排序方式: 共有80条查询结果,搜索用时 31 毫秒
41.
Chauhan N Gupta S Singh N Singh S Islam SS Sood KN Pasricha R 《Journal of colloid and interface science》2011,363(1):42-50
We depict a novel strategy exploiting the chemistry of metal ion adsorption for detection and sequestration of toxic heavy metal from processed water using gold nanoparticles capped with 4-aminothiophenol. The interaction between 4-aminothiophenol capped gold nanoparticles and heavy metal ions was studied as a function of time and concentration using TEM, HRTEM, SEM, EDS, and I-V characterization. Experiments confirmed that pH is one of the crucial controlling parameters. Adsorption capacity was monitored using AAS, UV-vis spectroscopy and I-V measurement. In the absence of any alloy formation between Au and heavy metal ions, the desorption of the heavy metal ions from 4-aminothiophenol capped gold nanoparticles surface by pH modulation serves as a mean of collection of heavy metal ions. Experiments revealed that the concentration of heavy metal ions in processed water after adsorption is below the maximum permissible limit set by the WHO. 相似文献
42.
We compute analytically the full distribution of Andreev conductance G(NS) of a metal-superconductor interface with a large number N(c) of transverse modes, using a random matrix approach. The probability distribution P(G(NS),N(c) in the limit of large N(c) displays a Gaussian behavior near the average value =(2-√2)N(c) and asymmetric power-law tails in the two limits of very small and very large G(NS). In addition, we find a novel third regime sandwiched between the central Gaussian peak and the power-law tail for large G(NS). Weakly nonanalytic points separate these four regimes-these are shown to be consequences of three phase transitions in an associated Coulomb gas problem. 相似文献
43.
The projection of integrating optical, magnetic and electronic functionalities into a single material have aggravated passionate
attention in mounting wide band gap diluted magnetic semiconductor (DMS) in the midst of room temperature ferromagnetism.
We report the evidence of ferromagnetism in Cu-doped ZnSe quantum dots (QDs) below room temperature, grown from a single source
precursor by lyothermal method with the sizes of approximately 3.2–5.14 nm. QDs mainly exhibit paramagnetic behavior between
80 and 300 K, with a weak ferromagnetic/anti-ferromagnetic exchange at lower temperature as observed by superconducting quantum
interference device (SQUID) magnetometer. From the Curie–Weiss behavior of the susceptibility, Curie temperature (T
c) of Cu-doped ZnSe sample has been evaluated. From EPR, we obtain the Lande-g factor in the Zeeman interaction term as 2.060. Photoluminescence and EPR measurements support and confirm the view that
Cu2+ substitutes for Zn2+ in Cu-doped ZnSe quantum dots. 相似文献
44.
Punita Srivastava Pushpendra Kumar Kedar Singh 《Journal of nanoparticle research》2011,13(10):5077-5085
Manipulation of carrier spins in semiconductors for spintronics applications has received great attention driven by improved
functionalities and higher speed operation. Doping of semiconductor nanocrystals by transition-metal ions pronounced as diluted
magnetic semiconductors (DMS) has attracted tremendous attention. Such doping is, however, difficult to achieve in low-dimensional
strongly quantum-confined nanostructures by conventional growth procedures. In the present case, magic-sized, pure, and Cr-doped
CdS DM-QDs have been synthesized by solution phase chemistry (lyothermal method). Structural, optical, and magnetic investigation
suggest an intrinsic nature of ferromagnetism with highly quantum-confined system. Optical and magnetic results of pure and
doped QDs reveal major physical consequences of dopant localization within the capacity to engineer dopant-carrier exchange
interactions introducing magnetic functionalities within the host semiconductor lattice. Unpaired Cr ions in Cd substitutional
sites could create spin ordering and ferromagnetic coupling. The results presented herein illustrate some of the remarkable
and unexpected complexities that can arise in doped QDs. 相似文献
45.
Huang L Manandhar P Byun KE Chase PB Hong S 《Langmuir : the ACS journal of surfaces and colloids》2006,22(21):8635-8638
We report a new strategy to selectively assemble and align filamentous actin (F-actin) onto desired locations on a solid substrate with a specific structural polarity. In this strategy, biotinylated gelsolin caps the structural minus end of F-actin so that the F-actin binds onto a streptavidin pattern with a specific structural polarity. We also demonstrate that an electric field can be utilized to align bound F-actin along a desired direction. This can be one of the major technical breakthroughs toward the assembly of nanomechanical systems based on myosin biomotors. 相似文献
46.
Nitin J. Pawar Lei Wang Takuya Higo Chandrabali Bhattacharya Pavan K. Kancharla Fuming Zhang Kedar Baryal Chang‐Xin Huo Jian Liu Robert J. Linhardt Xuefei Huang Linda C. Hsieh‐Wilson 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(51):18750-18756
The complex sulfation motifs of heparan sulfate glycosaminoglycans (HS GAGs) play critical roles in many important biological processes. However, an understanding of their specific functions has been hampered by an inability to synthesize large numbers of diverse, yet defined, HS structures. Herein, we describe a new approach to access the four core disaccharides required for HS/heparin oligosaccharide assembly from natural polysaccharides. The use of disaccharides rather than monosaccharides as minimal precursors greatly accelerates the synthesis of HS GAGs, providing key disaccharide and tetrasaccharide intermediates in about half the number of steps compared to traditional strategies. Rapid access to such versatile intermediates will enable the generation of comprehensive libraries of sulfated oligosaccharides for unlocking the “sulfation code” and understanding the roles of specific GAG structures in physiology and disease. 相似文献
47.
Feng Chen Prakash Manandhar Md Salauddin Ahmed Shuai Chang Namuna Panday Haiqian Zhang Joong Ho Moon Jin He 《Macromolecular bioscience》2019,19(2)
In‐depth understanding of the biophysicochemical interactions at the nano–bio interface is important for basic cell biology and applications in nanomedicine and nanobiosensors. Here, the extracellular surface potential and topography changes of live cell membranes interacting with polymeric nanomaterials using a scanning ion conductance microscopy‐based potential imaging technique are investigated. Two structurally similar amphiphilic conjugated polymer nanoparticles (CPNs) containing different functional groups (i.e., primary amine versus guanidine) are used to study incubation time and functional group‐dependent extracellular surface potential and topographic changes. Transmembrane pores, which induce significant changes in potential, only appear transiently in the live cell membranes during the initial interactions. The cells are able to self‐repair the damaged membrane and become resilient to prolonged CPN exposure. This study provides an important observation on how the cells interact with and respond to extracellular polymeric nanomaterials at the early stage. This study also demonstrates that extracellular surface potential imaging can provide a new insight to help understand the complicated interactions at the nano–bio interface and the following cellular responses. 相似文献
48.
We present a variational wave function which explains the behavior of the supersolid state formed by hard-core bosons on the triangular lattice. The wave function is a linear superposition of only and all configurations minimizing the repulsion between the bosons (which it thus implements as a hard constraint). Its properties can be evaluated exactly--in particular, the variational minimization of the energy yields (i) the surprising and initially controversial spontaneous density deviation from half-filling (ii) a quantitatively accurate estimate of the corresponding density wave (solid) order parameter. 相似文献
49.
We report the first observation of anomalous diffusion in nanometer scale direct deposition processes utilizing dip-pen nanolithography (DPN). DPN permits quite general nanostructure patterns to be drawn on flat surfaces. Here we demonstrate experimentally, and discuss theoretically, the situation in which the molecular ink in DPN binds weakly to the surface. We observe, for the weak-binding case of 1-dodecylamine on mica, that anomalous diffusion occurs, leading to nearly fractal deposition patterns. 相似文献
50.
We derive an effective Hamiltonian for Ga(1-x)Mn(x)As in the dilute limit, where Ga(1-x)Mn(x)As can be described in terms of spin F=3/2 polarons hopping between the Mn sites and coupled to the local Mn spins. We determine the parameters of our model from microscopic calculations. Our approach treats the large Coulomb interaction in a nonperturbative way, captures the effects of spin-orbit coupling and disorder, and is appropriate for other p-doped magnetic semiconductors. 相似文献