Adsorption of phenanthrene on natural snow

The snowpack is a reservoir for semivolatile organic compounds (SVOCs) and, in particular, for persistent organic pollutants (POPs), which are sequestered in winter and released to the atmosphere or hydrosphere in the spring. Modeling these processes usually assumes that SVOCs are incorporated into the snowpack by adsorption to snow surfaces, but this has never been proven because the specific surface area (SSA) of snow has never been measured together with snow composition. Here we expose natural snow to phenanthrene vapors (one of the more volatile POPs) and measure for the first time both the SSA and the chemical composition of the snow. The results are consistent with an adsorption equilibrium. The measured Henry's law constant is H(Phen)(T) = 2.88 x 10(22) exp(-10660/7) Pa m2 mol(-1), with Tin Kelvin. The adsorption enthalpy is delta H(ads) = -89 +/- 18 kJ mol(-1). We also perform molecular dynamics calculations of phenanthrene adsorption to ice and obtain AHads = -85 +/- 8 kJ mol(-1), close to the experimental value. Results are applied to the adsorption of phenanthrene to the Arctic and subarctic snowpacks. The subarctic snowpack, with a low snow area index (SAI = 1000), is a negligible reservoir of phenanthrene, butthe colder Arctic snowpack, with SAI = 2500, sequesters most of the phenanthrene present in the (snow + boundary layer) system.     

Survey of management practices on reproductive performance of dairy cattle on large US commercial farms

A survey regarding general management, sire selection, reproductive management, inseminator training and technique, heat abatement, body condition scoring, facility design and grouping, nutrition, employee training and management, and animal health and bio-security was carried out from March to September of 2004 in 153 herds in the Alta Genetics (Watertown, WI) Advantage Progeny Testing Program. A total of 103 herds (67.3%) completed the survey. Herd size was 613 ± 46 cows, with herds located in Wisconsin (26), California (12), New York (11), Minnesota (10), Michigan (7), Washington (6), Pennsylvania (6), Iowa (5), Idaho (5), Texas (4), Ohio (4), and other states (7). These farms sold 34.5 ± 0.3 kg of milk/d per cow, with an annual culling rate of 34 ± 1% and a calving interval of 13.8 ± 0.1 mo. Cows were observed for estrus 2.8 ± 0.3 times/d, for a duration of 27 ± 4 min, but 78% of the respondents admitted that detection of estrus was not the employee's sole responsibility at that time. Managers tried to achieve pregnancy until 8.8 ± 0.9 failed inseminations, 300 ± 26 d postpartum, or milk yield <17.7 ± 0.5 kg/d. Nonpregnant cows were culled at 326 ± 36 d postpartum or milk yield <16.4 ± 0.3 kg/d. Mean durations of the voluntary waiting period were 52 ± 1.3 and 53 ± 1.4 d for primiparous and multiparous cows, respectively. Hormonal synchronization or timed artificial insemination programs were used in 87% of the herds, with 86% synchronizing first services, 77% resynchronizing repeat services, and 59% treating cystic, anestrous, or anovular cows. Finding good employees was identified as the greatest labor challenge, followed by training and supervising employees. Mastitis and hairy heel warts were noted as the greatest animal health concerns, followed by lameness, abortions, and death losses, whereas the greatest reproductive challenges were artificial insemination service rate, conception rate, twinning, and retained placenta or metritis. Results of this study can provide a useful benchmark or reference with regard to commonly used management practices on large commercial US dairy farms at the present time.     

Targeting G Protein-Coupled Receptors with Magnetic Carbon Nanotubes: The Case of the A3 Adenosine Receptor

The A₃ adenosine receptor (AR) is a G protein-coupled receptor (GPCR) overexpressed in the membrane of specific cancer cells. Thus, the development of nanosystems targeting this receptor could be a strategy to both treat and diagnose cancer. Iron-filled carbon nanotubes (CNTs) are an optimal platform for theranostic purposes, and the use of a magnetic field can be exploited for cancer magnetic cell sorting and thermal therapy. In this work, we have conjugated an A₃AR ligand on the surface of iron-filled CNTs with the aim of targeting cells overexpressing A₃ARs. In particular, two conjugates bearing PEG linkers of different length were designed. A docking analysis of A₃AR showed that neither CNT nor linker interferes with ligand binding to the receptor; this was confirmed by in vitro preliminary radioligand competition assays on A₃AR. Encouraged by this result, magnetic cell sorting was applied to a mixture of cells overexpressing or not the A₃AR in which our compound displayed indiscriminate binding to all cells. Despite this, it is the first time that a GPCR ligand has been anchored to a magnetic nanosystem, thus it opens the door to new applications for cancer treatment.     

Ferroelectricity and high tunability in novel strontium and tantalum based layered perovskite materials

The present study reveals the ferroelectric nature of the novel (Sr₂Ta₂O₇)_100-x(La₂Ti₂O₇)_x layered perovskite materials and highlights a large variation of their permittivity under electric fields associated with very low dielectric loss in the radio-frequency range. More precisely, an ideal solid solution has been evidenced within the composition range 0?≤?x?≤?5 with lattice parameters and cell volume varying linearly with x. The relative permittivity also depends on the composition and reaches a maximum value (365 @10?kHz, RT), associated with a high tunability (17.6% @0.38?kV/mm) with very low dielectric loss lower than 2.10^?3. Variation of the relative permittivity as a function of the temperature is also demonstrated, with the existence of a temperature maximum, increasing with the composition. Polarization-electric field (P-E) measurements feature hysteresis loops for compositions x?≥?1.85, in conjunction with current peaks in the I-E curves originating from ferroelectric domains switching.     

New carbon cone nanotip for use in a highly coherent cold field emission electron microscope

A new cathode for cold-field emission gun using a pyrolytic carbon-cone supported onto a carbon nanotube as the electron emitting tip has been developed. This tip was mounted in a TEM using a FIB based method, and the brightness measured under real operating conditions is five times better than obtained with a standard tungsten tip. Its use overcomes the many technical difficulties which have dogged the use of carbon nanotube-based tips as proposed replacements for tungsten tips. The resulting properties of the final CFEG exhibit a very good energy spread of 0.32 eV, a reduced brightness of 1.6 × 10⁹ A m^?2 sr^?1 V^?1 and a very good long-term stability with a current damping less than 16% per hour.     

Alternative Bio-Based Solvents for Extraction of Fat and Oils: Solubility Prediction,Global Yield,Extraction Kinetics,Chemical Composition and Cost of Manufacturing

The present study was designed to evaluate the performance of alternative bio-based solvents, more especially 2-methyltetrahydrofuran, obtained from crop’s byproducts for the substitution of petroleum solvents such as hexane in the extraction of fat and oils for food (edible oil) and non-food (bio fuel) applications. First a solvent selection as well as an evaluation of the performance was made with Hansen Solubility Parameters and the COnductor-like Screening MOdel for Realistic Solvation (COSMO-RS) simulations. Experiments were performed on rapeseed oil extraction at laboratory and pilot plant scale for the determination of lipid yields, extraction kinetics, diffusion modeling, and complete lipid composition in term of fatty acids and micronutrients (sterols, tocopherols and tocotrienols). Finally, economic and energetic evaluations of the process were conducted to estimate the cost of manufacturing using 2-methyltetrahydrofuran (MeTHF) as alternative solvent compared to hexane as petroleum solvent.     

Synthesis and structure-activity relationships of constrained heterocyclic analogues of combretastatin A4

A series of combretastatin A4 (CA4) analogues with a lactam or lactone ring fused to the trimethoxyphenyl or the B‐phenyl moiety were synthesized in an efficient and stereoselective manner by using a domino Heck–Suzuki–Miyaura coupling reaction. The vascular‐disrupting potential of these conformationally restricted CA4 analogues was assessed by various in vitro assays: inhibition of tubulin polymerization, modification of endothelial cell morphology, and disruption of endothelial cell cords. Compounds were also evaluated for their growth inhibitory effects against murine and human tumor cells. B‐ring‐constrained derivatives that contain an oxindole ring (in contrast to compounds with a benzofuranone ring) as well as analogues bearing a six‐membered lactone core fused to the trimethoxyphenyl ring are endowed with significant biological activity. The most potent compound of this series (oxindole 9 b ) is of particular interest, as it combines chemical stability and a biological activity profile characteristic of a vascular‐disrupting agent.