Nutritive value of rapeseed meal: Effects of individual glucosinolates

In the first of a series of studies on the nutritional value of rapeseed meal, rats were fed diets containing six individual glucosinolates over a period of 29 days. The diets included progoitrin and gluconapin both of which are major components of high glucosinolate rapeseed cultivars. No reduction of feed intake or growth rate was noted and thyroid weights were significantly affected only by the progoitrin diet, which also produced small increases in the weights of the livers and kidneys. There was no depression of plasma thyroid hormone levels.     

Delta13C values of grasses as a novel indicator of pollution by fossil-fuel-derived greenhouse gas CO2 in urban areas

A novel fossil fuel pollution indicator based on the 13C/12C isotopic composition of plants has been designed. This bioindicator is a promising tool for future mapping of the sequestration of fossil fuel CO2 into urban vegetation. Theoretically, plants growing in fossil-fuel-CO2-contaminated areas, such as major cities, industrial centers, and highway borders, should assimilate a mixture of global atmospheric CO2 of delta13C value of -8.02 per thousand and of fossil fuel CO2 of average delta13C value of -27.28 per thousand. This isotopic difference should, thus, be recorded in plant carbon. Indeed, this study reveals that grasses growing near a major highway in Paris, France, have strikingly depleted delta13C values, averaging at -35.08 per thousand, versus rural grasses that show an average delta13C value of -30.59 per thousand. A simple mixing model was used to calculate the contributions of fossil-fuel-derived CO2 to the plant tissue. Calculation based on contaminated and noncontaminated isotopic end members shows that urban grasses assimilate up to 29.1% of fossil-fuel-CO2-derived carbon in their tissues. The 13C isotopic composition of grasses thus represents a promising new tool for the study of the impact of fossil fuel CO2 in major cities.     

Isolation and characterization of a psychrotolerant toxin producer, Bacillus weihenstephanensis, in liquid egg products

A psychrotolerant bacteria of the Bacillus cereus group was found responsible for the spoilage of whole liquid egg products. By sequencing a 16S rRNA region and performing a PCR amplification of specific 16S rRNA and cspA signatures, a Bacillus weihenstephanensis was identified. Characterization of this strain shows its ability to grow in defined medium as well as in whole liquid egg at refrigerated temperatures. The strain isolated possesses genes encoding for hemolysin BL, nonhemolytic enterotoxin, and B. cereus enterotoxins and produces enterotoxins with cytotoxic activity in whole liquid egg, even at refrigerated temperatures. The isolate exhibits a clear ability to stick and form biofilms on stainless steel, the most common material used in egg breaking factories, as well as on model hydrophilic (glass) and hydrophobic (polytetrafluoroethylene) materials. These findings show the necessity to monitor for Bacillus contamination in egg products that are often used in the composition of particularly susceptible finished products such as cream, dessert, dairy, meat, and seafood.     

The influence of temperature and interface strength on the microstructure and performance of sol–gel silica–epoxy nanocomposites

A series of silica–epoxy nanocomposites were prepared by hydrolysis of tetraethoxysilane within the organic matrix at different processing temperatures, i.e., 25 and 60 °C. Epoxy matrices reinforced with 2.0–10.0 wt% silica were subsequently crosslinked with an aliphatic diamine hardener to give optically transparent nanocomposite films. Interphase connections between silica networks and organic matrix were established by in situ functionalization of silica with 2.0 wt% γ-aminopropyltriethoxysilane (APTS). The microstructure of silica–epoxy nanocomposites as studied by transmission electron microscopy indicated the formation of very well-matched nanocomposites with homogeneous distribution of silica at relatively higher temperatures and in the presence of APTS. Thermogravimetric and static mechanical analyses confirmed considerable increase in thermal stability, stiffness, and toughness of the modified composite materials as compared to neat epoxy polymer and unmodified silica–epoxy nanocomposites. A slight improvement in the glass transition temperatures was also recorded by differential scanning calorimetry measurements. High temperature of hydrolysis during the in situ sol–gel process not only improved reaction kinetics but also promoted mutual solubility of the two phases, and consequently enhanced the interface strength. In addition, APTS influenced the size and distribution of the inorganic domain and resulted in better performance of the modified silica–epoxy nanocomposites.     

Micro and nano cellular amorphous polymers (PMMA, PS) in supercritical CO2 assisted by nanostructured CO2-philic block copolymers - One step foaming process

Microcellular foaming of commodity amorphous polymers, poly(methyl methacrylate) (PMMA), and poly(styrene) (PS) was studied in supercritical CO₂ via a batch one-step process in the presence of block copolymers able to change their foaming behaviour and therefore the porous structures. Triblock (styrene-co-butadiene-co-methylmethacrylate SBM, methylmethacrylate-co-butylacrylate-co-methylmethacrylate MAM) terpolymers were blended to PS or PMMA by extrusion. They showed advantages compared to classical PS-PMMA polymer blends in terms of cell size control and reduction of cell size. Foaming is carried out on bulk injection molded samples which were saturated under high pressures of CO₂ (300 bars) at different temperatures (25° C to 80 °C) and different depressurization rates (pressure drop rates from 150 bar/min to 12 bar/min). Very distinct cellular structures and densities were controlled by varying either the copolymer type or the foaming conditions (T,P). Cell sizes ranged from 0.2 μm to 200 μm, and densities from 0.30 g/cm³ to 1 g/cm³ in the polymers considered. Particularly, when triblock copolymers were able to self organize (nanostructuring) in a polymer matrix, they became phase separated at a nanometer level, presenting nanostructured polymers matrixes. To conclude the study, a possible nanostructuring mechanism is suggested based on the interplay between rubbery and highly CO₂-philic blocks/rigid and less CO₂-philic blocks. It is demonstrated that block copolymer additives are a good pathway towards micro and ultra microcellular supercritical CO₂ foaming of amorphous polymers.     

Synthesis and Surface-Active Properties of Uronic Amide Derivatives,Surfactants from Renewable Organic Raw Materials

Short chemical syntheses were developed to produce a new set of surfactants from uronic acids derived from widely available raw materials. Three different strategies were used to synthesize uronic amide derivatives, the structures of which were totally characterized by spectrometric methods (IR, MS, ¹H-RMN and ¹³C-RMN). The best one, using an acid chloride as the synthetic intermediate, furnished the expected amides as a mixture of anomers in 46–58% global yield. Surface-active properties (CMC, γ_cmc, Γ_max, A _min) of homologous series of uronic acid N-alkylamides from C8 to C18 were also assessed. In general, these sugar-based surfactants exhibited good surface-activities, and appeared as valuable nonionic surfactants compared to octylphenol 9–10 ethylene oxide condensate, the most well-known nonionic surfactant. Increasing the alkyl chain length influenced the CMC values for both glucuronic and galacturonic N-alkylamide derivatives. The galacturonic N-alkylamides decreased γ_cmc at slower values than their counterpart’s glucuronic N-alkylamides.     

Towards continuous sustainable processes for enzymatic synthesis of biodiesel in hydrophobic ionic liquids/supercritical carbon dioxide biphasic systems

The excellent suitability of immobilized Candida antarctica lipase B (Novozym 435) catalyst to carry out the synthesis of methyl oleate (biodiesel) by methanolysis of triolein in ILs based on imidazolium cations with large alkyl side chain (from C₁₂ to C₁₈) has been demonstrated at 60 and 85 °C. The phase behaviour of IL/triolein/methanol and IL/methyl oleate mixtures were studied at different concentrations and temperatures, the best results (up to 98.6% biodiesel yield after 6 h) being obtained for ILs able to provide monophasic reaction systems, i.e. 1-methyl-3-octadecylimidazolium bis(trifluoromethylsulfonyl)imide). A continuous enzymatic reactor, based on biocatalysts particles coated with hydrophobic ILs, for biodiesel synthesis in supercritical carbon dioxide was studied at 60 °C and 180 bar. The operational stability of the immobilized lipase was improved by its coating with ILs, i.e. 1-methyl-3-octadecylimidazolium hexafluorophosphate, leading to a two-phase systems with respect to the biodiesel product, which showed an excellent catalytic behaviour in continuous operation under supercritical conditions (up to 82% biodiesel yield after 12 cycles of 4 h).     

Coating carbon nanotubes with a polystyrene-based polymer protects against pulmonary toxicity

Background  

carbon nanotubes (CNT) can have adverse effects on health. Therefore, minimizing the risk associated with CNT exposure is of crucial importance. The aim of this work was to evaluate if coating multi-walled CNT (MWCNT) with polymers could modify their toxicity, thus representing a useful strategy to decrease adverse health effects of CNT. We used industrially-produced MWCNT uncoated (NT1) or coated (50/50 wt%) with acid-based (NT2) or polystyrene-based (NT3) polymer, and exposed murine macrophages (RAW 264.7 cell line) or Balb/c mice by intratracheal administration. Biological experiments were performed both in vitro and in vivo, examining time- and dose-dependent effects of CNT, in terms of cytotoxicity, expression of genes and proteins related to oxidative stress, inflammation and tissue remodeling, cell and lung tissue morphology (optical and transmission electron microscopy), and bronchoalveolar lavage fluid content analysis.     

Effect of processing procedures and conditions on structural,morphological, and rheological properties of polyethylene/polyamide/nanoclay blends

The article deals with the effect of processing procedures and conditions on structural, morphological, and rheological properties of ternary blends composed of polyethylene (PE), polyamide (PA)‐12, and organically modified montmorillonite nanoclay with selective affinity. Samples were prepared from PE/PA and PA/PE blends, either by simultaneous mixing or from a polymer/clay masterbatch, using two processing conditions. The results have shown the existence of a weight fraction threshold, above which no significant processing effect was observed. Below this weight fraction threshold, the results tend to underline the significant role of two parameters that depend on processing procedures and/or conditions: the contact time between PE and PA phases and the contact time between clay and PA. Clay structure, blend morphology, and rheological properties were all shown to depend on these two parameters, and also on the nature of the matrix (PE or PA), because of the selective affinity of clay toward polymer phases. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Processing and properties of transparent hydroxyapatite and β tricalcium phosphate obtained by HIP process

Stoichiometric β-tricalcium phosphate (β-TCP) and hydroxyapatite (HA) powders were synthesized by chemical precipitation of aqueous solutions of diammonium phosphate and calcium nitrate. After a calcination treatment and a milling step, the powders were shaped by slip casting. The sintering temperature effect on the relative density and the average grain size was investigated. By natural sintering at 1200 and 1120 °C, densities of 98% and 99% were obtained for HA and TCP, respectively. After determination of minimum temperatures to obtain only closed porosity and a pre-sintering at these temperatures, hot isostatic pressing (HIP) treatment was carried out. Transparent or translucent samples were obtained, indicating a relative density very close to the theoretical value (>99.9%). Mechanical properties (three-point bending strength, fracture toughness, Young's modulus and Vickers hardness) were measured on both materials with similar grain size (～ 1 μm). Bending strengths of 181 and 105 MPa were measured for TCP and HA, respectively.