With electronegativity and hardness of an atom defined as 1/2(I + A) and 1/2(I - A), respectively, where I and A are the ionization potential and electron affinity, electronegativity difference and hardness sum are proposed as coordinates in structure stability diagrams. With these coordinates a successful topological classification of the crystal structures of octet and suboctet binary compoun...

Quantum calculations of the physical properties (electronic and vibrational), based on density functional theory (DFT) method at B3LYP/6-31G** level of theory, were performed, by means of the Gaussian 09 set of programs, to investigate the effect of the addition of the radical CN on pyridazine molecules. The best geometry, the total energy, frontier molecular orbital energies (HOMO and HUMO), e...

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 ...

The influence of water hardness and dissolved organic matter (DOM) on bioavailability of organic chemicals to Daphnia magna was studied by using benzo[a]pyrene (BaP), pyrene, atrazine, and 3,3',4,4'-tetrachlorobiphenyl (TCB) as model compounds. Two types of DOM were used, namely Lake Kontiolampi, Joensuu, Finland water (KL) and Nordic reference fulvic acid (NoFA) dissolved in artificial freshwa...

all aquatic organisms are directly or indirectly affected by the physical characteristics of their environment, especially the chemical composition of the water. the high concentration levels, damage tissues and interfere with the normal growth and proliferation. the aim of this research was to investigation acute toxicity of znso4 and cucl2 to gambusia holbrooki by static bioassays at differen...

background:the aim of this study is to investigate the association ofcalcium and magnesium concentration of drinking water with cardiovascular disease (cvds) in urban and rural areas of a city in iran. methods:this case-control study was conducted in 2012 in khansar county in isfahan province, iran. we used the official data of the provincial health center regarding the chemical analysis data o...

The validity of the maximum hardness principle (MHP) is tested in the cases of 50 chemical reactions, most of which are organic in nature and exhibit anomeric effect. To explore the effect of the level of theory on the validity of MHP in an exothermic reaction, B3LYP/6-311++G(2df,3pd) and LC-BLYP/6-311++G(2df,3pd) (def2-QZVP for iodine and mercury) levels are employed. Different approximations ...

Super-hard materials have been extensively investigated due to their practical importance in numerous industrial applications. To stimulate the design and exploration of new super-hard materials, microscopic models that elucidate the fundamental factors controlling hardness are desirable. The present work modified the theoretical model of intrinsic hardness proposed by Gao. In the modification,...

Diamond-like carbon (DLC) is a metastable form of amorphous carbon having large sp 3 bonding. DLC films have unique properties such as high hardness, low-friction, good transparency in IR region, chemical inertness and biocompatibility. To have better performance of the coating one should have proper selection of different parameters for deposition. In the present study, DLC films were deposite...

This investigation evaluated the effect of resin composite inlay/onlay thickness on the hardness of a group of eight dual-cure resin-based cements. Fourteen disc specimens measuring 6 mm in diameter and 2.5 mm thick were prepared from each of eight dual-cure cements: Adherence, Choice, Duolink, Enforce, Lute-It, Nexus, Resinomer and Variolink. Two specimens from each material were directly ligh...