Search results for "Quaternary"

Mūsdienu ledāji

2021

Monogrāfijas mērķis ir iepazīstināt Zemes zinātņu un citu dabaszinātņu studentus un plašāku sabiedrību ar jautājumiem par mūsdienu ledāju un ledus vairogu attīstību, klasifikāciju, plūsmas mehānismiem, deformāciju, hidroloģiju, termālo struktūru, izplatību, izmaiņām un aktuālākajiem zinātniskajiem pētījumiem, kā arī ar Latvijas Universitātes zinātnieku polāro ekspedīciju organizāciju, norisi un rezultātiem. Galvenā uzmanība grāmatā pievērsta mūsdienu ledāju, galvenokārt Arktikas un Antarktikas reģionu ledus vairogu, raksturojumam, jo šie ledāji ietver lielāko daļu pasaules ledāju ledus masas. Papildus aplūkota arī ledus un ledājiem līdzīgu formu izplatība Saules sistēmas debess ķermeņos. Vi…

Is the Rigidity of SARS-CoV-2 Spike Receptor-Binding Motif the Hallmark for Its Enhanced Infectivity? Insights from All-Atom Simulations

2020

The severe acute respiratory syndrome coronavirus (SARS-CoV-2) pandemic is setting the global health crisis of our time, causing a devastating societal and economic burden. An idiosyncratic trait of coronaviruses is the presence of spike glycoproteins on the viral envelope, which mediate the virus binding to specific host receptor, enabling its entry into the human cells. In spite of the high sequence identity of SARS-CoV-2 with its closely related SARS-CoV emerged in 2002, the atomic-level determinants underlining the molecular recognition of SARS-CoV-2 to the angiotensin-converting enzyme 2 (ACE2) receptor and, thus, the rapid virus spread into human body, remain unresolved. Here, multi-m…

STOP 7: Madona-Trepe ice-marginal ridge at Smeceres sils, East-Latvian Lowland

2014

New insights on ice dynamics from analysis of terrain of Latvia

2019

A new hyaluronic acid pH sensitive derivative obtained by ATRP for potential oral administration of proteins

2013

Atom transfer radical polymerization (ATRP) has been successfully employed to obtain a new derivative of hyaluronic acid (HA) able to change its solubility as a function of external pH and then to be potentially useful for intestinal release of bioactive molecules, included enzymes and proteins. In particular, a macroinitiator has been prepared by linking 2-bromo-2-methypropionic acid (BMP) to the amino groups of ethylenediamino derivative of tetrabutyl ammonium salt of HA (HA-TBA-EDA). This macroinititor, named HA-TBA-EDA-BMP has been used for the ATRP of sodium methacrylate (MANa) using a complex of Cu(I) and 2,2'-bipyridyl (Byp) as a catalyst. The resulting copolymer, named HA-EDA-BMP-MA…

Synthesis of Both Ionic Species of Ammonium Dithiocarbamate Derived Cholic Acid Moieties

2011

The reaction of 3-aminopropylamide of cholic acid with CS2 produced a bile acid derivative of dithiocarbamic acid which further formed an ammonium salt with another molecule of 3-aminopropylamide of cholic acid. The cationic 3-ammonium propylamide of cholic acid did not react further with CS2 and the formed salt was stable in the reaction mixture, even when excess CS2 was used. When the reaction was carried out in the presence of aqueous sodium hydroxide, only the bile acid derivative of sodium dithiocarbamate was formed. The dithiocarbamate derivatives were characterized by 1H- and 13C-NMR spectroscopy and ESI-TOF mass spectrometry.

α,β-poly(asparthylhydrazide)–glycidyltrimethylammonium chloride copolymers (PAHy–GTA): novel polymers with potential for DNA delivery

2001

Hydrophilic polycations form complexes when mixed with plasmids. Following functionalisation with glycidyltrimethylammonium chloride (GTA) alpha,beta-poly(asparthylhydrazide) (PAHy), a water-soluble synthetic macromolecule, becomes polycationic and potentially useful for systemic gene delivery. Initially the biocompatibility of PAHy and PAHy-GTA derivatives with different degrees of positive charge substitution were studied and it was shown that PAHy-GTA was neither haemolytic nor cytotoxicity up to 1 mg/ml. After intravenous injection (125)I-labelled PAHy-GTA derivative containing 46 mol% (PAHy-GTA(b)) of trimethylammonium groups did not accumulate in the liver (4.1+/-0.9% of the recovered…

A barium method for the cytochemical detection of sulfated glycosaminoglycans in mast cells and basophilic leukocytes.

1999

Barium ions precipitate inorganic as well as organic sulfate compounds and they can be detected by a reaction with sodium rhodizonate. In this work, we describe the use of a barium method for the selective demonstration of sulfated glycosaminoglycans in cytoplasmic granules of mast cells and basophilic leukocytes. Methanol-fixed smears of mouse peritoneal mast cells and rat bone marrow basophils were treated with 5% BaCl2 for 10 min, followed by staining with either 0.2% sodium rhodizonate in 50% ethanol for 2 h at 60 degrees C, or 0.01% brilliant green in distilled water for 1 min. Light microscopic observation revealed a strong staining reaction of the cytoplasmic granules of these cell t…

Enhanced terminal room disinfection and acquisition and infection caused by multidrug-resistant organisms and Clostridium difficile (the Benefits of …

2017

Summary Background Patients admitted to hospital can acquire multidrug-resistant organisms and Clostridium difficile from inadequately disinfected environmental surfaces. We determined the effect of three enhanced strategies for terminal room disinfection (disinfection of a room between occupying patients) on acquisition and infection due to meticillin-resistant Staphylococcus aureus , vancomycin-resistant enterococci, C difficile , and multidrug-resistant Acinetobacter . Methods We did a pragmatic, cluster-randomised, crossover trial at nine hospitals in the southeastern USA. Rooms from which a patient with infection or colonisation with a target organism was discharged were terminally dis…

Nicotine receptors do not modulate the 3H-noradrenaline release from the isolated rat heart evoked by sympathetic nerve stimulation.

1982

Isolated rat hearts with the right sympathetic nerves attached were perfused at a constant flow rate of 7 ml/min with Tyrode's solution. (-)-3H-Noradrenaline (final concentration 10–13.9 nM) was infused for 10 min to label the noradrenaline stores. After wash-out the sympathetic nerves were stimulated electrically (3 Hz, 180 impulses, 1 ms, 20–30 mA) three times (S1–S3) at intervals of 15 min. 3H-Noradrenaline and its metabolites were determined by liquid scintillation counting according to Graefe et al. (1973). Both, nicotine 50 μM and p-aminophenethyltrimethylammonium (PAPETA) 30 μM, enhanced the 3H-noradrenaline overflow in the absence of nerve stimulation. The effect of PAPETA was bipha…