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1.
Sanchez-sanz M; Blyth MG 《The Quarterly Journal of Mechanics and Applied Mathematics》2007,60(2):125-138
Unsteady, axisymmetric stagnation flow about a circular cylinderis examined when the far-field flow is a periodic function oftime with a fixed time average and an oscillatory part of prescribedamplitude and frequency. Solutions are computed for arbitraryvalues of the Reynolds number, quantifying the effects of surfacecurvature, and a frequency parameter based on the period ofthe far-field flow. It is found that solutions remain regularand periodic provided that the far-field amplitude lies belowa critical value. Above this value, solutions terminate in afinite-time singularity. The blow-up time is delayed by increasingthe curvature of the surface. These results are corroboratedby asymptotic predictions valid in the limits of small and largeamplitude and frequency. For large Reynolds number, the problemreduces to the two-dimensional stagnation-point flow againsta plane wall studied by previous authors. 相似文献
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S -nitrosothiols have many biological activities and may act as nitric oxide (NO) carriers and donors, prolonging NO half-life in vivo. In spite of their great potential as therapeutic agents, most S -nitrosothiols are too unstable to isolate. We have shown that the S -nitroso adduct of N -acetylcysteine (SNAC) can be synthesized directly in aqueous and polyethylene glycol (PEG) 400 matrix by using a reactive gaseous (NO/O2 ) mixture. Spectral monitoring of the S–N bond cleavage showed that SNAC, synthesized by this method, is relatively stable in nonbuf-fered aqueous solution at 25°C in the dark and that its stability is greatly increased in PEG matrix, resulting in a 28-fold decrease in its initial rate of thermal decomposition. Irradiation with UV light (λ= 333 nm) accelerated the rate of decomposition of SNAC to NO in both matrices, indicating that SNAC may find use for the photogeneration of NO. The quantum yield for SNAC decomposition decreased from 0.65 ± 0.15 in aqueous solution to 0.047 ± 0.005 in PEG 400 matrix. This increased stability in PEG matrix was assigned to a cage effect promoted by the PEG microenvironment that increases the rate of geminated radical pair recombination in the homolytic S–N bond cleavage process. This effect allowed for the storage of SNAC in PEG at −20°C in the dark for more than 10 weeks with negligible decomposition. Such stabilization may represent a viable option for the synthesis, storage and handling of S -nitrosothiol solutions for biomedical applications. 相似文献
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Synthesis and Evaluation of GdIII‐Based Magnetic Resonance Contrast Agents for Molecular Imaging of Prostate‐Specific Membrane Antigen
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Dr. Sangeeta Ray Banerjee Dr. Ethel J. Ngen Matthew W. Rotz Dr. Samata Kakkad Ala Lisok Richard Pracitto Mrudula Pullambhatla Dr. Zhengping Chen Dr. Tariq Shah Dr. Dmitri Artemov Dr. Thomas J. Meade Dr. Zaver M. Bhujwalla Dr. Martin G. Pomper 《Angewandte Chemie (International ed. in English)》2015,54(37):10778-10782
Magnetic resonance (MR) imaging is advantageous because it concurrently provides anatomic, functional, and molecular information. MR molecular imaging can combine the high spatial resolution of this established clinical modality with molecular profiling in vivo. However, as a result of the intrinsically low sensitivity of MR imaging, high local concentrations of biological targets are required to generate discernable MR contrast. We hypothesize that the prostate‐specific membrane antigen (PSMA), an attractive target for imaging and therapy of prostate cancer, could serve as a suitable biomarker for MR‐based molecular imaging. We have synthesized three new high‐affinity, low‐molecular‐weight GdIII‐based PSMA‐targeted contrast agents containing one to three GdIII chelates per molecule. We evaluated the relaxometric properties of these agents in solution, in prostate cancer cells, and in an in vivo experimental model to demonstrate the feasibility of PSMA‐based MR molecular imaging. 相似文献
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T. Pomper U. Lode A. Karl G. v. Krosigk S. Minko I. Luzinov 《Journal of Macromolecular Science: Physics》2013,52(5-6):869-883
The development of crazes in polycarbonate was investigated with the method of ultra-small-angle X-ray scattering (USAXS) of synchrotron radiation. Measurements at different temperatures and with different draw rates were carried out. The two-dimensional scattering patterns were analyzed by means of a fibrillar model of the craze. The geometrical parameters of the craze as a function of the macroscopic draw ratio were determined by using a curve-fitting procedure. From the measured values of the diameter and the mean distance of the fibrils, it is possible to calculate the volume fraction vf of the fibrils directly. Additional scattering caused by submicrocracks is discussed. 相似文献
6.
Tuning Phenols with Intra‐Molecular Bond Shifted HYdrogens (IM‐SHY) as diaCEST MRI Contrast Agents
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Xing Yang Nirbhay N. Yadav Xiaolei Song Prof. Sangeeta Ray Banerjee Hannah Edelman Il Minn Prof. Peter C. M. van Zijl Prof. Martin G. Pomper Prof. Michael T. McMahon 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(48):15824-15832
The optimal exchange properties for chemical exchange saturation transfer (CEST) contrast agents on 3 T clinical scanners were characterized using continuous wave saturation transfer, and it was demonstrated that the exchangeable protons in phenols can be tuned to reach these criteria through proper ring substitution. Systematic modification allows the chemical shift of the exchangeable protons to be positioned between 4.8 to 12 ppm from water and enables adjustment of the proton exchange rate to maximize CEST contrast at these shifts. In particular, 44 hydrogen‐bonded phenols are investigated for their potential as CEST MRI contrast agents and the stereoelectronic effects on their CEST properties are summarized. Furthermore, a pair of compounds, 2,5‐dihydroxyterephthalic acid and 4,6‐dihydroxyisophthalic acid, were identified which produce the highest sensitivity through incorporating two exchangeable protons per ring. 相似文献
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Targeted Delivery and Sustained Antitumor Activity of Triptolide through Glucose Conjugation
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Man Kyu Shim Dr. Hong Yeol Yoon Dr. Ju Hee Ryu Dr. Heebeom Koo Dr. Sangmin Lee Dr. Jae Hyung Park Dr. Jong‐Ho Kim Dr. Seulki Lee Dr. Martin G. Pomper Dr. Ick Chan Kwon Dr. Kwangmeyung Kim 《Angewandte Chemie (International ed. in English)》2016,55(47):14698-14703
Recently, metabolic glycoengineering with bioorthogonal click reactions has focused on improving the tumor targeting efficiency of nanoparticles as delivery vehicles for anticancer drugs or imaging agents. It is the key technique for developing tumor‐specific metabolic precursors that can generate unnatural glycans on the tumor‐cell surface. A cathepsin B‐specific cleavable substrate (KGRR) conjugated with triacetylated N‐azidoacetyl‐d ‐mannosamine (RR‐S‐Ac3ManNAz) was developed to enable tumor cells to generate unnatural glycans that contain azide groups. The generation of azide groups on the tumor cell surface was exogenously and specifically controlled by the amount of RR‐S‐Ac3ManNAz that was fed to target tumor cells. Moreover, unnatural glycans on the tumor cell surface were conjugated with near infrared fluorescence (NIRF) dye‐labeled molecules by a bioorthogonal click reaction in cell cultures and in tumor‐bearing mice. Therefore, our RR‐S‐Ac3ManNAz is promising for research in tumor‐specific imaging or drug delivery. 相似文献
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马丽娜 《纯粹数学与应用数学》2007,23(4):549-555
通过构造两个非负鞅证明了一个强极限定理,然后把它应用到本文所定义的广义Bethe树上的奇偶马尔可夫链场上,从而获得了此马氏链场上的一类强极限定理. 相似文献
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Marta Overchuk Martha P.F. Damen Kara M. Harmatys Martin G. Pomper Juan Chen Gang Zheng 《Photochemistry and photobiology》2020,96(3):718-724
Targeted photodynamic therapy (PDT) combined with image-guided surgical resection is a promising strategy for precision cancer treatment. Prostate-specific membrane antigen (PSMA) is an attractive target due to its pronounced overexpression in a variety of tumors, most notably in prostate cancer. Recently, we reported a pyropheophorbide-based PSMA-targeted agent, which exhibited long plasma circulation time and effective tumor accumulation. To further advance PSMA-targeted photodynamic therapy by harvesting tissue-penetrating properties of the NIR light, we developed a bacteriochlorophyll-based PSMA-targeted photosensitizer (BPP), consisting of three building blocks: (1) a PSMA-affinity ligand, (2) a peptide linker to prolong plasma circulation time and (3) a bacteriochlorophyll photosensitizer for NIR fluorescence imaging and photodynamic therapy (Qy absorption maximum at 750 nm). BPP exhibited excellent PSMA-targeting selectivity in both subcutaneous and orthotopic mouse models. The nine D-peptide linker in BPP structure prolonged its plasma circulation time (12.65 h). Favorable pharmacokinetic properties combined with excellent targeting selectivity enabled effective BPP tumor accumulation, which led to effective PDT in a subcutaneous prostate adenocarcinoma mouse model. Overall, bright NIR fluorescence of BPP enables effective image guidance for surgical resection, while the combination of its targeting capabilities and PDT activity allows for potent and precise image-guided photodynamic treatment of PSMA-expressing tumors. 相似文献