Usporedba kemijskih i fizikalno-kemijskih metoda obezbojavanja otpadnih voda

Today\u27s chemical and physical-chemical wastewater discoloration methods do not completely meet demands regarding degree of discoloration. In this paper discoloration was performed using Fenton (FeSO4 · 7 H2O + H2O2 + H2SO4) and Fenton-like (FeCl3 · 6 H2O + H2O2 + HCOOH) chemical methods and physical-chemical method of coagulation/flocculation (using poly-electrolyte (POEL) combining anion active coagulant (modified poly-acrylamides) and cationic flocculant (product of nitrogen compounds) in combination with adsorption on activated carbon. Suitability of aforementioned methods was investigated on reactive and acid dyes, regarding their most common use in the textile industry. Also, investigations on dyes of different chromogen (anthraquinone, phthalocyanine, azo and xanthene) were carried out in order to determine the importance of molecular spatial structure. Oxidative effect of Fenton and Fenton-like reagents resulted in decomposition of colored chromogen and high degree of discoloration. However, the problem is the inability of adding POEL in stechiometrical ratio (also present in physical-chemical methods), when the phenomenon of overdosing coagulants occurs in order to obtain a higher degree of discoloration, creating a potential danger of burdening water with POEL. Input and output water quality was controlled through spectrophotometric measurements and standard biological parameters. In addition, part of the investigations concerned industrial wastewaters obtained from dyeing cotton materials using reactive dye (C. I. Reactive Blue 19), a process that demands the use of vast amounts of electrolytes. Also, investigations of industrial wastewaters was labeled as a crucial step carried out in order to avoid serious misassumptions and false conclusions, which may arise if dyeing processes are only simulated in the laboratory.Današnje kemijske i fizikalno-kemijske metode obezbojavanja otpadnih voda ne zadovoljavaju u potpunosti zahtjeve vezane uz stupanj obezbojavanja. U ovom radu obezbojavanje se provodilo pomoću Fentonove kemijske metode (FeSO4· 7 H2O + H2O2 + H2SO4) i modificirane Fentonove kemijske metode (FeCl3 · 6 H2O+H2O2+ HCOOH), te pomoću fizikalno-kemijske metode upotrebom koagulanata/flokulanata (polielektrolita-POEL), koja kombinira anionski koagulant (modificirani poliakrilamid) i kationski flokulant (produkt dušikovih spojeva) uz adsorpciju na aktivnom ugljenu. Prihvatljivost opisanih metoda ispitivana je za reaktivna i kisela bojila, s obzirom na njihovu raširenu primjenu u tekstilnoj industriji. Također, provedena su ispitivanja na bojilima različitih kromogena (antrakinon, ftalocijanin, azo i ksanten) s ciljem određivanja važnosti prostorne strukture molekule. Oksidativno djelovanje Fentonovog i modificiranog Fentonovog postupka dovodi do razgradnje obojenog kromogena i visokog stupnja obezbojavanja. Međutim, ustanovljena je nemogućnost dodavanja POEL u stehiometrijskom odnosu (također prisutno kod modificiranog Fentonovog postupka), odnosno dodavanje koagulanata u suvišku kako bi se postigao viši stupanj obezbojavanja, što u konačnici dovodi do opterećenja voda POEL-ima. Kvaliteta vode na ulazu i izlazu kontrolirana je pomoću spektrofotometrijskih mjerenja i uobičajenih bioloških parametara. U prilog tome, dio ispitivanja bio je vezan za industrijske otpadne vode bojadisaone, u kojoj se pamučni materijal bojadisao bojilom C. I. Reactive Blue 19 i to tehnološkim postupkom koji zahtijeva uporabu velike količine elektrolita. Također, ispitivanje industrijskih otpadnih voda označeno je ključnim korakom izbjegavanja niza krivih pretpostavki i zaključaka, koji bi mogli nastati u slučaju laboratorijskog simuliranja procesa bojadisanja

Usporedba kemijskih i fizikalno-kemijskih metoda obezbojavanja otpadnih voda

Today\u27s chemical and physical-chemical wastewater discoloration methods do not completely meet demands regarding degree of discoloration. In this paper discoloration was performed using Fenton (FeSO4 · 7 H2O + H2O2 + H2SO4) and Fenton-like (FeCl3 · 6 H2O + H2O2 + HCOOH) chemical methods and physical-chemical method of coagulation/flocculation (using poly-electrolyte (POEL) combining anion active coagulant (modified poly-acrylamides) and cationic flocculant (product of nitrogen compounds) in combination with adsorption on activated carbon. Suitability of aforementioned methods was investigated on reactive and acid dyes, regarding their most common use in the textile industry. Also, investigations on dyes of different chromogen (anthraquinone, phthalocyanine, azo and xanthene) were carried out in order to determine the importance of molecular spatial structure. Oxidative effect of Fenton and Fenton-like reagents resulted in decomposition of colored chromogen and high degree of discoloration. However, the problem is the inability of adding POEL in stechiometrical ratio (also present in physical-chemical methods), when the phenomenon of overdosing coagulants occurs in order to obtain a higher degree of discoloration, creating a potential danger of burdening water with POEL. Input and output water quality was controlled through spectrophotometric measurements and standard biological parameters. In addition, part of the investigations concerned industrial wastewaters obtained from dyeing cotton materials using reactive dye (C. I. Reactive Blue 19), a process that demands the use of vast amounts of electrolytes. Also, investigations of industrial wastewaters was labeled as a crucial step carried out in order to avoid serious misassumptions and false conclusions, which may arise if dyeing processes are only simulated in the laboratory.Današnje kemijske i fizikalno-kemijske metode obezbojavanja otpadnih voda ne zadovoljavaju u potpunosti zahtjeve vezane uz stupanj obezbojavanja. U ovom radu obezbojavanje se provodilo pomoću Fentonove kemijske metode (FeSO4· 7 H2O + H2O2 + H2SO4) i modificirane Fentonove kemijske metode (FeCl3 · 6 H2O+H2O2+ HCOOH), te pomoću fizikalno-kemijske metode upotrebom koagulanata/flokulanata (polielektrolita-POEL), koja kombinira anionski koagulant (modificirani poliakrilamid) i kationski flokulant (produkt dušikovih spojeva) uz adsorpciju na aktivnom ugljenu. Prihvatljivost opisanih metoda ispitivana je za reaktivna i kisela bojila, s obzirom na njihovu raširenu primjenu u tekstilnoj industriji. Također, provedena su ispitivanja na bojilima različitih kromogena (antrakinon, ftalocijanin, azo i ksanten) s ciljem određivanja važnosti prostorne strukture molekule. Oksidativno djelovanje Fentonovog i modificiranog Fentonovog postupka dovodi do razgradnje obojenog kromogena i visokog stupnja obezbojavanja. Međutim, ustanovljena je nemogućnost dodavanja POEL u stehiometrijskom odnosu (također prisutno kod modificiranog Fentonovog postupka), odnosno dodavanje koagulanata u suvišku kako bi se postigao viši stupanj obezbojavanja, što u konačnici dovodi do opterećenja voda POEL-ima. Kvaliteta vode na ulazu i izlazu kontrolirana je pomoću spektrofotometrijskih mjerenja i uobičajenih bioloških parametara. U prilog tome, dio ispitivanja bio je vezan za industrijske otpadne vode bojadisaone, u kojoj se pamučni materijal bojadisao bojilom C. I. Reactive Blue 19 i to tehnološkim postupkom koji zahtijeva uporabu velike količine elektrolita. Također, ispitivanje industrijskih otpadnih voda označeno je ključnim korakom izbjegavanja niza krivih pretpostavki i zaključaka, koji bi mogli nastati u slučaju laboratorijskog simuliranja procesa bojadisanja

Constraint-Based Model of Shewanella Oneidensis MR-1 Metabolism: A Tool for Data Analysis and Hypothesis Generation

Shewanellae are gram-negative facultatively anaerobic metal-reducing bacteria commonly found in chemically (i.e., redox) stratified environments. Occupying such niches requires the ability to rapidly acclimate to changes in electron donor/acceptor type and availability; hence, the ability to compete and thrive in such environments must ultimately be reflected in the organization and utilization of electron transfer networks, as well as central and peripheral carbon metabolism. To understand how Shewanella oneidensis MR-1 utilizes its resources, the metabolic network was reconstructed. The resulting network consists of 774 reactions, 783 genes, and 634 unique metabolites and contains biosynthesis pathways for all cell constituents. Using constraint-based modeling, we investigated aerobic growth of S. oneidensis MR-1 on numerous carbon sources. To achieve this, we (i) used experimental data to formulate a biomass equation and estimate cellular ATP requirements, (ii) developed an approach to identify cycles (such as futile cycles and circulations), (iii) classified how reaction usage affects cellular growth, (iv) predicted cellular biomass yields on different carbon sources and compared model predictions to experimental measurements, and (v) used experimental results to refine metabolic fluxes for growth on lactate. The results revealed that aerobic lactate-grown cells of S. oneidensis MR-1 used less efficient enzymes to couple electron transport to proton motive force generation, and possibly operated at least one futile cycle involving malic enzymes. Several examples are provided whereby model predictions were validated by experimental data, in particular the role of serine hydroxymethyltransferase and glycine cleavage system in the metabolism of one-carbon units, and growth on different sources of carbon and energy. This work illustrates how integration of computational and experimental efforts facilitates the understanding of microbial metabolism at a systems level

Mass and Angular Momentum Transfer in the Massive Algol Binary RY Persei

We present an investigation of H-alpha emission line variations observed in the massive Algol binary, RY Per. We give new radial velocity data for the secondary based upon our optical spectra and for the primary based upon high dispersion UV spectra. We present revised orbital elements and an estimate of the primary's projected rotational velocity (which indicates that the primary is rotating 7 times faster than synchronous). We use a Doppler tomography algorithm to reconstruct the individual primary and secondary spectra in the region of H-alpha, and we subtract the latter from each of our observations to obtain profiles of the primary and its disk alone. Our H-alpha observations of RY Per show that the mass gaining primary is surrounded by a persistent but time variable accretion disk. The profile that is observed outside-of-eclipse has weak, double-peaked emission flanking a deep central absorption, and we find that these properties can be reproduced by a disk model that includes the absorption of photospheric light by the band of the disk seen in projection against the face of the star. We developed a new method to reconstruct the disk surface density distribution from the ensemble of H-alpha profiles observed around the orbit, and this method accounts for the effects of disk occultation by the stellar components, the obscuration of the primary by the disk, and flux contributions from optically thick disk elements. The resulting surface density distribution is elongated along the axis joining the stars, in the same way as seen in hydrodynamical simulations of gas flows that strike the mass gainer near trailing edge of the star. This type of gas stream configuration is optimal for the transfer of angular momentum, and we show that rapid rotation is found in other Algols that have passed through a similar stage.Comment: 39 pages, 12 figures, ApJ in press, 2004 June 20 issu

Long-term stability of TES satellite radiance measurements

The utilization of Tropospheric Emission Spectrometer (TES) Level 2 (L2) retrieval products for the purpose of assessing long term changes in atmospheric trace gas composition requires knowledge of the overall radiometric stability of the Level 1B (L1B) radiances. The purpose of this study is to evaluate the stability of the radiometric calibration of the TES instrument by analyzing the difference between measured and calculated brightness temperatures in selected window regions of the spectrum. The Global Modeling and Assimilation Office (GMAO) profiles for temperature and water vapor and the Real-Time Global Sea Surface Temperature (RTGSST) are used as input to the Optimal Spectral Sampling (OSS) radiative transfer model to calculate the simulated spectra. The TES reference measurements selected cover a 4-year period of time from mid 2005 through mid 2009 with the selection criteria being; observation latitudes greater than −30° and less than 30°, over ocean, Global Survey mode (nadir view) and retrieved cloud optical depth of less than or equal to 0.01. The TES cloud optical depth retrievals are used only for screening purposes and no effects of clouds on the radiances are included in the forward model. This initial screening results in over 55 000 potential reference spectra spanning the four year period. Presented is a trend analysis of the time series of the residuals (observation minus calculations) in the TES 2B1, 1B2, 2A1, and 1A1 bands, with the standard deviation of the residuals being approximately equal to 0.6 K for bands 2B1, 1B2, 2A1, and 0.9 K for band 1A1. The analysis demonstrates that the trend in the residuals is not significantly different from zero over the 4-year period. This is one method used to demonstrate that the relative radiometric calibration is stable over time, which is very important for any longer term analysis of TES retrieved products (L2), particularly well-mixed species such as carbon dioxide and methane

Highly Ionized Collimated Outflow from HE 0238 - 1904

We present a detailed analysis of a highly ionized, multiphased and collimated outflowing gas detected through O V, O VI, Ne VIII and Mg X absorption associated with the QSO HE 0238 - 1904 (z_em ~ 0.629). Based on the similarities in the absorption line profiles and estimated covering fractions, we find that the O VI and Ne VIII absorption trace the same phase of the absorbing gas. Simple photoionization models can reproduce the observed N(Ne VIII), N(O VI) and N(Mg X) from a single phase whereas the low ionization species (e.g. N III, N IV, O IV) originate from a different phase. The measured N(Ne VIII)/N(O VI) ratio is found to be remarkably similar (within a factor of ~ 2) in several individual absorption components kinematically spread over ~ 1800 km/s. Under photoionization this requires a fine tuning between hydrogen density (nH) and the distance of the absorbing gas from the QSO. Alternatively this can also be explained by collisional ionization in hot gas with T > 10^{5.7} K. Long-term stability favors the absorbing gas being located outside the broad line region (BLR). We speculate that the collimated flow of such a hot gas could possibly be triggered by the radio jet interaction.Comment: Minor revision (accepted for publication in MNRAS letter

Mechanism of Translation Inhibition by Type II GNAT Toxin AtaT2

Type II toxin-antitoxins systems are widespread in prokaryotic genomes. Typically, they comprise two proteins, a toxin, and an antitoxin, encoded by adjacent genes and forming a complex in which the enzymatic activity of the toxin is inhibited. Under stress conditions, the antitoxin is degraded liberating the active toxin. Though thousands of various toxin-antitoxins pairs have been predicted bioinformatically, only a handful has been thoroughly characterized. Here, we describe the AtaT2 toxin from a toxin-antitoxin system from Escherichia coli O157:H7. We show that AtaT2 is the first GNAT (Gcn5-related N-acetyltransferase) toxin that specifically targets charged glycyl tRNA. In vivo, the AtaT2 activity induces ribosome stalling at all four glycyl codons but does not evoke a stringent response. In vitro, AtaT2 acetylates the aminoacyl moiety of isoaccepting glycyl tRNAs, thus precluding their participation in translation. Our study broadens the known target specificity of GNAT toxins beyond the earlier described isoleucine and formyl methionine tRNAs, and suggest that various GNAT toxins may have evolved to specifically target other if not all individual aminoacyl tRNAs

Multifaceted Mechanism of Amicoumacin A Inhibition of Bacterial Translation

Amicoumacin A (Ami) halts bacterial growth by inhibiting the ribosome during translation. The Ami binding site locates in the vicinity of the E-site codon of mRNA. However, Ami does not clash with mRNA, rather stabilizes it, which is relatively unusual and implies a unique way of translation inhibition. In this work, we performed a kinetic and thermodynamic investigation of Ami influence on the main steps of polypeptide synthesis. We show that Ami reduces the rate of the functional canonical 70S initiation complex (IC) formation by 30-fold. Additionally, our results indicate that Ami promotes the formation of erroneous 30S ICs; however, IF3 prevents them from progressing towards translation initiation. During early elongation steps, Ami does not compromise EF-Tu-dependent A-site binding or peptide bond formation. On the other hand, Ami reduces the rate of peptidyl-tRNA movement from the A to the P site and significantly decreases the amount of the ribosomes capable of polypeptide synthesis. Our data indicate that Ami progressively decreases the activity of translating ribosomes that may appear to be the main inhibitory mechanism of Ami. Indeed, the use of EF-G mutants that confer resistance to Ami (G542V, G581A, or ins544V) leads to a complete restoration of the ribosome functionality. It is possible that the changes in translocation induced by EF-G mutants compensate for the activity loss caused by Ami.Russian Foundation for Basic ResearchRevisión por pare

RNase T1 mimicking artificial ribonuclease

Recently, artificial ribonucleases (aRNases)—conjugates of oligodeoxyribonucleotides and peptide (LR)4-G-amide—were designed and assessed in terms of the activity and specificity of RNA cleavage. The conjugates were shown to cleave RNA at Pyr-A and G–X sequences. Variations of oligonucleotide length and sequence, peptide and linker structure led to the development of conjugates exhibiting G–X cleavage specificity only. The most efficient catalyst is built of nonadeoxyribonucleotide of unique sequence and peptide (LR)4-G-NH2 connected by the linker of three abasic deoxyribonucleotides (conjugate pep-9). Investigation of the cleavage specificity of conjugate pep-9 showed that the compound is the first single-stranded guanine-specific aRNase, which mimics RNase T1. Rate enhancement of RNA cleavage at G–X linkages catalysed by pep-9 is 108 compared to non-catalysed reaction, pep-9 cleaves these linkages only 105-fold less efficiently than RNase T1 (kcat_RNase T1/kcat_pep-9 = 105)