نتایج جستجو برای: chemical hardness

تعداد نتایج: 401656  

Stabilities and quantum molecular descriptors of cyclophoshphamide (an anticancer drug)-functionalized (8,0) zigzag and (4,4) armchair carbon nanotubes (CNTs) complexes in water were studied using density functional theory (DFT) calculations. Two attachments namely the sidewall- and tip-attachments are considered for the model constructions. Calculations of the total electronic energy (Et) and ...

2013
Rafael Velázquez Victor F. Neto Brad R. Weiner Gerardo Morell

The hardness, heat conductivity and low friction coefficient of microcrystalline diamond make it a suitable candidate for tribological applications. However, its roughness and high deposition temperature pose significant obstacles to these applications. We have successfully grown nanocrystalline diamond on steel at 400 °C by hot-filament chemical vapor deposition by employing a CrN interfacial ...

2011
Promita Bhattacharjee Howa Begam Abhijit Chanda

In this study, we made an attempt to synthesize doped bioactive hydroxyapatite (HAp) ceramic powder using a simple Chemical method and studied its physical and mechanical properties. Different quantities (2wt% and 5 wt%) of Magnesium chloride Hexahydrate , Zinc oxide, Titanium oxide were incorporated as dopants into Hap at the time of synthesis. The synthesized powder samples were analyzed for ...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 1992
M K Harbola

It is shown that for relatively more stable metallic clusters (those with magic number of atoms) the chemical hardness (I-A) too is relatively larger. Thus the occurrence of magic numbers for metal clusters whose stability is determined by their electronic shell structure can be understood as a manifestation of the principle of maximum hardness. This may also represent a possible way of delinea...

Journal: :Physical review letters 2009
E Yu Zarechnaya L Dubrovinsky N Dubrovinskaia Y Filinchuk D Chernyshov V Dmitriev N Miyajima A El Goresy H F Braun S Van Smaalen I Kantor A Kantor V Prakapenka M Hanfland A S Mikhaylushkin I A Abrikosov S I Simak

An orthorhombic (space group Pnnm) boron phase was synthesized at pressures above 9 GPa and high temperature, and it was demonstrated to be stable at least up to 30 GPa. The structure, determined by single-crystal x-ray diffraction, consists of B12 icosahedra and B2 dumbbells. The charge density distribution obtained from experimental data and ab initio calculations suggests covalent chemical b...

1999
Valentina Colla Leonardo Maria Reyneri Mirko Sgarbi

This work compares a few attempts based on Neural and Wavelet networks, for extracting the Jominy hardness pro le of steels directly from the chemical composition. In particular, the paper proposes a multi-networks architecture, where a rst network is used as a parametric modeler of the Jominy pro le itself, while a second one is used as a parameter estimator from the steel chemical composition.

1999
Valentina Colla Leonardo Maria Reyneri Mirko Sgarbi

This work address the problem of extracting the Jominy hardness pro les of steels directly from the chemical composition. Wavelet and Neural networks provide very intresting results, especially when compared with classical methods. A hierarchical architecture is proposed, with a rst network used as a parametric modeler of the Jominy pro le, and a second one estimating parameters from the steel ...

2015
Sunita Verma J. B. Khan

This Paper Present to study of the Physico-chemical Parameters of Fateh Sagar Talab in Bagar of Jhunjhunu district in Rajasthan. The study was carried out for a period of one year i.e. July 2012 to June 2013. Water samples were collected monthly from surface water and analyzed for Temp, pH, electric conductivity, total hardness, Alkalinity, TDS (Total dissolved solid), chloride, DO (Dissolved o...

2004
A. R. Marcondes M. Ueda K. G. Kostov A. F. Beloto N. F. Leite G. F. Gomes C. M. Lepienski

Nitrogen Plasma Immersion Ion Implantation (PIII) has been used to modify the surface chemical structure of Ultra High Molecular Weight Polyethylene (UHMWPE). Grinding and polishing processes based on abrasive papers and alumina pastes have been evaluated with regard to their results on the improvement of polymer surface roughness, which has shown to be of crucial importance for hardness charac...

2009
Zvonimir Maksić Nick Sablon Frank de Proft Paul Geerlings

In this contribution, we have investigated the performance of the initial hardness response, a reactivity index from conceptual DFT, in the prediction of the allowed or forbidden character of a series of sigmatropic hydrogen shifts, which are traditionally explained using the famous Woodward-Hoffmann rules for pericyclic reactions. Previously, it was observed that this quantity can be linked to...

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