A systematic investigation on the influence of the chemical treatment of natural fibers on the properties of their polymer matrix composites

This paper reports a systematic study of the effects on composite properties of different chemical treatments on natural fibers. Both short flax fibers and flax cellulose pulp in a polypropylene matrix have been investigated. The influence of treatments on fiber properties was investigated by means of spectroscopic, thermal and mechanical tests. Moreover, the effects of fiber treatment on the crystallinity of the matrix were analyzed using differential scanning calorimetry and optical microscopy. The mechanical properties of the composites obtained were studied using tensile and bending tests. It is shown that most of the main properties of the composites can be improved by adequately treating the fibers. The results of this study provide a database mainly devoted to material selection for the automotive industry. This research has been performed as a part of the ECOFINA project in the framework of the 5th European Research Program of the European Community. Polym. Compos. 25:470–479, 2004. © 2004 Society of Plastics Engineers.     

Experimental evaluation of the hydrothermal stability of a silicone/zeolite composite foam for solar adsorption heating and cooling application

This article evaluates the hydrothermal and mechanical stability of an adsorbent composite foam based on zeolite silicone for application in adsorption heat pump. The adsorption properties of the fresh composite adsorbents and their morphological features were already presented in previous papers. In the present work, hydrothermal aging of composite foams, at varying SAPO-34 zeolite contents and under real operating conditions, was carried out in order to verify the stability of the synthetized material. This improvement of knowledge is a key point for the industrial application. This evaluation was successfully performed by means of adsorption measurements and compression test on aged samples, up to 1500 aging cycles. The adsorption properties of composite foams are effective and stable up to the maximum number of cycles of the aging process. Instead, from the mechanical point of view, composite foams with high content of zeolite, aged at long cycles, evidenced a slight stiffening that stimulates mechanical brittle behavior. The composite foam with 67% zeolite filler represents a threshold value beyond which the action of the hydrothermal aging implies a significant loss of flexibility and mechanical integrity, which limits its applicability under typical conditions. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48311.     

Cu(II) Binding Increases the Soluble Toxicity of Amyloidogenic Light Chains

Light chain amyloidosis (AL) is caused by the aberrant overproduction of immunoglobulin light chains (LCs). The resulting abnormally high LC concentrations in blood lead to deposit formation in the heart and other target organs. Organ damage is caused not only by the accumulation of bulky amyloid deposits, but extensive clinical data indicate that circulating soluble LCs also exert cardiotoxic effects. The nematode C. elegans has been validated to recapitulate LC soluble toxicity in vivo, and in such a model a role for copper ions in increasing LC soluble toxicity has been reported. Here, we applied microscale thermophoresis, isothermal calorimetry and thermal melting to demonstrate the specific binding of Cu²⁺ to the variable domain of amyloidogenic H7 with a sub-micromolar affinity. Histidine residues present in the LC sequence are not involved in the binding, and yet their mutation to Ala reduces the soluble toxicity of H7. Copper ions bind to and destabilize the variable domains and induce a limited stabilization in this domain. In summary, the data reported here, elucidate the biochemical bases of the Cu²⁺-induced toxicity; moreover, they also show that copper binding is just one of the several biochemical traits contributing to LC soluble in vivo toxicity.     

Effect of mashing procedures on brewing

The effect of the double decoction mashing method (method A) and the single decoction plus infusion mashing method (method B) on brewing were compared. The trials were carried out with the same raw material (malt and a minor amount of corn as adjunct) on an industrial-scale plant. The effects of mashing methods A and B were evaluated in wort and beer samples obtained with the high gravity system. The analytical parameters of the worts and beers produced and the economic aspects of production (yield, beer quality, time and energy) were discussed. The results showed no considerable differences in beer quality, while a significant difference was observed in the composition of fermentable sugars of worts. Method B gave a wort with a higher content of fermentable sugars which were converted to alcohol during fermentation; therefore, it allowed to obtain a higher beer volumetric yield of the same quality while saving time and energy.     

Reduction of hexavalent chromium by H2O2 in acidic solutions

The rates of the reduction of Cr(VI) with H2O2 were measured in NaCl solutions as a function of pH (1.5-4.8), temperature (5-40 degrees C), and ionic strength (I = 0.01-2 M) in the presence of an excess of reductant. The rate of Cr(VI) reduction is described by the general expression -d[Cr(VI)]/dt = k2[Cr(VI)](m)[H2O2](n)[H+](z), where m = 1 and n and z are two interdependent variables. The value of n is a function of pH between 2 and 4 (n = (3 x 10(a))/(1 + 10(a)), where a = -0.25 - 0.58pH + 0.26pH2) leveling off at pH < 2 (where n approximately = 1) and pH > 4 (where n approximately = 3). The rates of Cr(VI) reduction are acid-catalyzed, and the kinetic order z varies from about 1.8-0.5 with increasing H2O2 concentration, according to the equation z = 1.85 - 350.1H2O2 (M) which is valid for [H2O2] < 0.004 M. The values of k2 (M(-(n+z)) min(-1)) are given by k2 = k/[H+](z) = k1/[H2O2](n)[H+](z), where k is the overall rate constant (M(-n) min(-1)) and k, is the pseudo-first-order rate constant (min(-1)). The values of k in the pH range 2-4 have been fitted to the equation log k = 2.14pH - 2.81 with sigma = +/- 0.18. The values of k2 are dependent on pH as well. Most of the results with H2O2 < 3 mM are described by log k2 = 2.87pH - 0.55 with sigma = +/- 0.54. Experimental results suggest that the reduction of Cr(VI) to Cr(III) is controlled by the formation of Cr(V) intermediates. Values of k2 and k calculated from the above equations can be used to evaluate the rates of the reaction in acidic solutions under a wide range of experimental conditions, because the rates are independent of ionic strength, temperature, major ions, and micromolar levels of trace metals (Cu2+, Ni2+, Pb2+). The application of this rate law to environmental conditions suggests that this reaction may have a role in acidic solutions (aerosols and fog droplets) in the presence of high micromolar concentrations of H2O2.     

Odour gradients and patterns in volatile emission of different plant parts and developing fruits of grapefruit (Citrus paradisi L.)

The volatiles spontaneously emitted in vivo by different plant parts of grapefruit (Citrus paradisi Macf., Rutaceae) were collected by solid phase micro-extraction (SPME) during the whole vegetative cycle of the plant and characterised by GC–MS to verify their involvement in entomophilous pollination, a controversial topic in the biology of this species. Furthermore, the essential oils obtained by expression of the pericarp from unripe and ripe fruits were studied. Altogether 127 compounds were identified, accounting from 82.1% to 99.9% of the whole volatiles. The main constituents detected were mono- and sesquiterpenes, with limonene (0.5–95.2%), linalool (0.2–52.5%), sabinene (0.5–42.5%), myrcene (0.2–15.4%), and β-caryophyllene (0.3–41.0%) as the most represented ones.     

Behavior of enteroaggregative Escherichia coli in bottled spring and mineral water

The ability of enteroaggregative Escherichia coli (EAEC) to survive in bottled mineral and spring water at common storage temperatures was investigated. Filtered mineral and spring waters were inoculated with EAEC (ca. 10(4) CFU/ml) and stored at 4, 10, and 23 degrees C. Water samples were analyzed every 3 days for viable EAEC by plating on tryptic soy agar plates over 60 days of storage. EAEC survived for the duration of the study in both mineral and spring waters. EAEC survival levels were significantly higher (P < 0.01) at 23 and 10 degrees C than at 4 degrees C. Furthermore, EAEC survival levels were significantly higher (P < 0.01) in mineral water than in spring water at 4 and 10 degrees C. The results of this study indicate that EAEC can survive in bottled mineral and spring waters for long periods of storage at 4, 10, and 23 degrees C. The ability of EAEC to survive in bottled water indicates that the source water for bottling industries must be kept free of contamination. Furthermore, the refrigeration of bottled water is recommended to minimize the growth of EAEC in water.     

Postharvest ethylene treatment affects berry dehydration,polyphenol and anthocyanin content by increasing the activity of cell wall enzymes in Aleatico wine grape

Ethylene is known to induce cell wall degradation by acting on cell wall enzymes. Thus, the objective of this experimental study was to evaluate the effect of ethylene on weight loss in Aleatico wine grape during dehydration and whether this effect was due to cell wall enzyme activation. Moreover, the effect on polyphenol, anthocyanin content, and volatile compounds was studied. Aleatico red grapes (Vitis vinifera L, cv Aleatico) were treated with 1,000 μL/L of ethylene in air for 48 h at 20 °C and high relative humidity (RH). Control grapes were untreated. After 48 h, grape clusters were placed at 45% RH, 20 °C, and 1 m/sec air flow (dehydration treatment) to dehydrate until reaching 40% of weight loss (wl). Pectin methylesterase (PME), polygalacturonase (PG), α galactosidase, and β glucosidase were analyzed during dehydration treatment. Weight loss in ethylene-treated berries was about 6% higher than in control grapes, and PME, PG, galactosidase, and glucosidase activities had increased. During dehydration, the concentration of polyphenols and anthocyanins in ethylene-treated grape was higher than in untreated grape. Geraniol and citronellol peak areas rose slightly in ethylene-treated grapes following the pattern of β glucosidase, but the total peak area of terpene alcohols decreased. Ethylene increased the concentration of anthocyanins and polyphenols during dehydration.     

Enriched methane production using solar energy: an assessment of plant performance

A novel hybrid plant for the production of a mixture of methane and hydrogen (17 vol%) from a steam-reforming reactor whose heat duty is supplied by a concentrating solar power (CSP) plant by means of a molten salt stream is here presented.