Complete bioconversion of hemicellulosic sugars from agricultural residues into lactic acid by Lactobacillus pentosus

On the basis of previous knowledge, different agroindustrial wastes were submitted to dilute-acid hydrolysis with H2SO4 to obtain hemicellulosic sugars and then employed for lactic acid production by Lactobacillus pentosus. Toxic compounds released from lignin did not affect lactic acid fermentation when hydrolysates from trimming vine shoots, barley bran husks, or corncobs were employed as carbon source, and complete bioconversion of hemicellulosic sugars was achieved. Nevertheless, Eucalyptus globulus hydrolysates had to be submitted to a detoxification process with activated charcoal. Maximum lactic acid concentration (33 g/L) was reached employing barley bran hydrolysates, whereas corncobs, trimming vine shoots, and detoxified E. globulus hydrolysates yielded 26, 24, and 14.5 g/L of lactic acid, respectively. The maximum product yield from pentoses (0.76 g/g) was achieved using hydrolysates from trimming vine shoots, followed by hydrolysates from detoxified E. globulus (0.70 g/g), barley bran (0.57 g/g), and corncob (0.53 g/g). These results confirm that L. pentosus can be employed to ferment hemicellulosic sugars (mainly xylose, glucose, and arabinose) from acid hydrolysates of most agricultural residues without appreciable substrate inhibition.     

Radioresistance studies in Methylobacterium spp.

Methylobacterium extorquen was isolated and was found as one of the most resistant microorganisms in the original bioburden of ophthalmic cotton dressings to be submitted to γ radiation sterilization. Radiation survival curves were simultaneously performed in phosphate buffer and in test-pieces on two isolates, one obtained before irradiation (wild strain) and the other after irradiation at 20 kGy (rad strain), as well as on three type strains of Methylobacterium spp. (M. extorquens^T, M. radiotolerans^T and M. fujisawaense^T). The radiation resistance was compared using D_values. To analyze the effect of non linearity on radioresistance other measures were applied, such as intercept point, fraction of surviving cells at a selected dose and area. The ranking of strains with these approaches showed to be different, pointing out the need of an integrated measure of radioresistance. Therefore, an index of relative survival (IRS) is proposed.     

Structural and stereochemical investigations into bromotyrosine-derived metabolites from southern Australian marine sponges, Pseudoceratina spp.

Chemical investigation of a southern Australian sponge, Pseudoceratina sp., resulted in the isolation of twelve bromotyrosine-derived alkaloids, comprising four new metabolites, aplysamine-7 (1), (−)-purealin B (2), purealin C (3) and purealin D (4); two new spiroisoxazole enantiomers, (−)-purealidin R (5) and (−)-aerophobin-2 (6); five known metabolites (−)-pseudoceratinine A (7), (−)-aeroplysinin-1 (8), aplysamine-2 (9), purpuramine G (10) and purpuramine J (11); and an artifact 12 derived from ethanolysis of 5. Structures for 1-12 were assigned on the basis of detailed spectroscopic analysis. A second southern Australian Pseudoceratina sp. afforded the first recorded account of a racemic bromotyrosine-derived spiroisoxazole, (±)-purealin (13b), together with the known achiral precursor purealidin A (15). A literature review of marine bromotyrosine-derived spiroisoxazoles reaffirmed the published dominance of (+)-spiroisoxazoles, acknowledging several accounts of (−)-spiroisoxazoles, while also revealing a wide range of chiroptical measurements suggestive of variable optical purity. The Pseudoceratina sp. metabolites 1-12, 13b and 15 were assessed for antibiotic properties, with the new metabolites 3 and 13b exhibiting broad spectrum activity against several Gram-positive bacteria.     

Effect of dose rate and comparison of different media used in the recuperation of gamma irradiated listeria monocytogenes

D₁₀ of different strains of Listeria monocytogenes (LM) gamma irradiated with varying dose-rates are were established. Our results seem to indicate that the dose-rate does not exert a significant effect on their D₁₀. D₁₀ obtained with LM irradiated and plated on Oxford agar showed the highest value.     

An experimental investigation into the gasification reactivity and structure of agricultural waste chars

The gasification reactivity as well as physical and chemical structure of chars generated from two kinds of agricultural waste (i.e. corn straw and wheat straw) were studied to better understand the role of lower pyrolysis temperatures and lower heating rates on the gasification characteristics of agricultural waste chars. Char samples were generated in a one-stage quartz fixed-bed reactor. The carbon dioxide (CO₂) gasification reactivity of chars was measured by thermogravimetric (TGA) analysis. Scanning electron microscopy (SEM) analysis, surface area (BET) analysis, Fourier transform infrared spectroscopy (FTIR) analysis and X-ray diffractometry (XRD) analysis were employed to determine the effect of operating conditions on the char structure. Char gasification reactivities decreased with increasing pyrolysis temperatures. The char particles generated under high pyrolysis temperatures had many smaller pores with thinner cell walls, larger surface areas, and some melting. Results indicated that many functional groups’ bands decreased and even disappeared with an increasing pyrolysis temperature. The chars’ microcrystalline became larger at high pyrolysis temperatures. The reactivity of wheat straw char is higher than corn straw char. The difference in the gasification reactivity of agricultural waste chars generated at different pyrolysis temperatures correlated well with the effect of pyrolysis temperatures on the agricultural waste char structure.     

Preparation and characterization of gamma irradiated ZnO/PANI hybrid films

Journal of Radioanalytical and Nuclear Chemistry - In this study, Zinc Oxide/Polyaniline (ZnO/PANI) hybrid was successfully synthesized using the combination of in-situ chemical oxidative...     

The optimization of the conversion of agricultural waste into volatile fatty acids under anaerobic conditions

The selection of a biocatalyst was performed and the first optimal microbial association was obtained. This association was capable of converting products of depolymerization of sawdust, straw, and lignin into volatile fatty acids with an acid-producing activity that was greater by 1.3 times than the initial methane activity. The largest percentages of butyric acid (40%) and ethanol (14%) were obtained from biomass out of straw in concentrations of soluble organic substances from 2.5 to 6.3 g_COD/L. Using biomass from sawdust and lignin at concentrations of organic substances from 4.0 to 8.0 g_COD/L and a duration of the conversion process of up to 18 days we obtained an output of butyric acid that was two times smaller than that on a biomass from straw.     

Detection of irradiated fresh fruits treated by e-beam or gamma rays

Since about 1990, the amount of commercially irradiated food products available worldwide has increased. Commercial irradiation of foods has been allowed in Brazil since 1973 and now more than 20 different food products are approved. Among these products are a number of fresh fruits which may be irradiated for insect disinfestation, to delay ripening and to extend shelf-life. Today, there is a growing interest to apply radiation for the treatment of fruits instead of using fumigation or e.g. vapour-heat treatments, and an increased international trade in irradiated fruits is expected. To ensure free consumer choice, methods to identify irradiated foods are highly desirable. In this work, three detection methods for irradiated fruits have been employed: DNA Comet Assay, the half-embryo test and ESR. Both electron-beam (e-beam) and gamma rays were applied in order to compare the response with these two different kinds of radiation. Fresh fruits such as oranges, lemons, apples, watermelons and tomatoes were irradiated with doses in the range 0, 0.50, 0.75, 1.0, 2.0 and 4.0 kGy. For analysis, the seeds of the fruits were utilized. Both DNA Comet Assay and the half-embryo test enabled an easy identification of the radiation treatment. However, under our conditions, ESR measurements were not satisfactory.     

ESR study of free radicals in UHMW-PE fiber irradiated by gamma rays

ESR spectra of the trapped radicals in an ultra-high molecular weight polyethylene (UHMW-PE) fiber irradiated by gamma rays showed well-resolved hyperfine splitting at room temperature since the c-axis of the crystallites is aligned with the fiber direction and the radicals are trapped in crystallites. The alkyl radical (?CH₂?^?CH?CH₂?) was the major product after irradiation in vacuum and in air at room temperature. Some of the alkyl radicals converted to allyl radicals (?CH₂?^?CH?CH=CH?) and polyenyl radicals (?CH₂?^?CH?(CH=CH)_n?CH₂?) during storage in vacuum. Upon storage in air atmosphere, the alkyl radicals decayed by reaction with oxygen. Of particular interest is the very slow decay rate of the alkyl radical trapped in UHMW-PE fiber, the half-life is 26 days in vacuum, and 13 days in air at room temperature, which is about 1/30 and 1/100 of that reported for high density polyethylene (HDPE), respectively. The extremely long lifetime of the alkyl radical is supposed to be caused by the large size of crystallites in UHMW-PE fiber. The rate of radical decay was accelerated by annealing at elevated temperature.     

Production control of metal alloys by laser spectroscopy of the molten metals. Part I. Preliminary investigations

After a short up-to-date survey of the method elaborated for chemical analysis of molten metals, the reason for the choice of time resolved laser induced spectroscopy (TRELIBS) is given. By means of a Nd:YAG laser and a double monochromator, the time resolved spectrum of the solid and molten aluminium alloys is detected using a photodiode array. According to the data obtained for the analytical performance, analysis in the molten phase can be done with sufficient accuracy and precision compared to the solid phase, without time loss for sample taking and preparation. Within the framework of the preliminary investigations, the fundamental analytical characteristics of the laser induced plasma are investigated (dependence of background (BG) and line/BG ratio on the atmosphere, state of the material, delay and gate time, the occurrence of self absorption and wavelength shift). The use of an argon atmosphere, relative line intensities (if possible, spectral lines of equal ionization state and excitation potentials should be near to each other) and an individual delay/gate time optimum can be recommended.     

Preliminary investigations of the binding media of paintings by differential thermal analysis

Differential thermal analysis has been used to study the binding media of paintings. To assist in the interpretation of the DTA curves known organic materials which are commonly used in paintings such as linseed oil, egg yolk and their mixtures with pigment (e.g. linseed oil/egg yolk/ ZnO) were initially investigated together with paint films containing linseed oil/lead white and some additions of proteinaceous material. The paint films had been prepared in the period 1915–1941. It appears as though DTA or DSC can be used both to characterize the binding media (i.e. to decide whether oil or protein appears as the main component), and to provide an indication of the age of the painting.

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Zusammenfassung Mit Hilfe der DTA werden die Bindemittel der Farbschicht von Gemälden untersucht. Um die Deutung der DTA-Kurven zu erleichtern, wurden zunächst bekannte, häufig in der Malerei benutzte organische Stoffe wie Leinöl, Eidotter und ihre Mischungen mit Pigmenten (Leinöl/Eidotter/ ZnO) sowie in den Jahren 1915–1941 hergestellte Anstrichfilme untersucht, die Leinöl/Bleiweiss mit einigen Zusätzen eiweisshaltiger Stoffe enthalten. Es scheint, dass die DTA oder DSC sowohl zur Charakterisierung der Bindemittel brauchbar ist (das heisst zum Nachweis ob öl oder Protein die Hauptkomponente darstellt) als auch Hinweise zum Alter der Gemälde liefert.

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Thanks are directed to the German Academic Exchange Service (DAAD), the South Australian Institute of Technology Internal Research Grant Scheme, and F.S.E. Scientific for their support; and to the Doerner Institute in Munich for the full use of laboratory facilities for a period of up to 12 months, and also for the pigment determination which was carried out by Frau Junghans.     

Detoxification of phenanthrene by C. elegans evaluated by calorimetry

The filamentous fungus Cunninghamella elegans IM 1785/21Gp has an ability to remove phenanthrene to hydroxylated products with high efficiency. The sensitivity of C. elegans spores to phenanthrene derived metabolic products, 9-phenanthrols, as a model example of hydroxyderivatives produced by this fungus, was determined in this work. Calorimetric measurements showed that 9-phenanthrol disturbed the metabolic activity and spore germination of C. elegans less than phenanthrene did. However, at concentrations exceeding 60–70 mg L⁻¹, phenanthrol strongly affected the intracellular processes of this fungus.     

Relationship between free volume and mechanical properties of polyurethane irradiated by gamma rays

Polyurethane was irradiated at various gamma radiation doses up to 1,000 kGy at room temperature in nitrogen. Positron annihilation lifetime spectroscopy, tensile test and dynamic mechanical analysis were used to find the relationship between free volume and mechanical properties. An increase of the free volume fraction in soft segments (SS) and a decrease of the free volume fraction in hard segments (HS) during gamma radiation was observed and analyzed. The results showed that HS in polyurethane had the excellent resistance to gamma radiation, whereas SS had a tendency to degrade. The reason for the decrease of the strain at break and the ultimate tensile strength was analyzed, which showed the changes in the mechanical properties of polyurethane irradiated by gamma rays were mainly determined by the changes of free volume in SS. If the resistance properties of polyurethanes exposed to radiations need to be improved, SS should be paid more attention to.     

Recycling of fibre-reinforced polymeric waste by pyrolysis: thermo-gravimetric and bench-scale investigations

A variety of composite wastes were pyrolysed in a bench-scale, static-bed reactor at 350–800 °C. The samples under investigation included composites of polyesters, phenolic and epoxy resins, and polypropylene, reinforced with glass and/or carbon fibre. Both the product mass balance and gas composition were dependent on the polymer matrix, pyrolysis temperature and, at the higher temperatures studied, the decomposition of thermally unstable fillers present in several samples, most notably calcium carbonate. The waste samples were also pyrolysed in a thermo-gravimetric analyser and the Arrhenius kinetic parameters of the main decomposition reactions were calculated using a non-isothermal method. The thermograms are discussed in relation to the results of the bench-scale work and related to the decomposition behaviour of individual sample components.     

The identification of irradiated seasoned filefish (Thamnaconus modestus) by different analytical methods

Dried seasoned filefish (Thamnaconus modestus) was irradiated at 0–10 kGy and the identification of irradiation treatment was investigated by analyzing the characteristics of thermoluminescence (TL), hydrocarbon (HC), and 2-alkylacyclobutanone (2-ACB). The TL (TL₁), glow curve of the irradiated samples peaked at approximately 150 °C with high intensity, but that of the non-irradiated samples peaked at about 300 °C with little intensity, thus making it possible to discriminate between irradiated and non-irradiated samples. Moreover, TL ratio (TL₁/TL₂), through normalization steps, enhanced the reliability of the TL₁ results. Six kinds of HCs and three kinds of 2-ACBs quantitatively determined for the samples linearly increased in proportion to irradiation doses. In particular, two HCs like 1-hexadecane and 1,7-hexadecadine, and three ACBs, such as 2-dodecylcyclobutanone, 2-(5′-tetradeceyl)cyclobutanone, and 2-tetradecylcyclobutanone, were identified only in the irradiated samples as radiation-induced markers.     

采用原位聚合法制备固相微萃取涂层的初步研究

采用一步原位合成法制备了新型有机多孔聚合物涂层，并对其进行了初步评价研究．观察了单体浓度对其所制备涂层的萃取容量的影响，并优化了合成浓度．同时，在分析水体基质中的苯系物时，证明了该涂层对苯系物等含苯环物质具有选择性吸附的能力．     

Effects of gamma irradiation on the shoot length of Cicer seeds

The effects of radiation on the shoot and root lengths of germinated seedling of irradiated seeds of Cicer species, i.e. three kabuli types and four desi types of cultivated chickpea (Cicer arietinum Ladiz.) and 2 annual wild types (C. reticulatum Ladiz. and C. bijugum K.H. Rech.) were investigated. The seeds were irradiated with a ⁶⁰Co gamma source using 0, 200, 300 and 400 Gy doses at 1.66 kGy h⁻¹. At 200 Gy minor effects could be observed, but at 400 Gy an obvious depression of shoot length was observed. The kabuli types were more affected than the desi ones. The critical dose that prevented the shoot and root elongation varied among species and also ranged from genotypes to genotype within species.     

Investigation characteristics of polyvinyl alcohol film dyed methylene blue and irradiated by gamma source

Journal of Radioanalytical and Nuclear Chemistry - The polyvinyl alcohol (PVA) films dyed methylene blue containing different masses of boric acid and PVA powder were investigated. The dyed PVA...