Open Junction Research Articles

Three-Dimensional Numerical Simulation of a Two-Phase Supercritical Open Channel Junction Flow

This study investigates the computational fluid dynamics (CFD) modeling of supercritical open channel junction flow using two different turbulence models: k-ω shear stress transport (SST) and k-ω SST scale-adaptive simulation (SAS), in conjunction with Volume of Fluid (VOF) and mixture multiphase models. The efficacy of these models in predicting the intricate free surface fluctuation and free surface elevation in a supercritical junction is evaluated through a comprehensive analysis of time-averaged free surface data obtained from CFD simulations and Light Detection and Ranging (LIDAR) measurements. The dimensionless Reynolds (Re) and Froude (Fr) numbers of the investigated scenario were Fr = 9 and Re = 5.1 × 104 for the main channel, and Fr = 6 and Re = 3.3 × 104 for the side channel. The results of the analysis demonstrated a satisfactory level of agreement with the experimental data. However, certain limitations associated with both CFD and LIDAR were identified. Specifically, the CFD performance was limited by the model’s incapacity to consider small-scale turbulent effects and to model air bubbles smaller than the cell size while the LIDAR measurements were limited by instrument range, inability to provide insight into what is happening below the water surface, and blind spots. Nonetheless, the k-ω SST turbulent model with the VOF multiphase model most closely matched the LIDAR results.

Organometallic Pillarplexes That Bind DNA 4-Way Holliday Junctions and Forks.

Holliday 4-way junctions are key to important biological DNA processes (insertion, recombination, and repair) and are dynamic structures that adopt either open or closed conformations, the open conformation being the biologically active form. Tetracationic metallo-supramolecular pillarplexes display aryl faces about a cylindrical core, an ideal structure to interact with open DNA junction cavities. Combining experimental studies and MD simulations, we show that an Au pillarplex can bind DNA 4-way (Holliday) junctions in their open form, a binding mode not accessed by synthetic agents before. Pillarplexes can bind 3-way junctions too, but their large size leads them to open up and expand that junction, disrupting the base pairing, which manifests in an increased hydrodynamic size and lower junction thermal stability. At high loading, they rearrange both 4-way and 3-way junctions into Y-shaped forks to increase the available junction-like binding sites. Isostructural Ag pillarplexes show similar DNA junction binding behavior but lower solution stability. This pillarplex binding contrasts with (but complements) that of metallo-supramolecular cylinders, which prefer 3-way junctions and can rearrange 4-way junctions into 3-way junction structures. The pillarplexes' ability to bind open 4-way junctions creates exciting possibilities to modulate and switch such structures in biology, as well as in synthetic nucleic acid nanostructures. In human cells, the pillarplexes do reach the nucleus, with antiproliferative activity at levels similar to those of cisplatin. The findings provide a new roadmap for targeting higher-order junction structures using a metallo-supramolecular approach, as well as expanding the toolbox available to design bioactive junction binders into organometallic chemistry.

Fabrication of an Open Gate-4H-SiC Junction Field Effect Transistor for Bio-Related and Chemical Sensing Applications

In this paper, a suitable process technology is employed to fabricate a new open gate silicon carbide-based junction field-effect transistor (OG-4H-SiC-JFET) intended to be used for all types of biochemical sensing applications. The main focus is dedicated to the fabrication steps and specifically the plasma etching of the SiC as it is the key step to pattern the device components. All necessary I-V characteristics (IDS-VDS and IDS-VGS) have been derived and show acceptable electrical performance. Furthermore, the electrical characteristics of the OG-4H-SiC JFET were simulated using 3D Silvaco ATLAS and are in line with the experimental electrical characteristics. The efficacity and simplicity of the process described in this paper is the first step for future development of biochemical sensors based on SiC-FETs.

Quantizing a multi-pronged open string junction

Abstract Covariant quantization of a multi-pronged open bosonic string junction is studied beyond static analysis. Its excited states are described by a set of ordinary bosons as well as some sets of twisted bosons on the worldsheet. The system is characterized by a certain large algebra of twisted type that includes a single Virasoro algebra as a subalgebra. By properly defining the physical states, one can show that there are no ghosts in the Hilbert space.

Experimental investigation and one-dimensional (1D) dynamic modelling of steady flow through a levee breach

Accurate prediction of levee breach flow is crucial to the mitigation of floods, and for timely breach closure. In this work, flow in an idealized levee breach has been studied for the case of a trapezoidal embankment. Flow data including water depths, surface velocities, and flow discharges were obtained from 28 experiments considering different cases of breach width and main channel downstream water depth. Ultrasonic sensors were used to record the water depth in the channel and the breach. The water surface velocity was measured using a particle tracking velocity method. A one-dimensional dynamic model based on the conservation of mass and momentum in two control volumes was developed by drawing similarities between levee breach flows and diverging open channel junction flows. The proposed model shows satisfactory performance against two independent datasets.

Particle creation and annihilation in an exclusion process on networks

To mimic the complex transport-like collective phenomena in a man-made or natural system, we study an open network junction model of totally asymmetric simple exclusion process with bulk particle attachment and detachment. The stationary system properties such as particle density, phase transitions, and phase diagrams are derived theoretically utilising the mean field approach. The steady-state phases have been categorized into various sub-classes based upon the phase transitions occurring across the junction. It is found that the number of steady-state phases depends on the number of incoming and outgoing segments at the junction. Further, an increase in the particle non-conserving rates significantly affects the topology of the phase diagram, and the number of stationary phases changes in a non-monotonic way. For both the case of equal and unequal incoming and outgoing segments, the critical values of non-conserving rates at which the topology of the phase diagram changes are identified. The theoretical results are validated using extensive Monte Carlo simulations.

Novel Field-Effect Transistor Sensor for DNA Storage Monitoring

This article presents a novel open gate junction field-effect transistor (OG-JFET)-based sensor that can be used for various life science applications including deoxyribonucleic acid (DNA) storage monitoring. We put forward the design, modeling, implementation, and characterization of OG-JFET sensor using a foundry process through CMC Microsystems. We also demonstrate and discuss the functionality and applicability of the proposed sensor for monitoring DNA samples suitable for DNA storage applications. Synthetic storage has emerged as an intriguing data storage solution with high density and long-term preservation potential. Most common modalities include the conversion of digital data into synthesized nucleotides, the physical storage of DNA materials, and reading out the data via sequencing and other computational processes. Among these, this article tackles the challenge of physical storage monitoring of DNA materials by developing a sensor for measurement of DNA samples in dry conditions. The proposed sensor reveals a linear response of sensor toward DNA concentration in ultra-pure water. Across a 0.7 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> sensing area, a DNA mass concentration from approximately 100–400 ng/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{L}$ </tex-math></inline-formula> has been detected using OG-JFET demonstrating a sensitivity of 30 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{A}$ </tex-math></inline-formula> /(ng/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{L}$ </tex-math></inline-formula> ). These performance quantities imply a promising role for OG-JFETs in emerging biotechnology applications including DNA storage monitoring.

Research of thermotechnical characteristics of domestic boiler with a mechanical pellet burner

An experimental study of technologies for direct combustion of pellets in a domestic boiler was conducted. Experimental studies to determine the thermophysical characteristics of the process of burning pellet fuel in the bulk layer were performed using a pellet burner Pelletron-15.To determine the patterns of the process of burning pellets in the burner and the thermal characteristics of the domestic boiler with a pellet burner, studies of the temperature of the boiler volume at different modes of operation of the burner were performed. Temperature measurement was performed using HA-thermocouples with open junction, located in the furnace space at different heights and different distances from the initial cross section of the burner. The analysis of the chemical composition of flue gases, which was determined using a gas analyzer TESTO 330-2LL, namely determined the temperature of the flue gases at the measurement point, as well as the concentration of oxygen (O2), carbon dioxide (CO2), carbon monoxide (CO), nitrogen oxides (NOx) and other parameters.According to the results of experiments, the temperature distribution in the furnace space of the solid fuel boiler Viadrus with a thermal capacity of up to 24 kW with a mechanized burner Pelletron-15 with a pellet feed hopper built into the front panel was determined.In addition, based on the results of some experimental studies, the heat of combustion, humidity and ash content of pellets were determined. The dependences on the time change of the boiler temperature at the stage of quasi-stationary mode of wood pellet combustion are obtained: at the minimum and maximum fuel supply from the hopper, as well as at the maximum fuel supply mode after the supply of additional air from the fan and in the pellet combustion process.The influence of speed and temperature of air introduced into the combustion chamber was determined. According to the research results, measures are proposed to improve the design characteristics of the pellet burner in low-power boilers (10…30 kW).

V-OG05 Robotic Hellers Myotomy

Abstract Background Achalasia is a rare condition affecting less than 1:100,000 patients. Treatment for this rare condition include balloon dilation, botox injection, endoscopic myotomy (POEMS) or surgical myotomy. Laparoscopic surgical myotomy is the “go to” approach for most surgeons; it is tried and tested, can be performed safely and quickly with a low complication rate, minimal pain and a short length of stay. Methods This video presents the technique adopted for robotic oesophageal myotomy in a patient with type II achalasia. A 4 arm technique was adopted with arm 4 on the patients left. The Davinci X system was used in this case. A Nathensen liver retractor was used to retract the liver; robotic instruments included the hook and cadiere forceps x2. Results The procedure was successfully performed; the operative time was 53 minutes, LOS was &amp;lt;24 hours. Check endoscopy revealed a wide open gastro-oesophageal junction and a long myotomy. The patient noted an improvement in symptoms with 24 hours and has had no significant reflux. Conclusion The enhanced magnified 3D view on the robotic platform allows better visualisation of the hiatal structures, vagal nerves and muscle fibres when performing the myotomy. Using the 4th arm to retract the lateral edge of the oesophageal muscle provides a very safe and stable platform to perform a long myotomy. I think the robotic system should be adopted as the standard approach for a hellers myotomy.

Reduction of the Flow Separation Zone at Combining Open-Channel Junction by Applying Alternate Suction and Blowing

The flow separation zone (FSZ) is one of the main flow characteristics of the combining open channel junction and is associated with energy dissipation. Bed shear stress in the contracted flow region increases as the channel’s effective width is reduced. Reduction of the FSZ at the junction to improve efficiency is desirable. The present numerical study focuses on the effect of continuous suction and blowing perturbations in reducing the FSZ at a right-angled open channel junction. The flow field is simulated using computational fluid dynamics (CFD) software. The numerical model is validated by comparing the simulated velocity field, water surface elevation, and energy loss for the unperturbed junction flow with corresponding experimental results available in the literature. The continuous suction and blowing perturbation is generated by a sinusoidal function with zero net discharge and is applied through a rectangular slit. Three different slit locations are considered downstream of the junction. The simulated results (time-averaged) show that the sinusoidal perturbation is effective in reducing the dimensions of the FSZ and, consequently, the energy loss and bed shear stress. The results demonstrate the enhanced effectiveness in reducing the energy loss when the slit is more proximate to the junction for the chosen flow configuration and the sinusoidal perturbation characteristics. The results of the time-averaged depth ratios show only a marginal reduction due to the flow perturbation.

Role of nearly-degenerate vibrational modes in electron transport through weakly-coupled molecular junctions

We consider an open molecular junction in which electrons are coupled to multi-mode phonons. Using a master equation approach for equilibrated phonons, we show that nearly-degenerate phonon modes can be mapped into an effective single mode, which can result in a noticeable reduction of computational costs. As an illustration, we apply our theory to the OPV-5 molecule and show that we can obtain the consistent conductance spectra while reducing the computational time by orders of magnitude.

Modeling Large Two-Dimensional Superconducting Quantum Interference Device Arrays With Josephson Junction Opens and Shorts

In this paper we explore the effects of open and shorted Josephson Junctions (JJs) on the current-voltage (I-V) curve, and the voltage-field (V-B) curve of two-dimensional high temperature superconductor (HTS) Gaussian distributed Superconducting Quantum Interference Device (SQUID) Arrays (SQAs). We examine two cases here. The first case involves having a portion of the parallel rows of junctions containing either a single open or shorted junction. The second case involves an array having large blocks of open JJs. The large blocks represent a large damaged area on an array.

A comparative study on the Efficacy of Retroperitoneoscopic Pyeloplasty and Open Surgery for Ureteropelvic Junction Obstruction in Children.

Objectives:To compare the therapeutic effect of retroperitoneoscopic dismembered pyeloplasty and open ureteropelvic junction plasty on the ureteropelvic junction obstruction (UPJO) in children.Methods:After the retrospective analysis of clinical data, 78 children with ureteropelvic junction stenosis treated from January, 2012 to June, 2018 were divided into two groups: OP (open pyeloplasty) group (38 cases) and LP (laparoscopic dismembered pyeloplasty) group (40 cases) according to the surgical methods. The operation time, intraoperative bleeding volume, postoperative length of stay (LOS), postoperative complication rate, postoperative hydronephrosis improvement and other indicators were compared between the two groups.Results:All patients underwent surgery successfully, without conversion to open surgery in LP group. The incidence of postoperative urine leakage and the recovery of hydronephrosis between LP group and OP group 12 months after operation showed no statistically significant difference (P>0.05). The intraoperative bleeding volume, the incidence of postoperative retroperitoneal hematoma, and the postoperative LOS in LP group were lower than those in OP group, while the operation time was longer than that in the OP group, with statistically significant difference (P<0.05).Conclusion:Retroperitoneoscopic dismembered pyeloplasty had similar effect with open dismembered pyeloplasty, but faster recovery and fewer complications, so it has become the preferred treatment method for UPJO in children.

Type 2 immunity in the skin and lungs.

There has been extensive progress in understanding the cellular and molecular mechanisms of inflammation and immune regulation in allergic diseases of the skin and lungs during the last few years. Asthma and atopic dermatitis (AD) are typical diseases of type 2 immune responses. interleukin (IL)-25, IL-33, and thymic stromal lymphopoietin are essential cytokines of epithelial cells that are activated by allergens, pollutants, viruses, bacteria, and toxins that derive type 2 responses. Th2 cells and innate lymphoid cells (ILC) produce and secrete type 2 cytokines such as IL-4, IL-5, IL-9, and IL-13. IL-4 and IL-13 activate B cells to class-switch to IgE and also play a role in T-cell and eosinophil migration to allergic inflammatory tissues. IL-13 contributes to maturation, activation, nitric oxide production and differentiation of epithelia, production of mucus as well as smooth muscle contraction, and extracellular matrix generation. IL-4 and IL-13 open tight junction barrier and cause barrier leakiness in the skin and lungs. IL-5 acts on activation, recruitment, and survival of eosinophils. IL-9 contributes to general allergic phenotype by enhancing all of the aspects, such as IgE and eosinophilia. Type 2 ILC contribute to inflammation in AD and asthma by enhancing the activity of Th2 cells, eosinophils, and their cytokines. Currently, five biologics are licensed to suppress type 2 inflammation via IgE, IL-5 and its receptor, and IL-4 receptor alpha. Some patients with severe atopic disease have little evidence of type 2 hyperactivity and do not respond to biologics which target this pathway. Studies in responder and nonresponder patients demonstrate the complexity of these diseases. In addition, primary immune deficiency diseases related to T-cell maturation, regulatory T-cell development, and T-cell signaling, such as Omenn syndrome, severe combined immune deficiencies, immunodysregulation, polyendocrinopathy, enteropathy, X-linked syndrome, and DOCK8, STAT3, and CARD11 deficiencies, help in our understanding of the importance and redundancy of various type 2 immune components. The present review aims to highlight recent advances in type 2 immunity and discuss the cellular sources, targets, and roles of type 2 mechanisms in asthma and AD.

The effects of environment on thermopower and thermocurrent in open molecular junctions

In this work, we consider an open single level molecular junction with electrons coupled to a single frequency phonon mode, in which the phonons are also coupled to another heat bath. By applying a temperature gradient between the electrical leads and investigating thermocurrent in non-linear regime, it is shown that the environment can excite phonons which may result in either suppression or very significant enhancement of thermocurrent, depending on the onsite energy. Similarly, in the linear regime the effects of environment are seen in the Seebeck coefficient.

Discharge and flow field simulation of open channel sewer junction using artificial intelligence methods

One of the most important parameters in designing of sewer structures is the ability to accurately simulation the discharge and velocity field of them. Among the various sewer receiving inflow methods, open channel junctions are mostly occurring. Because of the separation and contraction zone that occur at the open channel junctions, the fluid flow has a complex behavior. Modeling is carried out by Radial Basis Function (RBF) neural network, Gene Expression Programming (GEP), and Multiple Non-Linear Regression (MNLR) methods. Finding the optimum situation for GEP and RBF models are done by examining the various mathematical and linking functions for GEP and different number of hidden neurons and spread amount for RBF. In order to use the models in practical situations, three equations were conducted by using the RBF, GEP, and MNLR methods in modeling the longitudinal velocity. Then, the surface integral of the presented equations is used to simulate the flow discharge. The results showed that the GEP and RBF method perform significantly better than the MNLR in open channel junction characteristics simulations. The GEP method has higher performance in modeling the longitudinal velocity field compare with the RBF. However, the RBF presented more reliable results on the discharge simulations.

Influence of a thermal bath on the transport properties of an open molecular junction

In a molecular junction (MJ) which connects two electrical leads, electron-phonon coupling has significant effects on the transport properties. However, the MJ is not thermally isolated and the phonons can be coupled to another thermal bath. For strong enough couplings, the bath thermalizes phonons on the MJ so that their number would be bias independent. However, in medium and weak coupling regimes, the number of phonons created in MJ depends on the bias voltage. Obtaining the master equation (ME) for this system and comparing the results with the case where we have no such thermal bath, we show that if the bath temperature is greater than the leads, at low bias voltages (where in the absence of the thermal bath the probability of phonon excitation is low), the thermal bath heats up our MJ and decreases electronic current. On the other hand, at high bias voltages the bath cools down MJ and increases the current. However, if the bath temperature is less than the leads, it always increases the current and the heat flows from the junction to the leads.

Investigation of the Melting Behavior of DNA Three-Way Junctions in the Closed and Open States

Intramolecular three-way junctions are commonly found in both DNA and RNA. These structures are functionally relevant in ribozymes, riboswitches, rRNA, and during replication. In this work, we present a thermodynamic description of the unfolding of DNA intramolecular three-way junctions. We used a combination of spectroscopic and calorimetric techniques to investigate the folding/unfolding thermodynamics of two three-way junctions with a closed (Closed-J) or open (Open-J) junction and their appropriate control stem-loop motifs (GAAATT-Hp, CTATC-Hp, and Dumbbell). The overall results show that both junctions are stable over a wide range of salt concentrations. However, Open-J is more stable due to a higher enthalpy contribution from the formation of a higher number of basepair stacks whereas Closed-J has a defined structure and retains the basepair stacking of all three stems. The comparison of the experimental results of Closed-J and Open-J with those of their component stem-loop motifs allowed us to be more specific about their cooperative unfolding. For instance, Closed-J sacrifices thermal stability of the Dumbbell structure to maintain an overall folded state. At higher salt concentration, the simultaneous unfolding of the above domains is lost, resulting in the unfolding of the three separate stems. In contrast, the junction of Open-J in low salt retains the thermal and enthalpic stability of the Dumbbell structure although sacrificing stability of the CTATC stem. The relative stability of Dumbbell is the primary reason for the higher ΔG°(5), or free energy, value seen for Open-J at low salt. Higher salt not only maintains thermal stability of the Dumbbell structure in Open-J but causes the CTATC stem to fully fold.

Modeling of Unsteady Flow through Junction in Rectangular Channels: Impact of Model Junction in the Downstream Channel Hydrograph

Open channel junctions are encountered in urban water treatment plants, irrigation and drainage canals, and natural river systems. Junctions are very important in municipal sewerage systems and river engineering. Adequate theoretical description of flow through an open channel junction is difficult because numerous variables are to be considered. Equations of junction models are based on mass and momentum or mass and energy conservation. The objective of this study is to compare two junction models for subcritical flows. In channel branches, we solve numerically the Saint-Venant hyperbolic system by combining Preissmann scheme and double sweep method. We validate our results with HEC-RAS using Nash and Sutcliffe efficiency. In junction models, equality of water stage and complete energy conservation equation from HEC-RAS are compared. Outcome of the research clearly indicates that the complete conservation energy model is more suitable in flow through junction than equality of water stage model in serious situations.

Modeling of Graphene Coplanar Waveguide and its Discontinuities for THz Integrated Circuits Applications

Graphene, having extraordinary electronic and optical properties at THz frequencies, can be used in the design and development of miniaturized components, devices, and integrated circuits. Model of graphene-based transmission lines and their discontinuities play a crucial role in the realization of THz integrated circuits, which is not readily available in the literature. This paper reports the characteristics of graphene film deposited over a SiO2/Si wafer. Transmission line characteristics of graphene-based plasmonic coplanar waveguide (GPCPW) on SiO2/Si wafer have been determined from the electromagnetic modeling of the structure. Discontinuities in the GPCPW such as open end, series gap, and step junction have also been analyzed to obtain their lumped element electrical equivalent. Closed-form expressions are developed so that it can be used in the circuit design at later stage. It has been observed that GPCPW transmission lines have very high characteristic impedance values (∼1000–2500 Ω) which are not possible in non-graphene transmission line structures.