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121.
Louis Étienne Denaud Laurent Bléron Alain Ratle Rémy Marchal 《Annals of Forest Science》2007,64(5):569-575
In the course of most wood machining processes, operators are usually able to detect various problems simply by hearing the sound emitted by the process. This is especially true for wood peeling. Lathe checks formation has been identified as one of the typical situations that an experimented peeler can detect. Poplar and beech veneer samples have been produced on a laboratory microlathe, using working conditions deliberately favourable to checking. Forces, sound, and vibration levels were measured during the tests. The lathe check frequencies have been determined on both sound and vibration signals using a local Root Mean Square (RMS) averaging and a peak detection algorithm. This makes possible the evaluation of lathe checks distribution along the veneer length. The technique was validated by measuring the real veneer profile using a specific apparatus developed by IVALSA-CNR in Trento (Italy). 相似文献
122.
Sophie Gachet Alain Leduc Yves Bergeron Thuy Nguyen-Xuan Francine Tremblay 《Forest Ecology and Management》2007
The aim of this study was to evaluate if and how the previous land use (here: agriculture versus forest) has influenced the floristic composition now observed in the understory of jack pine plantations of Abitibi-Temiscamingue (North-Eastern Canada). Floristic inventories were conducted in jack pine plantations which had been established on forest sites after logging and on sites previously utilized for agriculture. These were compared to one another and to inventories conducted in natural forests and on agricultural sites which had not (not yet) been planted with trees (old fields). The vegetation community composition of the sites is analysed using several multivariate techniques. Results show that the flora of plantations on old agricultural fields is markedly different than that of plantations established on sites which were previously forested and that the two types of plantation are unlikely to become floristically the same before the anticipated harvest time. Comparing old and young plantations and old fields in light of natural forests sites, we show that the previous land-use is a key determinant of future compositional differences in plantations. This must be considered when we evaluate the impact of establishing plantations on sites with different land-use histories. 相似文献
123.
分别采用硼氢化钠、亚硫酸氢钠及其混合物处理杨木APMP漂白机械浆,优化了处理条件,研究了不同化学药品对纸浆还原处理后改善白度稳定性效果。结果表明硼氢化钠处理杨木漂白化机浆不但能够显著改善其白度稳定性而且对纸浆具有漂白作用。加入亚硫酸氢钠混合处理纸浆可大幅度减少硼氢化钠用量,并能取得类似的改善纸浆白度稳定性效果。杨木碱性氧化氢漂白机械浆光诱导返色有其固有特点,傅立叶红外光谱显示,纸浆木质素中的羰基和酚羟基结构基团是引起纸浆光诱导返色的主要原因。 相似文献
124.
Megiatto JD Hoareau W Gardrat C Frollini E Castellan A 《Journal of agricultural and food chemistry》2007,55(21):8576-8584
Sisal fibers have one of the greatest potentials among other lignocellulosic fibers to reinforce polymer matrices in composites. Sisal fibers have been modified to improve their compatibility with phenolic polymer matrices using furfuryl alcohol (FA) and polyfurfuryl alcohols (PFA) that can be obtained from renewable sources. The modification corresponded first to oxidation with ClO 2, which reacts mainly with guaiacyl and syringyl units of lignin, generating o- and p-quinones and muconic derivatives, followed by reaction with FA or PFA. The FA and PFA modified fibers presented a thin similar layer, indicating the polymer character of the coating. The untreated and treated sisal fibers were characterized by (13)C CP-MAS NMR spectrometry, thermal analysis, and scanning electron microscopy. Furthermore, for a better understanding of the reactions involved in the FA and PFA modifications, the sisal lignin previously extracted was also submitted to those reactions and characterized. The characterization of isolated lignin and hemicellulose provides some information on the chemical structure of the main constitutive macrocomponents of sisal fibers, such information being scarce in the literature. 相似文献
125.
Naef R Jaquier A Velluz A Maurer B 《Journal of agricultural and food chemistry》2006,54(24):9201-9205
The volatile constituents of two exquisite green tea varieties, Kiyosawa tea from Japan and Long Jing tea from China, were investigated in order to identify new compounds responsible for the characteristic flavor of a green tea brew. The extracts were prepared by solid-phase extraction using Oasis-HLB-cartridges. Besides the common compounds of green tea chemistry, the already described compounds 3-methyl-2,4-nonanedione (1) and 3-hydroxy-3-methyl-2,4-nonanedione (2), products of degradation of furan fatty acids, as well as three new compounds related to compound 1 were identified. These were 1-methyl-2-oxopropyl hexanoate (3), 1-methyl-2-oxoheptyl acetate (4) and 2-butyl-4,5-dimethyl-3(2H)-furanone (5). Their syntheses and spectroscopic data are reported. Compound 2 increases the sweet, creamy aroma and the characteristic mouthfeel of a green tea flavor, compounds 3 and 4 contribute to its floral, juicy notes and compound 5 exhibits an interesting sweet, buttery flavor. 相似文献
126.
Laurent Larrieu Alain Cabanettes Antoine Delarue 《European Journal of Forest Research》2012,131(3):773-786
In forest ecosystems, the level of biodiversity is strongly linked to dead wood and tree microhabitats. To evaluate the influence
of current forest management on the availability of dead wood and on the abundance and distribution of microhabitats, we studied
the volume and diversity of dead wood objects and the distribution and frequency of cavities, dendrothelms, cracks, bark losses
and sporophores of saproxylic fungi in montane beech-fir stands. We compared stands unmanaged for 50 or 100 years with continuously
managed stands. A total of 1,204 live trees and 460 dead wood objects were observed. Total dead wood volume, snag volume and
microhabitat diversity were lower in the managed stands, but the total number of microhabitats per ha was not significantly
different between managed and unmanaged stands. Cavities were always the most frequent microhabitat and cracks the least frequent.
Dendrothelm and bark loss were favored by management. Beech (Fagus sylvatica) carried many more microhabitats than silver fir (Abies alba), especially cavities, dendrothelms and bark losses. Fir very scarcely formed dendrothelms. Secondary tree species played
an important role by providing cracks and bark losses. The proportion of microhabitat-bearing trees increased dramatically
above circumference thresholds of 225 cm for beech and 215 cm for fir. Firs with a circumference of less than 135 cm did not
carry microhabitats. In order to conserve microhabitat-providing trees and to increase the volume of dead wood in managed
stands, we recommend conserving trees that finish their natural cycle over 10–20% of the surface area. 相似文献
127.
Trace metals and animal health: Interplay of the gut microbiota with iron,manganese, zinc,and copper
Metals such as iron, manganese, copper, and zinc are recognized as essential trace elements. These trace metals play critical roles in development, growth, and metabolism, participating in various metabolic processes by acting as cofactors of enzymes or providing structural support to proteins. Deficiency or toxicity of these metals can impact human and animal health, giving rise to a number of metabolic and neurological disorders. Proper breakdown, absorption, and elimination of these trace metals is a tightly regulated process that requires crosstalk between the host and these micronutrients. The gut is a complex system that serves as the interface between these components, but other factors that contribute to this delicate interaction are not well understood. The gut is home to trillions of microorganisms and microbial genes (the gut microbiome) that can regulate the metabolism and transport of micronutrients and contribute to the bioavailability of trace metals through their assimilation from food sources or by competing with the host. Furthermore, deficiency or toxicity of these metals can modulate the gut microenvironment, including microbiota, nutrient availability, stress, and immunity. Thus, understanding the role of the gut microbiota in the metabolism of manganese, iron, copper, and zinc, as well as in heavy metal deficiencies and toxicities, and vice versa, may provide insight into developing improved or alternative therapeutic strategies to address emerging health concerns. This review describes the current understanding of how the gut microbiome and trace metals interact and affect host health, particularly in pigs. 相似文献
128.
Kierzkowski D Nakayama N Routier-Kierzkowska AL Weber A Bayer E Schorderet M Reinhardt D Kuhlemeier C Smith RS 《Science (New York, N.Y.)》2012,335(6072):1096-1099
Although genetic control of morphogenesis is well established, elaboration of complex shapes requires changes in the mechanical properties of cells. In plants, the first visible sign of leaf formation is a bulge on the flank of the shoot apical meristem. Bulging results from local relaxation of cell walls, which causes them to yield to internal hydrostatic pressure. By manipulation of tissue tension in combination with quantitative live imaging and finite-element modeling, we found that the slow-growing area at the shoot tip is substantially strain-stiffened compared with surrounding fast-growing tissue. We propose that strain stiffening limits growth, restricts organ bulging, and contributes to the meristem's functional zonation. Thus, mechanical signals are not just passive readouts of gene action but feed back on morphogenesis. 相似文献
129.
Catherine Breton Alain Gil Julie Wargnier Hervé Serieys André Bervillé 《Euphytica》2012,186(2):557-572
Common sunflower (i.e., Helianthus annuus) is occasionally crossed with other Helianthus species to gain favourable agronomic traits. An interspecific cross between H. annuus and Helianthus mollis was used to examine events that occurred during the five first generations. First generation hybrid plants were verified using GISH, and F1 hybrid (#17) was back-crossed to common sunflower to obtain BC1 (#4) and BC2 (#21). Some BC2 progeny possessed new traits, i.e., compact (Compact plant architecture is due to short inter-node length, short petiole length and short leaf lamina length) architecture without and with corrugated leaves, which were not observed in the parents. These traits were selected for and fixed after the BC2-S3 (#18) to produce a H. mollis introgression line (namely HM374). Although the size of the population was small, we tentatively construct a genetic map using data from the BC2 generation. Two linkage groups were identified carrying H. mollis specific AFLP markers that were associated with compact plant architecture, and one unlinked marker was shown to explain variation for the corrugated leaves. Introgression line HM374 was used to test the inheritance of compact plant architecture in a cross with an elite high oleic line, OL75HO. Microsatellite (SSR) markers were used to genotype F1 and F2 offspring’s. Our data suggested that the line HM374 was still heterozygous for introgression after eight generations. HM374 displays new architecture traits (i.e. compact architecture with or without corrugated leaves) and carries H. mollis fragments anchored on LG1 and LG11 of sunflower public map. 相似文献
130.
François Bellamy Thomas Bader Alain Moussy Olivier Hermine 《Veterinary research communications》2009,33(8):831-837
Masitinib is the first veterinary drug recently approved in Europe to treat mast cell tumours in dogs (Hahn et al. JVIM, Masivet).
This inhibitor is selective and highly efficient in blocking c-Kit, PDGFR, and Lyn tyrosine kinase activities. It showed good
efficacy and acceptable toxicity in several animal studies such as mice, rats, rabbits and dogs (Dubreuil P, et al. submitted,
and Hahn et al. (J Vet Intern Med 22(6):8, 2008)). C-kit is a tyrosine kinase receptor that plays a critical role in the biology of mast cells including differentiation,
survival, migration and cytokine/mediator release. Mast cells are involved in a number of allergy-and immune-related diseases
in cats such as asthma (Reinero Carol et al. Vet Immunol Immunopathol 121(3–4):9, 2008), inflammatory bowel disease, (Janeczko et al. Vet Mic 128(1–2):15, 2008), and feline mast cell tumours (Rassnick et al. J Am Vet Med Assoc 232(8):1200–1205, 2008). Therefore, there might be a strong rationale to use masitinib in these indications. Here, we report the results of a preliminary
pharmacokinetic study of masitinib in cats which showed a good bioavailability of ~60% in both sexes. We propose that an oral
dose of 10–15 mg/kg masitinib is appropriate to achieve adequate plasma concentrations. 相似文献