Immobilization of aminophenylboronic acid on magnetic beads for the direct determination of glycoproteins by matrix assisted laser desorption ionization mass spectrometry

Aminophenylboronic acid (APBA) has been immobilized on magnetic beads for the direct determination of glycoprotein by matrix assisted laser desorption/ionizaton time of flight mass spectrometry (MALDI-TOF-MS). An APBA layer was formed on the surface of carboxylic acid terminated magnetic beads by coupling with carbodiimide and subsequently reacted with an N-hydroxysuccinimide moiety. The immobilized APBA was identified by MALDI-TOF-MS without a matrix. Glycoproteins, such as HbA1c, fibrinogen, or RNase B were separated and desalted using APBA magnetic beads by simply washing the magnetic beads and then separating them by external magnet. Proteins can be identified by direct determination of proteins on beads on MALDI plate and confirmed again by peptide mass finger printing after digestion of proteins on magnetic beads by trypsin. Fluorescence image with a FITC tagging protein using confocal laser microscopy showed the difference of immobilization efficiency between glycoproteins and nonglycoproteins. The methods developed within this work allow the simple treatment and enrichment of glycoproteins as well as direct determination of proteins on beads by MALDI-TOF-MS.     

Formation and growth mechanism of dissimilar coiled carbon nanotubes by reduced-pressure catalytic chemical vapor deposition

Dissimilar coiled carbon nanotubes were prepared by catalytic chemical vapor deposition (CCVD) on finely divided Co nanoparticles supported on silica gel under reduced pressure and at lower gas flow rates. The morphology of the regular coiled carbon nanotubes were examined by TEM, while the polygonization characteristics of the helix were examined by SAED. Observations were made on other forms of irregular coils with various shapes by TEM. On the basis of the heptagon-pentagon construction theory, we proposed a helix formation mechanism, which involves a carbon core formation centering on a catalytic particle followed by carbon helices growth controlled by kinetics.     

Chemical and structural effects on the electronic transport in organic single crystals

Effects induced by chemical and structural inhomogeneities on the electronic transport in organic crystals with the focus on highly-ordered polyacenes are discussed in this paper. The material class chosen is of great importance as polyacenes are widely studied with perspectives on applications in thin film devices. As will be shown, the charge carrier mobility in these long-range ordered molecular systems is limited by chemical impurities rather than by structural inhomogeneities. Time-of-flight spectroscopy on polyacenes purified by zone-refinement does not only show coherent carrier movement for holes but also for electrons, which is rarely observed for compounds that can be purified by sublimation only. Finally, we will present a direct comparison between the chemical species and their amount on the surface and in the volume of tetracene crystals. The significantly higher impurity concentration at the surfaces is relevant for the mobility estimated by field-effect transistor (FET) studies on single crystals in planar-geometry.     

La1－xSrxNi1－yCoyO3双功能氧电极的电化学性能

采用溶胶-凝胶法制备了一系列La1－xSrxNi1－yCoyO3（x=0、0.1、0.2、0.5； y=0～1.0）型的钙钛矿催化剂，并以活性碳为载体制备双功能氧电极.对催化剂进行了XRD结构分析以及XPS表面分析.采用三电极体系测试了氧电极的稳态极化曲线和电化学交流阻抗谱并对其阴极极化和阳极极化谱图进行了分析.实验表明，对于LaNiO3化合物，B位掺杂可显著提高催化剂表面的B离子浓度, 从而提高电催化性能；而A位掺杂由于导致有序化氧空位的增多和电导的降低而造成活性下降.电极氧还原反应的极化主要由电荷转移反应和能斯特扩散过程造成.     

Effect of argon plasma treatment on surface-enhanced Raman spectroscopy of polypyrrole deposited on electrochemically roughened gold substrates

In this work, polypyrrole (PPy) films were electrodeposited on electrochemically roughened gold substrates modified by argon plasma treatment. First, a gold substrate was roughened by a triangular-wave oxidation-reduction cycle (ORC) in an aqueous solution containing 0.1 N HCl. Then the roughened gold substrate was further treated by argon plasma. Encouragingly, the surface-enhanced Raman scattering (SERS) spectroscopy of polypyrrole electrodeposited on this roughened gold substrate modified by argon plasma treatment exhibits a higher intensity by 8-fold, as compared with the SERS of PPy electrodeposited on an unmodified roughened gold substrate. Meanwhile, the electropolymerization for pyrrole monomers occurring on the modified roughened gold substrate is easier. Also, the nucleation and growth of electropolymerization of pyrrole monomers on the modified and unmodified gold substrates are different.     

Partial dewetting of polyethylene thin films on rough silicon dioxide surfaces

The effect of roughness on the dewetting behavior of polyethylene thin films on silicon dioxide substrates is presented. Smooth and rough silicon dioxide substrates of 0.3 and 3.2-3.9 nm root-mean-square roughness were prepared by thermal oxidation of silicon wafers and plasma-enhanced chemical vapor deposition on silicon wafers, respectively. Polymer thin films of approximately 80 nm thickness were deposited by spin-coating on these substrates. Subsequent dewetting and crystallization of the polyethylene were observed by hot-stage optical microscopy in reflection mode. During heating, the polymer films melt and dewet on both substrates. Further observations after cooling indicate that, whereas complete dewetting occurs on the smooth substrate surface, partial dewetting occurs for the polymer film on the rough surface. The average thickness of the residual film on the rough surface was determined by ellipsometry to be a few nanometers, and the spatial distribution of the polymer in the cavities of the rough surface could be obtained by X-ray reflectometry. The residual film originates from the impregnation of the porous surface by the polymer fluid, leading to the observed partial dewetting behavior. This new type of partial dewetting should have important practical consequences, as most real surfaces exhibit significant roughness.     

Atom probe tomography characterization of thin copper layers on aluminum deposited by galvanic displacement

″Ultrathin″ metallization layers on the order of nanometers in thickness are increasingly used in semiconductor interconnects and other nanostructures. Aqueous deposition methods are attractive methods to produce such layers due to their low cost, but formation of ultrathin layers has proven challenging, particularly on oxide-coated substrates. This work focused on the formation of thin copper layers on aluminum, by galvanic displacement from alkaline aqueous solutions. Analysis by atom probe tomography (APT) showed that continuous copper films of approximately 1 nm thickness were formed, apparently the first demonstration of deposition of ultrathin metal layers on oxidized substrates from aqueous solutions. The APT reconstructions indicate that deposited copper replaced a portion of the surface oxide film on aluminum. The results are consistent with mechanisms in which surface hydride species on aluminum mediate deposition, either by directly reducing cupric ions or by inducing electronic conduction in the oxide, thus enabling cupric ion reduction by Al metal.     

The back-titration of chemisorbed atomic oxygen on copper by carbon monoxide investigated by microcalorimetry and transient kinetics

The back-titration of atomic oxygen chemisorbed on metallic copper using carbon monoxide is investigated by microcalorimetry. Results from simulations based on a microkinetic model of the back-titration are used for processing of microcalorimetric data. In addition, surface oxidation of copper by nitrous oxide is investigated by microcalorimetry. The results are compared with results obtained by nitrous oxide reactive frontal chromatography and by static oxygen adsorption studied by microcalorimetry. The heat of adsorption of nitrous oxide on copper amounts to 304 kJ mol⁻¹, and the heat of adsorption of carbon monoxide on surfaceoxidized copper is in the range from 120 to 70 kJ mol⁻¹.     

Enhanced fluorescence images for labeled cells on silver island films

Silver island films (SIFs) were deposited on glass substrates to serve as supports. T-Lymphocytic (PM1) cell lines were labeled by Alexa Fluor 680-dextran conjugates on the membranes or by YOYO in the nuclei. The fluorescence images of the cell lines were recorded in the emission intensity and lifetime using scanning confocal microscopy. The fluorescence signals by the fluorophores bound on the cell membranes were enhanced significantly by SIF supports as compared with those on the glass. In addition to the increase in the intensity, there was a dramatic shortening of the emission lifetime. In contrast to the Alexa Fluor 680 fluorophores on the membranes, the YOYO fluorophores intercalated in the cell nuclei were not influenced significantly by the silver islands. This result can be interpreted by an effect of the distance on coupling between the fluorophores and metal particles: the fluorophores on the cell membranes are localized within, but the fluorophores in the cell nuclei are beyond the region of metal-enhanced fluorescence. Thus, the metal supports can be used to improve the detection sensitivity for target molecules on cell surfaces when they are fluorescently labeled.     

Determination of Mg, Ti and Cl in Ziegler-Natta catalysts by WDXRF

A method for determination of Mg, Ti and Cl in Ziegler-Natta (ZN) catalysts by wavelength dispersive X-ray fluorescence (WDXRF) spectrometry was developed. For comparative reasons, Ti was determined by spectrophotometry, Mg by complexometry and Cl by argentometric titration. Direct pressing was shown to be unsuitable for sample preparation due to catalyst decomposition. For Ti and Mg measurements, catalyst samples were calcinated at 1000 °C and pressed at 275 MPa. Their determination by the fundamental parameters based on the Ti Ka line measurement was shown to be equivalent to those results obtained by univariate calibration or by the classical methods. Cl was determined by aqueous extraction, followed by deposition on a support. Chloride loss was observed. Fixation of Cl as AgCl on polytetrafluoroethylene (FHLC) millipore membrane afforded the best results. Nevertheless, measurements by WDXRF were shown to be inferior to those obtained by argentometric titration.     

微波辐射对TiO2制备及其光催化氧化乙醛性能的影响

采用微波辐射与常规加热法由TiO₂溶胶制备出TiO₂催化剂，采用高频低功率微波-光催化装置考察了微波对两种催化剂上CH₃CHO光催化氧化转化率和产物分布的影响。结果表明，微波干燥制备的TiO₂晶体比普通加热制备的TiO₂晶体对乙醛有更高的光催化活性和更强的氧化能力，且它们对乙醛光催化氧化的途径不同，前者的初始中间体为甲醛和甲酸，后者的初始中间体却为乙酸。还发现，微波辐射对两种样品上乙醛的光催化转化率有不同的影响，对微波辐射法所制样品的影响比对常规加热法所制样品的影响显著。微波辐射通过场效应可加速光催化初始中间体的转化，但它不改变光催化反应的途径，反应途径取决于光催化剂的特性。     

Polypyrrole on self-assembled monolayers of a pyrrolyl lipoic acid derivative—electrosynthesis and polymer film characterization

The electropolymerization of pyrrole on gold modified by a self-assembled monolayer (SAM) of a pyrrolyl lipoic acid derivative was investigated in detail and the results compared to those obtained on bare substrates. Both under potentiostatic and potentiodynamic control, a slight blocking action of the underlying SAM could be observed for the initial stages of polymer growth but thereafter the electrochemical features were similar to those collected for polypyrrole (PPy) deposition on bare gold. The morphology and structure of PPy films formed on the SAMs were characterized by atomic force microscopy and X-ray diffraction, which revealed that those polymer properties are much more influenced by the electrochemical mode of preparation, than by the underlying SAMs. While, when compared to PPy on bare gold, no effect has been detected on thin layers deposited at constant potential, surface areas with rather irregular morphology, as well as a small but beneficial influence in inducing order on the first few layers of the polymer film, have been observed on similar films formed by cyclic voltammetry. The typical globular morphology of PPy has always been observed for relatively thick layers in which the redox behavior, analyzed by in situ AFM, showed an increase in volume of the polymer nodules upon reduction, largely due to the SAM reorganization induced by the applied potential.     

Determination of antimony(III,V) in natural waters by separation and preconcentration on a thionalide loaded resin followed by neutron activation analysis

A chelating sorbent obtained by immobilization of thionalide on the macroporous resin Bio Beads SM-7 was used for speciation of antimony(III) and (V) in natural waters. Antimony(III) was separated from Sb(V) by sorption on a column with the sorbent at pH 5. Antimony(V) in the effluent was reduced to Sb(III) and preconcentrated by sorption on the sorbent from 0.5M HCl solution. Both the separated species were determined directly on the sorbent by neutron activation analysis.     

含金属纳米粒子的层层自组装及单壁碳纳米管的催化生长

利用层间的静电吸附作用，重氮树脂和不同种类的含金属纳米粒子被依次吸附到硅片表面形成层层自组装膜。通过改变自组装膜的层数可以控制纳米粒子在表面吸附的量，同时利用重氮树脂的光敏特性可以实现纳米粒子在表面的图案化排布。以这些纳米粒子为催化剂，研究了单壁碳纳米管在硅片表面的化学气相沉积生长。     

Influence of intermolecular interactions on the formation of tetra(carbomethoxy)-tetrathiafulvalene assemblies.

We study the assemblies that tetra(carbomethoxy)tetrathiafulvalene (TCM-TTF) forms in solution and when deposited on a surface depending on intermolecular interactions and on the interactions with the substrate and the solvent. Its organization on graphite and mica substrates was studied by atomic force microscopy, and different molecular assemblies were observed depending on the prevailing interactions. The promotion of molecule-molecule interactions gave rise to the formation of molecular fibers. The investigation of the influence of the solvent-molecule interactions on TCM-TTF molecular organizations was carried out by UV/Vis spectroscopy, and a new TCM-TTF polymorph was obtained by changing the nature of the solvent. Finally, an explanation for all these phenomena, supported by computational modeling, is put forward.     

High activity of Pt(4)Mo alloy for the electrochemical oxidation of formic acid

Surface processes on Pt4Mo alloy well-defined by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) were studied in acid solution by cyclic voltammetry. It was established that Mo in the alloy is much more resistant toward electrochemical dissolution than pure Mo. During the potential cycling of Pt4Mo surfaces in completely quiescent electrolyte, hydrous Mo-oxide could be generated on Mo sites. Investigation of the formic acid oxidation revealed that this type of Mo-oxide enhances the reaction rate by more than 1 order of magnitude with respect to pure Pt. Surface poisoning by CO(ads) is significantly lower on Pt4Mo alloy than on pure Pt. The effect of hydrous Mo-oxide on the HCOOH oxidation rate was explained through the facilitated removal of the poisoning species and through its possible influence on the intrinsic rate of the direct reaction path.     

Investigations on hopeite- and phosphophyllite-containing phosphate coatings on steel

A series of phosphate coatings on steel produced by different procedures and containing differing contents of hopeite and phosphophyllite, are investigated by SEM, XRD, XRF on removed coatings, AES, ESCA, and EDX microanalysis. The morphology of the coatings is mainly determined by the procedure employed (spray or immersion). The hopeite/phosphophyllite ratio of the layers depends on the phosphating bath composition and is quantitatively determinable with sufficient accuracy by XRD, XRF on the removed phosphate layers, and AES. Further results are that an immersion time of more than 60 s does not considerably increase the layer thicknesses and that the first-grown crystalline layers on the steel sheets are hopeite-enriched.     

Evaluation of the responses of a semiconductor gas sensor to gaseous mixtures under the application of temperature modulation

A novel gas-sensing system based on a dynamic nonlinear response is reported to evaluate the effect of gaseous mixtures on the sensor response. A sinusoidal temperature perturbation was applied to a semiconductor gas sensor and the resulting conductance of the sensor was analyzed by fast Fourier transformation (FFT). The sensor response, which changed characteristically depending on the composition of the gaseous mixture, could be classified into three types (enhanced, suppressed, and preferential responses) by the mixture. To monitor the progress of the reaction of gases, the sample gas was analyzed by gas chromatography. The coexistent effect on the response to gaseous mixtures was theoretically simulated by considering the kinetics of gas molecules on the semiconductor surface.     

纳米二氧化钛气相光催化降解三氯乙烯

采用气相色谱－质谱联用方法,Ｘ射线光电子能谱和程序升温脱附方法研究了纳米二氧化钛表面三氯乙烯的气相光催化降解反应。检测到四种新的含三个碳原子的中间体,说明三氯乙烯在反应过程中发生了Ｃ＝Ｃ双键的裂解及加成反应。研究表明,水蒸气对降解反应的影响不公与水蒸气的浓度有关,还与催化剂对水的吸收能力有关。反应副产物在催化剂表面的积累是导致催化剂活性降低的主要原因。催化剂的Ｘ射线光电子能谱显示,反应后催化剂表面     

Selective graphene formation on copper twin crystals

Selective graphene growth on copper twin crystals by chemical vapor deposition has been achieved. Graphene ribbons can be formed only on narrow twin crystal regions with a (001) or high-index surface sandwiched between Cu crystals having (111) surfaces by tuning the growth conditions, especially by controlling the partial pressure of CH(4) in Ar/H(2) carrier gas. At a relatively low CH(4) pressure, graphene nucleation at steps on Cu (111) surfaces is suppressed, and graphene is preferentially nucleated and formed on twin crystal regions. Graphene ribbons as narrow as ～100 nm have been obtained in experiments. The preferential graphene nucleation and formation seem to be caused primarily by a difference in surface-dependent adsorption energies of reactants, which has been estimated by first principles calculations. Concentrations of reactants on a Cu surface have also been analyzed by solving a diffusion equation that qualitatively explains our experimental observations of the preferential graphene nucleation. Our findings may lead to self-organizing formation of graphene nanoribbons without reliance on top-down approaches in the future.