排序方式: 共有29条查询结果,搜索用时 46 毫秒
1.
Boudjahem AG Monteverdi S Mercy M Bettahar MM 《Langmuir : the ACS journal of surfaces and colloids》2004,20(1):208-213
We have studied the effect of silica of quartz-type on the reducibility of nickel acetate in aqueous hydrazine (80 degrees C, pH = 10-12) and metal particle formation. The obtained materials were characterized by X-ray diffraction, transmission electron microscopy, and thermodesorption experiments. With nickel acetate alone, the reduction was partial (45%) and a metal film at the liquid-gas interface or a powdered metal precipitate with an average particle size of 120 nm was obtained. In the presence of silica as the surfactant, the reduction of nickel acetate was total and the nickel phase deposited as a film on the support with an average particle size of 25 nm. Supported nickel acetate was also totally reduced. Crystallites of a mean particle size of about 3 nm were obtained. Decreasing the nickel content or increasing the hydrazine/nickel ratio decreased the metal particle size. Whiskers were formed for low nickel loadings. Hydrogen thermal treatment of the reduced phase showed that the organic acetate fragment, belonging to the precursor salt, still remained strongly attached to the nickel phase. The amount of the retained organic matrix depended on the metal particle size. Surface defects are suggested as active sites, which enhanced nickel ion reduction in the presence of silica as the surfactant or support. Metal-support interactions and the nucleation/ growth rate were the main factors determining the size and morphology of the supported metal particles formed. The organic matrix covered the reduced nickel phase. 相似文献
2.
Host–Guest Assembly of a Molecular Reporter with Chiral Cyanohydrins for Assignment of Absolute Stereochemistry 下载免费PDF全文
Hadi Gholami Dr. Mercy Anyika Jun Zhang Dr. Chrysoula Vasileiou Prof. Dr. Babak Borhan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(27):9235-9239
The absolute stereochemistry of cyanohydrins, derived from ketones and aldehydes, is obtained routinely, in a microscale and derivatization‐free manner, upon their complexation with Zn‐MAPOL, a zincated porphyrin host with a binding pocket comprised of a biphenol core. The host–guest complex leads to observable exciton‐coupled circular dichroism (ECCD), the sign of which is easily correlated to the absolute stereochemistry of the bound cyanohydrin. A working model, based on the ECCD signal of cyanohydrins with known configuration, is proposed. 相似文献
3.
LetH be a Hilbert space,X be a real Banach space,A: H→X be an operator withD (A) dense inH, G: H→H be positive definite,x ∈D (A) andb ∈H. Consider the quadratic programming problem: $$\begin{gathered} QP:Minimize \frac{1}{2}\left\langle {p,x} \right\rangle + \left\langle {x,Gx} \right\rangle \hfill \\ subject to Ax = b \hfill \\ \end{gathered} $$ In this paper, we obtain an explicit solution to teh above problem using generalized inverses. 相似文献
4.
Shaji Varghese Samuthira Nagarajan Mercy R. Benzigar Ajayan Mano Zeid A. ALOthman George Allen Gnana Raj Ajayan Vinu 《Tetrahedron letters》2012,53(12):1485-1489
A novel bimetallic nanoporous FeAl-KIT-5 catalyst with a cage type porous structure and a high surface area has been prepared for the hydroarylation of styrene and arylacetylenes to afford 1,1-diarylalkanes and 1,1-diarylalkenes, respectively. The catalyst was found to be highly active, and selective, affording a high yield of substituted alkanes and alkenes. The catalyst also showed much higher activity as compared to those of other nanoporous catalysts such as AlSBA-15, AlKIT-5, and FeKIT-5, and can be reused several times without much loss of its activity. 相似文献
5.
Highly Crystalline Mesoporous C60 with Ordered Pores: A Class of Nanomaterials for Energy Applications 下载免费PDF全文
Mercy R. Benzigar Stalin Joseph Hamid Ilbeygi Dr. Dae‐Hwan Park Dr. Sujoy Sarkar Dr. Goutam Chandra Prof. Siva Umapathy Prof. Sampath Srinivasan Dr. Siddulu Naidu Talapaneni Prof. Ajayan Vinu 《Angewandte Chemie (International ed. in English)》2018,57(2):569-573
Highly ordered mesoporous C60 with a well‐ordered porous structure and a high crystallinity is prepared through the nanohard templating method using a saturated solution of C60 in 1‐chloronaphthalene (51 mg mL?1) as a C60 precursor and SBA‐15 as a hard template. The high solubility of C60 in 1‐chloronaphthalene helps not only to encapsulate a huge amount of the C60 into the mesopores of the template but also supports the oligomerization of C60 and the formation of crystalline walls made of C60. The obtained mesoporous C60 exhibits a rod‐shaped morphology, a high specific surface area (680 m2 g?1), tuneable pores, and a highly crystalline wall structure. This exciting ordered mesoporous C60 offers high supercapacitive performance and a high selectivity to H2O2 production and methanol tolerance for ORR. This simple strategy could be adopted to make a series of mesoporous fullerenes with different structures and carbon atoms as a new class of energy materials. 相似文献
6.
7.
8.
Sensing Remote Chirality: Stereochemical Determination of β‐, γ‐, and δ‐Chiral Carboxylic Acids 下载免费PDF全文
Prof. Dr. Marina Tanasova Dr. Mercy Anyika Prof. Dr. Babak Borhan 《Angewandte Chemie (International ed. in English)》2015,54(14):4274-4278
Determining the absolute stereochemisty of small molecules bearing remote nonfunctionalizable stereocenters is a challenging task. Presented is a solution in which appropriately substituted bis(porphyrin) tweezers are used. Complexation of a suitably derivatized β‐, γ‐, or δ‐chiral carboxylic acid to the tweezer induces a predictable helicity of the bis(porphyrin), which is detected as a bisignate Cotton Effect (ECCD). The sign of the ECCD curve is correlated with the absolute stereochemistry of the substrate based on the derived working mnemonics in a predictable manner. 相似文献
9.
10.
C. Mercy Philip 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(4):335-343
An attempt has been made to design theophylline selective polymers with maximum selectivity and specificity, and to relate the rebinding capacity of the polymers with the degree of crosslinking, as well as with the template‐monomer ratio. The theophylline imprinted and non‐imprinted polymers based on methacrylic acid as the functional monomer and ethylene glycol dimethacrylate (EGDMA) as crosslinking agent (35–80 mol%) were prepared. The developed imprinted polymers were characterized by FT‐IR, 1H and 13C‐NMR spectra. Equilibrium binding of theophylline by the imprinted and non‐imprinted polymers were investigated and optimized the conditions. Imprinted polymers showed specific binding of the template theophylline. Selectivity of the imprinted polymers was investigated towards caffeine and nicotine. Imprinted polymers showed specific and selective binding of theophylline, which varied with the degree of EGDMA crosslinking. Equilibrium rebinding experiments proved that imprinted polymer with moderate (70%) crosslinking with 1∶2 template‐functional monomer ratio is ideal with maximum specificity and selectivity. 相似文献