排序方式: 共有119条查询结果,搜索用时 713 毫秒
101.
Agha Beygli Ramtin Mohaghegh Neda Rahimi Esmaeil 《Research on Chemical Intermediates》2019,45(4):2255-2268
Research on Chemical Intermediates - Hydroxyapatite (Hap) modified graphitic carbon nitride (g-C3N4) powders (Hap/g-C3N4) were prepared and characterized. The sorption activities of g-C3N4 and... 相似文献
102.
Habib Bagheri Faezeh Khalilian Mehrnoush Naderi Esmaeil Babanezhad 《Journal of separation science》2010,33(8):1132-1138
A micro‐SPE technique was developed by fabricating a rather small package including a polypropylene membrane shield containing the appropriate sorbent. The package was used for the extraction of some triazine herbicides from aqueous samples. Solvent desorption was subsequently performed in a microvial and an aliquot of extractant was injected into GC‐MS. Various sorbents including aniline‐ortho‐phenylene diamine copolymer, newly synthesized, polypyrrole, multiwall carbon nanotube, C18 and charcoal were examined as extracting media. Among them, conductive polymers exhibited better performance. Influential parameters including extraction and desorption time, desorption solvent and the ionic strength were optimized. The developed method proved to be rather convenient and offers sufficient sensitivity and good reproducibility. The detection limits of the method under optimized conditions were in the range of 0.01–0.04 ng/mL. The RSDs at a concentration level of 0.1 ng/mL were obtained between 4.5 and 9.3% (n=5). The calibration curves of analytes showed linearity in the range of 0.05–10 ng/mL. The developed method was successfully applied to the extraction of selected triazines from real water samples. The whole procedure showed to be conveniently applicable and quite easy to manipulate. 相似文献
103.
An one-dimensional fluid model is used to study the physico-chemical properties of a 90%Ar–10%Cl2 plasma produced in dielectric barrier discharges under different driving voltages. The spatio-temporal characteristics of the discharge are obtained by applying a sinusoidal voltage with different amplitudes and frequencies from 350 to 1200 V and 10 to 19 kHz, respectively. As the voltage amplitude increases the plasma electronegativity and plasma radiations are increased and their radiations move toward the cathode vicinity. With decreasing frequency, the plasma radiations move toward the anode vicinity and the plasma electronegativity and its radiations are enhanced. At low voltage amplitudes, plasma most radiates VUV photons while UV radiations take place at higher voltage amplitudes. 相似文献
104.
Mohammad Esmaeil Shahaboddin Khosro Khajeh Abolfazl Golestani 《Applied biochemistry and biotechnology》2018,186(2):358-370
Removal of chondroitin sulfate glycosaminoglycan (GAG) chains with chondroitinase ABC I (chABC I) in CNS injury models promotes both saxon regeneration and plasticity. It has been suggested that direct interaction between an aromatic pair appears to contribute about ??1.3 kcal/mol to the stability of a folded protein, so introducing an aromatic pair by point mutation might increase the enzyme activity and thermal stability as in the case of mesophilic xylanase, although using this approach destabilized T4 lysozyme. In this study, we used site-directed mutagenesis to investigate the effect of new aromatic pairs on activity and stability of chABC I. We replaced Ile295, Ser581, and Gly730 adjacent to pre-existing aromatic residues with Tyr to obtain new aromatic pairs, i.e., Tyr295/His372, Tyr576/Tyr581, and Tyr623/Tyr730. Results showed that Km values of S581Y and G730Y variants decreased relative to wild-type enzyme while their catalytic efficiency (kcat/Km) increased but I295Y variant was inactive. Also, long-term and thermal stability of the active mutants was decreased. Fluorescence and circular dichroism studies showed that these mutations resulted in a more flexible enzyme structures: a finding which was confirmed by thermal and limited proteolytic studies. In conclusion, the activity of chABC I can be improved by introducing appropriate aromatic pairs at the enzyme surface. This approach did not provide any promising results regarding the enzyme stability. 相似文献
105.
Reza Gharraei Esmaeil Esmaeilzadeh Mohammad Reza Heirani Nobari 《Theoretical and Computational Fluid Dynamics》2014,28(1):89-106
Electrohydrodynamic conduction pumping of dielectric liquid films using flush-mounted electrodes is investigated numerically. Two major factors consisting of the ion mobility difference and electrodes’ configuration can affect the conduction pumps. The relative importance of these factors on the hydrodynamic behavior has been studied at different configurations of flush-mounted electrodes for conduction pumping of various dielectric liquids with different electrical properties. Furthermore, the effect of heterocharge layer structure on the hydrodynamic behavior of conduction pump has been studied. The electrical behavior and flow patterns of dielectric liquids with real measured mobilities are compared with the experimental results, and new features of conduction pumping are found. The numerical results indicate that in the various operating conditions, the flow direction is dictated by the dominant factor. 相似文献
106.
Mehdi Adib Mohammad Hosein Sayahi Behrooz Behnam Esmaeil Sheibani 《Monatshefte für Chemie / Chemical Monthly》2006,137(2):191-196
Summary. The reactive 1:1 intermediate produced in the reaction between isocyanides and dialkyl acetylenedicarboxylates was trapped
by hydantoins to yield highly functionalized stable ketenimines in fairly good yields. 相似文献
107.
Zahra Nazemi Esmaeil Shams Mohamad Kazem Amini 《Journal of Solid State Electrochemistry》2016,20(2):429-438
In this study, a new procedure for the fabrication of biosensors was developed. The method is based on the covalent attachment of nitrophenyl groups to the electrode surface via diazonium salt reaction followed by their conversion to amine moieties through electrochemical reduction and electrostatic layer-by-layer (LbL) assembly technique. In this procedure, highly stable iron oxide (Fe3O4) nanoparticles (IONPs), chitosan (CHIt), GOx, and Nile blue (NB) were assembled on the surface of aminophenyl modified glassy carbon electrode (AP/GCE) by LbL assembly technique. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to characterize the interfaces. The surface coverage of the active GOx and Michaelis–Menten constant (K M) of the immobilized GOx were Γ?=?3.38?×?10?11 mol cm?2 and 2.54 mM, respectively. The developed biosensor displayed a well-defined amperometric response for glucose determination with high sensitivity (8.07 μA mM?1) and low limit of detection (LOD) of 19.0 μM. The proposed approach allows simple biointerface regeneration by increasing pH which causes disruption of the ionic interactions and release of the electrostatic attached layers. The biosensor can then be reconstructed again using fresh enzyme. Simple preparation, good chemical and mechanical stabilities, and easy surface renewal are remarkable advantages of the proposed biosensor fabrication procedure. 相似文献
108.
Mehdi Shafiee Ardestani Ali Jabbari Arabzadeh Zahra Heidari Amirreza Hosseinzadeh Hamidreza Ebrahimi Elham Hashemi Mona Mosayebnia Mohammad Shafiee-Alavidjeh Abbas Alavi Mohammad Hossein Babaei Arman Rahmim Seyed Esmaeil Sadat Ebrahimi Massoud Amanlou 《Journal of Radioanalytical and Nuclear Chemistry》2010,283(2):447-455
DTPA is a very strong metal chelator widely utilized in radiopharmaceutical chemistry for conjugation of chemicals which do not have enough potency for direct metalo-labeling and also to manage toxic radioactive materials such as plutonium, americium, and curium. It is difficult to conjugate DTPA to an amine group in a singular direction and such reactions usually also coincidently produce a mixture of DTPA-bis-amides and DTPA-mono-amide resulting in considerable insufficiencies/difficulties in synthesis and especially yield/separation procedures. In this paper, novel methods for the exclusive synthesis of DTPA-mono-amide have been established which extensively reduce the difficulties otherwise encountered and increase the reaction’s yield considering the green chemistry approaches. This is expected to be of interest to radiopharmaceutical researchers interested in the DTPA (Radio)-metallic-conjugate. Overall, this paper provides a framework to achieve a higher degree of propriety from DTPA as a chelator to conjugate to the chemical compounds. 相似文献
109.
Iraj Mohammadpoor-Baltork Mohammad mehdi Khodaei Abdol R. Hajipour Esmaeil Aslani 《Monatshefte für Chemie / Chemical Monthly》2003,134(4):539-543
Summary. An efficient and environmentally benign method for the conversion of oximes, semicarbazones, phenylhydrazones, and azines
to their corresponding carbonyl compounds using KMnO4/montmorillonite K-10 as a commercially available, non-toxic, stable, and inexpensive reagent is reported.
Corresponding author. E-mail: Imbaltork@sci.ui.ac.ir
Received August 23, 2002; accepted March 23, 2002 相似文献
110.
A novel, sensitive and selective adsorptive stripping procedure for simultaneous determination of copper, bismuth and lead is presented. The method is based on the adsorptive accumulation of thymolphthalexone (TPN) complexes of these elements onto a hanging mercury drop electrode, followed by reduction of adsorbed species by voltammetric scan using differential pulse modulation. The influences of control variables on the sensitivity of the proposed method for the simultaneous determination of copper, lead and bismuth were studied using the Derringer desirability function. The optimum analytical conditions were found to be TPN concentration of 4.0 microM, pH of 9.0, and accumulation potential at -800 mV vs. Ag/AgCl with an accumulation time of 80 s. The peak currents are proportional to the concentration of copper, bismuth and lead over the 0.4-300, 1-200 and 1-100 ng mL(-1) ranges with detection limits of 0.4, 0.8 and 0.7 ng mL(-1), respectively. The procedure was applied to the simultaneous determination of copper, bismuth and lead in the tap water and some synthetic samples with satisfactory results. 相似文献