Structural Study on PbO–SiO2 Glasses by X-Ray and Neutron Diffraction and 29Si MAS NMR Measurements

Structure of x PbO–(100− x )SiO₂ ( x =25–89) glasses has been investigated by means of the X-ray and neutron diffraction and ²⁹Si MAS NMR measurements. In the radial distribution functions of all the glasses, the Pb–O correlation was observed at 0.23 nm, indicating that the PbO₃ trigonal pyramids units do exist in the whole glass forming composition range. Furthermore the existence of the first Pb–Pb correlation at ∼0.385 nm in the whole composition range suggests that the basic structural unit is considered to be a Pb₂O₄ unit, which consists of the edge-shared PbO₃ trigonal pyramids. These results strongly imply that the Pb₂O₄ units participate in the glass network constructed by SiO₄ tetrahedra even at low PbO content. Differing from other lead-containing glass systems, these structural characteristics of Pb ions in the PbO–SiO₂ glass system are responsible for the extremely wide glass-forming region.     

A systematic approach for model refinement considering blind and recognized uncertainties in engineered product development

In recent years, virtual testing has played an increasingly important role in the design and evaluation of engineered products. However, it is challenging to build the highly accurate computational models for virtual testing. Blind and recognized uncertainties are often unintentionally incorporated. These uncertainties consequently decrease the predictive capability of the models. To this end, this paper proposes a systematic approach for model refinement that minimizes the impact of unrecognized blind and recognized epistemic uncertainties in computational modeling. The approach consists of three steps: model invalidity analysis (MIA), development of an invalidity reasoning tree (IRT), and invalidity sensitivity analysis (ISA). First, in the MIA, possible causes that lead to discrepancies between the experimental and simulation responses are identified through brainstorming. Next, the IRT is built using the affinity diagram. It sequentially lists and screens potential candidate issues for model refinement at the stages of conceptual, mathematical, and computational modeling. Finally, the ISA quantifies the effect of incorporating updates in the model to address potential candidate issues with the goal of reducing the impact of the blind and recognized uncertainties. The most critical candidates are determined by using a weighted decision matrix. To demonstrate the effectiveness of the proposed approach, a case study examining a smartphone liquid crystal display fracture is presented.     

Inhibitory effect of cinnamon essential oils on selected cheese-contaminating fungi (Penicillium spp.) during the cheese-ripening process

The antifungal effects of essential oils (EOs) on cultures of the known cheese fungal contaminants Penicillium spp. were evaluated. Cinnamon leaf and bark EOs were the most effective among 8 EOs tested. The main components of both cinnamon EOs were eugenol, cinnamaldehyde, and linalool. Both inhibited growth of Penicillium spp. at a concentration of 10% v/v (2,000 ppm/mm²) on a lawn cell plate. When tested using 3 commercially available cheese starters, cinnamon EOs showed no effect against the FD-DVS ABT-5 cheese starter. However, growth of lactobacilli was inhibited in the presence of ≥10% (v/v) of leaf and bark EOs for the KAZU 1 starter, and ≥5% (v/v) for the FD-DVS FLORA-DANICA starter. A concentration of 4,000 ppm/mm² of cinnamon EOs completely inhibited growth of the Penicillium spp. that naturally contaminates the surface of Appenzeller cheese.     

Strain‐Visualization with Ultrasensitive Nanoscale Crack‐Based Sensor Assembled with Hierarchical Thermochromic Membrane

As eidetic signal recognition has become important, displaying mechanical signals visually has imposed huge demands for simple readability and without complex signal processing. Such visualization of mechanical signals is used in delicate urgent medical or safety‐related industries. Accordingly, chromic materials are considered to facilitate visualization with multiple colors and simple process. However, the response and recovery time is very long, such that rapid regular signals are unable to be detected, i.e., physiological signals, such as respiration. Here, the simple visualization of low strain ≈2%, with ultrasensitive crack‐based strain sensors with a hierarchical thermochromic layer is suggested. The sensor shows a gradient color change from red to white color in each strain, which is attributed to the hierarchical property, and the thermal response (recovery) time is dramatically minimized within 0.6 s from 45 to 37 °C, as the hierarchical membrane is inspired by termite mounds for efficient thermal management. The fast recovery property can be taken advantage of in medical fields, such as monitoring regular respiration, and the color changes can be delicately monitored with high accuracy by software on a mobile phone.     

Particle shape effect on the viscosity and thermal conductivity of ZnO nanofluids

The viscosity and thermal conductivity of ZnO nanofluids with nanoparticle shapes of nearly rectangular and of sphere, were experimentally investigated under various volume concentrations of the nanoparticles, ranging from 0.05 to 5.0 vol.%. The viscosity of the nanofluids increased with increases in the volume concentration by up to 69%. In addition, the enhancement of the viscosity of the nearly rectangular shape nanoparticles was found to be greater by 7.7%, than that of the spherical nanoparticles. The thermal conductivity of the ZnO nanofluids increased by up to 12% and 18% at 5.0 vol.% for the spherical and the nearly rectangular shape nanoparticles, respectively, compared to that of the base fluid (water). The shape of the particles is found to have a significant effect on the viscosity and thermal conductivity enhancements.     

"江南古陆"中段湖南地区金矿床成矿模式研究

“江南古陆”又称“江南古岛弧”,它是我国南方一条重要的金成矿带,其内发育有一系列似层状的金矿床,有关其成因长期以来一直被认为属于晚元古代的层控矿床。笔者通过对“江南古陆”金矿成矿带上新近发现的万古金矿床和邻近的其它金矿床进行对比性研究,提出了对“江南古陆”中段湖南地区金矿床成矿模式的有关认识,认为元古宙浅变岩系作为金矿赋存层位,在成矿作用过程中提供了一定的物源,但主要成矿作用发生在燕山期。     

Neutron Diffraction Study on the Structure of Na-Si-O-N Oxynitride Glasses

The local structure of a Na₂O─SiO₂ oxide glass and a Na₂O─iO₂─Si₃N₄ oxynitride glass has been investigated by the pulsed neutron diffraction method. In the oxide glass, the first peak of radial distribution function (RDF) curves appeared at 0.1627 nm corresponding to Si─O boxh length. In the oxynitride glass, the first peak of the RDF curve was shifted to longer distances at 0.1650 nm due to the coexistence of Si─O and Si─N boxhs. The first peak in the RDF curve of the oxynitride glass was deconvoluted into two peaks whose positions are located at 0.1626 and 0.1709 nm. The one at 0.1626 nm is ascribed to Si─O boxhs and the other at 0.1709 nm to Si─N boxhs. The number of silicon atoms around a nitrogen was found to be 2.42, suggesting that not all of the nitrogen atoms are boxhed to three silicon atoms, but 58% twofold (─N─) and 42% threefold (>N─) nitrogens coexist in the present Na-Si-O-N oxynitride glass. The formation of twofold nitrogens may arise from the reaction between ≡Si─O⁻ and ≡Si₃N groups. This model is compatible with the experimental observation that the density and Vickers hardness of oxynitride glasses increase with the nitrogen content.     

Synthesis and properties of (Hf1-xTax)C solid solution carbides

Thermodynamically stable (Hf_1–xTa_x)C (x?=?0.1–0.3) compositions were selected by First Principle Calculation and synthesized in nanopowders via high-energy ball milling and carbothermal reduction of commercial oxides at 1450?°C. The formation of a solid solution during powder synthesis was investigated. The solid solution carbide powders were sintered at 1900?°C by spark plasma sintering without a sintering aid. As a result, the (Hf_1–xTa_x)C solid solution carbides exhibited high densities, excellent hardness and fracture toughness (ρ: 98.7–100.0%, HVN: 19.69–19.98?GPa, K_IC: 5.09–5.15?MPa?m^1/2) compared with previously reported HfC and HfC–TaC solid solution carbides.     

In vitro and in vivo anti-inflammatory activities of mixed fruit and vegetable juice

Food Science and Biotechnology - In this study, we attempted to develop fruit-based functional juice with anti-inflammatory activity for consumers living under heavy air pollution. At first, four...