Search results for "Critical"
showing 10 items of 3024 documents
Comparison of heparin to citrate as a catheter locking solution for non-tunneled central venous hemodialysis catheters in patients requiring renal re…
2014
Background The incidence of acute kidney injury (AKI) is estimated at 10 to 20% in patients admitted to intensive care units (ICU) and often requires renal replacement therapy (RRT). ICU mortality in AKI patients can exceed 50%. Venous catheters are the preferred vascular access method for AKI patients requiring RRT, but carry a risk of catheter thrombosis or infection. Catheter lock solutions are commonly used to prevent such complications. Heparin and citrate locks are both widely used for tunneled, long-term catheters, but few studies have compared citrate versus heparin for patients with short-term, non-tunneled catheters. We aim to compare citrate 4% catheter lock solution versus hepar…
Use of the Cultex® Radial Flow System as an in vitro exposure method to assess acute pulmonary toxicity of fine dusts and nanoparticles with special …
2013
Exposure of the respiratory tract to airborne particles (including metal-dusts and nano-particles) is considered as a serious health hazard. For a wide range of substances basic knowledge about the toxic properties and the underlying pathomechanisms is lacking or even completely missing. Legislation demands the toxicological characterization of all chemicals placed on the market until 2018 (REACH). As toxicological in vivo data are rare with regard to acute lung toxicity or exhibit distinct limitations (e.g. inter-species differences) and legislation claims the reduction of animal experiments in general ("3R" principle), profound in vitro models have to be established and characterized to m…
Centrifuge tests on strip footings on sand with a weak layer
2017
Tests on small-scale physical models of a strip footing resting on a dense sand bed containing a thin horizontal weak soil layer were carried out at normal gravity (1 g ). The results, reported in a companion paper, point out that the weak layer plays an important role in the failure mechanism and the ultimate bearing capacity of the footing if it falls within the ground volume relevant to the behaviour of the sand–footing system. The same problem was also investigated by means of centrifuge tests on reduced-scale models at 25 g and 40 g . The results of these tests, reported and discussed in this paper, confirm that failure mechanisms are governed substantially by the presence of the weak…
The influence of various synthesis methods on the catalytic activity of cerium oxide in one-pot synthesis of diethyl carbonate starting from CO2, eth…
2013
Different synthesis methods such as homogeneous precipitation at room temperature and supercritical water (T > 647 K and P > 22.1 MPa) were employed for cerium oxide preparation. Additionally, deposition of ceria on silica mesoporous material, SBA-15, was carried out. The obtained materials were characterized by means of X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, nitrogen physisorption, X-ray photoelectron spectroscopy and CO2 temperature programmed desorption. Considerable variations in physico-chemical properties of the resulting materials were observed. The catalytic activities of pristine cerium oxide and ceria loaded on SBA-15 support were…
Cancer care for the homeless population: a literature review
2020
Abstract Background The last global survey in 2005 of the United Nations estimated that 100 million people were homeless. Cancer is becoming one of the most important public health problems worldwide, but specifically, the prevalence of cancer-related mortality for the homeless population has been reported to be double compared to the average adult population. To date, health research pays insufficient attention to studying cancer and improving the delivery of cancer care for the homeless population. Methods A systematic literature review of relevant databases was employed to identify all the quantitative studies addressing cancer care for the homeless population in English, Spanish, French…
Critical point and coexistence curve properties of the Lennard-Jones fluid: A finite-size scaling study
1995
Monte Carlo simulations within the grand canonical ensemble are used to explore the liquid-vapour coexistence curve and critical point properties of the Lennard-Jones fluid. Attention is focused on the joint distribution of density and energy fluctuations at coexistence. In the vicinity of the critical point, this distribution is analysed using mixed-field finite-size scaling techniques aided by histogram reweighting methods. The analysis yields highly accurate estimates of the critical point parameters, as well as exposing the size and character of corrections to scaling. In the sub-critical coexistence region the density distribution is obtained by combining multicanonical simulations wit…
Micellization in Model Surfactant Systems
1999
Formation of micelles in model lattice surfactant systems was studied by a novel methodology based on grand-canonical Monte Carlo simulations. The methodology involves combining free-energy information from a series of simulations in small systems by histogram reweighting. The solution osmotic pressure as a function of overall volume fraction of surfactant shows a sharp break at the critical micelle concentration (cmc) at sufficiently low temperatures. Studies in larger systems at appropriate values of the surfactant chemical potential are used to investigate the size distribution of micellar aggregates. The methodology allows for a clear distiction between micellization and macroscopic pha…
Study of percolation and clustering in supercritical water-CO2 mixtures
2008
The microscopic structure of supercritical water-CO(2) mixture is investigated by neutron diffraction experiments exploiting the isotopic HD substitution. The investigated water reach mixtures are in the liquidlike region of the phase diagram, according to the behavior of the radial distribution functions, yet a reduction of the average number of hydrogen bonds, compared to equivalent states of pure water, is found. As a consequence, the average dimension of water clusters is reduced and the system stays below the percolation threshold. These results, along with the shift of the main peaks of the site-site radial distribution functions, suggest that the excess volume in these supercritical …
Synthesis of micro-mesoporous aluminosilicates on the basis of ZSM-5 zeolite using dual-functional templates at presence of micellar and molecular te…
2017
Abstract Micro-mesoporous aluminosilicates consisting of agglomerates of the ZSM-5 nanoparticles were obtained using dual-functional templates [C6H13–N+(CH3)2–C6H12–N+(CH3)2–C6H13](Br−)2 (C6–6–6Br2), [C8H17–N+(CH3)2–C6H12–N+(CH3)2–C8H17](Br−)2 (C8–6–8Br2). Aluminosilicates with randomly oriented flake-like particles built from ZSM-5 layers were obtained using [C16H33–N+(CH3)2–C6H12–N+(CH3)2–C6H13](Br−)2 (C16–6–6Br2). Use of С8–6–8Br2 and additive of cetyltrimethylammonium bromide CTAB (CTAB concentration is lower than the first critical micelle concentration, CMC1) leads to an increase of the total specific surface area, mesopore surface area and the mesopore size uniformity in the product,…
Some observations on the fluorometric determination of metallic elements in micellar media
1989
Abstract Experimental evidence is given allowing us to interpret why the detection limits obtained in micellar media are higher than those expected according to fluorescence enhancements for the niobium-lumogallion-tartrate system in the presence of different nonionic surfactants. The residual fluorescence of the surfactant solution and the competitive interaction with micelles between complexes and free ligands were studied. Near the critical micelle concentration of surfactants, remarkable changes in the emission spectra were observed in the case of both complex and free ligand solutions, which indicate the existence of interactions between the chemical system and surfactant monomers and …