The radiation-induced grafting of low-density polyethylene in contact with styrene solution was studied. The effect of the degree of swelling of the polymer on the rate of grafting was investigated by diluting the styrene with methanol and with n-octane. For styrene-methanol solution, the rate of grafting was found to increase with degree of swelling, passing through a maximum when the sorbed solvent reaches 6.2 wt-% (70 vol-% methanol in the outside solution) and decreasing therafter. The methanol fraction of the sorbed liquid is far too small to cause precipitation of the grafted chains and inhibition of their termination rate. The dilution of styrene by octane has no effect on the swelling of polyethylene, but it decreases the grafting rate over the entire concentration range. The results are explained in terms of the concentration of sorbed monomer and the viscosity of the amorphous region of the polyethylene swollen by nonpolar liquids. Supporting evidence for the mechanism is presented in the form of grafting kinetic data as a function of dose rate (2.8 × 102?9.5 × 104 rad/hr), and post-irradiation grafting measurements for polyethylene in methanol-styrene (70/30, v/v). The data indicate that at the maximum grafting rate an optimum is achieved between a high concentration of sorbed monomer and a low viscosity for the poorly swelled polymer matrix. 相似文献
Arylidene-anthranilic acidSchiff base complexes with Th(IV), UO2(II), La(III), Ce(III), and Zr(IV) have been isolated and studied by several techniques, e.g. elemental analysis, electronic and IR spectra and conductance measurements. It is concluded that the salicylideneanthranilic acidL3 is coordinated to the metal ion as bivalent tridentate ONO ligand (L–2) while the other ligands behave as monovalent bidentate ON ligands. Furthermore, the molecular structure effect of these compounds on their tendency towards complex formation was investigated and discussed. The possibility that the Cu(II) complex ofL3 can act as bidentate ligand, coordinating through itscis-oxygen atoms to form binuclear metal complexes was studied.
Ein- und zweikernige Metall-Komplexe von Aryliden-Anthranilsäure-Schiff-Basen
Zusammenfassung Es wurden Aryliden-Anthranilsäure-Schiff-Basen mit Th(IV), UO2(II), La(III), Ce(III) und Zr(IV) isoliert und mittels Elementaranalysen, Elektronen-und IR-Spektroskopie und Leitfähigkeitsmessungen untersucht. Es wird aus den Untersuchungen geschlossen, daß Salicylidenanthranilsäure (L3) als bivalenter dreizähniger ONO-Ligand (L–2) an das Metallion koordiniert, währenddessen die anderen Liganden als monovalente zweizähnige Liganden agieren. Außerdem wurden Struktureffekte dieser Verbindungen in bezug auf ihre Komplexbildungstendenz untersucht. Die Möglichkeit, daß der Cu(II)-Komplex vonL3 über die Koordination mit dencis-Sauerstoff-Atomen und unter Bildung eines zweikernigen Metallkomplexes als zweizähniger Ligand agieren kann, wurde untersucht.
The extraction behavior of Zr(IV), Ce(III), Th(IV) and U(VI) from aqueous solutions containing Arsenazo-I with the organic solvents tridodecylamine (TDA), 1-[thenoyl-(2)]-3-3-3-trifluoroacetone (HTTA), di(2-ethylhexyl) phosphoric acid (HDEHP) and tricaprylmethylammonium chloride (TCMA) in xylene has been investigated. Effect of hydrogen ion concentration in the aqueous phase, Arsenazo-I concentration, as well as the effect of solvent concentration on the extraction was studied. Some alternatives for separation of the elements studied were recommended enabling the spectrophotometric determination of these elements using Arsenazo-I without interference. 相似文献
A sensitive and reproducible technique is reported for the determination of gold in tissue by carbon-furnace atomic-absorption spectrometry. Results are compared with those obtained by using a flame-atomization procedure and by neutron-activation analysis. The method is used to analyse samples of kidney, liver, spleen, nails and hair from human subjects. A possible correlation between gold levels in nails and plasma is suggested. 相似文献
Electrospray ionization (ESI) and collisionally induced dissociation (CID) mass spectra were obtained for five tetracyclines and the corresponding compounds in which the labile hydrogens were replaced by deuterium by either gas phase or liquid phase exchange. The number of labile hydrogens, x, could easily be determined from a comparison of ESI spectra obtained with N2 and with ND3 as the nebulizer gas. CID mass spectra were obtained for [M + H]+ and [M - H]- ions and the exchanged analogs, [M(Dx) + D]+ and [M(Dx) - D]- , and produced by ESI using a Sciex API-III(plus) and a Finnigan LCQ ion trap mass spectrometer. Compositions of product ions and mechanisms of decomposition were determined by comparison of the MS(N) spectra of the un-deuterated and deuterated species. Protonated tetracyclines dissociate initially by loss of H2O (D2O) and NH3 (ND3) if there is a tertiary OH at C-6. The loss of H2O (D2O) is the lower energy process. Tetracyclines without the tertiary OH at C-6 lose only NH3 (ND3) initially. MSN experiments showed easily understandable losses of HDO, HN(CH3)2, CH3 - N=CH2, and CO from fragment ions. The major fragment ions do not come from cleavage reactions of the species protonated at the most basic site. Deprotonated tetracyclines had similar CID spectra, with less fragmentation than those observed for the protonated tetracyclines. The lowest energy decomposition paths for the deprotonated tetracyclines are the competitive loss of NH3 (ND3) or HNCO (DNCO). Product ions appear to be formed by charge remote decompositions of species de-protonated at the C-10 phenol. 相似文献
Halloysite nanotube (HNT) which is cheap, natural, and easily accessible 1D clay, can be used in many applications, particularly heat transfer enhancement. The aim of this research is to study experimentally the pool boiling heat transfer (PBHT) performance of novel halloysite nanofluids at atmospheric pressure condition from typical horizontal heater. The nanofluids are prepared from halloysite nanotubes (HNTs) nanomaterials-based deionized water (DI water) with the presence of sodium hydroxide (NaOH) solution to control pH = 12 to obtain stable nanofluid. The nanofluids were prepared with dilute volume concentrations of 0.01–0.5 vol%. The performance of PBHT is studied via pool boiling curve and pool boiling heat transfer coefficient (PBHTC) from the typical heater which is the copper horizontal tube with a thickness of 1 mm and a diameter of 22 mm. The temperatures of the heated tube surface are measured to obtain the PBHTC. The results show an improvement of PBHTC for halloysite nanofluids compared to the base fluid. At 0.05 vol% concentration, HNT nanofluid has the best enhancement of 5.8% at moderate heat flux (HF). This indicates that HNT is a potential material in heat transfer applications. 相似文献
Determination of flavonoid markers quercetin, hesperetin, and chrysin, found in north Iranian citrus honey samples, was carried out by solid phase extraction (SPE) and isocratic liquid chromatographic separation using central composite design. Optimum conditions for SPE were achieved using 10 mL methanol/water (13:87, v/v, pH = 7) as the washing solvent and 4 mL methanol for elution. Good clean-up and high recovery >90% were observed for all analytes. The use of water/ACN/THF/AcOH (54:36:5:5, v/v) was found to serve as the optimum mobile phase composition and allowed for the separation of analytes from endogenous compounds present in honey. SPE parameters, such as maximum loading capacity and breakthrough volume, were also determined for each analyte. Limit of detection, linear range, recovery, repeatability of retention times, and peak heights were 3.11 × 10−8–4.44 × 10−8 g g−1, 0.50–50.0 μg mL−1 (R2 > 0.99), 90.7–96.9%, 3.0–3.6%, and 1.0–2.6%, respectively. Precision of the overall analytical procedure, estimated by five replicate measurements for quercetin, hesperetin and chrysin in citrus honey, as well as the relative standard deviations were 4.3%, 3.8%, and 5.5%, respectively.
Recently, it has been discovered that symbolic algebraic manipulations can be performed on the computer with input/output data in symbolic form. Accordingly, and for slightly nonlinear two-point boundary-value problems, it is feasible to obtain approximate analytical solutions in the form of power series in a small parameter. In these solutions, the boundary values are presented in a literal form. In this paper, the Lie canonical transformation is applied to derive approximate optimal solutions for slightly nonlinear systems with quadratic criteria. The transformation generator is determined by simple partial differential equations of the first order. To determine the arbitrary constants of the transformation in terms of the two-point boundary values, inversion of a vectorial power series in a small parameter is required, and a recursive algorithm for this inversion is given. To express the final solution in terms of these boundary values, a substitution of the inverted vectorial power series into another vectorial power series is also necessary, and a recursive algorithm for this substitution is presented.The authors are indebted to Professor J. V. Breakwell for his suggestions. 相似文献
Wave motion in an elastic layer has been analyzed conventionally either in terms of normal (discrete and continuous) mode spectra or in terms of ordinary or generalized ray fields. Either of these representations is inconvenient for describing the motion over the entire range of observations from early to late arrivals. A recently developed hybrid formulation, wherein modal fields, ray fields and a remainder are combined according to specified criteria within a single rigorous framework, overcomes these difficulties, Combinations may be chosen that ensure smooth passage from the ray phase at early times to the modal phase at later times. The method is illustrated here on the two-dimensional time-dependent SH Green's function for a homogeneous sediment layer above a higher velocity homogeneous semi-infinite bedrock, with the source located in the sediment. The hybrid fields may include various combinations of trapped modes, leaky modes, trapped rays, leaky rays, and lateral rays (head waves). This study complements an earlier investigation wherein the source was located in the bedrock. 相似文献