Ab Initio Calculation of Li-Sn System: Unraveling New Phases of Superconducting Materials with Increasing Compression

Stoichiometry, crystal compound, electronic attributes and superconductivity of compressed lithium-tin composites have been thoroughly studied using quantum mechanical genetic algorithm approach and the first principles computations based on density functional theory. Our simulations at moderate pressure (5-20 GPa) predict a complex convex hull diagram, with the following stable Li‑rich phases: I4/mmm-Li6Sn2, -Li7Sn2, -Li5Sn2, Ama2-Li4Sn2, -Li5Sn2, -Li6Sn2, C2/m-Li4Sn1, P21/m-Li6Sn2, -Li7Sn2 and Cmcm-Li4Sn2. Careful examination at their independent elastic parameters reveals sufficient mechanical stability in them. These phases are metallic system, with reasonably high electron concentration near to Fermi level or N(EF) that ranges from 0.6 to 2.4 states/eV cell. It is also interesting for us to observe soft modes and steep-flat energy bands at Fermi levels of Li6Sn2 structures which are stable throughout the pressure range. These features are prerequisites for superconducting behavior. Linear response function with Gaussian and tetrahedron methods reveals satisfactory superconducting transition temperature Tc (3.1 ~ 6.6 K) and Tc (2.1 ~ 2.4 K), respectively. Structural transition results for based elements Li and Sn agree well with literature thus signifying reliable prediction of intermediate phases.

Use of Selected Spectral Ratios to Assess the Response of Pineapple to Potassium Nutrition

Potassium (K) nutrition in pineapple grown on tropical peat can be problematic due to high precipitation which encourages leaching losses. Non-destructive tools that can assess K deficiency and the accompanying changes in biophysical and biochemical properties within pineapple is a good strategy to employ. In this study, we assessed the biophysical changes in pineapple (var. MD2) in response to different K rates by using a hyperspectral approach. K deficiency was detected at 171 days after planting. Shortage of K also exhibited a shift in red edge towards shorter wavelengths between 500-700 nm. In addition, spectral ranges of 430-680 nm, as well as 680-752 nm were found to be most effective in differentiating spectral response to varying K rates. Three vegetation indices, i.e. Normalized Pigment Chlorophyll Index (NPCI), Plant Senescence Index (PSRI) and Red-edge Vegetation Index (RVSI) were found to best describe K treatment effects on pineapple canopy reflectance. This study could be extended further to include pineapple varieties other than MD2, and also key nutrients, such as N and P, for better fertilizer management in peat-grown pineapple.

Mapping the pH and Salinity Values for Paddy Field Area in East Coast Malaysia using Kriging Interpolation Technique

In paddy farming, the condition of soil is one of the important factors to promote a healthy growing plant. Certain pH and salinity levels are required in order to have soil condition which suits the microorganism life and promotes nutrient opportunity to the plant. Currently, the method used to identify the pH and salinity levels of the soil is by embedding a sensor on the soil which requires cost and time. Furthermore, it will only show the pH and salinity values at only one point and there are limitations if the area of interest is difficult to be accessed. In this research, a method was studied by using Kriging interpolation technique to map soil salinity and pH near Kelantan and Terengganu paddy cultivation area. Ground truth data were pre-processed to generate an image model mapping which consists of acidity, neutral, alkalinity and level of salinity at coordinates of interest using ArcGIS Pro software. As a result, the estimated pH and salinity value range were between 3.9 to 5.9 and 0.48 to 0.71 ds m-1 respectively. To test the accuracy of the model, analysis of RMSE was done for pH (0.854) and salinity (0.057). This research shall contribute as a preliminary study to model the soil pH and salinity values for monitoring purpose and as an aid to the farmers.

Predicting AAK1/GAK Dual-Target Inhibitor against SARS-CoV-2 Viral Entry into Host Cells: An in silico Approach

Clathrin-mediated endocytosis (CME) is a normal biological process where cellular contents are transported into the cells. However, this process is often hijacked by different viruses to enter host cells and cause infections. Recently, two proteins that regulate CME – AAK1 and GAK – have been proposed as potential therapeutic targets for designing broad-spectrum antiviral drugs. In this work, we curated two compound datasets containing 83 AAK1 inhibitors and 196 GAK inhibitors each. Subsequently, machine learning methods, namely Random Forest, Elastic Net and Sequential Minimal Optimization, were used to construct Quantitative Structure Activity Relationship (QSAR) models to predict small molecule inhibitors of AAK1 and GAK. To ensure predictivity, these models were evaluated by using Leave-One-Out (LOO) cross validation and with an external test set. In all cases, our QSAR models achieved a q2LOO in range of 0.64 to 0.84 (Root Mean Squared Error; RMSE = 0.41 to 0.52) and a q2ext in range of 0.57 to 0.92 (RMSE = 0.36 to 0.61). Besides, our QSAR models were evaluated by using additional QSAR performance metrics and y-randomization test. Finally, by using a concensus scoring approach, nine chemical compounds from the Drugbank compound library were predicted as AAK1/GAK dual-target inhibitors. The electrostatic potential maps for the nine compounds were generated and compared against two known dual-target inhibitors, sunitinib and baricitinib. Our work provides the rationale to validate these nine compounds experimentally against the protein targets AAK1 and GAK.

A Review on the Application and Morphology of Organic Corrosion Inhibitors

Corrosion is a major challenge in construction technology and manufacturing industry. It does not only reduce the aesthetics of a building but also weakens the structure. Structural weakness caused by rust leads to the reduction in the durability of reinforced concrete. Various efforts and research ranging from prevention to maintenance process are being carried out globally to overcome this problem. Due to the increased awareness of the importance of preserving the environment for health and ecological system, studies are increasingly focused on the use of environmentally friendly corrosion inhibitor. This paper discusses several conditioning methods of using organic corrosion inhibitors in concrete reinforcement. It also takes a close look at the effect of every conditioning method towards the reinforced concrete strength and the mechanism to improve it. The migrating and admixed corrosion inhibitors (MCI) conditioning methods is considered as the best solution so far to enhance corrosion resistance performance that contributes to superior reinforced concrete mechanical strength.

Challenges and Way Forward for Implementing Green Roof in Construction Industry in Sarawak, Malaysia

There is a growing global concern about the adverse effects of today's rapid economic growth and development, which impact the environment and deplete energy supply. A green roof may lower a building's energy consumption and minimise air pollution by reducing dust particles in the air. The primary impediment to green roof implementation in Malaysia lacks local knowledge and unskilled green roof specialists. As a result, there is a shortage of green roof installers and specialised firms in the country. This article discusses the problems and solutions of adopting green roofs in building projects based on construction industry experience in Sarawak. A survey utilising a questionnaire is used to obtain data for this research. The paper revealed the possible challenges of adopting a green roof for the construction industry. The study is critical in order to adopt green roof technology quickly in Malaysia.