荷电膜渗透传质过程的计算机模拟:一价离子的传递

The transport of monovalent ions through a charged membrane was investigated by percolation approach. Based on percolation concept and theory, the theoretical simulation was conducted for two-dimension (2D) and three-dimension (3D). The results showed that for 2D lattices there has a obviously skip or percolation threshold with charged components from 0.4 to 0.6, and for 3D lattices, such value is between 0.1-0.2. The simulative results were well conformed to those by Monto Carlo simulation for a random system. A practical charged membrane which prepared from the blends of sulphonated polyphenylene sulfide (SPPS)/poly(ether sulfone) (PES) can be considered as a 3D lattices. The experimental conductivity was related with a 3D simulation and the result showed the membrane has a transition from insulator to conductor at the ratio of charged components SPPS about 0.144. Obviously, this value falls in the range of a theoretical simulation for a 3D lattices.     

N-Acetyl-N,N-dipyrid-2-yl (cyclooctadiene) rhodium (I) and iridium (I) complexes: Synthesis, X-ray structures, their use in hydroformylation and carbonyl hydrosilylation reactions and in the polymerization of diazocompounds

The synthesis of novel N-acetyl-N,N-dipyrid-2-yl complexes of Rh^I and Ir^I, i.e. [RhCl(CH₃CONPy₂)(COD)] (1) and [IrCl(CH₃CONPy₂)(COD)] (2), respectively, is described. Upon prolonged treatment in CH₂Cl₂ at room temperature, complex 1 is transformed into a cationic Rh-complex, i.e. [Rh(CH₃CONPy₂)(COD)⁺RhCl₂(COD)⁻] (1a). Compound 1a crystallizes in the monoclinic space group P2₁/c, complex 2 crystallizes in the triclinic space group . Compound 1 was investigated for its catalytic activity in the hydroformylation of cyclooctene as well as of 1-octene. In addition, 1 was used in various carbonyl hydrosilylation reactions of both aldehydes and ketones. There, turn-over numbers up to 50 000 and yields in the range of 85-100% were observed. Finally, compound 1 was successfully used for the polymerization of N₂CHCOOEt yielding highly stereoregular poly(ethoxycarbonylcarbene) with M_w = 67 000 g/mol and a polydispersity index (PDI) of 2.59.     

The effect of glass transition on phase separation in binary off-critical blends: different coarsening regimes near the nonequilibrium percolation threshold

The nonequilibrium percolation threshold was shown to take an intermediate position between binodal and mean-field spinodal. Below the nonequilibrium percolation threshold, a bicontinuous phase structure was produced. This percolation structure, depending on supersaturation, breaks down to ramified clusters slowly assuming a spherical droplet form or contracts to the center of the sample. In the latter case, at late stages, secondary phase separation is observed. Accepted: 21 September 1998     

The role of crystallization parameters for the synthesis of germanosilicate with UTL topology

The investigation of the critical synthesis parameters of germanosilicate of UTL topology, possessing 14- and 12-rings, has been carried out in detail. (6R,10S)-6,10-Dimethyl-5-azoniaspiro[4.5]decane hydroxide was used as the structure-directing agent (SDA). The kinetics of the synthesis, the role of the Si/Ge ratio in the synthesis mixture, and the effect of the calcination procedure were investigated in relation to the crystallinity and textural properties of the synthesized material. The optimum synthesis time was found to be six days for Si/Ge and (Si+Ge)/SDA molar ratios of 2 and 1.7, respectively. The UTL zeolite crystallizes as small sheets of 10 mum in size. The micropore volume of the best crystals is 0.22 cm(3) g(-1) with a micropore diameter of 1.05 nm, based on DFT and Saito-Foley analyses of adsorption data.     

The Development of Vanadyl Phosphate Cathode Materials for Energy Storage Systems: A Review

Various cathode materials have been proposed for high-performance rechargeable batteries. Vanadyl phosphate is an important member of the polyanion cathode family. VOPO₄ has seven known crystal polymorphs with tunneled or layered frameworks, which allow facile cation (de)intercalations. Two-electron transfer per formula unit can be realized by using V^V/V^IV and V^IV/V^III redox couples. The electrochemical performance is closely related to the structures of VOPO₄ and the types of inserted cations. This Review outlines the crystal structures of VOPO₄ polymorphs and their lithiated phases. The research progress of vanadyl phosphate cathode materials for different energy storage systems, including lithium-ion batteries, sodium-ion batteries, potassium-ion batteries, multivalent batteries, and supercapacitors, as well as the related mechanism investigations are summarized. It is hoped that this Review will help with future directions of using vanadyl phosphate materials for energy storage.     

Dispirocycles: Platforms for the Construction of High-Performance Host Materials for Phosphorescent Organic Light-Emitting Diodes

Spirocyclic compounds such as 9,9′-spirobifluorene (SBF) are becoming more and more attractive for use as host materials in organic optoelectronic devices. Herein, two dispirocycles, namely, dispiro[fluorene-9,9′-anthracene-10′,9′′-fluorene] and 10,10′′-diphenyl-10H,10′′H-dispiro[acridine-9,9′-anthracene-10′,9′′-acridine], were used for the construction of host materials 1 – 4 . The attached triphenylamino group determines the thermal, photophysical, electrochemical, and charge-transport properties, and therefore they have different electroluminescent performances. The device based on dispiro[fluorene-9,9′-anthracene-10′,9′′-fluorene] ( 2 ) and 10,10′′-diphenyl-10H,10′′H-dispiro[acridine-9,9′-anthracene-10′,9′′-acridine] ( 3 ) molecular platforms exhibited external quantum efficiencies of greater than 21 % with a very high power efficiency (≈100 lm W⁻¹). These results demonstrate the potential of extending the application of dispirocyclic molecular platforms with inherent rigidity for developing highly efficient host materials for organic light-emitting diodes.     

The Use of Chelating Solid Phase Materials in Flow Injection Systems: A Review

Flow injection analyses facilitate faster, inexpensive, and more environmentally friendly sample-preparation techniques than many traditional “wet chemistry” methods, and the use of flow injection has, therefore, expanded significantly in recent years. This review focuses on chelating solid phase materials, which have been used in flow injection analyses and also describes important information, such as type of chelating groups, the type of stationary phases, and their efficiency at pre-concentrating metal ions. Discussions of the improvement of the sensitivity and of improving limit of detection, as well as the efficiency with which concomitant ions are removed for the flow injection methods using chelating solid phase materials, are also made.     

The Mechanism of the Magnetodielectric Response in a Molecule-Based Trinuclear Iron Cluster Material

Magnetodielectric response mechanisms are critical for the rational design and synthesis of molecule-based magnetodielectric materials. Herein, the magnetodielectric response was investigated in the molecule-based material [Fe₃O(CH₃COO)₆(py)₃](py) ( 1 ). Its magnetodielectric coefficient (MD) is −2.8 % for phase transition III and −4.1 % for phase transition I. Study of the mechanism of the magnetodielectric response in 1 reveals that its magnetodielectric response at phase transition I is induced by the charge-frustration of the trinuclear iron cluster, while that at phase transition III is attributed to the spin-frustration of the trinuclear iron cluster, providing a new route for the design of magnetodielectric materials.     

On the Statistical Mechanics of Non-Hamiltonian Systems: The Generalized Liouville Equation, Entropy, and Time-Dependent Metrics

Several questions in the statistical mechanics of non-Hamiltonian systems are discussed. The theory of differential forms on the phase space manifold is applied to provide a fully covariant formulation of the generalized Liouville equation. The properties of invariant volume elements are considered, and the nonexistence in general of smooth invariant measures noted. The time evolution of the generalized Gibbs entropy associated with a given choice of volume form is studied, and conditions under which the entropy is constant are discussed. For non-Hamiltonian systems on manifolds with a metric tensor compatible with the flow, it is shown that the associated metric factor is in general a time-dependent solution of the generalized Liouville equation.     

The determination of organochlorine compounds and petroleum hydrocarbons in a seaweed sample: results of a world-wide intercomparison exercise

A seaweed sample (Fucus sp.) was prepared, homogenised and distributed to laboratories worldwide as the IAEA-140 intercomparison material for the analysis of organochlorine compounds and petroleum hydrocarbons. A total of 80 laboratories from 51 countries reported results for this sample. The data sets reported by laboratories were evaluated statistically and the mean concentration values could be computed with 95% confidence limits for a large number of analytes. The accuracy of the analytical performance of each laboratory has been introduced by using Z-scores. The spread of results reported generally indicates that the accurate determination of many persistent organic pollutants, such as hexachlorobenzene, lindane, Aroclors or fluoranthene, is still difficult for many laboratories. The final results of this intercomparison exercise enable individual participants to assess their performance and, where necessary, to introduce appropriate modifications in their analytical procedures. Furthermore, as a series of statistical criteria was fulfilled for a number of compounds, the sample IAEA-140 can now be used as a reference material for quality control in the determination of chlorinated compounds and petroleum hydrocarbons in environmental samples.     

The Mechanism of the Magnetodielectric Response in a Molecule‐Based Trinuclear Iron Cluster Material

Magnetodielectric response mechanisms are critical for the rational design and synthesis of molecule‐based magnetodielectric materials. Herein, the magnetodielectric response was investigated in the molecule‐based material [Fe₃O(CH₃COO)₆(py)₃](py) ( 1 ). Its magnetodielectric coefficient (MD) is ?2.8 % for phase transition III and ?4.1 % for phase transition I. Study of the mechanism of the magnetodielectric response in 1 reveals that its magnetodielectric response at phase transition I is induced by the charge‐frustration of the trinuclear iron cluster, while that at phase transition III is attributed to the spin‐frustration of the trinuclear iron cluster, providing a new route for the design of magnetodielectric materials.     

Preparation of High Purity Sodium 5‐Nitrotetrazolate (NaNT): An Essential Precursor to the Environmentally Acceptable Primary Explosive,DBX‐1

Sodium 5‐nitrotetrazolate dihydrate (NaNT) is a useful precursor compound for the synthesis of lead‐free primary explosives; however, currently employed syntheses for the compound are tedious, dangerous, and plagued by impurities. Through comprehensive analysis, we elucidate the identity of the most detrimental impurities and further report an improved procedure for preparation of NaNT, which greatly improves the purity, while avoiding the handling of acid copper(II) nitrotetrazolate, a highly sensitive explosive intermediate. In the new procedure, 5‐aminotetrazole is diazotized with sodium nitrite, cupric sulfate, and nitric acid. Copper is precipitated as its oxide and the aqueous solution evaporated. After soxhlet extraction with acetone, large crystals of NaNT are obtained. The prepared material is suitable for preparation of lead azide replacement DBX‐1 [copper(I) 5‐nitrotetrazolate] as evidenced by successful use in M55 stab detonators.     

Six‐Coordinate Group 13 Complexes: The Role of d Orbitals and Electron‐Rich Multi‐Center Bonding

Bonding in six‐coordinate complexes based on Group 13 elements (B, Al, Ga, In, Tl) is usually considered to be identical to that in transition‐metal analogues. We herein demonstrate through sophisticated electronic‐structure analyses that the bonding in these Group 13 element complexes is fundamentally different and better characterized as electron‐rich hypervalent bonding with essentially no role for the d orbitals. This characteristic is carried through to the molecular properties of the complex.     

The Evolution of Bonding and Thermodynamic Properties of Boron‐Doped Small Carbon Clusters: An Ab Initio Study

Theoretical studies on BC_n (n=1–6) clusters are carried out using density functional theory, Møller–Plesset second‐order perturbation theory (MP2), coupled‐cluster calculations including up to triple excitations (CCSD(T)), and higher‐level approaches. All possible isomers depending on the positions of the boron atom are generated and the lowest‐energy isomers are determined for doublet and quartet electronic states. The three potential evolution paths of the clusters are determined as a function of their size. The energetic and electronic consequences for the increased size of structures differ significantly, which leads to representatives of the ground electronic state from different structural groups. The ab initio calculated thermal functions allow enhancements to the available atomization energies and improve the agreement between the calculated and experimental heat content.     

The determination of adsorbable organically bound halogens (AOX) in soil: interlaboratory comparisons and reference materials

The interlaboratory variability in the quantification of adsorbable organically bound halogens (AOX) in industrially contaminated soil is presented. Three consecutive rounds of a proficiency testing scheme, in which between 88 and 119 routine laboratories participated, yielded relative reproducibility standard deviations between 7 and 20% at AOX contents between 10.9 and 268 mg kg⁻¹. Nineteen laboratories with established proficiency were invited to participate in the certification of the AOX content in three soil reference materials meant for the internal quality control in analytical laboratories. The certified values are (1349 ± 59) mg kg⁻¹, (80 ± 7) mg kg⁻¹ and (102 ± 8) mg kg⁻¹, respectively.     

Application of ion-in-conjugation molecules in resistive memories and gas sensors: The role of conjugation

Ion-in-conjugation(IIC) materials are eme rging as an important class of organic electronic materials with wide applications in energy storage,resistive memories and gas sensors.Many IIC materials were designed and investigated,however the role of conjugation in IIC materials' performance is yet investigated.Here we designed two molecules obtained by condensation of 4-butylaniline and oxocarbon acid.Squaric acid derivatives squaraine named SA-Bu and a croconamide named CA-Bu which only differ in their oxocarbon cores.While employing SA-Bu and CA-Bu as resistive memory and gas sensory materials,SA-Bu has attained promising performance in ternary memo ry and detection of NO_2 as low as 10 parts-per-billion whereas CA-Bu show mainly binary memory behavior and negligible NO_2 response.Theoretical calculations reveal that conjugation of CA-Bu was distorted by the increased steric hindrance,frustrating the charge transport and suppressing the conductivity.Our work demonstrates that the conjugation plays a crucial role in ion-in-materials promoting ternary RRAM devices and highperformance gas sensors manufacture.     

Graphene: Safe or Toxic? The Two Faces of the Medal

Graphene is considered the future revolutionary material. For its development, it is of fundamental importance to evaluate the safety profile and the impact on health. Graphene is part of a bigger family which has been identified as the graphene family nanomaterials (GFNs). Clarifying the existence of multiple graphene forms allows better understanding the differences between the components and eventually correlating their biological effects to the physicochemical characteristics of each structure. Some in vitro and in vivo studies clearly showed no particular risks, while others have indicated that GFNs might become health hazards. This Minireview critically discusses the recent studies on the toxicity of GFNs to provide some perspective on the possible risks to their future development in materials and biomedical sciences.