Application of a radiometric calibration method to lunar Fourier transform IR spectra by using a liquid-nitrogen-cooled high-emissivity blackbody

Since winter 1994/1995 the Moon has been used in addition to the Sun as an IR source of radiation to measure atmospheric absorption spectra with a Bruker IR Fourier transform spectrometer IFS 120M located near Kiruna, Sweden. A two-point radiometric calibration method with blackbody references was applied to lunar spectra in the long-wave detector channel to improve the accuracy of evaluation of the column amounts of different atmospheric trace gases. A new liquid-nitrogen-cooled high-emissivity blackbody without an entrance window is described that is used for this calibration method.     

Biodiversity offsets in South Africa – challenges and potential solutions

South Africa has a decade of experience designing and implementing biodiversity offsets. In the absence of explicit national policy on biodiversity offsets, the country has relied on existing legal provisions in environmental law as the basis for offset requirements, supported by provincial guidelines. South Africa’s periodic national biodiversity surveys provide scientifically rigorous quantification and mapping for individual ecosystems and finer scale surveys identify biodiversity priority areas, primed as ‘offset receiving areas’. Yet despite enabling factors the use of offsets has frequently been inadequate to deliver intended biodiversity outcomes. Challenges include: (a) the absence of national policy to drive and shape offset implementation; (b) insufficient capacity to evaluate, design and implement offsets; (c) inconsistent decision-making; (d) problems establishing sustainable financing mechanisms; and (e) inadequate enforcement and monitoring, linked to poor drafting of licencing conditions and/or insufficient capacity to monitor implementation. South Africa’s experience provides valuable insights into the challenges and potential solutions for making offsets work for biodiversity conservation and offers important lessons for the development and implementation of biodiversity offsetting in other developing countries.     

Stereochemistry of the hydroperoxides formed during autoxidation of CLA methyl ester in the presence of α-tocopherol

The initial steps in the autoxidation of CLA methyl ester are poorly understood. The aim of this study was to determine the stereochemistry of the hydroperoxides formed during autoxidation of CLA methyl ester in the presence of a good hydrogen atom donor. For this purpose, 9-cis, 11-trans CLA methyl ester was autoxidized in the presence of α-tocopherol under atmospheric oxygen at 40°C in the dark. The CLA methyl ester hydroperoxides were isolated, reduced to the corresponding hydroxy derivatives, and separated by HPLC. The stereochemistry of seven hydroxy-CLA methyl esters was investigated. The position of the hydroxy group was determined by GC-MS. The geometry as well as the position of the double bonds in the alkyl chain was determined by NMR. In addition, the ¹³C NMR spectra of six hydroxy-CLA methyl esters were assigned using COSY, gradient heteronuclear multiple bond correlation, gradient heteronuclear single quantum correlation, and total correlation spectroscopy experiments. The autoxidation of 9-cis, 11-trans CLA methyl ester in the presence of a good hydrogen atom donor is stereoselective in favor of one geometric isomer, namely the 13-(R,S)-hydroperoxy-9-cis, 11-trans-octadecadienoic acid methyl ester. Three types of conjugated diene hydroperoxides are formed as primary hydroperoxides: trans,trans hydroperoxides (12-OOH-8t,10t and 9-OOH-10t,12t), a cis,trans hydroperoxide with the trans double bond adjacent to the hydroperoxide-bearing carbon atom (13-OOH-9c,11t), and a new type of cis,trans lipid hydroperoxide with the cis double bond adjacent to the hydroperoxide-bearing carbon atom (8-OOH-9c,11t). In addition, three nonkinetic hydroperoxides (13-OOH-9t,11t, 8-OOH-9t,11t, and 9-OOH-10t,12c) are formed. This study supports the theory that CLA methyl ester autoxidizes at least partly through an autocatalytic free radical reaction. The complexity of the hydroperoxide mixture is due to formation of two different pentadienyl radicals. Moreover, the stereoslectivity in favor of one geometric isomer can be explained by the selectivity of the two previous steps: the preferential formation of a W-conformer of the pentadienyl radical over the Z-conformer, and regioselectivity of the oxygen addition to the pentadienyl radical.     

A new approach to obtain mesoporous-activated carbon via hydrothermal carbonization of Brazilian Cerrado biomass combined with physical activation for bisphenol-A removal

Abstract

The worrying hydric crisis and the increasing water contamination by emerging pollutants around the world stimulate the development of activated carbons (AC) for the removal of endocrine disruptors, including bisphenol-A (BPA). For this reason, a new approach for the synthesis of AC from hydrochar produced through hydrothermal carbonization (HTC) of Brazilian Cerrado biomass (Magonia pubescens–Sapindaceae) and physical activation using water vapor is highlighted. Compared to the traditional method of physical activation after pyrolysis, HTC was found to be better option to develop the specific surface area, porosity, and yield of the ACs, which presented mesoporous structure and carbon content higher than 80%. The BPA adsorption was evaluated by varying the contact time, BPA concentration, and pH. The Langmuir, Freundlich, and Redlich–Peterson isotherms were used to model the adsorption behavior. In the preliminary test to verify the adsorption efficiency, the AC obtained from hydrochar treated at 180?°C presented better results compared to commercial AC. The BPA adsorption data of the best treated hydrochar correlated well with the pseudo first-order model and the Langmuir isotherm (Q_max = 21.26?mg g^?1). The results of the studies indicated the combination of HTC and physical activation with steam to be an efficient way to prepare an ecologically sound adsorbent for removal of Bisphenol-A from water with lower temperature and without chemical reagents. The ACs obtained can also be potential materials for other applications, such as in the field of catalysis and environmental remediation.     

Origin of bicyclic fatty acids in tall oil

It was shown that two bicyclic fatty acids present in Finnish tall oil were formed from (5Z, 9Z, 12Z)-5, 9, 12-octadecatrienoic acid, pinolenic acid (I). Under the alkaline conditions of sulfate pulping, pinolenic acid forms conjugated isomers which undergo Diels-Alder cyclization during the heating in the tall oil distillation. The cyclization products, here called cyclopinolenic acids, are bicyclic fatty acids and stereoisomers of 4-(5-pentyl-3a, 4,5,7a-tetrahydro-4-indanyl) butanoic acid (IV and V).     

Experimental Study of Transformer Residual Flux and the Method of Restraining Inrush Current

Whenever a power transformer in a no‐load condition is manually tripped, a residual flux appears in the transformer core, which causes an inrush current when the transformer is later re‐energized. However, the true nature of residual fluxes has not yet been experimentally elucidated. The authors interpreted the residual flux as representing the ending states of transient phenomena after tripping, and tested this interpretation experimentally. In the authors' interpretation, a three‐phase balanced transient phenomenon of the voltage, current, and core flux occurs immediately after the transformer is tripped at the time t_op0, and it continues until time t_op1. The true nature of the residual flux is the core fluxes , , at t_op1. Furthermore, these residual fluxes as well as the voltages and currents during the transient interval are practically three‐phase balanced, so that they can be expressed as three‐phase balanced equilateral triangular phasors. The core flux values and waveforms cannot be directly measured but they can be digitally generated as the integrals of the voltage waveform. Thus a test of the residual flux under the above interpretation can be performed indirectly by preparing (1) measured voltage waveforms just after transformer tripping, (2) flux waveforms mathematically generated by voltage integration just after tripping, and (3) measured transient inrush current , , , occurring immediately after the transformer is re‐energized at time θcl, and then comparing these three data as characteristics in the 3‐D coordinates of and of . Verification tests were performed utilizing a simulation test circuit in which large numbers of on–off switching tests of a transformer were conducted. The test results clearly indicated that the inrush current reaches its maximum whenever θ_cl is in antiphase with θ_op1 (instead of θ_op0), and reaches its minimum whenever θ_cl is in phase with θ_op1. These test results confirmed the authors' interpretation of the true nature of the transient phenomena and the residual flux after tripping. The test results suggest essential algorithms for inrush current restraining control in order to appropriately restrain inrush current phenomena. Field test results at a 66‐kV wind power station where commercial equipment based on the above described theory and method were in service are also presented.     

Organophosphorus flame retardants and plasticizers in Swedish sewage treatment plants

The levels, distribution, and possible sources of 12 organophosphorus flame retardants and plasticizers, some of which are reported to be toxic to aquatic organisms, were investigated in samples of influents, effluents, and sludge from 11 Swedish sewage treatment plants (STPs). The organophosphorus compounds (OPs) studied were poorly removed from the wastewater; especially the chlorinated OPs tended to pass through the STPs without being removed or degraded, while alkyl-OPs, such as tributyl phosphate (TBP), were more successfully removed. In both influents and effluents, tris(2-butoxyethyl) phosphate and TBP were the most prominent substances followed by tris(2-chloroisopropyl) phosphate (TCPP). The highest concentration of any individual OP detected in the influents was 52 microg L(-1) (TBP). Ethylhexyl diphenyl phosphate and TCPP dominated in all sludge samples. A budget calculation comparing the annual amount of OPs in the influent received by Swedish STPs with the known amount of OPs imported indicated that approximately 15% is emitted to STPs. Of the total amount of OPs reaching the STPs annually, 49% is degraded, 50% (27 tons) is emitted to the recipients, and only 1% ends up in the sludge. The concentrations of most OPs were quite similar among the sampled STPs, indicating that the data may be applicable in other STPs.