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PubMed2005

The exploration of potassium ferrate(VI) as a disinfectant/coagulant in water and wastewater treatment.

This paper aims to explore potassium ferrate(VI) (K2FeO4) as an alternative water treatment chemical for both drinking water and wastewater treatment. The performance of potassium ferrate(VI) was evaluated in comparison with that of sodium hypochlorite (NaOCl) and that of NaOCl plus ferric sulphate (FS) or alum (AS). The dosages of ferrate(VI), NaOCl and FS/AS and sample pH values were varied in order to investigate the effects of these factors on the treatment performance. The study demonstrates that in drinking water treatment, ferrate(VI) can remove 10-20% more UV(254)-abs and DOC than FS for the same dose compared for natural pH range (6 and 8). The THMFP was reduced to less than 100 microg l(-1) by ferrate(VI) at a low dose. In addition to this, ferrate(VI) can achieve the disinfection targets (>6 log10 inactivation of Escherichia coliform (E. coli)) at a very low dose (6 mg l(-1) as Fe) and over wide working pH in comparison with chlorination (10 mg l(-1) as Cl2) plus coagulation (FS, 4 mg l(-1) as Fe). In wastewater treatment, ferrate(VI) can reduce 30% more COD, and kill 3log10 more bacteria compared to AS and FS at a similar or even smaller dose. Also, potassium ferrate(VI) can produce less sludge volume and remove more pollutants, which could make sludge treatment easier.

Alum Compounds↗
PubMed1985

Cell detachment and growth of fibroblasts as parameters for cytotoxicity of inorganic metal salts in vitro.

Eight inorganic metal compounds (AlCl3, Al(OH)3 gel, Al(OH)3 salt, SnCl2, ZnSO4, K2Cr2O7, CdCl2, HgCl2) were tested for their cytotoxic effect on an established hamster fibroblast line (BHK-21/C13) in vitro using a cell detachment assay and two different growth assays, the cloning efficiency and the cell number after 2 days subconfluent culture as parameters. The test conditions for these assays were optimized, including incubation period, application of test substance, growth conditions and data analysis. Aluminum, zinc and tin compounds showed low cytotoxic effects when compared to potassium, cadmium and mercuric compounds. Potassium dichromate was highly toxic in both growth assays (0.0001-0.01 mM, with a clear dependency on the incubation time), whereas it proved to be only slightly toxic in the detachment assay (0.1-5 mM). Cadmium and mercuric chlorides were the most toxic compounds in the growth (0.00001-0.001 mM) and the cell detachment assays (0.01-0.1 mM). Variable incubation periods barely affected the cytotoxicity of mercuric chloride. Ranking of these cytotoxicity data was found to be identical to the ranking of LD50 values (oral, rat) as well as to the ranking according to threshold limit values for human workroom environment, and of human eye irritation data.

Aluminum↗
PubMed1997

Compositional dependence of bioactivity of glasses in the system Na2O-K2O-MgO-CaO-B2O3-P2O5-SiO2.

The bioactivity, i.e., bone-bonding ability, of 26 glasses in the system Na2O-K2O-MgO-CaO-B2O3-P2O5-SiO2 was studied in vivo. This investigation of bioactivity was performed to establish the compositional dependence of bioactivity, and enabled a model to be developed that describes the relation between reactions in vivo and glass composition. Reactions in vivo were investigated by inserting glass implants into rabbit tibia for 8 weeks. The glasses and the surrounding tissue were examined using scanning electron microscopy (SEM), light microscopy, and energy-dispersive X-ray analysis (EDXA). For most of the glasses containing < 59 mol % SiO2, SEM and EDXA showed two distinct layers at the glass surface after implantation, one silica-rich and another containing calcium phosphate. The build-up of these layers in vivo was taken as a sign of bioactivity. The in vivo experiments showed that glasses in the investigated system are bioactive when they contain 14-30 mol % alkali oxides, 14-30 mol % alkaline earth oxides, and < 59 mol % SiO2. Glasses containing potassium and magnesium bonded to bone in a similar way as bioactive glasses developed so far.

Animals↗
PubMed2002

A virtual screening method for prediction of the HERG potassium channel liability of compound libraries.

A computer-based method has been developed for prediction of the hERG (human ether-à-go-go related gene) K(+)-channel affinity of low molecular weight compounds. hERG channel blockage is a major concern in drug design, as such blocking agents can cause sudden cardiac death. Various techniques were applied to finding appropriate molecular descriptors for modeling structure-activity relationships: substructure analysis, self-organizing maps (SOM), principal component analysis (PCA), partial least squares fitting (PLS), and supervised neural networks. The most accurate prediction system was based on an artificial neural network. In a validation study, 93 % of the nonblocking agents and 71 % of the hERG channel blockers were correctly classified. This virtual screening method can be used for general compound-library shaping and combinatorial library design.

Cation Transport Proteins↗
PubMed1998

[Math-model of efficient cultivation of Angelica sinensis].

Using two-time general rotation-constitution design, the math-mdele has been founded about Angelica sinensis prodution efficiency and quantity of nitrogen, phosphorus and potassium to use by doing experiments in many different spots and production demonstration for testing and verifying. Accordin to the modle, computer is used to simulate the better, through which people can get fresh Chinese angelica over 500 Kg per mu and also net income over 500 yuan per mu. It shows that this is the best combination. 95% density riliability for this plan is 6860-7600 plants, pure nitrogen 18.75-22.2 Kg, P2O5 9.1-11.1 Kg and K2O 4.46-5.37 Kg One mu. Proportion for nitrogen, phosphorus, potassium is 1:0.49:0.24.

Angelica↗
PubMed2003

(K4Li4)Al8Ge8O32.8H2O: an Li+-exchanged potassium aluminogermanate with the zeolite gismondine (GIS) topology.

The title compound, lithium potassium dialuminium digermanium octaoxide dihydrate, (K,Li)-(Al,Ge)-GIS (GIS is gismondine), is the result of a 50% Li(+) exchange into the K-(Al,Ge)-GIS structure. The (K,Li)-(Al,Ge)-GIS structure was determined from a 4 x 4 x 2 micro m octahedral single crystal at the ESRF synchrotron X-ray source. The ion exchange results in a symmetry transformation from I2/a for K-(Al,Ge)-GIS to C2/c for (K,Li)-(Al,Ge)-GIS. The structural change is due to disordering of K(+) ions with Li(+) ions along the [001] channel and ordering of water molecules in the [101] channels. The distance between sites partially occupied by K(+) ions increases from 2.19 (3) A in K-(Al,Ge)-GIS to 2.94 (3) A in (K,Li)-(Al,Ge)-GIS. The Li(+) ions occupy positions along the twofold axis at the intersection of the eight-membered-ring channels in a twofold coordination with water molecules. For the four closest framework O(2-) anions, the Li.O distances are 3.87 (4) A.

Journal Article↗
PubMed1999

Effect of potassium magnesium citrate on thiazide-induced hypokalemia and magnesium loss.

The study was performed to ascertain the value of potassium magnesium citrate, magnesium citrate, and potassium citrate in overcoming thiazide-induced hypokalemia and magnesium loss. Sixty-two healthy subjects were first administered hydrochlorothiazide, 50 mg/d. After 3 weeks of thiazide treatment (or earlier for potassium level </=3.5 mEq/L), they were randomized to receive one of three drugs while continuing to receive thiazide: potassium magnesium citrate (49 mEq of potassium, 24.5 mEq of magnesium), magnesium citrate (24.5 mEq/d of magnesium), or potassium citrate (49 mEq/d of potassium). Outcome measures were changes in serum potassium and magnesium levels and urinary potassium, magnesium, pH, and citrate values. All three drugs increased serum potassium concentration compared with that resulting from thiazide alone. Potassium magnesium citrate increased serum potassium levels from 3.3 +/- 0.2 to 3.8 +/- 0.3 mEq/L (P < 0.001), potassium citrate increased serum potassium levels from 3.4 +/- 0.4 to 3.9 +/-0.3 mEq/L (P < 0.001), and magnesium citrate from 3.4 +/- 0.4 to 3.7 +/- 0.3 mEq/L (P < 0.001). Potassium magnesium citrate led to a significant increase in urinary magnesium levels by the third week of supplementation (from 120 +/- 34 to 149 +/- 58 mg/d; P < 0.01) and produced a small but significant increase in serum magnesium level. Magnesium citrate significantly increased 24-hour urinary magnesium after the first week of supplementation and maintained this increase throughout the study. Potassium magnesium citrate and potassium citrate, but not magnesium citrate, significantly increased urinary pH and citrate values. Potassium magnesium citrate not only corrects thiazide-induced hypokalemia, but also may avert magnesium loss while providing an alkali load.

Adult↗
PubMed1993

Interactions in vitro of some organophosphoramidates with neuropathy target esterase and acetylcholinesterase of hen brain.

For organophosphates or phosphonates to initiate delayed neuropathy two steps are necessary: (1) progressive covalent reaction with neuropathy target esterase (NTE) to produce a form of inhibited NTE which can be reactivated by incubation with aqueous potassium fluoride (KF) and (2) progressive "aging" of inhibited NTE to a form which can no longer be reactivated by KF. However, it has been shown recently that certain N-unsubstituted organophosphoro-monoamidates (analogues of methamidophos) cause delayed neuropathy even though the inhibited NTE appeared not to have aged (Johnson et al. (1991). Arch. Toxicol., 65, 618-624). In order to study the generality of this phenomenon, we have examined some N-substituted compounds. We report in vitro studies of inhibition and reactivation and aging of both NTE and acetylcholinesterase (AChE) prior to toxicological tests. All the compounds studied were less inhibitory to both NTE and AChE in concentrated rather than in dilute suspensions of EDTA-washed brain particles without added cofactors. There was an apparent disposal of up to 100 mumoles of test compound by particles from 95 mg hen brain, which is far greater than can be explained by covalent binding. The activity is distinct from calcium-dependent "A" esterase. Several N-alkyl phosphoromonoamidates were found to be potent and selective inhibitors of NTE: second-order rate constant for O-n-pentyl N-benzylphosphoramido-fluoridate (Cmpd 6) = 5.6 x 10(7) M-1 min-1 at 37 degrees, which is about 100x higher than for acetylcholinesterase (AChE). Inhibited NTE and AChE from several chiral phosphoromono-amidates did not reactivate spontaneously (21 hours at 37 degrees). Virtually 100% reactivation by KF of AChE inhibited by phosphoromonoamidates was achieved at all times tested. Acetylcholinesterase inhibited by 2,5-dichlorophenyl N,N'-di-n-butylphosphorodiamidate was 42-56% reactivated by incubation with KF (192 mM in pH 5.2 buffer for 30 minutes at 37 degrees). We believe this is the first report of reactivation of any enzyme after inhibition by a phosphorodiamidate. For NTE inhibited by tabun (O-ethyl N-dimethylphosphoroamidocyanidate), virtually complete and rapid aging (t1/2 = 5.5-8.4 minutes) was observed. Consistent but only partial reactivation by KF was achieved 2 or more hours after inhibition of NTE by Cmpd 6 or by its 2,6-difluoro-analogue (Cmpd 7). However, a small but significant aging (approximately 15-20% loss of reactivatability) was measured soon after a 1 minute inhibition by Cmpd 7, but no further change occurred in 21 hours.(ABSTRACT TRUNCATED AT 400 WORDS)

Acetylcholinesterase↗
PubMed1995

Crystal structures of cyanide- and triiodide-bound forms of Arthromyces ramosus peroxidase at different pH values. Perturbations of active site residues and their implication in enzyme catalysis.

The structures of the cyanide and triiodide complexes of Arthromyces ramosus peroxidase (ARP) at different pH values were investigated by x-ray crystallography in order to examine the behavior of the invariant residues of arginine (Arg-52) and distal histidine (His-56) during the enzyme reaction as well as to provide the structural basis of the active site of peroxidase. The models of the cyanide complexes at pH 7.5, 5.0, and 4.0, respectively, were refined to the R-factors of 17.8, 17.8, and 18.5% using 7.0-1.6-A resolution data, and those of the triiodide complexes at pH 6.5 and 5.0 refined to 16.9 and 16.8% using 7.0-1.9-A resolution data. The structures of the cyanide complexes at pH 7.5, 5.0, and 4.0 are identical within experimental error. Cyanide ion bound to the heme in the bent conformation rather than in the tilt conformation. Upon cyanide ion binding, the N epsilon atom of His-56 moved toward the ion by rotation of the imidazole ring around the C beta-C gamma bond, but there was little conformational change in the remaining residues. The distance between the N epsilon atom of His-56 and the nitrogen atom of the cyanide suggests the presence of a hydrogen bond between them in the pH range investigated. In the triiodide complexes, one of the two triiodides bound to ARP was located at the distal side of the heme. When triiodide bound to ARP, unlike the rearrangement of the distal arginine of cytochrome c peroxidase that occurs on formation of the fluoride complex or compound I, the side chain of Arg-52 moved little. The conformation of the side chain of His-56, however, changed markedly. Conformational flexibility of His-56 appears to be a requisite for proton translocation from one oxygen atom to the other of HOO- by acid-base catalysis to produce compound I. The iron atom in each cyanide complex (low-spin ferric) is located in the heme plane, whereas in each triiodide complex (high-spin ferric) the iron atom is displaced from the plane about 0.2 A toward the proximal side.

Amino Acid Sequence↗