Recently, some harmful compounds and bacteria have been detected from tap water. Particularly, the nitrite nitrogen causes methemoglobinemia and cyanosis for infants. In this study, the surfaces of coffee grounds were carbonized by microwave and carbonaceous materials were produced. The specific surface area of the coffee grounds did not change by carbonization, while the base consumption decreased. Moreover, we estimated the extent of the adsorption of nitrite nitrogen onto the coffee grounds in terms of its removal from tap water. The adsorption mechanism of nitrite nitrogen onto coffee grounds would be monolayer adsorption, because the adsorption isotherms fitted to Freundlich or Langmuir equations. It is suggested that the adsorption of nitrite nitrogen onto coffee grounds is related to the phenolic hydroxyl and carboxyl groups. The coffee grounds thus can be utilized for the removal nitrite nitrogen from tap water.
Monitoring of proteins on biosensor surfaces is required for developing high performance biosensors. In this study, distributions of proteins, protein A and immunogloblin G (IgG), immobilized on glass plates were monitored by means of a new protein monitoring technique using time-of-flight secondary ion mass spectrometry (TOF-SIMS) that provides specific chemical imaging. The TOF-SIMS spectra of the protein immobilized on glass plates were analyzed by means of mutual information to select the appropriate fragment ions related to each protein for chemical imaging of proteins. Finally the distributions of protein A and IgG are obtained respectively with this method.
Poly (3-methylthiophene) (P 3 MeT) films were electrochemically deposited on titanium oxide (TiOX) layers prepared by anodic oxidation of titanium plates, and the chemical and electronic interaction at the P 3 MeT/TiOX p-n heterojunction interfaces were investigated by current-voltage and capacitance-voltage measurements. The junction properties (diode factor, rectifying ratio, barrier height and built-in potential) of the cells were spontaneously improved during their storage in the air, and the extent of the improvement was higher when the TiOX was prepared at a lower one (5 V) than in the case of a higher oxidation bias (20 V). These experimental findings were well explained by using a junction formation model described as the evolution of covalent bond formation at the interface, in which chemically active species on the TiOX surface are linked to the P 3 MeT and increase in number with decreasingthe anodic oxidation potential. This model was experimentally supported by the contact potential difference measurements of the TiOX films.
The angular distributions of desorbing products were examined in 193 nm photo-induced reactions of the O2 + CO adlayers on stepped Pt(112) = [(s) 3(111)×(001)]. At high coverage of O2(a) and CO(a), the product (CO2) desorption collimated closely the (111) terrace normal, where the translational temperature was maximized to 3240 K. On the other hand, at low coverage, the CO2 desorption collimated in highly inclined ways in the plane along the surface troughs, where the translational temperature was enhanced, confirming the hot atom mechanism. These results were compared with those in thermal CO oxidation and the origin of the collimation angle shift in the latter was discussed.
A periodic array of metallic In atomic chains on a Si(111) surface, 4×1-In superstructure, has been investigated by angule-resolved photoemission spectroscopy (ARPES) at room temperature and 100 K, and by scanning tunneling microscopy (STM) at 6 K. We have found from ARPES measurements a one-dimensional metallic band folding back at 100 K and leaving an energy gap at Fermi level. This leads to a metal-to-insulator phase transition and thus supports the charge-density-wave (CDW) model rather than an order-disorder model for the 4×1 (room temperature) to 8×'2' (low temperature) phase transition. We also have found a CDW-lattice locking effect from STM observation at 6 K, that is a lack of one-to-one correspondence between the filled- and empty-state images. The effect is interpreted that the CDW is pinned on the frozen lattice in two different ways. Furthermore, dynamics of a highly movable soliton in the CDW has been observed, which is a characteristic of this kind of quasi-one-dimensional systems.
Corrosion-resistance of titanium metal and tribological characteristics of titanium based materials, such as titanium metal, Ti-6Al-4V alloy and TiN-Ti composite, in n-alcohols of different carbon numbers were investigated. Corrosion-resistance of titanium metal in CH3OH was lower than in other alcohols. Friction and wear of titanium metal, Ti-6Al-4V alloy and TiN-Ti composite decreased in the order. Especially, wear of TiN-Ti composite was much smaller than of the titanium metal and alloy. Friction of titanium-based materials in long chain alcohols was lower than in short chain alcohols, because the viscosity of n-alcohols increases with chain length. Wear of the titanium metal and alloy was affected by the polarity of n-alcohols. The amounts of total wear of those were larger in n-alcohols with small polarity, i.e., long chain alcohols. Wear of the TiN-Ti composite was affected by corrosion-resistance of titanium in n-alcohols, and the wear of TiN-Ti composite was conspicuous in the corrosive alcohols.
The aggregates properties of amphipathic molecules formed at solid-liquid interfaces are influenced by the environmental conditions: solution concentration, temperature, kind of counterion, etc. The effect of the counterions on the adsorbed aggregates was investigated by atomic force microscopy in surface force mode and in surface imaging mode for alkyltrimethylammonium salts (hexadecyltrimethylammonium bromide; CTABr, hexadecyltrimethylammonium chloride; CTACl) at silica-aqueous solution interfaces. The surface force data was analyzed by using DLVO theory. The aggregate of CTABr had smaller surface potential than that of CTACl, and thus, the dissociation degree for CTABr aggregate was lower than that for CTACl. The collapse pressure for CTABr aggregate was smaller than that for CTACl. Although adsorbed aggregates with circular projections were observed for both CTABr and CTACl, the diameter of the circles for CTABr was greater than that for CTACl. Therefore, the aggregates of CTABr on the surface were softer and larger than those of CTACl. It will be considered that the aggregates of CTABr and CTACl were formed with a hemimicelle adsorbed on a flat monolayer and an admicelle on a solid surface, respectively.
Fullerene (C60) immobilized indium-tin-oxide (ITO) electrodes were prepared by a technique of self-assembled monolayers (SAMs) using five compounds of alkyldiamine (NH2(CH2)nNH2; n = 4, 6, 8, 10 and 12). These C60/diamine-SAMs modified ITO (C60/n/ITO; n = 4, 6, 8, 10 and 12) electrodes were examined in terms of properties of electrochemical and photoelectrochemical responses. The C60 surface coverage of C60/n/ITOs estimated was ca. 3×10−10 to 4×10−10 mol cm−2. The stable anodic photocurrent appeared immediately after the irradiation of the C60/n/ITO electrode in 0.1 M Na2SO4 containing 50 mM ascorbic acid (AA) as an electron sacrificer with λ = 400−600 nm, light power of 4.0−6.5 mW cm−2 and electrode potential of −0.15 V to +0.15 V vs. Ag/AgCl (saturated KCl). The photocurrents generated by C60/n/ITOs increased with the number of the methylene unit (n) except for n = 12. These results have shown that increasing the length of the methylene contributes to only immobilization of C60, because of highly ordered structure of diamine-SAMs.
Scanning tunneling microscopy observations reveal that dosed Fe atoms are adsorbed at steps to form monatomic Fe wires on vicinal Au(111) surfaces. We found that decoration of step edges with Fe adatoms has a significant influence on the behavior of the surface state confined between regularly arranged steps. On a stepped surface with Fe monatomic rows, angle-resolved photoemission spectra measured in the direction perpendicular to the steps show parabolic dispersion, in contrast to one-dimensional quantum-well levels observed on a clean surface. Simple analysis using a one-dimensional Kronig-Penney model reveals potential barrier reduction from 20 eVÅ to 4.6 eVÅ, suggesting an attractive nature of the Fe adatoms as scatterers.
Dynamic behavior of cyclohexane adsorbed on Ni(111) under the irradiation of NIR pulses (1064 nm) was studied by time-resolved sum-frequency generation (SFG). Two types of adsorbed cyclohexane were observed on Ni(111), which were attributed to the ordered cyclohexane domains at high coverage and disordered cyclohexane molecules. When the surface was temporally heated up by the irradiation with the NIR pulses, the disordered cyclohexane molecules were thermally excited to form the ordered structure.