Effect of black caarbon on the growth, development and evapotranspriration of maize

Abstract. The effect of soot on certain parameters of maize was analysed. We applied low rates of soot (3 gm–2week–1) with a motorised sprayer. The effect of soot on evapotranspiration was tested on plants grown in evapotranspirometer (ET). Soot pollution had no influence on maize growth and development. Leaf withering after full maturity, however, was delayed by the presence of soot. The ability of soot to absorb irradiation and thus increase leaf surface temperatures led to an increase of 4% in the annual evapotranspiration sum. Soot pollution reduced dry matter (DM) on the rainfed plots (8.8 %), but not in the ET tanks. In the ET tanks, soot had no significant influence on either the stalk or the grain DM, though slight reductions were recorded. On the non-irrigated plot there was 12.4 % reduction in grain dry matter in response to pollution. Supplementary water supplies mitigated the plant damage caused by soot. A further advantage was detected in the number of deformed ears

Vanadate complexes in serum: a speciation modeling study

The speciations of two drug candidate ligands, 2-hydroxypyridine-N-oxide (Hhpno) and 2-mercaptopyridine-N-oxide (Hmpno), with vanadate (V(V)) were determined at 25.0 \u25e6C and 0.20 mol dm-3 KCl by pH-metric and 51V-NMR methods. At pH 7.4, the two predominant compounds with both ligands are the VO2L2 and VO2L(OH). NH4[VO2(hpno)2]\ub73H2O was prepared in solid form, and its crystal structure was determined by X-ray diffraction. The stabilities of the complexes VO2L2 of five drug candidate ligands were compared at pH 7.4. In view of the stability sequence hpno > maltol ~ hdp (Hhdp: 3-hydroxy-1,2-dimethyl-4-pyridinone) >> mpno > picolinic acid, the first two of these ligands were chosen for equilibrium studies with apotransferrin (apoTf) competition. The V(V)-apoTf stability constants (log K1 = 6.03 \ub1 0.10; log K2 = 5.46 \ub1 0.18) determined by 51V-NMR spectroscopy were confirmed by ultrafiltration. Both methods proved that there seems to be no hydrogencarbonate\u2013 vanadate competition for the apoTf anion-binding positions. The other potential high molecular mass V(V) binder in the serum is human serum albumin (HSA). As no interaction was detected by 51V-NMR spectroscopy or fluorimetry, the binding properties of HSA were quantified on the basis of literature data. As a final conclusion, speciation modeling calculations suggest that, under serum conditions, apoTf is probably the primary metal ion binder, even in the presence of the most stable V(V) carrier ligands hpno and maltol and HSA plays a negligible role in V(V) binding

Interactions of pyridinecarboxylic acid chelators with brain metal ions: Cu(II), Zn(II), and Al(III)

The interactions of Cu(II), Zn(II), and Al(III) with 1,6-dimethyl-4-hydroxy-3-pyridinecarboxylic acid (DQ716) and 2,6-dimethyl-3-hydroxy-4-pyridinecarboxylic acid (DT726), possible chelating agents in Alzheimer\u2019s disease, were investigated in aqueous solution. The proton dissociation constants of the ligands, the stability constants, and the coordination modes of the metal complexes formed were determined by pH-potentiometric, UV\u2013vis spectrophotometric, and 1H NMR methods. The nitrogen of the pyridine ring changes the proton affinity of the carboxylate and phenolate moieties and these pyridine derivatives form stronger complexes with Cu(II), Zn(II), and Al(III) than salicylic acid. Interactions of the ligands with human serum albumin as their potential transporter in blood were investigated at physiological pH through ultrafiltration by UV\u2013vis and fluorescence spectroscopy

Complexation properties of ethylenediaminetetramethylenephosphonic acid (EDTMP) with Al-III and (VO)-O-IV

The complexation properties (including stoichiometries and stability constants of the complexes formed) of ethylenediaminetetramethylenephosphonic acid with AlIII and VIVO were studied in aqueous solution at an ionic strength of 0.2 M KCl, at 25 \ub0C by means of pH-potentiometry. For AlIII both mononuclear (AlLHn) and dinuclear (Al2LHn) species were found in solution, whereas for VIVO only mononuclear complexes were detected. For each metal ion, a solid complex was isolated at acidic pH and was characterized stoichiometrically. 1H and 31P NMR (for AlIII), UV/Vis and EPR (for VIVO) spectra were used to confirm the potentiometric results and to suggest the most probable binding mode of the complexes formed in solution

N,N'-Ethylenebis(pyridoxylideneiminato) and N,N'-Ethylenebis(pyridoxylaminato): Synthesis, Characterization, Potentiometric, Spectroscopic, and DFT Studies of Their Vanadium(IV) and Vanadium(V) Complexes

The Schiff base N,Nprime-ethylenebis(pyridoxylideneiminato) (H2pyr2en, 1) was synthesized by reaction of pyridoxal with ethylenediamine; reduction of H2pyr2en with NaBH4 yielded the reduced Schiff base N,Nprime-ethylenebis(pyridoxylaminato) (H2Rpyr2en, 2); their crystal structures were determined by X-ray diffraction. The totally protonated forms of 1 and 2 correspond to H6L4+, and all protonation constants were determined by pH-potentiometric and 1H NMR titrations. Several vanadium(IV) and vanadium(V) complexes of these and other related ligands were prepared and characterized in solution and in the solid state. The X-ray crystal structure of [VVO2(HRpyr2en)] shows the metal in a distorted octahedral geometry, with the ligand coordinated through the N-amine and O-phenolato moieties, with one of the pyridine-N atoms protonated. Crystals of [(VVO2)2(pyren)2]sdot2 H2O were obtained from solutions containing H2pyr2en and oxovanadium(IV), where Hpyren is the ldquohalfrdquo Schiff base of pyridoxal and ethylenediamine. The complexation of VIVO2+ and VVO2+ with H2pyr2en, H2Rpyr2en and pyridoxamine in aqueous solution were studied by pH-potentiometry, UV/Vis absorption spectrophotometry, as well as by EPR spectroscopy for the VIVO systems and 1H and 51V NMR spectroscopy for the VVO2 systems. Very significant differences in the metal-binding abilities of the ligands were found. Both 1 and 2 act as tetradentate ligands. H2Rpyr2en is stable to hydrolysis and several isomers form in solution, namely cis-trans type complexes with VIVO, and alpha-cis- and beta-cis-type complexes with VVO2. The pyridinium-N atoms of the pyridoxal rings do not take part in the coordination but are involved in acid-base reactions that affect the number, type, and relative amount of the isomers of the VIVO-H2Rpyr2en and VVO2-H2Rpyr2en complexes present in solution. DFT calculations were carried out and support the formation and identification of the isomers detected by EPR or NMR spectroscopy, and the strong equatorial and axial binding of the O-phenolato in VIVO and VVO2 complexes. Moreover, the DFT calculations done for the [VIVO(H2Rpyr2en)] system indicate that for almost all complexes the presence of a sixth equatorial or axial H2O ligand leads to much more stable compounds

Foerderung des betrieblichen Umweltschutzes durch uebergreifende Schulungskonzepte im Bereich der Oberflaechenlackierung Bericht zur Projekt-Evaluation und Abschlussbericht

Available from TIB Hannover: F04B207: F04B208 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDeutsche Bundesstiftung Umwelt, Osnabrueck (Germany)DEGerman