Physico-mechanical characteristics of tropical granite boulders in weathered heterogeneous zones for geotechnical design purposes

The presence of isolated or clustered granite boulders in tropical weathered masses commonly formed a very thick heterogeneous zone in weathering Zone 3 to 5. The boulders with various characteristics are always misinterpreted during the geotechnical design process due to being poorly understood and studied. This study aims to determine the physico-mechanical characteristics of boulders in different weathering zones for design purposes. The parameters studied include boulder types, porosity, density, durability, point load and uniaxial compressive strength. Results revealed boulders in weathering Zone 3, 4 and 5 can be classified into Type A, B and C, respectively. These boulders have significant differences in physical and mechanical properties. The boulders in Zone 4 and 5 consists of corestone, ringlets and saprolites and the boulders in Zone 3 have no ringlets. Corestones have the highest durability, point load and compressibility strength with a median of 94.5%, 7.80 MPa and 187.07 MPa, respectively. The ringlets possess the highest porosity range of 23.3%–31.3% compared with saprolite. Saprolite in Zone 5 has the lowest durability, point load and compressive strength with respectively less than 7%, 0.22 MPa and 1 MPa. The various characteristics of the boulders in different weathering zones could influence the geotechnical design model

Debris Flow Numerical Simulation Model Comparison with Field Events in Kuala Kubu Baru and Lentang, Malaysia

Debris flow is one of Malaysia's natural disasters which could cause casualties and serious infrastructure damage. Precisely predicting the factors associated with the occurrence of debris flow such as the run-out lengths, velocities and thickness of alluvial deposits can greatly mitigate damage, minimize or even avoid the aftermaths of the occurrence. Applying numerical simulation models explaining debris flow deposition would be a valuable tool in forecasting potential debris flow activity and providing criteria for designing protective measures. Comprehensive studies of available records of past debris flow events from relevant sources and site investigations have been carried out in order to assemble field information for the particular debris flow event in Malaysia. A number of calamitous debris flow events occurred in Malaysia have been closely observed and studied. The well-documented events, i.e. Lentang and Kuala Kubu Baru debris flow disasters occurred on 2nd November 2004 and 10th November 2003, respectively were simulated using the Kanako 2D (Ver.2.04) simulation model software. The results obtained from the numerical simulation model were compared with the real events in order to evaluate their predictive capabilities. The results showed an accuracy of more than 93% was obtained from the simulation model as compared to the real in-situ measurements. A positive simulation result will become a valuable method to predict potential debris flow hazard behavior of the same type and characteristics

Effect of fluidising velocity on the combustion of rice husk in a bench-scale fluidised bed combustor for the production of amorphous rice husk ash

This study was focused on investigating the optimum fluidising velocity during the combustion of rice husk in a bench-scale fluidised bed combustor (ID 210 mm) to obtain low carbon ash in the amorphous form. When all other parameters are held constant, the optimum fluidizing velocity aids in almost complete combustion, thereby releasing the entrapped carbon for further conversion. This results in ash with consistently low carbon content (less than 2 wt%). The range of fluidising velocities investigated was from as low as 1.5 Umf to as high as 8 Umf. It was found that the optimum fluidising velocity was approximately 3.3 Umf as the mixing of rice husk with the bed was good with a high degree of penetration into the sand bed. The resulting ash retained its amorphous form with low residual carbon content (at 2.88 wt%) and minimal sand contamination as shown by the X-ray diffraction analysis

Forecasting of groundwater level using artificial neural network by incorporating river recharge and river bank infiltration

Groundwater tables forecasting during implemented river bank infiltration (RBI) method is important to identify adequate storage of groundwater aquifer for water supply purposes. This study illustrates the development and application of artificial neural networks (ANNs) to predict groundwater tables in two vertical wells located in confined aquifer adjacent to the Langat River. ANN model was used in this study is based on the long period forecasting of daily groundwater tables. ANN models were carried out to predict groundwater tables for 1 day ahead at two different geological materials. The input to the ANN models consider of daily rainfall, river stage, water level, stream flow rate, temperature and groundwater level. Two different type of ANNs structure were used to predict the fluctuation of groundwater tables and compared the best forecasting values. The performance of different models structure of the ANN is used to identify the fluctuation of the groundwater table and provide acceptable predictions. Dynamics prediction and time series of the system can be implemented in two possible ways of modelling. The coefficient correlation (R), Mean Square Error (MSE), Root Mean Square Error (RMSE) and coefficient determination (R2) were chosen as the selection criteria of the best model. The statistical values for DW1 are 0.8649, 0.0356, 0.01, and 0.748 respectively. While for DW2 the statistical values are 0.7392, 0.0781, 0.0139, and 0.546 respectively. Based on these results, it clearly shows that accurate predictions can be achieved with time series 1-day ahead of forecasting groundwater table and the interaction between river and aquifer can be examine. The findings of the study can be used to assist policy marker to manage groundwater resources by using RBI method

Persistence of spike-specific immune responses in BNT162b2-vaccinated donors and generation of rapid ex-vivo T cells expansion protocol for adoptive immunotherapy: A pilot study

Introduction: The BNT162b2 mRNA-based vaccine has shown high efficacy in preventing COVID-19 infection but there are limited data on the types and persistence of the humoral and T cell responses to such a vaccine. Methods: Here, we dissect the vaccine-induced humoral and cellular responses in a cohort of six healthy recipients of two doses of this vaccine. Results and discussion: Overall, there was heterogeneity in the spike-specific humoral and cellular responses among vaccinated individuals. Interestingly, we demonstrated that anti-spike antibody levels detected by a novel simple automated assay (Jess) were strongly correlated (r=0.863, P<0.0001) with neutralizing activity; thus, providing a potential surrogate for neutralizing cell-based assays. The spike-specific T cell response was measured with a newly modified T-spot assay in which the high-homology peptide-sequences cross-reactive with other coronaviruses were removed. This response was induced in 4/6 participants after the first dose, and all six participants after the second dose, and remained detectable in 4/6 participants five months post-vaccination. We have also shown for the first time, that BNT162b2 vaccine enhanced T cell responses also against known human common viruses. In addition, we demonstrated the efficacy of a rapid ex-vivo T cell expansion protocol for spike-specific T cell expansion to be potentially used for adoptive-cell therapy in severe COVID-19, immunocompromised individuals, and other high-risk groups. There was a 9 to 13.7-fold increase in the number of expanded T cells with a significant increase of anti-spike specific response showing higher frequencies of both activation and cytotoxic markers. Interestingly, effector memory T cells were dominant in all four participants’ CD8+ expanded memory T cells; CD4+ T cells were dominated by effector memory in 2/4 participants and by central memory in the remaining two participants. Moreover, we found that high frequencies of CD4+ terminally differentiated memory T cells were associated with a greater reduction of spike-specific activated CD4+ T cells. Finally, we showed that participants who had a CD4+ central memory T cell dominance expressed a high CD69 activation marker in the CD4+ activated T cells.This research was funded by Academic Health System, Medical Research Center, Hamad Medical Corporation, Doha, Qatar, grant number MRC-01-21-113, and the Article Processing Charges was funded by Academic Health System, Medical Research Center, Hamad Medical Corporation, Doha, Qatar. The funder was not involved in the study design, collection, analysis, interpretation of data, the writing of this article, or the decision to submit it for publication

The value of open-source clinical science in pandemic response: lessons from ISARIC

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