CWPO of bisphenol A with iron catalysts supported on microporous carbons from grape seeds activation

This accepted manuscript is available under a CC BY-NC-ND licence after the 24 months embargo periodThe catalytic wet peroxide oxidation (CWPO) of bisphenol A (BPA) with Fe catalysts supported on activated carbon from grape seeds (GS) has been studied. The GS were pyrolized (N2, 600 °C, 2 h) and subjected to activation upon partial gasification with air (400 °C, 2 h). Oxidized samples of the char and activated carbon were also obtained upon treatment with HNO3. The Fe catalysts were prepared by incipient wetness impregnation with ferric nitrate solution. They showed narrow microporosity, with surface area values ≈350–500 m2 g−1 and total iron contents between 2.8 and 4.2% wt. The CWPO experiments were carried out at 50–80 °C. The best catalyst allowed complete conversion of BPA (100 mg L−1) and a 60% TOC reduction in 3 h reaction time at 80 °C and the theoretical stoichiometric amount of H2O2 (530 mg L−1). The ecotoxicity of the effluent was negligible and the biodegradability was highly improved. In a long-term experiment (100 h), the catalyst suffered a loss of activity upon the early stages on stream (≈15 h), where about 20% of Fe was lost, followed by a highly stable behavior for the rest of the experimentThe authors wish to thank the Spanish MINECO and Comunidad de Madrid for the financial support through the projects CTM2013-43803-P and S2013/MAE-2716, respectively. I. F. Mena wishes to thank the MINECO and the ESF for a research gran

Ultra-pure digital sideband separation at sub-millimeter wavelengths

Deep spectral-line surveys in the mm and sub-mm range can detect thousands of lines per band uncovering the rich chemistry of molecular clouds, star forming regions and circumstellar envelopes, among others objects. The ability to study the faintest features of spectroscopic observation is, nevertheless, limited by a number of factors. The most important are the source complexity (line density), limited spectral resolution and insufficient sideband (image) rejection (SRR). Dual Sideband (2SB) millimeter receivers separate upper and lower sideband rejecting the unwanted image by about 15 dB, but they are difficult to build and, until now, only feasible up to about 500 GHz (equivalent to ALMA Band 8). For example ALMA Bands 9 (602-720 GHz) and 10 (787-950 GHz) are currently DSB receivers. Aims: This article reports the implementation of an ALMA Band 9 2SB prototype receiver that makes use of a new technique called calibrated digital sideband separation. The new method promises to ease the manufacturing of 2SB receivers, dramatically increase sideband rejection and allow 2SB instruments at the high frequencies currently covered only by Double Sideband (DSB) or bolometric detectors. Methods: We made use of a Field Programmable Gate Array (FPGA) and fast Analog to Digital Converters (ADCs) to measure and calibrate the receiver's front end phase and amplitude imbalances to achieve sideband separation beyond the possibilities of purely analog receivers. The technique could in principle allow the operation of 2SB receivers even when only imbalanced front ends can be built, particularly at very high frequencies. Results: This digital 2SB receiver shows an average sideband rejection of 45.9 dB while small portions of the band drop below 40 dB. The performance is 27 dB (a factor of 500) better than the average performance of the proof-of-concept Band 9 purely-analog 2SB prototype receiver.Comment: 5 page

Digital compensation of the side-band-rejection ratio in a fully analog 2SB sub-millimeter receiver

In observational radio astronomy, sideband-separating receivers are preferred, particularly under high atmospheric noise, which is usually the case in the sub-millimeter range. However, obtaining a good rejection ratio between the two sidebands is difficult since, unavoidably, imbalances in the different analog components appear. We describe a method to correct these imbalances without making any change in the analog part of the sideband-separating receiver, specifically, keeping the intermediate-frequency hybrid in place. This opens the possibility of implementing the method in any existing receiver. We have built hardware to demonstrate the validity of the method and tested it on a fully analog receiver operating between 600 and 720GHz. We have tested the stability of calibration and performance vs time and after full resets of the receiver. We have performed an error analysis to compare the digital compensation in two configurations of analog receivers, with and without intermediate frequency (IF) hybrid. An average compensated sideband rejection ratio of 46dB is obtained. Degradation of the compensated sideband rejection ratio on time and after several resets of the receiver is minimal. A receiver with an IF hybrid is more robust to systematic errors. Moreover, we have shown that the intrinsic random errors in calibration have the same impact for configuration without IF hybrid and for a configuration with IF hybrid with analog rejection ratio better than 10dB. Compensated rejection ratios above 40dB are obtained even in the presence of high analog rejection. The method is robust allowing its use under normal operational conditions at any telescope. We also demonstrate that a full analog receiver is more robust against systematic errors. Finally, the error bars associated to the compensated rejection ratio are almost independent of whether IF hybrid is present or not

Catalytic wet peroxide oxidation of imidazolium-based ionic liquids: Catalyst stability and biodegradability enhancement

This Accepted Manuscript will be available for reuse under a CC BY-NC-ND license after 24 months of embargo periodThe catalytic wet peroxide oxidation (CWPO) of the imidazolium-based ionic liquids 1-butyl-3-methylimidazolium chloride (BmimCl), 1-butyl-3-methylimidazolium acetate (BmimAc), 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BmimNTf2), 1-hexyl-3-methylimidazolium chloride (HmimCl) and 1-decyl-3-methylimidazolium chloride (DmimCl) was examined by using a Fe catalyst supported on alumina (Fe2O3/Al2O3) that was prepared by incipient wetness impregnation. Variable H2O2 doses from 0.5 to 1.5 times the stoichiometric value provided similar results in terms mg TOC removed per mg H2O2 decomposed at 80 °C (0.033 mgTOC mgH2O2−1), all allowing complete Bmim+ removal. Raising the reaction temperature to 90 °C increased the mineralization rate up to 40% TOC conversion. Differences in TOC conversion among counteranions (chloride, acetate and NTf2−) were negligible. A plausible reaction pathway is propose involving hydroxylated compounds and short-chain organic acids as reaction byproducts. CWPO markedly increased the subsequent biodegradability of the IL test solutions and led there to TOC conversions after CWPO-biodegradability assays of 55–60%. The Fe2O3/Al2O3 catalyst exhibited high long-term stability; thus, it retained most of its properties and underwent negligible Fe leaching.The authors acknowledge funding from Spain’s MINECO (CTM2016-76564-R), the Madrid Regional Government (S2013/MAE-2716), UAM-Santander (CEAL-AL/2015-08) and UNAM Engineering Institute (II-4307). I. F. Mena also thanks MINECO and ESF for award of a research gran

Study of the Calibration Channel Width for a Digital Sideband Separating System for SIS 2SB Receiver

A Digital Sideband Separating (DSS) system has been recently applied to a full 2SB receiver, i.e., one with the analog IF hybrid still in place. This concept allows reaching IRR level around 45 dB and it presents additional advantages in calibration stability compared to the case when no IF hybrid is present. If implemented in multipixel cameras, the DSS system relaxes the requirements for the IRR level of the analog receiver substantially enabling to reach at least an IRR of 30 dB with relatively simple hardware. It would be ideal for spectral line surveys since it practically eliminates the line confusion in addition to rejecting the atmospheric noise in the image band. Therefore, the DSS system is a potential option for a future ALMA upgrade. Here we present our study on an important practical question: how wide should the calibration-channel width in order to reach a desired IRR level? This parameter determines, for a large part, the calibration speed of the DSS system and influences the back-end architecture. We estimate that for currently installed ALMA bands (B3-B8), the channel width of the DSS system can be at least 45 MHz to reach a 30db IRR level in entire band

Eyespot resistance gene Pch-1 from Aegilops ventricosa is associated with a different chromosome in wheat line H-93-70 than the resistance factor in "Roazon" wheat

The hexaploid wheat line H-93-70 carries a gene (Pch-1) that has been transferred from the wild grass Aegilops ventricosa and confers a high degree of resistance to eyespot diesease, caused by the fungus Pseudocercosporella herpotrichoides. Crosses of the resistant line H-93-70 with the susceptible wheat Pané 247 and with a 7D/7Ag wheat/Agropyron substitution line were carried out and F2 kernels were obtained. The kernels were cut transversally and the halves carrying the embryos were used for the resistance test, while the distal halves were used for genetic typing. Biochemical markers were used to discriminate whether the transferred Pch-1 gene was located in chromosome 7D, as is the case for a resistance factor present in Roazon wheat. In the crosses involving Pané 247, resistance was not associated with the 7D locus Pln, which determines sterol ester pattern (dominant allele in H-93-70). In the crosses with the 7D/7Ag substitution line, resistance was neither associated with protein NGE-11 (7D marker), nor alternatively inherited with respect to protein C-7 (7Ag marker). It is concluded that gene Pch-1 represents a different locus and is not an allele of the resistance factor in Roazon whea

Does electro-peroxonation improve performance of electro-ozonation?

This work focuses on the comparison of the degradation and mineralization of clopyralid with electrochemically produced hydrogen peroxide (electro-H2O2), ozone (electro-ozonation) and their mixture (electro-peroxone) and points out important differences among the performance of the oxidation technologies. Co-existence of electrochemically produced hydrogen peroxide and ozone decreases the concentration of ozone and increases the concentration of hydrogen peroxide in the bulk, because of the formation and recombination of hydroxyl radicals. Oxidation of clopyralid and mineralization of the wastewater is less efficient with hydrogen peroxide and more efficient with ozone. Peroxone shows an intermediate performance which can be related with the oxidant’s speciation produced in the wastewater. Different behavior between in situ electrochemically produced ozone and ozone dosed, indicates activation of ozone in the electrolyte during the electro-ozonation process. Results highlights the good performance of the simple electro-ozonation that overcomes other EAOPs and indicates than combination of powerful oxidants in this case does not result in the expected synergism but in antagonistic responses.Este trabajo se centra en la comparación de la degradación y mineralización de la clopiralida con peróxido de hidrógeno producido electroquímicamente (electro-H 2 O 2 ), ozono (electro-ozonización) y su mezcla (electro-peroxona) y señala diferencias importantes entre el rendimiento de Las tecnologías de oxidación. La coexistencia de peróxido de hidrógeno y ozono producidos electroquímicamente disminuye la concentración de ozono y aumenta la concentración de peróxido de hidrógeno a granel, debido a la formación y recombinación de radicales hidroxilo.. La oxidación de clopiralida y la mineralización de las aguas residuales es menos eficiente con peróxido de hidrógeno y más eficiente con ozono. La peroxona muestra un comportamiento intermedio que se puede relacionar con la especiación del oxidante producido en las aguas residuales. El diferente comportamiento entre el ozono producido electroquímicamente in situ y el ozono dosificado, indica la activación del ozono en el electrolito durante el proceso de electro-ozonización. Los resultados destacan el buen desempeño de la electro-ozonización simple que supera a otros EAOP e indica que la combinación de potentes oxidantes en este caso no da como resultado el sinergismo esperado sino respuestas antagónicas

The glutathione biosynthetic pathway of Plasmodium is essential for mosquito transmission

1Infection of red blood cells (RBC) subjects the malaria parasite to oxidative stress. Therefore, efficient antioxidant and redox systems are required to prevent damage by reactive oxygen species. Plasmodium spp. have thioredoxin and glutathione (GSH) systems that are thought to play a major role as antioxidants during blood stage infection. In this report, we analyzed a critical component of the GSH biosynthesis pathway using reverse genetics. Plasmodium berghei parasites lacking expression of gamma-glutamylcysteine synthetase (γ-GCS), the rate limiting enzyme in de novo synthesis of GSH, were generated through targeted gene disruption thus demonstrating, quite unexpectedly, that γ-GCS is not essential for blood stage development. Despite a significant reduction in GSH levels, blood stage forms of pbggcs− parasites showed only a defect in growth as compared to wild type. In contrast, a dramatic effect on development of the parasites in the mosquito was observed. Infection of mosquitoes with pbggcs− parasites resulted in reduced numbers of stunted oocysts that did not produce sporozoites. These results have important implications for the design of drugs aiming at interfering with the GSH redox-system in blood stages and demonstrate that de novo synthesis of GSH is pivotal for development of Plasmodium in the mosquito