Papers by Keyword: Phosphorus

Abstract: Today, most surface waters of Ukraine are eutrophied due to the entry into water bodies of a significant amount of nutrients – compounds of carbon, nitrogen and phosphorus. Nitrogen and phosphorus enter water bodies with wastewater, sewage from agricultural lands and livestock farms, as well as with precipitation, due to the decomposition of water biomass, aquatic vegetation and zoocenoses. In the presence of free carbon dioxide (the concentration of which depends on bicarbonate alkalinity and water pH) and at certain rates of biochemical oxygen utilization (BOD) 7.2 g of nitrogen and 1 g of phosphorus produce 115 g of algae, which decomposition then consumes 115 g of oxygen [1].

Abstract: This paper discusses a novel annealing technique for 4H-SiC implants which involves the use of pulsed XeCl laser (l=308 nm). In particular, an absorbing graphitic coating is used to protect the sample from surface atoms desorption or phase separation. Both conventional furnace annealing and laser annealing on P and Al implants, commonly employed for source and body in metal-oxide-semiconductor field-effect transistors (MOSFETs), were examined through Transmission Electron Microscopy (TEM), u-Raman spectroscopy and Scanning Electron Microscopy (SEM). It is shown that the implant activated through traditional thermal annealing at 1650 °C for 30 min has a large network of dislocation loops, while they do not appear to be present in the laser annealed implant. Through Raman spectroscopy and SEM investigations both the crystalline quality of the laser annealed sample and the integrity of the surface were attested.

Abstract: Biochar research has been gaining recent interest in agricultural applications because of its use as a soil amendment. Biochar is a porous carbonaceous solid produced from heat in the absence of any introduced oxygen (pyrolysis). It has relatively high surface area and slow-release properties that makes it suitable for fertilizer formulation. In this study, rice straw is used for biochar production using modified carbonizer at 600-650°C temperature range. After synthesis in the nanoscale level, the biochar produced was infused with nutrients such as nitrogen, phosphorus, potassium and zinc. The morphological characteristics were studied using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and energy dispersive Xray spectrometry (EDS). Nutrients were incorporated in the biochar and analysis revealed concentrations of 4.96% N, 3.46% P, 2.25% K, and 10.90% OM. The nanoscale biochar-based fertilizer was then applied into rice production. Rice grown in soil amended with nanoscale biochar-based fertilizer showed higher yield than control treatments but with comparable result from the inorganic fertilizer treatments. This implies that biochar can be used as an alternative to chemical based fertilizer when infused with the essential nutrients needed by plants. Furthermore, the soil amended with the nanoscale biochar-based fertilizer was also found to have a higher nutrient and organic matter content after harvest. Therefore, it could preserve the soil fertility which is beneficial in the long term.

Abstract: Soybean seedlings were treated with different phosphorus (P) concentrations for 20 days to investigate their growth and development. The root growth and development of soybean seedlings was the best when the concentration of phosphorus was 250 μmol/L. After 20 days of cultivation at this concentration, the roots of soybean seedlings were developed, indicating that the main root length, lateral root length, and the number of lateral root was the best among all treatments, and the number of lateral roots was quite a few. In addition, when the concentration of P was at 250 μmol/L, it had a better promotion effect on the plant height of soybean seedlings, and could significantly enhance the development of soybean seedlings. Moreover, the growth of soybean seedlings would be inhibited at the condition of phosphorus deficiency or excessive phosphorus. In this experiment, the growth indexes of soybean seedlings were compared between four treatments of phosphorus concentration, so as to make a basic study on the physiological effect of soybean on phosphorus in early stage.

Abstract: The possibility of joint solid-phase reduction of iron and phosphorus from ferromanganese ore has been experimentally confirmed. Solid-phase reduction was performed at a temperature of 1000°C and exposure time of 2-5 hours, in a CO atmosphere, also produced the separation of the reduction products by melting. The distribution of iron and phosphorus was studied using an electron scanning microscope. The phase analysis of the samples was studied using a Rigaku Ultima IV X-ray diffractometer. The results were processed using the "Match" software. Reducing roasting in a CO atmosphere provides a transition from the oxide phase to the metallic phase of only iron and phosphorus without loss of manganese, thus increasing the concentration of MnO oxide in the residual oxide phase of the ore.

Abstract: The effect of additives of P₂O₅ on the solubility of molybdenum in the amorphous part of glass and on the phase composition of the crystallized part of the highly alkaline glasses of the Li₂O–(Na₂O–K₂O)–B₂O₃-SiO₂ system was studied. The comparison of the phase composition of samples with or without phosphorus prior and after annealing allowed to determine the change of solubility of molybdenum in the amorphous part of the samples and to evaluate the thermal stability of the synthesized glass-ceramic materials. It was found, that for the compositions without phosphorus and the samples without lithium, when molybdenum is added at the synthesis stage, almost all of the molybdenum is included only in the crystalline molybdates. The study has shown an increase in the solubility of molybdenum only in the structure of lithium-containing glasses with phosphorus.

Abstract: We have investigated the effect of high temperature annealing of phosphorus doped poly on gate oxide integrity and device reliability. In NMOS capacitance analysis, unstable flat band voltage characteristics and lower oxide breakdown electric field were observed in wafers which received high temperature poly annealing at 1100 °C. Gate oxide integrity (GOI/Vramp) tests and time dependent dielectric breakdown (TDDB) tests were performed to evaluate wafer level reliability. Degraded GOI characteristics and poor gate oxide lifetime were obtained for the high temperature poly annealed condition. To evaluate package level reliability, high temperature gate bias (HTGB) stress tests were conducted. Some samples failed in positive gate bias stress and more severe negative threshold voltage shift was observed in negative gate bias stress for the high temperature poly annealed condition.

Abstract: Polyamide 66 (PA66) benefits from excellent mechanical properties and good chemical resistance, which enabled wide application of this material in various industrial fields; however, it suffers from high flammability. Generally, preparation of a flame retardant PA from a reactive flame retardant involves a two-step process. In this study, the flame retardant PA66s (FRPA66s) are synthesized via a one-pot melt copolycondensation route by using a reactive phosphorus-containing flame retardant (FR-B). Then, molecular weight, some mechanical and thermal properties along with flame retardant properties of FRPA66s were investigated by gel permeation chromatography (GPC), instron material testing, differential scanning calorimetry (DSC), thermogravimetry (TG) analysis, vertical burning test (UL 94), and limiting oxygen index test (LOI) techniques. The experimental results confirmed that FRPA66s synthesized by the one-pot method have very similar properties compared to those obtained via the two-step process. Moreover, the prepared materials showed good non-flammability behavior with limiting oxygen index value of over 30% and a vertical burning test result of V-0 rating.

Abstract: The characterization of natural zeolite from Badinsk deposit was carried out by means of X-ray diffraction, scanning electronic microscopy, thermal analysis, Fourier transform infrared spectroscopy. The possibility of water purification from phosphates in dynamic conditions using of natural zeolite as a filtering bed was studied. The effect of the filtration rate of phosphates solution on purification efficiency is investigated. The mechanism of phosphates and ammonium removal with the participation of the zeolite is discussed: in case of phosphates it is the formation of insoluble compounds by reacting of calcium cations and phosphate anions; in case of ammonium ions it is ion exchange.

Abstract: In this work, we have studied the crystal defectiveness and doping activation subsequent to ion implantation and post-annealing by using various techniques including photoluminescence (PL), Raman spectroscopy and transmission electron microscopy (TEM). The aim of this work was to test the effectiveness of double step annealing to reduce the density of point defects generated during the annealing of a P implanted 4H-SiC epitaxial layer. The outcome of this work evidences that neither the first 1 hour isochronal annealing at 1650 - 1700 - 1750 °C, nor the second one at 1500 °C for times between 4 hour and 14 hour were able to recover a satisfactory crystallinity of the sample and achieve dopant activations exceeding 1%.