Two-dimensional(2-D)Ag nanoplates have surface plasmon resonances which can be tuned from the visible to the near-IR by varying the size and morphology of the nanoplates.Due to their anisotropic structures and different surface energy distributions,Ag nanoplates-especially triangular ones-are kinetically stable and can transform into other nanostructures.Taking advantage of the synergetic effects of HNO_(3)and Cl-in the reduction solution,uniform Ag hexagonal nanoplates(HNPs)have been captured during the transformation of Ag triangular nanoplates(TNPs).The dimensions of the Ag HNPs can be controlled by changing the concentrations of reagents in the reaction or/and reduction solutions.Resonance absorption spectra of the obtained Ag HNPs indicated that their in-plane resonance peaks could be tuned from the visible to the near-IR region,showing their potential applications in medical diagnosis.
A visible rectification effect on the current-voltage curves of metal/porous silicon/p-silicon has been observed by current- sensing atomic force microscopy. The current-voltage curves of porous silicon membranes with different porosities, prepared through variation of etching current density for a constant time, indicate that a higher porosity results in a higher resistance and thus a lower rectification, until the current reaches a threshold at a porosity >55%. We propose that the conductance mode in the porous silicon membrane with porosities >55% is mainly a hopping mechanism between nano-crystallites and an inverse static electric field between the porous silicon and p-Si interface blocks the electron injection from porous silicon to p-Si, but with porosities ≥55%, electron flows through a direct continuous channel between nano-crystallites.
Bing XiaQiang MiaoJie ChaoShou Jun XiaoHai Tao WangZhong Dang Xiao
Nonradiative energy transfer (NET) and rheology were used to investigate the chain contraction and aggregation...
Tao Fangfang and Xue Qi Department of Polymer Science and Engineering, The School of Chemistry and Chemical Engineering, State Key Laboratory of Co-ordination Chemistry, Nanjing University, Nanjing 210093
Submicrometer sized pure cubic phase,Eu^(3+)doped,and Yb^(3+)/Er^(3+)co-dopedα-NaYF4 particles with octahedral morphology have been prepared in acetic acid.The acetate anion plays a critical role in the formation of such symmetric octahedral structures through its selective adsorption on the(111)faces of the products.The size of the as-prepared octahedra can be tuned by varying the amount of sodium acetate added to the acetic acid.A possible formation mechanism for these octahedra has been proposed.The dopedα-NaYF_(4) octahedral submicrometer particles show down-conversion and up-conversion photoluminescence typical of these materials.
Li GaoXin GeZhanli ChaiGuohai XuXin WangCheng Wang
The reaction of the 16e half-sandwich complex Cp*Co(S2C2B10H10) (1) (Cp* = pentamethylcyclopentadienyl) with excess methyl acetylene monocarboxylate, HC≡C-CO2Me, affords the 18e complexes 2-6. Compound 2 bears a B-CH2 unit in which B-substitution occurs in the B(3)/B(6) position of the ortho-carborane cage. Complexes 3-6 are geometrical isomers, in which the alkyne is twofold inserted into one of the Co-S bonds in all the four possible ways. Treatment of 1 with excess 3-butyn-2-one or phenyl ethynyl ketone, HC≡C-C(O)R (R = Me, Ph), at ambient temperature leads to the 18e complexes 7-10, respectively, with two alkynes inserted into one of the Co-S bonds. All the new complexes were fully characterized by spectroscopic techniques and elemental analysis. The solid-state structures of 2, 3, 5, 7, 8, 9 and 10 were further characterized by X-ray structural analysis.
Porous silicon(PSi)was applied as a supporting substrate for stepwise covalent derivatization of undecylenic acid, N-hydroxysuccinimidyl ester(NHS-ester)and nitrilotriacetic acid(NTA).By taking the advantages of porous silicon as a supporting matrix such as high surface area to volume ratio,infrared transparency,porous semiconductors for laser desorption/ionization mass spectroscopy,and low fluorescence background,a multi-mode detection biochip prototype can be realized. We prepared such a protein microarray by spotting NTA microarray dots on NHS-ester derivatized PSi,converting the rest of chip area into poly(ethylene glycol)background,loading NiII,and finally affinity-binding histidine-tagged(His-tagged)proteins.With the multi-mode analyses of infrared spectroscopy,X-ray photoelectron spectroscopy(XPS),atomic force microscopy(AFM),matrix-assisted laser desorption/ionization mass spectroscopy(MALDI-MS),and fluorescence scanning,two example proteins,His-tagged thioredoxin-urodilatin and His-tagged aprotinin,were well qualified and quantified.
