- Mechanics Reveals the Biological Trigger in Wrinkly Fingers. [Journal Article]
- ABAnn Biomed Eng 2016 Dec 02
- Fingertips wrinkle due to long exposure to water. The biological reason for this morphological change is unclear and still not fully understood. There are two main hypotheses for the underlying mecha...
Fingertips wrinkle due to long exposure to water. The biological reason for this morphological change is unclear and still not fully understood. There are two main hypotheses for the underlying mechanism of fingertip wrinkling: the 'shrink' model (in which the wrinkling is driven by the contraction of the lower layers of skin, associated with the shrinking of the underlying vasculature), and the 'swell' model (in which the wrinkling is driven by the swelling of the upper layers of the skin, associated with osmosis). In reality, contraction of the lower layers of the skin and swelling of the upper layers will happen simultaneously. However, the relative importance of these two mechanisms to drive fingertip wrinkling also remains unclear. Simulating the swelling in the upper layers of skin alone, which is associated with neurological disorders, we found that wrinkles appeared above an increase of volume of [Formula: see text] Therefore, the upper layers can not exceed this swelling level in order to not contradict in vivo observations in patients with such neurological disorders. Simulating the contraction of the lower layers of the skin alone, we found that the volume have to decrease a [Formula: see text] to observe wrinkles. Furthermore, we found that the combined effect of both mechanisms leads to pronounced wrinkles even at low levels of swelling and contraction when individually they do not. This latter results indicates that the collaborative effect of both hypothesis are needed to induce wrinkles in the fingertips. Our results demonstrate how models from continuum mechanics can be successfully applied to testing hypotheses for the mechanisms that underly fingertip wrinkling, and how these effects can be quantified.
- Electro-Kinetically Driven Peristaltic Transport Of Viscoelastic Physiological Fluids Through A Finite Length Capillary: Mathematical Modelling. [Journal Article]
- MBMath Biosci 2016 Nov 29
- Analytical solutions are developed for the electro-kinetic flow of a viscoelastic biological liquid in a finite length cylindrical capillary geometry under peristaltic waves. The Jefferys' non-Newton...
Analytical solutions are developed for the electro-kinetic flow of a viscoelastic biological liquid in a finite length cylindrical capillary geometry under peristaltic waves. The Jefferys' non-Newtonian constitutive model is employed to characterize rheological properties of the fluid. The unsteady conservation equations for mass and momentum with electro-kinetic and Darcian porous medium drag force terms are reduced to a system of steady linearized conservation equations in an axisymmetric coordinate system. The long wavelength, creeping (low Reynolds number) and Debye-Hückel linearization approximations are utilized. The resulting boundary value problem is shown to be controlled by a number of parameters including the electro-osmotic parameter, Helmholtz-Smoluchowski velocity (maximum electro-osmotic velocity), and Jefferys' first parameter (ratio of relaxation and retardation time), wave amplitude. The influence of these parameters and also time on axial velocity, pressure difference, maximum volumetric flow rate and streamline distributions (for elucidating trapping phenomena) is visualized graphically and interpreted in detail. Pressure difference magnitudes are enhanced consistently with both increasing electro-osmotic parameter and Helmholtz-Smoluchowski velocity, whereas they are only elevated with increasing Jefferys' first parameter for positive volumetric flow rates. Maximum time averaged flow rate is enhanced with increasing electro-osmotic parameter, Helmholtz-Smoluchowski velocity and Jefferys' first parameter. Axial flow is accelerated in the core (plug) region of the conduit with greater values of electro-osmotic parameter and Helmholtz-Smoluchowski velocity whereas it is significantly decelerated with increasing Jefferys' first parameter. The simulations find applications in electro-osmotic (EO) transport processes in capillary physiology and also bio-inspired EO pump devices in chemical and aerospace engineering.
- Novel Functional Whey-Based Drinks with Great Potential in the Dairy Industry. [Journal Article]
- FTFood Technol Biotechnol 2015; 53(3):307-314
- This work focuses on the production of liquid whey protein concentrates by ultrafiltration followed by thermal denaturation and homogenization of the ultrafiltrated concentrate, as well as on the pro...
This work focuses on the production of liquid whey protein concentrates by ultrafiltration followed by thermal denaturation and homogenization of the ultrafiltrated concentrate, as well as on the production of ultrafiltrated permeates concentrated by reverse osmosis. Kefir grains (fresh and thawed) and/or commercial probiotic bacteria were inoculated in both liquid whey protein concentrates and concentrated ultrafiltrated permeates and grown at 25 °C for 24 h for the manufacture of fermented drinks. The physicochemical characterization (pH, titratable acidity, viscosity, and content of total solids, ash, fat and proteins) of the obtained drinks was then assessed and compared. Enumeration of viable microorganisms was carried out immediately after inoculation (at 0 h), during the fermentation period (at 12 and 24 h) and during refrigerated storage (at 48, 168 and 336 h). The fermented drinks showed acceptable physicochemical and sensorial properties, and contained above 7 log CFU/mL of lactococci and lactobacilli and 6 log CFU/mL of yeasts after 14 days of refrigerated storage, which is in agreement with the standards required by international organizations like European Food Safety Authority (EFSA) and Food and Drug Administration (FDA) for products containing probiotics. In summary, the strategy developed in this work contributes to the expansion of the applications of products derived from whey fractionation for the design of novel functional foods.
- Teaching about Water Relations in Plant Cells: An Uneasy Struggle. [Journal Article]
- CLCBE Life Sci Educ 2016; 15(4)
- University students often struggle to understand the role of water in plant cells. In particular, osmosis and plasmolysis appear to be challenging topics. This study attempted to identify student dif...
University students often struggle to understand the role of water in plant cells. In particular, osmosis and plasmolysis appear to be challenging topics. This study attempted to identify student difficulties (including misconceptions) concerning osmosis and plasmolysis and examined to what extent the difficulties could be revised during a plant physiology course. A questionnaire was developed to monitor university students' conceptual knowledge before and after a course, and both qualitative and quantitative data were obtained. The data were analyzed using the constant comparison technique and descriptive statistics. Students were found to come to university with many misconceptions that had accumulated during their education. These misconceptions are extremely difficult to change during the traditional course, which comprises lectures and practical exercises. Students' misconceptions originate from commonly used sources such as textbooks, which are perceived as being reliable. Effective teaching of water relations in plant cells could include such didactic methods as "questioning the author," which allow teachers to monitor students' knowledge and help students acquire a more scientific understanding of key concepts.
- The Discovery of Electrokinetic Phenomena: Setting the Record Straight. [Review]
- ACAngew Chem Int Ed Engl 2016 Nov 30
- Electro-osmosis and electrophoresis were discovered by F. F. Reuss in Moscow in 1807. Or so the story goes. This essay critically examines the contributions of three scientists to the discovery of el...
Electro-osmosis and electrophoresis were discovered by F. F. Reuss in Moscow in 1807. Or so the story goes. This essay critically examines the contributions of three scientists to the discovery of electrokinetic phenomena. The evidence suggests that Reuss did indeed discover electro-osmosis, which takes its name (indirectly) from the work of Porrett. Contrary to current consensus, Gautherot made the earliest known observation of electrophoresis.
- Monitoring Process-Water Quality Using Near Infrared Spectroscopy and Partial Least Squares Regression with Prediction Uncertainty Estimation. [Journal Article]
- ASAppl Spectrosc 2016 Nov 29
- Reuse of process water in dairy ingredient production-and food processing in general-opens the possibility for sustainable water regimes. Membrane filtration processes are an attractive source of pro...
Reuse of process water in dairy ingredient production-and food processing in general-opens the possibility for sustainable water regimes. Membrane filtration processes are an attractive source of process-water recovery since the technology is already utilized in the dairy industry and its use is expected to grow considerably. At Arla Foods Ingredients (AFI), permeate from a reverse osmosis polisher filtration unit is sought to be reused as process water, replacing the intake of potable water. However, as for all dairy and food producers, the process-water quality must be monitored continuously to ensure food safety. In the present investigation we found urea to be the main organic compound, which potentially could represent a microbiological risk. Near infrared spectroscopy (NIRS) in combination with multivariate modeling has a long-standing reputation as a real-time measurement technology in quality assurance. Urea was quantified Using NIRS and partial least squares regression (PLS) in the concentration range 50-200 ppm (RMSEP = 12 ppm, R(2 )= 0.88) in laboratory settings with potential for on-line application. A drawback of using NIRS together with PLS is that uncertainty estimates are seldom reported but essential to establishing real-time risk assessment. In a multivariate regression setting, sample-specific prediction errors are needed, which complicates the uncertainty estimation. We give a straightforward strategy for implementing an already developed, but seldom used, method for estimating sample-specific prediction uncertainty. We also suggest an improvement. Comparing independent reference analyses with the sample-specific prediction error estimates showed that the method worked on industrial samples when the model was appropriate and unbiased, and was simple to implement.
- A new route of bioaugmentation by allochthonous and autochthonous through biofilm bacteria for SCOD removal of old leachate. [Journal Article]
- ETEnviron Technol 2016 Nov 28; :1-24
- Landfill leachate contains environmental pollutants that are generally resistant to biodegradation. In this study, indigenous and exogenous bacteria in leachate were acclimated in both biofilm and su...
Landfill leachate contains environmental pollutants that are generally resistant to biodegradation. In this study, indigenous and exogenous bacteria in leachate were acclimated in both biofilm and suspension forms to increase the removal of SCOD (soluble chemical oxygen demand). The bacteria from the leachate and sewage were acclimated to gradually increasing leachate concentration prepared using a reverse osmosis membrane over 28 days. The SCOD removal was measured aerobically or nominally anaerobically. Biofilms were prepared using different carrier media (glass, rubber, and plastic). The maximum SCOD removal in suspensions was 32% (anaerobic) and in biofilms was 39% (aerobic). In suspension form, SCOD removal using acclimated bacteria from leachate and sewage anaerobically increased in comparison with the control (P<0.05). In biofilm form, the aerobic condition and the use of acclimated bacteria from leachate and sewage increased removal efficiency of SCOD in comparison with other biofilm groups (P<0.05). Three species of bacteria including Bacillus cereus, Bacillus subtilis, and Pseudomonas aeruginosa were identified in the biofilm from leachate and sewage. Bioaugmentation technology using biofilms and acclimations can be an effective, inexpensive, and simple way to decrease SCOD in old landfill leachate.
- Evaluation of fertilizer-drawn forward osmosis for sustainable agriculture and water reuse in arid regions. [Journal Article]
- JEJ Environ Manage 2016 Nov 24; 187:137-145
- The present study focused on the performance of the FDFO process to achieve simultaneous water reuse from wastewater and production of nutrient solution for hydroponic application. Bio-methane potent...
The present study focused on the performance of the FDFO process to achieve simultaneous water reuse from wastewater and production of nutrient solution for hydroponic application. Bio-methane potential (BMP) measurements were firstly carried out to determine the effect of osmotic concentration of wastewater achieved in the FDFO process on the anaerobic activity. Results showed that 95% water recovery from the FDFO process is the optimum value for further AnMBR treatment. Nine different fertilizers were then tested based on their FO performance (i.e. water flux, water recovery and reverse salt flux) and final nutrient concentration. From this initial screening, ammonium phosphate monobasic (MAP), ammonium sulfate (SOA) and mono-potassium phosphate were selected for long term experiments to investigate the maximum water recovery achievable. After the experiments, hydraulic membrane cleaning was performed to assess the water flux recovery. SOA showed the highest water recovery rate, up to 76% while KH2PO4 showed the highest water flux recovery, up to 75% and finally MAP showed the lowest final nutrient concentration. However, substantial dilution was still necessary to comply with the standards for fertigation even if the recovery rate was increased.
- Study of the effect of the bacterial and fungal communities present in real wastewater effluents on the performance of fungal treatments. [Journal Article]
- STSci Total Environ 2016 Nov 23
- The use of the ligninolytic fungi Trametes versicolor for the degradation of micropollutants has been widely studied. However, few studies have addressed the treatment of real wastewater containing p...
The use of the ligninolytic fungi Trametes versicolor for the degradation of micropollutants has been widely studied. However, few studies have addressed the treatment of real wastewater containing pharmaceutically active compounds (PhAC) under non-sterile conditions. The main drawback of performing such treatments is the difficulty for the inoculated fungus to successfully compete with the other microorganisms growing in the bioreactor. In the present study, several fungal treatments were performed under non-sterile conditions in continuous operational mode with two types of real wastewater effluent, namely, a reverse osmosis concentrate (ROC) from a wastewater treatment plant and a veterinary hospital wastewater (VHW). In all cases, the setup consisted of two parallel reactors: one inoculated with T. versicolor and one non-inoculated, which was used as the control. The main objective of this work was to correlate the operational conditions and traditional monitoring parameters, such as laccase activity, with PhAC removal and the composition of the microbial communities developed inside the bioreactors. For that purpose a variety of biochemical and molecular biology analyses were performed: phospholipid fatty acids analysis (PLFA), quantitative PCR (qPCR) and denaturing gradient gel electrophoresis (DGGE) followed by sequencing. The results show that many indigenous fungi (and not only bacteria, which were the focus of the majority of previously published research) can successfully compete with the inoculated fungi (i.e., Trichoderma asperellum overtook T. versicolor in the ROC treatment). We also showed that the wastewater origin and the operational conditions had a stronger impact on the diversity of microbial communities developed in the bioreactors than the inoculation or not with T. versicolor.
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- Osmotic versus conventional membrane bioreactors integrated with reverse osmosis for water reuse: Biological stability, membrane fouling, and contaminant removal. [Journal Article]
- WRWater Res 2016 Nov 12; 109:122-134
- This study systematically compares the performance of osmotic membrane bioreactor - reverse osmosis (OMBR-RO) and conventional membrane bioreactor - reverse osmosis (MBR-RO) for advanced wastewater t...
This study systematically compares the performance of osmotic membrane bioreactor - reverse osmosis (OMBR-RO) and conventional membrane bioreactor - reverse osmosis (MBR-RO) for advanced wastewater treatment and water reuse. Both systems achieved effective removal of bulk organic matter and nutrients, and almost complete removal of all 31 trace organic contaminants investigated. They both could produce high quality water suitable for recycling applications. During OMBR-RO operation, salinity build-up in the bioreactor reduced the water flux and negatively impacted the system biological treatment by altering biomass characteristics and microbial community structure. In addition, the elevated salinity also increased soluble microbial products and extracellular polymeric substances in the mixed liquor, which induced fouling of the forward osmosis (FO) membrane. Nevertheless, microbial analysis indicated that salinity stress resulted in the development of halotolerant bacteria, consequently sustaining biodegradation in the OMBR system. By contrast, biological performance was relatively stable throughout conventional MBR-RO operation. Compared to conventional MBR-RO, the FO process effectively prevented foulants from permeating into the draw solution, thereby significantly reducing fouling of the downstream RO membrane in OMBR-RO operation. Accumulation of organic matter, including humic- and protein-like substances, as well as inorganic salts in the MBR effluent resulted in severe RO membrane fouling in conventional MBR-RO operation.