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Copper desorption in a soil with variable charge Scientia Agricola
Casagrande,José Carlos; Jordão,Camila Beig; Alleoni,Luís Reynaldo Ferracciú; Camargo,Otávio Antônio de.
Adsorption processes of heavy metals in soils have been more extensively studied than desorption, in spite of this latter process being related to nutrient bioavailability in the soil solution. Copper desorption from surface (0-0.2 m) and subsurface (1.0 - 1.2 m) samples of an Anionic Acrudox was studied at two pH values (4.5 and 7.5). Soil samples were incubated with Cu rates varying from 0 to 400 mg kg-1, during 4 and 12 weeks, in the presence of CaCl2 as support electrolyte at concentrations of 0.01 and 0.001 mol L-1. Complete soil adsorption of added Cu was observed at pH 7.5 in all incubation periods, indicating that a 24h-shaking period was enough to reach equilibrium and maximum adsorption. Copper adsorption varied with the incubation period and was...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Copper; Desorption; Ionic strength; PH.
Ano: 2004 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162004000200012
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Enzymatic and biochemical characterization of Bungarus sindanus snake venom acetylcholinesterase J. Venom. Anim. Toxins incl. Trop. Dis.
Ahmed,M; Latif,N; Khan,RA; Ahmad,A; Rocha,JBT; Mazzanti,CM; Bagatini,MD; Morsch,VM; Schetinger,MRC.
This study analyses venom from the elapid krait snake Bungarus sindanus, which contains a high level of acetylcholinesterase (AChE) activity. The enzyme showed optimum activity at alkaline pH (8.5) and 45ºC. Krait venom AChE was inhibited by substrate. Inhibition was significantly reduced by using a high ionic strength buffer; low ionic strength buffer (10 mM PO4 pH 7.5) inhibited the enzyme by 1. 5mM AcSCh, while high ionic strength buffer (62 mM PO4 pH 7.5) inhibited it by 1 mM AcSCh. Venom acetylcholinesterase was also found to be thermally stable at 45ºC; it only lost 5% of its activity after incubation at 45ºC for 40 minutes. The Michaelis-Menten constant (Km) for acetylthiocholine iodide hydrolysis was found to be 0.068 mM. Krait venom...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Acetylcholinesterase; Inhibition; Krait; Ionic strength; Acetylthiocholine iodide; Bungarus sindanus; Snake venom.
Ano: 2012 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1678-91992012000200014
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IS Annona emarginata CAPABLE OF ACCUMULATE ESSENTIAL HEAVY METALS WITHOUT DAMAGES IN THE METABOLISM? Rev. Bras. Frutic.
BARON,DANIEL; AMARO,AMANDA CRISTINA ESTEVES; MACEDO,ANA CLAUDIA; BOARO,CARMEN SÍLVIA FERNANDES; FERREIRA,GISELA.
ABSTRACT This study aimed to evaluate if ionic strength variation causes differential accumulation of heavy metals in plants of Annona emarginata (Schltdl.) H. Rainer var. ‘terra-fria’, modifying gas exchange and dry matter production. The seedlings were cultivated under different ionic strengths of the ‘Hoagland and Arnon’s’ nutrient solution (75% I, 50% I and 25% I). At 180 days after the application of the treatments, the effects of the essential heavy metals on the physiological parameters and foliar ionic concentration were assessed. The leaf gas exchanges and vegetative growth were affected by the variation in the essential heavy metals, with positive effects on the plants that were treated with 75%I. The seedlings that were grown under 75% I...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Heavy metals; Ionic strength; Mineral nutrition; Photosynthesis.
Ano: 2017 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-29452017000400202
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Nickel adsorption by variable charge soils: effect of pH and ionic strength BABT
Soares,Marcio Roberto; Casagrande,José Carlos; Mouta,Ernesto Rinaldi.
The effects of pH and ionic strength (I) on Ni adsorption in variable charge soils were evaluated by laboratory batch experiments. Experimental results fitted the Langmuir model. Maximum adsorption (Ads max) ranged from 260-2818 mg kg-1 (topsoil) to 532-1541 mg kg-1 (subsoil). Nickel affinity (K L) was higher in the subsoil samples (0.022-0.236 L kg-1) than in topsoil (0.003-0.049 L kg-1). Adsorption envelopes showed sharp increase in Ni adsorption (20-90%) in the 4.0-6.0 pH range. Nickel adsorption was affected by I and specific adsorption predominated in the 3.0-5.0 pH range, while above pH 5.0, it was adsorbed by electrostatic mechanisms. Negative values of free energy variation (ΔG) and the separation factor K R<1 indicated that Ni adsorption...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Adsorption isotherms; Free energy; Adsorption envelopes; Adsorption edges; Ionic strength.
Ano: 2011 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132011000100025
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Optimizing exponential growth of Triticum aestivum by application of the relative addition rate (RAR) technique utilizing a computer-controlled nutrient delivery system Braz. J. Plant Physiol.
Pintro,José Carlos; Taylor,Gregory James; Matumoto-Pintro,Paula Toshimi.
We conducted experiments designed to assess whether plants can be grown under conditions of low ionic strength simulating natural soil conditions. Wheat (Triticum aestivum, cv. Atlas 66) plants were grown using ten different relative nutrient addition rates (RAR) of nutrients (0.00, 0.06, 0.09, 0.12, 0.15, 0.18, 0.21, 0.24, 0.27, and 0.30 day-1) with a background solution containing 50 µmol.L-1 N and all other essential nutrients in optimal proportions relative to N. The relative growth rate (RGR) of plants over a 19-day experimental period responded directly to RAR (from 0.06 to 0.21 day-1) with a linear slope of 0.56 and an intercept of 0.085 day-1. Solution electrical conductivity (EC) values remained relatively stable over the experimental period. We...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Growth; Ionic strength; Nutrient solution; Wheat.
Ano: 2004 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1677-04202004000300006
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Phosphorus availability in a low pH highly weathered soil as affected by added salts Ciência Rural
Ernani,Paulo Roberto; Barber,Stanley Arthur.
Concentration and identity of cations and anions in the soil solution may affect soil P reactions and thus P availability. The magnitude of these reactions was evaluated in this research after application of various salts to a highly weathered low pH soil. Chloride, nitrate, and sulfate salts of Na, NH4, K, Ca, Mg, Sr, or Cu were added to the soil after addition of 360mg P/kg trying to simulate ion concentrations around granules of fertilizers in the soil. Thirty days later, P was determined in the soil solution (Pli) and on the solid phase (Psi). The soil samples of some treatments were leached with water and three days later a new soil solution was displaced. Separate addition of all salts increased Pli, except NaCl at the lowest rate. The increase of...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Acid soils; Phosphorus reactions; Ionic strength.
Ano: 1995 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-84781995000200007
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Purification of inulinases by changing the ionic strength of the medium and precipitation with alcohols Anais da ABC (AABC)
GOLUNSKI,SIMONE; SILVA,MARCELI F.; MARQUES,CAMILA T.; ROSSETO,VANUSA; KAIZER,ROSILENE R.; MOSSI,ALTEMIR J.; RIGO,DIANE; DALLAGO,ROGÉRIO M.; DI LUCCIO,MARCO; TREICHEL,HELEN.
ABSTRACT The present study evaluated the purification of inulinase by changing the ionic strength of the medium by addition of NaCl and CaCl2 followed by precipitation with n-propyl alcohol or iso-propyl alcohol. The effects of the concentration of alcohols and the rate of addition of alcohols in the crude extract on the purification yield and purification factor were evaluated. Precipitation caused an activation of enzyme and allowed purification factors up to 2.4-fold for both alcohols. The purification factor was affected positively by the modification of the ionic strength of the medium to 0.5 mol.L-1 NaCl before precipitation with the alcohol (n-propyl or iso-propyl). A purification factor of 4.8-fold and an enzyme yield of 78.1 % could be achieved by...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Inulinases; Ionic strength; Precipitation; Low cost..
Ano: 2017 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652017000100057
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Zinc adsorption in highly weathered soils PAB
Casagrande,José Carlos; Soares,Marcio Roberto; Mouta,Ernesto Rinaldi.
The objective of this work was to assess the effects of pH and ionic strength upon zinc adsorption, in three highly weathered variable charge soils. Adsorption isotherms were elaborated from batch adsorption experiments, with increasing Zn concentrations (0-80 mg L-1), and adsorption envelopes were constructed through soil samples reactions with 0.01, 0.1 and 1 mol L-1 Ca(NO3)2 solutions containing 5 mg L-1 of Zn, with an increasing pH value from 3 to 8. Driving force of reaction was quantified by Gibbs free energy and separation factor. Isotherms were C-, H- and L-type and experimental results were fitted to nonlinear Langmuir model. Maximum adsorption ranged from 59-810 mg kg-1, and Zn affinity was greater in subsoil (0.13-0.81 L kg-1) than in the...
Tipo: Info:eu-repo/semantics/article Palavras-chave: PH; Adsorption envelope; Adsorption isotherm; Ionic strength; Trace element.
Ano: 2008 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-204X2008000100017
Registros recuperados: 8
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