Materials Science Forum Vol. 1058

Abstract: The structure of graphene has been described in this research work by introducing some innovative elementary theoretical concepts such as: - interpretation of the free electron pair not as a concentration of the electron cloud on one side of the nucleus (lone pair), but as a symmetrical distribution of the electron cloud on both sides, - hypothesis that in polar bonds and the vast majority of multiple bonds, one electron is shared, not an electron pair and distinction of intermolecular bonds in bi-electronic and mono-electronic, - interpretation of the transformation of the geometry of molecules in relation to the number of bonds as a result of changes in the spatial relationships between atoms, and not as a result of the hybridization of orbitals and prediction and calculation of the spatial parameters of molecules (topology, bond lengths and angles) by applying trigonometric equations and other geometric rules, - consideration that the formation of multiple bonds occurs thanks to the transformation of bi electronic bonds (sigma) into mono-electronic bonds. This transformation serves to increase the quantity of electrons available to form pi bonds which intensifies the cohesion between the atoms. According to the proposed model, it is a dense cross-linking of π bonds inside each graphene ring that allows exceptional cohesion, strength and stability to a thin "spiderweb" formed by a single layer of atoms.

Abstract: Aggregation-Induced Emission (AIE) has gone through a rapid development since it’s discovery back in 2001. It is a famous research topic as it shows many advantages compared with traditional fluorescent material struggling with the issue of Aggregation-caused quenching (ACQ), since it only emits fluorescence when gathered. AIE material can provide better sensitivity, better photobleaching resistance and SNR compared with traditional material. AIE material can be applied in the fields of biosensing and bioimaging to replace traditional material with a better performance. This article describes the concept and structure of AIE material, shows types of the material with examples, also introduces the application of AIE material in photodynamic therapy, this article talks about the concept, usage, advantages and drawbacks of applying material with AIE characteristics in photodynamic therapy.

Abstract: Bilayer graphene has been widely studied in recent years due to its intriguing physical properties and potential engineering applications. Here, we report on the stability measurements of isotope-labeled bilayer graphene with different stacking sequences. The results showed evidence of different defect intensity after the Ar plasma treatment. We found that the AB stacked bilayer graphene shows better stability when compared to twisted bilayer and monolayer graphene. However, for the protection of the under layer graphene, the twisted bilayer graphene showed better results. Our work demonstrates that the stability of bilayer graphene strongly depends on the layer stacking sequence.

Abstract: In this work, we investigated the effect of thin film encapsulation on V_th shift in a-IGZ0 TFTs. The result shows that decreasing the NH₃ flow rate of deposited SiON films, the trend of V_th shift under the operation mode can vary from negative to positive direction, which can be attributed to lower amount of hydrogen diffused from SiON to the a-IGZO TFTs. Beside, we designed the TFE with stable inorganic-organic-inorganic stack structure, of which the CVD1 deposited with low NH₃ flow rate and the CVD2 with high barrier property, and a 16.9-inch high performance flexible OLED panel with controlled V_th shift and RA lifetime over 475 h was achieved at the condition of 85 °C and 85% RH. This study demonstrates the influence of TFE on a-IGZO TFTs, and offers an optimized TFE structure which promises both electrical characteristics and reliability for flexible OLEDs.

Abstract: This report studies the charge-based sensing modality of FET-embedded nanopore biosensors through FEM simulation. PNP equation is solved to analyze the mirror charge introduced by charged biomolecule while threading through the nanopore-FET sensor. Negative and positive charged molecules are analyzed respectively. Obvious local potential change induced by the presenting of charged molecules nearby is observed. In addition, the transport-induced descreening effect is observed under intensive bias, which might explain the capability of charge sensing even under high concentrations such as 1 M for FET-nanopore biosensors.

Abstract: Internationally, the most widely used concrete mix design methods are the American Concrete Institute, Department of Environment, Indian Standard, Fineness Modulus and Walker. These methods propose the dosage of materials from tables and graphs developed from multiple experiments and generalize the designs to achieve optimum strength, durability, and quality performance. However, sustainability does not contemplate the design, especially cement, which is responsible for CO₂ emissions and the cost of concrete. The study analyzed the procedure and dosage of five methods for a 20 MPa strength concrete mix in the laboratory and applied them to beams and columns in a multi-family building using sustainability indicators. The results indicate that the IS method uses water efficiently, is more economical, and requires less cement, while the ACI method generates a positive environmental and social impact due to the efficient consumption of materials.

Abstract: Geopolymeric mortars derived from residues of the Peruvian formal mining industry were manufactured and mechanically evaluated under normal conditions of temperature and atmosphere. The mechanical results found in geopolymeric mortars were compared with those found in conventional Portland cement mortars (control). The values of maximum uniaxial compressive strengths for geopolymeric mortars were between 15.5 and 31.5 MPa, finding the best results when considering a ratio binder:fine sand of 1:2, hardener solution molarity of 20M and a ratio hardener solution:binder of 0.6. The microstructure found for both types of mortars studied (control and geopolymeric) consisted of an interconnected continuous phase of binder (cement or geopolymerized mining tailings) and another discontinuous one of fine sand particles, located within the binder phase.

Abstract: The objective of this article was to study the morphological characteristic and mechanical properties of gypsum boards. The gypsum plaster (GP) type 1 was replaced by water hyacinth fiber (WHF) at the dosages of 0, 50, 75, 100, and 150 by mass. The scanning electron microscopy (SEM) was used to observe their morphological characteristics, whereas mechanical properties of gypsum board were based on the TIS 219-2552. The thermal conductivity (k) was tested by according to ASTM E 1225 standard. Test results found that the morphological characteristics of the WFH showed rather roughness; thus, the voids of WHF increased. The thermal conductivity of gypsum boards incorporated with WHF tended to decrease as the void increased. Finally, it was determined that the water absorption (A_W) and two bending forces (F_L and F_W) of the gypsum board including WHF were insufficient for compliance with the TIS 219-2552 standard.

Abstract: The ever-growing global production of glass generates high waste percentages, the vast majority of which does not get recycled hence increasing the concern on its environmental impact. Studies on the pozzolanic properties of glass powder emerged as a solution to the abundance of waste glass powder available and its insufficient recycling. The aim of this study is to investigate the influence 10% ,15% and 20% of waste soda-lime glass powder as partial cement replacement; fresh concrete tests were carried out, as well as compression strength tests at 28 days on grade 280 kg/cm² concrete produced with pozzolanic cement. Tests results show an insignificant reduction of slump on the concrete mixes, an increase of air content and a decrease in density and compressive strength resistance with increasing glass powder substitution.

Abstract: Shape memory alloys (SMAs) are promising materials for the creation of heating or cooling systems due to their elastocaloric character. The paper proposes a concept of elastocaloric “porous” SMA beam working in bending. The beam was made with superelastic nickel-titanium SMA wires of different diameters placed in a flexible tube. While water was flowing through the tube, bending was manually applied using 3D printed wavy profiles with portions of arcs with constant curvatures. Preliminary results showed an oscillation of the fluid temperature at the outlet of the flexible tube (containing the SMA wires) at the same frequency as the mechanical loading, validating therefore the concept of elastocaloric porous SMA beam operating in bending.