Species-Specific and Distance-Dependent Dispersive Behaviour of Forisomes in Different Legume Species

Forisomes are giant fusiform protein complexes composed of sieve element occlusion (SEO) protein monomers, exclusively found in sieve elements (SEs) of legumes. Forisomes block the phloem mass flow by a Ca²⁺-induced conformational change (swelling and rounding). We studied the forisome reactivity in four different legume species—Medicago sativa, Pisum sativum, Trifolium pratense and Vicia faba. Depending on the species, we found direct relationships between SE diameter, forisome surface area and distance from the leaf tip, all indicative of a developmentally tuned regulation of SE diameter and forisome size. Heat-induced forisome dispersion occurred later with increasing distance from the stimulus site. T. pratense and V. faba dispersion occurred faster for forisomes with a smaller surface area. Near the stimulus site, electro potential waves (EPWs)—overlapping action (APs), and variation potentials (VPs)—were linked with high full-dispersion rates of forisomes. Distance-associated reduction of forisome reactivity was assigned to the disintegration of EPWs into APs, VPs and system potentials (SPs). Overall, APs and SPs alone were unable to induce forisome dispersion and only VPs above a critical threshold were capable of inducing forisome reactions.     

Peculiarities of the composition of solid phases formed in aqueous calcium–silicate systems with a medium of variable acidity

The effect of a medium’s acidity on the composition of the solid phase formed in aqueous calcium-silicate systems is investigated. Solutions of Са(NO₃)₂ and Na₂SiO₃ are used for the synthesis; the pH values were varied in the range 7.00–12.00. Freshly precipitated solid phases and products of their annealing at 1000°C were studied by the methods of Fourier IR spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM).     

Quantitative analysis of morphological changes in yeast colonies growing on solid medium: the eccentricity and Fourier indices

The colony shape of four yeast species growing on agar medium was measured for 116 days by image analysis. Initially, all the colonies are circular, with regular edges. The loss of circularity can be quantitatively estimated by the eccentricity index, E_i, calculated as the ratio between their orthogonal vertical and horizontal diameters. E_i can increase from 1 (complete circularity) to a maximum of 1.17–1.30, depending on the species. One colony inhibits its neighbour only when it has reached a threshold area. Then, E_i of the inhibited colony increases proportionally to the area of the inhibitory colony. The initial distance between colonies affects those threshold values but not the proportionality, E_i/area; this inhibition affects the shape but not the total surface of the colony. The appearance of irregularities in the edges is associated, in all the species, not with age but with nutrient exhaustion. The edge irregularity can be quantified by the Fourier index, F_i, calculated by the minimum number of Fourier coefficients that are needed to describe the colony contour with 99% fitness. An ad hoc function has been developed in Matlab v. 7.0 to automate the computation of the Fourier coefficients. In young colonies, F_i has a value between 2 (circumference) and 3 (ellipse). These values are maintained in mature colonies of Debaryomyces, but can reach values up to 14 in Saccharomyces. All the species studied showed the inhibition of growth in facing colony edges, but only three species showed edge irregularities associated with substrate exhaustion. Copyright © 2014 John Wiley & Sons, Ltd.     

Numerical analysis of the crack growth path in the cement mantle of the reconstructed acetabulum

In this study, we use the finite element method to analyze the propagation's path of the crack in the orthopedic cement of the total hip replacement. In fact, a small python statement was incorporated with the Abaqus software to do in loop the following operations: extracting the crack propagation direction from the previous study using the maximal circumferential stresses criterion, drawing the new path, meshing and calculating again (stresses and fracture parameters). The loop is broken when the user's desired crack length is reached (number of propagations) or the value of the mode I stress intensity factor is negative. Results show that the crack propagation's path can be influenced by human body posture. The existing of a cavity in the vicinity of the crack can change its propagation path or can absolutely attract it enough to meet it. Crack can propagate in the outward direction (toward the acetabulum bone) and cannot propagate in the opposite direction, the mode I stress intensity factor increases with the crack length and that of mode II vanishes.     

Radiofrequency and microwave (10 kHz–8 GHz) electrical properties of polypyrrole and polypyrrole–poly(methyl methacrylate) composites

The complex permittivity ? = ?′ ?j ?″ of polypyrrole (PPY) samples and polypyrrole–poly(methyl methacrylate) (PPY‐PMMA) composites is calculated from measurements in the radiofrequency and microwave range (F = 10³–8 × 10⁹ Hz) at room temperature. A relaxation phenomenon is observed in PPY‐PMMA composites with polypyrrole concentration p = 6–12% by weight. The frequency F_max corresponding to the maximum of ?″ appears in the radiofrequency domain and increases with the PPY concentration from 10⁴ to 2 × 10⁶ Hz. This relaxation is caused by space charge moving into the conductive clusters of PPY. At low frequency F ? F_max, the real part of the permittivity ?′ becomes very high. For F ? F_max, PPY‐PMMA composites have a percolative behaviour, the percolation threshold p_c being 3.85%. For F ? F_max, in the microwave domain, an ac component of the conductivity σ_ac appears. σ_ac varies as a power function of the frequency, σ_ac ∝ ω ^x; with x < 1, x independent of p. © 2001 Society of Chemical Industry     

Specific roof behavior in the southern wing of the Upper Kama potash salt deposit

The authors consider a number of geomechanical monitoring methods for the underworked salt rock behavior, including visual control of its specific structural features, measurement of displacements using contour and depth reference points, and assessment of stresses in the surrounding rock mass. It is proposed to assess stresses in salt rocks using long spacing measurement methods without modeling-based recovery of stresses from measured strains if possible.     

Low-temperature processing and characterization of single-phase PZT powders by sol-gel method

A new sol-gel system using acetoin was developed and employed for the fabrication of PZT powders and films with compositions near the morphotropic phase boundary Pb(Zr_0.52Ti_0.48)O₃. Acetoin was used as chelating agent to replace the highly toxic methoxyethanol used in previous formulations. This route simplified the chemical processing of PZT-based solutions. Powders were completely crystallized by about 450 °C and contained the ferroelectric perovskite single phase. The firing temperature and time were to be the most important variables. Metallic lead formed only when excess Pb was incorporated. The precursor and the heat-treated powders have been characterized by using thermal analysis and X-ray diffractometry (XRD) studies. The average particle size, as measured from X-ray line broadening, was ∼35 nm.     

Physicochemical and nutritional properties and volatile constituents of six Japanese plum (<Emphasis Type="Italic">Prunus salicina</Emphasis> Lindl.) cultivars

The aim of this study is to contribute to the qualitative characterisation of six cultivars of Japanese plum (Prunus salicina Lindl.), i.e. ‘Black Amber’, ‘Suplumeleven’, ‘Fortune’, ‘Larry Ann’, ‘Suplumsix’ and ‘Songold’, by investigating their physicochemical and nutritional properties and their volatile fractions. The results indicate that the plum has a mean sugar content of 15% (between 12.3 and 17.8%), dietary fibre 1.2% (from 0.84 to 1.50%) and a mean energy value of 255 kJ 100 g⁻¹ of fresh produce (from 183 to 331 kJ 100 g⁻¹). ‘Black Amber’ has the highest phenolic and anthocyanin contents and the greatest total antioxidant activity. In terms of their volatile fraction, Japanese plums are relatively poor in volatile compounds in comparison with other stone fruits. However, there are significant differences between the cultivars studied, with ‘Fortune’ standing out as the richest in volatile compounds and especially in esters.