Structural Changes Of Dha-Containing Phospholipids By K+ And Na+ Cations In Nerve Cell Membranes

Understanding the structure and dynamics of a docosa hexaenoic acid (DHA) containing phospholipid monomer within membranes is essential for recognizing the bilayer function in central nervous system. It has been recognized that the electrical impulses in nerve cells arise from the movement of electrical charges in the form of ions across the plasma membrane. In this study, we have modeled a novel DHA-containing phosphatidylcholine (PC) found in a marine single cell eukaryote, >Schizochytrium sp F26-b> and we were focused on understanding the physico-chemical nature of K+ and Na+ movement toward DHA-containing phospholipid through its structural changes. To know more about the temperature dependence of the structural stability of 1-pentadecanoyl-2-docosahexaenoyl-sn-glycerol-3-phosphocholin frequently calculations have been carried out at different biological temperatures and the plotted graphs of energy values at all employed temperatures have been analyzed. Our findings confirmed the usefulness of Quantum chemical calculations for determination of dynamics of a phospholipid and prediction of their biological activity in bio-membranes.Chemistr

Effect of interfacial thermal resistance and nanolayer on estimates of effective thermal conductivity of nanofluids

Colloidal suspensions of nanoparticles (nanofluids) are materials of interest for thermal engineering, because their heat transfer properties are typically enhanced as compared to the base fluid one. Effective medium theory provides popular models for estimating the overall thermal conductivity of nanofluids based on their composition. In this article, the accuracy of models based on the Bruggeman approximation is assessed. The sensitivity of these models to nanoscale interfacial phenomena, such as interfacial thermal resistance (Kapitza resistance) and fluid ordering around nanoparticles (nanolayer), is considered for a case study consisting of alumina nanoparticles suspended in water. While no significant differences are noticed for various thermal conductivity profiles in the nanolayer, a good agreement with experiments is observed with Kapitza resistance ≈10−9 m2K/W and sub-nanometer nanolayer thickness. These results confirm the classical nature of thermal conduction in nanofluids and highlight that future studies should rather focus on a better quantification of Kapitza resistance at nanoparticle-fluid interfaces, in order to allow bottom up estimates of their effective thermal conductivity. Keywords: Nanolayer, Kapitza resistance, Nanofluid, Effective medium approximation, Thermal conductivit

Fuel Cells, Metal/Air Batteries : characterization of dual thin-layer flow through cell and determination of solubility and diffusion coefficient of oxygen in aqueous and non-aqueous electrolytes

Until now the energy demand is substantially met by fossil fuels such as natural gas, oil and coal. The available resources are finite. Forecasts assume that at constant consumption the availability of oil reserves in 2050 will decrease rapidly [1]. The amounts of energy required must be replaced by alternative techniques (e.g. solar or wind energy, fuel cells, metal/air batteries). In the combustion of fossil fuels, there are various environmental pollutant emissions such as nitrogen oxides, sulfur dioxide and carbon monoxide. Although carbon dioxide (CO2) as one of the main emissions is not an environmental poison, but it is a greenhouse gas that contributes to global warming. With the adoption of the Kyoto Protocol on 11th of December 1997, an international agreement to reduce emissions was decided [2]. In order to achieve this ambitious goal, it is necessary applying alternatives to develop the burning of fossil fuels [3]. The fossil or alternatively recovered energy can be saved by obtained electrolytic hydrogen, which can be later used for energy in fuel cells. Fuel cells, including the methanol fuel cell (DMFC) can compete with batteries and generators for mobile use. They provide services from a few watts for the power supply of mobile phones or laptops to a few kilowatts to supply of an entire household. Since 2003, the first small series of various automobile manufacturers are developed, in which the energy is produced with fuel cells. Nevertheless, research and development potential still exists [4]. One of the main challenges in the metal-air batteries is the selection of a suitable electrolyte that is characterized with high oxygen solubility, low viscosity, liquid state and low vapour pressure in a wide temperature range and stable in a wide potential window. In this work, we present a new technique to determine the solubility and diffusivity of oxygen in aqueous and non-aqueous electrolytes by on-line differential electrochemical mass spectrometry (DEMS), using a dual thin-layer flow through cell. Two methods are applied to characterize the dual thin-layer flow through cell. The first method considers the hydrodynamic electrochemical behavior of the cell which is composed of two working electrodes and can be considered as the analogue of a rotating ring-disk system. The hydrodynamic electrochemical characteristics such as correlation of the electrolyte flow rate with the faradaic current, transfer efficiency, shielding factor and collection efficiency are studied for Fe3+, Hydroquinone and dissolved H2 solutions. The second method represents the mass spectrometric behavior of the cell for different gaseous and volatile substances. In this method the dual thin-layer flow through cell is connected to the mass spectrometer via a permeable Teflon membrane. The correlation of mass spectrometric current with solution flow rate is studied by this method

Detection of human papillomavirus DNA in intraosseus ameloblastoma

Human Papillomavirus (HPV) infection has been shown as a risk factor in oral carcinogenesis. The association between HPV and benign and malignant neoplasm of oral mucosa, especially surface epithelium-derived tumors, is well established. The role of HPV in pathogenesis of odontogenic cysts and tumors has been published in few articles. The aim of this study was detection of HPV in Iranian patients with intrabony ameloblastoma and investigation of specific risk factors associated with ameloblastoma. One hundred intrabony ameloblastoma and 50 age-sex matched samples as controls were evaluated by polymerase chain reaction for the detection and typing of HPV. Fisher exact and chi square tests were used to assess the data. HPV DNA was detected in 32% of patients and 10% of controls. HPV-6 was the most prevalent genotype (31.6%) in infected cases. It was followed by HPV-11 (12.5%), HPV-16 (12.5%) and HPV-31 (3.1%). We found a significant association between presence of HPV and location of tumor (p = 0.02), traumatic history (p = 0.03) and ododontic therapy (p = 0.01). These findings indicated that HPV-6 probably is one of the most important etiologic agents in causing intraosseous ameloblastoma in Iranian population. © 2006 Academic Journals Inc., USA

Electrocaloric Response of Ferroelectric Material Applicable as Electrothermal Transducer

Electrocaloric response of the PMN-10PT is measured experimentally and compared with the numerical results. Based on the compatibility of the experimental and numerical results, feasibility of using ferroelectric materials as an electrothermal transducer has been investigated. In this study, electrocaloric response of three different ferroelectric capacitors (PMN-10PT, PMN-25PT, and PZN-4.5PT) under an applied periodic electric field have been investigated. Alternative switching of the electrocaloric elements with specific boundary conditions generates a directed heat flux. It can be concluded that each ferroelectric material can be used as a transducer in a special temperature range that in which it has good electrocaloric response

The Mid-Term Changes of Pulmonary Function Tests After Phrenic Nerve Transfer

Background: In the restoration of elbow flexion, the phrenic nerve has proven to be a good donor, but considering the role of the phrenic nerve in respiratory function, we cannot disregard the potential dangers of this method. Objectives: In the current study, we reviewed the results of pulmonary function tests (PFT) in four patients who underwent phrenic nerve transfer. Patients and Methods: We reviewed the results of serial spirometry tests, which were performed before and after phrenic nerve transfer surgery. Results: All patients regained Biceps power to M3 strength or above. None of our patients experienced pulmonary problems or respiratory complaints, but a significant reduction of spirometric parameters occurred after surgery. Conclusions: This study highlights the close link between the role of the phrenic nerve and pulmonary function, such that the use of this nerve as a transfer donor leads to spirometric impairments

Implementation of LiDAR data in hydrological model TOPMODEL for predicting flood: Monticano River case study

2010/2011The semi-distributed rainfall-runoff model, TOPOMODEL is applied to predict the ‎response of Monticano River basin to rain events. TOPMODEL is a topographic based ‎model in which the topographic index has an essential role. Topographic index is a ‎function of the Digital Elevation Model (DEM) resolution. ‎ The high resolution LiDAR data with 1-2 points per meter square, is used as ‎topographic data to generate DEMs, calculate the topographic index as well as extracting ‎the hydrological features. Due to significant effect of the DEM resolution on the ‎topographic index and hydrological features accuracy, different DEMs with 25 m, 50 m, ‎‎100 m and 200 m grid size are generated using LiDAR data. Comparing the density ‎function of topographic index with different resolutions indicate that by decreasing the ‎resolution there is a shift toward the higher values as well as increasing the topographic ‎constant λ from 7.36 for 25 m resolution to 10.32 corresponding to 200 m grid size.‎ TOPMODEL is applied to simulate the six events namely; 20-21 December 1997, 6-7 ‎November 2000, 10-12 August 2002, 21-23 January 2003 , 31 October-1November 2004 ‎and 22-26 December 2009. The model successfully simulates flood levels, with respect to ‎both their extent and to peak time.‎ The sensitivity analysis for scale parameter m and lateral transmissivity T0 shows that ‎the coefficient m affects much more than T0 on the hydrograph shape and peak value.‎ The effect of DEM resolution on the model results is examined. The model results are ‎different, but the differences are very small except for events 2003 and 2009. The results ‎of simulations based on 25 m grid size are very close to those of 50 m grid size, while the ‎simulated discharges using 100 m and 200 m grid size are overestimated.‎ The efficiency of the simulations are calculated for all events using different ‎topographic index distributions. The efficiency of model is in a range of 0.86 for event ‎‎2009 to 0.99 for event 2002. The high values of efficiency can be due to effect of accurate ‎topographic index distribution and hydrological features extracted from high resolution ‎topographic data.‎ The simulation based on DEM with 25 m resolution shows slightly higher efficiency ‎values. This means that generating higher resolution DEM with respect to suggested 50 m ‎grid size for TOPMODEL, may give a more accurate output as it is evident from this ‎study.‎XXIV Ciclo198

Sliding Dynamics of Parallel Graphene Sheets: Effect of Geometry and Van Der Waals Interactions on Nano-Spring Behavior

Graphene and carbon nanotubes are promising materials for nanoelectromechanical systems. Among other aspects, a proper understanding of the sliding dynamics of parallel graphene sheets or concentric nanotubes is of crucial importance for the design of nano-springs. Here, we analytically investigate the sliding dynamics between two parallel, rigid graphene sheets. In particular, the analysis focuses on configurations in which the distance between the sheets is kept constant and lower than the equilibrium interlayer spacing of graphite (unstable configurations). The aim is to understand how the interlayer force due to van der Waals interactions along the sliding direction changes with the geometrical characteristics of the configuration, namely size and interlayer spacing. Results show metastable equilibrium positions with completely faced sheets, namely a null force along the sliding direction, whereas net negative/positive forces arise when the sheets are approaching/leaving each other. This behavior resembles a molecular spring, being able to convert kinetic into potential energy (van der Waals potential), and viceversa. The amplitude of both storable energy and entrance/exit forces is found to be proportional to the sheet size, and inversely proportional to their interlayer spacing. This model could also be generalized to describe the behavior of configurations made of concentric carbon nanotubes, therefore allowing a rational design of some elements of carbon-based nanoelectromechanical systems

Lamotrigine extends lifespan but compromises health span in Drosophila melanogaster

The discovery of life extension in Caenorhabditis elegans treated with anticonvulsant medications has raised the question whether these drugs are prospective anti-aging candidate compounds. The impact of these compounds on neural modulation suggests that they might influence the chronic diseases of aging as well. Lamotrigine is a commonly used anticonvulsant with a relatively good adverse-effects profile. In this study, we evaluated the interaction between the impacts of lamotrigine on mortality rate, lifespan, metabolic rate and locomotion. It has been proposed in a wide range of animal models that there is an inverse relationship between longevity, metabolic rate, and locomotion. We hypothesized that the survival benefits displayed by this compound would be associated with deleterious effects on health span, such as depression of locomotion. Using Drosophila as our model system, we found that lamotrigine decreased mortality and increased lifespan in parallel with a reduction in locomotor activity and a trend towards metabolic rate depression. Our findings underscore the view that assessing health span is critical in the pursuit of useful anti-aging compounds