Synthesis and characterization of a series of mesoporous nanocrystalline lanthanides phosphate

A series of lanthanide (LA) phosphate were prepared by using N-(2-hydroxyethyl) ethylenediane-N,N′,N′-triacetic acid (H₃hedtra) as a chelating agent. The obtained samples were characterized by using X-ray diffraction (XRD), nitrogen adsorption-desorption isotherm, thermal analysis (TG-DTA), transmission electron microscope (TEM) and TPD-ammonia desorption. The results showed that samples prepared through chelating agent route possessed smaller particle size which led to higher specific surface area with increased acidic sites compared with the reference samples prepared free of H₃hedtra. It was also found that the acidic strength increased gradually from the light lanthanide phosphate to heavy lanthanide phosphate. Besides, pore size of the samples could be controlled by altering the mole ratio of the lanthanide(LA): H₃hedtra. Pore size distribution of the samples became narrower through synthesis in the presence of H₃hedtra. The precursor sol complex was investigated by FTIR and XRD and mesopore formation mechanism had been discussed.     

Cryogenic crushing of polystyrene

Atactic and isotactic polystyrene powders were fractured with a ball mill at ?196°C. The molecular weight distributions at various milling times measured by GPC show an initial asymmetric broadening and then a gradual returning to the original narrow bell-shaped distribution. Analysis of molecular weight distributions suggests a preferential chain scission near the chain ends. X-ray diffraction spectra of isotactic polystyrene samples show that after 24 hr of milling, the semicrystalline polystyrene was completely transformed into an amorphous polymer. DSC thermogram of the milled isotactic polystyrene reveals several crystallization peaks preceding melting when the samples were heated.     

Validity of a self-administered food frequency questionnaire (FFQ) and its generalizability to the estimation of dietary folate intake in Japan

Background  

In an epidemiological study, it is essential to test the validity of the food frequency questionnaire (FFQ) for its ability to estimate dietary intake. The objectives of our study were to 1) validate a FFQ for estimating folate intake, and to identify the foods that contribute to inter-individual variation of folate intake in the Japanese population.     

The Establishment of an Assay to Measure DNA Polymerase-Catalyzed Repair of UVB-Induced DNA Damage in Skin Cells and Screening of DNA Polymerase Enhancers from Medicinal Plants

An in vitro assay method was established to measure the activity of cellular DNA polymerases (Pols) in cultured normal human epidermal keratinocytes (NHEKs) by modifying Pol inhibitor activity. Ultraviolet (UV) irradiation enhanced the activity of Pols, especially DNA repair-related Pols, in the cell extracts of NHEKs. The optimal ultraviolet B (UVB) exposure dose and culture time to upregulate Pols activity was 100 mJ/cm² and 4-h incubation, respectively. We screened eight extracts of medicinal plants for enhancement of UVB-exposed cellular Pols activity using NHEKs, and found that rose myrtle was the strongest Pols enhancer. A Pols’ enhancement compound was purified from an 80% ethanol extract of rose myrtle, and piceatannol was isolated by spectroscopic analysis. Induction of Pol activity involved synergy between UVB irradiation and rose myrtle extract and/or piceatannol. Both the extract and piceatannol reduced UVB-induced cyclobutane pyrimidine dimer production, and prevented UVB-induced cytotoxicity. These results indicate that rose myrtle extract and piceatannol, its component, are potential photo-protective candidates for UV-induced skin damage.     

Scaling relation of domain competition on (2+1)-dimensional ballistic deposition model with surface diffusion

During heteroepitaxial overlayer growth multiple crystal domains nucleated on a substrate surface compete with each other in such a manner that a domain covered by neighboring ones stops growing. The number density of active domains ρ decreases as the height h increases. A simple scaling argument leads to a scaling law of ρ~h^-γ with a coarsening exponent γ=d/z, where d is the dimension of the substrate surface and z the dynamic exponent of a growth front. This scaling relation is confirmed by performing kinetic Monte Carlo simulations of the ballistic deposition model on a two-dimensional (d=2) surface, even when an isolated deposited particle diffuses on a crystal surface.     

Validity of decision mode analysis on an ROI determination problem in multichannel fNIRS data

Region of interest (ROI) determination is necessary when using functional near-infrared spectroscopy (fNIRS) data to detect brain activity. To extract ROIs from multiple fNIRS channels, we investigated the validity of applying decision mode analysis to the fNIRS dataset. This classifies a dataset into clusters with similar features. For each cluster, the dataset is decomposed into a mean vector and a linear combination of eigenvectors. Applying this to fNIRS signals, the mean vector can be used to represent change in hemoglobin (Hb), and the eigenvectors interpreted as a signal component constructing the arbitrary signal. Characterizing these vectors by correlating them with a theoretical model of brain function aids our understanding of where Hb changes occur and what type of Hb changes reflect brain activity in fNIRS data. Decision mode analysis of fNIRS data measured during viewing stereoscopic images identified ROIs around the right inferior frontal gyrus associated with attentional control, and frontal association area associated with decision on action and prediction. Our experimental results showed that information obtained from decision mode analysis can aid quantitative and qualitative ROI determination.     

Prevention of oxidative degradation of ZnDTP by microcapsulation and verification of its antiwear performance

Prevention of oxidative degradation of zinc dialkyldithiophosphate (ZnDTP) is very important to prolong the antiwear performance of the engine oil. The microcapsulation of ZnDTP was attempted so as to isolate ZnDTP from peroxides in bulk lubricating oil during use. Microcapsulation allows for the isolation and protection of ZnDTP in bulk lubricating oil, and the ability to release control of ZnDTP at the contact surfaces. The protection of ZnDTP from oxidative degradation was evaluated by adding cumenhydroperoxide to the microcapsule-containing sample oil or by blowing NO_x gas into the sample, followed by analysis with ³¹P NMR. The antiwear performance of the microcapsule-containing sample oil was studied using a 4-ball tribometer. It was confirmed that the microcapsulation of ZnDTP significantly reduced the oxidative degradation of ZnDTP additive, and antiwear performance was effectively maintained.     

Fabrication and thermal expansion properties of ZrW2O8/Zr2WP2O12 composites

ZrW₂O₈/Zr₂WP₂O₁₂ composites were fabricated by sintering ZrW₂O₈–Zr₂WP₂O₁₂ powder mixtures at 1473 K for 1 h, and their negative thermal expansion properties were investigated. The relative density of sintered pure-phase ZrW₂O₈ was 72.3%, while that of the sintered composites was 88.4–92.3%. In the composites, the observed hysteresis in the thermal expansion data was small because of the small difference between the CTEs of ZrW₂O₈ and Zr₂WP₂O₁₂. The CTE of the composites was negative and increased with the Zr₂WP₂O₁₂ content. When the Zr₂WP₂O₁₂ volume fraction in the composites was increased from 0 to 75 vol%, the CTEs of the composites increased from ?9.1 × 10^?6 to ?3.1 × 10^?6 K^?1 and from ?5.0 × 10^?6 to ?1.9 × 10^?6 K^?1 over the temperature ranges of 323–373 and 473–673 K, respectively. In composites with Zr₂WP₂O₁₂ volume fractions of 0–25 vol%, the experimentally obtained CTE values were in good agreement with the calculated values obtained by assuming mixed law behavior.     

Facile preparation of gold nanoparticle with diarylethene polymers by disodium malate and its photoreversible optical properties

We have developed a synthetic procedure of gold nanoparticle covered with polystyrene (Au-poly(St)) using organic acid salts, followed by a ligand exchange reaction. First, various chain lengths of polystyrenes (poly(St)s) bearing thiol-end group were used as the covering agent of gold nanoparticle prepared by reduction using trisodium citrate. The resulting nanoparticles with ca. 13 nm diameter were dispersed in toluene when the molecular weight of the ligand poly(St) is larger than 1200. Larger sized Au-poly(St) could be obtained using disodium malate instead of the citrate. The colloidal gold nanoparticle with ca. 40 nm diameter was easily prepared only by changing the reducing agent. Finally, we have demonstrated to prepare larger sized gold nanoparticle covered with a photochromic diarylethene polymer (Au-poly(DE)) that shows large change in local surface plasmon resonance absorption according to the photochromic reaction even in a solution.