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The immobilization of sedimentary phosphorus (P) by capping sediments with amended calcium peroxide material (ACPM) and CaO2 was investigated, the sediments and overlying water from a black-odor river. Under the capping with ACPM and CaO2, the pH and dissolved oxygen (DO) in the overlying water were higher than in the control. This contributed to the more loss of external P under the ACPM (the phosphate sorption was fitted well by the Langmuir equation, the maximum P sorption capacity up to 29.28 mg P g−1). Additionally, ACPM improves the decrease of the reduction materials (e.g., NH4+-N, Fe2+) in the pore water compared to that associated with CaO2, resulting in a less obvious dissolved inorganic P (DIP) in the pore water, but the accumulation of DIP in the pore water with CaO2 suggested an explosive release once the micro-environment conditions encounters adverse conditions. The sharp reduction of Fe/Al-P and Res-P contributes to the increase of DIP in the pore water, with a release of up to 390.60 mg P kg−1 DW (dry weight), whereas the value is only 62.55 mg P kg−1 DW when capped with ACPM. Correspondingly, the percentage of the bioavailable P to Tot-P decreases rapidly from 17.27% (control, 0–2 cm) to 7.21% (ACPM, 0–2 cm) and 10.57% (CaO2, 0–2 cm), indicating the obvious P immobilization. The implication is that the application of CaO2 is not suitable for direct use, while the combination with other materials (e.g., WPS) is a better choice.

3D graphene (or graphene-like porous carbon) is prepared from precursor lignin separated and purified from alkaline pulp black liquor. The lignin is pretreated using rapid freeze-dry technique for the porous, soft and dispersive microstructure. A special temperature control program is designed to keep the porous structure of lignin particles in the carbonization and graphitization process, avoiding agglomeration. The 3D graphene from lignin consist of curve graphene sheets in dimensions around dozen micrometers, which merge each other with clear dihedral angle and form wood-ear like architecture, different from fullerene like carbon crystals. The porous carbon is characterized and analyzed with FTIR, Raman, XRD, SEM, TEM, XPS, and SSA. A possible chemical mechanism in the synthesis of 3D graphene from lignin precursor is proposed. The aromatic groups and alkane fragments in lignin are decomposed during pyrolysis under high temperature, then the benzene rings compose the graphene sheets, and the sp3 free carbon atoms join the graphene sheets with chemical bonds along the framework of lignin polymer, forming the self-supporting and self-constructing 3D graphene, or porous carbon.

The transformation of sedimentary phosphorus (P) fractions by point injection of CaO2 was investigated in this study. The results showed that the addition of CaO2 increased the dissolved oxygen (DO) in the overlying water as well as its pH. Simultaneously, the concentrations of total organic carbon (TOC), ammonia nitrogen (NH4+-N), total phosphorus (TP) and dissolved inorganic P (DIP) in the overlying water were sharply reduced by the point injection of CaO2, indicating that this accelerated the mineralisation rate of organic matter. It also favoured the formation and maintenance of the micro-oxidation environment in the deep sediments. NH4Cl-P, Fe/Al-P and Ca-P increased significantly, while the Res-P decreased sharply, especially close to the injection point of CaO2, accelerating the transformation of P. These results can all be attributed to the oxidation of organic P and the adsorption of dissolved P from the overlying water. Additionally, the NaHCO3-extractable phosphorus (Olsen-P) and algal available phosphorus (AAP) were reduced, and their percentages in Ca-P and Fe/Al-P also decreased, especially close to the injection point of CaO2. The bioavailable P decreased from 25.6% (the initial) to 17.2% (the mean for the different distances) after the point injection of CaO2, when the sum of the Olsen-P and AAP was used to calculate the bioavailable P. This indicates that point injection of CaO2 favours not only the transformation of P species but also inhibition of the bioavailable P. This is attributable to acceleration of the transformation from bioavailable to inert P.

BACKGROUND The present work was performed to detect the potential inhibitory effect of cyclic guanosine monophosphate (cGMP)-dependent protein kinase II (PKG II) on epidermal growth factor (EGF) receptor-induced biological activity and related signal cascades in osteosarcoma cells. MATERIAL AND METHODS We transfected the osteosarcoma MG-63 cell line with an adenoviral vector encoding PKG II cDNA (Ad-PKGII) and incubated the transfected cells with 250 μM 8-pCPT-cGMP to activate the PKG II. We stimulated the MG-63 cells with100 ng/ml EGF, and then detected their proliferation using a CCK-8 assay. Transwell assay was used to examine MG-63 cell migration; and Western blot analysis was used to detect expression of matrix metalloproteinase 9 (MMP-9) and activation of ERK and Akt. RESULTS Stimulating cells by 100 ng/ml EGF promoted MG-63 cell proliferation and migration, ERK and Akt phosphorylation, and MMP-9 expression. These effects of EGF were inhibited in MG-63 cells infected with Ad-PKGII and incubated with 8-pCPT-cGMP. CONCLUSIONS Our results demonstrate that Ad-PKGII infection significantly inhibited EGF-induced proliferation and migration, as well as the associated-signal cascades; which indicates that PKG II might be a potential anti-cancer factor.

A fast analytical method for the simultaneous determination of 9 mycotoxins, including aflatoxins (B1, B2, G1, and G2), fumonisins (B1, B2 and B3), zearalenone, and deoxynivalenol in corn using dispersive solid-phase extraction method and ultra-performance liquid chromatography coupled to tandem quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) was developed and validated. Samples were extracted with acetonitrile-water (84:16, v:v, containing 1% acetic acid) using ultrasonic extraction. The extracts were purified with a dispersive SPE method using C18 as a cleaning agent. The final clear extracts were dried by nitrogen blowing and subsequently redissolved in methanol-water (5:5, v:v). The samples were then analyzed by UPLC-Q-TOF-MS with 0.1% formic acid in ammonium acetate-methanol as mobile phase. The mean recoveries were ranged from 68.0 to 120.0%, and the relative standard deviation (RSD) ranged from 0.18 to 6.29%. Limits of detections ranged from 0.05 to 50 μg kg−1, and limits of quantification ranged from 0.1 to 200 μg kg−1, which were below the legal limits set by the European Union for the legislated mycotoxins. The developed method was applied to 130 corn samples. Among the mycotoxins studied, aflatoxins B1 and fumonisins B1, B2 and B3 were the most predominant mycotoxins, and their concentrations were 0–593.12, 0–2.01×104, 0–6.94×103 and 0–3.05×103 μg kg−1, respectively.

Direct radical oxyphosphorylation of styrenes with diarylphosphine oxides and dialkyl phosphites mediated by Mn(OAc) 3 is described. The solvent played a key role in this selective difunctionalization reaction.

Graphene microcrystal (GMC) is a type of glassy carbon fabricated from lignin, in which the microcrystals of graphene are chemically bonded by sp3 carbon atoms, forming a glass-like microcrystal structure. The lignin is refined from sugarcane bagasse using an ethanol-based organosolv technique which is used for the fabrication of GMC by two technical schemes: The pyrolysis reaction of lignin in a tubular furnace at atmospheric pressure, and the hydrothermal carbonization (HTC) of lignin at lower temperature, followed by pyrolysis at higher temperature. The existence of graphene nanofragments in GMC is proven by Raman spectra and XRD patterns, the ratio of sp2 carbon atoms to sp3 carbon atoms is demonstrated by XPS spectra, and the microcrystal structure is observed in the high-resolution transmission electron microscope (HRTEM) images. Temperature and pressure have an important impact on the quality of GMC samples. With the elevation of temperature, the fraction of carbon increases, while the fraction of oxygen decreases, and the ratio of sp2 to sp3 carbon atoms increases. In contrast to the pyrolysis techniques, the HTC technique needs lower temperatures because of the high vapor pressure of water. In general, with the help of biorefinery, the biomass material, lignin, is found to be qualified and sustainable material for the manufacture of GMC. Lignin acts as a renewable substitute for the traditional raw materials of glassy carbon, copolymer resins of phenol formaldehyde, and furfuryl alcohol-phenol.

A facile and efficient protocol of oxythiocyanation of styrenes with ammonium thiocyanate has been developed. The reaction proceeded at room temperature using oxygen as sole oxidant to afford the α-oxothiocyanates via radical pathway in moderate to good yields. This method is straightforward, green and cost-effective, requires no catalyst and additives.

In this study, a sugarcane bagasse cellulose bundle crystal is converted to a cellulose few-layer two-dimensional (2D) crystal by a specially designed technique scheme, which consists of (1 → 4)-β-D-glucan chains bound to each other by hydrogen bonds in a plane. A graphene few-layer 2D crystal is fabricated from the cellulose 2D crystal by pyrolysis reaction. The fabricated graphene 2D crystal is further analysed and characterised using scanning electron microscopy, high-resolution transmission electron microscopy (HRTEM), atomic force microscopy, and Raman, X-ray diffraction and X-ray photoelectric spectroscopies. A very clear 2D crystal pattern of graphene is observed in the HRTEM image of the carbon product prepared from the cellulose 2D crystal. As a control, in a parallel experiment, multi-layer graphene (or graphite) is obtained from the cellulose bundle crystal. The following possible mechanism is proposed. During carbonization of the cellulose 2D crystal, the glucose units (C6H10O5)n lose oxygen and hydrogen atoms in the form of water, and the six carbon units (C6)n reorganise, forming the graphene 2D crystal at the structural basis of the 2D crystal of cellulose. The findings from this study provide an economical and environmentally friendly approach to the fabrication of graphene and extend the applications of sustainable biomass cellulose.

A protocol of Mn(OAc)3–mediated α,β-hydroxy-phosphorylation of alkenes with phosphorus-centered radicals generated from diphenylphosphine oxide is described. A combination of steric and electronic factors played an important role in this reaction. The reactions of styrenes bearing ortho-substituent gave the selective β-hydroxyphosphine oxide products.

The fuzzy comprehensive assessment method has proven effective in increasing the understanding of complex systems, including environmental systems. A fuzzy comprehensive assessment model of environmental impact of petroleum project is presented. The model utilizes factor set to represent environmental impact factors and evaluation set to environmental impact level. And it constructs the evaluation index system based on "pressure-state-response" model, and selects advantage indicators using the analysis hierarchy process, and determines the grading standard of environmental impact level. The results produced by this model reveal the degree of environmental impact caused by petroleum project.

A new heterogeneous catalyst Fe-Mn/GAC (iron and manganese were loaded into activated carbon particles) was prepared, which had a better catalytic reactivity to decompose H2O2 compared with Fe/GAC and Mn/GAC. The removal rate of Orange IV increased more than 10% with this catalyst compared with Fe/GAC and Mn/GAC. The effect of the initial concentration of H2O2, the initial dye concentration, the initial catalyst concentration, the initial pH and temperature on the reaction rate constant were also studied. The activated energy for Fe-Mn/GAC catalyzed oxidation of the dye was determined to be 66.16KJ/mol. Reuse of catalyst did not decrease the removal rate of Orange IV. The tert-butanol experiment indicated that there were not only hydroxyl radicals but also other active species in the system.

A new heterogeneous Fenton-like catalyst of Fe/S/GAC was prepared by granular activated carbon (GAC) soaked in solution of (NH4)2S2O8 and Fe(NO3)3. The effect of the concentration of (NH4)2S2O8 , Fe(NO3)3, drying temperature and different catalysts on the catalytic reactivity of catalyst was discussed. The removal rate of Orange IV was used to express the catalytic reactivity of the catalyst. The prepared catalysts were characterized by X-ray diffraction (XRD), specific surface area (BET) and scanning electron microscopy (SEM). The removal rate of Orange IV followed second-order kinetics. The catalyst of Fe/S/GAC has higher catalytic activity than that of Fe/GAC.

Natural dyes are normally unstable to photooxidation by UV light. We have measured the stability of a number of natural dyes in combination with high concentrations of antioxidants, excited state quenchers, and UV absorbers. We find that certain combinations, including indigo/BHT, methylene blue/p-benzoquinone, and methylene blue/triethylamine show enhanced stability in solution and/or in thin polymer films. By comparing solutions and films of the mixed components with solutions and films of the antioxidant placed between the dye and UV source, we can show that the effect is not UV screening but is due to some form of intermolecular chemistry. We believe that this effect may account for the high stability of natural dyes in plant tissues, such as the skins of fruit, and may be usable to stabilize natural dyes in foods or textiles, especially if suitable nanoparticle structures can be developed.

Solid super acid (S2O82-/FexOy-CuOx) was prepared and used as a heterogeneous Fenton-like catalyst to decompose H2O2for the degradation of refractory dye Orange IV in water. The factors that affected the degradation of Orange IV were discussed in this heterogeneous Fenton-like system. The catalytic activity of S2O82-/FexOy-CuOxwas evaluated by the degradation of Orange IV and the decomposition of H2O2. The results show that the catalyst S2O82-/FexOy-CuOxhas a good catalytic activity. The reaction follows pseudo-first-order kinetics; the reaction rate constant has a good relationship with the concentration of H2O2. The degradation rate of Orange IV and the decomposition rate of H2O2increase with the increase of temperature and the dosage of catalyst whereas it decreases with the increase of the initial concentration of Orange IV and the initial pH.

Chlortoluron chlorination is studied in the pH range of 3–10 at 25 ± 1 °C. The chlorination kinetics can be well described by a second-order kinetics model, first-order in chlorine and first-order in chlortoluron. The apparent rate constants were determined and found to be minimum at pH 6, maximum at pH 3 and medium at alkaline conditions. The rate constant of each predominant elementary reactions (i.e., the acid-catalyzed reaction of chlortoluron with HOCl, the reaction of chlortoluron with HOCl and the reaction of chlortoluron with OCl − ) was calculated as 3.12 (± 0.10) × 10 7 M −2 h −1 , 3.11 (±0.39) × 10 2 M −1 h −1 and 3.06 (±0.47) × 10 3 M −1 h −1 , respectively. The main chlortoluron chlorination by-products were identified by gas chromatography–mass spectrometry (GC–MS) with purge-and-trap pretreatment, ultra-performance liquid chromatography–electrospray ionization-MS and GC-electron capture detector. Six volatile disinfection by-products were identified including chloroform (CF), dichloroacetonitrile, 1,1-dichloropropanone, 1,1,1-trichloropropanone, dichloronitromethane and trichloronitromethane. Degradation pathways of chlortoluron chlorination were then proposed. High concentrations of CF were generated during chlortoluron chlorination, with maximum CF yield at circumneutral pH range in solution.

A new Fenton-like catalyst was prepared to degrade Orange IV in water by catalytic decomposition of H2O2. The optimal preparation conditions were discussed. The catalytic activity of catalyst was evaluated by the degradation of Orange IV and the decomposition of H2O2. The results show that solid super acid (S2O82-/FexOy) soaked in (NH4)2S2O8 is the most effective catalyst among the synthesized iron oxides soaked in other oxidants. The optimal conditions for solid super acid preparation are calcined at 500 for 2 h in the air.

Solid super acid(S2O82-/FexOy-CuOx)was prepared and used as a Fenton-like catalyst to decompose H2O2 for the removal of orgnanic pollutants in water. The catalytic activity of S2O82-/FexOy-CuOx was evaluated by the degradation of organic pollutants and the decomposition of H2O2. The results show that the catalytic activity of S2O82-/FexOy-CuOx to decompose H2O2 is higher than that of S2O82-/FexOy. The reason for this may be due to the dissolved of Fe2+ from the S2O82-/FexOy-CuOx, and the concentration of dissolved of Fe2+ is proportional to the concentration of organic pollutants in water. The degradation rate of phenol by the catalyst of S2O82-/FexOy-CuOx is obviously higher than that by the catalyst of Fe2+ ion under the same conditions. BET measurements show that the surface area of S2O82-/FexOy-CuOx is larger than that of S2O82-/FexOy.

The Biginelli-type condensation of ethyl acetoacetate/cycloketone, aldehyde and urea/thiourea under solvent-free condition catalyzed by 10% gallium(III) iodide to form dihydropyrimidine-2(1H)-one derivatives was described. This process offered one way to constructing dihydropyrimidine-2(1H)-ones in good to excellent yields with simple procedure and short reaction time.

Dissolved organic nitrogen (DON) measurements for water samples with a high dissolved inorganic nitrogen (DIN, including nitrite, nitrate and ammonia) to total dissolved nitrogen (TDN) ratio using traditional methods are inaccurate due to the cumulative analytical errors of independently measured nitrogen species (TDN and DIN). In this study, we present a nanofiltration (NF) pretreatment to increase the accuracy and precision of DON measurements by selectively concentrating DON while passing through DIN species in water samples to reduce the DIN/TDN ratio. Three commercial NF membranes (NF90, NF270 and HL) were tested. The rejection efficiency of finished water from the Yangshupu drinking water treatment plant (YDWTP) is 12%, 31%, 8% of nitrate, 26%, 28%, 23% of ammonia, 77%, 78%, 82% of DOC (dissolved organic carbon), and 83%, 87% 88% of UV(254) for HL, NF90 and NF270, respectively. NF270 showed the best performance due to its high DIN permeability and DON retention (∼80%). NF270 can lower the DIN/TDN ratio from around 1 to less than 0.6 mg N/mg N, and satisfactory DOC recoveries as well as DON measurements in synthetic water samples were obtained using optimized operating parameters. Compared to the available dialysis pretreatment method, the NF pretreatment method shows a similar improved performance for DON measurement for aqueous samples and can save at least 20 h of operating time and a large volume of deionized water, which is beneficial for laboratories involved in DON analysis. DON concentration in the effluent of different treatment processes at the YDWTP and the SDWTP (Shijiuyang DWTP) in China were investigated with and without NF pretreatment; the results showed that DON with NF pretreatment and DOC both gradually decreased after each water treatment process at both treatment plants. The advanced water treatment line, including biological pretreatment, clarification, sand filtration, ozone-BAC processes at the SDWTP showed greater efficiency of DON removal from 0.37 to 0.11 mg N L(-1) than that at the YDWTP, including pre-ozonation, clarification and sand filtration processes from 0.18 to 0.11 mg N L(-1).

Molecularly imprinted composite membranes for selective binding of erythromycin were synthesized by UV initiated photo-copolymerization using polysulfone ultrafiltration (PSF) membranes as porous supports. The thin imprinted layers deposited on the surface of the support membranes were formed by copolymerization of acrylic acid (AA) as functional monomer and ethylene glycol dimethacrylate (EGDMA) as cross-linker in the presence of erythromycin as template molecule in acetonitrile solution. Fourier transform infrared spectroscopy (FT-IR) was used to study the binding mechanism between the imprinted sites and the template. Scanning electron microscope (SEM) was utilized to visualize surface and cross-sections of membranes to gain better understanding in the analysis of imprinted layers deposited on PSF support membranes. The modification degrees for imprinted and nonimprinted membranes are 2.04 and 2.15 mg/cm2, respectively. Static equilibrium binding and recognition properties of the imprinted and nonimprinted membranes to erythromycin (EM) and its analogue roxithromycin (RM) in aqueous system were tested. The results showed that saturated binding capacity of imprinted membranes to erythromycin was about 0.185 mg/cm2, nearly eight times that of nonimprinted ones, and the selectivity factor of αEM/RM was 3.24. The results of this study implied that the synthesized molecularly imprinted composite membranes could be used as selective separation materials for erythromycin enrichment from water.

Zn-doped gallium nitride (GaN) nanotubes with zigzag morphology have been synthesized by a chemical vapor deposition method. A single-crystalline zigzag nanotube consists of two building blocks with equivalent growth directions, hexagonal cross sections, and about 10 nm wall thicknesses. The formation of the nanotube is attributed to the reduction of electrostatic interaction energy caused by the polar side surfaces of GaN. A room temperature photoluminescence spectrum of Zn-doped GaN nanotubes with zigzag morphology shows two peaks at 2.97 and 2.16 eV, respectively.

A facile and efficient protocol of oxythiocyanation of styrenes with ammonium thiocyanate has been developed. The reaction proceeded at room temperature using oxygen as sole oxidant to afford the α-oxothiocyanates via radical pathway in moderate to good yields. This method is straightforward, green and cost-effective, requires no catalyst and additives.

Controllable depositing of relatively thick inorganic sublayers into organic templates to fabricate organic-inorganic superlattices is of great importance. We report a novel approach to fabricating phospholipid/Ni(OH)(2) superlattices by electrochemical deposition of the inorganic component into solid-supported multilamellar templates. The well-ordered and highly oriented multilamellar templates are produced by spreading small drops of lipid solution on silicon surfaces and letting the solvent evaporate slowly. The templates which are used as working electrodes preserve the lamellar structure in the electrolyte solution. The resulting superlattices are highly oriented. The thickness of the nickel hydroxide is controlled by the concentration of nickel ions in the electrolyte bath. The electron density profiles derived from the X-ray diffraction data reveal that the thickness of the nickel hydroxide sublayers increases from 15 to 27 A as the concentration of nickel nitrate increases from 0.005 mol/L to 0.08 mol/L. We expect that the new method can be extended to depositing a variety of inorganic components including metals, oxides, and semiconductors.

This reaction can be further extended for analogous substrates for the synthesis of indene, benzoannulene, and other heterocyclic skeletons.

Introducing ionic liquids as new structure-controlled additives, Polysulfone (PSf) membranes were prepared by the wet-phase-inversion using 1-(n-Octyl)-3-Methyl limidazolium Hexfluorophosphate [C 8 mim][PF 6 ] or 1-hexadecyl-3-methylimidazolium thiocyanate [C 16 mim][SCN] into the casting solution (PSF/NMP). Scanning electron microscope was utilized to visualize cross-sections and surfaces of the membranes to gain more better understanding the influence of different ionic liquids on the structure and seperation properties of the membrane. With increase of concentration of ionic liquid [C 16 mim][SCN] in casting solutions, the structures of the membranes changed from asymmetric finger pores to the spongy-finger-macrovoid structure of the pores. However, With increase of concentration of ionic liquid [C 8 mim][PF 6 ] in casting solutions, the structures of the membranes changed from asymmetric finger pores, lengthened macroporous pores, to the close macrovoid pores. Fininally, permeation properties of the membranes was investigated. The result indicated that at the 4∶76 ratio of [C 16 mim][SCN]/NMP, the retention rate and solution flux of the prepared membrane are 97.1% for PEG10000 and 48.7 L· h−1· m−2. At the 4∶76 ratio of [C 8 mim][PF 6 ]/NMP in the polymer solution, the retention rate of the membrane is 92.3% for PEG10000 and solution flux is 33.7 L· h−1· m−2. Meanwhile, the two ionic liquids were used as plasticizers, according the thermal properties of the membranes.

Ionic Liquids(ILs) as one kind of green solvents was studied and applied more and more with the development of green chemistry, because of their unique physical and chemical properties. The intermediate 1-butyl-3-methylimidazolium bromide was synthesized from the materials of N-methylimidazolium and 1-butylbromide; 1-butyl-3-methylimidazolium terafluoroborate and hexafluorophosphate were synthesized with anion exchange reaction. the intermediate's synthesis mechanism is nucleophilic substitution reaction. Structures of the three ionic liquids were indicated by FT-IR, 1HNMR and Computer Simulation. At last, the thermal properties, conductivity and dissolved performance of the Ionic Liquids were investigated. The results of this work could provide meaningful insights in the understanding of the use of imidazoled ILs.

In the presence of a template molecule, roxithromycin (RM), novel molecularly imprinted polymer (MIP) microspheres were prepared by one-step precipitation polymerization using methacrylic acid (MAA), ethylene glycol dimethacrylate (EGDMA) and 2'2-azobisisobutyronitrile (AIBN) as functional monomer, cross-linker and initiator, respectively. The scanning electron microscopy exhibited that the imprinted polymers synthesized were uniform spheres with the diameter of about 3µm. The results of equilibrium rebinding experiments showed that the binding ability of imprinted microspheres to RM was much higher than that of non-imprinted ones and the imprinted polymers possessed a fast adsorption dynamics. Scatchard plot analysis revealed that there were two types of binding sites formed in the imprinted polymer microspheres. The dissociation constant and the apparent maximum binding capacity were 2.63×10-2µmol/mL and 14.65µmol/g for the high affinity binding sites and 1.05 µmol/mL, 83.16µmol/g for the low affinity binding sites. The specificity of the imprinted microspheres was investigated by binding analysis with RM and its analogues, erythromycin (EM), azithromycin (AM) and erythromycin ethylsuccinate (EE). Compared to those three structurally similar compounds, the imprinted microspheres exhibited a high selective recognizable capacity towards the template. The results of this study implied that the obtained imprinted microspheres can be utilized as specific absorbents for the separation, enrichment, and analysis of roxithromycin in environmental water or food.

Nanobubbles with ultrathin single crystal shells, a new kind of closed nanostructure, have been synthesized from a nonlayered indium oxide semiconductor.

The interaction potential energies of water–water and water–methane in structure-I unit cell of methane hydrate are calculated from 2.1 to 8.0 A using density functional theory (DFT) B3LYP/TZVP. The curves of potential energies are corrected for basis set superposition error (BSSE) and dispersion interaction using a 4-term L–J (4,6–8,12) correction equation, which is derived from CCSD(T)/cc-pVTZ calculations of water–water and water–methane molecular pairs, using least squares curve-fitting. The methane hydrate unit cell is a regular water dodecahedron cell consisting of 20 water molecules with a methane molecule in the center. The geometries of water and methane are optimized at CCSD(T)/cc-pVTZ level. The BSSE-corrections are calculated for water–water and water–methane interaction energies as functions of the side length, l , of the dodecahedron cell at B3LYP/TZVP level in the range from 2.1 to 8.0 A. The BSSE CP-corrected and dispersion-corrected potential energy surfaces (PES) of water–water and water–methane are useful for molecular dynamics simulation of gas clathrate–hydrates.

Reactions of acyclic ketones and o-phenylenediamines under solvent- and catalyst-free conditions have been developed for the preparation of dihydrobenzimidazoles. This method can also be used for the synthesis of other heterocyclic compounds such as dihydrobenzothiazoles and perimidines.