Anaerobic digestion of alcohol sulfate (anionic surfactant) rich wastewater--batch experiments. Part I: influence of the surfactant concentration

Textile wet processing wastewater (e.g., from cotton desizing) contains high concentrations of surfactants as well as readily biodegradable compounds like starch and other carbohydrates. Decyl sulfate (DS, surfactant) and soluble starch were used as model pollutants for biodegradation batch experiments. Very high loadings of the biomass were applied (DS: 21.7-217 g/kg cell dry weight (CDW); starch: 910 g/kg cell dry weight) to study inhibitory effects of the surfactant on the degradation cascade of the biopolymer. The starch hydrolysis was inhibited above sludge loadings of 65 g DS/kg CDW. Acidogenesis was the degradation step with the highest resistance towards inhibitory effects of the surfactant, whereas methanogenesis proved to be the most sensitive. The effects of the surfactant were described by the change of the methane evolution, which was reduced by 50% in 87 days with an addition of 58 g DS/kg CDW. The surfactant caused a high temporary accumulation of intermediates like volatile fatty acids. At the highest loading (217 g DS/kg CDW) the conversion of the substrate to methane was only minor.     

Secondary structural changes of metmyoglobin and apomyoglobin in anionic and cationic surfactant solutions: Effect of the hydrophobic chain length of the surfactants on the structural changes

Secondary structural changes of metmyoglobin and apomyoglobin were examined in solutions of sodium alkylsulfates with hydrocarbon numbers of 8 and 12, and alkyltrimethylammonium bromides with hydrocarbon numbers of 10, 12, 14, and 16. The relative proportion ofa-helical structure was estimated by the curve-fitting method of circular dichroic spectrum. The helical proportions of metmyoglobin and apomyoglobin were 82 and 63%, respectively. The shorter the hydrocarbon chain the surfactant had, the higher the concentration necessary to disrupt the secondary structures of these proteins. However, the helical proportion had a tendency to decrease down to lower values in solutions of the cationic surfactants with short hydrophobic groups. On the other hand, thea-helical structure of apomyoglobin was disrupted in lower concentrations of each cationic surfactant than that of metmyoglobin, although the disruptions of the same structures in both the proteins occurred in the same concentration range of each anionic surfactant. It appeared likely that the removal of the heme group unstabilized the myoglobin conformation only in the cationic surfactant solutions.     

Medium chain length polyhydroxyalkanoate (mcl-PHA) production from volatile fatty acids derived from the anaerobic digestion of grass

A two step biological process for the conversion of grass biomass to the biodegradable polymer medium chain length polyhydroxyalkanoate (mcl-PHA) was achieved through the use of anaerobic and aerobic microbial processes. Anaerobic digestion (mixed culture) of ensiled grass was achieved with a recirculated leach bed bioreactor resulting in the production of a leachate, containing 15.3 g/l of volatile fatty acids (VFAs) ranging from acetic to valeric acid with butyric acid predominating (12.8 g/l). The VFA mixture was concentrated to 732.5 g/l with a 93.3 % yield of butyric acid (643.9 g/l). Three individual Pseudomonas putida strains, KT2440, CA-3 and GO16 (single pure cultures), differed in their ability to grow and accumulate PHA from VFAs. P. putida CA-3 achieved the highest biomass and PHA on average with individual fatty acids, exhibited the greatest tolerance to higher concentrations of butyric acid (up to 40 mM) compared to the other strains and exhibited a maximum growth rate (μ_MAX?=?0.45 h^?1). Based on these observations P. putida CA-3 was chosen as the test strain with the concentrated VFA mixture derived from the AD leachate. P. putida CA-3 achieved 1.56 g of biomass/l and accumulated 39 % of the cell dry weight as PHA (nitrogen limitation) in shake flasks. The PHA was composed predominantly of 3-hydroxydecanoic acid (>65 mol%).     

Effect of alcohol chain length on tubule formation in 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine.

Aqueous dispersions of 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine, on cooling below the chain melting temperature, form hollow cylindrical structures known as 'tubules'. We have studied the formation of tubules in methanol/water, ethanol/water and n-propanol/water. For each alcohol, there is a defined window of alcohol/water ratios in which the lipid precipitates with the tubule morphology. As the chain length of alcohol is increased, the window shifts towards lower alcohol fraction. Light scattering studies show that at very low lipid concentrations the tubules self-assemble directly from the isotropic phase where as for lipid concentrations greater than 4 mg/ml an intermediate L alpha phase is observed. These results indicate that the mechanism of tubule formation may be dependent on lipid concentration.     

Alcohol induction of interdigitation in distearoylphosphatidylcholine: fluorescence studies of alcohol chain length requirements.

Although it is now well established that the fully interdigitated phase is induced in saturated like-chain phosphatidylcholines (PCs) by a variety of amphipathic molecules including alcohols, no systematic study of the properties of the inducing molecules has been reported. To elucidate the stereochemical features that lead to the alcohol induction of interdigitation in PCs, we have investigated the induction of interdigitation in distearoylphosphatidylcholine (DSPC) by a series of alcohols. Our previously established DPH (1,6-diphenyl-1,3,5-hexatriene) fluorescence intensity method has been expanded (P. Nambi, E. S. Rowe, and T. M. McIntosh (1988), Biochemistry 27:9175-9182) and used to determine which of the alcohols induce interdigitation and to determine the threshold concentrations for each. We have found that each of the n-alcohols up to heptanol and several branched alcohols are capable of inducing interdigitation in DSPC; octanol and nonanol do not appear to induce interdigitation by these criteria. The threshold concentrations for interdigitation for each of these alcohols up to heptanol were found to be correlated with the membrane: buffer partition coefficients. The mole fraction of bound alcohol at the threshold concentration was similar for each of the alcohols up to pentanol. These results are discussed in terms of a general mechanism of the formation of the interdigitated phase.     

The effect of 5-(n-alk(en)yl)resorcinols on membranes. II. Dependence of the aliphatic chain length and unsaturation

The effect of chain length and unsaturation on the haemolytic properties of cereal resorcinolic lipids, (5-n-alk(en)ylresorcinols), was studied using isolated saturated, monoenoic and dienoic homologues. The haemolytic activities of the homologues studied were proportional to the degree of the side chain unsaturation and inversely proportional to the chain length. At temperatures close to physiological of animal organisms the most active were mono- and di-enoic homologues of 5-n-heptadecyl and 5-n-nonadecyl resorcinols. The results might point to the importance of short-chain cereal resorcinolic lipids in animal and human nutrition.     

Effect of chain length and concentration of anionic surfactants on the conformational transitions of poly(L-ornithine) and poly(L-lysine) in aqueous solution

The conformation of poly(L-ornithine) (PLO) and poly(L-lysine) (PLL) in solutions of sodium alkyl sulfates, CH₃(CH₂)_nSO₄Na with n = 7, 9, 11, 13 and 15 was studied by circular dichroism. PLO adopts a helical conformation in all 5 homologs and PLL a β-form in only 4 of the homologs. With octyl sulfate PLL has a helical conformation instead. These conformations were observed in solution of surfactants both below and above the critical micelle concentration.     

Anaerobic digestion model No. 1-based distributed parameter model of an anaerobic reactor: II. Model validation

In this study, an ADM1-based distributed parameter model was validated using experimental results obtained in a laboratory-scale 10 L UASB reactor. Sensitivity analysis of the model parameters was used to select four parameters for estimation by a numerical procedure while other parameters were accepted from ADM1 benchmark simulations. The parameter estimation procedure used measurements of liquid phase components obtained at different sampling points in the reactor and under different operating conditions. Model verification used real time fluorescence-based measurements of chemical oxygen demand and volatile fatty acids at four sampling locations in the reactor. Overall, the distributed parameter model was able to describe the distribution of liquid phase components in the reactor and adequately simulated the effect of external recirculation on degradation efficiency. The model can be used in the design, analysis and optimization of UASB reactors.     

Classification of the flea families (Siphonaptera): II. Family hystrichopsyllidae (Part 4)

Distribution of the ancestral, homoiologous, and convergent character states over the tagmata and morpho-functional complexes of the flea body in nine subfamilies of the Hystrichopsyllidae is analyzed. The analysis is based upon the states of 111 characters of 73 structures of 3 tagmata in the adult flea body. The homoiologous states (those arising in parallel in close flea infraorders) comprise 35%, the ancestral (the least specialized) ones, 16%, and the convergent ones, 13% of the total number of character states of all the 10 types. The greatest numbers of the ancestral character states in the Hystrichopsyllidae are found in the mesothorax (22.8%) and aedeagus (21.1%); the metathorax reveals 19.3%, and the head, 17.5% of the ancestral character states. The greatest number of homoiologous character states, 34.1% of the total number, is observed in the mesothoracal segment. Smaller fractions of the homoiologous character states are found in the head (24.6%) and metathorax (17.5%). Those character states which arise in the phylogenetically remote infraorders are considered convergent. The greatest number of convergent character states in the Hystrichopsyllidae (55.1%) is observed in the structure of the aedeagus.     

Electrostatic and hydrophobic forces tether the proximal region of the angiotensin II receptor (AT1A) carboxyl terminus to anionic lipids

The carboxyl terminus of the type-1 angiotensin II receptor (AT(1A)) is a focal point for receptor activation and deactivation. Synthetic peptides corresponding to the membrane-proximal, first 20 amino acids of the carboxyl terminus adopt an alpha-helical conformation in organic solvents, suggesting that the secondary structure of this region may be sensitive to hydrophobic environments. Using surface plasmon resonance, immobilized lipid chromatography, and circular dichroism, we examined whether this positively charged, amphipathic alpha-helical region of the AT(1A) receptor can interact with lipid components in the cell membrane and thereby modulate local receptor attachment and structure. A synthetic peptide corresponding to the proximal region of the AT(1A) receptor carboxyl terminus (Leu(305) to Lys(325)) was shown by surface plasmon resonance to bind with high affinity to the negatively charged lipid, dimyristoyl L-alpha-phosphatidyl-DL-glycerol (DMPG), but poorly to the zwitterionic lipid, dimyristoyl L-alpha-phosphatidylcholine (DMPC). In contrast, a peptide analogue possessing substitutions at four lysine residues (corresponding to Lys(307,308,310,311)) displayed poor association with either lipid, indicating a crucial anionic component to the interaction. Circular dichroism analysis revealed that both the wild-type and substituted peptides possessed alpha-helical propensity in methanol and trifluoroethanol, while the wild-type peptide also adopted partially inserted helical structure in DMPG and DMPC liposomes. In contrast, the substituted peptide exhibited spectra that suggested the presence of beta-sheet and alpha-helical structure in both liposomes. Immobilized lipid chromatography was used to characterize the hydrophobic component of the membrane interaction, and the results demonstrated that hydrophobic and electrostatic interactions mediated the binding of the wild-type peptide but that the substituted peptide bound to the model membranes mainly via hydrophobic forces. We propose that, in intact AT(1A) receptors, the proximal carboxyl terminus associates with the cytoplasmic face of the cell membrane via a high-affinity, anionic phospholipid-specific tethering that serves to increase the amphipathic helicity of this region. Such associations may be important for receptor function and common for G protein-coupled receptors.     

Classification of the flea families (Siphonaptera): II. Family Hystrichopsyllidae (Part 3)

Morphological characters and their diversity in the Afrotropical subfamilies Dinopsyllinae and Listropsyllinae, and the Holarctic subfamily Anomiopsyllinae are evaluated. Three centers had the major significance in the formation of the family Hystrichopsyllidae: the South American (extra-Caribbean), Afro-European, and North American and Asian ones. One more center may have been located in Australia but its fauna has become largely extinct or remains unknown. The origin of a number of tribes of the subfamilies Hystrichopsyllinae and Doratopsyllinae is associated with the South American center; the origin of subgenera of the subfamily Ctenophthalminae as well as the subfamilies Listropsyllinae and Dinopsyllinae, with the Afro-European center; and the origin of the subfamilies Neopsyllinae, Rhadinopsyllinae, Anomiopsyllinae, Stenoponiinae, and Liuopsyllinae, with the North American and Asian center. Distribution of the subfamilies Doratopsyllinae and Hystrichopsyllinae sheds light on the initial stages of formation of the family Hystrichopsyllidae.     

Physiological changes in the running greyhound (Canis domesticus): influence of race length.

1. Racing greyhounds were allowed to run 402 m, 503 m, and 704 m to determine the influence of increased race length on physiological changes during and after exercise. 2. Plasma and whole blood variables that changed significantly with increased race length were [K+], [total protein], [lactate], hematocrit, and arterial pH. 3. Those variables that changed with increased race distance showed no indication of reaching a plateau; thus, the maximum changes that these variables might undergo with longer exercise duration remains unknown.     

On-field study of anaerobic digestion full-scale plants (Part II): new approaches in monitoring and evaluating process efficiency

Biogas plants need easy and practical tools for monitoring and evaluating their biological process efficiency. As soon as, in many cases, biomass supply present considerable costs, full-scale anaerobic digestion (AD) processes must approach, as much as possible, the potential biogas yield of the organic mixture fed to the biodigesters. In this paper, a new indicator is proposed (the bio-methane yield, BMY), for measuring the efficiency in full-scale AD processes, based on a balance between the biochemical methane potential (BMP) of the input biomass and the residual BMP of the output materials (digestate). For this purpose, a one-year survey was performed on three different full-scale biogas plants, in the Italian agro-industrial context, and the bio-chemical processes were fully described in order to calculate their efficiencies (BMY = 87-93%) and to validate the new indicator proposed, as useful and easily applicable tool for full-scale AD plants operators.     

Crystallization behavior and hydrophobic properties of biodegradable ethyl cellulose-g-poly(3-hydroxybutyrate-co-3-hydroxyvalerate): The influence of the side-chain length and grafting density

The copolymerization of grafting poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) onto ethyl cellulose (EC) was carried out through the homogeneous acylation reaction between EC as a backbone and telechelic OH-terminated PHBV oligomer as side chains in 1,2-dichloroethane by using 1,6-hexamethylene diisocyanate (HDI) as a coupling agent and dibutyltin dilaurate as catalyst. The resulting copolymers were studied by using NMR, FT-IR, WAXD, DSC, and contact angle measurements. It is found that with the increasing of the HDI/PHBV fraction, a transition exhibition occurred on crystallization behavior and hydrophobic properties, which could be modulated through controlling the lengths and grafting densities of PHBV side chains. Compared with those of neat PHBV, the degree of crystallinity for EC-g-PHBV_1.8 decreased from 58.1% to 39.1%, the maximum decomposition temperature increased from 259.6 to 266.3 °C, and the contact angle increased from 60.1° to 95.7°.     

Dye standards, Part II. 7: Magenta II (no CI number)

The names and affiliations of the SRMTS members are cited in Part I: terminology and general principles,Histochem. J. (1992)24, 217–19.     

The influence of the polar head and the hydrophobic chain on the skin penetration enhancement effect of poly(ethylene glycol) derivatives

The effect of a homologue series of nonionic surfactants, namely poly(ethylene glycol) (PEG) fatty acid esters, differing in oxyethylene (PEG 8, PEG 12, and PEG 40) and fatty acid (stearate, mono and di-laurate, and mono and di-oleate) chain lengths, on in vitro skin permeability of ketoprofen (KTP) vehicled in plasters was investigated. The drug diffusion through hairless mouse skin as well as the effect of the surfactant type and strength was studied by Franz diffusion cells and ATR-FTIR spectroscopy. The use of PEG stearate series revealed that the surfactant with the largest polar head, namely PEG 40, was ineffective in enhancing the skin permeation of KTP, independently of the plaster concentrations. The effect of the hydrophobic chain was investigated only by using the shortest oxyethylene chains. The experimental results revealed that the oxyethylene chain length of surfactants appeared to be more influent than the alkyl chain. The prediction of the absorption enhancing capability of these PEG derivatives appeared related to the vehicle other than the proper combination of the number of ethylene oxide groups and alkyl groups.