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Recent severe ice storms across the United States severely damaged trees resulting in extensive electrical power outages. Furthermore, trees and branches can fall on nearby roads, blocking traffic flow and reducing the safety of drivers. In this study, trees subjected to ice loads were analyzed using the finite element method and Monte Carlo simulation to develop analytical fragility curves. Two-dimensional, fractal trees were constructed with randomly generated geometric and mechanical parameters for four deciduous tree species: Acer saccharum, Tilia americana, Fagus grandifolia, and Quercus alba. Two load case scenarios were considered – with and without the effects of leaves – which were then subjected to varying ice accumulation thicknesses. The resulting fragility curves suggest that leaves have a substantial impact on tree branch damage under ice loads, which is significant because of the increase in unseasonably early ice storms due to climate change. [ABSTRACT FROM AUTHOR]

EDTA, a common chelating agent, is becoming a major organic pollutant in the form of metal-EDTA complexes in surface waters, partly due to its recalcitrance to biodegradation. Even an EDTA-degrading bacterium, BNC1, does not degrade stable metal-EDTA complexes. In the present study, an ABC-type transporter was identified for possible uptake of EDTA because the transporter genes and the EDTA monooxygenase gene were expressed from a single operon in BNC1. The ABC-type transporter had a periplasmic-binding protein (EppA) that should confer the substrate specificity for the transporter; therefore, EppA was produced in Escherichia coli, purified, and characterized. EppA was shown to bind free EDTA with a dissociation constant as low as 25 nM by using isothermal titration calorimetry. When unstable metal-EDTA complexes, e.g., (Mg-EDTA)[2.sup.-], were added to the EppA solution, binding was also observed. However, experimental data and theoretical analysis supported EppA binding only of free EDTA. When stable metal-EDTA complexes, e.g., (Cu-EDTA)[2.sup.-], were titrated into the EppA solution, no binding was observed. Since EDTA monooxygenase in the cytoplasm uses some of the stable metal-EDTA complexes as substrates, we suggest that the lack of EppA binding and EDTA uptake are responsible for the failure of BNC1 cells to degrade the stable complexes.

The seventh book [of the Writings] is Dabreiamin, that is 'Words of the days,' which we are able to call more specifically a chronicle ([TEXT NOT REPRODUCIBLE IN ASCII]) of [...]

Researchers have isolated and characterized an enzyme from the EDTA-degrading bacterium BNC1. Iminodiacetate oxidase appears to be the second enzyme in the pathway for degrading both EDTA and NTA.

Researchers report the isolation of an eight-gene cluster from the bacterium BNX1 that encodes some of the enzymes that degrade EDTA. Two of the gene products were identified as a reduced flavin mononucleotide-utilizing monooxygenase and an NADH:flavin mononucleotide oxidoreductase. The others include a transport system, a regulatory gene, and an iminodiacetate oxidase.

This study characterised the relationship between speech intelligibility and quality in listeners with hearing loss for a range of hearing-aid processing settings and acoustic conditions. Binaural speech intelligibility scores and quality ratings were measured for sentences presented in babble noise and processed through a hearing-aid simulation. The intelligibility–quality relationship was investigated by (1) assessing the effects of experimental conditions on each task; (2) directly comparing intelligibility scores and quality ratings for each participant across the range of conditions; and (3) comparing the association between signal envelope fidelity (represented by a cepstral correlation metric) and intelligibility and quality. Participants were 15 adults (7 females; age range 59–81 years) with mild to moderately severe sensorineural hearing loss. Intelligibility and quality showed a positive association both with each other and with changes to signal fidelity introduced by the entire acoustic and signal-processing system including the additive noise and the hearing-aid output. As signal fidelity decreased, quality ratings changed at a slower rate than intelligibility scores. Individual psychometric functions were more variable for quality compared to intelligibility. Variability in the intelligibility–quality relationship reinforces the importance of measuring both intelligibility and quality in clinical hearing-aid fittings. [ABSTRACT FROM AUTHOR]

Synthetic chelating agents are used in a broad variety of applications such as in household cleaners, water treatment, rubber/metal processing and pulp/paper treatment. Roughly 70% of all chelating agents used globally are aminopolycarboxylic acids primarily EDTA, DTPA and NTA. A study was conducted to investigate the biochemistry of EDTA degradation by bacterium BNC1. The purification and characterization of EDTA monooxygenase that catalyzes the initial step of EDTA degradation by BNC1 is described.

The reverse transcriptase/polymerase chain reaction (RT-PCR) process is examined with particular attention to the common observation that control DNA reaction mixtures with RT do not provide DNA amplification during PCR while control DNA reaction mixtures without RT do not inhibit PCR. The findings indicate that the RT interaction with the specific mRNA or cDNA template mediates RT inhibition of the PCR and that such inhibitory effect is influenced by template concentration.

Metal-reducing bacterium Shewanella alga strain BrY enzymatically reduces cobaltIIIEDTA- to CoIIEDTA2- with a 1:1 stoichiometry. Radioactive 60CoIIIEDTA- appeared to have no effect on the reduction of CoIIIEDTA- at concentrations exceeding figures recorded in contaminated environments. The direct reduction of CoIIIEDTA- by microorganisms and geochemical oxidation of CoIIEDTA2- by manganese-(IV) oxides could be important factors in the fate and transport of 60CoIIIEDTA2- in the environment.

Nitriloacetic acid (NTA) is a synthetic chelating agent that is used for decontaminating nuclear materials and processing nuclear waste. However, the ability of NTA to form complexes with a variety of radionucleotides and metal ions poses risks to the environment. An approach that has been proposed to reduce these risks promotes adsorption of NTA to soils and sediments by the addition of Chelatobacter heintzii. A model system to investigate the rates of NTA degradation is presented.

Aqueous speciation modeling can be applied in predicting the rate of nitrilotriacetate (NTA) degradation by NTA monooxygenase for complex systems containing multiple species. This was gleaned from an investigation of the impact of aqueous speciation of NTA on enzymatic degradation. Results indicate that the rate of transport into the cell limits the biodegradation of various metal-NTA complexes and that NTA-Mo may be useful for degradaing NTA-metal complexes which are resistant to degradation by whole cells.

A study was conducted on the effect of nitrilotriacetic acid (NTA) aqueous speciation on the acid's biodegradation. The NTA degrading bacterium Chelatobacter heintzii was used in batch experiments to test the hypothesis that NTA-complexing metals having larger thermodynamic stability constants degrade at a slower pace compared with NTA complexes having metals with smaller stability constants. The degradability of the metal-NTA complexes was observed to be linked to their lability or relative rates of formation of HNTA2-.

Various problems and their solutions are presented, to stimulate college students and mathematics teachers. Topics covered include an isosceles triangle, order in modulus 10, square circumscription around a parallelogram, self-dual graphs, self-complementary graphs and a sum of (ln 3)/16. The use of sine and cosine laws to give double angle formulas is also shown.

Individual soil variables are spatially dependent and the variables are systematically correlated in the landscape. The predominant shrub in the inter-mountain western US, big sagebrush, is related with multiple-variable indicator transform resource islands and adjacent to the big sagebrush. There are maximum chances for encountering zones of above-median resources.

Proposed problems and the solutions to problems from earlier issues are presented. New problems include quadrilateral vertices, distance maximization, natural numbers for a perfect square, a summation and right triangles. Solutions include a product sum, inequality, Pythagorean polygonal triples, a Diophantine equation and trigonometric integral inequalities.

Technologies involving the bioremediation of soils and groundwater contaminated with hazardous organic compounds have emerged since microorganisms were found to effectively decompose these contaminants. Methods involving the elimination of these contaminants in situ or by transporting and treating the contaminated sample in a bioreactor were discussed at the Second International Symposium 'In Situ and On-Site Bioreclamation' in San Diego, CA, in Apr 1993. The success of bioremediation depends on the innovative contributions of different disciplines.

An assessment of the effects of environmental release of lignin peroxidase- overexpressing genetically engineered microorganisms (GEMS) and other GEMS in soils is discussed. A recombitant Streptomyces lividans TK23.1 was discharged into soil in flask- andmicrocosm-scale studies. Three independent laboratories were used for differentparts of the research. Results show that the release of the strain into soil significantly affected some environmental parameters. However, these effects were found to be ecologically insignificant.

Five problems are proposed without solutions and five more problems are given with solutions. All are provided by the readers whose names, schools, home cities, states and countries mentioned. The problems concern a quadrilateral, a triangle, the natural logarithmic function, arithmetic progressions, a limit, singularity of matrices, convergence, a sum of roots, a geometric inequality for triangles and the order of a matrix.