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91.
Design of a novel MRI compatible manipulator for image guided prostate interventions 总被引:7,自引:0,他引:7
Krieger A Susil RC Ménard C Coleman JA Fichtinger G Atalar E Whitcomb LL 《IEEE transactions on bio-medical engineering》2005,52(2):306-313
This paper reports a novel remotely actuated manipulator for access to prostate tissue under magnetic resonance imaging guidance (APT-MRI) device, designed for use in a standard high-field MRI scanner. The device provides three-dimensional MRI guided needle placement with millimeter accuracy under physician control. Procedures enabled by this device include MRI guided needle biopsy, fiducial marker placements, and therapy delivery. Its compact size allows for use in both standard cylindrical and open configuration MRI scanners. Preliminary in vivo canine experiments and first clinical trials are reported. 相似文献
92.
The problem of bending a thin plate is solved by the finite element method. Using a differential equation of the plate element equilibrium determines the potential energy by contour values of displacements and their first derivatives. In the equilibrium state they have to be such that the potential energy reaches its minimum. The suggested calculation algorithm enables the use of multiangular elements of arbitrary shape instead of integration in the area of this element in which curvilinear integrals appear along the element contour. Elaborated also is the program for calculation by computer and verified usability of the method for various elements based on the example of the square plate. 相似文献
93.
94.
Peter Greil Ralf Nitzsche Hannelore Friedrich Waldemar Hermel 《Journal of the European Ceramic Society》1991,7(6):353-359
The oxygen content associated to the surface of silicon nitride powder particles was characterized using a method which is based on the measurement of the specific surface area and the isoelectric point in aqueous solution. From the dissociation model of hydrolyzed surface groups a linear dependence between the fraction of silanol groups (SiOH) and the pH of the isoelectric point is predicted, which was confirmed by electrophoretic measurements of various commercial silicon nitride powders. The proposed method provides rapid information on the particle surface composition, which is of particular relevance for colloidal processing of silicon nitride powders. 相似文献
95.
Waldemar A. Trzciński Józef Paszula Sebastian Grys 《Propellants, Explosives, Pyrotechnics》2010,35(2):85-92
Investigation of detonation parameters, blast wave characteristics and quasi‐static pressures (QSPs) for the mixtures of nitromethane and particles of an aluminium and magnesium (Al3Mg4) alloy was carried out. The mixtures of gelled nitromethane containing 15–60 wt.‐% Al Mg alloy were tested. Detonation velocity and Gurney energy were determined. Parameters of blast waves produced by charges of the investigated explosives were measured. QSP measurements were conducted in a steel chamber of 0.15 m3 volume filled with air. Thermochemical and gasdynamical calculations were also performed. The degree of combustion of the metallic addition with the gaseous products during detonation and expansion is discussed. 相似文献
96.
Tomasz P. Maniecki Paweł Mierczynski Waldemar Maniukiewicz Katarzyna Bawolak Danuta Gebauer Wojciech K. Jozwiak 《Catalysis Letters》2009,130(3-4):481-488
The influence of silver and gold addition on the activity and physicochemical properties of supported Cu/CrAl3O6 catalysts was the aim of this work. The reduction of CrAl3O6 support shows only one reduction stage attributed to Cr (VI) species reduction originating from previously oxidized binary oxide. Supported copper catalysts reduce in one or two stages depending on copper concentration representing the reduction of copper oxide—CuO, copper oxide chemically combined with Cr(III) oxide as copper chromite—CuCr2O4 and Cr(VI) species originating from surface chromate ions CrO4 2?. Additionally, the introduction of silver into supported copper catalysts Cu/CrAl3O6 can led to the appearance of silver chromate phase. XRD investigations of support CrAl3O6 alone, supported copper and gold and silver promoted copper supported catalysts calcined at 400, 700 and 900 °C indicated the presence of highly amorphous alumina γ-Al2O3 like structure network in which some of cationic locations of aluminum were occupied by chromium atoms and small quantities of α-Cr2O3 phase. Additionally, for copper, silver–copper, and gold–copper supported catalysts the following oxide phases were distinguished: monometallic oxides CuO, Ag2O, binary oxides CuAl2O4, Ag2CrO4, CuCr2O4 and even ternary oxide CuAlCrO4. In the case of gold promoted copper supported catalysts metallic gold phase was detected. Activity tests carried out for these catalysts show that the most active was 20 wt.% Cu/CrAl3O6 catalyst. Promotion of copper catalysts by silver improves the activity in methanol synthesis, what can be assigned to silver chromate formation. The analogical gold chromate like formation was not confirmed. 相似文献
97.
Thermal stability of expanded perlite modified by mullite 总被引:1,自引:0,他引:1
Results of the thermal stability of expanded perlite modified by mullite are presented. Mullite was formed from alumino-silicate gel by sol–gel method. This method allowed us to obtain very homogenous and reactive gel and phase formation of mullite took place at relatively low temperatures. Expanded perlite modified with alumino-silicate gel after firing above the temperature of mullite formation had better thermal stability and durability during heating. The thermal stability of this material was examined up to 1400 °C. 相似文献
98.
Jochen Krieger 《电子设计应用》2008,(6)
许多便携式应用需要超过8kV的ESD保护,同时将电容保持在5pF以下。Z二极管能够单独满足这一要求,但当与开关或结型二极管等低电容PN二极管相结合时,它们可同时满足该应用的以下两种要求:低电容,以及高ESD和 相似文献
99.
Multidimensional Waveform Encoding: A New Digital Beamforming Technique for Synthetic Aperture Radar Remote Sensing 总被引:6,自引:0,他引:6
Krieger G. Gebert N. Moreira A. 《Geoscience and Remote Sensing, IEEE Transactions on》2008,46(1):31-46
This paper introduces the innovative concept of multidimensional waveform encoding for spaceborne synthetic aperture radar (SAR). The combination of this technique with digital beamforming on receive enables a new generation of SAR systems with improved performance and flexible imaging capabilities. Examples are high-resolution wide-swath radar imaging with compact antennas, enhanced sensitivity for applications like alongtrack interferometry and moving object indication, and the implementation of hybrid SAR imaging modes that are well suited to satisfy hitherto incompatible user requirements. Implementation-specific issues are discussed and performance examples demonstrate the potential of the new technique for different remote sensing applications. 相似文献
100.
Jeferson L. da Silva Raul C. Maranhão Michelle S.M. Silva Rodrigo G. Dias Fatima R. Freitas Wladimir Bolani José R. Lemos Junior Cleber R. Alves Patrícia A. Oliveira Guilherme B. Alves Edilamar M. Oliveira Carlos Eduardo Negrao José Eduardo Krieger Alexandre C. Pereira Gisele A. Silva José P. Souza Carmen G.C. Vinagre 《Lipids》2019,54(6-7):381-388
Exercise training not only improves the plasma lipid profile but also reduces risk of developing coronary heart disease. We investigate whether plasma lipids and high density lipoprotein (HDL) metabolism are affected by aerobic training and whether the high-density lipoprotein cholesterol (HDL-C) levels at baseline influence exercise-induced changes in HDL. Seventy-one male sedentary volunteers were evaluated and allocated in two subgroups, according to the HLD-C levels (< or >40 mg/dL). Participants underwent an 18-week aerobic training period. Blood was sampled before and after training for biochemical analysis. Plasma lipids, apolipoproteins, HDL diameter, and VO2 peak were determined. Lipid transfers to HDL were determined in vitro by incubating plasma samples with a donor lipid artificial nanoemulsion. After the 18-week period of aerobic training, the VO2 peak increased, while the mean body mass index (BMI) decreased. HDL-C concentration was higher after the training period, but low-density lipoprotein cholesterol (LDL-C) and non-HDL-C did not change. The transfer of esterified cholesterol and phospholipids was greater after exercise training, but the triacylglycerol and unesterified cholesterol transfers were unchanged. The HDL particle diameter increased after aerobic training in all participants. When the participants were separated in low-HDL and normal-HDL groups, the postaerobic exercise increment in HDL-C was higher in the low-HDL group, while the transfer of esterified cholesterol was lower. In conclusion, aerobic exercise training increases the lipid transfers to HDL, as measured by an in vitro method, which possibly contributes to the classical elevation of the HDL-C associated with training. 相似文献