Modeling of thermal desorption of Hg from activated carbon

Activated carbon adsorbs mercury from combustion flue gas, and this is exploited for the control of mercury emissions from coal-fired boilers and incinerators. The reaction pathway for the adsorption of mercury on activated carbon appears to be complex. The form of mercury that is adsorbed on activated carbon is likewise unknown. Experiments were carried out on vaporization of mercury compounds on non-treated, non-halogenated activated carbon in order to identify characteristics of the mercury compound adsorbed on the carbon and to assess the thermal stability of mercury once adsorbed. In these experiments, a solid material was heated in a boat in flowing air in the Ohio Lumex pyrolysis furnace. As the temperature of the boat was ramped up, the amount of mercury transferred to the gas was measured. A transient heat-transfer model was developed and coupled with a mercury vaporization model to predict, respectively, the heat-up and evolution of mercury from samples in the pyrolysis furnace. The model was able to reproduce the trends in the experimental observations, particularly the location of the peaks. The activation energy of mercury desorption in the model was used to distinguish between two different mercury species. The model also illustrated the effect of the thermal profile on mercury evolution in the pyrolysis furnace.     

Induction of CYP1A and DNA damage in the fathead minnow (Pimephales promelas) following exposure to biosolids

Biosolids (treated sewage sludge) are increasingly disposed of on land. Thus particle-sorbed and dissolved constituents have the potential to enter nearby watersheds. Although organic contaminants are known to be present in biosolids these are not currently regulated and little data exist on their potential toxicity to aquatic organisms. We exposed Pimephales promelas to two concentrations of biosolids (0.5 and 2.5 g l(-1)) for 28-days (static-renewal) and characterized contaminants present and the extent of CYP1A and DNA damage induction at various time points. Many organic contaminants were detected in the biosolids, with polycyclic aromatic hydrocarbons (PAHs) being the dominant class. Substantial levels of polybrominated diphenyl ethers (PBDEs) and nonylphenols (NPs) were also present. Significant induction of hepatic CYP1A protein compared with controls (P<0.05) was observed in both low (0.5 g l(-1)) and high (2.5 g l(-1)) exposed fish from Day 7. CYP1A levels peaked at Day 21 with 21-fold and 8-fold inductions over controls in high and low dose fish respectively. Induction of DNA damage in hepatocytes (single strand breaks as measured using the COMET assay) was observed in both exposures compared with controls on Days 14 and 28 (P<0.05). A significant correlation was found between CYP1A induction and DNA damage (Pearson correlation index, P<0.05). It is plausible that activation of PAHs may be responsible for the induction of CYP1A and resulting increase in DNA damage. Our data show the potential for detrimental effects in the event of exposure of aquatic organisms to biosolids and the need for further investigations of possible impacts due to constituents not covered by current guidelines.     

Designer reagents for mass spectrometry-based proteomics: clickable cross-linkers for elucidation of protein structures and interactions

We present novel homobifunctional amine-reactive clickable cross-linkers (CXLs) for investigation of three-dimensional protein structures and protein-protein interactions (PPIs). CXLs afford consolidated advantages not previously available in a simple cross-linker, including (1) their small size and cationic nature at physiological pH, resulting in good water solubility and cell-permeability, (2) an alkyne group for bio-orthogonal conjugation to affinity tags via the click reaction for enrichment of cross-linked peptides, (3) a nucleophilic displacement reaction involving the 1,2,3-triazole ring formed in the click reaction, yielding a lock-mass reporter ion for only clicked peptides, and (4) higher charge states of cross-linked peptides in the gas-phase for augmented electron transfer dissociation (ETD) yields. Ubiquitin, a lysine-abundant protein, is used as a model system to demonstrate structural studies using CXLs. To validate the sensitivity of our approach, biotin-azide labeling and subsequent enrichment of cross-linked peptides are performed for cross-linked ubiquitin digests mixed with yeast cell lysates. Cross-linked peptides are detected and identified by collision induced dissociation (CID) and ETD with linear quadrupole ion trap (LTQ)-Fourier transform ion cyclotron resonance (FTICR) and LTQ-Orbitrap mass spectrometers. The application of CXLs to more complex systems (e.g., in vivo cross-linking) is illustrated by Western blot detection of Cul1 complexes including known binders, Cand1 and Skp2, in HEK 293 cells, confirming good water solubility and cell-permeability.     

The Protein Environment Drives Selectivity for Sulfide Oxidation by an Artificial Metalloenzyme

Magic Mn–salen metallozyme : The design of an original, artificial, inorganic, complex‐protein adduct, has led to a better understanding of the synergistic effects of both partners. The exclusive formation of sulfoxides by the hybrid biocatalyst, as opposed to sulfone in the case of the free inorganic complex, highlights the modulating role of the inorganic‐complex‐binding site in the protein.

     

Relationships among manure nitrogen output and dietary and animal factors in lactating dairy cows

A large data set derived from total diet digestibility assessments on lactating dairy cows (535 Holstein-Friesian and 29 Norwegian) was used to examine effects of dietary and animal factors on manure (feces and urine) nitrogen (N) output and to develop mitigation strategies and prediction equations for manure N output in lactating dairy cows. Manure N output was positively and significantly related to live weight, milk yield, dietary crude protein (CP) concentration, dry matter intake, and N intake. Reducing the dietary CP concentration or increasing the milk yield decreased manure N output per kilogram of milk yield. Prediction equations for manure N output using live weight and milk yield, either alone or combined, had relatively low R² (0.227 to 0.474) and large standard error (70.6 to 85.6) values. Addition of dietary CP concentration to these relationships considerably increased R² to 0.754 and reduced the standard error to 48.2. Relating manure N output to N intake produced a very high r² (0.901) and a very low standard error (30.6). The addition of live weight and milk yield to this relationship as supporting predictors only marginally increased R² to 0.910 and reduced the standard error to 29.3. The internal validation of these equations revealed that use of N intake as the primary predictor produced a very accurate prediction of manure N output. In situations in which data on N intake are not available, prediction equations based on dietary CP concentration, live weight, and milk yield together can produce a relatively accurate assessment of manure N output.     

行为理论——设计活动的通用方法

 对工程设计的实证研究指出了提高解决方案质量的步骤特征:机会策略;用脑思考和用手思考(画草图)相结合;对自己的成果进行提问式反思。这些步骤特征符合工作活动的思维调控理论的预测(“行为理论”)。     

Synthetic elevation beamforming and image acquisition capabilities using an 8 x 128 1.75D array

Ultrasound imaging can be improved with higher order arrays through elevation dynamic focusing in future, higher channel count systems. However, modifications to current system hardware could yield increased imaging depth-of-field with 1.75D arrays (arrays with individually addressable elements, several rows in elevation) through the use of synthetic elevation imaging. We describe synthetic elevation beamforming methods and its implementation with our 8 /spl times/ 128, 1.75D array (Tetrad Co., Englewood, CO). This array has been successfully interfaced with a Siemens Elegra scanner for summed RF and single channel RF data acquisition. Individual rows of the 8 /spl times/ 128 array can be controlled, allowing for different aperture configurations on transmit and receive beamforming. Advantages of using this array include finer elevation sampling, a larger array footprint for aberration measurements, and elevation focusing. We discuss system tradeoffs that occur in implementing synthetic receive and synthetic transmit/receive elevation focusing and show significant image quality improvements in simulation and phantom data results.     

Detecting a moorland wildfire scar in the Peak District,UK, using synthetic aperture radar from ERS-2 and Envisat ASAR

Wildfires occur annually in UK moorland environments, especially in drought years. They can be severely damaging to the ecosystem when they burn deep into the peat, killing ground-nesting birds and releasing CO₂ into the atmosphere. Synthetic aperture radar (SAR) was evaluated for detecting the 18 April 2003 Bleaklow wildfire scar (7.4 km²). SAR’s ability to penetrate cloud is advantageous in this inherently overcast area. SAR can provide fire scar boundary information which is otherwise labour intensive to collect in the field using a global positioning system (GPS). This article evaluates the potential of SAR intensity and InSAR coherence to detect a large peat moorland wildfire scar in the Peak District of northern England. A time-series of pre-fire and post-fire ERS-2 and advanced synthetic aperture radar (ASAR) Single Look Complex (SLC) data were pre-processed using SARScape 4.2 to produce georeferenced greyscale images. SAR intensity and InSAR coherence values were analysed against Coordinate Information on the Environment (CORINE) land‐cover classes and precipitation data. SAR intensity detected burnt peat well after a precipitation event and for previous fire events within the CORINE peat bog class. For the 18 April 2003 fire event, intensity increased to 0.84 dB post-fire inside the fire scar for the peat bog class. InSAR coherence peaked post-fire for moors and heathland and natural grassland classes inside the fire scar, but peat bog exposed from previous fires was less responsive. Overall, SAR was found to be effective for detecting the Bleaklow moorland wildfire scar and monitoring wildfire scar persistence in a degraded peat landscape up to 71 days later. Heavy precipitation amplified the SAR fire scar signal, with precipitation after wildfires being typical in UK moorlands. Further work is required to disentangle the effects of fire size, topography, and less generalized land‐cover classes on SAR intensity and InSAR coherence for detecting fire scars in degraded peat moorlands.     

Survival after heart transplantation without regular immunosuppression

Seventy renal allograft biopsies were done in 31 patients, routinely at 1, 2, and 3 months posttransplant, and as clinically indicated, using an automated biopsy "gun." The histological diagnosis was made according to the Banff schema, which emphasizes tubulitis and vascular inflammation over mononuclear cell infiltration. Fifty-three biopsies satisfied histological inclusion criteria. Twenty-nine biopsies were obtained from stable patients, defined as those in whom serum creatinine had changed < 10% in 2 weeks, and in whom immunosuppression (cyclosporine, azathioprine, and prednisone) had not been increased in that interval. Of these biopsies, 30% (9/29) showed rejection, which could not have been predicted from pretransplant (HLA mismatch, panel-reactive antibody titer) or posttransplant (cyclosporine and serum interleukin 2 receptor levels) variables. The significance of these early subclinical rejection episodes is unknown, and their effects on long-term graft histology and function are being examined in a controlled study.