Ferroelectric properties of (1 − x)Bi(Zn1/2Ti1/2)O3–xPbZrO3 ceramics

The (1 − x)Bi(Zn1/2Ti1/2)O3–xPbZrO3 solid solution ceramics were prepared by using solid-state reaction method, and their ferroelectric properties were investigated. It was found that the perovskite structure is stable for compositions with x ≥ 0.900. Within this composition range, the crystal structure of the solid solution preserves the orthorhombic symmetry of PbZrO3 (PZ). The Curie point of the ceramics was found to decrease with increasing Bi(Zn1/2Ti1/2)O3 (BZT) content. The intermediate ferroelectric phase of PZ was stabilized by BZT addition and exists within a much wider temperature range in the solid solution

The morphotropic phase boundary and electrical properties of (1 − x)Pb(Zn1/2W1/2)O3–xPb(Zr0.5Ti0.5)O3 ceramics

Ceramics in the solid solution of (1 − x)Pb(Zn1/2W1/2)O3–xPb(Zr0.5Ti0.5)O3 system, with x = 0.80, 0.85, 0.90, and 0.95, were synthesized with the solid-state reaction technique. The perovskite phase formation in the sintered ceramics was analyzed with X-ray diffraction. It shows that the rhombohedral and the tetragonal phases coexist in the ceramic with x = 0.90, indicating the morphotropic phase boundary (MPB) within this pseudo-binary system. Dielectric and ferroelectric properties measurements indicate that the transition temperature decreases while the remanent polarization increases with the addition of Pb(Zn1/2W1/2)O3. In the composition of x = 0.85 which is close to the MPB in the rhombohedral side, a high piezoelectric property with d 33 = 222 pC/N was observed

The Morphotropic Phase Boundary in the (1-x)PbZrO3–x[0.3Bi(Zn1/2Ti1/2)O3–0.7PbTiO3] Perovskite Solid Solution

Ceramics in the (1-x)PbZrO3–x[0.3Bi(Zn1/2Ti1/2)O3–0.7PbTiO3] solid solution system with 0.48 x 0.56 were investigated. A morphotropic phase boundary separating rhombohedral and tetragonal perovskite phases was identified at x = 0.52. This composition displays the maximum remanent polarization Pr of 40.7 μC/cm2 and the best piezoelectric coefficient d33 of 311 pC/N in the pseudo-binary system. However, the Curie temperature Tc for this MPB composition is 291 °C, much lower than initially expected

Absolute and proportional measures of potential markers of rehearsal, and their implications for accounts of its development

Previous studies of the development of phonological similarity and word length effects in children have shown that these effects are small or absent in young children, particularly when measured using visual presentation of the memoranda. This has often been taken as support for the view that young children do not rehearse. The current paper builds on recent evidence that instead suggests that absent phonological similarity and word length effects in young children reflects the same proportional cost of these effects in children of all ages. Our aims are to explore the conditions under which this proportional scaling account can reproduce existing developmental data, and in turn suggest ways that future studies might measure and model phonological similarity and word length effects in children. To that end, we first fit a single mathematical function through previously reported data that simultaneously captures absent and negative proportional effects of phonological similarity in young children plus constant proportional similarity effects in older children. This developmental function therefore provides the benchmark that we seek to re-produce in a series of subsequent simulations that test the proportional scaling account. These simulations reproduce the developmental function well, provided that they take into account the influence of floor effects and of measurement error. Our simulations suggest that future empirical studies examining these effects in the context of the development of rehearsal need to take into account proportional scaling. They also provide a demonstration of how proportional costs can be explored, and of the possible developmental functions associated with such an analysis

Selective cell death of latently HIV-infected CD4+ T cells mediated by autosis inducing nanopeptides.

Despite significant advances in the treatment of human immunodeficiency virus type-1 (HIV) infection, antiretroviral therapy only suppresses viral replication but is unable to eliminate infection. Thus, discontinuation of antiretrovirals results in viral reactivation and disease progression. A major reservoir of HIV latent infection resides in resting central memory CD4+ T cells (TCM) that escape clearance by current therapeutic regimens and will require novel strategies for elimination. Here, we evaluated the therapeutic potential of autophagy-inducing peptides, Tat-Beclin 1 and Tat-vFLIP-α2, which can induce a novel Na+/K+-ATPase dependent form of cell death (autosis), to kill latently HIV-infected TCM while preventing virologic rebound. In this study, we encapsulated autophagy inducing peptides into biodegradable lipid-coated hybrid PLGA (poly lactic-co-glycolic acid) nanoparticles for controlled intracellular delivery. A single dose of nanopeptides was found to eliminate latent HIV infection in an in vitro primary model of HIV latency and ex vivo using resting CD4+ T cells obtained from peripheral blood mononuclear cells of HIV-infected patients on antiretroviral with fully suppressed virus for greater than 12 months. Notably, increased LC3B lipidation, SQSTM1/p62 degradation and Na+/K+-ATPase activity characteristic of autosis, were detected in nanopeptide treated latently HIV-infected cells compared to untreated uninfected or infected cells. Nanopeptide-induced cell death could be reversed by knockdown of autophagy proteins, ATG5 and ATG7, and inhibition or knockdown of Na+/K+-ATPase. Importantly, viral rebound was not detected following the induction of the Na+/K+-ATPase dependent form of cell death induced by the Tat-Beclin 1 and Tat-vFLIP-α2 nanopeptides. These findings provide a novel strategy to eradicate HIV latently infected resting memory CD4+ T cells, the major reservoir of HIV latency, through the induction of Na+/K+-ATPase dependent autophagy, while preventing reactivation of virus and new infection of uninfected bystander cells

Multifunctional Properties of Cyanate Ester Composites with SiO2 Coated Fe3O4 Fillers

SiO2 coated Fe3O4 submicrometer spherical particles (a conducting core/insulating shell configuration) are fabricated using a hydrothermal method and are loaded at 10 and 20 vol % into a bisphenol E cyanate ester matrix for synthesis of multifunctional composites. The dielectric constant of the resulting composites is found to be enhanced over a wide frequency and temperature range while the low dielectric loss tangent of the neat cyanate ester polymer is largely preserved up to 160 °C due to the insulating SiO2 coating on individual conductive Fe3O4 submicrometer spheres. These composites also demonstrate high dielectric breakdown strengths at room temperature. Dynamic mechanical analysis indicates that the storage modulus of the composite with a 20 vol % filler loading is twice as high as that of neat resin, but the glass transition temperature considerably decreases with increasing filler content. Magnetic measurements reveal a large saturation magnetization and negligibly low coercivity and remanent magnetization in these composites

Design of a Direct-Detection Wind and Aerosol Lidar for Mars Orbit

The present knowledge of the Mars atmosphere is greatly limited by a lack of global measurements of winds and aerosols. Hence, measurements of height-resolved wind and aerosol profiles are a priority for new Mars orbiting missions. We have designed a direct-detection lidar (MARLI) to provide global measurements of dust, winds and water ice profiles from Mars orbit. From a 400-km polar orbit, the instrument is designed to provide wind and backscatter measurements with a vertical resolution of 2 km and with resolution of 2 in latitude along track. The instrument uses a single-frequency, seeded Nd:YAG laser that emits 4 mJ pulses at 1064 nm at a 250 Hz pulse rate. The receiver utilizes a 50-cm diameter telescope and a double edge Fabry-Prot etalon as a frequency discriminator to measure the Doppler shift of the aerosol-backscatter profiles. The receiver also includes a polarization-sensitive channel to detect the cross-polarized backscatter profiles from water ice. The receiver uses a sensitive 4 4 pixel HgCdTe avalanche photodiode array as a detector for all signals. Here we describe the measurement concept, instrument design, and calculate its performance for several cases of Mars atmospheric conditions. The calculations show that under a range of atmospheric conditions MARLI is capable of measuring wind speed profiles with random error of 24 m/s within the first three scale heights, enabling vertically resolved mapping of transport processes in this important region of the atmosphere

On the IRS Deployment in Smart Factories Considering Blockage Effects: Collocated or Distributed?

In this article, we study the collocated and distributed deployment of intelligent reflecting surfaces (IRS) for a fixed total number of IRS elements to support enhanced mobile broadband (eMBB) and ultra-reliable low-latency communication (URLLC) services inside a factory. We build a channel model that incorporates the line-of-sight (LOS) probability and power loss of each transmission path, and propose three metrics, namely, the expected received signal-to-noise ratio (SNR), expected finite-blocklength (FB) capacity, and expected outage probability, where the expectation is taken over the probability distributions of interior blockages and channel fading. The expected received SNR and expected FB capacity for extremely high blockage densities are derived in closed-form as functions of the amount and height of IRSs and the density, size, and penetration loss of blockages, which are verified by Monte Carlo simulations. Results show that deploying IRSs vertically higher leads to higher expected received SNR and expected FB capacity. By analysing the average/minimum/maximum of the three metrics versus the number of IRSs, we find that for high blockage densities, both eMBB and URLLC services benefit from distributed deployment; and for low blockage densities, URLLC services benefit from distributed deployment while eMBB services see limited difference between collocated and distributed deployment

Transesterification of Poly(ethyl glyoxylate): A Route to Structurally Diverse Polyglyoxylates

Polyglyoxylates are a class of self-immolative polymers that depolymerize in solution and the solid state. The glyoxylic acid degradation product is a metabolite in the glyoxylate cycle and can also be processed in the liver in humans, making polyglyoxylates attractive for applications in the environment and in medicine. Although expanding the scope of available polyglyoxylates would enable new properties and applications, highly pure glyoxylate monomers are required for polymerization, and this level of purity is difficult to achieve for many potential monomers. To address this challenge, we report here the 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD)-catalyzed post-polymerization transesterification of poly(ethyl glyoxylate) (PEtG) as a general method for the synthesis of directly inaccessible polyglyoxylates. Using a new end-capping strategy, PEtG compatible with the transesterification reaction was developed. n-Propanol, i-propanol, n-butanol, t-butanol, n-pentanol, n-hexanol, n-octanol, and benzyl alcohol were employed and the reactivities of these different alcohols were investigated. The resulting polyglyoxylates were characterized chemically and their thermal properties were compared. In all cases, the transesterified polyglyoxylates retained the stimuli-responsive depolymerization properties of the parent PEtG. In addition, functional polyglyoxylates based on allyl, propargyl, and furfuryl esters, which are suitable for subsequent click reactions, were prepared. The propargyl-functionalized polyglyoxylate was used to conjugate pyrene, and the resulting molecules underwent a change in fluorescence properties upon depolymerization