Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0847097 (acidity)
 15,165 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Low-spin nickel(II) complexes containing bidentate ligands with modulated nitrogen donor ability, Py(Bz)2 or MePy(Bz)2 (Py(Bz)2 = N,N-bis(benzyl)-N-[(2-pyridyl)methyl]amine, MePy(Bz)2 = N,N-bis(benzyl)-N-[(6-methyl-2-pyridyl)methyl]amine), and a beta-diketonate derivative, tBuacacH (tBuacacH = 2,2,6,6-tetramethyl-3,5-heptanedione), represented as [Ni(Py(Bz)2)(tBuacac)](PF6) (1) and [Ni(MePy(Bz)2)(tBuacac)](PF6) (2) have been synthesized. In addition, the corresponding high-spin nickel(II) complexes having a nitrate ion, [Ni(Py(Bz)2)(tBuacac)(NO3)] (3) and [Ni(MePy(Bz)2)(tBuacac)(NO3)] (4), have also been synthesized for comparison. Complexes 1 and 2 have tetracoordinate low-spin square-planar structures, whereas the coordination environment of the nickel ion in 4 is a hexacoordinate high-spin octahedral geometry. The absorption spectra of low-spin complexes 1 and 2 in a noncoordinating solvent, dichloromethane (CH2Cl2), display the characteristic absorption bands at 500 and 540 nm, respectively. On the other hand, the spectra of a CH2Cl2 solution of high-spin complexes 3 and 4 exhibit the absorption bands centered at 610 and 620 nm, respectively. The absorption spectra of 1 and 2 in N,N-dimethylformamide (DMF), being a coordinating solvent, are quite different from those in CH2Cl2, which are nearly the same as those of 3 and 4 in CH2Cl2. This result indicates that the structures of 1 and 2 are converted from a low-spin square-planar to a high-spin octahedral configuration by the coordination of two DMF molecules to the nickel ion. Moreover, complex 1 shows thermochromic behavior resulting from the equilibrium between low-spin square-planar and high-spin octahedral structures in acetone, while complex 2 exists only as a high-spin octahedral configuration in acetone at any temperature. Such drastic differences in the binding constants and thermochromic properties can be ascribed to the enhancement of the acidity of the nickel ion of 2 by the steric effect of the o-methyl group in the MePy(Bz)2 ligand in 2, which weakens the Ni-N(pyridine) bond length compared with that of the nonsubstituted Py(Bz)2 ligand in 1.
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PMID:Equilibrium of low- and high-spin states of Ni(II) complexes controlled by the donor ability of the bidentate ligands. 1510 94

One of the problems in a reverse osmosis process for livestock wastewater treatment is disposal of the by-product concentrate. The agricultural recycling of the concentrate is more cost saving than a further treatment. Application of the concentrate reduces the chemical fertilizer amendment. The agricultural recycling of the concentrate from the Kimhae livestock wastewater treatment plant, processed with the VSEP RO and bio-ceramic SBR, was studied. The concentrate includes non-biodegradable humic ubstance and residual inorganic ions (NH4+, NO3-, PO4(3-), K+, etc.). The contents of N, P and K were 1,650, 382 and 2,059 mg L(-1), respectively. The total acidity of humic acids extracted from the concentrate was 5.17 cmol(+) g(-1), composed of 2.38 cmol(+) g(-1) of carboxylic group and 2.79 cmol(+) g(-1) of phenolic hydroxyl group. Coliforms and E. coli were not detected in the concentrate. The yield of rice plant with the concentrate applied to it resulted in similar production to that with chemical fertilizer applied. The water extractable nitrate content of the concentrate-applied land did not exceed that of chemical fertilizer applied, at soil depths of 30 and 60 cm. The percolated amount of nitrate into the water table in arable land with the concentrate applied showed a similar level to that treated with the chemical fertilizer.
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PMID:Agricultural recycling of the by-product concentrate of livestock wastewater treatment plant processed with VSEP RO and bio-ceramic SBR. 1513 51

The ionic compositions of particulate matter with aerodynamic diameter < or = 2.5 microm (PM2.5) and size-resolved aerosol particles were measured in Big Bend National Park, Texas, during the 1999 Big Bend Regional Aerosol and Visibility Observational study. The ionic composition of PM2.5 aerosol was dominated by sulfate (SO4(2-)) and ammonium (NH4+). Daily average SO4(2-) and NH4+ concentrations were strongly correlated (R2 = 0.94). The molar ratio of NH4+ to SO4(2-) averaged 1.54, consistent with concurrent measurements of aerosol acidity. The aerosol was observed to be comprised of a submicron fine mode consisting primarily of ammoniated SO4(2-) and a coarse particle mode containing nitrate (NO3-). The NO3- appears to be primarily associated with sea salt particles where chloride has been replaced by NO3-, although formation of calcium nitrate (Ca(NO3)2) is important, too, on several days. Size-resolved aerosol composition results reveal that a size cut in particulate matter with aerodynamic diameter < or = 1 microm would have provided a much better separation of fine and coarse aerosol modes than the standard PM2.5 size cut utilized for the study. Although considerable nitric acid exists in the gas phase at Big Bend, the aerosol is sufficiently acidic and temperatures sufficiently high that even significant future reductions in PM2.5 SO4(2-) are unlikely to be offset by formation of particulate ammonium nitrate in summer or fall.
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PMID:Aerosol ion characteristics during the Big Bend Regional Aerosol and Visibility Observational study. 1514 45

Chemical analyses during a decade of bulk precipitation, throughfall, humus water and soil water in forest plots ranging from sand to silt of Pleistocene origin in Flanders (N-Belgium) prove that previous and present weathering is predominantly due to synthesis of HNO3 from soil organic matter. The HNO3 reacts with silicates and possibly PO4(3-) species, releasing Al, Fe, nutrient base cations and H2PO4-, and is transformed into NO3-. In all soils solubilized Al3+ is predominantly associated with NO3- and with some organic bases in the coarse-textured soils with undisturbed or previously plowed spodic B horizon. The amounts of ions leached, especially Al3+ and NO3-, are much higher in the sandy than in the silty soils as a result of a stronger neutralization of acidity in the silty soils. Nutrients, leached from the soil, have to be replenished in some way for a sustained forest growth. N- and S-species must come from the atmosphere. Basic cations and P-species have to be supplied out of the solid phase. The concentrations of NO3- in the soil water show that the liberation of these elements from the solid phase is performed by HNO3. Especially in the coarse-textured soils the need for NO3- is high. Therefore, instead of being a real hazard for the forest ecological system, supplementary addition of HNO3 or NH3 can be beneficial.
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PMID:Synthesis of HNO3 from organic matter and its influence on nutrient replenishment in forest soils. 1547 49

Discrete dinuclear and polymeric heterometallic copper(II)-lanthanide(III) complexes have been synthesized upon variation of pH and characterized by X-ray diffraction analysis. Reactions of the ligand Htza (tetrazole-1-acetic acid) with copper(II) and lanthanide(III) salts gave dinuclear [CuLn(tza)4(H2O)5Cl] complexes at the low pH of 3.5 and 2D heterometallic coordination polymers with high-nuclearity [{Cu2(OH)2}2{Cu12Ln6(mu3-OH)24(Cl)(1/2)(NO3)(1/2)(tza)12(H2O)18}](NO3)(9).8H2O (Ln = Gd or Nd) at a higher pH of 6.6. The acidity of the reaction solution can cause drastic changes in the structures of the products. In the dinuclear complexes, each pair of adjacent dinuclear molecules is linked through hydrogen bonds and pi-pi stacking interactions, and the whole structure is a hydrogen-bonded three-dimensional cubic net. In the coordination polymers, the connecting nodes are [Cu12Ln6] units, which are interconnected by [Cu2O2] units into two-dimensional structures. Magnetic studies exhibit the existence of weak exchange interactions between the Cu(II) and Ln(III) ions bridged by carboxylate and hydroxy ligands.
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PMID:Controlled aggregation of heterometallic nanoscale Cu12Ln6 clusters (Ln = Gd(III) or Nd(III)) into 2D coordination polymers. 1567 85

Lichens were collected from three low-elevation sites in the western Cascade Range: HJ Andrews, OR (clean) and Bull Run, OR, and Pack Forest, WA (moderately enhanced nitrogen and sulfur deposition). The latter sites were within 50 km of Portland and Seattle/Centralia urban-industrial areas, respectively. Tissue concentrations of sulfur, nitrogen, and other macronutrients; rates of net carbon uptake; concentrations of photosynthetic pigments; and thallus density were correlated with season and seasonal changes in Platismatia glauca. Ion concentrations in precipitation and total wet deposition were measured from natural settings. Concentrations of depositional ions in precipitation, including NO3- and NH4+, were generally highest at Bull Run and Pack Forest; SO4(2-) concentrations and acidity were highest at Pack Forest. Total wet deposition was higher in the winter rainy season than the dry summer season at all three sites. Lichens adapted physiologically and morphologically to the higher light intensity and the warm, dry climate of summer through decreased optimal water content for CO2 uptake, increased concentrations of carotenoids and increased thallus density. Compared to the clean site, the sites with enhanced deposition were associated in P. glauca with year-round higher tissue concentrations of N, S, K, and Na; higher concentrations of total chlorophyll and carotenoids; higher OD435/415 ratios; higher CO2 uptake and lower thallus density in summer; and a general absence of other sensitive lichens. These results indicate that moderate levels of fertilizing air pollutants can stimulate carbon uptake and provide protection against chlorophyll degradation in air pollution-tolerant lichens of the Pacific Northwest, especially during the dry summer season.
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PMID:Effects of season and low-level air pollution on physiology and element content of lichens from the U.S. Pacific Northwest. 1586 42

Wet deposition is one of the important sources of nitrogen input into the ecosystem. It also contributes to rain acidity in some environments. In this study we reported the annual as well as seasonal trends of nitrogen wet deposition at three locations in Thailand: Bangkok, Chiang Mai and Nan. Comparison of nitrogen wet deposition between in rural and in the urban areas was also made. Daily rainfall was measured and monthly rainwater was collected for nitrogen analysis during 1999-2002. The average NO3- concentration in rainwater collected from the rural sites (60 km from urban area) was around 0.2-0.3 mg L(-1), while that from the urban areas of Chiang Mai and Nan cities it was 0.4-0.5 mg L(-1). NH4+ concentration in rainwater showed the similar ranges to that of NO3-, except at Nan where concentration was not significantly different between the urban and rural sites. On the other hand, the average concentrations of NO3- were higher at Bangkok site than other sites, while concentration of NH4+ was almost the same between Chiang Mai and Bangkok. Wet deposition of NO3- at the rural sites of Chiang Mai and Nan ranged from 2.1 to 3.2 kg N ha(-1) yr(-1), while at the urban sites this ranged from about 6 kg N ha(-1) yr(-1) in Chiang Mai and Nan Cities to 8.6 kg N ha(-1) yr(-1) in Bangkok. Wet deposition of NH4+ at the rural sites of Chiang Mai and Nan was about 2.4 to 3.6 kg N ha(-1) yr(-1) and at the urban sites of Chiang Mai, Nan and Bangkok this was 7.7, 4.9 and 8.1 kg N ha(-1) yr(-1), respectively. Thus, it was concluded that wet deposition of both nitrogen species was significantly higher at the urban sites than at the rural sites.
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PMID:Three-year monitoring results of nitrate and ammonium wet deposition in Thailand. 1586 76

Seasonal variations in the chemical characteristics of wet and bulk deposition samples collected in Erzurum were investigated for the period March 2002-January 2003. Major cations (Ca2+, K+, Mg2+) and major anions (SO4(2-),NO3-) were determined in bulk and wet deposition samples; pH was also measured in wet deposition. The average pH of the wet deposition at Erzurum was 6.6 due to extensive neutralization of the acidity. A strong relationship between pH and SO4(2-) concentrations was observed in all seasons; however, only a weak relationship was found between pH and NO3-. On a seasonal basis, the correlation between Ca2+ and SO4(2-) concentrations was stronger in winter than in summer. Seasonal variations of ions were examined in both wet and bulk deposition samples. Although maximum concentrations of anions generally occurred during winter and spring, cation concentrations peaked in summer for both wet and bulk deposition. Results indicated that Ca2+ was the dominant cation and SO4(2-) the dominant anion in all deposition samples at Erzurum. Even though correlations among the crustal ions (calcium, magnesium and potassium) were high, the relationship between anthropogenic ions (sulfate and nitrate) was less clear in bulk deposition.
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PMID:Composition of wet and bulk deposition in Erzurum, Turkey. 1589 42

Seventeen fog events were sampled in Baton Rouge, Louisiana during 2002-2004 as part of characterizing wet deposition by fogwater in the heavily industrialized corridor along the Louisiana Gulf Coast in the United States. These samples were analyzed for chemical characteristics such as pH, conductivity, total organic and inorganic carbon, total metals and the principal ion concentrations. The dominant ionic species in all samples were NH4+, NO3-, Cl- and SO4(2-). The pH of the fogwater sampled had a mean value of 6.7 with two cases of acidic pH of 4.7. Rainwater and fogwater pH were similar in this region. The acidity of fogwater was a result of NO3- but partly offset by high NH4+. The measured gaseous SO2 accounted for a small percentage of the observed sulfate concentration, indicating additional gas-to-particle conversion of SO2 to sulfate in fogwater. The gaseous NOx accounted for most of the dissolved nitrate and nitrite concentration in fogwater. The high chloride concentration was attributable to the degradation of chlorinated organics in the atmosphere. The metal composition was traced directly to soil-derived aerosol precursors in the air. The major metals observed in fogwater were Na, K, Ca, Fe, Al, Mg and Zn. Of these Na, K, Ca and Mg were predominant with mean concentrations > 100 microM. Al, Fe and Zn were present in the samples, at mean concentrations < 100 microM. Small concentrations of Mn (7.8 microM), Cu (2 microM), Pb (0.07 microM) and As (0.32 microM) were also observed in the fogwaters, and these were shown to result from particulates (PM2.5) in the atmosphere. The contribution to both ions and metals from the marine sources in the Louisiana Gulf Coast was minimal. The concentrations of all principal ionic species and metals in fogwater were 1-2 orders of magnitude larger than in rainwater. Several linear alkane organic compounds were observed in the fogwater, representing the contributions from petroleum products at concentrations far exceeding their aqueous solubility. A pesticide (atrazine) was also observed in fogwater, representing the contribution from the agricultural activities nearby.
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PMID:Monitoring of fogwater chemistry in the gulf coast urban industrial corridor: Baton Rouge (louisiana). 1630 81

Soluble aerosols are measured at Guangdong and Hainan Provinces of southern China. The measured chemical composition of aerosols includes F-, Cl-, NO3-, SO4=, Na+, NH4+, K+, Ca2+, and Mg2+. The locations of measurements include a mega city (Guangzhou), a medium city along the coastline (Haiko), a small city along the coastline (Shanya), and a remote island site in the South China Sea (Yongxing island). The results reveal that aerosols in this region are complex and heterogeneous. Sulfate aerosol (SO4=) has the highest concentrations in Guangzhou (approximately 41% of total soluble aerosol mass), suggesting that anthropogenic activities (e.g., coal burning) play important roles in controlling aerosol concentrations in Guangzhou. By contrast, the concentrations of chlorine (Cl-) and sodium (Na+) are higher in Yongxing than in Guangzhou, indicating that the sea salt is the dominant aerosol in this marine environment site. In the medium (Haiko) and small (Shanya) city sites, the effects of anthropogenic and marine activities on aerosols fall in between the values in the mega city and the remote island site. The measured ratio of Cl-/Na+ shows that the ratio is less than 1.16 in all observation sites. The ratio in the Guangzhou city, the Haiko city, the Shanya city, and the Yongxing island is 0.52, 0.91, 0.24, and 0.53, respectively, indicating that significantly heterogeneous chemical reactions occur on sea salt particles. Unlike those in Europe and North America, there are high concentrations of calcium (Ca+) in all observation sites. The percentage of calcium mass to the measured total soluble aerosols mass is 21, 32, 34, and 30 at Guangzhou, Haiko, Sanya, and Yongxing, respectively. The calculations show that calcium plays an important role in neutralizing aerosols. The calculated "cation/anion" (summation operator[ion+]/summation operator[ion-]) ratio is 2.5, 2.5, 3.2, and 2.1, at Guangzhou, Haiko, Shanya, and Yongxing, respectively. The high "cation/anion" ratios suggest that SO4=, NO3-, and Cl- are neutralized, and the aerosols as a whole (internally mixed), appear to be in an alkaline mode in this region. However, without taking into account for calcium, the calculated "cation/anion" ratio reduces to 1.2, 0.98, 1.3, and 0.8 at Guangzhou, Haiko, Sanya, and Yongxing, respectively. The property of aerosols switches from an alkaline mode to an acidity mode at the Haiko and Yongxing sites.
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PMID:Chemical characterizations of soluble aerosols in southern China. 1640 82


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