Parallel Solution-Based Synthesis Approach for Search of Lanthanoid-Activated Ca2SnO4 Phosphor Materials

In the search for new fluorescent materials among lanthanoid-activated Ca₂SnO₄ compounds, a parallel solution-based synthesis approach was applied and a new blue-emission Ca₂SnO₄:Ce phosphor was discovered; its emission intensity reaches 80% of the intensity of one of the best commercial Y₃Al₅O₁₂:Ce³⁺ phosphors. Among 14 lanthanoid-activated materials, three categories could be distinguished with respect to the effect of the dopant ion on the excitation and emission properties of the phosphor. In addition, potential phosphors in the A–Sn–O (A=Mg, Ca, Sr, and Ba) systems were investigated and Ca₂SnO₄ was found to be the most suitable host compound for the lanthanoid-activated phosphors.     

Impact of Saharan Dust on Ocean Surface Wind Speed Derived by Microwave Satellite Sensors

In the present paper ground truth and remotely sensed datasets were used for the investigation and quantification of the impact of Saharan dust on microwave propagation, the verification of theoretical results, and the validation of wind speeds determined by satellite microwave sensors. The influence of atmospheric dust was verified in two different study areas by investigations of single dust storms, wind statistics, wind speed scatter plots divided by the strength of Saharan dust storms, and wind speed differences in dependence of microwave frequencies and dust component of aerosol optical depth. An increase of the deviations of satellite wind speeds to ground truth wind speeds with higher microwave frequencies, with stronger dust storms, and with higher amount of coarse dust aerosols in coastal regions was obtained. Strong Saharan dust storms in coastal areas caused mean relative errors in the determination of wind speed by satellite microwave sensors of 16.3% at 10.7 GHz and of 20.3% at 37 GHz. The mean relative errors were smaller in the open sea area with 3.7% at 10.7 GHz and with 11.9% at 37 GHz.     

The molecular origin of enhanced toughness in double-network hydrogels: A neutron scattering study

Double-network hydrogels (DN-gels) are a new class of crosslinked polymer networks with extraordinary mechanical properties while containing 80–90 vol.% water. Small-angle neutron scattering (SANS) was applied to investigate the molecular origin of the mechanical properties observed in DN-gels. We present SANS results in both deformed and undeformed conditions for a tough DN-gel made of poly(2-acrylamido-2-methyl-1-propane sulfonic acid) (PAMPS) and polyacrylamide (PAAm). The SANS measurements indicate that deformation of DN-gels results in periodic and mesoscale (1.5 μm) compositional fluctuations in both PAMPS and PAAm. In addition, SANS measurements also indicate that the DN-gel constituents interact favorably with each other while in water. This favorable interaction between PAMPS and PAAm is consistent with the rheological results on solution mixtures of these two polymers. The implications of the above observations to toughening mechanisms are discussed.     

Corrosion behavior of rapidly solidified Mg-Zn-rare earth element alloys in NaCl solution

Rapidly solidified flaky powder metallurgy (RS FP/M) processing was applied for preparation of corrosion-resistant bulk Mg alloys with Zn and rare earth elements. The corrosion behavior of the melt spun Mg-Zn-La and Mg-Zn-Yb alloy ribbons in 1% NaCl solution was investigated in order to determine optimum composition of corrosion-resistant Mg alloys. The effect of heat-treatment on the corrosion behavior of RS Mg-Zn-La and Mg-Zn-Yb alloys also was studied. In the Mg-Zn-La alloys, as-quenched alloys showed good corrosion resistance in the NaCl solution, but heat-treatment led to degradation due to microstructure change, that is, reduction in dispersion of the Mg₁₇La₂-type intermetallic compound. In the Mg-Zn-Yb alloys, both as-quenched and heat-treated Mg_97.5Zn_0.5Yb₂ alloys exhibited low corrosion rates because fine distribution of Mg₂Yb-type intermetallic compound in α-Mg matrix was not largely changed by heat treatment.     

Formation of 14H long period stacking ordered structure and profuse stacking faults in Mg–Zn–Gd alloys during isothermal aging at high temperature

This paper proposes a time–temperature-transformation diagram of an Mg–Zn–Gd alloy. An Mg₉₇Zn₁Gd₂ (at.%) alloy shows different precipitation sequences at low, medium and high temperatures. Low-temperature aging at <523 K brings about coherent β′-phase precipitation to a -Mg solid solution, resulting in increase in strength of the alloys. However, aging at medium and high temperatures >623 K led to strengthening of the Mg–Zn–Gd alloy, owing to the formation of profuse stacking faults and 14H long period stacking ordered structure from the supersaturated -Mg matrix, respectively.     

Grwoth rate versus temperature relations characteristic of environmental stress cracks in low-density polyethylenes and the underlying thermodynamic mechanism

Growth rate versus temperature relations of environmental stress cracks (ESC) in low-density polyethylenes (PE) are investigated. In the experiments, bent PE specimens are immersed in dimethylsiloxanes (DMS) of various molecular sizes. The growth rates are increased from 10^?9 to 10^?4 m s^?1 by a few tens of degrees increase in temperature. The relations behave in apparently complicated manners depending on DMS molecular size, PE molecular weight and amount of bending deformation. Their Arrhenius type plots, however, fall into either of the two characteristic shapes as in PE ESC induced by several non-ionic surfactants and n-propanol. They are consistently interpreted in terms of the authors' thermodynamic theory. The active liquids, though incompatible with a stress-free polymer, migrate into its matrices in a restricted region at the crack tip. The change in the paths of the state shifts leading to failure in the relevant thermodynamic potential diagrams is essential to the ESC kinetics.     

Microwave Dielectric Study on Water Structure and Physical Properties of Aqueous Systems Using Time Domain Reflectometry with Flat-End Cells

Microwave dielectric measurements were performed in the frequency range from 1 mHz up to 30 GHz using a time domain reflectometry (TDR) method for emulsions and gels. Flat-end sample cells have been used in the TDR measurement to contact a small spot of the surface of those viscoelastic and solid samples without any destruction. Relaxation processes due to various water structures were observed for these aqueous systems. Relaxation parameters thus obtained offer information about these water structures and amounts. The relaxation strength obtained from the high frequency process due to free water can be an adequate measure of water content in spite of some ambiguities for different water structures in some materials. Comparisons of actual water contents in emulsion with those estimated from the relaxation strength indicate that water structure is affected by the interaction between water and micelle. Unfreezable water observed in DNA gel under the freezing point consists of bound water and a fraction of free water. Bound water molecules are still unfreezable to keep the double helical structure of DNA, when the fraction of free water is frozen at lower temperatures. These water structures determine physical properties of moist materials. TDR measuring technique with the flat-end cell is effective to investigate water structures in viscoelastic moist materials and to evaluate physical properties and structures of complex molecular systems.     

Isolation of Endotoxin Eliminating Lactic Acid Bacteria and a Property of Endotoxin Eliminating Protein

Recently, many scholars have reported lactic acid bacteria (LAB) functions, such as anticancer activity and anti‐inflammatory activity for intestines. To decrease inflammatory substances such as endotoxins, LAB consumed safely with meals were isolated from food and food ingredients. First, LAB were isolated as 168 strains of bacillus LAB (49 strain) and coccus LAB (119 strains) from food ingredients and fermented foods such as rice, rice bran, malt, grains, miso soy paste, and some pickles. Their LAB (168 strains) were cultivated in medium containing endotoxin from Escherichia coli O18 LPS at 15 and 30 °C for 64 h to identify endotoxin‐eliminating LAB. Consequently, the AK‐23 strain was screened as an endotoxin‐eliminating LAB strain. The strain decreased endotoxin in YP medium without sugar at 30 °C for 64 h until 9% of endotoxin. The strain was identified as Pediococcus pentosaceus according to morphological characteristics such as its cell shape, physiological characteristics related to its fermentation type, assimilation of sugars, pH tolerance, optimum growth temperature, and molecular biological characteristics as its homology to 16S rRNA. To investigate the location of the endotoxin‐eliminating substance, 4 fractions were separated from AK‐23 cells as extracellular, cell wall digestion, cytoplasm, and cell membrane fractions. The endotoxin‐decreasing substance, located on a cell wall, was identified as a 217 kDa protein.