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101.
Bouffier L Yiu HH Rosseinsky MJ 《Langmuir : the ACS journal of surfaces and colloids》2011,27(10):6185-6192
Spherical magnetite nanoparticles (MNPs, ~ 24 nm in diameter) were sequentially functionalized with trimethoxysilylpropyldiethylenetriamine (TMSPDT) and a synthetic DNA intercalator, namely, 9-chloro-4H-pyrido[4,3,2-kl]acridin-4-one (PyAcr), in order to promote DNA interaction. The designed synthetic pathway allowed control of the chemical grafting efficiency to access MNPs either partially or fully functionalized with the intercalator moiety. The newly prepared nanomaterials were characterized by a range of physicochemical techniques: FTIR, TEM, PXRD, and TGA. The data were consistent with a full surface coverage by immobilized silylpropyldiethylenetriamine (SPDT) molecules, which corresponds to ~22,300 SPDT molecules per MNP and a subsequent (4740-2940) PyAcr after the chemical grafting step (i.e., ~ 2.4 PyAcr/nm(2)). A greater amount of PyAcr (30,600) was immobilized by the alternative strategy of binding a fully prefunctionalized shell to the MNPs with up to 16.1 PyAcr/nm(2). We found that the extent of PyAcr functionalization strongly affects the resulting properties and, particularly, the colloidal stability as well as the surface charge estimated by ζ-potential measurement. The intercalator grafting generates a negative charge contribution which counterbalances the positive charge of the single SPDT shell. The DNA binding capability was measured by titration assay and increases from 15 to 21.5 μg of DNA per mg of MNPs after PyAcr grafting (14-20% yield) but then drops to only ~2 μg for the fully functionalized MNPs. This highlights that even if the size of the MNPs is obviously a determining factor to promote surface DNA interaction, it is not the only limiting parameter, as the mode of binding and the interfacial charge density are essential to improve loading capability. 相似文献
102.
Hung WY Liu B Shou W Wen TB Shi C Sung HH Williams ID Lin Z Jia G 《Journal of the American Chemical Society》2011,133(45):18350-18360
The electrophilic substitution reactions of metallabenzynes Os(≡CC(R)═C(CH(3))C(R)═CH)Cl(2)(PPh(3))(2) (R = SiMe(3), H) were studied. These metallabenzynes react with electrophilic reagents, including Br(2), NO(2)BF(4), NOBF(4), HCl/H(2)O(2), and AlCl(3)/H(2)O(2) to afford the corresponding bromination, nitration, nitrosation, and chlorination products. The reactions usually occur at the C2 and C4 positions of the metallacycle. These observations support the notion that metallabenzynes exhibit aromatic properties. 相似文献
103.
Yiu Tung Poon 《Linear and Multilinear Algebra》2013,61(1-3):221-223
Let A 1,…,Am be nxn hermitian matrices. Definine W(A 1,…,Am )={(xA1x ?,…xAmx ?):x?C n ,xx ?=1}. We will show that every point in the convex hull of W(A 1,…,Am ) can be represented as a convex combination of not more than k(m,n) points in W(A 1,…,Am ) where k(m,n)=min{n,[√m]+δ n 2 m+1}. 相似文献
104.
Dr. Sze-Chun Yiu Dr. Po-Yu Ho Yan-Yi Kwok Xiaojie He Yi Wang Wai-Hong Yu Dr. Cheuk-Lam Ho Dr. Shuping Huang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(19):e202104575
Weak light absorption of common Ir(III) complexes (e. g., using phenylpyridine as the ligand) has hindered their applications in photocatalytic hydrogen generation from water as an efficient photosensitizer. To address this issue, a series of cyclometalated Ir(III) complexes (Ir1–Ir5), featuring different electron-donating substituents to enhance the absorptivity, have been synthesized and studied as photosensitizers (PSs) for light-driven hydrogen production from water. Ir6–Ir7 were prepared as fundamental systems for comparisons. Electron donors, including 9-phenylcarbazole, triphenylamine, 4,4′-dimethoxytriphenylamine, 4,4′-di(N-hexylcarbazole)triphenylamine moieties were introduced on 6-(thiophen-2-yl)phenanthridine-based cyclometalating (C^N) ligands to explore the donor effect on the hydrogen evolution performance of these cationic Ir(III) complexes. Remarkably, Ir4 with 4,4′-dimethoxytriphenylamine achieved the highest turn-over number (TON) of 12 300 and initial turnover frequency (TOFi) of 394 h−1, with initial activity (activityi) of 547 000 μmol g−1 h−1 and initial apparent quantum yield (AQYi) of 9.59 %, under the illumination of blue light-emitting diodes (LEDs) for 105 hours, which demonstrated a stable three-component photocatalytic system with high efficiency. The TON (based on n(H2)/n(PSr)) in this study is the highest value reported to date among the similar photocatalytic systems using Ir(III) complexes with Pt nanoparticles as catalyst. The great potential of using triphenylamine-based Ir(III) PSs in boosting photocatalytic performance has also been shown. 相似文献
105.
Dr. Zhengong Meng Dr. Guijun Li Dr. Sze-Chun Yiu Dr. Nianyong Zhu Prof. Dr. Zhen-Qiang Yu Dr. Chi-Wah Leung Prof. Dr. Ian Manners Prof. Dr. Wai-Yeung Wong 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(28):11618-11623
Self-assembly of d8 metal polypyridine systems is a well-established approach for the creation of 1D organometallic assemblies but there are still challenges for the large-scale construction of nanostructured patterns from these building blocks. We describe herein the use of high-throughput nanoimprint lithography (NIL) to direct the self-assembly of the bimetallic complexes [4′-ferrocenyl-(2,2′:6′,2′′-terpyridine)M(OAc)]+(OAc)− (M=Pd or Pt; OAc=acetate). Uniform nanorods are fabricated from the molecular self-organization and evidenced by morphological characterization. More importantly, when top-down NIL is coupled with the bottom-up self-assembly of the organometallic building blocks, regular arrays of nanorods can be accessed and the patterns can be controlled by changing the lithographic stamp, where the mold imposes a confinement effect on the nanorod growth. In addition, patterns consisting of the products formed after pyrolysis are studied. The resulting arrays of ferromagnetic FeM alloy nanorods suggest promising potential for the scalable production of ordered magnetic arrays and fabrication of magnetic bit-patterned media. 相似文献
106.
This paper introduces a new exact and smooth penalty function to tackleconstrained min-max problems.By using this new penalty function and adding justone extra variable,a constrained min-max problem is transformed into an unconstrainedoptimization one.It is proved that,under certain reasonable assumptions and when thepenalty parameter is sufficiently large,the minimizer of this unconstrained optimizationproblem is equivalent to the minimizer of the original constrained one.Numerical resultsdemonstrate that this penalty function method is an effective and promising approach forsolving constrained finite min-max problems. 相似文献
107.
108.
Xiaoyan Li Kaikai Li Sicong Zhu Ke Fan Linlong Lyu Haimin Yao Yiyang Li Jinlian Hu Haitao Huang Yiu‐Wing Mai John B. Goodenough 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(19):6305-6309
The sodium‐ion battery is a promising battery technology owing to its low price and high abundance of sodium. However, the sluggish kinetics of sodium ion makes it hard to achieve high‐rate performance, therefore impairing the power density. In this work, a fiber‐in‐tube Co9S8‐carbon(C)/Co9S8 is designed with fast sodiation kinetics. The experimental and simulation analysis show that the dominating capacitance mechanism for the high Na‐ion storage performance is due to abundant grain boundaries, three exposed layer interfaces, and carbon wiring in the design. As a result, the fiber‐in‐tube hybrid anode shows a high specific capacity of 616 mAh g?1 after 150 cycles at 0.5 A g?1. At 1 A g?1, a capacity of ca. 451 mAh g?1 can be achieved after 500 cycles. More importantly, a high energy density of 779 Wh kg?1 and power density of 7793 W kg?1 can be obtained simultaneously. 相似文献
109.
分析了以 S T D 总线工控机为核心的离子氮化温控系统总体结构和主要性能该控制系统采用双模控制方式,实现了在氮化过程中对各种工艺参数的最优控制,系统的设计达到了准确、直观、实时地控制整个渗氮过程的目的 相似文献
110.
Supported in part by NSERC of Canada 相似文献