Biphasic Structure Research Articles

Thermoelectric Properties of Solid Solutions PbSnAgTe

The phase composition and thermoelectric properties of solid solutions Pb16Sn2Ag2Te20 and Pb14Sn4Ag2Te20 are researched. Biphasic structure of the samples is installed, which providing to low values of thermal conductivity. Best samples have values of dimensionless thermoelectric figure of merit ZT ≈ 0,55.

Colossal dielectric constant and interfacial charge polarization in a polymer-derived amorphous silicon carbonitride

Abstract The dielectric properties of a polymer-derived amorphous silicon carbonitride were measured at different frequencies and temperatures. The results revealed that the material underwent an interfacial-charge polarization process. This process resulted in an S-shaped frequency dependence of the dielectric constant that reached a colossal value of 2 × 104 at room temperature. With regard to the effect of the temperature on the dielectric properties of this material, the dielectric loss peak corresponding to the interfacial-charge polarization process shifted to higher frequencies with temperature by following a 3-dimentional (3D) hopping mechanism. The unique bi-phased amorphous structure of this material accounted for the observed results.

Structural and catalytic stability assessment of Ni-La-Sn ternary mixed oxides for hydrogen production by steam reforming of ethanol.

NixLaSn trimetallic catalysts (x=5 and 15% by weight) were prepared by a coprecipitation technique by pH change and then calcined at 700°C, 850°C, 900°C and 950°C. XRD analysis of the fresh and unreduced catalysts showed the formation of crystalline phases corresponding to the pyrochlore structure La2Sn2O7 and NiO following calcination at 850°C, 900°C and 950°C. Ni3Sn and Ni3Sn2 compounds were formed under a pure hydrogen atmosphere and 650°C in the well crystallized catalyst containing the pyrochlore. This catalyst was highly active in the ethanol steam reforming reaction at 650°C, giving yield to gaseous mixtures containing hydrogen, carbon monoxide, carbon dioxide and methane. XRD analysis of the spent catalyst showed the presence of Ni3Sn2, Ni3Sn and the pyrochlore as unique phases after 80 hours of reaction time. After an initial decay, H2 yield kept stable until the end of the test. Carbon formation was observed by TEM, TG and elemental analysis. Lanthanum carbonates were also revealed by Raman spectroscopy. The highly stable biphasic structure containing Ni-Sn intermetallic compounds and the La2Sn2O7 could be the basis of catalysts for the production of H2-rich gaseous mixtures starting from bioethanol.

Microphase separation and crystallization behaviors of bi-phased triblock terpolymers with a competitively dissolved middle block

A series of poly(ε-caprolactone)-b-poly(n-butyl acrylate)-b-polystyrene (PCL-b-PnBA-b-PS) triblock terpolymers with fixed PCL and PnBA block lengths but different PS block lengths were prepared. In all of these triblock terpolymers the PnBA block can be competitively dissolved in both the PCL and PS phases to form bi-phase structures in the melt, as revealed by atomic force microscopy (AFM). Due to the “competitive dissolution effect” of the PnBA middle block, the microphase separation and crystallization behaviors of these triblock terpolymers are different from those of common diblock copolymers to some extent. As revealed by the Flory-Huggins parameters, more PnBA segments tend to dissolved in the PS phase. Therefore, the volume fraction of the PS-rich phase (fPS-rich) is evidently larger than the calculated volume fraction of the PS block (fPS), and the phase boundaries between two different structures shift to lower fPS. There also exists a thick interphase layer between the PS-rich and PCL-rich phases due to competitive dissolution of the PnBA block. However, confined crystallization can only occur at a larger fPS-rich, though the measured glass transition temperature (Tg) is high for the PS block. This can be attributed to a high fraction of the soft zone surrounding the PCL-rich phase and the lower volume fraction of the hard zone.

Dynamic instrumented palpation (DIP)—a new method for soft tissue quality assessment; application to engineered mechanical phantom materials

This paper presents a novel way of assessing the quality of biological tissue for diagnostic purposes, dynamic instrumented palpation. The method involves applying a controlled modulated strain or displacement to the tissue and measuring the resulting force as a function of time. The method is distinct from dynamic elastography in that the force and displacement are applied and measured by direct mechanical means at relatively low frequency (up to a few tens of Hz) and is more akin to a conventional mechanical test. The dynamic relationship between the force/stress and the strain/displacement is expressed as a function of frequency, this function being the measure to be correlated with tissue quality. The method is applied here to indentation of a set of engineered phantoms, intended to represent a controlled range of tissue quality, by altering the type and distribution of a harder and a softer phase. In the present work, the phantom tissues were engineered from natural and synthetic sponges impregnated with either silicone or gelatin, although the ultimate application is to human prostate, which can be considered as a biphasic structure (at least at the macro-scale), to distinguish between benign prostate disease and cancer. The work demonstrates that a range of frequencies can be used to yield a characteristic for the material which depends not only on the material type(s) but also on the morphology of the constituents. The method, therefore, shows good promise for application to the identification of multicomponent soft tissue make-up. As such, it is complementary to dynamic elastography, and its value lies in it being deployable in vivo as an adjunct during minimally invasive interventions. Future work will be aimed at establishing the capability of the method on human prostate tissue both in vitro and in vivo.

Electrodeposition of compact and porous Cu-Pd alloy layers and their application to nitrate reduction in alkali

Compact Cu-Pd alloys of compositions extending over the entire range are deposited at low overpotentials, from acidic sulphate/perchlorate baths of the two metal ions. XRD data show a lattice parameter following Vegard’s law. Porous alloy layers can be deposited from acidic chloride baths under large current densities causing vigorous hydrogen evolution. Good deposits with regular morphology are obtained only from Cu-rich baths, and for Pd contents up to ca 33 at%. XRD investigations indicate a biphasic structure, made of pure Cu and a Cu17Pd83 phase, in variable ratios depending on composition. Single phase porous Cu-Pd materials are obtained by prolonged galvanic displacement of porous Cu layers. Selected electrode materials are tested in the nitrate reduction in alkaline media, comparing the effects of composition and surface area.

Artificial and Biological Intelligence: Hardware vs Wetware

By starting from physical principles, the paper formulates the basis of the biological intelligence and coscience formation. The work shows that far from equilibrium, the principle of maximum energy dissipation, in a fluid phase, brings the molecules to organize themselves in living systems (ordered stationary states) that sustain energy-matter fluxes that determine the architecture of the dissipative system. The driver of the process is the energy; the matter is the substrate. On this base, and thanks to a “selection rule”, the living systems developed a bi-phasic structure consisting of a solid network permeated by a liquid where fluxes of ions and molecules can be maintained. In this way they realize a “wetware” where the energy and the organization/information are handled, and where a high specialization of functions can be obtained by using the spatial delocalization leading to the development of the complexity of the shape. The outputs of a living system can be divided in two categories: 1) macroscopic outputs: Movements, definition of an organized reaction or plan of action, and 2) microscopic ones: Plastic rearrangement of structures, migration of chemical species and electrochemical dynamics (transportation of matter, rearrangement, sensing, storage and information handling). The biological intelligence is a product of these basic processes where the wetware (matter substrate) is continuously modified by the energy-matter fluxes. On this base, the artificial intelligence of computers can be seen as a subclass of intelligent processes since it owns some limitations due to the invariance of the material substrate (that is not self-modified by the energy fluxes) and by the unique form of the flux of matter that is given by the electron current. Finally, the definition of a bio-inspired artificial intelligence is discussed.

Artificial and Biological Intelligence: Hardware vs Wetware

By starting from physical principles, the paper formulates the basis of the biological intelligence and coscience formation. The work shows that far from equilibrium, the principle of maximum energy dissipation, in a fluid phase, brings the molecules to organize themselves in living systems (ordered stationary states) that sustain energy-matter fluxes that determine the architecture of the dissipative system. The driver of the process is the energy; the matter is the substrate. On this base, and thanks to a “selection rule”, the living systems developed a bi-phasic structure consisting of a solid network permeated by a liquid where fluxes of ions and molecules can be maintained. In this way they realize a “wetware” where the energy and the organization/information are handled, and where a high specialization of functions can be obtained by using the spatial delocalization leading to the development of the complexity of the shape. The outputs of a living system can be divided in two categories: 1) macroscopic outputs: Movements, definition of an organized reaction or plan of action, and 2) microscopic ones: Plastic rearrangement of structures, migration of chemical species and electrochemical dynamics (transportation of matter, rearrangement, sensing, storage and information handling). The biological intelligence is a product of these basic processes where the wetware (matter substrate) is continuously modified by the energy-matter fluxes. On this base, the artificial intelligence of computers can be seen as a subclass of intelligent processes since it owns some limitations due to the invariance of the material substrate (that is not self-modified by the energy fluxes) and by the unique form of the flux of matter that is given by the electron current. Finally, the definition of a bio-inspired artificial intelligence is discussed.

Influence of reaction parameters for the enhanced photocatalytic hydrogen production using surface modified semiconductor Titania nanotubes

The physico-chemical properties of the photocatalyst and nature of reaction solution significantly influences the hydrogen (H2) production efficiency. The reaction parameters like Hydrogen ion concentration (pH) and nature of organic scavengers are aimed to amend the physico-chemical properties of catalyst that functions under natural solar light. CuO (1.5 wt %) loaded titania nanotubes (TNT) was used as a photocatalyst. The lower in the carbon chain length of alcohol (scavenger) and the alkaline reaction conditions are complimentary to each other for the superior rate of H2 production. The enhancement in H2 production is due to the effective interface reactions on the surface of the catalyst are more in number and the most suitable reduction potential of the conduction band of the photocatalyst for the ease of proton reduction. The 1.5 wt% CuO/TNT catalyst was well characterized for structural, morphological and surface elemental composition properties. Further biphasic anatase-rutile structure and one dimensional tubular morphology with +2 state of Cu deposited on the surface of TiO2 are responsible for high rate of gaseous H2 production.

Orthodontic archwire composition and phase analyses by neutron spectroscopy.

Quantitative metallurgical and phase analyses employing neutron diffraction technique were conducted on two as-received commercial rectangular austenitic stainless steel orthodontic archwires, G&H and Azdent, 0.43×0.64 mm (0.017×0.025 inch). Results showed a bi-phase structure containing martensitic phase (45.67% for G&H and 6.62% for Azdent) in addition to the expected metastable austenite. The former may be a strain-induced phase-transformation arising during the cold working process of wire fabrication. Further neutron resonance capture analysis determinations provided atomic and isotopic compositions, including alloying elements in each sample, complementary to the results of traditional energy dispersive X-ray spectroscopy. Together, these results assist in relating commercial alloying recipes and processing histories with mechanical performance, strength and ductility in particular.

Effect of Zr substitution on structural, magnetic, and optical properties of Bi0.9Dy0.1Fe1−xZrxO3 multiferroic ceramics prepared by rapid liquid phase sintering method

Zr substituted Bi0.9Dy0.1Fe1−xZrxO3 (x=0.03, 0.06 and 0.10) multiferroic ceramics were synthesized by rapid liquid phase sintering technique to improve its multiferroic properties. Rietveld structural refinement of XRD patterns and Raman spectra revealed a partial structural phase transition from rhombohedral (R3c) to biphasic structure (R3c+P4mm) on codoping. The substitution of larger ionic radii and higher valence Zr4+ ions at Fe-site leads to decrease in the grain size as a result of charge compensation at Fe site. The weak ferromagnetic behavior were observed in all samples along with maximum Mr value of 0.159emu/g for x=0.03 concentration, which is also endorsed by second order Raman modes. The distortion in FeO6 octahedra due to Zr substitution leads to splitting of electronic bands of 3.2eV into multiplets, which in turn reduced the optical band gap value in the range of 2.06–2.10eV for all samples.

Articular Cartilage Inspired Bilayer Tough Hydrogel Prepared by Interfacial Modulated Polymerization Showing Excellent Combination of High Load-Bearing and Low Friction Performance

Articular cartilage is a load-bearing and lubricious tissue covering the ends of articulating bones in synovial joints to reduce friction and wear. It ideally combines the high mechanical property and the ultralow friction performance as a result of biphasic structure and lubricious biomolecules. A biomimicking hydrogel with bilayer structure of thin porous top layer covering a compact and tough hydrogel bulk is fabricated with interfacial modulated polymerization. The top porous layer ensures the ultralow friction toward its contact pairs, while the bottom renders the high load-bearing property. Therefore, with bilayer architecture, hydrogel achieves an outstanding combination of low friction and high load bearing performance with long wear life when sliding against either steel or silicone elastomer counterpair.

Preparation and Thermoelectric Properties of Pb1–x Fe x Te Alloys Doped with Iodine

This is the first systematic report on the preparation and thermoelectric properties of n-type Pb1–xFexTe alloys. Iodine-doped n-type Pb0.85Fe0.15Te polycrystalline was prepared by melting and hot-pressing techniques. The morphology and phase structure of the prepared materials were analyzed by scanning electron microscopy and x-ray diffraction, which indicated that the samples possessed a rock-salt crystal structure and showed a biphase structure. The major phase was the polycrystalline PbTe compound and the second phase was the FeTe compound. The FeTe nano-/micro-precipitates were homogeneously distributed in the PbTe matrix, which is beneficial for the reduction of the lattice thermal conductivity. The effects of the iodine content on the thermoelectric properties of I-doped Pb0.85Fe0.15Te have been investigated. The measurement results of electrical resistivity, carrier concentration, Seebeck coefficient, and thermal conductivity in the temperature range of 300–850 K indicate that the thermoelectric transport properties of the obtained samples are sensitive to the iodine content. When the concentration of iodine is about 0.6 at.%, the maximum dimensionless figure-of-merit value of ∼0.65 at 800 K was obtained.

Distinct stages in stress granule assembly and disassembly.

Stress granules are non-membrane bound RNA-protein (RNP) assemblies that form when translation initiation is limited and contain a biphasic structure with stable core structures surrounded by a less concentrated shell. The order of assembly and disassembly of these two structures remains unknown. Time course analysis of granule assembly suggests that core formation is an early event in granule assembly. Stress granule disassembly is also a stepwise process with shell dissipation followed by core clearance. Perturbations that alter liquid-liquid phase separations (LLPS) driven by intrinsically disordered protein regions (IDR) of RNA binding proteins in vitro have the opposite effect on stress granule assembly in vivo. Taken together, these observations argue that stress granules assemble through a multistep process initiated by stable assembly of untranslated mRNPs into core structures, which could provide sufficient high local concentrations to allow for a localized LLPS driven by IDRs on RNA binding proteins.

Principal Component Analysis of the Longitudinal Carotid Wall Motion in Association with Vascular Stiffness: A Pilot Study

The longitudinal motion of the carotid wall during a heart cycle has a multiphasic waveform. Recent studies have examined the amplitude of this motion. Instead of amplitude measurements, we focus on making a detailed characterization of the motion waveform. Two-minute carotid ultrasound videos were obtained for 19 healthy volunteers, and a speckle tracking algorithm was used to measure the motion of the carotid wall. Principal component analysis revealed the characteristic features of wall motion and their relation to known arterial stiffness indices. By estimating two principal components, we could account for more than 92% of the variation in the motion graphs. The first principal component derived from the longitudinal motion curves was significantly correlated to pulse pressure, indicating that the main dominant base waveform of the longitudinal motion was related to blood pressure. The second principal component derived from the longitudinal motion curves had multiple significant correlations to known stiffness indices, indicating that the stronger biphasic structure of the motion curve, especially on the adventitia layer, was associated with higher distensibility and compliance, as well as reduced carotid artery stiffness. According to this study, the second principal component of the longitudinal motion may be a useful parameter reflecting vascular health.

Formation and characterization of Al–Ti–Nb alloys by electron-beam surface alloying

The combination of attractive mechanical properties, light weight and resistance to corrosion makes Ti-Al based alloys applicable in many industrial branches, like aircraft and automotive industries etc. It is known that the incorporation of Nb improves the high temperature performance and mechanical properties. In the present study on Al substrate Ti and Nb layers were deposited by DC (Direct Current) magnetron sputtering, followed by electron-beam alloying with scanning electron beam. It was chosen two speeds of the specimen motion during the alloying process: V1=0.5cm/s and V2=1cm/s. The alloying process was realized in circular sweep mode in order to maintain the melt pool further. The obtained results demonstrate a formation of (Ti,Nb)Al3 fractions randomly distributed in biphasic structure of intermetallic (Ti,Nb)Al3 particles, dispersed in α-Al solid solution. The evaluated (Ti,Nb)Al3 lattice parameters are independent of the speed of the specimen motion and therefore the alloying speed does not affect the lattice parameters and thus, does not form additional residual stresses, strains etc. It was found that lower velocity of the specimen motion during the alloying process develops more homogeneous structures. The metallographic analyses demonstrate a formation of surface alloys with very high hardness. Our results demonstrate maximal values of 775HV [kg/cm2] and average hardness of 673HV [kg/cm2].

Clinical-radiologic correlation of mixed epithelial and stromal tumor of the kidneys: Cases analysis

BackgroundMixed epithelial and stromal tumor of the kidney (MESTK) is a rare tumor, with few malignant cases reported. Occurring mostly in middle-aged women, it is characterized by a biphasic pathological structure. MethodsThis study retrospectively reviewed the imaging findings and medical records of six MESTK cases of a single institution in a 10-year period. ResultsAll of the patients were middle-aged women without hormone therapy history. The typical image was a renal tumor with varied cystic components. Half of the cases had sinus invagination, but only one had intratumor calcification. On imaging studies, four were Bosniak Category IV, one was Category III, and one presented as a solid tumor. The mean RENAL nephrometry score was 9.3. Five patients underwent partial nephrectomy, with no statistical renal functional deterioration after nephron-sparing surgery. There were no peri-operative complications. ConclusionSurgery remains the treatment of choice for MESTK, and nephron-sparing surgery should be considered in feasible cases.

Effect of (Sr0.7Ca0.3)TiO3-substitution on structure, dielectric, ferroelectric, and magnetic properties of BiFeO3 ceramics

Bi1−x(Sr0.7Ca0.3)xFe1−xTixO3 ceramics were prepared by a standard solid state reaction process, and the influence of Sr/Ca ratio on structure and properties for Bi1−x(Sr,Ca)xFe1−xTixO3 system was discussed by comparing with Sr0.5Ca0.5TiO3-modified BiFeO3 ceramics. Rietveld analysis of X-ray diffraction data revealed that the crystal structure changed from rhombohedral R3c (x ≤ 0.4) to orthorhombic Pnma (x = 0.6) with Sr0.7Ca0.3TiO3 substitution, and biphasic structure (R3c + Pnma) was determined at x = 0.5, while that for Bi1−x(Sr0.5Ca0.5)xFe1−xTixO3 system was at x = 0.4. This indicated that the morphotropic phase boundary in Bi1−x(Sr,Ca)xFe1−xTixO3 system shifted toward (Sr,Ca)TiO3 side with increasing Sr/Ca ratio. The Raman spectrometric analysis and selected area electron diffraction analysis also confirmed this transition. The dielectric relaxation could be well fitted by Arrhenius law, and the different activation energies were attributed to the different origins of the dielectric relaxations with increasing temperature. The current density-field (J-E) curves indicated that the leakage current was reduced to about five orders of magnitude with Sr0.7Ca0.3TiO3 substitution. The P-E hysteresis loops obtained by three different methods indicated the enhanced ferroelectricity at x = 0.4, and it could be attributed to the decrement of leakage current. Meanwhile, the magnetization was enhanced with Sr0.7Ca0.3TiO3 substitution, and the maximum remanent magnetization was determined at x = 0.2. The enhanced magnetization originated from the partial substitution of Fe3+ by Ti4+

Influence cutting parameters on the surface quality and corrosion behavior of Ti–6Al–4V alloy in synthetic body environment (SBF) using Response Surface Method

Most of the global manufacturing of titanium alloys is related to produce biphasic structures with grains alpha and beta. The development of modern applications of titanium alloy is a great challenge due to the chemical composition of Ti–6Al–4V alloy and the complexity of the manufacturing technology. This study proposed an optimal investigation of the variation of cutting speed, feed rate, and depth of cut in the turning of Ti–6Al–4V alloy on surface roughness, cutting efforts, and corrosion resistance. Response Surface Method has been established to optimize and model the responses mathematically. The adequacy of the models and a significant contribution of parameters were determined by analysis of variance (ANOVA). The biocompatibility of the machined surface for different cutting parameters was evaluated by the electrochemical polarization in simulated body fluids (SBF). Furthermore, desirability function analysis was used to determine the optimal values for surface quality, the turning force, and the passivation rate. It was clearly noticed that the multi-responses of the desirability function improved the machine process. The feed rate and depth of cut were the most relevant factors to minimize surface roughness and the turning forces. Moreover, the experimental results showed that the corrosion behavior was strongly related to minimal surface roughness. Finally, the optimization reduced the surface roughness Ra and Rz in 5.5% and 11.9%, respectively and increased the corrosion resistance in 18.8%.

Optimization of Heat Treatments for Reversion of Strain-Induced Martensite in 304L SS Explosive Clad

Explosive clad joints of 304L SS and Ti-5Ta-2Nb alloy, fabricated for an important application in the spent nuclear fuel reprocessing industry showed formation of deformation induced metastable α′ martensite and fcc Ti phase in SS and TiTaNb alloy respectively. A biphasic structure consisting of metastable phases is not preferred for industrial applications due to degradation of corrosion and mechanical properties of the structural materials during service. Hence, it is essential to carry out post cladding heat treatments. The results reported in this paper provide evidence for the presence of α′ phase in 304L SS in ‘as clad’ joints and its reversion process during thermal exposure. The temperature window in the range of 400-700 °C and time was optimized based on complete transformation of the metastable phases to parent phases, and avoiding the formation of brittle Fe-Ti intermetallics at the interface. A systematic increase in the fraction of austenite phase associated with the reversion phenomena has been studied using electron back scattered diffraction and transmission electron microscopy. Orientation relationship between product fcc and parent bcc phases was found to obey the K-S relationship. The reverted γ phase was found to nucleate within the martensite laths. A temperature of 550 °C for duration of about 10 h was found to be optimum for the post cladding treatments of the explosive clad joints.