Preparation of an optimum mobile phase for the simultaneous determination of neurochemicals in mouse brain tissues by high-performance liquid chromatography with electrochemical detection.

A systematic method is described for the optimization of a mobile phase for the simultaneous determination of 24 neurochemicals consisting of catecholamine, serotonin, their precursors and metabolites and related materials. This mobile phase contained sodium acetate (0.04 M), citric acid (0.01 M), sodium chloride (0.0126 M), sodium octyl sulfate (91 mg/l), tetrasodium EDTA (50 mg/l) and 10% (v/v) methanol. When this optimum mobile phase was applied to the analysis of brain tissues of the Swiss male mouse, twelve neurochemicals were quantified in the free state: tyrosine, L-beta-3,4-dihydroxyphenylanine, dopamine, 3,4-dihydroxyphenylacetic acid, 4-hydroxy-3-methoxyphenylacetic acid, norepinephrine, 3-methoxy-4-hydroxyphenylglycol, DL-3,4-dihydroxymandelic acid, DL-4-hydroxy-3-methoxymandelic acid, serotonin, L-tryptophan, 5-hydroxyindole-3-acetic acid and DL-synephrine and normetanephrine, appearing as a fused peak. This fused peak was present on the chromatogram tracings of all the mouse brain tissues. The separable neurochemicals not found by this procedure in the Swiss male mouse tissues were DL-3,4-dihydroxyphenylglycol,5-hydroxytryptophan, epinephrine, DL-octopamine, metanephrine, deoxyepinephrine, homovanillyl alcohol, N-acetylserotonin, tyramine and 3-methyltyramine.     

Novel Anti‐Inflammatory Constituents of Artocarpus rigida

A novel phenolic compound containing an oxepine ring, artocarpol I ( 1 ), and a new biphenylpropanoid, artocarpol J ( 2 ), were isolated from the root bark of Artocarpus rigida. The structures, including relative configurations, were elucidated by spectroscopic data. Compound 1 and artocarpol J peracetate ( 3 ) strongly inhibited in a concentration‐dependent manner the formyl‐Met‐Leu‐Phe (fMLP)/cytochalasin B (CB)‐stimulated superoxide anion formation in neutrophils with IC₅₀ values of 17.1±0.40 and 20.5±2.60 μM , respectively. Biogenetically, all the novel phenolic compounds isolated from this plant seem to be derived from stilbene.     

PAHs Formation in the Depositions in a Methyl tert-Butyl Ether/Ar,a Methyl tert-Butyl Ether/O2/Ar and a Methyl tert-Butyl Ether/H2/Ar RF Plasma Environment

Contents and distributions of polycyclic aromatic hydrocarbons (PAHs) in the depositions were investigated and discussed in a MTBE/Ar, a MTBE/O₂/Ar and a MTBE/H₂/Ar plasma systems. A radio-frequency (RF) plasma system was used to produce the depositions under the designed operational condition. The identification and quantification of PAHs was accomplished by using a GC with a mass selectivity detector (GC/MS). Results indicated that when the input power controlled at high wattage (70 W) in the three systems, the contents of total-PAH in the MTBE/Ar system are higher than those of total-PAH in other system with adding O₂ or H₂. The comparison of three systems indicated the formation and accumulation of PAHs in the MTBE/Ar system is easier than other systems. At high input power wattage, when the MTBE/Ar mixture added O₂ or H₂, the domain pattern was shifted from both 3- and 4-ring PAH to 2-ring PAH. As far as the total-PAH content is concerned, the MTBE/Ar system at 70 W was found to have the highest mean total-PAH content (1540 g/g), while the MTBE/O₂/Ar system at 20 W had the lowest mean total-PAH content (44.4 g/g).     

Error analysis of splitting algorithms for polynomials

An error analysis is given for the general splitting algorithm, proposed by Shaw and Traub, for evaluating a polynomial and some of its derivatives. The results show that the usual synthetic division is least likely to be affected by round-off errors if only single-precision arithmetic is available for all the algorithms. However, the new splitting algorithms are better than the synthetic division if extended-precision arithmetic is available for the evaluation of powers ofx.This work supported in part by the United States Air Force under grant AFOSR 76-3020     

Benzo[1,2-b:4,5-b']bis[b]benzothiophene as solution processible organic semiconductor for field-effect transistors

Coplanar benzo[1,2-b:4,5-b']bis[b]benzothiophenes (, ) for the application in organic field-effect transistors were synthesized by a simple two-step procedure involving triflic acid induced ring-closure reaction; such solution processed devices show a hole mobility of up to 0.01 cm(2) V(-1) s(-1).     

Cross-point analysis for a multimode fiber sensor based on surface plasmon resonance

A novel analysis based on surface plasmon resonance (SPR) with a side-polished multimode fiber and a white-light (halogen light) source is presented. The sensing system is a multimode optical fiber in which half of the core has been polished away and a 40 nm gold layer is deposited on to the polished surface by dc sputter. The SPR dip in the optical spectrum is investigated with an optical spectrum analyzer (OSA). In our SPR fiber sensor, the use of liquids with different refractive indices leads to a shift in the spectral dip in the SPR curve. The cross point (CP) of the two SPR spectra obtained from the refractive-index liquid and the deionized water measurements was observed with the OSA. The CP is shifted sensitively in wavelength from 630 to 1300 nm relative to a change in the refractive index of the liquid from 1.34 to 1.46. High sensitivities of 1.9 x 10(-6) refractive-index units (RIUs) in the range of the refractive index of the liquid from 1.40 to 1.44 of 5.7 x 10(-7) RIUs above the value of 1.44 are proposed and demonstrated in our novel SPR analysis.     

Spallation processes and nuclear interaction products of cosmic rays

Most cosmic-ray nuclei heavier than helium have suffered nuclear collisions in the interstellar gas, with transformation of nuclear composition. The isotopic and elemental composition at the sources has to be inferred from the observed composition near the Earth. The source composition permits tests of current ideas on sites of origin, nucleosynthesis in stars, evolution of stars, the mixing and composition of the interstellar medium and injection processes prior to acceleration. The effects of nuclear spallation, production of radioactive nuclides and the time dependence of their decay provide valuable information on the acceleration and propagation of cosmic rays, their nuclear transformations, and their confinement time in the Galaxy. The formation of spallation products that only decay by electron capture and are relatively long-lived permits an investigation of the nature and density fluctuations (like clouds) of the interstellar medium. Since nuclear collisions yield positrons, antiprotons, gamma rays and neutrinos, we shall discuss these topics briefly.     

A phage display system with unnatural amino acids

We report a general method to display peptide-containing unnatural amino acids on filamentous M13 phage. Five distinct unnatural amino acids were site-specifically incorporated at the N-terminal of the M13 phage minor coat protein pIII. Phages that contain p-azidophenylalanine can undergo a highly specific azide-alkyne [3 + 2] cycloaddition reaction with an alkyne-derivatized fluorophore. The generalization of phage display to include unnatural amino acids should significantly increase the scope of phage display technology.     

Seed‐Mediated Growth of Silver Nanocubes in Aqueous Solution with Tunable Size and Their Conversion to Au Nanocages with Efficient Photothermal Property

Two seed‐mediated approaches for the growth of silver nanocubes in aqueous solution have been developed. Addition of a silver‐seed solution to a mixture of cetyltrimethylammonium chloride (CTAC), silver trifluoroacetate, and ascorbic acid and heating the solution at 60 °C for 1.5 h produces uniform Ag nanocubes with tunable sizes from 23 to 60 nm by simply adjusting the volume of silver‐seed solution introduced. Alternatively, the silver‐seed solution can be injected into a mixture of cetyltrimethylammonium bromide (CTAB), silver nitrate, copper sulfate, and ascorbic acid and heated to 80 °C for 2 h to generate 46 nm silver nanocubes. Plate‐like Ag nanocrystals exposing {111} surfaces can be synthesized by reducing Ag(NH₃)₂⁺ with ascorbic acid in a CTAC solution. Relatively large Ag nanocubes were converted to cuboctahedral Au/Ag and Au nanocages and nanoframes with empty {111} faces through a galvanic replacement reaction. The nanocages showed a progressive plasmonic band red‐shift with increasing Au content. The nanocages exhibited high and stable photothermal efficiency with solution temperatures quickly reaching beyond 100 °C when irradiated with an 808 nm laser for large heat and water vapor generation.