Thermally activated delayed fluorescence in neutral and cationic copper(I) complexes with the 2-(4-Thiazolyl)benzimidazole ligand

Cationic [Cu(P^P)(Htbz)]PF6 [P^P = xantphos, dpephos; Htbz = 2-(4-thiazolyl)benzimidazole] and the corresponding neutral complexes [Cu(P^P)(tbz)], obtained through deprotonation of the diimine ligand, have been synthesized with the aim of analyzing the role of the diphosphane and Htbz deprotonation in the emissive properties of these complexes. For the study of the diphosphane effect, the luminescence properties of these compounds have been compared with those of the reported analogous derivatives with Htbz and carborane diphosphanes. Complexes [Cu(P^P)(Htbz)]PF6 (P^P = xantphos, dpephos) and [Cu(dpephos)(tbz)] display thermally activated delayed fluorescence, which has been studied, revealing a ΔE(S1–T1) between 658 and 455 cm–1. Theoretical calculations indicate different origins for the absorptions, leading to the observed emissions

Experimental assessment of skull aberration and transmission loss at 270 kHz for focused ultrasound stimulation of the primary visual cortex

Transcranial focused ultrasound is a rapidly emerging method for non-invasive neuromodulation and stimulation. However, the skull causes a significant acoustic barrier and can reduce the focal intensity and alter the position and shape of the focus compared to free-field. In this study, the insertion loss and focal distortion due to the skull bone were quantified using three ex vivo human skulls and a focused ultrasound transducer operating at 270 kHz targeted on the approximate positions of the left and right primary visual cortex. Compared to free-field, the average insertion loss was -9.8 dB (± 2.2 dB), while the average focal shift was 1.7 mm (± 0.56 mm) in the lateral direction and 2.8 mm (±4.2 mm) in the axial direction. Overall, the acoustic aberrations were small compared to the size of the focal volume, meaning effective stimulation at this frequency can likely be achieved without patient-specific targeting. However, the insertion loss was significant and should be considered when selecting the target focal intensity for human studies

Fenton-like oxidation of landfill leachate

The treatment of stabilized leachates by means of Fenton's like reagent [Fe(III)-H2O2] has been studied. It has been demonstrated that the oxidation state of the catalyst does not influence the efficacy of the process in terms of chemical oxygen demand depletion profiles. The abrupt increase in temperature experienced in oxidation experiments involves a wastage of hydrogen peroxide diminishing the fraction of this reagent addressed at removing COD. If temperature is kept constant, the hydrogen peroxide uptake is 10 mg of H2O2 consumed per mg of COD abated (from 15 to 30°C). Working temperatures above 30°C does not lead to additional COD conversion, contrarily, the percentage of wasted H2O2 is increased. A rough economic analysis of the process indicates that this treatment can be a suitable alternative to deal with this type of effluents

Adsorption of landfill leachates onto activated carbon: Equilibrium and kinetics

The adsorption of stabilized leachates generated in a municipal landfill onto three commercial activated carbons has been investigated. Norit 0.8, Chemviron AQ40 and Picacarb 1240 have been used as adsorbents. Equilibrium experiments have been conducted to obtain the experimental isotherm profiles. Isotherms have been plotted based on the adsorption of general parameters, for instance chemical oxygen demand, total carbon, absorption at 410 nm and absorption at 254 nm. Different literature models and error functions have been used to adequately fit the experimental data. As a rule of thumb, three-parameter models do adjust experimental results better than two-parameter models. Norit 0.8 shows better adsorption characteristics than the rest of activated carbons, both in terms of contaminant level reduction of per unit mass of absorbent and in terms of the process kinetics

Study of different integrated physical-chemical + adsorption processes for landfill leachate remediation

Some integrated processes to deal with landfill leachates have been investigated and their efficiencies expressed in terms of chemical oxygen demand (COD) removal. The systems tested were the result of different combinations of the following single stages: acidic pH shift (elimination of humic substances), ozonation (O3), coagulation-flocculation with Fe(III) salts, Fenton's oxidation (Fe(III) + H2O2), wet air oxidation (with or without radical promoters), and adsorption onto activated carbon (commercial Norit 0.8 powdered activated carbon). COD removals obtained ranged in the interval of 80-96% for initial COD values close to 11000 mg L-1. None of the processes tested reduced the COD levels sufficiently to allow direct discharge; however, the ratio biochemical oxygen demand (BOD/COD was significantly increased (up to 1000% in some cases, i.e., from 0.1 to values above 1.0). Total carbon reduction achieved ranged from 60 to 94%, while complete decolorization (measured as the absorbance at 410 nm) was obtained in practically all the combinations investigate

Stabilized leachates: sequential coagulation–flocculation + chemical oxidation process

The combined sedimentation-chemical oxidation treatment of medium-stabilized landfill leachates has been investigated. The sequence of stages implemented was: (a) coagulation–flocculation by pH decrease (pH 2) to acidic conditions (COD removal ≈ 25% related to COD0 ≈ 7500 ppm); (b) coagulation–flocculation by Fe(III) addition (0.01 M) at pH 3.5 (COD removal ≈ 40% related to COD of supernatant after step (a); (c) Fenton (Fe(III) = 0.01 M; H2O2 = 1.0 M) oxidation (COD removal ≈ 80% related to COD of supernatant after step (a); and (d) coagulation–flocculation of Fenton’s effluent at pH 3.5 (COD removal ≈ 90% related to COD of supernatant after step (a). The use of Kynch theory allows for the design of clarifiers based on the amount of solids fed. For a general example of 1000 m3 day−1 of a feeding stream, clarifier area values of 286, 111 and 231 m2 were calculated for compacting indices of 3.7, 2.67 and 2.83 corresponding to the first, second and third consecutive sedimentation processes, respectively, (steps (a), (b) and (d))

Stabilized leachates: Ozone-activated carbon treatment and kinetics

Ozone has been used as a pre-oxidation step for the treatment of stabilized leachates. Given the refractory nature of this type of effluents, the conversion of some wastewater quality parameters has been moderate after 1 h of ozonation (i.e. 30% chemical oxygen demand (COD) depletion). Ozone uptake was calculated in the interval 1.3–1:5 g of ozone per gram of COD degraded. An optimum dose of ozone has been experienced in terms of biodegradability of the processed effluent (60 min of treatment, 1 103 mol L1 ozone inlet feeding concentration and 50 L h1 gas flowrate). pH and other typical hydroxyl radical generator systems exerted no influence on the efficiency of the process, suggesting the negligible role played by the indirect route of oxidation (generation of hydroxyl radicals). The ozonated effluent was thereafter treated in a second adsorption stage by using a commercial activated carbon. Removal levels up to 90% of COD in approximately 120 h were experienced for adsorbent dosages of 30 g L1 : Both steps, the single ozonation and the adsorption stage have been modelled by using different pseudoempirical models. r 2003 Elsevier Ltd. All rights reserved

Analysis of volatile compounds by GC-MS of a dry fermented sausage: chorizo de Pamplona

The profile of volatile compounds of a typical Spanish dry fermented sausage, chorizo de Pamplona, has been analyzed by GC-MS, using a simultaneous distillation-extraction (SDE) system. Qualitative and quantitative differences were found in the volatile profiles obtained in the five analyzed commercial brands. One hundred and ninety three different substances were isolated, the group of acids being the most important from a quantitative point of view in all brands, accounting at least for the 60% of the total area. Aldehydes, basically from lipid oxidation, contributed between 7.72% and 13.97% to the total amount. Acids and aldehydes were the chemical families that showed the lowest variability among brands. In contrast, esters showed the highest coefficient of variation among brands (111%), followed by phenols (82%) and terpenes (76%). The variability observed in these three families could be attributed respectively to the different starter cultures, smoking process and spices employed in their production. Butylated hydroxytoluene (added as an antioxidant, E-321) was the third most abundant compound in 3 of the 5 brands

New formulations for healthier dry fermented sausages: a review.

An excessive intake of meat products, particularly dryfermented sausages, is not recommended from a health point of view, at least for some population groups, due to their high level of sodium and animal fat. Many efforts of the meat industry are focused on the development of new products with better nutritional properties than traditional ones. KCl, CaCl2, and/or calcium ascorbate, among others, have been assessed as partial substitutes of NaCl, giving products with acceptable sensory quality, smaller amounts of sodium and being sometimes a significant source of potassium or calcium. In relation to fat, recent research has focused on the use of different types of fibres and vegetable oils as partial substitutes of pork backfat. The use of fibres results in low-fat and low-energy products. The use of vegetable oils results in products with healthier fatty acid profiles. Aspects related to improving sensory properties and control of oxidation should be taken into account in future research

Depth of focus increase by multiplexing programmable diffractive lenses

A combination of several diffractive lenses written onto a single programmable liquid crystal display (LCD) is proposed for increasing the Depth of Focus (DOF) of the imaging system as a whole. The lenses are spatially multiplexed in a random scheme onto the LCD. The axial irradiance distribution produced by each lens overlaps with the next one producing an extended focal depth. To compare the image quality of the multiplexed lenses, the Modulation Transfer Function (MTF) is calculated. Finally we obtain the experimental Point Spread Functions (PSF) for these multiplexed lenses and experimental results in which an extended object is illuminated under spatially incoherent monochromatic light. We compare the images obtained in the focal plane and in some defocused planes with the single lens and with three multiplexed lenses. The experimental results confirm that the multiplexed lenses produce a high increase in the depth of focus.Fil: Iemmi, Claudio Cesar. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Campos, Juan. Universitat Autonoma de Barcelona; EspañaFil: Escalera, J. C.. Universitat Autonoma de Barcelona; EspañaFil: López Coronado, O. Universitat Autonoma de Barcelona; EspañaFil: Gimeno, R.. Universitat Autonoma de Barcelona; EspañaFil: Yzuel, María J.. Universitat Autonoma de Barcelona; Españ