Mid-infrared supercontinuum generation in a four-hole As2S5 chalcogenide microstructured optical fiber

We demonstrate the supercontinuum (SC) generation in a four-hole As₂S₅ chalcogenide microstructured optical fiber (MOF) experimentally. The As₂S₅ glass has better property of transmission than As₂S₃ glass in the visible range. The four-hole As₂S₅ MOF is fabricated by a rod-in-tube method. The SCs generated by different pump wavelengths at 2,000, 2,300 and 2,500 nm in the MOF whose length is from 2.3 to 20 cm are demonstrated. Those pump wavelengths correspond to the chromatic dispersion wavelength in the normal chromatic dispersion region, the anomalous chromatic dispersion region close to zero-dispersion wavelength (ZDW) and the anomalous chromatic dispersion region far from ZDW, respectively. Wider SCs can be obtained when pumped at a wavelength in the anomalous dispersion region close to ZDW. The widest SC range of 4,280 nm (from 1,370 to 5,650 nm) covering two octaves was obtained in a 4.8-cm-long fiber pumped at 2,300 nm.     

Hemorrhagic cerebral metastases from thyroid cancer on T2*-weighted gradient echo MRI

We report a case of multiple hemorrhagic cerebral metastases from papillary thyroid cancer, with reference to T(2)*-weighted gradient echo (GRE) magnetic resonance imaging (MRI). Small metastatic nodules were recognized as round nodules with signal loss on T(2)*-weighted GRE MRI, and were more pronounced compared with other sequences. Lesions were later confirmed as hemorrhagic on T(1)- and T(2)-weighted MRI. T(2)*-weighted GRE MRI was a sensitive tool for early detection of metastases displaying hemorrhagic changes.     

A thiol-mediated active membrane transport of selenium by erythroid anion exchanger 1 protein

In this paper, we describe a thiol-mediated and energy-dependent membrane transport of selenium by erythroid anion exchanger 1 (AE1, also known as band 3 protein). The AE1 is the most abundant integral protein of red cell membranes and plays a critical role in the carbon dioxide transport system in which carbon dioxide is carried as bicarbonate in the plasma. This protein mediates the membrane transport of selenium, an essential antioxidant micronutrient, from red cells to the plasma in a manner that is distinct from the already known anion exchange mechanism. In this pathway, selenium bound to the cysteine 93 of the hemoglobin β chain (Hb-Cysβ93) is transported by the relay mechanism to the Cys317 of the amino-terminal cytoplasmic domain of the AE1 on the basis of the intrinsic interaction between the two proteins and is subsequently exported to the plasma via the Cys843 of the membrane-spanning domain. The selenium export did not occur in plain isotonic buffer solutions and required thiols, such as albumin, in the outer medium. Such a membrane transport mechanism would also participate in the export pathways of the nitric oxide vasodilator activity and other thiol-reactive substances bound to the Hb-Cysβ93 from red cells to the plasma and/or peripherals.     

Cyclization reaction of n-propargyl epoxyamide to acetylenic 2-azetidinone,a precursor to thienamycin and related carbapenems

Base treatment of N-propargyl epoxyamide 5 afforded the acetylenic 3-(hydroxyethyl)-2-azetidinone 9a, which was subsequently transformed to phenyl thiolester 2, a versatile intermediate for the carbapenem synthesis.     

Total synthesis of (±)-pyrenolide B

Synthesis of the title compound is described.     

Stereospecific synthesis of dinucleoside monophosphate aryl esters by using new condensing reagents

Abstract

New condensing reagents, arenesulfonyl 5-(pyridin-2-yl)tetrazoles have been synthesized and used for stereospecific synthesis of dinucleoside monophosphate aryl esters.     

Diet and gastrointestinal signal on T1-weighted magnetic resonance imaging of mice

In magnetic resonance (MR) imaging of small animals, the gastrointestinal contents may give rise to intense signals on T1-weighted images. The aim of this study was to determine the optimal dietary preparation to reduce gastrointestinal signals in mice and to evaluate the usefulness of this approach. Images of the mouse trunk were obtained using a T1-weighted, three-dimensional fast low-angle shot sequence under various dietary conditions and were compared with respect to the gastrointestinal signals and image quality. The dietary preparation studied included giving alternative diets for 24 h, intestinal cleansing, and 6-h fasting. Mice with and without dietary preparation underwent MR lymphography using gadofluorine 8, and the visualization of abdominal lymph nodes was compared. In the absence of dietary preparation, hyperintense areas were conspicuous in the gastrointestinal system, whereas on the images taken from mice fed potato or sweet potato for 24 h before imaging, gastrointestinal hyperintensity was less prominent. This preparation also reduced artifactual signals and resulted in higher-quality images of the kidneys. Intestinal cleansing, which consisted of 24-h fasting and laxative intake, did not reduce the gastrointestinal signals and caused signal changes that were indicative of fatty liver development. Some of the abdominal lymph nodes of the mice that did not receive dietary preparation were visualized on MR lymphography source images but not on maximum intensity projection (MIP) images. In contrast, on the MIP images of mice fed potato, all the lymph nodes delineated on the source images were successfully visualized. In conclusion, feeding mice potato or sweet potato for 24 h before MR imaging reduces the gastrointestinal signals and image degradation due to artifacts. Appropriate dietary preparations facilitate the display of target structures on MIP images and are expected to enhance the capabilities of small animal MR imaging.     

Raman sum rule and the relation to the infrared sum rule in La2-xSrxCuO4

Electronic Raman scattering has no sum rule in no and weak correlation, but the existence of sum rule has been proposed in strong correlation. The present Raman scattering disclosed that the first moment of the Raman susceptibility is proportional to the generalized moment of the optical conductivity in the metallic phase. The present experiment disclosed that a large amount of electronic states are incoherent states. The incoherent states are the relevant states for the superconductivity, because the gap opens in the incoherent states as well as the coherent states.     

Syntheses of glucose-containing E5564 analogues and their LPS-antagonistic activities

Lipid A analogues containing a glucose moiety on their non-reducing end were synthesized, and their LPS-antagonistic activities were measured. The inhibitory activities (IC₅₀) on LPS-induced TNFα production of these six compounds, 26, 33, 44β, 52β, 59, and 61, toward human whole blood cells were 0.49, 0.65, 0.51, 0.98, 0.46, and 1.11 nM, respectively. Inhibitory doses (ID₅₀) of compounds 26, 33, 44β, 59, and 61 on TNFα production induced by coinjection of galactosamine and LPS in C3H/HeN mice were measured. The ID₅₀ values of these compounds were 0.45, 0.96, <0.2, 1.08, and <0.2 mg/kg, respectively. Moreover, C3H/HeN mice preinjected with compounds 26, 33, and 44β were protected from lethality induced by coinjection of galactosamine and LPS. Out of eight mice preinjected with 1 mg/kg of compounds 26, 33, and 44β, five, eight and six mice were protected, respectively.     

Analytical isotachophoresis utilizing computer simulation. II. Assessment of optimum separation conditions for urinary trifluoroacetic acid metabolized from anaesthetic halothane

Experimentally determined optimum separation conditions for a metabolite of anaesthetic halothane in urine, trifluoroacetic acid, were assessed by means of computer simulation of the isotachophoretic steady-state. The simulation confirmed that urinary acids and trifluoroacetic acid can be separated in the limited pH range of 3.5-3.7 buffered by beta-alanine, as far as the pH dependence of effective mobility is utilized. The separated fraction of the trifluoroacetic acid zone was identified by mass spectrometry. The simulated coefficient of the calibration curve agreed well with the observed value.