Kaon interferometry in heavy-ion collisions at the CERN SPS

K⁺K⁺ and K^–K^– correlations from S+Pb collisions at 200 GeV/c per nucleon and K⁺K⁺ correlations from p+Pb collisions at 450 GeV/c per nucleon, are presented as measured by the focusing spectrometer of the NA44 experiment at CERN. Multidimensional fits are performed in order to characterize the kaon-emission volume, which is found to be smaller than the pion-emission volume.     

Identification of the source of the crude drug Tu-zhu-ye using low-temperature plasma ashing

Tu-zhu-ye is a Korean crude drug for use as a diuretic but its plant source has not been identified. The present work has been attempted for identification of the original plant using specimens collected both at Seoul and Taegu, Korea, their mineral microstructures being examined after ashing the specimens by a low-temperature method with high-frequency oxygen plasma. A preliminary survey of the specimens with the naked eye suggested that the Tu-zhu-ye was near to Phyllostachys or its closely related bamboo species. Several specimens, namely, Phyllostachys heterocyclaMitf. var. pubescensOhwi, Phyllostachys nigraMunro var. henonisStapf, Phyllostachys bambusoidesSieb. et Zucc. and Bambusa multiplexRaeuschel were therefore ashed by the low-temperature method and the comparative microscopic studies with the resultant ashed tissues concluded that the “Tu-zhu-ye” from Seoul was perfectly identical with Phyllostachys nigraMunro var. henonisStapf. A further investigation is continued for the specimen from Taegu since it is different from any other specimens provided for the present work.     

Quadruple Decker [3.3][3.3][3.3]Orthocyclophane Acetal—An Orthocyclophane Ladder

Through clever bridging of orthocyclophanes (in this case by acetalization), molecules such as 1 can be formed with four benzene rings in a stacked face-to-face arrangement. UV/Vis spectroscopic and electrochemical properties of 1 are governed by π–π through-space interactions within the molecule.     

Second-generation synthesis of endogenous sperm-activating and attracting factor (SAAF) isolated from the ascidian Ciona intestinalis

Stereoselective synthesis of the chemoattractant sperm-activating and attracting factor (SAAF), isolated from the eggs of the ascidian Ciona intestinalis, was achieved via reductive 1,3-transposition of an allylic alcohol and the axial opening of an epoxide as key steps. This second-generation synthesis improved the total yield of SAAF over that of the first-generation synthesis and provided a key intermediate for synthesizing molecular probes of SAAF.     

Mass-tag technology responding to intracellular signals as a novel assay system for the diagnosis of tumor

A novel mass spectrometry-based assay system for determining protein kinase activity employing mass-tagged substrate peptide probes was used for the diagnosis of tumors. Two peptide probes (H-type and D-type) were synthesized containing the same substrate peptide sequence for protein kinase C (PKC). The molecular weights of the two probes differ because of the incorporation of deuterium into the acetyl groups of the D-type probe. The lysates of the normal and tumor tissue were prepared and reacted with the H- and D-type peptide probes, respectively. The PKC activities of the normal and tumor tissues can be compared simply and directly by calculating the phosphorylated ratio to each peptide probe, obtained from the peak intensity of the mass spectrum after mixing of the two reaction solutions. The phosphorylation ratio for the reaction of the H-type peptide probe with the tumor tissue lysate (B16 melanoma) was more than three times higher than that of the D type peptide probe with the normal skin tissue lysate. These results show that the novel assay system for detecting protein kinase activity using mass-tag technology can be a simple and useful means to profile protein kinase activity for cell or tissue lysate samples, and can be applied to the diagnosis of tumors.     

Radiation source dependence of device performance degradation for 4H-SiC MESFETs

The impact of radiation source dependence on the device performance degradation of 4H-SiC MESFETs (Metal Schottky Field Effect Transistors), which have been irradiated at room temperature with 2 MeV electrons and 20 MeV protons, is studied. No performance degradation is observed by 1×10¹⁵ e/cm² and 5×10¹¹ p/cm², while a slight increase of the linear drain current together with a decrease of the threshold voltage are noticed above higher fluence. The damage coefficient for protons is about three orders of magnitude larger than that for electrons. The radiation source dependence of the device performance degradation is attributed to the difference of mass and the possibility of nuclear collision for the formation of lattice defects. Based on thermal annealing results of electron-irradiated MESFETs, it is found that the recovery of the drain current characteristics principally takes place from 100 C, and that the drain current recovers to the pre-rad value after 200 C annealing. On the other hand, capacitance and induced deep levels do not recover by 200 C annealing. It is concluded that the degradation of the drain current is mainly sensitive to the radiation-induced decrease of the Schottky barrier height at the gate contact.