Facilitated transport of diuron and glyphosate in high copper vineyard soils

The fate of organic herbicides applied to agricultural fields may be affected by other soil amendments, such as copper applied as a fungicide. The effect of copper on the leaching of diuron and glyphosate through a granitic and a calcareous soil was studied in the laboratory using sieved-soil columns. Each soil was enriched with copper sulfate to obtain soil copper concentrations of 125, 250, 500, and 1000 mg kg(-1). Glyphosate leaching was influenced by soil pH and copper concentration, whereas diuron leaching was not. In the calcareous soil, glyphosate leaching decreased as copper levels increased from 17 mg kg(-1) (background) to 500 mg kg(-1). In the granitic soil, glyphosate leaching increased as copper levels increased from 34 mg kg(-1) (background) to 500 mg kg(-1). The shapes of the copper elution curves in presence of glyphosate were similar to shapes of the glyphosate curves, suggesting the formation of Cu-glyphosate complexes that leach through the soil. Soil copper concentration does not influence diuron leaching. In contrast, increasing copper concentrations reduces glyphosate leaching through calcareous soils, and conversely, increases glyphosate leaching through granitic soils. Our findings suggest that the risk of groundwater contamination by glyphosate increases in granitic soils with elevated copper concentrations.     

Frequency locking of a 1324 nm DFB laser to an optically pumpedrubidium vapor

Some experimental results and a simple theoretical model on a dither-free frequency-locking technique of a DFB laser operating at 1324 nm are presented. A resonance observed through absorption in an ⁸⁷ Rb vapor optically pumped by a modulated 795-nm laser diode tuned to the D₁ line is used. This approach has the advantage of producing sub-Doppler resonances. Such a technique could be used to generate an unmodulated 1324-nm wavelength reference     

Broad-Spectrum Antifungal Agents: Fluorinated Aryl- and Heteroaryl-Substituted Hydrazones

Fluorinated aryl- and heteroaryl-substituted monohydrazones displayed excellent broad-spectrum activity against various fungal strains, including a panel of clinically relevant Candida auris strains relative to a control antifungal agent, voriconazole (VRC). These monohydrazones displayed less hemolysis of murine red blood cells than that of VRC at the same concentrations, possessed fungicidal activity in a time-kill study, and exhibited no mammalian cell cytotoxicity. In addition, these monohydrazones prevented the formation of biofilms that otherwise block antibiotic effectiveness and did not trigger the development of resistance when exposed to C. auris AR Bank # 0390 over 15 passages.     

Chemically Controllable Magnetic Transition Temperature and Magneto-Elastic Coupling in MnZnSb Compounds

Magneto-caloric materials offer the possibility to design environmentally friendlier thermal management devices compared to the widely used gas-based systems. The challenges to develop this solid-state based technology lie in the difficulty of finding materials presenting a large magneto-caloric effect over a broad temperature span together with suitable secondary application parameters such as low heat capacity and high thermal conductivity. A series of compounds derived from the PbFCl structure is investigated using a combination of computational and experimental methods focusing on the change of cell volume in magnetic and non-magnetic ground states. Scaling analysis of the magnetic properties determines that they are second order phase transition ferromagnets and that the magnetic entropy change is driven by the coupling of magneto-elastic strain in the square-net through the magnetic transition determined from neutron and synchrotron X-ray diffraction. The primary and secondary application related properties are measured experimentally, and the c/a parameter is identified as an accurate proxy to control the magnetic transition. Chemical substitution on the square-net affords tuning of the Curie temperature over a broad temperature span between 252 and 322 K. A predictive machine learning model for the c/a parameter is developed to guide future exploratory synthesis.     

Study of the formation of acid-based geopolymer networks and their resistance to water by time/temperature treatments

Acid-based geopolymers are known for their high temperature resistance and good mechanical performances. Some compositions also exhibit water resistance, which make them suitable for outdoor applications. This work aims to understand accurately the steps occurring during the geopolymerization process and focuses on the type of networks forming at early stages of the reaction. The sample, prepared from metakaolin and phosphoric acid, has been analyzed at different durations and temperatures during its solidification, in order to identify which compounds would crystallize. The structural characterizations have been performed using Fourier transform infrared spectroscopy and X-ray diffraction. Several Al–O–P compounds and especially AlPO₄ polymorphs crystallize in these conditions. They belong to three families of aluminophosphates and are a reliable indication of the amorphous organization of the original sample. The first one is similar to the phases that appear in the phase transition sequences of silica, the second one is composed of AlPO₄-based zeolites, and the last one is characterized by the presence of aluminum in an octahedral network. The transitions between the different phases are also discussed. Finally, the water resistance of the calcined samples is improved, and the release of acidic species in the water is limited even after a calcination at low temperature.     

Application of the off-gas method to the measurement of oxygen transfer in biofilters

To determine the oxygen mass transfer in clean water in biofilters, a method based on the follow up of the oxygen fraction in the off gas during the oxidation of sulphite in excess has been evaluated and applied to a pilot-scale unit (250 L, superficial gas velocity from 0 to , superficial liquid velocity from 0 to ). Tests performed on a two-phase reactor showed that, without any cobalt addition, standard oxygen transfer efficiencies (SOTE) obtained from the proposed method are not statistically different from those issued from the standardised method. A relationship has been proposed to express SOTE values as a function of the conductivity, and the influence of the gas and liquid velocities on SOTE and k_La has been investigated.     

Volume relaxation in a borosilicate glass hot compressed by three different methods

The temperature dependence of glass relaxation has been intensively studied; however, the effect of an imposed pressure history on relaxation behavior is poorly understood. In this study, we subjected SCHOTT N-BK7^® borosilicate glasses to isostatic compression in a Paterson press (PP) and a gas pressure chamber (GPC). The pressure ranged from 0.1 GPa to 2 GPa for various dwell temperatures and times near the glass transition region. Comparison with our recent results on the same glass using the piston-cylinder apparatus (PC, 0.5-1.5 GPa) reveals that the density of a glass, which has been quenched from the equilibrium state under high pressure at 2 K/min (pressure quench), increases approximately linearly with increasing pressure up to 2 GPa. Considering the volume recovery results at ambient pressure, we assert that the preceding high-pressure treatment in PC (uniaxial loading) generates a similar isostatic pressure effect on N-BK7 glass as those of PP and GPC treatments. Finally, we verify the previously proposed two-internal-parameter relaxation model on the volume recovery data using the three different compression methods. With a new set of parameters in the model, we can account for the pressure and temperature dependence of volume relaxation even for the samples quenched from nonequilibrium states at high pressure.     

<Emphasis Type=Italic>Oenocarpus bataua</Emphasis> Mart. (Arecaceae): Rediscovering a Source of High Oleic Vegetable Oil from Amazonia

The fatty acid (FA) composition of Oenocarpus bataua oil from 38 samples collected over a large geographical range (i.e. French Guiana and Peru) was analyzed. Fifteen fatty acids were obtained from the mesocarp of this palm species. Oleic (72.7%) and palmitic (18.1%) acids were the predominant FAs. Minor FAs were cis-vaccenic acid (2.3%), linoleic acid (1.9%), stearic acid (1.7%), palmitoleic (0.9%) and alpha-linolenic acid (0.8%). The mean lipid content of the dry mesocarp was 51.6%. The O. bataua oil samples analyzed were remarkably rich in α-tocopherol. By contrast, the other fractions of the unsaponifiable matter (sterols, carotenoids) did not show any noteworthy specificity in comparison with common vegetable oils. However, the particularly high percentage in Δ5-avenasterol of O. bataua oil could serve as a marker for its authentication. Results are discussed in terms of the potential nutritional value of O. bataua oil.     

Cold-Sprayed Cu-MoS<Subscript>2</Subscript> and Its Fretting Wear Behavior

Cu and Cu-MoS₂ coatings were fabricated by cold spray, and the fretting wear performance of the two coatings was compared. A mixture (95 wt.% Cu + 5 wt.% MoS₂) was used as feedstock for the composite coating. Coatings were sprayed with identical gas flow conditions on the substrates pre-heated to approximately 170 °C. The morphology of coating top surface and polished cross sections was analyzed by scanning electron microscopy (SEM) and light optical microscopy (LOM). The influence of MoS₂ on Cu deposition was examined. The local MoS₂ concentration within the coating was found to affect the hardness. Fretting tests were carried out at two different normal loads, and the influence of MoS₂ on friction and wear was studied. The morphology and elemental compositions of the wear scars and wear debris were observed by SEM and energy dispersive x-ray spectroscopy (EDS), respectively.     

Oxygen transfer prediction in aeration tanks using CFD

In order to optimize aeration in the activated sludge processes, an experimentally validated numerical tool, based on computational fluid dynamics and able to predict flow and oxygen transfer characteristics in aeration tanks equipped with fine bubble diffusers and axial slow speed mixers, is proposed. For four different aeration tanks (1;1493;8191 and ), this tool allows to precisely reproduce experimental results in terms of axial liquid velocities, local gas hold-ups. Predicted oxygen transfer coefficients are within ±5% of experimental results for different operating conditions (varying pumping flow rates of the mixers and air flow rates). The actual bubble size must be known with precision in order to have a reliable estimation of the oxygen transfer coefficients.