Results from Super-Kamiokande and K2K

Results from Super-Kamiokande-I’s entire 1496 live days of solar neutrino data are presented, including the absolute flux, energy spectrum, zenith angle (day/night) and seasonal variation. The possibility of MSW and vacuum oscillations is discussed in light of these results. Results from the first 1289 days of Super-K-I’s atmospheric neutrino analysis are also presented, including the evidence for ν_μ →ν _τ oscillations, against ν_μ → ν_sterile oscillations, and the current limits on proton decay. Finally, results based on 56 × 10¹⁹ protons on target are given for the K2K long-baseline neutrino oscillation experiment.     

Spectrophotometric determination of Pd(II) using 1,3 bis (2′-pyridyl)-1,2-diaza-prop-2-ene

Summary The reaction of 1,3 bis (2-pyridyl)-l,2-diaza-prop-2-ene(PAPHY) with Pd(II) to produce a coloured complex extractable into organic solvents has been used to measure microquantities of Pd(II) in acid solutions. The method is sensitive for Pd(II) concentrations of 5g and above. Method used involves the reaction of Pd(II) with the ligand PAPHY in an acid medium followed by extraction of the Pd-PAPHY complex into benzene. The red complex has 2 absorption maxima in the visible spectrum, one at 573 nm and the other at 545 nm. The interference by other divalent ions has been studied and found to be negligible.

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Zusammenfassung Die Reaktion von 1,3-Bis-(2-pyridyl)-1,2-diaza-propen-2 (PAPHY) mit Pd(II) führt zur Bildung einer mit organischen Lösungsmitteln extrahierbaren, gefärbten Komplexverbindung und wurde zur Bestimmung von Mikromengen Pd(II) in sauren Lösungen verwendet. Die Methode eignet sich für 5g Pd(II) und mehr. Der rote Pd-PAPHY-Komplex wird aus saurem Milieu mit Benzol extrahiert und hat 2 Absorptionsmaxima im sichtbaren Bereich, u. zw. bei 573 nm und bei 545 nm. Störungen durch zweiwertige Fremdionen wurden geprüft und sind vernachlässigbar.

     

Pseudilins: Halogenated,Allosteric Inhibitors of the Non‐Mevalonate Pathway Enzyme IspD

The enzymes of the non‐mevalonate pathway for isoprenoid biosynthesis have been identified as attractive targets with novel modes of action for the development of herbicides for crop protection and agents against infectious diseases. This pathway is present in many pathogenic organisms and plants, but absent in mammals. By using high‐throughput screening, we identified highly halogenated marine natural products, the pseudilins, to be inhibitors of the third enzyme, IspD, in the pathway. Their activity against the IspD enzymes from Arabidopsis thaliana and Plasmodium vivax was determined in photometric and NMR‐based assays. Cocrystal structures revealed that pseudilins bind to an allosteric pocket by using both divalent metal ion coordination and halogen bonding. The allosteric mode of action for preventing cosubstrate (CTP) binding at the active site was elucidated. Pseudilins show herbicidal activity in plant assays and antiplasmodial activity in cell‐based assays.     

Comparison of iodinated [Nle15]- and [Met15]-gastrin17 prepared by reversed-phase HPLC

125I-[Nle15]-gastrin17 prepared by the iodogen method can be separated by reversed-phase high performance liquid chromatography into two peaks, both of which elute after [Nle15]-gastrin17. Direct determination of the specific activities of the two derivatives by microbore reversed-phase HPLC indicated that they were the mono- and di-iodinated species. In contrast the two peaks obtained with [Met15]-gastrin17 iodinated under the same conditions eluted earlier, relative to the appropriate gastrin17 standard, than the [Nle15]-gastrin derivatives. Treatment of either peak with 0.75 M dithiothreitol at 56 degrees C or 95 degrees C resulted in progressive conversion to compounds migrating in relative positions similar to the 125I-[Nle15]-gastrin17 derivatives. Direct determination of the specific activity of the earlier eluting [Met15]-gastrin17 derivative before reduction indicated that it was the mono-iodinated species. It thus appears likely that iodination of [Met15]-gastrin17 by the iodogen method results predominantly in the formation of mono- and di-125I-[Met sulphoxide15]-gastrin17. To avoid problems arising from oxidation of the methionine residue of gastrin during iodination, the use of 125I-[Nle15]-gastrin17 in binding studies is therefore recommended.     

A colorimetric method using chlorpromazine-5-oxide for the assay of NAD- and NADP-oxidoreductases

Summary Chlorpromazine-5-oxide (CPZ · O) in the presence of H₂SO₄ and Cl- forms a free radical with absorption maximum at 535 nm. Molar absorptivity at 535 nm of the free radical was found to be (1.12±0.02) 10⁴. The red CPZ · O free radical in H₂SO₄, when diluted with 45% H₃PO₄, is readily reduced by reducing agents, like Fe²⁺, S₂O₃ ^2-, NADH, NADPH and ascorbic acid, to chlor-promazine. Onemole NADH/NADPH reduces 2moles of the CPZ·O free radical. Details of assay methods for lactate, hydroxybutyrate and malate dehydrogenases are given. The method can also be used in the measurement of enzymes like phosphohexose isomerase and pyruvate kinase by coupled enzyme methods and for assay of isocitrate, glucose-6-phosphate and 6-phosphogluconate dehydrogenases. Results of comparison studies between the colorimetric method and rate analyser methods with lactate, malate, isocitrate and glucose-6-phosphate dehydrogenases are given. The colonmetric results correlated well with Rate Analyser results.

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Zusammenfassung Chlorpromazin-5-oxid (CPZ. O) bildet in Gegenwart von Schwefelsäure und Chloridionen ein freies Radikal mit einem Absorptionsmaximum bei 535 nm, dessen molare Extinktion bei dieser Wellenlänge (1,12±0,02)·10⁴ beträgt. Das rot gefärbte freie Radikal CPZ.O läßt sich in Schwefelsäure nach Verdünnen mit 45% Phosphorsäure leicht mit Fe(II), S₂O₃ ^2-, NADH, NADPH und Ascorbinsäure zu Chlorpromazin reduzieren. Ein Mikromol NADH/NADPH reduziert 2 Mikromole CPZ.O.Details über die Bestimmung von Laktat-, Hydroxybutyrat- und Malatdehydrogenasen wurden mitgeteilt. Die Methode kann auch für die Bestimmung von Enzymen wie Phosphohexose-Isomerase und Pyruvatkinase durch gekoppelte Enzymmethoden und für die Bestimmung der Isozitrat-, Glucose-6-phosphat- und 6-Phosphogluconat-Dehydrogenasen verwendet werden. Resultate des Vergleichs zwischen der kolorimetrischen Methode und Schnellmethoden zur Bestimmung von Laktat-, Malat-, Isozitrat- und Glucose-6-phosphat-Dehydrogenase zeigen gute Übereinstimmung.

     

Inhibitors of the kinase IspE: structure-activity relationships and co-crystal structure analysis

Enzymes of the non-mevalonate pathway for isoprenoid biosynthesis are therapeutic targets for the treatment of important infectious diseases. Whereas this pathway is absent in humans, it is used by plants, many eubacteria and apicomplexan protozoa, including major human pathogens such as Plasmodium falciparum and Mycobacterium tuberculosis. Herein, we report on the design, preparation and biological evaluation of a new series of ligands for IspE protein, a kinase from this pathway. These inhibitors were developed for the inhibition of IspE from Escherichia coli, using structure-based design approaches. Structure-activity relationships (SARs) and a co-crystal structure of Aquifex aeolicus IspE bound to a representative inhibitor validate the proposed binding mode. The crystal structure shows that the ligand binds in the substrate-rather than the adenosine 5'-triphosphate (ATP)-binding pocket. As predicted, a cyclopropyl substituent occupies a small cavity not used by the substrate. The optimal volume occupancy of this cavity is explored in detail. In the co-crystal structure, a diphosphate anion binds to the Gly-rich loop, which normally accepts the triphosphate moiety of ATP. This structure provides useful insights for future structure-based developments of inhibitors for the parasite enzymes.     

A novel application of range-gated underwater laser imaging system (ULIS) in near-target turbid medium

Range-gated imaging system improves signal-to-backscattering noise ratio (SBR) by rejecting backscattered light from the target irradiance. This is achieved by synchronizing the arrival of pulsed target irradiance with the gating of an intensified camera. Witherspoon and Holloway (Ocean Optics X 1302 (1990) 414–420) indicated that the image quality of range-gated imaging system might be further improved by a delay in the camera gating towards the tail of reflected image temporal profile (RITP). This phenomena has, however, not been further elaborated. This paper extends on Witherspoon's observation. The MCRITP (Monte Carlo for RITP) algorithm is validated with theoretical and experimental results for medium attenuation coefficients of 0.26–5.90/m. By temporal convolution of the simulated results with outgoing Gaussian light pulse, Tail RITP region shows more reduction in the unwanted backscatter effects than the target intensity. This can be observed as an improvement in image contrast and a modified fidelity index (MF).     

Three-dimensional woodpile photonic crystal templates for the infrared spectral range

High-quality templates of three-dimensional woodpile photonic crystals are fabricated in photoresist SU-8 by use of femtosecond laser lithography. The samples have smooth surfaces, are mechanically stable, and are resistant to degradation under environmental and chemical influences. Fundamental and higher-order photonic stopgaps are identified in the wavelength range 2.0-8.0 microm. These templates can be used for subsequent infiltration by optically active or high-refractive-index materials.