Hustedfarah7944

The challenges of handling user-hostile alkaline solutions in the conventional alkali-activated binders (AAB) have initiated the development of "just add water" or one-part solid-based AAB systems. This paper aims to present a preliminary investigation on the development of one-part ambient-cured alkali-activated binders produced by synthesising high-calcium fly ash (HCFA) and ground granulated blast furnace slag (GGBS) using sodium metasilicate anhydrous. Three test series were conducted in this study to investigate the effects of GGBS/binder, activator/binder and water/binder ratios on the fresh and hardened properties of the one-part synthesis AAB system. It was found that the SiO2/Al2O3 molar ratio plays an important role in the attainment of compressive strength and limits the amounts of solid activators effective in contributing to the alkali-activation reaction process. The optimum SiO2/Al2O3 molar ratio was found between 3.20 and 3.30. The test results revealed that the optimum proportion between HCFA and GGBS was discovered at a GGBS/binder ratio of 0.50. The optimum activator/binder ratio was between 0.08 and 0.12, and it is recommended that the water/binder ratio should not exceed 0.50. This study demonstrated the potential of the one-part synthesis method in the production of alkali-activated binder for practical structural applications.Fibre-reinforced composite laminates are frequently used in various engineering structures, due to their increased weight-to-stiffness ratio, which allows to fulfil certain regulations of CO2 emissions. Limited inter-laminar strength makes composites prone to formation of various defects, which leads to progressive degradation of residual strength and fatigue life of the structure. Using ultrasonic guided waves is a common technique for assessing the structural integrity of composite laminates. Phase velocity is one of the fundamental characteristics of guided waves and can be used for defect detection, material property estimation, and evaluation of dispersion. https://www.selleckchem.com/products/pi4kiiibeta-in-10.html In this paper, a phase velocity reconstruction approach, based on the phase-shift method, was proposed, which uses frequency sweep excitation to estimate velocity at specific frequency harmonics. In contrast to the conventional phase spectrum technique, the proposed approach is applicable to the narrowband piezoelectric transducers and suitable for the reconstruction of dispersion curves for direct, converted, and multiple co-existing modes with high accuracy. The proposed technique was validated with finite element simulations and experiments, both on isotropic and anisotropic structures, analysing the direct, converted, and overlapped modes. The results demonstrated that, using the proposed technique, the phase velocity dispersion can be reconstructed at -20 dB level bandwidth of the transducer, with a relative error of ±4%, compared to the theoretical velocity predictions.Chemical corrosion has a significant impact on the properties of rock materials. To study the mechanical behavior and energy mechanism of rock under chemical corrosion, this paper took the sandstone of Haitangshan tunnel in Fuxin as the research object, used a Na2SO4 solution to simulate different chemical environments, carried out a triaxial loading test on sandstone through the MTS815.02 test system, and analyzed the mechanical parameters and energy damage evolution law of sandstone under different chemical environments. The test results showed that the basic mechanical parameters (peak strength σpk, peak strain εpk, elastic modulus E, cohesion c, and internal friction angle φ) and characteristic stress parameters (closure stress σcc, initiation stress σci, and dilatancy stress σcd) of sandstone first increased and then decreased with the increase of pH in the Na2SO4 solution, Poisson's ratio µ showed the opposite trend, and the extreme values of all parameters were taken when pH = 7. The influence degree od a linear function.In general, 20-25% of the original fibre weight is considered waste in the production of high-quality textiles for the construction sector. A market analysis has shown that in the Republic of Croatia alone, up to 327 tonnes of this waste is produced annually, which is enough to reinforce 50 to 150 thousand m3 of cementitious composites. This preliminary study aims to evaluate the contribution of glass, basalt and carbon fibres generated as waste in the local production of high-performance technical textiles, to the fresh and hardened properties of fibre reinforced mortars. In order to investigate the influence of fibres, three types of fibres in two different lengths (5 and 10 mm) were used, while the amount of fibres was constant. The obtained results show that due to the fibre presence, workability is reduced regardless of the type and length of the fibre. The tested fibres have a negligible effect on compressive strength, but the use of basalt and carbon fibres increases the tensile strength. Furthermore, all three types have positive influence on the toughness and volumetric deformations, although to a greater extent in the use of 10 mm long fibres and carbon fibres.The formation and evolution of silicene on ultrathin Au films have been investigated with low energy electron microscopy and diffraction. Careful control of the annealing rate and temperature of Au films epitaxially grown on the Si(111) surface allows for the preparation of a large scale, of the order of cm2, silicene sheets. Depending on the final temperature, three stages of silicene evolution can be distinguished (i) the growth of the low buckled phase, (ii) the formation of a layered heterostructure of the low buckled and planar phases of silicene and (iii) the gradual destruction of the silicene. Each stage is characterized by its unique surface morphology and characteristic diffraction patterns. The present study gives an overview of structures formed on the surface of ultrathin Au films and morphology changes between room temperature and the temperature at which the formation of Au droplets on the Si(111) surface occurs.The aim of this review is to present the recent developments in heat pipe production, which respond to the current technical problems related to the wide implementation of this technology. A novel approach in HP manufacturing is to utilise hi-tech additive manufacturing techniques where the most complicated geometries are fabricated layer-by-layer directly from a digital file. This technology might be a solution to various challenges that exist in HP production, i.e., (1) manufacturing of complex or unusual geometries HPs; (2) manufacturing complicated and efficient homogenous wick structures with desired porosity, uniform pore sizes, permeability, thickness and where the pores are evenly distributed; (3) manufacturing a gravity friendly wick structures; (4) high customisation and production time; (5) high costs; (6) difficulties in the integration of the HP into a unit chassis that enables direct thermal management of heated element and decrease its total thermal resistance; (7) high weight and material use of the part; (8) difficulties in sealing; (9) deformation of the flat shape HPs caused by the high pressure and uneven distribution of stress in the casing, among others.The collagen superfamily includes more than fifty collagen and/or collagen-like proteins with fibril-forming collagen type I being the most abundant protein within the extracellular matrix. Collagen type I plays a crucial role in a variety of functions, it has been associated with many pathological conditions and it is widely used due to its unique properties. One unique nano-scale characteristic of natural occurring collagen type I fibers is the so-called D-band periodicity, which has been associated with collagen natural structure and properties, while it seems to play a crucial role in the interactions between cells and collagen and in various pathological conditions. An accurate characterization of the surface and structure of collagen fibers, including D-band periodicity, on collagen-based tissues and/or (nano-)biomaterials can be achieved by Atomic Force Microscopy (AFM). AFM is a scanning probe microscope and is among the few techniques that can assess D-band periodicity. This review covers issues related to collagen and collagen D-band periodicity and the use of AFM for studying them. Through a systematic search in databases (PubMed and Scopus) relevant articles were identified. The study of these articles demonstrated that AFM can offer novel information concerning D-band periodicity. This study highlights the importance of studying collagen D-band periodicity and proves that AFM is a powerful tool for investigating a number of different properties related to collagen D-band periodicity.This study presents a U-shaped dual-frequency-reconfigurable liquid-metal monopole antenna. Eutectic Gallium-Indium (EGaIn) was used as a conductive fluid and filled in the two branches of the U-shaped glass tube. A precision syringe pump was connected to one of the branches of the U-shaped tube by a silicone tube to drive EGaIn, forming a height difference between the two liquid levels. When the height of liquid metal in the two branches met the initial condition of L1 = L2 = 10 mm, and L1 increased from 10 mm to 18 mm, the two branches obtained two working bandwidths of 2.27-4.98 GHz and 2.71-8.58 GHz, respectively. The maximum peak gain was 4.00 dBi. The initial amount of EGaIn also affected the available operating bandwidth. When the liquid metal was perfused according to the initial condition L1 = L2 = 12 mm, and L1 was adjusted within the range of 12-20 mm, the two branches had the corresponding working bandwidths of 2.18-4.32 GHz and 2.57-9.09 GHz, and the measured maximum peak gain was 3.72 dBi. The simulation and measurement data corresponded well. A series of dual-frequency-reconfigurable antennas can be obtained by changing the initial amount of EGaIn. This series of antennas may have broad application prospects in fields such as base stations and navigation.A comparative study of the fracture features, strength and deformation properties of pseudo strain-hardening composites based on alkali-activated slag and Portland cement matrices with polypropylene microfiber was carried out. Correlations between their compositions and characteristics of stress-strain diagrams under tension in bending with an additional determination of acoustic emission parameters were determined. An average strength alkali-activated slag matrix with compressive strength of 40 MPa and a high-strength Portland cement matrix with compressive strength of 70 MPa were used. The matrix compositions were selected for high filling the composites with polypropylene microfiber in the amount of 5%-vol. and 3.5%-vol. ensuring the workability at the low water-to-binder ratios of 0.22 and 0.3 for Portland cement and alkali-activated slag matrices, respectively. Deformation diagrams were obtained for all studied compositions. Peaks in the number of acoustic signals in alkali-activated slag composites were observed only in the strain-softening zone. Graphs of dependence of the rate of acoustic events occurrence in samples from the start of the test experimentally prove that this method of non-destructive testing can be used to monitor structures based on strain-hardening composites.