Visualization of charges stored in the floating gate of flash memory by scanning nonlinear dielectric microscopy

By applying scanning nonlinear dielectric microscopy (SNDM), we succeeded in clarifying that electrons existed in the poly-Si layer of the floating gate of a flash memory. The charge accumulated in the floating gate can be detected by SNDM as a change in the capacitance of the poly-Si (floating gate) by scanning the surface of the SiO(2)-SiN(4)-SiO(2) (ONO) film covering the floating gate. There was a clear black contrast region in the SNDM image of the floating gate area, where electrons were injected. However, no clear contrast appeared in the floating gate where electrons were not injected. We confirmed that SNDM is one of the most useful methods of observing the charge accumulated in flash memory.     

The Role of Leaky Gut in Nonalcoholic Fatty Liver Disease: A Novel Therapeutic Target

The liver directly accepts blood from the gut and is, therefore, exposed to intestinal bacteria. Recent studies have demonstrated a relationship between gut bacteria and nonalcoholic fatty liver disease (NAFLD). Approximately 10–20% of NAFLD patients develop nonalcoholic steatohepatitis (NASH), and endotoxins produced by Gram-negative bacilli may be involved in NAFLD pathogenesis. NAFLD hyperendotoxicemia has intestinal and hepatic factors. The intestinal factors include impaired intestinal barrier function (leaky gut syndrome) and dysbiosis due to increased abundance of ethanol-producing bacteria, which can change endogenous alcohol concentrations. The hepatic factors include hyperleptinemia, which is associated with an excessive response to endotoxins, leading to intrahepatic inflammation and fibrosis. Clinically, the relationship between gut bacteria and NAFLD has been targeted in some randomized controlled trials of probiotics and other agents, but the results have been inconsistent. A recent randomized, placebo-controlled study explored the utility of lubiprostone, a treatment for constipation, in restoring intestinal barrier function and improving the outcomes of NAFLD patients, marking a new phase in the development of novel therapies targeting the intestinal barrier. This review summarizes recent data from studies in animal models and randomized clinical trials on the role of the gut–liver axis in NAFLD pathogenesis and progression.     

Gene expression property of high-density three-dimensional tissue of HepG2 cells formed in radial-flow bioreactor

In our previous study, we examined three-dimensional culture using 5-ml radial-flow bioreactor (RFB) and showed that genes encoding cell cycle related proteins were suppressed in a stable phase. In this study, we analyzed the gene expression profiles of RFB-cultivated HepG2 cells and found that vascular endothelial growth factor (VEGF) production was strongly induced in the stable phase compared with the growth phase or static two-dimensional culture. When human umbilical vein endothelial cells (HUVECs) were grown under the conditioned medium of the stable phase, it was found that the formation of new blood vessels was induced in the angiogenesis model. DNA microarray analysis showed that the expression levels of both genes related to cell cycle arrest and which are known as tumor markers have increased in the stable phase. This result suggests that HepG2 cells in the stable phase maintain an active tumor phenotype. In addition, the expression of genes induced in the hypoxic condition was also induced in the stable phase. When the culture was carried out under a higher dissolved oxygen (DO) concentration, VEGF production did not decrease significantly and the new blood-vessel-forming ability of the conditioned medium was not suppressed. This suggests that the induction of VEGF production in a stable phase is not affected by DO during the tested level. These results suggest that the RFB cell culture system may be used to assess tumor progression mechanism under three-dimensional condition in vitro.     

Bubble lattice formation in thick MnBi platelet by one-point nucleation

The dynamic domain formations in a single crystal MnBi platelet were examined under various external field strengths. Once the reverse domain is nucleated at one point of the saturated plate by pricking or external pulse field, the domain expands with various modes depending on the net field strength acting on the moving wall and forms various patterns. In a thick platelet, a bubble lattice is produced with no bias field, but it is suppressed by the external field; a radial stripe domain pattern or a spider web like pattern is formed depending on the field polarity. The phase velocity of the wall propagation during lattice formation was estimated as about 50m/sec by the pulse field method. This result brought us the important information about the truly complicated nature of the bubble lattice formation, i.e., the sequential process of the dynamic conversion, breakdown of velocity, static conversion, high speed propagation, and sharp deflection.     

Spontaneous Formation of Uniform Cell-Sized Microgels through Water/Water Phase Separation

In this study, a one-step method is discussed for producing uniform cell-sized microgels using glass capillaries filled with a binary polymer blend of polyethylene glycol (PEG) and gelatin. Upon decreasing temperature, phase separation of the PEG/gelatin blends and gelation of gelatin occur, and then the polymer blend forms linearly aligned, uniformly sized gelatin microgels in the glass capillary. When DNA is added to the polymer solution, gelatin microgels entrapping DNA are spontaneously formed, and the DNA prevents the coalescence of the microdroplets even at temperatures above the melting point. This novel method to form uniform cell-sized microgels may be applicable to other biopolymers. This method is expected to contribute to diverse materials science via biopolymer microgels and biophysics and synthetic biology through cellular models containing biopolymer gels.     

Green emitting β$\ubeta$-SiAlON:Eu2+ phosphors derived from chemically modified perhydropolysilazanes

We report the first synthesis of β-SiAlON:Eu²⁺ phosphors from single-source precursors, perhydropolysilazane (PHPS), chemically modified with Al(OCH(CH₃)₂)₃, and EuCl₂. The reactions occurring during the precursor synthesis and the subsequent thermal conversion of polymeric precursors into β-SiAlON:Eu²⁺ phosphors have been studied by a complementary set of analytical techniques, including infrared spectroscopy, gas chromatography–mass spectrometry, thermogravimetry–mass spectrometry, X-ray diffraction (XRD), photoluminescence spectroscopy, and scanning electron microscopy. It has been clearly established that Al(OCH(CH₃)₂)₃ immediately reacted with PHPS to afford N–Al bonds at room temperature, whereas N–Eu bond formation was suggested to proceed above 600°C accompanied by the elimination of HCl up to 1000°C in flowing N₂. The subsequent 1800°C-heat treatment for 1 h under an N₂ gas pressure at 980 kPa allowed converting the single-source precursors into fine-grained β-SiAlON:Eu²⁺ phosphors. XRD analysis revealed that the Al/Si of .09 was the critical atomic ratio in the precursor synthesis to afford single-phase β-SiAlON (z = .55). Moreover, Eu²⁺-doping was found to efficiently reduce the carbon impurity in the host β-SiAlON. The polymer-derived β-SiAlON:Eu²⁺ phosphors exhibited green emission under excitation at 460 nm and achieved the highest green emission intensity at the critical dopant Eu²⁺ concentration at 1.48 at%.     

In situ Raman spectroscopy analysis of local structure in dry gel for zeolite beta synthesis

To investigate faster crystallization of zeolite beta by the dry-gel conversion method, the local structure of the dry gel before synthesis was quantitatively evaluated using in situ Raman spectroscopy during the drying process. The dry gel prepared from Si and Al sources, and tetraethylammonium hydroxide solution was crystallized after several hours by the dry-gel conversion method. The conformational change of TEA⁺ cations was observed during the drying process by the deconvolution of the spectrum, and the conformational change was larger than that during the synthesis process. The rate of conformational change was increased with the drying temperature, and the apparent activation energy was estimated to be 68.2 kJ/mol. The generation and transformation of double three-membered silicate rings (D3Rs) and 4-2 type secondary building units (SBUs), which are essential for the crystallization of zeolite beta, were observed during the drying process. The transformation from D3R to 4-2 SBU in the dry gel during drying process could be confirmed quantitatively by the difference of the time variation for the amounts of these silicate building units estimated by in situ observation.     

Connection of nonlinear model predictive controllers for smooth task switching in autonomous driving

Motion planning, decision making, and control are vital functions in autonomous driving for accomplishing the desired driving task while considering passenger comfort, road infrastructure, and surrounding traffic participants. Model predictive control (MPC) is a promising method for simultaneously realizing these functions. However, formulating a single MPC that can run through all driving scenarios is difficult, and previous research has often been conducted to design an MPC for a specific driving task. To extend the availability of MPC for all driving tasks, smooth switching between different MPCs designed for each driving task must be addressed. One of the difficulties in switching between MPCs is guiding the state to a feasible set of optimization problems after switching. In this paper, we present a new framework to realize the smooth connection of MPCs, that is, to reduce the optimization infeasibility at the time of MPC switching. In our proposed method, two general nonlinear MPCs with different state spaces, cost functions, constraints, and formulations can be systematically switched via automatically generated intermediate-MPCs without requiring any particular alterations. This can help reduce the system complexity of the hybrid MPC system.     

Gas permeation and thermomechanical properties for macroporous alumina focused on necking size at grain boundaries

The gas permeation and thermomechanical properties of macroporous alumina used as a support substrate for microporous ceramic permselective membranes were investigated. The porosity, pore size, and apparent necking size between grains of macroporous alumina were systematically varied, and the relationships between the porous microstructure and material properties were examined. The grain necking size at alumina grain boundaries was evaluated by microstructural observations. The nitrogen gas permeance of the porous alumina increased with increasing pore size. All the measured thermal and mechanical properties decreased with increasing porosity. The properties of porous alumina samples with extensive grain necking showed higher values even in samples with the largest pore size. The high thermal conductivity of porous alumina with extensive grain necking was due to the low interfacial thermal resistance at grain boundaries. Porous alumina with extensive grain necking had high thermal shock strength due to the higher thermal conductivity. It was demonstrated that a porous structure combining high gas permeability and excellent fracture resistance could be successfully achieved.     

Asymmetric Hydrogenation of Ketones with Polymer‐Bound BINAP/Diamine Ruthenium Catalysts

The BINAP/1,2‐diphenylethylenediamine RuCl₂ complexes bound to a polystyrene resin act as precatalysts for asymmetric hydrogenation of various simple ketones. The enantioselectivity, turnover number, and turnover frequency are comparable to those attained under homogeneous conditions.