Stochastic integrators indexed by a multi-dimensional parameter

Summary Multi-parameter stochastic integrators are described and classified according to directions of integrability. Sets of directions are distinguished precisely by the combinatorial dimension of corresponding fractional Cartesian products. The main theorem establishes existence of stochastic processes which are integrators in prescribed directions but not others.     

A Diepoxide Belonging to the Rare C1 Point Group

2,6- and 2,7-Dimethylanthracenes were reduced seriatim with lithium in liquid ammonia and lithium in methylamine to their 1,4,5,8,9,10-hexahydro derivatives. Two-fold epoxidation of these tetraenes provided the cis and trans diepoxides resulting from electrophilic attack at the inner double bonds. Trans diepoxide 1 has the very unusual characteristic of lacking a σ plane of symmetry but possessing an inversion center. As a consequence, the ¹H NMR spectrum of C₁-symmetric 1 is simplified relative to those of its isomers 5, 9, and 10.     

High-performance liquid chromatography and thin-layer chromatography assays for Devil's Club (Oplopanax horridus)

Devil's root, Oplopanax horridus, is a widely used folk medicine in Alaska and British Columbia. The inner bark of the root and stem has been used to treat colds, cough, fever, and diabetes. The present study involves the development of high-pressure liquid chromatography (HPLC) and thin-layer chromatography (TLC) methods to detect the presence of trans-nerolidol and sterols in the root bark. The HPLC and TLC analytical methods presented are suitable for the characterization and identification of Oplopanax horridus.     

Automated separation and measurement of radioxenon for the Comprehensive Test Ban Treaty

A fully automatic radioxenon sampler/analyzer (ARSA) has been developed and demonstrated for the collection and quantitative measurement of the four xenon radionuclides,^131mXe(11.9 d),^133mXe(2.2 d),¹³³Xe(5.2 d), and¹³⁵Xe(9.1 hr), in the atmosphere. These radionuclides are important signatures in monitoring for compliance to a Comprehensive Test Ban Treaty (CTBT). Activity ratios of these radionuclides permit source attribution. Xenon, continuously and automatically separated from the atmosphere, is automatically analyzed by electron-photon coincidence spectrometry providing a lower limit of detection of about 100 μBq/m³. The demonstrated detection limit is about 100 times better than achievable with reported laboratory-based procedures for the short-time collection intervals of interest.     

Microarray-based in vitro evaluation of DNA oligomer libraries designed in silico.

We report on the microarray-based in vitro evaluation of two libraries of DNA oligonucleotide sequences, designed in silico for applications in supramolecular self-assembly, such as DNA computing and DNA-based nanosciences. In this first study which is devoted to the comparison of sequence motif properties theoretically predicted with their performance in real-life, the DNA-directed immobilization (DDI) of proteins was used as an example of DNA-based self-assembly. Since DDI technologies, DNA computing, and DNA nanoconstruction essentially depend on similar prereguisites, in particular, large and uniform hybridization efficiencies combined with low nonspecific cross-reactivity between individual sequences, we anticipate that the microarray approach demonstrated here will enable rapid evaluation of other DNA sequence libraries.     

Where is the sodium in self-assembled monolayers of single-stranded DNA?

Monolayers of single-stranded DNA (ssDNA) immobilized on surfaces form the basis of a number of important biotechnology applications, including DNA microarrays and biosensors. The organization of ssDNA as layer on a solid substrate allows one to investigate various properties of the DNA in a controlled manner and to use DNA for analytical applications as well as for exploring futuristic schemes for molecular electronics. It is commonly assumed that the adsorbed DNA layer contains some structural water and the cations. Here we show, based on XPS studies, that when monolayers of ssDNA are formed from sodium phosphate buffer and washed thoroughly, no Na+ signal is detected. A finite concentration of ions is observed when the DNA is made from a solution of Mg2+ ions, but it is still only a fifth of what it would be if all the phosphate ions were fully neutralized by the metal cations.     

Synthesis and structures of heterocyclic azidogallanes [(CH3)ClGaN3]4 and [(CH3)BrGaN3]3 en route to [(CH3)HGaN3]x: an inorganic precursor to GaN

The synthesis of [(CH3)ClGaN3]4 (1) with a heterocyclic cyclooctane-like structure and [(CH3)BrGaN3]3 (2) with a trimeric structure has been demonstrated. X-ray structural determinations reveal that 1 and 2 consist of Ga4N4 eight-membered rings and Ga3N3 six-membered rings, respectively, in which the Ga atoms are bridged by the alpha nitrogens of the azide groups. [(CH3)ClGaN3]4 crystallizes in the tetragonal space group P42(1)c with a = 11.017(4) A, c = 8.699(7) A, and Z = 8. [(CH3)BrGaN3]3 crystallizes in the triclinic space group P1 with a = 8.1080(10) A, b = 9.9390(13) A, c = 10.4439(13) A, alpha = 86.069(3) degrees, beta = 86.771(3) degrees, gamma = 80.829(2) degrees, and Z = 6. The reaction of 1 and 2 with LiGaH4 yields [(CH3)HGaN3]x, which is a new low-temperature source of GaN.