Powder flowability affects dynamic powder behavior during additive manufacturing and varies depending on particle size distribution, particle morphology, and surface features. In this study, Inconel ...718 alloy powders were prepared by gas atomization (GA), plasma atomization (PA), and plasma rotating electrode process (PREP). The flowability was experimentally evaluated by the avalanche angle. With the help of numerical simulations, the individual effects of particle size distribution, particle morphology, and particle surface features on flowability were analyzed. The results showed that the PREP powder possessed the best flowability among the three powders. The PSDs were slightly different, but these differences had almost no effect on their flowability. Nevertheless, the excellent flowability of the PREP powder was due to the high particle sphericity and the thin surface oxide film. If the environmental factors are well controlled during the handling, PREP has a natural advantage over GA and PA in terms of flowability.
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•Flowability of powders for AM was evaluated by experiment and simulation.•Effects of PSD, particle morphology and surface feature on flowability were evaluated.•Surface roughness that correlated to the oxidation altered powder flowability.•High sphericity and thin oxide film contributed to the superb flowability of PREP powder.
Amperometric flow injection analysis (FIA) biosensors were developed by using various biomolecules-modified carbon felt (CF) as a working electrode unit of flow-through electrochemical cell-based FIA ...detector. The CF is a micro-electrode ensemble of micro-carbon fiber (ca. 7 μm diameter) that possesses a three-dimensional random structure. The CF has high conductivity and a large effective surface area, which allows large measurable current density and high electrolytic efficiency. In addition, a high porosity of CF (> 90 %) permits a low diffusion barrier of solution-flow. Four enzymes (tyrosinase, peroxidase, glucose oxidase, uricase), heme proteins (myoglobin, hemoglobin) and hemin were immobilized on the CF surface by chemical modification and physical adsorption. The developed FIA biosensors are divided into the following categories: 1) Tyrosinase (polyphenol oxidase)-modified CF for highly sensitive amperometric flow determination of phenol and catechol compounds, based on signal amplification due to the enzymatic/electrochemical redox recycling; 2) Peroxidase-modified CF for the amperometric flow determination of H2O2 based on direct electron transfer (DET)-based bioelectrocatalysis; 3) Oxidases (glucose oxidase and uricase)-modified CF-based enzyme reactors coupled with peroxidase-CF for amperometric flow determination of glucose and uric acid; 4) Hemin-modified CF for amperometric flow determination of dissolved oxygen (DO), based on an electrocatalytic activity of hemin for the reduction of DO; 5) Heme-proteins-modified CFs for the amperometric flow determination of respiratory toxins (N3− and CN−), based on reversible inhibition of toxins on bioelectrocatalytic activity of heme-proteins for the reduction of DO. These FIA biosensors do not need any indication reagents, sample-pretreatment and column separation, because biomolecules immobilized on the CF surface possesses highly selective bio-specificity and specific bio-affinities, which allows simple and consecutive analysis of many samples. Therefore, in future, these FIA biosensors can be expected to be applied to on-line automated analysis systems coupled with advanced IoT and AI technology.
Non-linear microscopy, such as multi-photon excitation microscopy, offers spatial localities of excitations, thereby achieving 3D cross-sectional imaging with low phototoxicity even in thick ...biological specimens. We had developed a multi-point scanning two-photon excitation microscopy system using a spinning-disk confocal scanning unit. However, its severe color cross-talk has precluded multi-color simultaneous imaging. Therefore, in this study, we introduced a mechanical switching system to select either of two NIR laser light pulses and an image-splitting detection system for 3- or 4-color imaging. As a proof of concept, we performed multi-color fluorescent imaging of actively dividing human HeLa cells and tobacco BY-2 cells. We found that the proposed microscopy system enabled time-lapse multi-color 3D imaging of cell divisions while avoiding photodamage. Moreover, the application of a linear unmixing method to the 5D dataset enabled the precise separation of individual intracellular components in multi-color images. We thus demonstrated the versatility of our new microscopy system in capturing the dynamic processes of cellular components that could have multitudes of application.
In the Xenopus laevis intestine during metamorphosis, stem cells appear and generate the adult epithelium analogous to the mammalian one. We have previously shown that connective tissue cells ...surrounding the epithelium are essential for the stem cell development. To clarify whether such cells correspond to mammalian Foxl1-expressing mesenchymal cells, which have recently been shown to be a critical component of intestinal stem cell niche, we here examined the expression profile of Foxl1 in the X. laevis intestine by using RT-PCR and immunohistochemistry. Foxl1 expression was transiently upregulated only in connective tissue cells during the early period of metamorphic climax and was the highest just beneath the proliferating stem/progenitor cells. In addition, electron microscopic analysis showed that these subepithelial cells are ultrastructurally identified as telocytes like the mammalian Foxl1-expressing cells. Furthermore, we experimentally showed that Foxl1 expression is indirectly upregulated by thyroid hormone (TH) through Shh signaling and that TH organ-autonomously induces the Foxl1-expressing cells concomitantly with appearance of the stem cells in the tadpole intestine in vitro. The present results suggest that intestinal niche cells expressing Foxl1 are evolutionally conserved among terrestrial vertebrates and can be induced by TH/Shh signaling during amphibian metamorphosis for stem cell development.
Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) is causing the global coronavirus disease 2019 (COVID‐19) pandemic. Because complete elimination of SARS‐CoV‐2 appears difficult, ...decreasing the risk of transmission is important. Treatment with 0.1 and 0.05 ppm ozone gas for 10 and 20 hr, respectively, decreased SARS‐CoV‐2 infectivity by about 95%. The magnitude of the effect was dependent on humidity. Treatment with 1 and 2 mg/L ozone water for 10 s reduced SARS‐CoV‐2 infectivity by about 2 and 3 logs, respectively. Our results suggest that low‐dose ozone, in the form of gas and water, is effective against SARS‐CoV‐2.
•The probability of having a work-related accident rises with a worker’s age.•Occupational accidents are more likely to cause death to sufferers in their 60s or later.•The impact of age on ...work-related accidents has remained almost constant during the late 2000s and 2010s.
As a result of recent government policies, Japanese firms have a growing number of elderly workers. However, little attention has been given to the various costs of an aging workforce, one of which is an increase in occupational accidents. Based on the industry-aggregated data and publicly available administrative individual-level data from the late 2000s, during which many policies aimed at promoting elderly employment have been implemented, this study investigates whether the probability of having a work-related accident rises with a worker’s age and whether injury (or illness) due to an accident is more likely to be fatal when the worker is older. We found a positive and statistically significant impact of a worker’s age on the probability of having a work-related accident, after controlling for factors such as industry and firm size. We also found that occupational accidents are more likely to cause death to sufferers in their 60 s or later. However, the impact of age on work-related accidents has remained almost unchanged throughout the period of our analysis.
The development of cells specialized for water conduction or support is a striking innovation of plants that has enabled them to colonize land. The NAC transcription factors regulate the ...differentiation of these cells in vascular plants. However, the path by which plants with these cells have evolved from their nonvascular ancestors is unclear. We investigated genes of the moss Physcomitrella patens that encode NAC proteins. Loss-of-function mutants formed abnormal water-conducting and supporting cells, as well as malformed sporophyte cells, and overexpression induced ectopic differentiation of water-conducting–like cells. Our results show conservation of transcriptional regulation and cellular function between moss and Arabidopsis thaliana water-conducting cells. The conserved genetic basis suggests roles for NAC proteins in the adaptation of plants to land.
•Kinked crack angle and strain energy release rate after crack initiation are achieved.•Magneto elastic stress subjected to uniform magnetic field intensity is analyzed.•Cavities with arbitrary shape ...can be solved by changing a rational mapping function.•Three ways to solve the present problem are stated.•It is stated from Faraday’s law that the present problem is a pure shear stress one.
A kinked crack initiating from an initial crack in an infinite plate of a soft ferromagnetic and paramagnetic elastic materials is analyzed. Uniform magnetic field intensity applies at the remote area in the plate. Paramagnetic and soft ferromagnetic elastic materials can be belonged to the linear magneto-elastic material. Three ways analyzing this magneto-elastic stress problem are stated, which use ferromagnetic field intensity, paramagnetic field intensity and stress field derived from Faraday’s law of magnetic force line (uniform pure shear stress state), respectively. These three ways give the same result which is a uniform pure shear stress state.
The kinked crack angles θ just after the crack initiation are achieved for any direction δ of the magnetic field intensity. The directions for 0⩽δ⩽360° are considered. The following three criteria for the crack initiation are considered; (1) The kinked crack initiates in the direction taking maximum value of the Mode I stress intensity factor just after the crack initiation under the additional condition that the Mode I stress intensity factor is positive; (2) The kinked crack initiates in the direction satisfying Mode II stress intensity factor is zero; (3) The kinked crack initiates in the direction taking the maximum value of the strain energy release rate under the additional condition that the Mode I stress intensity factor is positive. It is found that the initiating angles exist in the range of -150°⩽θ⩽150°. It is stated that these criteria give the same results for the kinked crack angles. The distributions of the magnetic field intensity and the stress are investigated for some kinked crack angles and directions of magnetic field intensity. The stress intensity factors for some directions of magnetic field intensity are also investigated versus the crack length for some kinked crack angles.
Enantiomerically pure amino acid derivatives could be foundational compounds for peptide drugs. Deracemization of racemates to l-amino acid derivatives can be achieved through the reaction of evolved ...d-amino acid oxidase and chemical reductants, whereas deracemization to d-amino acid derivatives has not progressed due to the difficulty associated with the heterologous expression of l-amino acid oxidase (LAAO). In this study, we succeeded in developing an ancestral LAAO (AncLAAO) bearing broad substrate selectivity (13 l-amino acids) and high productivity through an Escherichia coli expression system (∼50.7 mg/L). AncLAAO can be applied to perform deracemization to d-amino acids in a similar way to deracemization to l-amino acids. In fact, full conversion (>99% ee, d-form) could be achieved for 16 racemates, including nine d,l-Phe derivatives, six d,l-Trp derivatives, and a d,l-phenylglycine. Taken together, we believe that AncLAAO could be a key enzyme to obtain optically pure d-amino acid derivatives in the future.
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