An application of activation analysis of aluminum in biological materials

The behavior of aluminum compounds in animals was made clear by using non-destructive neutron activation analysis instead of radiotracer method. Basic aluminum sucrose sulfate (BASS) and dried aluminum hydroxide gel (DAHG) were orally administered to rats. The residual BASS and DAHG on gastric walls of rats were determined by neutron activation analysis. It was obtained the following results that BASS was found at the longer time in the stomach. For reason, it is seemed that BASS is hydrolyzed in gastric juice. And it could not find the aluminum in liver, kidney and spleen.     

Growth process and structure of Fe/Si(1 1 1) ultrathin film: Transition from single-domain Fe(1 1 1)/Si(1 1 1) to β-FeSi2

The growth processes and structures of Fe/Si(1 1 1) ultrathin films grown by solid-phase reactive epitaxy were investigated by coaxial impact-collision ion scattering spectroscopy (CAICISS). It has been revealed that the Fe(1 1 1) thin films with a bcc-type structure were epitaxially grown on a Si(1 1 1) crystal, even at room temperature, and formed a single-domain structure: Fe(1 1 1)∥Si(1 1 1). After annealing at above 600 °C, the Fe(1 1 1) films were transformed into β-FeSi₂ via the collapse of the bcc-type structure to an amorphous or polycrystalline structure. On the basis of the thickness dependences of the growth processes, this phenomenon was discussed in terms of the diffusion of Si into Fe thin films.     

Computation of betti numbers of monomial ideals associated with cyclic polytopes

We give a combinatorial formula for the Betti numbers which appear in a minimal free resolution of the Stanley-Reisner ringk[Δ(P)]=A/I _Δ(P) of the boundary complex Δ(P) of an odd-dimensional cyclic polytopePover a fieldk. A corollary to the formula is that the Betti number sequence ofk[Δ(P)] is unimodal and does not depend on the base fieldk.     

Effect of fast neutron irradiation on magnetic properties of fullerene superconductor Rb3C60

Effects of fast neutron irradiation and post-annealing on magnetic properties of Rb₃C₆₀ were studied through the dc magnetization measurement. Rb₃C₆₀ powder samples were prepared in an evacuated quartz glass tube, and the temperature and the magnetic field dependences of dc magnetization were measured before and after irradiation and after post-annealing. The neutron fluences were 1.0, 1.8 and 3.3 × 10¹⁶ n/cm², and the post-annealing was made at a temperature of 473 K for 3 h. Magnetic hysteresis of the samples irradiated at the fluence of 1.8 and 3.3 × 10¹⁶ n/cm² disappeared, and the hysteresis curves hardly changed at the fluence of 1.0 × 10¹⁶ n/cm². As for the post-annealing effect, the hysteresis curves of the sample irradiated at the fluence of 1.8 × 10¹⁶ n/cm² were completely recovered after annealing, while those of the other samples, which had a magnetic background before irradiation, were not recovered. In this study, it was found that the loss of superconductivity in Rb₃C₆₀ powder is observed when the neutron irradiation fluence exceeds 1.0 × 10¹⁶ n/cm², and the lost superconductivity is completely recovered by the post-annealing at 473 K for 3 h.     

Hybrid Mesoporous-Silica Materials Functionalized by Pt(II) Complexes: Correlation between the Spatial Distribution of the Active Center, Photoluminescence Emission, and Photocatalytic Activity

[Pt(tpy)Cl]Cl (tpy: terpyridine) was successfully anchored to a series of mesoporous-silica materials that were modified with (3-aminopropyl)triethoxysilane with the aim of developing new inorganic-organic hybrid photocatalysts. Herein, the relationship between the luminescence characteristics and photocatalytic activities of these materials is examined as a function of Pt loading to define the spatial distribution of the Pt complex in the mesoporous channel. At low Pt loading, the Pt complex is located as an isolated species and exhibits strong photoluminescence emission at room temperature owing to metal-to-ligand charge-transfer ((3) MLCT) transitions (at about 530?nm). Energy- and/or electron-transfer from (3) MLCT to O(2) generate potentially active oxygen species, which are capable of promoting the selective photooxidation of styrene derivatives. On the other hand, short Pt???Pt interactions are prominent at high loading and the metal-metal-to-ligand charge-transfer ((3) MMLCT) transition is at about 620?nm. Such Pt complexes, which are situated close to each other, efficiently catalyze H(2) -evolution reactions in aqueous media in the presence of a sacrificial electron donor (EDTA) under visible-light irradiation. This study also investigates the effect of nanoconfinement on anchored guest complexes by considering the differences between the pore dimensions and structures of mesoporous-silica materials.     

Cohen–Macaulayness and Limit Behavior of Depth for Powers of Cover Ideals

Let 𝕂 be a field, and let R = 𝕂[x ₁,…, x _n ] be the polynomial ring over 𝕂 in n indeterminates x ₁,…, x _n . Let G be a graph with vertex-set {x ₁,…, x _n }, and let J be the cover ideal of G in R. For a given positive integer k, we denote the kth symbolic power and the kth bracket power of J by J ^(k) and J ^[k], respectively. In this paper, we give necessary and sufficient conditions for R/J ^k , R/J ^(k), and R/J ^[k] to be Cohen–Macaulay. We also study the limit behavior of the depths of these rings.     

Arithmetical Rank of Squarefree Monomial Ideals Generated by Five Elements or with Arithmetic Degree Four

Let I be a squarefree monomial ideal of a polynomial ring S. In this article, we prove that the arithmetical rank of I is equal to the projective dimension of S/I when one of the following conditions is satisfied: (1) μ(I) ≤5; (2) arithdeg I ≤ 4.     

On the exponential Diophantine equation $$(3pm^2-1)^x+(p(p-3)m^2+1)^y=(pm)^z$$

Let m be a positive integer, and let p be a prime with \(p \equiv 1~(\mathrm{mod}~4).\) Then we show that the exponential Diophantine equation \((3pm^2-1)^x+(p(p-3)m^2+1)^y=(pm)^z\) has only the positive integer solution \((x, y, z)=(1, 1, 2)\) under some conditions. As a corollary, we derive that the exponential Diophantine equation \((15m^2-1)^x+(10m^2+1)^y=(5m)^z\) has only the positive integer solution \((x, y, z)=(1, 1, 2).\) The proof is based on elementary methods and Baker’s method.