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981.
Zhu GP Nguyen NT Ramanujan RV Huang XY 《Langmuir : the ACS journal of surfaces and colloids》2011,27(24):14834-14841
This paper reports experimental and numerical results of the deformation of a ferrofluid droplet on a superhydrophobic surface under the effect of a uniform magnetic field. A water-based ferrofluid droplet surrounded by immiscible mineral oil was stretched by a magnetic field parallel to the substrate surface. The results show that an increasing flux density increases the droplet width and decreases the droplet height. A numerical model was established to study the equilibrium shape of the ferrofluid droplet. The governing equations for physical fields, including the magnetic field, are solved by the finite volume method. The interface between the two immiscible liquids was tracked by the level-set method. Nonlinear magnetization was implemented in the model. Comparison between experimental and numerical results shows that the numerical model can predict well the nonlinear deformation of a ferrofluid droplet in a uniform magnetic field. 相似文献
982.
9-Anthracenecarboxylic acid, a molecule that undergoes a reversible [4 + 4] photodimerization, is prepared in the form of oriented crystalline microribbons. When exposed to spatially uniform light irradiation, these photoreactive ribbons rapidly twist. After the light is turned off, they relax back to their original shape over the course of minutes. This photoinduced motion can be repeated for multiple cycles. The final twist period and cross-sectional dimensions of individual microribbons are measured using a combination of atomic force and optical microscopies. Analysis of this data suggests that the reversible twisting involves the generation of interfacial strain within the ribbons between unreacted monomer and photoreacted dimer regions, with an interaction energy on the order of 3.4 kJ/mol. The demonstration of reversible twisting without the need for specialized irradiation conditions represents a new type of photoinduced motion in molecular crystals and may provide new modes of operation for photomechanical actuators. 相似文献
983.
Xiaoying Wang Xiaobing Wang Xiaoning Wang Fentian Chen Kehui Zhu Qian Xu Meng Tang 《Analytica chimica acta》2013
A novel electrochemical biosensor based on functional composite nanofibers for sensitive hybridization detection of p53 tumor suppressor using methylene blue (MB) as an electrochemical indicator is developed. The carboxylated multi-walled carbon nanotubes (MWNTs) doped nylon 6 (PA6) composite nanofibers (MWNTs–PA6) was prepared using electrospinning, which served as the nanosized backbone for pyrrole (Py) electropolymerization. The functional composite nanofibers (MWNTs–PA6–PPy) used as supporting scaffolds for ssDNA immobilization can dramatically increase the amount of DNA attachment and the hybridization sensitivity. The biosensor displayed good sensitivity and specificity. The target wild type p53 sequence (wtp53) can be detected as low as 50 fM and the discrimination is up to 57.5% between the wtp53 and the mutant type p53 sequence (mtp53). It holds promise for the early diagnosis of cancer development and monitoring of patient therapy. 相似文献
984.
Yong Xue HuaLi Nie Limin Zhu Shubai Li Haitao Zhang 《Applied biochemistry and biotechnology》2010,160(1):109-121
Papain (EC 3.4.22.2) has been chemically modified using two novel reagents including different anhydrides of 1,2,4-benzenetricarboxylic
and pyromellitic acids. Then, the modified papain was immobilized on the activated cotton fabric by a two-step method. The
number of free amino groups in the modified protein was investigated through the 2,4,6-trinitrobenzenesulfonic acid method.
Energy dispersive spectrometer was used to characterize papain immobilization. Some parameters of both modified and native
papain immobilized on cotton fabric, such as optimum temperature, optimum pH, and the stabilities for reservation in various
detergents were studied and compared. The resultant papain had its optimum pH shifted from 6.0 to 9.0. Compared with immobilized
native papain, the thermal stability and the resistance to alkali and washing detergent of immobilized modified enzyme were
improved considerably. When the concentration of detergent was 20 mg/ml, the activity of the immobilized pyromellitic papain
retained about 40% of its original activity, whereas the native papain was almost inhibited. This work demonstrated that the
cotton fabric immobilized modified papain has potential applications in the functional textiles field. 相似文献
985.
Guangfeng Wang Yanhong Zhu Xiuping He Ling Chen Lun Wang Xiaojun Zhang 《Mikrochimica acta》2014,181(3-4):411-418
We report on the detection of trace quantities of melamine (MA) by a colorimetric method that exploits the conformational change of hemin G-quadruplex-DNAzyme. The addition of MA to hemin G-quadruplex-DNAzyme structure containing thymine bases causes the thymine in the DNAzyme to interact with MA via a stable triple H-bond and leads to a conformational change. This, in turn, affects the peroxidase-like activity of hemin which is determined colorimetrically at 450 nm by adding 3,3’,5,5’-tetramethylbenzidine and hydrogen peroxide. The method was applied to the colorimetric determination of MA over a wide range of concentrations (0.2 to 24 μM) with a detection limit of 80 nM. The effect also can be detected with bare eyes. The method was successfully applied to the determination of MA in spiked milk powder. Figure
A novel, simple and rapid, visual colorimetric method is applied for the detection of melamine with a wide range of 8?×?10?7 M to 1?×?10?3 M and low detection limit of 2.7?×?10?7 M. 相似文献
986.
Lijuan Song Yulong Wang Lu Zhu Bolong Guo Suwen Chen Wangsuo Wu 《Journal of Radioanalytical and Nuclear Chemistry》2014,299(3):1589-1595
Polyoxometalates K7[α-PW11O39]·14H2O (PW11) modified mesoporous silica (MCM-48) with cubic structure, was prepared by impregnation and calcination methods. The modified mesoporous silica sorbent (PW11/MCM-48) was studied as a potential adsorbent for U(VI) from aqueous solutions. MCM-48 and PW11/MCM-48 were confirmed by X-ray diffraction and nitrogen physisorption techniques. The results indicate the original keggin structure of PW11 and mesoporous structure of MCM-48 are maintained after supporting PW11 on mesoporous silica MCM-48. The effects of contact time, solid-to-liquid ratio (m/V), solution pH and ionic strength on U(VI) sorption behaviors of the pure and modified mesoporous silicas were also studied. Typical sorption isotherms such as Langmuir and Freundlich isotherms were determined for sorption process. The results suggest that the sorption of U(VI) on MCM-48 or PW11/MCM-48 are strongly dependent on pH values but independent of ionic strength. The sorption capacity of PW11/MCM-48 for U(VI) is about ten times more than that of MCM-48. 相似文献
987.
988.
Realignment of Nanocrystal Aggregates into Single Crystals as a Result of Inherent Surface Stress 下载免费PDF全文
Zhaoming Liu Dr. Haihua Pan Genxing Zhu Yaling Li Dr. Jinhui Tao Biao Jin Prof. Ruikang Tang 《Angewandte Chemie (International ed. in English)》2016,55(41):12836-12840
Crystallization by particle attachment is widely observed in both natural and synthetic environments. Although this form of nonclassical crystallization is generally described by oriented attachment, random aggregation of building blocks to give single‐crystal products is also observed, but the mechanism of crystallographic realignment is unknown. We herein reveal that random attachment during aggregation‐based growth initially produces a nonoriented growth front. Subsequent evolution of the orientation is driven by the inherent surface stress applied by the disordered surface layer and results in single‐crystal formation by grain‐boundary migration. This mechanism is corroborated by measurements of orientation rate versus external stress, which demonstrated a predictive relationship between the two. These findings advance our understandings about aggregation‐based growth via nanocrystal blocks and suggest an approach to material synthesis that takes advantage of stress‐induced coalignment. 相似文献
989.
Huan Ge Dongya Wang Yue Pan Yuanyuan Guo Hongyu Li Fan Zhang Prof. Xinyuan Zhu Prof. Yuehua Li Prof. Chuan Zhang Prof. Ling Huang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(21):8210-8214
DNA-modified lanthanide-doped upconversion nanoparticles (DNA-UCNPs) that combine the functions of DNA and the optical features of UCNPs have shown great promise in a wide range of fields. However, challenges remain in precisely tethering and orienting the DNA strands on the UCNP surface. Herein, we systematically investigate the sequence dependence of DNAs in their interactions with UCNPs, and reveal that poly-cytosine (poly-C) has high affinity for the UCNP surface. A general approach to synthesize monodispersed DNA-UCNP conjugates is developed using poly-C-containing diblock DNA strands. The poly-C segment of the DNA strand binds to the surfaces of UCNPs and the second segment is oriented perpendicularly on the UCNP surface, making the DNA-UCNPs highly stable and monodispersed in aqueous solution. The dense layer of DNA on the UCNP surface enables the programmable assembly of UCNPs with other DNA-functionalized nanoparticles or DNA origamis through hybridization, resulting in the formation of well-organized complex structures. 相似文献
990.
Wan‐Lei Yu Yong‐Chun Luo Lei Yan Dan Liu Zhu‐Yin Wang Peng‐Fei Xu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(32):11057-11061
A synergistic catalytic method combining photoredox catalysis, hydrogen‐atom transfer, and proton‐reduction catalysis for the dehydrogenative silylation of alkenes was developed. With this approach, a highly concise route to substituted allylsilanes has been achieved under very mild reaction conditions without using oxidants. This transformation features good to excellent yields, operational simplicity, and high atom economy. Based on control experiments, a possible reaction mechanism is proposed. 相似文献