The CARS apparatus at OSU was modified to permit studies in the 0-500 cm⁻¹ spectral region. The new low frequency capabilities were then used to study molecular clusters formed in free expansion jets of carbon dioxide. A strong cluster band was observed at 73 cm⁻¹, with a weaker shoulder at...
An important aspect in device technology is the
processing of GaAs to produce highly-resolved etch
patterns on the substrate. This is done typically on the
GaAs(100) surface. Recently, a number of methods, all
using chlorinated vapor reactants, have been applied to
fabrication of GaAs devices. In spite of these
technological...
Early studies on the biosynthesis of Sarubicin A, 1, had suggested the
intermediacy of the novel aromatic amino acid 6-hydroxyanthranilic acid,
17. To investigate the biosynthetic steps beyond 17, [¹³C-¹⁵N carboxamide]
6-hydroxyanthranilamide, 27a, was synthesized, and fed to fermentations
of Streptomyces helicus. Incorporation of 27a into 1 provided suggestive
evidence...
A practical and versatile instrument has been developed both to
optimize the chemistry of bio- and chemiluminescence reactions and to
measure ultra-trace quantities of associated analytes. The instrument
consists of a pneumatic flow injection system linked to a detection cell and a
signal processing and readout system. The disk-like cell...
Single crystal surfaces can be used as substitutes or
models for the actual reactive surfaces of heterogeneous
catalysts. The advantage in using such models is that the
reaction of interest can be isolated on the particular
face of the crystal that is thought to be catalytically
active. A variety of...
Nearly 100 chondrules were extracted from -8.6g of the
Mokoia (CV3) meteorite and have been analyzed by
sequential instrumental neutron activation analysis
(INAA). The resulting data were utilized in a
comprehensive statistical characterization of these
objects and, unlike similar investigations, virtually no
loss of relevant data was incurred due to...
A novel acyl protecting group for cytosine and adenine has been prepared
from 4-( chloromethyl) benzoic acid. Reaction of the acid with morpholine produces
4-( 4-morpholinyl )methyl benzoic acid which is converted to it's acid chloride
with thionyl chloride. This may be used to acylate cytidine and adenosine under
standard...
A new general method is developed for the optimization of
HPLC ternary or pseudo-quaternary mobile phases which are
represented by the trilinear coordinate system. This method can
predict the global optimum of the mobile phase composition. The
global optimum composition along each edge of the triangle and
the corresponding selectivity...
The plant Senecio jacobaea (tansy ragwort) produces several macrocyclic pyrrolizidine alkaloids which cause irreversible liver cirrhosis. All of the pyrrolizidine alkaloids in Senecio jacobaea are macrocyclic diesters of the necine base retronecine, with the two most predominant being seneciphylline and jacobine. Unlike horses and cattle, sheep and goats are generally...
The photodebromination of selected bromoarenes has been studied at 300 nm
to determine the the possible mechanistic pathways leading to product.
Irradiation of 4-bromobiphenyl (BpBr) at this wavelength leads to the product
biphenyl. The quantum yield of intersystem crossing (0.98) and quenching
studies with cis-1 ,3-pentadiene suggest that the reaction...
Polybenzimidazoles were synthesized from 3, 3', 4, 4'-tetraminobiphenyl
(diaminobenzidine, or DAB) with orthoesters, carboxylic acid derivatives (an ester and
an acid) and with m-benzenedialdehyde. The products were of low molecular weight,
as evidenced by low inherent viscosity, except in the case of the dialdehyde plus DAB.
The product of that...
In particle induced desorption-ionization mass spectrometry the strength of an
analyte's signal under a given set of bombardment conditions is usually considered to
be representative of the analytes relative surface activity. This rationale is generally
used to explain differences in the technique's sensitivity between and within various
classes of compound....
Several experiments were undertaken to investigate the mechanism of
photodechlorination of pentachlorobenzene. The thermal methoxydechlorination
reaction of pentachlorobenzene was studied. In DMSO at 50 °C sodium
methoxide reacts smoothly with pentachlorobenzene to give three
tetrachloroanisole isomers. A second-order kinetic plot for this reaction is linear to
high precision, indicating that...
Hop cell wall material (CWM) extracted from hop leaves (hamulus lupulus) was
purified and characterized. The total sugar content, uronic acid content and
monosaccharide composition of the CWM were determined. Galacturonic acid is the
major component in the CWM. A mixture of unsaturated oligogalacturonides were
released from purified hop CWM...
The photohydrodebromination of brominated paracyclophanes was studied to
help elucidate the possible mechanistic pathways leading to product for
bromoarenes in general. Several brominated [2.2]paracyclophanes were studied to
determine the effect of substitution patterns on this reaction. [2.2]Paracyclophanes
were chosen for this study in order to investigate possible intramolecular excimer
formation...
A synthetic approach toward the two major fragments of cathedulin K-19,
euonyminol (4) and dimethyl cathate (69), was investigated. Synthesis of
dimethyl cathate was accomplished in 3 steps starting from 73. Efforts directed
towards the synthesis of euonyminol, a highly oxygenated dihydroagarofuran
sesquiterpene, was advanced to a stage in which...
A fiber optic fluorometer utilizing a double-fiber optic probe
was constructed. The absolute fluorescence signal and effective
collection efficiency are approximately one fifth those of typical
cuvette fluorometers and agree with those predicted by theory. A
quinine sulfate calibration curve shows linearity from a detection
limit of 10 pg/mL to...
The inert gas ion bombardment of solid surfaces has
found many uses in the field of analytical chemistry. In
one method of spectrochemical analysis, inert gas ion
bombardment in a glow discharge is used to produce an atomic
vapor, representative of the sample bulk, which is analyzed
using atomic absorption...
Polybenzimidazoles were synthesized from 3,3'-diaminobenzidine (DAB) and dicarboxylic acids. The polymerizations using the dicarboxylic acid monomers were carried out in polyphosphoric acid (PPA) and phosphorus pentoxide/methansulfonic acid (PPMA) which acted as the solvent and condensing agent. The resulting polybenzimidazoles had inherent viscosities in the range of 0.12 to 0.84 dL/g....
An oscillating plasma glow discharge detector for gas
chromatography is used to obtain fingerprint information
about an analyte by combining both the average cell
current and oscillation frequency signals. Five homologs
each of the n-alkanes, 1-alkenes, 1-alkynes, 2-ketones and
aldehydes are studied. Although triplicate determinations
had some scatter due to...
More that just magnificent views of atoms and
molecules, Scanning Tunneling Microscopy, STM, images have
the potential to answer some fundamental questions relating
to surface molecular dynamics and bonding characteristics of
localized species versus more common analytical tools that
provide average of bulk sample information. A special
feature of the...
The photoelectron spectra of a series of ketone
compounds have been investigated in the gas phase. Core
ionization energies were measured to probe the effects of
molecular size and connectivity number on core ionization
energies.
It was found that core ionization energies roughly
decrease with increasing connectivity number as expected....
The change in the oscillation frequency in the current of
an atmospheric helium glow discharge is a sensitive detector
for gas chromatography. The response of the detector is in
the femtomole and picomole range for nonane and decane. The
effluent of a capillary column is directed into a glow
discharge...
Two related techniques, based upon ion-exchange solid phase extraction, have been
developed for the determination of arsenic speciation. The inorganic arsenic species
arsenite (As(III)) and arsenate (As(V)) are separated by anion-exchange and detected with
graphite furnace atomic absorption spectrophotometry (GFAAS) with a nickel matrix
modifier. The first separation technique, which...
Three aspects of glow discharges have been studied: glow discharge oscillations,
sputtering, and coupling between cathode and anode regions the two most important
regions in a glow discharge. Cathode and anode processes are tightly coupled by electron
and ion coupling effects. Both electron and ion coupling effects were observed by...
An atmospheric pressure argon glow discharge is shown
to detect trace levels of carbohydrates in aqueous flowing
systems, using either of two glow discharge solution
interface configurations. The first configuration consists
of an oscillating glow discharge sustained between a flowing
aqueous cathode and platinum anode. Picomole and micromolar
mass and...
A new experimental apparatus was built at Oregon State University to perform high resolution stimulated Raman spectroscopy in a pulsed molecular jet at state densities of the order of 10¹¹ cm⁻³. The technique uses a stimulated Raman step to first populate a vibrational/rotational level and then a resonantly enhanced multiphoton...