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Abstract  

A TiO2/monazite photocatalyst was prepared by embedding TiO2 nanoparticles into a monazite substrate surface. TiCl4 hydrolysis/citric acid chelating procedure under acidic conditions were used to synthesize the nanophase TiO2 particles. The anatase TiO2/monazite photocatalyst surface area, morphology, crystalline and elemental concentrations were characterized using Brunauer-Emmett-Teller (BET) method, scanning electron microscopy (SEM), X-ray diffraction (XRD), and inductively coupled plasma-atomic emission spectrometry (ICP-AES). Monazite contains a large amount of Ce-, La-, Nd- and Th-PO4 compounds; it has been known as a natural mineral material with minor radioactivity. TiO2-CeO2 composite is a kind of radiation sensitive photocatalyst in which the radiations of thorium nuclides give energy to trigger TiO2 and cerium ions which play an energy absorber with charge separator. The result showed that methylene blue and phenol were spontaneously photocatalytic decomposed by TiO2/monazite composite even in a dark environment. A synergistic effect was also examined with applied exterior UV or 60Co irradiation. A hybrid mechanism is proposed; according by the radioluminescence (RL) from excited Ce ion by γ-radiation soliciting CeO2/TiO2 heterojunction (HJ). This seems to be a possible mechanism to explain this self-activated photo-catalytic behavior.

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Abstract  

We report on the design, construction, and testing of a gamma-ray imaging system with spectroscopic capabilities. The imaging system consists of an orthogonal strip detector made from either HgI2 or CdZnTe crystals. The detectors utilize an 8×8 orthogonal strip configuration with 64 effective pixels. Both HgI2 or CdZnTe detectors are 1 cm2 devices with a strip pitch of approximately 1.2 mm (producing pixels of 1.2 mm × 1.2 mm). The readout electronics consist of parallel channels of preamplifier, shaping amplifier, discriminators, and peak sensing ADC. The preamplifiers are configured in hybrid technology, and the rest of the electronics are implemented in NIM and CAMAC with control via a Power Macintosh computer. The software used to readout the instrument is capable of performing intensity measurements as well as spectroscopy on all 64 pixels of the device. We report on the performance of the system imaging gamma-rays in the 20–500 keV energy range and using a pin-hole collimator to form the image.

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Abstract  

The radionuclide iron-55 (T 1/2 = 2.73 a) decays by electron capture and consists of small percentage of weak gamma rays. 55Fe can be employed for industrial, medical and agriculture applications. First, calculation of the excitation functions of iron-55 via the 55Mn(p,n)55Fe, 55Mn(d,2n)55Fe and 54Fe(α,n2p)55Fe reactions were performed and investigated by ALICE/ASH (hybrid model) and EMPIRE (3.1 Rivoli) codes. Then the required thickness of the target was calculated by the SRIM code; moreover, the theoretical physical yields of 55Fe production reactions were obtained. Consequently, the best reaction, 55Mn(p,n)55Fe, was suggested to take full benefit of the excitation function and to avoid formation of radioactive and non-radioactive impurities as far as possible. Furthermore, the optimum energy range were predicted to be 2–18 MeV and the theoretical physical yield were obtained to be 0.35 MBq/μA h. Lastly, manganese dioxide (MnO2) powder was used to prepare the thick layer; it was deposited on an elliptical copper substrate by means of sedimentation method. Target was irradiated at 20 μA current and 18 MeV proton beam. The radioactivity of 55Fe was determined via X-ray detector.

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Abstract

The mechanism of adsorption and desorption of ethyl cellulose (EC) on and from silver powder was studied. After analysis with DSC, XPS and dynamic FT-IR, which could be heated by a program-controlled heater, applied to observe the states of pure EC and of EC adsorbed on silver powder, and also the thermal decomposition of EC from silver powder, the chemisorption bonding bridge between the oxygen atoms of EC and the silver atoms investigated. The differences in thermal decomposition between pure EC and EC adsorbed in silver powder were also studied. It was concluded that the chemisorption bonding between the oxygen atoms of EC and the silver atoms mainly involved the lone-pair electrons of the oxygen atoms on the EC chain and the outer empty 5 sp3 hybrid orbital of the silver. Because of the formation of this bridge, the bonds between neighboring carbon and oxygen atoms are weakened. As a result of this effect, the C-O bonds in the EC chain are broken more easily than the C-H bonds, which leads to the observation of -C-H- fragments in the upper space when EC adsorbed on silver is heated. When the same experiments were carried out on pure EC, almost all kinds of broken fragments of the EC molecule, including -C-H-, -C=O- and -C-O- appeared simultaneously.

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Abstract  

61Cu is positron emitter and can be used as the PET and molecular imaging. In this study cyclotron production of 61Cu via 61Ni(p,n)61Cu, natNi(p,x)61Cu, natNi(d,x)61Cu, natNi(α,x)61Cu, natZn(p,x)61Cu and 59Co(α,2n)61Cu reactions was investigated. The ALICE/ASH (hybrid and GDH models) and TALYS-1.2 codes were used to calculate excitation functions for proton, alpha and deuteron induced on natNi, proton on 61Ni and natZn and also alpha-particle on 59Co targets that lead to the production of 61Cu radioisotopes using intermediate energy accelerators. In addition, we compared the data obtained from in this study with the reported measurement by experimental data. Moreover, optimal thickness of the targets and physical yield were obtained by stopping and range of ions in matter code for each reaction. Eventually 61Ni(p,n)61Cu and 59Co(α,2n)61Cu reaction to produce 61Cu in no-carrier added state with high production yield was suggested. Finally the natNi(p,x)61Cu reaction was employed to test the target preparation using electroplating technique.

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To simulate front displacement through porous media (TLC plates) the effect of the axisymmetric alternating electric fields on liquids confined in capillary tubes was studied. This electric field causes liquid displacement through capillary tubes with great velocity, the main action being on the liquid column meniscus. Capillary tubes were used to enable understanding of the flow phenomena which occur in porous media. It was observed that the displacement velocity of the liquids confined in capillary tubes depended on the magnitude of the alternating electric field, the electric properties (conductivity, permittivity) of the liquids, the frequency of the current, and the tube material.In normal TLC practice, migration of the mobile phase through the layer is controlled by capillary forces. The velocity and migration distance of the mobile-phase front in prous media can be increased by application of an external electric field, an effect called by us ‘dielectroosmotic flow’ (DEOF), because of its similarity with electrokinetic phenomena. DEOF is observed on different TLC plates and paper strips developed with non-polar and polar solvents. As a result the separation of some compounds was improved. This method is a hybrid of electric forced flow and classical TLC; we have named it ‘planar dielectrochromatography’ (PDEC).A horizontal chromatographic chamber has been constructed and has been used to investigate the principles of planar dielectrochromatography, specifically the increase in front velocity and the dielectrophoretic force generated at granule level on different ready-to-use plates.

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Abstract  

Bentonite has been studied extensively because of its strong sorption and complexation ability. Herein, GMZ bentonite from Gaomiaozi county (Inner Mongolia, China) was investigated as the candidate of backfill material for the removal of Th(IV) ions from aqueous solutions. The results indicate that the sorption of Th(IV) is strongly dependent on pH and ionic strength at pH < 5, and independent of ionic strength at pH > 5. Outer-sphere surface complexation or ion-exchange are the main mechanism of Th(IV) sorption on GMZ bentonite at low pH values, whereas the sorption of Th(IV) at pH > 5 is mainly dominated by inner-sphere surface complexation or surface precipitation. Soil fulvic acid (FA) and humic acid (HA) have a positive influence on the sorption of Th(IV) on bentonite at pH < 5. The different addition sequences of HA and Th(IV) to GMZ bentonite suspensions have no obvious effect on Th(IV) sorption to HA-bentonite hybrids. The high sorption capacity of Th(IV) on GMZ bentonite suggests that the GMZ bentonite can remove Th(IV) ions from large volumes of aqueous solutions in real work.

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Acta Chromatographica
Authors: Xi Bao, Bingge Huang, Yiting Mao, Zhiguang Zhang, Yunfang Zhou, Congcong Wen, and Quan Zhou

Byakangelicol is one of coumarins from Baizhi and has been shown to inhibit the release of PGE2 from human lung epithelial A549 cells in a dose-dependent manner. A sensitive ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) method was developed and full validated for the quantification of byakangelicol in rat plasma. The pharmacokinetics of byakangelicol after both intravenous (5 mg/kg) and oral (15 mg/kg) administrations were studied. Chromatographic separation was performed on an ultra-performance liquid chromatography ethylene bridged hybrid (UPLC BEH) C18 column with acetonitrile and 0.1% formic acid as the mobile phase at a flow rate of 0.4 mL/min; fargesin was used as the internal standard (IS). The following quantitative analysis of byakangelicol was utilized in the multiple reaction monitoring mode. The samples were extracted from rat plasma via protein precipitation using acetonitrile. In the concentration range of 1–2000 ng/mL, the method correlated linearity (r > 0.995) with a lower limit of quantitation (LLOQ) of 1 ng/mL. Intra-day precision was less than 11%, and inter-day precision was less than 12%. The accuracy was between 92.0% and 108.7%, the recovery was better than 89.6%, and the matrix effect was between 85.9% and 98.6%. The method was successfully applied to a pharmacokinetic study of byakangelicol after intravenous and oral administration, and the absolute bioavailability was 3.6%.

Open access
Acta Chromatographica
Authors: Qinghua Weng, Lianguo Chen, Luxin Ye, Xiaojie Lu, Zheng Yu, Congcong Wen, Yichuan Chen, and Gang Huang

The aim of this study was to establish a rapid, sensitive, and selective ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) method to quantify the concentrations of licochalcone A and applicate the technique to its pharmacokinetic study. Analytes were separated on an UPLC ethylene bridged hybrid (BEH) C18 column (2.1 mm × 50 mm, 1.7 μm). The mobile phase was consisted of acetontrile and 0.1% formic acid with a flow rate of 0.4 mL/min in a gradient elution mode. Multiple-reaction monitoring (MRM) was carried out in a negative mode for licochalcone A (m/z 337.2 → 119.7) and the internal standard (IS) (m/z 609.0 → 300.9). The linearity of licochalcone A was great from 0.53 to 530 ng/mL. The lower limit of quantification and the lower limit of detection were 0.53 ng/mL and 0.26 ng/mL, respectively. The intra-day precision was less than 14%, and the inter-day precision was no more than 11%. The accuracy was from 91.5% to 113.9%, the recovery was over 90.5%, and the matrix effect was between 84.5% and 89.7%. The results of stability were in an acceptable range. The bioavailability was only 3.3%, exhibiting poor absorption. The developed method was successfully applicable for determining the concentrations of licochalcone A and its pharmacokinetic study.

Open access

Hair is a stable specimen and has a longer detection window (from weeks to months) than blood and urine. Through the analysis of hair, the long-term information of the drug use of the identified person could be explored. Our work is to establish an ultra-performance liquid chromatography–tandem mass spectroscopy (UPLC–MS/MS) method for simultaneous determination of methamphetamine, amphetamine, morphine, monoacetylmorphine, ketamine, norketamine, 3,4-methylenedioxymethamphetamine (MDMA), and 3,4-methylenedioxyamphetamine (MDA) in hair. Methoxyphenamine was used as an internal standard. The chromatographic separation was performed on a UPLC ethylene bridged hybrid (BEH) C18 (2.1 mm × 50 mm, 1.7 μm) column using a mobile phase of acetonitrile–water with 10 mmol/L ammonium acetate solution which containing 0.05% ammonium hydroxide. The multiple reaction monitoring in positive electrospray ionization was used for quantitative determination. The intra-day and inter-day precisions (relative standard deviation [RSD]) were below 15%. The accuracy ranged between 85.5% and 110.4%, the average recovery rate was above 72.9%, and the matrix effect ranged between 92.7% and 109.2%. Standard curves were in the range of 0.05–5.0 ng/mg, and the correlation coefficients were greater than 0.995. The established UPLC–MS/MS method was applied to analyze the hair samples successfully.

Open access