Uracil in human DNA from subjects with normal and impaired folate status as determined by high-performance liquid chromatography-tandem mass spectrometry.

A sensitive and selective method for determination of the uracil content in human DNA was first developed on the basis of high-performance liquid chromatography-tandem mass spectrometry. Uracil was excised from DNA using uracil DNA glycosylase. The released uracil was derivatized with 4-bromomethyl-7-methoxycoumarin, thereby forming bis-N,N'-(4-methylene-7-methoxycoumaryl)-uracil (uracil-MMC). 15N2-Uracil was used as an internal standard. The analytes were separated on an Adsorbsphere XL ODS column. A SCIEX API III tandem mass spectrometer equipped with a turbo ion-spray interface was used as the detector. Multiple reaction monitoring using the parent --> product ion combinations of m/z 489 --> 232 and 491 --> 233 were used to detect uracil-MMC and the internal standard, respectively. The detection limit for this assay is <1.0 x 10(-10) mol/L uracil, and the linearity is from 1.0 x 10(-10) to 2.5 x 10(-6) mol/L. The method was used for determination of uracil in human DNA. Our data show that the uracil levels in human DNA isolated from peripheral white blood cells did not differ between subjects with folate deficiency and subjects with normal red cell folate levels.     

Methods for Checking the Consistency of Precedence Constraints

Precedence constraints appear in mathematical models from many different fields of application and the problem of determining whether or not a set of such constraints is consistent is of rather general interest. This paper describes a number of different approaches to this problem. For each approach a survey of existing algorithms is given. An efficient algorithm, especially designed for checking the consistency of activity networks, is developed by the combination of recent graph algorithms with ideas published in the early 60's. The time of computation for this algorithm grows linearly with the number of constraints and it is faster than any other published algorithm when applied to digraphs of a certain structure.     

Specific Modulation of Protein Activity by Using a Bioorthogonal Reaction

Unnatural amino acids with bioorthogonal reactive groups have the potential to provide a rapid and specific mechanism for covalently inhibiting a protein of interest. Here, we use mutagenesis to insert an unnatural amino acid containing an azide group (Z) into the target protein at positions such that a “click” reaction with an alkyne modulator (X) will alter the function of the protein. This bioorthogonally reactive pair can engender specificity of X for the Z‐containing protein, even if the target is otherwise identical to another protein, allowing for rapid target validation in living cells. We demonstrate our method using inhibition of the Escherichia coli enzyme aminoacyl transferase by both active‐site occlusion and allosteric mechanisms. We have termed this a “clickable magic bullet” strategy, and it should be generally applicable to studying the effects of protein inhibition, within the limits of unnatural amino acid mutagenesis.     

Validation and modification of modeling thermally activated building systems (TABS) using EnergyPlus

EnergyPlus (EP) integrates a low temperature radiant system module to evaluate thermal performance of radiant systems such as thermally activated building systems (TABS), but the assumptions in this module neglect thermal resistance of the pipe and thermal resistance between the pipe exterior surface and the pipe level, which may result in the inaccurate evaluation of TABS in terms of surface temperature and surface heat flow. In this paper, in order to validate this module used in EP, steady and transient heat transfer processes of TABS in buildings were studied by analytical solution, two-dimensional numerical simulation and EP simulation. The comparison shows that the assumptions indeed result in a largely overestimated cooling and heating capacity of TABS. In order to improve this radiant module, a simple solution of introducing a no mass material layer with the neglected thermal resistances to both sides of the pipe level was proposed. With this method, the results of mean surface temperature and mean heat flow show good agreement with that from analytical solution as well as numerical simulation. Furthermore, the results of the simulation coupling the modified module with room systems show very small deviation from the results found in the literature. In addition, the application of the modified module in a hollow core concrete deck structure with TABS was investigated.     

The complex aerodynamic footprint of desert locusts revealed by large-volume tomographic particle image velocimetry

Particle image velocimetry has been the preferred experimental technique with which to study the aerodynamics of animal flight for over a decade. In that time, hardware has become more accessible and the software has progressed from the acquisition of planes through the flow field to the reconstruction of small volumetric measurements. Until now, it has not been possible to capture large volumes that incorporate the full wavelength of the aerodynamic track left behind during a complete wingbeat cycle. Here, we use a unique apparatus to acquire the first instantaneous wake volume of a flying animal''s entire wingbeat. We confirm the presence of wake deformation behind desert locusts and quantify the effect of that deformation on estimates of aerodynamic force and the efficiency of lift generation. We present previously undescribed vortex wake phenomena, including entrainment around the wing-tip vortices of a set of secondary vortices borne of Kelvin–Helmholtz instability in the shear layer behind the flapping wings.     

ENDOW (efficient development of offshore wind farms): modelling wake and boundary layer interactions

While experience gained through the offshore wind energy projects currently operating is valuable, a major uncertainty in estimating power production lies in the prediction of the dynamic links between the atmosphere and wind turbines in offshore regimes. The objective of the ENDOW project was to evaluate, enhance and interface wake and boundary layer models for utilization offshore. The project resulted in a significant advance in the state of the art in both wake and marine boundary layer models, leading to improved prediction of wind speed and turbulence profiles within large offshore wind farms. Use of new databases from existing offshore wind farms and detailed wake profiles collected using sodar provided a unique opportunity to undertake the first comprehensive evaluation of wake models in the offshore environment. The results of wake model performance in different wind speed, stability and roughness conditions relative to observations provided criteria for their improvement. Mesoscale model simulations were used to evaluate the impact of thermal flows, roughness and topography on offshore wind speeds. The model hierarchy developed under ENDOW forms the basis of design tools for use by wind energy developers and turbine manufacturers to optimize power output from offshore wind farms through minimized wake effects and optimal grid connections. The design tools are being built onto existing regional‐scale models and wind farm design software which was developed with EU funding and is in use currently by wind energy developers. Copyright © 2004 John Wiley & Sons, Ltd.     

Promoting Bacillus cereus spore germination for subsequent inactivation by mild heat treatment

Sublethal heat treatment may activate dormant spores and thereby potentiate the conversion of spores to vegetative cells. As the germinated spore is known to possess lower heat resistance than its dormant counterpart, it has been postulated that double heat treatment, i.e., spore heat activation followed by germination and then by heat inactivation, can be used to control spores in foods. Production of refrigerated processed foods of extended durability often includes more than one heat treatment of the food components. This work simulates conventional heat treatment procedures and evaluates double heat treatment as a method to improve spore control in model food matrixes of meat broth and cream sauce. Bacillus cereus NVH 1230-88 spores were supplemented in food model matrixes and heat activated at 70°C and then heat inactivated at 80 or 90°C. The samples were held at 29 to 30°C for 1 h between primary and secondary heat treatments, to allow spore germination. Nutrients naturally present in the food matrixes, e.g., amino acids and inosine, could act as germinants that induce germination. The levels of germinants could be too low to produce effective germination within 1 h. Following primary heat treatment, some samples were therefore supplemented with a combination of L-alanine and inosine, a germinant mixture known to be effective for B. cereus spores. In both matrixes, a combination of double heat treatment (heat activation, germination, and inactivation) and addition of germinants gave a reduction in spore counts equivalent to or greater than that obtained with a single heat treatment for 12 min at 90°C. Addition of germinants was essential to induce effective germination in cream sauce during 1 h at 29 to 30°C, and germinants were therefore a crucial supplement to obtain an effect of double heat treatment in this matrix. These data will be valuable when setting up temperature-time-germinant combinations for an optimized spore reduction in mild-heat-treated foods.     

Alcohol, psychoactive drugs and fatal road traffic accidents in Norway: a case-control study

A case–control study was conducted on 204 drivers fatally injured in road traffic accidents in south-eastern Norway during the period 2003–2008. Cases from single vehicle accidents (N = 68) were assessed separately. As controls, 10 540 drivers selected in a roadside survey in the same geographical area during 2005–2006 were used. Blood samples were collected from the cases and oral fluid (saliva) samples from the controls. Samples were analysed for alcohol, amphetamines, cannabis, cocaine, opioid analgesics, hypnotics, sedatives and a muscle relaxant; altogether 22 psychoactive substances. Equivalent cutoff concentrations for blood and oral fluid were used. The risk for fatal injury in a road traffic accident was estimated using logistic regression adjusting for gender, age, season of the year, and time of the week. The odds for involvement in fatal road traffic accidents for different substances or combination of substances were in increasing order: single drug < multiple drugs < alcohol only < alcohol + drugs. For single substance use: medicinal drug or THC < amphetamine/methamphetamine < alcohol. For most substances, higher ORs were found when studying drivers involved in single vehicle accidents than for those involved in multiple vehicle accidents, but confidence intervals were wider.     

Adsorption of glyphosate on goethite: molecular characterization of surface complexes

As a component of herbicides, the fate of glyphosate (PMG) in the environment is of significant interest. The nature of PMG adsorption on mineral surfaces plays a significant role in the degradation of PMG. The adsorption of PMG on goethite (alpha-FeOOH) has been studied as a function of pH and PMG concentration. Adsorption was investigated with batch experiments, attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), and X-ray photoelectron spectroscopy (XPS). The N 1s line in XPS spectra showed deprotonation of the amine group of PMG (NH2+) with increasing pH. IR analyses showed no evidence for the interaction of PMG's carboxylate group with the goethite surface, while the phosphonate group formed inner-sphere complexes. There is evidence for intramolecular hydrogen bonding between NH2+ and both the carboxylate and the phosphonate groups at low pH. Intramolecular hydrogen bonding is lost when the amine group is deprotonated, and the trend in intramolecular hydrogen bonding between NH2+ and phosphonate shows that PMG adsorbs via predominantly monodentate complexation. A minor quantity of bidentate complexes is thought to form both at near-neutral pH and when the surface concentration of PMG is low. While the phosphonate group of PMG binds directly, the carboxylate group remains relatively "free" from complexation with goethite, leaving it subject to degradation and/or complexation with metal ions present in the environment.