Optimisation of the bolt profile configuration for load transfer enhancement

Both bolt profile shape and profile spacing (rib spacing) have been found to influence the bonding capacity of the grouted rock bolt. The bolt surface profile configuration has greater importance to rock bolt than the steel rebar used in civil engineering construction, because the rock bolt is subjected to greater dynamic loading than the steel rebar. The increased bonding capacity of bolts is important when supported ground is either heavily fractured, faulted or the supported ground is of soft formation, typically that of coal measure rocks. Past laboratory studies have identified the bolt profile spacing as of significant relevance to bolt resin rock bonding increase, however, no attempt has been made to determine the optimum spacing between the bolt profiles spacing. Accordingly, a series of laboratory tests were carried out on 22 core diameter bolts installed in cylindrical steel sleeve. The study was carried out by both push and pull testing. The push testing was carried out in 150 mm long sleeves while the pull testing was made in 115 mm long sleeves. Profile spacing tested include, 12.5, 25.0mm, 37.5 mm and 50 mm lengths. The profile spacing of 37.5 mm wide was found to provide the optimum bearin

Numerical modelling of a fast pyrolysis process in a bubbling fluidized bed reactor

In this study, the Eulerian-Granular approach is applied to simulate a fast pyrolysis bubbling fluidized bed reactor. Fast pyrolysis converts biomass to bio-products through thermochemical conversion in absence of oxygen. The aim of this study is to employ a numerical framework for simulation of the fast pyrolysis process and extend this to more complex reactor geometries. The framework first needs to be validated and this was accomplished by modelling a lab-scale pyrolysis fluidized bed reactor in 2-D and comparing with published data. A multi-phase CFD model has been employed to obtain clearer insights into the physical phenomena associated with flow dynamics and heat transfer, and by extension the impact on reaction rates. Biomass thermally decomposes to solid, condensable and non-condensable and therefore a multi-fluid model is used. A simplified reaction model is sued where the many components are grouped into a solid reacting phase, condensable/non-condensable phase, and non-reacting solid phase (the heat carrier). The biomass decomposition is simplified to four reaction mechanisms based on the thermal decomposition of cellulose. A time-splitting method is used for coupling of multi-fluid model and reaction rates. A good agreement is witnessed in the products yield between the CFD simulation and the experiment

Correction to: The emerging role of probiotics as a mitigation strategy against coronavirus disease 2019 (COVID�19) (Archives of Virology, (2021), 166, 7, (1819-1840), 10.1007/s00705-021-05036-8)

Authors would like to correct the error in their publication. The original article has been corrected. 1. Reference 17 is incorrect. The correct one should be �The probiotic Bifidobacterium in the management of Coronavirus: A theoretical basis� https://doi.org/10.1177/2058738420961304. 2. The unnecessary symbol �??� found in text is deleted. © 2021, Springer-Verlag GmbH Austria, part of Springer Nature

Bacterial co-infections with SARS-CoV-2

The pandemic coronavirus disease 2019 (COVID-19), caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), has affected millions of people worldwide. To date, there are no proven effective therapies for this virus. Efforts made to develop antiviral strategies for the treatment of COVID-19 are underway. Respiratory viral infections, such as influenza, predispose patients to co-infections and these lead to increased disease severity and mortality. Numerous types of antibiotics such as azithromycin have been employed for the prevention and treatment of bacterial co-infection and secondary bacterial infections in patients with a viral respiratory infection (e.g., SARS-CoV-2). Although antibiotics do not directly affect SARS-CoV-2, viral respiratory infections often result in bacterial pneumonia. It is possible that some patients die from bacterial co-infection rather than virus itself. To date, a considerable number of bacterial strains have been resistant to various antibiotics such as azithromycin, and the overuse could render those or other antibiotics even less effective. Therefore, bacterial co-infection and secondary bacterial infection are considered critical risk factors for the severity and mortality rates of COVID-19. Also, the antibiotic-resistant as a result of overusing must be considered. In this review, we will summarize the bacterial co-infection and secondary bacterial infection in some featured respiratory viral infections, especially COVID-19. © 2020 International Union of Biochemistry and Molecular Biolog

An Assessment of Load Transfer Mechanism Using the Instrumented Bolts

Load transfer capacity and failure mechanism of a fully grouted bolt installed across joint plane in shear is evaluated experimentally and numerically, tests were made on un-instrumented and strained gauge instrumented bolts. Four types of bolts, with different properties and surface configurations were selected for the study. The changes in strength of the concrete, bolt mechanical properties and bolt pretension load were evaluated in different shear environments. Results from the instrumented bolts and numerical simulation showed that the tensile and compression stresses and strains are generated at early stage of loading and hinge points are created at both sides of the shear joints. Strains are in greater value in vicinity of the shear joint. The failure location moves towards the bolt joint intersection due to the increasing shear load, shear displacement and axial load developed along the bolt

Modelling shearing characteristics of reinforced concrete

Numerical modeling represents the most versatile computational method for various engineering disciplines. Nowadays, numerical modelling is extensively used in civil and mining applications because of cost and risk problems associated with excessive field studies, particularly in ground control applications. In this study, the behaviour of shearing a fully grouted bolt with regard to assessing strata reinforcement (particularly in shearing) has been simulated. In addition, the effect of both different rock strength and different pretensioning levels with 3D numerical simulation are analysed. It was found that the strength of surrounding material contributed to the increased resistance of the installation and has reduced shear displacement; shear resistance increased with increasing bolt tensile load. Several laboratory tests were carried out in order to confirm the numerical results and the findings from the laboratory studies were found to be in agreement with modelling simulations

Rock and bolt properties and load transfer mechanism in ground reinforcement

Load transfer capacity and failure mechanism of a fully grouted bolt installed across joints in shear is evaluated in both experimental and numerical approaches in 5 types of bolts. The strength of the concrete, bolt profile configuration and bolt pretension load plays significant influence on the shear resistance, shear displacement and failure mechanism of the reinforced medium. Bolt yields at low level of loading at hinge points. Failure location moves towards the bolt joint intersection due to the increasing shear load, shear displacement and bolt pretension load. Finally bolt failure occurs as a result of the induced axial and shear stresses acting between hinge point distances at the vicinity of shear joint plane

The effect of resin thickness on bolt-grout-concrete interaction in shear

Numerical modelling is extensively used in civil and mining engineering applications because of cost and risk problems associated with different experimental studies. In this study, the effect of resin thickness was evaluated in bolt-grout-concrete interaction and bending behaviour of a fully grouted bolt installed across joints in post failure region. Tests were conducted in 20 and 40 MPa concretes, and modelling simulations were made, using ANSYS version 8.1, to include both with and without different pretension loads. It was found that in all resin thickness, both the strength of the concrete and bolt pretension had major influences on the shear resistance and shear displacement of the reinforced medium. Also it was found that the strength of the surrounding concrete is more important than that of the grout thickness in both the shear resistance and shear displacement when the bolt is pretensioned

An assessment of load transfer mechanism using the instrumented bolts

Load transfer capacity and failure mechanism of a fully grouted bolt installed across joint plane in shear is evaluated experimentally and numerically, tests were made on un-instrumented and strained gauge instrumented bolts. Four types of bolts, with different properties and surface configurations were selected for the study. The changes in strength of the concrete, bolt mechanical properties and bolt pretension load were evaluated in different shear environments. Results from the instrumented bolts and numerical simulation showed that the tensile and compression stresses and strains are generated at early stage of loading and hinge points are created at both sides of the shear joints. Strains are in greater value in vicinity of the shear joint. The failure location moves towards the bolt joint intersection due to the increasing shear load, shear displacement and axial load developed along the bolt