1,320 research outputs found

    Role of amylase, mucin, IgA and albumin on salivary protein buffering capacity: A pilot study

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    It has been suggested that proteins serve as major salivary buffers below pH 5. It remains unclear, however, which salivary proteins are responsible for these buffering properties. The aim of this pilot study was to evaluate the correlation between salivary concentration of total protein, amylase, mucin, immunoglobulin A (IgA), albumin and total salivary protein buffering capacity at a pH range of 4-5. In addition, the buffering capacity and the number of carboxylic acid moieties of single proteins were assessed. Stimulated saliva samples were collected at 9:00, 13:00 and 17:00 from 4 healthy volunteers on 3 successive days. The buffering capacities were measured for total salivary protein or for specific proteins. Also, the concentration of total protein, amylase, mucin, IgA and albumin were analysed. Within the limits of the current study, it was found that salivary protein buffering capacity was highly positively correlated with total protein, amylase and IgA concentrations. A weak correlation was observed for both albumin and mucin individually. Furthermore, the results suggest that amylase contributed to 35% of the salivary protein buffering capacity in the pH range of 4-

    A Numerical Solution Algorithm for a Heat and Mass Transfer Model of a Desalination System Based on Packed-Bed Humidification and Bubble Column Dehumidification

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    The humidification-dehumidification (HDH) desalination system can be advantageous in small-scale, off-grid applications. The main drawback of this technology has been its low energy efficiency, which results in high water production costs. Previous studies have approached this issue through thermodynamic balancing of the system; however, most theoretical work on the balancing of HDH has followed a fixed-effectiveness approach that does not explicitly consider transport processes in the components. Fixing the effectiveness of the heat and mass exchangers allows them to be modeled without explicitly sizing the components and gives insight on how the cycle design can be improved. However, linking the findings of fixed-effectiveness models to actual systems can be challenging, as the performance of the components depends mainly on the available surface areas and the flow rates of the air and water streams. In this study, we present a robust numerical solution algorithm for a heat and mass tranfer model of a complete humidification-dehumidification system consisting of a packed-bed humidifier and a multi-tray bubble column dehumidifier. We look at the effect of varying the water-to-air mass flow rate ratio on the energy efficiency of the system, and we compare the results to those reached following a fixed-effectiveness approach. In addition, we study the effect of the top and bottom temperatures on the performance of the system. We recommended the implementation a control system that varies the mass flow rate ratio in order to keep the system balanced in off-design conditions, especially with varying top temperature.Center for Clean Water and Clean Energy at MIT and KFUPM (Project R4-CW-08

    Brominated Flame Retardants in Fish of Lake Geneva (Switzerland)

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    Polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD) were determined in fish (Salmo trutta forma lacustris) from Lake Geneva. Brominated flame retardants were detected in all nine samples with an average concentration for the sum of BDE-28, BDE-47, BDE-49, BDE-66, BDE-99, BDE-100, BDE-119, BDE-153, BDE-154 and BDE-209 of 207ng per g lipid weight (ngglw−1). The congener patterns were dominated by BDE-47. The average concentration of HBCD was 168ngglw−

    Comparison of three strip-type tests and two laboratory methods for salivary buffering analysis

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    This study evaluated the correlation between three strip-type, colorimetric tests and two laboratory methods with respect to the analysis of salivary buffering. The strip-type tests were saliva-check buffer, Dentobuff strip and CRT® Buffer test. The laboratory methods included Ericsson's laboratory method and a monotone acid/base titration to create a reference scale for the salivary titratable acidity. Additionally, defined buffer solutions were prepared and tested to simulate the carbonate, phosphate and protein buffer systems of saliva. The correlation between the methods was analysed by the Spearman's rank test. Disagreement was detected between buffering capacity values obtained with three strip-type tests that was more pronounced in case of saliva samples with medium and low buffering capacities. All strip-type tests were able to assign the hydrogencarbonate, di-hydrogenphosphate and 0.1% protein buffer solutions to the correct buffer categories. However, at 0.6% total protein concentrations, none of the test systems worked accurately. Improvements are necessary for strip-type tests because of certain disagreement with the Ericsson's laboratory method and dependence on the protein content of saliv

    Clinical Study Monitoring the pH on Tooth Surfaces in Patients with and without Erosion

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    The aim of this study was to compare tooth surface pH after drinking orange juice or water in 39 patients with dental erosion and in 17 controls. The following investigations were carried out: measurement of pH values on selected tooth surfaces after ingestion of orange juice followed by ingestion of water (acid clearance), measurement of salivary flow rate and buffering capacity. Compared with the controls, patients with erosion showed significantly greater decreases in pH after drinking orange juice, and the pH stayed lower for a longer period of time (p < 0.05). Saliva parameters showed no significant differences between the two patient groups except for a lower buffering capacity at pH 5.5 in the erosion group

    The application of predictive modelling for determining bio-environmental factors affecting the distribution of blackflies (Diptera: Simuliidae) in the Gilgel Gibe watershed in Southwest Ethiopia

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    Blackflies are important macroinvertebrate groups from a public health as well as ecological point of view. Determining the biological and environmental factors favouring or inhibiting the existence of blackflies could facilitate biomonitoring of rivers as well as control of disease vectors. The combined use of different predictive modelling techniques is known to improve identification of presence/absence and abundance of taxa in a given habitat. This approach enables better identification of the suitable habitat conditions or environmental constraints of a given taxon. Simuliidae larvae are important biological indicators as they are abundant in tropical aquatic ecosystems. Some of the blackfly groups are also important disease vectors in poor tropical countries. Our investigations aim to establish a combination of models able to identify the environmental factors and macroinvertebrate organisms that are favourable or inhibiting blackfly larvae existence in aquatic ecosystems. The models developed using macroinvertebrate predictors showed better performance than those based on environmental predictors. The identified environmental and macroinvertebrate parameters can be used to determine the distribution of blackflies, which in turn can help control river blindness in endemic tropical places. Through a combination of modelling techniques, a reliable method has been developed that explains environmental and biological relationships with the target organism, and, thus, can serve as a decision support tool for ecological management strategies

    A method for predicting baking performance through evaluation of short crust dough

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    The three major components of short-crust cookie dough are flour, sugar, and fat. Since high fat contents have been shown to have a major effect on the development of the gluten network, studying how these ingredients could affect the texture of the dough and the baked product became interesting. In addition, there are no existing methods on short crust cookie dough that allow predicting the characteristics of the baked product based on those of the dough. Therefore, the task was to study whether developing such a method is possible or not. In this paper, the amount of ingredients was varied and textural analyses were run on dough and baked samples. The results were analyzed using chemometrics and statistical tools and different graphs were plotted to visualize the relations between the variables and parameters. The analyses showed that the fat and egg amounts have a significant effect on the texture of the dough in terms of hardness and gumminess. In addition, the hardness of the baked product was shown to be positively correlated with dough hardness and gumminess, which in turn can be controlled by the addition of fat and/or eggs according to requirements on the final product. Thus, prediction of baking performance based on dough characteristics was shown to be possible.The three major components of short-crust cookie dough are flour, sugar, and fat. Since high fat contents have been shown to have a major effect on the development of the gluten network, studying how these ingredients could affect the texture of the dough and the baked product became interesting

    Optimizing energy market participation with batteries

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    Due to the fact that the energy sector is in transition, there are goals for lowering the energy cost with the use of renewables and batteries. This presents challenges to the system and the solution is the issuing of energy communities that can be used to make electricity provision more clean and secure. It is also to see how energy flexibility elements or elements on the consumption side can make the system more efficient and cheaper, which is being done in this paper concerning the day-ahead bid and batteries. Traditional day-ahead bidding methods have become costly, mainly when the forecasted energy consumption differs from the actual consumption, which has to be resolved by penalizing with an imbalance cost. This thesis is part of a more significant project (Layered Energy System) that is to be deployed in Spain. Applying such changes to the electricity system first requires becoming familiar with and understanding Spain's context. The first part of this thesis provides research to understand the Spanish regulatory framework, how the market works, and the status of these technologies in Spain. Following that, this thesis's primary work is to explore how day-ahead market bid could be improved through the use of batteries for better planning and error assumptions. It mentions several day-ahead bidding strategies in the context of energy and batteries. And then selects a subset (three) of the studied strategies and implements them, comparing their performance on actual electricity data. Finally, selects the one that best fits various scenarios and requirements. A particular objective function is opted to be minimized with respect to the battery constraints that involve the variables. A linear program will find the values that best fits those variables at every time step tt of a single day. The methodology is an improvement over traditional predictive models. After comparing different strategies, Results show that strategy one, namely "Stochastic Chance-constraint optimization", yields the best results. In this strategy, the battery would have the freedom to maximize profit even if it sometimes increases imbalance. The preferred error distribution for this strategy is the Gamma distribution. Using a battery to offset imbalances can help to minimize total energy cost for a whole day (up to 26%). The last part of the thesis is ongoing research about capacity traders and market performance. It surveys the literature on trading strategies in various contexts and markets relevant to capacity traders. The market performance in capacity trading needs to consider how well the buildings can reach their desired capacity through bidding and selling. Performance metrics that are typically used to evaluate those trading strategies were documented. This feature is being worked on with python, but it will not be able to be shown
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