579 research outputs found
„Frailty” - Kann durch Prävention die Altersgebrechlichkeit verhindert werden?
In dieser Arbeit soll auf das gesellschaftliche Problem der Altersgebrechlichkeit (Frailty) aufmerksam gemacht werden. Die Bedeutung für jedes Individuum, gebrechlich, frail zu altern und damit den Verlust an Lebensqualität und eine vorzeitige Mortalität zu riskieren wird deutlich gemacht. Das Alterssyndrom wäre einfach zu diagnostizieren, fällt aber dennoch zurzeit durch ein Raster. Deshalb wird ein Kodierungsvorschlag für Frailty entworfen, aus dem sich gezielte individuelle Therapie- und Rehabilitationsmaßnahmen ableiten lassen. Der Zusammenhang von altersphysiologischen immuno-neuro-endokrinen Veränderungen und der Frailty bilden die Grundlage für eine Präventionskaskade: F1, F2; F3 in Anlehnung der „U“-Untersuchungen für Kinder
Gold(III)-CO and gold(III)-CO2 complexes and their role in the water-gas shift reaction
The water-gas shift (WGS) reaction is an important process for the generation of hydrogen. Heterogeneous gold catalysts exhibit good WGS activity, but the nature of the active site, the oxidation state, and competing reaction mechanisms are very much matters of debate. Homogeneous gold WGS systems that could shed light on the mechanism are conspicuous by their absence: gold(I)–CO is inactive and gold(III)–CO complexes were unknown. We report the synthesis of the first example of an isolable CO complex of Au(III). Its reactivity demonstrates fundamental differences between the CO adducts of the neighboring d8 ions Pt(II) and Au(III): whereas Pt(II)-CO is stable to moisture, Au(III)–CO compounds are extremely susceptible to nucleophilic attack and show WGS reactivity at low temperature. The key to understanding these dramatic differences is the donation/back-donation ratio of the M–CO bond: gold-CO shows substantially less back-bonding than Pt-CO, irrespective of closely similar n(CO) frequencies. Key WGS intermediates include the gold-CO2 complex [(C^N^C)Au]2(m-CO2), which reductively eliminates CO2. The species identified here are in accord with Au(III) as active species and a carboxylate WGS mechanism
SMBOs: buying time or improving performance?
On the basis of an empirical analysis of 491 UK recent secondary management buyouts (SMBOs), we find strong evidence of a deterioration in long-run abnormal returns following SMBO deals. SMBOs also perform worse than primary buyouts in terms of profitability, labor productivity, and growth. We find no evidence for superior performance of private equity (PE) backed SMBOs, compared with their non-PE-backed counterparts. It appears that a PE firm's reputation and change in management are important determinants of improvements in profitability and labor productivity, respectively. High debt and high percentage of management equity tend to be associated with poor performance measured by profitability and labor productivity. Notably, none of the buyout mechanisms (i.e., financial, governance, operating) normally associated with performance improvements generate growth during the secondary buyout phase. The results are robust to the use of alternative performance measures, alternative benchmarks, and the possibility of sample selection bias. © 2013 The Authors. Managerial and Decision Economics published by John Wiley & Sons, Ltd
An element through the looking glass: Exploring the Au-C, Au-H and Au-O energy landscape
Gold, the archetypal “noble metal”, used to be considered of little interest in catalysis. It is now clear that this was a misconception, and a multitude of gold-catalysed transformations has been reported. However, one consequence of the long-held view of gold as inert metal is that its organometallic chemistry contains many “unknowns”, and catalytic cycles devised to explain gold's reactivity draw largely on analogies with other transition metals. How realistic are such mechanistic assumptions? In the last few years a number of key compound classes have been discovered that can provide some answers. This Perspective attempts to summarise these developments, with particular emphasis on recently discovered gold(III) complexes with bonds to hydrogen, oxygen, alkenes and CO ligands
The creation of new rotation arc to the rat latissimus dorsi musculo-cutaneous flap with delay procedures
BACKGROUND: Latissimus dorsi musculocutaneous flap is one of the most frequently performed reconstructive techniques in surgery. Latissimus dorsi muscle has two arcs of rotation. It is classified as type V muscle. This muscle can be elevated on the thoracodorsal artery to cover large defects in the anterior chest and also, the muscle can be elevated on the segmental vessels to cover midline defects posteriorly. The aim of this study was to create a new arc of rotation on a vertical axis for the muscle and investigate effectiveness of vascular and chemical delays on the latissimus dorsi muscle flap with an inferior pedicle in an experimental rat model. We hypothesized that the latissimus dorsi muscle would be based on inferior pedicle by delay procedures. METHODS: We tested two different types of delay: vascular and combination of vascular and chemical. We also tried to determine how many days of "delay" can elicit beneficial effects of vascular and combination delays in an inferior pedicled latissimus dorsi musculocutaneous flap. To accomplish this, 48 male Sprague-Dawley rats were randomly subjected to vascular or combination delay (vascular and chemical). In addition, one ear of each rat was assigned into a delay procedure and the other ear was used as a control. Results were evaluated macroscopically, and micro-angiography and histological examinations were also performed. As a result, there was a significant difference in viable flap areas between vascular delay alone and control groups (p < 0.05). RESULTS: The higher rate of flap viability was obtained in seven-day vascular delay alone. However, there was no significant difference in the viability between seven-day vascular delay and five-day vascular delay (p < 0.05), so the earliest time when the flap viability could be obtained was at five days. The rate of flap viability was significantly higher in the vascular delay combined with chemical delay than the control group (p < 0.05). CONCLUSION: The combination of vascular and chemical delays increased the rate of viability. Nevertheless, there was no significant difference between vascular delay alone and combination of vascular and chemical delays. Chemical delay did not significantly decrease the delay period. Better histological and microangiographical results were achieved in delay groups compared to control groups. We concluded that the arch of the latissimus dorsi musculocutaneous flap can be changed and the flap can be used for various purposes with the delay procedures
Über den Mechanismus der Oxydationsvorgänge und die Oxydation von Eisen(II)salzen durch Wasserstoffsuperoxyd
Über eine Verbindung von Schwefelsäure-anhydrid mit Stickoxyd und die Theorie des Bleikammer-Prozesses
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