Study of modal structure of a semiconductor laser by measurement of the complex degree of coherence

The evaluation of the amplitude of the lateral transverse modes emitted by a semiconductor laser, by means of near or farfield techniques, generally is not easy. In this paper the behaviour of the optical coherence function provides much more sensitive method of analysis. A simple way of implementing the above analysis is described and the results of an experiment are reported.     

Influence of must composition on phenolic oxidation kinetics

White grape musts with added sulphur dioxide, ascorbic acid, glutathione, copper or flavanols were prepared and oxidised using known amounts of oxygen. Sulphur dioxide and ascorbic acid delayed caffeoyltartaric acid oxidation, 2-S-glutathionyl caffeoyltartaric acid (GRP) formation and browning development. The glutathione content determined the quantity of GRP formed; browning was prevented when all the caffeoyltartaric acid quinones generated by enzymic oxidation could be trapped as GRP. Cupric ions, which lower the concentration of available glutathione, enhanced must browning. Coupled oxidation of flavanols by the caffeoyltartaric acid quinones also led to increased discoloration.     

Antihypertensive activity of casein-enriched milk fermented by Lactobacillus helveticus

Milk proteins contain peptidic angiotensin I-converting enzyme (ACE) inhibitors, which can be released by proteolysis during milk fermentation by some strains of Lactobacillus helveticus. Reconstituted milk media containing skim milk powder (12%), skim milk powder (10%) with added sodium caseinate (5%) or whey protein isolate (5%) were fermented by L. helveticus strains R211 and R389, and further tested for bacterial growth, proteolysis (free NH₃ groups) and ACE-inhibitory activity. The antihypertensive activity in spontaneously hypertensive rats (SHR) was also investigated with caseinate-enriched milk unfermented (UFM) and fermented by the two strains of L. helveticus. Caseinate-enriched milk fermented by both strains showed higher proteolysis and ACE-inhibitory activity, indicating that ACE-inhibitory peptides are probably released from caseins during milk fermentation. Significant decreases in mean arterial blood pressure in SHR rats were measured following oral administration of UFM milk at doses of 1.0 and 2.5 g kg⁻¹ of body weight, and milk fermented by R211 or R389 strains at doses of 0.5, 1.0 and 2.5 g kg⁻¹ of body weight. The antihypertensive activity of UFM could be explained by the release of ACE-inhibitory peptides from caseins during the digestion process.     

Genetic evaluation of claw health traits accounting for potential preselection of cows to be trimmed

Claw lesions are one of the most important health issues in dairy cattle. Although the frequency of claw lesions depends greatly on herd management, the frequency can be lowered through genetic selection. A genetic evaluation could be developed based on trimming records collected by claw trimmers; however, not all cows present in a herd are usually selected by the breeder to be trimmed. The objectives of this study were to investigate the importance of the preselection of cows for trimming, to account for this preselection, and to estimate genetic parameters of claw health traits. The final data set contained 25,511 trimming records of French Holstein cows. Analyzed claw lesion traits were digital dermatitis, heel horn erosion, interdigital hyperplasia, sole hemorrhage circumscribed, sole hemorrhage diffused, sole ulcer, and white line fissure. All traits were analyzed as binary traits in a multitrait linear animal model. Three scenarios were considered: including only trimmed cows in a 7-trait model (scenario 1); or trimmed cows and contemporary cows not trimmed but present at the time of a visit (considering that nontrimmed cows were healthy) in a 7-trait model (scenario 2); or trimmed cows and contemporary cows not trimmed but present at the time of a visit (considering lesion records for trimmed cows only), in an 8-trait model, including a 0/1 trimming status trait (scenario 3). For scenario 3, heritability estimates ranged from 0.02 to 0.09 on the observed scale. Genetic correlations clearly revealed 2 groups of traits (digital dermatitis, heel horn erosion, and interdigital hyperplasia on the one hand, and sole hemorrhage circumscribed, sole hemorrhage diffused, sole ulcer, and white line fissure on the other hand). Heritabilities on the underlying scale did not vary much depending on the scenario: the effect of the preselection of cows for trimming on the estimation of heritabilities appeared to be negligible. However, including untrimmed cows as healthy caused bias in the estimation of genetic correlations. The use of a trimming status trait to account for preselection appears promising, as it allows consideration of the exhaustive population of cows present at the time a trimmer visited a farm without causing bias in genetic parameters.     

Characterization of new strain Lactobacillus paracasei I-N-10 with proteolytic activity: Potential role in decrease in β-casein immuno-reactivity

The proteolytic activity of thirty-three LAB isolates from Mongolian tarag was tested on skimmed milk. The strain displaying the highest proteolytic activity was purified and presented by 16S rDNA sequencing 99.9?% homology with Lactobacillus paracasei 1-4-2A. It was named L. paracasei I-N-10. Proteases of L. paracasei I-N-10 hydrolyze predominately ??-casein and in some level ??_S2-casein; hydrolysis of ??_S1-casein was not observed. Proteolytic activity was optimal at 42?°C and neutral pH. Proteases of L. paracasei I-N-10 were inhibited by serine- and metalloproteases inhibitors. PCR amplification revealed the presence of prtP gene, which was identical to prtP gene of L. paracasei genus. Mass spectrometry analysis of ??-casein hydrolysate allowed to characterize 7 peptides resulting from proteolysis by L. paracasei I-N-10. The isolated strain was able to cleave ??-casein in different sites including 2 of the major linear epitopes implicated in its allergenicity. Being sensitive to main antibiotics classes, L. paracasei I-N-10 could be considered as safe and used as starter culture with a potential role in decreasing ??-casein immuno-reactivity.     

Yield and composition of cell wall residues isolated from various feedstuffs used for non-ruminant farm animals

The contents of cell wall residue were measured in 14 common feedstuffs used for non-ruminant farm animals by utilising a technique involving pronase and α-amylase treatments. Comparison with the contents of neutral detergent fibre (NDF) revealed that the NDF procedure underestimated cell wall contents in the dicotyledonous plant materials. The losses of cell wall material due to the neutral detergent solution were correlated (r=0.931, P<0.01) with the amount of pectic substances present in the cell wall residues of the dicotyledonous plant materials. Cell wall residues were analysed for starch, crude protein, polysaccharides, condensed tannins, sulphuric acid lignin, acetyl bromide lignin, and ash. Condensed tannins in the cell wall residues of sorghum, rapeseed meal and field bean resulted in a large protein contamination (11.3–26.6%) of these residues and to an overestimation of their lignin content. Compositions of polysaccharides are discussed from chemical and nutritonal viewpoints.     

Characterisation of highly polymerised prodelphinidins from skin and flesh of four cashew apple (Anacardium occidentale L.) genotypes

Tannins were extracted by acetone/water 60:40 from skin and flesh of four cashew apple genotypes from Brazil and Bénin (West Africa), and separated from monomeric phenols. Tannins were submitted to acid-catalysed degradation in the presence of phloroglucinol and the products were analysed by HPLC–DAD/ESI–MS. Both skin and flesh tannins contained high percentages of (-)-epigallocatechin and (-)-epigallocatechin-O-gallate, followed by minor quantities of (-)-epicatechin and (-)-epicatechin-3-O-gallate; 100% of the compounds were the 2,3-cis configuration. Skin tannins were half as galloylated (∼20%) than flesh tannins (∼40%). Their weight-average molecular weight (M_w) was high.     

Monomeric phenols of cashew apple (Anacardium occidentale L.)

Monomeric phenols were extracted by acetone/water (60:40) from the skin and flesh of four cashew apple genotypes from Brazil and Bénin (West Africa), purified by absorption chromatography and subjected to HPLC-DAD/ESI-MS analysis. Skins were found much richer than fleshes in simple phenolics. Flavonol glycosides were dominant with myricetin and quercetin hexosides (2 of each), pentosides (3 of each), and rhamnosides as major compounds. Anthocyanidin glycosides were detected in skins from the two scarlet and orange pigmented genotypes as peonidin, petunidin and cyanidin 3-O-hexosides, and were absent from fleshes.     

Electrical and mechanical percolation in graphene-latex nanocomposites

Conductive composites based on few layer graphene are of primary interests. In this work latex based composites were produced leading to a specific cellular morphology. Highly conductive graphene-based composite materials have been produced through a solvent-free procedure. Both the mechanical and conductivity behaviors were successfully described using a percolation approach that confirms the presence of a three dimensional filler network efficiently spread across the material. The influence of the aspect ratio between the conductive filler and the latex nanosphere drove the study. It was demonstrated experimentally that the tuning of the cell dimensions of the composite morphology influences the percolation threshold and the reachable maximum conductivity and reinforcement. These experimental results are consistent with phenomenological models based on the statistical percolation theory.     

Metabolism of phenylalanine and biosynthesis of styrene in Penicillium camemberti

The occurrence of styrene in food may be an important aroma defect (celluloid odour), even at very low concentrations (Miltz et al. 1980) causing consumer rejection and is therefore a problem for the food industry. We examined the biosynthetic pathway leading to styrene formation by Penicillium camemberti using labelled compounds. As styrene is strongly hydrophobic and volatile, we first had to develop a continuous extraction process. Using resins XAD2 it was reasonable to suspect phenylalanine (Phe) as the precursor. The addition of Phe marked with 13C on the ring provokes the accumulation of labelled styrene. The enzyme activities involved were also tentatively measured. Styrene appears to be synthesized from phenylalanine by phenylalanine ammonia-lyase activity followed by a decarboxylation catalysed by a cinnamic acid decarboxylase.