bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanical and Piezoresistive Properties of Fibre Reinforced Concrete Pavement
Authors: Kadhim Ayad , Al-Dahawi Ali Majeed , Banyhussan Qais Sahib
Published: March 2021

Multifunctional Cementitious Composite (MCC) characteristics are directly related to the type and dosage of the Electrically Conductive Materials (ECMs) reinforcing the relevant concrete matrices. This study investigated the electro-mechanical capacities of concrete pavement (FRCP) with and without the addition of micro scale-carbon fibre (CF12). The mechanical and self-sensing responses of RFCP under indirect tension stress were evaluated initially; then, the effects of 0.5% and 1% content by volume of CF12 on the piezoresistivity capacities of FRCP under compressive load. These types of loads are the most common forces acting to continuously deteriorate rigid pavement. The test findings showed that adding CF12 improved the conductivity and reduced the resistivity of the concrete mixture and reduced polarisation time to on the order of zero seconds. Under indirect tension, however, the use of 1% by volume macro end hook steel fibre (S) resulted in a decrease in electrical resistivity, which was opposite to the expected change, and which suggested that a conductive network built from steel fibre cannot detect changes due to applied loads correctly. However, the CF-reinforced concrete pavement with 1% content by volume succeeded in identifying electrical resistivity changes. Moreover, the developed FRCP showed good results in terms of self-sensing under compression loads with both 0.5 and 1.0% by volume of CF. The results also showed that the use of a hybrid fibre (CF12 0.5% and S 1% by volume) enhanced the indirect tensile strength and compression strength due to CF12’s resistance to micro-cracks.
Experimental Study on the Behaviours of Post-tensioned Concrete Members with Unbonded Tendons
Authors: Peera Iqbal , Oukaili Nazar
Published: March 2021

This paper presents experimental results regarding the behaviours of eight simply supported partially prestressed concrete beams with internally unbonded tendons, focusing particularly on the effect of three different variables: concrete compressive strength, fc
′; jacking stress, fj
; and the prestressing index, ω. Increasing the concrete compressive strength from 35 MPa to 60 MPa was seen to lead to an increase in load-carrying capacity by about 10%. The load capacity was also affected, though to a lesser extent, by the jacking stress. The failure load of partially prestressed concrete beams with internally unbonded strands was increased by about 2.5%, to 10%, when the jacking stress increased from 0.5 to 0.7 of the strand’s ultimate strength, fpu
. The test results showed that the prestressing index was the most influential parameter among the examined variables. The experimental results of the stress increase in unbonded strands at failure and the ultimate load resistance of members were also compared to the analytical results of various standards and research methodologies for verification.
Behaviours of Ring and Circular Footings Subjected to Eccentric Loading: a comparative Study
Authors: Kadhum Mohammed Qassim , Albusoda Bushra Suhale
Published: March 2021

This study experimentally examined the behaviours of ring and circular footings resting on loose sand overlying dense sand based on the application of eccentric loads with eccentricity values of 0, 4, 8, and 16 mm. Many researchers have examined the effects of concentrated loads on ring footings numerically; however, few studies have taken into account the effect of eccentric loads on ring footings on loose and dense sand, and even fewer have done so experimentally. This paper thus presents the experimental work done to understand and make comparisons between circular and ring footings under such circumstances. The results of the tests indicate that there is a significant increase in the bearing capacity and a decrease in the settlement of ring footings in comparison with circular footings under the same conditions. Further, ring footings offer approximately the same behaviours as circular footings with respect to eccentric loads. These results indicate that the use of ring footings rather than circular footing can provide improved structural performance at low cost.
Responses of buried steel pipes under footing loadings – a numerical parametric study
Authors: Al-Naddaf Mahdi , Rasheed Sajjad Emad , Sharefi Mohammed Q. , Mustapha Rahmaninezhad S. , Jie Han P.E.
Published: March 2021

Buried pipes are among the most important urban facilities due to their use in multiple key applications such as drainage, sewerage, oil lines, electrical conduits, and culverts. The performance of such infrastructure under different loading conditions relies highly on their design, yet adequate design cannot be achieved unless their actual behaviours are well understood. This paper thus uses numerical analyses to investigate the response in terms of vertical stresses of buried steel pipes under monotonic static footing loads. Based on a reduced-scale physical test constructed in a test box under plane-strain conditions, a finite element model was built and verified using Plaxis3D software, and a parametric study to investigate the effects of footing width and loading condition, and pipe location or embedment ratio was then conducted. The results of the numerical analyses showed that the Hardening Soil (HS) model depicted the response of the backfill material adequately. The numerical analysis results also showed that increasing embedment depth decreased the pressure on the pipe, while increasing the footing width increased the pressure on the pipe when the embankment height was twice the pipe diameter. A critical footing width of 1B was identified that was responsible for the highest pressure on the pipe when the embankment height was equal to the pipe diameter (H/D = 1). When H/D = 1, the localised footing loading condition is thus critical due to the higher vertical stresses on the pipe than seen under uniform loading.
The impact of using pure ethanol additives on gasoline fuel with respect to SI engine emissions
Authors: Kurji H J , Imran M S , Bded A S
Published: March 2021

A major problem in the gasoline engine operation process under heavy-duty conditions is the knocking phenomenon, noises produced in the combustion chamber during the combustion procedure as a consequence of the pre-ignition process. These occur effect of the high temperature of the air, which causes fuel to ignite without additional activation energy (spark). The octane number for gasoline fuel measures the resistance of the fuel to such auto-ignition. Experimental work was done in this study to study the influence of adding pure ethanol to conventional Iraqi gasoline fuel at percentages varying from 10% to 90% in 10% increments by volume, with various fuel properties like density, octane number, viscosity, fuel vapour pressure, and flash point temperature, measured and compared. Ethanol additives were found to increase fuel density, flash point temperature, viscosity, and octane number while reducing fuel vapour pressure. The engine utilised in the trials was a single-cylinder, gasoline engine, naturally aspirated and air-cooled. The experimental outcomes for specific fuel consumption showed decreases of up to 29% at the 90% volumetric percentage of ethanol in conventional gasoline fuel, and emissions of engine NOX, CO, and HC decreased by 67. 7%, 69%, and 61%, respectively, However, CO2 emissions increased.
Analysis of fluid flow states in viscometers in ansys software
Authors: Azziz H N , Hussein E Q , Abdulhameed M A
Published: March 2021

Viscometers have multiple major applications in various areas of engineering, as the fluid flow is inherently connected to the properties of fluid viscosity. This paper substantively examines the fluid flow state over a capillary viscometer to examine the stability of such flow under the effects of various geometries (variations in tube length and cylinder base shape) of capillary viscometer, using a simulation model improved by means of the application of finite element software in Ansys 16 to depict the flow in the capillary viscometer. In this work, experimental measures were utilised and implemented to evaluate various fluid properties and to observe the effects of the geometrical shapes of the viscometer on the flow properties (pressure, velocity, and temperature) and the effect of fluid type on the vortex and fluid circulation during flow.
Control analysis and simulation of multi-body systems using full state controllers
Authors: Ali H A
Published: March 2021

This paper simulates a dynamic model of a multi-body dynamic system with a Linear Flexible Joint cart with a single Inverted Pendulum (LFJ_IVP). The dynamic equation of motion for the nonlinear system was linearised utilising a suitable state space method with full state feedback and full state observer controllers that act as both servos and regulator systems. The results showed a significant improvement as compared with other researchers’ work using other controls, including an improvement in the response of both the cart position (the state output of the plant), which tracked the designed external input signal to within 20%, with similar results for spring deflection, and an improvement in the amount of deflection of the right angle around the vertical position by 37.24%. There was also a marked improvement in electrical energy consumption, by approximately 55.7% based on the application of the full state feedback controller. Comparing these results to those of other controllers, such as a full state observer controller, there was a significant improvement in the consumption of electrical energy of approximately 33%.
A review of the mechanical properties of additively manufactured fiber reinforced composites
Authors: Li J H , Huang X D , Durandet Y , Ruan D
Published: March 2021

Recent developments in additive manufacturing technologies have made it possible to print fiber reinforced composite materials that have reasonable mechanical performance. In this paper, a brief review of the additive manufacturing technologies for composites are presented. The focus is the mechanical properties of both discontinuous and continuous fiber reinforced composites fabricated by state-of-the-art additive manufacturing technologies. The deformation mechanisms are also briefly discussed. In addition, recommendations for future work are made.
Quasi-static three-point bending of metallic sandwich panels
Authors: Xia F , Durandet Y , Ruan D
Published: March 2021

Sandwich panels become ideal candidates in industry applications due to their excellent energy absorption ability and light weight. The cellular core of sandwich panels may experience large plastic deformation at an almost constant stress, thus the panel has excellent energy absorption capability. The current paper examines and compares the mechanical performance of sandwich panels with three types of cores (corrugated, honeycomb and lattice truss) under quasi-static three-point bending. Finite element analysis (FEA) was performed in this study and the numerical models of each panel were developed using ABAQUS to predict the deformation mode and the bending response of panels (i.e. force-displacement curve and energy absorption) under three-point bending. Two deformation modes are predicted for all three types of sandwich panels. The honeycomb sandwich panel is expected to have the best energy absorption ability among the three types of sandwich panels with the same relative density. The outcomes of the present study will thereby provide useful information for their applications in industry.
Numerical study of a re-entrant diamond structure under dynamic compression
Authors: Logakannan K P , Ramachandran V , Rengaswamy J , Ruan D
Published: March 2021

Auxetic materials, due to its negative Poisson’s ratio, shrink laterally when compressed axially and expand laterally when pulled axially. A re-entrant diamond structure was developed by replacing the vertical walls in a conventional re-entrant structure with diamond cells, which featured cross-linking members to make them rigid. The incorporation of the rigid diamond unit cells increased the stiffness, strength, and energy absorption of the structure. A validated finite element (FE) model was adopted from previous work, and the structures were compressed at a speed of 5 m/s in the FE model. The independent geometrical parameters of the re-entrant diamond unit cell were re-entrant wall length (L1
), diamond angle (θ2
), and diamond wall length (L2
). The FE model based on these values was thus used to investigate the influence of geometrical parameters (θ2
& L2/L1
) on the deformation mode, stiffness, strength, and specific energy absorption (SEA) of the structure. The value of diamond angle (θ2
) varied from 40° to 90° at intervals of 10°, while the length ratio (L2/L1
) varied from 0.7 to 1.2 in increments of 0.1. The specific strength was used in the discussion to account for differences in the relative density of re-entrant diamond structures.
Investigation on mechanical properties of graphene-polyurethane nanocomposites
Authors: Abbas S A , Younas T , Asadullah  , Anwar M A
Published: March 2021

Polymer nanocomposites are increasingly used in applications because of their improved mechanical properties compared to traditional polymers. Graphene has attracted considerable attraction as a reinforcing material in polymers in recent years due its extraordinary effect on enhancing mechanical properties of polyurethane. This paper presents the development and characterisation of mechanical properties of graphene based polyurethane nanocomposites. The yield of the graphene nano material was carried out by using the technique called liquid exfoliation as the use of N-Methyl-2-Pyrollidone (NMP) and Tetrahydrofuran (THF) solvent. Granules polyurethane was converted into blend polyurethane by heating at 100°C and then graphene nano particles were fused with pure polyurethane matrix with different percentage weight of graphene (0, 0.1, 0.3, 0.5 and 0.7 wt.%). Microstructural and Mechanical characterisation of graphene/polyurethane nano-composite matrix were carried out involving Atomic Force Microscopy (AFM), X-Rays Diffraction (XRD) and Universal Testing Machine (UTM) and results were compared with pure polyurethane. The results have shown drastic improvements in mechanical properties with modulus of elasticity increasing by 320% and elongation at breaking point increased by 134% with just 0.7 wt. % of graphene concentration as compared to those of pure polyurethane sample.
Control Strategies for Grid-Tied Inverters Based on Photovoltaic Solar Systems
Authors: Almousawi A Q , Aldair A
Published: March 2021

A two control strategy for a photovoltaic grid-tied system is proposed in this paper. A microgrid (MG) can be operated in a grid-tied mode or be disconnected from the grid (in an islanded mode). To interface renewable energy sources with low-voltage distribution systems, grid-tied inverters are more commonly used, however. When a MG operates in conjunction with the grid, various control techniques have been proposed based on current control (power control) in single or triple loops. In this paper, the proposed controller enables the PV solar system to run based on voltage-control (frequency/voltage) to regulate both active and reactive power injected into the grid. The MG consists of a photovoltaic (PV) array; a DC/DC boost converter to interface the PV array to a common DC-link with double loop strategy; a 3-phase inverter controlled using a triple loop strategy; an LCL output filter; and an impedance feeder used to connect the output of the inverter to the busbar of the grid. A dq-frame for voltage and current control structure is also used. A Phase-Locked Loop (PLL) mechanism is used to provide current control in order to extract (Ɵ), while it is extracted from the frequency control in the voltage control structure. Additionally, the control strategy uses feed-forward techniques to reduce the impacts of the inherent nonlinearity of the control system and inter-couplings. Two control strategies were thus designed, analysed, and validated through simulations under several operating scenarios using detailed switching models of a 23.5 kW a PV unit in PSCAD/EMTDC software.
Effects of Heat Treatment on the Corrosion and Mechanical Properties of Stainless Steel 316L as Used in Biomedical Applications
Authors: Marwan N Ali , Saad M Ali , Hamed Jamal M , Al_Hifadhi Muthanna
Published: March 2021

This work examines the influence of heat treatment processes, using oil and water at various temperatures as quenching media, on the mechanical, corrosion, and microstructural properties of 316L austenitic stainless steel as used as a biomaterial for temporary and permanent bone repairs or grafts and as a plate bone fixation during periods of treatment. The results show that the highest microhardness rate is obtained using normal water as a cooling media; this sample reached 157.7 Hv, a 9.97% higher value than that obtained using oil media and an 18.66% higher value than that obtained using one-hour heating. The microstructure images for the quenched samples in oil displayed more evenly and uniformly distributed carbon particles, suggesting the formation of a more pearlite structure as compared with the water-quenched samples, however. The highest polarization resistance value was obtained when using water cooling media with two hours heating time; this reached 2.849 V/μA. Dec., while the minimum value, reached 0.185 V/μA. Dec., was obtained using the hot water cooling medium. The minimum corrosion rate value was obtained using the oil cooling media; this was 0.34 × 10-5 milli-in./year, while the maximum value reached 0.86x10-5 milli-in./year for the water cooling medium with a three-hour heating duration. The resulting equivalent von-Mises stress reached its maximum value at 285.24 MPa at 150 Kg patient weight and 5 mm plate thickness. The total deformation reached a minimum value of 0.0723 mm, while the stress safety factor reached a maximum value of 2.7 for a patient weight of 60 Kg when using 10 mm plate thickness. The equivalent elastic strain and the strain energy reached minimum values of 4.7 × 10-4 mm and 0.021 mJ for a patient weight of 60 Kg when using 5 mm plate thickness, respectively.
Design of a Low-Cost Ventilator to Support Breathing for Patients with Respiratory Failure Arising from COVID-19
Authors: Ali Saad Mahmood , Mahmood Mohammed Saad , Mahmood Noor Saad
Published: March 2021

In this work, two new, low cost, lightweight and simple pneumatic portable mechanical ventilator prototypes that offer minimal oxygen consumption were presented in support of treatment during the novel coronavirus (COVID-19) epidemic of 2020. The prototypes were implemented in ANSYS 18.0 and evaluated using Expert Systems 11.0 software. Both prototypes devices were found appropriate for all patients with difficulty breathing, which for patients with COVID-19, includes those with all severities of illness, recovery levels, and ages, no matter what the capacity of the patient’s respiratory system. To ensure the safety of the designed devices, the airway oxygen sensors, valves, and analysers were equipped with programmable alarms and other controllable safety attachments, including a modification to enable the delivery of nitric oxide (NO) for a specified therapy treatment recommended for respiratory failure. The overall prototype device capacity was obtained in terms of tidal volume/min. (TV), which was between 0.2 to 1.6 I./breath, suggesting that the device can be used treat patients of all ages, from children to adults. The prototype device has a range of 10 to 40 breaths/min. (bpm), and for normal spontaneous breathing, at an expiratory to inspiratory ratio E:I = 2:1, the designed prototype can produce a total tidal volume between 2.02 to 32.32 l/min. For patients with moderate breathing difficulties, i.e. with E:I ratios of 1:1, between 3.03 to 48.48 l/min. was estimated, with between 4.04 to 64.64 l/min for those with high severity of breathing issues, i.e. those with higher E:I ratios above 2:1. The designed ventilator can also be used for most oxygen consumption durations as it uses any oxygen fraction (concentration) of inspired oxygen-enriched in gas (FIO2) at an efficiency at least 0.42% higher than previous similar and standard ventilator devices.
Synthesis of WO3/TiO2nanocomposites for Use as Photocatalysts for Eosin Yellow Dye Degradation
Authors: Jawad T M , Ahmed L M
Published: March 2021

This work focused on the modification of a WO3surface by incorporating a TiO2surface via ultrasonic techniques to produce a nano-composite in the ratio 1:2 WO3:TiO2. All materials were then characterised by x-ray diffraction, atomic force microscopy, and UV-VIS spectrophotometry. The x-ray diffraction data proved that the WO3incorporated the TiO2as a nano-composite, with an elevated mean crystal size from 17.89 nm to 40.084 nm. The atomic force microscopy analysis also indicated that all samples were spherical. An increase in reaction temperature was found to enhance photoreaction, an endothermic and non-spontaneous reaction. The activation energy value after incorporation was decreased to 14.54 kJ mol-1after the composite was formed, improving the WO3photo properties after modification with TiO2. Moreover, photocatalysis for the decolourisation of Eosin Yellow dye reaction with observed on using the WO3/TiO2nano-composite as a pseudo-first-order behaviour.
Mechanical concept development using principle solution models
Authors: Zerwas Thilo , Jacobs Georg , Spütz Kathrin , Höpfner Gregor , Drave Imke , Berroth Joerg , Guist Christian , Konrad Christian , Rumpe Bernhard , Kohl Jens
Published: March 2021

Cyber-physical systems (CPS) are characterized by the interaction of mechanical, electronic and information technology subsystems. Model-Based Systems Engineering (MBSE) is an approach for the cross-domain development of CPS and requires compatible methods and models for a function-oriented collaboration of the domains. However, the mechanics operate mainly component-oriented and thus cannot participate in the function-oriented development process. We propose a new modeling method that allows mechanics to develop a consistent and function-oriented system model from requirements and functions to principle solutions. The principle solution formally specifies the physical effect, active surfaces and material through which a function is fulfilled. Since principle solutions are consistently parameter-based, they can be calculated by linked external models and checked against requirements. This enables to examine possible solutions for functions at an early stage without having to develop components. Since principle solutions consist of recurring elements, we also propose a modeling concept for a solution libraryso that proven models can be efficiently reused and the modeling effort is reduced. Modeling method, test and solution library are explained using the example of an electric water pump of an automotive cooling circuit.
Investigation of the coating of hydrodynamic plain bearing contact surfaces by means of Extreme High-Speed Laser Material Deposition (EHLA)
Authors: Stephan Koß , Holzer Achill , Megahed Sandra , Ziegler Stephan , Schleifenbaum Johannes Henrich , Schmitz Katharina
Published: March 2021

In the field of drive technology, plain bearings are used in almost all drives. During operation these bearings have a very low load resistance and almost no wear. However, increased mixed friction can occur during starts, stops, low speeds and/or high loads. As a result of the increasing demands on the drive systems, such as in the automotive sector with the automatic start-stop system to reduce exhaust gases or in the area of the angular force, a greater mixed friction occurs, which increases wear. Extreme High-Speed Laser Material Deposition (EHLA) is a coating process that allows the application of cor-rosion and wear protection coatings in a resource-saving and productive manner. Furthermore, alterna-tive materials and material combinations can be created. In the framework of this study two different Metal Matrix Composites (MMC) are tribologically investigated and characterized in the area of mixed friction against three friction contacts each.
Simulation-Based Data Sampling for Condition Monitoring of Fluid Power Drives
Authors: Makansi Faried , Schmitz Katharina
Published: March 2021

Machine learning techniques are continuously gaining attention and importance in several technical domains. In the field of engineering, they can potentially provide manifold advantages for condition monitoring. However, availability of extensive operation data is a limiting factor. In this contribution, a simulation-based approach is presented, which allows an efficient generation of training data. Based on a lumped parameter simulation, a database of time-series data is generated for a hydraulic reference system. In order to incorporate states of faulty machine operation in the database, means to model component faults in the simulation are assessed. Further, a procedure for an automated training data generation is presented.
Evaluation of the Additive Manufacturability of CAD-Parts for initial Data Labelling in AI-based Part Identification
Authors: Winkler Marcel , Stürmer Stefan , Konrad Christian
Published: March 2021

The objective of this study is to develop and implement an analysis tool that identifies CAD geometries which impair Additive Manufacturing. A key performance indicator is generated to be used as data label representing the manufacturability for a future application of AI. Relevant geometric features are identified and algorithms to evaluate critical features are developed. The analyses include part orientation, build volume, wall thicknesses, gap widths, bore and cylinder diameters as well as the process-specific factors powder removal and need for support structures. The manufacturability of a part is calculated as Additive Manufacturing Feasibility Indicator (AMFI), depending on the identified critical features and a user-specific weighting. The AMFI successfully serves as data label which is suitable for application in AI methods. The developed GUI supports designers by highlighting critical features directly in the CAD environment and allowing the user in a purposeful part optimization for AM.
Research on UAV Flight Test Technology Based on Embedded Commands
Authors: Yin Wenqiang , Wang Yalong , Qi Shenjun
Published: March 2021

This paper presents the current situation that the pilot’s manual operation method can’t fully meet the requirements of UAV flight test. To solve the problem, a UAV flight test technology based on embedded command is proposed. By analysing the verification contents and assessment methods of UAV flight test, the typical actions in UAV flight test are extracted, the embedded command modules are designed, and the embedded command flight test method is formulated. The flight test results show that compared with the manual operation method, the embedded command flight test technology can alleviate pilot’s operation burden, reduce the flight test risks and improve the flight test efficiency.
A Review of Advanced High-Speed Rotorcraft
Authors: Yan Xufei , Lou Bin , Xie Anhuan , Chen Lingkai , Zhang Dan
Published: March 2021

Urban air transportation (private aircraft, air taxi, etc.) and all kinds of special flight missions (aerial sightseeing, logistics transportation, disaster relief, anti-terrorism and anti-riot etc.) put forward high requirements for the flight performance of future urban aircraft. It not only demands high-efficiency hovering performance, but also demands the capability of high-speed cruising as well as high safety, clean energy and other characteristics. The maximum flight speed of conventional rotorcraft (such as helicopter, multi-rotor UAV, etc.) is limited by the fluid compressibility of advancing rotor blade and the airflow separation of retreating rotor blade, which makes further improvement of the flight speed more difficult. In order to overcome the fluid compressibility of rotor advancing side and stall of rotor retreating side encountered under high-speed, researchers have proposed many new concepts of advanced rotorcraft. This article sorts and analyses the current advanced VTOL (Vertical Take-Off and Landing) rotorcrafts with new configurations, and attempts to point out the feasible research direction in the future.
Substrate dopant induced electronic inhomogeneity in epitaxial bilayer graphene
Authors: Zhang Shuai , Huang Di , Gu Lehua , Wang Yuan , Wu Shiwei
Published: March 2021

Two-dimensional (2D) materials have become a new territory for exploring novel properties and functionalities because of their superior tunability. The unprecedented tunability of 2D materials is also accompanied by many and equally great challenges, as they are susceptible to defects and disorders. The presence of defects and disorders induces the inhomogeneity of electronic states, often making it difficult to directly probe the intrinsic properties of materials. Therefore, many efforts have been devoted to improve the electronic homogeneity, for example, by reducing the density of defects and disorders in the materials and at the interface. However, little attention is paid to the disorders embedded in underlying substrates. Here we investigate how individual dopants in substrate interact with 2D materials and give rise to the electron–hole puddles by low temperature scanning tunneling microscopy (STM) and spectroscopy. Specifically, we take the epitaxial bilayer graphene grown on nitrogen doped silicon carbide (SiC) substrates as a model system, which has played the essential roles in many applications and fundamental studies. The nitrogen dopants inside SiC substrate were imaged over the epitaxial graphene by STM for the first time. The charged nitrogen dopants from the substrate induce the electron-lack puddles in graphene with a diameter of ∼2 nm, via electrostatic Coulomb interaction. The Fermi level with respect to the Dirac point is modulated by the puddles with an amplitude of ∼40 meV, causing the electronic inhomogeneity of epitaxial graphene. Our findings on this prototype material are expected to facilitate the quality improvement of graphene and other 2D materials in general.
Central Hypertension in Patients With Thoracic Aortic Aneurysms: Prevalence and Association With Aneurysm Size and Growth
Authors: Rooprai Jasjit , Boodhwani Munir , Beauchesne Luc , Chan Kwan-Leung , Dennie Carole , Wells George A , Coutinho Thais
Published: March 2021

BACKGROUND

Hypertension (HTN) has the greatest population-attributable risk for aortic dissection and is highly prevalent among patients with thoracic aortic aneurysms (TAAs). Although HTN is diagnosed based on brachial blood pressure (bBP), central HTN (central systolic blood pressure [cSBP] ≥130 mm Hg) is of interest as it better reflects blood pressure (BP) in the aorta. We aimed to (i) evaluate the prevalence of central HTN among TAA patients without a diagnosis of HTN, and (ii) assess associations of bBP vs. central blood pressure (cBP) with aneurysm size and growth.

METHODS

One hundred and five unoperated subjects with TAAs were recruited. With validated methodology, cBP was assessed with applanation tonometry. Aneurysm size was assessed at baseline and follow-up using imaging modalities. Aneurysm growth rate was calculated in mm/year. Multivariable linear regression adjusted for potential confounders assessed associations of bBP and cBP with aneurysm size and growth.

RESULTS

Seventy-seven percent of participants were men and 49% carried a diagnosis of HTN. Among participants without diagnosis of HTN, 15% had central HTN despite normal bBP (“occult central HTN”). In these patients, higher central systolic BP (cSBP) and central pulse pressure (cPP) were independently associated with larger aneurysm size (β ± SE = 0.28 ± 0.11, P = 0.014 and cPP = 0.30 ± 0.11, P = 0.010, respectively) and future aneurysm growth (β ± SE = 0.022 ± 0.008, P = 0.013 and 0.024 ± 0.009, P = 0.008, respectively) while bBP was not (P > 0.05).

CONCLUSIONS

In patients with TAAs without a diagnosis of HTN, central HTN is prevalent, and higher cBP is associated with larger aneurysms and faster aneurysm growth.
Quantitative Fit Evaluation of N95 Filtering Facepiece Respirators and Coronavirus Inactivation Following Heat Treatment
Authors: Massey Travis L , Borucki Monica K , Paik Samuel Y , Fuhrer Kyle W , Bora Mihail , Kane Staci R , Haque Razi-ul M , Baxamusa Salmaan H
Published: March 2021

Reuse of filtering facepiece respirators (FFRs, commonly referred to as N95s) normally meant for single use has become common in healthcare facilities due to shortages caused by the COVID-19 pandemic. Here, we report that murine hepatitis coronavirus initially seeded on FFR filter material is inactivated (6 order of magnitude reduction as measured by median tissue culture infective dose, TCID50) after dry heating at 75°C for 30 min. We also find that the quantitative fit of FFRs after heat treatment at this temperature, under dry conditions or at 90% relative humidity, is not affected by single or 10 heating cycles. Previous studies have reported that the filtration efficiency of FFRs is not negatively impacted by these heating conditions. These results suggest that thermal inactivation of coronaviruses is a potentially rapid and widely deployable method to reuse N95 FFRs in emergency situations where reusing FFRs is a necessity and broad-spectrum sterilization is unavailable. However, we also observe that a radiative heat source (e.g. an exposed heating element) results in rapid qualitative degradation of the FFR. Finally, we discuss differences in the results reported here and other recent studies investigating heat as a means to recycle FFRs. These differences suggest that while our repeated decontamination cycles do not affect FFR fit, overall wear time and the number of donning/doffing cycles are important factors that likely degrade FFR fit and must be investigated further.
Synergic Effect of Botulinum Toxin Type A and Triamcinolone Alleviates Scar Pruritus by Modulating Epidermal Hyperinnervation: A Preliminary Report
Authors: Huang Shu-Hung , Wu Kuo-Wei , Lo Jing-Jou , Wu Sheng-Hua
Published: March 2021

Background

Patients often experience scar-related pruritus, which adversely affects quality of life. Triamcinolone acetonide (TAC) is widely used to treat pathologic scars, and botulinum toxin type A (BTX-A) reportedly improves scarring and associated discomfort.

Objectives

The aim of this study was to investigate the clinical efficacy of combining TAC and BTX-A to reduce scar itch; potential mechanisms were investigated via an animal model.

Methods

For the clinical study, each scar on a patient was divided into 2 equal parts, with one part receiving TAC/BTX-A and the other TAC alone. Therapeutic interventions were administered over 3 sessions at 4-week intervals. Itch intensity was measured on a visual analog scale before each therapeutic intervention (V1, V2, V3) and 4 weeks after the last intervention (V4). For the animal model, rats were allocated into 5 groups: control, untreated burn, TAC, BTX-A, and TAC/BTX-A. We evaluated alloknesis in the right hind paw and analyzed possible molecular mechanisms.

Results

In humans, TAC/BTX-A significantly reduced scar itch compared with TAC alone at V4 (P = 0.04). In rats, post-burn itch was mitigated at 4 weeks after treatment with TAC, BTX-A, and TAC/BTX-A (P = 0.03, P = 0.0054, and P = 0.0053, respectively). TAC/BTX-A significantly decreased the density of intraepidermal nerve fibers post-burn relative to the untreated burn (P = 0.0008). TAC/BTX-A downregulated the expressions of nerve growth factor and protein transient receptor potential vanilloid subtype 1.

Conclusions

TAC/BTX-A therapy exhibited enhanced and sustained clinical efficacy in relieving scar itch, possibly via modulating epidermal innervation and expression of transient receptor potential vanilloid subtype 1 .

Level of Evidence: 2
Targeted delivery of protein arginine deiminase-4 inhibitors to limit arterial intimal NETosis and preserve endothelial integrity
Authors: Molinaro Roberto , Yu Mikyung , Sausen Grasiele , Bichsel Colette A , Corbo Claudia , Folco Eduardo J , Lee Gha Young , Liu Yuan , Tesmenitsky Yevgenia , Shvartz Eugenia , Sukhova Galina K , Kloss Frederik , Croce Kevin J , Farokhzad Omid C , Shi Jinjun , Libby Peter
Published: March 2021

Aims

Recent evidence suggests that ‘vulnerable plaques’, which have received intense attention as underlying mechanism of acute coronary syndromes over the decades, actually rarely rupture and cause clinical events. Superficial plaque erosion has emerged as a growing cause of residual thrombotic complications of atherosclerosis in an era of increased preventive measures including lipid lowering, antihypertensive therapy, and smoking cessation. The mechanisms of plaque erosion remain poorly understood, and we currently lack validated effective diagnostics or therapeutics for superficial erosion. Eroded plaques have a rich extracellular matrix, an intact fibrous cap, sparse lipid, and few mononuclear cells, but do harbour neutrophil extracellular traps (NETs). We recently reported that NETs amplify and propagate the endothelial damage at the site of arterial lesions that recapitulate superficial erosion in mice. We showed that genetic loss of protein arginine deiminase (PAD)-4 function inhibited NETosis and preserved endothelial integrity. The current study used systemic administration of targeted nanoparticles to deliver an agent that limits NETs formation to probe mechanisms of and demonstrate a novel therapeutic approach to plaque erosion that limits endothelial damage.

Methods and results

We developed Collagen IV-targeted nanoparticles (Col IV NP) to deliver PAD4 inhibitors selectively to regions of endothelial cell sloughing and collagen IV-rich basement membrane exposure. We assessed the binding capability of the targeting ligand in vitro and evaluated Col IV NP targeting to areas of denuded endothelium in vivo in a mouse preparation that recapitulates features of superficial erosion. Delivery of the PAD4 inhibitor GSK484 reduced NET accumulation at sites of intimal injury and preserved endothelial continuity.

Conclusions

NPs directed to Col IV show selective uptake and delivery of their payload to experimentally eroded regions, illustrating their translational potential. Our results further support the role of PAD4 and NETs in superficial erosion.
Clinical risk prediction models for the prognosis and management of acute coronary syndromes
Authors: Haghbayan Hourmazd , Gale Chris P , Chew Derek P , Brieger David , Fox Keith A , Goodman Shaun G , Yan Andrew T
Published: March 2021

Patients with acute coronary syndromes (ACS), particularly non-ST-segment elevation ACS, represent a spectrum of patients at variable risk of short- and long-term adverse clinical outcomes. Accurate prognostic assessment in this population requires the simultaneous consideration of multiple clinical and laboratory variables which may be under-recognized by the treating physicians, leading to an observed risk-treatment paradox in the use of invasive and pharmacological therapies. The routine application of established clinical risk scores, such as the Global Registry of Acute Coronary Events risk score, is recommended by major international clinical practice guidelines for structured risk stratification at the time of presentation, but uptake remains inconsistent. This article discusses the methodology of designing, deriving, and validating clinical risk scores, reviews the major validated risk scores for assessing prognosis in ACS, and examines their role in guiding clinical decision-making in ACS management, especially the timing of invasive coronary angiography. We also discuss emerging data on the impact of the routine use of such risk scores on patient management and clinical outcomes, as well as future directions for investigation in this field.
Host restriction, pathogenesis and chronic carriage of typhoidalSalmonella
Authors: J. Barton Amber , Hill Jennifer , J. Blohmke Christoph , J. Pollard Andrew
Published: March 2021

While conjugate vaccines against typhoid fever have recently been recommended by the World Health Organization for deployment, the lack of a vaccine against paratyphoid, multidrug resistance and chronic carriage all present challenges for the elimination of enteric fever. In the past decade, the development of in vitro and human challenge models has resulted in major advances in our understanding of enteric fever pathogenesis. In this review, we summarise these advances, outlining mechanisms of host restriction, intestinal invasion, interactions with innate immunity and chronic carriage, and discuss how this knowledge may progress future vaccines and antimicrobials.
Minimally invasive coronary artery bypass grafting via a lower ministernotomy for left anterior descending artery myocardial bridging: mid-term results
Authors: Ghazy Ahmed , Alkady Hesham , Abugameh Ahmad , Buschmann Katja , Chaban Rayan , Schnelle Nalan , Kornberger Angela , Beiras-Fernandez Andres , Vahl C-F
Published: March 2021

OBJECTIVES

Coronary artery bypass grafting or supra-arterial myotomy is now suggested as a better therapeutic option in myocardial bridging (MB) when medical treatment fails to control symptoms. For left anterior descending (LAD) MB, minimally invasive coronary artery bypass via a lower ministernotomy can be offered.

METHODS

Forty-four consecutive patients who underwent elective minimally invasive coronary artery bypass surgery from 2005 to 2014 via an inferior sternotomy using the left internal mammary artery as a bypass graft for LAD MB were evaluated retrospectively.

RESULTS

The mean age was 59.1 ± 13.1 years with 26 (59%) men and 18 (41%) women. The mean body mass index was 27.2 ± 3.9 and the mean EuroSCORE II was 1.6 ± 1.8. Routine coronary multislice computed tomography angiography on the 6th postoperative day revealed 97.7% graft patency. During the initial hospital stay, 1 patient (2.3%) underwent a reoperation for early graft failure. Forty patients (91%) could be followed up for a mean period of 64.4 ± 24.5 months after the procedure, during which 2 patients (4.5%) died of non-cardiac causes and 9 patients (20.5%) underwent postoperative coronary angiography with confirmed graft occlusion in only 1 case (2.3%). The improvement in the distribution of patients in the Canadian Cardiovascular Society class 0 was from 4 patients (9%) preoperatively to 37 patients (84%) at the end of the follow-up period (P-value 0.001).

CONCLUSIONS

Minimally invasive coronary artery bypass surgery via a lower ministernotomy may be safe and efficient for treating LAD artery MB with acceptable complication rates, cosmetic benefits and patency rates.
Kinetic analysis of the inhibition mechanism of bovine mitochondrial F1-ATPase inhibitory protein using biochemical assay
Authors: Kobayashi Ryohei , Mori Sougo , Ueno Hiroshi , Noji Hiroyuki
Published: March 2021

ATPase inhibitory factor 1 (IF1) is a mitochondrial regulatory protein that blocks ATP hydrolysis of F1-ATPase, by inserting its N-terminus into the rotor–stator interface of F1-ATPase. Although previous studies have proposed a two-step model for IF1-mediated inhibition, the underlying molecular mechanism remains unclear. Here, we analysed the kinetics of IF1-mediated inhibition under a wide range of [ATP]s and [IF1]s, using bovine mitochondrial IF1 and F1-ATPase. Typical hyperbolic curves of inhibition rates with [IF1]s were observed at all [ATP]s tested, suggesting a two-step mechanism: the initial association of IF1 to F1-ATPase and the locking process, where IF1 blocks rotation by inserting its N-terminus. The initial association was dependent on ATP. Considering two principal rotation dwells, binding dwell and catalytic dwell, in F1-ATPase, this result means that IF1 associates with F1-ATPase in the catalytic-waiting state. In contrast, the isomerization process to the locking state was almost independent of ATP, suggesting that it is also independent of the F1-ATPase state. Further, we investigated the role of Glu30 or Tyr33 of IF1 in the two-step mechanism. Kinetic analysis showed that Glu30 is involved in the isomerization, whereas Tyr33 contributes to the initial association. Based on these findings, we propose an IF1-mediated inhibition scheme.
Immune Response and Hemolymph Microbiota ofApis melliferaandApis ceranaAfter the Challenge With RecombinantVarroaToxic Protein
Authors: Balakrishnan Balachandar , Wu Hua , Cao Li , Zhang Yi , Li Wenfeng , Han Richou
Published: March 2021

The honey bee is a significant crop pollinator and key model insect for understanding social behavior, disease transmission, and development. The ectoparasitic Varroa destructor mite put threats on the honey bee industry. A Varroa toxic protein (VTP) from the saliva of Varroa mites contributes to the toxicity toward Apis cerana and the deformed wing virus elevation in Apis mellifera. However, the immune response and hemolymph microbiota of honey bee species after the injection of recombinant VTP has not yet been reported. In this study, both A. cerana and A. mellifera worker larvae were injected with the recombinant VTP. Then the expressions of the honey bee immune genes abaecin, defensin, and domeless at three time points were determined by qRT–PCR, and hemolymph microbial community were analyzed by culture-dependent method, after recombinant VTP injection. The mortality rates of A. cerana larvae were much higher than those of A. mellifera larvae after VTP challenge. VTP injection induced the upregulation of defensin gene expression in A. mellifera larvae, and higher levels of abaecin and domeless mRNAs response in A. cerana larvae, compared with the control (without any injection). Phosphate buffer saline (PBS) injection also upregulated the expression levels of abaecin, defensin, and domeless in A. mellifera and A. cerana larvae. Three bacterial species (Enterococcus faecalis, Staphylococcus cohnii, and Bacillus cereus) were isolated from the hemolymph of A. cerana larvae after VTP injection and at 48 h after PBS injections. Two bacterial species (Stenotrophomonas maltophilia and Staphylococcus aureus) were isolated from A. mellifera larvae after VTP challenge. No bacterial colonies were detected from the larval hemolymph of both honey bee species treated by injection only and the control. The result indicates that abaecin, defensin, and domeless genes and hemolymph microbiota respond to the VTP challenge. VTP injection might induce the dramatic growth of different bacterial species in the hemolymph of the injected larvae of A. mellifera and A. cerana, which provide cues for further studying the interactions among the honey bee, VTP, and hemolymph bacteria.