Synthesis,structure, and magnetic property of hexagonal perovskite Ba5Sn1.1Mn3.9O15

A new compound Ba₅Sn_1.1Mn_3.9O₁₅ has been synthesized at 1300 °C by solid-state reaction. The structure was characterized by X-ray, electron and neutron diffraction methods. Ba₅Sn_1.1Mn_3.9O₁₅ crystallizes in hexagonal space group P6₃/mmc with a = 5.717 Å and c = 23.534 Å. The magnetic measurement reveals that Ba₅Sn_1.1Mn_3.9O₁₅ has a spin glass transition at 7 K.     

Pore Structure Evolution of Lanthana–Alumina Systems Prepared through Coprecipitation

Pure Al₂O₃ and different compositions of La₂O₃–Al₂O₃ samples have been prepared through coprecipitation. Even after heating at 1300°C, the compositions La₂O₃·11Al₂O₃ and La₂O₃·13Al₂O₃ had higher surface area compared to the pure Al₂O₃ and the La₂O₃·Al₂O₃ composition. Ethanol washing is an effective way for improving the textural stability of pure Al₂O₃ and La₂O₃–Al₂O₃ samples. The effect of steam on the thermal stability of La₂O₃·11Al₂O₃ has also been studied. La₂O₃·11Al₂O₃ sample is found to be stable in steam.     

Dislocations at Prismatic Fracture Surfaces in Sapphire

Single-crystal sapphire exhibits a highly anisotropic fracture behavior. The surfaces of specimens fractured along prismatic planes are wavy, with fractographic features appearing as small areas of contrast under an optical microscope. Optical microscopy, atomic force microscopy, X-ray topography, and confocal microscopy are used to demonstrate a correlation between the areas of contrast and dislocations penetrating the sample surface. The surface features are argued to be a consequence of the stress field surrounding the dislocations, which deflect the crack approximately 10 nm normal to the surface as the crack cuts the dislocations. The lateral extent of measurable surface deflection is of the order of 5 μm. These images can be compared directly to show the equivalence of the position of the dislocations observed by X-ray topography and the surface contrast observed optically.     

UV, Raman and XRD study of polymorphism of poly(methyl-n-propylsilane)

Raman, UV and XRD studies have been performed to characterize the structures of differently prepared samples of poly(methyl-n-propylsilane). The results demonstrate polymorphism of this polymer between T_c and T_g. At room temperature the polymer can exist in up to four modifications which comprise one amorphous disordered phase and three more ordered modifications, differing in the interchain organization and in the silicon backbone conformations. The latter are considered to be deviant, transoid and all-anti, respectively. The number of the modifications present and relative amount of each strongly depends on the preparation method and thermal history of the sample as well as on the molecular weight.     

Prevention of liquid metal embrittlement cracks in resistance spot welds by adaption of electrode geometry

ABSTRACT

Advanced high strength steels are usually coated by a zinc layer for an increased resistance against corrosion. During the resistance spot welding of zinc coated steel grades, liquid metal embrittlement (LME) may occur. As a result, cracking inside and around the spot weld indentation is observable. The extent of LME cracks is influenced by a variety of different factors. In this study, the impact of the used electrode geometry is investigated over a stepwise varied weld time. A spot welding finite element simulation is used to analyse and explain the observed effects. Results show significant differences especially for highly increased weld times. Based on identical overall dimensions, electrode geometries with a larger working plane allow for longer weld times, while still preventing LME within the investigated material and maintaining accessibility.     

In search of intelligence: evolving a developmental neuron capable of learning

A neuro-inspired multi-chromosomal genotype for a single developmental neuron capable of learning and developing memory is proposed. This genotype is evolved so that the phenotype which changes and develops during an agent's lifetime (while problem-solving) gives the agent the capacity for learning by experience. Seven important processes of signal processing and neural structure development are identified from biology and encoded using Cartesian Genetic Programming. These chromosomes represent the electrical and developmental aspects of dendrites, axonal branches, synapses and the neuron soma. The neural morphology that occurs by running these chromosomes is highly dynamic. The dendritic/axonal branches and synaptic connections form and change in response to situations encountered in the learning task. The approach has been evaluated in the context of maze-solving and the board game of checkers (draughts) demonstrating interesting learning capabilities. The motivation underlying this research is to, ab initio, evolve genotypes that build phenotypes with an ability to learn.     

Combined Blockade of TIGIT and CD39 or A2AR Enhances NK-92 Cell-Mediated Cytotoxicity in AML

This study aimed to characterize different natural killer (NK) cell phenotypes on bone marrow and peripheral blood cells from acute myeloid leukemia (AML) patients and healthy donors (HDs). Our data show that CD56^dimCD16⁻ and CD56^brightCD16⁻ NK cells represent the predominant NK cell subpopulations in AML, while the CD56^dimCD16⁺ NK cells are significantly reduced compared to HDs. Moreover, TIGIT⁺ and PVRIG⁺ cells cluster on the CD56^dimCD16⁺ subset whereas CD39⁺ and CD38⁺ cells do so on CD56^brightCD16⁻ NK cells in AML. Furthermore, functional effects of (co-)blockade of TIGIT and CD39 or A2AR on NK cell functionality were analyzed. These experiments revealed that the single blockade of the TIGIT receptor results in an increased NK-92 cell-mediated killing of AML cells in vitro. Combined targeting of CD39 or A2AR significantly augments the anti-TIGIT-mediated lysis of AML cells. Our data indicate that distinct NK cell subsets in AML exhibit different immunosuppressive patterns (via the TIGIT/PVRIG receptors and the purinergic pathway). In summary, we conclude that TIGIT, CD39, and A2AR constitute relevant inhibitory checkpoints of NK cells in AML patients. A combinatorial blockade synergistically strengthens NK-92 cell-mediated cytotoxicity. As inhibitors of TIGIT, CD39, and A2AR are clinically available, studies on their combined use could be conducted in the near future.     

Dynamic data rectification using particle filters

The basis of dynamic data rectification is a dynamic process model. The successful application of the model requires the fulfilling of a number of objectives that are as wide-ranging as the estimation of the process states, process signal denoising and outlier detection and removal. Current approaches to dynamic data rectification include the conjunction of the Extended Kalman Filter (EKF) and the expectation-maximization algorithm. However, this approach is limited due to the EKF being less applicable where the state and measurement functions are highly non-linear or where the posterior distribution of the states is non-Gaussian. This paper proposes an alternative approach whereby particle filters, based on the sequential Monte Carlo method, are utilized for dynamic data rectification. By formulating the rectification problem within a probabilistic framework, the particle filters generate Monte Carlo samples from the posterior distribution of the system states, and thus provide the basis for rectifying the process measurements. Furthermore, the proposed technique is capable of detecting changes in process operation and thus complements the task of process fault diagnosis. The appropriateness of particle filters for dynamic data rectification is demonstrated through their application to an illustrative non-linear dynamic system, and a benchmark pH neutralization process.     

Novel Acyl Phosphate Mimics that Target PlsY,an Essential Acyltransferase in Gram‐Positive Bacteria

PlsY is a recently discovered acyltransferase that executes an essential step in membrane phospholipid biosynthesis in Gram‐ positive bacteria. By using a bioisosteric replacement approach to generate substrate‐based inhibitors of PlsY as potential novel antibacterial agents, a series of stabilized acyl phosphate mimetics, including acyl phosphonates, acyl α,α‐difluoromethyl phosphonates, acyl phosphoramides, reverse amide phosphonates, acyl sulfamates, and acyl sulfamides were designed and synthesized. Several acyl phosphonates, phosphoramides, and sulfamates were identified as inhibitors of PlsY from Streptococcus pneumoniae and Bacillus anthracis. As anticipated, these inhibitors were competitive inhibitors with respect to the acyl phosphate substrate. Antimicrobial testing showed the inhibitors to have generally weak activity against Gram‐positive bacteria with the exception of some acyl phosphonates, reverse amide phosphonates, and acyl sulfamates, which had potent activity against multiple strains of B. anthracis.     

Methanol reforming for fuel-cell applications: development of zirconia-containing Cu–Zn–Al catalysts

The steam reforming of methanol to form mixtures of carbon dioxide and hydrogen, together with traces of carbon monoxide, is considered to be a potential source of hydrogen as the fuel for a fuel-cell to be used in mobile power sources. After outlining some of the constraints inherent in the use of the reaction and the types of catalysts which have been used by other investigators, this paper presents results on the preparation and testing of a series of copper-containing catalysts for this reaction. It is shown that the reaction sequence probably involves the formation of methyl formate which then decomposes to give CO₂ as the primary product; CO is formed by the reverse water–gas shift reaction and this only occurs to an appreciable extent when the methanol is almost completely converted. A number of different copper-containing catalysts are then described and it is shown that of these sequentially precipitated Cu/ZnO/ZrO₂/Al₂O₃ materials have the highest activities and stabilities for the steam reforming reaction.