Effect of Fe Substitution on the Structural,Magnetic and Magnetocaloric Properties of Pr0.6La0.1Mg0.3Mn1−x Fe x O3 (0≤x≤0.3) Perovskite Manganites Prepared by Sol Gel Method

Studies of the structural, magnetic, and magnetocaloric properties of polycrystalline Pr_0.6La_0.1Mg_0.3Mn_1?x Fe _x O₃ (0≤x≤0.3) perovskite manganites were carried out. The compounds were synthesized using the sol–gel method. X-Ray diffraction (XRD) analysis using Rietveld refinement shows that all our compounds crystallize in the orthorhombic structure with the Pnma space group. The surface morphology and elemental analysis of both samples were carried out by scanning electron microscopy (SEM) and the energy dispersive X-ray technique (EDX), respectively. Magnetization measurements versus temperature under magnetic applied field of 0.05 T showed that all our investigated samples display a ferromagnetic-paramagnetic transition. The substitution of Mn by Fe leads to an increase of the Curie temperature T _C from 64 K for x=0 to 380 K for x=0.3. The Arrott plots show that the phase transition is of second order. A large magnetic entropy change |ΔS _M | deduced from isothermal magnetization curves has been recorded in the parent compound Pr_0.6La_0.1Mg_0.3MnO₃ reaching a maximum of 0.79 J/kg K under a magnetic applied field of 2 T close to T _C . Our results on magnetocaloric properties suggest that the Pr_0.6La_0.1Mg_0.3MnO₃ compound is attractive as a possible refrigerant for low temperature magnetic refrigeration.     

Ultrasonic cavitation test applied to thin metallic films for assessing their adhesion with mercaptosilanes and surface roughness

Evaluating the adhesion of micrometer or nanometer thick coatings is a challenging question which concerns many application fields. This is especially true for thin films deposited on a substrate of elastic modulus higher than that of the film, or for granular coatings, that do not allow the use of common adhesion tests. Usually, applied to characterize the wear resistance of bulk materials or thick coatings, the ultrasonic cavitation test is applied here to evaluate the adhesion strength of gold and copper thin films (~200 nm) that are evaporated on a silicon substrate. The test is shown to be sensitive enough to discriminate the influence of the surface chemistry on the adhesion strength of gold and copper films. Particularly, the role of (3-mercaptopropyl)triethoxysilane as an effective adhesion promotor is demonstrated. Furthermore, the role of surface roughness of the substrate is characterized and discussed in order to get further insights on the way this parameter interferes with the ultrasonic test and determines the adhesive strength of the coating. An estimate of the adhesive strength is given on the basis of the coating delamination kinetics.     

Electrical properties of magnesium sodium hydrogen monophosphate: MgNa3H(PO4)2

Magnesium sodium hydrogen monophosphate, Na₃MgH(PO₄)₂, crystallizes in the triclinic cell . The crystal morphology is related to the synthesis temperature and the evaporation rate. Samples were characterized through X-ray diffraction and chemical analysis, examined by IR and Raman vibrational spectroscopy and impedance and modulus spectroscopy techniques. The conductivity relaxation parameters associated with some H^· conduction have been determined from an analysis of the M^″/M_max^″ spectrum measured in a wide temperature range. Transport properties in this material appear to be due to an H^· ion hopping mechanism.     

Fetal hydrocolpos

This work studies the role that nitric oxide (NO) plays in ischemia/reperfusion (I/R) of the rat kidney. Sprague-Dawley rats, weighing 250-300 g, were subjected to 75 min of warm ischemia and contralateral nephrectomy. The animals were divided into six groups (n = 12 per group): ischemic control (IC) with normal saline, L-NG-mono-methyl-arginine (L-NMMA) 50 mg/kg, L-arginine (L-Arg) 300 mg/kg, Na-nitroprusside (Na-NP) 2.5 mg/kg, the combination of L-NMMA+Na-NP at the doses used before, and the sham group. All animals received the drug intravenously 60 min prior to ischemia. Survival was evaluated at seven days. Renal damage was assessed by kidney function tests (serum creatinine and blood urea nitrogen) and light histology. Lipid peroxidation was measured in renal tissue using the thiobarbituric acid assay. Significantly better survival was seen in the Na-NP group, as compared to the rest of the study. Serum creatinine at 24 and 48 hr showed a significant difference between the Na-NP group and the other groups. Histological damage was minimal in the Na-NP group. Clearly, the Na-NP had the most beneficial effect in survival and histological structure. Lipid peroxidation was significantly different, with the lower levels seen in the L-NMMA group and the higher levels in the Na-NP group. In base to these results, we conclude that exogenous NO has a beneficial and protective effect of the ischemically damaged rat kidney. This protection is independent of lipid peroxidation. Endogenous NO production does not play a role in I/R injury in our model.     

Importance of in-plane shear rigidity in finite element analyses of woven fabric composite preforming

A finite element made of woven unit cells under biaxial tension and in-plane shear is proposed for the simulation of fabric forming. The simulation is made within an explicit dynamic approach and is based on a simplified dynamic equation accounting for tension and in-plane shear strain energy. The biaxial tensile properties (given by two surfaces) and the in-plane shear properties (given by a curve) can be determined both by biaxial tensile tests and picture frame experiments or obtained by mesoscopic 3D finite element analyses of the woven unit cell. The interior load components of the proposed finite element are calculated explicitly and simply from the tensions and shear torque on four woven cells. The results obtained by the simulations of a hemispherical forming process on a very unbalanced fabric are compared to experiments. It is shown that the tension strain energy permits to describe the asymmetry of the response but that the computation of wrinkles and of the deformed states when the locking angle is exceeded needs to take the in-plane shear stiffness and its evolution with shear angle into account.     

Whey Powder, ι-Carrageenan,and Fat Interactions and Their Influence on Instrumental Texture and Sensory Properties of Turkey Meat Sausage Using a Mixture Design Approach

A 10-point simplex lattice design was used to investigate the effect of varying the ratios of whey powder, ι-carrageenan, and fat, and their interactions on instrumental texture and sensory properties of mechanically separated turkey meat sausages. Regression models have been developed and contour plots were drawn in order to better understand the global tendency of measured responses. Whey powder had a more notable influence than that of ι-carrageenan on all textural parameters as whey powder proportion increased. At a higher proportion (8 g/100 g sausage), whey powder improved essentially hardness, gel stress, and chewiness of extra low-fat sausage (formulation 3, 4.2 ± 0.3 g of fat/100 g sausage). Environmental scanning electron microscopy of the corresponding sausage showed a compact microstructure characterized by large network connections. Sensory evaluation also indicated that whey powder increased the flavor, the firmness, and the sliceability scores of mechanically separated turkey meat sausage, in comparison to the high-fat standard sausage (formulation 1, 13.2 ± 0.2 g of fat/100 g sausage).     

Production of free standing composite membranes or of patterned films after sol–gel reactions in an exponential layer-by-layer architecture

This paper aims at describing that polyelectrolyte multilayer (PEM) films, made of biocompatible molecules, Hyaluronic acid (HA) and Poly(6-lysine) (PLL), can entrap negatively charged precursors of titania or silica. These precursors undergo hydrolysis and polycondensation in contact with the amino groups of PLL leading to the formation of oxides (TiO₂ or SiO₂) within the films. Moreover, this work shows that these composite thin films, a few μm thick, can be easily detached as free standing membranes containing photoactive TiO₂. To this aim the PEM film containing TiO₂ was thermally cross-linked to form amide bonds. Immersion of the film in diluted hydrofluoric acid (2% (v/v)) allowed then the formation of a free standing membrane. We extend the concept of sol–gel reaction in PEM films to films made from poly(L-glutamic acid) (PGA) and Poly(allylamine) (PAH) and show that the composition of the multilayer film influences the distribution of the inorganic material in the films: the TiO₂ distribution seems homogeneous in (PLL–HA)_n films whereas the (PAH–PGA)_n films are self patterned with inorganic aggregates tens of micrometers in diameter. The free standing membranes or self patterned composite films obtained in this investigation may present interesting bio-applications.     

Speak-Correct: A Computerized Interface for the Analysis of Mispronounced Errors

Any natural language may have dozens of accents. Even though the equivalent phonemic formation of the word, if it is properly called in different accents, humans do have audio signals that are distinct from one another. Among the most common issues with speech, the processing is discrepancies in pronunciation, accent, and enunciation. This research study examines the issues of detecting, fixing, and summarising accent defects of average Arabic individuals in English-speaking speech. The article then discusses the key approaches and structure that will be utilized to address both accent flaws and pronunciation issues. The proposed SpeakCorrect computerized interface employs a cutting-edge speech recognition system and analyses pronunciation errors with a speech decoder. As a result, some of the most essential types of changes in pronunciation that are significant for speech recognition are performed, and accent defects defining such differences are presented. Consequently, the suggested technique increases the Speaker’s accuracy. SpeakCorrect uses 100 h of phonetically prepared individuals to construct a pronunciation instruction repository. These prerecorded sets are used to train Hidden Markov Models (HMM) as well as weighted graph systems. Their speeches are quite clear and might be considered natural. The proposed interface is optimized for use with an integrated phonetic pronounced dataset, as well as for analyzing and identifying speech faults in Saudi and Egyptian dialects. The proposed interface detects, analyses, and assists English learners in correcting utterance faults, overcoming problems, and improving their pronunciations.