7,192 research outputs found
A fundamental study of electrophilic gases for plasma quenching
Electron attachment properties of high molecular weight gases for plasma quenchin
Accessibility to Theater for Deaf and Deaf-blind People: Legal, Language and Artistic Considerations
Without accessibility, theater can be meaningless to the deaf, hard of hearing, and deaf-blind consumers. As part of a larger study conducted by B. Kilpatrick (2007), the authors interviewed 38 participants who have been professionally involved in deaf children’s theater as to their opinions related to theater accessibility options. Their responses bring forward for discussion options ranging from English text-based accessibility, the closest to the English language, to shadow interpreting, which provides accessibility closest to the play being delivered in full in American Sign Language. Using historical research methods, semi-structured and structured interviews, open-ended questions, archival materials, and published documents on theater interpreting, the authors provide a descriptive commentary about accessibility options based on legal, language and artistic considerations. Following these descriptions, the authors recommend that interpreter training programs include theater interpretation techniques
Salivary testosterone measurement in women with and without polycystic ovary syndrome
Clinical and/or biochemical hyperandrogenism is one of the diagnostic criteria for PCOS. An evaluation of the role of salivary testosterone (salT) and androstenedione (salA) for the diagnosis of PCOS was undertaken in a cross sectional study involving 65 women without PCOS and 110 women with PCOS fulfilling all 3 diagnostic Rotterdam criteria. Serum and salivary androgen measurements were determined by LC-MS/MS. salT and salA were significantly elevated in PCOS compared to controls (P<001). No androgen marker was more predictive than another using ROC curves, but multiple logistic regression suggested salT was more predictive than free androgen index (FAI)(p<0.01). The combination of salT or FAI identified 100% of PCOS women. PCOS women with both biochemical and clinical hyperandrogenism as opposed to clinical hyperandrogenism alone showed a metabolic phenotype (p<0.05) and insulin resistance(p<0.001). PCOS patients with an isolated elevated FAI showed increased insulin resistance compared to those with an isolated salT(P<0.05). salT appeared to be at least as predictive as FAI for the diagnosis of the classical PCOS phenotype, and the combination of salT or FAI identified 100% of PCOS patients. This suggests that salT measurement by LC-MS/MS holds the promise of complementing existing laboratory tests as a means of assessing hyperandrogenemia
Launch vehicle trajectory optimization computer program, phase 4 Final technical report
Computer program for retrieving stored data and determining variations in launch vehicle performance as function of mission and vehicle parameter
Bimetallic complexes of d- and f-block metals with pentalene ligands
The focus of this thesis is the synthesis and characterisation of organometallic
complexes incorporating the silylated pentalene ligand, [C8H4{SiiPr3-1,4}2]2- (= Pn†),
bound to more than one metal centre. In general, metals in low oxidation states from the
d- and f-block of the periodic table have been selected for these bimetallic complexes,
as they are potentially reactive with small molecule substrates.
Chapter One introduces the pentalene molecule and its derivatives, and discusses their
use as ligands in organometallic chemistry. Particular emphasis is given to the
application of organometallic pentalene complexes, ranging from conducting polymers
in materials chemistry to small molecule activation and catalysis.
In Chapter Two the silylated pentalene ligand Pn†is used to bridge two lanthanide(II)
centres in anti-bimetallic sandwich complexes of the type [Cp*Ln]2(μ-Pn†) (Ln = Yb,
Eu and Sm). Magnetic measurements and electrochemical methods are used to
investigate the extent of intermetallic communication in some of these systems, which
show potential for the design of organometallic 'molecular-wires'. Chemical oxidation
of [Cp*Yb]2(μ-Pn†) leads to dissociation into mononuclear fragments (η8-Pn†)YbCp*
and [Cp*Yb]+, and reaction of [Cp*Sm]2(μ-Pn†) with CO yields (η8-Pn†)SmCp*.
Rational synthetic routes to mononuclear mixed-sandwich Pn†/Cp* compounds with
trivalent f-block ions (Dy, Tb and U) are also developed, and their magnetic properties
are studied by SQUID magnetometry including variable-frequency ac susceptibility
measurements. These studies identified (η8-Pn†)DyCp* as the first known example of a
pentalene based single molecule magnet, with a closed-waist hysteresis loop observed
up to 2 K.
Chapter Three describes the synthesis of iron(II) complexes with silylated pentalene
ligands, and efforts towards incorporating them into extended organometallic arrays and
heteronuclear anti-bimetallic complexes. Six complexes have been structurally characterised including the triple-decker homobimetallic [Cp*Fe]2(μ-Pn†), and the
potassium salt [Cp*Fe(η5-Pn†)][K] which is an organometallic polymer in the solid
state.
Chapter Four documents efforts towards the synthesis of syn-bimetallic pentalene
complexes, including the first row d-block metals V, Ti and Sc. A novel synthetic route
to the di-titanium bis(pentalene) 'double-sandwich' complex (Pn†)2Ti2 is developed, via
chloride-bridged dimers [(η8-Pn†)Ti]2(μ-Cl)x (x = 2 and 3). The electronic and magnetic
properties of the latter are investigated using EPR spectroscopy and SQUID
magnetometry, and the structure and bonding in (Pn†)2Ti2 is examined using
spectroscopic, crystallographic, electrochemical and computational techniques.
Preliminary studies toward the synthesis of an analogous di-scandium complex were
unsuccessful, however three novel complexes have been synthesised including (η8-
Pn†)ScCp* which is first example of a Sc complex bearing a Pn†ligand to be
characterised by X-ray diffraction.
Chapter Five explores the reactivity of the double-sandwich compound (Pn†)2Ti2
prepared in Chapter Four, with small molecules which are of industrial and
environmental importance. The relatively open structure of (Pn†)2Ti2 allows the
formation of adducts with unsaturated small molecules CO, MeNC and CO2. In the
latter case the adduct formed is unstable at room temperature and the coordinated CO2
molecule is reduced to give a bis(oxo) bridged dimer and a di-carbonyl complex. This
provides the first example of small molecule activation by a di-metal bis(pentalene)
double-sandwich complex.
The reactivity survey of (Pn†)2Ti2 is extended in Chapter Six to other substrates;
including unsaturated heteroallenes as model molecules for CO2. In the case of nonpolar
heteroallenes CS2 and carbodiimide, thermally stable adducts are isolated and
have been structurally characterised. Polar heteroallenes COS and organic isocyanates
undergo reductive transformations to give sulfide- and carbonimidate-bridged
complexes respectively. The reactivity of (Pn†)2Ti2 with organic molecules containing
heteroatom-heteroatom bonds is also described; the reactions with
diphenyldichalcogenides and azobenzene show the ability of the double-sandwich
complex to act as a 2e- and 4e- reducing agent respectively. The rich and varied
chemistry shown by (Pn†)2Ti2 is evaluated and future work is suggested
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