The Enhancement of Efficiency of High-order Harmonic in Intense Laser Field Based on Asymptotic Boundary Conditions and Symplectic Algorithm

Asymptotic boundary condition (ABC) of laser-atom interaction presented recently is applied to transform the initial value problem of the time-dependent Schrödinger equation (TDSE) in infinite space into the initial and boundary value problem in the finite space, and then the TDSE is discretized into linear canonical equations by substituting the symmetry difference quotient for the 2-order partial derivative. The canonical equation is solved by symplectic algorithm. The ground state and the equal weight coherent superposition of the ground state and the first excited state have been taken as the initial conditions, respectively, while we calculate the population of bound states, the evolution of average distance and the high-order harmonic generation (HHG). The conversion efficiency of HHG can be enhanced by initial coherent superposition state and moderate laser intensities     

Effect of hydrocolloids on starch thermal transitions,as measured by DSC

Differential scanning calorimetry (DSC) was used to analyze the influence of different hydrocolloids (xanthan, guar, and locust bean gums, carboxymethylcellulose and sodium alginate) on the gelatinization of corn starch in systems with starch concentration ranging between 0.1 and 0.7 g starch/g mixture. The reduction of available water produced a shift in gelatinization temperature, especially of the conclusion temperature. The effect was more marked for ionic hydrocolloids. The influence of hydrocolloids on glass transition temperature (T _g) of gelatinized starch suspensions and on the glass transition temperature of the maximally freeze-concentrated solute/unfrozen water matrix (T _g) was also studied.T _g onset values ranged between –4.5 and –5.5C for corn starch pastes with and without hydrocolloids. Those hydrocolloids that increased the viscosity of the unfrozen matrix inhibited additional ice formation during thawing (devitrification).Starch concentration and final heating temperature were found to be relevant factors affecting the kinetics of amylopectin retrogradation during frozen storage at –4C. Xanthan gum failed to prevent amylopectin retrogradation; this observation could be attributed to the fact that gums act outside the starch granule, while amylopectin retrogradation takes place within the granule.     

R?ntgenspektrometrische Bestimmung von Eisen-55 in Luftstaub- und Niederschlagsproben

Zusammenfassung Eisen-55 wurde in Neuherberg bei München seit März 1970 in monatlich gesammelten Luftstaubproben und seit Januar 1971 in Monatsniederschlagsproben bestimmt. Nach dem Veraschen der Proben wurde Eisen durch Extraktion' mit Di-iso-propyläther abgetrennt. Zur weiteren Entfernung störender Radionuklide des Fallouts wurde eine Ionenaustauschertrennung angeschlossen. Nach der elektrolytischen Abscheidung des Eisens auf Kupferplättchen wurden die Röntgenspektren mit einem Proportionalzähler sowie einem Si(Li)-Detektor aufgenommen.Die mittlere spezifische Luftaktivität betrug in Neuherberg 1,0 fCi/m³ im Jahr 1970 (ab März), 1,2 fCi/m³ im Jahr 1971 und 0,36 fCi/m³ im Jahr 1972. Die dem Boden durch den Niederschlag zugeführte Aktivität wurde zu 697 pCi/m² · Jahr für 1971 und 178 pCi/m² · Jahr für 1972 bestimmt.Vortrag anläßlich der Tagung Spurenanalyse, 2. bis 5. April 1973 in Erlangen.     

Spectrographic estimation of Ga, In and Tl in semiconductor grade selenium

Summary An emission spectrographic method for the estimation of Ga, In and Tl in semiconductor grade selenium at less than a ppm concentration has been developed. The impurities were separated from 1 g of selenium by volatilizing it from its solution in nitric acid and sulphuric acid. The residue containing the impurities was dissolved in small amounts of 6 M HCl and was loaded along with the washings on 10 mg mixture containing graphite (90%) and sodium chloride carrier (10%) in the electrode crater. The spectra were excited in a d.c. arc carrying 13 A current. The detection limits lie in the range of 0.0025–0.005 ppm. The precision of the method ranges from 7–12% for these elements. The recoveries of impurities from selenium were confirmed using radioactive tracers.

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Spektrographische Bestimmung von Gallium, Indium und Thallium in Halbleiterselen

Zusammenfassung Eine 1 g-Probe wird in Salpeter- und Schwefelsäure gelöst und die Verunreinigungen durch Verflüchtigung des Selens isoliert. Sie werden in 6 M HCl gelöst und zusammen mit einem Graphit/NaCl-Gemisch (91) in die Elektrode eingebracht. Zur Anregung dient ein Gleichstrombogen (13 A). Die Nachweisgrenzen liegen im Bereich von 0.0025–0.005 ppm, der Variationskoeffizient bei 7–12%. Die Wiedergewinnung der Verunreinigungen wurde mit Hilfe von Radioindicatoren geprüft.

     

Visual observation of contact-induced intercrystalline migration of aromatic species adsorbed in zeolites by fluorescence microscopy.

Intercrystalline migration and a migration-assisted chemical reaction of adsorbed aromatic species between zeolite particles in physical contact were visualized by fluorescence microscopy coupled with a particle manipulation technique. The luminescence color characteristics of particular zeolite particles originating from the specific photochemistry of adsorbed species was exploited to follow the migration of the molecules. Two examples are shown that are relevant to the visualization of the time-dependent migration process: A one guest-two sets of zeolite crystals system: chrysene (Chry)-loaded zeolite Na+ -X (the sodium form of zeolite X) crystals were placed in contact with unloaded Tl+ -X (thallium-exchanged X) crystals and allowed to stand at room temperature. Initially, the blue fluorescence of Chry was detected only from the Na+ -X particles, but later, the development of green phosphorescence emission was discernible from the Tl+ -X which suggests that Chry migrated from the Na+ -X to the Tl+ -X crystals. A two guest-species systems: Electron-donating Chry-loaded Na+ -X crystals were placed in contact with electron-accepting 1,2,4,5-tetracyanobenzene (TCNB)-loaded Na+ -X or Na+ -Y crystals. With time, the former system (Chry/Na+ -X and TCNB/Na+ -X) gave rise to the emission of Chry-TCNB charge-transfer complexes resulting mainly from the migration of Chry while the latter system (Chry/Na+ -X and TCNB/Na+ -Y) afforded the same emission resulting largely from the migration of TCNB. The present investigation reveals that there is a certain direction for guest migration depending on the zeolite host and the nature of host-guest or guest-guest interaction.     

HPLC Analysis of Cotinine in Urine After SPE with a Cholesterol-Modified Adsorbent

A one-step solid-phase extraction procedure, based on a new silica gel adsorbent modified with cholesterol groups, has been investigated for measurement of cotinine in urine. Cotinine is the main metabolite of nicotine in the human body and is analyzed as a biomarker for assessment of direct or passive exposure to tobacco smoke. New cholesterol-modified adsorbents have been obtained by chemical modification of silica gel of different porosity with cholesterol ligands. Although recovery by this extraction procedure were optimum over a relatively broad range of sample pH (3.1–8.0), analytical conditions such as sample loading, washing and elution conditions, concentration of cotinine to be extracted, and the type of adsorbent used for extraction were found to affect the efficiency of the procedure and had to be controlled for optimum recovery. When these conditions were controlled, recovery of cotinine from spiked human urine was reproducible and depended on compound ionization. Quantitative analysis of cotinine was performed by reversed-phase high-performance liquid chromatography with UV detection. Presented at: Conference of the Hyphenation of Liquid Chromatography–Nuclear Magnetic Resonance Spectroscopy, Liquid Chromatography–Mass Spectrometry and Related Topics, Tuebingen, Germany, March 25–29, 2006.     

A comparison of phototautomerism in different sites of free-base porphin (H2P) in n-alkane crystals

Selective laser-induced phototautomerism of free-base porphin in different n-alkanes (n-hexane, n-heptane, n-octane, nnonane, n-decane, n-undecane and n-dodecane) has been used to identify tautomer splittings in a number of sites in polycrystalline samples at 2 K. Pairs or lines arising from the two molecular orientations in each site can be reversibly transformed into each other. In the odd n-alkanes the occupation of different sites was not dependent on the rate at which the samples were frozen, but in the even n-alkanes metastable sites were only occupied following rapid quenching.     

In-gel deglycosylation of sodiumdodecyl sulfate polyacrylamide gel electrophoresis-separated glycoproteins for carbohydrate estimation by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Mass determination by mass spectrometric methods (electrospray ionization mass spectrometry (ESI-MS), matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS)) of sodiumdodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE)-separated proteins is a well known procedure and reliable protocols are available. In our efforts to use the established methods to determine the molecular mass of the disulfide bridged, heterodimeric glycoprotein GP3 and to determine the carbohydrate content of each protein subunit we developed an in-gel chemical deglycosylation method. For this purpose we established experimental conditions that allow maximum extraction of the high molecular mass protein subunits and developed a routine method to apply the HF-pyridine deglycosylation protocol to proteins isolated from polyacrylamide gel pieces. The novel protocol and extraction procedure described can be used to analyze O-glycosylated proteins up to 150 kDa after SDS-PAGE separation.     

NMR investigation on the conformational properties of N-[2-pyridyl-N-oxide]-amino derivatives

The proton NMR spectra of N-[2-pyridyl-N-oxide]-derivatives of primary and secondary ethylamines, containing a substituent R on the C atom bearing the amino function, have been completely analysed in terms of the fundamental NMR parameters. The preferred conformations of the compounds investigated were established by the indications from NOE experiments as well as: (1) the long range coupling across the five bond between the aminic hydrogen and the proton in 4-position of the pyridine-N-oxide ring (⁵J_m^H,NH ～ 0·5 c/s), (2) the value of the vicinal coupling constant in the fragment CHNH (³J_NHCH ～ 7–9 c/s), (3) the large deshielding (Δτ ～ 1–1·5 ppm) observed for the resonance position of the proton on the asymmetric C atom in secondary amine derivatives with respect to the corresponding primary ones, and (4) the diamagnetic shielding produced on protons in position 3 and 4 of the pyridine-N-oxide ring by different aromatic groups introduced in the R substituent.The NMR data confirmed the preferred rotamers previously suggested on the basis of ORD and CD measurements.     

LC-ESI-MS Determination of Bilobalide and Ginkgolides in Canine Plasma

A sensitive and selective method using liquid chromatography with electrospray ionization mass spectrometric detection was developed for the quantification of bilobalide and ginkgolides in canine plasma. The analytes were extracted with diethyl ether-dichloromethane-isopropanol (6:3:1, v/v) after spiking the samples with daidzein (internal standard). The lower limit of quantification (LLOQ) of the method was 2.5 μg L⁻¹ for ginkgolide B and 10.0 μg L⁻¹ for bilabolide, ginkgolide A and ginkgolide C. The accuracy of the method was within 15% of the actual values over a wide range of plasma concentrations. The intra-day and inter-day precision was better than 15% (R.S.D.). Finally, the LC-ESI-MS method was successfully applied to study the pharmacokinetics of ginkgolides and bilabolide after administration of Ginkgo biloba extracts to dogs.