Impact of Ba2+ on Structure and Piezoelectric Properties of PMN–PZN–PNN–PT Ceramics Near the Morphotropic Phase Boundary

The effect of using Ba²⁺ to modify the structure and dielectric and piezoelectric properties of Pb_(1?x)Ba_x(Mg_1/3Nb_2/3)_m(Zn_1/3Nb_2/3)_y(Ni_1/3Nb_2/3)_nTi_zO₃(x = 0–0.15) ceramics near the morphotropic phase boundary has been investigated. It is found that increasing the content of Ba²⁺ leads to a sequence of structural transformations from heterophase state (tetragonal and pseudocubic phases) to a cubic state via an intermediate pseudocubic phase. The evolution of the dielectric and piezoelectric properties (sequences of transformations: normal ferroelectric →relaxor ferroelectric → paraelectric) is shown. It is stated that ceramics with x = 0.025–0.050 possess the optimal combination of functional parameters for use in low‐frequency receivers and actuators. They are characterized by high values of small‐signal and large‐signal piezoelectric coefficients d₃₃ of 621 pC/N and ~1500 m/V (at E = 5 kV/cm), respectively, and also by increased values of dielectric permittivity ε/ε₀ and tunability coefficient (К = [(ε/ε₀(E = 0) ? ε/ε₀(E≠0))/ε/ε₀(E = 0)]·100%), equal to ~7000 and ~80%, respectively (at E = 20 kV/cm). It is shown that for the creation of high‐power piezoelectric transducers it is necessary to use ceramics with x = 0.125, which differs with high values of the mechanical quality factor Q_m and ε/ε₀ (1406 and 10 890, respectively).     

CMOS-compatible dense arrays of Ge quantum dots on the Si(001) surface: hut cluster nucleation, atomic structure and array life cycle during UHV MBE growth

We report a direct observation of Ge hut nucleation on Si(001) during UHV molecular beam epitaxy at 360°C. Nuclei of pyramids and wedges were observed on the wetting layer (WL) (M × N) patches starting from the coverage of 5.1 Å and found to have different structures. Atomic models of nuclei of both hut species have been built as well as models of the growing clusters. The growth of huts of each species has been demonstrated to follow generic scenarios. The formation of the second atomic layer of a wedge results in rearrangement of its first layer. Its ridge structure does not repeat the nucleus. A pyramid grows without phase transitions. A structure of its vertex copies the nucleus. Transitions between hut species turned out to be impossible. The wedges contain point defects in the upper corners of the triangular faces and have preferential growth directions along the ridges. The derived structure of the {105} facet follows the paired dimer model. Further growth of hut arrays results in domination of wedges, and the density of pyramids exponentially drops. The second generation of huts arises at coverages >10 Å; new huts occupy the whole WL at coverages ~14 Å. Nanocrystalline Ge 2D layer begins forming at coverages >14 Å.     

Light scattering study of sodium caseinate + dextran sulfate in aqueous solution: Relationship to emulsion stability

Using combined static and dynamic light scattering, various structural and thermodynamic parameters have been determined for the complex particles formed from sodium caseinate (0.5 wt/v%) + dextran sulfate (0.01, 0.1 or 1.0 wt/v%) in aqueous solution at pH = 6.0. The polysaccharide contents refer, respectively, to three polysaccharide/protein molar ratios (R = 1, 10 and 100) calculated on the basis of the measured values of the weight-average molar masses of sodium caseinate particles and dextran sulfate molecules. The complexes were prepared by mixing together the two biopolymer components in bulk solution or bringing them together at the interface in a protein-stabilized foam. The results indicate dissociation of the original sodium caseinate particles in response to associative interactions with excess amounts of negatively charged polysaccharide. A significant difference was observed between properties of complexes formed in solution and those formed at the interface, especially for R = 100. We identify a possible correlation between the structures of these complexes and the recently reported stability properties of oil-in-water emulsions containing the same biopolymers (Jourdain, L., Leser, M. E., Schmitt, C., Michel, M., & Dickinson, E. (2008). Food Hydrocolloids, 22, 647–659). In particular, we infer that the greater hydrophilicity and the more open/bulky architecture of complexes formed in the bulk aqueous phase are better able to provide effective steric/electrostatic stabilization of the so-called “mixed” emulsions, as compared with the interfacial complexes formed in the so-called “bilayer” emulsions. We also present results on the effect of ionic strength on the structural parameters of the complexes, and we attempt to interpret the data in the context of previously determined stability behaviour of the corresponding emulsions.     

Comparative in Vivo Assessment of Some Adverse Bioeffects of Equidimensional Gold and Silver Nanoparticles and the Attenuation of Nanosilver’s Effects with a Complex of Innocuous Bioprotectors

Stable suspensions of nanogold (NG) and nanosilver (NS) with mean particle diameter 50 and 49 nm, respectively, were prepared by laser ablation of metals in water. To assess rat’s pulmonary phagocytosis response to a single intratracheal instillation of these suspensions, we used optical, transmission electron, and semi-contact atomic force microscopy. NG and NS were also repeatedly injected intraperitoneally into rats at a dose of 10 mg/kg (0.5 mg per mL of deionized water) three times a week, up to 20 injections. A group of rats was thus injected with NS after oral administration of a “bioprotective complex” (BPC) comprised of pectin, multivitamins, some amino acids, calcium, selenium, and omega-3 PUFA. After the termination of the injections, many functional and biochemical indices and histopathological features of the spleen, kidneys and liver were evaluated for signs of toxicity, and accumulation of NG or NS in these organs was measured. From the same rats, we obtained cell suspensions of different tissues for performing the RAPD test. It was demonstrated that, although both nanometals were adversely bioactive in all respects considered in this study, NS was more noxious as compared with NG, and that the BPC tested by us attenuated both the toxicity and genotoxicity of NS.     

Biocidal action of copolymers based on aliphatic diamines and guanidine hydrochloride

Copolymers of polyguanidines with various lengths of hydrocarbon radicals were obtained by polycondensation. The biocidal action of water‐soluble, guanidine‐containing copolymers on the pathogenic microorganisms Escherichia coli and Bacillus cereus by the method of agar diffusion was evaluated. The results indicate that the ratio of hydrophobic methylene groups to ionogen guanidine groups influenced the copolymer biocidal action. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40319.     

Desulfurization of Tall Oil Rosin

Tall oil rosin has limited application due to the presence of sulfur compounds. By treatments with acetic acid and 2‐ethoxyethanol the total sulfur content of tall oil rosin was reduced from 630 to 48 ppm.     

Two distinct events, section compression and loss of particles ("lost caps"), contribute to z-axis distortion and bias in optical disector counting

Deformation of tissue sections in the z-axis can bias optical disector counting. When samples of particle densities are not representative for the entire tissue section, significant bias of estimated numbers can result. To assess the occurrence, prevalence, extent, sequence of events, and causes of z-axis distortion, the distribution of neuronal nucleoli in thick paraffin and vibratome sections was determined in chicken, rodent, and human brain tissues. When positions of neuronal nucleoli were measured in the z-axis, nucleoli were more frequent at the surfaces (bottom and top) of tissue sections than in the core. This nonlinear z-axis distribution was not lab-, equipment-, or investigator-specific, and was independent of age, fixation quality, coverslipping medium, or paraffin melting temperature, but in paraffin sections, was highly correlated with the tilt of the knife (cutting) angle. Manipulation of subsequent tissue processing steps revealed that two events contribute to z-axis distortion. Initially, a higher density of particles results at surfaces after sectioning, apparently due to section compression. Subsequently, particles can be lost to varying degrees from surfaces during floating or staining and dehydration, resulting in "lost caps." These results may explain different degrees of z-axis distortion between different types of sections and different labs, and reinforce the importance of checking z-axis distributions as a "quality control" prior to selection of guard zones in optical disector counting. Indirect approaches to assess section quality, such as resectioning in a perpendicular plane, yield additional artifacts, and should be replaced by a direct quantitative measurement of z-axis distribution of particles.     

Cheaper faster drug development validated by the repositioning of drugs against neglected tropical diseases

There is an urgent need to make drug discovery cheaper and faster. This will enable the development of treatments for diseases currently neglected for economic reasons, such as tropical and orphan diseases, and generally increase the supply of new drugs. Here, we report the Robot Scientist ‘Eve’ designed to make drug discovery more economical. A Robot Scientist is a laboratory automation system that uses artificial intelligence (AI) techniques to discover scientific knowledge through cycles of experimentation. Eve integrates and automates library-screening, hit-confirmation, and lead generation through cycles of quantitative structure activity relationship learning and testing. Using econometric modelling we demonstrate that the use of AI to select compounds economically outperforms standard drug screening. For further efficiency Eve uses a standardized form of assay to compute Boolean functions of compound properties. These assays can be quickly and cheaply engineered using synthetic biology, enabling more targets to be assayed for a given budget. Eve has repositioned several drugs against specific targets in parasites that cause tropical diseases. One validated discovery is that the anti-cancer compound TNP-470 is a potent inhibitor of dihydrofolate reductase from the malaria-causing parasite Plasmodium vivax.     

Moving Droplets in 3D Using Light

The emulation of the complex cellular and bacterial vesicles used to transport materials through fluids has the potential to add revolutionary capabilities to fluidic platforms. Although a number of artificial motile vesicles or microdroplets have been demonstrated previously, control over their movement in liquid in 3D has not been achieved. Here it is shown that by adding a chemical “fuel,” a photoactive material, to the droplet, it can be moved in any direction (3D) in water using simple light sources without the need for additives in the water. The droplets can be made up of a range of solvents and move with speeds as high as 10.4 mm s^?1 toward or away from the irradiation source as a result of a light‐induced isothermal change in interfacial tension (Marangoni flow). It is further demonstrated that more complex functions can be accomplished by merging a photoactive droplet with a droplet carrying a “cargo” and moving the new larger droplet to a “reactor” droplet where the cargo undergoes a chemical reaction. The control and versatility of this light‐activated, motile droplet system will open up new possibilities for fluidic chemical transport and applications.