Intermolecular Radical Reaction of O,Se-Acetals Generated via Seleno-Pummerer Rearrangement

A new general protocol for the synthesis of O,Se-acetals using the seleno-Pummerer reaction has been developed, and their radical-based two- and three-component coupling reactions were studied. The three-component coupling employed the O,Se-acetal, cyclopentenone, and an allylstannane derivative, and enabled stereoselective installations of α-acyloxy alkyl and functionalized allyl groups to generate the 2,3-trans-disubstituted cyclopentanone in a single operation. The obtained highly functionalized structure was used as an intermediate for facile assembly of the zedoarondiol carboskeleton.     

High-yield synthesis of semiconductive type-II Si clathrates with low Na content

To develop an efficient synthesis of type-II Si clathrates with low Na content (Na_xSi₁₃₆: x = 0–24), various conditions for annealing the Zintl phase NaSi were examined. The addition of a pre-annealing process under vacuum at 250 °C following the preparation of NaSi resulted in a decrease in the Na content of type-II Si clathrates from 4 to 2 when the pre-annealing duration ranged from 0 to 60 h, while the volume fraction of type-II Si clathrate crystals in the synthesized specimens (type-II/(type-I + type-II + d-Si)) deduced by powder X-ray diffraction and Rietveld analysis was maintained at approximately 85%. These preparation techniques that enable the high-yield synthesis of semiconductive type-II Si clathrates open opportunities for the application of these substances to semiconductor devices.     

Exact solution of transient thermal stress problem of a multilayered magneto-electro-thermoelastic hollow sphere

This paper presents the theoretical analysis of a multilayered magneto-electro-thermoelastic hollow sphere under unsteady and uniform surface heating. We obtain the exact solution of the transient thermal stress problem of the multilayered magneto-electro-thermoelastic hollow sphere in the spherically symmetric state. As an illustration, we perform numerical calculations of a two-layered composite hollow sphere made of piezoelectric and magnetostrictive materials and investigate the numerical results for temperature change, displacement, stress, and electric and magnetic potential distributions in the transient state are shown in figures.     

Relationship between sound insulation performance of walls and word intelligibility scores

Conversations must be shielded from people in an adjacent room if they include confidential information. Word intelligibility tests were performed in a total of 185 sound fields to examine the relationship between sound insulation performance and the degree of conversation leakage. The parameters of the test sound fields were background noise level in the adjacent room and the level difference between the two rooms. The background noise level was varied from 30 to 50 dB (A-weighted). The level difference was parametrically varied in terms of eight frequency characteristics and 10 absolute values. The results showed that word intelligibility scores were strongly correlated with the A-weighted speech-to-noise ratio and SNR_uni32. Equal-intelligibility contours, which can easily show the weighted level difference and A-weighted background noise level required to achieve a certain level of word intelligibility scores, were obtained from a multiple logistic regression analysis.     

Superconductivity induced by longitudinal ferromagnetic fluctuations in UCoGe

From detailed angle-resolved NMR and Meissner measurements on a ferromagnetic (FM) superconductor UCoGe (T(Curie)～2.5 K and T(SC)～0.6 K), we show that superconductivity in UCoGe is tightly coupled with longitudinal FM spin fluctuations along the c axis. We found that magnetic fields along the c axis (H∥c) strongly suppress the FM fluctuations and that the superconductivity is observed in the limited magnetic-field region where the longitudinal FM spin fluctuations are active. These results, combined with model calculations, strongly suggest that the longitudinal FM spin fluctuations tuned by H∥c induce the unique spin-triplet superconductivity in UCoGe. This is the first clear example that FM fluctuations are intimately related with superconductivity.     

Miscibility, mechanical and thermal properties of poly(lactic acid)/polyester-diol blends

We found new plasticizers with high molecular weight and low mobility for poly(lactic acid) (PLA). The new plasticizers are polyester-diols (PED) with nominal molecular weight 2000. Temperature dependence of oscillatory tensile moduli of PLA/PED blends in solid states was measured and miscible pairs of the blends were found. The miscible pairs are PLA/poly(ethylene adipate) and PLA/poly(diethylene adipate). Observation by scanning electron microscope and results of differential scanning calorimetry also indicate that these blends are miscible with PLA at weight ratio of PED less than or equal to 20%. In these blends, glass transition temperature is significantly lower than that of PLA. On the other hand, poly(butylene adipate) and poly(hexamethylene adipate) are partially miscible with PLA at weight ratio of PED 20%. The difference of the miscibility is discussed in terms of solubility parameter, which is calculated using the method by Small and configurational entropy.     

Ultralow-jitter passive timing stabilization of a mode-locked Er-doped fiber laser by injection of an optical pulse train

The pulse timing of a mode-locked Er-doped fiber laser was stabilized to a reference pulse train from a Cr:forsterite mode-locked laser by all-optical passive synchronization scheme. The reference pulses were injected into a ring cavity of the fiber laser by using a 1.3-1.5 mum wavelength-division multiplexer. The spectral shift induced by cross-phase modulation between copropagating two-color pulses realizes self-synchronization due to intracavity group-delay dispersion. The rms integration of timing jitter between the fiber laser pulse and the reference pulse was 3.7 fs in a Fourier frequency range from 1 Hz to 100 kHz.     

Binding thermodynamics of metal ions to HIV-1 ribonuclease H domain

Journal of Thermal Analysis and Calorimetry - Metal–protein interactions are not necessarily tight in many transient biological processes, such as cellular signaling, enzyme regulation, and...