Development of high-performance strand boards: multiscale modeling of anisotropic elasticity

The interrelationships between microstructural characteristics and anisotropic elastic properties of strand-based engineered wood products are highly relevant in order to produce custom-designed strand products with tailored properties. A model providing a link between these characteristics and the resulting elastic behavior of the strand products is a very valuable tool to study these relationships. Here, the development, the experimental validation, and several applications of a multiscale model for strand products are presented. In a first homogenization step, the elastic properties of homogeneous strand boards are estimated by means of continuum micromechanics from strand shape, strand orientation, elastic properties of the used raw material, and mean board density. In a second homogenization step, the effective stiffness of multi-layer strand boards is determined by means of lamination theory, where the vertical density profile and different layer assemblies are taken into account. On the whole, this model enables to predict the macroscopic mechanical performance of strand-based panels from microscopic mechanical and morphological characteristics and, thus, constitutes a valuable tool for product development and optimization.     

Translocation of apple proliferation phytoplasma via natural root grafts – a case study

Apple proliferation (AP), a phytoplasma-induced disease of apple trees, was proven to be transmitted through infected grafting material and sap-sucking insects. To date there are little firm data on disease propagation in the field via natural root grafts. This question was thus addressed in the present case study by investigating trees of a 24-year old commercial apple orchard (‘Red Chief’ on MM 111), where the existence of root connections was discovered accidentally. After having displayed specific AP symptoms, nine trees were cut down and the stubs were infiltrated or brushed with glyphosate. Herbicide injury, however, remained not only restricted to the treated stubs, but also spread to approximately 50 neighbouring trees. Surprisingly, none of the pollinators (‘Granny Smith’ on M 9) growing interjacently and alternating between herbicide-damaged main crop trees was affected. Respective to the position of the nine AP-infected and glyphosate-treated cut stumps, four sections in the orchard were defined, from which a total of 122 trees was sampled and analysed using qualitative real-time PCR for detection of AP phytoplasma. The pathogen was found in 71.4% of ‘Red Chief’ trees with severe herbicide damage and 18.8% of trees with partial herbicide damage. None of the 31 investigated pollinators was AP-infected. Our data indicate that root connections seem to play a role for the spread of AP phytoplasma at least in older orchards and between trees on vigorous rootstocks.     

Effects of microcystin-containing cyanobacterial extract on hematological and biochemical parameters of common carp (Cyprinus carpio L.)

The aim of the study was to assess the effects of a cyanobacterial extract containing microcystins (MCs) on selected hematological and biochemical parameters in common carp (Cyprinus carpio L.), as well as to determine the accumulation of toxins in fish tissues. The fish were immersed for 5 days in water containing toxins at a final concentration of 12 μg/L of microcystin LR equivalent. Microcystin LR residues were detected in fish liver, reaching 207, 238 and 260 ng/g f.w. of the tissues taken 24 h, 72 h and 5 days after the end of intoxication, respectively. The most substantial changes were found in fish plasma, including increases in creatine kinase, lactate dehydrogenase, ammonia, glucose, aspartate aminotransferase and alanine aminotransferase levels. A decline of about 50% in lysozyme activity was observed by the end of the experimental period. Moreover, a marked increase in ceruloplasmin activity was detected 24 h after the end of intoxication with a subsequent decrease in its activity after 72 h and 5 days. This study concludes that not only consumption of food containing toxins but also MCs dissolved in water may pose a threat to fish health. Additionally, detected changes in lysozyme and ceruloplasmin activity may have distinct effects in fish resistance against pathogens or oxidative stress, which should be taken into account in the future studies.     

Effect of cutting frequency on species richness and dry matter yield of permanent grassland after grazing cessation

The effect of grazing cessation management has only rarely been investigated. In this study, the influence of cutting regime in the absence of fertilization was examined during 2005–2011 on a semi-natural grassland in Rapotin (Czech Republic) which had been grazed for more than 30 years before the start of the trial. This was conducted as a randomized plot design with five levels of treatment: 4 C – intensive (four cuts per year); 3 C – medium intensive (three cuts per year); 2 C – low intensive (two cuts per year); 1 C – extensive (one cut per year); 0 C – abandoned (control; without any management). Species richness was significantly lower in treatments 1 C and 0 C than in other treatments. Management and year had similar and significant influence on species composition and explained 23% of its variability. Dry matter (DM) yields were found to be lower in three-cut than in two-cut treatments (5.56 t ha^?1 and 6.22 t ha^?1, respectively). In the case of grazing cessation, a suitable compromise of three cuts per year can be recommended to guarantee maintenance of species richness, botanical composition, and appropriate grass forage yield under similar site conditions.     

Tree Fruit Growing—Research and Production in Germany: A Statistical and Bibliometric Analysis of the Period 1950–2010

Germany is one of the leading European countries in tree fruit growing and the fruit produced has an actual production value of 794?million?€. Six decades, from 1950 to 2010, of fruit production and internationally relevant scientific output for fruit crops—apple, pear, cherry, plum, apricot, and peach—were analysed in this study. Bibliographic and bibliometric analyses were based on the Science Citation Index^?. Data were compared and discussed in the European and global context. The German annual per capita consumption of fruit amounts to 125.5?kg/a originating from commercial intensive fruit growing, including 71.8?kg/a of fresh fruit, 48.3?kg/a of citrus and tropical fruit, 3.8?kg/a nut fruit, and 1.6?kg/a dry fruit. Approximately 25?kg per annum and inhabitant has to be added to the total fruit consumption, since a conspicuous amount of fruit originates from meadow orchards and house gardens. Nevertheless, Germany’s self-supply with fruit is a low 22.4%. Within the EU (2009/2010), Germany ranks fourth in apple production, tenth in pear production, fifth in cherry production, sixth in plum production, and 15th in the production of apricots and peaches. Based on the number of international scientific articles published in Germany, fruit crops can be ranked in descending order: apples, cherries, pears, plums, peaches and apricots. Relating the scientific output over the last six decades to the production data of the same country nowadays achieved, we obtain an indicator for the scientific impact on the crop production. On a worldwide comparison Germany ranks tenth for apple, sixth for pears, 21st for cherries, 17th for plums and first for apricots and peaches. With regard to the absolute output of scientific original articles Germany ranks fourth worldwide for apples, eighth for pears, second for cherries, fifth for plums, ninth for apricots and 14th for peaches, indicating that research on tree fruit growing in Germany supports the economic competitiveness of its production regions with highly specialized knowledge.     

A new approach for cytokinin isolation from Arabidopsis tissues using miniaturized purification: pipette tip solid-phase extraction

ABSTRACT: BACKGROUND: We have developed a new analytical approach for isolation and quantification of cytokinins (CK) in minute amounts of fresh plant material, which combines a simple one-step purification with ultra-high pressure liquid chromatography-fast scanning tandem mass spectrometry. RESULTS: Plant tissue samples (1-5 mg FW) were purified by stop-and-go-microextraction (StageTip purification), which previously has only been applied for clean-up and pre-concentration of peptides. We found that a combination of two reverse phases and one cation-exchange phase, was the best tool, giving a total extraction recovery higher than 80%. The process was completed by a single chromatographic analysis of a wide range of naturally occurring cytokinins (bases, ribosides, O- and N-glucosides, and nucleotides) in 24.5 minutes using an analytical column packed with sub-2-microne particles. In multiple reaction monitoring mode, the detection limits ranged from 0.05 to 5 fmol and the linear ranges for most cytokinins were at least five orders of magnitude. The StageTip purification was validated and optimized using samples of Arabidopsis thaliana seedlings, roots and shoots where eighteen cytokinins were successfully determined. CONCLUSIONS: The combination of microextraction with one-step high-throughput purification provides fast, effective and cheap sample preparation prior to qualitative and quantitative measurements. Our procedure can be used after modification also for other phytohormones, depending on selectivity, affinity and capacity of the selected sorbents.     

网室内作物蒸散量的变化和影响要素研究

在香蕉种植网室内,研究了网室内外作物蒸散量和参考作物蒸散量的关系,以及网室内小气候变化对参考作物蒸散量的影响.研究结果显示,网室内参考作物蒸散量(ET0)和A级蒸发皿水面蒸发量分别比大田减少39%和42%,网室内香蕉树蒸腾量较网室外下降53%.网室内净辐射降低和风速减小是网室内香蕉树蒸腾量和参考作物蒸散量降低的主要原因,而网室内温度和饱和水汽压差变化对蒸散量的影响较小.建立了网室内参考作物蒸散量和网室内外水面蒸发量的关系,计算出该地区的A级蒸发皿系数为0.84.