Search results for "chemistry.chemical_classification"
showing 10 items of 10585 documents
Automated detection of protein unfolding events in atomic force microscopy force curves
2016
Atomic force microscopy is not only a high-resolution imaging device but also a mechanical machine, which can be used either to indent or stretch (soft) biomaterials. Due to the statistical nature of such materials (i.e., hydrogels or polymers) hundreds of force-distance curves are required to describe their mechanical properties. In this manuscript, we present an automated system for polymer unfolding detection based on continuous wavelet analysis. We have tested the automated program on elastin, which is an important protein that provides elasticity to tissues and organs. Our results show that elastin changes its mechanical behavior in the presence of electrolytes. In particular, we show …
Influence of negative allosteric cooperativity in cation transport.
1992
Abstract The bis-macrocyclic ether5 seems to have a negative allosteric cooperativity and is able to transport double the amount of Na+ and K+ cations as monocyclic systems. This compound could be used as a simple model of the plasma membrane Na+−K+ ATPase which actively pumps Na+ out and K+ into the cell, respectively.
Metal ion-promoted activation of amino acid esters of carbohydrates in the synthesis of peptides
1992
Abstract Carbohydrate esters 1 and 2 of N-protected amino acids are activated by coordination of metal ions and subjected to aminolysis by amino acid esters 3 to form peptides 4 .
Model compound synthesis for the structure determination of new unknown planar aromatic compounds originating from pulp mill
1991
Abstract Several model compounds have been synthesized for verification of the structures of new unknown planar aromatic compounds (UPACs) observed in high-resolution gas chromatography/low-resolution mass spectrometry analyses of the polychlorodibenzodioxins (PCDDs) and polychlorodibenzofurans (PCDFs) in pulp mill products, effluents, sediments and mussels. The mass spectra of synthetic alkyl polychlorodibenzofurans (C6-PCDFs) were different, but those of alkyl polychlorobibenzyls (C5-PCBBs) were very similar compared to the spectra of UPACs.
Crystal structures, infrared-spectra, and thermal behavior of calcium hydrogenselenite monohydrate, Ca(HSeO3)2 · H2O, and dicalcium diselenite bis(hy…
1986
Abstract Calcium hydrogenselenite monohydrate and dicalcium diselenite bis(hydrogenselenite) were synthesized and their crystal structures determined. Crystal data for Ca(HSeO3)2 · H2O: a = 6.911(2), b = 7.369(2), c = 6.739(2) A, α = 90.51(3)°, β = 90.93(3)°, γ = 107.46(2)°, V = 327.3(2) A3, space group P 1 (No. 2), dcalcd = 3.19 M gm−3, Z = 2, and R = 0.036 for 1503 reflections. Data for Ca2(HSeO3)2(Se2O5): a = 14.719(4), b = 7.059(2), c = 11.793(2) A, β = 117.96(2)°, V = 1082.3(4) A3, space group C2 c (No. 15), dcalcd = 3.52 Mg m−3, Z = 4, and R = 0.047 for 1251 reflections. Both structures form a three-dimensional network. The coordination polyhedron around calcium is a monocapped trigon…
Designing Medical Devices Based on Silicon Polymeric Material with Controlled Release of Local Anesthetics
2012
The drug delivery systems that are the object of this article take the form of a polymer matrix made of silicone containing a drug. These devices can be used as patches for local dermal applications releasing the drug in a controlled manner. The model active agent, lidocaine hydrochloride was chosen from the range of local anesthetics. When the drug is restricted to the surface, it is released more rapidly than when it is allowed to spread evenly throughout the silicon structure. When hydrophilic polymers such as PVA and HEC are mixed in with the lidocaine hydrochloride and deposited on the surface of the polymer matrix, we observed that the burst effect was eliminated without modifying the…
SKRINING FITOKIMIA, UJI AKTIVITAS ANTIMIKROBA DAN ANTITUMOR TUMBUHAN OBAT KABUPATEN MANOKWARI
2008
<p><em>Pythochemistry screening and testing of antimicrobial and antitumor activities was carried out on 31 species of medicinal plants distributed around Manokwari Regency. All parts of the plants were collected and screened for the presence of alkaloids, saponins, and tannins; antimicrobial and antitumor activity. The number of positive tests obtained are 17 (55, 3%) for alkaloids, 6 (19, 4%) for saponins, and 26 (84, 7%) for tannins. Eleven species shown inhibition activities (antimicrobial) to Candida albicans, Staphyloccocus aureus, and Echericia colii while only seven species have antitumor activity, especially against tumor cell P-388. </em></p>
Anaerobic oxidation of methane in sediments of a nitrate-rich, oligo-mesotrophic boreal lake
2021
AbstractThe identity of electron acceptors in promoting anaerobic oxidation of methane (AOM) in the sediments of boreal lakes is currently unknown. Here, we studied the AOM rate of sediment slurries collected from three profundal stations of a nitrate-rich, oligo-mesotrophic, boreal lake (Lake Pääjärvi, Finland), under varying nitrate concentrations using 13C-labelling. Furthermore, vertical profiles of the sediment and porewater geochemistry, and the microbial communities (16S rRNA gene and shotgun metagenomic sequencing) were analyzed. Despite geochemical data indicating that simultaneous consumption of nitrate and methane took place at the sediment layers chosen for incubations, AOM rate…
Development of core-shell colloids to study self-diffusion in highly concentrated dispersions
2007
To study single particle motion in highly concentrated colloidal dispersions, a host-tracer colloid system was developed, consisting of crosslinked polymer micronetwork spheres placed in a good solvent. The host colloid is made invisible to the experimental probe by matching its refractive index to that of the solvent. For the tracer particles a core-shell structure was chosen to ensure the interaction potential to be identical to that of the host particles. Therefore the shell was made of the same polymer as the host. The core differs in refractive index from the solvent and is therefore visible due to scattered light.
Intestinal conversion of linoleic acid to arachidonic acid in the rat
1993
Abstract The arachidonic acid (C20:4, n-6) appearing in intestinal lymph during linoleic acid (C18:2, n-6) absorption may originate from enterocyte synthesis or from the liver either after secretion in biliary phospholipids at the same time dietary linoleic acid absorption occurs or via plasma. The radioactivity measured in the total bile collected during the 6 hours of linoleic acid absorption is too small to explain hepatic origin of the C20:4 detected by high performance liquid chromatography analysis of labeled fatty acids recovered in the lymph, in the intestinal mucosa, and the intestinal wall at the peak of linoleic acid intestinal absorption. This study confirms the probability that…