The Mammalian Class 3 PI3K (PIK3C3) Is Required for Early Embryogenesis and Cell Proliferation

The Pik3c3 gene encodes an 887 amino acid lipid kinase, phosphoinositide-3-kinase class 3 (PIK3C3). PIK3C3 is known to regulate various intracellular membrane trafficking events. However, little is known about its functions during early embryogenesis in mammals. To investigate the function of PIK3C3 in vivo, we generated Pik3c3 null mice. We show here that Pik3c3 heterozygous are normal and fertile. In contrast, Pik3c3 homozygous mutants are embryonic lethal and die between E7.5 and E8.5 of embryogenesis. Mutant embryos are poorly developed with no evidence of mesoderm formation, and suffer from severely reduced cell proliferations. Cell proliferation defect is also evident in vitro, where mutant blastocysts in culture fail to give rise to typical colonies formed by inner cell mass. Electron microscopic analysis revealed that epiblast cells in mutant embryos appear normal, whereas the visceral endoderm cells contain larger vesicles inside the lipid droplets. Finally, we provide evidence that mTOR signaling is drastically reduced in Pik3c3 null embryos, which could be a major contributor to the observed proliferation and embryogenesis defects

Nanoscale corrosion behavior of polycrystalline copper fine wires in dilute NaCl solution investigated by in-situ atomic force microscopy

In this study, nanoscale corrosion behavior of copper fine wires in dilute NaCl solution is studied by atomic force microscopy and electron backscatter diffraction. The dissolution rate of grains constituting the wires strongly depends on their crystallographic orientation. In pure water, the dissolution rate increases in the order of (111) < (001) < (110). Addition of Cl- dramatically increases the dissolution rate of the (111) surface to alter the order to (110) ≈ (001) ≈ (111) at 0.1 mM. These results show that the crystallographic orientation dependence is significantly changed by a slight increase of Cl- concentration in dilute solution. © 2016 Elsevier Ltd.Embargo Period 24 month

Visualizing Nanoscale Distribution of Corrosion Cells by Open-Loop Electric Potential Microscopy

Corrosion is a traditional problem but still one of the most serious problems in industry. To reduce the huge economic loss caused by corrosion, tremendous effort has been made to understand, predict and prevent it. Corrosion phenomena are generally explained by the formation of corrosion cells at a metal-electrolyte interface. However, experimental verification of their nanoscale distribution has been a major challenge owing to the lack of a method able to visualize the local potential distribution in an electrolytic solution. In this study, we have investigated the nanoscale corrosion behavior of Cu fine wires and a duplex stainless steel by in situ imaging of local corrosion cells by open-loop electric potential microscopy (OL-EPM). For both materials, potential images obtained by OL-EPM show nanoscale contrasts, where areas of higher and lower potential correspond to anodic areas (i.e., corrosion sites) and cathodic areas, respectively. This imaging capability allows us to investigate the real-time transition of local corrosion sites even when surface structures show little change. This is particularly useful for investigating reactions under surface oxide layers or highly corrosion-resistant materials as demonstrated here. The proposed technique should be applicable to the study of other redox reactions on a battery electrode or a catalytic material. The results presented here open up such future applications of OL-EPM in nanoscale electrochemistry. © 2016 American Chemical Society.Embargo Period 12 month

On the biaxiality of smectic C and ferroelectric liquid crystals

Ferroelectric liquid crystals (FLCs) were a major topic for research in the 1980s and 1990s, to which George Gray and his research family played a fundamental role in developing the field. The famous symbiotic relationship between the chemists at Hull University and device physicists at the Royal Signals and Radar Establishment (RSRE) continued throughout this period, providing the basis for the τVmin mode of FLC operation. The principal of this mode relies on the dielectric biaxiality inherent to the smectic C and ferroelectric smectic C* liquid crystal phases. As with nematics before, new materials and device physics developed hand-in-hand, allowing materials to be formulated with addressing times of 12μs at voltages below 30 V. After reviewing the material physics behind these devices, new measurements of the biaxial refractive indices and permittivities are presented, from which the biaxial order parameter C is determined

Organization of sensory feature selectivity in the whisker system

Our sensory receptors are faced with an onslaught of different environmental inputs. Each sensory event or encounter with an object involves a distinct combination of physical energy sources impinging upon receptors. In the rodent whisker system, each primary afferent neuron located in the trigeminal ganglion innervates and responds to a single whisker and encodes a distinct set of physical stimulus properties – features – corresponding to changes in whisker angle and shape and the consequent forces acting on the whisker follicle. Here we review the nature of the features encoded by successive stages of processing along the whisker pathway. At each stage different neurons respond to distinct features, such that the population as a whole represents diverse properties. Different neuronal types also have distinct feature selectivity. Thus, neurons at the same stage of processing and responding to the same whisker nevertheless play different roles in representing objects contacted by the whisker. This diversity, combined with the precise timing and high reliability of responses, enables populations at each stage to represent a wide range of stimuli. Cortical neurons respond to more complex stimulus properties – such as correlated motion across whiskers – than those at early subcortical stages. Temporal integration along the pathway is comparatively weak: neurons up to barrel cortex are sensitive mainly to fast (tens of milliseconds) fluctuations in whisker motion. The topographic organization of whisker sensitivity is paralleled by systematic organization of neuronal selectivity to certain other physical features, but selectivity to touch and to dynamic stimulus properties is distributed in “salt-and-pepper” fashion