis of Fe（SO）, showing the yields of 39.6, 30.5, 56.6 and 50.1 mol%, respectively. In addition,the recycling and reuse of Fe（SO）was studied by characterizing them using powder X-ray diffraction（XRD）, scanning electron microscope（SEM）, X-ray photoelectron spectroscopy（XPS）. A plausible reaction pathway for the one-pot synthesis of BL from fructose was proposed. This study provides a facile and feasible way for the synthesis of BL from biomass.

In-situ synthesis of interconnected SWCNT/OMC framework on silicon nanoparticles for high performance lithium-ion batteries

In spite of silicon has a superior theoretical capacity, the large volume expansion of Si anodes during Li^+ insertion/extraction is the bottle neck that results in fast capacity fading and poor cycling performance. In this paper, we report a silicon, single-walled carbon nanotube, and ordered mesoporous carbon nanocomposite synthesized by an evaporation-induced self-assembly process, in which silicon nanoparticles and single-walled carbon nanotubes were added into the phenolic resol with F-127 for co-condensation. The ordered mesoporous carbon matrix and single-walled carbon nanotubes network could effectively accommodate the volume change of silicon nanoparticles, and the ordered mesoporous structure could also provide efficient channels for the fast transport of Li-ions. As a consequence, this hybrid material exhibits a reversible capacity of 861 mAh g^(-1) after 150 cycles at a current density of 400 mAg^(-1). It achieves significant improvement in the electrochemical performance when compared with the raw materials and Si nanoparticle anodes.

Synthesis of propylene glycol ethers from propylene oxide catalyzed by environmentally friendly ionic liquids

A series of acetate ionic liquids were synthesized using a typical two‐step method.The ionic liquids were used as environmentally benign catalysts in the production of propylene glycol ethers from propylene oxide and alcohols under mild conditions.The basic strengths of the ionic liquids were evaluated by determination of their Hammett functions,obtained using ultraviolet‐visible spectroscopy,and the relationship between their catalytic activities and basicities was established.The catalytic efficiencies of the ionic liquids were higher than that of the traditional basic catalyst NaOH.This can be attributed to the involvement of a novel reaction mechanism when these ionic liquids are used.A possible electrophilic‐nucleophilic dual activation mechanism was proposed and confirmed using electrospray ionization quadrupole time‐of‐flight mass spectrometry.In addition,the effects of significant reaction parameters such as concentration of catalyst,molar ratio of alcohol to propylene oxide,reaction temperature,and steric hindrance of the alcohol were investigated in detail.