带喷头混合型毛细管色谱柱的制备及其在蛋白质组分离分析中的应用

本研究制备了一种应用于液-质联用（LC-MS）系统中的带喷头混合型毛细管色谱柱．用标准蛋白和酵母蛋白胰蛋白酶酶切溶液考察了其在LC—MS中的离子化效率、毛细管色谱柱分离性能和寿命,并与直接填充型毛细管色谱柱的色谱性能进行比较,未见显著性差异．将制备的带喷头混合型毛细管色谱柱应用于鼠肝蛋白组的分析,在假阳性率为1％的条件下鉴定到1262个肽段,归属于513个蛋白簇．通过对鉴定蛋白质理化性能的统计分析,其等电点和分子量分布高于一般两维凝胶电泳的范围．实验结果还表明该混合型毛细管色谱柱在肽段的理化性能上没有偏性,可以广泛应用于蛋白质组学的研究中．     

Application of a new standardization method in activation analysis with registration of soft gamma radiation

An application of a new standardization method for rapid activation mass analysis with registration of the strongly absorbed low-energy gamma radiation is described. This method makes it possible to avoid the use of the time-consuming and laborious method of Internal Standard.     

Extraction of biosilica from date palm biomass ash and its application in photocatalysis

There is an emerging trend in the valorization of biomass waste for the development of value-added products. Date palm biomass is an extensively available bioresource in Saudi Arabia. In date palm farms, the biomass residues are usually burnt, and a lot of ash is generated. Biomass ash is rich in silica, which is a valuable material used in a wide range of applications. This study explores the extraction of pure silica nanoparticles from date palm biomass ash (DPBA) and its application in photocatalysis. A chemical sol–gel method or thermal combustion method was employed for the extraction of silica. The extracted silica nanoparticles were characterized by EDX, FT-IR, XRD, SEM, BET, and TGA. FT-IR spectra of extracted biosilica samples displayed only the characteristic peaks corresponding to the silica functional groups. The chemically synthesized biosilica sample exhibited higher purity (98 %) and higher surface area (376 m²/g) compared to the thermally prepared biosilica samples. The SEM analysis revealed the presence of spherical-shaped silica particles of an average diameter of 93 nm in chemically extracted biosilica and 208 nm in thermally extracted biosilica. The newly extracted biosilica samples were tested for the photodegradation of the bromophenol blue dye in water. The dye degradation efficiency of chemically prepared biosilica sample was 82 % and that of thermally prepared biosilica sample was 74 %. The relatively higher degradation efficiency of BS-chemical could be due to its higher surface area and smaller particle size, and also due to the presence of lots of surface defects in this fully amorphous biosilica.     

A new method to determine pore size and its volume distribution of porous solids having known atomistic configuration

A simple method, based on Monte Carlo integration, is presented to derive pore size and its volume distribution for porous solids having known configuration of solid atoms. Because pores do not have any particular shape, it is important that we define the pore size in an unambiguous manner and the volume associated with each pore size. The void volume that we adopt is the one that is accessible to the center of mass of the probe particle. We test this new method with porous solids having well defined pores such as graphitic slit pores and carbon nanotubes, and then apply it to obtain the pore volume distribution of complex solids such as disordered solids, rectangular pores, defected graphitic pores, metal organic framework and zeolite.     

填充吸附剂微萃取技术及其在微小体积样品萃取应用中的研究进展

微萃取技术是分析化学领域发展迅速,且已经得到广泛应用的样品前处理技术.填充吸附剂微萃取(MEPS)是一种微量固相萃取技术,使用微量的吸附剂填充于微量注射器,通过反复抽推方式使样品多次流经吸附剂以完成样品吸附萃取过程,萃取后的样品可直接用于色谱分析.典型的MEPS萃取设备包括MEPS注射器和MEPS吸附床(BIN).ME...     

Synthesis of a molecularly imprinted polymer and its application for microextraction by packed sorbent for the determination of fluoroquinolone related compounds in water

Molecularly imprinted polymer (MIP) has been synthesized by precipitation polymerization using ciprofloxacin (CIP) as template for the analysis of fluoroquinolone antibiotics (FQs). This MIP material was packed as sorbent in a device for microextraction by packed sorbent (MEPS) combined with liquid chromatography–tandem mass spectrometry (LC–MS/MS) for the analysis of selected FQs drugs including CIP, norfloxacin (NOR) and ofloxacin (OFLO) in municipal wastewater samples. In comparison to the new MIP-MEPS procedure, the target compounds were also determined by solid-phase extraction (MISPE) using the new molecular imprinted polymer material to validate the new MIP-MEPS method. The ability of the MIP for molecular recognition of CIP, NOR and OFLO was proved in presence of structurally different environmental relevant substances such as quinolones (Qs), flumequine (FLU), di(methyl)phthalate (DMP), technical 4-nonylphenol (NP), caffeine, Galaxolide^®, Tonalid^®, di(butyl)phthalate (DBP), Triclosan, bisphenol-A (BPA), carbamazepine, di(ethylhexyl)phthalate (DEHP), estradiol and octocrylene. The analysis of wastewater samples revealed the high selectivity of the synthesized polymer which was able to recognize and retain the target analytes by both extraction methods, the offline SPE with MIP material and the semi-automated MEPS packed with MIP material.     

Evaluation of gamma radiation for degradation of a polychlorinated biphenyl in solution and on activated carbon

A polychlorinated biphenyl isomer was irradiated in aqueous solution and in deoxygenated alkaline 2-propanol /0.3M KOH/. Recovery of original PCB was diminished in aqueous solution but no degradation products were seen. Degradation in alkaline 2-propanol was readily achieved by a chain reaction. Polychlorinated biphenyl adsorbed on activated carbon was also irradiated, but no degradation was evident.     

Synthesis of pectin-N,N-dimethyl acrylamide hydrogel by gamma radiation and application in drug delivery (in vitro)

The objective of the work is to synthesize pectin-N, N-Dimethylacrylamide (DMAA) hydrogel by gamma radiation without using any initiators and cross-linking agents. Effect of radiation doses on gel fraction and equilibrium swelling as a function of pH were studied, and 5 kGy radiation dose was found to be the optimum dose for hydrogel synthesis. The grafting /crosslinking was investigated by Fourier transform infrared spectroscopy. Thermal properties and surface morphology were studied by differential scanning calorimetry and scanning electron microscopy. To study the drug release kinetics, 5-fluorouracil was loaded into the hydrogel and in vitro release was carried out in simulated gastric and intestinal fluid. The release profile of drug showed that more than 90% of the loaded drugs were released after 4 hours at both gastric fluid and intestinal fluid pH. Drug release data was fitted into zero order, Higuchi and Korsmeyer-Peppas kinetic models. Higuchi model was found to be the best fitted and release exponent ‘n’ value of Korsmeyer-Peppas model indicated the non-Fickian transport.     

Ammonia absorption into water in a packed tower I: Characterization of packing and liquid distribution

Pressure loss, holdup and liquid distribution were measured for a standard 10 mm glass Raschig ring packing. The first two characteristics showed gener However, the actual holdup values and the loading and flooding zones were significantly lower than those expected for nominally similar packing. These of packing which caused variations in mass transfer coefficients due to the existence of different dry or inactive areas in nominally similar packings.The flow distribution was shown to be statistical in nature in agreement with the rivulet flow model. At the top of the packing, the radial distributio of 12 – 15 column diameters, the liquid flow distribution became constant and was predominantly at the wall. The main flow in the bulk of the packing distribution. Any increase in liquid flow was carried in existing rivulets since the number density increased very slightly with increasing liquid flow     

新型平板碳电极的研制与应用

研制了一种新型平板碳电极,用K3Fe(CN)6对电极的性能进行了简单的研究。将该电极用于神经递质多巴胺(DA)的测定,发现在pH 7.0的磷酸盐缓冲介质(PBS)中,多巴胺在该电极上产生一灵敏的氧化峰,峰电流与DA浓度在6.0×10-8~1.0×10-3mol/L范围内呈良好的线性关系,检出限(3σ)为2.0×10-8mol/L。方法可用于人工合成样品的分析。     

A new technique for the early detection of stiffness in coupled differential equations and application to standard Runge-Kutta algorithms

Higher-order Runge-Kutta (RK) algorithms employing local truncation error (LTE) estimates have had very limited success in solving stiff differential equations. These LTEs do not recognize stiffness until the region of instability has been crossed after which no correction is possible. A new technique has been designed, using the local stiffness function (LSF), which can detect stiffness very early before instability occurs. The LSF is a normalized dimensionless ratio which is essentially based on the product of the step size and the geometric mean of all the slopes. It is exceedingly sensitive to the onset of stiffness. Together, the LSF and the LTE form a complementary pair which can cooperate to help solve some mildly stiff equations which were previously intractable to RK algorithms alone. Examples are given of implementation and LSF performance. Received: 18 September 1997 / Accepted: 13 February 1998 / Published online: 17 June 1998     

A new method to determine the distance of electron tunneling transfer and its application to recombination of paramagnetic radiation deffects in CaO

A new method to determine the distance of electron tunneling transfer between paramagnetic reagents based on simultaneous analysis of both kinetic and ESR data is suggested. This method has been used to estimate the tunneling distance and the parameters characterizing the rate of tunneling for finely dispersed CaO.

---

, - . CaO , .

     

Liquid-phase polymerization of fluorine-containing esters of acrylic and methacrylic acid in a gamma radiation field

Basic kinetic characteristics of the process of radiation liquid-phase polymerization of fluorine-containing methacrylates and their hydrocarbon analogs have been compiled. The kinetics of the polymerization of fluorine-containing methacrylates is described well by a kinetic mechanism with quadratic termination of growing macromolecules and clearly expressed gel effect. The insertion of perfluorinated substituents into the methacrylate molecule evidently leads to a decrease of the rate constant of termination of the polymer chains. The kinetics of the polymerization of fluorine-containing acrylates, like their hydrocarbon analogs, differ significantly from the polymerization of maethacrylates by the absence of a quasisteady-state regime — the rate increases sharply from the very beginning of the process because of the diffusion character of termination.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1330–1334, June, 1991.     

Synthesis of a new enantiopure chiral aza crown ether and its application in enantiomeric separation

A new enantiopure chiral aza crown ether (S,S)‐1,7‐bis(4‐phenyl‐5‐hydroxy‐2‐oxo‐3‐ zapentyl)‐1,7‐diaza‐12‐crown‐4 ligand (1) has been synthesized and used as a chiral selector in the enantiomeric separation of D/L‐carnitine by capillary electrophoresis.     

Preparation of a new core-shell Ag@SiO2 nanocomposite and its application for fluorescence enhancement

Ag@SiO₂ nanoparticles with different shell thicknesses were synthesized via modified Stöber method. Rhodamine B isothiocyanate was covalently bound onto the surface of Ag@SiO₂ nanoparticles to form fluorescent core-shell Ag@SiO₂ nanocomposites. Effects of shell thickness on the fluorescence enhancement were examined using the corresponding nanobubbles prepared by cyanide etching as a control. The result showed that the fluorescence enhanced as the shell thickness increased till the distance between fluorophore and metal core reached about 75 nm with the optimal enhancement factor of ∼5-folds. Further increasing of fluorophore-metal distance caused a decrease in the enhancement factor.