Sources and doses of aluminum in experiments with rice in nutrient solution

ABSTRACT The aluminum source to produce toxicity in upland rice in nutrient solution experiments is not yet well established, althought the aluminum potassium sulfate has been utilized source to produce aluminum toxicity. However, in recent studies have used aluminum chloride. The aim of this study was to evaluate the capacity of aluminum sources and doses to produce toxicity in upland rice plants grown in nutrient solution. The experiment was arranged in a block randomized design, in a 2 x 5 factorial scheme and four repetitions. The treatments were two aluminum sources (aluminum potassium sulfate - AlK(SO4)2.12H2O and aluminum chloride - AlCl3.6H2O) and five aluminum doses in nutrient solution (0, 370, 740, 1100 and 1480 μmol L-1). The experiment was conducted in a greenhouse in Botucatu city, São Paulo state, Brazil, starting in April 2012, and was carried out for 56 days from transplanting of the seedlings. Using aluminum chloride, the rice plants show lower production of root and total dry weight, area and root volume, medium and thick root length, potassium and sulfur contents and accumulations. Using aluminum potassium sulfate, there are lower aluminum activity and availability, besides the formation of large amount of aluminum compounds non-toxic to the plants (aluminum sulfate) in the nutrient solution. The aluminum doses between 1100 to 1480 µmol L-1, corresponding to aluminum activity of 336.8 to 429.0 µmol L-1 of aluminum chloride as source, are more effective to produce aluminum toxicity in upland rice plants grown in nutrient solution.

High temperature corrosion of commercial FeCrAl alloys (Kanthal AF) in nitrogen gas

In the present study, the corrosion mechanism of commercial FeCrAl alloy (Kanthal AF) during annealing in nitrogen gas (4.6) at 900?C and 1200?C is outlined. Isothermal and thermo-cyclic tests with varying total exposure times, heating rates, and annealing temperatures were performed. Oxidation test in air and nitrogen gas were carried out by thermogravimetric analysis. The microstructure is characterized by scanning electron microscopy (SEM-EDX), Auger electron spectroscopy (AES), and focused ion beam (FIB-EDX) analysis. The results show that the progression of corrosion takes place through the formation of localized subsurface nitridation regions, composed of AlN phase particles, which reduces the aluminum activity and causes embrittlement and spallation. The processes of Al-nitride formation and Al-oxide scale growth depend on annealing temperature and heating rate. It was found that nitridation of the FeCrAl alloy is a faster process than oxidation during annealing in a nitrogen gas with low oxygen partial pressure and represents the main cause of alloy degradation.

Nanosized Catalysts in the Process of Hydrogenating Acetylene

Hydrogenating process of the acetylene to ethylene using automated flow catalytic installation at nanoscaled catalysts Ni, Co and carriers at a pressure of 5 atm was studied. The actions of carriers and nanosized catalysts during hydrogenation reaction of acetylene to ethylene at low temperatures in the range from 50–120 °С were analyzed. With ratio of С2Н2:Н2 being equal to (1:2), at 80 °С the aluminum oxide carrier exhibits an activity, conversion of acetylene makes up 70%, when using zeolite 3A it is 63%. When the temperature rises to 120 °С, the aluminum activity is decreasing and conversion is 53%. However, zeolite exhibits its activity at high temperatures, at a temperature of 120 °С conversion of acetylene reaches to 73.5%. It is shown that with increasing of hydrogen ratio, the ethylene yield increases from 5 to 10.7% using catalyst 5% Ni/3A. In addition, in reaction of acetylene hydrogenation there are not formed waste products. For this process, the optimum reaction temperature is 80 °С, feedstock ratio (1:3) is positive, where the ethylene yield increased up to 16.7% and at catalyst to 5% Co/3A.

The Effects of Aluminum Activity on Aluminide Coating Formation of Nickel-Base Superalloy

The effects of different pure Al compositon in the pack powder on aluminide coating formation of a new kind of Ni-Cr-W-Al nickel-base superalloy by pack cementation aluminizing was investigated. The content of pure Al powder is 15% and 30% in the aluminizing agent. The microstructure and phase composition of diffusion coating was studied.

Theory and Experimental Research on Inclusion Modification in Improved Carbon Structural Steel

By means of the thermodynamics analysis of inclusion modification in the process of calcium treatment, and the advantage area chart of calcium, aluminum, sulfur, oxygen activity in inclusion midification, this paper analyzes the effects of molten steel temperature, aluminum activity, sulfur activity and other factors on inclusion modification. After calcium treatment, inclusions in high-quality carbon steel S48 will become massive or globular calcium aluminate, MnS inclusion and the composite inclusions of MgO·Al2O3 in kernel and CaO·Al2O3 in shell.