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991.
Repeated irradiation enhances the precision and sensitivity of INAA based on short-live radionuclides, but entail systematic losses due to dead time. The relative standard deviation in the net peak area decreases with the square root of the number of cycles while the systematic bias increases with it. The limits of decision, detection and determination decrease in a somewhat more complicated way with the number of cycles. The derived formulation is applied to the determination of selenium in hair by the 161.9 keV photopeak of77mSe,T
1/2=17.8 s. 相似文献
992.
Improved numerical methods and physical models have been applied to droplet collision modeling. Numerically, an adaptive collision mesh method is developed to calculate collision rate. This method produces a collision mesh that is independent of the gas phase mesh and adaptively refined according to local parcel number density. An existing model describing the satellite droplet formation during the collision process is improved to reflect the experimental findings that the satellite droplets are much smaller than the parent droplets. The adaptive collision mesh and the improved satellite model have been used to simulate three impinging spray experiments. The model was able to qualitatively predict the occurrence of small satellite drops and bi-modal post-collision drop size distributions. The effect of the collision mesh and the satellite droplet model on a high-speed non-evaporating diesel spray is also assessed. 相似文献
993.
Cross‐Linked Aptamer–Lipid Micelles for Excellent Stability and Specificity in Target‐Cell Recognition 下载免费PDF全文
Xiaowei Li Dr. C. Adrian Figg Dr. Ruowen Wang Dr. Ying Jiang Dr. Yifan Lyu Hao Sun Dr. Yuan Liu Dr. Yanyue Wang Dr. I‐Ting Teng Dr. Weijia Hou Dr. Ren Cai Dr. Cheng Cui Long Li Xiaoshu Pan Prof. Brent S. Sumerlin Prof. Weihong Tan 《Angewandte Chemie (International ed. in English)》2018,57(36):11589-11593
The specific binding ability of DNA–lipid micelles (DLMs) can be increased by the introduction of an aptamer. However, supramolecular micellar structures based on self‐assemblies of amphiphilic DLMs are expected to demonstrate low stability when interacting with cell membranes under certain conditions, which could lead to a reduction in selectivity for targeting cancer cells. We herein report a straightforward cross‐linking strategy that relies on a methacrylamide branch to link aptamer and lipid segments. By an efficient photoinduced polymerization process, covalently linked aptamer–lipid units help stabilize the micelle structure and enhance aptamer probe stability, further improving the targeting ability of the resulting nanoassembly. Besides the development of a facile cross‐linking method, this study clarifies the relationship between aptamer–lipid concentration and the corresponding binding ability. 相似文献
994.
We computed by spin-polarized DFT the structure and the electronic properties of an infinite periodic wire constituted of planar Cu-bridged hydroxypyridone chelator base pairs and of a similarly stacked finite dimer. The Cu centers undergo electronic hybridization with the bases. There is an unpaired spin per plane, and the majority-spins manifest ordering: The ferromagnetic and antiferromagnetic phases are energetically degenerate. The total magnetization of the ferromagnetic wire depends linearly on the number of planes in the stack. The combination of interplane spin coupling and intraplane metal-hydroxypyridone coupling makes this system very appealing for electronic and magnetic device exploitation. 相似文献
995.
<正>A TiO_2/porous silicon(PS) composite system is prepared by chemical vapor deposition.The crystal form with anatase phase of the samples is evaluated by X-ray diffraction and ultraviolet-visible(UV-vis) absorbance spectra,and the morphology with microsphere of TiO_2 particles is characterized by scanning electron microscopy.The composite system formed by this technique gives a broad blue luminescence and the mechanism of photoluminescence with TiO_2/PS is also discussed. 相似文献
996.
997.
高功率半导体激光端面泵浦方形掺Nd3+离子激光晶体热形变研究 总被引:1,自引:4,他引:1
为了解决高功率半导体激光器端面泵浦激光晶体引起的热效应问题,激光晶体泵浦端面的热形变必须进行准确的计算.通过对于全固态激光器中激光晶体的工作特点分析,建立了矩形截面激光晶体热分析模型.基于热传导方程,提出了泊松方程的一种新解,并获得了矩形截面激光晶体端面热形变分布的一般解析表达式.同时讨论了半导体激光器偏心泵浦激光晶体给端面热形变带来的影响.与有限元分析方法以及其他数值分析方法相比,解析分析方法不会给计算引入任何的误差.热形变的解析分析为解决激光晶体的热效应问题以及提高激光器的性能提供了理论的依据. 相似文献
998.
提出了一种基于微悬臂梁传感技术研究大分子折叠/构象转变的新方法.通过分子自组装的方法将热敏性的聚N-异丙基丙烯酰胺(PNIPAM)分子链修饰到微悬臂梁的单侧表面,用光杠杆技术检测温度在20-40 ℃之间变化时由于微悬臂梁上的PNIPAM分子在水中的构象转变所引起的微悬臂梁变形.实验结果显示:在升温过程中,微悬臂梁的表面应力发生了变化并且导致微悬臂梁产生了弯曲变形,这个过程对应着微悬臂梁上的PNIPAM分子从无规线团构象到塌缩小球构象的构象转变.在降温过程中,微悬臂梁发生了反方向的弯曲变形,这对应着PNIPAM分子从塌缩小球构象向无规线团构象的构象转变.整个温度变化过程中构象转变是连续进行的,而在低临界溶解温度(约32 ℃)附近转变幅度较大,这与自由水溶液中PNIPAM分子的无规线团-塌缩小球构象转变相对应.实验结果还显示:由于PNIPAM分子在塌缩过程中氢键的形成和链段间可能的缠结效应,整个温度循环过程中微悬臂梁的变形是不可逆的且有明显的迟滞效应. 相似文献
999.
Abe K Adachi I Aihara H Arinstein K Asano Y Aulchenko V Aushev T Aziz T Bakich AM Balagura V Barbero M Bedny I Bitenc U Bizjak I Bondar A Bracko M Brodzicka J Browder TE Chao Y Chen A Cheon BG Chistov R Choi SK Choi Y Choi YK Chuvikov A Cole S Dalseno J Danilov M Dash M Drutskoy A Eidelman S Epifanov D Fratina S Gabyshev N Gershon T Gokhroo G Golob B Ha HC Haba J Hasegawa Y Hayasaka K Hayashii H Hazumi M Hinz L Hoshi Y Hou S Hou WS Hsiung YB Iijima T Ishikawa A Iwasaki M Iwasaki Y Kapusta P 《Physical review letters》2007,98(8):082001
We report the first observation of a charmoniumlike state recoiling from the J/psi in the inclusive process e+e- -->J/psi+anything at a mass of (3.943+/-0.006+/-0.006) GeV/c{2}. We also observe the decay of this state into D*D[over ] and determine its intrinsic width to be less than 52 MeV/c{2} at the 90% C.L. These results are obtained from a 357 fb{-1} data sample collected with the Belle detector near the Upsilon(4S) resonance, at the KEKB asymmetric-energy e+e- collider. 相似文献
1000.
Drutskoy A Abe K Abe K Adachi I Aihara H Anipko D Arinstein K Aulchenko V Aushev T Banerjee S Barberio E Barbero M Bedny I Belous K Bitenc U Bizjak I Blyth S Bondar A Bozek A Bracko M Brodzicka J Browder TE Chang P Chao Y Chen A Chen KF Chen WT Cheon BG Chistov R Choi Y Choi YK Chuvikov A Cole S Dalseno J Danilov M Dash M Dragic J Eidelman S Epifanov D Fratina S Gabyshev N Gershon T Go A Gokhroo G Goldenzweig P Golob B Ha H Haba J Hara T Hayasaka K Hayashii H Hazumi M Heffernan D Higuchi T 《Physical review letters》2007,98(5):052001
The inclusive production of D(s), D(0), and J/psi mesons is studied using a 1.86 fb(-1) data sample collected on the Upsilon(5S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. The number of bb events in this Upsilon(5S) data sample is determined. We measure the branching fractions B(Upsilon(5S)-->D(s)X)/2=(23.6+/-1.2+/-3.6)%, B(Upsilon(5S)-->D(0)X)/2=(53.8+/-2.0+/-3.4)%, and B(Upsilon(5S)-->J/psiX)/2=(1.030+/-0.080+/-0.067)%. From the D(s) and D(0) inclusive branching fractions the ratio f(s)=(18.0+/-1.3+/-3.2)% of B(s)(*)B(s)(*) to the total bb quark pair production at the Upsilon(5S) energy is obtained in a model-dependent way. 相似文献