Silicon

Silicon (Si) is known as a beneficial or quasi-essential element particularly for graminaceous crops, as Si increases photosynthetic efficiency, increased resistance to biotic and abiotic stress, aluminium toxicity, heavy metal toxicity, dry matter accumulation and enhances resistance to lodging and drought. The combined application of phosphorus (P) and Si has a significant impact on the growth and yield of various crops. While the residual effect of Si and P application on growth, yield and soil biological activity in wheat were not ascertained. Therefore, the present study was conducted to evaluate the residual effect of Si and P on the wheat crop. The four levels of Si (0, 40, 80, and 120 kg Si ha–1) and P (0, 30, 60, and 90 kg P2O5 ha–1) were applied to the preceding aerobic rice crop and their effect was evaluated in succeeding wheat crop after two years of application. The results demonstrated a significant effect of Si and P on wheat growth, yield, nutrient uptake, and soil enzyme activities. The residual effect of 120 kg Si and 90 kg P2O5 ha–1 significantly improved the grain yield of the succeeding wheat crop by 24–45%. Further, the residual Si and P remarkably improved Si, N, P, and K concentration in wheat grain by 35, 13.2, 45, and 56 %, respectively, over control. Similarly, an increase in the microbial biomass carbon, dehydrogenase, fluorescein diacetate, and alkaline phosphatase activity by 17.2, 33.5, 12.4, and 37.5%, respectively were observed in the residual application of 120 kg Si and 90 kg P2O5 ha–1 over control. Therefore, the inclusion of Si and P could have great potential to improve soil enzyme activities and productivity of the wheat crop.

5-(2,4-dichlorophenyl)-2-furoic acid and anthraquinone-2-carboxylic acid were reacted separately with chitin. The synthesized products were characterized by various spectroscopic methods (FTIR, NMR and XRD) and were abbreviated as C524D2FA and CA2CA, respectively. The surface of the chitin derivatives, pulverized by pounding in mortar, was examined by SEM technique. Then, two different diodes were made by using these chitin derivatives as an interface layer. Al as metal and p-Si as semiconductor were used in the construction of the diodes. Some important properties of these diodes made were determined both in the dark and under an illumination of 100 mW/cm2. The Al/CA2CA/p-Si diode has been found to be more ideal than the Al/C524D2FA/p-Si diode conducted in this study and many other diodes made using Al and p-Si in other studies up to now.

The exogenous application of silicon (Si) is reported to enhance tolerance of plants against various environmental stresses. Therefore, the present study was carried out to examine the influence of foliar applied Si (1.5 mM) on growth, physiochemical processes and antioxidant defense system of barley plants (cvs. Jow-83 and B-12026) under different regimes of temperature (20 °C (control), 25 °C, 30 °C, and 35 °C). High temperature (HT) regimes caused a significant (P < 0.001) decline in shoot (68% and 84%) and root (44% and 77%) dry masses, leaf area (66% and 81%), chlorophyll (Chl) a (11% and 70%), Chl b (69% and 71%), carotenoids (60% and 62%), anthocyanins (56%), total soluble proteins (62%) and phenolics (36% and 50%) contents in both cvs. Jow-83 and B-12026, respectively. A significant (P < 0.001) increase in superoxide dismutase (205% and 133%), peroxidase (128% and 88%) and catalase (127% and 87%) activities was recorded in stressed plants of both cultivars, respectively. Moreover, HT stress markedly (P < 0.001) increased hydrogen peroxide (H2O2) (54% and 75%) and malondialdehyde (MDA) (52% and 149%) levels in both cultivars that activated the oxidative stress. But, plants treated with Si showed better growth and had higher total soluble proteins (18% and 12%), anthocyanins (74% and 39%), flavonoids (31% and 27%) and phenolics (39% and 19%) as well as the activities of SOD (43% and 29%), POD (46% and 40%) and CAT (24% and 63%) enzymes. Application of Si reduced HT-mediated oxidative stress by decreasing the concentration of MDA (39% and 49%) and H2O2 (14% and 56%) and increased shoot (49% and 46%) and root (40% and 34%) dry masses, Chl a (10% and 86%), Chl b (82% and 81%), and carotenoids (53% and 33%) in both barley cultivars. Plants of cv. Jow-83 showed more tolerance to temperature regimes than that of cv. B-12026 as evident from higher plant dry masses. Thus, our findings exhibited that foliar-applied Si is an efficient strategy that can be used to enhance the tolerance of barley plants to HT stress.

New glasses from harmful environmental waste like cement dust; limestone phosphate and sand were fabricated. The constructions of these sample investigation by FTIR, mechanical and optical properties. The density and refractive index of these glasses increases by increasing of SiO2 concentration. Longitudinal (vL), and share (vT) velocities increase with addition of silicon oxide. The elastic moduli values were showing increasing as an increasing of SiO2 concentration. The increase in elastic moduli may be connected to changing of the coordination number with an addition of SiO2 and the increase the bond strength, average force constant and the crosslink density. DTA of the investigated samples with exclusive SiO2 contents shows the increasing in Tg values. The molar volume and the optical band gab of these glasses decreases with increase of SiO2 expense on CaO.

TiO2 nanopowders doped by Ni were prepared by sol–gel method. The effects of Ni ion (transition metal ion) doping on the physical structural and optical properties of TiO2 have been investigated by X-ray diffraction (XRD), scanning electron microscopy and UV–Vis absorption spectroscopy. XRD results suggest that adding impurities has a significant effect on anatase phase stability, crystallinity, and particle size of TiO2. The phase transformation from anatase to rutile was inhibited by Ni ion doped TiO2 at temperatures 675 °C. The lowest band gap value (2.83 eV) was obtained for TiO2-4%Ni sample calcined at 675 °C.

In this study we have assessed the effect of long-term water storage at 37oC on silane-aided adhesion promotion. Five experimental silane blends were evaluated as adhesion-promoters. First, five functional organosilane monomers (silicon esters), 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, tetrakis-(2-methacryloxyethoxy)silane and bis-[3-(triethoxysilyl)propyl]tetrasulfide, were diluted to 1% (v/v) in 95% ethanol and blended with a non-functional cross-linking silane, bis-1,2-(triethoxysilyl)ethane (1%). A commercially available pre-activated silane product was used as the control. After activation by hydrolysis, each primer blend was applied to silica-coated Ti coupons. Stubs of experimental bis-phenol-A-diglycidyldimethacrylate (bis-GMA)-based resin were bonded by photo-polymerization onto the pretreated Ti coupons. Half of the specimens were stored in deionized water for 6 months and half for 12 months. The primer containing 3-acryloxypropyltrimethoxysilane and bis-1,2-(triethoxysilyl)ethane produced significantly higher shear bond strengths than the control silane and other experimental silane primers after both periods of storage.

This work investigates how the saw damage from different processes affected the Silver-catalyzed Metal Assisted Chemical Etching. Multicrystalline silicon ingot was grown from a 15 kg Directional Solidification (DS) furnace. The wafers were extricated from silicon brick by using the blade or diamond wire cutting machine which leaves the saw damage in the substrate of the wafer. Surface texturization process is required to reduce the reflectance of the wafer and to trap more photons on the surface. Silver-catalyzed Metal Assisted Chemical Etching was deployed to texture the surface of the silicon wafer. Five Mc-Si wafers were prepared through blade cut, diamond wire cut, lapping, mechanical polishing and chemical polishing. The surface of those wafers was textured using Silver-catalyzed Metal Assisted Chemical Etching. The preliminary studies like weight measurement, thickness calculations, lifetime measurement and resistivity are made. From the preliminary studies, it is confirmed that the etching rate is directly proportional to the roughness of the surface. All the wafers are subjected to SEM, Optical Microscopy and UV-Vis-NIR analysis. It is concluded that the saw damage affected the proper metal coating at the surface. The nanostructures are found in mirror-like polished wafers which produce the lowest weighted average reflection of 2.573%. From the results obtained from the characterizations, the simulations were done to examine the efficiency of the solar cell made from differently processed silicon wafers.

An important property which affects the heat transfer process in buildings and to minimize the usage of artificial energy in buildings is thermal conductivity. The transfer of heat through walls and roofs determines the amount of artificial energy required in the buildings. The conventional methods used to determine the thermal conductivity of buildings are transient and steady state methods. The objective of this paper is to measure the thermal conductivity of concrete specimens replacing nanosilica and GGBS by weight of ordinary Portland cement. Nanosilica was replaced by weight of cement in different proportions ranging from 1% to 5%. Addition of nanosilica and GGBS in concrete improves the compressive strength and split tensile strength of concrete by around 10%. Improvement in strength properties is mainly due to densification of concrete microstructure by filling pores in concrete specimens. In addition to the strength characteristics, nanosilica incorporated concrete specimens showed better thermal resistance as compared with conventional concrete mix. Lower heat transfer rate is due to the better particle packing nature of nanoparticles in concrete. Nanosilica acts as better heat retarding agent in concrete and thus it minimizes the use of artificial energy in the buildings. It is concluded that utilization of nanosilica reduces the heat transfer rate in to the buildings and the optimum amount of nanosilica was found to be 3% by weight of cement.