Search results for " solution"
showing 10 items of 3084 documents
Amphiphilic Polysaccharide Block Copolymers for pH-Responsive Micellar Nanoparticles
2017
A full polysaccharide amphiphilic block copolymer was prepared from end group-functionalized dextrans using copper-mediated azide-alkyne click chemistry. Sufficient modification of the reducing end in both blocks was achieved by microwave-enhanced reductive amination in a borate-buffer/methanol solvent system. The combination of a hydrophilic dextran block with a hydrophobic acetalated dextran block results in an amphiphilic structure that turns water-soluble upon acid treatment. The material has a low critical micelle concentration and self-assembles in water to spherical micellar nanoparticles. The formed nanoparticles have a narrow size distribution below 70 nm in diameter and disassembl…
Identification of passive layers on Co in Alkaline solutions by photocurrent spectroscopy
2005
The photoelectrochemical behavior of passive films on Co has been studied as a function of the polarizing voltage and electrolyte composition. Passive layers formed at 0 V (standard hydrogen electrode, SHE) in 0.1 M NaOH consisted of Co(OH) 2 , whose bandgap value has been found to be 1.85 eV. Higher bandgap values (2.75 eV) have been measured for passive films formed in borate buffer at 0 V (SHE), which are mainly consist of CoO. The Eg values have been related to the film composition on the basis of a correlation between the bandgap of passive films and the electronegativity of their constituents.
Multi-Resource Management for Multi-Tier Space Information Networks: A Cooperative Game
2019
With the drastic increase of space information network (SIN) traffic and the diversity of network traffic types, the optimal allocation of the scarce network resources is of great significance for optimizing the SIN system capability. In this paper, we propose a multi-resource management method for multi-tier SIN using the cooperative Nash bargaining solution. Since the original problem is a non-convex problem, we firstly make logarithmic transition, and then find a tightest lower bound function to convert the initial problem into a convex one. In order to carry out the optimal bandwidth and power allocation in SIN, we construct a joint bandwidth and power allocation (JBPA) algorithm. Simul…
A correction method for dynamic analysis of linear systems
2004
Abstract This paper proposes an analytical method to improve the accuracy of the dynamic response of classically damped linear systems, as given by a standard truncated modal analysis. Upon computing the first m undamped modes of a n-degree-of-freedom system, two sets of equations in the Rn nodal space are built, which are uncoupled and govern the contribution to the response of the m computed modes and the remaining (n−m) unknown modes, respectively. The first set is solved in the Rm modal space by using the m available modes; the second set is solved in a reduced R(n−m) nodal space, without computing additional modes. Specifically, it is shown that the particular solution of the second se…
Utilization of waste sodium sulfate from battery chemical production in neutral electrolytic pickling
2021
Abstract Several industrial activities produce metal sulfates, which are controlled by strict limitations for wastewater concentrations of sulfate. One emerging area where these activities occur is the production of lithium-ion battery chemicals in which sodium sulfates are formed because of cathode precursor co-precipitation. Several solutions for sulfate removal exist, but one option is to reuse the sulfate side stream in other processes to increase circular economy and atom efficiency. In this paper, the reuse of sodium sulfate solution in a steel industry pickling solution is considered. Neutral electrolytic pickling experiments were carried out to compare the pickling behavior of the e…
A beam theory for layered composites subjected to uniformly distributed load
2015
A theory for multilayered composite beams undergoing transverse uniformly distributed loads is presented. The formulation starts by assuming a layer-wise kinematical model characterized by third order approximation of the axial displacements and fourth order approximation of the transverse displacements. By enforcing the point-wise balance equations as well as the interface continuity conditions, the layer-wise kinematical model is rewritten in terms of a set of generalized kinematical variables associated with the beam as a whole. Stress resultants are then obtained in terms of the generalized variables derivatives and of the normal stresses applied to the top and bottom surfaces of the la…
Silver(I), Copper(I) and Copper(II) Complex of the New N,Se-Chelate Ligand 2-Phenylselenomethyl-1H-benzimidazole: Electrochemistry and Structure
2009
Abstract. 2-Phenylselenomethyl-1H-benzimidazole (psbi) can form complexes in 2:1 ratio with coinage metal ions. Crystal structure analysis revealed a flattened metal coordination for [AgI(psbi)2](BF4) (1), approaching a distorted planar arrangement with weak Ag-Se bonds (d > 2.9 A) and confirmed as energy minimum by DFT calculations. The typical Jahn-Teller system [CuII(psbi)2Cl2] (2) exhibits a planar CuN2Cl2 core with weak Se---Cu---Se axial ligation (3.2944(8) A Cu--Se distance). The oxygen-sensitive compound [CuI(psbi)2](BF4) (3) exhibits electrochemically reversible oxidation in contrast to the silver(I) analogue 1.
Photocatalytic oxidation mechanism of benzonitrile in aqueous suspensions of titanium dioxide
2007
Abstract The photocatalytic oxidation of benzonitrile was carried out in aqueous suspensions (pH 11) of commercial polycrystalline TiO 2 (Merck and Degussa P25) irradiated by ultraviolet light. The rate of decomposition was dependent on the concentration of benzonitrile and followed a pseudo-first order kinetics. The complete mineralization of a 0.70 mM benzonitrile solution was achieved in ca. 8 h by using TiO 2 Degussa P25, whereas the substrate was only partially mineralized even after 14 h of irradiation in the presence of TiO 2 Merck. The final oxidation products were carbonate and nitrate. The appearance and the evolution of organic and inorganic intermediate species were also investi…
Coordinating properties of the Cephalexine antibiotic. A potentiometric study of the complexes formation between Cephalexine and Co(II), Ni(II) and C…
1989
Abstract The formation of complexes between Co(II), Ni(II) and Cu(II) with Cephalexine has been investigated using potentiometric techniques. The stability constants of the complexes formed were calculated using the non-linear least-squares computer program SUPERQUAD. The obtained values were: Co(II) logβ1=2.40, logβMLOH=8.89; Ni(II) logβ1=2.80, logβ2=5.10, logβML2OH=12.09; Cu(II) logβ1=4.094 (25 °C, 0.1 M KNO3). The compound [Ni(CEX)(OH2)4]BPh4 has been synthesized and characterized by electronic, IR and NMR spectroscopies as well as by magnetic measurements. From these studies it is proposed that the Cephalexinate anion acts as a bidentate ligand and is bound to the metal ion through the …
Cu2+and AMP complexation of enlarged tripodal polyamines
2006
The synthesis, characterization, Cu2+ coordination and interaction with AMP of three tripodal polyamines are reported. The polyamines are based on the structure of the tetraamine (tren) which has been enlarged with three propylamino functionalities (TAL), with a further anthrylmethyl fragment at one of its terminal primary nitrogens (ATAL) or with naphthylmethyl fragments at its three ends (N3TAL). The protonation constants of all three polyamines show that at pH 6, all six primary and secondary nitrogen atoms in the arms are protonated. The interaction with Cu2+ and AMP (adenosine-5′-monophosphate) has been studied by potentiometric, UV-Vis, ESI-MS spectroscopy and NMR techniques. pH-Metri…