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51.
ICP-AES determination of trace elements after preconcentrated with p-dimethylaminobenzaldehyde-modified nanometer SiO2 from sample solution 总被引:1,自引:0,他引:1
A new method that utilizes p-dimethylaminobenzaldehyde-modified nanometer SiO2 (SiO2-p-DMABD) as a solid phase extractant has been developed for simultaneous preconcentration of trace Cr(III), Cu(II), Fe(III) and Pb(II) prior to the measurement by inductively coupled plasma atomic emission spectrometry (ICP-AES). The preconcentration conditions of analytes were investigated, including the pH value, the shaking time, the mass of sorbent, the sample flow rate and volume, the elution condition and the interfering ions. The adsorption capacity of nanometer SiO2-p-DMABD was found to be (mg g− 1) Cr(III): 6.2, Cu(II): 18.6, Fe(III): 4.7 and Pb(II): 6.0 at pH 4. The adsorbed metals were quantitatively eluted with 4 mL of 1.0 mol L− 1 HCl. According to the definition of IUPAC, the detection limits (3σ) of this method for Cr(III), Cu(II), Fe(III) and Pb(II) were 0.79, 1.27, 0.40 and 1.79 ng mL− 1, respectively. The proposed method achieved satisfied results when it was applied to the determination of trace Cr(III), Cu(II), Fe(III) and Pb(II) in biological and water samples. 相似文献
52.
The dynamics of metal-to-ligand charge transfer (MLCT) in a cis-bis(4,4'-dicarboxy-2,2'-bipyridine)-bis(isothiocyanato)ruthenium(II) dye (N3) are compared for the free dye in solution and the dye adsorbed on the surface of the TiO(2) nanoparticles from resonance Raman spectroscopy. The 544-nm MLCT absorption band of N3 adsorbed on TiO(2) is slightly blue-shifted from that of the free N3, indicating a weak electronic coupling between N3 and TiO(2). The resonance Raman spectra of N3 and the N3|TiO(2) complex obtained upon excitation within the lowest-lying MLCT singlet state of the dye are similar except for slight shifts in band positions. Resonance Raman cross sections have been obtained for the vibrational modes of both N3 and N3|TiO(2) with excitation frequencies spanning the 544-nm MLCT band. Self-consistent analysis of the resulting resonance Raman excitation profiles and absorption spectrum using a time-dependent wave packet formalism over two electronic states yields mode-specific vibrational and solvent reorganization energies. Despite the weak electronic coupling between N3 and TiO(2) in N3|TiO(2), adsorption strongly affects the reorganization energies of N3 in the intramolecular MLCT state. Adsorption of N3 onto TiO(2) increases the absolute Raman cross section of each mode by a factor of ca. 1.6 and decreases the vibrational and solvent reorganization energies by factors of 2 and 6, respectively. The excited-state dynamics of N3 adsorbed on the surface of TiO(2) nanoparticles were observed to be independent of the number of N3 molecules adsorbed per TiO(2) nanoparticle. The effect of TiO(2) on the dynamics of the adsorbed N3 is primarily due to both mode-specific vibrational and electronic pure dephasing, with the dominant contribution from the latter process. 相似文献
53.
Microchip-based proteomic analysis requires proteolytic digestion of proteins in microdevices. Enzyme reactors in microdevices, fabricated in glass, silicon, and PDMS substrates, have recently been demonstrated for model protein digestions. The common approach used for these enzyme reactors is employment of a syringe pump(s) to generate hydrodynamic flow, driving the proteins through the reactors. Here we present a novel approach, using electroosmotic flow (EOF) to electrokinetically pump proteins through a proteolytic system. The existence of EOF in the proteolytic system packed with immobilized trypsin gel beads was proven by imaging the movement of a neutral fluorescent marker. Digestions of proteins were subsequently carried out for 12 min, and the tryptic peptides were analyzed independently using capillary electrophoresis (CE) and MALDI-TOF mass spectrometry (MS). The results from CE analysis of the tryptic peptides from the EOF-driven proteolytic system and a conventional water bath digestion were comparable. MALDI-TOF MS was used to identify the parent protein and the tryptic peptides using MS-Fit database searching. The potential utility of the EOF-driven proteolytic system was demonstrated by direct electro-elution of proteins from an acrylamide gel into the proteolytic system, with elution and tryptic digestion achieved in a single step. The EOF-driven proteolytic system, thus, provides a simple way to integrate protein digestion into an electrophoretic micro total analysis system for protein analysis and characterization. 相似文献
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Nucleation and growth during bulk electrodeposition is studied using kinetic Monte Carlo (KMC) simulations. Ion transport in solution is modeled using Brownian dynamics, and the kinetics of nucleation and growth are dependent on the probabilities of metal-on-substrate and metal-on-metal deposition. Using this approach, we make no assumptions about the nucleation rate, island density, or island distribution. The influence of the attachment probabilities and concentration on the time-dependent island density and current transients is reported. Various models have been assessed by recovering the nucleation rate and island density from the current-time transients. 相似文献
57.
Guo‐Fu Chen Chang‐Heng Tan Zhu‐Lian Li Shan‐Hao Jiang Da‐Yuan Zhu 《Helvetica chimica acta》2003,86(3):787-792
Pseudolarolides O ( 1 ) and P ( 2 ), two novel triterpenoids with a cycloartane‐type framework, were isolated from the seeds of Pseudolarix kaempferi Gord. (Pinaceae). Their structures were elucidated as (16R,23S,25R)‐16,23‐epoxy‐3,4 : 9,10‐disecocycloartan‐1(10),9(11)‐diene‐3(4),26(23)‐diolide ( 1 ), and (9S,16R,23S,25R)‐1,9 : 16,23‐diepoxy‐8,9 : 9,10‐disecocycloartan‐1(29),5(6),10(19)‐triene‐3(4),26(23)‐diolide ( 2 ), respectively, on the basis of spectroscopic techniques and X‐ray‐diffraction studies. 相似文献
58.
The reactions of CpRu(dppf)Cl (1) with the sulfur-containing ligands, thiophenol HSPh, 2-mercaptopyridine C5H4N(SH), thiourea SC(NH2)2, vinylene trithiocarbonate SCS(CH)2S and ethylene trithiocarbonate SCS(CH2)2S, yielded chloro-substituted derivatives, viz. the mono-ruthenium(II) complexes CpRu(dppf)(SPh) (2), [CpRu(dppf)(SC5H4NH)]BPh4 (3)BPh4, [CpRu(dppf)(SC(NH2)2]PF6 (4)PF6, [CpRu(dppf)(SCS(CH)2S)]Cl (5)Cl and [CpRu(dppf)(SCS(CH2)2S)]Cl (6)Cl, respectively. Treatment of 1 with AuCl(SMe2) in the presence of NH4PF6 gave [(CpRu(dppf)(SMe2)]PF6 (7)PF6. The reaction of 1 or 6 with SnCl2 resulted in cleavage of chloro and dithiocarbonate ligands, respectively, to give CpRu(dppf)SnCl3 (8). All complexes were spectroscopically characterized and the structures of 2 and cationic complexes 4-7 were determined by single-crystal diffraction analyses. 相似文献
59.
Yan Ping Wang Wen Fa Xie Bin Li Wen Lian Li 《中国化学快报》2007,18(12):1501-1504
A new 1,3,4-oxadiazole-contanining rhenium(I) complex,with the formula [Re(CO)_3(Bphen)(PTOP)],(Bphen=bathophe- nardine,PTOP=4-(5-p-tolyl-1,3,4-oxadiazd-2-yl)pyridine),is synthesized and characterized by elemental analysis,IR,~1H NMR, UV-vis and luminescence spectroscopy.The double-layer electroluminescence devices based on the Re(I) complex have been fabricated by spin-coating technique.The turn-on voltage,maximum efficiency,and brightness for green emission obtained from the devices are 9V,2.1cd/A and 165cd/m~2,respectively. 相似文献
60.
纳米尺寸团簇NinZrn(n=3~5)的几何结构与成键规律研究 总被引:3,自引:0,他引:3
根据化学键理论与拓扑原理,设计了团簇NinZrn(n=3-5)的可能几何构型,并用从头算方法进行构型优化,结果表明,由NiZr组成的团簇原子间的Zr-Zr和Zr-Ni键明显较强,而Ni-Ni的成键较弱,并发与NinZrn(n=3-5)团簇电子性质与有机烯烃分子等瓣相似,原子之间的成键按照强弱相间的规则分布。 相似文献