In this work, two amorphous hydrated nickel borates were synthesized with nickel chloride hexahydrate and borax as reactants at mole ratios of 1:2 and 1:8, respectively. The chemical compositions of these nickel borates were determined to be NiO·0.8B₂O₃·4.5H₂O and NiO·B₂O₃·3H₂O through thermogravimetryderivative thermogravimetry (TG-DTG) and chemical analysis, in which the main anions were determined to be B₃O₃(OH)₅^2- and B₂O(OH)₆^2-, respectively, by Raman spectroscopy. The local structure of these samples was studied by synchrotron radiation extended X-ray absorption fine structure (EXAFS). Based on the processing and fitting of the EXAFS experimental data, the neighboring coordination atoms type, the interatomic distances, and the atom-pair numbers of Ni were determined. The fitting results of the amorphous nickel borate show that the local structure around the Ni atom has a similar structure to that of the Ni₃B₂O₆ crystal. The neighboring coordination atoms of Ni in these amorphous nickel borates are O, B, and Ni. For NiO·0.8B₂O₃·4.5H₂O, the interatomic distances for Ni―O, Ni―B, and Ni―Ni are 0.208, 0.263, and 0.311 nm, and the atom-pair numbers are 5.7, 3.8, and 3.8, respectively. The interatomic distances of NiO·B₂O₃·3H₂O are 0.207, 0.262, and 0.310 nm, and the atom-pair numbers are 6.0, 4.0, and 4.0, respectively. The first shells of Ni²⁺ in NiO·0.8B₂O₃·4.5H₂O and NiO·B₂O₃·3H₂O are octahedral with six oxygen atoms.

Changes of the ground-state molecular structure of rhodamine 6G (Rh6G⁺) in pure electron donor solvent N,N-diethylaniline (DEA) were investigated by nonresonance Raman spectroscopy and quantum chemical calculations to help understand photoinduced intermolecular electron transfer (PIET) in this system. All of the vibrational modes coupled to PIET were determined and assigned. The results indicate that the most prominent vibrational mode at 675 cm^-1, corresponding to the in-plane bending of the xanthene ring, strongly contributes to PIET. Compared with the C―C stretching mode, the C=C stretching vibration of the chromophore aromatic ring of the Rh6G/DEA⁺ charge-transfer complex is more sensitive to PIET. This work provides new insight for designing molecular structures or solvent environments with desirable electron transfer properties for use in photovoltaic devices.

Raman spectroscopy combined with density functional theory (DFT) calculations provides information at the molecular level to understand weak intermolecular interactions relevant to molecular structures. In this work, the influence of the fundamental properties of thiourea on the Raman spectra of thioureawater complexes was investigated using DFT calculations. The results showed that hydrogen bond interactions can change the order of the frontier orbitals and directly influence the Raman spectra of thiourea. In addition, the keto-enol tautomerization of thiourea cannot occur in neutral aqueous solution because of the large positive Gibbs free energy change.

Grand canonical ensemble Monte Carlo (GCMC) simulations were performed to investigate the purification of benzene from air by single-walled carbon nanotubes (SWNTs). It was found that (20,20) SWNT with a large diameter is suitable to adsorb pure benzene. For the removal of benzene in air, the minimum and maximum selectivities were observed for the (12,12) SWNT at 4.0 MPa and the (18,18) SWNT at 0.1 MPa, respectively. To obtain deep insight into the unusual behavior, we analyzed the local density profiles, snapshots, and probability profiles of N₂-O₂-C₆H₆ mixtures. The results showed that the (18,18) SWNT was entirely occupied by benzene molecules, while, for the (12,12) SWNT, N₂ andwere prone to appear in the interstices between tubes, instead of inside tubes, because of stronger adsorbate-adsorbent interactions. Additionally, we calculated the orientation order parameters of the adsorbates. The results suggested that benzene molecules prefer lying nearly flat on the pore surface, while N₂ and O₂ molecules orient parallel to the pore axis. Finally, the effects of temperature and concentration on the selectivity of benzene were investigated. We found that with increasing temperature the selectivity in large pores decreased more evidently than that in small pores. By contrast, the concentration plays a more important role in affecting the selectivity in small pores.

To control the kinetic oscillations for the purpose of obtaining a high conversion rate, external forcing of methane oxidation on metal catalysts was studied with kinetic Monte Carlo simulations. The influence of composition cycling of the feed on the dynamics and conversion rate was investigated. The results showed that the composition cycling of feed cannot give rise to different kinetic behavior, such as short periods or doublepeaks, but does bring about a higher conversion rate. It was shown that with forcing periods from T/3 to 2T (T is the average period of autonomous oscillations), the oscillations changed from short periods and small amplitudes to typical double-peak oscillations. The conversion rate can also be calculated, and the results showed that the mean conversion was slightly higher with forced oscillations. The changing of the kinetics can be attributed to phase transition of the metal catalysts from the oxidized surface to a partially reduced state.

The deformation mechanisms and mechanical tensile behavior of Ag nanowires containing different densities of parallel twin boundaries were investigated using molecular dynamics simulations. The effect of twin boundaries on the Young's modulus in nanowires was not obvious in the elastic deformation stage. After the elastic deformation stage, the initial dislocation from the edge of the free surfaces in nanowires resulted in plastic deformation. The existence of the twin boundary in nanowires will cause the spread of the dislocation and act as sources of dislocations with the assistance of the newly formed defects with further tension load. The simulation showed that the mechanical strength of Ag nanowires was highly dependent on the twin boundary spacing and the size of the grain, resulting from the aspect ratio between the spacing distance and the length of the cross-section. In particular, twinned Ag nanowires with small twin density (aspect ratio > 1) had small yielding stresses, even less than that of the single crystal Ag nanowires. Only with large twin density (aspect ratio < 1) can the nanowires be strengthened by the structure of the twin boundaries. We also investigated the effects of tensile rate and temperature on the yielding strength of the Ag nanowires. With increasing temperature, the difference of yielding stress between twinned nanowires and single crystal nanowires first increased and then decreased to a stable level. With increasing tensile rate, this difference showed the opposite trend.

From the viewpoint of the elastic-plastic microscopic mechanisms of explosives, we investigated the microscopic physical and chemical responses of seven dominant slip systems in the β-octahydro-1,3,5,7- tetranitro-1,3,5,7-tetrazocine (β-HMX) single crystal under low pressure and long pulse loading using the ReaxFFforce- field-based molecular dynamics method. The simulation results suggest that the seven slip systems exhibit different physical and chemical responses for loading orientations normal to the (001), (101), (100), (011), (111), (110), and (010) crystal planes. The shear stress, energy, temperature, and chemical reaction strongly depend on the loading direction. For the (010) plane, the shear stress barrier is very high, which leads to fast energy accumulation and temperature increment that contribute to the early bond-breaking process, making it the most sensitive direction. For the (001) plane, the small shear stress barrier results in slow energy accumulation and temperature increase, and thus little bond dissociation, making it the least sensitive direction. The reaction sensitivity of the slip system is suggested to be significantly related to the intermolecular contacts on the two sides of the slip plane (i.e., steric hindrance) and the reaction activity of contacted atoms or groups. Directions with large steric hindrance and high reaction activity lead to high reaction sensitivity, whereas directions with small steric hindrance or low reaction activity result in low reaction sensitivity. The slip system with relatively high chemical reaction sensitivity is suggested to be associated with the origin of“hot spots”in energetic single crystals. This study provides theoretical support for developing a more reasonable and reliable sensitivity evaluation method for high explosives.

A multiscale simulation strategy was designed based on the features of polyurethane. With this strategy, we investigated the mechanical properties and glass transition temperatures of polyurethane materials crosslinked by different reactants or with different functionalities of the same reactants. From the atomistic simulation results, a coarse-grained dissipative particle dynamics model combined with the reaction module was constructed. Then, this simulation was used to describe the diffusion of components as well as the crosslinking process and the formation of the network structure. Finally, the reverse-mapping scheme was used for atomistic representation and to analyze the mechanical properties and glass transition temperature of the system. This multiscale simulation strategy can be expanded to other complex systems with competing dynamic influencing factors.

Several new porous aromatic frameworks (PAFs) were designed by Li doping or B substitution based on the PAF-301 molecular model. The hydrogen storage capacities of these materials were investigated using quantum mechanics and molecular mechanics methods. First, the binding energies between H₂ and the different molecular fragments were calculated using quantum mechanics, and the atomic charge distributions of the molecular fragments were calculated by the density-derived electrostatic and chemical charge (DDEC) method. Then, the adsorption equilibrium properties of H₂ on the different PAFs were calculated at 77 and 298 K using grand canonical Monte Carlo (GCMC) simulations. The results indicate that the binding energy between H₂ and benzene without Li doping is poor, while the binding energies between H₂ and Li-doped six-member rings are improved. Li atoms doped into the benzene ring result in higher positive charges, and the electronegativity of the original carbon atoms in the benzene ring increase after its two carbon atoms are replaced with two boron atoms. Among these new materials, PAF-301Li has the highest hydrogen storage capacity at 77 K, while PAF-C₄B₂H₄-Li₂-Si and PAF-C₄B₂H₄-Li₂-Ge have better hydrogen storage capacities at room temperature than at 77 K. However, the hydrogen storage capacities of these various materials at room temperature are far below the capacities at cryogenic temperature. The preferential adsorption sites for H₂ on the PAFs at 77 K were analyzed through the potential energy surfaces and mass center density distribution of the adsorption equilibrium. It was found that there are four obvious high-density adsorption regions in the frameworks of PAF-301 and PAF-301Li because of their wide low-energy regions in the crystal center, while there are only two distinct high-density adsorption regions in the other three PAFs because of their narrow low-energy regions in the unit cell center.

To accurately predict the capability and possible reaction site for atoms in molecules to donate or accept electrons in chemical processes, i.e., to quantitatively determine electrophilicity, nucleophilicity, and regioselectivity, is an important yet incomplete task. Earlier, we proposed using the Hirshfeld charge and information gain as two equivalent descriptors for this purpose, based on the Information Conservation Principle we recently proposed. This idea was successfully applied to two series of molecular systems to confirm its validity. However, our previous work is hindered by the fact that the involved element is carbon. It is unclear if stockit applies to other elements and to different valence states of the same element. In this study, to address these issues, the method was applied to nitrogen-containing systems. Five different cate ries of compounds were studied, including benzenediazonium, azodicarboxylate, diazo, and primary and secondary amines, with a total of 40 molecules. The results show that there are strong linear correlations between the Hirshfeld charge and their experimental scales of electrophilicity and nucleophilicity. However, these correlations depend on the valence state and bonding environment of the nitrogen element. The linear relationship only holds within the same cate ry. Possible reasons for this observation are discussed.

The hydrodesulfurization (HDS) of thiophene on an γ-Mo₂N(100) surface was investigated by density functional theory (DFT) and different configurations of thiophene on γ-Mo₂N(100) surface were considered. After geometric optimization, it was confirmed that the η5-Mo₂N configuration was the most stable adsorption model with an adsorption energy of -0.56 eV, where thiophene absorbed on 4-fold hcp vacant sites parallel to the surface with the S atom bonded to a Mo2 atom. The stable coadsorption of H atoms and thiophene on hcp sites showed that the hcp site is the active site for thiophene HDS on γ-Mo₂N(100). A direct desulfurization reaction pathway in HDS of thiophene dominated the process on the γ-Mo₂N(100) surface, which could be divided into the removal of the S atom and the hydrogenation saturation of C₄ species. To identify the intermediate products and the most probable reaction mechanism of thiophene HDS, a transition state search was carried out. The results indicated that the reaction of the first H atom required an activation energy of 1.69 eV, which was the rate-determining step in the HDS of thiophene. The thiol group (―SH) and butadiene were preferentially formed after hydrogenation of thiophene, and ―SH detached from mercaptan was the intermediate of H₂S. 2-Butene and butane were the products of the hydrogenation saturation of butadiene. H₂S, 2-butene, and butane were easily desorbed from γ-Mo₂N(100) to give the products because of weak adsorption.

Electrochemical impedance spectroscopy (EIS) is a very useful technique for studying electrochemical behavior. The ideal Nyquist plot of electrochemical impedance spectroscopy for an electrical double-layer capacitor (EDLC) consists of a 45° line in the high-middle frequency region and a vertical line in the low frequency region, which can be explained by the transmission line model with pore size distribution. However, a semicircle loop in the high frequency region has been found in many studies. Hence, in this study, an equivalent model is proposed, in which the semicircle loop is ascribed to the contact resistance and contact capacitance between particles of activate materials, and between the activated carbon (AC) electrode and current collector. The effects of the charging process, conductivities of the active material and electrolyte, content of conductive additive and binder, porous separator, mass loading, and exerted pressure to the electrode on the EIS spectra of EDLCs were experimentally investigated. Among these effects, the most significant factors were the charging cut-off voltage, conductivity of activated carbon, content of conductive additive, and exerted pressure.

Three-dimensional reduction of graphene oxide with a series of different degrees of reduction was performed by the hydrothermal method in the temperature range from 120 to 220 ℃, with graphene oxide sols as the precursor and prepared by graphite oxide gels. The effect of the temperature of the hydrothermal reaction on the materials appearance, structure, and super capacitor performance was investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and electrochemical measurements. The results show that the prepared three dimensional reduction of graphene oxide was porous and reticulated, and its volume and inner mesh aperture gradually decreased with increasing temperature, while its degree of reduction and order increased at the same time, and its structure gradually transformed to the graphite oxide structure. However, thematerials' specific capacitance and energy density showed the tendency of first increasing and then decreasing, with the electric double-layer capacitor mainly remaining. The three-dimensional reduction of graphene oxide materials at 180 ℃ resulted in the best super capacitor performance, with a specific capacitance of 315 F·g^-1 when the current density was 0.5 A·g^-1 and 212 F·g^-1 when the current density was 10 A·g^-1. Its energy density was 40.5 Wh·kg^-1 and its specific capacitance was 86% after 5000 cycles, with all these properties indicating its od super capacitor performance.

To improve the sensitivity of molecular imprinted electrochemical sensors, a molecularly imprinted polymer (MIP) film for the determination of phenobarbital (PB) was electropolymerized on a CuO nanoparticlemodified glassy carbon electrode. Methacrylic acid was used as the functional monomer and ethylene glycol maleic rosinate acrylate as a cross-linking agent in the presence of supporting electrolyte (tetrabutylammonium perchlorate). The electrochemical properties of CuO nanoparticle-modified molecularly imprinted and non-imprinted polymer (NIP) sensors were investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). The results showed that the electrochemical properties of the CuO nanoparticle-modified MIP sensor were completely different from those of NIP sensors. X-ray diffraction confirmed that the nanoparticles were CuO. The morphology of the CuO nanoparticle-modified MIP sensor was examined under a scanning electron microscope. The CuO nanoparticles were uniformly distributed on the surface of the modified glassy carbon electrode, which improved the recognition sites of the modified MIP sensor. The response value of the DPV peak current showed linear dependence on the PB concentration in the range 1.0×10^-8 to 1.8×10^-4 mol·L^-1 (linear regression coefficient =0.9994) with a detection limit (S/N=3) of 2.3×10^-9 mol·L^-1. The results indicated that the CuO nanoparticle-modified MIP sensor is one of the most sensitive and selective sensors for PB determination. The prepared sensor was successfully applied for the determination of PB in practical samples and the recovery ranged from 95.0% to 102.5%.

Zn-Al-[V₁₀O₂₈]^6- layered double hydroxide (LDH-V) as a type of corrosion inhibitor was prepared with the co-precipitation method using one solution containing zinc and aluminum nitrates precursors and a second solution containing Na₃VO₄, where the decavanadate anion is speciated at pH 4.5. The hybrid solgel solution was prepared from 3-glycydoxypropyltrimethoxysilane (GPTMS) as the organic precursor sol and zirconium n-propoxide (TPOZ) as the inorganic precursor sol. The doped coatings were obtained by dip coating the way that the samples were immersed into solutions with different LDH-V concentrations (0.0, 0.25×10^-3, 0.75×10^-3, 1.5×10^-3, 3.0×10^-3 mol·L^-1). The morphology and corrosion resistance of the solgel coating doped with different LDH-V concentrations were studied. The sol-gel coatings were investigated by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The salt spray test was used to evaluate the corrosion resistance of the different coatings. The corrosion behavior of the coatings was evaluated by electrochemical impedance spectroscopy (EIS) during immersion in 0.05 mol·L^-1 NaCl solution. The results showed that LDH-V not only improves the corrosion resistance of the coating, but also provides a function for self-healing of broken coatings. However, when the LDH-V doping concentration was high, it destroyed the integrity of the coatings and decreased the corrosion resistance of the coatings. The best LDH-V doping concentration was 1.5×10^-3 mol·L^-1.

Photocatalytic overall water splitting under a two-step photocatalytic (Z scheme) system was studied with layered perovskite H_1.9K_0.3La_0.5Bi_0.1Ta₂O₇ (HKLBT) and Pt/WO₃ used as the hydrogen and oxygen evolution photocatalysts, respectively. The influence of the redox mediator species and the concentration of the redox mediator was investigated. The results showed that overall water splitting (H₂/O₂ volume ratio: 2:1) was achieved using Fe²⁺/Fe³⁺ as the redox mediator, where the hydrogen and oxygen evolution rates reached 66.8 and 31.8 μmol·h^-1 (H₂/O₂ volume ratio: 2.1:1), respectively. A very high concentration of the redox mediator is unable to improve the photocatalytic activity because it is blocked by the carrier mediator redox rate based on the activity of the photocatalysts.

Silver phosphate/bismuth vanadate (Ag₃PO₄/BiVO₄) composite photocatalysts were successfully synthesized by coupling a reflux method with an in situ precipitation route. X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), UV-Vis diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) spectroscopy were used to characterize the as-prepared products. The XRD and FESEM results showed that Ag₃PO₄/BiVO₄ composite photocatalysts were successfully obtained. An energy-efficient light emitting diode lamp was used as the visible light source, and the photocatalytic performances of the as-synthesized products were evaluated for dye degradation in a low-cost photocatalytic system. The Ag₃PO₄/BiVO₄ composite with a Ag₃PO₄:BiVO₄ molar ratio of 1:3 exhibited much higher photocatalytic activity than pure Ag₃PO₄ catalyst, resulting in decreased use of Ag₃PO₄. The Ag₃PO₄/BiVO₄ composite photocatalyst showed the best photoactivity in neutral solution and had a higher photodegradation rate for cationic dyes than anionic dyes. The superoxide radicals (O₂^-·) and holes (h+) were considered to be the main active species in the Ag₃PO₄/BiVO₄ system. The photocatalytic activity of the Ag₃PO₄/BiVO₄ composite photocatalyst decreased to different degrees after three cycles because of the production of metallic silver.

A Bi₂MoO₆/BiVO₄ photocatalyst with a heterojunction structure was synthesized by a one-pot hydrothermal method. Its crystal structure and microstructure were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HRTEM). The FESEM and HRTEM images indicated that Bi₂MoO₆ nanoparticles were loaded on the surface of BiVO₄ nanoplates to form a heterojunction. The ultraviolet visible (UV-Vis) diffuse reflection spectra (DRS) showed that the resulting Bi₂MoO₆/BiVO₄ heterojunction possessed more intensive absorption within the visible light range compared with pure Bi₂MoO₆ and BiVO₄. These excellent structural and spectral properties endowed the Bi₂MoO₆/BiVO₄ heterojunction with enhanced photocatalytic activity. It was found that the Rhodamine B (RhB) degradation rate with Bi₂MoO₆/BiVO₄ was higher than that with pure BiVO₄ and Bi₂MoO₆ under visible light (λ>420 nm) by photocatalytic measurements. The enhanced photocatalytic performance of the Bi₂MoO₆/BiVO₄ sample can be attributed to the improved separation efficiency of photogenerated hole-electron pairs generated by the heterojunction between Bi₂MoO₆ and BiVO₄, intensive absorption within the visible light range, and high specific surface area.

Nano-sized Ag₂CO₃ and carbon nanotube (CNT) composites were fabricated by a facile chemical precipitation approach in N,N-dimethylformamide (DMF) solvent. The as-prepared Ag₂CO₃/CNT samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and ultra violet-visible (UV-Vis) diffuse reflectance spectroscopy (DRS). The photocatalytic activity of the samples was evaluated by photocatalytic degradation of methyl orange (MO) under visible light irradiation. The results showed that the nano-sizedAg₂CO₃ particles and CNTs were well combined. The Ag₂CO₃/CNT composite with CNT content of 1.5%(w) exhibited optimal photocatalytic activity under visible light. Ninetythree percent of the MO was removed by the Ag₂CO₃/CNT composite within 60 min. For the Ag₂CO₃/CNT composites, we found that the incorporation of CNT improved the structural stability of Ag₂CO₃ compared with Ag₂CO₃. After three cycles, 81% of the MO was decomposed by the Ag₂CO₃/CNT composite with CNT content of 1.5% (w), but only 59.5% of the MO could be removed by Ag₂CO₃. The improvements in the activity and stability are attributed to the conductive structure supported by CNTs, which favors electron-hole separation and the removal of photogenerated electrons from the decorated Ag₂CO₃.

A series of Ce-Cu-Co/carbon nanotubes (CNTs) catalysts with different Ce contents were prepared by co-impregnation, and the catalytic performance was investigated for the synthesis of higher alcohols from syngas. The catalysts were characterized by X-ray diffraction (XRD), temperature-programmed reduction of H₂ (H₂-TPR), N₂ adsorption-desorption isotherms (BET), transmission electron microscopy (TEM), and temperature-programmed desorption of CO (CO-TPD). The results showed that at a Ce content of 3% the catalyst had the highest catalytic activity. The formation rate and selectivity of alcohol reached 696.4 mg·g^-1· h^-1 and 59.7%, where the mass fraction of ethanol was 46.8% of the total amount of alcohols. The addition of an appropriate amount of Ce facilitated the dispersion of Cu and promoted reduction of the catalysts. It also markedly increased the adsorption capacity for CO, and significantly improved the formation of active sites for alcohols, which is favorable for the catalytic activity and to improve the selectivity of alcohols. Research showed that combining the CuCo-based catalyst, which has high activity and a high ability of carbon chain growth, with the confinement effect of CNTs can result in a narrow distribution of alcohols and significantly improve the selectivity of ethanol.

The photochemical properties of difloxacin (DFX) were investigated in neutral aqueous solution. DFX aqueous solution showed intense absorption with one peak at 273 nm (molar absorption coefficient ε= 33000 dm³·mol^-1·cm^-1) and two other peaks at 323 and 335 nm (ε=15500 dm³·mol^-1·cm^-1) with the same molar absorption coefficient. Both the absorption and emission properties of DFX were pH-dependent. The acid dissociation constant (pK_a) for the protonation equilibria of the ground state (5.9 and 9.8) were determined spectroscopically. DFX fluoresces weakly, and its maximum quantum yield for fluorescence emission was 0.06 at pH 3. Laser flash photolysis and pulse radiolysis studies were carried out to characterize the transient species of DFX aqueous solution. Triplet-triplet absorption reached a maximum at 620 nm with a molar absorption coefficient of 7900 dm³·mol^-1·cm^-1. The energy transfer method was used to estimate the triplet energy of DFX, which was 263.5 kJ·mol^-1. The quantum yield of triplet formation was determined to be 0.21. Furthermore, DFX showed monophotonic photoionization with a quantum yield of 0.02. Pulse radiolysis indicated that DFX could react with e_aq^- and ·OH, and the bimolecular rate constants for these reactions were 1.72×10¹⁰ and 1.0×10¹⁰ dm³· mol^-1 ·s^-1, respectively. It is expected that this research may be helpful in determining the phototoxicity mechanism of DFX.

The effect of Kolavenic acid (KA), an active component isolated from the genus Polyalthia, on the structure of human serum albumin (HSA) was investigated by fluorescence polarization, synchronous fluorescence, three-dimensional (3D) fluorescence, and absorption spectroscopy in combination with molecular modeling techniques under physiological conditions. The synchronous and absorption fluorescence spectra confirmed that KA has an effect on the microenvironment around HSA in aqueous solution. The two-dimensional (2D) and 3D fluorescence spectra showed that KA could quench the intrinsic fluorescence of HSA and make its conformation change. Fluorescence polarization measurements provided useful information on the relaxation time and aggregation behavior of the complex formed between HSA and KA, and indicated that the presence of KA caused changes in the fluidity and microviscosity of HSA. The binding constants and thermodynamic parameters for KA-HSA systems were obtained under different temperatures (298, 308, and 318 K). Molecular docking showed that the KAmoiety bound to the hydrophobic cavity of HSA, and there were three hydrogenbonding interactions between KAand the Lys195 andAsp451 residues. Fluorescent displacement measurements confirmed that KA bound to HSA at site Ⅱ. In addition, the binding mechanism of KA and HSA was revealed by the physicochemical parameters at the molecular level. The results showed that the interaction between KA and HSA was strong, indicating that KA may be stored and transferred by serum albumin.

Molecular dynamics simulations were used to compare the adsorption behavior of lysozyme on two typical antifouling polymer materials: poly(ethylene) glycol (PEG) and poly(dimethylsiloxane) (PDMS). The influence of the surface properties of the polymer films on protein adsorption is discussed at the microscale. Based on the interactions, energy changes between the protein and polymer films, and dynamical behavior of the hydration molecules near the polymer film, the reasons why the PEG antifouling coating has a better antifouling effect than the PDMS surface were determined as follows. (1) The lower binding energy between the protein and the PEG coating than between the protein and the PDMS coating makes the protein adsorb weaker on the PEG coating than on the PDMS coating. (2) The protein would adsorb on the film surface when overcoming the energy barrier caused by the hydration layer. Molecular water adsorbs on the PEG surface stronger than on the PDMS surface, and is difficult to desorb. Therefore, the protein needs to overcome a higher energy barrier to adsorb to the PEG surface than to the PDMS surface, and thus it is more difficult for protein to absorb on the PEG surface than on the PDMS surface.

ω-Conotoxins are active peptides composed of 24-31 amino acids isolated from venomous marine predatory cone snails. ω-Conotoxins selectively inhibit voltage-gated calcium channels (VGCCs) in nociceptors, so are considered attractive molecules for drug design. In this study, based on a set of new amino acid structure descriptors (c-scales) and genetic partial least squares (G/PLS) regression method, quantitative structureactivity relationship (QSAR) models for N-type and P/Q-type VGCC anta nists of ω-conotoxins were developed. Two virtual polypeptide libraries with 2244 peptides were designed and established for N-type and P/Q-type VGCC anta nists, respectively. Then, based on the biological activities predicted from the constructed QSAR models and chemical similarities to the probes MVIIA and MVIIC, the polypeptide libraries were virtually screened. As a result, the established QSAR models had od predictability (cross- validated correlation coefficient CV-r²>0.89). The structural diversity of the libraries was validated using principal component analysis (PCA) and hierarchical cluster analysis (HCA) approaches. Six N-type and nineteen P/Q-type VGCC anta nists with high selectivity and activity were identified by virtual screening. The results of this study will be valuable for finding highly active polypeptide and non-peptide mimetics. Furthermore, the established polypeptide QSAR models and virtual screening strategy can also be applied to other peptide systems.

Cationic grafted particles with a brush structure were prepared with micron-sized silica gel particles as a matrix via graft-polymerization and macromolecular reaction. The adsorption ability, adsorption mechanism, and adsorption thermodynamics of bovine serum albumin (BSA) on the particles were investigated in depth. The tertiary amine group-containing monomer (dimethylaminoethyl methacrylate, DMAEMA) was first allowed to polymerize on the surfaces of silica gel particles by initiating the ―NH₂/S₂O_82- surface system, resulting in grafted PDMAEMA/SiO₂ particles. Subsequently, the tertiary amine groups in the chains of the grafted PDMAEMA macromolecules were quaternized with chlorethamin reagent to obtain the functional grafted QPDMAEMA/SiO₂ particles, on which the cationic polyelectrolyte QPDMAEMA macromolecules were grafted. The zeta potential of the QPDMAEMA/SiO₂ particles was determined to estimate their surface electrical property. Isothermal adsorption experiments were carried out to investigate the effects of several main factors, including the pH value of the medium, ion strength, and temperature, on the adsorption performance of QPDMAEMA/SiO₂ particles. Finally, the adsorption thermodynamics were investigated. The results showed that the functional grafted QPDMAEMA/SiO₂ particles had much higher zeta potential than PDMAEMA/SiO₂. BSA would be very strongly adsorbed on QPDMAEMA/SiO₂ particles through electrostatic interactions. The adsorption capacity first increased and then decreased with increasing pH value, and it had a maximum value of 112 mg·g^-1 when the pH value of the medium was equal to the isoelectric point of BSA (pI=4.7). On both sides of the isoelectric point, the effect of ion strength on the adsorption capacity was opposite. When the pH value of the medium was lower than the isoelectric point of BSA (i.e., pH<4.7), the adsorption capacity increased with increasing concentrations of electrolyte (NaCl). When the pH value of the medium was equal to the isoelectric point of BSA (i.e., pH=4.7), the adsorption capacity was almost unchanged with ion strength. The adsorption process was exothermic and during this process the entropy tended to decrease. Furthermore, this adsorption process was driven by enthalpy.