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•SnO, ZrO2 and CeO2 modified TiO2 show reduced band gaps compared to unmodified TiO2.•Formation of oxygen vacancies in all nanocluster modifiers is more favourable than in unmodified ...TiO2.•CO2 adsorbs strongly at reduced ZrO2 to form carbonates.•CO2 can interact with reduced CeO2 to break a CO bond and form free CO.
The reduction of CO2 to fuels is an active research topic with much interest in using solar radiation and photocatalysts to transform CO2 into higher value chemicals. However, to date there are no photocatalysts known that can use solar radiation to efficiently reduce CO2. One particularly difficult problem is activating CO2 due to its high stability. In this paper we use density functional theory simulations to study novel surface modified TiO2 composites, based on modifying rutile and anatase TiO2 with molecular-sized metal oxide nanoclusters of SnO, ZrO2 and CeO2 and the interaction between CO2 and nanocluster-modified TiO2. We show that reduction of the supported nanocluster is favourable which then provides reduced cations and sites for CO2 adsorption. The atomic structures and energies of different adsorption configurations of CO2 on the reduced modified TiO2 composites are studied. Generally on reduced SnO and CeO2 nanoclusters, the interaction of CO2 is weak producing adsorbed carbonates. On reduced ZrO2, we find a stronger interaction with CO2 and carbonate formation. The role of the energies of oxygen vacancy formation in CO2 adsorption is important because if reduction is too favourable, the interaction with CO2 is not so favourable. We do find an adsorption configuration of CO2 at reduced CeO2 where a CO bond breaks, releasing CO and filling the oxygen vacancy site in the supported ceria nanocluster. These initial results for the interaction of CO2 at surface modified TiO2 provide important insights for future work on CO2 reduction using novel materials.
Bis-ketal-protected diethyl galactarate was condensed with different diamines to prepare sugar-based polyamides. Ketal-protected polyamides, which are soluble in organic solvents, were deprotected ...with 90% trifluoroacetic acid to yield water insoluble materials. FTIR, NMR, GPC, MALDI-TOF, ESI and TGA techniques were used to characterize the structure and the properties of these biodegradable materials.
D-galactaric acid-based polyamides are complex mixtures of cyclic and linear structures. High molecular weight linear polymer formation was limited by competitive cyclization reactions. The percentage of cyclization was highly dependent on the nature of the diamine used. Polycondensation with linear aliphatic diamines favored the formation of macrocycles, identified by MALDI-TOF and ESI.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
The use of recycled asphalt shingles (RAS) as a partial replacement for petroleum-based virgin asphalt binder has received considerable attention in recent years. The objective of this study is to ...correlate the molecular structure of asphalt binders of conventional asphalt mixtures as well as of mixtures containing RAS with their cracking potential at intermediate temperature. Laboratory testing evaluated the molecular composition of asphalt binders obtained from asphalt mixtures evaluated in this study using gel permeation chromatography (GPC), extent of ageing using Fourier Transform Infrared spectroscopy, and fracture resistance of laboratory produced mixtures using the Semi-Circular Bending test at intermediate temperature. Molecular fractionation through GPC of RAS samples confirmed the presence of associated asphaltenes in greater concentrations than recycled asphalt pavement samples. High concentrations of high-molecular-weight asphaltenes decrease the fracture resistance of the asphalt mixtures. The use of rejuvenating agents, Cyclogen-L and Hydrogreen, did not reduce the concentration of the highly associated asphaltenes, and thus they failed to improve the cracking resistance of the asphalt mixtures evaluated in this study.
Objectives The purpose of this study was to compare the agreement between two heparin assays, Hepcon HMS plus/Kaolin-ACT and Anti-Xa, and their predictive power in detecting circulating heparin ...levels post-reperfusion of the liver graft when compared with thromboelastogram (TEG) r time ratio in patients undergoing orthotopic liver transplantation (OLT). Design Prospective, observational cohort study design. Setting Single center, university hospital. Participants Thirty-eight consecutive adults who had undergone liver transplant. Interventions None. Measurements and Main Results Paired arterial blood samples were collected before surgical incision, 5 minutes after administration of an average dose of 2,054±771 units of intravenous unfractionated heparin before caval cross-clamping, 5 minutes after portal reperfusion, 5 minutes after hepatic artery reperfusion, and 1 hour after hepatic artery reperfusion. The observations that heparin assay measurements were within the predetermined limits of agreement, strongly suggested the two heparin assays (Hepcon HMS plus and Anti-Xa assay) are interchangeable during prophylactic heparin dose therapy during OLT. Post-reperfusion, receiver operating characteristic curve analysis revealed high accuracy in measuring circulating heparin levels with both Anti-Xa and Hepcon HMS assays when compared with the TEG r time ratio assay. Conclusions The point-of-care Hepcon HMS plus/Kaolin-ACT (activated clotting time) assay appeared to be a reliable alternative to the more expensive and laboratory-required Anti-Xa assay in monitoring the response to intravenous heparin in patients undergoing OLT.
Amphibian skin has provided a wide range of biologically active alkaloids. During the past 30 years, over 400 alkaloids of over 20 structural classes have been detected. These include the ...batrachotoxins, which are potent and selective activators of sodium channels, the histrionicotoxins, which are potent noncompetitive blockers of nicotinic receptor-gated channels, the pumiliotoxins and related allo- and homo-pumiliotoxins, which have myotonic and cardiotonic activity due to effects on sodium channels, and epibatidine, which has potent antinociceptive activity due to agonist activity at nicotinic receptors. Further classes of alkaloids from amphibian skin include pyrrolidines and piperidines, decahydroquinolines, pyrrolizidines, various indolizidines, quinolizidines, and tricyclic gephyrotoxins, pyrrolizidine oximes, pseudophrynamines, coccinellines, and cyclopentaquinolizidines. Most alkaloids of amphibian skin appear to be sequestered from dietary arthropods. The source of the batrachotoxins, histrionicotoxins, pumiliotoxins, epibatidine, and certain izidines are unknown.
Summary
• Recent health care policies have resulted in patients having access to an integrated system of care that is quick and reliable. In concert with these changes, opportunities for professional ...development in nursing have increased, together with a reduction in the numbers of doctors. Advanced Nurse Practitioners (ANPs) have, therefore, developed to meet the complex demands of health care systems.
• This paper reports on a study that aimed to explore the current role of ANPs in primary care in the West Midlands region of the UK and how ANPs within three different nursing disciplines in primary care developed their roles over time.
• The study utilized a qualitative exploratory design incorporating a longitudinal element. Twenty‐one ANPs were interviewed during phase one, 15 of whom were interviewed again during phase two, approximately 15 months later. Their managers (where appropriate) were also interviewed during phase one.
• The findings reveal that the nature and focus of practice varies between disciplines. At the extreme practice end of the practice‐strategic continuum, Practice Nurse ANPs’ expertise lies in their advanced practical assessment and diagnosis of individual patients, with little opportunity for strategic development. Health Visitor and District Nurse ANPs operate at the strategic end of the practice‐strategic continuum, but operate differently at this level. Health Visitors, being community and public health focused are involved in multi‐agency work, practice development and policy formulation. District Nurses work with individual patients/carers and the nursing team, thus their involvement in strategic developments tends to focus at the patient care level, such as protocol and practice developments, although their work also involves work in all three other domains. Overall, the findings reveal a unique role for all three with a potential career pathway for ANPs to become Nurse Consultants in the future.
The main objective of this study was to establish the relationship between asphalt binder deformation properties at intermediate and low temperatures, its molecular compositions, and mix performance. ...To achieve this objective, nine straight binders obtained from two asphalt suppliers were tested using the ductility and the direct tensile tests. To assess the results of these tests, selected asphalt binders were evaluated using high pressure gel permeation chromatography (HP-GPC), differential scanning calorimetry (DSC), and dynamic mechanical analysis. Measurements showed that an inverse correlation exists between binder ductility at intermediate temperatures and failure strain at low temperatures. In other words, a binder that provides high ductility at intermediate temperatures would be characterized by poor elongation properties at low temperatures. This trend was related to the binder molecular compositions as characterized by HP-GPC. An increase in the binder content of low molecular weight results in an increase in its ductility at intermediate temperatures. However, an increase in paraffinic maltene content results in the binder tending to crystallize at higher temperatures as it approaches the glassy region. This was confirmed through DSC measurements, which showed that an increase in crystalline fractions may have a negative impact on the binder stiffness at low temperatures. In general, physical properties of the binder can be strongly linked to its molecular constituents. In addition, there was a positive correlation between the binder ductility and the measured tensile strength of the mixture as well as its strain at failure. Using a binder with a high ductility resulted in a mixture with greater indirect tensile strength and a stronger ability to resist cracking at intermediate temperatures.
Celotno besedilo
Dostopno za:
DOBA, FGGLJ, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
The influence of size and surface area of two different types of clay on the structure and characteristics of PEO/clay nanocomposites in the form of multilayered films is discussed. To search for new ...synergistic properties and/or improve the properties of nanocomposite films already known, we study polymer nanocomposites that have laponite as well as montmorillonite incorporated. While DSC measurements showed that higher laponite amounts gradually suppress the crystallinity of PEO in the nanocomposite, XRD measurements provided evidence that higher montmorillonite amounts ensure an improved final orientation of the clay platelets, parallel to the plane of the multilayered film.
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