Lamellar x-ray diffraction was studied from thin films of L-α-1,2-dipalmitoyl lecithin (DPL) and a 1:1 mixture (BrDPL) of L-α-l-palmitoyl-2-(9- bromopaimitoyl) lecithin and its 10-bromo analog. The specimens had high lamellar order, with an upper bound on the mosaicity of 6 mrad (0.4°) for DPL and BrDPL. With various water contents,...
The work presented here is focused on applying basic principles of solid-state chemistry to the study and development of new wide band-gap semiconductors and insulators for photovoltaic and electronic-device applications. Analysis of crystal structure, band structure, optical band gap, morphology and transport properties provides fundamental insight into materials performance as...
Due to its importance, the phenomenon of hydrogen
bonding has been the subject of much research over the
years. Among the different techniques used to study
hydrogen bonded systems, vibrational spectroscopy is
perhaps the most sensitive because of the striking
changes induced in molecular spectra by the formation of
hydrogen...
In this dissertation, the spectroscopic properties and thermodynamic stability of a class of materials known as metal oxo and hydroxo clusters are studied. In aqueous solutions, many metals can aggregate into discrete clusters of metals bridged by oxo or hydroxo ligands. These clusters are of particular interest to us for...
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous contaminants formed from the incomplete combustion of organic material. These contaminants are of concern because of their widespread presence in the environment and toxic properties. In addition, PAHs encompass a class of diverse compounds with varying physicochemical properties and exist in the environment as...
A new approach to the discovery of high absorbing semiconductors for solar cells was taken by working under a set of design principles and taking a systemic methodology. Three transition metal chalcogenides at varying states of development were evaluated within this framework. Iron pyrite (FeS₂) is well known to demonstrate...
SOCs volatility and persistence properties cause many SOCs to become ubiquitous in the environment as well as accumulate in areas with lower temperatures such as polar or orographic regions. Many anthropogenic SOCs pose a serious risk to human and ecosystem health because of their persistent, bioaccumulative, and toxic properties in...
Femtosecond stimulated Raman spectroscopy (FSRS) is a powerful ultrafast technique which can track photoinduced excited state structural events on femtosecond (fs) to picosecond (ps) timescales. In addition to high temporal and spectral resolutions, FSRS provides a broad spectral window from ca. 100—2000 cm-1 for detection, enabling the direct mapping of...
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Figure 5.4. Distribution of the O···O distance between the chromophore phenolic
hydroxyl and
In this dissertation, excited state proton transfer (ESPT) and its inhibition in solution and protein environments are revealed using both femtosecond transient absorption (fs-TA) spectroscopy and femtosecond stimulated Raman spectroscopy (FSRS). Using a tunable Raman pump to enhance transient vibrational features of the photoacidic chromophore HPTS in methanol and methanol...
In this report, three studies are presented that aid in the development of drug discovery and their synthesis. In each, the importance of the marriage between computations and experiments is highlighted. Continued efforts in this vein are essential for future efforts towards improving human health.
The first case study investigated...
Pyrolysis of 4-cycloheptene-l-methyl acetate under flow conditions at 285° gives only rearranged bicyclic acetates and hydrocarbons rather than the anticipated simple elimination product methylenecyclohept- 4-ene. These rearranged acetates have the same structures and are formed in virtually the same relative percentages as those observed in the "π- route" solvolysis of...
A comparative study was made on the effect of urea denaturation
of bovine serum albumin (BSA), polyglycyl BSA and poly-L-phenylalanyl
BSA. The denaturation process was followed by ultraviolet
spectrophotometry and optical rotation.
A blue shift in the absorption maximum at 278 mμ was observed
in urea denatured proteins, In 7M...
A spectrophotometric study has been made of catalysis of the decomposition of sulfuryl chloride in carbon tetrachloride solution to an equilibrium mixture of sulfuryl chloride, sulfur dioxide and chlorine. The catalysts were activated charcoal, acetonitrile and 18-crown-6 polyether. A weak acetonitrile-sulfur dioxide complex also was established; formation constants found at...
Alkylation of propylene oxide with 2-lithiofuran gave alcohol I,
which was smoothly converted to acetylfuran II. hydrogenation of II
over rhodium on charcoal followed by Jones' oxidation afforded ketone
III. Further transformation into IV was accomplished via a Wittig
reaction followed by saponification with methanolic sodium hydroxide.
Hydroboration of the...
A facile route to bicyclo(2.1.1)hexanes was developed involving
the intramolecular photocyclization of 1, 5-hexadien-3-one to
bicyclo(2.1.1)hexan-2-one. A study of the chemistry of bicyclo-(2.1.1)hexan-2-one was undertaken. Deuterium exchange and borohydride
reduction demonstrated the strain present in the ketone.
Further evidence was obtained from the failure to introduce substituents
alpha to the...
The unique reaction between 4, 6-dimethoxy-5-nitropyrimidine
and methylhydrazine was investigated. The reaction product was
identified as 4-hydrazino-6-hydroxypyrimidine from (a) spectral
data, (b) by direct synthesis of the product via 4-chloro-6-hydroxypyrimidine
and hydrazine, and (c) by conversion of the product to
the known 4-amino-6-hydroxypyrimidine using Raney nickel. The
product was not...
The extraction of tantalum fluoride complexes by large cationic
extractants (tetraphenylarsonium ion, TPA, and crystal violet) and
by methyl isobutyl ketone (MIBK) has been investigated as a function
of fluoride concentration using ¹⁸² Ta as tracer. Extractions by the
cationic extractants into chloroform were carried out in the absence
of...
Aseptic radiorespirometry has been used to examine
the utilization of external carbon sources by proliferating
Thiobacillus thioparus cells. These studies reveal
that glucose, galactose, mannose, fructose, ribose, DL-glutamate,
and L-aspartate were not utilized by this
chemoautotrophic organism. However, it has been shown
that trace amounts of acetate, glycine, DL-serine, DL-alanine,...
Contaminant transport in ground water is an important environmental process that
affects a host of natural systems. Transport of contaminants is affected by many
processes, including aqueous complexation, adsorption, and redox reactions. One of the
most important components of an aquifer that controls transport is iron-oxide. In this
study, the...
White muscle disease or muscular dystrophy of sheep is a selenium
responsive malady common to many areas with an inherent natural
deficiency of selenium in the forage. The disease can be prevented in
lambs by adding trace amounts (approximately 0.1 ppm) of selenium to
the otherwise selenium deficient, forage fed...
The oxidation of triethylamine by the two electron oxidant
thallium(III) chloride was studied and the results compared to those
when triethylamine is oxidized by copper(II) halides. This study
requires anhydrous conditions since in an aqueous system thallium(III)
chloride is extensively hydrolyzed and triethylamine causes
precipitation of thallium(III) oxide. Most of...
A method of calculating the normal vibrations of polymer molecules
is presented in detail. The method is based on that used by
Schachtschneider and Snyder in their analysis of polypropylene but
has not heretofore been published. The factoring of the infinite matrix
and reduction to the coordinates of the unit...
Neptunium, with its rich redox chemistry, has a special position in the chemistry of actinides. With a decades-long history of development of aqueous separation methods for used nuclear fuel (UNF), management of neptunium remains an unresolved issue because of its not clearly defined redox speciation. Neptunium is present in two,...
This thesis investigated on the dehalogenation of 2, 4-
dichloropyrimidine in various different conditions. These conditions
were changed by varying the solvents, the amount of catalysts and
the hydrogen chloride acceptors in order to study the effects on the
yields.
It was found that the ether-aqueous sodium hydroxide medium
with...
The present study has consisted primarily of an investigation
of the rates of isotopic sulfur exchange between sulfur dioxide and
various sulfur (VI) solutions, both 100% H₂SO₄ and, in particular,
related ammonia-containing sulfur (VI) solutions. One of the main
objects of the work was to obtain a comparison between exchange...
Research on chemicals used as pesticides has been intensified
because of current interest in the possible long range effects on the
biota. It is vitally important to understand the action of these
chemicals on the metabolism of animals and plants which have
direct or indirect contact with pesticides.
It has...
The incorporation of europium and dysprosium in potassium
chloride crystals was investigated. The crystals were prepared by
the Kyropoulos method from melts containing the rare-earth chlorides.
The concentration of these rare-earth ions in the crystals was determined
by neutron-activation analysis. The distribution coefficient of
europium and dysprosium between the molten...
The spectrophotometric method for the determination of the
acid nonextractable flavin in the proteolytic digest of the trichloroacetic
acid precipitate from the heart muscle preparation has been
examined for the interference of the degraded hemeproteins. The
proteolytic digest was chromatographically separated into the heme
and flavin fractions. Spectrophotometric determinations made...
Vanadium pentoxide electrodes were prepared by melting
the powdered oxide around a platinum foil in a pyrex tube. The
electrode was discharged, and the discharge product was studied,
but not identified, by means of chemical and x-ray diffraction analysis.
A study was made of the relationship between the electrode
potential...
New alloys containing refractory metals have been developed
by the aero-space industry to meet the demand for thermally resistant
materials. The chemical analysis of these alloys has been
handled successfully by the use of ion exchange. Hydrofluoric acid,
either alone or combined with hydrochloric acid, has here-to-fore
been used to...
The development and optimization of a single-phase derivatization
technique for small ring aromatics in water are presented. Also
described are the design, optimization and application of a remote
reaction chamber for fiber optic sensing.
Aqueous solutions of the major aromatic compounds in gasoline are
derivatized to o-nitrosophenol-Cu complexes with a...
A long path dc plasma arc operated in an atmosphere of
argon is described. The arc is easily ignited and operated, and
is inexpensive to use. Samples were introduced into the arc as
solution aerosols. Radially resolved emission measurements are
reported for calcium, copper, and hafnium. The detection limit
for...
A Heath EUW-20A Servo-Recorder was converted to a self-balancing, recording Wheatstone bridge. The EUW-20A 10000Ω slide-wire was used as the variable resistance arm of the bridge, the
servo-amplifier was used as the bridge unbalance signal detector,
and the servo-motor was used to balance the bridge automatically.
The bridge was arranged...
A comparison was made of the d.c. conductivity of KCI:Pb²⁺
and KCl:PbO single crystals at temperatures greater than 325°C.
The energy of activation was 0.72 ev for all crystals. Lead concentration
was determined by chemical, optical and electrical methods. The
half band width of the UV absorption band at 273...
Since the use of N, N-diethylaniline hydrochloride in the chlorination
of uric acid with phosphoryl chloride seems to promote the
reaction, a study of the effect of other salts of nitrogenous bases in
the chlorination of uric acid was undertaken. When N, N-diethylaniline
hydrochloride was used in lieu of the...
Since many 1, 4, 5, 6-tetrahydropyrimidines have become available
and commercially useful in recent years, a study of the chemistry
of certain of these compounds has been undertaken.
2-Hydroxy- and 2-mercapto-1, 4, 5, 6-tetrahydropyrimidine
have been synthesized by the condensation of urea and thiourea, respectively,
with 1, 3-propanediamine, with yields...
Solid-state amorphous materials show amazing promise in thin-film electronics. The interface-to-bulk ratio of thin films makes interfacial chemistries of these systems of utmost importance. Thin films of amorphous metals, dielectrics and semiconductors have novel chemistries that are not only based upon their elemental constituent makeup, but also based upon the...
The purpose of this investigation was to determine the nature of the extractives from red alder bark in an effort to discover the materials which cause the red stain in red alder wood. Samples of bark and wood were obtained and successively extracted with hexane, benzene, ether, ethanol, and hot...
An attempt has been made to elucidate the biosynthetic precursor
of ethylene in the mold P. digitatum. By application of basic
radiotracer methodology and the utilization of several specifically
labeled radiochemical substrates, it has been possible to demonstrate
that the internal carbon atoms of C-4 dicarboxylic acids such
as succinate,...
Pelargonium graveolens Ait., rose geranium, contains several oxygenated monoterpenes, most of which are related to each other structurally. In this work, the metabolism and interconversions of these terpenes was investigated. A chromatographic analysis of geranium oil was performed initially for the purposes of identifying the terpenes and determining which chromatographic...