Integral approach and numerical improvement to calculate the carbon concentration profiles in carburising process

In the present work, the carbon diffusion in steel, where the carbon diffusivity varies with the carbon content, was solved with the integral methods under the third boundary condition. The variation of carbon diffusivity in steel with the carbon content was described with two different functions ie. linear dependence and exponential dependence. The integral approximation for both cases was improved with the numerical computation to more accurately predict the carbon profiles. The integral solution is more accurate than the formulation based on the assumption of a constant diffusivity or those based on the assumption of a constant diffusivity and/or constant carbon content at part surface. It is also more easily used in practice than the numerical method to describe the carburising process and predict the carbon content at steel surface and carbon profiles in treated layer.

Integral approach and numerical improvement to calculate carbon concentration profiles in carburising

The carbon diffusion in steel, where the carbon diffusivity varies with the carbon content, was solved with the integral methods under the third boundary condition. The variation of carbon diffusivity in steel with the carbon content was described with two different functions, linear dependence and exponential dependence. The integral approximation for both cases was improved with the numerical computation to more accurately predict the carbon profiles. The integral solution is more accurate than the formulation based on the assumption of a constant diffusivity or those based on the assumption of a constant diffusivity and/or constant carbon content at part surface. It is also more easily used in practice than the numerical method to describe the carburising process and predict the carbon content at steel surface and carbon profiles in treated layer.

Concentration monitoring and performance of a migratory corrosion inhibitor in steel-reinforced concrete

Inhibitor concentration depth profiles for concrete samples treated with a proprietary migratory corrosion inhibitor (of the Cortec MCI range) are presented. The treated concrete was cored and these cores were then sectioned and crushed before being immersed in distilled water to extract the available inhibitor. The amine concentrations were quantified using an ammonium-sensing electrode and were then related to the inhibitor concentration present. The inhibitor examined, reported to contain a combination of volatile amines and amino carboxylate compounds, was found to readily diffuse through concrete. The inhibitor was subjected to a 5-year trial and found to be effective in suppressing corrosion of steel reinforcement in the presence of high chloride concentrations. The concentration profiles indicate that only relatively low concentrations of inhibitor were required to achieve inhibition in this case.

Consistent model predictions for isothermal cure kinetics investigation of high performance epoxy prepregs

An accurate kinetics model is essential for understanding the curing mechanism and predicting the end properties of polymer materials. Graphite/epoxy AS4/ 8552 prepreg is a recent high-performance thermosetting composite modified with thermoplastic, which is being used in the manufacture of aircraft and military structures. The isothermal cures of this system along with another thermoplastic toughened high-performance prepreg, the T800H/3900-2 system, were investigated by real-time Fourier transform infrared (FTIR) spectroscopy. The cure rate was quantitatively analyzed based on the concentration profiles of both the epoxy and primary amine groups. Three autocatalytic models were used to determine kinetics parameters for both composite systems. The model which utilizes an empirical term, the final relative conversion (at different isothermal curing temperatures), describes the experimental data of both systems more satisfactorily than the model which applies a diffusion factor. The modeling results suggest that the curing of epoxy within both prepregs can be assumed to be a second order process.

Critical assessment of various techniques for the extraction of carotenoids and co-enzyme Q10 from the Thraustochytrid strain ONC-T18

A variety of techniques for extracting carotenoids from the marine Thraustochytrium sp. ONC-T18 was compared. Specifically, the organic solvents acetone, ethyl acetate, and petroleum ether were tested, along with direct and indirect ultrasonic assisted extraction (probe vs bath) methods. Techniques that used petroleum ether/acetone/water (15:75:10, v/v/v) with 3 h of agitation, or 5 min in an ultrasonic bath, produced the highest extraction yields of total carotenoids (29−30.5 μg g^-1). Concentrations up to 11.5 μg g^-1 of canthaxanthin and 17.5 μg g^-1 of β-carotene were detected in extracts stored for 6 weeks. Astaxanthin and echinenone were also detected as minor compounds. Extracts with and without antioxidants showed similar carotenoid concentration profiles. However, total carotenoid concentrations were approximately 8% higher when antioxidants were used. Finally, an easy-to-perform and inexpensive method to detect co-enzymes in ONC-T18 was also developed using silica gel TLC plates. Five percent methanol in toluene as a mobile phase consistently eluted co-enzyme Q10 standards and could separate the co-enzyme fractions present in ONC-T18.

In-situ confocal Raman monitoring of evaporation process during protein crystallization

We have introduced an in-situ Raman monitoring technique to investigate the crystallization process inside protein drops. In addition to a conventional vapour-diffusion process, a novel procedure which actively stimulates the evaporation from a protein drop during crystallization was also evaluated, with lysozyme as a model protein. In contrast to the conventional vapour-diffusion condition, the evaporation-stimulated growth of crystals was initiated in a simple dehydration scheme and completed within a significantly shorter time. To gain an understanding of crystallization behaviours under the conditions with and without such evaporation stimulation, confocal Raman spectroscopy combined with linear regression analysis was used to monitor both lysozyme and HEPES buffer concentrations in real time. The confocal measurements having a high spatial resolution and good linear response revealed areas of local inhomogeneity in protein concentration when the crystallization started. The acquired concentration profiles indicated that (1)ÿthe evaporation-stimulated crystallization proceeded with protein concentrations lower than those under conventional vapour diffusion, and (2)ÿcrystals under the evaporation-stimulated condition were noticeable within an early stage of crystallization before the protein concentration approached its maximum value. The HEPES concentration profiles, on the other hand, increased steadily towards the end of the process regardless of the conditions used for crystallization. In particular, the observed local inhomogeneities specific to protein distribution suggested an accumulation mechanism of protein molecules that initiates the nucleation of crystals.

Molecular mechanism of stabilization of thin films for improved water evaporation protection

All-atom molecular dynamics simulations and experimental characterization have been used to examine the structure and dynamics of novel evaporation-suppressing films where the addition of a water-soluble polymer to an ethylene glycol monooctadecyl ether monolayer leads to improved water evaporation resistance. Simulations and Langmuir trough experiments demonstrate the surface activity of poly(vinyl pyrrolidone) (PVP). Subsequent MD simulations performed on the thin films supported by the PVP sublayer show that, at low surface pressures, the polymer tends to concentrate at the film/water interface. The simulated atomic concentration profiles, hydrogen bonding patterns, and mobility analyses of the water-polymer-monolayer interfaces reveal that the presence of PVP increases the atomic density near the monolayer film, improves the film stability, and reduces the mobility of interfacial waters. These observations explain the molecular basis of the improved efficacy of these monolayer/polymer systems for evaporation protection of water and can be used to guide future development of organic thin films for other applications.

Use of in vitro critical inhibitory concentration, a novel approach to predict in vivo synergistic bactericidal effect of combined amikacin and piperacillin against pseudomonas aeruginosa in a systemic rat infection model

PURPOSE: This study was undertaken to explore the use of in vitro critical inhibitory concentration (CIC) as a surrogate marker relating the pharmacokinetic (PK) parameters to in vivo bactericidal synergistic effect [pharmacodynamic (PD)] of amikacin + piperacillin combination against Pseudomonas aeruginosa in a systemic rat infection model. METHODS: The in vitro antibacterial activities of amikacin and piperacillin, alone and in combinations at various ratios of the concentrations, were tested against a standard [5 x 10(5) colony-forming units (CFU)/ml] and a large (1.5 x 10(8) CFU/ml) inoculum of P. aeruginosa ATCC 9027 using a modified survival-time method. The CIC of each individual antibiotic for the different combinations was determined using a cup-plate method. In vivo studies were performed on Sprague-Dawley rats using a systemic model of infection with P. aeruginosa ATCC 9027. PK profiles and in vivo killing effects of the combination at different dosing ratios were studied. RESULTS: An inoculum effect was observed with the antibiotics studied. Synergy was seen against both the inocula at the following concentration ratios: 70% C(ami) + 30% C(pip) and 75% C(ami) + 25% C(pip), where C(ami) and C(pip) are the concentrations of amikacin and piperacillin to produce a 1000-fold decrease in bacterial population over 5 h, respectively. The CIC values determined corroborated with the order of in vitro bacterial killing observed for the antibiotic combinations. The dosing ratio of 12.6 mg/kg amikacin + 36 mg/kg piperacillin (a 70:30 ratio of the individual doses) exhibited the greatest killing in vivo when compared to the other ratios. The PK-PD relationships were described by simple, linear regression equations using the area under the in vivo killing curve as a PD marker and the AUCIC(ami)/CIC(ami) + AUCIC(pip)/CIC(pip), AUC(ami)/CIC(ami) + AUC(pip)/CIC(pip), C(max,ami)/CIC(ami) + C(max,pip)/CIC(pip), and AUCIC(ami)/MIC(ami) + AUCIC(pip)/MIC(pip) as PK markers for the amikacin + piperacillin combination. CONCLUSION: The combination of amikacin and piperacillin exhibited synergistic killing effect on P. aeruginosa that could be modeled using CIC as a surrogate marker relating the PK parameters to in vivo bactericidal effect.

Nursing educations and graduates : profiles for 2001 and projections for 2002

The present study was commissioned for the National Review of Nursing Education. This is the second of two national studies commissioned to map in detail nursing education programs and to profile and make future projections regarding graduates from undergraduate and postgraduate nursing education courses in Australia.

The first study was undertaken in 2001 by Deakin University School of Nursing under the auspices of the 2001 Evaluation Investigations Project titled "Nursing Education and Graduates: Profiles for 1999, and 2000 with projections for 2001". This project sought data on nursing education within Australia in order to improve the accuracy of nursing education databases and to strengthen the ability of DETYA to provide advice on workforce planning. Issues that arose from that project included differences in data sets for undergraduate nursing courses in Australia and the complex process of attempting to tease out and accurately quantify postgraduate specialty courses when a trend towards postgraduate generic courses was evident. Approximately 26% of postgraduate domestic student enrolment data were reported utilising a generic nursing course category.

The purpose of this study was, therefore, twofold. Firstly, this study validated and extended the existing database developed in the previous study mapping in detail the full range of undergraduate programs offered by tertiary education providers across Australia that lead to an initial qualification and entry into nursing practice.

New data about the following was sought:

* Undergraduate nursing degrees (both three-year and four-year courses);
* Double/combined nursing degrees;
* Courses offered by private universities;
* Four-year bachelor degrees that concurrently provide both initial nurse registration and preparation for specialty nursing practice;
* Courses that facilitate ‘fast-tracking’ of students for initial nurse registration with previous tertiary or nursing studies,
* Hours and configuration of clinical experience in undergraduate nursing courses.

A primary numeracy : a mapping review and analysis of Australian research in numeracy learning at the primary school level : report

The outcome from this project produces a database of over 185 projects and 726 publications relating to numeracy research to systematically ‘mapped’ Australian research on primary school numeracy over the last decade. The database incorporates research summaries and findings that are easily accessible to teachers and teacher educators, and act as a valuable tool for determining further research directions. The project report examines the available research and organises the discussion of the research findings under a set of themes and sub-themes.

Some summarised examples from the report reveals that:

* Effective teachers of numeracy:
- have high expectations of their students;
- focus on children’s mathematical learning, rather than on providing pleasant classroom experiences;
- provide a challenging curriculum;
- use higher-order questioning;
- make connections both within mathematics and between mathematics in different contexts; and
- use highly interactive teaching involvement with students in class discussion.

* Effective professional development programmes:
- provide teachers with the time and appropriate resources to enable them to reflect on their teaching;
- provide continuing support and encouragement while teachers explore possibilities and trial new strategies in their classrooms;
- involve teachers in school-based and wider networks;
- are of sufficient duration to allow significant changes to habitual beliefs and practices; and
- create opportunities for the exploration of theory-practice relationships.

Effect of the glycemic index of carbohydrates on day-long (10 h) profiles of plasma glucose, insulin, cholecystokinin and ghrelin

Background: Low glycemic index (GI) carbohydrates have been linked to increased satiety. The drive to eat may be mediated by postprandial changes in glucose, insulin and gut peptides.
Objective: To investigate the effect of a low and a high GI diet on day-long (10 h) blood concentrations of glucose, insulin, cholecystokinin (CCK) and ghrelin (GHR).
Design: Subjects (n¼12) consumed a high and a low GI diet in a randomized, crossover design, consisting of four meals that were matched for macronutrients and fibre, and differed only in carbohydrate quality (GI). Blood was sampled every 30–60 min and assayed for glucose, insulin, CCK and GHR.
Results: The high GI diet resulted in significantly higher glucose and insulin mean incremental areas under the curve (IAUC, P¼0.027 and P¼0.001 respectively). CCK concentration was 59% higher during the first 7 h of the low GI diet (394±95 pmol/l min) vs the high GI diet (163±38 pmol/l min, P¼0.046), but there was no difference over 10 h (P¼0.224). GHR concentration was inversely correlated with insulin concentration (Pearson correlation 0.48, P¼0.007), but did not differ significantly between the low and high GI diets.
Conclusions: Mixed meals of lower GI are associated with lower day-long concentrations of glucose and insulin, and higher CCK after breakfast, morning tea and lunch. This metabolic profile could mediate differences in satiety and hunger seen in some, but not all, studies.

Prediction of chlorine and THMs concentration profile in bulk drinking water distribution systems from laboratory data

Nearly all drinking water distribution systems experience a "natural" reduction of disinfection residuals. The most frequently used disinfectant is chlorine, which can decay due to reactions with organic and inorganic compounds in the water and by liquid/solids reaction with the biofilm, pipe walls and sediments. Usually levels of 0.2-0.5 mg/L of free chlorine are required at the point of consumption to maintain bacteriological safety. Higher concentrations are not desirable as they present the problems of taste and odour and increase formation of disinfection by-products. It is usually a considerable concern for the operators of drinking water distribution systems to manage chlorine residuals at the "optimum level", considering all these issues. This paper describes how the chlorine profile in a drinking water distribution system can be modelled and optimised on the basis of readily and inexpensively available laboratory data. Methods are presented for deriving the laboratory data, fitting a chlorine decay model of bulk water to the data and applying the model, in conjunction with a simplified hydraulic model, to obtain the chlorine profile in a distribution system at steady flow conditions. Two case studies are used to demonstrate the utility of the technique. Melbourne's Greenvale-Sydenham distribution system is unfiltered and uses chlorination as its only treatment. The chlorine model developed from laboratory data was applied to the whole system and the chlorine profile was shown to be accurately simulated. Biofilm was not found to critically affect chlorine decay. In the other case study, Sydney Water's Nepean system was modelled from limited hydraulic data. Chlorine decay and trihalomethane (THM) formation in raw and treated water were measured in a laboratory, and a chlorine decay and THM model was derived on the basis of these data. Simulated chlorine and THM profiles agree well with the measured values available. Various applications of this modelling approach are also briefly discussed.

Prediction of chlorine and trihalomethanes concentration profile in bulk drinking water distribution systems from laboratory data

Nearly all drinking water distribution systems experience a "natural" reduction of disinfection residuals. The most frequently used disinfectant is chlorine, which can decay due to reactions with organic and inorganic compounds in the water and by liquid/solids reaction with the biofilm, pipe walls and sediments. Usually levels of 0.2-0.5 mg/L of free chlorine are required at the point of consumption to maintain bacteriological safety. Higher concentrations are not desirable as they present the problems of taste and odour and increase formation of disinfection by-products. It is usually a considerable concern for the operators of drinking water distribution systems to manage chlorine residuals at the "optimum level", considering all these issues. This paper describes how the chlorine profile in a drinking water distribution system can be modelled and optimised on the basis of readily and inexpensively available laboratory data. Methods are presented for deriving the laboratory data, fitting a chlorine decay model of bulk water to the data and applying the model, in conjunction with a simplified hydraulic model, to obtain the chlorine profile in a distribution system at steady flow conditions. Two case studies are used to demonstrate the utility of the technique. Melbourne's Greenvale-Sydenham distribution system is unfiltered and uses chlorination as its only treatment. The chlorine model developed from laboratory data was applied to the whole system and the chlorine profile was shown to be accurately simulated. Biofilm was not found to critically affect chlorine decay. In the other case study, Sydney Water's Nepean system was modelled from limited hydraulic data. Chlorine decay and trihalomethane (THM) formation in raw and treated water were measured in a laboratory, and a chlorine decay and THM model was derived on the basis of these data. Simulated chlorine and THM profiles agree well with the measured values available. Various applications of this modelling approach are also briefly discussed.

Understanding the effectiveness of cathodic protection under disbonded coatings

© 2015 Elsevier Ltd. All rights reserved. Factors affecting the effectiveness of cathodic protection under disbonded coatings were studied using a partially covered two dimensional electrode array that simulates a crevice under a disbonded coating and allows for the mapping of electrochemical currents under the influence of cathodic protection (CP). This technique enabled the study of the effects of major factors, including crevice gap size, solution conductivity and applied CP potential on the distribution and evolution of CP currents over the electrode array surface. The effect of each of these factors on the overall current distribution profile has been explained using a new electrochemical model. This model suggests that, despite the detrimental effect of cathodic shielding, the steel under disbonded areas could still be protected, independent of the crevice geometry and solution resistivity, by means of concentration polarization instead of direct electrochemical polarization. A set of conditions for maintaining CP potentials more negative than -850 mVCSE along disbonded coating areas was deduced from the proposed model and validated against potential profiles available in the literature. The possible practical implications of the current mapping technique used in this study for developing in-situ CP monitoring sensors has also been discussed.

The burden of neck pain: its meaning for persons with neck pain and healthcare providers, explored by concept mapping

PURPOSE: To empirically define the concept of burden of neck pain. The lack of a clear understanding of this construct from the perspective of persons with neck pain and care providers hampers adequate measurement of this burden. An additional aim was to compare the conceptual model obtained with the frequently used Neck Disability Index (NDI). METHODS: Concept mapping, combining qualitative (nominal group technique and group consensus) and quantitative research methods (cluster analysis and multidimensional scaling), was applied to groups of persons with neck pain (n = 3) and professionals treating persons with neck pain (n = 2). Group members generated statements, which were organized into concept maps. Group members achieved consensus about the number and description of domains and the researchers then generated an overall mind map covering the full breadth of the burden of neck pain. RESULTS: Concept mapping revealed 12 domains of burden of neck pain: impaired mobility neck, neck pain, fatigue/concentration, physical complaints, psychological aspects/consequences, activities of daily living, social participation, financial consequences, difficult to treat/difficult to diagnose, difference of opinion with care providers, incomprehension by social environment, and how person with neck pain deal with complaints. All ten items of the NDI could be linked to the mind map, but the NDI measures only part of the burden of neck pain. CONCLUSION: This study revealed the relevant domains for the burden of neck pain from the viewpoints of persons with neck pain and their care providers. These results can guide the identification of existing measurements instruments for each domain or the development of new ones to measure the burden of neck pain.