排序方式: 共有24条查询结果,搜索用时 15 毫秒
21.
Guogang Jia M. Belli U. Sansone S. Rosamilia S. Gaudino 《Journal of Radioanalytical and Nuclear Chemistry》2004,260(3):481-494
The smear samples of the penetrator were analyzed for the determination of the uranium composition. The obtained relative
composition (m/m) of uranium isotopes in all the smear samples is in the range of 99.76-99.78% for 238U, 0.000659-0.000696% for 234U, 0.213-0.234% for 235U, and 0.00274-0.00328% for 236U, showing characteristics of depleted uranium (DU). The uranium concentrations in Kosovo soil and water samples as well as
biological samples were investigated. It was found that the uranium concentrations in the Kosovo soil samples are in the range
of 11.3-2.26·105 Bq·kg-1 for 238U, 10.3-3.01·104 Bq·kg-1 for 234U, 0.60-3251 Bq·kg-1 for 235U, and £0.019-1309 Bq·kg-1 for 236U. The obtained activity ratios are in the range of 0.112-1.086 for 234U/238U, 0.0123-0.1144 for 235U/238U, and 0-0.0078 for 236U/238U, indicating the presence of DU in about 77% of the surface soil samples. At a specific site, the DU inventory in the surface
soil is about 140 mg·cm-2, which is 1.68·106 times higher as the estimated mean DU dispersion rate in the region. The uranium concentrations in Kosovo lichen, mushroom,
bark, etc., are in the range of 1.97-4.06·104 Bq·kg-1 for 238U, 0.48-5158 Bq·kg-1 for 234U, 0.032-617 Bq·kg-1 for 235U, and £0.019-235 Bq·kg-1 for 236U with mean activity ratios of 0.325±0.0223 for 234U/238U, of 0.0238±0.0122 for 235U/238U, and 0.0034±0.0028 for +U/238U, indicating the presence of DU in the entire sample. On the contrary, the uranium concentrations in Kosovo water samples
are low, compared with the water samples collected in central Italy, indicating the presence of negligible amount of DU. The
uranium isotopes in Kosovo waters do not constitute a risk of health at the present time.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
22.
Thomas H. Webb Lisa M. Thomasco Stephen T. Schlachter John J. Gaudino Craig S. Wilcox 《Tetrahedron letters》1988,29(52):6823-6826
In reactions with stabilized ylides, γ-lactols of ribo configuration afford 90% Z-olefins whereas γ-lactols of allo configuration afford predominantly E-olefins. Lactols of arabino configuration give intermediate results. The unusual results in the ribo series completely disappear on protection of the γ-hydroxyl group. 相似文献
23.
Silvia Tagliapietra Emanuela CalcioGaudino Katia Martina Alessandro Barge Giancarlo Cravotto 《Chemical record (New York, N.Y.)》2019,19(1):98-117
A combination of microwave irradiation and flow chemistry has been described as a promising smart and hyphenated technology that can fuse and synergize the benefits of the techniques. The cells and tissues of all living organisms promote a huge number of bioorganic reactions that occur as flow systems and not the batch‐type conditions typically used by chemists and biotechnologists. Microwave‐assisted chemical conversion carried out in continuous flow mode with micro‐ or meso‐channel reactors can offer significant processing advantages, including improved thermal exchange, energy efficiency, safety, mixing control, a wider range of reaction conditions, repeatability and scalability as well as dramatic reductions in side‐reactions and degradations. This review will discuss relevant examples of organic synthesis and nanoparticles production performed in continuous flow mode with integrated microwave irradiation in micro‐ or mesofluidic systems. 相似文献
24.
Giorgio Grillo Emanuela Calcio Gaudino Roberto Rosa Cristina Leonelli Ana Timonina Saulius Grygikis Silvia Tabasso Giancarlo Cravotto 《Molecules (Basel, Switzerland)》2021,26(4)
Aiming to fulfil the sustainability criteria of future biorefineries, a novel biomass pretreatment combining natural deep eutectic solvents (NaDESs) and microwave (MW) technology was developed. Results showed that NaDESs have a high potential as green solvents for lignin fractionation/recovery and sugar release in the following enzymatic hydrolysis. A new class of lignin derived NaDESs (LigDESs) was also investigated, showing promising effects in wheat straw delignification. MW irradiation enabled a fast pretreatment under mild condition (120 °C, 30 min). To better understand the interaction of MW with these green solvents, the dielectric properties of NaDESs were investigated. Furthermore, a NaDES using the lignin recovered from biomass pretreatment as hydrogen bond donor was prepared, thus paving the way for a “closed-loop” biorefinery process. 相似文献