Double Step Research Articles

Investigation of Non-Newtonian Fluids Flow Behavior in A Double Step Expansion Channel: Part 2

Investigation of Non-Newtonian Fluids Flow Behavior in A Double Step Expansion Channel: Part 2

Involvement of Aquaporins in the Pathogenesis, Diagnosis and Treatment of Sjögren's Syndrome.

Sjögren’s syndrome (SS) is a chronic autoimmune disease characterized by lymphocytic infiltration of salivary and lacrimal glands resulting in diminished production of saliva and tears. The pathophysiology of SS has not yet been fully deciphered. Classically it has been postulated that sicca symptoms in SS patients are a double step process whereby lymphocytic infiltration of lacrimal and salivary glands (SG) is followed by epithelial cell destruction resulting in keratoconjunctivitis sicca and xerostomia. Recent advances in the field of the pathophysiology of SS have brought in new players, such as aquaporins (AQPs) and anti AQPs autoantibodies that could explain underlying mechanistic processes and unveil new pathophysiological pathways offering a deeper understanding of the disease. In this review, we delineate the link between the AQP and SS, focusing on salivary glands, and discuss the role of AQPs in the treatment of SS-induced xerostomia.

Absolute Mean Graceful Labeling in Path Union of Various Graphs

Present paper aims to focus on absolute mean graceful labeling in path union of various graphs. We proved path union of graphs like tree, path Pn, cycle Cn, complete bipartite graph Km, n, grid graph PM × Pn, step grid graph Stn and double step grid graph DStn are absolute mean graceful graphs.

Primary concept of nickel toxicity - an overview.

Toxic metals, including excessive levels of essential metals tend to change biological structures and systems into either reversible or irreversible conformations, leading to the derangement of organ functions or ultimate death. Nickel, a known heavy metal is found at very low levels in the environment. Nickel is available in all soil types and meteorites and also erupts from volcanic emissions. In the environment, nickel is principally bound with oxygen or sulfur and forms oxides or sulfides in earth crust. The vast industrial use of nickel during its production, recycling and disposal has led to widespread environmental pollution. Nickel is discharged into the atmosphere either by nickel mining or by various industrial processes, such as power plants or incinerators, rubber and plastic industries, nickel-cadmium battery industries and electroplating industries. The extensive use of nickel in various industries or its occupational exposure is definitely a matter of serious impact on human health. Heavy metals like nickel can produce free radicals from diatomic molecule through the double step process and generate superoxide anion. Further, these superoxide anions come together with protons and facilitate dismutation to form hydrogen peroxide, which is the most important reason behind the nickel-induced pathophysiological changes in living systems. In this review, we address the acute, subchronic and chronic nickel toxicities in both human and experimental animals. We have also discussed nickel-induced genotoxicity, carcinogenicity, immunotoxicity and toxicity in various other metabolically active tissues. This review specifically highlighted nickel-induced oxidative stress and possible cell signaling mechanisms as well.

Application of electromagnetic forming in terminal crimping using different types of field shapers

Mechanical crimping is the most used method of pressure connection for permanent electrical contact in electrical and electronic equipment. Terminal plastic deformation on multi-wire strands is carried out to achieve mechanical strength and electrical conductivity. Electromagnetic (EM) is assumed to be an alternative method to overcome the challenges of spring back in the terminal on tool relaxation, cracks, non-uniform deformation, reduced strength, decreased the durability of joints in conventional crimping tool. Implementation of the field shaper (FS) has been proposed to enhance the magnetic field to concentrate the magnetic pressure at the required location for the effective terminal crimping over the wire strands. In this work, crimping was carried out using FS as a tool. Experiments were carried out utilizing tapered FS, single step FS and double step FS on aluminum terminal over seven strands aluminum wire strands that are commercially utilized for making interconnections. Results like contact length, contact resistance, terminal deformation, surface hardness, cross-section hardness and pull-out tests were found out and compared simultaneously. Also, the test results were compared with the samples crimped using a conventional crimping tool. From the results single step FS was found to be the most efficient FS than double step FS whereas the tapered FS was the least efficient. The results will be helpful in determining the geometry for the field shapers in similar applications.

Investigation of Non-Newtonian Fluids Flow Behavior in A Double Step Expansion Channel: Part 2

A numerical investigation to study the behavior of the turbulent non-newtonian flow through a channel from two expansions with constant heat flux at the lower wall is calculated. This behavior predicted for Reynolds number from 16000 to 100000 and for the range of power law index from 0.4 to 1.6. The distance ratio between the two expansions is varied from 1 to 6 with expansion ratio from 1.5 to 3 and aspect ratio from 1 to 4. These results are obtained by using ANSYS FLUENT 15.0. The results illustrate the effect of the first expansion on the second expansion and the variation of the reattachment length and Nusselt number. These results gave an idea about the ability of the step distance to control the whole flow structure

Instrumented Wireless SmartInsole System for Mobile Gait Analysis: A Validation Pilot Study with Tekscan Strideway

A SmartInsoles Cyber-Physical System (CPS) is designed and implemented for the purpose of measuring gait parameters of multiple users in a restriction-free environment. This CPS comprises a master software installed on a computer and numerous multi-sensory health devices in the form of smart insoles. Each of these insoles contains 12 Force-Sensitive Resistor (FSR) sensors, an Inertial Measurement Unit (IMU), a WiFi-enabled microcontroller and a battery to power all components. A validation pilot study was completed in collaboration with the Interdisciplinary School of Health Sciences at the University of Ottawa by performing 150 trials on 15 healthy subjects. Each subject performed 10 walks on the Tekscan Strideway gait mat system, while simultaneously wearing the designed SmartInsoles CPS. Spatiotemporal data for over 450 unique steps were collected by both systems. These data were analyzed carefully, and a thorough comparison was performed between the results from the two systems. Seven parameters were analyzed in this study: stride time, stance time, swing time, double support time, step time, cadence and gait time. Detailed results in the form of tables, scatterplots, histograms and Bland–Altman graphs were generated. Analysis of the results shows high agreement between the values of the two systems and suggests high accuracy of the implemented CPS as a multi-device, multi-sensory system for gait measurement and analysis.

Effect of obstacle positions for turbulent forced convection heat transfer and fluid flow over a double forward facing step

A numerical study has been performed to analyze turbulent fluid flow behaviour along with forced convective heat transfer for a rectangular channel having double forward facing step with cylindrical obstacles placed near the steps. The flow equations as well as standard k−ε model used for turbulence is solved by a commercial code FLUENT. The positions of the obstacles are varied in vertical direction. The effect of different position ratios of the obstacles and Reynolds number, on the heat transfer and hydrodynamic behaviour of the flow, has been investigated. Results reveal that, when both the obstacles are positioned vertically with same position ratio, the rate of heat transfer increases as obstacle position ratio increases. Optimum vertical positions of the obstacles has also been individually obtained from the results to get the maximum heat transfer co-efficient.

Design of three Step Joint typologies: Review of European standardized approaches

When assessing timber roof structures on-site for any restoration project, engineers can be faced with elements that, over time, were poorly preserved, especially damaged joints in contact with moist masonry walls. Before dealing with any intervention technique, the mechanical behaviour of such carpentry connections must be properly understood. Therefore, it has to be determined how the joints fail, which parameters (i.e. geometrical configurations and mechanical properties of the joint) influence the appearance conditions of failure modes, and the way how the internal forces are distributed within the connection. Therefore, the present paper aims at overviewing three different typologies of Step Joints (SJ) which can often be encountered within traditional timber carpentries between the rafter and the tie beam: the Single Step Joint, the Double Step Joint, and the Single Step Joint with Tenon-Mortise. Regarding each SJ typology, some design rules and geometrical recommendations can be gathered from European Standards and from authors of works on the subject, but no design equation is conventionally defined. Hence, new design models have been determined through the Analytical Campaign for the investigated Step Joints according to their geometrical parameters and to both failure modes: the shear crack in the tie beam and the crushing at the front-notch surface. In order to check the reliability of new design models and the emergence conditions of both failure modes, future experiments and numerical analysis on the three SJ typologies are going to be performed.

Effect of Sharp Diameter Geometrical Modulation on the Magnetization Reversal of Bi-Segmented FeNi Nanowires.

Controlling functional properties of matter and combining them for engineering a functional device is, nowadays, a common direction of the scientific community. For instance, heterogeneous magnetic nanostructures can make use of different types of geometrical and compositional modulations to achieve the control of the magnetization reversal along with the nano-entities and, thus, enable the fabrication of spintronic, magnetic data storage, and sensing devices, among others. In this work, diameter-modulated FeNi nanowires are fabricated paying special effort to obtain sharp transition regions between two segments of different diameters (from about 450 nm to 120 nm), enabling precise control over the magnetic behavior of the sample. Micromagnetic simulations performed on single bi-segmented nanowires predict a double step magnetization reversal where the wide segment magnetization switches near 16 kA/m through a vortex domain wall, while at 40 kA/m the magnetization of the narrow segment is reversed through a corkscrew-like mechanism. Finally, these results are confirmed with magneto-optic Kerr effect measurements at the transition of isolated bi-segmented nanowires. Furthermore, macroscopic vibrating sample magnetometry is used to demonstrate that the magnetic decoupling of nanowire segments is the main phenomenon occurring over the entire fabricated nanowires.

Properties of Porous Magnesium Using Polymethyl Methacrylate (PMMA) as a Space Holder

Porous magnesium has been recognized as a promising biodegradation metal for bone substitute application because of its excellent biocompatibility, low density, ability to biodegrade in vivo and excellent mechanical properties. In the present work, porous magnesium was fabricated by powder metallurgy using spherical polymethyl methacrylate (PMMA) as a space holder. To determine the optimum sintering temperature for porous magnesium fabrication, the porous magnesium was fabricated using double step sintering process at various sintering temperature (550°C, 585°C and 620°C) in first stage of research. The porous magnesium fabricated was then characterized for morphology, porosity, density and compressive strength. Density of porous magnesium increases and the porosity decreases with increasing sintering temperature. The mechanical characterization indicated that porous magnesium sintered at 620°C exhibited the highest compressive strength and density with optimum range of porosity of 39.37%. For second stage of research, porous magnesium with porosities of 39.38 – 40.82% was produced with different sizes of PMMA particles (38-63 µm, 63-90 µm and 90-125 µm). The compressive yield strength ranges between 19.95 MPa to 23.28 MPa and increases with decreasing PMMA particles size and porosity. These results proven that the PMMA has a potential to be used as space holder in porous magnesium for biomedical application.

Refined isolation techniques for GaN-based high electron mobility transistors

This work investigates the Ar+/N+ based ion implantation and Ar based reactive ion etching (RIE) techniques for device isolation. A comparison of ion implantation technique with three ion energies (20/35/65 keV) and 4 energies (20/35/65/160 keV) of Ar+ and N+ with different ion doses for isolation was reported. Use of 4 energy ion implantation provided better isolation. Ar based single and dual step reactive ion etching process was also explored for the mesa isolation of GaN HEMTs. The etch rate increases (44.7%) significantly after mixing of Ar gas directly with BCl3: Cl2 combination. Hence, the Ar addition in the single step etching proved to be more beneficial as compared to the double step etching technique.

Spectroscopy takes electrochemistry beyond the interface: A compact analytical solution for the reversible first-order catalytic mechanism

The monitoring of the non-interfacial phenomena of mass transport and homogeneous chemical reactions by combining spectroscopic and electrochemical methods is examined. The spectroelectrochemical study of a charge transfer process is addressed, considering the possibilities that the electro-consumed species is regenerated in solution by means of a first-order chemical reaction or that the diffusivity of the oxidized and reduced species differ from each other significantly.Novel closed-form explicit analytical expressions for the concentration profiles and the absorbance response of all the species for any voltammetric technique are deduced, taking into account the two main working arrangements: the normal-beam and parallel-beam modes. The analytical solutions are particularized to double potential step chronoamperometry and to cyclic voltammetry. The corresponding chronoabsorptometric and voltabsorptometric responses in parallel-mode are proven to provide additional information with respect to electrochemical-only measurements, as well as insights into the solution regions next to the interface where the concentration changes and equilibrium disruption take place. With this theory the absorptometric response can be related to the physicochemical dynamics of the redox system and optimum configuration and conditions for the study of diffusion and reaction layers, the species diffusion coefficients and the chemical kinetic and equilibrium constants can be established.

Scalable Clustering of Individual Electrical Curves for Profiling and Bottom-Up Forecasting

Smart grids require flexible data driven forecasting methods. We propose clustering tools for bottom-up short-term load forecasting. We focus on individual consumption data analysis which plays a major role for energy management and electricity load forecasting. The first section is dedicated to the industrial context and a review of individual electrical data analysis. Then, we focus on hierarchical time-series for bottom-up forecasting. The idea is to decompose the global signal and obtain disaggregated forecasts in such a way that their sum enhances the prediction. This is done in three steps: identify a rather large number of super-consumers by clustering their energy profiles, generate a hierarchy of nested partitions and choose the one that minimize a prediction criterion. Using a nonparametric model to handle forecasting, and wavelets to define various notions of similarity between load curves, this disaggregation strategy gives a 16% improvement in forecasting accuracy when applied to French individual consumers. Then, this strategy is implemented using R—the free software environment for statistical computing—so that it can scale when dealing with massive datasets. The proposed solution is to make the algorithm scalable combine data storage, parallel computing and double clustering step to define the super-consumers. The resulting software is openly available.

Simultaneous HS-SPME GC-MS determination of short chain fatty acids, trimethylamine and trimethylamine N-oxide for gut microbiota metabolic profile

Trimethylamine (TMA), trimethylamine-N-oxide (TMAO) and short chain fatty acids (SCFAs), as acetic, propionic, butyric and valeric acids are among the most important products of the gut microbiota (GM) metabolism. The present study is aimed at the determination of TMA, TMAO and SCFAs by a double step headspace-solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS) analysis, allowing the simultaneous quantitation of both the acidic and basic metabolites in faecal samples. TMAO amount was evaluated after its reduction to TMA by using Fe(II)-EDTA complex as a reagent. Under the fully validated experimental conditions, adequate sensitivity (LOQ 0.011–0.23 µmol g−1), good accuracy (79 – 110%) and precision (CV% < 11%) were achieved for all the target analytes. The presented method is successfully applied to the quantitation of the considered gut metabolites in faecal samples from Italian healthy volunteers.

An Expeditious Synthesis of 1-Thiotrehalose

A two-step synthesis of 1-thiotrehalose is reported. In the key TMSOTf-mediated double thioglycosylation step, the tri-O-benzyl 1,6-anhydro-D-glucose reactant behaves both as a glycosyl donor and a glycosyl acceptor precursor. In this highly convergent process, two carbon-sulfur bonds are created at the anomeric positions with a high level of stereocontrol.

Magic Moments: Determinants of Stress Relief and Subjective Wellbeing from Visiting a Cultural Heritage Site.

We provide an experimental evaluation of the impact of aesthetic experiences in terms of stress reduction (cortisol levels) and wellbeing increase. The test experience is a visit to the vault of the Sanctuary of Vicoforte, Italy. Data have been collected using a double step method. A structured interview in relation to the individual subjective well-being has been administered to a sample of 100 subjects. In addition, a sample of their saliva has been taken, and its cortisol level measured, before and after the experience, and likewise for momentary wellbeing measured on a Visual Analogous Scale. Subjects reported an average increase of 40% in wellbeing and a decrease of the 60% in the cortisol level. The recorded cortisol level values dropped on average well beyond the decrease normally associated to its circadian cycle. The modulating role of various variables has been appreciated, and profiling of the typical subjects who are wellbeing respondents/non-respondents and cortisol respondents/non-respondents has been carried out. We conclude that aesthetic experience seems to have a noticeable impact on individual physical and mental health. In both dominions, cultural participation intensity is significantly correlated to the response. The study underlines the potential of the arts and culture as a new platform for public health practices and new approaches to welfare policy design.

I-V characteristic behavior of BSCCO-2223 superconductor under low intensity DC magnetic fields a Home-Made Experiment

Electrical characterization of superconductor materials exposed to external magnetic field play a important role for many technological applications. In this paper, the electrical characterization of Bi-2223 pellet prepared by conventional route was performed. The electrical resistance temperature dependence (RxT), showed a superconductor transition at around 105 K. The current-voltage (I-V) behavior under magnetic field and temperature has been investigated, the results point to a powerlaw dependence between the electrical current (I) and applied voltage (V), at different conditions, as described by the literature. The external DC magnetic field, was produced by a simple home-made apparatus, where a simple copper coil was used to produce an external DC magnetic field between 2,0 mT and 8,0 mT. Then, the dependence of the critical current (Ic) on magnetic field and temperature has been studied, revealing a double step behavior DOI: http://dx.doi.org/10.30609/JETI.2018-2.5682

I-V characteristic behavior of BSCCO-2223 superconductor under low intensity DC magnetic fields a Home-Made Experiment

Electrical characterization of superconductor materials exposed to external magnetic field play a important role for many technological applications. In this paper, the electrical characterization of Bi-2223 pellet prepared by conventional route was performed. The electrical resistance temperaturedependence (RxT), showed a superconductor transition at around 105 K. The current-voltage (I-V) behavior under magnetic field and temperature has been investigated, the results point to a powerlaw dependence between the electrical current (I) and applied voltage (V), at different conditions, as described by the literature. The external DC magnetic field, was produced by a simple home-made apparatus, where a simple copper coil was used to produce an external DC magnetic field between 2,0 mT and 8,0 mT. Then, the dependence of the critical current (Ic) on magnetic field and temperature has been studied, revealing a double step behavior DOI:http://dx.doi.org/10.30609/JETI.2018-2.5682

Design and Synthesis of Chiral oxa-Spirocyclic Ligands for Ir-Catalyzed Direct Asymmetric Reduction of Bringmann's Lactones with Molecular H2.

We herein present a facile and column-free synthetic route toward a structurally unique oxa-spirocyclic diphenol, termed as O-SPINOL. Features of the synthesis include the construction of the all-carbon quaternary center at an early stage, a key double intramolecular SNAr step to introduce the spirocycles and the feasibility of operating on >100 g scale. Both enantiomers of O-SPINOL can be easily accessed through optical resolution with l-proline by control of the solvent. The chiral tridentate ligand O-SpiroPAP derived from O-SPINOL has been successfully synthesized and applied in the iridium-catalyzed asymmetric hydrogenation of bridged biaryl lactones under mild reaction conditions, providing valuable and enantioenriched axially chiral molecules in excellent yields and enantioselectivities (up to 99% yield and >99% ee). This method represents a rare example of constructing axially chiral molecules by direct reduction of esters with H2.