Biodegradation of Polyhydroxyalkanoate Films in Natural Environments

Summary: Biodegradation of film specimens from polyhydroxyalkanoates (PHAs) of two types – poly-3-hydroxybutyrate (PHB) and poly-3-hydroxybutyrate-co-3-hydroxyvalerate (PHBV) – was analysed in different environments: tropical sea waters of the South China Sea (Nha Trang, Vietnam) and soils in the environs of Hanoi (Vietnam), Nha Trang (Vietnam) and Krasnoyarsk (Siberia, Russia). In seawater, the mass loss of the specimens of both types was almost equal. However, in tropical soils, PHB degraded quicker than PHBV. In the Siberian soil, the degradation rate of the PHBV was generally higher than that of PHBV. Analysis of molecular mass of PHA specimens showed its decreasing during biodegradation. In the tropical sea conditions, PHA degrading microorganisms were represented by bacteria of Enterobacter, Bacillus and Gracilibacillus genera. Among PHA degrading bacteria, Burkholderia, Alcaligenes, Bacillus, Mycobacterium and Streptomyces genera were identified in Vietnamese soils, and Variovorax, Stenotrophomonas, Acinetobacter, Pseudomonas, Bacillus and Xanthomonas genera in Siberian soils. Micromycetes of Gongronella, Paecilomyces, Penicillium and Trichoderma genera exhibited PHA degrading activity in Vietnamese soils, and Paecilomyces, Penicillium, Acremonium, Verticillium and Zygosporium genera – in Siberian soils.     

Synthesis, π‐Face‐Selective Aggregation,and π‐Face Chiral Recognition of Configurationally Stable C3‐Symmetric Propeller‐Chiral Molecules with a π‐Core

The C₃‐symmetric propeller‐chiral compounds (P,P,P)‐ 1 and (M,M,M)‐ 1 with planar π‐cores perpendicular to the C₃‐axis were synthesized in optically pure states. (P,P,P)‐ 1 possesses two distinguishable propeller‐chiral π‐faces with rims of different heights named the (P/L)‐face and (P/H)‐face. Each face is configurationally stable because of the rigid structure of the helicenes contained in the π‐core. (P,P,P)‐ 1 formed dimeric aggregates in organic solutions as indicated by the results of ¹H NMR, CD, and UV/Vis spectroscopy and vapor pressure osmometry analyses. The (P/L)/(P/L) interactions were observed in the solid state by single‐crystal X‐ray analysis, and they were also predominant over the (P/H)/(P/H) and (P/L)/(P/H) interactions in solution, as indicated by the results of ¹H and 2D NMR spectroscopy analyses. The dimerization constant was obtained for a racemic mixture, which showed that the heterochiral (P,P,P)‐ 1 /(M,M,M)‐ 1 interactions were much weaker than the homochiral (P,P,P)‐ 1 /(P,P,P)‐ 1 interactions. The results indicated that the propeller‐chiral (P/L)‐face interacts with the (P/L)‐face more strongly than with the (P/H)‐face, (M/L)‐face, and (M/H)‐face. The study showed the π‐face‐selective aggregation and π‐face chiral recognition of the configurationally stable propeller‐chiral molecules.     

Fluorescence properties of selected benzo[c]phenantridine alkaloids and studies of their interaction with CT DNA

The spectral, especially fluorescence properties, of seven selected quaternary benzo[c]phenantridine alkaloids (sanguinarine, chelerythrine, chelirubine, sanguirubine, chelilutine, sanguilutine, and macarpine) were studied in presence and in absence of double-stranded DNA. This study has proved dramatic differences in fluorescence emission of all studied alkaloids in presence of calf thymus DNA in comparison to fluorescence of free alkaloids. The most remarkable are changes in emission spectra of macarpine, chelirubine, and sanguirubine. Association constants (logK) for interaction of all studied alkaloids with CT DNA were calculated.     

Beiträge zur Chemie der Pyrrolpigmente, 77. Mitt. Synthese und Struktur vonb-Nor-bilatrienen-abc undb-Nor-biladienen-ac bzw. Bi-9,9′-dipyrrinonylidenen und Bi-9,9′-dipyrrinonylenen

B-Nor-biladienes-ac are prepared by oxidative coupling of dipyrrinones in nearly quantitative yields. Further oxidation of these derivatives yieldsb-nor-bilatrienes-abc. Constitutions, tautomerism, configurations at exocyclic double bonds, and conformations at exocyclic chromophore single bonds are determined for the crystalline state and their states of solution using X-ray structural analysis and spectroscopic methods, respectively.B-nor-biladienes-ac are found to be of (4Z,15Z)5sp,9sc,14sp geometry,b-nor-bilatrienes-abc are planar systems of (4Z,9E,15Z) configuration in the crystal, whereas in solutions there are indications of a more twisted conformation at their exocyclic chromophore single bonds.

Herr Dipl.-Ing.Heinz Flödl hat uns am 11. April 1988 für immer verlassen — wir trauern um ihn.     

Protease Production by Different Thermophilic Fungi

A comparative study was carried out to evaluate protease production in solid-state fermentation (SSF) and submerged fermentation (SmF) by nine different thermophilic fungi – Thermoascus aurantiacus Miehe, Thermomyces lanuginosus, T. lanuginosus TO.03, Aspergillus flavus 1.2, Aspergillus sp. 13.33, Aspergillus sp. 13.34, Aspergillus sp. 13.35, Rhizomucor pusillus 13.36 and Rhizomucor sp. 13.37 – using substrates containing proteins to induce enzyme secretion. Soybean extract (soybean milk), soybean flour, milk powder, rice, and wheat bran were tested. The most satisfactory results were obtained when using wheat bran in SSF. The fungi that stood out in SSF were T. lanuginosus, T. lanuginosus TO.03, Aspergillus sp. 13.34, Aspergillus sp. 13.35, and Rhizomucor sp. 13.37, and those in SmF were T. aurantiacus, T. lanuginosus TO.03, and 13.37. In both fermentation systems, A. flavus 1.2 and R. pusillus 13.36 presented the lowest levels of proteolytic activity.     

Light-induced cis/trans isomerization of cis-[Pd(L-S,O)2] and cis-[Pt(L-S,O)2] complexes of chelating N,N-dialkyl-N′-acylthioureas: key to the formation and isolation of trans isomers

Irradiation cis-[M(Lⁿ-S,O)₂] complexes (M = Pt^II, Pd^II) derived from N,N-dialkyl-N′-benzoylthioureas (HLⁿ) with various sources of intense visible polychromatic or monochromatic light with λ < 500 nm leads to light-induced cis?→?trans isomerization in organic solvents. In all cases, white light derived from several sources or monochromatic blue-violet laser 405 nm light, efficiently results in substantial amounts of the trans isomer appearing in solution, as shown by ¹H NMR and/or reversed-phase HPLC separation in dilute solutions at room temperature. The extent and relative rates of cis/trans isomerization induced by in situ laser light (λ = 405 nm) of cis-[Pd(L²-S,O)₂] was directly monitored by ¹H NMR and ¹⁹⁵Pt NMR spectroscopy of selected cis-[Pt(L-S,O)₂] compounds in chloroform-d; both with and without light irradiation allows the δ(¹⁹⁵Pt) chemical shifts cis/trans isomer pairs to be recorded. The cis/trans isomers appear to be in a photo-thermal equilibrium between the thermodynamically favored cis isomer and its trans counterpart. In the dark, the trans isomer reverts back to the cis complex in what is probably a thermal process. The light-induced cis/trans process is the key to preparing and isolating the rare trans complexes which cannot be prepared by conventional synthesis as confirmed by the first example of trans-[Pd(L-S,O)₂] characterized by single-crystal X-ray diffraction, deliberately prepared after photo-induced isomerization in acetonitrile solution.     

New algorithms for the computation of column dynamics of multicomponent liquid phase adsorption

New and efficient numerical algorithms were developed for simulating column dynamics of multicomponent liquid phase adsorption. Simple and realistic models are used for the simulation. Langmuir form of isotherm and linear driving force rate expressions are employed in the model equations. Algorithms were formulated for three different rate control mechanisms, namely, film diffusion control, particle diffusion control and combined film and particle diffusion control. The algorithms derived are explicit with the exception of the requirement of solving a nonlinear equation in one single variable which is the concentration of a reference species. Thus the tedious iterative calculation procedure for solving simultaneous nonlinear equations in a multicomponent fixed bed system is avoided. Example calculations indicated very good numerical accuracy as verified from an independent check by means of an overall mass balance.Nomenclature C Concentration of speciesi in the solution. mol/l - h _i Dimensionless length variable for speciesi - H _i Dimensionless total length parameter for speciesi. - k _li Liquid phase mass transfer coefficient for speciesi, l/sec - K _li Overall liquid phase mass transfer coefficient for speciesi. l/sec - k _si Solid phase mass transfer coefficient for speciesi, l/sec - K _si Overall solid phase mass transfer coefficient for speciesi. l/sec - L Total bed height, m - Q _i Concentration of speciesi in the adsorbent. mol/g solid - t Absolute time, second - V Linear superficial flow rate, m/see - X _i Normalized liquid phase i species concentration - Y _i Normalized liquid phasei species concentration - Z Axial distance of the bed, m     

Mass transfer in the gas phase during top-blowing with plasma jets

Deoxidation of copper melts by hydrogen has been investigated experimentally by top-blowing with argon-hydrogen plasma jets. The course of the deoxidation process has been described mathematically using kinetic laws. The overall divided course of the process can be examined in live partial steps, which are hydrogen transport within the gas phase, hydrogen transport within the melt, oxygen transport within the melt, reaction between hydrogen and oxygen, and H₂O transport within the gas phase. Based on these five elementary processes, an equation for the velocity of deoxidation has been derived. The values of the rate of deoxidation resulting from this equation, in combination with the mass-transter coefficients valid for this process, have been compared to the experimental data. The results of this study verify those of former investigations on vaporization of elements out of copper melts. The mass-transfer coefficients are the same, when the local activity differences are used as the driving force for mass transport in a system. This means that the surface-renewal theory is valid, when mass-transfer coefficients are defined in this way. This is the case, at least, when metallic melts are subjected to top-blowing by plasma jets.Nomenclature a activity (a _i =x _{i i} ) - A _c (m²) effective mass-transfer area - D(m) characteristic length, such as diameter - D _r(m²/s) diffusion coefficient - H(Cu) oxygen dissolved in copper - k _g (mol/m²s) mass-transfer coefficient in the gas phase [k _g (i) mass-transfer coefficient for speciesi] - k _N (mol/m²s) mass-transfer coefficient in the melt phase - K _i = (x _i /y _i )_eq equilibrium coefficient (distribution coefficient) - n _N (mol) mole number of the melt phase - n _G (mol) mole number of the gas phase - n _i (mol/s) mole flow of speciesi - O(Cu) oxygen dissolved in copper - p(N) momentum flow - t(s) time - T (°C or K) temperature;T _G : in the gas,T _s : in the melt,T ^f : at the phase interface - x _i (mol/mol) concentration in the melt - y _i , (mol/mol) concentration in the gas phase - activity coefficient     

Approaches for on-line coupling of extraction and chromatography

This review provides an overview of the approaches available in order to perform on-line coupling of various extraction techniques with liquid and gas chromatography, for the analysis of semivolatile and nonvolatile analytes in liquid and solid samples. The main focus is on the instrumental set-up of these techniques. Selected real applications are described by way of illustration. The extraction methods suitable for on-line coupling covered in this review are: liquid-liquid extraction, solid-phase extraction, membrane-based techniques, pressurised liquid extraction, supercritical fluid extraction, and microwave- and sonication-assisted extractions. The following systems are not covered in this review: on-line coupled solid-phase extraction-liquid chromatography, purge-and-trap-GC, and membrane extraction with a sorbent interface-GC.Abbreviations DMAE Dynamic microwave-assisted extraction - DSAE Dynamic sonication-assisted extraction - FIA Flow injection analysis - FID Flame ionisation detection - GC Gas chromatography - HGAAS Hydride generation atomic absorption spectroscopy - IC Ion chromatography - IPLC Ion pair liquid chromatography - LC Column liquid chromatography - LLE Liquid-liquid extraction - LVI Large-volume injection - MAE Microwave-assisted extraction - MESI Membrane extraction with a sorbent interface - MMLLE Microporous membrane liquid-liquid extraction - MS Mass spectrometry - NP Normal-phase - OTT Open-tubular trapping - OTTTD Open-tubular trapping with thermal desorption - PAH Polycyclic aromatic hydrocarbon - PHWE Pressurised hot water extraction - PCB Polychlorinated biphenyl - PLE Pressurised liquid extraction - PTV Programmed-temperature vaporizer - RP Reversed-phase - RSD Relative standard deviation - SAE Sonication-assisted extraction - SFE Supercritical fluid extraction - SIM Selective ion monitoring - SLM Supported liquid membrane - SPE Solid-phase extraction - SPE-TD Solid-phase extraction-thermal desorption - SVE Solvent vapour exit - TD Thermal desorption     

Diffusion of nonionic azo dyes in nylon-6

Diffusion of 2,4-dinitroaniline and three nonionic azo dyes in Nylon-6 film was studied by analysis of the concentration-distance curves (profiles) of penetrants in the polymer. Actual diffusivities D_(c) of penetrants in polymer, diffusion coefficients as a function of the concentration C_f of penetrant in polymer, were calculated from the profile. It was found that D_(c) is almost constant or decreases gradually with decreasing C_f in the range of high-medium C_f but decreases appreciably with decreasing C_f at low C_f. The change in D_(c) with C_f was explained in terms of the dual-mode sorption-diffusion model. The penetrants diffuse in the polymer as two distinct species, i.e., a dissolved species and an adsorbed species. The former is the penetrant taken up by the polymer by a partition mechanism (dissolved species) and the latter is that taken up by Langmuir sorption (adsorbed species). The actual diffusivity D_P(c) of the dissolved species decreases with decreasing C_f. While the actual diffusivity D_L(c) of the adsorbed species normally increases gradually with decreasing C_f. D_P(c) is usually larger than D_L(c). © 1993 John Wiley & Sons, Inc.