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As a catalytic center, the 4N-coordinated post-transition metal (PM) confined within phthalocyanine (Pc) shows promise for the environmentally friendly synthesis of CH4 and NH3. A range of PM–Pc catalysts (where PM represents Al, Ga, In, Tl, Ge, Sn, Pb, and Bi) is methodically evaluated through DFT mechanistic analysis and electrochemical exploration to determine their stability, activity, and selectivity. Our comparative analysis reveals that the orientational specificity of initial cyanide adsorption would play a crucial role in cyanide electroreduction reaction (CNRR) pathways within diverse PM–Pc nanosheets. Specifically, the NC* model typically requires higher supplies of Gibbs free energy for the CNRR, preponderantly resulting in CH3NH2. Conversely, the counterpart of the CN* model necessitates lower energetic demands, leading to a broader diversity of products including methane and ammonia. Of particular significance that the relationships of limiting potentials (UL) through two types of descriptors, ΔGNC*→HNC* and ΔGCN*→HCN*, were essential for constructing volcano plots, thus illustrating the relation within the intrinsic adsorption performance of diverse PM–Pc series and their associated prominent CNRR efficiency. From a comprehensive screening of the studied results, we have determined that the nanosheets Al–Pc, In–Pc, Ge–Pc, and Sn–Pc (triggered by the CN* model) are the exceptionally proficient electrocatalysts, specifically in producing only CH4 and NH3 via the CNRR process, as indicated by our final compiled findings. Within the range of nanosheets evaluated, the Al–Pc associated model emerges as a standout, demonstrating markedly higher selectivity and CNRR activity than its counterparts. This study advances the understanding of the unique superior characteristics of SACs, subsequently providing innovative perspectives that could directly guide their discovery for CNRR applications. [ABSTRACT FROM AUTHOR]

The statistical thermodynamic theory of the absorbate-induced surface stress of adion monolayer on Au(111) is established by using the lattice gas model. The effective pair interaction energy, surface stress, and its components due to various intermolecule forces, and the area elasticity modulus k(sub 2D)(super -1) in the chloride adlayer at the Au(111) electrode surface, are calculated.

A theoretical study of the CH3NO2 unimolecular decomposition potential energy surface is presented. It also includes 46 interconversion transition states and 16 major dissociation products.

Laser-induced nuclear magnetic resonance (NMR) shifts were investigated theoretically by semiclassic approach as a dynamic Stark effect of optical fields. Evidence showed that light shifts in an optical pumping experiment and in NMR and electron spin resonance spectra can be explained by the identical fundamental principle. The computed NMR shift for a Hg199 atom can be of the order of 1 MHz in a circularly polarized laser beam 10 W/sq cm at a frequency near the singlet-triplet transition absorption.

The electrocompression behavior of electrodeposited halide monolayer at the electrode surface of Au(111) may be investigated using a simple physical model and theory. Calculations of the statistical thermodynamic formulas, effective pair interaction energy, two dimensional spreading pressure, two dimensional isothermal compressibility and electrode potential-coverage yield results that are in agreement with experimental measurements. The calculations show that the adatom-adatom interactions, such as repulsive interactions, determine the compressibility of the halide adlayer.

A dihydrotestosterone/5alpha-androstane-3alpha,17beta-diol UDP-glucuronosyltransferase (transferase) is used to encode a human cDNA, UDPGTh-3.A530 amino acid protein with an ordinary membrane insertion-signal peptide. A membrane-anchoring region and three powerful asparagine-connected glycosylation sites are encoded by the nucleotide series of UDPGTh-3. A 96% similarity is observed between the encoded isozyme and the presumed isoform, HLUG4, which metabolizes estriol. There is a 78% similarity between the udpgth-3 isozyme and two steroid isoforms, udpgth-1 and -2.

Two human liver UDP-glucoronosyltransferase cDNA clones with different activities, HLUG25which encode isoenzymes in the glucuronidation of hyodeoxycholic acid and UDPGT(sub h)-2 which is involved with estrogen derivatives, have isoforms that were identified and evaluated. The HLUG25 isoform is produced by mRNA only in the liver while the UDPGT(sub h)-2 isoform is produced in both the liver and kidney and primarily detoxifies bile salt and active estrogen intermediates.

The Ir-based materials are prepared via metathesis reaction between halide and alkali metal salts of two cationic and three anionic Ir complexes and their electrochemical and photophysical characterization are described. The studies have shown that the soft salts have produced maximum external quantum efficiencies (EQE) and that the internal energy alignment between two ions in the soft salts is responsible for the disparate results

Comprehensively characterization of a generic and efficient chemical patterning method based on local plasma-induced conversion of surface functional groups on self-assembled monolayers (SAMs) is described. Spatially controlled plasma exposure realized by elastomeric poly(dimethylsiloxane) (PDMS) contact masks or channel stamps with feature sizes ranging from nanometer, micrometer, to centimeter is also presented.

A new comprehensive method to combine scanning probe microscopy (SPM) nanolithography and modified SPM break junction techniques to fabricate and characterize single molecular break junction devices is described. The newly designed approach also allowed one to eliminate, or at least minimize, the variations of experimental conditions and enabled the measurement of multiple molecules under the same experiment with exactly the same experimental conditions.

An extremely simple and practical Ti[Cl.sub.4]-Mg promoted synthesis of 1,5-keto esters via multicomponent coupling of various amides with C[H.sub.2][Cl.sub.2] and methyl acrylate is described. The efficiency of the reaction chemistry is demonstrated by the very simple preparation of unusual 4,4-dideuterio-1,5-keto esters.

White electroluminescent (EL) emission is demonstrated from single-layered solid-state light-emitting electrochemical cells (LECs) based on host-guest cationic iridium complexes. The results have shown that white LECs based on host-guest cationic transition metal complexes is a good alterative for solid-state lighting methods.

The self-assembly, as well as the tunable plasmonic response of the highly ordered alkanethiolate-stabilized gold nanoparticle superlattices are discussed. The approach demonstrates the application of near-field coupling for the development of plasmonic crystals.

High-level ab initio molecular orbital methods were used to investigate the reaction between C[H.sub.2]O and ClO and to map out the complete potential energy surface (PSE) for the system. The calculated results demonstrated that the formation of HOCl+HCO was the dominant reaction channel and was exothermic suggesting that the decomposition in both the forward and backward directions for HOCl would be difficult in the ground electronic state.

The original measurements of the single-molecule conductance of a carotenoid polyene were made by inserting the molecule into an alkanethiol self-assembled monolayer and contacting the inserted molecules either directly with a conducting atomic force microscope (AFM) probe or by using a gold nanoparticle as an intermediate contact. The electronic decay constant for carotenoid polyenes is measured, finding a value in good agreement with results of electronic structure calculations.

The self-assembled monolayers (SAM) formed by tethering tetrathiafulvalene (TTF) derivatives through two thiolate groups directly to a gold surface are reported and the structural and electrical properties are studied. Based on the results, the dithiol variants would be ideal as candidate molecular wires in any self-assembled systems.

Antisymmetric vibrational transition polarizability induced by intermolecular charge-transfer interactions is proposed and studied by using group theory, especially time-reversal symmetry, and Milliken's theory of charge-transfer complexes. The results show that under the Bjorn-Oppenheimer (B-O) approximation, the antisymmetric transition polarizability of even-electron systems with real representation ground states is zero.

The Resonance Raman (RR) spectra of aggregates of tetrakis(4-sulfonatophenyl)porphyrin diacid [H4TSPP(super 2-)] and segregated monomers were calculated with time-dependent resonant Raman formulas for the Franck-Condon mechanism of enhancement. It was deduced from the analysis that there are large dimensionless displacements on the excited state along the nu8, lambda16 and nu2 coordinates for both aggregated and segregated H4TSPP(Super 2-).

Pollutant treatment is critical in modern society and often requires tedious workup and expensive facilities. By virtue of structural diversity and tunability, metal-organic frameworks (MOFs) have shown promise in pollutant control. We herein report a powerful templated freeze-drying protocol for the fabrication of multifunctional MOF hollow tubular structures for both air and liquid contaminants filtration. Various hollow tube systems (e.g., "Janus", "coaxial" and "cellular") are produced. Specially, a multilayer coaxial MOF hollow tube is prepared for highly efficient capture of mixed inorganic-organic liquid contaminants with >94% filtration efficiency. Further, a "cellular" hollow tube with low pressure-drop (12 Pa, 10 cm s[sup -1]) is applied in particulate matter filtration with high efficiency (>92%). Given the rich structural and functional diversities, this protocol might bring MOFs into industrial applications to remediate environmental problems. [ABSTRACT FROM AUTHOR]

The accelerating search for new types of drugs and delivery strategies poses challenge to understanding the mechanism of delivery. To this end, a detailed atomistic picture of binding between the drug and carrier is quintessential. Although many studies focus on the electrostatics of drug-vector interactions, it has also been pointed out that entropic factors relating to water and counterions can play an important role. By carrying out extensive molecular dynamics simulations and subsequently validating with experiments, we shed light herein on the binding in aqueous solution between a protein drug and polymeric carrier. We examined the complexation between the polymer poly(ethylene glycol) methyl ether acrylate-b-poly(carboxyethyl acrylate (PEGMEA-b-PCEA) and the protein egg white lysozyme, a system that acts as a model for polymer-vector/protein-drug delivery systems. The complexation has been visualized and characterized using contact maps and hydrogen bonding analyses for five independent simulations of the complex, each running over 100 ns. Binding at physiological pH is, as expected, mediated by Coulombic attraction between the positively charged protein and negatively charged carboxylate groups on the polymer. However, we find that consideration of electrostatics alone is insufficient to explain the complexation behavior at low pH. Intracomplex hydrogen bonds, van der Waals interactions, as well as water-water interactions dictate that the polymer does not release the protein at pH 4.8 or indeed at pH 3.2 even though the Coulombic attractions are largely removed as carboxylate groups on the polymer become titrated. Experiments in aqueous solution carried out at pH 7.0, 4.5, and 3.0 confirm the veracity of the computed binding behavior. Overall, these combined simulation and experimental results illustrate that coulomb interactions need to be complemented with consideration of other entropic forces, mediated by van der Waals interactions and hydrogen bonding, to search for adequate descriptors to predict binding and release properties of polymer-protein complexes. Advances in computational power over the past decade make atomistic molecular dynamics simulations such as implemented here one of the few avenues currently available to elucidate the complexity of these interactions and provide insights toward finding adequate descriptors. Thus, there remains much room for improvement of design principles for efficient capture and release delivery systems. [ABSTRACT FROM AUTHOR]

Thermophoresis is a phenomenon about the migration of particles along a temperature gradient and is sensitive to the properties of particles and the surrounding medium. While a few studies have investigated its mechanisms and effects on particle motion in recent years, the applications of thermophoresis in biosensing has not been well explored. In this study, we demonstrate a thermophoresis-based method for detecting DNA. We use DNA-functionalized gold nanoparticles and fluorescent DNA probes to capture target DNA in free solution, and we demonstrate that the hybridization between the specially designed capture probes and the target DNA significantly changes the thermophoretic properties of the fluorescent probes. As a result, the target DNA can be specifically detected in serum-containing buffers based on the spatial distribution of the fluorescent probes in a laser-induced temperature gradient. The optical setup consists of only a laser and an epifluorescence microscope, and the detection does not rely on any micro- or nanofabricated devices. In addition, because the detection is based on the thermophoretic motion of molecules in free solution, no capture probes need to be immobilized on a fixed surface before detection, and no channels or pumps are needed for washing away unbound molecules. The thermophoresis-based biosensing method is found to be simple and effective for detecting DNA. [ABSTRACT FROM AUTHOR]

Analyzing purified membrane proteins and membrane protein complexes by mass spectrometry has been notoriously challenging and required highly specialized buffer conditions, sample preparation methods, and apparatus. Here we show that a standard matrix-assisted laser desorption/ionization (MALDI) protocol, if used in combination with a high-mass detector, allows straightforward mass spectrometric measurements of integral membrane proteins and their complexes, directly following purification in detergent solution. Molecular weights can be determined precisely (mass error ≤ 0.1%) such that high-mass MALDI-MS was able to identify the site for N-linked glycosylation of the eukaryotic multidrug ABC transporter Cdr1p without special purification steps, which is impossible by any other current approach. After chemical cross-linking with glutaraldehyde in the presence of detergent micelles, the subunit stoichiometries of a series of integral membrane protein complexes, including the homomeric PglK and the heteromeric BtuCD as well as BtuCDF, were unambiguously resolved. This thus adds a valuable tool for biophysical characterization of integral membrane proteins. [ABSTRACT FROM AUTHOR]

Spherulite morphology and growth kinetics of poly(octamethylene terephthalate) (POT), cast on single-side glass or confined between two slides in thin-film forms, were characterized using polarized versus nonpolarized optical microscopy, scanning electron microscopy (SEM), and wide-angle X-ray (WAXD) analysis. POT can simultaneously display solely one type of spherulite or dual types of spherulites (double-ring-banded and ringless ones), depending on Tcor Tmaximposed. Fractions of these two types depend on Tcwhen quenched from a fixed Tmax= 160 °C. At lower Tc’s, POT exhibits higher crystallization rates leading to higher fractions of ringless spherulites; at higher Tc’s, POT exhibits lower crystallization rates leading to ring-banded spherulites. At intermediate to high Tc’s where the growth kinetics of POT could be monitored, the ring-band type dominates and the fraction of ringless spherulites is insignificantly small. Both ringless and ring-banded spherulites can be seen in regime III ( Tc= 70−110 °C), with fractions of ringless type of spherulites decreasing with temperature. Thus, growth kinetics for POT was mainly focused on the regime of ring-banded spherulites. In regime III, the ring-band pattern is more orderly concentric with smaller inter-ring spacing (1−2 μm) for lower Tc’s but intermediately larger spacing (3−5 μm) for higher Tc’s. The orderly lamellar orientation in the ring-bands in contrast with the inter-ring valley region is discussed. In regime II (115 °C and above), the ring-band pattern is first distorted to highly zigzag irregularity at higher Tc’s and then eventually disappears at extremely high Tc, with the lamellar crystals eventually turning dendritic with no rings. Apparently, the types of spherulites in polymers are more influenced by the growth rates as determined by Tcand slightly less by Tmax, but not by the substrate surface nucleation. [ABSTRACT FROM AUTHOR]