295 research outputs found
Charge-displacement analysis as a tool to study chalcogen bonded adducts and predict their association constants in solution
The secondary interaction between a polarized chalcogen atom and different Lewis bases, either anionic
or neutral, has been studied by charge displacement analysis. Using charge displacement analysis, the
charge rearrangement in the adduct upon the formation of the interaction has been quantified and
described in great detail. By comparing the theoretical results with the experimental association con-
stants, two linear correlations can be found for anionic and neutral bases. Such correlations can be used
to reliably predict the association constants of adducts for which experimental data are not available yet
Organoselenium Compounds as Phytochemicals from the Natural Kingdom.
Selenium is naturally present in soils but it is also produced by pollution from human activities into the environment. Its incorporation into plants affords organoselenium metabolites that, depending on the nature of the molecules and the plant species, can be incorporated into proteins, stored or eliminated by volatilization. The possibility to use the selenium metabolism of some plants as a method for bioremediation and, at the main time, as a source of selenated phytochemicals is here discussed taking into consideration the growing interest in organic selenium derivatives as new potential therapeutic agents
Monitoring and understanding crustal deformation by means of GPS and InSAR data
Monitoring deformation of the Earth’s crust by using data acquired by both the GNSS and SAR techniques allows
describing crustal movements with high spatial and temporal resolution. This is a key contribution for achieving a
deeper and better insight of geodynamic processes. Combination of the two techniques provides a very powerful
means, however, before combing the different data sets it is important to properly understand their respective
contribution. For this purpose, strictly simultaneous and long time series would be necessary. This is not, in
general, a common case due to the relatively long SAR satellites revisit time. A positive exception is represented
by the data set of COSMO SKYMed (CSK) images made available for this study by the Italian Space Agency
(ASI). The flyover area encompass the city of Bologna and the smaller nearby town of Medicina where permanent
GPS stations are operational.
At the times of the CSK flyovers, we compared the GPS and SAR Up and East coordinates of a few stations as
well as differential tropospheric delays derived by both techniques. The GPS time series were carefully screened
and corrected for the presence of discontinuities by adopting a dedicated statistical procedure. The comparisons
of both the estimated deformation and the tropospheric delays are encouraging and highlight the need for having
available a more evenly sampled SAR data set
Agarsenone, a Cadinane Sesquiterpenoid from Commiphora erythraea
Agarsenone (1), a new cadinane sesquiterpenoid, was isolated from the resin of Commiphora erythraea. The structures of 1 and its decomposition products agarsenolides (2a and 2b) and myrrhone (3) were established by extensive NMR spectroscopic analysis. The absolute configuration of 3 and the relative and absolute configurations of 1 were assigned by comparison of experimental and calculated optical rotatory dispersion and electronic circular dichroism spectr
HEDONIC ANALYSIS OF CELL PHONES SOLD WITH POST-PAID SERVICE PLANS IN BRAZIL
The aim of this paper is to analyze the determining factors for the pricing of handsets sold with service plans, using the hedonic price method. This was undertaken by building a database comprising 48 handset models, under nine different service plans, over a period of 53 weeks in 2008, and resulted in 27 different attributes and a total number of nearly 300,000 data registers. The results suggest that the value of monthly subscriptions and calling minutes are important to explain the prices of handsets. Furthermore, both the physical volume and number of megapixels of a camera had an effect on the prices. The bigger the handset, the cheaper it becomes, and the more megapixels a camera phone has, the more expensive it becomes. Additionally, it was found that in 2008 Brazilian phone companies were subsidizing enabled data connection handsets
organoselenium compounds an overview on the biological activities beyond antioxidant properties
For a long period, Selenium was considered mainly a toxic element and has been the object of disputes for its controversial balance between beneficial and toxic effects. Nowadays, many evidences demonstrated its role as essential microelement in mammalian diet, having an essential role in redox homeostasis of all the living systems. Around 25 proteins were discovered to contain a selenocysteine in the place of the more common sulfureted amino acid and, in this protein, selenium have the main role in the catalytic center and playng a key role in several major metabolic pathways such as thyroid hormone metabolism, antioxidant defense systems, and immune functions. Many studies report that selenium has a protective effect against some forms of cancer decreases, cardiovascular disease mortality, regulates the inflammatory mediators in asthma, maintains bone homeostasis and protects against bone loss. Antioxidant activities of organoselenium compounds has been widely studied and discussed in a number of recent review article. In this communication taking inspiration from a number of recent publications we want to highlight that other biological activities can be envisioned for organoselenium compounds deriving from the peculiar reactivity of this element
DES as a green solvent to prepare 1,2-bis-organylseleno alkenes. Scope and limitations
We describe here our results on the use of choline chloride/urea 1:2 as a deep eutectic solvent (DES) in the synthesis of vinyl selenides. A good selectivity for the (E)-1,2-bis-organylseleno alkenes was observed starting from terminal alkynes and diaryl or dibutyl diselenides in the presence of NaBH4. The reaction of 1,3-butadiynes with diphenyl diselenide afforded exclusively the respective mono-selenylated (Z)-alkenynes. Diphenyl ditelluride reacted with phenylacetylene and 1,4-diphenyl-but-1-en-3-yne affording (Z)-phenyltelluro alkenes in good yields
Eosinophil as a cellular target of the ocular anti-allergic action of mapracorat, a novel selective glucocorticoid receptor agonist
Abstract: Purpose: Glucocorticoids can either suppress gene transcription (transrepression) or activate it (transactivation). This latter process may contribute to certain side effects caused by these agents. Mapracorat (also known as BOL-303242-X or ZK 245186) is a novel selective glucocorticoid receptor agonist that maintains a beneficial anti-inflammatory activity but seems to be less effective in transactivation, resulting in a lower potential for side effects; it has been proposed for the topical treatment of inflammatory skin disorders. This study assessed the anti-allergic activity of mapracorat at the ocular level and whether eosinophils and mast cells are targets of its action
Subcutaneous Direct-to-Implant Breast Reconstruction: Surgical, Functional, and Aesthetic Results after Long-Term Follow-Up
BACKGROUND: Direct-to-implant breast reconstruction can be achieved more easily by means of soft-tissue replacement devices such as dermal matrices and synthetic meshes. The feasibility of a subcutaneous approach has been recently investigated by some studies with different devices functioning as implant support. Aim of this study is to analyze the long-term results, both objective and subjective, of a previous nonrandomized trial comparing prepectoral (subcutaneous) and retropectoral breast reconstructions. METHODS: Patients enrolled in a nonrandomized prospective trial, comparing the standard retropectoral reconstruction and the prepectoral subcutaneous approach, using a titanium-coated mesh in both techniques, were followed up and evaluated for long-term results. Cases were compared in terms of the causes and rate of reinterventions, of the postoperative BREAST-Q questionnaire results, and of an objective surgical evaluation. RESULTS: The subcutaneous group had a rate of implant failure and removal of 5.1% when compared with 0% in the retropectoral group. Aesthetic outcome was significantly better for the subcutaneous group both at a subjective and at an objective evaluation. Capsular contracture rate was 0% in the subcutaneous group. CONCLUSIONS: A higher rate of implant failure and removal, although not significant, always because of skin flaps and wound problems, should be taken into account for a careful patients selection. The subcutaneous breast reconstruction shows good long-term results. A coherent subjective and objective cosmetic advantage of this approach emerges. Moreover, no capsular contracture is evident, albeit in a relatively limited number of cases
Reaction of Acyl Chlorides with In Situ Formed Zinc Selenolates: Synthesis of Selenoesters versus Ring-Opening Reaction of Tetrahydrofuran
Attempting to apply thein situproduction of PhSeZnSePh to the synthesis of selenoesters, an unexpected reaction involving the solvent (tetrahydrofuran) was observed and studied. We reported here some evidences about the mechanism and the possibility to control the chemoselectivity of this new reaction that afforded the formation of interesting selenoderivatives in which the selenium moiety and the carboxylic one are spaced by four carbon units
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