New ideas in neutrino detection

What is new in the field of neutrino detection? In addition to new projects probing both the low and high ends of the neutrino energy scale, an inexpensive, effective technique is being developed to allow tagging of antineutrinos in water Cherenkov (WC) detectors via the addition to water of a solute with a large neutron cross-section and energetic γ daughters. Gadolinium is an excellent candidate since in recent years it has become very inexpensive, now less than $8 per kilogram in the form of commercially available gadolinium trichloride. This non-toxic, non-reactive substance is highly soluble in water. Neutron capture on gadolinium yields an 8.0 MeV gamma cascade easily seen in detectors like Super-Kamiokande. The uses of GdCl₃ as a possible upgrade for the Super-Kamiokande detector — with a view toward improving its performance as an antineutrino detector for supernova neutrinos and reactor neutrinos — are discussed, as are the ongoing R&;D efforts which aim to make this dream a reality within the next two years.     

Fluorescent Nitric Oxide Photodonors Based on BODIPY and Rhodamine Antennae

Two novel NO photodonors (NOPDs) based on BODIPY and Rhodamine antennae activatable with the highly biocompatible green light are reported. Both NOPDs exhibit considerable fluorescence emission and release NO with remarkable quantum efficiencies. The combination of the photoreleasing and emissive performance for both compounds is superior to those exhibited by other NOPDs based on similar light-harvesting centres, making them very intriguing for image-guided phototherapeutic applications. Preliminary biological data prove their easy visualization in cell environment due to the intense green and orange-red fluorescence and their photodynamic action on cancer cells due to the NO photo-liberated.     

Synthesis and Structural Characterization of the Trimeric Furoxan (= Furazan 2-Oxide) System,a New Potent Vasodilating Moiety

The synthesis, structural characterization, and NO donor properties of a series of terfuroxan (= terfurazan trioxide) derivatives 1a–h and 2a–j are reported (Schemes 1 and 2). Structural assignments were confirmed principally by mass and ¹³C- and ¹H-NMR spectroscopy. The extent and the initial rate of NO release in the presence of thiol cofactor was evaluated for each derivative. Vasodilator effects of all the terfuroxan derivatives were evaluated on endothelium-denuded strips of rat aorta precontracted with noradrenaline. Concentration-response curves were also evaluated in the presence of 10 m?M oxyhemoglobin (HbO₂), a well known NO scavenger. The whole series displays high vasodilating potency; the most active terfuroxans ( 1a, b, g and 2i ) are 5–10 times as potent as glyceryl trinitrate taken as reference (see Table 3). The potency decrease observed in the presence of HbO₂ agrees with the involvement of NO in the vasorelaxing action. The 4,3′:4′,4″ connection (series 1 ; furoxan numbering) gives rise to the most potent compounds. The conformational factors seem to play important roles in the activity. No clear relationship between physico-chemical properties of the substituents and potencies of derivative emerges.     

Unsymmetrically substituted furoxans. Part 11. Methylfuroxancarbaldehydes

The two isomeric 3-methyl-4-furoxancarbaldehydes ( 2a ) and 4-methyl-3-furoxancarbaldehyde ( 2b ) have been prepared. Discussion of their structures, thermal equilibration and kinetic of thermal conversion from the 3-methyl to the 4-methyl isomer are also reported. (Phenylsulfonyl)hydrazones 3a and 3b have been prepared as derivatives in view of their potential antitumoral properties.     

Unsymmetrically substituted furoxans. IIII. Methylnitrofuroxan: Its structure and behavior toward nucleophilie substitution

A series of unsymmetrically substituted furoxans have been prepared from methyinitro-furoxan and a variety of nucleophilic reagents. The nmr study of these compounds and of their parent furazans suggested the structure of 3-methyl derivatives for all the furoxans synthesized: on this ground the 3-methyl structure for methylnitrofuroxan was proposed. On heating some 3-methylfuroxan derivatives, a partial isomerization into the corresponding 4-methyl isomers occurred.     

Structure-Property Relationships in the Basicity and Lipophilicity of Arylalkylamine Oxides

Homologous N,N-dimethyl-phenylalkylamine oxides and N,N-dimethyl-diphenylalkylamine oxides were prepared. Their basicity and lipophilicity (octan-1-ol/H₂O) were compared to those of the parent amines. In contrast to the amines, the basicity of all N,N-dimethyl-arylalkylamine oxides showed very limited pK_a variations (range 4.65 – 5.01) with increasing chain length and number of Ph groups. The N-oxides in their neutral form had a log P^N value lower by 2.77±0.34 (n=9) units than that of the parent amine. The log P^C of the cationic N,N-dimethyl-diphenylalkylamines was lower than that of their neutral form, with a decrement diff(log P^N−C) that increased from 3.25 to 4.21 in the homologous series. Unexpectedly, the decrement diff(log P^N−C) for the N-oxides was much smaller than for the tertiary amines, being 0.23 for the aliphatic N,N-dimethyl-pentylamine oxide, 0.47±0.13 for the phenylalkylamine oxides, and 0.80±0.07 for the diphenylalkylamine oxides. In fact, the protonated N-oxides had log P^C values that were quite comparable to those of the protonated parent amines. Because of the differences in basicity, the difference in distribution coefficients at physiological pH (log D^7.4) between a tertiary arylalkylamine and its N-oxide was 0.82±0.66 (n=9). The pharmacokinetic implication is that N-oxygenation may have a smaller effect on the urinary excretion of tertiary amines than usually assumed.     

有机硅活性中间体的研究 II. 一些含环丙基的有机硅化合物的合成及其结构

用锂有机物的方法合成了四种含有环丙基有机硅化合物,对上述每种化合物中可能存在着的立体异构进行了分离和和构型测定。     

Studies in the chemistry of 1,2,5-oxadiazole (II). Synthesis and properties of furazanodiazepines

This paper describes the synthesis and the properties of some furazanodiazepine derivatives obtained by condensing the appropriate β-diketones with 3,4-diaminofurazan. On the basis of U.V., I.R. and N.M.R. evidence a mono-imino structure is suggested for the compounds obtained. Low temperature N.M.R. spectra suggest a rapid tautomensm for the dimethyl derivative.