Beiträge zur röntgenradioskopischen Visualisierung und Charakterisierung von Erstarrungsvorgängen und zweiphasigen Strömungsphänomenen in metallischen Schmelzen

Röntgenradioskopische Bildgebungsverfahren ermöglichen es, ein besseres Verständnis der zweiphasigen Strömungsphänomene und der Prozesse der Mikrostrukturentstehung während der Erstarrung in Metallschmelzen intuitiv zu gewinnen, da diese Verfahren die innere Gestalt der sonst undurchsichtigen Flüssigkeiten abbilden. In der vorliegenden Arbeit wurden dazu Untersuchungen zu zwei unterschiedlichen Teilaufgaben durchgeführt. Zum einen wurde die Dichteverteilung in dünnen Erstarrungsproben in Echtzeit und in-situ mit räumlichen Auflösungen von wenigen Mikrometern untersucht, um den Einfluss natürlicher und erzwungener Schmelzenströmungen auf die Erstarrung einer binären Gallium-Indium-Metalllegierung experimentell nachzuweisen. Zum anderen wurden Gasblasenströmungen in nichttransparenten Metallschmelzen nicht-invasiv und in-situ visualisiert und charakterisiert, um Kenntnis der Eigenschaften und der Bewegung von Argon-Einzelblasen und Blasenketten in flüssigem Gallium-Indium-Zinn ohne und unter dem Einfluss eines externen magnetischen Feldes zu erlangen. Diese experimentellen Untersuchungen wurden mit einem Mikrofokus-Röntgenbildgebungssystem durchgeführt. Die Implementation angepasster Bildverarbeitungs-algorithmen ermöglichte die präzise quantitative Vermessung der dendritischen Strukturparameter und der Wachstumsgeschwindigkeiten. Die Strömungsgeschwindigkeiten in der Schmelze vor der Erstarrungsfront wurden durch Berechnung des optischen Flusses in den Röntgenbildsequenzen vermessen. Thermosolutale Konvektionsbewegungen und der Einfluss magnetisch angetriebener erzwungener Schmelzenströmung auf die Gefügeentstehung konnten durch die Röntgenvisualisierung nachgewiesen werden. Die lokale Akkumulation angereicherter Schmelze, das Aufschmelzen von Dendritenarmen und das Entstehen von Entmischungskanälen im Zweiphasengebiet hinter der Erstarrungsfront wurden unmittelbar beobachtet. Für die Untersuchung des Verhaltens von Gasblasen in einer schmalen Flüssigmetall-Blasensäule wurde das Röntgenbildgebungssystem modifiziert. Das ermöglichte die Vermessung der Gasblasengrößen, der Trajektorien und der Geschwindigkeiten zur Charakterisierung der Blasenströmungen. Die Abhängigkeit der Gasblasengrößen von der Benetzung der Mündungsöffnung wurde gezeigt. Vergleichsexperimente im Gas-Wasser-System verdeutlichten die signifikanten Unterschiede der zweiphasigen Gas-Flüssigmetall-Strömungen.X-ray radioscopic imaging methods enables one to intuitively gain a better understanding of the two-phase flow phenomena and the processes of microstructure formation during solidification in molten metals, as these methods depict the internal shape of the otherwise opaque liquids. In the present work, investigations were carried out on two different subtasks. On one hand, the density distribution in thin solidification samples was investigated in real time and in-situ with a spatial resolution of a few micrometers in order to demonstrate experimentally the influence of natural and forced melt flow on the solidification of a binary gallium-indium (GaIn) metal alloy. On the other hand, gas bubble flows in non-transparent metal melts were visualized and characterized non-invasively and in-situ in order to gain knowledge of the properties and the movement of individual argon bubbles and bubble chains in liquid gallium-indium-tin (GaInSn) without and under the influence of an external magnetic field. These experimental studies were performed with a microfocus X-ray imaging system. The implementation of adapted image processing algorithms enabled the precise quantitative measurement of the dendritic structure parameters and the growth rates. The flow velocities in the melt in front of the solidification front were measured by calculating the optical flow in the X-ray image sequences. Thermosolutal convection and the influence of magnetically driven forced melt flow on the formation of the structure could be demonstrated by the X-ray visualization. The local accumulation of enriched melt, the melting of dendrite arms and the emergence of segregation channels in the two-phase area behind the solidification front were observed directly. The X-ray imaging system was modified to study the behavior of gas bubbles in a narrow column of liquid metal bubbles. This made it possible to measure the gas bubble sizes, the trajectories and the velocities to characterize the bubble flows. The dependence of the gas bubble sizes on the wetting of the nozzle opening was shown. Comparative experiments in the gas-water system clearly revealed the significant differences in two-phase gas-liquid metal flows

Экономический замкнутый цикл как основа экологической и социально-экономической стабильности России

Экономический замкнутый цикл позволяет взаимодействовать различным отраслям экономики. Безусловно, это приводит к улучшению экологической ситуации и социально-экономического благополучия в России. В статье представлена оценка отдельных замкнутых циклов разных отраслей (сельское хозяйство, машиностроение, пищевая и перерабатывающая отрасли). Предложено и обосновано их включение в единый экономический замкнутый цикл с целью повторного восстановления отходов

Stimulation of leukotriene synthesis in intact polymorphonuclear cells by the 5-lipoxygenase inhibitor 3-oxo-tirucallic acid.

ABSTRACT Commercially available extracts from Boswellia serrata resin used as anti-inflammatory drugs or phytonutrients show paradoxical concentration-dependent potentiating and inhibitory actions on 5-lipoxygenase (5-LO) product synthesis in stimulated PMNs. In our attempt to characterize the stimulating constituents, we identified the tetracyclic triterpene 3-oxo-tirucallic acid (3-oxo-TA), which, in the range from 2.5 to 15 M, enhanced 5-LO product formation in ionophore-challenged polymorphonuclear cells (PMNs) (e.g., from 1981 Ϯ 177 to 3042 Ϯ 208 pmol at 10 M 3-oxo-TA), and initiated Ca 2ϩ mobilization, MEK-1/2 phosphorylation, 5-LO translocation, and 5-LO product formation in resting cells (534 Ϯ 394 pmol/ 5 ϫ 10 6 PMNs). In cell-free 5-LO assays, 3-oxo-TA acted only inhibitory (IC 50 value of about 3 M), demonstrating the pivotal role of intact cell structure for its activating property. In 3-oxo-TA-challenged PMNs, the mitogen-activated protein kinase kinase (MEK)-1/2 inhibitor PD098059 abolished 5-LO product formation, along with inhibition of MEK-1/2 phosphorylation and 5-LO translocation. The 3-acetoxy derivative of 3-oxo-TA acted like 3-oxo-TA in intact PMNs, whereas 3-hydroxy-TA barely stimulated MEK phosphorylation in resting cells and showed only inhibition on ionophore-induced 5-LO product synthesis. Steroid-type tetracycles neither induced 5-LO activation nor had enhancing or inhibitory effects. In summary, defined natural tetracyclic triterpenes, which act as inhibitors of the 5-LO in the cell-free assay, initiate 5-LO activation by a MEK-inhibitor sensitive mechanism and potentiate stimulated product synthesis in intact cells. Because TAs contribute significantly to the overall biological effects of B. serrata resin extracts, special precaution for standardization is recommended when using B. serrata preparations as drugs or dietary supplements. 5-Lipoxygenase (5-LO; EC 1.13.11.34) catalyzes the first two steps in the biosynthesis of leukotrienes and 5(S)-HETE from arachidonic acid. Leukotrienes and 5-oxo-eicosa-tetraenoic acid, a final metabolite from 5(S)-HETE The enzymatic activity of 5-LO, as well as its binding to other macromolecules, is regulated in a highly complex manner (for concise reviews on many aspects of 5-LO, products, and receptors, se

Mobile Asteroid Surface Scout (MASCOT) - Design, Development and Delivery of a Small Asteroid Lander Aboard Hayabusa2

MASCOT is a small asteroid lander launched on December 3rd, 2014, aboard the Japanese HAYABUSA2 asteroid sample-return mission towards the 980 m diameter C-type near-Earth asteroid (162173) 1999 JU3. MASCOT carries four full-scale asteroid science instruments and an uprighting and relocation device within a shoebox-sized 10 kg spacecraft; a complete lander comparable in mass and volume to a medium-sized science instrument on interplanetary missions. Asteroid surface science will be obtained by: MicrOmega, a hyperspectral near- to mid-infrared soil microscope provided by IAS; MASCAM, a wide-angle Si CMOS camera with multicolour LED illumination unit; MARA, a multichannel thermal infrared surface radiometer; the magnetometer, MASMAG, provided by the Technical University of Braunschweig. Further information on the conditions at or near the lander‘s surfaces is generated as a byproduct of attitude sensors and other system sensors. MASCOT uses a highly integrated, ultra-lightweight truss-frame structure made from a CFRP-foam sandwich. It has three internal mechanisms: a preload release mechanism, to release the structural preload applied for launch across the separation mechanism interface; a separation mechanism, to realize the ejection of MASCOT from the semi-recessed stowed position within HAYABUSA2; and the mobility mechanism, for uprighting and hopping. MASCOT uses semi-passive thermal control with Multi-Layer Insulation, two heatpipes and a radiator for heat rejection during operational phases, and heaters for thermal control of the battery and the main electronics during cruise. MASCOT is powered by a primary battery during its on-asteroid operational phase, but supplied by HAYABUSA2 during cruise for check-out and calibration operations as well as thermal control. All housekeeping and scientific data is transmitted to Earth via a relay link with the HAYABUSA2 main-spacecraft, also during cruise operations. The link uses redundant omnidirectional UHF-Band transceivers and patch antennae on the lander. The MASCOT On-Board Computer is a redundant system providing data storage, instrument interfacing, command and data handling, as well as autonomous surface operation functions. Knowledge of the lander’s attitude on the asteroid is key to the success of its uprighting and hopping function. The attitude is determined by a threefold set of sensors: optical distance sensors, photo electric cells and thermal sensors. A range of experimental sensors is also carried. MASCOT was build by the German Aerospace Center, DLR, with contributions from the French space agency, CNES. The system design, science instruments, and operational concept of MASCOT will be presented, with sidenotes on the development of the mission and its integration with HAYABUSA2

Outcome of coronary plaque burden: a 10-year follow-up of aggressive medical management

<p>Abstract</p> <p>Background</p> <p>The effect of aggressive medical therapy on quantitative coronary plaque burden is not generally known, especially in ethnic Chinese.</p> <p>Aims</p> <p>We reasoned that Cardiac CT could conveniently quantify early coronary atherosclerosis in our patient population, and hypothesized that serial observation could differentiate the efficacy of aggressive medical therapy regarding progression and regression of the atherosclerotic process, as well as evaluating the additional impact of life-style modification and the relative effects of the application of statin therapy.</p> <p>Methods</p> <p>We employed a standardized Cardiac CT protocol to serially scan 113 westernized Hong Kong Chinese individuals (64 men and 49 women) with Chest Pain and positive coronary risk factors. In all cases included for this serial investigation, subsequent evaluation showed no significantly-obstructive coronary disease by functional studies and angiography. After stringent risk factor modification, including aggressive statin therapy to achieve LDL-cholesterol lowering conforming to N.C.E.P. ATP III guidelines, serial CT scans were performed 1-12 years apart for changes in coronary artery calcification (CAC), using the Agatston Score (AS) for quantification.</p> <p>Results</p> <p>At baseline, the mean AS was 1413.6 for males (mean age 54.4 years) and 2293.3 for females (mean age 62.4 years). The average increase of AS in the entire study population was 24% per year, contrasting with 16.4% per year on strict risk factor modification plus statin therapy, as opposed to 33.2% per year for historical control patients (p < 0.001). Additionally, 20.4% of the 113 patients demonstrated decreasing calcium scores. Medical therapy also yielded a remarkably low adverse event rate during the follow-up period --- 2 deaths, 2 strokes and only 1 case requiring PCI.</p> <p>Conclusions</p> <p>This study revealed that aggressive medical therapy can positively influence coronary plaque aiding in serial regression of calcium scores.</p

Humanized Mice Recapitulate Key Features of HIV-1 Infection: A Novel Concept Using Long-Acting Anti-Retroviral Drugs for Treating HIV-1

BACKGROUND: Humanized mice generate a lymphoid system of human origin subsequent to transplantation of human CD34+ cells and thus are highly susceptible to HIV infection. Here we examined the efficacy of antiretroviral treatment (ART) when added to food pellets, and of long-acting (LA) antiretroviral compounds, either as monotherapy or in combination. These studies shall be inspiring for establishing a gold standard of ART, which is easy to administer and well supported by the mice, and for subsequent studies such as latency. Furthermore, they should disclose whether viral breakthrough and emergence of resistance occurs similar as in HIV-infected patients when ART is insufficient. METHODS/PRINCIPAL FINDINGS: NOD/shi-scid/γ(c)null (NOG) mice were used in all experimentations. We first performed pharmacokinetic studies of the drugs used, either added to food pellets (AZT, TDF, 3TC, RTV) or in a LA formulation that permitted once weekly subcutaneous administration (TMC278: non-nucleoside reverse transcriptase inhibitor, TMC181: protease inhibitor). A combination of 3TC, TDF and TMC278-LA or 3TC, TDF, TMC278-LA and TMC181-LA suppressed the viral load to undetectable levels in 15/19 (79%) and 14/14 (100%) mice, respectively. In successfully treated mice, subsequent monotherapy with TMC278-LA resulted in viral breakthrough; in contrast, the two LA compounds together prevented viral breakthrough. Resistance mutations matched the mutations most commonly observed in HIV patients failing therapy. Importantly, viral rebound after interruption of ART, presence of HIV DNA in successfully treated mice and in vitro reactivation of early HIV transcripts point to an existing latent HIV reservoir. CONCLUSIONS/SIGNIFICANCE: This report is a unique description of multiple aspects of HIV infection in humanized mice that comprised efficacy testing of various treatment regimens, including LA compounds, resistance mutation analysis as well as viral rebound after treatment interruption. Humanized mice will be highly valuable for exploring the antiviral potency of new compounds or compounds targeting the latent HIV reservoir

Common Genetic Variation And Age at Onset Of Anorexia Nervosa

Background Genetics and biology may influence the age at onset of anorexia nervosa (AN). The aims of this study were to determine whether common genetic variation contributes to AN age at onset and to investigate the genetic associations between age at onset of AN and age at menarche. Methods A secondary analysis of the Psychiatric Genomics Consortium genome-wide association study (GWAS) of AN was performed which included 9,335 cases and 31,981 screened controls, all from European ancestries. We conducted GWASs of age at onset, early-onset AN (< 13 years), and typical-onset AN, and genetic correlation, genetic risk score, and Mendelian randomization analyses. Results Two loci were genome-wide significant in the typical-onset AN GWAS. Heritability estimates (SNP-h2) were 0.01-0.04 for age at onset, 0.16-0.25 for early-onset AN, and 0.17-0.25 for typical-onset AN. Early- and typical-onset AN showed distinct genetic correlation patterns with putative risk factors for AN. Specifically, early-onset AN was significantly genetically correlated with younger age at menarche, and typical-onset AN was significantly negatively genetically correlated with anthropometric traits. Genetic risk scores for age at onset and early-onset AN estimated from independent GWASs significantly predicted age at onset. Mendelian randomization analysis suggested a causal link between younger age at menarche and early-onset AN. Conclusions Our results provide evidence consistent with a common variant genetic basis for age at onset and implicate biological pathways regulating menarche and reproduction.Peer reviewe

Exercise therapy in Type 2 diabetes

Structured exercise is considered an important cornerstone to achieve good glycemic control and improve cardiovascular risk profile in Type 2 diabetes. Current clinical guidelines acknowledge the therapeutic strength of exercise intervention. This paper reviews the wide pathophysiological problems associated with Type 2 diabetes and discusses the benefits of exercise therapy on phenotype characteristics, glycemic control and cardiovascular risk profile in Type 2 diabetes patients. Based on the currently available literature, it is concluded that Type 2 diabetes patients should be stimulated to participate in specifically designed exercise intervention programs. More attention should be paid to cardiovascular and musculoskeletal deconditioning as well as motivational factors to improve long-term treatment adherence and clinical efficacy. More clinical research is warranted to establish the efficacy of exercise intervention in a more differentiated approach for Type 2 diabetes subpopulations within different stages of the disease and various levels of co-morbidity