Carbon nanotubes have become ideal candidates for fabricating nanosized gas sensors because of their excellent mechanical, electrical, physical, and chemical properties, one?dimensional nanostructure, high surface adsorption capability, superior conductive performance, and electronic ballistic transport characteristics. Recently, a great deal of effort has been devoted to the development of carbon nanotube?based gas sensors and rapid progress has been made. The results show that carbon nanotube gas sensors possess unique properties such as high sensitivity, fast response, small size, low energy consumption, and low operating temperature. In this review, we combine the great deal of work carried out by our group and try to summarize research progress in carbon nanotube-based gas sensors for environmental monitoring, medical diagnosis, and military and defense applications. The working mechanisms and manufacturing processes of these sensors are also presented and analyzed. Despite facing enormous challenges, owing to their excellent performance, sensors based on carbon nanotubes will be substitutes for commercially traditional gas sensors.

A coupled computational technique, which combines the one dimensional two-temperature model and molecular dynamics, was used to study the melting dynamics of a nanoscale aluminum film irradiated by a femtosecond laser pulse. The model is capable of providing an atomic-level depiction of fast microscale processes in metals and gives an adequate description of laser light absorption, energy transfer, and fast electron heat conduction in metals. The simulation revealed that the electron temperature, lattice temperature, and laser induced pressure of the Al film were significantly different from those of Ni and Au films. The Al film melts globally soon after laser radiation and this is different from the Ni film, which es through a step melting process. In addition, the Al film shows a much faster melting process than the Ni and Au films because of strong electron-phonon coupling. The melting time of the Al film by an ultrafast laser pulse is consistent with recent experimental observations, which supports the assertion that the laser induced melting of an Al film is a thermal process.

Based on a detailed chemical reaction mechanism, a reduced reaction mechanism with 18 species and 24 steps was used to simulate the supersonic combustion of methane. Heated air calculations showed that seven main vitiated species, i.e., H₂O, CO₂, O, OH, CO, H, and H₂, were present in ethanolfueled heated air. We analyzed the effects of these species on methane-fueled supersonic combustion using chemical kinetics and thermodynamics. H₂O inhibits the combustion process, decreases the combustion efficiency, and decreases the specific thrust. The relatively large molecular weight of CO₂ contributes to an increase in the mean molecular weight of the fuel gas, which is a negative factor in the mechanism of specific thrust. Free radicals O, OH, H can effectively promote the combustion process and thus increase the combustion efficiency. Intermediate products CO and H₂ increase the combustion efficiency, and this is a function of the additional fuel.

Femtosecond time-resolved multiphoton ionization dynamics of xenon was investigated using a homemade ion imaging detector. A comparison experiment comprising of the multiphoton ionization of Xe at 408 nm showed that the energy resolution of our homemade image detector was similar to that of a commercial detector. Under 272 nm femtosecond laser irradiation, photoelectrons with a kinetic energy of 1.57 and 0.26 eV, produced by three-photon ionization, corresponded to two different Xe + spin states, respectively. For the ionization at 408 nm, an additional first-order above-threshold ionization of Xe was also observed. In the two-color femtosecond time-resolved experiments, the photoelectron kinetic energy spectra varied with the delay time between the pump and the probe. The photoelectron intensities produced by 3+1' and 4'+1 two-color multiphoton ionization schedules became stronger with an increase in the degree of overlap between the two laser beams. The kinetic energy of the photoelectrons produced by one-color multiphoton ionization showed obvious red shifts, which were modulated by the second laser beam. Depopulation of the excited states was also observed upon application of the second laser beam. The red shifts in the photoelectron kinetic energy spectra reflect the time-dependent dynamical modulation process of the laser induced ponderomotive effect in an atomic system.

NiW alloys were electrodeposited under a super gravity field. The effects of super gravity on the partial current density, W content, and cell voltage were studied. The surface morphologies of the NiW films were characterized by scanning electron microscopy (SEM). The anti-corrosion properties and stability of the NiW films in NaOH solution were also studied by Tafel, electrochemical impedance spectroscopy (EIS), and 144 h exposure test. The results indicate that the W content increases with the gravity coefficient (G) and no cracks are produced on the surface of the NiW alloys electrodeposited under the super gravity field. Compared with those electrodeposited under normal gravity conditions, the self-corrosion potentials of the NiW alloys electrodeposited under a super gravity field shifts in a positive direction and the self-corrosion current densities become smaller. Meanwhile, the corrosion resistance also increases from 865 to 2305 Ω·cm² with an increase in the G value from 1 to 256. After 144 h exposure in 10% (w) NaOH solution, no surface peeling or damage occur. We conclude that when the NiW alloy is electrodeposited under a super gravity field, both the anti-corrosion resistance and the stability of the NiW alloy in the NaOH solution are improved obviously.

Zinc acetate/polyacrylonitrile nanofibers were prepared by an electrospinning method. The as-prepared nanofibers were carbonized under ar n and washed with acid to obtain porous carbon nanofibers. The surface morphology and microstructure of the porous carbon nanofibers were examined by scanning electron microscopy and X-ray diffraction. The surface area was found to be 413 m²·g^-1 by the Brunauer-Emmett-Teller (BET) method. The electrochemical performance of the electrodes was characterized by cyclic voltammetry and by chronopotentiogram tests. The results showed that the specific capacitance of the as-repapered carbon porous nanofiber electrode was 275 F·g^-1 under 1 A·g^-1, which is 162% higher than that of the carbon nanofibers without a porous structure.

Co-Ni layered double hydroxides (Co_xNi_1-x LDHs) were successfully synthesized by a 5- sulfosalicylic acid (SSA)-assisted hydrothermal process. Structural and morphological characterizations were performed using powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The results reveal that different morphologies of Co_xNi_1-x LDHs could be obtained by tuning the Co/Ni molar ratio. The Co_xNi_1-x LDHs exhibit petal-like nanospheres that are composed of nanoflakes at a Co molar fraction of 0.24. The LDH of this structure has a specific capacitance of 1735 F·g^-1 at a current density of 1 A·g^-1 as determined by cyclic voltammetry and galvanostatic charge-discharge.

Polyaniline/carbon nanofiber (PANI/CNF) composite materials were prepared by in situ polymerization. The functional group, composition, surface morphology, and specific surface area of composite materials were characterized by Fourier transform infrared (FT?IR) spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and Brunauer?Emmelt?Teller analysis. Cyclic voltammetry (CV) and galvanotactic charge?discharge methods were used to study the electrochemical properties of the PANI/ CNF composite materials. Results showed that the composite materials had a rough surface with a burry PANI structure that was uniformly distributed over the CNF. The composite materials, as electrodes, showed od reversibility in redox reactions. The specific capacitance of 44.4%(w) PANI/CNF was 587.1 F·g^-1, the specific energy was 66.1 Wh·kg^-1 at a current density of 100 mA·g^-1, and the specific power was 1014.2 W·kg^-1 at a current density of 800 mA·g^-1. Moreover, the specific capacitance of PANI/CNF only decreased by 28% after 1000 charge?discharge cycles. Therefore, the PANI/CNF composite material is an excellent material for use in supercapacitors because of its high electrical conductivity and large specific capacitance.

Spinel Li₄Ti₅O_l2/TiN was successfully prepared by sol-gel processing using acetylacetone (ACAC) as a chelating ligand and polyethylene glycol (PEG) as a dispersant. The effect of the TiN film on the electrochemical properties of spinel Li₄Ti₅O_l2 for lithium-ion batteries was studied. The Li₄Ti₅O_l2/TiN was analyzed by X-ray photoelectron spectroscopy (XPS). X-ray diffraction (XRD) patterns and scanning electron microscope (SEM) images showed that this anode material with the TiN film was pure spinel Li₄Ti₅O_l2 and was of sub-micron size. The initial specific discharge capacity of the Li₄Ti₅O_l2/TiN is 173.0 mAh·g^-1. When tested at a rate of 0.2C, 1C, 2C, and 5C, it still retained a discharge capacity of 170.6, 147.6, 135.6, and 111.0 mAh·g^-1, respectively, after 10 cycles, indicating that Li₄Ti₅O_l2/TiN had better high-rate performance than that without the TiN film. The positive effect of the TiN film on lithium-ion batteries was also demonstrated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS).

A platinum-decorated Ru/C catalyst with high platinum utilization efficiency, high performance, and high poisoning tolerance was prepared using a two-stage impregnation reduction method. We found that for anodic methanol oxidation the catalyst activity in terms of the Pt load was 1.9 and 1.5 times as that of Pt/C and PtRu/C alloy catalysts, respectively. These values are also higher than that of the commercial JM PtRu/C catalyst. The electrochemically active surface area of Ru@Pt/C was found to be 1.6 and 1.3 times as those of Pt/C and PtRu/C alloy catalysts, respectively. Furthermore, we found that the ratio of the forward peak current density (I_f) to the backward peak current density (I_b) reached 2.4, which was 2.7 times as that of the Pt/C catalyst. This implies that the Pt-decorated Ru/C catalyst possesses a high tolerance for the intermediate poisoning species. In addition, the stability of Ru@Pt/C was higher than that of Pt/C, PtRu/ C alloy and JM PtRu/C. The catalyst was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The core-shell structure of the catalyst was determined by XRD and TEM. The high performance and high poisoning tolerance of Ru@Pt/C during the anodic oxidation of methanol make it a promising electrocatalyst for direct methanol fuel cells.

We investigated the effect of HClO₄, NH₄ClO₄, and NaClO₄ electrolytes on the electrocatalytic performance of a Pd/C catalyst electrode for formic acid oxidation. The Pd/C catalyst was characterized by X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). The performance of the Pd/C catalyst electrode during formic acid oxidation in different electrolytes was measured using electrochemical methods. We found that the electrocatalytic activity and stability of the Pd/C catalyst electrode for formic acid oxidation decreased in the following order: NH₄ClO₄ > NaClO₄ > HClO₄. The difference in pH between the different electrolytes was small because of the presence of formic acid. Therefore, the electrolyte pH has a small effect and the cations have a large effect. The better performance of the NaClO₄ electrolyte compared to the HClO₄ electrolyte is due to a pH effect. The better performance of the NH₄ClO₄ electrolyte compared to the NaClO₄ electrolyte is due to NH₄⁺ decreasing the adsorption strength and amount of CO on the Pd/C catalyst. This finding has large significance for the increase in the performance of the direct formic acid fuel cell (DFAFC).

The microbiologically influenced corrosion and electrochemical behavior of Q235 steel were investigated in the presence of pseudomonas and iron bacteria using the weight loss method, electrochemical impedance spectroscopy (EIS), and surface analysis method. The results showed that the corrosion of Q235 steel was evidently prohibited in the presence of the two bacterial species. Q235 steel immersed in a mixed culture containing both pseudomonas and iron bacteria showed higher free corrosion potential, lower corrosion current density, and an increase in impedance with immersion time. Scanning electron microscopy (SEM) revealed that a significant corrosion product film formed on the surface of Q235 steel with superior homogeneity and compactness.

A platinum electrode was electrochemically modified with polypyrrole (PPy) in the ionic liquid 1-ethylimidazolium trifluoroacetate (HEImTfa) to produce a modified electrode (PPy-HEImTfa/Pt). Its electrocatalytic performance toward the oxidation of ascorbic acid (0.1 mol·L^-1) was investigated by cyclic voltammetry. Compared with a bare Pt electrode and a PPy-H₂SO₄/Pt electrode, which was prepared in a solution of H₂SO₄, the peak potentials for ascorbic acid oxidation on the PPy-HEImTfa/Pt electrode decreased by 0.19 and 0.10 V, respectively. Additionally, the peak currents increased by 3.6 and 3.0 mA, respectively. Therefore, the electrocatalytic activity of the PPy-HEImTfa/Pt electrode for the oxidation of ascorbic acid was far better than that of the other systems. In situ Fourier transform infrared (In situ FTIR) spectroscopy results showed that the ascorbic acid was firstly oxidized to dehydroascorbic acid on the PPy-HEImTfa/Pt electrode and then underwent a fast hydration reaction to give hydrated dehydroascorbic acid in the aqueous solution. The hydrated dehydroascorbic acid then underwent further hydrolysis to form 2,3-diketogulonic acid by a ring opening reaction. Finally, a part of ascorbic acid was oxidized to CO₂ at high potentials.

A novel strategy for the immobilization of laccase onto a glassy carbon electrode with high stability and electrocatalytic performance is presented. Laccase is attached to a matrix of mixed poly aryl amide (PAA) and multiwalled carbon nanotubes (MWCNTs) (denoted Lac/PAA-MWCNTs/GCE) by covalently bonding the surface amine group of laccase to the terminal carboxyl group of PAA and hydrophobic-hydrophobic interaction between MWCNTs and the laccase. The PAA backbone avoids the detachment and denaturing of the laccase, and the intermixed MWCNTs provide high electronic conductivity. The loading of laccase is 56.0 mg·g^-1 and more than 68% shows electrochemical activity. The electrode delivers direct electron transfer between the redox center of the laccase and the electrode with two pairs of redox peaks at 0.73 and 0.38 V, which is close to the formal potential of the T₁ and T₂ Cu-sites (0.78 and 0.39 V (vs NHE)), respectively. The onset potential for O₂ reduction reaction (ORR) is ca 0.55 V in a phosphate buffer solution (pH=4.4). The Michaelis constant (K_M) of the Lac/PAA-MWCNTs/GEs for O₂ is 55.8 μmol·L^-1 and the detection limit of oxygen reaches 0.57 μmol·L^-1. After 2 months of storage at 4 °C the ORR activity of the Lac/PAA-MWCNTs/GC electrode retains ca 86% of its initial values and the peak potential of the ORR shifts negatively by ca 50 mV. Given the excellent catalytic performance towards ORR and its high stability this strategy will be widely applicable to the development of an enzyme-based cathode for biofuel cells and amperometric biosensors for oxygen.

The binary Cu-selenomethionine (SeMet) complex was investigated using voltammetry and chronocoulometry. A pair of peaks (V, VI) were observed at -132 and 71 mV in the Cu(NO₃)₂ solution. When SeMet and Cu(NO₃)₂ coexisted, four peaks (I, II, III, and IV) were observed at 14, 128, 271, and -194 mV, respectively. From the 600 to -600 mV potential scan, we observed that the Cu(II)-(SeMet)₂ complex was reduced to Cu(I)-SeMet complex at 14 mV and then the Cu(I)-SeMet complex was reduced to Cu(0) and SeMet at -194 mV. After reaching -600 mV the potential was reversed and the reduced product was oxidized to the Cu(I)-SeMet complex at 128 mV and Cu(II)-(SeMet)₂ complex at 271 mV. The Cu(I)-SeMet complex was stable from about -100 to 200 mV and a redox process was observed for Cu(I). The stability constants of the binary Cu-SeMet complex, 2.24×10⁷ (K₁) and 2.24×10⁶ (K₂), were determined by capillary electrophoresis. We proposed the structures of Cu-SeMet complexes: Copper coordinated with SeMet by the formation of Cu—Se and Cu—OCO bonds at pH 3.9 or by the formation of Cu—N and Cu—OCO bonds under physiological conditions.

A photosensitive amphiphilic copolymer P(St/VM-co-MA) was synthesized from styrene (St), a styrene-containing photosensitive monomer 7-(4-vinylbenzyloxy)-4-methyl coumarin (VM), and maleic anhydride (MA) by free radical copolymerization. P(St/VM-co-MA) self-assembled into colloid particles in the selective solvent N,N-dimethylformamide (DMF)/H₂O. The morphologies, sizes, and size distributions of the colloid particles were characterized by transmission electron microscopy (TEM) and dynamic laser scattering (DLS). The P(St/VM-co-MA) colloid particles were photo-crosslinked by the photodimerization of the coumarin groups under UV irradiation to form crosslinked colloid particles. The crosslinking process was monitored using UV-Vis spectroscopy. The sizes and stabilities of the crosslinked and non-crosslinked colloid particles were examined by DLS. Additionally, the emulsification and encapsulation of the colloid particles were studied by laser scanning confocal microscopy (LSCM) and optical microscopy. The results showed that both the crosslinked and non-crosslinked colloid particles possessed emulsifying properties. During emulsification the oil-soluble dye was encapsulated into the emulsion. When the colloid particles were crosslinked, they became smaller and their structural stability as well as emulsification and encapsulation were improved.

Acrylic polymer emulsions were synthesized by semi-continuous seeded emulsion polymerization and the corresponding redispersible polymer powders were prepared by spray drying. Methacrylic acid (MAA) was used as the hydrophilic shell monomer. The influences of the amount of MAA on the average particle size of the original emulsion, the dispersion stability, zeta potential, and size distribution of the redispersion emulsion were investigated. The results show that with an increase in the amount of MAA, the particle size of original emulsion, the dispersion stability, and the zeta potential of the redispersion emulsion increased significantly. The size distribution of the redispersion emulsion with a high amount of MAA was unimodal and similar to the original emulsion indicating excellent water-redispersibility. Transmission electron microscopy (TEM) was used to characterize the internal microtopography of the redispersible polymer powder, and results showed that with a higher amount of MAA, millipores with larger pore sizes were present in the transection of the redispersible polymer powder. When polymer powders are redispersed in an aqueous phase, large micropores provide a more convenient channel for water permeation, which optimizes the redispersibility. The hairy structure and higher zeta potential endow the redispersion emulsion with excellent redispersion stability.

We studied the effect of Pluronic F127 micelle solution on the solubility of ibuprofen (IBU). The critical micelle concentration (cmc) of F127 in both water and 0.01 mol·L^-1 pH 7.4 phosphate buffer salt (PBS) solution at different temperatures was determined by the pyrene fluorescence method. The concentration of the solubilized IBU was determined using high-performance liquid chromatography (HPLC). We calculated the solubility descriptors (molar solubilization capacity, χ, and micelle-water partition coefficient, K). The influences of temperature, medium properties, and additional copolymer F68 on the micellization of F127 and the solubilization of IBU were also investigated. The results showed that the solubility of IBU increased linearly with an increase in the F127 mass fraction. With an increase in temperature, a significant decrease in the cmc was apparent and a less polar microenvironment was present in the micelle core. Slight increases in χ and K were found with an increase in temperature. The cmc of F127 in PBS solution was much less than that in water, χ was essentially the same and K decreased significantly in PBS solution. F127 micelle property and the solubilization capacity of the F127 micelles were only slightly affected in the presence of F68. An analysis of the solubility descriptors indicates that the K is particularly unique for the drug IBU, and the χ is useful in determining the solubility effectiveness of copolymer F127. We also demonstrated that IBU was predominantly in the micelle core and core-corona interface.

An ordered mesoporous carbon -silica nanocomposite was synthesized by the evaporation - induced triconstituent co ?assembly method, wherein a soluble resol polymer was used as an organic precursor, tetraethoxysilane was used as an inorganic precursor, and the triblock copolymer F127 was used as the template. After the removal of silica with HF, ordered mesoporous pure carbon (OMC) was obtained. X-ray diffraction (XRD), N₂ adsorption -desorption isotherms (BET), and transmission electron microscopy (TEM) showed that the OMC product had a highly ordered structure with a large pore size of 6.4 nm, a pore volume of 2.13 cm³·g^-1, and a high surface area of 1330 m²·g^-1. The OMC was subsequently functionalized with ethylenediamine by treatment with nitric acid and thionyl chloride to obtain a functionalized ordered mesoporous carbon (C-NH₂(m)), m is the mass (g) of the added ethylenediamine. Fourier transform infrared (FTIR) spectroscopy showed that the amino group was successfully grafted onto the surface of the OMC. TEM images showed that C-NH₂(m) had a highly ordered mesoporous structure. OMC and C?NH₂(m) were used as adsorbents for the selective adsorption of Cu(II) and Cr(VI) ions from the aqueous solution. C?NH2(9.0) had a higher adsorption capacity for Cu(II) of 495.05 mg·g^-1 versus 213.33 mg·g^-1 for the OMC and a lower adsorption capacity for Cr(VI) of 68.21 mg·g^-1 versus 241.55 mg·g^-1 for the OMC, indicating its significantly favorable potential for the selective adsorption of Cu(II).

Al MCM-41 mesoporous molecular sieves were synthesized by a hydrothermal method at 110 °C using the cationic surfactant cetyltrimethylammonium bromide as a template, sodium silicate as the silicon source, and pseudoboehmite as the aluminum source. The obtained Al MCM-41 molecular sieve was characterized by X-ray powder diffraction (XRD), N₂ adsorption-desorption, solid-state ²⁹Si, ²⁷Al magic angle spinning nuclear magnetic resonance (MAS NMR), scanning electron microscopy (SEM), and pyridine adsorption in Fourier transform infrared (FTIR) spectroscopy. The results showed that the Al MCM-41 molecular sieves had an ordered hexa nal packed structure, high relative crystallinity, high BET surface area, large pore volume, and a narrow pore size distribution. Furthermore, strong bonding between the silicon atoms in the Al MCM-41 framework resulted in od crystallization. The presence of the four-coordinate aluminum in the framework resulted in higher acidity.

A series of Ba-Ru/Al₂O₃ catalysts were prepared by the impregnation method using industrial alumina (Al₂O₃-1) and synthesized alumina (Al₂O₃-2) as supports. The catalysts were characterized by X-ray diffraction, N2 adsorption-desorption, X-ray fluorescence spectroscopy, transmission electron microscopy, H₂ temperature-programmed reduction, NH₃ temperature-programmed desorption, and X-ray photoelectron spectroscopy. The effect of Al₂O₃ and the BaO promoter on the phase structure, texture properties, morphology, surface properties, and catalytic activity in ammonia synthesis were investigated. The results indicate that the physical and chemical properties of Al₂O₃ have a strong impact on the structure and activity of the ruthenium catalysts. The BaO promoter has a strong impact on the ruthenium catalyst in two ways: first, the amount of BaO added leads to a difference in the interaction between BaO and γ-Al₂O₃, which further influences the specific area and the porous structure of the catalysts; second, the addition of BaO influences the reduction process and the surface acidity and alkaline properties of the ruthenium catalysts. A proper amount of BaO promotes the activity and the optimal amount of BaO depends on the properties of the supports.

Pt catalysts supported on high specific surface area ZrO₂ were prepared by the impregnation method and applied to the hydrogenation of crotonaldehyde in the gas phase at atmospheric pressure. The effects of Pt loading and reduction temperature on the catalytic properties of the Pt/ZrO₂ catalysts were investigated. It was found that the 3Pt/ZrO₂ catalyst with a mass fraction of 3% Pt and at a reduction temperature of 500 °C exhibited favorable catalytic performance for the selective hydrogenation of crotonaldehyde. The selectivity for crotyl alcohol reached 55% at 27% crotonaldehyde conversion. The catalysts were characterized by X-ray powder diffraction (XRD), CO chemisorption, and NH₃ temperature programmed desorption (NH₃-TPD). The results indicated that the catalytic performance depended on the strong Lewis acidic sites on the catalyst surface and a proper Pt particle size of ca 8 nm for the selective hydrogenation of crotonaldehyde to crotyl alcohol.

CuO/CeO₂-ZrO₂ catalysts were prepared by microwave heating decomposition (one-step approach) and by microwave heating treatment of co-precipitation followed by impregnation (two-step approach). The catalysts were characterized by X-ray diffraction (XRD), low temperature N2 adsorption/ desorption, and H₂-temperature-programmed reduction (H₂-TPR). The catalytic activities of the catalysts for low temperature CO oxidation were investigated using a microreactor-gas chromatograph. The results showed that the one-step approach was more beneficial to CuO dispersion on the catalyst surface because of a strong interaction between CuO and CeO₂-ZrO₂ and to the improved reducibility of CuO, which resulted in higher catalytic activity. We conclude that finely dispersed and small CuO particles strongly interact with CeO₂-ZrO₂ are responsible for the high catalytic activity toward CO oxidation and that large CuO particles that do not interact with CeO₂-ZrO₂ inhibit the catalytic activity.

A series of Cu_xCo_1-x/Al₂O₃/FeCrAl (x=0-1) catalysts were prepared using an FeCrAl alloy as support, a boehmite primer sol as the first washcoat layer and copper as well as cobalt oxides as the active washcoat layer. The structure of the catalysts was characterized using X-ray powder diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and temperatureprogrammed reduction (TPR). Toluene was chosen as the model compound to evaluate the catalytic activity in a conventional fixed-bed quartz reactor. Results indicate that a Cu-Co-O solid solution phase was present when the content of Cu in the catalysts was low and a CuO phase was present when the content of Cu was high. Both Co²⁺ and Co³⁺ were present on the surface of the obtained monolithic catalysts while Cu²⁺ was the main Cu species. The addition of a proper amount of copper oxide improved the reducibility of the cobalt oxide, which enhanced the catalytic activity of the catalysts. All the obtained catalysts showed od activity for the catalytic combustion of toluene. The Cu_0.5Co_0.5/Al₂O₃/FeCrAl catalyst had the best catalytic activity, and toluene was totally oxidized at 374 °C over it.

The catalytic cracking of n-heptane, which was selected as a model compound for the paraffin of light straight-run naphtha, was studied over HZSM-5 catalyst in a fixed-bed microreactor. Its catalytic behavior was compared with that of 1-heptene and the effects of hydrothermal treatment and catalyst carrier were evaluated. The results showed that compared with the cracking of 1-heptene, the concentration of hydrogen, methane, and ethane was much higher in the cracked gas obtained from the cracking of n-heptane. We concluded that this mainly originated from the monomolecular cracking pathway while the content of propylene and butylene in liquefied petroleum gas (LPG) was much lower. Upon hydrothermal treatment, the total amount of acid decreased sharply, especially the strong Brönsted acid (B acid) sites, leading to a steep decline in catalytic activity. This was accompanied by the improved propylene/ propane and butylene/butane molar ratios in the products. Meanwhile, the ratio between the C₃ and C₄ products decreased, suggesting a decrease in the occurrence of monomolecular cracking. The carrier also significantly influenced the cracking behavior of n-heptane. We found that the presence of Lewis acid (L acid) sites in the carrier improved the n-heptane conversion and promoted the bimolecular cracking pathway. Generally, compared with the olefin reactant, paraffin usually shows much lower reactivity and light olefin selectivity and, therefore, it is not a desirable feed for the catalytic cracking reaction over the zeolite catalyst for the purpose of light olefin production.

WO₃ and Bi₁₂SiO₂₀ powders were prepared by a gas-liquid reaction and chemical solution decomposition, respectively. WO₃/Bi₁₂SiO₂₀ photocatalysts were coupled by mixing WO₃ and Bi₁₂SiO₂₀. The reduction of benzene was used to investigate the activity of WO₃/Bi₁₂SiO₂₀. The results indicate that the activity of the coupled WO₃/Bi₁₂SiO₂₀ catalysts increased substantially. The degradation behavior of benzene over 30%(w) WO₃/Bi₁₂SiO₂₀ under UV irradiation was obviously better than that of P-25, and the degradation of benzene under visible light was also considerable. The photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS). The results showed that there was a od synergistic effect between WO₃ and Bi₁₂SiO₂₀. The photogenerated electrons and holes were effectively separated after coupling between WO₃ and Bi₁₂SiO₂₀ and the rate of electron and hole production increased. The electrons and holes were effectively separated and the photocatalytic activity increased accordingly.

The deactivation and regeneration properties of the methanol aromatization catalyst, Ag/ ZSM-5, were investigated by a continuous reaction-catalyst regeneration experiment over four cycles. The activity of the catalyst decreased gradually over the long reaction and was only partly recovered after coke burning. Characterization of the regenerated catalyst by X-ray diffraction (XRD) and transmission electron microscope (TEM) revealed that the ZSM-5 framework remained unchanged and that the sintering of the Ag nanoparticles was not serious. Analyses by Fourier transform Infrared spectroscopy (FTIR) and ammonia-temperature programmed desorption (NH₃-TPD) experiment confirmed that the hydrothermal de-alumination of the catalyst by water in large amounts at 475 °C during aromatization resulted in a significant loss of Brønsted acidity. Consequently, an irreversible decrease in the aromatization ability of the catalyst was apparent.

Novel 3,4-dialkyloxythiophene-based D-A-D organic conjugated molecules di(2-vinyl-3,4- dialkyloxythiophene)-p-2,5-bisphenyl-1,3,4-oxadiazole [(3,4DAOTV)₂-OXD] were obtained using the Wittig reaction. The structure was effectively characterized using hydrogen nuclear magnetic resonance (¹H NMR), Fourier transform infrared (FTIR) spectroscopy, high pressure liquid chromatography (HPLC) and elemental analysis (EA). The optical and electrochemical properties were studied by UV-Vis, fluorescence spectroscopy, and cyclic voltammetry. The UV-Vis maximum absorption of the three studied compounds ranged between 382-383 nm and their optical bandgaps ranged from 2.92 to 2.97 eV. Their emission maxima ranged from 448 to 452 nm with a bright cyan light and their luminescence quantum yields ranged from 36.8%-37.6% in CHCl₃. As solid films, these compounds emit glaucous light at 513-516 nm. The (3, 4DAOTV)₂-OXDs show oxidation and reduction processes in their cyclic voltammograms. Their ionization potentials of 5.65-5.70 eV coincide with the hole transport ability of thiophenes and their electron affinity values of 2.74-2.88 eV are close to the required properties of an electron transport material. These properties will facilitate electron injection and transfer from the cathode. Theoretical calculations indicate that the D-A-D organic conjugation molecule has high coplanarity and that electrons are delocalized along its backbone, which might result in interfacial molecular self-assembly and efficient charge carrier transport as well as efficient quantum yields of devices.

We synthesized a kind of green phosphor, NaBaPOM₄:Tb³⁺, by the high temperature solid-state method, and investigated its luminescent characteristics. NaBaPO₄:Tb³⁺ has several emission peaks, and these are located at 437, 490, 543, 587, and 624 nm, which correspond to the ⁵D₃→⁷D₄ and ⁵D₄→⁷F_{J=6. 5, 4, 3} transitions of Tb³⁺, respectively. The main peak is at 543 nm. The excitation spectrum (monitored at an emission wavelength of 543 nm) consists of several bands, and the main peak is located at 380 nm. The effect of amount of Tb³⁺ doping content, the compensators (Li⁺, Na⁺, K⁺, or Cl^-), and the sensitizer activator Ce³⁺ on the emission intensity of the NaBaPOM₄:Tb³⁺ phosphor were also studied. The results show that the emission intensity can be controlled by the above factors, and the intensity can be enhanced by selecting the prime optimum conditions.

The order of stability for complexes of differently coordinated metal ions (M^+/2+=Na⁺, K⁺, Ca²⁺, Mg²⁺, Zn²⁺) with thirteen guanine isomers in gas (g) and aqueous (a) phases was systematically investigated at the B3LYP/6-311++G^** level in combination with the polarized continuum model (PCM). Special effort was devoted to differences in the order of stability for aGn_xM^+/2+ (n is the label of guanine isomers, x denotes binding site of M^+/2+ and guanine isomers) complexes that were obtained in aqueous solutions. An analysis was also performed to determine the reason for these differences with respect to the solute-solvent effect, binding energy, deformation energy, and relative free energy of the guanine isomers. The most stable complexes generated by the five metal ions were: aG1_N2,N3Na⁺ , aG1_N2,N3K⁺ , aG1_O6,N7Ca²⁺ , aG1_N2,N3Mg²⁺ (aG1_O6,N7Mg²⁺), and aG2_N3,N9Zn²⁺. The isomer of guanine in the most stable Zn²⁺ complex in the aqueous solution was G2 whereas in the other four most stable complexes it was G1, i.e., the different active sites in G1 generate the four most stable complexes. Additionally, we report on stable complexes in the gas phase such as gG3_N1,O6K⁺, gG5_N1,O6K⁺, gG3_N1,O6Ca²⁺/Mg²⁺, and gG4_O6,N7Ca²⁺/Mg²⁺.

The structures and proton transfer processes of hydroxylated A-T base pairs were theoretically studied at the B3LYP/6-31++G(d,p)//B3LYP/6-31G(d,p) level. Our calculations revealed that hydroxyl radical could react with A-T at different positions to form eight stable adducts. The order of these adducts in energy is ^8OHA-T<A-T^6OH<A-T^5OH<^2OHA-T<^4OHA-T<^5OHA-T<A-T^2OH<A-T^4OH (the number denotes the label of the atom in the A/T which is attacked by hydroxyl), which relates well with their structural changes upon the addition of hydroxyl radical. The interaction energy between A and T would increase slightly when hydroxyl radical reacts with the adenine, but it would decrease when the radical reacts with thymine. To study the proton transfer processes of the hydroxylated A-T base pairs, the most stable adducts, ^8OHA-T and A-T6OH, were selected to give calculations. The calculated results indicate that the proton transfer processes of ^8OHA-T and A-T^6OH follow the concerted mechanism, which is different from the stepwise mechanism of A-T. What is more, its energy barrier is lower than the corresponding energy of the latter's first step (rate-determining step).

We systematically studied the heats of formation (HOFs) for a series of 3,3′-azobis-1,2,4, 5-tetrazine derivatives by density functional theory (DFT). The results show that the —N3 group plays a very important role in increasing the HOFs for these derivatives. An analysis of the bond dissociation energies for the weakest bonds indicates that the attachment of —NH2 or —N3 group to 3,3′-azobis-1,2,4, 5-tetrazine is favorable in enhancing its thermal stability. The calculated detonation velocities (D) and pressures (p) indicates that —NO2 or —NF2 largely enhances the detonation performance of the derivatives. Considering the detonation performance and the thermal stability, the three derivatives may be regarded to be promising candidates for high-energy density materials (HEDMs).

We studied the reaction mechanism for the reaction between bis[1,2-di(trifluoromethyl) ethylene-1,2-dithiolato] nickel (Ni[S₂C₂(CF₃)₂]₂) and butadiene by density functional theory (DFT) at the B3LYP/6-31G(d) level. The solvent effect on the charge distribution, dipole moment, and solvation free energies of the stationary points were investigated using the polarizable continuum model (PCM). The calculation results showed that this reaction was orbital symmetry allowed and concerted. The reaction stationary points become more stable with an increase of solvent dielectric constant. Additionally, the degree of stabilization for the transition state and the product is larger than that of the reactants in the same solvent, which means that the reaction occurs more easily.

A total of 1559 molecular descriptors including constitutional, charge distribution, topological, geometrical, and physicochemical descriptors were calculated to encode acetylcholinesterase inhibitors. The 37 molecular descriptors were selected using a hybrid filter/wrapper approach by combining a Fischer Score and Monte Carlo simulated annealing. Classification models for the acetylcholinesterase inhibitors were then built based on support vector machine (SVM), artificial neural networks (ANN), and k ?nearest neighbor (k?NN) methods. For the 515 samples in the training set, we obtained average prediction accuracies of 87.3%-92.7%, 67.0%-81.0%, and 79.4%-88.2% for the positive, the negative, and the total samples, respectively, by 5 ?fold cross validation. Average prediction accuracies of 72.7%-82.5%, 41.0%-53.0%, and 62.1%-69.1% were obtained for the positive, the negative, and the total samples, respectively, by the y?scrambling method, indicating that there was no chance correlation in our models. An external test was conducted on 172 samples that were not used for model building and we obtained prediction accuracies of 93.3%-100.0%, 74.6%-89.6%, and 86.1%-95.9% for the positive, the negative, and the total samples, respectively. The prediction accuracies obtained by all the machine learning methods especially by the SVM method were far better than previously reported results.

We prepared two kinds of CoPt nanorods by galvanic displacement reaction and chemical reduction. One type was solid (CoPt?a) and the other was hollow (CoPt?b). Transmission electron microscopy (TEM) and energy?dispersive X?ray spectroscopy (EDS) were used to characterize the shape and composition of the nanorods. The magnetic properties were measured at 5 and 300 K. The coercivities of the CoPt?a and CoPt?b nanorods were found to be 6.5 and 9.3 A·m^-1 at 5 K, respectively. The coercivities decreased to 0 A·m^-1 when the temperature was increased to 300 K. The field cooling (FC) and zero field cooling (ZFC) curves indicated that both the CoPt?a and CoPt?b nanorods are superparamagnetic. The blocking temperatures (T_B) of CoPt ?a and CoPt ?b are 10.0 and 9.0 K, respectively. The different magnetic properties of the two kinds of CoPt nanorods including coercivity, magnetization, and blocking temperature may be due to their different compositions and structures.

Permanganic potassium was reduced by malic acid under hydrothermal conditions without a template or additives and olive-shaped MnCO₃ particles were obtained. After the MnCO₃ precursor was calcined at 600 °C for 3 h, Mn₂O₃ was obtained and the olive-shape morphology was maintained. The products were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermogravimetry-differential thermal analysis (TG-DTA). The effect of hydrothermal reaction time on the morphology of the products was studied. A MnCO₃ precursor with hollow olive morphology and thick wall was obtained when the reaction time was 2 h. When the reaction time was increased to 6 h, the wall of the hollow olive-shaped particles became thinner. When the reaction time was increased to 24 h the wall thickness of the MnCO₃ precursor with the hollow olive morphology was about 30 nm. Because of the Ostwald-Ripening effect, the morphology of the MnCO₃ precursor gradually evolved from thick-wall hollow olive to thin-wall hollow olive by increasing the reaction time.

Ordered zinc (Zn) nanowire arrays embedded in anodic aluminum oxide (AAO) templates were prepared by an effective electrodeposition method. Oxygen was used to oxidize the electrodeposited zinc nanowire arrays in the AAO templates. By thermal treatment in an oxygen atmosphere at 800 °C for 2 h, the deposited Zn was completely oxidized. The microstructures and optical properties of the synthesized zinc oxide (ZnO) nanowire arrays were investigated by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and photoluminescence (PL) spectrum analytic apparatus. We found that large scale polycrystalline ZnO nanowire arrays were uniformly assembled in the nanochannels of the AAO template. The nanowires have a very high aspect ratio of about 1000:1 with the length equaling the template thickness and a diameter of about 80 nm. PL measurements of the ZnO/AAO assembly showed a strong green emission at 504 nm, which was attributed to the oxygen vacancy defects of the ZnO nanowires. These results can be used in further studies of the structural and functional properties of electroluminescence devices based on the ZnO/AAO assembly.