Carbon nanotube, graphene, nanowire, and molecule-based electron and spin transport phenomena using the nonequilibrium Green's function method at the level of first principles theory

Based on density functional theory, we have developed a program code to investigate the electron transport characteristics for a variety of nanometer scaled devices in the presence of an external bias voltage. We employed basis sets comprised of linear combinations of numerical type atomic orbitals, particularly focusing on k-point sampling for the realistic modeling of the bulk electrode. The scheme coupled with the matrix version of the nonequilibrium Green's function method enables calculation of the transmission coefficients at a given energy and voltage in a self-consistent manner as well as the corresponding current-voltage (I-V) characteristics. This scheme has advantages because it is applicable to large systems, easily transportable to different types of quantum chemistry packages, and extendable to time-dependent phenomena or inelastic scatterings. It has been applied to diverse types of practical electronic devices such as carbon nanotubes, graphene nanoribbons, metallic nanowires, and molecular electronic devices. The quantum conductance phenomena for systems involving quantum point contacts and I-V curves for a single molecule in contact with metal electrodes using the k-point sampling method are described.     

Electrocatalytic activity of nanoporous Pd and Pt: effect of structural features

The electrocatalytic activities of nanoporous palladium (npPd) and platinum (npPt) for oxygen reduction reaction (ORR) under alkaline conditions and hydrogen peroxide electrochemical reactions under neutral conditions were examined. npPd and npPt were prepared by the electrochemical deposition of each metal from the corresponding metal precursor in the presence of reverse micelles of Triton X-100, directing highly porous microstructures. The nanoporous catalysts showed excellent electrocatalytic activity for both the ORR and hydrogen peroxide electrochemical oxidation/reduction due to the increased active surface area. In particular, the npPd exhibited superior ORR activity (i.e., more positive onset and half-wave potentials, higher current density and greater number of electrons transferred) despite the smaller roughness factor than the npPt and commercial Pt. The catalytic activity for the hydrogen peroxide electrochemical reactions was also higher while using npPd (i.e., faster electrode reaction kinetics, increased current densities, etc.) compared to npPt. The higher catalytic activity of npPd than that of npPt suggests an advantage of the unique npPd structure, composed of nano- as well as micro-porosity, in facilitating mass transport through the porous metal layer. The npPd exhibited amperometric current responses, induced by the oxidation as well as reduction of hydrogen peroxide, linearly proportional to the hydrogen peroxide concentration with a rapid response time (<~2 s), high sensitivity, and low detection limit (<1.8 μM).     

C-H activation: a complementary tool in the total synthesis of complex natural products

The recent advent of transition-metal mediated C-H activation is revolutionizing the synthetic field and gradually infusing a "C-H activation mind-set" in both students and practitioners of organic synthesis. As a powerful testament of this emerging synthetic tool, applications of C-H activation in the context of total synthesis of complex natural products are beginning to blossom. Herein, recently completed total syntheses showcasing creative and ingenious incorporation of C-H activation as a strategic manoeuver are compared with their "non-C-H activation" counterparts, illuminating a new paradigm in strategic synthetic design.     

C?H Activation: A Complementary Tool in the Total Synthesis of Complex Natural Products

The recent advent of transition‐metal mediated C? H activation is revolutionizing the synthetic field and gradually infusing a “C? H activation mind‐set” in both students and practitioners of organic synthesis. As a powerful testament of this emerging synthetic tool, applications of C? H activation in the context of total synthesis of complex natural products are beginning to blossom. Herein, recently completed total syntheses showcasing creative and ingenious incorporation of C? H activation as a strategic manoeuver are compared with their “non‐C? H activation” counterparts, illuminating a new paradigm in strategic synthetic design.     

In vitro induction of anterior gradient-2-specific cytotoxic T lymphocytes by dendritic cells transduced with recombinant adenoviruses as a potential therapy for colorectal cancer

Anterior gradient-2 (AGR2) promotes tumor growth, cell migration, and cellular transformation, and is one of the specific mRNA markers for circulating tumor cells in patients with gastrointestinal cancer. We investigated the feasibility of AGR2 as a potent antigen for tumor immunotherapy against colorectal cancer (CRC) cells using dendritic cells (DCs) transduced with a recombinant adenovirus harboring the AGR2 gene (AdAGR2). DCs transduced with a recombinant adenovirus encoding the AGR2 gene (AdAGR2/DCs) were characterized. These genetically-modified DCs expressed AGR2 mRNA as well as AGR2 protein at a multiplicity of infection of 1,000 without any significant alterations in DC viability and cytokine secretion (IL-10 and IL-12p70) compared with unmodified DCs as a control. In addition, AdAGR2 transduction did not impair DC maturation, but enhanced expression of HLA-DR, CD80, and CD86. AdAGR2/DCs augmented the number of IFN-γ-secreting T-cells and elicited potent AGR2-specific cytotoxic T lymphocytes capable of lysing AGR2-expressing CRC cell lines. These results suggest that AGR2 act as a potentially important antigen for immunotherapy against CRC in clinical applications.     

In-situ probe of gate dielectric-semiconductor interfacial order in organic transistors: origin and control of large performance sensitivities

Organic thin film transistor (OTFT) performance is highly materials interface-dependent, and dramatic performance enhancements can be achieved by properly modifying the semiconductor/gate dielectric interface. However, the origin of these effects is not well understood, as this is a classic "buried interface" problem that has traditionally been difficult to address. Here we address the question of how n-octadecylsilane (OTS)-derived self-assembled monolayers (SAMs) on Si/SiO(2) gate dielectrics affect the OTFT performance of the archetypical small-molecule p-type semiconductors P-BTDT (phenylbenzo[d,d]thieno[3,2-b;4,5-b]dithiophene) and pentacene using combined in situ sum frequency generation spectroscopy, atomic force microscopy, and grazing incidence and reflectance X-ray scattering. The molecular order and orientation of the OTFT components at the dielectric/semiconductor interface is probed as a function of SAM growth mode in order to understand how this impacts the overlying semiconductor growth mode, packing, crystallinity, and carrier mobility, and hence, transistor performance. This understanding, using a new, humidity-specific growth procedure, leads to a reproducible, scalable process for highly ordered OTS SAMs, which in turn nucleates highly ordered p-type semiconductor film growth, and optimizes OTFT performance. Surprisingly, the combined data reveal that while SAM molecular order dramatically impacts semiconductor crystalline domain size and carrier mobility, it does not significantly influence the local orientation of the overlying organic semiconductor molecules.     

Analytical estimation of liquid film thickness in two-phase annular flow using electrical resistance measurement

This paper presents an analytical solution to estimate the liquid film thickness in two-phase annular flow through a circular pipe using electrical resistance tomography. Gas–liquid flow with circular gas core surrounded by a liquid film is considered. Conformal mapping is employed to obtain the analytic solution for annular flow with an eccentric circular gas core. The liquid film thickness for an arbitrary annular flow is estimated by comparing the resistance values for concentric and eccentric annular flows. The film thickness estimation has a good performance when the normalized distance between the gas core center and the flow center is less than 0.2 and the void fraction is greater than 0.4, the estimated error of the normalized thickness is less than 0.04.     

Multilayer transfer printing on microreservoir-patterned substrate employing hydrophilic composite mold for selective immobilization of biomolecules

In this study, we introduce a hydrophilic composite mold with elasticity and moderate water permeability, suitable for transferring water-soluble polar molecules such as polyelectrolyte multilayer. This composite mold is constructed from two UV-curable polymers-Norland Optical Adhesives (NOA) 63, a urethane-related polymer, and poly(ethylene glycol) diacrylate (PEGDA). The mixture of inherently hard NOA 63 and hydrogel precursor, PEGDA, resulted in an optically transparent mold with some degree of elasticity and enhanced water permeability upon UV polymerization. Employing the NOA 63-PEGDA composite mold, a polyelectrolyte multilayer comprising alternate thin layers of poly(acrylic acid) (PAA) and poly(acrylamide) (PAAm) was transfer-printed onto arrays of microreservoir-patterned substrate to selectively prevent unwanted adsorption of biomolecules on the protruding surface. Antibody was immobilized selectively inside the microreservoirs where multilayer was not transferred, and a specific antibody binding reaction was detected inside the microreservoirs. Furthermore, the potential of this composite mold as a convenient tool for constructing a biosensor for detecting Escherichia coli (E. coli) O157:H7 was explored.     

Grid-based Thomas-Fermi-Amaldi equation with the molecular cusp condition

First, the Thomas-Fermi-Amaldi (TFA) equation was formulated with a newly derived condition to remove the singularities at the nuclei, which coincided with the molecular cusp condition. Next, the collocation method was applied to the TFA equation using the grid-based density functional theory. In this paper, the electron densities and the radial probabilities for specific atoms (He, Be, Ne, Mg, Ar, Ca) were found to agree with those from the Thomas-Fermi-Dirac (TFD) method. Total energies for specific atoms (He, Ne, Ar, Kr, Xe, Rn) and molecules (H2,CH4) were also found to be close to those from the Hartree-Fock method using the Pople basis set 6-311G relative to the TFD method. In addition, the computational expense to determine the electron density and its corresponding energy for a large scale structure, such as a carbon nanotube, is shown to be much more efficient compared to the conventional Hartree-Fock method using the 6-31G Pople basis set.     

A study of the radical-radical reaction dynamics of O(3P)+t-C4H9 --> OH+iso-C4H8

The radical-radical reaction dynamics of ground-state atomic oxygen [O(3P)] with t-butyl radicals (t-C4H9) in the gas phase were investigated using high-resolution laser spectroscopy in a crossed-beam configuration, together with ab initio theoretical calculations. The radical reactants, O(3P) and t-C4H9, were produced by the photodissociation of NO2 and the supersonic flash pyrolysis of the precursor, azo-t-butane, respectively. A new exothermic channel, O(3P)+t-C4H9 --> OH+iso-C4H8, was identified and the nascent rovibrational distributions of the OH (X 2Pi: upsilon" = 0,1,2) products were examined. The population analyses for the two spin-orbit states of F1(2Pi32) and F2(2Pi12) showed that the upsilon" = 0 level is described by a bimodal feature composed of low- and high-N" rotational components, whereas the upsilon" = 1 and 2 levels exhibit unimodal distributions. No noticeable spin-orbit or Lambda-doublet propensities were observed in any vibrational state. The partitioning ratio of the vibrational populations (Pupsilon") with respect to the low-N" components of the upsilon" = 0 level was estimated to be P0:P1:P2 = 1:1.17+/-0.24:1.40+/-0.11, indicating that the nascent internal distributions are highly excited. On the basis of the comparison of the experimental results with the statistical theory, the reaction mechanism at the molecular level can be described in terms of two competing dynamic pathways: the major, direct abstraction process leading to the inversion of the vibrational populations, and the minor, short-lived addition-complex process responsible for the hot rotational distributions. After considering the reaction exothermicity, the barrier height, and the number of intermediates along the addition reaction pathways on the lowest doublet potential energy surface, the formation of CH3COCH3(acetone)+CH3 was predicted to be dominant in the addition mechanism.