Radiation emission from the ＂Rhodotron-TT200＂ cavity

In this paper, the X-rays emitted from the Rhodotron-TT200 cavity have been studied in depth. We found that the Bremsstrahlung interaction is the only contribution of X-ray generation important to safety. The X-ray dose rate in the Rhodotron vault is calculated for normal conditions based on MCNP4C results. The presented calculation shows good agreement with the experimental measurements, which consequently confirms the reliability of the calculation for use in shielding design and other safety aspects.     

Rationalizing chain microstructure in the polyα-olefins synthesized by cationic AlCl3/H2O catalytic system

In this study, three middle range α-olefin monomers including 1-hexene, 1-octene, and 1-decene were oligomerized using conventional AlCl₃/H₂O catalytic system. Molecular weight and microstructure of the oligomers were analyzed by GPC and ¹HNMR, respectively. By ¹HNMR spectra, both internal (CHR=CHR′ and CHR=CR′R′′) and external (CH₂=CR′R′′) olefins containing di and tri-substituted C=C bonds were detected. After successful oligomerization, synthesized polyα-olefins underwent hydrogenation process using Pd(0)-Hal catalyst to yield synthetic oils of PHex, POct, and PDec, respectively and then completion of the hydrogenation was confirmed by ¹HNMR spectroscopy. The microstructure of the synthesized oligomers was rationalized using the ratio under the peak of CH?+?CH₂/CH₃ hydrogens (S1/S2) in ¹HNMR spectra and the degree of oligomerization obtained from M_n. According to the results, the best match between theoretical and real S1/S2 is obtained when considering double bond isomerization in the synthesized PAOs. By knowing PAO molecular weight, a relationship between monomer type and S1/S2 in the PAO homopolymers was detected. Our suggested methodology can be generalized to the unknown PAO homopolymers to unravel their monomer type by simple ¹HNMR and GPC analyses.     

Remarkable Oxygen‐Evolution Activity of a Perovskite Oxide from the Ca2−xSrxFe2O6−δ Series

Herein in we report the unprecedented catalytic activity of an iron‐based oxygen‐deficient perovskite for the oxygen‐evolution reaction (OER). The systematic trends in OER activity as a function of composition, defect‐order, and electrical conductivity have been demonstrated, leading to a methodical increase in OER catalytic activity: Ca₂Fe₂O_6?δ<CaSrFe₂O_6?δ<Sr₂Fe₂O_6?δ. Sr₂Fe₂O_6?δ also has the highest electrical conductivity and a unique type of defect‐order. In conventional experiments using glassy carbon electrode, Sr₂Fe₂O_6?δ shows better OER activity than the current state of the art catalysts, Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3?δ and RuO₂. It also offers a high intrinsic electrical conductivity, which allows it to act as a catalyst without the need for glassy carbon electrode or carbon powder. Pure disks of this material exhibit an outstanding activity for OER, without any additives or need for electrode preparation.     

Determination of BTEX in urine samples using cooling/heating-assisted headspace solid-phase microextraction

Excessive and uncontrolled exposures of the workers to benzene, toluene, ethylbenzene and xylene (BTEX) have currently raised great concerns among industrial hygienist all over the world. Therefore, the effective monitoring of such exposures is assumed to be of prime importance. A cold fiber solid-phase microextraction device based on a cooling capsule as a cooling unit and CO₂ as a coolant was applied to quantitatively analyze BTEX in aqueous samples. A gas chromatography with flame ionization detection was recruited to analyze the target analytes, which had been identified according to their retention times. Several factors such as coating temperature, extraction time and temperature, sample volume and sodium content were optimized. Two modes of extraction, i.e., headspace (HS) and headspace cold fiber (HS-CF) in SPME, were investigated and compared under optimized conditions. The results revealed that HS-CF-SPME has the most appropriate outcome for the extraction of BTEX from aqueous samples. Under the optimized conditions, the calibration curves were linear within the range of 0.2–500 ng ml^?1 and the detection limits were between 0.02 and 0.07 ng ml^?1.The intraday relative standard deviations was lower than about 10%. The method was successfully applied to the determination of BTEX in urine samples with good recovery.     

Calibration of Near-Infrared Detectors Using a Wavelength Tunable Light Source

Optical Review - This paper presents the spectral responsivity calibrations of two indium gallium arsenide (InGaAs) and one germanium based near-infrared photovoltaic detectors using a wavelength...     

Change in ~7Be half-life in host media

First-principle calculations within the density functional theory framework are used to study the probability of electron capture for the ~7Be nucleus.For this purpose,electron density at the ~7Be nucleus is computed in Al,Au,Pd,Pt,and Pb environments.Our results show that the half-life of ~7Be is changed by implanting ~7Be in host environments.Electron affinity of the media and confinement effects are responsible for the change in the half-life of ~7Be nucleus.Moreover,electric potential at the ~7Be nucleus is calculated.Results show that variations in electric potential are usually consistent with those in electron density at the ~7Be nucleus.     

Synthesis and crystal structure of manganese(III), zinc(II) and cadmium(II) complexes based on a symmetrical macroacyclic Schiff base ligand containing piperazine moiety,DNA binding studies of complexes

Transition Metal Chemistry - Three macroacyclic Schiff base complexes have been obtained by the reaction of a previously known Schiff base ligand,...     

Wipe sampling procedure coupled to LC–MS/MS analysis for the simultaneous determination of 10 cytotoxic drugs on different surfaces

A simple wipe sampling procedure was developed for the surface contamination determination of ten cytotoxic drugs: cytarabine, gemcitabine, methotrexate, etoposide phosphate, cyclophosphamide, ifosfamide, irinotecan, doxorubicin, epirubicin and vincristine. Wiping was performed using Whatman filter paper on different surfaces such as stainless steel, polypropylene, polystyrol, glass, latex gloves, computer mouse and coated paperboard. Wiping and desorption procedures were investigated: The same solution containing 20% acetonitrile and 0.1% formic acid in water gave the best results. After ultrasonic desorption and then centrifugation, samples were analysed by a validated liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS) in selected reaction monitoring mode. The whole analytical strategy from wipe sampling to LC–MS/MS analysis was evaluated to determine quantitative performance. The lowest limit of quantification of 10 ng per wiping sample (i.e. 0.1 ng cm⁻²) was determined for the ten investigated cytotoxic drugs. Relative standard deviation for intermediate precision was always inferior to 20%. As recovery was dependent on the tested surface for each drug, a correction factor was determined and applied for real samples. The method was then successfully applied at the cytotoxic production unit of the Geneva University Hospitals pharmacy.