Search results for "Urea"
showing 10 items of 888 documents
Selective Recognition and Sensing of Succinate vs. Other Aliphatic Dicarboxylates by Thiourea-Functionalized Gold Nanoparticles
2016
Gold nanoparticles functionalized with thiourea moieties have been used as selective colorimetric sensors for the naked-eye detection of succinate versus other aliphatic dicarboxylates, all of them as their TBA salts. The detection process is based on the interparticle aggregation triggered by coordination of the end-carboxylates to the thiourea moieties of two different nanoparticles. This nanoparticle aggregation results in a batochromic shift of the plasmon resonance band and a visual color change from red to blue.
Mesoporous silica microparticles gated with a bulky azo derivative for the controlled release of dyes/drugs in colon.
2018
[EN] Mesoporous silica microparticles were prepared, loaded with the dye safranin O (M-Saf) or with the drug budesonide (M-Bud) and capped by the grafting of a bulky azo derivative. Cargo release from M-Saf at different pH values (mimicking those found in the gastrointestinal tract) in the absence or presence of sodium dithionite (a reducing agent mimicking azoreductase enzyme present in the colon) was tested. Negligible safranin O release was observed at pH 6.8 and 4.5, whereas a moderate delivery at pH 1.2 was noted and attributed to the hydrolysis of the urea bond that linked the azo derivative onto the external surface of the inorganic scaffold. Moreover, a marked release was observed w…
Factors associated with milk urea concentrations in Girgentana goats
2010
A total of 1,481 milk samples of 166 Girgentana goats, taken along the entire lactation, were utilised to evaluate the effect of non nutritional factors on milk urea (MU). Parity, stage of lactation and month of sampling significantly influenced MU, while no effect was found for born kids number. The first kidding goats produced lower MU than multiparous goats. Trend of MU was similar to milk production course with a peak found at 60 DIM. The different MU levels between several months of production are often linked to pasture chemical variations.
Märkälujaliimojen määritys pyrolyysi-kaasukromatografi-massaspektrometrillä
2017
Polymeerien, kuten märkälujaliimojen, analysoiminen on ollut nykyisillä menetelmillä erittäin työlästä tai hidasta. Pyrolyysi edustaa kuitenkin menetelmää, jolla esikäsittely ja aika saadaan minimiin. Menetelmässä näyte pilkotaan pienemmiksi yhdisteiksi, jolloin näyte saadaan helpommin analysoitavaan muotoon. Yleisimmin pyrolyysiä käytetään yhdessä kaasukromatografian kanssa. Työn kirjallisessa osassa perehdyttiin yleisimpien märkälujaliimojen valmistukseen, rakenteisiin ja ominaisuuksiin. Kirjallisuuskatsauksessa käytiin myös läpi pyrolyysin periaatteet, sovellukset sekä kartongin ja eräiden märkälujaliimojen pyrolyysituotteet. Lisäksi työssä perehdyttiin typpimäärityksiin. Työn kokeellise…
Persistence of oxidation state III of gold in thione coordination
2017
Ligands N,N'-tetramethylthiourea and 2-mercapto-1-methyl-imidazole form stable Au(III) complexes [AuCl3(N,N'-tetramethylthiourea)] (1) and [AuCl3(2-mercapto-1-methyl-imidazole)] (2) instead of reducing the Au(III) metal center into Au(I), which would be typical for the attachment of sulfur donors. Compounds 1 and 2 were characterized by spectroscopic methods and by X-ray crystallography. The spectroscopic details were explained by simulation of the UV-Vis spectra via the TD-DFT method. Additionally, computational DFT studies were performed in order to find the reason for the unusual oxidation state in the crystalline materials. The preference for Au(III) can be explained via various weak in…
D-pantenola saturošu preparātu un SIA "LMP" ražotā Bepaderm G gela stabilitātes pētījumi un sastāva optimizēšana
2019
Gels sastāv no vairāku vielu komponentiem- aktīvās vielas, šķīdinātāja, biezinātājvielas, emulgatora, konservanta u.c. vielām. Šo vielu savstarpējā mijiedarbība nodrošina preparāta stabilitāti, farmakoloģisko darbību un nosaka tā uzglabāšanas laiku. Mērķis ir izvērtēt esošo dekspantenolu saturošo preparātu sastāvus un optimizēt SIA “LMP” ražotā Bepaderm G gela sastāvu. Darba gaitā tika izvērtēti dažādu ražotāju dekspantenolu saturošu gelu un krēmu sastāvi, veikti SIA “LMP” ražotā Bepaderm G gela stabilitātes pētījumi un izveidoti jauni dekspantenolu saturošu gelu paraugi. Rezultātā tika konstatēts, ka gan karbomērs, gan hipromeloze ir pietiekami labas gela biezinātājvielas, dekspantenola ko…
Novedades sobre taxonomía y nomenclatura de híbridos vasculares españoles
1990
The nomenclature of some Iberian hybrids is revised and several new combinations are proposed: <i>Centaurea X subdecurrens</i> var. segobricensis, C.</i> X <i>subdecurrens</i> notbosubsp. <i>albuferae, Cistus</i> X <i>hybridus</i> nothosubsp. <i>grandiflorus</i> var. <i>secallianus. C.</i> X <i>ledon</i> var. <i>recognitus, C. </i>X <i>nigricans</i> var. <i>longifolius, C.</i> X <i>nigricans</i> nothosubsp. <i>grosii</i> and <i>Onopordum</i> X <i>humile</i> var. <i>turolensis</i>. Besides, a new nothosubspec…
Co-reductive fabrication of carbon nanodots with high quantum yield for bioimaging of bacteria
2018
A simple and straightforward synthetic approach for carbon nanodots (C-dots) is proposed. The strategy is based on a one-step hydrothermal chemical reduction with thiourea and urea, leading to high quantum yield C-dots. The obtained C-dots are well-dispersed with a uniform size and a graphite-like structure. A synergistic reduction mechanism was investigated using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The findings show that using both thiourea and urea during the one-pot synthesis enhances the luminescence of the generated C-dots. Moreover, the prepared C-dots have a high distribution of functional groups on their surface. In this work, C-dots proved …