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61.
Park Y Luce AC Whitaker RD Amin B Cabodi M Nap RJ Szleifer I Cleveland RO Nagy JO Wong JY 《Langmuir : the ACS journal of surfaces and colloids》2012,28(8):3766-3772
Monodisperse gas microbubbles, encapsulated with a shell of photopolymerizable diacetylene lipids and phospholipids, were produced by microfluidic flow focusing, for use as ultrasound contrast agents. The stability of the polymerized shell microbubbles against both aggregation and gas dissolution under physiological conditions was studied. Polyethylene glycol (PEG) 5000, which was attached to the diacetylene lipids, was predicted by molecular theory to provide more steric hindrance against aggregation than PEG 2000, and this was confirmed experimentally. The polymerized shell microbubbles were found to have higher shell-resistance than nonpolymerizable shell microbubbles and commercially available microbubbles (Vevo MicroMarker). The acoustic stability under 7.5 MHz ultrasound insonation was significantly greater than that for the two comparison microbubbles. The acoustic stability was tunable by varying the amount of diacetylene lipid. Thus, our polymerized shell microbubbles are a promising platform for ultrasound contrast agents. 相似文献
62.
E Debroye G Dehaen SV Eliseeva S Laurent L Vander Elst RN Muller K Binnemans TN Parac-Vogt 《Dalton transactions (Cambridge, England : 2003)》2012,41(35):10549-10556
A ditopic DTPA monoamide derivative containing an 8-hydroxyquinoline moiety was synthesized and the corresponding gadolinium(iii) complex ([Gd(H5)(H(2)O)](-)) was prepared. After adding aluminum(iii), the 8-hydroxyquinoline part self-assembled into a heteropolymetallic triscomplex [(Gd5)(3)Al(H(2)O)(3)](3-). The magnetic and optical properties of this metallostar compound were investigated in order to classify it as a potential in vitro bimodal contrast agent. The proton nuclear magnetic relaxation dispersion measurements indicated that the relaxivity r(1) of [Gd(H5)(H(2)O)](-) and [(Gd5)(3)Al(H(2)O)(3)](3-) at 20 MHz and 310 K equaled 6.17 s(-1) mM(-1) and 10.9 s(-1) mM(-1) per Gd(iii) ion respectively. This corresponds to a relaxivity value of 32.7 s(-1) mM(-1) for the supramolecular complex containing three Gd(iii) ions. The high relaxivity value is prominently caused by an increase of the rotational tumbling time τ(R) by a factor of 2.7 and 5.5 respectively, in comparison with the commercially used MRI contrast agent Gd(iii)-DTPA (Magnevist?). Furthermore, upon UV irradiation, [(Gd5)(3)Al(H(2)O)(3)](3-) exposes green broad-band emission with a maximum at 543 nm. Regarding the high relaxivity and the photophysical properties of the [(Gd5)(3)Al(H(2)O)(3)](3-) metallostar compound, it can be considered as a lead compound for in vitro bimodal applications. 相似文献
63.
骨折长骨中超声导波传播特性的仿真研究 总被引:5,自引:1,他引:4
采用超声导波评价长骨骨折已成为近两年来的一个研究热点.本文采用混合边界元方法(HBEM)对超声导波在骨裂长骨中的传播情况以及各导波模式的反射系数和透射系数进行了数值分析.研究结果表明,入射导波模式经由裂纹处模式转换后依然保持为主要接收模式不变.对某一裂纹,各模式透射系数常在相近的频率点上达到局部峰值.对于不同深宽比(d/w)裂纹,某些模式透射系数曲线局部峰值所对应的频率存在着相互错开的现象,这些结果可用于选择最优入射导波模式和频率,以便更好地定量评价骨质以及骨裂状况. 相似文献
64.
CHEN Wu-Hua ZHOU Yun-Long TA Hong-Gui HU Zhi-Biao ZHANG Zhu-Sen QIU Ze-Hai ZHANG Li ZENG Qing-Xin 《结构化学》2009,28(12)
The title compound 1 has been synthesized by the reaction of H_2MoO_4, CdCl_2, H_3PO_4, KF, piperazine hexahydrate and water in aqueous solution under mild hydrothermal conditions. Single-crystal X-ray analysis reveals that the title compound crystallizes in the triclinic system, space group P(-1) with a = 14.049(3), b = 15.972(3), c = 20.043(4) (A), α = 85.82(3), β = 81.28(3),γ = 67.15(3)°, V= 4095.9(14) (A)~3, M_r = 3204.62, Z=2,D_c = 2.598 g/cm~3,μ = 2.360 mm~(-1), F(000) = 3124, the final R = 0.0314, wR = 0.0826 and S = 0.989 for 18592 observed reflections with I > 2σ(I). The crystal packing is stabilized by N-H…O and O-H…O intra- and intermolecular hydrogen bonds to form an infinite 3D network. 相似文献
65.
Cesar B. Granda Mark T. Holtzapple Gary Luce Katherine Searcy Darryl L. Mamrosh 《Applied biochemistry and biotechnology》2009,156(1-3):107-124
The MixAlco process employs a mixed culture of acid-forming microorganisms to convert biomass to carboxylate salts, which are concentrated via vapor-compression evaporation and subsequently chemically converted to other chemical and fuel products. To make alcohols, hydrogen is required, which can be supplied from a number of processes, including gasifying biomass, separation from fermentor gases, methane reforming, or electrolysis. Using zeolite catalysts, the alcohols can be oligomerized into hydrocarbons, such as gasoline. A 40-tonne/h plant processing municipal solid waste ($45/tonne tipping fee) and using hydrogen from a pipeline or refinery ($2.00/kg H2) can sell alcohols for $1.13/gal or gasoline for $1.75/gal with a 15% return on investment ($0.61/gal of alcohol or $0.99/gal of gasoline for cash costs only). The capital cost is $1.95/annual gallon of mixed alcohols. An 800-tonne/h plant processing high-yield biomass ($60/tonne) and gasifying fermentation residues and waste biomass to hydrogen ($1.42/kg H2) can sell alcohols for $1.33/gal or gasoline for $2.04/gal with a 15% return on investment ($1.08/gal of alcohol or $1.68/gal of gasoline for cash costs only). The capital cost for the alcohol and gasification plants at 800 tonnes/h is $1.45/annual gallon of mixed alcohols. 相似文献
66.
R. Duncan Luce 《Aequationes Mathematicae》2009,78(3):321-328
A 1987 article studied the fact that some attributes can be measured in two ways: via concatenations and via decomposition
in a conjoint fashion. The measures were shown to be the same provided a distribution law is satisfied. The proof was algebraic
and indirect. A direct proof is provided using functional equation arguments. 相似文献
67.
A convenient label-free fluorescence(FL) nanoprobe for rapid detection of cadmium(Cd) was established using glutathione-capped CdS quantum dots(QDs) and 1,10-phenanthroline(phen). The prepared CdS QDs exhibited a strong FL emission at 536 nm, which could be quenched by phen due to the photoinduced hole transfer(PHT) mechanism. The existence of Cd effectively recovered the FL intensity of CdS QDs, which was due to the easy detachment of phen from the surface of QDs to form[Cd(phen)2(H2O)2]2+ in solution. Cd concentrations were linearly correlated with the FL intensity in the range of 0.0625-1.25 μmol/L under the optimized conditions and the detection limit was 0.01 μmol/L. Finally, the Cd concentration was accurately quantified in real water sample using the proposed sensor. 相似文献
68.
基频估计算法研究平均骨小梁间距 总被引:1,自引:0,他引:1
超声背散射信号能提供松质骨微结构信息从而能有效的诊断骨质疏松,而平均骨小梁间距(MTBS)是表征松质骨微结构的重要参数之一.本文提出了一种基频估计的MTBS估计算法,对仿真信号和离体牛胫骨松质骨中的超声背散射信号分别进行分析处理,并和现有的两种算法(简易反向滤波跟踪(SIFT)算法和AR倒谱法)进行比较.实验结果表明基频估计算法对噪卢和随机散射回波有更好的鲁棒性,在信噪比较低和随机散射回波幅度较大时估计值更加精确,且有很好的方差性能.充分说明了本文算法是一种有效的MTBS估计算法. 相似文献
69.
The formation and propagation of thermal fronts in a cylindricalmedium that is undergoing microwave heating is studied in detail.The model consists of Maxwell's wave equation coupled to a temperaturediffusion equation containing a bistable nonlinear term. When the thermal diffusivity is sufficiently small the leading-ordertemperature solution of a singular perturbation analysis isused to reduce the system to a free boundary problem. This approximationis then used to derive predictions for the steady-state penetrationand profiles of the temperature and electric fields. These solutionsare valid for arbitrary values of the electric conductivity,and thus extend the previous (small conductivity) results foundin the literature. A quasi-static approximation for the electric field is thenused to obtain an ordinary differential equation for the relaxationdynamics to the steady state. This equation appears to accuratelydescribe the time scale of the electric field's evolution bothwith and without the presence of a strongly coupled temperaturefront, and may be of wider interest than the model for microwaveheating studied here. 相似文献
70.