Screening of organophosphorus pesticides using liquid chromatography-atmospheric pressure chemical ionization mass spectrometry.

Screening and identification of organophosphorus pesticides in blood from patients suffering from acute agricultural chemical toxicity were established by a liquid chromatography-atmospheric pressure chemical ionization mass spectrometric method. To determine 21 pesticides, it was necessary to monitor both positive and negative ions. This method could easily screen for 21 organophosphorus pesticides in less than 30 min. By comparison with a gas chromatographic-mass spectrometric method, the chemicals indicated a similar extent of specificity and within equivalent detection limits, thus satisfying clinical requirements completely.     

Synthesis and central nervous system stimulant activity of 5,8-methanoquinazolines fused with 1,2,4-triazole,tetrazoleand 1,2,4-triazine

5,8-Methanoquinazolines fused with 1,2,4-triazole 4–5 , tetrazole 6 , and 1,2,4-triazine 8 were prepared starting from 2-hydrazino-5,8-methanoquinazoline 3 . Compound 3 and 6 showed the most potent central nervous system (CNS) stimulant activities.     

A new spectroscopic method using the Fraunhofer diffraction pattern

Conclusions From the results shown above, it may be said that this new spectroscopic method using the Fraunhofer diffraction pattern has the possibility of practical use. This method has the advantages that the multiplex gain is retained and the experimental apparatus is very simple as compared with the conventional grating spectroscopy. The resolution is about 1.25A/2KX and becomes higher with the increase of the number of slits and the maximum value of variable in the diffraction pattern. The other way, the simultaneous equations become more difficult to solve with the increase of resolution and at present the maximum value of N_S is 21. In such a case the adjustment factor A and the figure of condition of matrix are important. Further, large memory of the electronic computer is required, for example, 2.56MB for N=800. The experimental setup is now under construction in order to verify the usefulness of this method in the far infrared region.     

Highly sensitive optical sensor system for blood leakage detection

A highly sensitive method for the detection of blood leakage has been developed, and a practical sensor system for blood concentration measurement has been constructed. The present method is based on the attenuation of laser light by blood cells. The effects of the fluctuations of the incident laser light power are eliminated by normalizing the attenuated light intensity by the incident light intensity. A part of the incident laser light is reflected by a beam splitter mounted at the entrance of the test cell, of which the power is measured to provide base data for normalization. The optical path is extended to enhance sensitivity by using a pair of side mirrors. This multi-reflection method is very effective to increase sensitivity; the maximum sensitivity obtained for blood concentration is about 4 X 10^-6 by volume, which is significantly higher than that of the conventional sensors.     

Sub-nanosecond passively Q-switched Yb:YAG/Cr4+:YAG sandwiched microchip laser

We report on laser-diode pumped low-threshold, and compact passively Q-switched Yb:YAG microchip lasers, with Cr⁴⁺:YAG crystals as the saturable absorbers. The laser threshold at the fundamental wavelength of 1.03 μm is as low as 0.25 W, and the slope efficiency is as high as 36.8%, and the optical-to-optical efficiency is as high as 27% for the 95% initial transmission of the Cr⁴⁺:YAG crystal. A pulse width of 1.35 ns and peak power of over 8.2 kW was obtained. Using a 5 mm thick KTP crystal as the second-harmonic generation medium, 514.7 nm green light of 155 mW power was generated. The pulse duration of 480 ps was generated at 1.03 μm by using 85% of the initial transmission of the Cr⁴⁺:YAG saturable absorber. Stable single-longitudinal-mode oscillation and wide-separated multi-longitudinal-mode oscillation due to the etalon effect of the Cr⁴⁺:YAG thin plate was achieved at different pump power levels. PACS 42.55.Sa; 42.55.Xi; 42.60.Gd     

How is it possible to obtain buried interface information through very thick films using a hard-X-ray PEEM?

We analyze the excitation of secondary electrons by hard-X-rays in subsurface layers. By studying core-excited photoelectron lines and their plasmon satellites in photoemission spectra, we show how electrons excited by hard-X-rays can carry information from deep regions deep within the sample to the surface. It is believed that the decay of high-energy photoelectrons via plasmon-loss is strongly related to the production of secondary electrons. For high-energy electrons, however, the momentum transfer to plasmons is small compared to the electron’s initial momentum, so the lateral position on the surface from which the secondary electrons are emitted is close to that of the atom initially excited by the hard-X-rays. This explains why the spatial resolution of hard-X-ray photoelectron emission microscope (HX-PEEM) images is good even if the buried interface is covered by a film with a thickness many times the inelastic mean free path of the primary electrons. This argument explains well recent HX-PEEM results.     

Molecular assemblies of bis- and tris-adenine derivatives

Molecular assemblies of bis- and tris-adenine derivatives were studied by means of NMR, IR, and DSC. Mixtures of the adenine derivatives and 1-hexadecylthymine showed multiple phase transitions in the temperature range of the solid phase. A difference of the NMR, IR, and DSC data between bis-adenine and tris-adenine derivatives may be attributable to a formation of intramolecular hydrogen bonds.     

Electrochemical enzyme immunoassay using immobilized antibody on gold film with monitoring of surface plasmon resonance signal

Sandwich immunoassay was conducted on a thin gold film set in a surface plasmon resonance (SPR) cell. Monochronal antibody (anti-IgG) was immobilized onto the gold film via 4,4′-dithiodibutyric acid (DDA) and avidin-biotin bonding. Next, IgG sample and alkaline phosphatase-conjugated anti-IgG (ALP anti-IgG) were introduced into the cell successively. Finally, p-aminophenyl phosphate (PAPP) was injected as an enzyme substrate, and the produced p-aminophenol (PAP) was electrochemically measured. Flow did not need to be stopped for incubation for the enzyme reaction, because of the thinness of the cell. In these processes, all the antigen-antibody reactions took place on the gold film. Therefore, the immobilization was performed quickly, and each process could be confirmed by SPR signal. This system had the advantage that the middle of the complicated process could be monitored. For example, the amount of antibody immobilized, which affected on the final electrochemical signal, could be confirmed in the course of immobilization. It was also convenient to investigate process conditions, such as removal of used antigens and labeled antibodies. Good correlation was obtained between the electrochemical current and the SPR signals due to the adsorption of IgG and ALP anti-IgG, and the sensitivity of the electrochemical measurement was much higher than the SPR’s.     

Studies on heat transfer and flow characteristics in subcooled flow boiling—Part 2. Flow characteristics

Distributions of fluid temperature and its fluctuation are measured across a R-113 subcooled boiling flow channel with heat fluxes up to the CHF. A microthermocouple probe associated with an electric compensation circuit for the time constant is used for this purpose. Applying statistical treatments to the recorded temperature fluctuation, the heat transfer process in the flow and the characteristics of the bubbles flowing close to the heated surface are investigated. For high heat fluxes nearby the CHF, some bubbles adjacent to the heated surface show a clear trend to coalesce to large volume bubbles with relatively long passing periods, suggesting a mechanism of departure from nucleate boiling by periodical wall temperature rise due to momentary liquid film dryout underneath the large bubbles.     

Preparation and characterization of thin films of monomeric and polymeric octacyanophthalocyanines

Thin films were prepared on substrates, cleavage surface of KCl single crystal, and metallic copper, by reaction of 1,2,4,5-tetracyanobenzene with the substrate at various temperatures. The films were characterized by elemental analysis, IR, and UV/VIS spectroscopies. The films were observed by scanning electron microscopy. The films produced on copper at temperatures between 300 and 400°C consisted of copper octacyanophthalocyanine and its polymer with ladder structure. The ratio of polymer to monomer increased with elevating the reaction temperature. The films were composed of ribbon-like crystals. The film produced on copper above 450°C was composed of an amorphous and continuous layer of polymeric copper phthalocyanine. The film produced on KCl at temperatures between 250 and 350°C consisted of potassium octacyanophthalocyanine and its polymer with ladder structure. The film produced on KCl above 450°C was polymeric potassium phthalocyanine. Those films contained more metal content than that required stoichiometrical.