Sol–Gel Preparation of Lead Zirconate Titanate Powders and Ceramics: Effect of Alkoxide Stabilizers and Lead Precursors

Lead zirconate titanate (PZT) (52/48) powders were prepared by a sol–gel process, using different raw materials to introduce the lead component together with several solvents and chemical modifying agents. A study of the effect of these variables on crystallization behavior was conducted to determine the best conditions for preparing monophasic submicrometer-sized PZT perovskite powders in the morphotropic region. In the present work, well-crystallized, submicrometer-sized single-phase perovskite PZT powders were obtained after heat treatment at 600°C for 1 h. The dependence of this crystallization temperature on the preparation conditions was observed. The sol–gel-derived submicrometer-sized PZT powders were sintered to ∼96% of relative density after 2 h at 950°–970°C. The sintered ceramics exhibited a dielectric permittivity of 1000, a piezoelectric coefficient of 135 pC·N⁻¹, a remanent polarization of 20 μC·cm⁻², and a coercive field of 10.6 kV·cm⁻¹.     

Influence of strain and fermentation time on the production,composition, and properties of xanthan gum

The objective of this study was to monitor the influence of Xanthomonas spp. and fermentation time on the production, properties, and composition of xanthan gum, verifying how these variables affect the biopolymer synthesis and properties. Three strains were monitored for 168 h of fermentation. Every 24 h, a sample was collected to determine cell growth, gum production, and substrate consumption. Fourier transform infrared, X-ray diffraction, rheology, molecular characterization, thermogravimetric analysis, sugars, and acids analyzes were performed to characterize the gums produced and to identify possible differences in these properties and composition. The results showed the influence of strain and the fermentation time in production (Pr₆₄₅ = 0.047 g L⁻¹ h⁻¹, Pr₂₉₀ = 0.039 g L⁻¹ h⁻¹, Pr₁₁₅₅ = 0.149 g L⁻¹ h⁻¹) and gum quality, since the viscosity was highest in the first 48 h for strains 290 (148.71 MPa s⁻¹) and 645 (135.28 MPa s⁻¹), while for Strain 1155, the maximum value identified for this property was 90.48 MPa s⁻¹. These results are of practical importance, since they allow obtaining better quality xanthan, enabling reduction of production costs. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48557.     

Monitoring Water Status of Grapevine by Means of THz Waves

Monitoring grapevine water status by means of measuring the reflectivity at the trunk in the terahertz band is presented. A grapevine is located inside a growth chamber to simulate diverse outdoor conditions and correlate them with variations produced in the reflected signal of the trunk. Modifications of light conditions, temperature, and irrigation of the grapevine are recorded either in time domain broadband measurements as well as in the magnitude and phase of narrowband measurements in the frequency domain. The results are compared with traditional techniques using a dendrometer and a humidity probe with excellent agreement.     

Mechanisms of what-where-when memory in black-capped chickadees (Poecile atricapillus): Do chickadees remember “when”?

Integrated what-where-when memory, sometimes called 'episodic-like' memory, has been shown to occur in a number of animals, including food-storing birds and rodents. It is not always clear in these studies, however, what aspect of “when” is remembered. We examined memory for what, where, and when in black-capped chickadees Poecile atricapillus in a procedure designed to dissociate memory for elapsed time (how long ago) from memory for a point in time, the sense of “when” implied in most discussions of episodic or episodic-like memory. Chickadees searched for food in multiple trials that each involved a two-phase procedure. In Phase 1, birds found preferred mealworms in half the sites on one side of an aviary and less preferred sunflower seeds in half the sites on the other side of the aviary. In Phase 2, following a retention interval, birds searched in the aviary with fresh sunflower seeds placed in the sites that held seeds in Phase 1 but either fresh or degraded mealworms in the sites that held mealworms in Phase 1. Whether a site held fresh or degraded worms depended on either when during the day Phase 1 had occurred (Group When), how long ago Phase 1 had occurred (Group HLA), or both (Group When + HLA). Chickadees in all three groups were able to discriminate where and when palatable worms were to be found, but there were temporal limitations on the use of HLA and When + HLA cues that were not found for the use of When cues. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Impact of the geometry of inclusions at the micro-scale on the overall stochastic properties

In this contribution, the establishment of relationships between the microstructure of the material and the macroscopic properties is numerically investigated. The material under study is composed by inclusions randomly distributed on a uniform matrix and its heterogeneous nature is characterized by the size, shape, spatial distribution, and properties of the inclusions. To conduct these analyses, a general framework that generates and simulates representative volume elements (RVEs) based on the commercial finite element (FEM) software ABAQUS and existing homogenization techniques is developed. Two- and three-dimensional RVEs are generated and the variation of the properties investigated using a statistical approach.     

Laboratory methods for assessing API sensitivity to mechanical stress during agitated drying

Two distinct laboratory methods have been developed to assess the propensity of active pharmaceutical ingredients to undergo particle breakage during agitated drying operations. In the first method, mechanical stress is applied to particles by mechanical agitation of powders compressed under an applied normal force. For the second, particles experience stresses as they are carried within a pressurized gas stream. These methods are simple, relatively compound-sparing, and are used to rank materials according to a quantitative breakage classification scale as hard, medium, or easy to break. Based on the results obtained using these methods at laboratory scale, recommendations and precautions for processing at larger scale are made. In this paper, these methods are described in detail, and the results, obtained for several pharmaceutical compounds, are presented.     

Functionally graded materials produced by friction stir processing

An investigation was conducted in order to produce aluminium based functionally graded MMC reinforced by SiC ceramic particles with median size of 118.8, 37.4 and 12.3 μm. AA5083 aluminium alloy plates in the H111 and partially annealed conditions were processed. Several strategies for reinforcement were investigated and its influence on the particle distribution and homogeneity was studied. A square shaped groove packed with reinforcement particles of SiC was studied and it was seen that it was more effective when the groove was placed under the probe. If the groove was placed outside the probe interaction area, but within the shoulder influence area, insufficient dispersion of particles was observed. Small particles lead to higher concentration along the bead surface and to smooth fraction gradients both in depth and along the direction parallel to the surface. The thickness of the reinforced layer depends of particle size within the parametric conditions and the tool geometry used in this investigation.     

Future Perspectives in Detecting EGFR and ALK Gene Alterations in Liquid Biopsies of Patients with NSCLC

Non-small-cell lung cancer (NSCLC) is a major cause of death worldwide. Alterations in such genes as EGFR and ALK are considered important biomarkers in NSCLC due to the existence of targeted therapies with specific tyrosine kinase inhibitors (TKIs). However, specific resistance-related mutations can occur during TKI treatment, which often result in therapy inefficacy. Liquid biopsies arise as a reliable tool for the early detection of these types of alterations, allowing a non-invasive follow-up of the patients. Furthermore, they can be essential for cancer screening, initial diagnosis and to check surgery success. Despite the great advantages of liquid biopsies in NSCLC and the high input that next-generation sequencing (NGS) approaches can provide in this field, its use in oncology is still limited. With improvement of assay sensitivity and the establishment of clinical guidelines for liquid biopsy analysis, it is expected that they will be used in routine procedures. This review focuses on the usefulness of liquid biopsies of NSCLC patients as a means to detect alterations in EGFR and ALK genes and in disease management, highlighting the impact of NGS methods.