Broad Phase Research Articles

Ferromagnetic ordering along the hard axis in the Kondo lattice YbIr3Ge7

Ferromagnetic Kondo lattice compounds are far less common than their antiferromagnetic analogs. In this work, we report the discovery of a new ferromagnetic Kondo lattice compound, YbIr3Ge7. Like almost all ferromagnetic Kondo lattice systems, YbIr3Ge7 shows magnetic order with moments aligned orthogonal to the crystal electric field (CEF) easy axis. YbIr3Ge7 is unique in that it is the only member of this class of compounds that crystallizes in a rhombohedral structure with a trigonal point symmetry of the magnetic site, and it lacks broken inversion symmetry at the local moment site. AC magnetic susceptibility, magnetization, and specific heat measurements show that YbIr3Ge7 has a Kondo temperature TK = 14 K and a Curie temperature TC = 2.4 K. Ferromagnetic order occurs along the crystallographic [100] hard CEF axis despite the large CEF anisotropy of the ground state Kramers doublet with a saturation moment along [001] almost four times larger than the one along [100]. This implies that a mechanism which considers the anisotropy in the exchange interaction to explain the hard axis ordering is unlikely. On the other hand, the broad second-order phase transition at TC favors a fluctuation-induced mechanism.

Afirmação de políticas educativas de âmbito municipal num território regionalizado: o caso da Região Autónoma da Madeira

O Estado português pretende iniciar uma nova fase, mais abrangente no relacionamento com os Municípios, alargando o leque de competências a transferir no setor da educação. Portugal é, no entanto, um Estado unitário regionalizado. Qualquer iniciativa, neste âmbito, não pode perder de vista as atribuições das regiões autónomas portuguesas. No caso, da Madeira e da Educação, o processo de ampliação de competências municipais, não pode deixar de considerar as competências regionais já existentes. O alargamento competencial para os municípios da Madeira, tudo terá a ganhar se for conduzido mediante políticas bottom-up pela interação com os atores locais, em lugar de top-down, em que a desconfiança conduzirá à redução das dinâmicas de autonomia e à descaraterização da qualidade do serviço educativo.Palavras-chave: administração educacional; autonomia regional; descentralização; municipalização; regionalização e políticas educativas regionais.

A V-Band Power Amplifier With Integrated Wilkinson Power Dividers-Combiners and Transformers in 0.18-$\mu$ m SiGe BiCMOS

A high output power fully integrated V-band power amplifier (PA) is developed using a 0.18- $ {\mu }\text{m}$ SiGe BiCMOS technology. The developed PA makes use of four-way parallel power dividing and combining structures to feed and combine powers from four identical unit-PA cells, respectively. Especially, the parallel power combiner and divider are developed by integrating a low-loss wideband Wilkinson structure and two transformers connected in parallel, which achieve broad bandwidth and minimum phase and amplitude mismatches between ports. The unit-PA is designed as a pseudo-differential two-stage cascode amplifier, which employ transformers for both matching and impedance transformation. The PA achieves measured broadband small-signal gain of 19 dB at 60 GHz and 3-dB bandwidth of 56.8–67.5 GHz, which encompasses the overall unlicensed V-band spectrum (57–64 GHz). In addition, it delivers 18.8 dBm of saturated output power and 15.3 dBm of output 1-dB compressed power at 60 GHz. Across 55 to 65 GHz, the PA achieves a very flat power performance with maximum output power between 17–19.1 dBm.

Thermomagnetic properties and magnetocaloric effect of FeCoNiCrAl-type high-entropy alloys

In this work, we investigate the effects of substituting Ni/Al for Cr on the thermomagnetic and magnetocaloric properties of FeCoNiCrAl-type high entropy alloys (HEAs). Ni and Al appear to prefer the BCC phase, and increases in the Al composition appear to stabilize the BCC phase. In contrast to Al, Ni content yields an increase in the FCC phase fraction, resulting in a drop off in magnetization. The phase transformation from BCC to FCC was intensified at annealing temperatures of 800 °C and higher due to increased diffusion rates and the resulting spinodal decomposition. A magnetic phase transition around 150 K was found in the FeCoNi1.5Cr0.5Al annealed alloy potentially corresponding to the FCC phase, and a very broad magnetic phase transition was observed in the annealed FeCoNiCrAl alloy, resulting in a high refrigerant capacity of RCFWHM = 242.6 J⋅kg-1 near room temperature. A peak magnetic entropy change of −ΔSM = 0.674 J⋅kg-1⋅K-1 was also obtained at applied fields of ∼70 kOe at 290 K in the FeCoNiCrAl HEA. These magnetocaloric values are comparable to Fe-based metallic glasses such as Fe-Tm-B-Nb and Fe-Zr-B-Co alloys, with a similar transition near room temperature.

Improvement of Energy Storage Characteristics of (Ba0.7Ca0.3)TiO3 Thick Films by the Increase of Electric Breakdown Strength from Nano-Sized Grains

Lead free (Ba0.7Ca0.3) TiO3 thick films with nano-sized grains are prepared using an aerosol deposition (AD) method at room temperature. The crystallinity of the AD thick films is enhanced by a post annealing process. Contrary to the sharp phase transition of bulk ceramics that has been reported, AD films show broad phase transition behaviors due to the nanosized grains. The polarization-electric hysteresis loop of annealed AD film shows ferroelectric behaviors. With an increase in annealing temperature, the saturation polarization increases because of an increase in crystallinity. However, the remnant polarization and cohesive field are not affected by the annealing temperature. BCT AD thick films annealed at 700 °C/2h have an energy density of 1.84 J/cm3 and a charge-discharge efficiency of 69.9%, which is much higher than those of bulk ceramic with the same composition. The higher energy storage properties are likely due to the increase in the breakdown field from a large number of grain boundaries of nano-sized grains.

Double orthogonal phase stubs technique for Minkowski fractal reflectarray antenna

ABSTRACTWe propose a unit cell consisting of Minkowski fractal with double stubs to attain a broad phase range for the reflectarray antenna. In this study, single stub for Minkowski fractal and double stubs with orthogonal symmetry are simulated using HFSS™ program with Floquet Port incidence. It is observed that the single stub causes higher cross polarization level compared to the double orthogonal stubs. Simulation results are supported by the experimental data obtained from the measurements using waveguide setup. As a result, a broad phase response, better reflection loss, and 10.9% shrinkage in patch size are obtained using double stubs with orthogonal symmetry. Subsequently, the proposed unit cell is used to design and fabricate a full-scale 221 element reflectarray antenna, which may be used, particularly, in aeronautical and space applications. At 10 GHz, simulation results are compared with the measured data, and good agreement is observed.

Understanding the Role of Ferroelastic Domains on the Pyroelectric and Electrocaloric Effects in Ferroelectric Thin Films.

Temperature- and electric-field-induced structural transitions in a polydomain ferroelectric can have profound effects on its electrothermal susceptibilities. Here, the role of such ferroelastic domains on the pyroelectric and electrocaloric response is experimentally investigated in thin films of the tetragonal ferroelectric PbZr0.2 Ti0.8 O3 . By utilizing epitaxial strain, a rich set of ferroelastic polydomain states spanning a broad thermodynamic phase space are stabilized. Using temperature-dependent scanning-probe microscopy, X-ray diffraction, and high-frequency phase-sensitive pyroelectric measurements, the propensity of domains to reconfigure under a temperature perturbation is quantitatively studied. In turn, the "extrinsic" contributions to pyroelectricity exclusively due to changes between the ferroelastic domain population is elucidated as a function of epitaxial strain. Further, using highly sensitive thin-film resistive thermometry, direct electrocaloric temperature changes are measured on these polydomain thin films for the first time. The results demonstrate that temperature- and electric-field-driven domain interconversion under compressive strain diminish both the pyroelectric and the electrocaloric effects, while both these susceptibilities are enhanced due to the exact-opposite effect from the extrinsic contributions under tensile strain.

Dielectric and piezoelectric properties of Sm3+ doped lead barium niobate (PBN) ceramics

Rhombohedral samarium doped Lead based ceramic materials were fabricated by a high temperature conventional solid state mixed oxide ceramic process. The ceramic composition Pb1-x-3y/2BaxRey3+ Nb2O6 (x = 0.35 and y = 0.00, 0.02, 0.04 and 0.06, Re3+ = Sm3+). The pure and Sm3+ doped lead barium niobate ceramic materials are single phase with rhombohedral(hexagonal) symmetry obtained from powder x-ray diffraction (XRD). The grain size has been measured for all the compositions and lying between 1.60 and 2.90 μm. Broad dielectric peak phase transitions observed with temperature in pure and Sm3+ ion modified lead barium niobate ceramic materials. It is observed that the high values of piezoelectric charge coefficients in d31 and d33 in Sm3+ doped lead barium niobate ceramics. The mechanical quality factor Qm and d33 increases with increase of Sm3+ ion concentration and indicating a highly polarisable lead ion contributing to high Curie temperature dielectric constant.

Interpenetrating thermophobic and thermophilic dual responsive networks

ABSTRACTPoly(N‐acryloyl glycinamide) (PNAGA)/poly(N‐isopropyl acrylamide) (PNIPAAm) interpenetrating network (IPN) hydrogels were made by UV‐light initiated radical polymerization in two‐steps. The IPN hydrogels showed a double thermoresponsive behavior due to the combination of PNIPAAm (thermophobic) and PNAGA (thermophilic) networks. Increasing the content of the thermophobic PNIPAAm network leads to a change from a broad thermophilic volume phase transition temperature of PNAGA to a thermophilic–thermophobic‐type dual transition for the prepared IPN. Due to the double thermoresponsive character of the IPN gels, the mechanical properties are dependent upon temperature as demonstrated by performing tensile tests in water at 15 and 50 °C. Furthermore, the IPN hydrogels were characterized using turbidity measurements, SEM, and the determination of the equilibrium swelling ratio. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 539–544

Composition‐driven broad phase boundary for optimizing properties and stability in lead‐free barium titanate ceramics

AbstractA new piezoelectric system of (1−x−y)BaTiO3‐yCaZrO3‐xBaSnO3 (BT‐yCZ‐xBS) was designed to achieve enhanced piezoelectric/strain properties and temperature stability. First, the relationships between composition, phase, and electrical properties are systematically investigated. The broad phase boundary with successive rhombohedral‐orthorhombic (R‐O) and orthorhombic‐tetragonal (O‐T) was obtained in 0.04 ≤ x ≤ 0.05 and 0.04 ≤ y ≤ 0.07 by tailoring the relationship of composition and phase structure, confirmed by X‐ray diffraction, temperature‐dependent dielectric constants, and Raman spectra. The optimized piezoelectric coefficient of d33 = 560 pC/N, high strain of >0.20%, and large converse piezoelectric coefficient of d33* = 1170 pm/V were realized. Second, the optimized piezoelectricity both demonstrate a stable performance with fluctuation <8% for d33* and 20% for d33 between 22 and 60°C since the broad phase boundary is exhibited in this temperature range. We believe that this work is a successful example to optimize piezoelectric properties and enhance the stability for piezoceramics.

Combined interpretation of NMR, MICP, and SIP measurements on mud-dominated and grain-dominated carbonate rocks

Carbonate formations still present a challenging target with regard to reservoir characterization as they possess a wide range of pore types and sizes as well as interconnected and isolated pore space. In this study a set of micritic and oomoldic carbonate samples was investigated with three measurement techniques (magnetic resonance (NMR), mercury intrusion (MICP), and spectral induced polarization (SIP, in a frequency range from 5mHz to 100 Hz)) which provide information about a rock's pore space indirectly based on different physical principles. The aims of the study were to combine these pieces of information to characterize the pore space of mud-dominated and grain-dominated carbonate rocks and to investigate potential correlations between pore space properties and SIP-derived parameters.Pore body and pore throat size distributions were derived from NMR and MICP data, respectively, and interpreted in terms of dominant pore throat (rt) radius, pore body (rb) radius and the rb/rt ratio. For validation of the NMR-derivedrb distributions, scanning electron microscope images were used for the computation of image-derived pore size distributions. The SIP data were interpreted in terms of characteristic features for oomoldic and micritic samples. Phase shift, real (σ′) and imaginary part (σ′′) of complex conductivity, respectively, were fitted with Cole-Cole models and the characteristic parameters relaxation time τ, chargeability m, and frequency dependence c were derived for each sample. Subsequently, these parameters were interpreted with regard to correlations with rb,rt, and rb/rt and specific surface Spor.The results indicate that grain-dominated carbonates possess comparatively large radii rb and rtand low Spor, which seems to go along with sharp phase peaks (i.e. high c values) and a low absolute phase level (and therefore low chargeability m). The mud-dominated carbonates, in contrast, possess relatively small radii rb and rt and high Spor which is obviously associated with broad phase peaks (i.e. low c values) and a comparatively high phase level resulting in high m values. τ, in contrast, was found to decrease with increasing ratio rb/rt and may therefore have similar values in both micritic and oomoldic samples. Consequently, the results of this study contribute to a better understanding of the petrophysical properties of carbonate rocks as a function of their pore space characteristics.

Synthesis, structural, magnetic and magnetocaloric properties of La0.8Sr0.2MnO3 nanoparticles

In this work, we reported a detailed study on the synthesis, structural and magnetic properties of nanocrystalline La0.8Sr0.2MnO3. The synthesized nanoparticles were prepared using a sol–gel method and characterized using X-ray diffraction and high-resolution transmission electron microscope. The average particle size was found in the range from 40 to 45 nm. The magnetization versus temperature M(T) measurements as well as magnetization field dependence M(H) have been investigated using vibrating-sample magnetometer. The magnetization as a function of temperature M(T) indicated a broad second-order magnetic phase transition from ferromagnetic state to paramagnetic state in the Curie temperature region (320–340 K). The magnetocaloric effect of the sample has been estimated and presented a maximum magnetic entropy change |ΔSM|max = 0.86 J kg−1 K−1 with relative cooling power = 62.12 J kg−1 at magnetic field (H) = 2T. Based on the result of magnetocaloric properties, the investigated sample could be considered as a good refrigerant material for near room temperature magnetic refrigeration.

Flexible Use of Temporal and Spatial Reasoning for Fast and Scalable CPU Broad‐Phase Collision Detection Using KD‐Trees

AbstractRealistic computer simulations of physical elements such as rigid and deformable bodies, particles and fractures are commonplace in the modern world. In these simulations, the broad‐phase collision detection plays an important role in ensuring that simulations can scale with the number of objects. In these applications, several degrees of motion coherency, distinct spatial distributions and different types of objects exist; however, few attempts have been made at a generally applicable solution for their broad phase. In this regard, this work presents a novel broad‐phase collision detection algorithm based upon a hybrid SIMD optimized KD‐Tree and sweep‐and‐prune, aimed at general applicability. Our solution is optimized for several objects distributions, degrees of motion coherence and varying object sizes. These features are made possible by an efficient and idempotent two‐step tree optimization algorithm and by selectively enabling coherency optimizations. We have tested our solution under varying scenario setups and compared it to other solutions available in the literature and industry, up to a million simulated objects. The results show that our solution is competitive, with average performance values two to three times better than those achieved by other state‐of‐the‐art AABB‐based CPU solutions.

Investigation of 4-pyridyl liquid crystals on the photovoltaic performance and stability of dye sensitized solar cells by the co-sensitization

Two dual functional molecules 3N and 3N-1 have been utilized to demonstrate the effects of the rod-like liquid crystals (LCs) on dye-sensitized solar cells (DSSCs). The newly developed compounds were characterized by traditional spectrum methods, and the LC properties were investigated through differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). DSSCs were assembled to evaluate the photovoltaic properties. The results show that both 3N and 3N-1 have broad nematic phase temperature intervals during the cooling cycle, and also gain photovoltaic properties on DSSCs as individual dyes. Meanwhile, these two LCs show different effects on the long-term stability and photo-conversion efficiency of the co-sensitized DSSC 3N/AZ6 or 3N-1/AZ6. The loading mode and the dye-desorption mechanism of dyes were also investigated by ATR-IR spectroscopy and DFT calculations.

Acoustic analog computing system based on labyrinthine metasurfaces

Acoustic computing devices, including switches, logic gates, differentiator and integrator, have attracted extensive attentions in both academic research and engineering. However, no scheme of acoustic computing device with more complex functionality has been proposed, such as ordinary differential equation (ODE) solver. Here, we propose an acoustic analog computing (AAC) system based on three cascaded metasurfaces to solve the nth-order ODEs. The metasurfaces are constructed with layered labyrinthine units featuring broad amplitude and phase modulation ranges. The simulated transmitted pressure of the AAC system agrees well with the theoretical solution of ODE, demonstrating the excellent functionality. Unlike the optical ODE solver based on differentiator or integrator, whose geometry becomes more complicated for solving higher order ODE, the proposed AAC system with fixed geometry can be designed for arbitrary nth-order ODE in principle. The proposal may find applications in various scenarios such as acoustic communication, analog computing and signal processing.

Dielectric and optical properties of Ni doped Na0.5Bi0.5TiO3

Polycrystalline Ni doped Na.5Bi0.5TiO3 samples (Na0.5Bi0.5)Ti1-xNixO3, (x = 0.5, 0.10, 0.15) have been prepared by solid state reaction. The appearance of the additional peak in X-ray diffraction pattern indicates the ordering of Ti4+ and Ni2+ ions. Polygonal grains are converted into flakes with an increase of Ni concentration. Replacement of Ti4+ by Ni2+ strongly modifies the relative contribution of two peaks in the Raman bands within 200–400 cm−1. Oxygen vacancy is observed in X-ray photoelectron spectrum to maintain charge neutrality due to aliovalent doping. Broad diffuse phase transition centered at the dielectric constant maximum indicates relaxor behaviour. Comparison between impedance and electric modulus spectrum suggests non-Debye relaxation. The ac conductivity follows the power law with the frequency exponent lies 0.52 − 0.72. The generation of holes by divalent Ni dopant at tetravalent Ti sites enhances optical band gap.

Phase transition and thermal equations of state of (Fe,Al)-bridgmanite and post-perovskite: Implication for the chemical heterogeneity at the lowermost mantle

In this study, we have determined the phase boundary between Mg0.735Fe0.21Al0.07Si0.965O3-Bm and PPv and the thermal equations of state of both phases up to 202 GPa and 2600 K using synchrotron X-ray diffraction in laser heated diamond anvil cells. Our experimental results have shown that the combined effect of Fe and Al produces a wide two-phase coexistence region with a thickness of 26 GPa (410 km) at 2200 K, and addition of Fe lowers the onset transition pressure to 98 GPa at 2000 K, consistent with previous experimental results. Furthermore, addition of Fe was noted to reduce the density (ρ) and bulk sound velocity (VΦ) contrasts across the Bm-PPv phase transition, which is in contrast to the effect of Al. Using the obtained phase diagram and thermal equations of state of Bm and PPv, we have also examined the effect of composition variations on the ρ and VΦ profiles of the lowermost mantle. Our modeling results have shown that the pyrolitic lowermost mantle should be highly heterogeneous in composition and temperature laterally to match the observed variations in the depth and seismic signatures of the D″ discontinuity. Normal mantle in a pyrolitic composition with ∼10% Fe and Al in Bm and PPv will lack clear seismic signature of the D″ discontinuity because the broad phase boundary could smooth the velocity contrast between Bm and PPv. On the other hand, Fe-enriched regions close to the cold slabs may show a seismic signature with a change in the velocity slope of the D″ discontinuity, consistent with recent seismic observations beneath the eastern Alaska. Only regions depleted in Fe and Al near the cold slabs would show a sharp change in velocity. Fe in such regions could be removed to the outer core by strong core-mantle interactions or partitions together with Al to the high-pressure phases in the subduction mid ocean ridge basalts. Our results thus have profound implication for the composition of the lowermost mantle.

PD-L1 inhibition with avelumab for metastatic Merkel cell carcinoma

ABSTRACTIntroduction: Merkel cell carcinoma (MCC) is a rare and aggressive neuroendocrine skin cancer that lacks durable responses to traditional chemotherapy.Areas covered: After MCC was shown to be an immunogenic tumor, small trials revealed high objective response rates to PD-1/PD-L1 checkpoint inhibitors. The JAVELIN Merkel 200 (NCT02155647) trial tested the use of avelumab, a human IgG1 monoclonal antibody against PD-L1, in metastatic MCC. Avelumab recently became the first approved drug for metastatic MCC.Expert commentary: By conducting broad phase I studies assessing the safety of avelumab and a small phase II study demonstrating efficacy in this rare orphan tumor type, avelumab gained accelerated approval for the treatment of metastatic MCC. Additional studies are needed to determine how the antibody-dependent cellular cytotoxicity (ADCC) competent Fc region of avelumab contributes to disease control.Remaining questions: Longer follow-up will determine the durability of checkpoint blockade in controlling metastatic MCC. Additional studies will assess the utility and safety of adjuvant checkpoint blockade in patients with excised MCC. How to increase response rates by combining PD-1/PD-L1 blockade with other treatment approaches needs to be explored. In addition, treatment options for MCC patients who fail or do not respond to avelumab need to be identified.

Multitemperature Memory Actuation of a Liquid Crystal Polymer Network over a Broad Nematic-Isotropic Phase Transition Induced by Large Strain.

The shape change of a polymer actuator based on liquid crystal network (LCN) generally occurs over a relatively sharp LC-isotropic phase transition. Reported herein is the discovery of an unusual phenomenon and the enabled actuation control for LCN. The smectic phase of a LCN with mesogenic moieties on the chain backbone can be suppressed by high elongation of the specimen, which gives rise to a broad nematic-isotropic phase transition. Consequently, the actuation force and related shape of the actuator can be activated to a given degree by easily varying the temperature over a wide range (35 K for LCN prepared with 500% strain) to adjust the proportion of the order-disorder phase transition. This reversible multitemperature memory actuation can translate into many stable and interconvertible shapes with one single LCN actuator.

Mobile phase effects in reversed-phase and hydrophilic interaction liquid chromatography revisited

Correct adjustment of the mobile phase is equally important as the selection of the appropriate column for the separation of polar compounds in LC. Both solvophobic and selective polar interactions control the retention in the Reversed Phase and Hydrophilic Interaction modes. The retention models describing the effects of the volume fraction of the strong eluent component in binary mobile phases on the sample retention factors apply in a limited mobile phase composition range. We introduced a three-parameter retention model, which provides improved prediction of retention over a broad mobile phase range, under isocratic and gradient elution conditions. The model does not imply any assumptions concerning either adsorption or partition distribution mechanism, but allows estimating retention in pure strong and in pure weak mobile phase components. The experimental retention data for phenolic acids and flavones on several core-shell columns with different types of stationary phases agree with the theory.Many polar columns with important structural hydrophobic moieties show dual retention mechanism, (Reversed Phase in water rich mobile phases and Hydrophilic Interaction at high acetonitrile concentrations). It is possible to select the mobile phase compositions in each of the two modes for separations of samples containing compounds largely differing in polarity. The three-parameter model describes the retention in each mode, with separately determined best-fit parameters. We applied the two-mode model to the retention data of sulfonamides and benzoic acid related compounds on a new polymethacrylate zwitterionic monolithic micro-column.