Mode multiplexing in optical frequency mixers

Asymmetric Y junctions allow the development of a new class of optical frequency mixers that utilize higher-order waveguide modes for signal processing. We measure high-contrast (>30 dB) mode sorting in asymmetric Y junctions by use of a novel technique: efficient TM00, TM10, and TM20 mode mixing in a periodically poled lithium niobate waveguide. We also demonstrate an odd-to-even mode wavelength converter capable of spectral inversion without offset or bidirectional wavelength conversion.     

One-pot synthesis to engineer a Co-KIT-6 catalyst for the ring opening of methylcyclopentane

Co-KIT-6 mesoporous materials with Ia3d symmetry and Si/Co ratios of 50, 25, and 10 were prepared using hydrothermal one-pot synthesis. The Co-KIT-6 mesoporous materials were characterized by X-ray diffraction, N₂ adsorption–desorption isotherms, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared, and X-ray photoelectron spectroscopy. The physicochemical characterization results show that all of the samples have well-ordered cubic mesostructures and that the structural integrity is preserved for n_Si/n_Co ratios as high as 10. It was found that most of the cobalt ions exist as isolated framework species, but for Co-KIT-6 with an n_Si/n_Co ratio of 10, the presence of extra-framework species/small cobalt oxide clusters cannot be excluded. The ability of these catalysts was tested by examining the conversion of the reaction of methylcyclopentane with hydrogen at atmospheric pressure and temperatures between 200 and 450 °C. The catalytic results show that their catalytic activity increases significantly with increasing cobalt content. The active sites, tetrahedrally coordinated Co and isolated atomic Co sites, were responsible for the endocyclic CC bond rupture between substituted secondary–tertiary carbon atoms, whereas the small clusters serve as active sites for the successive CC bond rupture. The ring-opening selectivity can be improved by increasing the density of isolated cobalt atom sites at low reaction temperatures.     

Superparamagnetic iron oxide-enhanced MR imaging for early and late radiation-induced hepatic injuries

Superparamagnetic iron oxide (SPIO)-enhanced MRI was performed in twenty-one patients undergoing proton-beam radiotherapy for hepatocellular carcinomas. Patients were divided into two groups: early and late phase hepatic injuries. Each group was investigated 3 to 9 weeks and 4 to 65 months after the start of irradiation, respectively. T(1)-weighted, T(2)-weighted, and T(2)*-weighted images were obtained before and after SPIO administration. In all postcontrast sequences in the early phase, irradiated livers demonstrated relatively higher intensity than nonirradiated livers and the radiation-to-liver contrast-to-noise ratio (C/N) was improved. Postcontrast T(2)*-weighted images showed the highest C/N. In the late phase, the irradiated areas showed high intensity on T(2)-weighted images and low intensity on T(1)-weighted images without SPIO, while high intensity on T(1)-weighted images with SPIO. The C/N increased with SPIO in all sequences and postcontrast T(2)-weighted images showed the highest C/N in the late phase. SPIO-enhanced MRI is useful to evaluate this entity both in the early and late phase of clinical studies.     

Evaluation of vermicompost as bioadsorbent substrate of Pb,Ni, V and Cr for waste waters remediation using Total Reflection X-ray Fluorescence

The use of vermicompost as adsorbent substrate for removing Pb, Ni, V and Cr from waste waters is proposed. In this work, after a preliminary physical and chemical characterization of the vermicompost, the optimal parameters for the heavy metal adsorption were obtained. A synthetic multielemental solution of Pb, Cr and Ni and a solution of NH₄VO₃ for vanadium were evaluated. The optimized parameters were pH, vermicompost mass to volume ratio, agitation time and particle size of the adsorbent. A batch system was employed for the assays. The elements were determined in the supernatant solution after filtration of the substrate. An optimal pH of 4.5 was found for ion removal. The agitation time slightly influences the adsorption of Pb and Cr, but it has a high influence on the Ni and V adsorption. The highest adsorption and removal of the metals was observed for a vermicompost mass of 2 g per 500 mL using a particle size between 75 to 841 µm for Pb, Cr and Ni, and 841 till 1192 µm for V. The mean removal percentage for each element is around 95% for Pb. Ni and Cr in the multielemental synthetic sample, demonstrating a high removal capacity of the substrate. For V it was found a removal efficiency of 50%.     

Comparison of Different d-SPE Sorbent Performances Based on Quick,Easy, Cheap,Effective, Rugged,and Safe (QuEChERS) Methodology for Multiresidue Pesticide Analyses in Rapeseeds

Pesticide extraction in rapeseed samples remains a great analytical challenge due to the complexity of the matrix, which contains proteins, fatty acids, high amounts of triglycerides and cellulosic fibers. An HPLC-MS/MS method was developed for the quantification of 179 pesticides in rapeseeds. The performances of the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method were evaluated using different dispersive solid-phase extraction (d-SPE) sorbents containing common octadecylsilane silica/primary–secondary amine adsorbent (PSA/C18) and new commercialized d-SPE materials dedicated to fatty matrices (Z-Sep, Z-Sep⁺, and EMR-Lipid). The analytical performances of these different sorbents were compared according to the SANTE/12682/2019 document. The best results were obtained using EMR-Lipid in terms of pesticide average recoveries (103 and 70 of the 179 targeted pesticides exhibited recoveries within 70–120% and 30–70%, respectively, with low RSD values). Moreover, the limits of quantification (LOQ) range from 1.72 µg/kg to 6.39 µg/kg for 173 of the pesticides. Only the recovery for tralkoxydim at 10 μg/kg level was not satisfactory (29%). The matrix effect was evaluated and proved to be limited between −50% and 50% for 169 pesticides with this EMR-Lipid and freezing. GC-Orbitrap analyses confirmed the best efficiency of the EMR-Lipid sorbent for the purification of rapeseeds.     

Synthesis and surface-active properties of the fatty acid N-methylethylolamides and their phosphate derivatives

N-Methylethylolamides have been synthesized on the basis of vegetable oils (corn, coconut, canola, olive, cotton-seed, and palm) and modified with orthophosphoric acid. The structure of the synthesized N-methylethylolamides and their phosphate derivatives has been identified by IR and NMR spectroscopies. Surface activity of the N-methylethylolamides and their derivatives at the water–air border has been determined and their colloidal-chemical parameters (maximum surface excess concentration and minimum area per molecule at the aqueous solution–air interface, surface pressure at the critical micellization concentration (CMC), standard thermodynamic parameters of adsorption and micellization) have been calculated. The character of influence of the surfactants structure on their colloidal-chemical parameter has been clarified. The petroleum-collecting and petroleum-dispersing capacities of the synthesized surfactants have been studied on the surface of the water of various mineralization degrees.     

Effect of Al and Ce on Zr-pillared bentonite and their performance in catalytic oxidation of phenol

Catalysts based on pillared clays with Zr and/or Al and Ce–Zr and/or Al polycations have been synthesized from a Tunisian bentonite and tested in catalytic oxidation of phenol at 298 K. The Zr-pillared clay showed higher activity than the Al-one in phenol oxidation. Mixed Zr–Al pillars lead to an enhancement of the catalytic activity due to the modification of the zirconium properties. The clays modified with Ce showed high conversions of phenol and TOC thus showing to be very selective towards the formation of CO₂ and H₂O.     

Electrical probing of endothelial cell behaviour on a fibronectin/polystyrene/thiol/gold electrode by Faradaic electrochemical impedance spectroscopy (EIS)

The electrochemical impedance spectroscopy (EIS) technique has been shown to be an effective tool for monitoring endothelial cell behaviour on a multilayer functionalised gold electrode. Polystyrene, a reproducible model substrate, is deposited as a thin layer on a thiol functionalised gold electrode. Fibronectin, a protein promoting endothelial cell adhesion, is then adsorbed on the polystyrene surface. The different steps of this multilayer assembly are characterized by Faradaic impedance. The charge transfer resistance and the capacitance for the total layer are modified at each step according to the electrical properties of each layer. This gives the endothelial cells' electrical state in terms of its resistive and capacitive properties. In this study, the endothelial cell layer presents a specific charge transfer resistance equal to 1.55 kOmega cm(2) with no large defects in the cell layer, and a specific capacitance equal to few microF cm(-2) explained by the existence of pseudopods. These electrical properties are correlated to the endothelial cell viability, adhesion and cytoskeleton organization.     

Dual double arterial phase dynamic MR imaging with sensitivity encoding (SENSE): which is better for diagnosing hypervascular hepatocellular carcinomas, in-phase or opposed-phase imaging?

The purpose of this study was to investigate the efficacy of sensitivity encoding (SENSE) dynamic magnetic resonance imaging (MRI) with the dual (in-phase and opposed-phase) double arterial phase to detect hypervascular hepatocellular carcinomas (HCCs). MR images of the liver from 44 consecutive patients were obtained. Dynamic MRI with SENSE was performed six times (precontrast, early arterial, late arterial, 1 min, 3 min and 5 min after contrast injection) at 11 s per scan using the gradient recalled echo sequence (TR/TE/flip angle = 168/2.3 and 4.6/70). In-phase and opposed-phase images were obtained simultaneously each scan. For the quantitative analysis, the signal-to-noise ratio (S/N) of HCC and tumor-to-liver contrast-to-noise ratio (C/N) were analyzed for 55 HCCs. The mean S/N of HCCs on in-phase images showed significantly higher values than that on opposed-phase images regarding all phases (P < 0.001). In arterial phases, the mean tumor-to-liver C/N for in-phase images was significantly higher than that for opposed-phase images (P < 0.05). In portal and delayed-phase images, the mean tumor-to-liver C/N in opposed-phase images showed a negative value. In six HCCs with fatty metamorphosis, the mean tumor-to-liver C/N on arterial phase images approached zero in opposed-phase, while it showed a positive value in-phase. In dual double arterial phase dynamic MRI of the liver, in-phase images were superior to opposed-phase images for detecting early enhancement of hypervascular HCCs, while the latter were superior for detecting washout of contrast media from HCCs in the portal and delayed phase. The combination of both images overcomes the difficulty of diagnosing hypervascular HCCs with fatty metamorphosis.