Growth of self-integrated atomic quantum wires and junctions of a Mott semiconductor

1ナノメートル半導体量子細線の作製に成功 --量子の熱帯魚パターンが拓く未来のナノテク--. 京都大学プレスリリース. 2023-05-08.Continued advances in quantum technologies rely on producing nanometer-scale wires. Although several state-of-the-art nanolithographic technologies and bottom-up synthesis processes have been used to engineer these wires, critical challenges remain in growing uniform atomic-scale crystalline wires and constructing their network structures. Here, we discover a simple method to fabricate atomic-scale wires with various arrangements, including stripes, X-junctions, Y-junctions, and nanorings. Single-crystalline atomic-scale wires of a Mott insulator, whose bandgap is comparable to those of wide-gap semiconductors, are spontaneously grown on graphite substrates by pulsed-laser deposition. These wires are one unit cell thick and have an exact width of two and four unit cells (1.4 and 2.8 nm) and lengths up to a few micrometers. We show that the nonequilibrium reaction-diffusion processes may play an essential role in atomic pattern formation. Our findings offer a previously unknown perspective on the nonequilibrium self-organization phenomena on an atomic scale, paving a unique way for the quantum architecture of nano-network

ウシ κ-カゼイン ノ フキンイツセイ ニ カンスル ケンキュウ ノウゲイ カガク ブモン

牛κ-カゼインの不均一性を調べるため, Zittle-Custer法で調製したκ-カゼインを, β-メルカプトエタノールで還元した後, 0.02Mイミダゾール・塩酸緩衝液(pH 7.0), NaCl濃度勾配(0.02M∿0.2M)を用いて, DEAEセルロースクロマトグラフィーをおこない, 非吸着画分を含めて6画分を得た。(P-1∿P-6)澱粉ゲル電気泳動(pH 8.6)において, P-1は負極へ移動するが, 他の5画分は, 高い塩濃度で溶出する画分ほど, 正極へより多く移動する傾向が見られた。6画分の化学組成を調べた結果, シアル酸含有量に著しい差異が見られ, P-1とP-2には全くシアル酸が含まれず, P-3∿P-6では, 高い塩濃度で溶出する画分ほど, シアル酸を多く含んでいた。アミノ酸組成は, どの画分もほぼ同じであった。6画分のうち, P-1以外は, κ-カゼインの特徴であるα_S-カゼイン安定化能を有している。The heterogeneity of bovine κ-casein was studied. κ-Casein was prepared from fresh bovine milk by the method of Zittle and Custer. After the reduction of κ-casein with β-mercaptoethanol, it was fractionated by chromatography on a column of DEAE cellulose with linear gradient system of sodium chloride (0.02M to 0.2M) in imidazole-HCl buffer, pH 7.0. Six fractions (P-1 to P-6) were obtained including a non absorbed fraction to the column. In the starch gel electrophoresis, the fractions migrated to anode except the fraction P-1 which was mobile to the cathode. The sequence of mobilities in electrophoresis coincides exactly with the sequence of the elution on DEAE cellulose chromatography in the gradient system. The amino acid compositions of these fractions are almost the same except the fraction P-1 but the sialic acid contents are different greatly. All these fractions (P-2 to P-6) had the ability of stabilizing α_S-casein and the removement of sialic acid is of no effect on that stabilizing effect. It is concluded that the heterogeneity of κ-casein is attributed to the difference of the sialic acid contents

各種保存条件下での牛乳κ-カゼインの変化(農芸化学部門)

UHT滅菌乳の長期貯蔵による沈殿生成やゲル化の機構を解明する予備実験として, 牛乳κ-カゼインの各種保存条件下における変化を, 安定化能, 4.5M尿素を含むディスクおよびSDS-ポリアクリルアミドゲル電気泳動により検討した。保存条件としては, 温度-20,4,25℃で, 溶液(70mM KCIを含む10mMイミダゾール塩酸緩衝液pH7.1,4.5M尿素, 蒸留水, 濃度はいずれも10mg/ml)中または, 凍結乾燥標品の12種を設定し, 1,3,5,7ケ月間の保存状態を検討した。-20℃では, ほとんど変化せず, いずれも保存状態は良好であった。4℃では, 4.5M尿素中および凍結乾燥品での保存が良かった。また, 25℃では, 凍結乾燥保存を除き, 全般的に保存性は悪かった。両電気泳動の結果から, 長期保存によってκ-カゼインは高分子化や分解が進んでいることが明らかとなり, 同時に, それらの進行と安定化能の低下との間に相関が認められた。The formation of precipitate and the gelation of ultra high-temperature sterilized milk have been observed during the long storage. As the preliminaly experiments to make clear the mechanism of these phenomena, the effects of various preservative conditions on bovine κ-casein were investigated by the stabilizing ability test for α_-casein in the presence of calcium ion, disc gel electrophoresis containing 4.5M urea and sodium dodecylsufate (SDS)-polyacrylamide gel electrophoresis. κ-Casein was stored at -20°, 4°and 25℃ as the solution dissolved in 10mM imidazole-HCl-70mM KCl buffer (pH7.1), 4.5M urea and distilled water and as the lyophilized material for 1,3,5 and 7 months. When κ-casein was stored at -20℃ at various states, the stabilizing ability was maintained and the behaviors on both electrophoreses were not different from those of native one, though the samples at 25℃ lost the ability quickly. The preservation at 4℃ in 4.5M urea solution did not affect on the properties of κ-casein. The lyophilized material was stable at every tested temperatures through the experimental period. It was considered that the loss of stablizing ability of κ-casein was due to the polymerization and the degradation from the results of disc and SDS gel electrophoreses

Acute effect of electrical stimulation on the infraspinatus muscle using different types of muscle contractions and shoulder joint positions

BACKGROUND: Electrical stimulation (ES) is considered to be effective on infraspinatus muscle with functional decline and atrophy. However, it is not clear which parameters of ES e.g., types of muscle contractions and shoulder joint positions have good effects for inducing hypertrophy and increasing muscular strength. The purpose of this study was to determine the acute effects of ES in different types of muscle contractions and shoulder joint positions on the infraspinatus muscle by measuring the muscle swelling after ES. METHODS: Forty subjects were randomly assigned to one of five groups: an isometric contraction with maximum internal rotation (IR), an isometric contraction with neutral position of rotation (NEUT), an isometric contraction with maximum external rotation (ER), a concentric contraction (CONCEN), and a control (CON) group. Subjects in all groups except for the CON group received ES for 20 min. The CON group did not receive intervention. The muscle thicknesses of the superior and inferior infraspinatus were measured using ultrasonography before and immediately after a single ES intervention. RESULTS: Percentage change in muscle thickness of the inferior infraspinatus was greater in the IR and NEUT groups than the muscle thickness of the CON group; however, the muscle thickness of the superior infraspinatus did not differ significantly among the groups. CONCLUSIONS: The results of this study indicate that applying ES to the inferior infraspinatus muscle in an isometric contraction with the muscle in a stretched position is an effective method to induce greater muscle swelling

Effects of a Thermal Agent and Physical Activity on Muscle Tendon Stiffness, as Well as the Effects Combined With Static Stretching

Context: A recent review or article reported that thermal agents (TA) or physical activity (PA) can increase range of motion (ROM) and that the combination of TA with stretching is superior to performing stretching only. However, since ROM is affected by the psychological factors, it is questionable whether these studies measured the effect of these interventions on muscle flexibility. By measuring muscle stiffness, the authors attempted to evaluate the effect these interventions on muscle flexibility. Objective: To compare the individual effects of TA and PA on muscle flexibility, as well as their effectiveness when combined with static stretching (SS). Design: Crossover trial. Setting: University research laboratory. Participants: 15 healthy men without a history of orthopedic disease in their lower limbs. Interventions: 15 minutes of 3 different conditions: hot pack as TA, pedaling exercise as PA, and the control group with no TA or PA intervention, followed by 3 min of SS for the hamstrings. Main Outcome Measures: Joint angle and passive torque of the knee during passive elongation were obtained prior to interventions, after 3 kinds of intervention, and after SS. From these data, muscle-tendon-unit (MTU) stiffness of the hamstrings was calculated. Results: Although knee-joint ROM increased with both TA and PA (P < .05), there were no significant differences in MTU stiffness between pre- and postintervention measurements for either of the interventions (TA, P = .477; PA, P = .377; control, P = .388). However, there were similar significant decreases in MTU stiffness between postintervention and post-SS for all conditions (P < .01). Conclusions: TA and PA did not decrease MTU stiffness, and combining these interventions with SS did not provide additional decreases in MTU stiffness compared with performing SS alone