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991.
Yulin He Weina Zhou Xiangcheng Wang Baoliang Bao Guojian Zhang Cheng Wang Chunmei Wang Xuemei Wang Wei Fang 《Journal of Radioanalytical and Nuclear Chemistry》2014,301(2):469-474
In this study, we synthesized and characterized N-[11C]methyl-dopamine ([11C]MDA) for cardiac sympathetic nerve imaging. [11C]MDA was synthesized by direct N-methylation of dopamine with [11C]methyl iodide and purified by semi-preparation reverse high pressure liquid chromatography (HPLC). The total synthesis time was 45 min including HPLC purification. The radiochemical yields of [11C]MDA was 20 ± 3 %, without decay correction. The radiochemical purity was >98 % and the specific activity was about 50 GBq/mmol. The biological properties of [11C]MDA were evaluated by biodistribution study in normal mice. PET imaging was performed in healthy Chinese mini-swines. Biodistribution study showed that [11C]MDA had high myocardium uptake. PET/CT imaging showed [11C]MDA had clear and symmetrical myocardium uptake, which was blocked obviously by injecting imipramine hydrochloride. [11C]MDA would be a promising candidate of radiotracer for cardiac sympathetic nervous system imaging. 相似文献
992.
Zhi Zeng Jian Su Hao Ma Hengguan Yi Jianping Cheng Qian Yue Junli Li Hui Zhang 《Journal of Radioanalytical and Nuclear Chemistry》2014,301(2):443-450
To determine the environmental gamma background levels which affects rare events experiments, we measured in situ gamma spectrum at four locations in the China Jinping Underground Laboratory. The integral background count rates (40–2,700 keV) varied from 3.76 to 74.1 cps. The average count rate of the measurements inside the CJPL was 73.4 cps. The spectrometer was calibrated with a 152Eu point source and Monte Carlo simulation to obtain the activity conversion factors for the rock and the air, respectively. The rocks that surrounded the CJPL was characterized by very low activity concentrations of 238U (3.69–4.21 Bq kg?1), 232Th (0.52–0.64 Bq kg?1) and 40K (4.28 Bq kg?1). 相似文献
993.
Jing Liu Fangjun Wang Jun Zhu Jiawei Mao Zheyi Liu Kai Cheng Hongqiang Qin Hanfa Zou 《Analytical and bioanalytical chemistry》2014,406(13):3103-3109
Conventional N-glycoproteome analysis usually applies C18 reversed-phase (RP) adsorbent for sample purification, which will lead to unavoidable sample loss due to the high hydrophilicity of N-glycopeptides. In this study, a porous graphitized carbon (PGC) absorbent was combined with a C18 adsorbent for N-glycopeptide purification in comprehensive N-glycoproteome analysis based on the hydrophobic and polar interactions between carbon and N-glycans. It was observed that the small hydrophilic N-glycopeptides that cannot retain onto C18 adsorbent can be captured by the graphitized carbon, while the large hydrophobic N-glycopeptides that cannot retain onto the graphitized carbon can be feasibly captured by the C18 adsorbent. Comparing with sample purification by using C18 adsorbent only, 28.5 % more N-glycopeptides were identified by combining both C18 and PGC adsorbents. The C18-PGC strategy was further applied for both sample purification and pre-fractionation of a complex protein sample from HeLa cell. After hydrophilic interaction chromatography enrichment, 1,484 unique N-glycopeptides with 1,759 unique N-glycosylation sites were finally identified. Online Abstract Figure
The overlap of identified N-glycosylation sites by different SPE strategies 相似文献
994.
Photofragment translational spectroscopy at 304 nm from C-H symmetric stretch excited CH3I [v
1 = 1]
ZHOU ZhiMin HU LiLi DONG ChangWu ZHANG LiJuan LIU Sheng DU YiKui CHENG Min ZHU QiHe 《中国科学:化学(英文版)》2014,57(6):902-910
The 304 nm photodissociation of the C-H symmetric stretch excited CH3I[v1=1,v2=0](v1 denotes the C-H symmetric stretch mode,and v2 denotes the umbrella mode)is studied with our simple photofragment translational spectrometer.An IR laser is used to excite the ground state CH3I[0,0]to the C-H symmetric stretch excited CH3I[1,0].With IR laser OFF and ON,the fractions of photofragments CH3(ν1,ν2)from the 304 nm photodissociation of CH3I[1,0]have been determined through the photofragment translational spectra(PTS)from measuring I and I*and also through the PTS from measuring CH3(0,0)(1,0)(0,1)and(1,1).The experimental results show that the C-H symmetric stretch vibration(v1=1)in parent molecules is about 66%retained in the photofragments in the I channel,but only 24%in the I*channel.The populations of photofragments CH3(0,2)and(0,3)are higher than CH3(0,0)and(0,1),showing strong inverted population both in I and I*channels. 相似文献
995.
HUANG Jin Cheng LI Chun Shan BAI Lu NIE Yi WANG Er Qiang HE Yu Jian ZHANG Suo Jiang 《中国科学:化学(英文版)》2014,(12)
Coal-tar pitch(CP)is a promising carbon raw material for producing needle coke,carbon fiber etc.During processing,the H/C ratio,ash content,and quinoline insoluble(QI)in the CP are the key factors that influence the material preparation.In this study,NMP was selected to extract CP first;then[BMIM]Cl/NMP mixed solvent was used;and finally a series of ionic liquids(ILs)mixtures with NMP were developed for the extraction of CP to obtain the refined pitch.The extracts were analyzed via elemental analysis,TGA,FT-IR,and 13C-NMR.Results indicate that different NMP/IL mass ratios or different kinds of ILs have impact on the extraction yield.The relationship of the hydrogen to carbon(H/C)ratio changed with different solvents and QI extracts were obtained.Results showed that the H/C ratios changed little between NMP extracts and could be adjusted by changing the NMP/ILs mass ratio or using different ILs.The extracts are suitable for preparation mesophase pitch because of no ash content,low QI,and appropriate H/C ratios.As a result,NMP can be used to refine pitch.In addition,[BMIM]Cl is good mixed with NMP for CP extraction,because it can obtain a relatively high yield under the same extraction conditions. 相似文献
996.
Mingqiang Ding Xiaowu Jiang Lifen Zhang Zhenping Cheng Xiulin Zhu 《Macromolecular rapid communications》2015,36(19):1702-1721
Atom transfer radical polymerization (ATRP) is a versatile and robust tool to synthesize a wide spectrum of monomers with various designable structures. However, it usually needs large amounts of transition metal as the catalyst to mediate the equilibrium between the dormant and propagating species. Unfortunately, the catalyst residue may contaminate or color the resultant polymers, which limits its application, especially in biomedical and electronic materials. How to efficiently and economically remove or reduce the catalyst residue from its products is a challenging and encouraging task. Herein, recent advances in catalyst separation and recycling are highlighted with a focus on (1) highly active ppm level transition metal or metal free catalyzed ATRP; (2) post‐purification method; (3) various soluble, insoluble, immobilized/soluble, and reversible supported catalyst systems; and (4) liquid‐liquid biphasic catalyzed systems, especially thermo‐regulated catalysis systems.
997.
Qingqing Cheng Yiming Pan Qianjin Wang Tao Li Shining Zhu 《Laser \u0026amp; Photonics Reviews》2015,9(4):392-398
Recent realization of nontrivial topological phases in photonic systems has provided unprecedented opportunities in steering light flow in novel manners. Based on the Su–Schriffer–Heeger (SSH) model, a topologically protected optical mode was successfully demonstrated in a plasmonic waveguide array with a kinked interface that exhibits a robust nonspreading feature. However, under the same excitation conditions, another antikinked structure seemingly cannot support such a topological interface mode, which appears to be inconsistent with the SSH model. Theoretical calculations are carried out based on the coupled‐mode theory, in which the mode properties, excitation conditions, and the robustness are studied in detail. It is revealed that under the exact eigenstate excitations, both kinked and antikinked structures do support such robust topological interface modes; however, for a realistic single‐waveguide input only the kinked structure does so. It is concluded that the symmetry of interface eigenmodes plays a crucial role, and the odd eigenmode in a kinked structure offers the capacity to excite the nonspreading interface mode in the realistic excitation of a one‐waveguide input. Our finding deepens the understanding of mode excitation and propagation in coupled waveguide systems, and could open a new avenue in optical simulations and photonic designs.
998.
Dongliang Gao Andrey Novitsky Tianhang Zhang Fook Chiong Cheong Lei Gao Chwee Teck Lim Boris Luk'yanchuk Cheng‐Wei Qiu 《Laser \u0026amp; Photonics Reviews》2015,9(1):75-82
This paper investigates the singular optics of nonparaxial light beams in the near field when the light behaves as a tractor beam. New insights into the optical pulling force, which is usually represented by integrating the stress tensor at a black box enclosing the object, are interpreted by the optical singularity of the Poynting vector. The negative nonconservative pulling force originates from the transfer of the azimuthal Poynting vector to the longitudinal component partly owing to the presence of a scatterer. The separatrice pattern and singularity shifts of the Poynting vector unanimously exhibit a differentiable near‐field distribution in the presence of optical pulling force. A new method is established to calculate the near‐field optical force using the differential Poynting vector in the far field. The results obtained provide a clear physical interpretation of the light–matter interaction and manifest the significance of singular optics in manipulating objects.
999.
Tumor microenvironment is a multicomponent system consisting of tumor cells, noncancer cells, extracellular matrix, and signaling molecules, which hosts tumor cells with integrated biophysical and biochemical elements. Because of its critical involvement in tumor genesis, invasion, metastasis, and resistance, the tumor microenvironment is emerging as a hot topic of tumor biology and a prospective therapeutic target. Unfortunately, the complex of microenvironment modeling in vitro is technically challenging and does not effectively generalize the local tumor tissue milieu. Recently, significant advances in microfluidic technologies have provided us with an approach to imitate physiological systems that can be utilized to mimic the characterization of tumor responses with pathophysiological relevance in vitro. In this review, we highlight the recent progress and innovations in microfluidic technology that facilitates the tumor microenvironment study. We also discuss the progress and future perspective of microfluidic bionic approaches with high efficiency for the study of tumor microenvironment and the challenges encountered in cancer research, drug discovery, and personalized therapy. 相似文献
1000.