Search results for "cycle"
showing 10 items of 3119 documents
ChemInform Abstract: Kimberlite, Carbonatite, and Potassic Magmatism as Part of the Geochemical Cycle
2013
Iodolactonization of 3-Alkynylthiophene-2-Carboxylic and 3-Alkynylpicolinic Acids for the Synthesis of Fused Heterocycles
2020
The iodolactonization of 3-alkynylthiophene-2-carboxylic acids and 3-alkynylpicolinic acids has been investigated. Using I2 as the iodine source and NaHCO3 as the base in MeCN, the process took place smoothly to afford thienopyranones and pyranopyridinones, respectively, from 6-endo-dig cyclization. The method also worked nicely for the transformation of 2-(phenylethynyl)thiophene-3-carboxylic acid and 3-(phenylethynyl) isonicotinic acid into 7-iodo-6-phenyl-4H-thieno[3,2-c]- pyran-4-one and 4-iodo-3-phenyl-1H-pyrano[4,3-c]pyridin-1- one, respectively. Although with some 3-alkynylpicolinic acids the process led to a mixture of the 6-endo-dig and 5-exo-dig products, it could be still made se…
Synthesis ofo-thiatelluraphenylenezirconocenes. X-ray crystal structure of
1992
o-Thiatelluraphenylenezirconocene complexes were obtained in good yield by reaction of dilithiumo-benzenthiatelluride with zirconocene dichlorides. These compounds represent the first examples of heterodichalcogenaphenylene bent metallocences. They were characterized by spectroscopic methods and the effect on the n.m.r. results of stepwise substitution of one and two Te atoms for S is discussed.
In silico, spectroscopic, and biological insights on annelated pyrrolo[3,2-e]pyrimidines with antiproliferative activity
2013
The in silico COMPARE analysis was performed on 8-[3-(piperidino)propyl]-4,10-dimethyl-9-phenyl-6-(methylsulfanyl)-3,4-dihydropyrimido[1,2-c]pyrrolo[3,2-e]pyrimidin-2(8H)-one, a compound with promising antiproliferative activity, previously synthetized and screened against a panel of 60 human tumor cell lines. The results evidenced that this compound matches the biological properties of Chromomycin A3 and Actinomycin D, known drugs with high DNA binding affinity. Prompted by such results, a thorough spectroscopic investigation of its DNA aqueous solutions was performed, with the aim to verify its DNA-binding properties. DNA groove-binding interaction was assigned by UV-vis spectrophotometri…
Ethyl (2,3-dihydro-1H,1′H-2,3′-biindol-1-yl)glyoxylate
2007
The crystal structure of the title compound, C20H18N2O3, was determined in the course of our studies of the synthesis of 3-acylindole derivatives. We obtained it as an unexpected racemic side product. The crystal structure contains chains of dimers along the a axis.
Combined theoretical and experimental analysis of processes determining cathode performance in solid oxide fuel cells
2013
Solid oxide fuel cells (SOFC) are under intensive investigation since the 1980's as these devices open the way for ecologically clean direct conversion of the chemical energy into electricity, avoiding the efficiency limitation by Carnot's cycle for thermochemical conversion. However, the practical development of SOFC faces a number of unresolved fundamental problems, in particular concerning the kinetics of the electrode reactions, especially oxygen reduction reaction. We review recent experimental and theoretical achievements in the current understanding of the cathode performance by exploring and comparing mostly three materials: (La,Sr)MnO3 (LSM), (La,Sr)(Co,Fe)O3 (LSCF) and (Ba,Sr)(Co,…
Hypoxie beim Zervixkarzinom: Pathogenese, Charakterisierung und biologische/klinische Konsequenzen 1
2001
Approximately 60% of locally advanced carcinomas of the uterine cervix exhibit hypoxic and/or anoxic tissue areas which are heterogeneously distributed within the tumor mass. Hypoxia is caused by structural and functional abnormalities of the newly formed tumor vessels arising from neovascularization, by a disturbed microcirculation, enlarged diffusion distances and by tumor- or therapy-associated anemia. The extent of pretherapeutically measured hypoxic tissue areas is independent of clinical size, FIGO stage and histopathological grade of squamous cell carcinomas of the uterine cervix. Anemia can intensify tumor hypoxia. O2-tensions in local recurrences are even lower than those in the pr…
Mothers' abusive childhood predicts child abuse
1999
To examine the intergenerational transmission of abuse, the study compared 25 mothers whose child had been under the supervision of the child protection services (CPS) with 25 mothers who had had no contact with the CPS. The groups were compared with respect to their own self-reported childhood abuse, their abuse of their own child and punitiveness. The data were gathered using interviews and files. There were no significant differences between the groups in self-reported childhood physical abuse, but the CPS mothers had experienced more childhood psychological abuse, especially rejection, accusations, terrorizing and corrupting. The groups did not differ in the self-reported physical or ps…
An integrated approach based on Life Cycle Assessment and Thermoeconomics: Application to a water-cooled chiller for an air conditioning plant
2018
Abstract A large number of methods for energy systems analysis were developed in the last decades, aimed at acquiring an in-depth understanding of plant performances and enabling analysts to identify optimal design and operating conditions. In this work an integrated approach based on Life Cycle Assessment and Thermoeconomics is proposed as a method for assessing the exergo-environmental profile of energy systems. The procedure combines the capabilities of these two techniques, to account simultaneously for aspects related to thermodynamics of energy conversion processes and to the overall impacts along the plant life cycle related to other phases, i.e. from raw material extraction to the d…
Life Cycle Assessment Performance Comparison of Small Solar Thermal Cooling Systems with Conventional Plants Assisted with Photovoltaics
2012
Abstract Life Cycle Assessment (LCA) allows for the consideration of energy consumption and environmental impacts associated with all the stages of a product's life, from the cradle to the grave . Starting from the results obtained in the IEA SHC Task 38 framework for the LCA of small solar assisted heat driven chillers, the application of such methodology has been extended to systems with a conventional compression chiller assisted by a photovoltaic plant. This study aims to provide a more comprehensive investigation through a comparison of these two families of solar assisted cooling systems (with solar thermal or PV), which is an important topic for studies concerning the research of eff…