Using a surface complexation model to predict the nature and stability of nanoparticles

Nanoparticles are discrete nanometer-scale assemblies of atoms and have dimensions between those characteristic of ions and those of macroscopic materials. These minerals commonly possess extremely large specific surface areas and surface adsorption capacities for foreign ions. Due to the large specific surface area and large fraction of surface atoms, the natures of nanoparticles are expected to be modified by the adsorption (surface complexation) process. In this paper,we discuss theoretically the stability of nanoparticles that make the surface complex with foreign ions. The principal theoretical assumption is that the surface complexation occurs at the bulk of the nanoparticles, as in a solid solution. The surface complexation affects two aspects of the intrinsic stability of the nanoparticles simultaneously: one is the composition of the nanoparticles; the other is the free energy of formation of nanoparticles. The solubility of hydrous ferric oxide (HFO) was estimated by using surface complexation modeling coupled with published data of the free energy of formation of the relevant components. The solubility modeling of surface-charged (H+ or OH- sorbed) HFO mechanistically and quantitatively explained the observed nonintegral behavior of the solubility of HFO. Moreover, solubility modeling of anion (SO4(2-), PO4(3-), and As(V)) sorption by HFO showed that the sorption process strongly influences the stability of the nanoparticles. This result implies that geochemical modeling leads to the erroneous prediction of a natural system if the effect of the sorption process is not taken into account.     

Optical properties of epitaxial plzt thin films

In the epitaxial (Pb_1?x , La _x )(Zr_1?y , Ti _y )_1?x/4O₃ [PLZT] films, the composition dependence of the refractive index and electric-optic (EO) coefficient near the morphotropic phase boundary (MPB) composition was investigated. A (100/001)-oriented PLZT 10/65/35 epitaxial film is found to have isotropic optical properties. Highly (100/001)-oriented epitaxial PLZT films with compositions near the MPB on Nb–SrTiO₃ substrates were fabricated using a sol–gel process. The value of birefringence from 4?×?10^?3 to 5?×?10^?4 in PLZT epitaxial film was smaller than that of lithium niobate single crystal. The refractive index decreases with increasing lanthanum content. The difference in the refractive index obtained depended upon the lanthanum content up to 2%. This value is adequate for fabrication of waveguide structures. The EO coefficient of PLZT 9/65/35 thin films was 45 pm/V, which is larger than that of lithium niobate single crystal. A very small polarization dependence of the EO coefficient was also observed.     

Beef texture characterization using internationally established texture vocabularies in ISO5492:1992: Differences among four different end-point temperatures in three muscles of Holstein steers

‘Tenderness’ has been an important sensory characteristic for beef, although ‘tenderness’ has not been commonly defined. On the other hand, ISO5492:1992 provides internationally established vocabularies for sensory analysis with simple definition. The aim of this study was texture characterization for three beef muscles cooked to four end-point temperatures using ISO5492:1992 texture terms in Japanese to develop objective sensory evaluation terms for beef texture other than ‘tenderness.’ Longissimus, semitendinosus, and psoas major muscles harvested from three Holstein steers were cooked to 45, 60, 72, and 92 °C end-point temperatures and evaluated by a trained sensory panel. Correspondence analysis indicated that the ‘chewiness’ and ‘hardness’ defined in ISO5492 were distinguished in each muscle. Changes in the ‘chewiness’ and ‘hardness’ qualities during cooking were different from each other. These findings suggest that both ‘chewiness’ and ‘hardness’ as defined in ISO5492:1992 should be evaluated simultaneously to determine the sensory texture of beef.     

Creep-fatigue crack propagation in lead-free solder under cyclic loading with various waveforms

Crack propagation tests of lead-free solder were conducted using center-notched plate specimens under cyclic tension-compression of three load waveforms: pp waveform having fast loading and unloading, cp-h waveform having a hold time under tension, and cc-h waveform having a hold time under tension and compression. In the case of fatigue loading, i.e. pp waveform, the path of crack propagation was macroscopically straight and perpendicular to the maximum principal stress direction, showing tensile-mode crack propagation. The introduction of the creep components by hold time in cc-h and cp-h waveforms promoted shear-mode crack propagation. For fatigue loading of pp wave, the crack propagation rate was expressed as a power function of the fatigue J integral and the relation was identical for load-controlled and displacement-controlled conditions. The creep component due to the hold time greatly accelerates the crack propagation rate when compared at the same values of the fatigue J integral or the total J integral (the sum of fatigue J and creep J integrals). The creep crack propagation rate was expressed as a power function of the creep J integral for each case of cp-h and cc-h waveforms. The crack propagation rate for cp-h waveform is higher than that for cc-h waveform. The predominant feature of fracture surfaces was striations for pp waveform and grain boundary fracture for cp-h waveform. Grain fragmentation was abundantly observed on the fracture surface made under cc-h waveform.     

Efficient Identification of the MYC Regulator with the Use of the CRISPR Library and Context-Matched Database Screenings

MYC is a major oncogene that plays an important role in cell proliferation in human cancers. Therefore, the mechanism behind MYC regulation is a viable therapeutic target for the treatment of cancer. Comprehensive and efficient screening of MYC regulators is needed, and we had previously established a promoter screening system using fluorescent proteins and the CRISPR library. For the efficient identification of candidate genes, a database was used, for which mRNA expression was correlated with MYC using datasets featuring “Similar” and “Not exactly similar” contexts. INTS14 and ERI2 were identified using datasets featuring the “Similar” context group, and INTS14 and ERI2 were capable of enhancing MYC promoter activity. In further database analysis of human cancers, a higher expression of MYC mRNA was observed in the INTS14 mRNA high-expressing prostate and liver cancers. The knockdown of INTS14 in prostate cell lines resulted in decreased MYC mRNA and protein expression and also induced G0/1 arrest. This study confirmed that CRISPR screening combined with context-matched database screening is effective in identifying genes that regulate the MYC promoter. This method can be applied to other genes and is expected to be useful in identifying the regulators of other proto-oncogenes.     

Acetylated Xylan Degradation by Glycoside Hydrolase Family 10 and 11 Xylanases from the White-rot Fungus Phanerochaete chrysosporium

Endo-type xylanases are key enzymes in microbial xylanolytic systems, and xylanases belonging to glycoside hydrolase (GH) families 10 or 11 are the major enzymes degrading xylan in nature. These enzymes have typically been characterized using xylan prepared by alkaline extraction, which removes acetyl sidechains from the substrate, and thus the effect of acetyl groups on xylan degradation remains unclear. Here, we compare the ability of GH10 and 11 xylanases, PcXyn10A and PcXyn11B, from the white-rot basidiomycete Phanerochaete chrysosporium to degrade acetylated and deacetylated xylan from various plants. Product quantification revealed that PcXyn10A effectively degraded both acetylated xylan extracted from Arabidopsis thaliana and the deacetylated xylan obtained by alkaline treatment, generating xylooligosaccharides. In contrast, PcXyn11B showed limited activity towards acetyl xylan, but showed significantly increased activity after deacetylation of the xylan. Polysaccharide analysis using carbohydrate gel electrophoresis showed that PcXyn11B generated a broad range of products from native acetylated xylans extracted from birch wood and rice straw, including large residual xylooligosaccharides, while non-acetylated xylan from Japanese cedar was readily degraded into xylooligosaccharides. These results suggest that the degradability of native xylan by GH11 xylanases is highly dependent on the extent of acetyl group substitution. Analysis of 31 fungal genomes in the Carbohydrate-Active enZymes database indicated that the presence of GH11 xylanases is correlated to that of carbohydrate esterase (CE) family 1 acetyl xylan esterases (AXEs), while this is not the case for GH10 xylanases. These findings may imply co-evolution of GH11 xylanases and CE1 AXEs.     

Performance Evaluation of Magnetostrictive Small Wind Turbines Using Fe–Co Alloy–Based Clad Sheets

In this study, the Fe–Co alloy is combined with cobalt ferrite (CoFe₂O₄) and nickel (Ni) to form Fe–Co/CoFe₂O₄ and Fe–Co/Ni clad sheets and their energy-harvesting performance is evaluated. The Fe–Co/CoFe₂O₄ clad sheet exhibits an output voltage of 4.229 mV and an output power of 6.89 nW at a wind speed of 10 m s⁻¹. The energy-harvesting performance of both these clad sheets cannot be quantitatively compared owing to their different thicknesses, which result in varying volume and distance from the neutral plane. Nevertheless, the values of output voltage and power for Fe–Co/CoFe₂O₄ are higher than those for Fe–Co/Ni (2.107 mV and 0.294 nW).