Two series of compounds: N-(4-substituted benzylidene) anilines (1) and N-(4-substituted benzylidene) cyclohexylamines (2) were synthesized. Their ¹³C NMR and ¹H NMR chemical shifts and their UV absorption spectra were obtained. Compounds (1) and (2) were compared quantitatively to determine the effect of the substituents on the ¹³C NMR chemical shifts δ_C(C=N) and the ¹H NMR chemical shifts δ_H of the CH=N bond, and the UV absorption maximum wavelength energies v_max. Our results show that the substituents affect compounds (1) and (2) differently despite them having a similar molecular skeleton. These effects are: (i) a substituent specific cross-interaction effect (Δσ²) that significantly affects the δ_C(C=N), δ_H, and v_max of compounds (1) while its effect on the corresponding properties of compounds (2) is limited, (ii) for compounds (1) and compounds (2) the field/induced effect σ_F and the conjugation effect σ_R of the substituents negatively affect δ_C(C=N). However, they positively influence δ_H and thus both σ_F and σ_R showopposite behavior toward δ_C(C=N) compared with δ_H. In contrast the field/induced effect greatly affects the δ_C(C=N) of both (1) and (2) but does not affect their δ_H, (iii) the regular change in δ_C(C=N), δ_H, and the v_max of (1) as well as (2) can be expressed by a general equation in which the effect of the phenyl group attached to the N atom of the CH=N bond can be expressed by a dummy parameter I. The phenyl group has a constant contribution toward these three properties.

The absorption spectra of adenine, fumaric acid, and their cocrystal were measured using terahertz time-domain spectroscopy (THz-TDS) at room temperature. Experimental results show that they all have distinct fingerprint spectra in the terahertz region. The absorption peaks observed in the terahertz spectra of the cocrystal were at 0.92, 1.24, and 1.52 THz. These are very different from the corresponding reagents. Based on the characteristic hydrogen donor and/or acceptor behavior of adenine, density functional theory (DFT) was used to simulate three possible theoretical cocrystal structures with a focus on hydrogen bond formation between adenine and fumaric acid. The theoretical result shows that one of three possible simulated cocrystal structures had absorption peaks at 0.89, 1.16, and 1.41 THz, which is in agreement with the terahertz experimental result. Therefore, the structure of the cocrystal was confirmed wherein the first hydrogen bond is formed between the amino group of adenine and the hydroxyl group of fumaric acid. The second hydrogen bond is formed between the nitrogen atom of the nitrogen ring in adenine and the carbonyl group of fumaric acid. The characteristic absorption bands of the cocrystal between adenine and fumaric acid are also assigned based on the simulation results from the DFT calculation.

2,5-Diferrocenyl-1-(3-trifluorom-ethylphenyl)-pyrrole (1), 2,5-diferrocenyl-1-(4-fluorophenyl)-pyrrole (2), 2,5-diferrocenyl-1-phenyl pyrrole (3), 2,5-diferro-cenyl-1-(4-ethylphenyl)-pyrrole (4), and 2,5-diferrocenyl- 1-(4-ethoxyphenyl)-pyrrole (5) were prepared by the one-pot cycloaddition reaction of ferrocenyl alkyne. The 2,5-diferrocenyl-1-phenyl-1-pyrrole derivatives were characterized by elemental analysis, Fourier-transform infrared (FTIR) spectroscopy, mass spectrometry (MS), and nuclear magnetic resonance (NMR) spectroscopy. The influence of substituents at the phenyl moiety on the electronic interaction was studied using cyclic voltammetry (CV) and density functional theory (DFT) calculations. A linear relationship was observed between the first oxidation potential (E_a1), oxidation potential difference (ΔE) with Hammett constant (Hammett σ) of the substituent, pyrrole ¹H NMR chemical shift (δ), and pyrrole N natural bond orbital (NBO) charge. A high N charge density weakened the electronic interaction, and vice versa. Electron transfer between the two ferrocenyl units of these diferrocenyl pyrrole derivatives was influenced by the N charge density.

The second-order nonlinear optical (NLO) properties of bis-cyclometalated iridium(Ⅲ) isocyanide complexes were investigated by density functional theory (DFT). In this work, the geometries of the complexes were optimized using the B3PW91(UB3PW91) functional and they were found to be in od agreement with experimental data. The 6-31G^* basis set was used for the non-metal elements while the LANL2DZ basis set was used for iridium. From the optimized geometries the total first hyperpolarizabilities (β_tot) of the complexes were calculated by the B3PW91(UB3PW91) and B3LYP(UB3LYP) functionals. Because the polarization and diffuse function may have a nontrivial effect on the calculation of the first hyperpolarizabiliy the more flexible and polarized 6-31+G^* non-metal atom basis sets and the LANL2DZ basis set for iridium were used. The absorption spectra of all the complexes were calculated at the CAM-B3LYP(UCAM-B3LYP)/6-31+G^** (LANL2DZ iridium atom) level in acetonitrile to obtain a deeper insight into the second-order NLO properties of these complexes. The results indicate that the second-order NLO response is not strongly affected by different substituents, while the redox reaction plays an important role in improving the second-order NLO response and this comes from a change in the charge transfer pattern and an increase in the degree of charge transfer. The β_tot values of the one-electron oxidized/reduced species (1a²⁺/1a)(complexes cyclometalated with N-arylazolesand alkyl isocyanides, [(C^∧N)₂Ir(CNR)₂]⁺ (R=CH₃)) are 75 and 144 times larger than that of the eigenstate complex (1a⁺), respectively. Therefore, the redox reaction of the cationic bis-cyclometalated iridium isocyanide complexes can effectively tune the second-order NLO properties.

The influence of the substitution of Al for Si on the structural stability and mechanical properties of D8₈-Ti₅Si₃ was determined using first-principles pseudopotential plane-wave methods based on density functional theory. Several parameters including formation enthalpies ((ΔH_f), cohesive energies (ΔE_coh), bulk modulus (B), shear modulus (G),Poisson's ratio (ν), Cauchy's pressure (C₁₂-C₆₆,C₁₃-C₄₄), metallicity (f_m), and Peierls stress (τ_P-N) were calculated. To develop a better understanding of the effects of substitutional Al alloying on the toughness/brittleness of D8₈-Ti₅Si₃ from an electronic structure point of view the density of states, charge density differences and Mulliken population were determined. The results show that the intrinsic brittleness of D8₈-Ti₅Si₃ comes from strong covalent bonding between Ti^6g and Si^6g.When one or two Ti atoms occupy Si sites in the D8₈- Ti₅Si₃ crystal the intensity of covalent bonding between Ti^6g and Si^6g is reduced and the metallicity increases. This is accompanied by the presence of low intensity Al^6g―Si^6g, Ti^6g―Al^6g, and Ti4d―Al^6g bonds. However, when three Ti atoms occupy Si sites in the D8₈-Ti₅Si₃ crystal the Al^6g―Si^6g bonds disappear and the intensity of covalent bonding between Ti^6g and Si^6g increases leading to an increase in brittleness.

The processes involved in the separation of gaseous CH₄/CO₂ mixtures using a nanoporous graphene membrane were simulated using a molecular dynamics method, and the effects of three functional modifications (i.e., N/H, all H, and N/―CH₃ modifications) in the nanopores were analyzed. The results showed that the gas molecules could form an adsorption layer on the surface of the graphene. The adsorption intensity of the CO₂ molecules was higher than that of the CH₄ molecules. The functional modifications in the nanopores not only reduced the permeable area, but also improved the adsorption intensity of the gas molecules by changing the potential distribution of atoms at the edge of nanopores, and therefore affecting the permeability and selectivity of the gas mixture being separated by the nanoporous graphene membranes. Furthermore, the permeability of the CO₂ molecules was as high as 10⁶ GPU (1 GPU=3.35×10^-10 mol·s^-1·m^-2·Pa^-1), which was far greater than those of the existing polymer gas separation membranes. These results therefore demonstrate that nanoporous graphene membranes could be used in an extensive range of applications in industrial gas separation processes, such as natural gas processing and CO₂ capture.

A zirconium nanocrystalline coating has been fabricated on a Ti-6A1-4V alloy bipolar plates using a double cathode glow discharge technique to improve the corrosion resistance and reduce the interfacial contact resistance in polymer electrolyte membrane fuel cells (PEMFCs). The microstructure of Zr coating was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The microstructure of the Zr coating was found to be continuous and compact; consisting of deposited and diffusion layers. The deposited layer was 30 μm thick and composed of equiaxed grains with an average grain size of around 15 nm, whereas the diffusion layer was 10 μm thick with a gradient distribution of alloying elements, which offered a smooth transition of mechanical properties that were suitable for improving the adhesion strength of the Zr coating on the Ti-6A1-4V substrate. The electrochemical behavior of the Zr coating was evaluated in 0.5 mol·L^-1 H₂SO₄ solution containing 2 mg·L^-1 of HF solution at 70 ℃ to simulate the environment found in a PEMFC. The solution was purged with H2 (simulated PEMFC anodic environment) or air (simulated PEMFC cathodic environment). The Ecorr of the deposited Zr nanocrystalline coating was much higher than that of the Ti-6A1-4V alloy in the simulated PEMFC environment. At the applied cathode (+0.6 V) potentials for PEMFCs, both the Zr nanocrystalline coating and Ti-6A1-4V alloy were in the passive region, but the passive current density of the as-deposited Zr nanocrystalline coating was four orders of magnitude lower than that of the Ti-6A1-4V alloy. At the applied anode (-0.1 V), the Zr nanocrystalline coating exhibited characteristic cathodic protection behavior. The results of electrochemical impedance spectroscopy (EIS) showed that the values of the capacitance semicircle, phase angle maximum and frequency range were larger than those of the Ti-6A1-4V alloy in the simulated PEMFC environment when the phase angle was near -80°. Moreover, the Zr nanocrystalline coating effectively improved the conductivity and hydrophobicity of the Ti-6A1- 4V alloy bipolar plate.

A Pt/TiO₂ nanofiber catalyst has been prepared through the combination of an electrospinning technique with a reductive impregnation method. The compositions, morphologies and structures of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive spectroscopy (EDS). The results showed that the crystal phase of the TiO₂ nanofibers was composed of anatase and rutile TiO₂. Pt nanoparticles were found to be uniformly distributed on the surface of the TiO₂ nanofibers with an average size of 4.0 nm. The mass fraction of Pt in the Pt/TiO₂ nanofiber catalyst was about 20%. The electrocatalytic activities of the samples towards the oxidation of methanol were measured by cyclic voltammetry and chronoamperometry using a three-electrode system in an acidic solution. Compared with Pt/P25 and commercial Pt/C catalysts containing the same quality percentage of Pt nanoparticles, the Pt/TiO₂ nanofiber catalyst exhibited higher catalytic activity towards the oxidation of methanol and better stability.

A La₂CoNiO₆ inorganic nanofiber supercapacitor electrode material was successfully prepared from a polyvinylpyrrolidone/lanthanum nitrate-cobalt acetate-nickel acetate (PVP/LCN) precursor by electrostatic spinning. Its surface morphology and structure were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). We found that the fibers were connected through rhombohedral La₂CoNiO₆ nanoparticles resulting in a linear spatial network structure. The electrochemical performance of the as-prepared inorganic nanofibers was characterized by cyclic voltammetry (CV), chronopotentiograms (CP), and cycle life tests. The results show that the La₂CoNiO₆ nanofiber electrode material has od capacitor performance. For the three-electrode system the electrode achieved a respectable specific capacitance of 335.0 F·g^-1 at 0.25 A·g^-1. For the symmetrical two-electrode system the electrode achieved a specific capacitance of 129.1 F·g^-1 at the same current density.

SSZ-13 molecular sieves were synthesized in situ on the surface of a honeycomb-shaped cordierite support using a hydrothermal method, and the resulting material was characterized by X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM). The process for preparing SSZ-13/cordierite was optimized in detail. Furthermore, the ion exchange levels of the 50% Cu-SSZ-13/cordierite and Cu-SSZ-13 catalysts were tested in the ammonia-selective catalytic reduction (NH₃-SCR) of NO both before and after the hydrothermal treatment process using a fixed-bed reactor. The results of these experiments showed that the Cu-SSZ-13/cordierite prepared in situ by hydrothermal synthesis had od catalytic activity, and gave an NO conversion of more than 80% at temperatures in the range of 200-500 ℃, with the highest NO conversion of 96.4%being reached at 300 ℃. After being aged hydrothermally at 850 ℃ for 12 h, the SCR activity of the Cu- SSZ-13 catalyst was significantly reduced, whereas that of Cu-SSZ-13/cordierite remained largely unchanged with an NO conversion of 91% at 300 ℃. Analysis of the catalysts framework both before and after the hydrothermal treatment by X-ray diffraction and solid state ²⁷Al NMR revealed a significant reduction in the intensities of the X-ray diffraction and tetrahedral aluminumpeaks for Cu-SSZ-13, whereas those of the Cu-SSZ- 13/cordierite material remained unchanged. These results indicated that the Cu-SSZ-13/cordierite prepared by in situ hydrothermal synthesis was less prone to deactivation by hydrothermal aging.

α-MnO₂, β-MnO₂, γ-MnO₂, and δ-MnO₂ catalysts were synthesized by hydrothermal methods, and their catalytic performances towards the oxidation of ethanol were evaluated in detail. The as-synthesized MnO₂ catalysts were characterized by N₂ adsorption- desorption measurements, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and H₂ temperature-programmed reduction (H₂-TPR). The α-MnO₂ catalyst showed the best activity of the catalysts tested for the combustion of ethanol and the trend in the activity of different MnO₂ catalysts towards the oxidation of ethanol was of the order α-MnO₂>δ-MnO₂>γ-MnO₂>β-MnO₂. The effect of the crystal phase structure on the activity of the MnO₂ catalysts was investigated. The XRD results showed that there were differences in the crystallinities of the α-, β-, γ-, δ-MnO₂ catalysts, but these differences did not have a significant effect on their catalytic performances towards the oxidation of ethanol. The BET surface areas of the α-, β-, γ-, δ-MnO₂ catalysts exhibited similar tendencies to their ethanol oxidation activities, although the results of standardization calculations showed that the surface area was not the main factor affecting their catalytical activities. The XPS results showed that the lattice oxygen concentration played an important role in defining the catalytic performance of the MnO₂. The α-MnO₂ catalyst showed the best reducibility of all of the MnO₂ catalysts tested, as determined by H₂-TPR. The excellent performance of α-MnO₂ was attributed to its higher lattice oxygen concentration and reducibility, which were identified as the main factors affecting the activity of the MnO₂ towards the complete oxidation of ethanol.

Core/shell nanostructured monolithic TiO₂/SiO₂ composite aerogels were prepared by the anilineacetone in situ water formation sol-gel method. Titanium(IV) n-butoxide was used as a precursor followed by supercritical modification with partially hydrolyzed titanium alkoxide and tetraethoxysilane during ethanol supercritical fluid drying. The obtained composite aerogel showed excellent mechanical strength with a Young's modulus of 4.5 MPa. The composite aerogel exhibited excellent heat resistance. After heat treatment at 1000 ℃ its linear shrinkage decreased from 31% for the TiO₂ aerogel to 10% for the composite aerogel. The specific surface area increased from 31 m² ·g^-1 for the TiO₂ aerogel to 143 m² ·g^-1 for the composite aerogel. The composite aerogel exhibited excellent photocatalytic performance during the degradation of methylene blue after heat treatment at 1000 ℃. Its excellent photocatalytic property is attributed to its high specific surface area and the small particle size of the composite aerogel after heat treatment at 1000 ℃. The enhanced heat resistance, mechanical strength, and photocatalytic performance makes the obtained core/shell nanostructured TiO₂/SiO₂ composite aerogel a promising candidate for photocatalytic applications.

The aim of this work was to compare the structural characteristics of the FlgM protein from the thermophile aquifex aeolicus at room temperature (293 K) and at the physiological temperature (358 K) using molecular dynamics simulations. Two independent long-time molecular dynamics simulations were performed using the GROMACS software package at 293 and 358 K, respectively. The OPLS-AA force field and the TIP3P water model were used. Each simulation was run for 1500 ns. We mainly analyzed the secondary structural characteristics, the overall conformation variation, the conformational characteristics of a semi-disordered region and the structured region of the FlgM protein at two different temperatures. The results indicate that the helix structure of the N terminal increased at room temperature. The FlgM protein had the following characteristics at the physiological temperature: the structure loosed, the helix structure reduced in size, the conformational stability weakened, the H1 helix spread, the conformational flexibility increased, and the degree of instability increased. In summary, the semi-disordered region (N terminal) formed a helical structure in the unbound state and its stability decreased with an increase in temperature. The FlgM protein adapts to temperature by increasing the degree of disorder, creating a more flexible structure by improving the binding rate.