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The vapor–liquid equilibrium (VLE) data of the ethanol + sec-butyl acetate, 1-propanol + sec-butyl acetate, and 2-propanol + sec-butyl acetate mixtures were determined at 101.3 kPa. The first principle quantum chemistry calculation method, which focuses on the hydrogen bond and interaction energies, is used to give insight into interactions at the molecular level. The experimental VLE data passed the thermodynamic consistency test. The data were regressed using Wilson, nonrandom two liquids, and universal quasi-chemical equations. The 1-propanol + sec-butyl acetate mixture forms a minimum temperature azeotropic mixture. The azeotropic temperature is 370.01 K, and the composition of 1-propanol is 89.2 mol % when calculated with the Wilson model.

The self-assembly powder (SAP) with varying Nafion content was synthesized and characterized by XRD, XPS, HRTEM, and mapping. It is observed that the oxygen from oxygen functional groups transfers to the surface of Pt and generate PtO during the process of self-assembly with the mechanism of micro galvanic cell, where Pt, carbon black, and Nafion act as the anode, cathode and electrolyte, respectively. The appearance of PtO on the surface of Pt leads to a turnover of Nafion structure, and therefore more hydrophilic sulfonic groups directly contact with Pt, and thus the triple-phase boundary (TPB) has been expanded.

•More unsaturated bonds in the lipid will result in high gamma secretase (GS) stability.•Lipids with a short alkyl tail chain or with a shorter PC head than a PE head result in high TM6 mobility.•GS mobility was lowest in 2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC).•Distinct structure details of the five lipids offer clues and methods for modulating GS activity.

A new family of all‐carbon structures is proposed via substituting the sp2carbon atom in graphene and graphyne with carbon trigons. Owing to the existence of carbon trigons, these porous carbon allotropes are named as trigraphene and trigraphyne. The calculations of geometrical, vibrational, and energetic properties by density functional theory reveal that all these structures are metastable and dynamically stable. It is further disclosed from the electronic band structures that trigraphene and α‐trigraphyne are metal, while β‐trigraphyne and γ‐trigraphyne are semiconductor with indirect band gaps of 0.33 and 0.52 eV, respectively. Our results suggest a strategy to design new carbon materials with desired properties, and these all‐carbon materials would have many interesting applications once obtained.

Due to many remarkable advantages, such as biodegradability, low cost, chiral property, no toxicity, and excellent solution property, amino acid ionic liquids (AAILs) have received more and more attention and recognition in many chemical and environmental engineering fields. The intervention of water would significantly influence their properties.

Accumulating evidence suggests that toxicity in patients with Alzheimer's disease originates from the deposition of Aβ42 aggregates on the neuronal cell membrane. However, the molecular mechanism underlying Aβ42 aggregation on the surface of different lipids is poorly understood. In this study, coarse-grained and all-atomic molecular dynamics (MD) simulations were used to characterize the assembly process of two Aβ42 pentameric oligomers and the perturbation “footprints” of three characteristic lipid constitute bilayer membranes: POPC, POPG, and their hybrid PcPg composed of POPG and POPC in a 1:3 ratio. Our results revealed that the Aβ decamer was first formed in the water phase prior to its contact with the lipid surface, indicating that the water phase plays an incubation role in Aβ42 oligomer aggregation. Moreover, the presence of any of the three lipids accelerated the assembly process of the two Aβ42 pentameric. The aggregation rate and aggregate conformation were strictly dependent on lipid charge, oligomer size, and degree of aggregation. In turn, the presence of oligomer impacted the surface of the lipid, generating a clear perturbation “footprint,” regardless of whether the interplay was direct or indirect, revealing for the first time that the indirect interaction is not seamless and can be detected clearly at the molecular level. Indirect interplay stands for the non-contacting interaction interfaced by the water phase, indicating a metastable state with long-range interaction under non-shaking conditions. Our results reveal the crucial role of non-contacting interactions in determining the phase status of zwitterionic membranes.

Pentaerythritol-zinc (called Penzinc), which is a novel thermal stabilizer for PVC, was synthesized, and its performance was characterized during the thermal processing of PVC. The stabilization effects of this new stabilizer combined with calcium stearate (CaSt2) and stearoyl benzoyl methane (ß-diketone) were investigated using conductivity tests, thermal aging tests, and torque rheometry tests. The results revealed that the addition of Penzinc can improve the color and thermal stability of PVC in both static and dynamic tests. There are no obvious synergistic effects between Penzinc and CaSt2. However, the synergistic action between Penzinc and ß-diketone is excellent. The thermal stability mechanisms of Penzinc and ß-diketone are also discussed with the help of quantum chemical calculations.

The effect of the new designed multicopper modification of base pairs on the conductivity of DNA was investigated by the nonequilibrium Green’s function method combined with density functional theory. Electronic transport calculations revealed that the equi-number H-by-Cu replacement can significantly enhance the conductivity of DNA from two aspects: transverse base-to-base communication along the hydrogen-bond direction and longitudinal transport along the DNA duplex. Furthermore, the enhancement effect on the longitudinal direction is more notable than that on the transverse. A tunneling mechanism is suggested for the short DNA segments. The decay factor of conductance in Cu-DNA decreases by half compared with the native DNA, thus making it more promising for constructing nanowires. In addition, Cu-DNA may prefer electron migration to hole transport with the lengthening of DNA segments. This work will shed some light on the design of promising DNA-based molecular wires.

The regulatory roles of metal ions M2 Li, Na, K, Be2, Mg2, and Ca2 and water molecules in stabilizing the zwitterionic form of glycine derivatives are discussed in the present paper. The involved glycine conformers are 1 the glycine zwitterion OO, which can bind an ion to form the salt-bridge-form derivative, and 2 two neutral forms NO and OH, which can bind the ion with both the carboxyl oxygen and the amino nitrogen NO, or both the carboxyl oxygen and the hydroxyl oxygen OH to form charge-solvated structures. Results show that four water molecules can make the OO-mode glycine–LiNaKderivatives more stable than each of the corresponding NO-mode counterparts. Similarly, two water molecules can make the OO-mode glycine–Be2more stable than its corresponding NO-mode counterpart, while the OO-mode glycine–Mg2Ca2are always more stable than their corresponding NO counterparts whether there is a water molecules attached or not. No OH-mode glycine–Be2Mg2Ca2hydrates are observed because the large electrostatic effect of these divalent metal ions makes the OH-mode hydrates degenerate into the OO-mode ones. For the non-hydrated or monohydrated glycine–LiNaisomers, the global minimum derives from the NO-mode structure. Their (di–tetra)hydrates, however, prefer the OH-mode to the other two. For all these different glycine–Khydrates, each OH-mode structure is always the global minimum among the corresponding isomers, as for the non-hydrated reactant glycine–K. These predictions are consistent with other theoretical and experimental results. Most of the relative binding strengths, between a metal ion and its corresponding ligand, of the three modes are in good agreement with the relative stabilities, i.e., the larger the binding energy is, the more stable the structure would be. Some exceptions to the agreement are explained. A comparison of binding strengths shows that the smaller the ion radius is, the greater its binding strength would be. For instance, Li–NO·W −50.5 kcal mol−1 > Na–NO·W −36.4 kcal mol−1 > K–NO·W −25.4 kcal mol−1.

Several biologically relevant glycine–Fe+/Fe2+complexes with three different multiplicities were studied for the first time by using the hybrid three‐parameter B3LYP density functional method with different basis sets. Single‐point calculations were also carried out at the BHLYP level with a larger basis set to refine and calibrate these energy values. The results show that the most stable glycine–Fe+isomer is the C1‐symmetric sextet NO‐16, in which Fe+is interacted with both the amino nitrogen and carbonyl oxygen of the glycine ligand. The ground‐state structure of glycine–Fe2+is the 5A′′ state 2O‐25, which generates from the interaction of Fe2+with the two oxygen terminus of the zwitterionic glycine. The calculations indicate that the binding energies mainly derive from the contributions of electrostatic effects, for both the monovalent and divalent metal cation‐chelated glycine complexes. The differences in binding energies between these different multiple‐state glycine–Fe+isomers with same combination modes mainly derive from their different electrostatic and polarized effects, and those between the isomers of different combination modes with the same multiple states mainly stem from their different deformation effects. The differences in the relative stabilities of these glycine–Fe+isomers with different multiple states mainly come from the fact that the more electrostatic contribution of the lower spin complex cannot compensate for the loss of energy enhancement of its corresponding metal cation relative to that of the higher spin counterpart. The same is true for the glycine–Fe2+complexes. Copyright © 2004 John Wiley & Sons, Ltd.