Surface smoothing of additively manufactured Ti-6Al-4V alloy by combination of grit blasting and large-area electron beam irradiation

Additively manufactured (AMed) titanium products are typically produced by electron beam melting (EBM), since oxidation of titanium alloy surface can be suppressed in vacuum environment. The surface roughness of AMed titanium products becomes more than 200 µm Rz, and the very rough surface would lead to reduction in fatigue strength. Therefore, a post surface finishing process is required. Abrasive blasting is one of the common surface smoothing processes of AMed metal products. Large surface roughness can be decreased, and compressive residual stress can be introduced to the surface. However, there is a limitation to reduction of surface roughness to several µm Rz. On the other hand, it was recently found that AMed metal surface produced by powder bed fusion with laser beam could be smoothed by large-area electron beam (LEB) irradiation. However, it is difficult to smooth surface with large initial surface roughness, and a tensile residual stress may be generated on the surface. In this study, surface smoothing and change in residual stress of AMed titanium alloy (Ti-6Al-4 V) were proposed by combination of grit blasting and LEB irradiation. Surface roughness of AMed Ti-6Al-4 V alloy significantly decreases from 265 to about 2.0 µm Rz by combination of grit blasting and LEB irradiation. Reduction rate of surface roughness by LEB irradiation linearly increases with decreasing mean width of blasted surface. Influence of the mean width on smoothing effect by LEB irradiation can be explained by thermo-fluid analysis. Moreover, tensile residual stress caused by LEB irradiation can be reduced when LEB is irradiated to blasted surface

Facile synthesis of > 99% phase-pure brookite TiO 2 by hydrothermal conversion from Mg 2 TiO 4

The synthesis of pure brookite is generally much more difficult than that of pure anatase. The hydrothermal conversion, recently developed by Kozawa et al., is a facile method to synthesize brookite TiO2 from inverse spinel-type Mg2TiO4 under a mild hydrothermal condition e.g. in 1 M HCl solution at 100 °C. However, slight rutile TiO2 is usually co-existed under the reported conditions. The aim of this study is to prepare a high-purity brookite TiO2 powder by the hydrothermal conversion from Mg2TiO4. We investigated the conditions of Mg2TiO4 preparation and hydrothermal conversion, and it was found that the most important factor for the high-purity brookite synthesis, i.e. decreasing the co-existing rutile TiO2, was to prepare the Mg2TiO4 precursor without MgTiO3. Using an MgO-rich composition and adding a second calcination step for the Mg2TiO4 preparation yielded a high-purity (99.3 wt%) brookite powder with a surface area of 27.7 m2/g. Under the current experimental conditions, addition of a surfactant or an alcohol for the hydrothermal treatment was not apparently effective for the high-purity brookite synthesis

Element Stratification in the Middle-Aged Type Ia Supernova Remnant G344.7-0.1

Despite their importance, a detailed understanding of Type Ia supernovae (SNe Ia) remains elusive. X-ray measurements of the element distributions in supernova remnants (SNRs) offer important clues for understanding the explosion and nucleosynthesis mechanisms for SNe Ia. However, it is challenging to observe the entire ejecta mass in X-rays for young SNRs, because the central ejecta may not have been heated by the reverse shock yet. Here we present over 200 kilosecond Chandra observations of the Type Ia SNR G344.7-0.1, whose age is old enough for the reverse shock to have reached the SNR center, providing an opportunity to investigate the distribution of the entire ejecta mass. We reveal a clear stratification of heavy elements with a centrally peaked distribution of the Fe ejecta surrounded by intermediate-mass elements (IMEs: Si, S, Ar Ca) with an arc-like structure. The centroid energy of the Fe K emission is marginally lower in the central Fe-rich region than in the outer IME-rich regions, suggesting that the Fe ejecta were shock-heated more recently. These results are consistent with the prediction for standard SN Ia models, where the heavier elements are synthesized in the interior of an exploding white dwarf. We find, however, that the peak location of the Fe K emission is slightly offset to the west with respect to the geometric center of the SNR. This apparent asymmetry is likely due to the inhomogeneous density distribution of the ambient medium, consistent with our radio observations of the ambient molecular and neutral gas.Comment: 16 pages, 10 figures, Accepted for publication in Astrophysical Journa

A phase diagram of the pinch-off-type behavior of impulsively-induced viscoelastic liquid jets

In this study, we systematically investigate the jet behaviors of viscoelastic liquids, focusing on the region of high velocity and high viscoelasticity, which has not been investigated in previous studies. We generate viscoelastic jets using an impulsive force and categorize the resulting jets into two types: pinch-off jets (jets that break up during elongation after ejection) and no-pinch-off jets (jets that pull back to the nozzle after maximum elongation or jets that return without elongation after ejection). We then propose criteria to characterize these regions using the Weissenberg number and the Reynolds number, which are dimensionless numbers composed of the rheological properties of the solution and the initial conditions of the jet injection. It is found that pinch-off jets occur at $Re \gtrsim 23.4Wi$ in regions of high elasticity $Wi \gtrsim 10$, and at $Re \gtrsim 250$ in regions of low elasticity $Wi \lesssim 10$. We also show that the phase diagram can be explained by modeling a focused jet using the finitely extensible non-linear elastic dumbbell model with the Chilcott-Rallison closure approximation (FENE-CR)

Learning to Select, Track, and Generate for Data-to-Text

We propose a data-to-text generation model with two modules, one for tracking and the other for text generation. Our tracking module selects and keeps track of salient information and memorizes which record has been mentioned. Our generation module generates a summary conditioned on the state of tracking module. Our model is considered to simulate the human-like writing process that gradually selects the information by determining the intermediate variables while writing the summary. In addition, we also explore the effectiveness of the writer information for generation. Experimental results show that our model outperforms existing models in all evaluation metrics even without writer information. Incorporating writer information further improves the performance, contributing to content planning and surface realization.Comment: ACL 201

Structural and functional insights into thermally stable cytochrome c' from a thermophile

Thermophilic Hydrogenophilus thermoluteolus cytochrome c0 (PHCP) exhibits higher thermal stability than a mesophilic counterpart, Allochromatium vinosum cytochrome c0 (AVCP), which has a homo-dimeric structure and ligand-binding ability. To understand the thermal stability mechanism and ligand-binding ability of the thermally stable PHCP protein, the crystal structure of PHCP was first determined. It formed a homo-dimeric structure, the main chain root mean square deviation (rmsd) value between PHCP and AVCP being 0.65 A ° . In the PHCP structure, six specific residues appeared to strengthen the heme-related and subunit–subunit interactions, which were not conserved in the AVCP structure. PHCP variants having altered subunit–subunit interactions were more severely destabilized than ones having altered heme-related interactions. The PHCP structure further revealed a ligand-binding channel and a penta-coordinated heme, as observed in the AVCP protein. A spectroscopic study clearly showed that some ligands were bound to the PHCP protein. It is concluded that the dimeric PHCP from the thermophile is effectively stabilized through heme-related and subunit–subunit interactions with conservation of the ligand-binding ability.This work was performed under the Cooperative Research Program of the “Network Joint Research Center for Materials and Devices”

The fungal metabolite (+)-terrein abrogates osteoclast differentiation via suppression of the RANKL signaling pathway through NFATc1

Pathophysiological bone resorption is commonly associated with periodontal disease and involves the excessive resorption of bone matrix by activated osteoclasts. Receptor activator of nuclear factor (NF)-κB ligand (RANKL) signaling pathways have been proposed as targets for inhibiting osteoclast differentiation and bone resorption. The fungal secondary metabolite (+)-terrein is a natural compound derived from Aspergillus terreus that has previously shown anti-interleukin-6 properties related to inflammatory bone resorption. However, its effects and molecular mechanism of action on osteoclastogenesis and bone resorption remain unclear. In the present study, we showed that 10 µM synthetic (+)-terrein inhibited RANKL-induced osteoclast formation and bone resorption in a dose-dependent manner and without cytotoxicity. RANKL-induced messenger RNA expression of osteoclast-specific markers including nuclear factor of activated T-cells cytoplasmic 1 (NFATc1), the master regulator of osteoclastogenesis, cathepsin K, tartrate-resistant acid phosphatase (Trap) was completely inhibited by synthetic (+)-terrein treatment. Furthermore, synthetic (+)-terrein decreased RANKL-induced NFATc1 protein expression. This study revealed that synthetic (+)-terrein attenuated osteoclast formation and bone resorption by mediating RANKL signaling pathways, especially NFATc1, and indicated the potential effect of (+)-terrein on inflammatory bone resorption including periodontal disease

The Fungal Metabolite (+)-Terrein Abrogates Ovariectomy-Induced Bone Loss and Receptor Activator of Nuclear Factor-kappa B Ligand-Induced Osteoclastogenesis by Suppressing Protein Kinase-C alpha/beta II Phosphorylation

Osteoporosis is a common disease characterized by a systemic impairment of bone mass and microarchitecture that results in fragility fractures. Severe bone loss due to osteoporosis triggers pathological fractures and consequently decreases the daily life activity and quality of life. Therefore, prevention of osteoporosis has become an important issue to be addressed. We have reported that the fungal secondary metabolite (+)-terrein (TER), a natural compound derived from Aspergillus terreus, has shown receptor activator of nuclear factor-kappa B ligand (RANKL)-induced osteoclast differentiation by suppressing nuclear factor of activated T-cell 1 (NFATc1) expression, a master regulator of osteoclastogenesis. TER has been shown to possess extensive biological and pharmacological benefits; however, its effects on bone metabolism remain unclear. In this study, we investigated the effects of TER on the femoral bone metabolism using a mouse-ovariectomized osteoporosis model (OVX mice) and then on RANKL signal transduction using mouse bone marrow macrophages (mBMMs). In vivo administration of TER significantly improved bone density, bone mass, and trabecular number in OVX mice (p < 0.01). In addition, TER suppressed TRAP and cathepsin-K expression in the tissue sections of OVX mice (p < 0.01). In an in vitro study, TER suppressed RANKL-induced phosphorylation of PKC alpha/beta II, which is involved in the expression of NFATc1 (p < 0.05). The PKC inhibitor, GF109203X, also inhibited RANKL-induced osteoclastogenesis in mBMMs as well as TER. In addition, TER suppressed the expression of osteoclastogenesis-related genes, such as Ocstamp, Dcstamp, Calcr, Atp6v0d2, Oscar, and Itgb3 (p < 0.01). These results provide promising evidence for the potential therapeutic application of TER as a novel treatment compound against osteoporosis