Online Separation and Preconcentration of Gold and Palladium on Amidinothiourea Immobilized Glass Bead for Interference-Free Flame Atom Absorption Spectrometry Determination

Amidinothiourea immobilized glass bead (AGB) was applied as the microcolumn packing for the flow-injection online separation and preconcentration of Au(III) and Pd(II) coupled with FAAS determination. The peak-area absorbance (A) and the peak-height absorbance (H) were all used as the evaluating modes. Au(III) and Pd(II) in 0.50 M HCl solution were absorbed onto AGB completely and then eluted into AAS with thiourea solution. Base metal ions with a concentration of 2.0 mg/mL and anions with a concentration of 20.0 mg/mL caused no interference in the determination of Au(III) and Pd(II). The LODs of Au(III) and Pd(II) for a preconcentration time of 60 s with a sampling flow rate of 5.0 mL/min for 0.20 μg/mL of Au(III) and 0.30 μg/mL of Pd(II) were 2.7 and 6.5 ng/mL with the H mode and 4.6 and 10.2 ng/mL with the A mode, respectively. The RSD of seven replicate determinations of 0.20 μg/mL of Au(III) and 0.30 μg/mL of Pd(II) were 0.018 and 0.024 for the H mode and 0.013 and 0.018 for the A mode, respectively. The method was successfully applied to the determination of Au and Pd in real samples. __________ From Zhurnal Analiticheskoi Khimii, Vol. 60, No. 10, 2005, pp. 1023–1029. Original English Text Copyright ? 2005 by Liu, Pu, Su. The text was submitted by the authors in English.     

Synergistic Efficiency of Tricresyl Phosphate and Montmorillonite on the Mechanical Characteristics and Flame Retardant Properties of Polylactide and Poly(butylene succinate) Blends

The main aim of this research was to investigate the synergistic influence of additives and poly(butylene succinate) (PBS) in improving both the mechanical and flame retardant properties of polylactide (PLA) blends.Tricresyl phosphate (TCP) and montmorillonite (MMT) were the additives used to improve the mechanical characteristics and fire resistance of PLA.Differential scanning calorimetry (DSC) thermograms revealed that the addition of TCP and MMT significantly affected their thermal behaviors.The results of the mechanical and morphological characterizations were in agreement with the changes in thermal behavior.The impact strength and limiting oxygen index (LOI) value of PLA significantly increased with the presence of PBS.The failure mode of the blends as evidenced by scanning electron microscopy (SEM) changed from brittle to ductile.The addition of TCP and MMT produced excellent anti-dripping and self-extinguishing behaviors of the blends,achieving V-0 rating.For the PLA/PBS blends,the synergistic combination of PBS and additives led to an acceleration of cold crystallization,a significant increment of flexibility and impact toughness,and an improvement of flame retardancy.     

{[K.18-Crown-6]Br3}n:保护胺和醇的三溴化催化剂（英文）

{[K.18-Crown-6]Br3}n , a unique tribromide-type catalyst, was utilized for the N-boc protection of amines and trimethylsilylation (TMS) and tetrahydropyranylation (THP) of alcohols. The method is general for the preparation of N-boc derivatives of aliphatic (acyclic and cyclic) and aromatic, and primary and secondary amines and also various TMS-ethers and THP-ethers. The simple separation of the catalyst from the product is one of the many advantages of this method.     

In-situ reduction synthesis of manganese dioxide@polypyrrole core/shell nanomaterial for highly efficient enrichment of U(Ⅵ) and Eu(Ⅲ)

Radionuclides with long half-life are toxic,and thereby result in serious threat to human beings and ecological balance.Herein,a simple two-step synthesis method was used to prepare manganese dioxide@polypyrrole(Mn O_2@PPy)core/shell structures for efficient removal of U(Ⅵ)and Eu(Ⅲ)from aqueous solutions.The adsorption of U(Ⅵ)and Eu(Ⅲ)were investigated under different kinds of experimental conditions.The experimental results suggested that the adsorption of U(Ⅵ)and Eu(Ⅲ)on Mn O_2@PPy were greatly affected by p H.U(Ⅵ)adsorption on Mn O_2@PPy was independent of ionic strength at p H6.0,and dependent on ionic strength at p H6.0.However,Eu(Ⅲ)adsorption on Mn O_2@PPy was independent of ionic strength at the whole p H range of experimental conditions.The maximum adsorption capacities(q_(max))of U(Ⅵ)and Eu(Ⅲ)were 63.04 and54.74 mg g~(-1)at T=298 K,respectively.The BET,XRD,FTIR and XPS analysis evidenced that high adsorption capacities of U(Ⅵ)and Eu(Ⅲ)on Mn O_2@PPy were mainly due to high surface area and rich metal oxygen-containing group(i.e.,Mn–OH and Mn–O),and the interaction was mainly attributed to strong surface complexation and electrostatic interaction.This study highlighted the excellent adsorption performance of U(Ⅵ)and Eu(Ⅲ)on Mn O_2@PPy and could provide the reference for the elimination of radionuclides in real wastewater management.     

Manganese Oxide(MnO) and Cadmium Dioxide(CdO_2) Attached to Carbon Nanotube(8, 0) as Anodes of Metal-ion Batteries: a DFT Study

Performance of carbon nanotube(CNT) and their attached metal oxides(manganese oxide(MnO) and cadmium dioxide(CdO2)) structures as anode electrodes in lithium-ion battery(LIB) and potassium-ion battery(KIB) are investigated. The Gibbs free energy of adsorption of Li and K atoms/ions on surfaces of CNT(8, 0), CNT(8, 0)-MnO and CNT(8, 0)-CdO2 are calculated. The cell voltages(Vcell) of Li and K atoms/ions adsorption on studied surfaces are examined. The Vcell of LIBs with metal-oxides attached to CNT(8, 0) as anode electrodes are higher than those KIBs. The adsorbed metal oxides(MnO and CdO2) on CNT(8, 0) increased the charges, electronic conductivity and Vcell of LIB and KIB, efficiently. The CNT(8, 0)-CdO2 as anode electrodes in LIB and KIB is proposed.     

Studies on the Hydrogen Bonding Network Structures of Amino-konjacglucomannan-zinc Chelate

Amino-Konjacglucomannan(NH2-KGM) was prepared through the reaction of ammonium hydroxide with KGM by ultrasonic. The influence of amount of ammonium hydroxide, concentration of KGM and ultrasonic time on the extent of amination was studied. Then, NH2-KGM and zinc sulfate were used as materials for the preparation of NH2-KGM-Zn complex. The results indicated that the extent of amination increases with increasing the ammonium hydroxide. The optimum concentration of KGM and ultrasonic time are 0.3% and 75 min respectively. IR showed KGM is successfully aminated and NH2-KGM forms stable complex with zinc(Ⅱ). The hydrogen bonding network structures of NH2-KGM-Zn are more stable and the key linking points of hydrogen bonding network are at the OH(6) and O(3) positions of mannose and OH(2) of glucose and O(3) of mannose on the KGM ring. It is more favorable for NH2-KGM-Zn to form intermolecular hydrogen bonds between KGM.     

THE RELATIONSHIPS BETWEEN THE POLARIZING FORCE OF CATIONS AND THE ELECTROPHILIC CHARACTER AND CATALYTIC PERFORMANCES OF PROMOTED Pt-Al_2O_3 CATALYST

The electronic modification effect of various metal oxides over Pt-Al_2O_3 catalyst andthe relationships between the polarizing force of cations(PFC)and the electrophiliccharacter(EC)and catalytic performances(CP)of promoted Pt catalyst have been studiecby competitive hydrogenation reaction method(CHRM)and test reaction,i.e.hydrogena-tion of benzene and hydrogenolysis of cyclopentane.     

POLAR SUBSTITUENT EFFECTS OF ORGANOPHOSPHORUS ESTERS IN STRUCTURE-REACTIVITY STUDIES

In order to study the polar substituent effect almost with no steric effect in organophosphoruschemistry,a series of 4-substituted-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane 1-oxides(1)and p-substitutedphenylphosphonates(2)and corresponding mono hexyl esters(3)as model were synthesized.~(31)P-NMR chemicalshifts of compounds(1)in methanol and deuterioacetone were determined.The Δδ values reflect 4-sbstituent po-lar effect.The ~(31)P-NMR of compounds(2)and(3)and the pKa of compounds(3)were also measured.Theresults showed that the trend of polar effects of substituents in both carboxylic and organophosphates chemistryare similar,and the change of polar effects in variation with the alkyl groups is not significant.     

Photosensitized oxidation of tryptophan and tyrosine by aromatic ketones: A laser flash photolysis study

Photochemical processes of benzophenone (BP) and xanthone (XT) with tryptophan (TrpH) and tyrosine (TyrOH) were studied using the laser flash photolysis technique.It has been observed that the triplet state of BP and XT reacted with TrpH and TyrOH by hydrogen transfer with the formation of BP and XT ketyl radicals and oxidized radicals of TrpY and TyrOY.The related rate constants of these reactions were determined in this paper.The free energy changes (G) of these reactions suggested that the proposed hydrogen transfer mechanism was thermodynamically feasible.These results provide theoretical foundation for further studying structural effects on the photochemical behaviors of proteins with triplet state BP and XT.     

STUDIES ON REDOX PROPERTIES OF HETEROPOLY ACIDS (SALTS) AND THEIR DERIVATIVES WITH KEGGIN AND DAWSON STRUCTURES

We have systematically studied redox properties of two series of several dozen heteropoly acids (salts) and their derivatives with vanadium and rare-earth elements with Keggin and Dawson structures, e. g. LnHSiMo_(12), SiMo_(12-n)V_n, M_(1.5)PMo_(12), PMo_(12-n)V_n, PW_(12-n_V_n, Ln(PMo_(11))_2, Sm(XMo_(11))_2 and P_2Mo_(18-n)V_n, etc., and obtained their sequence of oxidation. It was found that there is a linear relationship between the reduction potentials of heteropoly anions and the derivatives of heteropoly anions with rare-earth elements with Keggin structure and nq~2 (n and q are the principal quantum number and charge of the central ion respectively). On the basis of the electrostatic model the regularity of oxidation and reduction was rationalized.     

CO-DEPOSITION OF Li(Ⅰ)WITH RE(Ⅲ)AND ITS APPLICATION IN THE PRODUCTION OF Al-Li-Cu-RE ALLOY BY MOLTEN SALT ELECTROLYSIS

The possibility of co-deposition of Li(Ⅰ)and RE(Ⅲ)has been estimated by boththeoretical analysis and experimental study on the influences of temperature and concen-tration of chloride on the deposition potential.Both the electrochemical and electrolyticresults clearly show that Li(Ⅰ)and RE(Ⅲ)can co-deposit on the Al-Cu electrode underselected conditions.     

THE SIMULTANEOUS DISCHARGES OF TWO NEURONS IN N. Pf AND RF AND THE INFLUENCES ON THEM BY STIMULATING CENTRAL GRAY MATTER

This paper employs the method of simultaneous recording of the electric discharges oftwo neurons with two microelectrodes to study the interrelationship of simultancous electricactivities of pain excitation neurons (PEN) and pain inhibition neurons (PIN) in N. parafas-cicularis (Pf) of thalamus and reticular formation (RF) of midbrain in 42 rats. The resultsprove: (i) There are both PEN and PIN in RF in midbrain and they act coordinately;(ii) noxious messages may simultaneously act on PEN and PIN in N. Pf and RF, and thereciprocal coordination of electric activities of these two kinds of neurons is very obvious;(iii) stimulating central gray matter or injecting morphine may weaken the activities ofPEN simultaneously, with the opposite effects on PIN.     

Orthogonal array optimization of ionic liquid based dispersive liquid-liquid microextraction for toxic anilines in foods

A simple and rapid method of ionic liquid based dispersive liquid-liquid microextraction(DLLME) combining with high performance liquid chromatography(HPLC) was developed for the analysis of four toxic anilines in flour steamed bread and maize steamed bread.Several possible influential factors such as the type of ionic liquid and disperser solvent,extraction time,sample pH,ionic strength and the volume of ionic liquid and disperser solvent were optimized using single factor experiments and orthogonal array design(OAD) with OA 25(5 4) matrix.Analysis of variance(ANOVA) and percent contribution(PC) were used to investigate the significance of the factors of OAD.Sample pH and ionic strength are statistically demonstrated two chief factors.Under the optimum condition,the method exhibits a good linearity(r 2 > 0.99) over the studied range(50-1000 ng g 1) for anilines.The extraction factors and recoveries for the anilines in two kinds of steamed breads ranged between 34.1%-73.3% and 44.3%-95.3%,respectively.The limit of detections(LODs) and limit of quantitations(LOQs) ranged between 10-15 ng g 1 and 30-45 ng g-1.     

DMS AND ~(13)C NMR STUDIES ON THE COMPATIBILITY AND DYNAMICS OF LATEX BIDIRECTIONAL IPNS AND LATEX IPN OF PVAc/PBA

The compatibility and dynamics of latex bidirectional/nterpenetrating polymer networks (LBIPNs) and latex IPN(LIPN) of poly(vinyl acetate)(PVAc) and poly (butyl acrylate )(PBA) are investigated by means of dynamic mechanical spectroscopy (DMS) and nuclear magnetic resonance (NMR) techniques. The results of DMS show that the compatibility of the LBIPNs is much better than that of the corresponding LIPN and depends to, a large extent on the distribution of PVAc both in the core and in the shell. The results of NMR measurements indicate that the rotational correlation times of the side- groups of PBA in the LBIPN are longer than those in the LIPN. The relation between the ~(13)C linewidths of PBA and temperature is also discussed.     

PHASE STRUCTURE AND COMPATIBILITY OF LADDERLIKE POLYPHENYLSILSESQUIOXANE (PPSQ)/POLYCARBONATE (PC) BLENDS PREPARED BY SOLUTION CASTING*

Blends of PC and PPSQ (A) with high M_w and good ladderlike regularity or PPSQ(B) withlow M_w and more defective Si-atoms in its structure have been prepared by solution casting. Thedispersed spheres (PPSQ(A)-rich) are unevenly dispersed in the continuous PC-rich phase and there isno phase-inversion as PPSQ(A) content increases when the percentage of PPSQ(A) is not more than70%. PPSQ(B)-rich spheres are evenly dispersed in the continuous phase (PC-rich) and phase-inversion occurs when PPSQ(B) percentage is up to 70%. T_g of PPSQ(A)/PC or PPSQ(B)/PC at somecompositions are lower than that of pure PC due to the enlarged free-volume of PC-rich phase becausesome spheres of rigid PPSQ chains are included in the PC-rich phase. PC and PPSQ(A) or PPSQ(B)are partially compatible. The compatibility of PC and PPSQ(B) is better than that of PC and PPSQ(A)with high M_w and good ladderlike regularity. Heat history has some influence on the T_gs andcompatibility of PPSQ(A)/PC and PPSQ(B)/PC blends.     

STUDIES ON THE DYNAMIC MECHANICAL BEHAVIOR OF POLYMERIZATION OF BIS(4-(4-ETHYNYLPHENOXY)PHENYL)SULFONE AND ITS POLYMERS

The dynamic mechanical behavior and structural characteristics of polymerization bis(4-(4-ethynylphenoxy)phenyl)sulfine(ESF) and its polymers were investigated by means of tcrsional braid analysis(TBA) and infrared spectroscopy.Results show that the multiple transitions including the melting,low-temperature and high-temperature reactions of ESF oligomers,glass transition and decomposition reaction of resulted polymer can be characterized in the TBA spectra.The glass transition tempe: atures and structural characteristics of ESF polymers depend upon the conditions of polymerization.     

Effect of Endothelin, Angiotensin Ⅱ and ANP on Proliferation of Vascular Smooth Muscle Cells and Cardiomyocytes

By means of cell culture, ~3H-thymidine (~2H-TdR) incorporation and c-fos oncogene dot plotting technique, it was found that endothelin (ET) and angiotensin (ANG Ⅱ) could promote proliferation and DNA synthesis of cultured vascular smooth muscle cells (VSMCs) and myocardial cells, and stimulate expression of c-fos oncogene of VSMCs. However, atrial natriuretic peptide (ANP) antagonizes the above effects of ET and ANG Ⅱ.     

Atomic absorption spectrometric determination of Fe(III) and Cr(III) in various samples after preconcentration by solid-phase extraction with pyridine-2-carbaldehyde thiosemicarbazone

An atomic absorption spectrometric method for the determination of Fe(III) and Cr(III) after solid-phase extraction of their Schiff-base chelates by a column procedure with Amberlite XAD-4 was developed. A Schiff base, pyridine-2-carbaldehyde thiosemicarbazone (PCTSC), was synthesized and used as a chromogenic reagent for solid-phase extraction of Fe(III) and Cr(III) ions in the column procedure. The influence of various analytical parameters including the amount of solid phase, pH, type of elution solution, volume of sample solution, and flow rate of sample solution on the extraction efficiency of analytes were investigated. The recoveries of Fe(III) and Cr(III) were 99 ± 1 and 98 ± 2%, respectively, at the 95% confidence level under the optimum conditions. Fe(III) and Cr(III) were preconcentrated up to 25-fold. The limit of detection of Fe(III) and Cr(III) are 4.1 and 3.72 μg/L, respectively. The proposed method was applied to the determination of these metal ions in tap water, river water, Atatürk Dam water, and alloy samples. The relative standard deviation and the relative error are lower than 6%. The text was submitted by the authors in English.     

SBR composites reinforced with <Emphasis Type="Italic">N</Emphasis>-isopropyl-<Emphasis Type="Italic">N</Emphasis>′-phenyl-<Emphasis Type="Italic">P</Emphasis>-phenylenediamine-modified clay

SBR compounds including the N-isopropyl-N’-phenyl-p-phenylenediamine-modified clay(organoclay) were prepared.Effects of modified clay and antioxidant(IPPD) contents on mechanical and rheological properties of SBR composites were studied.FTIR results confirmed that the clay was chemically modified by IPPD and changed into an organoclay.X-ray diffraction(XRD) results confirmed the increase in interlayer distance of the clay due to the insertion of IPPD.Rheological and cure characteristics of SBR compounds were determined using RPA(Rubber Process Analyzer) and rheometer.Scorch time and cure time of SBR compounds decreased with introduction of the organoclay.Mechanical properties and heat aging resistance of the SBR composites were improved significantly by incorporation of the organoclay.