Experimental proof of thiophene hydrodesulfurization reaction steps by isotope (14C) labeled thiophene

Hydrodesulfurization of thiophene has been studied over alumina supported sulfided molybdena, nickel-promoted molybdena and over nickel (Mo, NiMo and Ni) catalysts. The experiments were carried out with a mixture of thiophene, labeled with radioactive carbon (thiophene-[G-]-14C) and of non-radioactive tetrahydrothiophene (1:1 mol ratio) in a micro catalytic system. It was established, that the main products were tetrahydrothiophene-14C, 1-butene-14C, 2-butene-14C, butane-14C. Tetrahydrothiophene-14C was a major intermediate in the conversion of thiophene—14C in the experimental condition applied. The amounts of converted tetrahydrothiophene on the catalysts were substantially higher than those of thiophene under the same conditions. Hydrothiophene and dihydrothiophene—14C were intermediate products in the hydrodesulfurization of thiophene and tetrahydrothiophene. The hydrodesulphurization of tetrahydrothiophene was paired with dehydrogenation, producing small amounts of thiophene. The experimental results have been considered in the discussion of the mechanism of thiophene and tetrahydrothiophene desulfurization reaction pathway.

14C Research at the Laboratory for the Analysis of Radiocarbon with AMS (LARA), University of Bern

The Laboratory for the Analysis of Radiocarbon with AMS (LARA) at the University of Bern measures the radioactive carbon isotope 14C with accelerator mass spectrometry (AMS) in different applications. Besides radiocarbon dating of environmental and archaeological samples, the LARA focuses on source apportionment of air-borne particulate matter (i.e. aerosols) as well as greenhouse gases such as carbon dioxide and methane. This approach allows the identification and quantification of fossil carbon emissions in these air components, which is relevant for measures of air-quality improvement. The LARA furthermore develops instrumental setups for and at the AMS in order to analyze 14C samples in μg-amounts with low contamination and high throughput, preferably using online-hyphenated systems.

Two Types of Iron Smelting Furnaces in Ancient Mongolia

We excavated the Iron smelting furnaces, belonging to the Xiongnu Age (209BCE-155CE), in Mongolia. These furnaces can be divided into three types by structures. By the stratigraphic research and the radioactive carbon dating of charcoal, the transition from Type 3 to Type1 occurred from late BC1c. to around the beginning of AD1c.

Pole models of decay of natural radioactive carbon as dose-forming nuclide

The article presents the pole model of radiocarbon decay process. When using this model it is assumed that there is a pair bond in the form of an individual pole axis between proton and electron. This bond can change the tilt angle relative to the generalized axis, with increasing energy. Increase of the tilt angle of the pole axis is accompanied by increase of its energy, this process is interrelated with energy state of the paired electron. With increasing energy of the paired bond the energy of the electron decreases and it occupies the energy level located closer to the nucleus. At critical increase of energy of the pole axis it will deflect to the maximum angle, the electron takes the position located in the maximum proximity to the nucleus, which leads to the connection with the paired proton and formation of the neutron. The analysis of the decay process illustration is carried out. This article describes the β-decay process using pole models.

Micro alloying of SiC by radioisotope

The endotaxia is the process of growth of one crystal structure inside the volume of another. In this case we are talking about the formation of the Silicon Carbide film in the Silicon substrate. The Silicon substrate is placed in the gas chamber. The sample is exposed to the stream of methane gas CH4 at temperature of 1360 - 1380 ◦C and at normal pressure. Moreover, gas contains both the stable Carbon isotope C12 and the radioactive Carbon isotope C14, and hydrogen H2 in the gas acts as a carrier of Carbon.