Pressure-Induced Change in the Long-Period Stacking Sequence of the Close-Packed Layers in Mg_3In(Physics)

Samples of the alloy Mg_3In were annealed at 200-250℃ in the Bridgman-anvil-type press under pressures between 20 and 100 kbar. After being quenched to ambient pressure and temperature, the crystal structure was studied by X-ray diffraction. The number of close-packed layers in one repeating unit of the alloy structure is twelve with the stacking sequence (31)_3 when annealed under the atmospheric pressure, but at 20, 35 and 55 kbar it increases to eighteen with the sequence (3111)_3, and at 75 and 100 kbar a 24-layered structure with the sequence (311111)_3 has been found to form. The pressure-induced change in the layer-stacking sequence in Mg_3In is similar to the change with the decrease in the electron-atom ratio previously observed for the ternary alloys Mg_3(In_, Cd_x)

Synthesis of Polycyclic Spirocarbocycles via Acid-Promoted Ring-Contraction/Dearomative Ring-Closure Cascade of Oxapropellanes

We report herein the development of an acid-promoted rearrangement of oxa[4.3.2]propellanes to afford polyaromatic-fused spiro[4.5]carbocycles. DFT calculations suggest that the reaction pathway involves generation of a cyclobutyl cation, ring contraction to the cyclopropylcarbinyl cation, and dearomative ring closure by an internal 2-naphthol moiety. The resulting spirocarbocycles are synthetically valuable, as they could be transformed into two different polycyclic aromatic hydrocarbons via skeletal rearrangement. Syntheses of optically pure spirocarbocycles via a central-to-axial-to-central chirality transfer are also described

尿道原発と考えられた悪性リンパ腫の1例

82歳女.主訴は排尿困難と残尿感.膀胱底部から尿道周囲にかけて鶏卵大の腫瘤を認め, 生検で非ホジキンリンパ腫と診断された.他臓器に病変を認めなかった為, 尿道原発の悪性リンパ腫と診断し放射線療法を施行した.治療後, 腫瘍は著明に縮小したが肺転移が出現した.エトポシド単剤による化学療法を追加したが, 放射線治療後5ヵ月で腫瘍の急激な増加を認め癌死したA patient with a primary malignant lymphoma surrounding the female urethra is reported. Despite the good response of the primary tumor to radiotherapy, the patient died shortly after diagnosis due to disseminated disease. We reviewed 16 cases of this rare entity reported previously

Helical Nanographenes Embedded with Contiguous Azulene Units

うねり構造をもつグラフェンナノリボンの精密合成に成功 --非ベンゼノイド構造の新規構築反応を開発--. 京都大学プレスリリース. 2020-07-20.The azulene moiety, composed of contiguous pentagonal and heptagonal rings, is a structural defect that alters the electronic, magnetic, and structural properties of graphenes and graphene nanoribbons. However, nanographenes embedded with an azulene cluster have not been widely investigated because these compounds are difficult to synthesize in their pure form. Herein, azulene-embedded nanographenes bearing a unique cove-type edge were synthesized by a novel synthetic protocol. Experimental and theoretical investigations revealed that this cove edge imparts stable helical chirality, unlike normal cove edges. The in-solution self-association behavior and the structural, electronic, and electrochemical properties were also described in detail

An X-ray Investigation of Thermal Mean-Square Atomic Displacements in Magnesium, Cadmium and Mg_3Cd

Measurements have been made of integrated intensities of X-ray symmetrical reflections from single crystals of magnesium, cadmium and Mg_3Cd, kept at temperatures ranging from room temperature to about 90°K. It is observed that the thermal mean-square atomic displacements along two directions, the one parallel to the hexagonal c-axis u_z^2 and the other perpendicular to the c-axis u_x^2, are nearly the same in Mg_3Cd, showing little anisotropy. The result suggests that thermal vibrational amplitudes in the alloy can not be a simple average of those in magnesium and cadmium. No appreciable difference is observed between the mean-square displacements of an ordered and an imperfectly ordered Mg_3Cd. The mean-square atomic displacements is calculated for magnesium and cadmium applying Zener\u27s theory of thermal vibration in hexagonal crystals and is compared with the observed displacements. Discussions are given on the correlation between u_z^2 / u_x^2 and the axial ratio, c/a, of hexagonal close-packed metals and also on the thermal mean-square displacements in alloys

miR-200b Precursor Can Ameliorate Renal Tubulointerstitial Fibrosis

Members of the miR-200 family of micro RNAs (miRNAs) have been shown to inhibit epithelial-mesenchymal transition (EMT). EMT of tubular epithelial cells is the mechanism by which renal fibroblasts are generated. Here we show that miR-200 family members inhibit transforming growth factor-beta (TGF-beta)-induced EMT of tubular cells. Unilateral ureter obstruction (UUO) is a common model of EMT of tubular cells and subsequent tubulointerstitial fibrosis. In order to examine the role of miR-200 family members in tubulointerstitial fibrosis, their expression was investigated in the kidneys of UUO mice. The expression of miR-200 family miRNAs was increased in a time-dependent manner, with induction of miR-200b most pronounced. To clarify the effect of miR-200b on tubulointerstitial fibrosis, we injected miR-200b precursor intravenously. A single injection of 0.5 nM miR-200b precursor was sufficient to inhibit the increase of collagen types I, III and fibronectin in obstructed kidneys, and amelioration of fibrosis was confirmed by observation of the kidneys with Azan staining. miR-200 family members have been previously shown to inhibit EMT by reducing the expression of ZEB-1 and ZEB-2 which are known repressors of E-cadherin. We demonstrated that expression of ZEB-1 and ZEB-2 was increased after ureter obstruction and that administration of the miR-200b precursor reversed this effect. In summary, these results indicate that miR-200 family is up-regulated after ureter obstruction, miR-200b being strongly induced, and that miR-200b ameliorates tubulointerstitial fibrosis in obstructed kidneys. We suggest that members of the miR-200 family, and miR-200b specifically, might constitute novel therapeutic targets in kidney disease

A high harmonic gyrotron with an axis-encircling electron beam and a permanent magnet

A gyrotron with an axis-encircling electron beam is capable of high-frequency operation, because the high-beam efficiency is kept even at high harmonics of the electron cyclotron frequency. We have designed and constructed such a gyrotron with a permanent magnet. The gyrotron has already operated successfully at the third, fourth, and fifth harmonics. The frequencies are 89.3, 112.7, and 138 GHz, respectively, and the corresponding cavity modes are TE/sub 311/, TE/sub 411/, and TE/sub 511/. The permanent magnet system is quite novel and consists of many magnet elements made of NbFeB and additional coils for controlling the field intensities in the cavity and electron gun regions. The magnetic field in the cavity region can be varied from 0.97 to 1.18 T. At the magnetic field intensities, the output powers at the third and the fourth harmonics are 1.7 and 0.5 kW, respectively. The gyrotron is pulsed, the pulse length is 1 ms and the repetition frequency is 1 Hz. The beam energy is 40 kV and the beam current is 1.2-1.3 A. Beam efficiencies and emission patterns have also been measured. In this paper, the experimental results of the gyrotron are described and compared with computer simulations