A novel dithiolene ligand appended with a 4,5-diazafluorene moiety has been synthesized and used for the preparation of discrete nickel and mercury complexes and a one-dimensional polymer in the presence of sodium cations. 相似文献
The proposed method is a simple process for the determination of trace amount of thallium(I) in the environmental wastewater samples by electrothermal atomic absorption spectrometry. The wastewater samples were obtained from the environment of a cement plant and subjected to a simple treatment, such as adjusting pH and masking the interfering ions, to prepare for the flotation process in which the thallium(I) content was floated as an ion-association complex using iodide and Rhodamine B at the interface of aqueous/cyclohexane layers. The floated layer was then separated and dissolved in 2 ml of a solution, which was 1% to H2SO4 and 50% to methanol, respectively. Aliquots of 10-microl of this solution were subjected to the graphite furnace to determine the thallium(I) content. The flotation process can be carried in a weak acidic medium in which the interfering effects owing to certain metal ions were eliminated by masking them as neutral citrate chelates. The dynamic range for the determination was found to be 1.0 x 10(-8) - 1.0 x 10(-7) mol l(-1). The RSD was 3.2% and the DL was 2.5 x 10(-9) mol l(-1) (calculated as 3SD of the blank). The reliability of the method is demonstrated by the analysis of a synthetic wastewater in which the recovery was found to be 94%. 相似文献
The combination of the chiral tecton based on the (R)-6,6'-dibromo-1,1'-binaphthyl moiety bearing two isonicotinoyl groups with AgX (X = BF4-, CF3SO3-, PF6-) leads to the formation of enantiomerically pure helical strands with orthogonal packing in the rare space group I2(1)3. 相似文献
Due to their wide applications as insecticides, pesticides, chemical warfare agents, etc., detection of organophosphorus compounds
is of great importance. This paper deals with application of polyaniline conducting polymer (PANi) as a sensor material for
detection of some agricultural organophosphorus compounds that are commonly used as insecticides and pesticides. The compounds
employed in this investigation are dichlorvos, trichlorophon, and chlorpyrifos. The effects of some important parameters such
as concentration, thickness of the polymer film, etc., on electrical conductivity and conductivity stability for these compounds
have also been investigated. In situ electrical conductivity measurements were performed using a standard direct-current (DC)
four-point probe technique. It was found that adsorption and desorption of these compounds on PANi film cause measurable change
in the resistance of conducting polymers. 相似文献
A new chelating polymeric sorbent as an extractant impregnated resin (EIR) has been developed using eosin B and Amberlite
IRA-410 resin. The impregnation process was characterized by FT-IR spectroscopy. The eosin B-impregnated resin showed superior
binding affinity for Th(IV) over U(VI) and many co-existing ions. The influence of various physicochemical parameters on the
recovery of Th(IV) were optimized by both static and dynamic methods. The Langmuir adsorption isotherm gave a satisfactory
fit of the equilibrium data. The kinetic studies performed for Th(IV) sorption revealed that <20 min was sufficient for reaching
equilibrium metal ion sorption. A preconcentration factor of 100 was found for the column-mode extraction. The accuracy of
the developed method in conjunction with Arsenazo III procedure was tested by analyzing geological reference materials and
seawater sample, which are prepared, synthetically. Furthermore, the above procedure has been successfully employed for the
analysis of natural water samples. 相似文献
In this paper, heat transfer characteristics of a miniature heat sink cooled by SiO2–water nanofluids were investigated both experimentally and numerically. The heat sink was fabricated from aluminum and insulated by plexiglass cover plates. The heat sink consisted of an array of 4 mm diameter circular channels with a length of 40 mm. Tests were performed while inserting a 180 W/cm2 heat flux to the bottom of heat sink and Reynolds numbers ranged from 400 to 2000. The three-dimensional heat transfer characteristics of the heat sink were analyzed numerically by solving conjugate heat transfer problem of thermally and hydrodynamically developing fluid flow. Experimental results showed that dispersing SiO2 nanoparticles in water significantly increased the overall heat transfer coefficient while thermal resistance of heat sink was decreased up to 10%. Numerical results revealed that channel diameter, as well as heat sink height and number of channels in a heat sink have significant effects on the maximum temperature of heat sink. Finally, an artificial neural network (ANN) was used to simulate the heat sink performance based on these parameters. It was found that the results of ANN are in excellent agreement with the mathematical simulation and cover a wider range for evaluation of heat sink performance. 相似文献
The formation of ion-acoustic solitons (IASs) in an unmagnetized plasma with negative ions has been investigated through the KdV equation in both the situations \(Q^{\prime}\left( { = m_{j} /m_{i} = {\text{negative}}\;{\text{to}}\;{\text{positive}}\;{\text{ion}}\;{\text{mass}}\;{\text{ratio}}} \right)\) less and greater than one and the mKdV equation only for \(Q^{\prime} > 1\). The existence of both KdV and mKdV solitons has been established for \(\alpha \left( { = {\text{ion}}\;{\text{to}}\;{\text{electron}}\;{\text{temperature}}\;{\text{ratio}}} \right)\; > \;\beta \left( { = {\text{negative}}\;{\text{ion}}\;{\text{to}}\;{\text{electron}}\;{\text{temperature}}\;{\text{ratio}}} \right)\) and \(\alpha < \beta\), which is the new outcome of the current investigation. Furthermore, the existence of both compressive and rarefactive solitons for \(Q^{\prime} > 1\) and \(Q^{\prime} < 1\) has been demonstrated.
The role of β-CoOOH crystallographic orientations in catalytic activity for the oxygen evolution reaction (OER) remains elusive. We combine correlative electron backscatter diffraction/scanning electrochemical cell microscopy with X-ray photoelectron spectroscopy, transmission electron microscopy, and atom probe tomography to establish the structure–activity relationships of various faceted β-CoOOH formed on a Co microelectrode under OER conditions. We reveal that ≈6 nm β-CoOOH(01 0), grown on [ 0]-oriented Co, exhibits higher OER activity than ≈3 nm β-CoOOH(10 3) or ≈6 nm β-CoOOH(0006) formed on [02 - and [0001]-oriented Co, respectively. This arises from higher amounts of incorporated hydroxyl ions and more easily reducible CoIII−O sites present in β-CoOOH(01 0) than those in the latter two oxyhydroxide facets. Our correlative multimodal approach shows great promise in linking local activity with atomic-scale details of structure, thickness and composition of active species, which opens opportunities to design pre-catalysts with preferred defects that promote the formation of the most active OER species. 相似文献