Effects of microstructure and crystallography on crack path and intrinsic resistance to shear-mode fatigue crack growth

The paper focuses on the effective resistance and the near-threshold growth mechanisms in theferritic-pearlitic and the pure pearlitic steel. The influence of microstructure on the shear-mode fatigue crackgrowth is divided here into two factors: the crystal lattice type and the presence of different phases.Experiments were done on ferritic-pearlitic steel and pearlitic steel using three different specimens, for whichthe effective mode II and mode III threshold values were measured and fracture surfaces were reconstructed inthree dimensions using stereophotogrammetry in scanning electron microscope. The ferritic-pearlitic andpearlitic steels showed a much different behaviour of modes II and III cracks than that of the ARMCO iron.Both the deflection angle and the mode II threshold were much higher and comparable to the austenitic steel.Mechanism of shear-mode crack behaviour in the ARMCO iron, titanium and nickel were described by themodel of emission of dislocations from the crack tip under a dominant mode II loading. In other testedmaterials the cracks propagated under a dominance of the local mode I. In the ferritic-pearlitic and pearliticsteels, the reason for such behaviour was the presence of the secondary-phase particles (cementite lamellas),unlike in the previously austenitic steel, where the fcc structure and the low stacking fault energy were the mainfactors. A criterion for mode I deflection from the mode II crack-tip loading, which uses values of the effectivemode I and mode II thresholds, was in agreement with fractographical observations

The Influence of synthetic strigolactones and plant extracts on the morphological parameters of onion (Allium cepa)

In recent years there has been frequent reference to the significance of strigolactones as a new group of hormones which might have a significant effect on horticultural production. The aim of this work was to find an ideal combination of stable synthetic strigolactones and plant extracts with potential effects on onion plants. The synthetic strigolactone Fenyl 7 (dihydro-3-[[2,5- dihydro-4-methyl-5-oxo-2-furanyl)oxy]-methylene]-5-phenyl-2(3H)-furanone) was tested in a carrot macerate, with citric acid and with salicylic acid. From the results it was confirmed that increasing the pH of the preparation leads to improving the stability of Fenyl 7. Evaluation has repeatedly confirmed the effect of the preparation, combining synthetic strigolactone and a macerate of carrot in a mixture of surfactants with added citric acid. In all the experiments this combination showed a statistically demonstrable influence on leaf weight (increased by 12-31%) and length (increased by 6-13%) in comparison with the controls.

Demography and Dispersal Ability of a Threatened Saproxylic Beetle: A Mark-Recapture Study of the Rosalia Longicorn (Rosalia alpina)

The Rosalia longicorn or Alpine longhorn (Coleoptera: Cerambycidae) is an endangered and strictly protected icon of European saproxylic biodiversity. Despite its popularity, lack of information on its demography and mobility may compromise adoption of suitable conservation strategies. The beetle experienced marked retreat from NW part of its range; its single population survives N of the Alps and W of the Carpathians. The population inhabits several small patches of old beech forest on hill-tops of the Ralska Upland, Czech Republic. We performed mark-recapture study of the population and assessed its distribution pattern. Our results demonstrate the high mobility of the beetle, including dispersal between hills (up to 1.6 km). The system is thus interconnected; it contained ∼2000 adult beetles in 2008. Estimated population densities were high, ranging between 42 and 84 adult beetles/hectare a year. The population survives at a former military-training ground despite long-term isolation and low cover of mature beech forest (∼1%). Its survival could be attributed to lack of forestry activities between the 1950s and 1990s, slow succession preventing canopy closure and undergrowth expansion, and probably also to the distribution of habitat patches on conspicuous hill-tops. In order to increase chances of the population for long term survival, we propose to stop clear-cuts of old beech forests, increase semi-open beech woodlands in areas currently covered by conifer plantations and active habitat management at inhabited sites and their wider environs

Propagation of Long Fatigue Cracks under Remote Modes II and III in Ferritic-Pearlitic Steel

The aim of this research was to determine the 3D crack path and the related growth micromechanism in specimens made of the ferritic-pearlitic steel loaded in modes II and III. Crack closure effects were minimized at the beginning of the experiments by a special technique of generation of precracks in order to measure effective values of fatigue thresholds. Dependences of the crack growth rate on the stress intensity factor range were plotted for the near-threshold region. The effective mode III threshold \DeltaK_text{IIIeff,th}=4.4 MPam^{1//2} was found to be higher than that for mode II (\DeltaK_\text{IIeff,th}=2.9 MPam^{1//2}, the theory predicts $3.1 MPam^{1//2}$) which is in agreement with the results for other metallic materials and available theoretical models. Fractographical observations in three dimensions revealed that the remote mode II cracks deflected towards the opening mode I by the mean angle ≈50°, which is significantly different from the low-angle deflections (coplanar growth) previously observed in the ARMCO iron. The simple linear elastic fracture mechanics based criterion for growth of a mode I branch at the crack front loaded in mode II was fulfilled

Screening of Chilli Pepper Genotypes as a Source of Capsaicinoids and Antioxidants under Conditions of Simulated Drought Stress

In many regions of the world, the production of vegetable crops is limited by a deepening water crisis. Drought stress aects productivity and the chemical composition of crops. The variability of drought tolerance between species and cultivars of economically important crops, such as pepper (Capsicum species), requires specific investigations to understand the physiological and biochemical responses to the aftermath of drought. The fruits and leaves of four chilli pepper cultivars were investigated to elucidate the fruits’ pungency (Scoville Heat Units, SHU), ascorbic acid content, DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity, polyphenol content, membrane lipid peroxidation and key protective antioxidant enzyme activity under drought stress (18–28% volumetric water content) as compared to the control (35–60%). Drought increased the chilli pepper fruits’ pungency expressed in Scoville Heat Units (SHU) as well as ascorbic acid content, but this relationship was also dependent on genotype and stress duration. ‘Jolokia’ was marked as most sensitive to drought by increasing content of capsaicinoids and DPPH scavenging activity under stress conditions. Capsaicinoids and Ascorbic acid (AsA) greatly influenced the antioxidant activity of highly pungent chilli pepper fruits, although total phenols played a significant role in the mildly pungent genotypes. Generally, the activities of antioxidant enzymes increased under drought in chilli pepper leaves and fruits, although the intensity of the reaction varied among the cultivars used in the current research. All the investigated biochemical parameters were involved in the drought response of chilli pepper plants, but their significance and eectiveness were highly cultivar-dependent

Ocena różnych metod ekstrakcji dna w celu wykrycia bakterii Xanthomonas campestris pv. Campestris w liściach kapusty

The bacterium Xanthomonas campestris pathovar campestris (Xcc) as the causal agent of black rot of cruciferous plants causes considerable losses in agricultural yield all over the world. The control of black rot is difficult as well as the determination of Xccon the basis of morphological parameters or by pathogenicity testing. Ten different possibilities for extraction bacterial DNA followed by PCR detection method were tested to optimize PCR protocol. On the basis of ISTA validated method, three sets of primers UBP 1052F-BACR, DLH 120-125 and ZUP 2309-2310 were used. The results of measured concentration and quality of DNA and efficacy for PCR amplification were compared. Finally, three approaches for DNA extraction within Xanthomonas campestris pv. campestris detection protocol were recommended – commercial kits used for isolation from tissues by Macherey-Nagel and MO BIO and kit intended for microbial cultures by MO BIO.Bakteria Xanthomonas campestris pathovar campestris (Xcc) jako przyczyna czarnej zgnilizny roślin z rodziny krzyżowych powoduje znaczne straty w plonie rolniczym na całym świecie. Zwalczanie czarnej zgnilizny, a także określenie Xcc na podstawie parametrów morfologicznych lub za pomocą testów patogeniczności jest trudne. W celu zoptymalizowania protokołu PCR przetestowano dziesięć różnych możliwości ekstrakcji DNA, a następnie metodę PCR. Na podstawie walidowanej metody ISTA za-stosowano trzy zestawy primerów, mianowicie UBP 1052F-BACR, DLH 120-125 i ZUP 2309-2310. Porównano wyniki zmierzonego stężenia i jakości DNA oraz skuteczności dla amplifikacji PCR. Zalecono trzy sposoby ekstrakcji DNA w ramach protokołu detekcji Xanthomonas campestris pv. Campestris: zestaw komercyjny używany do izolacji z tkanek według Macherey-Nagel, MO BIO oraz zestaw dla hodowli mikrobowych według MO BIO

Plant growth, yield, fruit quality and residual biomass composition of tomato as affected by mulch type

This research was carried out to assess the effects of biodegradable mulching films on fruit yield and quality performances of greenhouse grown tomato, in southern Italy. Four mulching treatments (two MaterBi biodegradable black films, MB N2/12 and MB N8, having 15 and 12 μm thickness respectively; black polyethylene film, LDPE, 50 μm thick; non-mulched control) were compared using a randomized complete block design with three replicates. LDPE resulted in higher harvest precocity than non-mulched control. The biodegradable MB N8 and the plastic LDPE films led to the highest fruit yield, total crop biomass and leaf area index, whereas the non-mulched control had the lowest values in terms of overall performances. Fruit dry matter and soluble solids were the highest under the biodegradable films MB N2/12 and MB N8, and the lowest in the control. Titratable acidity and color component “a” were the highest under MB N8 and the lowest in the control. Fruits of MB N8 and LDPE attained the highest levels of color components “L” and “b” respectively, the biodegradable mulch MB N8 also led to the highest fruit firmness. The highest antioxidant concentrations and activities were obtained from the biodegradable films. Biodegradable mulch films MB N2/12 and MB N8 proved to be as effective as the plastic film in terms of tomato yield, but the positive effect on fruit quality and antioxidant content as well as the environmentally friendly features of those films also increase their importance

Agricultural practices, biology and quality of eggplant cultivated in Central Europe. A Review.

The eggplant is a warm-climate crop of high economic importance. In many Asian and Mediterranean countries, eggplants are essential components of everyday dishes, while in Central Europe they have become popular only in recent years. Eggplants are harvested at an immature stage and have low storage value; therefore, the sale of fruits in local markets requires an appropriate production strategy. In Poland, consumer demand for eggplants is currently met by imports and domestic production, which, until recently, has been carried out only in greenhouses, ensuring the availability of fresh fruits but resulting in high selling prices. The demand for eggplants is growing among Polish consumers, and, accordingly, field production is expected to gradually gain in importance due to the fruit’s profitability. Accordingly, the biology and farming practices of this warm-climate crop remain in the investigation phase in temperate climate. This review aims to report the status of current knowledge regarding the technologies affecting the biology, cultivation, and nutritional value of eggplant grown in temperate climatic zone