Assay of Acetylcholinesterase Activity and Electrochemical Determination of Fenthion in Oil-in-water Emulsion

Organophosphates (OPs) have been widely used as pesticides,insecticides or even chemical warfare agents.Acetylcholinesterase (ACHE) inhibition has been employed to develop verious assay methods for detection of pesticides with the advantages of low cost,simple procedure and quick assay time.The study of acetylcholinesterase (ACHE) activity and OPs inhibition in the solution containing organic solvent is extremely important owing to poor solubility of Ops in water and a higher solubility in organic solvents.     

Studies on Middle-Phase Microemulsions of Green Surfactant n-Dodecyl Polyglucoside C12G1.46

The three-phases behavior in the quaternary stsem of n-dodecyl polyglucoside C12G1.46/1-butanol/cyclohexane/water has been studied at 40℃ in terms of the variables γ and δ.Increasing δ at constant γcauses a phase inversion from an oil-in-water microemulsion in contact with excess oil(winsor I or 2) to a water-in-oil microemulsion in contact with excess water (winsor Ⅱor 2)via a middle-phase microemulsion in contact with excess oil and water(winsor Ⅲor 3).By taking into account the different solubilities of alkyl polyglucoside and 1-butanol in the oil phase,the composition of the hydrophile-lipophile balanced interfacial film in the middle of the three-phase body can be calculated.The effects of different oils and aqueous media on the phase behavior and on the composition of the interfacial film and the efficiency for alkyl polyglucoside to make equal weights of water and oil to a single phase were investigated.It was found that the oil molecules with small molecular volumes can improve the solubilizing efficiency of the surfactant to form single-phase microemulsion.In inorganic salt(NaCl) and acid(HCl) solutions,less 1-butanol is needed than that in alkali(NaOH) solution to form middle-phase microemulsion.     

1-萘甲酰苯胺和2-萘甲酰苯胺的分子内电荷转移研究

A series of 1-naphthanilides (1) and 2-naphthanilides (2) with varied substituents at the para- or meta-position of anilino phenyl ring were prepared and their absorption and fluorescence spectra in a nonpolar solvent cyclohexane were investigated. An abnormal long wavelength emission assigned to the charge transfer (CT) state was found for all of the prepared naphthanilides in cyclohexane. A linear free energy correlation between the CT emission energies and the Hammett constants of the substituent was found within series 1 and 2. The value of the linear slope with 1 (0.42 eV) was higher than that with 2 (0.32 eV) being close to that of the substituted benzanilides 3 (0.31 eV) The higher slope value suggested higher charge separation extent in the CT state of 1 than that of 2. It was found that the corresponding linear slope of anilino-substituted benzanilides remained unchanged when para-, meta-, ortho-, or ortho, ortho-methyls were introduced into the anilino moiety, which ruled out the possible contribution of the difference in the steric effect and the electron accepting ability of the naphthoyl acceptor in 1 and 2. Compared with the early reported N-substituted-benzoyl-aminonaphthalene derivatives 4 and 5, it was considered that 1-naphthoyl enhanced the charge transfer in 1 and the proximity of its ^1La and ^1Lb states was suggested to be responsible. It was shown that 1- and/or 2-substituted naphthalene cores acting as either electron acceptor (naphthoyl) or electron donor (aminonaphthalene) were different in not only electron accepting (donating) ability but also shaping the charge transfer pathway.     

TRANSESTERIFICATION OF POLY(ETHYLENE TEREPHTHALATE) WITH POLY(ε-CAPROLACTONE)*

Transesterification of poly(ethylene terephthalate) (PET) with poly(ε-caprolactone) (PCL) was investigated bymeans of NMR spectroscopy, extraction experiments, differential scanning calorimetry (DSC) and phase contrast microscopy(PCM). The ~1H-NMR results show that transesterification takes place in the melt blends and leads to the formation of thePET-PCL copolyester with a chemical structure similar to ethylene terephthalate-ε-caprolactonc copolycster (TCL)synthesized directly from monomers. However, even in the blend that has been transesterified for 8 h, the random PET-PCLcopolyester, PET-PCL copolyester with long PET or long PCL segments and the unreacted PET and PCL homopolymersmay coexist. Due to the low mobility of PET and PCL chains and the high viscosity of the two macromolecules, thetransesterification proceeds with difficulty. Furthermore, PET is incompatible with PCL, the transesterification can onlyoccur at the interface or in the interfacial region between two phases, and finally the reaction can only reach a localequilibrium. These results indicate that in fact the transesterification in the melt blend between two incompatiblehomopolymers could not lead to the formation of completely random or typical block copolyesters.     

An Efficient Procedure for Esterification of Aryloxyacetic Acid and Arylthioacetic Acid Catalyzed by Silica Sulfuric Acid

Aryloxyacetate and arylthioacetate are wildly used in herbicides, plant regulator and insecticides. Recently, Wille et al. have reported that methyl aryloxyacetate is an efficient agent to prevent and treat allergic contact dermatitis.[1] The most popular synthesis is by heating sodium phenoxide (mercaptide) with ethyl chloroacetate in DMF,[2] or by the esterification of acid with alcohol using concentrated H2SO4 as catalyst.[3] In this paper, synthesis of aryloxyacetate and aryl thioacetate from aryloxyacetic acid and arylthioacetic acid respectively in ether catalyzed by silica sulfuric acid in 83%～94% yields is described. The catalyst is reused for 3 times without significant loss of activity (Entry 4). Compared with common procedures, the present procedure possesses the advantages of the operational simplicity, short reaction time,less-corrosion, high yield and reusable catalyst.     

COPOLYMER OF 1-(ACETYLSALICYLYLOXY)ETHYL METHACRYLATE AND ITS HYDROLYSIS

The copolymers of 1-(acetylsalicylyloxy)ethyl methacrylate (HEMA-ASA) with methacrylicacid (MA) have been prepared and their hydrolysis in dioxane-H_2.O either in acdic or alkaline medium,at 60℃or 37℃have been investigated. It is found that the chief product of hydrolysis is alwaysaspirin with minor amount of salicylic acid. Due to its neighbouring group effect, the hydrolysisrate of (HEMA-ASA)-MA copolymer markedly depends on its composition and the pH value ofhydrolysis medium, i.e. the hydrolysis rate increases with increasing mole fraction of MA in the copoly-mer and pH value of hydrolysis medium.     

Cuprous Iodide Catalyzed Synthesis of Diaryl Selenide and Telluride from Organoboronic Acids with Diphenyl Diselenide and Ditelluride

Organoselenium and tellurium compounds have received much attention not only as synthetic reagents or intermediates in organic synthesis but also as promising donor molecules for conductive materials.[1] A number of synthetic methods have been reported to prepare organoselenium and tellurium derivatives. A convenient and general method to introduce a selenium or tellurium moiety into organic molecules is the reaction of a metal selenolate or tellurolate with appropriate electrophiles such as organic halides, acyl chlorides, epoxides, and α, β-enones.[2] However, it is difficult to synthesize the unsymmetrical diarylselenides and tellurides through the reaction of selenide anion with organic halides because of the less reactivity of aryl halides. To accomplish this purpose, the reaction (iodobenzene with phenylselenol)was generally carried out in the presence of catalysts, ligands and strong bases. But, the reaction needs longer time to accomplish and form the products in moderate yields.     

Synthesis and Characterization of Poly-Ortho-Methylaniline With Different Degrees of Oxidation

Poly-ortho-methylanilines (POT) in three states fully oxidized, fully reduced and oxidized in varying degrees were synthesized by the reaction of common POT (C-POT) having nearly equal amounts of benzenediamine and quinonediimine units with iodine or phenylhydrazine, and the resulting polymers were characterized by IR,~(13)C-NMR, SEM and elemental analysis. The results showed that the quinonediimine unit in C-POT could be reduced by phenylhydrazine to the benzenediamine unit,forming the polymer with low OD (oxidation degree) or in a fully reduced state and that iodine-oxidation resulted in the increase of quinonediimine unit and decrease of benzenediamine unit. The solubility and flexibility of the formed polymers depend strongly on the amount of quinonediimine unit in it. It is necessary to reduce the content of quinonediimine structure unit in order to improve the solubility of aniline-class polymers.     

Probing the Subunit-Subunit Interaction of the Tetramer of E. coli KDO8P Synthase by Electrospray Ionization Mass Spectrometry

Escherichia coli 3-Deoxy-D-manno-octulosonate 8-phosphate (KDO8P) synthase catalyzes the condensation reaction between D-arabinose 5-phosphate (A5P) and phosphoenolpyruvate (PEP) to form KDO8P and inorganic phosphate (Pi). This enzyme exists as a tetramer in solution, which is important for catalysis. Two different states of the enzyme were obtained: i) PEP-bound and ii) PEP-unbound. The effect of the substrates and products on the overall structure of KDO8P synthase in both PEP-bound and unbound states was examined using electrospray ionization mass spectrometry. The analysis of our data showed that the complexes of the PEP-unbound enzyme with PEP (or Pi) favored the formation of monomers, while the complexes with A5P (or KDO8P) mainly favored dimers. The PEP-bound enzyme was found to exist in the monomer and dimer with a small amount of the tetramer, whereas the PEP-unbound form primarily exists in the monomer and dimer, and no tetramer was observed, suggesting that the bound PEP have a role in stabilization of the tetrameric structure. Taken together, the results imply that the addition of the substrates or products to the unbound enzyme may alter the subunit-subunit interactions and/or conformational change of the protein at the active site, and this study also demonstrates that the electrospray ionization mass spectrometric method may be a powerful tool in probing the subunit-subunit interactions and/or conformational change of multi-subunit protein upon binding to ligand.     

FKBP23 in ER binds to BiP specifically

FKBP23 was found in mouse endoplasmic reticulum (ER) in 1998. It consists of an N-terminal peptidyl-prolyl cis-trans isomerase (PPIase) domain and a C-terminal domain with Ca2+ binding sites. The fusion protein of mouse FKBP23 and glutathione S-transferase (GST), GST-FKBP23, and the fusion protein of BiP, a member of heat shock protein 70 (Hsp 70) in ER, and GST, GST-BiP, were subcloned in E. coli, expressed and purified. The fusion proteins were restrictively digested by Factor Xa (FaXa) to obtain the free cloned proteins FKBP23 and BiP. With the assay of adsorption of free FKBP23 or BiP with GST-BiP or GST-FKBP23 attached to the Glutathione-Sepharose 4B, the adsorbed FKBP23 or BiP could be detected by Immunoblot. It means that FKBP23 binds to BiP. Furthermore, BiP in leukocyte ER-extract can be adsorbed with GST-FKBP23 attached to the glutathione-Sepharose 4B. It shows that FKBP23 binds to natural BiP in ER, too. These experiments show that a PPIase binds to a molecular chaperone of the Hsp70 family.     

LaCl3提高菠菜光系统Ⅱ活性的作用机制

The effect of LaCl3 on the K3Fe(CN)6 (FeCy) reduction rate and the oxygen-evolving rate of PSU particles of spinach, and the spectral characterization of the D1/D2/Cytb559 of a PSII reaction center complex consisting of three polypeptides from spinach were studied. The experimental results showed that LaCl3 could significantly accelerate the transformation from light energy to electric energy, the electron transport, water photolysis and oxygen evolution of PSII of spinach, which was related to the spectral characterization of the D1/D2/Cytb559 complex.Soret band and Q band of Chl-a of UV-vis spectrum of D1/D2/Cytb559 complex were blue shifted, and the fluorescence emission peak was blue shifted in LaCl3 treated spinach compared with that in the control. The EXAFS (extended X-ray absorption fine structure spectroscopy) revealed that La^3 was coordinated with 8 nitrogen or oxygen atoms in the first coordination shell with La-N or La-O bond length of 0.254 nm, and with 6 nitrogen or oxygen atoms in the second coordination shell with La-N or La-O bond length of 0.321 nm in the D1/D2/Cytb559 complex. The CD suggested that the secondary structure of D1/D2/Cytb559 complex have been litfie affected by the treatment of LaCl3.     

ROLE OF THIOL-DISULFIDE EXCHANGE IN INSULIN BINDING TO ITS RECEPTOR

The effects of reduction by DTT, oxidation by DTNB and treatment with NEM on the thiol contents and insulin binding to its receptor in mice liver membranes were studied. Reduction with DTT leads to a parallel increase in the thiol content and the speciflc binding of insulin to the membrane. Scatchard analysis of the results shows little change in the number of binding sites but a twofold increase of the binding constant. Washing the membrane with bound insulin by a DTT containing buffer results in a more marked increase in the release of bound insulin than washing with buffer alone, suggesting that part of the insulin is bound to its receptor by covalent disulfide linkages through a thIol-disulfide exchange reaction and reduction with DTT leads to a marked increase in this "disulfide-linked" insulin. Treatment with DTNB or NEM of the DTT-reduced membrane seems to reverse the effect of DTT reduction, although the reaction of the untreated membrane with DTNB or NEM had little or no effect on the specific     

Synthesis, Structural Characterization of Ferrocenyl Iminophosphines and Amidophosphines as Well as Their Application in the Suzuki Reaction

Ferrocenyliminophosphine 1 and 1,1'-bisferrocenyliminophosphine 2 were easily prepared from the condensation of formylferrocene or 1,1'-diformylferrocene with 2-(diphenylphosphino)aniline.The following reduction of imine group by LiAlH4 led to the formation of the corresponding ferrocenyl amidophosphines 3 and 4.The new ligands 2-4 were well characterized by IR,1H NMR,31P NMR spectra,elemental analysis,and ESI-MS.The catalytic activity of all the ligands with palladium compounds in the Suzuki reaction was evaluated.Ligand 1,in combination with Pd(OAc)2,was found to be the most effective for the Suzuki reaction of aryl bromides with phenylboronic acid.Typically,the use of 0.1%(molar fraction)of Pd(OAc)2/ligand 1 in the presence of two equivalents of K2CO3 as base in toluene at 110 ℃ provided good to excellent yields of the coupled products.     

NUCLEAR PORE COMPLEX IN SPERMATOGENESIS OF BEIJING DOMESTIC DUCK——ELECTRON MICROSCOPE OBSERVATION OF FREEZE-ETCHING

The nuclear pore complex in spermatogenesis of Beijing domestic duck has been studiedby means of electron microscopic observation of freeze-etching. The structure of the poreobserved proves to be in accord with the model of the nuclear pore complex proposed respec-tively by Franke (1970) and Roberts et al. (1970). But its central granule may be present(1--3 granules) or absent. The granules are considered to be material in transit. The sizeand frequency of the pore vary with different types of reproductive cells, which is believedto be related to the cells' function. The pores concentrate on the side of nucleus near Golgizone in primary spermatocyte and near the proacrosome of spermatid, and this shows thefunctional variety of parts in the nucleus.     

Voltammetric determination of stability constants of lead complexes with diallyl disulfide,dimethyl disulfide,and diallyl sulfide

The complexation of Pb~(2+)by diallyl disulfide(DADS), dimethyl disulfide(DMDS) and diallyl sulfide(DAS)has been studied by differential pulse voltammetry. Stability constants,(log b), of the 1:1(PbL) and 1:2(PbL_2) complexes, where L = ligand, were found to be in the range of ca. 3.8–4.2 and 9.4–10.2,respectively. Complex formation is accompanied with a significant decrease in the peak current and the shift of the Pb2+/Pb half-wave potential to a higher one upon the addition of the sulfur containing ligands(L). The formation of 1:1 and 1:2 complexes, i.e., PbL~(2+)and PbL_2~(2+)was observed in the case of the three ligands. The consecutive formation constants of labile lead complexes with DADS, DMDS, and DAS were determined at 298 K by the method of De Ford and Hume. Apparently due to the large size of the lead ion,steric hindrance caused by the greater steric bulk of DADS compared to that of DMDS have little or no effects on the formation constants, so that very similar values were obtained in the case of the two ligands. Also, the possible participation of C=C double bonds in coordination with the metal center in the case of DADS appears to compensate for the steric effects caused by the larger size of this ligand. In agreement with the Jorgensen principle of symbiosis, the second formation constants were found to be approximately six orders of magnitude greater than the first ones.     

Distribution and forms of phosphorus in tidal flat sediments of the Yangtze Estuary and coast

The distribution and forms of phosphorus (P) were investigated in the tidal flat sediments of the Yangtze Estuary and coast. The total P contents in surface sediments range from 18.0 to 31.4 μmol · g-1 along the southern coast. The spatial and temporal distribution of P in tidal flats is closely related to the location and pollution resources, especially in association with the variation of hydrodynamic conditions. Significant variations in the forms of P in different sites were observed. P bonded with Ca(Ca-P) is the dominant mineral form in all surface sediments, organic P(Org-P) is lower. Most P is of unstable form, suggesting that P has larger potential activity. P accumulation is the main behavior process between water and sediment in the coastal environment of the Yangtze Estuary.     

Hydrogen Bonds in Coal -The Influence of Coal Rank and the Recognition of a New Hydrogen Bond in Coal

By means of in-situ diffuse reflectance FTIR.The IR spectra of 6 coals with different ranks were obtained from room temperature to 230℃.A new curve fitting method was used to recognize the different hydrogen bonds in the coals.and the influence of coal ranks on the distribution of hydrogen bonds(HBs) in the coals and their thermal stability were discussed.The results show that there is another new HB(around 2514cm^-1) between the-SH in mercaptans or thiophenols and the nitrogen in the pyridine-like compounds in the coals.and the evidence for that was provided.The controversial band of the HB between hydroxyl and the nitrogen of the pyridine-like compounds was determined in the range of 3028-2984cm^-1,and the result is comsistent with but more specific than that of Painter et al.It was ound that the stability of different HBs in the coals is influenced by both coal rank and temperature,For some HBs.the higher the coal rank,the higher the stability of them.Within the temperature range of our research,the stability of the HB between the hydroxyl and the π bond increases to some extent for some coals at temperatures higher than 110 or 140℃.     

HPLC-DAD data coupled with second-order calibration method applied to food analysis: Simultaneous determination of six benzoylurea insecticides in various fruit samples by selecting time region of chromatogram

This work presents a novel application of second-order calibration based on self-weighted alternating trilinear decomposition(SWATLD)algorithm for analyzing the HPLC-DAD data.The proposed method makes it possible to simultaneously determine teflubenzuron,hexaflumuron,flufenoxuron,chlorfluazuron,diflubenzuron and benzoylurea in different fruit samples,i.e.pear,apple and banana,in the selected time region of chromatogram.The concentration,elution time and spectral information of these benzoylurea insecticides are selectively extracted from complex matrices even in the presence of unknown interferences.The root-mean-square error of prediction(RMSEP)and figures of merit,including sensitivity(SEN),selectivity(SEL)and limit of detection(LOD)are employed to access the performance of the method.The LODs obtained for these insecticides are within the range 0.017–0.26 ppm in pears,0.039–0.33 ppm in apples,0.041–0.44 ppm in bananas,respectively.Such a chemometrics-based protocol holds great potential to be extended as a promising alternative for more practical applications in food safety and quality monitoring.     

Synthesis,Spectroscopic Properties,and Photodynamic Anticancer Activities of Novel Arginine-modified Silicon(Ⅳ) Phthalocyanines

We design and synthesize a series of novel silicon(IV)phthalocyanines(SiPcs,1a,2a,1b,and 2b)axially conjugated with arginine or arginine-containing oligopeptides(Arg-Arg,Cys-Arg,Cys-Arg-Arg)through ester or ether linkers to demonstrate the effects of substituents and coupling ways on the spectral behaviors and photodynamic activities.The ester-linked SiPcs(1a and 2a)show slight red-shift,higher fluorescence emission and singlet oxygen generation compared to the ether-linked analogues(1b and 2b)due to the stronger electron-withdrawing ability of the ester group,suggesting that electronic effect of the linkers plays an important role in their spectral properties.The introduction of arginine could effectively reduce the aggregation of phthalocyanine in aqueous solutions.With higher cellular uptake and plasma membrane localization ability,1b and 2b exhibit significantly higher photocytotoxicity against both HepG2 and Hela cells.Moreover,the in vivo fluorescence imaging suggests that 2b is the most specific toward H22 tumor-bearing ICR mice,and it shows efficient tumor growth inhibition with the tumor inhibition rate up to 93%.Thus,this work would provide a new reference for the development of phthalocyanine-based photosensitizers.