bluuebunny/crossref_metadata_2025 huggingface dataset:
HAX1 maintains the glioma progression in hypoxia through promoting mitochondrial fission
Authors: Lin Jinghui , Wang Yang , Lin Zhiqing
Published: November 2021

HCLS1‐associated protein X‐1 (HAX1), an anti‐apoptotic molecular, overexpresses in glioma. However, the role of HAX1 in glioma cell surviving in hypoxic environment remains unclear. Western blotting, qRT‐PCR, Transwell assay, TUNEL assay, wounding healing assay, clone formation, tumour xenograft model and immunohistochemical staining were used to investigate the role of HAX1 in glioma. HAX1 regulated by HIF‐1α was increased in glioma cells cultured in hypoxia. Silencing of HAX1 could cause an increased apoptosis of glioma cells cultured in hypoxia. Silencing of HAX1 also decreased the proliferation, migration and invasion of glioma cells cultured in hypoxia. Increased mitochondrial fission could prevent glioma cells from the damage induced by HAX1 knockdown in hypoxia. Furthermore, HAX1 was found to regulate glioma cells through phosphorylated AKT/Drp signal pathway. In conclusion, our study suggested that HAX1 promoted survival of glioma cells in hypoxic environment via AKT/Drp signal pathway. Our study also provided a potential therapeutic target for glioma.
Mothers susceptible to child maltreatment and requiring public health nurses’ continuous support
Authors: Yoshioka‐Maeda Kyoko , Fujii Hitoshi
Published: November 2021

Objective

This study aimed to identify the characteristics of mothers who are at a high risk for future child maltreatment and therefore, require continuous support from public health nurses (PHNs) to prevent child maltreatment and those who do not require it.

Design and samples

This retrospective cross‐sectional study included women who were registered in 2018 for being at risk for future child maltreatment and required help with childrearing in City A within the Tokyo metropolis.

Measurements

Public health nurses registered data pertaining to each mother, including demographic data, family‐related variables, assessment by PHNs, use of maternal and child healthcare services, and continuity of support from PHNs.

Results

Of the 206 cases, the discontinued group—comprising those who no longer needed PHNs’ support—included 83 cases (40.3%) and the continuing group—comprising those needed continuing support—included 123 cases (59.7%). Logistic regression analysis showed that those with marital conflicts, maternal mental instability, lack of parenting skills, and not moving out of the city were more likely to require continuous PHNs’ support.

Conclusions

By identifying these factors, PHNs can identify new mothers who need continuous support and provide more concentrated care for them. Thus, support from PHNs can help prevent child maltreatment.
Using Weather and Schedule Based Pattern Matching and Feature Based Principal Component Analysis for Whole Building Fault Detection—Part II Field Evaluation
Authors: Chen Yimin , Wen Jin , Lo James
Published: November 2021

In a heating, ventilation, and air conditioning (HVAC) system, a whole building fault (WBF) refers to a fault that occurs in one component but may trigger additional faults/abnormalities on different components or subsystems resulting in significant impacts on the energy consumption or indoor air quality in buildings. At the whole building level, interval data collected from various components/subsystems can be used to detect WBFs. In the Part I of this study, a novel data-driven method which includes weather and schedule-based pattern matching (WPM) procedure and a feature based principal component analysis (FPCA) procedure was developed to detect the WBF. This article is the second of a two-part study of the development of the whole building fault detection method. In the Part II of the study (this paper), various WBFs were designed and imposed in the HVAC system of a campus building. Data from both imposed fault and naturally occurred faults were collected through the building automation system (BAS) to evaluate the developed fault detection method. Evaluation results show that the developed WPM-FPCA method reaches a satisfactory detection rate (85% and 100% under two principal component retention rates) and a 0% false alarm rate (under two principal component retention rates).
Modeling Intersonic Crack Propagation in Fiber Reinforced Composites With Contact/Cohesive Laws
Authors: Dwivedi S. K. , Espinosa H. D.
Published: November 2021

Dynamic crack propagation in an unidirectional Carbon/Epoxy composite is studied through finite element analyses in total Lagrangian co-ordinates. A finite deformation anisotropic visco-plastic model is used to describe the constitutive response of the composite. Crack initiation and propagation is simulated by embedding zero thickness interface element along the possible crack path. An irreversible cohesive law is used to describe the evolution of normal and shear tractions as a function of displacement jumps. The compressive response prior to interface failure is analyzed using contact impenetrability conditions. The failure of the first interface element at the pre-notch tip models crack initiation. Crack propagation is modeled through consecutive failure of interface elements. Dynamic crack propagation phenomena are studied in terms of crack initiation time, crack speed, mode I and mode II displacement jumps and tractions associated with the failure of interface elements, effective plastic strain at the crack tip and path independent integral J′. Analyses are first carried out for the dynamic crack propagation along bi-material interfaces. The results obtained from present analyses agree well with literature data. Detailed analyses are carried out for a pre-notched unidirectional Carbon/Epoxy composite material. The impact velocity in the analyses is an imposed velocity over an assumed impact region and remains constant throughout the analysis. Analyses are carried out at impact velocities of 5, 10, 20, 30 and 40 m/s, assuming the crack wake is frictionless. Moreover, analyses at impact velocities of 30 and 40 m/s are also carried out with a friction coefficient of 0.5 along the crack surfaces. The analyses established intersonic crack speed in the fiber reinforced composite material. Intersonic crack propagation for the impact velocities of 40 m/s is 400% of the shear wave speed and 87% of the longitudinal wave speed. Detailed discussion is given on the features of sub-sonic and intersonic crack propagation in Carbon/Epoxy composite materials. It is shown that the friction coefficient along the crack surface plays an important role by smearing the discontinuous field that develops behind the crack tip and by reducing crack speed in the intersonic regime. The analyses show that the contour integral J′ computed at near field contours are path independent and can serve as a parameter for characterizing intersonic crack propagation.
Crush of High Density Aluminum Honeycombs
Authors: Lu Wei-Yang , Hinnerichs Terry
Published: November 2021

The orthotropic crush model has commonly been used to describe the stress-strain behavior of honeycomb. Important model parameters include crush strength and crush efficiency of each principal direction. Experiments were conducted to obtain these model parameters of high-density honeycombs. Various deformation modes were observed during “bare” compression tests. The normal crush mode of honeycomb is progressive plastic buckling. Low energy absorption (or abnormal) modes include transverse splitting and global buckling. To obtain a consistent normal mode of deformation under wide testing conditions, a confined compression test was developed. A series of confined compressions on T-, L-, and W-directions were performed to get crush parameters for the orthotropic crush model. The temperature dependence and loading rate effects on crush parameters were also obtained.
Conducting Dynamic Impact Tests Using a “Free-Flight” Drop Tower Facility: Part II — Practical Aspects
Authors: Johnson Nancy L. , Browne Alan L.
Published: November 2021

“Free-Flight” drop tower facilities are commonly used to study the dynamic impact response and energy absorption capabilities of a wide range of test specimens including automotive components and structural elements. The information they provide, if tests are conducted properly, is useful both for validating analytical predictions of dynamic crush and for determining the dynamic crush response itself in those cases where analytical prediction capability does not exist. This paper covers practical aspects of conducting impact tests using such facilities that are critical to the success and usefulness of such tests. Specific topics that are discussed include the categories of impact studies for which drop towers are best suited and guidelines for selecting the test conditions including specimen size, drop height/impact velocity, drop mass, height of arresting stops, and methods of crush initiation. Also included are guidelines for mounting test specimens, a discussion of good test practices for minimizing transducer resonances, and hints for conducting tests with asymmetric and/or net lateral loads including non-axial impacts.
Design of a Wireless Sensor for Injection Molding Cavity Pressure Measurement
Authors: Zhang Li , Theurer Charles B. , Gao Robert X. , Kazmer David O.
Published: November 2021

The concept of a wireless sensor for injection molding machine cavity pressure measurement is proposed. The pressure information inside the cavity can be sensed by means of a series of ultrasonic pulses. The current pressure is obtained simply multiplying the number of pulses with a preset threshold value. Instead of using any external power supply, the sensor is self-powered by a piezoelectric stack that extracts energy from the melt pressure changes and converts it into electrical energy. Theoretical background of ultrasonic pulses and micromechanical switches are introduced, in view of their applications in the proposed design. Preliminary experiments have shown that pressure change of 20 MPa within 1 μs could be detected wirelessly by a single ultrasonic pulse. Further work will be done to validate the proposed design.
Nonlinear Model Reduction for Automotive System Descriptions
Authors: Liu Zeyu , Wagner John
Published: November 2021

The mathematical modeling of dynamic systems is an important task in the design, analysis, and implementation of advanced automotive control systems. Although most vehicle control algorithms tend to use model-free calibration architectures, a need exists to migrate to model-based control algorithms which offer greater operating performance. However, in many instances, the analytical descriptions are too complex for real-time powertrain and chassis model-based control algorithms. Therefore, model reduction strategies may be applied to transform the original model into a simplified lower-order form while preserving the dynamic characteristics of the original high-order system. In this paper, an empirical gramian balanced nonlinear model reduction strategy is examined for the simplification process of dynamic system descriptions. The empirical gramians may be computed using either experimental or simulation data. These gramians are then balanced and unimportant system dynamics truncated. For comparison purposes, a Taylor Series linearization will also be introduced to linearize the original nonlinear system about an equilibrium operating point and then a balanced realization linear reduction strategy will be applied. To demonstrate the functionality of each model reduction strategy, two nonlinear dynamic system models are investigated and respective transient performances compared.
Component Power Sizing and Limits of Operation for Proton Exchange Membrane (PEM) Fuel Cell/Battery Hybrid Automotive Applications
Authors: Boettner Daisie D. , Paganelli Gino , Guezennec Yann G. , Rizzoni Giorgio , Moran Michael J.
Published: November 2021

This paper describes use of a Proton Exchange Membrane (PEM) fuel cell system model for automotive applications in a fuel cell system/battery hybrid configuration. The fuel cell system model has been integrated into a vehicle performance simulator that determines fuel economy and allows consideration of control strategies. The simulator is used to explore relevant regions of the fuel cell-powered hybrid electric vehicle design space by conducting simulations using two simple supervisory-control strategies: thermostatic control and proportional control. During the simulations power provided by the battery and fuel cell system and operational limits on battery state of charge and fuel cell system current density are varied while maintaining minimum component sizing to meet vehicle performance criteria. Analysis of results from these simulations provides component power sizing and limits of operation suitable for development of a more advanced supervisory vehicle control strategy for a fuel cell vehicle.
A Hardware-in-the-Loop Transient Diesel Engine Test System for Control and Diagnostic Development
Authors: Tartt C. Jason , Moskwa John J.
Published: November 2021

This paper describes the design and capabilities of a state-of-the-art diesel engine transient test system, which has been developed and built in the Powertrain Control Research Laboratory (PCRL) at the University of Wisconsin - Madison. The system includes a hydrostatic transient dynamometer capable of approximately 300 Hz actuation bandwidth, which is integrated with a dynamic vehicle drivetrain model that runs in real time. This hardware-in-the-loop (HIL) system simulates dynamic torque loading on the engine while performing an FTP, NEDC, J10.15, or any other drive cycles. The dynamometer system is complemented with transient emissions instrumentation to evaluate the state and composition of engine feed gases, and pre and post catalytic converter gases. Included in this paper are details of the design philosophy, why a hydrostatic design was used, specifics on the hardware of the system, as well as experimental data from the system.
A Scalable Approach for Energy Converter Modeling and Supervisory Control Design
Authors: Wei Xi , Rizzoni Giorgio
Published: November 2021

Increasing demand for hybrid electric vehicle designs requires automated modeling and simulation tools to construct a design space search. Composability and scalability are highly desirable in these simulators to provide design candidates. To achieve effective and efficient automation of the design space search, a scaling approach with moderate complexity and consideration of component nonlinear characteristics is necessary in sizing powertrain components, especially energy converters. The Willans line approach proposed in this paper provides models that are sufficiently accurate but not excessively complicated and permits the derivation of a scalable supervisory control algorithm for overall energy consumption minimization. The scalable models and the control strategy can be adapted to various vehicle drivetrain configurations, providing a scalable and composable simulation tool for vehicle powertrain rapid designing. Scaling results of the Willans line approach are compared with real data and another scaling method in a “forward”, quasi-static simulator.
On the Nonlinear Modeling and Identification of Piezoelectric Inertial Actuators
Authors: Knowles David W. , Jalili Nader , Khan Taufiquar
Published: November 2021

Active counter-force vibration control has significant advantages over the more traditional motion-based active vibration suppression schemes. A piezoelectric ceramic (PZT) inertial actuator is an efficient and inexpensive solution for this type of structural vibration control. In order to properly tune the control parameters of the absorber subsection, an accurate mathematical model is necessary. For this, a nonlinear model for the PZT inertial actuators is presented. In particular, a polynomial form of non-linearity in the dynamical model of the actuator is assumed. An inverse problem is then formed to identify the model parameters of the actuator (absorber). The model parameters consist of the effective mass, damping and stiffness of the actuator as well as the polynomial form of the non-linearity. Using Lyapunov’s second method, the stability conditions for the proposed nonlinear model are established. An experimental setup is developed to validate the proposed nonlinear model. The results of the model identification using the actual experimental data demonstrate that the nonlinear model would better fit the experimental data, when compared to the linear model.
Jerk Limited Time Optimal Control of Flexible Structures
Authors: Muenchhof Marco , Singh Tarunraj
Published: November 2021

This paper deals with the design of jerk-limited time-optimal control sequences for rest-to-rest maneuvers of flexible structures. The resulting jerk profiles will be either bang-bang or bang-off-bang. To ensure quiescent states at the end of the maneuver, a pole cancellation technique will be used. Further constraints account for the geometric boundary conditions. This paper will also investigate the development of the control profile upon variation of the maximum allowable amount of jerk. The last section presents numerical results. The proposed control algorithm is implemented for the Floating Oscillator benchmark problem.
Nonlinear Model Based Coordinated Adaptive Robust Control of Electro-Hydraulic Robotic Manipulators: Methods and Comparative Studies
Authors: Bu Fanping , Yao Bin
Published: November 2021

Compared to conventional robot manipulators driven by electrical motors, hydraulic robot arms have richer nonlinear dynamics and stronger couplings among various joints (or hydraulic cylinders). This paper focuses on the physical model based coordinated adaptive robust control (ARC) strategies that explicitly take into account the strong coupling among various hydraulic cylinders (or joints). In our recent studies, two such methods were proposed to avoid the need of acceleration feedback in doing ARC backstepping designs. The first method uses an observer to recover the state needed for the ARC backstepping design. The second method utilizes the property that the adjoint matrix and the determinant of the inertial matrix can be linearly parametrized by certain suitably selected parameters and employ certain over-parametrizing techniques. Theoretically, both the resulting ARC controllers guarantee a prescribed output tracking transient performance and final tracking accuracy while achieving asymptotic output tracking in the presence of parametric uncertainties only. This paper focuses on the comparative studies of these two methods under various practical constraints. Extensive simulation results which are based on a three degree-of-freedom (DOF) hydraulic robot arm are presented to illustrate the advantages and drawbacks of each method.
Real Time, Near-Optimal Trajectory Planning of an Omni-Directional Vehicle
Authors: Kalmár-Nagy Tamás , Ganguly Pritam , D’Andrea Raffaello
Published: November 2021

In this paper, we discuss an innovative method of generating near-optimal trajectories for a robot with omni-directional drive capabilities, taking into account the dynamics of the actuators and the system. The relaxation of optimality results in immense computational savings, critical in dynamic environments. In particular, a decoupling strategy for each of the three degrees of freedom of the vehicle is presented, along with a method for coordinating the degrees of freedom. A nearly optimal trajectory for the vehicle can typically be calculated in less than 1000 floating point operations, which makes it attractive for real-time control in dynamic and uncertain environments.
Compliant Wafer Level Package
Authors: Patel Chirag , Martin Kevin P. , Meindl James D.
Published: November 2021

A high I/O density and high performance wafer level packaging technology called the Compliant Wafer Level Package (CWLP) is reported. The necessity for compliant interconnects in upcoming generations of electronic products is discussed by analyzing the technology requirements projected by the International Technology Roadmap for Semiconductors (ITRS). To be a true wafer level package, the technology should have following three characteristics11: I) package all Integrated Circuits (ICs) intact on wafer at once, II) perform wafer level test and burn-in, and III) assemble the WLP on the system board without using an underfill. Compliant interconnects are essential to accomplishing wafer level test and assembly without underfill. These topics are discussed in the paper followed by fabrication and performance analysis of the CWLP technology.
Corrosion Analysis of a Fiber-Optic Transceiver Housing
Authors: Lau J. H. , Jiaa C. L. , Erasmus S. J.
Published: November 2021

The corrosion responses of a fiber-optic transceiver’s housing with zinc alloy die casting material are investigated in this study. Emphasis is placed on the determination of the weight change and corrosion rate of the housing when it is subjected to a 85% relative humidity and 85°C temperature (85%RH/85°C) test condition. Also, the average light optical power, receiver sensitivity, extinction ratio, and mask margin of transceiver modules subjected to 85%RH/85°C and 3.47V at 500, 1000, 1500, and 1600 hours are provided. Furthermore, metallography is performed on the surfaces and cross sections of the housing. Finally, measurements are made of the thickness of the oxide layer on the surfaces of the fiber-optic transceiver housing.
Numerical Simulations of Fluid Flow During Electromagnetic Stirring of Metals
Authors: Teodorescu Sorin G. , Dupac Mihai , Bakhtiyarov Sayavur I. , Overfelt Ruel A.
Published: November 2021

In this paper we propose a new relationship between the opposing mechanical torque and the electric conductivity of a rotating liquid specimen in a permanent external magnetic field of constant induction. It is shown that the proposed relationship describes the experimental data for a rotating specimen better than Braunbeck formula derived under the assumption that a magnetic field rotates around a stationary metal sample.
Efficient Replacement of Centrifugal With Absorption Chillers Upgrading the Heat Transfer of the Cooling Tower
Authors: Rogdakis E. D. , Papaefthimiou V. D.
Published: November 2021

It is a general trend today, the old centrifugal machines to be replaced by new absorption machines. The mass flow rate of the cooling water in the centrifugal machines is normally 30% less than that in the two-stage absorption chiller for the same refrigerating capacity. Some absorption chillers manufacturers have updated and improved the double-effect technology increasing the cooling water temperature difference from the typical value of 5.5°C to 7.4°C and reducing the cooling water flow rate by about 30%.

Using such a modern double effect absorption unit to replace a centrifugal chiller the same cooling water circuit can be used and the total cost of the retrofit is minimized. In this case a new flow pattern of the cooling tower is developed, and in this paper the design of a new tower fill is predicted taking into account the new factors characterizing the operating conditions and the required performance of the tower. As an example, the operational curves of a modified cooling tower (1500 KW cooling power) used by a 240 RT double-effect absorption chiller are presented.
Design of a Micro Direct Methanol Fuel Cell (μDMFC)
Authors: Mench M. M. , Wang Z. H. , Bhatia K. , Wang C. Y.
Published: November 2021

Recently, there has been increased interest in the development of a small-sized direct methanol fuel cell (DMFC) for low-power applications. In this paper, the design of a self-activated DMFC stack is presented. Gravitational and capillary forces feed the anode side liquid methanol solution. On the cathode side, air is supplied by thermal and solutal buoyancy forces. Based upon experimental results for a larger test cell, and calculated flow velocities for the small-cell design, the fuel and oxidizer supply rates should be adequate for acceptable performance. The entire DMFC is therefore a pump-less operation and self-activated by electrochemical reactions. At 1 cm3 total volume, the DMFC is expected to provide a power density around 1 W/cm3, with a range of output of 10V, 0.1A to 1 V, 1A depending on the arrangement of individual cell connections.
A 3-D Model for Magntic Damping of G-Jitter Induced Convection and Solutal Transport in a Simplified Bridgman Configuration
Authors: Handa J. , Zhang X. , Li B. Q. , de Groh H. C.
Published: November 2021

A 3-D transient finite element model is developed to represent the oscillating thermal convection induced in a simplified Bridgman configuration filled with a Ga-doped germanium melt in microgravity under the influence of an external magnetic field. The model development is based on the penalty-finite element solution of the equations describing the transport of momentum, heat and solution and also the electromagnetic field distribution in the melt pool. Automatic time step control is applied to help speed up the calculations. Numerical performance of finite element simulations for this class of problems is discussed. In particular, various types of finite element formulations were studied to minimize the global matrix size and to investigate the computational efficiency. Numerical simulations are conducted to study the convection and magnetic damping effects as a function of frequency, directions and amplitudes of g-jitter and also the direction and magnitudes of the applied magnetic fields. The results show that the g-jitter driven flow is time dependent and complex convection pattern can develop in a 3-D configuration even when the thermal conditions are symmetric and that the convection can be suppressed with an applied magnetic field.
Perspectives in Modelling Film-Cooling of Turbine Blades by Transcending Conventional Two-Equation Turbulence Models
Authors: Azzi A. , Lakehal D.
Published: November 2021

The paper exposes some recent new trends in modelling jets-in-crossflow with relevance to film-cooling of turbine blades. The aim is to compare two classes of turbulence models with respect to their predictive performance in reproducing flow physics. The study focuses on anisotropic eddyviscosity/diffusivity models and explicit algebraic stress models, up to cubic fragments of strain and vorticity tensors. The first class of models are DNS-based two-layer approaches transcending the conventional k–ε model by means of a non-isotropic representation of the turbulent transport coefficients; this is employed in connection with a near-wall one-equation model resolving the semi-viscous sublayer. The aspects of this new strategy are based on known DNS statistics of channel flows and boundary layers. The other class of models are quadratic and cubic explicit algebraic stress formulations rigorously derived from second-moment closures. The stress-strain relations are solved in the context of a two-layer strategy resolving the near-wall region by means of a non-linear one-equation model; the outer core flow is treated by use of the two-equation model. The models are tested for the film cooling of a flat plate, and are then extended to film cooling of a symmetrical turbine blade by a row of laterally injected jets. Comparison of the calculated and measured wall-temperature distributions shows that only the anisotropic eddy viscosity/diffusivity model can correctly predict the spanwise spreading of the temperature field and reduces the strength of the secondary vortices. The non-linear algebraic stress models were of a mixed quality in film cooling calculations.
Removal of Contaminants by Induced Air Flow Inside Structures
Authors: Ziskind G. , Dubovsky V. , Letan R.
Published: November 2021

The present paper discusses the continuous removal of contaminants from enclosed spaces by means of induced air flow. The air flow is caused by natural convection in a heated horizontal or vertical duct. The heating of the duct can be achieved by absorption of solar irradiation or any other means. As a result, a steady air flow can be induced inside the duct and the enclosed space, as has been shown by the authors for a small scale laboratory model.

Three dimensional numerical simulations are performed for various kinds of real-size structures, including one-story detached buildings and underground enclosed spaces. The k-epsilon turbulence model is used in the simulations.

The results yield detailed flow field inside the enclosures at various configurations of the openings. Rate of air change is calculated both for the whole enclosure and for the layers above the floor where the contaminants tend to accumulate. Optimal design of the systems is discussed.
Prediction of Thermal Performance of Flip-Chip-Plastic Ball Grid Array (FC-PBGA) Packages: Effect of Die Size
Authors: Ramakrishna K. , Lee T.-Y.
Published: November 2021

Package level thermal performance of flip-chip plastic ball grid array (FC-PBGA) packages has been predicted using experimentally validated mechanistic methodologies. The resulting conjugate heat transfer models have been solved using methods of computational fluid dynamics under natural and forced convection for freestream velocities up to 2 m/s. Overall junction to ambient, Θja, junction-to-board, Ψjb, and junction to case Ψjτ thermal resistances (here after referred to as thermal parameters) have been derived from the results of these computations. Using these models and methodologies, which are previously validated against experimental data, a parametric study of effect of die size on the package thermal parameters has been carried out for die sizes in the range 2 to 20 mm (area of 4–400 mm2) under natural and forced convection with freestream velocities in the range of 0.5 to 2 m/s. The predictions in this study are expected to be ±10% of the measured data. Based on this work the following conclusions have been drawn:

1. The junction to ambient, Θja, and junction to board, Ψjb, thermal resistances decrease with increase in freestream velocity, U, and junction to case thermal resistance, Ψjτ, increases with U. Ψjb shows a weaker dependence on U than Θja does.

2. For a fixed substrate size, package thermal resistances, Θja and Ψjb, decrease as the die size increases from 2 mm (4 mm2) to 20 mm (400 mm2). However, these resistances reach asymptotic values for die sizes above 50 mm2. The change in these resistances is in the range 20% to 35% and the effect of freestream velocity on the percentage changes is small.

3. An extensive database of experimentally validated FC-PBGA package thermal parameters have been generated for a wide range of die sizes.
Three-Dimensional Flow and Heat Transfer Calculations in Micro-Channel Heat Exchangers
Authors: Saha A. K. , Acharya Sumanta
Published: November 2021

A three-dimensional numerical study has been carried out to analyze the unsteady flow and heat transfer in a micro-channel with an array of periodically mounted square cylinders. The current geometry represents a micro-heat exchanger and has potential applications in the cooling of turbine blades and electronic cooling. The cylinder dimensions are of the order of few microns. The three-dimensional unsteady Navier-Stokes and energy equations are solved using higher order temporal and spatial discretizations. The simulations have been carried out for a range of Reynolds number based on cylinder width (180–600) and a Prandtl number of 6.99. Conjugate heat transfer calculations have been employed to account for the conduction in the solid cylinder and convection in the fluid. The flow is found to become unsteady at a critical Reynolds number that falls between 250 and 400. The flow shows quasi-periodic behavior with multiple frequencies at a Reynolds number of 400. The heat transfer enhancement compared to a plane channel is marginal (1.1–1.4 times) for the steady flow cases whereas it is significant (12–15 times) when the flow is unsteady. The friction factor was found to decrease with Reynolds number in both the steady and unsteady regimes. However, the friction factor increases at the critical Reynolds number where it becomes unsteady in nature.
Effect of Condenser Location and Tubing Length on the Performance of a Compact Two-Phase Thermosyphon
Authors: Yuan Lang , Joshi Yogendra K. , Nakayama Wataru
Published: November 2021

This study investigates the issues involved in the design of compact two-phase thermosyphon systems for high power chip cooling. In such systems, the locations of the evaporator and condenser need to be given a high degree of freedom. The key components used in the experiment are: an evaporator enclosure (20 mm × 20 mm × 20 mm internal volume), a simulated chip (20 mm × 20 mm) with an enhancement structure (10 mm × 10 mm × 6.8 mm) and a cartridge heater embedded in a copper rod (11.9 mm × 11.9 mm cross-section). A dielectric coolant (PF-5060, boiling point 56 °C @ 1 atm) is used as the working fluid. Also included in the loop are a natural convection cooled condenser of dimensions 58 mm × 60 mm × 432 mm and connecting tubing. The relative height between the evaporator and the condenser, the tubing length, and the heat input were systematically varied. In this study, the heat flux ranged from 0 to 40 W/cm2; the pressure within the system ranged from −68.9 kPa to +34.5 kPa; and the relative height of the condenser over the evaporator ranged from 15 cm to 45 cm. These ranges represent actual conditions for electronics applications. Experimental studies show that these parameters affect the evaporator thermal resistance from the chip to the boiling pool, and the overall thermal resistance from the chip to the ambient air in a complex way. However, close examination of the data suggests that there could be an optimum point in the parametric domain.
A regulatory T cell signature distinguishes the immune landscape of COVID-19 patients from those with other respiratory infections
Authors: Vick Sarah C. , Frutoso Marie , Mair Florian , Konecny Andrew J. , Greene Evan , Wolf Caitlin R. , Logue Jennifer K. , Franko Nicholas M. , Boonyaratanakornkit Jim , Gottardo Raphael , Schiffer Joshua T. , Chu Helen Y. , Prlic Martin , Lund Jennifer M.
Published: November 2021

Unique circulating regulatory T cell phenotypes distinguish hospitalized patients with SARS-CoV-2.
Rapid mosaic brain evolution under artificial selection for relative telencephalon size in the guppy (
Poecilia reticulata
)
Authors: Fong Stephanie , Rogell Björn , Amcoff Mirjam , Kotrschal Alexander , van der Bijl Wouter , Buechel Séverine D. , Kolm Niclas
Published: November 2021

Experimental evidence shows that mosaic evolution can drive brain morphology variation and potentially cognitive evolution.
Frizzled BRET sensors based on bioorthogonal labeling of unnatural amino acids reveal WNT-induced dynamics of the cysteine-rich domain
Authors: Kowalski-Jahn Maria , Schihada Hannes , Turku Ainoleena , Huber Thomas , Sakmar Thomas P. , Schulte Gunnar
Published: November 2021

WNTs induce conformational changes in the extracellular CRD of Frizzleds irrespective of their signaling profile.
Selective targeting of NaV1.7 via inhibition of the CRMP2-Ubc9 interaction reduces pain in rodents
Authors: Cai Song , Moutal Aubin , Yu Jie , Chew Lindsey A. , Isensee Jörg , Chawla Reena , Gomez Kimberly , Luo Shizhen , Zhou Yuan , Chefdeville Aude , Madura Cynthia , Perez-Miller Samantha , Bellampalli Shreya Sai , Dorame Angie , Scott David D. , François-Moutal Liberty , Shan Zhiming , Woodward Taylor , Gokhale Vijay , Hohmann Andrea G. , Vanderah Todd W. , Patek Marcel , Khanna May , Hucho Tim , Khanna Rajesh
Published: November 2021

Protein-protein interaction inhibitor of the sodium NaV1.7 channel has analgesic effects in preclinical models of pain.
Diguanylate Cyclase and Phosphodiesterase Interact To Maintain the Specificity of Cyclic di-GMP Signaling in the Regulation of Antibiotic Synthesis in Lysobacter enzymogenes
Authors: Xu Gaoge , Zhou Lichuan , Qian Guoliang , Liu Fengquan
Published: November 2021

Cyclic dimeric GMP (c-di-GMP) is a universal second messenger in bacteria. The signaling of c-di-GMP is complex and dynamic, and it is mediated by a large number of components, including c-di-GMP synthases (diguanylate cyclases [DGCs]), c-di-GMP-degrading enzymes (phosphodiesterases [PDEs]), and c-di-GMP effectors.
Alternative Splicing Landscape of Small Brown Planthopper and Different Response of JNK2 Isoforms to Rice Stripe Virus Infection
Authors: Tong Lu , Chen Xiaofang , Wang Wei , Xiao Yan , Yu Jinting , Lu Hong , Cui Feng
Published: November 2021

Alternative splicing (AS) is a regulatory mechanism that occurs after gene transcription. AS events can enrich protein diversity to promote the reactions of the organisms to various endogenous and exogenous stimulations.
The Peptidyl Transferase Center: a Window to the Past
Authors: Tirumalai Madhan R. , Rivas Mario , Tran Quyen , Fox George E.
Published: November 2021

In his 2001 article, “Translation: in retrospect and prospect,” the late Carl Woese made a prescient observation that there was a need for the then-current view of translation to be “reformulated to become an all-embracing perspective about which 21st century Biology can develop” (RNA 7:1055–1067, 2001,
https://doi.org/10.1017/s1355838201010615
). The quest to decipher the origins of life and the road to the genetic code are both inextricably linked with the history of the ribosome. After over 60 years of research, significant progress in our understanding of how ribosomes work has been made.
Prospective Study of the Performance of Parent-Collected Nasal and Saliva Swab Samples, Compared with Nurse-Collected Swab Samples, for the Molecular Detection of Respiratory Microorganisms
Authors: Woodall Claire A. , Thornton Hannah V. , Anderson Emma C. , Ingle Suzanne M. , Muir Peter , Vipond Barry , Longhurst Denise , Leeming John P. , Beck Charles R. , Hay Alastair D.
Published: November 2021

RTIs are ubiquitous among children. Diagnosis involves a swab sample being taken by a health professional, which places a considerable burden on community health care systems, given the number of cases involved.
In Vitro
Evolution of Cefiderocol Resistance in an NDM-Producing Klebsiella pneumoniae Due to Functional Loss of CirA
Authors: McElheny Christi L. , Fowler Erin L. , Iovleva Alina , Shields Ryan K. , Doi Yohei
Published: November 2021

Cefiderocol, a newly approved cephalosporin agent with an extensive spectrum of activity against Gram-negative bacteria, binds siderophore and uses its receptors to access the bacterial periplasm. Loss of functional CirA, an iron transporter, has been associated with cefiderocol resistance.
Supplemental Material: Could the Réunion plume have thinned the Indian craton?
Authors: Paul Jyotirmoy , Ghosh Attreyee
Published: November 2021

Supplemental Figures S1–S5 and Videos S1–S4.
Can the ‘Learn in peace, educate without violence’ intervention in Cote d’Ivoire reduce teacher violence? Development of a theory of change and formative evaluation results
Authors: Devries Karen , Balliet Manuela , Thornhill Kerrie , Knight Louise , Procureur Fanny , N’Djoré Yah Ariane Bernadette , N’Guessan Dedou Gruzshca Ferrand , Merrill Katherine G , Dally Mustapha , Allen Elizabeth , Hossain Mazeda , Cislaghi Beniamino , Tanton Clare , Quintero Lucia
Published: November 2021

Objectives

To gather evidence on whether a brief intervention (Apprendre en paix et éduquer sans violence, developed by the Ivorian Ministry of Education and Graines de Paix) to promote peace in primary schools by reducing teacher violence perpetration and improving pedagogical techniques was acceptable to teachers and affected change in intermediate outcomes.

Design

Mixed-methods formative research.

Setting

Primary schools in Tonkpi region, Cote d’Ivoire.

Participants

160 teachers participating in the peace training, surveyed three times during implementation; qualitative in-depth interviews with 19 teachers and teacher-counsellors.

Interventions

Learn in peace, educate without violence–a brief intervention with primary school teachers designed to promote peace in primary schools.

Outcomes

For survey data, we generated composite measures of intermediate outcomes (teachers’ awareness of consequences of violence, self-efficacy in applying positive classroom management methods, acceptance of physical discipline practices in school) and used random intercept linear mixed-effects models to compare responses over time. Qualitative research included open-ended questions about acceptability and perceived need for such an intervention. A framework analysis was undertaken.

Results

Four-months post-training (vs pretraining), teachers had higher self-efficacy in applying positive classroom management methods (pre-mean=26.1; post-mean=27.5; p<0.001) and borderline lower acceptance of physical discipline practices (premean=4.2; postmean=3.6; p=0.10). We found no change in teacher awareness of the consequences of violence. Qualitatively, teachers found the intervention acceptable and understandable, perceiving it as useful because it provided methods for non-violent discipline. Teachers had mixed views about whether the techniques improved classroom dynamics.

Conclusions

Data suggest that the intervention is acceptable and leads to change in intermediate outcomes for teachers. Further evaluation in a randomised controlled trial is warranted.
Association between surgeon grade and implant survival following hip and knee replacement: a systematic review and meta-analysis
Authors: Fowler Timothy J , Aquilina Alex L , Blom Ashley W , Sayers Adrian , Whitehouse Michael R
Published: November 2021

Objective

To investigate the association between surgeon grade (trainee vs consultant) and implant survival following primary hip and knee replacement.

Design

A systematic review and meta-analysis of observational studies.

Data sources

MEDLINE and Embase from inception to 6 October 2021.

Setting

Units performing primary hip and/or knee replacements since 1990.

Participants

Adult patients undergoing either a primary hip or knee replacement, predominantly for osteoarthritis.

Intervention

Whether the surgeon recorded as performing the procedure was a trainee or not.

Primary and secondary outcome measures

The primary outcome was net implant survival reported as a Kaplan-Meier survival estimate. The secondary outcome was crude revision rate. Both outcomes were reported according to surgeon grade.

Results

Nine cohort studies capturing 4066 total hip replacements (THRs), 936 total knee replacements (TKRs) and 1357 unicompartmental knee replacements (UKRs) were included (5 THR studies, 2 TKR studies and 2 UKR studies). The pooled net implant survival estimates for THRs at 5 years were 97.9% (95% CI 96.6% to 99.2%) for trainees and 98.1% (95% CI 97.1% to 99.2%) for consultants. The relative risk of revision of THRs at 5 and 10 years was 0.88 (95% CI 0.46 to 1.70) and 0.68 (95% CI 0.37 to 1.26), respectively. For TKRs, the net implant survival estimates at 10 years were 96.2% (95% CI 94.0% to 98.4%) for trainees and 95.1% (95% CI 93.0% to 97.2%) for consultants. We report a narrative summary of UKR outcomes.

Conclusions

There is no strong evidence in the existing literature that trainee surgeons have worse outcomes compared with consultants, in terms of the net survival or crude revision rate of hip and knee replacements at 5–10 years follow-up. These findings are limited by the quality of the existing published data and are applicable to countries with established orthopaedic training programmes.

PROSPERO registration number

CRD42019150494.
Use of inhalational anaesthetic agents in paediatric and adult patients for status asthmaticus, status epilepticus and difficult sedation scenarios: a protocol for a systematic review
Authors: Gorsky Kevin , Cuninghame Sean , Chen Jennifer , Jayaraj Kesikan , Withington Davinia , Francoeur Conall , Slessarev Marat , Jerath Angela
Published: November 2021

Introduction

Inhaled volatile anaesthetics have a long tradition of use as hypnotic agents in operating rooms and are gaining traction as sedatives in intensive care units (ICUs). However, uptake is impeded by low familiarity with volatiles, unique equipment and education needs. Inhaled anaesthetics are often reserved in ICUs as therapies for refractory and life threatening status asthmaticus, status epilepticus, high and difficult sedation need scenarios given they possess unique pharmacological properties to manage these medical conditions while providing sedation to acutely ill patients. The objective of this systematic review is to collate evidence regarding the efficacy, safety and feasibility of volatile anaesthetics in adult and paediatric ICU patients for these three emergency conditions.

Methods and analysis

We will conduct a systematic review of the primary studies in adult and paediatric ICU patients with status asthmaticus, status epilepticus and high/difficult sedation needs. We will include observational and interventional studies published from 1970 to 2021 in English or French investigating patients who have received a volatile inhalational agent for the above indications. We will evaluate the efficacy, safety, feasibility and implementation barriers for the volatile anaesthetics for each of three specified indications. Included studies will not be limited by necessity of a comparator arm. We will also evaluate clinical characteristics, patient demographics and provider attitudes towards volatile anaesthetic administration in defined critical care scenarios. Data will be extracted and analysed across these domains. The databases MEDLINE, EMBASE, the Science Citation Index as well as the Cochrane Central Controlled Trials Register will be queried with our search strategy.

Descriptive and statistical analysis will be employed where appropriate. Data extraction and quality assessment will be performed in duplicate using a standardised tool. A narrative approach and statistical analyses will be used to describe patient characteristics, volatile efficacy, safety concerns, technical administration, attitudes towards administration and other implementation barriers.

Ethics and dissemination

No ethics board approval will be necessary for this systematic review. This research is independently funded. Results will be disseminated in a peer-reviewed journal and conference presentation.

PROSPERO number

CRD42021233083.