Stable cavitation induces increased cytoplasmic calcium in L929 fibroblasts exposed to 1-MHz pulsed ultrasound

An increase in cytoplasmic calcium (Ca²⁺ increase) is a second messenger that is often observed under ultrasound irradiation. We hypothesize that cavitation is a physical mechanism that underlies the increase in Ca²⁺ in these experiments. To control the presence of cavitation, the wave type was controlled in a sonication chamber. One wave type largely contained a traveling wave (wave type A) while the other wave type largely contained a standing wave (wave type B). Fast Fourier transform (FFT) analysis of a sound field produced by the wave types ascertained that stable cavitation was present only under wave type A ultrasound irradiation. Under the two controlled wave types, the increase in Ca²⁺ in L929 fibroblasts was observed with fluorescence imaging. Under wave type A ultrasound irradiation, an increase in Ca²⁺ was observed; however, no increase in Ca²⁺ was observed under wave type B ultrasound irradiation. We conclude that stable cavitation is involved in the increase of Ca²⁺ in cells subjected to pulsed ultrasound.     

Notoamide E: Biosynthetic incorporation into notoamides C and D in cultures of Aspergillus versicolor NRRL 35600

Notoamide E, a short-lived secondary metabolite, has been proposed as a biosynthetic intermediate to several advanced metabolites isolated from Aspergillus versicolor. In order to verify the role of this indole alkaloid along the biosynthetic pathway, synthetic doubly ¹³C-labeled notoamide E was fed to Aspergillus versicolor. Analysis of the metabolites showed significant incorporation of notoamide E into the natural products notoamides C and D.     

Spironaamidine, a new spiroquinone-containing alkaloid from the marine sponge Leucetta microraphis

Spironaamidine (1), a unique spiroquinone-containing alkaloid, was isolated from the marine sponge, Leucetta microraphis, along with two known imidazole alkaloids, naamidine H (2) and (9E)-clathridine 9-N-(2-sulfoethyl)imine (3). Spironaamidine (1) showed antimicrobial activity against Bacillus cereus.     

Micromagnetic recording field analysis of fast-switching single-pole-type heads for bit-patterned media

A Landau–Lifshitz–Gilbert (LLG) micromagnetic analysis of the recording field of single-pole-type (SPT) heads was carried out. The whole volume comprising the SPT head and the double-layered medium was treated micromagnetically using the finite-difference method with cubic cells as small as 5 nm, giving a total number of cells of more than 10.8 million. A parallelized fast Fourier transform (FFT) method was used to solve this large-scale problem. Dynamic recording fields were calculated for various head structures and head materials. The timing (synchronization) between the dynamic head field and land location in bit-patterned media (BPM) is discussed and the design methodology is discussed for a fast-switching SPT head.     

Micromagnetic recording field analysis of a fast-switching single-pole-type head

Single-pole-type (SPT) heads for perpendicular magnetic recording were investigated using a Landau–Lifshitz–Gilbert (LLG) micromagnetic analysis program running on a PC cluster system. Dynamic recording fields were calculated for various driving currents, head structures and head materials. The dynamic head field response is discussed with regard to the write timing window for bit-patterned media, as described in previous papers.     

Controlled Synthesis of Au25 Superatom Using a Dendrimer Template

Superatoms are promising materials for their potential in elemental substitution and as new building blocks. Thus far, various synthesis methods of thiol-protected Au clusters including an Au₂₅ superatom have been investigated. However, previously reported methods were mainly depending on the thermodynamic stability of the aimed clusters. In this report, a synthesis method for thiol-protected Au clusters using a dendrimers template is proposed. In this method, the number of Au atoms was controlled by the stepwise complexation feature of a phenylazomethine dendrimer. Therefore, synthesis speed was increased compared with the case without the dendrimer template. Hybridization for the Au₂₅ superatoms was also achieved using the complexation control of metals.