Molecular Dynamics Simulation of the Melting and Coalescence in the Mixed Cu–Ni Nanoclusters

Molecular dynamics simulation with the embedded atom method was applied to study the melting and coalescence in the mixed Cu–Ni nanoclusters. The validity of the model was tested by examining the consistency of the phase diagrams of the (Cu_682-mNi_m)₆₈₂ and (Cu_1048-mNi_m)₁₀₄₈ clusters with the Cu–Ni bulk. The coalescences of two mixed Cu–Ni clusters and a pure Cu cluster with a pure Ni cluster were simulated. The coalesced temperature T _c forming a liquid complex and melting temperature T _m of the cluster with the same size were compared. The results indicate that T _c is higher than T _m for the coalescences of both (CuNi)₆₈₂ and (CuNi)₁₀₄₈ clusters. The analysis of the relationship between the Cu–Ni bond content and T _c indicates that the formation of the Cu–Ni bonds contributes a lot to the phenomenon.     

High-Tc superconductivity in the ErBaCuO and related systems

ErBa₂Cu₃O₇ and Er_0.5Y_0.5Ba₂Cu₃O₇ are both high-T_c superconductors attaining zero resistance above 80 K. Preliminary studies indicate that Yb_1−xY_xBa₂Cu₃O₇ also exhibits zero resistance above 77 K.     

Preparation and Electrochemical Properties of the Pd-modified Cu Electrode for Nitrate Reduction in Water

The reduction of nitrate has gained renewed attention due to environmental problems like overfertilization and the increasing costs of purification of drinking water. The usual techniques (e.g. ion-exchange and biofiltration) have some disadvantages1. So …     

MHD mixed convection in an inclined cavity containing adiabatic obstacle and filled with Cu–water nanofluid in the presence of the heat generation and partial slip

Journal of Thermal Analysis and Calorimetry - In the present paper, the performance of the graphene oxide in the solar steam generation has experimentally been examined. For this purpose, a setup...     

Synthesis and Structure of Complexes Formed in the CuCl2–Cu–N-allylquinolinium Chloride System

The crystals of [C₉H₇N(C₃H₅)]₂Cu^IICl₄(IV) were obtained through ac electrochemical synthesis using CuCl₂· 2H₂O, N-allylquinolinium chloride, and copper electrodes in an ethanol-benzene medium. These crystals transformed with time into crystals of the [C₉H₇N(C₃H₅)][Cu^IICl₃(C₉H₇N)] complex (V). When tin(II) chloride was added to the initial reagents, the [C₉H₇N(C₃H₅)]Cu^I ₂Cl₃complex (VI) was obtained. The X-ray diffraction analysis (DARCh-1 autodiffractometer, MoK radiation, Zr filter) indicated that complexes IVand Vcrystallize in the triclinic system: space group P ; for IV, a= 12.817(4), b= 10.435(3), c= 9.606(3) Å, = 97.94(2)°, = 107.28(2)°, = 95.99(2)°, V= 1200.6(6) ų, Z= 2; for V, a= 16.992(5), b= 8.243(2), c= 7.345(3) Å, = 91.89(3)°, = 91.19(3)°, = 88.18(3)°, V= 1027.5(6) ų, Z= 2. Crystals VIare monoclinic, space group P2₁/n, a= 13.578(5), b= 15.079(4), c= 6.953(4) Å, = 105.08(4)°, V= 1370.6(10) ų, Z= 4. Structures IV–VIconsist of N-allylquinolinium cations and different anions: isolated [CuCl₄]^2–tetrahedrons (IV), [C₉H₇NCuCl₃]^–tetrahedrons (V) containing a quinoline molecule, and a polymer chain |[Cu^I ₄Cl₆]^2–} _n (VI) in which two independent metal atoms have trigonal-pyramidal and planar-trigonal environments. The C=C bond of the allyl group is not involved in cooordination with the Cu(I) atom.     

Inclusion Complexation of Carbaryl and β-Cyclodextrin in Solution and in the Solid State

This study was carried out with the aim ofinvestigating the interactions between-cyclodextrin and carbaryl, a carbamatepesticide, and their effect on some physico-chemicalproperties of carbaryl, such as aqueous solubility andlipophilicity. The interactions between carbaryl and-cyclodextrin were thoroughly investigated bothin solution and in the solid state. The effect of-cyclodextrin on the aqueous solubility ofcarbaryl was evaluated by the phase solubility method.The amount of carbaryl dissolved increased linearlywith the addition of -cyclodextrin according toan A_L type plot and without precipitation of thecomplex. The apparent stability constant of thecomplex was 289 ± 21 M^-1, assuming a 1 : 1stoichiometry; this value was confirmed by a methodbased on circular dichroism measurements.Equimolar carbaryl/-cyclodextrin solid systemswere prepared by physical-mixing and freeze-drying,and fully characterised by Differential ScanningCalorimetry, X-ray powder diffractometry and FourierTransform Infra-Red analysis. The results of the solidstate study demonstrated that the freeze-drying methodyields a system with a high degree of amorphisationand yields an inclusion complex.The dissolution profile of the pesticide was affectedby the physico-chemical properties of each solidsystem, the freeze-dried form dissolving more rapidly. However, the physical association of-cyclodextrin and carbaryl enhanced the aqueoussolubility of the insecticide as well.     

Segregated self-assembly and pillaring action of aliphatic dicarboxylic acids in the super structure of Cu–picolinate complexes

Three new supramolecular assemblies of co-crystallized metal complexes and aliphatic dicarboxylic acids, {[Cu(pic)₂(H₂O)₂](H₂mal)}_n (1), {[Cu(pic)₂(H₂O)₂](H₂mal)₂(H₂O)₂}_n (2) and {[Cu(pic)₂(MeOH)](H₂succ)}_n (3) {Hpic = 2-picolinic acid, H₂mal = malonic acid and H₂succ = succinic acid} have been synthesized and characterized by X-ray single-crystal structure determination. The crystal packings of the complexes reveal that supramolecular associations of the monomeric complex units lead to the formation of layers through hydrogen bonding. In all the complexes, the dicarboxylic acid units connect the 2-D layers to act as pillars. The interaction between water molecules and the dicarboxylic acid plays an important role in the overall supramolecular assembly.     

Studies on the Peptides and Polysaccharides in Pollen

The peptides RP3I and PSPP1-4 were purified from the rape and the Papaver Somniferunpollens, respectively. Their sequences and physiological activities were determined and synthesized ex-cept PSPP1. The polysaccharides TAA-C and CPA-E were obtained from Typha Angustifilia andCodonopsis Pilosula pollens, respectively. Their partial characterization and structures were studied.     

Jahn-Teller effects on π-stacking and stereoselectivity in the phenylethaniminopyridine tris-chelates Cu(NN')3(2+)

Optically pure phenylethaniminopyridine (S(C)-L) tris-chelates of Fe(II) and other first row transition metal systems have previously been shown to give exclusively the fac structures in the solid state. Here it is shown by powder X-ray diffraction that the complex [CuL(3)][ClO(4)](2) crystallises exclusively as the mer isomer, although--for a given absolute configuration of the ligand--of the same helicity (Δ/Λ) as that displayed by the other metal complexes. The similar ligand R(C)-L(F), which contains a peripheral (19)F spin label, gave [CuL(F)(3)][ClO(4)](2) which also adopts exclusively the mer structure in the crystal, but is shown by NMR spectroscopy to have a fac:mer ratio of 1:6 in solution at low temperature. Molecular mechanics calculations for a number of isomers and conformers are consistent with the presence of such a mixture of isomers in solution for both complexes. The origin of the difference in behaviour between Fe(II) and Cu(II) is the presence of a Jahn-Teller distortion (and the generally longer M-N bonds) in the Cu(II) complexes. This disturbs intra-ligand π-stacking, leading to the poor fac/mer stereoselectivity while leaving enantioselectivity Δ/Λ apparently unaffected.     

Correlation Analysis of the Runoff of the Rivers and the Seisms in China

In recent hundred years the annual discharge variations of the Changjiang River (represented by the Yichang station) and the Huanghe River (represented by Shanxian and Tangnaihe, respectively) have closely related to the geographical distribution of the earthquakes coming about in China in the same year, Both the occurrence of the destructive seism or seismic swarm in the river basins and the disappearance of the shocks in the east and south of the basins are the conditions that the Changjiang and Huanghe Rivers are the high flow while that the strong earthquake of magnitude 7 or more occurred in North China is the condition for the Changjiang low flow year and that of 6 or more in the Qilian Mountains area is for the Huanghe River. In the latter part of this paper, a 2-year sample is given to explain that the conditions of the 2 rivers being high flow years are that the north-south seismic belt is active and in the meanwhile no seism occurred in South China, and those of the low flow year are that the     

The effect of Cu–Zn distribution in zincian malachite on the formation of individual CuO and ZnO particles

Journal of Thermal Analysis and Calorimetry - Cu–Zn distribution in zincian malachite was regulated in preparation process, and its effect on the formation of CuO and ZnO during the thermal...     

Studies on the Halogen Substituted β-Amino Acids and Their Cu(Ⅱ) Coordination Complexes in Crystallography

Halogen substituted β-amino acids, D,L-3-amino-3-(4-fluoro)phenylpropionic acid(D,L-HL1, 1) and D,L-3-amino-3-(4-bromo)phenylpropionic acid(D,L-HL2, 2), as well as their Cu(Ⅱ) coordination complexes[Cu(L1)₂(CH₃OH)₂]·2CH₃OH(3) and[Cu(L2)₂(CH₃OH)₂]·2CH₃OH(4) were investigated and their single crystal structures were discussed in details. Supramolecular helical chains were found in β-amino acids 1 and 2 while there was no helix in their coordination complexes 3 and 4. The formation of supramolecular helixes could be due to the hydrogen bonds between terminal-NH³⁺ and adjacent-COO^- in β-amino acids 1 and 2. While, this kind of hydrogen bonds could not be observed in their Cu(Ⅱ) coordination complexes 3 and 4, in which central-symmetrical dimers could be formed via coplanar coordinated bonds(N-Cu-O) between-NH₂ and-COO^-.     

Comparative selectivities of two copper-based catalysts: Mixed Cu?Cr and Cu?Al oxides for allylic alcohol reactions in the presence of molecular hydrogen

In the presence of mixed copper-chromium (aluminium) oxide, allylic alcohols react with molecular hydrogen and lead to several primary products. This is due to the simultaneous presence of two active sites in the mixed oxides. Copper species (Cu⁺) are responsible for hydrogenation (HYD) and the chromium (Cr³⁺) (aluminium [Al³⁺]) species for the isomerization (I) and the hydrodeoxygenation (HDO) reactions. However, the stronger acidic character of Al³⁺, compared with Cr³⁺, entails some differences evidenced by the HYD/(I+HDO) and HDO/I ratios.

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- () , . . (Cu⁺ (), (Cr³⁺) ( Al³⁺) (), (). , Al³⁺ Cr³⁺ , /(+) /.

     

Thermodynamic parameters of the formation of deprotonated single-ligand complexes in the Cu(II)−triglycine system in aqueous solutions

Heat effects arising from interactions between triglycine solutions and Cu(NO₃)₂ solutions are studied at 298.15 K and ionic strengths of 0.2 to 1.0 (KNO₃) via isothermal calorimetry. Using experimental data, enthalpies of formation are calculated for species CuH_?1L, CuH_?2L^?, and CuH_?3L^2?, along with Δ_rH°, Δ_rG°, and Δ_rS° of the complexation process. A relationship is revealed between the structures of deprotonated single-ligand triglycine complexes of Cu(II) and the thermodynamic parameters of their formation.     

Analysis of the interaction energy in the Cu+-H2O and Cl−-H2O systems,with CP corrections to the BSSE of the separate terms,and MC simulations of the aqueous systems with and without CP corrections

The interaction energyE of the systems Cu⁺-H₂O and Cl^–-H₂O has been computed over a wide range of distances and orientations with the MINI-1 basis set in the SCF approximation. The interaction energy has been decomposed according to the Kitaura-Morokuma scheme, with and without counterpoise (CP) corrections to the basis set superposition error. The importance of this correction is analysed by its effect upon Monte Carlo calculations of the Cu⁺-water and Cl^–-water systems, using two-body potentials without and with CP corrections. The effect of CP corrections on theE analysis is similar to that found in other systems of analogous composition (of the general type ion plus neutral ligands), but with significant differences in the details. The effect of the CP corrections to the interaction potential, and then on the results of the Monte Carlo simulations, is small for the Cu⁺ ion, but remarkable for the Cl^– ion.     

Relationship between the Cu content and thermal properties of Al–Cu alloys for latent heat energy storage

Current Al alloys still have shortcomings in their volumetric latent heat (LHV), compatibility and high-temperature inoxidizability, which limit their applications in the field of latent heat energy storage (LHES). The performance of aluminum alloys can be improved by the addition of Cu. The effects of the Cu content on the phase change temperature, mass latent heat (LHM), LHV, supercooling degree and microstructure of Al–Cu alloys were first studied by means of power-compensated differential scanning calorimetry, density, composition analysis and metallographic analysis. The measured values of the latent heat of Al–Cu alloys have been compared with the theoretically predicted values. The results show that for Al–Cu alloys with 7.3–52.8% Cu, the melting/freezing temperature is 540–655 °C/510–637 °C; the LHM and the LHV are 290–340 J g^?1 and 877–1224 J cm^?3, respectively; and the degree of supercooling is within 10 °C. The LHM and LHV of Al–Cu alloys decrease with the increase in the Cu content; when the content of Cu is over 16.6%, the difference between the theoretical value of the LHM and the measured average of the Al–Cu alloys is within 5%. The LHES phases in Al–Cu alloys are the α-Al and theta phases. Quantitative relationships of the Cu content and metallurgical microstructure with the LHM and LHV of Al–Cu alloys are established, and both theoretical and empirical equations are obtained for the estimation of the latent heat for Al–Cu alloys.     

Calorimetric investigation of order–disorder transition in Cu0.6Pd0.4 and Cu0.85Pd0.15 alloys

Order–disorder phase transitions in Cu_0.6Pd_0.4 and Cu_0.85Pd_0.15 alloys have been investigated using differential scanning calorimetry and drop calorimetry. The differential scanning calorimetry measurements show that the transition in both these alloys are reversible in nature and the enthalpy increment measurements reveal that these transitions are first order in nature. The transition temperature of first-order phase transition in Cu_0.6Pd_0.4 and Cu_0.85Pd_0.15 alloys have been evaluated to be 884(±2) and 799(±2) K, respectively, from drop calorimetric measurements. The latent heat of first-order phase transition in Cu_0.6Pd_0.4 alloy were evaluated to be 31.2(±0.6) and 28.9(±0.5) J g^?1, by enthalpy increment and differential scanning calorimetry measurements, respectively. Similarly, the latent heat of first-order phase transition in Cu_0.85Pd_0.15 alloy were evaluated to be 23.1(±0.6) and 21.3(±0.5) J g^?1, by enthalpy increment and differential scanning calorimetry measurements, respectively. The solidus temperatures of Cu_0.6Pd_0.4 and Cu_0.85Pd_0.15 alloys were found to be 1,457(±2) and 1,360 K, respectively.     

Interaction between Sulfaproxyline and β-Cyclodextrin in the Solution and Solid States

The 1 : 1 inclusion complex between sulfaproxyline (SP) and -cyclodextrin (-CD) was prepared by the freeze-drying and the kneading method. Complex formation was confirmed in the solid state by X-ray diffractometry and by infrared spectroscopy. The interaction between sulfaproxyline and -cyclodextrin in solution was studied by the solubility method and 13C-NMR spectroscopy. Phase solubility studies in water revealed a AN type diagram and a stability constant of 930 ± 120 M-1 for a 1 : 1 inclusion complex was derived. Complexation was found to improve the dissolution rate of sulfaproxyline.     

Structure of 1-β-d-xylofuranosyluracil in the crystal and in solution

The molecular and crystal structure of 1-β-d-xylofuranosyluracil hydrate was established by X-ray diffraction analysis. The mutual arrangement of the xylofuranose fragment and the nucleic base corresponds to the anti conformation. The furanose ring adopts a C-envelope conformation. The structure of the nucleoside in a DMSO-d₆ solution has been determined by¹H NMR spectroscopy. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1378–1380, July, 1998.