ВЫБОР ЭКСТРАКТИВНЫХ АГЕНТОВ ДЛЯ РАЗДЕЛЕНИЯ СМЕСИ ХЛОРОФОРМ - МЕТАНОЛ -ТЕТРАГИДРОФУРАН

Variants of the extractive distillation of chloroform - methanol - tetrahydrofuran equimolar mixture with industrial separating agents are considered. The basic system shows opposite deviations from the ideal behavior, because it contains binary azeotropes with minimum and maximum boiling points (3.3.1-4 system according to Serafimov’s classification). The choice of selective substances for extractive distillation was carried out taking into account the concentration dependences of the excess molar Gibbs energy of the binary constituents of the derivative system “chloroform - methanol - tetrahydrofuran - industrial test agent (ethylene glycol (EG), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (N-MP))” at 101.32 kPa. Based on the results of the evaluation of the thermodynamic criterion, DMSO and N-MP are recommended. Both agents show selective effect when separating two binary constituents. EG is selective only with respect to chloroform-tetrahydrofuran mixture. Since the tested agents show different selective effects, the final agent choice determines the qualitative composition of the product flows in the column for the extractive distillation of the three-component mixture (the first column of the flowsheet) and, accordingly, the structure of the total flowsheet. The schemes consist of two two-column complexes for extractive distillation (for the basic three-component mixture and for the binary mixture). The maximum contribution to the total reboiler energy consumption of the distillation columns is made by the first extractive distillation column: 65% (EG), 53% (N-MP) and 24% (DMSO). The use of the most selective agent reduces the energy consumption of this column: the reboiler load is maximal in the case of EG, in comparison with which the load is 47% lower in the case of N-MP and 76% lower in the case of DMSO.Рассмотрены варианты экстрактивной ректификации эквимолярной смеси хлороформ - метанол - тетрагидрофуран с промышленными разделяющими агентами. Базовая система проявляет разноименные отклонения от идеального поведения, так как содержит бинарные азеотропы с минимальной и максимальной температурой кипения (система 3.3.1-4 по классификации Л.А. Серафимова). Выбор селективных веществ для экстрактивной ректификации трехкомпонентной смеси проведен с учетом концентрационных зависимостей избыточной молярной энергии Гиббса бинарных составляющих производной системы хлороформ - метанол - тетрагидрофуран - тестируемый промышленный агент: этиленгликоль (ЭГ), диметилсульфоксид (ДМСО), N-метилпирролидон (N-МП) при 101.32 кПа. По результатам оценки термодинамического критерия рекомендованы ДМСО и N-МП, которые проявляют селективное действие при разделении двух бинарных составляющих. ЭГ селективен только в отношении смеси хлороформ - тетрагидрофуран. Поскольку тестируемые агенты проявляют различное селективное действие, выбор агента определяет качественный состав продуктовых потоков колонны экстрактивной ректификации трехкомпонентной смеси (первая колонна схем разделения) и, соответственно, структуру схем в целом. Схемы состоят их двухколонных комплексов экстрактивной ректификации: базовой трехкомпонентной смеси и бинарной азеотропной смеси. Максимальный вклад в суммарные энергозатраты на разделение (нагрузка кипятильника ректификационной колонны) во всех вариантах вносит колонна экстрактивной ректификации трехкомпонентной смеси, который составляет: 65 % (ЭГ), 53 % (N-МП) и 24 % (ДМСО). Применение наиболее селективного агента обеспечивает снижение энергозатрат этой колонны: нагрузка на кипятильник максимальна в случае ЭГ, в сравнении с которым при использовании N-МП нагрузка ниже на 47 % , для ДМСО - на 76 %

Mining conflicts around the world: Common grounds from an Environmental Justice perspective

Abstract. This report aims at exploring contemporary mining conflicts in the context of the sustainable development and environmental justice movement. This is done based on 24 real case studies from 18 different countries which are described by local activists and scholars. While 17 of the reported cases focus on conflicts related to metal mining (e.g. gold, silver, copper, zinc, and lead), four address uranium mining and one refers to coal mining. As an example of a new frontier in the industry, a sand mining conflict from India is also reported. All of these cases are directly chosen and reported, either in factsheet or in-depth study format, by EJOs, as part of a knowledge sharing activity well-established in EJOLT between EJOs and the academic community. Although the cases covered here are all quite unique and diverse in terms of type of conflict and geographical setting, they all share a common frame of analysis. First, the project and type of conflict are characterized in a nutshell, with some basic factual background that describe the companies involved, and the communities and locations affected. The roots of the conflicts are explored next, as well as relevant socioeconomic, cultural, health, and ecological impacts and related community claims. Where relevant, means of resistance are also specified with their influence on the project and/or the outcome of the conflict. The report then offers a synthesis of the described mining cases, review their commonalities, link gained insights with research needs and discuss some policy recommendations that might follow from this analysis. Despite its limitations, compiling such a diverse set of mining conflicts that builds on EJO knowledge promotes mutual learning and collaboration among stakeholders, EJOs and academia, which is one of the key objectives of EJOLT

Критерий выбора потенциальных разделяющих агентов экстрактивной ректификации

Criterion of formation of possible entrainers set for extractive distillation process of binary mixtures containing minimum boiling azeotrope has been developed.Рассмотрен критерий формирования множества потенциальных разделяющих агентов для экстрактивной ректификации бинарных азеотропных смесей с положительными азеотропам

Evaluation of Intra-Host Variants of the Entire Hepatitis B Virus Genome

Genetic analysis of hepatitis B virus (HBV) frequently involves study of intra-host variants, identification of which is commonly achieved using short regions of the HBV genome. However, the use of short sequences significantly limits evaluation of genetic relatedness among HBV strains. Although analysis of HBV complete genomes using genetic cloning has been developed, its application is highly labor intensive and practiced only infrequently. We describe here a novel approach to whole genome (WG) HBV quasispecies analysis based on end-point, limiting-dilution real-time PCR (EPLD-PCR) for amplification of single HBV genome variants, and their subsequent sequencing. EPLD-PCR was used to analyze WG quasispecies from serum samples of patients (n = 38) infected with HBV genotypes A, B, C, D, E and G. Phylogenetic analysis of the EPLD-isolated HBV-WG quasispecies showed the presence of mixed genotypes, recombinant variants and sub-populations of the virus. A critical observation was that HBV-WG consensus sequences obtained by direct sequencing of PCR fragments without EPLD are genetically close, but not always identical to the major HBV variants in the intra-host population, thus indicating that consensus sequences should be judiciously used in genetic analysis. Sequence-based studies of HBV WG quasispecies should afford a more accurate assessment of HBV evolution in various clinical and epidemiological settings

Epidemic History and Evolutionary Dynamics of Hepatitis B Virus Infection in Two Remote Communities in Rural Nigeria

BACKGROUND: In Nigeria, hepatitis B virus (HBV) infection has reached hyperendemic levels and its nature and origin have been described as a puzzle. In this study, we investigated the molecular epidemiology and epidemic history of HBV infection in two semi-isolated rural communities in North/Central Nigeria. It was expected that only a few, if any, HBV strains could have been introduced and effectively transmitted among these residents, reflecting limited contacts of these communities with the general population in the country. METHODS AND FINDINGS: Despite remoteness and isolation, approximately 11% of the entire population in these communities was HBV-DNA seropositive. Analyses of the S-gene sequences obtained from 55 HBV-seropositive individuals showed the circulation of 37 distinct HBV variants. These HBV isolates belong predominantly to genotype E (HBV/E) (n=53, 96.4%), with only 2 classified as sub-genotype A3 (HBV/A3). Phylogenetic analysis showed extensive intermixing between HBV/E variants identified in these communities and different countries in Africa. Quasispecies analysis of 22 HBV/E strains using end-point limiting-dilution real-time PCR, sequencing and median joining networks showed extensive intra-host heterogeneity and inter-host variant sharing. To investigate events that resulted in such remarkable HBV/E diversity, HBV full-size genome sequences were obtained from 47 HBV/E infected persons and P gene was subjected to Bayesian coalescent analysis. The time to the most recent common ancestor (tMRCA) for these HBV/E variants was estimated to be year 1952 (95% highest posterior density (95% HPD): 1927-1970). Using additional HBV/E sequences from other African countries, the tMRCA was estimated to be year 1948 (95% HPD: 1924-1966), indicating that HBV/E in these remote communities has a similar time of origin with multiple HBV/E variants broadly circulating in West/Central Africa. Phylogenetic analysis and statistical neutrality tests suggested rapid HBV/E population expansion. Additionally, skyline plot analysis showed an increase in the size of the HBV/E-infected population over the last approximately 30-40 years. CONCLUSIONS: Our data suggest a massive introduction and relatively recent HBV/E expansion in the human population in Africa. Collectively, these data show a significant shift in the HBV/E epidemic dynamics in Africa over the last century

VOLUME COMPUTATION OF A STOCKPILE – A STUDY CASE COMPARING GPS AND UAV MEASUREMENTS IN AN OPEN PIT QUARRY

The following paper aims to test and evaluate the accuracy of UAV data for volumetric measurements to the conventional GNSS techniques. For this purpose, an appropriate open pit quarry has been chosen. Two sets of measurements were performed. Firstly, a stockpile was measured by GNSS technologies and later other terrestrial GNSS measurements for modelling the berms of the quarry were taken. Secondly, the area of the whole quarry including the stockpile site was mapped by a UAV flight. Having considered how dynamic our world is, new techniques and methods should be presented in numerous fields. For instance, the management of an open pit quarry requires gaining, processing and storing a large amount of information which is constantly changing with time. Fast and precise acquisition of measurements regarding the process taking place in a quarry is the key to an effective and stable maintenance. In other words, this means getting an objective evaluations of the processes, using up-to-date technologies and reliable accuracy of the results. Often legislations concerning mine engineering state that the volumetric calculations are to present ±3% accuracy of the whole amount. On one hand, extremely precise measurements could be performed by GNSS technologies, however, it could be really time consuming. On the other hand, UAV photogrammetry presents a fast, accurate method for mapping large areas and calculating stockpiles volumes. The study case was performed as a part of a master thesis