Reactions of formaldehyde and methanol on clean,carburized and oxidized Mo(100) surfaces

The reactions of formaldehyde and methanol have been studied on clean, carburized, and oxidized Mo(100) surfaces using temperature programmed reaction spectroscopy (TPRS). The thermal cracking of ethylene at 550 K and the adsorption of molecular oxygen at 1050 K were used to carburize and oxidize, respectively, the clean surface to saturation. Both the carbide and oxide surfaces showed (1×1) LEED features. Methanol decomposed to give hydrogen atoms and methoxy intermediates upon adsorption on the clean Mo(100) surface at 200 K. The methoxy intermediate was stable up to 340 K. Adsorbed carbon and oxygen suppressed the dissociation of the hydroxyl hydrogen from the alcohol and yielded a significantly different activity and selectivity compared to the very reactive clean surface. The binding energies for both formaldehyde and methanol on the three surfaces were similar, demonstrating the weak sensitivity of donor-acceptor bonds to surface modifiers. The results in this study were very similar to those previously observed for W(100) though different adlayer structures were present. This similarity suggested that the modification in surface reactivity was primarily a compositional effect.     

Halide–Amine Co‐Passivated Indium Phosphide Colloidal Quantum Dots in Tetrahedral Shape

Wet chemical synthesis of covalent III‐V colloidal quantum dots (CQDs) has been challenging because of uncontrolled surfaces and a poor understanding of surface–ligand interactions. We report a simple acid‐free approach to synthesize highly crystalline indium phosphide CQDs in the unique tetrahedral shape by using tris(dimethylamino) phosphine and indium trichloride as the phosphorus and indium precursors, dissolved in oleylamine. Our chemical analyses indicate that both the oleylamine and chloride ligands participate in the stabilization of tetrahedral‐shaped InP CQDs covered with cation‐rich (111) facets. Based on density functional theory calculations, we propose that fractional dangling electrons of the In‐rich (111) surface could be completely passivated by three halide and one primary amine ligands per the (2×2) surface unit, satisfying the 8‐electron rule. This halide–amine co‐passivation strategy will benefit the synthesis of stable III‐V CQDs with controlled surfaces.     

On (<Emphasis Type="Italic">m</Emphasis>, <Emphasis Type="Italic">C</Emphasis>)-Isometric Operators

In this paper we study the spectral properties of (m, C)-isometric operators. In particular, if \(T\in \mathcal{{L(H)}}\) is (m, C)-isometric operators, then the power of (m, C)-isometric operators is also (m, C)-isometric operators. Moreover, if \(T^{*}\) has the single-valued extension property, then T has the single-valued extension property. Finally, we investigate conditions for (m, C)-isometric operators to be (1, C)-isometric operators.     

Nox reduction with CO over supported Pd catalysts under simulated post Euro-IV diesel exhaust conditions

The catalytic reduction of NO_x with CO over Pd/Al₂O₃ and Pd/TiO₂/Al₂O₃ under simulated post Euro-IV diesel exhaust conditions was studied. The catalytic activities obtained by using various Pd and TiO₂ loadings and total amounts of reductant and the influence of H₂ and H₂O was investigated.     

Sensitive analysis of donepezil in plasma by capillary electrophoresis combining on-column field-amplified sample stacking and its application in Alzheimer's disease

Field-amplified sample stacking (FASS) in capillary electrophoresis (CE) was used to determine the concentration of donepezil, an acetylcholinesterase inhibitor, in human plasma. A sample pretreatment by liquid-liquid extraction with isopropanol/n-hexane (v/v 3:97) and subsequent quantification by FASS-CE was used. Before sample loading, a water plug (0.5 psi, 6 s) was injected to permit FASS. Electrokinetic injection (7 kV, 90 s) was used to introduce sample cations. The separation condition for donepezil was performed in electrolyte solutions containing Tris buffer (60 mM, pH 4.0) with sodium octanesulfonate 40 mM and 0.01% polyvinyl alcohol as a dynamic coating to reduce analytes' interaction with capillary wall. The separation was performed at 28 kV and detected at 200 nm. Using atenolol as an internal standard, the linear ranges of the method for the determination of donepezil in human plasma were over a range of 1-50 ng/mL. The limit of detection was 0.1 ng/mL (S/N=3, sampling 90 s at 7 kV). One female volunteer (54 years old) was orally administered a single dose of 10 mg donepezil (Aricept, Eisai), and blood samples were drawn over a 60 h period for pharmacokinetic study. The method was also applied successfully to monitor donepezil in sixteen Alzheimer's disease patients' plasmas.     

Cation-selective exhaustive injection and sweeping micellar electrokinetic chromatography for analysis of morphine and its four metabolites in human urine

A cation-selective exhaustive injection and sweeping micellar EKC (CSEI-Sweep-MEKC) was established to analyze morphine and its four metabolites, including codeine, normorphine (NM), morphine-3-glucuronide (M3G), and morphine-6-glucuronide (M6G). After SPE, the urine samples were analyzed by this CE method. The phosphate buffer (75 mM, pH 2.5) containing 30% methanol was first filled into an uncoated fused-silica capillary (40 cm, 50 microm id), then a high-conductivity buffer (120 mM phosphate, 10.3 kPa for 99.9 s) followed. The pretreated urine sample was loaded by electrokinetic injection (10 kV, 600 s). The stacking and separation were performed by using phosphate buffer (25 mM, pH 2.5) containing 22% methanol and 100 mM SDS at -20 kV, and detected at 200 nm. During method validation, calibration plots were linear (r > or = 0.998) over a range of 30-3000 ng/mL for morphine, NM, and codeine, 100-2000 ng/mL for M6G, and 80-3200 ng/mL for M3G. The LODs (S/N = 5, sampling 600 s at 10 kV) were 10 ng/mL for morphine, NM, and codeine, 35 ng/mL for M6G, and 25 ng/mL for M3G. This stacking CE method could increase 2500-fold sensitivity of codeine, when comparing with CZE. Five addicts' urine specimens were analyzed. Their results were compared with those of LC-MS-MS, and showed good coincidence. This method could be feasible for monitoring morphine and its metabolites in forensic interest and pharmacokinetic investigations.     

Growth of high-aspect-ratio gold nanowires on silicon by surfactant-assisted galvanic reductions

A simple galvanic reduction for direct growth of Au nanowires on silicon wafers is developed. The nanowires were prepared by reacting HAuCl4aq with Sns in the presence of CTACaq (cetyltrimethylammonium chloride) and NaNO3aq, which were important to the product morphology development. The nanowire diameter was 50-100 nm, and the length was more than 20 microm.     

Hydrodynamic flows in electrowetting

Hydrodynamic flows are generated inside a droplet in electrowetting when an ac voltage is applied. To discover the characteristics and origin of the flows, we investigated the flow pattern for a sessile droplet for various needle-electrode positions, electrolyte concentrations, and applied electrical frequencies. Two distinct types of flows were observed under current experimental conditions. In the typical experimental condition, a quite fast flow appears in the low-frequency range of about 10 Hz to 15 kHz. A different type of flow is observed in the high-frequency range of about 35 to 256 kHz, but this frequency range depends significantly on the electrolyte concentration. Most typically, the flow directions are different for the two flows. A shape oscillation of a droplet was observed in the low-frequency range by a high-speed camera. The flow in the low-frequency range is insensitive to the conductivity of the solution and may be caused by the interfacial oscillation of the droplet. The flow at high frequency is very sensitive to the conductivity of the solution and electrode position, so the high-frequency flow is believed to be caused by some electrohydrodynamic effect.     

Minimalism in fabrication of self-organized nanogels holding both anti-cancer drug and targeting moiety

Recent researches to develop nano-carrier systems in anti-cancer drug delivery have focused on more complicated design to improve therapeutic efficacy and to reduce side effects. Although such efforts have great impact to biomedical science and engineering, the complexity has been a huddle because of clinical and economic problems. In order to overcome the problems, a simplest strategy to fabricate nano-carriers to deliver doxorubicin (DOX) was proposed in the present study. Two significant subjects (i) formation of nanoparticles loading and releasing DOX and (ii) binding specificity of them to cells, were examined. Folic acid (FA) was directly coupled with pullulan (Pul) backbone by ester linkage (FA/Pul conjugate) and the degree of substitution (DS) was varied, which were confirmed by 1H NMR and UV spectrophotometry. Light scattering results revealed that the nanogels possessed two major size distributions around 70 and 270 nm in an aqueous solution. Their critical aggregation concentrations (CACs) were less than 10 microg/mL, which are lower than general critical micelle concentrations (CMCs) of low-molecular-weight surfactants. Transmission electron microscopy (TEM) images showed well-dispersed nanogel morphology in a dried state. Depending on the DS, the nanogels showed different DOX-loading and releasing profiles. The DOX release rate from FA8/Pul (with the highest DS) for 24h was slower than that from FA4/or FA6/Pul, indicating that the FA worked as a hydrophobic moiety for drug holding. Cellular uptake of the nanogels (KB cells) was also monitored by confocal microscopy. All nanogels were internalized regardless of the DS of FA. Based on the results, the objectives of this study, to suggest a new method overcoming the complications in the drug carrier design, were successfully verified.