Intestinal absorption and biological effects of orally administered amorphous silica particles

Although amorphous silica nanoparticles are widely used in the production of food products (e.g., as anticaking agents), there is little information available about their absorption and biological effects after oral exposure. Here, we examined the in vitro intestinal absorption and in vivo biological effects in mice of orally administered amorphous silica particles with diameters of 70, 300, and 1,000 nm (nSP70, mSP300, and mSP1000, respectively) and of nSP70 that had been surface-modified with carboxyl or amine groups (nSP70-C and nSP70-N, respectively). Analysis of intestinal absorption by means of the everted gut sac method combined with an inductively coupled plasma optical emission spectrometer showed that the intestinal absorption of nSP70-C was significantly greater than that of nSP70. The absorption of nSP70-N tended to be greater than that of nSP70; however, the results were not statistically significant. Our results indicate that silica nanoparticles can be absorbed through the intestine and that particle diameter and surface properties are major determinants of the degree of absorption. We also examined the biological effects of the silica particles after 28-day oral exposure in mice. Hematological, histopathological, and biochemical analyses showed no significant differences between control mice and mice treated with the silica particles, suggesting that the silica nanoparticles evaluated in this study are safe for use in food production.     

Attribute-based quality classification of academic papers

Investigating the relevant literature is very important for research activities. However, it is difficult to select the most appropriate and important academic papers from the enormous number of papers published annually. Researchers search paper databases by combining keywords, and then select papers to read using some evaluation measure—often, citation count. However, the citation count of recently published papers tends to be very small because citation count measures accumulated importance. This paper focuses on the possibility of classifying high-quality papers superficially using attributes such as publication year, publisher, and words in the abstract. To examine this idea, we construct classifiers by applying machine-learning algorithms and evaluate these classifiers using cross-validation. The results show that our approach effectively finds high-quality papers.     

Electrical resistivity of Si3N4 ceramics with Yb2O3 additive

Si₃N₄ ceramics with excellent mechanical properties are used for heat dissipation substrates and so on. In order to improve their reliability and expand their application fields, it is desirable to understand and control the electrical properties of Si₃N₄ ceramics. In this study, the electrical resistivity of Si₃N₄ ceramics with Yb₂O₃ additive was investigated by applying various voltages at temperatures ranging from 25°C to 300°C. When Yb₂O₃ was added as a sintering aid to Si₃N₄ ceramics, a crystalline J-phase (Yb₄Si₂O₇N₂) was formed and their electrical resistivity was significantly lower than that of Y₂O₃ additive. The electrical resistivity of the Yb₂O₃-added ceramics decreased with an increase in temperature and applied voltage. Yb existed in multiple valence states, Yb²⁺ and Yb³⁺, in the Si₃N₄ ceramics and the decrease in the electrical resistivity can be attributed hopping conduction through the J-phase. The J-phase in the Si₃N₄ ceramics was observed to be continuous, and percolation analysis suggested that the J-phase formed an infinite cluster. Therefore, the decrease in the electrical resistivity of the Yb₂O₃-added Si₃N₄ ceramics was found mainly to result from the formation of an infinite cluster of J-phase, which exhibits hopping conduction.     

Effect of TiO2 on morphology and mechanical properties of PVDF/PMMA blend films prepared by melt casting process

Effect of titanium dioxide (TiO₂) on morphology and mechanical properties of poly(vinylidene fluoride) (PVDF)/poly(methyl methacrylate) (PMMA) blend films prepared at different TiO₂ contents by a melt casting process was studied. The results showed that tensile moduli in both the machine direction (MD) and the transverse direction (TD) increased with increasing TiO₂ content, and calculated tensile moduli based on the Halpin–Tsai and the Kerner model were consistent with experimental ones in both the MD and TD of films containing 10 wt % TiO₂. However, experimental tensile moduli exhibited smaller values compared with calculated ones, as the TiO₂ content increased to 30 wt %_, and it was assumed that this is due to the decrease of crystallinity of PVDF. Morphological observations indicated that TiO₂ particles did not affect crystal structures of PVDF and the morphology of PVDF/PMMA amorphous phase, but hindered the crystallization of PVDF. The MD and TD elongation at break exhibited >200 and <20%, respectively. The SEM micrographs revealed that spherulites could deform along the MD when the tensile force was applied along the direction. By contrast, spherulites could not deform along the TD and fractured at very small elongation, owing to the anisotropic morphology of spherulites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40454.     

Dynamic Changes in Reactive Oxygen Species in the Shoot Apex Contribute to Stem Cell Death in Arabidopsis thaliana

In monocarpic plants, stem cells are fated to die. However, the potential mechanism of stem cell death has remained elusive. Here, we reveal that the levels of two forms of reactive oxygen species (ROS), superoxide anion free radical (O2·−) and hydrogen peroxide (H₂O₂), show dynamic changes in the shoot apex during the plant life cycle of Arabidopsis thaliana. We found that the level of O2·− decreased and disappeared at four weeks after bolting (WAB), while H₂O₂ appeared at 3 WAB and showed a burst at 5 WAB. The timing of dynamic changes in O2·− and H₂O₂ was delayed for approximately three weeks in clv3-2, which has a longer lifespan. Moreover, exogenous application of H₂O₂ inhibited the expression of the stem cell determinant WUSCHEL (WUS) and promoted the expression of the developmentally programmed cell death (dPCD) marker gene ORESARA 1 (ORE1). These results indicate that H₂O₂ triggers an important signal inducing dPCD in stem cells. Given that O2·− plays roles in maintaining WUS expression and stem cell activity, we speculate that the dynamic shift from O2·− to H₂O₂ in the shoot apex results in stem cell death. Our findings provide novel insights for understanding ROS-mediated regulation during plant stem cell death.     

Investigation of hydrogen storage capacity of various carbon materials

Hydrogen storage capacity of various carbon materials, including activated carbon (AC), single-walled carbon nanohorn, single-walled carbon nanotubes, and graphitic carbon nanofibers, was investigated at 303 and 77 K, respectively. The results showed that hydrogen storage capacity of carbon materials was less than 1 wt% at 303 K, and a super activated carbon, Maxsorb, had the highest capacity (0.67 wt%). By lowering adsorption temperature to 77 K, hydrogen storage capacity of carbon materials increased significantly and Maxsorb could store a large amount of hydrogen (5.7 wt%) at a relatively low pressure of 3 MPa. Hydrogen storage capacity of carbon materials was proportional to their specific surface area and the volume of micropores, and the narrow micropores was preferred to adsorption of hydrogen, indicating that all carbon materials adsorbed hydrogen gas through physical adsorption on the surface.     

Effects of processing and cooking on the levels of pesticide residues in soybean samples

The effects of processing and cooking on the levels of pesticide residues in soybean samples were investigated for 14 pesticides in pre-harvest samples. On soaking, the transfer ratios (%, total pesticide residue amount in product/that in soybean) of soaked soybean were greater than 60% for most of the pesticides investigated. The transfer ratio of soymilk ranged from 37% to 92%, and that of tofu ranged from 7% to 63%. The processing factor (Pf, the concentration (mg/kg) of pesticide in product/that in soybean) of tofu ranged from 0.026 to 0.28. These values varied among pesticides. There was a high correlation between the log P(ow) and the transfer ratio of tofu. The test described here should be useful to obtain the transfer ratios of pesticide residues in processing and/or cooking steps.     

Toughening of cyanate ester resin by N‐phenylmaleimide–N‐(p‐hydroxy)phenyl‐maleimide–styrene terpolymers and their hybrid modifiers

N‐Phenylmaleimide–N‐(p‐hydroxy)phenylmaleimide–styrene terpolymer (HPMS), carrying reactive p‐hydroxyphenyl groups, was prepared and used to improve the toughness of cyanate ester resins. Hybrid modifiers composed of N‐phenylmaleimide–styrene copolymer (PMS) and HPMS were also examined for further improvement in toughness. Balanced properties of the modified resins were obtained by using the hybrid modifiers. The morphology of the modified resins depends on HPMS structure, molecular weight and content, and hybrid modifier compositions. The most effective modification of the cyanate ester resin was attained because of the co‐continuous phase structure of the modified resin. Inclusion of the modifier composed of 10 wt% PMS (M_w 136 000 g mol^?1) and 2.5 wt% HPMS (hydroxyphenyl unit 3 mol%, M_w 15 500 g mol^?1) led to 135% increase in the fracture toughness (K_IC) for the modified resin with a slight loss of flexural strength and retention of flexural modulus and glass transition temperature, compared with the values for the unmodified resin. Furthermore, the effect of the curing conditions on the mechanical and thermal properties of the modified resins was examined. The toughening mechanism is discussed in terms of the morphological and dynamic viscoelastic behaviour of the modified cyanate ester resin system. © 2001 Society of Chemical Industry     

Antihypertensive Effect of Salt-Free Soy Sauce,a New Fermented Seasoning,in Spontaneously Hypertensive Rats

ABSTRACT: In this study, we focused on the antihypertensive effect of newly fermented salt-free soy sauce (SFS) in spontaneously hypertensive rats (SHRs). A 13-wk oral administration of SFS was performed daily in 8- to 21-wk-old SHRs with a dose of 200 mg/kg of body weight/d. The systolic (SBP) and diastolic (DBP) blood pressures were measured for each week during the experimental period. As a result, a significant (P < 0.01) BP lowering effect was observed from the 5th d to the end of the experiment in the SFS group compared with the control group (ΔSBP_21-wk: 27 mmHg, ΔDBP_21-wk: 20 mmHg). In contrast to such substantial effect by SFS intake, angiotensin I-converting enzyme activities in blood and local organs as well as pharmaceutical parameters such as serum Na⁺ or K⁺ level did not show any significant difference between in both SFS and control groups. Vasoconstriction experiment using thoracic aorta rings from 21-wk SHRs provided an interesting result that the rings from the SFS group evoked a >2-fold higher increase in the angiotensin II-stimulated constrictive response compared with the rings from the control group (P = 0.012), which suggested that the SFS-intake would be effective in possessing a higher vessel tone. Practical Application: In this study, we investigated the antihypertensive effect of newly fermented SFS in SHRs. As a result of 13-wk SFS-administration, we found a significant antihypertensive effect of the SFS. This finding strongly demonstrates that the developed SFS would be greatly beneficial for health and useful for health-related industries.