Surface diffusion lenght during MOMBE and CBE growth measured by μ-RHEED

The growth rates of layers grown on a mesa-etched (001) GaAs surface were measured by in-situ scanning microprobe reflection high-energy electron diffraction (μ-RHEED) from the period of the RHEED intensity oscillation in real time. The diffusion lenght of the surface adatoms of column III elements was determined from the gradient of the variation of the growth rates in the cases of MBE, MOMBE using trimethylgallium (TMGa) and CBE using TMGa or triethylgallium (TEGa) and arsine (AsH₃). The obtained values of the diffusion lengths were of the order of a micrometer in every case of the source-material combination. In the case of metalorganic materials as Ga source, it was found that the diffusion length was larger than that of Ga atom from metal Ga source. Since the substrate temperature of the present experiment is high enough to decompose TMGa and TEGa on the surface, Ga adatoms are considered to be responsible to the surface diffusion. Therefore, it is considered that the derivatives of the metalorganic molecules such as methyl radicals affect the diffusion of Ga adatoms.     

Structure and magnetic properties of FeCo nanoparticles encapsulated in carbon nanotubes grown by microwave plasma enhanced chemical vapor deposition

Plasma enhanced chemical vapor deposition is a simple technique for preparing magnetic nanoparticles encapsulated in carbon nanotubes. We employed alloy catalysts when growing carbon nanotubes to control the composition and magnetic properties of encapsulated nanoparticles. Single-crystal nanoparticles were successfully encapsulated in carbon nanotubes, and their crystal structure varied depending on the composition of the alloy catalysts. The coercive force of nanoparticles also varied according to the composition of the catalysts.     

A radiochemical study on the existence of dineutron

A radiochemical study has been made to search for dineutron² n produced in the simultaneous two-neutron emission of the excited⁶He nuclei,⁶He^*, induced in the reaction of⁹Be+n→-⁶He^*+α with fast neutrons in a reactor. It was attempted to detect the radio-activity of²⁸Mg as a product of the reaction² n+²⁷Al→²⁸Mg+p. The²⁸Mg radioactivity observed in heterogeneous samples composed of the² n-producing target Be and the² n-detecting target Al separately was not found to be more than that of a side reaction,²⁷Al{(n, p)(n _th, γ)+(n _th, γ)(n, p)}²⁸Mg, whereas it clearly exceeded that of the side reaction in alloy samples made of Be and Al metals. The former experiment gives an upper limit of the production rate of the dineutron in the bound state 1×10^?7 per event of the simultaneous two-neutron emission. A tentative explanation for the excessive²⁸Mg radioactivity observed in the latter experiment is the following two-step process,⁹Be+n→⁶He+α and²⁷Al+⁶He→+²⁸Mg+α+p, rather than the process induced by the dineutron in a virtual state.     

Design of a Hyperpolarized Molecular Probe for Detection of Aminopeptidase N Activity

Aminopeptidase N (APN) is an important enzyme that is involved in tumor angiogenesis. Detection of APN activity can thus lead to early diagnosis and elucidation of tumor development. Although some molecular probes for APN have been developed, the detection of APN activity in opaque biological samples remains a challenge. To this end, we designed a hyperpolarized NMR probe [1‐¹³C]Ala‐NH₂ which satisfies the prerequisites for APN detection, namely, sufficient retention of the hyperpolarized state, a high reactivity to APN, and an APN‐induced chemical shift change. The [1‐¹³C]Ala‐NH₂ probe allowed sensitive detection of APN activity using ¹³C NMR spectroscopy.     

Synthesis of Δ1-carbapenem derivative by aldol condensation method

The Δ¹-carbapenem derivative($\text{6}$) was prepared by the aldol condensation of the dialdehydic compound($\text{5}$) with piperidinium acetate. Careful hydride reduction followed by benzoylation gave $\text{7}$b, which was successfully decarbalkoxylated to $\text{8}$. The X-ray structure analysis of $\text{8}$ showed the C-3 carboxylate group and C-5 H are $\text{cis}$ each other.     

Explicit Solution to a Certain Non-ELQG Risk-sensitive Stochastic Control Problem

A risk-sensitive stochastic control problem with finite/infinite horizon is studied with a 1-dimensional controlled process defined by a linear SDE with a linear control-term in the drift. In the criterion function, a non-linear/quadratic term is introduced by using the solution to a Riccati differential equation, and hence, the problem is not ELQG (Exponential Linear Quadratic Gaussian) in general. For the problem, optimal value and control are calculated in explicit forms and the set of admissible risk-sensitive parameters is given in a concrete form. As applications, two types of large deviations control problems, i.e., maximizing an upside large deviations probability and minimizing a downside large deviations probability, are mentioned.     

Binding assay for cholera toxin based on sequestration electrochemistry using lactose labeled with an electroactive compound

A simple electrochemical binding assay for cholera toxin (CT) was developed using lactose labeled with daunomycin as an electroactive compound. The labeled lactose (LL) was determined with high sensitivity by adsorptive stripping voltammetry (AdSV). The electrochemical behaviors of LL at glassy carbon (GC), plastic formed carbon (PFC) and carbon nanotubes paste (CNTP) electrode were investigated. The CNTP electrode showed the greatest accumulation capacity for LL. The assay for CT based on the sequestration electrochemistry was demonstrated. The binding event of the LL to CT was detected by the decrease in the electrochemical response of daunomycin as an electroactive label without a separation process to remove the free LL from the one bound with CT before any measurements can be made. The detection limit of the CT assay using the CNTP electrode was 0.5 nM (42 ng mL(-1)).