Fabrication of a miniature twin-fuel-cell on silicon wafer

The fabrication and performance evaluation of a miniature twin-fuel-cell on silicon wafers are presented in this paper. The miniature twin-fuel-cell was fabricated in series using two membrane-electrode-assemblies sandwiched between two silicon substrates in which electric current, reactant, and product flow. The novel structure of the miniature twin-fuel-cell is that the electricity interconnect from the cathode of one cell to the anode of another cell is made on the same plane. The interconnect was fabricated by sputtering a layer of copper over a layer of gold on the top of the silicon wafer. Silicon dioxide was deposited on the silicon wafer adjacent to the copper layer to prevent short-circuiting between the twin cells. The feed holes and channels in the silicon wafers were prepared by anisotropic silicon etching from the back and front of the wafer with silicon dioxide acting as intrinsic etch-stop layer. Operating on dry H-2/O-2 at 25 degreesC and atmospheric pressure, the measured peak power density was 190.4 mW/cm(2) at 270 mA/cm(2) for the miniature twin-fuel-cell using a Nafion 112 membrane. Based on the polarization curves of the twin-fuel-cell and the two single cells, the interconnect resistance between the twin cells was calculated to be in the range from 0.0113 Omega (at 10 mA/cm(2)) to 0.0150 Omega (at 300 mA/cm(2)), which is relatively low. (C) 2003 Elsevier Science Ltd. All rights reserved.

Immobilized metal-ion chelating capillary microreactor for peptide mapping analysis of proteins by matrix assisted laser desorption/ionization-time of flight-mass spectrometry

Peptide mass mapping analysis, utilizing a regenerable enzyme microreactor with metal-ion chelated adsorption of enzyme, combined with matrix assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS) was developed. Different procedures from the conventional approaches were adopted to immobilize the chelator onto the silica supports, that is, the metal chelating agent of iminodiacetic acid (IDA) was reacted with glycidoxypropyltrimethoxysilane (GLYMO) before its immobilization onto the inner wall of the fused-silica capillary pretreated with NH4HF2. The metal ion of copper and subsequently enzyme was specifically adsorbed onto the surface to form the immobilized enzyme capillary microreactor, which was combined with MALDI-TOF-MS to apply for the mass mapping analysis of nL amounts of protein samples. The results revealed that the peptide mapping could routinely be generated from 0.5 pmol protein sample in 15 min at 50degreesC, even 20 fmol cytochrome c could be well digested and detected.

Controllable synthesis of metal hydroxide and oxide nanostructures by ionic liquids assisted electrochemical corrosion method

Cu(OH)(2) nanowires have been synthesized by anodic oxidation of copper through a simple electrolysis process employing ionic liquid as an electrolyte. Controlling the electrochemical conditions can qualitatively modulate the lengths, amounts, and shapes of Cu(OH)(2) nanostructures. A rational mechanism based on coordination self-assembly and oriented attachment is proposed for the selective formation of the polycrystalline Cu(OH)(2) nanowires. In addition, the FeOOH nanoribbons, Ni(OH)(2) nanosheets, and ZnO nanospheres were also synthesized by this route, indicative of the universality of the electrochemical route presented herein. The morphologies and structures of the synthesized nanostructures have been characterized by transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), powder X-ray diffraction (XRD). Fourier transform infrared spectra (FT-IR), and thermogravimetric (TG). (C) 2007 Elsevier Masson SAS. All rights reserved

Charge transport in accumulation layers of organic heterojunctions

We studied the charge transport in organic heterojunction films consisting of copper phthalocyanine (CuPc) and copper hexadecafluorophthalocyanine (F16CuPc). The heterojunction effect between CuPc and F16CuPc induced high-density carriers at both sides of heterojunction. The Hall effect was observed at room temperature, which demonstrated the existence of free carriers and their delocalized transport under heterojunction effect. The Hall mobility of 1.2 cm(2)/V s for holes and 2.4 cm(2)/V s for electrons indicated that the transport capability of the heterojunction films is comparable to single crystals. The transport process was further explained by the multiple trap-and-release model according to the temperature dependence of conduction.

Copper(I)-Catalyzed Aryl Bromides To Form Intermolecular and Intramolecular Carbon-Oxygen Bonds

A highly efficient Cu-catalyzed C-O bond-forming reaction of alcohol and aryl bromides has been developed. This transformation was realized through the use of copper(I) iodide as a catalyst, 8-hydroxyquinoline as a ligand, and K3PO4 as a base. A variety of functionalized substrates were found to react under these reaction conditions to provide products in good to excellent yields.

Turn-on fluorescent cyanide sensor based on copper ion-modified CdTe quantum dots

A new fluorescent sensor for the sensitive and selective detection of cyanide (CN-) in aqueous media was developed herein. The sensing approach is based on CN--modulated quenching behavior of Cu2+ toward the photoluminescence (PL) of CdTe quantum dots (QDs). In the presence of CN-, the PL of QDs that have been quenched by Cu2+ was found to be efficiently recovered, which then allows the detection of CN- in a very simple approach. Experimental results showed that the pH of the buffer solution, concentration of copper ions, and size of CdTe QDs all influenced the response of the sensor to CN-. Under the optimal conditions, a good linear relationship between the PL intensity and the concentration of CN- can be obtained in the range of 3.0 x 10(-7) to 1.2 x 10(-5) M, with a detection limit as low as 1.5 x 10(-7) M. In addition, the present fluorescent sensor possesses remarkable selectivity for cyanide over other anions, and negligible influences were observed on the cyanide detection by the coexistence of other anions or biological species (such as albumin and typical blood constituents).

Copper phthalocyanine based hybrid p-type permeable-base transistor in vertical architecture

We demonstrate the production of copper phthalocyanine (CuPc) based p-type hybrid permeable-base transistors, which operate at low voltages having high common-base current gains. These transistors are prepared by evaporating a thin metal layer (Ag or Al) that acts as base on top of a Si substrate that acts as collector. In the sequence CuPc and Au are thermally sublimated to produce the emitter, constituting a quite simple device production procedure with the additional advantage of allowing higher integration due to its vertical architecture.

Investigation of charge-carrier injection characteristics in NPB/Alq3 heterojunction devices

The effect of copper phthalocyanine (CuPc) and LiF interfacial layers on the charge-carrier injection in NN'-di(naphthalene-l-yl)N,N'-diphenyl-benzidine (NPB)/tris(8-hydroxyquinoline) aluminium (Alq(3)) organic heterojunction devices have been studied through the analysis of current-voltage characteristics. The investigation clearly demonstrated that the hole injection into NPB from anode is Fowler-Nordheim (FN) tunneling and the electron injection into Alq3 from cathode is Richardson-Schottky (RS) thermionic emission. The barrier heights obtained from the FN and RS models proved that the band alignments for charge-carrier injection are greatly improved by the CuPc and LiF interfacial layers, which should fully clarify the role of the interfacial layer on the improvement of device performance.

Self-assembling process of alkanethiol monolayers on gold surface via underpotential deposition

It was demonstrated feasible that underpotential deposition(UPD) of copper on a monolayer-modified gold substrate can be used to determine the gold electrode area. The deposition and stripping of a Cu adlayer can take Place reversibly and stably at a bared or a self-assembled monolayer modified gold electrode. The growth kinetics of decanethiol/Au was also investigated via Cu UPD. The difference between the assembling kinetics determined by UPD and that by quartz crystal microbalance measurements reveals the configuration transmutation of the assembled molecules from a disordered arrangement to an ordered arrangement during the self-assembling processes.

Technique for determination of gold electrode area and its application of characterization in self-assembling process

Underpotential deposition(UPD) of copper at polycrystal gold surface under different concentrations has been studied, and its reversibility and stability in high concentration (0.2M CuSO4+0.IM H2SO4) have been demonstrated by cyclic voltermmetry and EQCM. A Valid approach to determine the gold electrode area in presence of adsorbed species has been provided by using Cu UPD method. Further, the growth kinetics of decane thiol on gold has also been investigated based on such a Cu UPD technique.

A method to identify the collapse of monolayers at the air-water interface

The collapse behaviour of phthalocyanine monolayers at the air-water interface was studied by means of compression-expansion isotherms. Measurements of two cycles of compression-expansion isotherms of copper tetrakis (4'-benzyloxy-4-phenylsulfonylphenoxy) phthalocyanine showed that the difference in the area per molecule at target pressure between the first cycle and the second cycle was dependent on the target pressure. This difference was used to identify the collapse of monolayers at the air-water interface. The transfer behaviour of monolayers at the air-water interface onto a substrate at different target pressures was also studied.

APPLICATION OF FACTOR-ANALYSIS TO CORRECTION OF SPECTRAL OVERLAP INTERFERENCE IN INDUCTIVELY COUPLED PLASMA ATOMIC EMISSION-SPECTROMETRY

Correction of spectral overlap interference in inductively coupled plasma atomic emission spectrometry by factor analysis is attempted. For the spectral overlap of two known lines, a data matrix can be composed from one or two pure spectra and a spectrum of the mixture. The data matrix is decomposed into a spectra matrix and a concentration matrix by target transformation factor analysis. The component concentration of interest in a binary mixture is obtained from the concentration matrix and interference from the other component is eliminated. This method is applied to correcting spectral interference of yttrium on the determination of copper and aluminium: satisfactory results are obtained. This method may also be applied to correcting spectral overlap interference for more than two lines. Like other methods of correcting spectral interferences, factor analysis can only be used for additive spectral overlap. Results obtained from measurements on copper/yttrium mixtures with different white noise added show that random errors in measurement data do not significantly affect the results of the correction method.

SERRS OF PHTHALOCYANINE DERIVATIVES LB MONOLAYER

SERRS of copper tetrakis(2,4-ditert-penthyl phenoxy) Phthalocyanine LB monolayer on Ag island film and RRS of the compound in solid state have been obtained. On comparison between the spectra, it is proposed that the macrocycle of the molecule on the Ag substrate is oriented parallel to the surface.

Distribution and their pollution assessment of heavy metals in the sediments of the Yalu River Estuary and its adjacent coastal waters

The present paper deals with the distribution patterns of heavy metals and the associated influencing factors in the Yalu River Estuary and its adjacent coastal waters. Based upon the analysis of the surficial and core sediments measurements, the pollution of heavy metal and potential ecological risk were evaluated. The burial flux and contents of heavy metals (except for copper) have been continuously increasing since the 1920s. Therefore, the gross potential ecological risk for the sediments was high or very high, and the study area was endangered by heavy metals contamination. Heavy metals originated mainly from upstream pollutant input, correlation analysis showed that chromium, nickel, zinc, cadmium, lead, arsenic, and mercury in the sediments of the middle and west channels as well as the sea area of the western Yalu River Estuary concentrations were most probably derived from similar sources. In contrast, the metal of copper most probably originated from sources different from the other metals. Preliminary studies indicate that copper contamination was most likely the result of emission from mining activities situated at the upstream of the river. The contents of heavy metals in the sediments of estuarine turbidity maximum zone of Yalu River were larger than those of any other areas in the middle channel. With large portion of fine sediments, weaker hydrodynamics, and richer sources of heavy metals, the sediments of the west channel, were even more enriched with heavy metals than those of the middle channel.

Microscale mechanics for metal thin film delamination along ceramic substrates

The metal thin film delamination along metal/ceramic interface in the case of large scale yielding is studied by employing the strain gradient plasticity theory and the material microscale effects are considered. Two different fracture process models are used in this study to describe the nonlinear delamination phenomena for metal thin films. A set of experiments have been done on the mechanism of copper films delaminating from silica substrates, based on which the peak interface separation stress and the micro-length scale of material, as well as the dislocation-free zone size are predicted.