Phosphorus Inputs to Lake Simcoe from 1990 to 2003: Declines in Tributary Loads and Observations on Lake Water Quality

Total phosphorus (TP) inputs to Lake Simcoe have led to hypolimnetic dissolved oxygen (DO) depletion and loss of cold water fish habitat. Since 1990, efforts have been made to reduce the total TP input to the lake below a defined target of 75 t/year, which was predicted to lead to reductions in spring TP concentration and improvements in end-of-summer hypolimnetic DO concentrations. The total TP load to the lake during the most recent period of record (1998/99-2003/04) ranged from 53 to 76 t/yr and averaged 67 t/yr, compared to an average of 114 t/yr estimated between 1990/91 and 1997/98 (range 85-157 t/yr). Reductions in TP loads from the catchment via tributary discharge (∼26 t) accounted for the majority of the decrease in total load between the two time periods. Total P concentrations decreased significantly in four out of six long-term monitored tributaries; however, concentrations in all six tributaries remain above the level recommended to avoid nuisance plant growth (30 μg/L). Although TP loads to the lake are currently below the target 75 t/yr, excessive growths of filamentous algae and macrophytes continue to be a problem in the nearshore zone. End-of-summer minimum hypolimnetic DO concentrations (average 4.3 mg/L, 1998/99-2003/04) remain substantially below the level (7 mg/L) that is considered protective of lake trout. Efforts to reduce TP loads to the lake therefore need to continue.     

Heat transfer mechanisms in gas fluidized beds. Part 3: Heat transfer in circulating fluidized beds

Part 1 of this contribution reported on the effects of system properties on heat transfer between heating or cooling surfaces and bubbling fluidized beds. This investigation produced four correlations which define the respective maximum heat transfer. Part 2 of this study suggests that the heat transfer between exchanger surfaces and bubbling fluidized beds depends on superficial gas velocity, expressed as dimensionless excess gas velocity. The present paper shows that heat transfer coefficients in circulating fluidized beds can be predicted by evaluation of a state diagram, which combines three dimensionless groups: Nusselt number, Archimedes number and a dimensionless pressure gradient. A comparison of coal combustion experiments with own cold model measurements indicates that the radiative component of heat transfer coefficients is only evident at very low dimensionless pressure gradients.     

FODA — the formal specification of ODA document structures and its use as a basis for conformance testing

The Office Document Architecture (ODA) is an International Standard which is developed by TC 97/sc 18 of the International Organization for Standardization (ISO) in close collaboration with CCITT's Study Group VIII and with ECMA. This paper describes the current state of a formal specification of the ODA document structures by mathematical means and its use for conformance specification and conformance testing.     

Near-wall porosity characteristics of fixed beds packed with wood chips

Packed beds of fuel wood chips are commonly found in thermal conversion processes such as combustion or gasification. Wood chips in particular are mostly used as fuel for small-scale domestic heating boilers but also for commercial-scale combustion units. The characterization of spatial voidage distribution inside the wood chip beds is of great importance for flow and reactor modelling. This study focuses on the radial porosity variations of cylindrical beds of three different types of commercially available wood chips including chips classified as G30 size class. The conventional technique of consolidating packed beds with a resin was chosen as the experimental procedure. The radial voidage distribution in different cylindrical beds is determined by image analysis of sections of the solidified packings. Additionally, a packing of monosized spheres was investigated in order to assess the selected procedure in comparison with widely available literature data for spheres. The results are discussed and summarized in a mathematical expression correlating the radial voidage distribution depending on average wood chip size, packing core porosity and dimensionless distance from the tube wall.     

IR spectroscopic study of Pt/Kl zeolites using adsorption of CO as a molecular probe

FTIR spectra of CO adsorbed on Pt/KL catalysts show that the relative band intensities and the total dispersion markedly depend on the catalyst preparation method (ion exchange, incipient wetness impregnation or co-impregnation with KCl). The CO stretching frequency of the dominant band for linear CO is shifted to higher wavenumbers, parallel with the proton concentration in the reduced catalyst, which is derived independently from the intensity of the IR bands of the OH groups. The results are in accordance with the model that electron-deficient platinum particles are platinum-proton adducts.On leave from: N.D. Zelinsky Institute of Organic Chemistry, Academy of Sciences, Moscow, USSR.     

6-Phospho-{beta}-galactosidases of Gram-positive and 6-phospho-{beta}-glucosidase B of Gram-negative bacteria: comparison of structure and function by kinetic and immunological methods and mutagenesis of the lacG gene of staphylococcus aureus

The 6-phospho-ß-galactosidase of Staphylococcus aureus,Lactococcus lactis and Lactobacillus casei and 6-phospho-ßglucosidaseB of Escherichia coli build a subfamily inside a greater enzymefamily, named the glycosal hydrolase family 1, which, hi addition,contains nine ß-glycosidases of different origins.Kinetic and immunological evidence is provided in this reportwhich strengthens the relationship of the four 6-phospho-ß-glycosidases.It is shown that the 6-phospho-ß-galactosidases and6-phospho-ß-glucosidase B are able to split aromaticß-galactoside phosphates and ß-glucosidephosphates. The turnover numbers of hydrolysis of substrateswith different epimerization at C-4 of the glycon vary up to15-fold only. Two polydonal antisera, one derived against thenative 6-phospho-ß-galactosidase from S.aureus andthe other derived against the 6-phospho-ß-glucosidaseB, cross-reacted with both enzymes. Peptides of the proteinswere separated by reverse phase HPLC. The cross-reacting peptideswere sequenced and shown to be localized at almost the sameposition in the aligned primary structures of both enzymes.An insertion of nine amino adds near these antigenic domainsis unique for the 6-phospho-ß-glycosidases and missingwithin the sequences of the ß-glycoside-specific membersof the family. The lacG gene of a 6-phospho-ß-galactosidasenegative S.aureus mutant was doned into E.coli and sequenced.In the totally inactive mutant protein only the glycine at position332 was changed to an arginine. This amino acid is part of thesequence insertion near the antigenic domain reacting with bothantisera. These data support the assumption that the regionis of great importance for the function of the enzymes and thatit is possible it determines the specificity of the phosphorylatedform of the substrates. In addition, the 6-phospho-ß-galactosidaseof S.aureus was modified by sitedirected mutagenesis of thecorresponding lacG gene hi order to replace residues Glul60and Glu375, which were suspected of being involved hi the generalacid catalysis of substrate hydrolysis, with glutamine residues.The mutant protein 160EQ retained some catalytic activity whilethe protein 375EQ was totally inactive. Glu375 is the activesite nudeophile of the 6-phospho-ß-galactosidase ofS.aureus. It is located in the sequence motif ENG where Glu358was identified as the catalytkally active nudeophile hi theß-glucosidase of Agrobacterium.