Superfocusing of channeled protons and crystal rainbows

This study is devoted to the effect of superfocusing of protons having the energy of 2 MeV in a 〈1 0 0〉 channel of a Si crystal. The analysis is performed by the theory of crystal rainbows. We analyze the superfocusing effect in the first rainbow cycle. The evolution of the spatial distribution of channeled protons is examined by the numerical solution of the proton equations of motion in the transverse position plane. We demonstrate that the superfocusing effect is a reduced crystal rainbow effect, in which the rainbow line comes to a point.     

Laser-induced surface oxidation of (Ni/Ti)/Si system with picosecond laser pulses

The surface oxidation of Ni/Ti bilayer, deposited on silicon substrate, affected by picosecond Nd: YAG laser radiation has been investigated. Fluence close to the target ablation threshold and multi-pulse laser irradiation regime were applied. Changes in the chemical composition of the formed surface oxide layer were studied by Elastic Recoil Detection Analysis (ERDA) and X-ray photoelectron spectroscopy (XPS). Morphological features analysis, at the oxide surface layer, was monitored, too. Laser modification as-deposited (Ni/Ti)/Si sample with 10 pulses induces a progressed interaction between Ni and Ti layers with the initial surface oxidation and formation of NiTi alloy phase. Progressed intermixing of components was achieved for the irradiation with 50 and more pulses, when all components were quite uniformly distributed to a depth of about 80 nm. An oxide layer was formed at the surface, with the specific combination of the oxide phases depending on the number of accumulated pulses. Changes in the morphological characteristics are reflected in the increase of the mean surface roughness and the generation of a certain number of cavities. These features are decreased with increasing number of pulses, caused by the surface melting and a pronounced mobility of the materials.     

Thermoplastic polyurethanes with isosorbide chain extender

Isosorbide, a renewable diol derived from starch, was used alone or in combination with butane diol (BD) as the chain extender in two series of thermoplastic polyurethanes (TPU) with 50 and 70% polytetramethylene ether glycol (PTMEG) soft segment concentration (SSC), respectively. In the synthesized TPUs, the hard segment composition was systematically varied in both series following BD/isosorbide molar ratios of 100 : 0; 75 : 25; 50 : 50; 25 : 75, and 0 : 100 to examine in detail the effect of chain extenders on properties of segmented polyurethane elastomers with different morphologies. We found that polyurethanes with 50% SSC were hard elastomers with Shore D hardness of around 50, which is consistent with assumed co‐continuous morphology. Polymers with 70% SSC displayed lower Shore A hardness of 74–79 (Shore D around 25) as a result of globular hard domains dispersed in the soft matrix. Insertion of isosorbide increased rigidity, melting point and glass transition temperature of hard segments and tensile strength of elastomers with 50% SSC. These effects were weaker or non‐existent in 70% SSC series due to the short hard segments and low content of isosorbide. We also found that the thermal stability was lowered by increasing isosorbide content in both series. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42830.     

Anti-Inflammatory Effect of Allicin Associated with Fibrosis in Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is characterized by pulmonary vascular remodeling. Recent evidence supports that inflammation plays a key role in triggering and maintaining pulmonary vascular remodeling. Recent studies have shown that garlic extract has protective effects in PAH, but the precise role of allicin, a compound derived from garlic, is unknown. Thus, we used allicin to evaluate its effects on inflammation and fibrosis in PAH. Male Wistar rats were divided into three groups: control (CON), monocrotaline (60 mg/kg) (MCT), and MCT plus allicin (16 mg/kg/oral gavage) (MCT + A). Right ventricle (RV) hypertrophy and pulmonary arterial medial wall thickness were determined. IL-1β, IL-6, TNF-α, NFκB p65, Iκβ, TGF-β, and α-SMA were determined by Western blot analysis. In addition, TNF-α and TGF-β were determined by immunohistochemistry, and miR-21-5p and mRNA expressions of Cd68, Bmpr2, and Smad5 were determined by RT-qPCR. Results: Allicin prevented increases in vessel wall thickness due to TNF-α, IL-6, IL-1β, and Cd68 in the lung. In addition, TGF-β, α-SMA, and fibrosis were lower in the MCT + A group compared with the MCT group. In the RV, allicin prevented increases in TNF-α, IL-6, and TGF-β. These observations suggest that, through the modulation of proinflammatory and profibrotic markers in the lung and heart, allicin delays the progression of PAH.     

A longitudinal study of immunologic reactivity in leprosy patients treated with immunotherapy

More than 150 leprosy patients treated with multidrug therapy (MDT) plus immunotherapy (IMT) with a mixture of heat-killed Mycobacterium leprae plus live BCG were studied in relation to humoral and cell-mediated immune responses. Many previously had received prolonged sulfone monotherapy. Patients received 2 to 10 doses of IMT in a period of 1 to 3 years, depending upon their clinical form of leprosy. The patients were followed up for 5 to 10 years with repeated determinations of antibody levels to phenolic glycolipid-I; lymphoproliferative (LTT) responses to soluble extract of M. leprae, to whole bacilli and to BCG, skin-test responses and bacterial indexes (BIs). After MDT plus IMT there was a statistically significant decrease of antibody levels in the multibacillary (MB) group. The BI decreased proportionally to the ELISA results. LTT increased to M. leprae antigens, especially to soluble extract, in a high percentage of these patients (34% of LL patients positive). Lepromin positivity in MB patients increased from 5% initially positive to 75% at the cut-off during this follow up. These results show substantial early and persistent cell-mediated reactivity to M. leprae in many MB patients treated with MDT-IMT, confirming and expanding previously published data.     

Antimony doping effect on barium titanate structure and electrical properties

Nanopowders of pure and antimony doped barium titanate (BaTiO₃-BT) were synthesized by polymeric precursors method based on Pechini process. Obtained powders were pressed and sintered at 1300 °C for 8 h. XRD analysis showed the formation of cubic crystal structure in all nanopowders and tetragonal in BT ceramics. The influence of antimony concentration on structure change, grain size reduction and microstructure development was analyzed. Dielectric behavior of pure and antimony doped ceramics was studied as a function of temperature and frequency. The significant dielectric properties modification as a consequence of doping with different antimony concentration was noticed. The electrical resistivity measurements pointed out that antimony concentration influenced also on materials change from insulator to semiconductor.     

PZT-nickel ferrite and PZT-cobalt ferrite comparative study: Structural,dielectric, ferroelectric and magnetic properties of composite ceramics

Comparative study of different PZT-based composite materials ((x)PbZr_0.52Ti_0.48O₃ + (1-x)CoFe₂O₄ and (x)PbZr_0.52Ti_0.48O₃ +(1-x)Ni_0.7Zn_0.3Fe₂O₄ (x = 0.8 and 0.9)) is presented in the frame of structural, dielectric, ferroelectric and magnetic properties. PZT and NZF/CF powders were synthesized by auto combustion technique. The composites were synthesized by mixing the appropriate amount of individual phases using conventional sintering. XRD data indicated the formation of well crystallized structure of PZT and NZF/CF, without the presence of undesirable phases. SEM micrographs revealed a uniform grain distribution of both, ferroelectric and ferromagnetic phases. Non-saturated hysteresis loops are evident in all samples due to the existence of non-ferroelectric ferrite phase. All the samples exhibit typical ferromagnetic hysteresis loop, indicating the presence of the order magnetic structure. Dielectric investigations revealed that ferrites are the main source of charge carriers, which must be of electronic origin. The activation energy of effective electrical resistivity is heavily influenced by the ferroelectric phase.     

Composite nanostructured hydroxyapatite/yttrium stabilized zirconia dental inserts – The processing and application as dentin substitutes

The objective of the study was to process nano-structured hydroxyapatite/yttrium-stabilized zirconia bioceramic and to investigate the possibilities of its application as dentin replacement in the form of dental inserts. The processing conditions were varied in order to optimize phase composition, microstructure, fracture toughness, hardness and shear bond strength (SBS) between the obtained composite inserts and restorative materials, following either the "total-etch" or ?self-etch“ clinical protocol. Composite nano-powder, obtained by mixing and homogenization of 80?wt% of stoichiometric hydroxyapatite (HAp) synthesized by modified precipitation method and 20?wt% of yttrium-stabilized ZrO₂ (YSZ) synthesized by plasma method, was isostatically pressed into cylinder-shaped green bodies. After dilatometric analysis, HAp/YSZ inserts were sintered in the temperature range from 1200?°C to 1300?°C. Hardness and fracture toughness of sintered inserts were ranged between 3.90?±?0.20 – 3.95?±?0.12?GPa and 1.82?±?0.04 – 1.88?±?0.03 MPam^1/2, respectively. Microstructural analysis of biphasic HAp/t-ZrO₂ inserts indicated two potential fracture mechanisms for fracture toughness increasing. Sintering temperature and different clinical protocols affected SBS between processed inserts and commercial dental restorative materials. Maximum SBS values of 10.50?±?4.94?MPa (mean±standard deviation) were reached in inserts sintered at 1300?°C, following the ?self-etch“ protocol of adhesive application. It could be concluded that resin-based composites could be strongly bonded to HAp/YSZ inserts, preferably with ?self-etch“ adhesive application. In addition, the values of fracture toughness and hardness of the obtained inserts indicated the possibility of their usage as dentin substitutes, which could be a good prerequisite for satisfactory mechanics of restored teeth.