Search results for "Ilici"
showing 10 items of 238 documents
Una asociación peculiar de fusulinas en las calizas de Tanes, sección de Campo de Caso (Pensilvánico, Moscoviense superior; zona Cantábrica, España)
2021
The Campo de Caso section (eastern part of the Cantabrian Zone, NW Spain) exposes a middle to upper Moscovian (Middle Pennsylvanian) succession, up to 3500-m thick, consisting of marine shelfal and deltaic siliciclastic and shale deposits with numerous intercalated fossiliferous limestones. A limestone outcropping in the upper part of this section, close to the village of Tanes, has yielded a fusuline assemblage composed of species of the genera Eostaffella, Pseudonovella, Ozawainella, Pseudostaffella, Neostaffella, Schubertella, Fusiella, Taitzehoella, Fusulinella, Beedeina and Putrella . The specific composition of these genera, considered as a whole, indicates an early to mid- Myachkov…
Gas-liquid chromatography as a tool for evaluation of lipophilicity of selected esters of aromatic and aliphatic acids
1986
Abstract The use of gas-liquid chromatographic retention values for the determination of lipophilicity was studied for series of esters of aromatic and aliphatic acids and for series of aliphatic alcohols. The regression relationships between the logarithms of the partition coefficients and the retention characteristics measured on two capillary columns, SE-30 and OV-351, differing markedly in polarity, were evaluated. It may be deduced that, for the structurally similar compounds, the stationary phases used simulate the reference partitioning system octanol-water.
Skin permeation model of phenyl alcohols: comparison of experimental conditions
1998
Abstract This study was conducted primarily to establish the significance of the experimental conditions in the determination of permeability coefficients. In order to do this, standard in vitro skin permeation methods were used to determine the permeability coefficient (kp) of a homologous series of phenyl alcohols, with a wide range of lipophilicity, by two different experimental conditions through rat skin; first, using solutions (at 75% saturation concentration) of the penetrants in the donor compartment and second using saturated solutions added with an excess of the penetrant. The kp values obtained by these techniques were compared. Solubility of the phenyl alcohols in the donor phas…
Identification of binding peptides on calcium silicate hydrate: a novel view on cement additives.
2014
Cement is the most used industrial product in the world. Although the chemical composition of the material has stayed more or less the same since its discovery by the Romans around 2000 years ago, [ 1 ] the performance has been increased by chemical additives. Spectacular buildings like the Willis Tower in Chicago, Taipei 101 or lately the over 800 m high Burj Khalifa in Dubai were realizable thanks to the development of high performance building materials. [ 2 ] Not only for such prestige objects but also in daily building processes, the trend goes towards always higher buildings because of the continued urbanization which was identifi ed already in 1982 as one of the so-called “megatrends…
Estimation of the effect of the acidosis and alkalosis on the anesthetic potency of local anesthetics by biopartitioning micellar chromatography and …
2004
Local anesthetics are hydrophobic compounds and weak bases with protonation constants ranged between 7.5 and 8.8. These drugs block reversibly nerve conduction near their site of application or injection and thus produce temporary loss of feeling or sensation in a limited area of the body. The efficacy of anesthetic blockade of local anesthetics depends on the charged/uncharged form ratio and the hydrophobicity of the compounds. In addition their toxicological effects have been reported to be highly dependent on the physiological pH. Biopartitioning micellar chromatography (BMC) and micellar electrokinetic chromatography (MEKC), that use micellar solutions as mobile phases, have proven to b…
H2-antihistaminics. 20. Structure-activity relationships in H2-receptor antagonists containing a 4-pyrimidone moiety.
1984
In a series of 5,6-substituted 4- pyrimidones 1 a-v the H2-antihistaminic activity was determined (guinea-pig atrium) and lipophilicity data are given in form of Rmo -values. The influence of different substituents at position 5 or 6 of a pyrimidone moiety has been studied. Quantitative structure-activity analyses showed the importance of lipophilicity for drug activity. Additionally other physicochemical substituent-properties may play a major role.
Gradients in physical parameters in zoned felsic magma bodies: Implications for evolution and eruptive withdrawal
1990
Abstract Five diverse, well documented, chemically zoned magmas have been chosen from the literature to demonstrate the extent and patterns of density and viscosity gradients in zoned magma chambers. The patterns are used to assess implications for development of zonation, and withdrawal dynamics and preservation of systematic chemical variations in the final pyroclastic deposit. These examples are: Bishop Tuff, California (high-silica rhyolite); Los Humeros, Mexico (calc-alkaline rhyolite to andesite); Fogo A, Azores (trachyte); Laacher See, Eifel (phonolite) and Tenerife, Canary Islands (phonolite). It was necessary to make several simplifying assumptions in order to calculate viscosity a…
Biosilicification of loricate choanoflagellate: organic composition of the nanotubular siliceous costal strips of Stephanoeca diplocostata.
2010
SUMMARY Loricate choanoflagellates (unicellular, eukaryotic flagellates; phylum Choanozoa) synthesize a basket-like siliceous lorica reinforced by costal strips (diameter of approximately 100 nm and length of 3 μm). In the present study, the composition of these siliceous costal strips is described, using Stephanoeca diplocostata as a model. Analyses by energy-dispersive X-ray spectroscopy (EDX), coupled with transmission electron microscopy (TEM), indicate that the costal strips comprise inorganic and organic components. The organic, proteinaceous scaffold contained one major polypeptide of mass 14 kDa that reacted with wheat germ agglutinin. Polyclonal antibodies were raised that allowed …
A latest Biharian small vertebrate fauna from the lacustrine succession of San Lorenzo (Sant’Arcangelo Basin, Basilicata, Italy)
2005
Abstract The Sant’Arcangelo Basin is located in the southern part of the Apennine chain (Basilicata). It is filled by a siliciclastic sequence 3500 m thick, dated to the Late Pliocene–Middle Pleistocene time interval. In this basin an Early Middle Pleistocene fluvio-lacustrine sequence, known as San Lorenzo Cycle, has been recognised. In the upper part of the sequence, in Rifreddo, a fairly diversified small vertebrate assemblage has been recovered. The occurrence of Mimomys savini allows to the fauna to be considered as Biharian. The presence of some faunal elements such as Microtus ( Terricola ) arvalidens, Microtus ( Iberomys ) ex gr . huescarensis-brecciensis, and Macroneomys cf. brachy…
Structural Approaches to Explain the Selectivity of COX-2 Inhibitors: Is There a Common Pharmacophore?
2000
The identification and characterisation of the isoenzyme cyclooxygenase 2 (COX-2) stimulated investigations to develop efficient non-steroidal anti-inflammatory drugs with reduced side effects compared to standard NSAIDs. This review will focus on the structural features needed to achieve COX-2 selectivity. Five structural classes can be identified together with a class bearing little or no resemblance to one another in their molecular structure. The most interesting point is the very distinct structure/activity relationship. On the one hand only minor modifications to a particular compound induce a drastic change in its COX selectivity and on the other hand the structural prerequisites in …