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Der vorliegende Ubersichtsartikel berichtet uber Fortschritte in der molekularen Modellierung und Simulation mittels massiv-paralleler Hoch- und Hochstleistungsrechner (HPC). Im SkaSim-Projekt arbeiteten dazu Partner aus der HPC-Community mit Anwendern aus Wissenschaft und Industrie zusammen. Ziel dabei war es mittels HPC-Methoden die Vorhersage von thermodynamischen Stoffdaten in Bezug auf Effizienz, Qualitat und Zuverlassigkeit weiter zu optimieren. In diesem Zusammenhang wurden verschiedene Themen bearbeitet: Atomistische Simulation der homogenen Gasblasenbildung, Oberflachenspannung klassischer Fluide und ionischer Flussigkeiten, multikriterielle Optimierung molekularer Modelle, Weiterentwicklung der Simulationscodes ls1 mardyn und ms2, atomistische Simulation von Gastrennprozessen, molekulare Membran-Strukturgeneratoren, Transportwiderstande und gemischtypenspezifische Bewertung pradiktiver Stoffdatenmodelle.

Familial paragangliomas of the neck are often bilateral and more aggressive than spontaneous forms. Tumors appear earlier (2nd-4th decade) often with diffuse, multifocal involvement. Without treatment, these tumors can lead to significant morbidity. Three families with succinate dehydrogenase subunit D (SDHD) germline mutations underwent clinical and genetic evaluation. Patients were screened using ultrasound and evaluated further with conventional and functional imaging. Tumors with a diameter >1.5 cm were surgically removed. Multicentric and bilateral tumors were detected in 9/13 (69%) and 8/13 (62%) patients, respectively. Surgical morbidity occurred in 64% of patients. Local recurrence was 57%, although this was lower in tumors with a diameter

We analyse the relationship between firm value, as measured by Tobin's q, and newly released indices of effective corporate governance for a sample of 263 Canadian firms. The results indicate that corporate governance does matter in Canada. However, not all elements of measured governance are important, and the effects of governance do differ by ownership category. For the entire sample of firms we find no evidence that a total governance index affects firm performance. This is mainly because we find no evidence that board independence, the most heavily-weighted sub-index, has any positive effect on firm performance. Indeed, for family-owned firms we find that the effect is negative. In general, sub-indices measuring effective compensation, disclosure and shareholder rights practices enhance performance and this is true for most ownership types. We also find no evidence that governance practices are endogenous.

Hypoglycemia-induced peripheral neuropathy due to insulinoma is unusual and, as far as we know, has previously been reported in only 34 patients. In this case report, we describe the clinical features, electrophysiological features, and pathological findings in a 37-year-old patient with polyneuropathy from repeated hypoglycemic episodes over a 9-year period that related to an insulinoma. The literature is discussed. The reported case is of special interest because the peripheral neuropathy led to the correct diagnosis.

Metastable materials like amorphous silicon (a-Si) are created under non-equilibrium conditions, such as quenching from the melt. Therefore, in contrast to the equilibrium phases, careful control of the external thermodynamic variables (temperature and pressure) is important, as they influence the quality of the material produced. We present a scheme for incorporating temperature and pressure control in tight-binding molecular dynamics. It is applied to a-Si formation from the melt under zero external pressure. The influence of the control mechanisms is studied. The characteristics of the prepared a-Si specimen are discussed.

Based on a multiple reflection model, the concentration depth profiles of gold diffused into a silver substrate are determined. To conclude the structure of the sample from the measured intensity of radiation, an accurate correction procedure is necessary. A new model was developed for this purpose. Since the new electron probe microanalysis (EPMA) correction procedure is also valid for tilted samples, measurements with different geometries could be performed. The different angles of incidence and take-off angles allow for a better comparison of theory with experiment. One advantage of the applied multiple reflection model is that it can be extended comparatively easily with the analysis of layered specimens. Measurements of some specimens with one layer on a substrate are reported. The mean deviation of calculated thicknesses is about 10%. To calculate depth profiles, gold was evaporated with physical vapor deposition on silver foils. The thicknesses of evaporated gold films were 50 and 100 nm. Then the specimens were annealed at a temperature of approximately 400°C. Finally, the concentration depth profiles were quantified with EPMA. The shape of the profiles was derived from a simple diffusion model valid for the samples under consideration. To check the shape of the functions obtained, a comparison with measurements by secondary ion mass spectrometry was performed.

An electron scattering model (multiple reflections) based on physical quantities only is refined and extended. New expressions for the most probable scattering angle, for the angular distribution of transmitted electrons, and for the angular distribution of backscattered electrons under oblique incidence, derived by fitting to already published data or to Monte Carlo results, are presented and compared with well-established formulae. The mean path-elongation factor for a multiple reflection model is calculated by introducing a correlation of angular distributions. The value of the new path elongation factor is compared with already existing fits.

An equation for angular-dependent energy distributions of backscattered electrons is presented. Extensive Monte Carlo simulations lead to a simple description for the energy distribution. A comparison of the new expression with experimentally derived curves, Monte Carlo results, and an analytical model is performed. The newly derived energy distributions are used for the calculation of the surface ionization ϕ0 for oblique angle of incidence. For normal incidence, a comparison with several published experimental data leads to a mean value for the deviation of < 4%. For tilted specimens the results are compared with findings of other authors.

The long-term follow up of 128 colorectal cancer patients is reported. Seventy-nine percent (101/128) of the patients had curative resections: 70 patients had radical lymphadenectomies with wide removal of tumor-adjacent nodes, and 31 patients had standard resections. The 5-year overall survival rates for Dukes' stage B and C patients and for all rectosigmoid cancer patients significantly favored radical resection (60% vs. 38%, 57% vs. 29%, respectively, P < 0.05). Tumor-free survival rates were also higher after radical lymphadenectomy but did not reach statistical significance. Eleven percent (14/128) of the patients required multiorgan resections, and/or preoperative radiation to render fixed cancers resectable, and these patients had a 10-year tumor-free survival rate of 45%, compared to zero % 5-year survival for the 27 patients who underwent palliative procedures (P < 0.01). These results confirm that many colorectal cancer patients will be cured with aggressive treatment and they support the need for a controlled trial for evaluation of lymphadenectomy for this disease. © 1996 Wiley-Liss, Inc.

Starting from a scattering model, the transmission coefficient of electrons for an oblique angle of incidence is derived. The descent of the transmitted fraction is described by the backscattering of electrons and the energy loss caused by the decreasing mean free path. The angular and energy distribution of electrons is replaced by the most probable angle and mean energy. A comparison with other models and measurements valid for normal incidence was made. The altered transmission characteristics by tilting the sample were verified by comparison with results from Monte Carlo simulations and results from Neubert and Rogaschewski, which were based on measurements. An analytical expression for the transmission law was obtained.

Wahrend in der letzten Ausgabe von BIUZ anhand einfacher Laborversuche die Moglichkeit aufgezeigt wurde, zellphysiologische Leistungen, wie die pinocytotische Aufnahme von gelosten Substanzen, Lichtmikroskopisch zu beobachten (Das Experiment - Teil I „Die Pinocytose”), steht im heutigen Teil II die experimentelle Durchfuhrung der Phagocytose als einer weiteren Moglichkeit des cytotischen Stofftransports im Vordergrund der Betrachtungen. ahnlich wie die Pinocytose wird auch die Phagocytose durch externe Reize ausgelost. Reizauslosende Faktoren sind hier allerdings keine Losungen, die bei den Amoben eine eher unspezifische Pinocytose einleiten, sondern Beuteorganismen in Form von Ciliaten und Flagellaten; diese rufen bei Beruhrung mit der Amobe eine lokale und spezifische Antwort in Form einer Phagocytose hervor.

Die meisten tierischen Zellen besitzen ein komplexes, vakuolares Verdauungssystem mit Endosomen und Phagosomen sowie primaren und sekundaren Lysosomen als Hauptkomponenten. Summarisch betrachtet enthalten diese Vakuolen extrazellulares oder intrazellulares Material, eine Mischung von maximal 40 Verdauungsenzymen sowie verschiedene Membran-spezifische Proteine fur gezielte Transport- und Fusionsvorgange. Nach neueren Untersuchungen verfugen die meisten Zellen aber auch uber nichtlysosomale Verdauungsmoglichkeiten; so konnen Biomolekule entweder direkt im Grundplasma oder in bestimmten Zellkompartimenten wie der Kernhulle, dem endoplasmatischen Retikulum oder den Mitochondrien abgebaut werden. Diesen Weg beschreitet die Zelle vor allem bei der Beseitigung abnormer oder kurzlebiger Proteine durch Ca2+-aktivierbare Proteasen (Calpaine) oder Ubiquitin-abhangige Proteolyse. Dagegen unterliegen die meisten langlebigen cytoplasmatischen Proteine einer normalen lysosomalen Verdauung, Nachdem im ersten Teil dieses Beitrags (im vorangegangenen BIUZ-Heft) die unterschiedlichen Moglichkeiten des endocytotischen Stofftransports dargestellt worden sind, sollen im zweiten Teil Gemeinsamkeiten und Unterschiede des Lysosomalen Abbauwegs bei Einzellern und Vielzellern naher behandelt werden.

The morphology of the principal sections of the gastrointestinal system of two Antarctic seals with different dietary habits, namely, the Weddell seal (Leptonychotes weddellii) and the crabeater seal (Lobodon carcinophagus), has been investigated. Histologically examined by light microscopy, the tissue layers of the gastrointestinal tract of both seals are almost identical to those observed in most other mammals and no major differences in principle organization could be found between the two seal species. The ultrastructure of the gastric and intestinal epithelial cells has been examined and is also closely comparable to that of these cells in other mammals; however, Paneth cells have not been found in our material. In general, therefore, adaptations of the gastrointestinal tract to the aquatic environment or the diet are not obvious at the morphological levels of organization studied. Histochemical differences are found between the two closely related species; mucins of the surface epithelium in the stomach of Weddell seals are highly sulfated, while those in the crabeater seal are not. Mucous neck cells in Weddell seals contain acid mucosubstances, while those of crabeater seals contain neutral ones. Goblet cells in the small and large intestine in Weddell seals contain both neutral and acid mucosubstances. Both mucin types are detected in the crabeater seal; however, the mucins of the colon in the crabeater seal are more highly sulfated than those in the Weddell seal. The ratio of globet cells to enterocytes in the large intestine of crabeater seals is higher than that in Weddell seals. © 1995 Wiley-Liss, Inc.

2,4-Diamino-N(4),6-diarylpyrimidines were identified as potent, isoform specific inhibitors of lysophosphatidic acid acyltransferase-beta (LPAAT-beta). Active inhibitors also blocked proliferation of tumor cell lines in vitro. The effect of 2j in an in vivo tumor model was investigated.

Der thermische Zerfall von Dicumylhyponitrit (1a) ist eine Reaktion erster Ordnung mit einer Aktivierungsenthalpie von 27.3 keal/Mol und einer Aktivierungsentropie von 8.5 cal/Mol·Grad in Isooctan. Die Radikalausbeute fur 1a betragt 84%, fur Di-tert.-butylhyponitrit 92%. Die Zerfallskonstanten substituierter Dicumylhyponitrite gehorchen bei Verwendung der σ+-Werte der Hammett-Beziehung mit σ=+ +0.34. Kinetic and Radical Efficiency for the Decomposition of Tertiary Hyponitrites The thermal decomposition of dicumylhyponitrite (1a) is a first order reaction with an activation enthalpy of 27.3 kcal/mole and an activation entropy of 8.5 e. u. in isooctane. The efficiency of radical formation is 84% for 1a but 92% for di-tert-butylhyponitrite. The rate constants for the decomposition of substituted dicumylhyponitrites follow the Hammett equation with σ=++0.34 by applying σ+ values.

Dicumylhyponitrit (1a), substituierte Dicumylhyponitrite (1b1f) (p-Br, p-Cl, p-CH3, m-CH3, p-CH3O), Bis-[1.1-diphenyl-athyl]-hyponitrit (1h) und Bis-[1.1-dimethyl-pentyl]-hyponitrit (1g) wurden dargestellt. Die tertiaren Hyponitrite zerfallen bereits rasch bei-40 in Stickstoff und freie Alkoxyradikale, die dann zu den entsprechenden Alkoholen und Ketonen weiter reagieren. Die relativen Reaktivitaten von tert.-Butyloxy-und Cumyloxyradikalen hinsichtlich Wasserstoffabstraktion und β-Spaltung wurden fur verschiedene Losungsmittel bestimmt; Cumyloxyradikale neigen starker zur β-Spaltung als tert-Butyloxyradikale. Die freien Alkoxyradikale konnen Polymerisations- und Autoxydationsreaktionen initiieren und mit stabilen freien Radikalen abgefangen werden. Synthesis and Decomposition of Tertiary Hyponitrites Dicumylhyponitrite (1a), substituted dicumylhyponitrites (1b1f) (p-Br, p-Cl, p-CH3, m-CH3, p-CH3O), bis-(1.1-diphenylethyl)hyponitrite (1h) and bis-(1.1-dimethylpentyl)hyponitrite (1g) were synthesized. The tertiary hyponitrites decompose thermally already fast at 40°C into nitrogen and free tertiary alkoxy radicals which then react further to the corresponding alcohols and ketones. The relative reactivities of tert-butoxy and cumyloxy radicals in respect to hydrogenabstraction and β-scission were determined in various solvents; cumyloxy radicals tend much more to β-scission than the tert-butoxy radicals. The generated free alkoxy radicals are able to initiate polymerization and autoxidation reactions and can be trapped by stable radicals.

(1 R ,2 S )- and (1 S ,2 R )-Acetoxycycloalkanedimethanols 1-6 of high enantiomeric purities were prepared by enzymatic hydrolysis and esterification respectively in presence of lipase from porcine pancreas (PPL) and Pseudomonas sp . (SAM-II).

The complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 47. DOI:10.1002/anie.198300470

Das vollstandige Manuskript dieser Zuschrift erscheint in: Angew. Chem. Suppl. 1983, 47. DOI: 10.1002/ange.198300470