Application of magnetite and silica-magnetite composites to the isolation of genomic DNA

Magnetite and silica-magnetite composites were used as adsorbents for the isolation of genomic DNA from maize kernels. Two methods are described for the preparation of silica-magnetite composites, both of which afford higher yields of genomic DNA than when using magnetite alone, or a commerically available kit. DNA isolated using silica-magnetite was suitable for use in further applications such as polymerase chain reaction amplification and enzyme digestion.     

Resonance ionization spectroscopy of lithium

Saturated three-step resonance ionization of ground state lithium was demonstrated and the first measurement of the photoionization cross section from the excited n = 3 manifold of lithium was made. This demonstration of saturation shows the feasibility of detecting single atoms of lithium using sensitive charge detection methods.     

Multiecho multimoment refocussing of motion in magnetic resonance imaging: MEM-MO-RE

Gradient moment nulling techniques for refocussing of spin dephasing resulting from movement during application of magnetic resonance imaging gradients have gained widespread application. These techniques offer advantages over conventional imaging gradients by reducing motion artifacts due to intraview motion, and by recovering signal lost from spin dephasing. This paper presents a simple technique for designing multiecho imaging gradient waveforms that refocus dephasing from the interaction of imaging gradients and multiple derivatives of position. Multiple moments will be compensated at each echo. The method described relies on the fact that the calculation of time moments for nulled moment gradient waveforms is independent of the time origin chosen. Therefore, waveforms used to generate the second echo image for multiple echo sequences with echo times given by TEn = TE1 + (n - 1) * (TE2 - TE1) may also be used for generation of the third and additional echo images. All echoes will refocus the same derivatives of position. Multiecho, multimoment refocussing (MEM-MO-RE) images through the liver in a patient with ampullary adenocarcinoma metastatic to the liver demonstrate the application of the method in clinical scanning.     

Open shell calculations for the two- and three-electron ions

Open shell calculations are made for all the three-electron atomic systems of the second period of the periodic table. These results are compared with corresponding two-electron and experimental energies.

It is noted that the improvement of open shell over closed shell calculations becomes less with increasing atomic number. In parallel trend the disparity of both from the experimental results increases with Z. An electron affinity of zero is found for the helium atom.     

A New Series of Proton/Charge Transfer Molecules: Synthesis and Spectral Studies of 2-(5-Aryl-1-carbomethoxy-1H-pyrazol-3-yl)phenols

Abstract. The carbomethoxyhydrazone of 2'-hydroxyacetophenone was trilithiated with excess lithium diisopropylamide and C-acylated with a variety of benzoate esters followed by acid cyclization of the intermediates to 2-(5-aryl-l-car-bomethoxy-lHpyrazol-3-yl)phenols [3-(2-hydroxyphen-yl)-lH-pyrazoles]. The products were characterized by Fourier transform-IR, ^lH NMR, ¹³C NMR, UV-visible absorption and fluorescence. All the derivatives in n -heptane have an absorption maximum at ˜304 nm and an extremely weak (φ_r= 10 ⁴) fluorescence with maxima in the range of 335–460 nm. The broad range of fluorescence maxima and fluorescence quantum yields is attributed to varying contributions of charge transfer that are dependent on both the identity of the substituent and solvent polarity. A phenomenally large Stokes-shifted fluorescence maximum at 620 nm was observed for 2-(l-car-bomethoxy-5-[4-dimethylaminophenyl]-lff-pyrazol-3-y1)phenol in n-heptane and attributed to excited-state intramolecular proton transfer. As a result, competitive excited-state proton/charge transfer properties have been observed in the pyrazoles studied, of which the spectral properties can be fine tuned by substituent as well as solvent effects.     

The geometry of state space

The geometry of the state space of a finite-dimensional quantum mechanical system, with particular reference to four dimensions, is studied. Many novel features, not evident in the two-dimensional space of a single spin, are found. Although the state space is a convex set, it is not a ball, and its boundary contains mixed states in addition to the pure states, which form a low-dimensional submanifold. The appropriate language to describe the role of the observer is that of flag manifolds.     

Solid phase extraction for an improved assay of physostigmine in biological fluids

A simple, selective and very sensitive assay is described for the quantification of physostigmine in blood, plasma and urine. The most appropriate solid phase column was selected after a systematic investigation of nine types of phase. The conditions for solid phase extraction were optimized using [3H]physostigmine so that the overall recoveries were greater than 90%. Physostigmine was retained on alkaline treated cyanopropyl columns and eluted into the minimum volume of methanol, obviating the need for an evaporation step. Extracted samples were quantified by HPLC with a three electrode coulometric detection system. The limit of detection was 50 pg/mL for a 0.5 mL plasma sample. The precision (CV) for 0.5 mL plasma samples containing 50 pg was 8.1%. Application of the method to plasma, blood and urine samples is presented.