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.     

Electron beam penetration of poly (methyl methacrylate)/colemanite composite irradiated at low earth orbit space radiation environment

Poly (methyl methacrylate) modification by colemanite (CMT) addition has ensured beta shielding improvement. This study has connected with space environmental utilization with Kibo Japanese Experiment Module on International Space Station at low earth orbit. Space environment experiment was performed by using Kibo Experiment Handrail Attachment Mechanism–ExHAM. The changes in beta transmission of the composite were examined (by Sr-90 radioisotope) before and after space environmental utilization and details on beta penetration capacity was examined to protect the equipment (used in aviation and aerospace industries) from space radiation. Beta attenuation variations have indicated composite densification with beta attenuation enhancement after CMT addition.     

Study of the dielectric relaxation of poly(phenylpropyl acrylate) and poly(phenylpropyl methacrylate): effect of slight differences in chemical structure

A comparative study of the dielectric relaxational behaviour of two structurally close polymers, containing aromatic side groups, was carried out in order to analyse how slight differences in the chemical structure affect the molecular responses to perturbation field. Specifically, poly(phenylpropyl acrylate) (P3Ph1PA) and poly(phenylpropyl methacrylate) (P3Ph1PM) were studied using differential scanning calorimetry and dielectric relaxation spectroscopy in the frequency range 10^?2–10⁶ Hz and temperature window of ?80 to 120 °C. Both techniques show one glass–rubber transition for P3Ph1PA and two for P3Ph1PM, which evidence the great effect of the methyl groups on the segmental motions of the polymer. Phenomenological analysis of the data was carried out in order to establish the strength, width and fragility parameters of the glass–rubber transitions. In the case of P3Ph1PA, the strength is found to be larger than for P3Ph1PM, pointing out that the methyl group disturbs the mobility. Conductive processes dominate the dielectric spectra at high temperatures and low frequencies. © 2015 Society of Chemical Industry     

Effect of kaolin nanofiller and processing conditions on the structure,morphology, and biofilm development of polylactic acid

The effect of high energy ball milling, HEBM, and the presence of kaolin on the structure, morphology, and biofilm development of polylactic acid, PLA, were studied. Biofilm development was evaluated in terms of structural and/or morphological variations so as the sole presence of kaolin. Composites based on PLA filled with kaolin were prepared by HEBM followed by hot pressing to obtain films. Structure was studied by X‐ray diffraction and Fourier transformed infrared spectroscopy whereas morphology was inspected by scanning electron microscopy and atomic force microscopy. To study biofilm development on the surface of these materials, Pseudomonas fluorescens B52 were used. The shear forces from the milling process favor kaolin dispersion within the PLA. Longer milling times and cryogenic conditions improve clay dispersion. Subsequent hot pressing process enhances the most ordered structure of PLA (α‐phase) which is also favored with previous milling at longer times and under cryogenic conditions. Changes in P. fluorescens biofilm development are mainly due to modifications of surface properties induced by structural variations, being the most ordered structures those which better support bacterial adhesion and proliferation. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42676.     

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).     

Synthesis of Open Zeolite Structures from Mixtures of Tetramethylammonium and Benzylmethylalkylammonium Cations: A Step Towards Driving Aluminium Location in the Framework

Three bulky organic cations, benzylmethylpyrrolidinium (BMP), (S,S)-2-hydroxymethyl-1-benzyl-1-methylpyrrolidinium (BML) and benzylmethylhexamethyleniminium (BMH), were used in combination with the small cation tetramethylammonium (TMA) in the synthesis of zeolite materials. Two of them are distinguished by the number of carbon atoms forming the cyclic amine, which varies from 4 in BMP to 6 in BMH. In addition, a –CH₂–OH group has been introduced in the carbon atom belonging to the amine ring next to the nitrogen atom, to originate a chiral molecule, BML, the third SDA used in this work. It has been found that the combination of the small TMA with those three bulkier SDAs, promotes the crystallization of zeolite structures that contain cages and channels. BMP leads to the crystallization of the 10-ring zeolite ferrierite, where TMA is located inside the ferrierite cage. If the size of the N-cyclic amine moiety increases, the resulting cation cannot be accommodated in the relatively narrow 10-ring channels of ferrierite, and in these cases the zeolite MCM-22 crystallizes. This zeolite contains large cages whose cross section is delimited by a 12-ring, where both BMH and BML can be easily accommodated. In this system, cage-like, chlatrasil type structures often co-crystallize with the open structures, evidencing that an appropriate balance between TMA and the bulky SDA is required to achieve the crystallization of open-frameworks. When BMP is used, mixtures of structurally related ferrierite and cage-like RUB-10 are obtained if an excess of TMA is present in the synthesis gel, while MCM-22 crystallizes together with the structurally related cage-like MTN phase.     

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.     

Effect of the glass substrate on the efficiency of the different orders that propagate in a transmission sinusoidal diffraction grating

In this work we study the effect of the glass substrate on the efficiencies of the different orders that propagate inside a transmission sinusoidal diffraction grating. Holographic optical elements are usually recorded on a photosensitive medium deposited on to a glass substrate. Therefore, the study of the entire system, namely the holographic element plus the glass substrate, is necessary. In this work we study the entire system by using the rigorous coupled-wave theory. As will be demonstrated, the effect of the glass is to generate an oscillatory pattern of the efficiency of the different orders around the average. The effect of the glass substrate is therefore sufficiently significant, and care must be taken in order to choose the appropriate thickness of the glass if maximum diffraction efficiency is to be achieved.