On equivalence of L p -norms related to Schrödinger type operators on Riemannian manifolds

In this paper, we study Schrödinger type operator on a Riemannian manifold. Under some assumptions on a potential function, we characterize the domain of the square root of the Schrödinger type operator on L ^p space. In the proof, the defective intertwining properties and the Littlewood-Paley inequalities play important roles.     

Highly charging of nanoparticles through electrospray of nanoparticle suspension

Patterned deposition of nanoparticles is a prerequisite for the application of unique properties of nanoparticles in future nanodevices. Recent development of nanoxerography requires highly charged aerosol nanoparticles to avoid noise deposition due to random Brownian motion. However, it has been known that it is difficult to charge aerosol nanoparticles with more than two elementary charges. The goal of this work is to develop a simple technique for obtaining highly charged monodisperse aerosol nanoparticles by means of electrospray of colloidal suspension. Highly charged aerosol nanoparticles were produced by electrospraying (ES) and drying colloidal suspensions of monodisperse gold nanoparticles. Size and charge distributions of the resultant particles were measured. We demonstrate that this method successfully charges monodisperse nanoparticles very highly, e.g., 122 elementary charges for 25.0 nm, 23.5 for 10.5 nm, and 4.6 for 4.2 nm. The method described here constitutes a convenient, reliable, and continuous tool for preparing highly charged aerosol nanoparticles from suspensions of nanoparticles produced by either wet chemistry or gas-phase methods.     

Thermal analysis graphite intercalation compounds with dichlorides of some d-elements: A.S. Skoropanov,G.S. Petrov,A.A. Vecher,Yu.N. Novikov and M.E. Vol'pin,Thermochim. Acta, 90 (1985) 339-342

Kinetic and thermodynamic aspects of the axial base dissociation of solid Co(salen) (X-py) complexes, X = H (1), 3-Me (2), 4-Me (3), 3,4-Me₂ (4), 3,5-Me₂ (5), 3-NH₂ (6), 3-Cl (7), 3-CN (8), 4-CN (9), have been investigated by means of TG-DSC and isothermal weight-loss measurements. These adducts endothermically dissociate the axial base giving rise to the oxygen-active Co(salen) complex. The axial base dissociation reactions fit the contracting disc equation and the kinetic compensation effect is observed for all the adducts excepting Adducts 4–6. For the remaining adducts the kinetic and thermodynamic stabilities of the Co-(X-py) bond are found to increase linearly with increasing Hammett's substitution constants of X except for Adducts 3 and 9. These results are discussed in terms of the σ and π interactions between cobalt(II) and substituted pyridine. Factors dominating the kinetic bond stability are briefly discussed.     

Pre-concentration of traces of tin by coprecipitation with yttrium hydroxide for electrothermal atomisation atomic absorption spectrometry

Summary Trace amounts of tin were concentrated by coprecipitation and determined by electrothermal atomisation atomic absorption spectrometry. Yttrium hydroxide coprecipitated quantitatively 0.1–3 g of tin from 50–500 ml of sample solution at pH 9.5–11.2. The atomic absorbance of tin increased about twice by using an impregnated graphite tube with yttrium. The impregnated graphite tube, furthermore, improved the reproducibility of the measurement of tin. A linear calibration graph was obtained in the range of 0.004–0.12 g/ml of tin. Twenty-three foreign ions did not interfere seriously. The method was applicable to the determination of tin in zinc metal.     

Selective growth of ag nanowires on Si(111) surfaces by electroless deposition

Electroless deposition of Ag on atomically flat H-terminated Si(111) surfaces in aqueous alkaline solutions containing Ag ions produced two different sizes of Ag nanowires along atomic step edges: (1) a narrow nanowire of 10 nm in width and 0.5 nm in height and (2) a wide nanowire of 35 nm in width and 11 nm in height. The narrow and wide nanowires were formed by immersion in the solutions containing less than 1 ppb and 8 ppm dissolved-oxygen concentrations, respectively. This result indicates that the dissolved oxygen initiates the formation of Ag nucleation sites and that the fabrication method has a possibility of controlling the size of Ag nanowires.     

Optimization of a multi-residue screening method for the determination of 85 pesticides in selected food matrices by stir bar sorptive extraction and thermal desorption GC-MS

A multi-residue method to determine 85 pesticides, including organochlorine pesticides, carbamates, organophosphorus pesticides, and pyrethroids, in vegetables, fruit, and green tea, has been developed. The method is based on stir bar sorptive extraction (SBSE) coupled to thermal desorption (TD) and retention time locked (RTL) GC-MS operating in the scan mode. Samples are extracted with methanol and diluted with water prior to SBSE. Dilution of the methanol extract before SBSE was optimized to obtain high sensitivity and to minimize adsorption onto the glass wall of the extraction vessel as well as to minimize sample matrix effects (particularly for the pesticides with high log K(o,w) values). The optimized method consists of a dual SBSE extraction performed simultaneously on respectively a twofold and a fivefold diluted methanol extract. After extraction, the two stir bars are placed in a single glass thermal desorption liner and are simultaneously desorbed. The method showed good linearity (r2 > 0.9900) and high sensitivity (limit of detection: < 5 microg kg(-1)) for most of the target pesticides. The method was applied to the determination of pesticides at low microg kg(-1) in tomato, cucumber, green soybeans, spinach, grapes, and green tea.     

Preconcentration of palladium(II) from water with thionalide loaded on silica gel

2-Mercapto-N-2-naphthylacetamide (thionalide) on silica gel is used for rapid preconcentration of μg l^?1 levels of palladium(II) from aqueous solution, followed by atomic absorption spectrometric measurement. In batch experiments, palladium was quantitatively retained on the gel from solutions 5 M in acid to pH 8; equilibrium was achieved within 10 s. The chelating capacity of the gel was 7.5 μmol Pd g^?1 at pH < 4. The effect of flow rate on retention was studied. Palladium retained on the column was completely eluted with 20 ml of 0.2 M thiourea in 0.1 M hydrochloric acid. The palladium concentration in sea water is shown to be < 0.3 μg l^?1.     

Preconcentration of silver(I), gold(III) and palladium(II) in sea water with p-dimethylaminobenzylidenerhodanine supported on silica gel

A water-insoluble chelating material, p-dimethylaminobenzylidenerhodanine on silica gel (DMABR—SG) is described for preconcentration of trace amounts of silver(I), gold(III) and palladium(II) from water samples. Radioactive tracers (^110mAg and ¹⁹⁵Au) were used to study the behavior of silver and gold; palladium was monitored spectrophotometrically as its 1-(2-pyridylazo)naphthol complex in chloroform. In batch experiments, silver was quantitatively retained on the DMABR—SG at acidities ranging from 1.7 M to pH 5, and gold from 3 M to pH 5; equilibrium was achieved within 1 min for both elements. From sea water, silver ion was completely retained at pH 1.0–6.5 and gold ion at pH 1.0–3.5. In the case of palladium, shaking for about 20 min was required for quantitative retention at pH 1.0–5.0 for aqueous solution and at pH 1.0–7.0 for sea water. The chelating capacity of the DMABR—SG was 23 μmol Ag, 11 μmol Au and 11 μmol Pd per g. Quantitative recovery of silver and gold on DMABR—SG columns from sea water was achieved at higher flow rates (1–2 l h^-1 and 2–3 l h^-1, respectively) than with other chelating resins, e.g., Chelex 100, palladium required slower flow rate (150 ml h^-1). Silver retained on the DMABR—SG column was completely eluted with 20 ml of 2.5% sodium thiosulfate solution but palladium remained on the column. Silver, gold and palladium were quantitatively eluted with 20 ml of 0.1% thiourea in 0.1 M hydrochloric acid.     

Large four-wave mixing of spatially extended excitonic states in thin GaAs layers

We study the size dependence of the nonlinear response of weakly confined excitons for the size region beyond the long wavelength approximation regime. The observed degenerate-four-wave mixing signal of GaAs thin layers exhibits an anomalous size dependence, where the signal is resonantly enhanced at a particular thickness region. The theoretical analysis elucidates that this enhancement is due to the size-resonant enhancement of the internal field with a spatial structure relevant to the nondipole-type excitonic state. These results establish the formerly proposed new type of size dependence of nonlinear response due to the nonlocality induced double resonance.     

Cardiac glycosides: 5. Stereoselective syntheses of digitoxigenin α-D, β-D, α-L,and β-L-glucosides

As part of a continuing study of cardiac g1ycos1des,^1,2 stereoselective syntheses of the four possible glucosides of digitoxigenin were developed via the thermodynamically produced tetra-O-benzyl-D- and L-glucosyl α-trichloroacetaimidates 2α and 11α, and the kinetically produced β-trichloroacetaimidates 2β and 11β. A 58%:19% isolated yield ratio of α-D and β-D benzyl protected glycosides 6 and 3 could be obtained in 30 minutes reaction at ?10°. Halide ion catalysis with a 2:1 excess of tetra-O-benzyl-α-D-glucopyranosyl bromide for 14 days in methylene chloride at room temperature gave a 39%:11% ratio of 6 and 3, along with 43% of recovered digitoxigenin. Debenzylation of the D-glucosides required milder conditions (20% Pd/C, atmospheric pressure, 45 min-1 hr) than the L-glucosides (40% Pd/C, 2 hr) but yields were typically 80% for both groups.