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81.
A general and practical one‐pot synthesis of naphthopyran derivatives using hexadecyltrimethylammonium bromide (HTMAB) as catalyst (10 mol%) is described. This method provides several advantages such as neutral conditions, high yields and simple workup procedure. The catalyst is low cost, facile, active, environmentally friendly, and reusable. In addition, water is chosen as a green solvent. 相似文献
82.
Tetsuyuki Taniai Sachiko Wakasugi Susumu Hashimoto Ai Shimada Tatsuya Urabe Kazuya Takahashi 《International journal of environmental analytical chemistry》2013,93(5):601-612
To obtain information on the environmental impact of materials eluted from volcanic ashes of Mt. Oyama, Miyake Island, which erupted in July 2000, the dissolution behaviours of heavy metals and rare-earth elements from the volcanic ashes were examined. The most important characteristic of the Mt. Oyama eruption is that sulphur dioxide (SO2) gas has been continuously released, and all persons living on Miyake Island have been required to evacuate. To estimate in terms of the volcanic eruption using SO2 gas, the ash nature in Mt. Usu, Hokkaido, was also examined and compared with that in Mt. Oyama. When rain water mixed the ashes, the water from the ashes of Mt. Oyama became acidic because of the sulphuric acid. Therefore, SO2 gas in Mt. Oyama can accelerate the dissolution of protons and heavy metals in the ashes, whereas the rain water in Mt. Usu was not acidic and the dissolution of the heavy metals was not so evident compared with that in the case of Mt. Oyama. With this sulphuric acid, heavy metals such as As, Cd, Pb and Hg in the ashes in Mt. Oyama easily dissolved owing to the low pH. The ashes in Mt. Oyama had been released for eight years and the amount of fallen ashes was estimated to be 33 billion tons. The weights of the harmful heavy metals in the volcanic ashes, such as As, Cd, Pb and Hg, were estimated to be 3.8?×?102, 1.3?×?103, 1.1?×?103 and 29?kg, respectively, and these heavy metals were dissolved and diluted in seawater. Therefore, the concentration and species (chemical form) of these metals should be carefully monitored in the future. Moreover, SO2 gas, which has a direct effect on human health and has been monitored continuously, causes other effects, such as facilitation of metal ion elution and rock aeration. 相似文献
83.
84.
Dr. Junwu Zhu Chi Cheng Xiaowei Yang Yufei Wang Ling Qiu Prof. Dan Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(9):3082-3089
Restacking of graphene sheets to a graphite‐like structure is a prevailing problem that is known to compromise the performance of individual graphene sheets in an assembled bulk form. To address this common problem efficiently and monitor the structure and quality of graphene products comprehensively, it is highly desirable to develop reliable metrology techniques for characterising graphene‐based materials on a bulk assembly level and in a quantitative manner. Here, by revisiting the physicochemical principle of electrosorption, we propose a simple electrochemical approach, namely dynamic electrosorption analysis (DEA), as an easily accessible and effective technique for evaluation of the self‐stacking behaviour of graphene. Taking multilayered chemically converted graphene films as a model, we demonstrate that the DEA technique can effectively reveal very subtle variation in accessible surface area and pore size of graphene assemblies in the liquid phase and thus can provide useful insights to the experimental design relating to restacking control. This work also reveals the huge effect some routine processing conditions, such as heat treatment and drying, can have on the structure and performance of graphene‐based bulk materials, providing useful guidance for future manufacturing of this class of materials. 相似文献
85.
Yufei Ma Sheng Liang Hua Wu Hui Wang 《Journal of Radioanalytical and Nuclear Chemistry》2014,299(3):1865-1870
The successes of noninvasive methods to visualize and quantify integrin αvβ3 expression in vivo have paved the way for radiolabeling anti-integrin therapy in clinic. Arginine-glycine-aspartice (RGD) peptide and related derivatives labeled with radionuclides for radio-therapy, which specifically targeting integrin αvβ3-positive tumors, could be used to treat these tumors. We have labeled c(RGDyK)-His, a RGD derivative, with 188Re and the radio-therapy efficiency has been evaluated in model nude mice. c(RGDyK)-His was labeled with 188Re by chelating with [188Re(CO)3(H2O)3]+ under a slightly basic condition. The in vitro specific binding affinity to U87 MG cell lines and the biodistribution of 188Re-c(RGDyK)-His in the animal tumor models was measured. The inhibitory effects of 188Re-c(RGDyK)-His were observed more than 1 month, and evaluated by microPET/CT imaging with 18F-FDG. Results of in vivo, cell uptake demonstrated 188Re-c(RGDyK)-His had a high specific binding affinity to receptor integrin αvβ3. In biodistribution experiment, 188Re-c(RGDyK)-His was accumulated in the tumor and cleared fast from the normal tissues. In radiotherapy study, tumor growth inhibition was significantly higher in the treatment groups than in the control groups. These studies showed that 188Re-c(RGDyK)-His could be effectively used for integrin αvβ3 targeting therapy. This may offer a potential therapeutic strategy for the treatment of integrin-positive tumors in clinic. 相似文献
86.
The photoactivity of CdS nanorods was greatly improved by amino functionalized accordion-like MXene and spherical ZnSnO3. MXene possesses good electron transfer capability and ZnSnO3 presents matched energy band with CdS, which deeply accelerate the electron transfer and prevent the recombination of photogenerated electron-hole pair, leading to a strong photoelectrochemical (PEC) response. Taking the merit of the improved photoactivity of CdS nanorods, a novel PEC biosensor was constructed for DNA hydromethylation detection based on immune recognition of target molecule, where 5-hydroxymethyl-2′-deoxycytidine triphosphate (5hmdCTP) was employed as detect target, CdS/MXene was used as photoactive material, and ZnSnO3 was adopted as signal amplification unit. Under enzymatic covalent reaction of –CH2OH of 5hmdCTP with –NH2 of MXene, 5hmdCTP was specifically recognized and captured. Then, taking advantages of the covalent reaction between phosphate group of 5hmdCTP and ZnSnO3, the signal amplification unit was captured. Under the optimum conditions, this PEC biosensor presents wide linear range of 0.008–100 nM and low detection limit of 4.21 pM (3σ). The applicability of the developed method was evaluated by investigating the effect of Cd2+ and perfluorohexane compound pollutant on 5-hydroxymethylcytosine content in the genomic DNA of the roots and leaves of wheat seedlings. 相似文献
87.
Nanomaterials with localized surface plasmon resonance (LSPR) locating in the near-infrared region have broad application prospects in the field of biomedicine. However, the biggest problem that limits the biomedical application of such nanomaterials lies in two aspects: First, the potential long-term in vivo toxicity caused by the metabolism of many nanomaterials with LSPR effect; Second, most of current nanomaterials with LSPR effect are difficult to achieve LSPR wavelength tunability in the near-infrared region to adapt to different biomedical applications. Copper selenide nanomaterials are composed of selenium and copper, which are necessary nutrient elements for human life. Because of the active and flexible chemical properties of selenium and copper, copper selenide nanomaterials can not only be effectively degraded and utilized in human body, but also be endowed with various physicochemical properties by chemical modification or doping. Recently, copper selenide nanomaterials have shown unique properties such as LSPR in the near-infrared region, making them attractive for near-infrared thermal ablation, photoacoustic imaging, disease marker detection, multimode imaging, and so on. Currently, to the best of our knowledge, there is no review on the LSPR properties of copper selenide nanomaterials and its biomedical applications. This review first discusses the relationship between the physicochemical properties and the LSPR of copper selenide nanomaterials and then summarizes the latest progress in the application of copper selenide nanomaterials in biological detection, diagnosis, and treatment of diseases. In addition, the advantages, and prospects of copper selenide nanomaterials in biomedicine are also highlighted. 相似文献
88.
Hu Pan Renpeng Yan Xudong Li Xin Fa Yufei Ma Rongwei Fan Xin Yu Deying Chen 《Journal of Russian Laser Research》2016,37(3):259-264
We present a compact high-peak-power, high-repetition-rate burst-mode laser from a master-oscillator power amplifier (MOPA) at 1064 nm for laser-based measurement applications. The oscillator is an 808 nm pulsed laser diode side-pumped acousto-optical (A-O) Q-switched Nd:YAG laser at repetition rates ranging from 10–100 kHz, producing a pulse train with a pulse number of 2–25. The maximum output energy of the oscillator is 15.6 mJ at 10 kHz, whereas it is 1.7 mJ at 100 kHz. After twostage amplifiers, a single-pulse energy of 85.2 mJ with a pulse-width of 14.5 ns is achieved at 10 kHz, which produces a peak power of 6.1 MW. At 100 kHz, the total burst energy reaches 220 mJ with a single-pulse energy of 8.8 mJ in the pulse burst laser system. 相似文献
89.
90.
Sarah E. Walker Dr. James A. Jordan‐Hore Dr. David G. Johnson Prof. Dr. Stuart A. Macgregor Dr. Ai‐Lan Lee 《Angewandte Chemie (International ed. in English)》2014,53(50):13876-13879
A direct Pd‐catalyzed C? H functionalization of benzoquinone (BQ) can be controlled to give either mono‐ or disubstituted BQ, including the installation of two different groups in a one‐pot procedure. BQ can now be directly functionalized with aryl, heteroaryl, cycloalkyl, and cycloalkene groups and, moreover, the reaction is conducted in environmentally benign water or acetone as solvents. 相似文献