scholarly journals Gas-Transport Characteristics of PdCu–Nb–PdCu Membranes Modified with Nanostructured Palladium Coating

2021 ◽  
Vol 23 (1) ◽  
pp. 228
Author(s):  
Iliya Petriev ◽  
Polina Pushankina ◽  
Nikita Shostak ◽  
Mikhail Baryshev
Keyword(s):  
Hydrogen Transfer ◽  
Membrane Surface ◽  
Protective Layer ◽  
Gas Diffusion ◽  
Threshold Temperature ◽  
Functional Layer ◽  
Cu Doping ◽  
Associative Processes ◽  
Significant Difference ◽  
Cost Efficient

A method for obtaining composite gas-diffusion PdCu–Nb–PdCu membranes modified with a nanostructured crystalline coating was developed to increase the performance of Nb-based membranes. A modifying functional layer with a controlled size and composition was synthesized by electrochemical deposition, which made it possible to determine a certain geometric shape for palladium nanocrystallites. Developed PdCu–Nb–PdCu membranes have demonstrated flux values up to 0.232 mmol s−1 m−2 in the processes of diffusion purification of hydrogen at 400 °C. A very significant difference in the hydrogen fluxes through the modified and non-modified composite PdCu–Nb–PdCu membranes reached 1.73 times at the lower threshold temperature of 300 °C. Cu doping of protective layer did not affect the selective properties of the membranes, which was confirmed by the obtained high selectivity values up to 1323, and made it possible to reduce the noble metal content. The research data indicate that the modification of the membrane surface significantly accelerates the hydrogen transfer process at sufficiently low temperatures due to the acceleration of dissociative–associative processes on the surface. The reported approach demonstrates new possibilities for creating productive and cost-efficient membranes based on niobium.

scholarly journals Nursing stress and satisfaction outcomes resulting from implementing a team nursing model of care in a rural setting

2017 ◽  
Vol 6 (1) ◽  
pp. 60 ◽  
Author(s):  
Linda Deravin ◽  
Karen Francis ◽  
Sharon Nielsen ◽  
Judith Anderson
Keyword(s):  
Nursing Staff ◽  
Rural Setting ◽  
Model Of Care ◽  
New Model ◽  
Safety Issues ◽  
Nursing Stress ◽  
Significant Difference ◽  
Cost Efficient ◽  
Team Nursing ◽  
Fiscal Considerations

Objective: With increasing demands to provide a cost efficient nursing service, changes to nursing skill mix are being implemented globally. Team nursing as a model of care is seen as a way to address both patient care and safety issues. The aim of this study was to explore job satisfaction (JS) and stress outcomes of nursing staff when introducing team nursing as model of care within the Australian healthcare environment.Methods: An experimental study was utilised. Nursing staff (n = 63) were surveyed, using the Person Centred Nursing Index (PCNI) tool, prior to the implementation of a team nursing model of care and then again six months post implementation of the model (n = 64). Data was analysed to determine if there was a statistically significant difference in the average theme between pre and post surveys.Results: Nursing stress (NS) was reduced and JS was increased post implementation of the new model of care. JS and organisational traits, JS and work stress (WS), were positively related and increased post implementation. WS and nursing care (NC), organisational traits and NC were positively related but showed no statistically significant change after the implementation. This study demonstrated that in introducing a new model of care, levels of stress staff increased yet unexpectedly JS also improved.Conclusions: Decisions to adopt team nursing as the model of care should be based on a broad range of considerations not simply on fiscal considerations and should include staff readiness, staff mix and supportive measures to introduce a changed model of care.

scholarly journals Radon Progeny Recoil Effect in Retrospective Indoor Glass Dosimetry

2020 ◽  
Vol 7 (1) ◽  
pp. 35-41
Author(s):  
C.D. Tibambre-Heredia ◽  
H. Olaya-Dávila ◽  
A.C. Sevilla ◽  
R. Samasundaram ◽  
J.A. Lopez ◽  
...  
Keyword(s):  
Structural Modification ◽  
Atomic Displacement ◽  
Gas Diffusion ◽  
Recoil Energy ◽  
Recoil Effect ◽  
Radon Progeny ◽  
Significant Difference ◽  
Geant4 Code ◽  
Diffusion Speed ◽  
Ion Recombination

Radon gas diffusion and progeny transport in air, are mechanisms to be considered in retrospective glass dosimetry.   With the aim to contribute to the understanding of the Rn progeny recoil energy role in this dosimetry methodology, we carried out a simulation employing GEANT4 code. In that, we assumed the chemical compound of the glass that is used commonly in households.  Results are compared to experimentally measured 210Bi concentration to show that the recoil energy helps the progenies incrustation, mainly for the 218,214Po alpha emitters but do not influence bismuth-210 diffusion directly. A significant difference exists between our results and measured values; that is interpreted as due to atomic displacement by primary knock-on atoms. The SiO2 molecule binding energy breaks and the following ion recombination, induce a structural modification between the atom by e.g. cavities formation in such a way that reduces significantly the radon progeny diffusion speed.

An ecology-based analysis of irreversible biofouling in membrane bioreactors

2007 ◽  
Vol 55 (8-9) ◽  
pp. 395-402 ◽  
Author(s):  
K. Zhang ◽  
H. Choi ◽  
M. Wu ◽  
G.A. Sorial ◽  
D. Dionysiou ◽  
...  
Keyword(s):  
Restriction Analysis ◽  
Membrane Surface ◽  
Acinetobacter Calcoaceticus ◽  
Paper Mill ◽  
Membrane Bioreactors ◽  
Bacterial Populations ◽  
Membrane Biofouling ◽  
Significant Difference ◽  
Microfiltration Membranes ◽  
Highly Correlated

To provide the first step towards a microbial ecology-based understanding of irreversible membrane biofouling, four laboratory-scale membrane bioreactors (MBRs) were operated to investigate the identity of bacterial populations highly correlated with irreversible membrane biofouling. The conventional MBR was divided into two separate experimental units. Unit one consisted of four suspended-growth, activated sludge, sequencing batch bioreactors treating a synthetic paper mill wastewater. Unit two consisted of a microfiltration membrane cell. Amplified ribosomal deoxyribonucleic acid restriction analysis (ARDRA) was used to compare the predominant bacterial populations in samples of mixed liquor and irreversibly bound to the membrane surface. The results of ARDRA showed a significant difference between the planktonic and sessile bacterial communities suggesting that irreversible biofouling of microfiltration membranes may be more highly correlated to specific bacterial populations rather than the total, bulk concentration of biomass. A custom-built mini-flow cell and light microscopy were used to visualise the early formation of biofilms by two pure cultures (Escherichia coli and Acinetobacter calcoaceticus) on membrane surfaces. The results confirmed that A. calcoaceticus was able to enhance the initiation of biofilm formation on microfiltration membranes.

EFFECTS OF AMBROSIA BEETLE ATTACK ON CERCIS CANADENSIS

IAWA Journal ◽  
2002 ◽  
Vol 23 (2) ◽  
pp. 143-160 ◽  
Author(s):  
Roland R. Dute ◽  
Michael E. Miller ◽  
Micheal A. Davis ◽  
Floyd M. Woods ◽  
Kathy S. McLean
Keyword(s):  
Ethylene Production ◽  
Protective Layer ◽  
Hyphal Growth ◽  
Cell Types ◽  
Ambrosia Beetle ◽  
Host Cell Response ◽  
Cercis Canadensis ◽  
Significant Difference ◽  
Extensive Growth ◽  
Micro Organisms

Damage caused to Cercis canadensis by the Asian ambrosia beetle and its associated micro-organisms was investigated as was host response to infestation. Various micro-organisms were connected with beetle infestation but only filamentous fungi exhibited extensive growth. In particular, species of Ambrosiella were associated with beetle tunnels. Fungal hyphae infected all cell types by growing directly through cell walls, by penetrating pit membranes, and by traversing perforations. Colonization of parenchyma was intensive and these cells probably provided the nutrients for continued hyphal growth. Host cell response to damage included breakdown of the protective layer of some parenchyma cells and accumulation of polysaccharide gels within vessel members. Measurements showed no significant difference in ethylene production by wood samples from infected versus uninfected trees. However, established literature indicates that damage-induced ethylene production was responsible for initiating events that caused vascular blockage by carbohydrate gel.

scholarly journals Glucose Levels During Dialysis with Glucose-Free Versus Glucose-Rich Dialysate Fluid

PRILOZI ◽  
2019 ◽  
Vol 40 (3) ◽  
pp. 41-46
Author(s):  
Irena Rambabova Bushljetik ◽  
Lada Trajceska ◽  
Vladimir Pusevski ◽  
Goce Spasovski
Keyword(s):  
Glucose Control ◽  
Membrane Surface ◽  
Glucose Variability ◽  
T Test ◽  
Diabetic Patients ◽  
Dialysis Session ◽  
Glycaemic Variability ◽  
Dialysis Unit ◽  
Significant Difference ◽  
The Mean

Abstract Introduction: Asymptomatic hypoglycaemia has been reported in both diabetic and non-diabetic patients on haemodialysis. Uremic symptoms as inadequate appetite, nausea and vomiting worsen the risk of hypoglycaemia at dialysis initiation. As a standard therapeutic approach for decreasing this risk and dis-equilibrium syndrome at our dialysis unit, a continuous venous 5% glucose solution is applied during the glucose-free dialysate (GFD) dialysis. In this interventional study we sought to assess the glycaemic control during standard initiating dialysis protocol versus novel approach with glucose-rich dialysis fluid (GRD). Material and methods: Twenty-one dialysis patients with chronic renal failure were dialyzed alternatively using GRD (5.6 mmol/l) and GFD fluid. They were not taking any hypoglycaemic medication prior and food during dialysis session. Blood was sampled at regular intervals during dialysis. The dialysis prescription consisted of ultrafiltration (UF) of up to 1 L, membrane surface (MS) up to 1.4 square meters and duration time of 2-2.5 hours. Intra-patient glycaemic variability was defined by Coefficient of variation (CV). In paired analysis t-test was used to determine the glucose control differences in both therapeutic approaches in each patient. For the whole group t-test was used to assess the glucose variability as CV. Results: The mean age of study participants was 62.95±11.73 years; 7 (33%) had diabetes. The two dialysis approaches did not differ in respect of initial blood pressure, UF and MS. Only two episodes of hypoglycaemia occurred in both types of dialysis. The mean glucose level was higher during GRD (8.15±1.89 vs. 6.29±1.33, p=0.001), respectively. The glucose CV was lower in GRD dialysis when pared t-test was applied, without significant difference (16.97± 8.86 vs. 21.05±11.99, p=0.151). When only diabetic patients were analysed, there was no significant glucose CV difference as well (p=0.151). For the whole cohort glucose variability was significantly higher in glucose-free dialysate dialysis (p=0.0001). Conclusion: The GRD approach for initiating dialysis sessions is non-inferior to standard GFD care. Dialysate rich in glucose obtains better glucose control during dialysis compared to glucose-free dialysate.

Torus-Bearing Pit Membranes in Cercocarpus

IAWA Journal ◽  
2010 ◽  
Vol 31 (1) ◽  
pp. 53-66 ◽  
Author(s):  
Roland Dute ◽  
Jaynesh Patel ◽  
Steven Jansen
Keyword(s):  
Secondary Wall ◽  
Membrane Surface ◽  
Parenchyma Cell ◽  
Protective Layer ◽  
Wall Material ◽  
Tracheary Elements ◽  
Bordered Pit ◽  
Parenchyma Cells ◽  
Conducting Cell ◽  
Cell Ontogeny

Intervascular pit membranes of Cercocarpus possess torus thickenings. The thickenings, or pads, consist of lignified, secondary wall material. Torus pad deposition occurs late in cell ontogeny and is not associated with a microtubule plexus. Half-bordered pit pairs between tracheary elements and parenchyma cells often have a torus pad on the membrane surface facing the conducting cell. In contrast, a thick protective layer fills the pit cavity on the side of the parenchyma cell. Ontogeny of the torus thickenings in Cercocarpus represents a third mode of torus development in eudicots when compared to that occurring in Osmanthus/Daphne and Ulmus/Celtis.

Impact of Microcystis aeruginosa on membrane fouling in a biologically treated effluent

2011 ◽  
Vol 63 (12) ◽  
pp. 2853-2859 ◽  
Author(s):  
Y. T. Goh ◽  
J. L. Harris ◽  
F. A. Roddick
Keyword(s):  
Microcystis Aeruginosa ◽  
Membrane Fouling ◽  
Early Phase ◽  
Cell Concentration ◽  
Membrane Surface ◽  
Late Phase ◽  
Protective Layer ◽  
Green Algal ◽  
Treated Effluent ◽  
Cake Layer

Microcystis aeruginosa was cultured in biologically treated municipal effluent to simulate blue-green algal bloom conditions in a treatment lagoon. The effect of algae in the early, mid and late phases of growth on membrane fouling, chemical coagulation (alum or aluminium chlorohydrate (ACH)) and hydraulic cleaning on the microfiltration of this effluent was investigated. The effect of M. aeruginosa in the early phase was negligible and gave a similar flux profile and permeate volume to that of effluent alone. The increase in M. aeruginosa concentration for the mid and late phases caused a significant reduction in permeate volume compared with the early phase. Full flux recovery was achieved with an alum dose of 1 mg Al3+ L−1 (early phase) and 10 mg Al3+ L−1 (mid phase), demonstrating that membrane fouling was hydraulically reversible. For the late phase, the highest flux recovery was 89%, which was achieved with an alum dose of 5 mg Al3+ L−1. Higher alum dosages resulted in a reduction in flux recovery. The use of 1.5 µm pre-filtration after alum treatment showed little improvement in water quality but led to a drastic reduction in flux recovery, which was attributed to diminishing the protective layer on the membrane surface, thus enabling internal fouling. The performance of ACH was comparable to alum at low dissolved organic carbon (DOC) and cell concentration, but was not as effective as alum at high DOC and cell concentration due to the formation of more compact ACH flocs, which resulted in a higher cake layer specific resistance, leading to the deterioration of performance.

On the Influence of Mechanical and Geometrical Property Distribution of the Safe Reeling of Rigid Pipelines

2009 ◽  
Author(s):  
Sylvain Denniel ◽  
Tomasz Tkaczyk ◽  
Brett Howard ◽  
Erik Levold ◽  
Olav Aamlid
Keyword(s):  
Yield Strength ◽  
Wall Thickness ◽  
Moment Capacity ◽  
Significant Difference ◽  
Optimizing Design ◽  
Bending Radius ◽  
Variation Parameter ◽  
Efficient Alternative ◽  
Pipe Joints ◽  
Cost Efficient

The reel-lay method is a fast and cost efficient alternative to the S-lay and J-lay installation methods for steel pipelines up to 20″ in diameter. The quality of the pipeline construction is high due to onshore welding under controlled conditions. However, reeled pipelines are subject to plastic straining (up to approx. 2.3%) during installation. It is therefore common practice to specify a minimum required wall thickness to avoid on-reel buckling. For a given pipe outside diameter and bending radius, formulae developed for pipes under pure bending are generally used. In addition, to ensure the integrity of pipelines during reeling, a minimum spooling-on tension is specified and tolerances on pipe properties, such as wall thickness and yield strength, are constrained. Tolerance limits are specified to reduce the likelihood of spooling two consecutive pipe joints, which have a significant difference in plastic moment capacity (mismatch). It has been shown previously that high levels of mismatch can trigger an on-reel buckle [1]. The reliability of the reeling process is indeed related to the uniformity of pipe properties. It can therefore be supposed that more uniform pipe properties may allow reeling of thinner-walled pipes, while achieving the same level of reliability. This issue has been investigated as part of a wider evaluation of reeling mechanics and the development of procedures for optimized assessment of the process, including such aspects as the effect of the geometry of pipelay equipment [2]. This paper explores methods that can be used to evaluate the reliability of reeling a given pipe onto a given vessel. Particular focus is given on the selection of appropriate material variation parameter for the assessment. The concept of an averaging factor is introduced as a means to relate variations in individual wall thickness and yield strength measurements to the variation in pipeline cross-section, which determines the likelihood of buckling. It is suggested that, in the future, this factor could be used as a method for optimizing design for reeling when using higher quality pipe.

Measurement of Liquid Water Content Inside the Gas Diffusion Layer

2012 ◽  
Author(s):  
Siddiq Hussain Tahseen ◽  
Kehan Chen ◽  
Mehdi Shahraeeni ◽  
Samuel C. M. Yew ◽  
Mina Hoorfar
Keyword(s):  
Water Content ◽  
Capillary Pressure ◽  
Diffusion Layer ◽  
Liquid Water ◽  
Gas Diffusion Layer ◽  
Liquid Water Content ◽  
Gas Diffusion ◽  
Water Volume ◽  
Significant Difference ◽  
The Impact

The amount of the liquid water present at the gas diffusion layer (GDL) has an impact on the diffusivity, capillary pressure and the permeability which in turn influences convective and diffusive transport. A prodigious amount of research has been conducted to study and measure the different properties (time of breakthrough and capillary pressure versus saturation) associated with the breakthrough condition. However, most of the reported data ignored the impact of expansion of different components in the set-up (such as tubing) and the condition after the time of breakthrough. The focus of this study is to measure the breakthrough pressure and time of breakthrough and hence determine the liquid water content inside the GDL before the time of breakthrough. The measurements are performed for different samples to study the effect of the thickness and hydrophobic contents. The results show that expansion has significant difference in the determination of water volume inside the GDL.

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