Vertically aligned InGaN nanowires with engineered axial In composition for highly efficient visible light emission.

We report on the fabrication of novel InGaN nanowires (NWs) with improved crystalline quality and high radiative efficiency for applications as nanoscale visible light emitters. Pristine InGaN NWs grown under a uniform In/Ga molar flow ratio (UIF) exhibited multi-peak white-like emission and a high density of dislocation-like defects. A phase separation and broad emission with non-uniform luminescent clusters were also observed for a single UIF NW investigated by spatially resolved cathodoluminescence. Hence, we proposed a simple approach based on engineering the axial In content by increasing the In/Ga molar flow ratio at the end of NW growth. This new approach yielded samples with a high luminescence intensity, a narrow emission spectrum, and enhanced crystalline quality. Using time-resolved photoluminescence spectroscopy, the UIF NWs exhibited a long radiative recombination time (τr) and low internal quantum efficiency (IQE) due to strong exciton localization and carrier trapping in defect states. In contrast, NWs with engineered In content demonstrated three times higher IQE and a much shorter τr due to mitigated In fluctuation and improved crystal quality

Three-dimensional flow phenomena in a wire-wrapped 37-pin fuel bundle for SFR

AbstractThree-dimensional flow phenomena in a wire-wrapped 37-pin fuel assembly mock-up of a Japanese loop-type sodium-cooled fast reactor, Monju, were investigated with a numerical analysis using a general-purpose commercial computational fluid dynamics code, CFX. Complicated and vortical flow phenomena in the wire-wrapped 37-pin fuel assembly were captured by a Reynolds-averaged Navier–Stokes flow simulation using a shear stress transport turbulence model. The main purpose of the current study is to understand the three-dimensional complex flow phenomena in a wire-wrapped fuel assembly to support the license issue for the core design. Computational fluid dynamics results show good agreement with friction factor correlation models. The secondary flow in the corner and edge subchannels is much stronger than that in an interior subchannel. The axial velocity averaged in the corner and edge subchannels is higher than that averaged in the interior subchannels. Three-dimensional multiscale vortex structures start to be formed by an interaction between secondary flows around each wire-wrapped pin. Behavior of the large-scale vortex structures in the corner and edge subchannels is closely related to the relative position between the hexagonal duct wall and the helically wrapped wire spacer. The small-scale vortex is axially developed in the interior subchannels. Furthermore, a driving force on each wire spacer surface is closely related to the relative position between the hexagonal duct wall and the wire spacer

Two distinct red giant branch populations in the globular cluster NGC 2419 as tracers of a merger event in the Milky Way

Recent spectroscopic observations of the outer halo globular cluster (GC) NGC 2419 show that it is unique among GCs, in terms of chemical abundance patterns, and some suggest that it was originated in the nucleus of a dwarf galaxy. Here we show, from the Subaru narrow-band photometry employing a calcium filter, that the red giant-branch (RGB) of this GC is split into two distinct subpopulations. Comparison with spectroscopy has confirmed that the redder RGB stars in the $hk$[=(Ca$-b)-(b-y)$] index are enhanced in [Ca/H] by $\sim$0.2 dex compared to the bluer RGB stars. Our population model further indicates that the calcium-rich second generation stars are also enhanced in helium abundance by a large amount ($\Delta$Y = 0.19). Our photometry, together with the results for other massive GCs (e.g., $\omega$ Cen, M22, and NGC 1851), suggests that the discrete distribution of RGB stars in the $hk$ index might be a universal characteristic of this growing group of peculiar GCs. The planned narrow-band calcium photometry for the Local Group dwarf galaxies would help to establish an empirical connection between these GCs and the primordial building blocks in the hierarchical merging paradigm of galaxy formation.Comment: 4 pages, 4 figures, 1 table, accepted for the publication in ApJ

Intracellular Membrane Association of the Aplysia cAMP Phosphodiesterase Long and Short Forms via Different Targeting Mechanisms

Phosphodiesterases (PDEs) play key roles in cAMP compartmentalization, which is required for intracellular signaling processes, through specific subcellular targeting. Previously, we showed that the long and short forms of Aplysia PDE4 (ApPDE4), which are localized to the membranes of distinct subcellular organelles, play key roles in 5-hydroxytryptamineinduced synaptic facilitation in Aplysia sensory and motor synapses. However, the molecular mechanism of the isoform-specific distinct membrane targeting was not clear. In this study, we further investigated the molecular mechanism of the membrane targeting of the ApPDE4 long and short forms. We found that the membrane targeting of the long form was mediated by hydrophobic interactions, mainly via 16 amino acids at the N-terminal region, whereas the short form was targeted solely to the plasma membrane, mainly by nonspecific electrostatic interactions between theirNtermini and the negatively charged lipids such as the phosphatidylinositol polyphosphates PI4P and PI(4,5)P<inf>2</inf>, which are embedded in the inner leaflet of the plasma membrane. Moreover, oligomerization of the long or short form by interaction of their respective upstream conserved region domains, UCR1 and UCR2, enhanced their plasma membrane targeting. These results suggest that the long and short forms of ApPDE4 are distinctly targeted to intracellular membranes through their direct association with the membranes via hydrophobic and electrostatic interactions, respectively. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.1

Progress in Understanding and Sequencing the Genome of Brassica rapa

Brassica rapa, which is closely related to Arabidopsis thaliana, is an important crop and a model plant for studying genome evolution via polyploidization. We report the current understanding of the genome structure of B. rapa and efforts for the whole-genome sequencing of the species. The tribe Brassicaceae, which comprises ca. 240 species, descended from a common hexaploid ancestor with a basic genome similar to that of Arabidopsis. Chromosome rearrangements, including fusions and/or fissions, resulted in the present-day “diploid” Brassica species with variation in chromosome number and phenotype. Triplicated genomic segments of B. rapa are collinear to those of A. thaliana with InDels. The genome triplication has led to an approximately 1.7-fold increase in the B. rapa gene number compared to that of A. thaliana. Repetitive DNA of B. rapa has also been extensively amplified and has diverged from that of A. thaliana. For its whole-genome sequencing, the Brassica rapa Genome Sequencing Project (BrGSP) consortium has developed suitable genomic resources and constructed genetic and physical maps. Ten chromosomes of B. rapa are being allocated to BrGSP consortium participants, and each chromosome will be sequenced by a BAC-by-BAC approach. Genome sequencing of B. rapa will offer a new perspective for plant biology and evolution in the context of polyploidization

One-Step Fabrication of Hierarchically Structured Silicon Surfaces and Modification of Their Morphologies Using Sacrificial Layers

Fabrication of one-dimensional nanostructures is a key issue for optical devices, fluidic devices, and solar cells because of their unique functionalities such as antireflection and superhydrophobicity. Here, we report a novel one-step process to fabricate patternable hierarchical structures consisting of microstructures and one-dimensional nanostructures using a sacrificial layer. The layer plays a role as not only a micromask for producing microstructures but also as a nanomask for nanostructures according to the etching time. Using this method, we fabricated patterned hierarchical structures, with the ability to control the shape and density of the nanostructure. The various architectures provided unique functionalities. For example, our sacrificial-layer etching method allowed nanostructures denser than what would be attainable with conventional processes to form. The dense nanostructure resulted in a very low reflectance of the silicon surface (less than 1%). The nanostructured surface and hierarchically structured surface also exhibited excellent antiwetting properties, with a high contact angle (>165°) and low sliding angle (<1°). We believe that our fabrication approach will provide new insight into functional surfaces, such as those used for antiwetting and antireflection surface applications

Comparison of Clinical Outcomes Following Gefitinib and Erlotinib Treatment in Non–Small-Cell Lung Cancer Patients Harboring an Epidermal Growth Factor Receptor Mutation in Either Exon 19 or 21

Background:Gefitinib and erlotinib, small-molecule kinase inhibitors that block epidermal growth factor receptor (EGFR) signaling, have demonstrated a dramatic response rate and prolonged progression-free survival (PFS) in patients harboring an activating EGFR mutation. We compared the clinical outcomes in gefitinib- and erlotinib-treated patients harboring EGFR mutations who had recurrent or metastatic non–small-cell lung cancer (NSCLC).Methods:A total of 375 patients with recurrent or metastatic stage IIIB/IV NSCLC, who had either exon 19 deletion or the L858R mutation in exon 21, and had received either gefitinib (n = 228) or erlotinib (n = 147), were included in the study. A matched-pair case-control study design was implemented in the analysis, where 121 pairs of gefitinib-treated and erlotinib-treated patients were matched according to sex, smoking history, Eastern Cooperative Oncology Group performance status, and types of EGFR mutation.Results:The median age of all patients was 58 years (range, 30–84), and more than half of patients had never been smokers (63.6%). Most patients had adenocarcinoma (98.3%) and good Eastern Cooperative Oncology Group performance status (0, 1) (90.9%). The median number of cycles of EGFR tyrosine kinase inhibitor (TKI) treatment was 12.7 in the gefitinib group and 10.8 in the erlotinib group. Of the 242 patients, 63 (26%) received EGFR TKI as first-line therapy. The overall response rates and disease control rates in the gefitinib- or erlotinib-treated groups were 76.9% versus 74.4% (p = 0.575) and 90.1% versus 86.8%, respectively (p = 0.305). There was no statistically significant difference with regard to PFS (median, 11.7 versus 9.6; p = 0.056) between the gefitinib- and erlotinib-treated groups. For patients receiving EGFR TKI as the first-line treatment, there was no significant difference between the two treatment groups in overall response rates (76.7% and 90.0%) (p = 0.431) and median PFS (11.7 versus 14.5 months) (p = 0.507).Conclusion:In NSCLC patients harboring EGFR mutation, treatment with gefitinib and erlotinib resulted in similar effectiveness