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51.
52.
Matrix metalloproteinases (MMPs) are zinc‐ and calcium‐dependent endopeptidases. Representing a subfamily of the metzincin superfamily, MMPs are involved in the proteolytic degradation of components of the extracellular matrix. Unregulated MMP expression, MMP dysregulation and locally increased MMP activity are common features of various diseases, such as cancer, atherosclerosis, stroke, arthritis, and others. Therefore, activated MMPs are suitable biological targets for the specific visualization of such pathologies, in particular by using radiolabeled MMP inhibitors (MMPIs). The aim of this work was to develop a radiofluorinated molecular probe for noninvasive in vivo imaging for the detection of up‐regulated levels of activated MMPs in the living organism. Fluorinated MMPIs ( 26 , 31 and 38 ) based on the pyrimidine‐2,4,6‐trione lead structure RO 28‐2653 ( 1 ) were synthesized, and their MMP inhibition potency was evaluated in vitro. The radiosynthesis and the in vivo biodistribution of the first 18F‐labeled prototype, MMP‐targeted tracer [18F] 26 , suitable for molecular imaging by means of positron emission tomography (PET) were realized.  相似文献   
53.
The demand for instruments that are suitable for the separation of fine particles and biological cells is steadily increasing. Various innovative particles have already implemented in bulk products and many others are close to commercial availability. Tubular bowl centrifuges offer high centrifugal forces at reasonable throughputs. There is a high potential for the optimisation of existing processes and in the design of new tubular centrifuges especially for the separation of nanoscale materials. The separation of fine particulates and biological cells in a semibatch tubular bowl centrifuge at high rotational speeds is described in this work. Furthermore, the influence of the sediment on the process outcome and possibilities to enhance the separation efficiency were investigated. A boundary layer flow was indirectly detected. Structures inside the rotor of the centrifuge cause defined liquid flow patterns, which influence the separation efficiency. A comparison of the separation behaviour with an unimpaired flow and the redirected flow yielded conclusions about the actual flow patterns.  相似文献   
54.
    
Early fallout is defined as the fallback to the earth’s surface of radioactive particles shortly after a nuclear detonation (often arbitrarily defined within 24 h). At the difference of wide spreading global fallout,early fallout mainly consists of larger particles that are often visible. The initial mixture is rich in short- and very short-lived radionuclides associated with a very high initial activity that decreases rapidly (in 7 h,the dose rate is reduced by 90%). The main danger of early fallout results from external irradiation by highly penetrating gamma-radiation that may cause acute radiation sickness. Only in the case of the thyroid,internal irradiation by the incorporation of radioiodine may prevail. The bombings of Hiroshima and Nagasaki are examples of airbursts with many fatalities by prompt effects (blast,burns,and initial ionizing radiations),but they produced little fallout. The nuclear test code-named Castle Bravo on the Marshall Islands (1954) did not have casualties by its blast,thermal or initial radiation effects,but the inhabitants of the nearby islands and the crew of a Japanese fisherboat (Lucky Dragon) were affected by large amounts of fallout. For the inhabitants of the Rongelap Atoll,the average dose from external irradiation was assessed at 1.6 Gy. From a clinical point of view,based on hematological data using the METREPOL classification system,the acute radiation syndrome can be categorized as mild (H1). Blood transfusions were not required,and antibiotics were not administered for prophylaxis or therapy of infections related to irradiation. The equivalent dose received by the thyroid resulted mainly from internal irradiation with 7.6 Gy. The major late effects were thyroid abnormalities,including thyroid failure,nodules,and malignant tumors. The 23 Japanese crewmen seem to have been irradiated by higher doses (2.9 Gy). Compared to the hematological data of the Rongelap victims,the evolution pattern over time is quite similar. Still,the absolute values of the cell counts are lower,and on average,the acute radiation syndrome can be categorized as rather moderate (H2). Considering the individual cases,data show a large interindividual variability,and the clinical severity category ranges from “no alterations” (H0) to severe (H3). Victims were treated with repeated blood transfusions and antibiotics. Several of them developed jaundice,and one of them died six months after the incident showing symptoms compatible with subacute liver failure. A radiochemical organ analysis revealed that only the bones were clearly contaminated with fission products. In the 1990s,many surviving crewmen were diagnosed with hepatitis C,incurred probably from blood transfusions that were often contaminated at the time,and died from hepatocellular carcinomas. Thyroid dysfunctions were not reported. The Castle Bravo case permits to study the health hazards resulting from early fallout independently from the prompt effects of a nuclear detonation. The prevailing external irradiation was confirmed,except for the thyroid with a higher dose resulting from radioiodine incorporation mainly caused by ingestion. As shown for the Japanese fishermen,the risks incurred by medical treatments must be carefully weighed against the benefits of the therapeutic intervention. The cause of death of the only short-term fatality is not fully elucidated,but is consistent with liver failure due to transfusion hepatitis rather than radiation effects.https://doi.org/10.1051/radiopro/2022030  相似文献   
55.
Calculation of the flow pattern in a new small homogenising valve design (Stansted, U.K.), able to reach operating pressure as high as , was investigated in the first part of this paper using a Computational Fluid Dynamics method. Numerical simulation results are used in the present paper to better understand the emulsification process in the Stansted high-pressure homogeniser.Deformation of drops is supposed to occur in the intense elongational flow caused by the restriction between the piston and the seat of the valve. Deformation may be mainly followed by drop disruption in the narrow valve gap. Break-up probably also occurred in the highly turbulent region, located just at the exit of the gap, and underlined by the numerical investigation. Cavitation and the rate of recoalescence, first assumed from numerical results, are determined thank to experimental methods. Intensities of both phenomena strongly increase with homogenising pressure. Final droplet size of model oil-in-water emulsions is then the result of equilibrium between droplet break-up and recoalescence, which strongly depends on operating pressure.  相似文献   
56.
57.
Abstract

Oxide ferroelectric thin films for frequency-tunable microwave devices, in which the dielectric constant of the non-linear dielectric is varied by application of electric fields, have been deposited using PLD. We have fabricated single phase epitaxial Ba0.6Sr0.4TiO3 and KTaO3 thin film capacitors for applications at 300K and 77K, respectively. Single phase KTaO3 films were obtained only with excess potassium source in the target along with KTaO3 perovskite phase. The films have been characterized for structure and morphology by X-ray diffraction and AFM. The dielectric properties were measured in the low frequency range from 100 kHz to 10 MHz, using interdigitated capacitors. Low loss tangents (0.002 at 300K) were observed for highly oriented Ba0.6Sr0.4TiO3 films. The importance of low losses for various devices is discussed and the dielectric constants, loss tangents and tunability of these films are reported in this paper.  相似文献   
58.
世界上第一条新型气体绝缘高压输电线路   总被引:2,自引:0,他引:2  
介绍瑞士日内瓦机场的气体绝缘输电线路(GIL)工程,涉及工程的系统设计、技术指标和施工方法等。阐述GIL具有运营成本低、安全性和可靠性高、电磁场强度低和无老化等优越性。  相似文献   
59.
The Time-Triggered Architecture, as architecture for safety-critical real-time applications, incorporates fault-tolerance mechanisms to ensure correct system operation despite failures. The primary fault hypothesis of the TTA claims to tolerate either the arbitrary failure of any one of its nodes or the passively arbitrary failure of any one of its communication channels. To cover these failure modes, active redundancy techniques are used, which basically means that nodes and channels are physically replicated. The primary fault hypothesis, is, however, not strong enough for certain applications that have to tolerate transient upsets of multiple, possibly all, components in the system. Such a transient upset of the system may break up the synchrony of the nodes and leave disjoined sets of nodes synchronized to each other while the overall synchronization is lost. Although the TTA provides a clique avoidance algorithm that is able to correct a wide class of such multiple transient failures, a stronger algorithm is needed for full coverage. In this paper we discuss a secondary fault hypothesis for the TTA that addresses the transient upset of multiple components and present a new clique resolving algorithm based on the TTA's integrated diagnosis and startup service. This paper is a revised version of Steiner et al. (2003). This work has been funded by the European Project DECOS (Project number: IST-511764). Michael Paulitsch is currently affiliated with Honeywell International.  相似文献   
60.
Online Social Networks (OSNs) wie MySpace, Facebook und StudiVZ sind inzwischen zu einem wichtigen Bestandteil des allt?glichen Miteinanders geworden. Entgegen der weit verbreiteten Meinung vermitteln Profile in OSNs kein verf?lschtes, selbstidealisiertes, sondern ein sehr genaues Bild von der Pers?nlichkeit der Profilbesitzer. Dies k?nnte ein wichtiger Grund für die Beliebtheit sozialer Netzwerke sein: Sie bieten eine Plattform für reale soziale Interaktionen und erm?glichen den Ausdruck der eigenen Pers?nlichkeit. Implikationen für den Datenschutz in OSNs werden diskutiert.  相似文献   
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