Glass/PDMS hybrid microfluidic device integrating vertically aligned SWCNTs to ultrasensitive electrochemical determinations

This communication reports a promising platform for rapid, simple, direct, and ultrasensitive determination of serotonin. The method is related to integration of vertically aligned single-walled carbon nanotubes (SWCNTs) in electrochemical microfluidic devices. The required microfabrication protocol is simple and fast. In addition, the nanomaterial influenced remarkably the obtained limit-of-detection (LOD) values. Our system achieved a LOD of 0.2 nmol L(-1) for serotonin, to the best of our knowledge one of the lowest values reported in the literature.     

Synthesis,Characterization, Electronic and Gas‐Sensing Properties towards H2 and CO of Transparent,Large‐Area,Low‐Layer Graphene

Low‐layered, transparent graphene is accessible by a chemical vapor deposition (CVD) technique on a Ni‐catalyst layer, which is deposited on a <100> silicon substrate. The number of graphene layers on the substrate is controlled by the grain boundaries in the Ni‐catalyst layer and can be studied by micro Raman analysis. Electrical studies showed a sheet resistance (R_sheet) of approximately 1435 Ω per □, a contact resistance (R_c) of about 127 Ω, and a specific contact resistance (R_sc) of approximately 2.8×10^?4 Ω cm² for the CVD graphene samples. Transistor output characteristics for the graphene sample demonstrated linear current/voltage behavior. A current versus voltage (I_ds–V_ds) plot clearly indicates a p‐conducting characteristic of the synthesized graphene. Gas‐sensor measurements revealed a high sensor activity of the low‐layer graphene material towards H₂ and CO. At 300 °C, a sensor response of approximately 29 towards low H₂ concentrations (1 vol %) was observed, which is by a factor of four higher than recently reported.     

Structure selection based on high vertical electron affinity for TiO2 clusters

We study the structure and electronic properties of (TiO2)(2-10) clusters by using basin hopping based on density functional theory, combined with many-body perturbation theory. We show that in photoemission experiments performed on anions isomers with high electron affinity are selectively observed rather than those with the lowest energy. These isomers possess a highly reactive Ti3+ site. The selectivity for highly reactive clusters may be exploited for applications in catalysis.     

Comparison of Young's modulus and specific heat anomalies at the magnetic transition in α′-NaV2O5

We have measured Young's modulus (using a vibrating reed technique) and the specific heat (using ac calorimetry) on the same crystals of α′-NaV₂O₅ at its T_c=34 K magnetic phase transition. Both properties exhibit large, unsymmetrical, and sample-dependent anomalies. While the specific heat results suggest tricritical behavior of the transition, large fluctuation effects are observed in the modulus above T_c. Fits of the modulus in terms of the specific heat, entropy, and free energy suggest that fluctuations are strongly stress- and sample-dependent.     

Unsteady oblique shock waves

A spatially and temporally local analysis is provided for unsteady, oblique shock waves, in which the flow is assumed to be two-dimensional or axisymmetric. Three unsteady parameters, in a laboratory frame, are viewed as the known independent variables. These are the upstream Mach number, the shock Mach number, and the angle of the shock relative to the instantaneous upstream velocity. Other steady and unsteady parameters, such as the velocity turn angles and downstream Mach numbers, are evaluated in closed form, in terms of these three quantities. Trends are assessed, and a sensitivity analysis is provided. It is suggested that the theory may find application in converting a shock capturing algorithm, at an early time during the computational process, into a shock fitting algorithm. Received 30 April 1999 / Accepted 29 November 1999     

Die Ordnungsfunktionen einer Geometrie

Ohne ZusammenfassungÜber diesen Gegenstand habe ich zum ersten Mal im November 1943 in Bukarest und Timisoara Vorträge gehalten.     

Die ein-eindeutigen punkttransformationen der ebene

Ohne Zusammenfassung     

Transmetallation of Bis(6-diphenylphosphinoacenaphth-5-yl)-Mercury and -Tributyltin with Precious Metal Chlorides

The reaction of bis(6-diphenylphosphinoacenapht-5yl)mercury, (6-Ph₂P-Ace-5-)₂Hg, with [(CO)₂RhCl]₂ and PtCl₂ proceeded with extrusion of mercury / mercury(I) chloride and provided the octahedral rhodium and platinum complexes (6-Ph₂P-Ace-5-)₂Rh(CO)Cl and (6-Ph₂P-Ace-5-)₂PtCl₂, respectively. The reaction of the (6-diphenylphosphinoacenapht-5yl)stannane 6-Ph₂P-Ace-5-SnBu₃ with PdCl₂ gave rise to tributyltin chloride and a dimeric arylpalladium chloride [(6-Ph₂P-Ace-5-)PdCl]₂ with a planar Pd₂Cl₂ core. Together with the previously known gold(III) complex cis- and trans-[R₂Au][Cl], the newly prepared compounds were investigated by DFT calculations. The fully optimized gas-phase structure of [(6-Ph₂P-Ace-5-)PdCl]₂ gives rise to a bend Pd₂Cl₂ core featuring a Pd ··· Pd palladophilic interaction. The bonding situation was studied using a set of real-space bonding indicators (RSBIs) derived from the methods Atoms-In-Molecules (AIM), Electron Localizability Indicator (ELI-D) and Non-Covalent Interaction (NCI) index.