H2O effects on the inclusional complexation of β-cyclodextrin with sodium 2-naphthalenesulfonate in capillary electrophoresis and UV spectrophotometry

In capillary electrophoresis, deuterium isotope effects of ²H₂O in the running buffer on the equilibrium constant (K) for the formation of an inclusion complex between β-cyclodextrin and sodium 2-naphthalenesulfonate (2NS) have been investigated. The K value for ²H₂O is 27% greater than that for H₂O. A similar trend in the K value of 2NS has been obtained from the results employing a UV spectrophotometric method.     

Liaison hydrogène O-H-O symétrique : II. Spectres de vibration des oxalates acides de lithium hydratés et anhydres

Infrared and Raman spectra of polycrystalline LiHC₂O₄, LiHC₂O₄, · H₂O and their D and ⁶Li containing isotopic derivatives have been investigated at 300 and 90 K in the 4000–50 cm⁻¹ region. All the internal and external optically active modes of lithium hydrogen oxalate monohydrate have been identified and an assignment is given. The spectroscopic data are consistent with X-ray data showing an asymmetric short hydrogen bond with a positive deuterium isotope effect. The dehydration of LiHC₂O₄, · H₂O changes the type of hydrogen bond which becomes symmetric of the double minimum type. The deuteration of LiHC₂O₄, on the other hand. weakens the hydrogen bond and makes it asymmetric again. The asymmetry appears more pronounced at low temperature.     

Effect of high coverages on proton transfer in the zeolite/water system

The density functional theory and Hartree–Fock methods were used to investigate the proton transfer reaction for a series of model clusters of zeolite/(H₂O)_n; n=1,2,3, and 4. Without promoted water, the hydrogen-bonded dimer of the water/zeolite system exists as a simple hydrogen-bonded complex, ZOH.(H₂O)₂, and no proton transfer occurs from zeolite to water. The third promoted water, ZOH(H₂O)₂H₂O, was found to induce a pathway for proton transfer, but at least addition two promoted molecules, ZO(H₃O⁺)H₂O(H₂O)₂, must be involved for complete proton transfer from zeolite to H₂O. The results show that the hydronium ion in water cluster adsorbed on zeolite, ZO(H₃O⁺)(H₂O)₃, can considerably affect the structure and bonding of the hydrogen-bonded dimer of water. The OO distance is contracted from 2.818 Å found in the neutral complex, ZOH(H₂O)₄, to 2.777 Å for ion-pair complex, ZO(H₃O⁺)(H₂O)₃. The distance between the oxygen of the hydronium ion and the zeolitic acid site oxygen is predicted to be 2.480 Å which is in good agreement with the experimentally observed value of 2.510 Å. The corresponding density functional adsorption energy of the high coverages of adsorbing molecules on zeolite is calculated to be −9.14 kcal/mol per molecule at B3LYP/6-311+G(d,p) level of theory and compares well with the experimental observation of −8.20 kcal/mol.     

Chemical Evolution of LiCoO2 and NaHSO4·H2O Mixtures with Different Mixing Ratios During Roasting Process

Mixtures of NaHSO₄·H₂O and LiCoO₂ extracted from spent lithium-ion batteries were prepared with molar ratios of 1:1, 1:2 and 1:3. The chemical evolution of the LiCoO₂ and NaHSO₄·H₂O mixtures during the roasting process was investigated by means of thermogravimetric analysis and differential scanning calorimetry (TG-DSC), X-ray diffraction(XRD), scanning electron microscopy(SEM), and X-ray photoelectron spectroscopy (XPS). The results show that the chemical reactions in the LiCoO₂ and NaHSO₄·H₂O mixtures proceed during the roasting process. The Li element in the product of the roasting process is in the form of LiNa(SO₄). With the increase of the proportion of NaHSO₄·H₂O in the mixtures, the Co element evolves as follows: LiCoO₂→Co₃O₄→ Na₆Co(SO₄)₄→Na₂Co(SO₄)₂. The roasting products exhibit dense structures and irregular shapes, and the bonding energy of Co increases.     

五元体系LiCl-NaCl-KCl-MgCl2-H2O 25℃时溶度研究和等温蒸发实验

本文首次给出了五元体系LiCl-NaCl-KCl-MgCl₂-H₂O 25℃时的溶度图。讨论了氯化锂对体系中其它盐类的盐析作用。还报道了几个合成卤水在静态条件下的等温蒸发结果。研究表明所得平衡相图可作为此类盐卤析盐顺序的理论依据。     

Measured and Predicted Solubility Phase Diagrams of Quaternary Systems LiBr-NaBr-MgBr2-H2O and LiBr-KBr-MgBr2-H2O at 298.15 K

The stable phase equilibria of quaternary systems LiBr-NaBr-MgBr₂-H₂O and LiBr-KBr-MgBr₂-H₂O at 298.15 K were studied by both experimental measurement(isothermal solution saturation method) and theoretical prediction(Pitzer model). The solubilities of the saturated solution have been determined experimentally and two stable phase diagrams and relevant water diagrams of the two quaternary systems were obtained. Results show that quaternary system LiBr-NaBr-MgBr₂-H₂O is hydrate II type as NaBr and NaBr·2H₂O coexistence. Its phase diagram consists of only one invariant point, four univariant curves, and five crystallization fields. The quaternary system LiBr-KBr-MgBr₂-H₂O is a complex type as the double salt KBr·MgBr₂·6H₂O formed. In addition to this double salt, the three single salts LiBr·2H₂O, KBr and MgBr₂·6H₂O also crystallize. In this paper, the solubilities of phase equilibria in above quaternary systems were also calculated by the Pitzer's electrolyte solution model. All the needed parameters can be obtained from the literature or be fitted by experimental data. On the Basis of the experimental and calculated results, the phase diagram of the quaternary system was plotted for comparison. It shows that the calculation results are consistent with the experimental ones.     

The coupling effect of the thermodynamic swelling process in pervaporation

In order to analyze the coupling effect in thermodynamic swelling process, the relationship between the activity and volume fraction of each component within membrane was defined as ^m_i=γ^m_iφ^m_i. The concept of reference state in thermodynamic swelling process which only considered the interaction between individual component and membrane matrix was also set up. The difference of activity coefficient of each component within the membrane from reference state reflected the contribution of coupling effect to thermodynamic swelling process. For chitosan and H₂SO₄ crosslinking chitosan membrane the influence of coupling effect on selectivity of H₂O in thermodynamic swelling process could be described from distribution coefficients and competition distribution coefficients of H₂O and EtOH successfully. The interaction between H₂O and the membrane matrix dominated the activity coefficient of H₂O within the membrane, and the coupling effect between H₂O and EtOH within the membrane only had a little influence on the activity coefficient of H₂O. However, the activity coefficient of EtOH was dominated strongly by the coupling effect between H₂O and EtOH within the membrane. This was attributed to the large amount of H₂O present in the membrane. The distribution coefficient of EtOH, k^m₂ and competition distribution coefficient of membrane k^m₁₂ directly determined the selectivity of H₂O in thermodynamic swelling process and the coupling effect between H₂O and EtOH within the membrane had a negative influence on the selectivity of H₂O within the membrane.     

Location of the discotic lamellar-nematic tricritical point and isotope effects in the caesium pentadecafluorooctanoate (CsPFO)/water system as established by 133 Cs N.M.R. spectroscopy

¹³³Cs N.M.R. spectroscopy has been used to locate the discotic lamellar (smectic A)-nematic tricritical point in the CsPFO/H₂O and CsPFO/²H₂O systems. In both systems this occurs at the same volume fraction of 0·25, but at different temperatures (302·05 and 304·80 K, respectively). The phase diagram for the CsPFO/H₂O system has also been studied for the first time and a comparison of the corresponding fixed points shows there to be large isotope effects.     

Solid-liquid Equilibria in the Ternary System (NaCl+SrCl2+H2O) and (KCl+SrCl2+H2O) at 288.15 K and 0.1 Mpa

Solid-liquid phase equilibria of the two ternary systems (NaCl+SrCl₂+H₂O) and (KCl+SrCl₂+H₂O) at T=288.15 K and p=0.1 MPa were studied using the isothermal dissolution equilibrium method. Solubilities of the equilibrium liquid phase were determined, and the solids were also investigated by the Schreinemaker method of wet residues. In the ternary system (NaCl+SrCl₂+H₂O) at 288.15 K, there is one invariant point corresponding to (NaCl+SrCl₂·6H₂O) and two crystallization regions corresponding to NaCl and SrCl₂·6H₂O. The crystallized area of SrCl₂·6H₂O decreased with the increasing temperature, while that of NaCl increased slightly. In the ternary system (KCl+SrCl₂+H₂O) at 288.15 K, there is one invariant point(KCl+SrCl₂·6H₂O) and two crystallization regions corresponding to KCl and SrCl₂·6H₂O. Both systems belong to a simple eutectic type, and neither double salts nor solid solutions were formed. On the basis of Pitzer-Harvie-Weare model, the solubilities of the two systems at 288.15 K were demonstrated. A comparison showed that the calculated solubilities agreed well with the experimental data.     

加拿大油砂沥青减压渣油在CO/H2-H2O作用下的热改质特性研究

以加拿大油砂沥青大于420℃的减压渣油（BVR）为原料,对比研究其在CO/H₂-H₂O和N₂体系中的热改质特性,通过系统分析BVR在H₂-H₂O、CO-H₂O、N₂-H₂O等不同氢源下的热改质特性以揭示CO/H₂-H₂O对渣油热改质的作用机制,最后探讨合成气压力、含水量以及温度对BVR临CO/H₂-H₂O改质生焦倾向的影响。结果表明,与临氮改质相比,相同反应条件下,合成气和水可使BVR热改质的生焦诱导期延长3.5-6.5 min;相同生焦率（约0.1%）时,合成气和水可显著提升BVR热改质降黏率,410℃时相对临氮改质的降黏率为29.1%,而420℃时可达54.6%。比较不同氢源下BVR热改质的生焦诱导期、改质油黏度和安定性、渣油转化率发现,H₂-H₂O、CO-H₂O、N₂-H₂O等均对BVR热改质表现出与CO/H₂-H₂O相同的促进效果,各氢源作用活性的大小顺序为H₂-H₂O > CO/H₂-H₂O > CO-H₂O > N₂-H₂O。由此可知,CO/H₂-H₂O对渣油热改质的促进作用可归因于氢气、CO水热变换新生氢和水热裂解的综合效应,且其中氢气的作用仍最显著。合成气压力、含水量和反应温度可通过影响不同氢源的贡献而调控BVR临CO/H₂-H₂O改质生焦倾向。低成本易获取的合成气可以提供BVR热降黏改质所需氢源,水能够通过CO水热变换反应供出新生活泼氢而协同合成气实现BVR高效改质。     

Radiation induced scavenging of NOx, SO2, H2S from exhaust gases

The theoretical model of exhaust gases radiation induced oxidation was developed. NO, SO₂ and H₂S concentrations curves vs dose calculated by use of this model for mixtures containing N₂ (80.5%), O₂ (11%), H₂O (8.4%), NO (100–600 ppm), SO₂ (150–500 ppm) and H₂S (300–1000 ppm) have been obtained. It has been shown that NO and SO₂ conversion reactions with acids formation go simultaneously with oxidizing reaction of H₂S giving SO₂ as an intermediate substance. These processes were evaluated for different initial concentrations of NO, SO₂ and H₂S. Data established by our simulation calculations show that the electron beam process can be judged as a promising technology for simultaneous removal of SO₂, NO and H₂S from exhaust gases.     

Nd(Gly)2Cl3·3H2O和Pr(Ala)3Cl3·3H2O的热力学性质

利用精密自动绝热热量计测定了Nd(Gly)₂Cl₃·3H₂O在80-357K和Pr(Ala)₃Cl₃·3H₂O在80-374K温区的热容. 根据两个化合物的热容计算出了相对于参考温度298.15K的热力学函数(H_T?H_298.15)和(S_T?S_298.15). 根据热重(TG)分析结果, 提出了这两个稀土化合物可能的热分解机理. 利用溶解-反应恒温热量计测定相关化合物的溶解焓并设计盖斯热化学循环, 计算出了两个化合物的标准摩尔生成焓.     

Diagnostics of water-containing gas mixtures using thermal laser-induced gratings

Laser-induced gratings (LIGs) experiments, employing vibrational-overtone excitation of H₂O molecules through rovibrational transitions of the (2 1 1) ← (0 0 0) band around 820 nm to produce gratings, have been performed in humid ambient air, in a room-temperature cell with neat water vapor or that diluted in buffer gas at pressures of 0.02–4 bar, and in the vicinity of premixed atmospheric pressure CH₄-air flame, with the aim to investigate the feasibilities of the techniques for accomplishing gas diagnostics or tracing H₂O at various temperatures and pressures.

In highly vibrationally-excited H₂O rapid multi-stage collisional thermalization processes occur, and as a result both strong oscillatory (due to standing acoustic waves) and stationary (due to stationary density modulations) contributions to LIGs have been observed in gas mixtures.

Temporal profiles of LIG signals recorded at various conditions of gas mixtures employed have been analysed in frame of a model of a two- or three-stage R–T, V–V′, and V–T collisional relaxation of H₂O and buffer gas molecules. The informative parameters, like adiabatic sound velocity, gas temperature, H₂O mole fraction have been derived. The results of the analysis are presented, demonstrating possibilities and challenges of the technique in application to gas diagnostics.     

Theoretical investigations of structure and enzymatic mechanisms of aspartyl proteinases : Part I. Ab-initio calculations on an active site model: hydrogen diformiate with H2O and H3O

The active site of aspartyl proteinases (Asp) was modelled as two formiates connected with a proton and set in geometry corresponding to Asp 32 and Asp 215 side chain carboxylate groups of endothiapepsin. The shared solvent molecule was alternatively H₂O and H₃O⁺. Their positions and those of hydrogen-bonded protons were optimized using the STO-3G basis set. Full geometry optimizations were made of the hydrogen diformiate complexes with H₂O and H₃O⁺. Asymmetric hydrogen-bonded structures resulted from these calculations, except for the fully optimized complex with H₂O. In the complexes with H₃O⁺, one proton moved consistently to the proximate carboxylic oxygen yielding a neutral, hydrated formic acid dimer. Interaction energies and proton potential energy curves were calculated using the 4-31G basis set. The interaction energy with H₂O was found to be 20.49 kcal mol⁻¹ and 202.75 kcal mol⁻¹ with H₃O⁺.     

气体再燃低NOx燃烧中NO与NHi的反应机理研究

采用量子化学密度泛函理论(DFT)对NO与NH_i自由基的反应机理进行了研究,并结合经典过渡态理论对各反应速率常数进行了计算。结果表明,NO与NH₂自由基的反应体系可通过六个反应通道形成N₂+H₂O、N₂O+H₂和N₂H+OH。从能量变化和反应速率两方面考虑,产物N₂+H₂O最容易生成,其最佳反应通道为NO+NH₂→→N₂+H₂O;NO与NH自由基的反应体系可通过七个反应通道形成N₂+OH、N₂O+H和N₂H+O;其中,N₂+OH最容易生成,最佳反应通道为NO+NH→→N₂+OH。比较发现, NH比NH₂自由基更易与NO发生反应生成N₂。因此,在实际运行中改变操作条件,实现NH₂等向NH方向转化,有利于NO_x的还原。     

X-ray crystal structure and vibrational spectra of hydrazides and their metal complexes. Part II. Hexaaquacobalt(II)bis(phthalhydrazidato)tetrahydrate

The hexaaquacobalt(II)bis(phthalhydrazidato)tetrahydrate, [Co(H₂O)₆](C₈N₂O₂H₅)₂·4H₂O is examined using single crystal X-ray diffraction analysis. The crystals are triclinic, space group , with a = 9.757(1), b = 10.955(2), c = 11.106(1),  = 100.79(2), β = 90.35(3), γ = 91.54(1) and Z = 2. In [Co(H₂O)₆](C₈N₂O₂H₅)₂·4H₂O, the cobalt(II) is coordinated by six water ligands and the [Co(H₂O)₆]²⁺ is associated with the two O-deprotonated phthalhydrazidato ions only by hydrogen bonds. The infrared and Raman spectra of phthalhydrazide (PH) and infrared spectra of deuterated derivative phthalhydrazide (PD) and of [Co(H₂O)₆](C₈N₂O₂H₅)₂·4H₂O are reported. The theoretical wavenumbers, infrared intensities and Raman scattering activities have been calculated using density functional (B3LYP) method with the 6-311++G(d,p) basis set. The calculated potential energy distribution has proved to be of great help in assigning the spectra PH, its deuterated derivative and [Co(H₂O)₆](C₈N₂O₂H₅)₂·4H₂O. The results from natural bond orbital (NBO) analysis for keto-hydroxy form of PH are presented.     

Optimised hydrothermal synthesis of multi-dimensional hybrid coordination polymers containing flexible organic ligands

In this paper, we summarise our recent research interest in the hydrothermal synthesis and structural characterisation of multi-dimensional coordination polymers. The use of N-(phosphonomethyl)iminodiacetic acid (also referred to as H₄pmida) in the literature as a versatile chelating organic ligand is briefly reviewed. This molecule plays an important role in the formation of centrosymmetric dimeric [V₂O₂(pmida)₂]⁴⁻ anionic units, which were first used by us as building blocks to construct novel coordination polymers. Starting with [V₂O₂(pmida)₂]⁴⁻ in solution, we have isolated [M₂V₂O₂(pmida)₂(H₂O)₁₀] species (where M²⁺ = Mn²⁺, Co²⁺ or Cd²⁺) via the hydrothermal synthetic approach, which were then employed for the construction of [CdVO(pmida)(4,4′-bpy)(H₂O)₂]·(4,4′-bpy)_0.5·(H₂O), [CoVO(pmida)(4,4′-bpy)(H₂O)₂]·(4,4′-bpy)_0.5, [Co(H₂O)₆][CoV₂O₂(pmida)₂(pyr)(H₂O)₂]·2(H₂O) and [Cd₂V₂O₂(pmida)₂(pyr)₂(H₂O)₄]·4(H₂O) by the inclusion of bridging organic ligands in the reactive mixtures, such as pyrazine (pyr) and 4,4′-bipyridine (4,4′-bpy). These materials can contain channel systems, and exhibit magnetic behaviour, not only due to the V⁴⁺ centres but also to the transition metal centres which establish the links between neighbouring dimeric [V₂O₂(pmida)₂]⁴⁻ anionic units. A closely related anionic moiety, [Ge₂(pmida)₂(OH)₂]²⁻, was engineered to allow the study of such crystalline hybrid materials using one- and two-dimensional high-resolution solid-state NMR.     

胜利褐煤在合成气/复合溶剂体系下液化性能研究

在合成气(H_2+CO)/复合溶剂(THN+H_2O)体系和氢气/四氢萘(H_2/THN)体系下考察了胜利褐煤液化性能,并对液化产物沥青烯和前沥青烯进行了红外光谱分析。结果表明,合成气/复合溶剂体系下胜利褐煤液化转化率和油产率显著高于H_2/THN体系,当反应条件为H_2∶CO=1∶1(体积比)、THN∶H_2O=1∶1(体积比)、反应温度400℃、初压4 M Pa、时间30 min、催化剂添加量3%(Fe的质量计)和硫铁原子比1.2时,胜利褐煤液化转化率和油产率分别为88.79%和55.47%,比H_2/THN体系分别高出8.00%和7.54%。据此表明,在合成气/复合溶剂体系下,水煤气变换反应产生的氢活性更高,对煤和液化产物前沥青烯具有更好的加氢效果,同时四氢萘的存在稳定了煤热解自由基和溶解分散液化重质产物沥青烯和前沥青烯,这些因素的协同作用提高了煤液化转化率和油产率。实验表明,合成气/复合溶剂体系是一种新的褐煤直接液化技术。     

在288.15K时H3BO3-MgCl2-MgSO4-H2O四元体系的溶解度等温线

研究了MgCl₂-MgSO₄-H₂O、H₃BO₃-MgCl₂-H₂O、H₃BO₃-MgSO₄-H₂O三个三元体系及由它们所组成的四元体系H₃BO₃-MgCl₂-MgSO₄-H₂O在288.15K的溶解度等温线。确定了六水硫酸镁的存在,讨论了各相之间的关系及各化合物相互间的盐析作用。     

Thermal decomposition study on mixed ligand thymine complexes of divalent nickel(II) with dianions of some dicarboxylic acids

Thermal decomposition of mixed ligand thymine (2,4-dihydroxy-5-methylpyrimidine) complexes of divalent Ni(II) with aspartate, glutamate and ADA (N-2-acetamido)iminodiacetate dianions was monitored by TG, DTG and DTA analysis in static atmosphere of air. The decomposition course and steps of complexes [Ni(C₅H₆N₂O₂)(C₄H₅NO₄)²⁻(H₂O)₂]·H₂O, [Ni(C₅H₆N₂O₂)(C₅H₇NO₄)²⁻(H₂O)₂]·H₂O and [Ni(C₅H₆N₂O₂)(C₆H₈N₂O₅)²⁻(H₂O)₂]·1.5H₂O were analyzed. The final decomposition products are found to be the corresponding metal oxides. The kinetic parameters namely, activation energy (E*), enthalpy (ΔH*), entropy (ΔS*) and free energy change of decomposition (ΔG*) are calculated from the TG curves using Coats–Redfern and Horowitz–Metzger equations. The stability order found for these complexes follows the trend aspartate > ADA > glutamate.