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991.
In the present study, the acid-base equilibria of N,O-carboxymethy chitosan abbreviated as (NOCC), is investigated. The complex
formation equilibria with the metal ions Cu(II), Ni(II), Co(II), Mn(II), and Zn(II) are investigated potentiometrically. The stability constant values of the binary and ternary complexes formed in solution
were determined and the binding centers of the ligands were assigned. The relationships between the properties of the studied
central metal ions as ionic radius, electronegativity, atomic number, and ionization potential, and the stability constants
of the formed complexes were investigated in an effort to give information about the nature of chemical bonding in complexes
and make possible the calculation of unknown stability constants. Cu(II), Ni(II), and U(VI) complexes with NOCC are isolated as solid complexes and characterized by conventional chemical and physical methods. The
structures of the isolated solid complexes are proposed on the basis of the spectral and magnetic studies. The ternary copper(II)
complexes involving NOCC and various biologically relevant ligands containing different functional groups, as amino acids
and DNA constituents are investigated. The stability constants of the complexes are determined and the concentration distribution
diagrams of the complexes are evaluated. 相似文献
992.
Sun YX Huang YX Li FL Wang HY Fan C Bao YL Sun LG Ma ZQ Kong J Li YX 《Chemistry Central journal》2012,6(1):2
Background
The virtual screening (VS) of lead compounds using molecular docking and pharmacophore detection is now an important tool in drug discovery. VS tasks typically require a combination of several software tools and a molecular graphics system. Thus, the integration of all the requisite tools in a single operating environment could reduce the complexity of running VS experiments. However, only a few freely available integrated software platforms have been developed. 相似文献993.
994.
One-step reaction compatibilized microfibrillar reinforced iPP/PET blends(CMRB) were successfully prepared through a "slit extrusion-hot stretching-quenching" process.Crystallization behavior and morphology of CMRB were systematically investigated.Scanning electronic microscopy(SEM) observations showed blurry interface of compatibilized common blend(CCB).The crystallization behavior of neat iPP,CCB,microfibrillar reinforced iPP/PET blend(MRB) and CMRB was investigated by differential scanning calorimetry(DSC) and polarized optical microscopy(POM).The increase of crystallization temperature and crystallization rate during nonisothermal crystallization process indicated both PET particles and microfibrils could serve as nucleating agents and PET microfibrils exhibited higher heterogeneous nucleation ability,which were also vividly revealed by results of POM.Compared with MRB sample,CMRB sample has lower crystallization temperature due to existence of PET microfibrils with smaller aspect ratio and wider distribution.In addition, since in situ compatibilizer tends to stay in the interphase,it could also hinder the diffusion of iPP molecules to the surface of PET phase,leading to decrease of crystallization rate.Two-dimensional wide-angle X-ray diffraction(2D-WAXD) was preformed to characterize the crystalline structure of the samples by injection molding,and it was found that well-developed PET microfibrils contained in MRB sample promoted formation ofβ-phase of iPP. 相似文献
995.
Electroactive conducting polymers for corrosion control 总被引:1,自引:0,他引:1
Dennis E. Tallman Geoff Spinks Anton Dominis Gordon G. Wallace 《Journal of Solid State Electrochemistry》2002,6(2):73-84
There is an intensive effort underway to develop new corrosion control coatings for structural metals. In part, this effort
has been motivated by the desire to replace chromium(VI)-containing coatings currently used for corrosion control of iron
and aluminum alloys. Cr(VI) has been shown to be hazardous to the environmental and to human health, and its use in many countries
will be sharply curtailed in the coming years. Electroactive conducting polymers (ECPs) represent a class of interesting materials
currently being explored for use in corrosion control coating systems, possibly as a replacement for Cr(VI)-based coatings.
The electroactivity and the electronic conductivity (or semiconductivity) of ECPs set them apart from traditional organic
coatings. As with chromate, interesting and potentially beneficial interactions of ECPs with active metal alloys such as steel
and aluminum are anticipated, with concomitant alteration of their corrosion behavior. A review of this active research area
will be presented in two parts. Here in Part 1, a general introduction to the topic of corrosion control by ECPs will be presented,
including an overview of corrosion and its control by traditional methods, an introduction to ECPs and their properties, and
a discussion of the processing issues surrounding the use of ECPs as coatings. Part 1 also includes a review of the literature
on the use of ECPs as coatings (or components of coatings) on non-ferrous active metals, principally aluminum and aluminum
alloys, although some work on zinc, copper, silver, titanium and silicon will also be described. In Part 2 of this review
(to be published in the next issue of this journal), the rather extensive literature on the use of ECPs for the corrosion
control of ferrous alloys (steels) will be reviewed.
Electronic Publication 相似文献
996.
The compositional zoning of the garnet in a strongly deformed eclogite from Raobazhai foliated peridotite has been recognized. The CaO concentrations of the garnet are decreased from the core to the rim, while its MnO concentrations are increased, suggesting the retrograde origin of such CaO—MnO zoning. The tie line of garnet + omphacite from this eclogite gives a Sm-Nd age of (187 ± 5) Ma, which is less significant than the Sm-Nd ages of (221±5)—(228 ± 3) Ma and (210 ± 6)—(214 ± 6) Ma for ultrahigh-pressure eclogites in the southern Dabie zone and in the northern Dabie zone, respectively. This younger Sm-Nd age could result from the143Nd/144 Nd ratio decrease of the retrograde zone in the garnet. The δ18O values of the garnet and omphacite show that their fractionation values are less than the equilibrium fractionation value between the garnet and omphacite at 500—900°C, which suggests an oxygen isotopic disequilibrium between them. 相似文献
997.
Yazhou Wang Lixin Wang Zhipeng Ma Lijun Gao Xucai Yin Ailing Song Xiujuan Qin Guangjie Shao Weimin Gao 《Journal of Solid State Electrochemistry》2018,22(10):2977-2987
MnO has a high theoretical capacity, moderate discharge plateau, and low polarization when it is used as the anode material in lithium battery. However, the issues that limit its application are its poor conductivity and large volume changes, which can easily result in the collapse of electrode structure during long-term cycling. In the present work, a carbon-coated MnO/graphene 3D-network anode material is synthesized by an electrostatic adsorption of dispersed precipitates precipitation method. The MnO nanoparticles coated by carbon are uniformly distributed on the surface of graphene nanosheets and form a 3D sandwich-like nanostructure. A carbon layer is coated on the surface of MnO nanoparticles, which slows down the volume expansion in the process of lithium intercalation. The graphene nanosheets are cross-linked through carbons in this 3D nanostructure, which provides mechanical support and effective electron conduction pathways during the charge-discharge. The electrochemical tests indicate that the prepared 3D carbon-coated MnO/graphene electrode exhibits an excellent rate capacity of 1247.3 and 713.2 mAh g?1 at 100 and 1000 mA g?1, respectively. The capacity is 792.2 mAh g?1 after long cycle at a current density of 1000 mA g?1. The specific capacity is higher than that of MnO-based composite lithium anode materials currently reported. The superior rate and cycling performances are attributed to the unique 3D-network structure, which provides an effectively conductive network, buffers volume expansion, and prevents falling and aggregation of MnO in the charge and discharge process of the electrode materials. The 3D-structured carbon-coated MnO/graphene anode material will have an excellent application prospect. 相似文献
998.
Da-Wei Fang Jian-tao Zuo Mei-Chen Xia Jun Li Jia-zhen Yang 《Journal of Thermal Analysis and Calorimetry》2018,133(2):1015-1021
The heat capacities of 1-butyl-3-methylimidazolium lactate ionic liquids ([C4mim][Lact]) were measured with a highly accurate automatic adiabatic calorimeter over the temperature range from 79 to 406 K. And the experimental values of molar heat capacities were fitted to a polynomial equation using least square method in the appropriate temperature ranges. The standard molar heat capacity was determined to be 1734.46?±?5.12 J K?1 mol?1 at 298.15 K. The molar enthalpy and molar entropy of the transition were determined to be 15.575?±?0.045 and 64.44?±?0.14 J K?1 mol?1. Other thermodynamic properties, such as (HT???H298.15) and (ST???S298.15), were also calculated. Furthermore, when the temperature reaches 241.87 K, the strongest peaks appeared by analysis of the heat capacity curve. This phenomenon could be explained from the interionic interaction, which is the hydrogen bond between the anions and cations. 相似文献
999.
Božidar Čobeljić Andrej Pevec Stepan Stepanović Milica R. Milenković Iztok Turel Maja Gruden Dušanka Radanović Katarina Anđelković 《Structural chemistry》2018,29(6):1797-1806
The isothiocyanato Zn(II) complex (1) and mixed isothiocyanato/thiocyanato Cd(II) complex (2) with the condensation product of 2-acetylpyridine and trimethylammoniumacetohydrazide chloride (Girard’s T reagent) (HLCl) were investigated both experimentally and theoretically. The crystal structures of both complexes showed tridentate N2O coordination of hydrazine ligand. In complex 1 square-pyramidal coordination surrounding of Zn(II) consists of deprotonated hydrazone ligand and two isothiocyanato ligands, while in octahedral Cd(II) complex ligand is coordinated without deprotonation as a positively charged species and coordination geometry is completed with two N-coordinated and one S-coordinated NCS? anions. NMR spectroscopy and molar conductivity results for Cd(II) and Zn(II) complexes indicated their instability in solution. DFT calculations were performed to explain coordination preference and stability of complexes 1 and 2 in solid state and in solution. The obtained Cd(II) complex is the first reported mononuclear pseudohalide/halide Cd(II) complex with quinoline-/pyridine-based hydrazone ligands possessing octahedral geometry in solid state. In this complex, H-bonding has significant impact on coordination number and supramolecular assembly in solid state. 相似文献
1000.
Miroslav Pohanka 《Chemical Papers》2015,69(1):4-16
Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) are enzymes expressed in the human body under physiological conditions. AChE is an important part of the cholinergic nerves where it hydrolyses neurotransmitter acetylcholine. Both cholinesterases are sensitive to inhibitors acting as neurotoxic compounds. In analytical applications, the enzymes can serve as a biorecognition element in biosensors as well as simple disposable sensors (dipsticks) and be used for assaying the neurotoxic compounds. In the present review, the mechanism of AChE and BChE inhibition by disparate compounds is explained and methods for assaying the enzymes activity are shown. Optical, electrochemical, and piezoelectric biosensors are described. Attention is also given to the application of sol-gel techniques and quantum dots in the biosensors’ construction. Examples of the biosensors are provided and the pros and cons are discussed. 相似文献