Layered double hydroxides (LDHs) are a class of layered inorganic materials that consist of structurally positively charged layers and exchangeable anions in the interlayer gallery for charge balance. The delamination of LDHs has attracted much attention in the last decade because it is an effective way for exposing the inner surfaces of the host layers. Delaminated nanosheets may be referred to as “macromolecules”, and they have opened nanostructures. They can be used as an ideal model system and as building blocks for various multilayer ultrathin films and functional nanocomposites. In this article, we outline the progress made regarding the delamination of LDHs and pose future challenges.

The dissociation dynamics of vibrational state-selected NO₂⁺(e³B₂) was investigated using threshold photoelectron-photoion coincidence velocity imaging and photoionization by synchrotron radiation. The vibrational resolution threshold photoelectron spectrum of NO₂⁺ (e³B₂) was recorded in the energy range of 18.8-19.2 eV and was consistent with previous measurements. Furthermore, the coincident velocity images of the O⁺ fragments that dissociated from the (0,0,0) and (1,0,0) vibronic levels of NO₂⁺ (e³B₂) showed a multi-ring structure, indicating that O⁺ fragments with different speeds were produced during dissociation as well as corresponding NO molecules with different internal energy distributions. The total kinetic energy released distributions and the angular distributions of O⁺ during dissociation were obtained subsequently from the images. The internal energy distributions of the NO (X²Π) fragments that dissociated from the two vibrational states of NO₂⁺(e³B₂) were very similar and consisted of 3-5 dominant populated vibronic levels. The available energy released from dissociation was found to be almost evenly distributed between the kinetic and internal energies of the fragments and, specifically, a total kinetic energy of 52% and an internal energy of 48% were obtained. In addition, the anisotropy parameter, β, of the O⁺ fragments was about 0.3 and was hardly dependent on the vibrational quantum number of the NO(X²Π) fragment.

The crystallization processes of oilfield brine components from the Nanyishan area at temperature between -18.90 and -30.90 °C were studied by a self-designed refrigeration instrument and the precipitation temperatures of the first and second salts were measured accurately. The concentrations of the major ions (Ca²⁺, Mg²⁺, K⁺, Cl^-, B₂O₃, Na⁺) in the liquid phase of the brine at different temperatures (from -18.90 to -30.90 °C) were determined by chemical analyses. The solids obtained at low temperature were identified and the phase changes of the oilfield brine at temperatures between -10.0 and -30.0 °C were monitored in situ by subzero temperature X-ray powder diffraction. The results show that the first salt (hydrohalite) precipitates at -19.10 °C and the ice and NaCl·2H₂O co-precipitate at -23.55 °C.

The combustion of oxygenated fuel produces more non-regulated pollutants which usually contain oxygen such as aldehydes than the combustion of hydrocarbon fuel. The formation of these oxygenated intermediates may be associated with the release of oxygen from the oxygenated fuel. In this paper, migration pathways of oxygen from several oxygenated fuels were investigated to obtain the formation characteristics of oxygenated intermediates. Major oxygenated intermediates and other intermediates were identified using synchrotron vacuum ultraviolet photoionization mass spectrometry in a dimethyl ether flame, an ethanol flame, and a propane flame. Their mole fractions were also evaluated. The results indicate that the oxygen from oxygenated fuel leads to an easier production of oxygenated intermediates, compared with oxygen from the oxidizer. The major oxygenated intermediate depends on the structure of the oxygenated fuel and was found to be formaldehyde in the dimethyl ether flame, and acetaldehyde in the ethanol flame. However, formaldehyde and acetaldehyde are present in low concentrations while hydrocarbon intermediates, such as ethene, ethyne, and propene, are present in high concentrations in the propane flame.

We present a systematic study using density functional theory (DFT) with the generalized gradient approximation (GGA) method to understand the adsorption and migration of Pt atoms on the γ-Al₂O₃(001) surface. Energetically the most favorable adsorption sites were identified and all these adsorption configurations were found to show substantial structural relaxation. Our calculated adsorption and energy barrier of migration results indicate that the Pt clusters can be stably anchored onto the surface. A significantly higher adsorption energy at the O site is largely attributed to the fact that charge transfer from Pt to O atoms results in positively charged Pt atoms. The repulsion between Pt and Al atoms leads to much weaker bonds. The calculated average adsorption energies were found to be size and shape dependent and in general decrease as the number of Pt atoms increases. The highest energy barrier for Pt atom migration on the γ-Al₂O₃(001) surface is about 0.51 eV. The formation of a metal cluster would be strongly preferred upon high Pt atom loading. Consequently, the evolution of Pt atoms on the γ-Al₂O₃(001) surface is unlikely to be smooth and agglomeration can occur under certain conditions.

Phosphorus modified ZSM-5 (P-ZSM-5) zeolite was investigated using quantum mechanics density functional theory and our own N-layer integrated molecular orbital molecular mechanics method (ONIOM). Extra-framework phosphate and in-framework moieties containing phosphorus were found to be plausible local structures in P-ZSM-5 zeolites based on the calculated heats of formation and the free energy data from the hypothetical reactions. Furthermore, we find that the cationic moieties are favored at room temperature. The in-framework acidic moieties are more stable at high temperatures and the stability of the in-framework phosphorus moieties is insensitive to temperature changes. The calculated ²⁷Al, ³¹P, and ²⁹Si chemical shifts, acidity changes, and structural parameters agree well with the known experimental observations.

A series of nitrogen-containing heterocyclic compounds as imidazole glycerol phosphate dehydrase (IGPD) inhibitors were successfully screened based on IGPD substrates; however, the mechanism is not clear. In this study, the B3LYP density functional theory method with the 6-31G^** basis set as implemented in the Gaussian 03 program was selected to optimize the nitrogen-containing heterocyclic phosphates. These complex structures were constructed using molecular docking and optimization. The mode of interaction was discussed with regards to their electronic structures (frontier orbital energies and composition, the atomic charges, the natural bond orbital, etc.) and complex spatial structures (recognition functional domains of the inhibitor of IGPD, intermolecular hydrogen bonding, van der Waals interactions, etc.). The charge distribution of the nitrogen-containing heterocycle, the phosphate ion charge distribution, and the frontier orbital LUMO energy levels of the inhibitor were determined to be intrinsic factors that affect inhibitor activity. The conclusion of our study will provide valuable information for the screening and optimization of new herbicides targeted at IGPD.

To obtain Gay-Berne (GB) parameters, we carried out Monte Carlo sampling of four reference configurations based on the Boltzmann distribution. After comparing with the van der Waals potential within the all-atom model we obtained the GB parameters. Also by fitting the charge, dipole, and quadrupole with the electric potential obtained from quantum chemical computations with Gaussian 03 we obtained the electric multipole potential (EMP) parameters. With the GB-EMP parameters we then carried out molecular dynamics simulations (MDS) for CHCl₃ and tetrahydrofuran (THF) based on the coarse- grained (CG) model. Compared with the all-atom model, the CG model can reproduce the simulation results on the whole, but there are some deviations in the simulations in some details. The reason is that we only take one interaction site into account in this work. Therefore, for more complicated molecules it is necessary to take the placement of the interaction sites into account. Additionally, the multi-sites situation is also considered in the MDS within the frame of the coarse-grained model.

We carried out a theoretical study on the geometries, electronic structures, and frontier molecular orbitals of vinyl thiophene group conjugated spirooxazines (SO-SO3) using density functional theory (DFT) at the B3LYP/6-31G^* level. The calculated results show that the equalization of bond lengths at the left and right parts of the open-forms occurred during the ring-opening process. A large conjugated system was formed and this significantly narrowed the energy gap. The conjugated system became larger and its electrons flowed easily because of the introduction of different lengths of vinyl thiophene conjugation moieties into the spirooxazine molecule. The electrons and energy efficiently transferred from the vinyl thiophene to naphthoxazine. The orbital contribution rate of the vinyl thiophene group in the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) increased obviously. Time-dependent DFT (TD-DFT) calculations showed that as the conjugated vinyl thiophene unit reached 2-3 the first singlet excited state of SO2 and SO3 resulted from the electron transition from the HOMO to the LUMO, which were also assigned to the π-π^* transition. Meanwhile, λ_max was between 466 and 540 nm with an obvious red-shift while the λ_max of O-SO2 and O-SO3 reached 605 and 647 nm, respectively.

A promising macroscopic carbon nanotube (CNT) system was developed by catalytic chemical vapor deposition through CNT growth on a three-dimensional network of sinter-locked conductive metal microfibers (i.e., SMF-Ni using 8 μm nickel fibers and SMF-SS using 8 μm SS316L fibers). The electrocatalytic performance of CNTs/SMF-Ni [CNTs: 50% (w)] and CNTs/SMF-SS [CNTs: 40% (w)] hybrids were examined as electrodes in the aerobic oxidation of p-anisaldehyde (p-MT) to p-cresol methyl ether (p-MBA). An excellent conversion of 95.4% and a target product selectivity of 96.5% can be obtained with a very high electric current efficiency of >80% in the presence of air at a current density of 16 mA·cm^-2 in a methanol/p-MT/KF electrolyte using SMF-SS and CNTs/SMF-Ni as an anode and a cathode, respectively.

The transfer of Pb²⁺ facilitated by interfacial complexation with 5-(4-phenoxyphenyl)-6H-1,3,4-thiadiazin-2-amine (PPTA) at the polarized water/1,2-dicholoroethane (1,2-DCE) interface was investigated by cyclic voltammetry. We synthesized the thiadiazine derivative, PPTA, firstly. The transfer was performed at different metal concentrations and scan rates, and the obtained voltammetric transfer peaks toward Pb²⁺ ion over other divalent cations (Zn²⁺, Co²⁺, Ni²⁺, Cd²⁺, Hg²⁺, and Cu²⁺) were reversible. The dependence of the half-wave potentials of the Pb²⁺ ion on the concentration of PPTA in the organic phase indicates that the ion transfer is facilitated by the formation of 1:2 (metal:ligand) complex in the organic phase with the association constant (lgβ₂) of (17.1±0.2).

We synthesized LiFePO₄/C composite cathode materials by the rheological phase method with vegetable protein soya bean milk as a carbon source while FePO₄·4H₂O and LiOH·H₂O as raw materials. X-ray diffraction (XRD) and scanning electron microscopy (SEM) results showed that the LiFePO₄/C composite materials had od crystallinity, ultrafine sphere-like particles of 200 nm in size and in situ carbon. The electrochemical performance of LiFePO₄/C by galvanostatic cycling studies showed excellent cycle stability. The LiFePO₄/C cathode material gave a high initial discharge capacity of 156 mAh·g^-1 at 0.1C and the first columbic efficiency was 98.7%. This capacity was still 149 mAh·g^-1 after 40 cycles at 0.1C and its capacity retention was more than 95% while the discharge capacity reached 134.7 mAh·g^-1 at 1C indicating high electrochemical capacity and excellent cycling stability.

Pt/Au composite monolayer films were fabricated by combining interfacial assembly and under-potential deposition (UPD) with redox replacement. Based on the Pt/Au composite monolayers, an organic linker-free method was proposed for the fabrication of sandwich-like Pt/Au composite multilayer films: (Pt/Au)_n, Pt_m/Au, and (Pt₃/Au)_k (n, m, or k represents the layer number). Electron microscopy was used to characterize the morphologies of the Au monolayer films and the Pt/Au composite multilayer films. For each type of composite multilayer films, a common characteristic was that the effective electroactive areas increased with an increase in the layer number. Additionally, the electrocatalytic activities of the composite multilayer films for methanol electrooxidation are systematically discussed by examining the catalytic current densities and its tolerance toward carbonaceous species. For the same series of composite multilayer films (Pt/Au)₃, Pt₃/Au, and (Pt₃/Au)₂ showed a higher catalytic current density than bulk Pt (Pt_bulk). Among the three composite multilayer films, (Pt/Au)₃ showed the best catalytic performance in terms of the current density and tolerance toward carbonaceous species. The tolerance of (Pt/Au)₃ to carbonaceous species was found to be better than that of the commercial Pt/C catalyst. This better electrocatalytic activity may be attributed to the maximum synergistic effect between Au and Pt, which depends on the Pt:Au atomic ratio and also the arrangement of Pt and Au nanoparticles.

Pt nanoparticles supported on carbon nanofibers (Pt/CNFs) with different microstructure, i.e., platelet CNF (Pt/p-CNF), fish-bone CNF (Pt/f-CNF), and tubular CNF (Pt/t-CNF) were synthesized by a chemical reduction method. X-ray diffraction (XRD) and high resolution transmission electron microscope (HRTEM) were applied to characterize the structure of the as-prepared catalysts. The electrochemical surface area (ESA) was studied by cyclic voltammetry (CV). Membrane electrode assemblies (MEAs) with the as-prepared catalysts were fabricated and tested. We found that Pt nanoparticles showed different particle size and dispersion on the three kinds of CNF supports and the mean size of the Pt nanoparticles on p-CNF, f-CNF, and t-CNF was 2.4, 2.7, and 2.8 nm, respectively. Single cell testing indicated that the cell with Pt/p-CNF as the anode catalyst gave better performance compared to Pt/f-CNF and Pt/t-CNF. The maximum power density was 0.569 W·cm^-2 for Pt/p-CNF, which was higher than that for Pt/f-CNF (0.550 W·cm^-2) and Pt/t-CNF (0.496 W·cm^-2). Furthermore, Pt nanoparticles supported on carbon black (Pt/XC-72) were also prepared. Pt nanoparticles supported on CNFs have been shown to have a smaller particle size and better dispersion than those on XC-72, and this proves that CNFs can be an efficient electrocatalyst support for proton exchange membrane fuel cells (PEMFCs).

Using mesoporous SiO₂ (SBA-15) as templates and sugar as a carbon precursor, mesoporous carbon (CMK-3) was prepared at different temperatures (600-900 °C). 20%(w) Pt/CMK-3 was then prepared by impregnation reduction with sodium borohydride as a reductant. Cyclic voltammetry (CV) and chronoamperometry were applied to study the catalytic performance and stability toward methanol oxidation for the as-prepared catalyst. CO striping voltammetry was used to determine its anti-poisoning capability toward CO. The results show that the Pt/CMK-3 prepared at 900 °C had the best catalytic performance and stability toward methanol but at a carbonization temperature of 700 °C the Pt catalyst had a lower stripping potential to CO.

Novel sulfonated polyether sulfone (SPES)/AlOOH organic/inorganic composite membranes were prepared by doping SPES with AlOOH, which lowered the methanol crossover and increased the proton conductivity at high temperatures. The structure and performance of the obtained membranes were characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) etc. Compared with the pure SPES membrane the composite membranes had higher thermal stability and water uptake. The morphology of the composite membranes indicated that AlOOH was uniformly distributed throughout the SPES matrix. The network-like structure began to form when the AlOOH content was around 10%. The proton conductivity was still ca 0.014 S·cm^-1 even at a temperature as high as 120 °C. Additionally, the methanol resistance improved greatly as the content of AlOOH increased. The SPES/AlOOH composite membrane is a promising candidate for direct methanol fuel cell (DMFC) applications.

An indolium squarine 1,3-bis[(3,3-dimethylindolin-2-ylidene)methyl]squaraine was investigated as a semiconductor for use in organic field-effect transistors. Intramolecular charge separation and face to face packing were found by X-ray crystallography. p-Type thin film transistors were fabricated on Si/SiO₂ substrates by thermal evaporation and spin-coating. By channel state research we found that annealing could improve the polycrystallization of the semiconductor film from the amorphous state and device mobility improved from 10^-5 to 10^-5 cm²·V^-1·s^-1. The highest mobility of 7.8×10^-2 cm²·V^-1·s^-1 was achieved in a top contact single crystal device. ISQ transistors were also stable in air without encapsulation.

The behavior of the mixed amphiphilic drug promethazine hydrochloride (PMT) and cationic as well as nonionic surfactants was studied by tensiometry. The cmc values of the PMT-surfactant systems decrease at a surfactant mole fraction of 0.1 and it then becomes constant. The critical micelle concentration (cmc) values are lower than the ideal cmc (cmc^*) values for PMT/TX-100, PMT/TX-114, PMT/Tween 20, and PMT/Tween 60 systems. For the PMT/Tween 40, PMT/Tween 80, PMT/CPC, and PMT/CPB systems the cmc values are close to the cmc* values. This indicates that PMT forms mixed micelles with these surfactants by attractive interactions. The surface excess (Γ_max) decreases in the presence of surfactants. The rigid structure of the drug makes adsorption easier and the contribution of the surfactant at the interface decreases. The interaction parameters β^m (for the mixed micelles) and β^σ (for the mixed monolayer) are negative indicating attraction among the mixed components.

The structural property of hemoglobin (Hb) was studied in detail by UV-Vis absorption, fluorescence, circular dichroism, negative staining-transmission electron microscopy (NS-TEM), and freeze etching-transmission electron microscopy (FE-TEM) techniques using a Span 80/PEG 400/H₂O niosome system. The obtained results show that Hb is adsorbed onto the surface of niosome. The peptide chain of Hb spreads out and the apparent radius of the niosome, the intensities of the UV-Vis absorption peaks, and the fluorescence peaks increase. For the second structural parameter of Hb, the α-helix content decreases but the β-sheet and β-turn content increases. The stability of Hb varies with that of the niosome.

The aggregation behavior of 1-alkyl-3-methylimidazolium tetrafluoroborate ([Cnmim][BF₄]) ionic liquids in aqueous solutions was investigated by isothermal titration calorimetry (ITC), fluorescence quenching, and conductivity methods. The critical micelle concentration (cmc), the changes of the enthalpy (ΔH_mic), the Gibbs free energy (ΔG_mic), and the entropy (ΔS_mic) for the micelle formation and the mean aggregation number of the micelles at different concentrations were obtained. We found that entropy was the principle driving force leading to the micellization of these types of ionic liquids. The increase in alkyl chain length led to a decrease in ΔG_mic, favoring the formation of micelles. Furthermore, by combining with the aqueous solution data for [C_nmim]X (X=Cl^-, Br^-), the effect of anions on the aggregation behavior of the ionic liquids was investigated. The increase in the hydrophobicity and the volume of the anions favored the formation of micelles when the ionic liquids contained identical cations. This is believed to result from the decrease in electrostatic repulsion between the head groups in the micelles because of the relatively strong binding between the anions and the cations. With respect to [C₁₂mim][BF₄], the addition of β-cyclodextrin (β-CD) caused an increase in its cmc and a decrease in ΔH_mic and ΔS_mic; while the presence of KBF₄ caused a decrease in cmc and ΔH_mic, and an increase in ΔS_mic.

Poly((2-hydroxyethyl methacrylate)-co-(methacrylic acid)) (P(HEMA/MAA)) microgels with potential application in the restoration of damaged tissue were prepared. The phase transition behavior of P(HEMA/MAA) microgel dispersions at different pH values and concentrations as well as rheological properties of diluent and concentrated dispersions were investigated by tube inversion measurements and rheometry, respectively. The mechanism of the pH-induced physical gel phase transition was discussed. The results indicate that P(HEMA/MAA) microgel dispersions at a given concentration can be transformed into a macroscopic gel for gelation at a physiological pH. The mechanical strength of the P(HEMA-co-MAA) macroscopic gel (n_HEMA/n_MAA=8/2, pH=7.0) is the best and the elastic modulus (G') value can reach 7.58×10³ Pa. The swelling effects of the P(HEMA/MAA) microgel are different under different conditions, which results in a variety of apparent viscosities for the diluent dispersions. We deduce that the swelling behavior of the microgel particles can be divided into three stages from the outer parts of the particles to the inner parts. The gelation transitions of the concentrated dispersions are caused synergistically by space electrostatic interactions and hydrogen bonds of the neighboring microgel particles or between microgel particles and water molecules.

We report on a novel approach toward dimethyl ether (DME) synthesis using crude CO₂-rich bio-syngas and biomass char. The crude bio-syngas was derived from bio-oil reforming and was initially conditioned by catalytic conversion into CO-rich bio-syngas using biomass char over the Ni/Al₂O₃ catalyst. The molar ratio of CO₂ to CO significantly decreased from 6.33 in the CO₂-rich bio-syngas to 0.21 after bio-syngas conditioning at 800 °C. The yield of dimethyl ether from the conditioned bio-syngas was about four times higher than that from the CO₂-rich bio-syngas over the Cu-ZnO-Al₂O₃/HZSM-5 catalyst. This work potentially provides a useful approach toward producing biofuels and chemicals from bio-syngas and a novel utilization of biomass char.

Based on detailed experimental results, the effects of heat treatment on the structure, acidity, and catalytic performance of the 12-tungstophosphoric acid (TPA) modified zirconia aerogel (ZA) (TPZA) solid acids were investigated. TPZA samples, with TPA mass fraction of 25% and heat-treated at 120- 750 °C, were characterized by N₂ physical adsorption, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, FTIR spectroscopy of adsorbed pyridine (Py-FTIR), and temperature programmed desorption of NH₃ (NH₃-TPD). And they were used as catalysts in the polymerization of tetrahydrofuran (THF). The results show that, although the heat treatment might greatly influence both the surface density and type of tungsten species, the TPZA materials with the TPA loading of 25% could acquire suitable Brönsted and Lewis acidity and accordingly acceptable catalytic activities over the wide temperature ranges of 120-300 °C and 550-750 °C. In the TPZA samples treated at 120-300 °C, the presence of Brönsted acid sites can be associated with the presence of highly dispersed and somewhat distorted but intact Keggin-anions, whereas the Brönsted acid sites in the samples treated at 550-750 °C might originate from the zirconia-anchored, highly polymerized tungstate surface species. Moreover, all the samples show obvious Lewis acidity, which is associated with the presence of coordinatively unsaturated Zr⁴⁺ and phosphorous oxide produced by the decomposition of TPA.

Macroporous TiO₂ with aligned channels was synthesized using citric acid as a chelator. The wall of the macropore was composed of nanosized anatase crystals. The degradation of rhodamine B (RhB) was used as a model reaction to test the photocatalytic activity of the samples. Compared with ground TiO₂ powder, macroporous TiO₂ with aligned channels did not give a better photocatalytic RhB degradation property. Because of the scattering of UV-light by anatase nanoparticles, the TiO₂ located inside the macroporous wall was not irradiated by UV-light, and this affected the photocatalytic property of the macroporous TiO₂. The photocatalytic property improved upon exposing more of the external TiO₂ surface to UV light. Furthermore, uniform and dispersed micrometer sized TiO₂ spheres were fabricated using cetyltriethylammonium bromide (CTAB) and polyacrylic acid (PAA) as templates. The photocatalytic degradation of RhB confirmed that reducing the particle size improved the efficiency of the photocatalytic activity.

Modified magnesium-aluminate spinels (MgAl₂O₄) were prepared by recrystallizing a mixture of MgAl₂O₄ and zeolite Y nanoclusters in acidic medium to improve the acidity of MgAl₂O₄, which was commonly used as a sulfur transfer agent in fluid catalytic cracking (FCC) units. The acidity and basicity of these samples can be tuned by varying the pH value of the synthesis system. From the characterization and catalytic cracking tests the introduction of zeolitic building units into the spinels contributed to the increased microporosity, acidity, and hydrothermal stability. The catalytic results indicate that the activities and the product selectivities of the modified spinels for vacuum gas oil (V ) cracking improved remarkably compared to the parent spinel. These samples exhibited even better performance than Kaolin clay for V cracking while retaining a part of the basic sites for oxidative SO₂ uptake. Moreover, the FCC catalyst prepared using the modified spinel as a partial matrix, after equilibration, also gave superior catalytic behavior compared to a reference FCC catalyst with Kaolin clay as the main matrix.

A magnetic composite of multi-walled carbon nanotubes (MCNT) decorated with mono-dispersed Fe₃O₄ nanoparticles was prepared by a polyol method. The structure and composition of the resultant composite were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) techniques. We found that the size of the Fe₃O₄ nanoparticles supported on the MCNT could be easily controlled by changing the mass ratio of the Fe₃O₄ precursor to the MCNT. By a subsequent polyol process, 3% (w) Pd was loaded onto a Fe₃O₄-MCNT composite to form Pd/Fe₃O₄-MCNT magnetic catalysts. The results from magnetic measurements indicated that the prepared composites before and after Pd loading possess superparamagnetic characteristics at room temperature. The prepared Pd/Fe₃O₄-MCNT catalysts were evaluated by the selective hydrogenation of cinnamaldehyde as a probe reaction and it showed high activity toward the conversion of cinnamaldehyde to hydrocinnamaldehyde. Under a magnetic field, the catalyst powder was easily separated from the liquid-phase reaction system. The catalyst did not show any significant degradation after four cycles indicating the od recyclability of the prepared composite catalyst.

The purification treatment of carbon nanotubes-alumina was carried out using various oxidizers (ox), such as H₂O₂, concentrated HNO₃, and air. The obtained composite was used as support for ruthenium catalysts. The structures and properties of the products before and after modification were characterized and measured using transmission electron microscopy (TEM), thermogravimetric analysis (TG), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. The results show that purification modification treatment can remove the impurities on the surface of the CNTs-alumina, shorten the CNTs, and increase the amounts of hydroxyl, carboxyl, and carbonyl groups. Inductively coupled plasma (ICP) analysis shows that the dissolution solution composition of the CNTs-alumina composite supports with HNO₃ oxidation treatment contains 49.98 mg·g^-1 Al. The ammonia synthesis rate of the Ru/CNTs-alumina-H₂O₂ was found to be 39.8 mmol·g^-1·h^-1 at 10 MPa, 10000 h^-1, and 425 °C, which was higher than those for other CNTs-alumina-ox supported Ru catalysts.

The water-soluble coumarin derivative 7-hydroxy-4-methyl-8-(4'-methylpiperazin-1'-yl) methylcoumarin (HMPC) was synthesized by the Mannich reaction between 7-hydroxy-4-methylcoumarin and N-methylpiperazine, which possesses an electrondonating piperazine group with pH responsivity. Since the piperazine group is a pH-sensitive electron donor, the resultant HMPC has interesting photophysical and photochemical properties in different pH solutions. We investigated the characteristic UV absorption and photodimerization behavior of the coumarin derivative. The characteristic UV absorption and also the photodimerization of HMPC, which was irradiated by UV light (λ>310 nm), was effectively changed in different pH solutions. The photodimerization experiments showed that in the neutral solution the dimerization reaction rate was most rapid followed by that in the alkaline solution and it was the slowest in the acidic solution at the same concentration.

The kinetics and mechanisms of the reactions between phenothiazine and CCl₃OO^·, ^·OH were evaluated and the related rate constants were determined using nanosecond pulse radiolysis technique. The experimental results indicate that the maximum absorption of the transient product from the reaction between phenothiazine and CCl₃OO^·, ^·OH was located at 380 nm, which is attributed to CCl₃OO^· and ^·OH abstracting hydrogen from phenothiazine to generate a phenothiazine radical. The rate constants of the reactions between phenothiazine and CCl₃OO^·, ^·OH were determined to be 1.1×10⁹, 4.0×10⁹ L·mol^-1·s^-1, respectively. These results provide a theoretical foundation for the further study of the antioxidant activity of phenothiazine.

The removal of formaldehyde by dielectric barrier discharge in a coaxial cylindrical reactor has been studied at atmospheric pressure. The emission spectra of OH (A²Σ→X ²Π, 0-0) emitted from the dielectric barrier discharge have been successfully recorded. The relationship between the removal efficiency of formaldehyde and the emission intensity of OH (A²Σ→X ²Π, 0-0) has been investigated at different applied voltages, driving frequencies, concentrations of ar n and oxygen. We find that the removal efficiency of HCHO increases when the emission intensity of OH (A²Σ→X ²Π, 0-0) increases with rising applied voltage, driving frequency, and concentration of ar n. However, the removal efficiency of HCHO decreases when the emission intensity of OH (A²Σ→X ²Π, 0-0) decreases with an increase in the concentration of oxygen. The removal efficiency of HCHO is 93.8% in N₂+HCHO mixed gas at 11.5 kV applied voltage and 9 kHz driving frequency.

The second order nonlinear optical properties of sandwich thulium bisphthalocyanine (TmPc₂) molecule Langmuir-Blodgett (LB) films were investigated using the second harmonic generation (SHG)method. The dependence of the second harmonic intensity on the incident angle of the fundamental beam was measured and the mechanisms of nonlinearity were discussed briefly. The experimental results indicated that the second harmonic signal intensity was very strong and its maximum was obtained at an incident angle of 45°. The second order nonlinear optical susceptibility χ⁽²⁾ was about 1.152×10^-8 esu and the hyperpolarizability β was about 1.905×10^-30 esu. By measuring the polarization properties of the second harmonic signal for the LB film and comparing this with the theoretical analysis, we found that the origin of the second harmonic generation was attributed to the electric quadrupole mechanism for the TmPc₂ molecule.

We designed and built a microfluidic mixer based on the principle of hydrodynamic focusing verned by Navier-Stokes equation for single-molecule kinetics experiments. The mixer is a cast of poly(dimethylsiloxane) (PDMS) sealed with transparent fused-silica coverglass, which results in low fluorescence background and broad biological compatibility and this enables single-molecule fluorescence detection under nonequilibrium conditions. The pressure regulated sample delivery system is convenient for loading a sample and allows for precise and stable flow velocity control. The combination of microfluidic mixer and single-molecule fluorescence resonance energy transfer (smFRET) allows us to measure the time course of the distribution of the smFRET efficiency in protein folding. We used the fact that denatured protein collapses much faster than the mixing process to characterize the mixing time using donor and acceptor dyes labeled staphylococcal nuclease (SNase) as an smFRET efficiency indicator. By monitoring the smFRET efficiency of denatured SNase during the course of mixing, we determined that the mixing time was 150 ms under conditions suitable for single-molecule detection.

One-dimensional titanate nanomaterials were synthesized by a hydrothermal reaction using different titania sources. The morphology and crystal structure of the one-dimensional titanate nanomaterials were greatly affected by the primary particle size and crystal structure of the starting materials. The smaller initial particle size of the reactant led to a faster phase transformation of the products. The pure anatase titania favored the formation of titanate nanotubes, while the mixture of anatase titania and a small amount of rutile titania as a starting material favored the further transformation of nanotubes to nanowires or nanoribbons and promoted the phase transformation.

Optimized YLuAG:Ce (Y_0.600Lu_2.364Al₅O₁₂:Ce_0.036) phosphors were synthesized by three methods: nitrate-pyrolysis (NP), co-precipitation (CP) with ammonium hydrogen carbonate, and citrate-combustion (CC). Differences in the reaction process, crystallization, morphologies, photoluminescence (PL), and scintillant performance of the three kinds of phosphors were revealed and are explained using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), PL and thermoluminescence (TL) measurements and observations. Obvious differences in the emission bands and decay times of the different phosphors prepared were found and the differences were mostly caused by the defects either on the surface or in the bulk phase of the YLuAG:Ce phosphors powders. The recorded thermoluminescence spectra of the three kinds of phosphors show a different intensity and main glow peak positions. Additionally, the thermoluminescence spectra show that the synthesis methods induce defects in the phosphors. The defects result in strong trapping process effects and a high probability of radiative recombination between the trapped holes and electrons in the final phosphor powders that were obtained using the different synthesis routes.

Tungsten-bronze type titanate BaNd₂Ti₄O₁₂ ceramics were synthesized by solid state reactions. The conductivity and microwave dielectric loss of the samples that were thermally treated under various conditions and Ta-doped were investigated by electrochemical impedance measurement and microwave dielectric resonator measurement. The variation in conductivity with annealing atmospheres of air, O₂, and N₂ was consistent with the defect equilibriums 2O_O^×↔2V_O^··+O₂↑+2e' and Ti_Ti^×+e'↔Ti'_Ti, suggesting n-type conductance for BaNd₂Ti₄O₁₂. Thermal treatment in air/O₂ was found to favor the elimination of the native defects V_O^×, Ti'_Ti and weakly bound electrons thus decreasing the conductivity. Thermal treatment in a N₂ atmosphere, which had a low oxygen partial pressure, increased the defect content and the conductivity. Thermal treatment in air/O₂/N₂ did not clearly affect the microwave dielectric loss, suggesting that native defects have negligible effects on this property. The air-annealed sample was found to have lower conductivity and lower microwave loss compared with the air-quenched sample. The change in conductivity was found to be related to the equilibrium of the native defects but the change in microwave dielectric loss might be explained by the release of thermally induced lattice strain. Ta doping reduced the conductivity but increased the microwave dielectric loss. This work shows that air-annealing may be an efficient way to improve the Q×f factor for BaNd₂Ti₄O₁₂ ceramics, which was enhanced by ~12%.