1,582 research outputs found
Effects of Hyperbaric Hypoxia on Some Enzyme Systems in the Mammalian Liver
The metabolic effects of hypobaric hypoxic stress on the mammalian liver were studied. The lactate dehydrogenase (LDH) and succinate dehydrogenase (SDH) activity of mouse liver homogenates were measured after exposure to an equivalent altitude of 36,000 feet and compared to controls kept at zero altitude. After six and twelve hour incubation periods, the altitude exposed samples demonstrated a significantly higher LDH activity than controls. SDH activity remained unchanged from controls after six hours but was significantly lower than controls after a 12 hour exposure to altitude. It is concluded that the changes in enzyme activity reflect a metabolic control mechanism attempting to maintain adequate energy production during periods of exposure to hypobaric hypoxic stress
IT/IS Project Portfolio Selection in the Presence of Project Interactions â Review and Synthesis of the Literature
Adequately considering interactions among IT/IS projectsin the process of constructing an IT/IS project portfoliois an important requirement for value-based IT/IS projectportfolio selection. A lot of articles already deal with modelingapproaches to incorporate such interactions, but theliterature lacks a common terminology and a structured perspectiveon the manifold types of interactions and their effects.When applied in business practice, this may lead toa systematically wrong project portfolio selection. Basedon a comprehensive literature review, our contributions are(1) an identication of relevant classication dimensions ofIT/IS project portfolio selection, (2) the development of aframework that provides a structured perspective on deterministic,intratemporal interactions, and { as the main contribution{ (3) a unication of the terminology and the semanticsof interactions among IT/IS projects. This workshall support decision-makers in the identication of possibleinteractions among IT/IS project proposals
Towards adaptable nano-circuitry - functional domain walls and disorder engineering in improper ferroelectrics [Abstract]
Positivity of hexagon perturbation theory
The hexagon-form-factor program was proposed as a way to compute three- and
higher-point correlation functions in super-symmetric
Yang-Mills theory and in the dual AdSS superstring theory, by
exploiting the integrability of the theory in the 't Hooft limit. This approach
is reminiscent of the asymptotic Bethe ansatz in that it applies to a
large-volume expansion. Finite-volume corrections can be incorporated through
L\"uscher-like formulae, though the systematics of this expansion is largely
unexplored so far. Strikingly, finite-volume corrections may feature negative
powers of the 't Hooft coupling in the small- expansion, potentially
leading to a breakdown of the formalism. In this work we show that the
finite-volume perturbation theory for the hexagon is positive and thereby
compatible with the weak-coupling expansion for arbitrary -point functions.Comment: v2: misprints corrected, further details on physical magnons adde
Oxygen Toxicity in the Mammalian Liver
The effect of hyperbaric oxygen tensions on the oxygen consumption of mouse liver homogenates was investigated. It was found that hyperbaric oxygen rapidly inhibits the oxidative metabolism of the mammalian liver. Mouse liver homogenate exposed to an oxygen tension of 3837.8 mm Hg for 30 minutes demonstrated a 50.6% reduction in oxygen consumption compared to controls exposed to nitrogen at ambient pressure. The effects of reduced glutathione as a protective agent against hyperbaric oxygen toxicity were also examined. Liver homogenates pretreated with reduced glutathione and exposed to hyperbaric oxygen tensions demonstrated greater activity than untreated controls. It is concluded that: (1) Reduced glutathione protects important enzymes associated with oxidative metabolism by keeping them in a reduced and viable state, and (2) Reduced glutathione can stimulate oxygen consumption by increasing succinate formation through a reduced glutathione - succinate shunt
Arylâgroup substituted polysiloxanes with highâoptical transmission, thermal stability, and refractive index
Polysiloxanes are an important class of polymers for optoelectronic applications.
Novel polysiloxanes with high-refractive index (RI) based on phenanthrenylsubstituted monomers are prepared by a polycondensation reaction starting
from various substituted dialkoxysilanes as monomers. The substitution patterns
on the Si atom are systematically changed to vary the properties of the
linear polymers as well as the final cured material. The two monomers with
polycyclic aromatic side groups 9-phenanthrenylmethyldimethoxysilane and
9-phenanthrenylphenyldimethoxysilane are synthesized and fully characterized,
including their single crystal X-ray structures. Linear polysiloxanes with variations in hydride, methyl, vinyl, phenyl, and phenanthrenyl side group content
are prepared by acid- and base-catalyzed polycondensation reactions. Both Si H
and Si vinyl substituted polymers with molecular weights up to 30 kDa and
adjustable RI's from 1.52 to 1.63 are obtained and the thermally cured by
Pt-catalyzed hydrosilylation reactions. Polysiloxane resins are obtained with
high-RI's, optical transmittance above 95% and thermal stabilities up to 420C.
Long-term thermal stability tests show transmittance values above 85% even
after 60 days of thermal treatment at 180C
Reading mixtures of uniform sequence-defined macromolecules to increase data storage capacity
In recent years, the field of molecular data storage has emerged from a niche to a vibrant research topic. Herein, we describe a simultaneous and automated read-out of data stored in mixtures of sequence-defined oligomers. Therefore, twelve different sequence-defined tetramers and three hexamers with different mass markers and side chains are successfully synthesised via iterative Passerini three-component reactions and subsequent deprotection steps. By programming a straightforward python script for ESI-MS/MS analysis, it is possible to automatically sequence and thus read-out the information stored in these oligomers within one second. Most importantly, we demonstrate that the use of mass-markers as starting compounds eases MS/MS data interpretation and furthermore allows the unambiguous reading of sequences of mixtures of sequence-defined oligomers. Thus, high data storage capacity considering the field of synthetic macromolecules (up to 64.5âbit in our examples) can be obtained without the need of synthesizing long sequences, but by mixing and simultaneously analysing shorter sequence-defined oligomers
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