含氧气氛下电子束辐照聚碳硅烷制备碳化硅纤维

以聚碳硅烷(polycarbosilane,PCS)为原料,在含氧气(1%)的气氛下用电子束低剂量辐照PCS原丝,然后在惰性气氛下退火实现不熔化处理并烧成制得碳化硅(SiC)纤维。分析了退火温度对辐照后PCS的氧含量、凝胶含量及化学结构的影响,研究了PCS在含氧气氛下辐照及在惰性气氛下退火所发生的化学反应。结果表明:在辐照过程中,主要是Si—H与O2反应生成Si—OH;在退火过程中,主要是Si—OH缩合脱水生成Si—O—Si交联结构。在1250℃烧成制得的SiC纤维呈芯–壳结构,表壳富氧,而芯部氧含量较低。纤维的平均拉伸强度为2.4GPa,平均弹性模量为170.1GPa

サトウキビ野生種と製糖用品種との種間雑種を利用して作出した熊毛地域向け株出し多収品種「はるのおうぎ」

“Harunoogi” is a new sugarcane cultivar jointly developed by the NARO Kyushu Okinawa Agricultural Research Center and the Japan International Research Center for Agricultural Sciences. It shows vigorous initial growth after ratooning and high ratoon yield in the Kumage region in the Kagoshima Prefecture, and has been applied for variety registration for the region in March 2019. “Harunoogi” was selected from progenies derived from crossing between a high ratoon yield forage cultivar “KRFo93-1” as seed parent and a thick-stalk early maturing cultivar “NiN24” as pollen parent. The “KRFo93-1” was developed by interspecific hybridization of a commercial sugarcane cultivar with a wild sugarcane (Saccharum spontaneum L.). Ratooning ability and number of tillers of “Harunoogi” are higher than those of “NiF8”, which is a major cultivar in the Kumage region. Even though single stalk weight of “Harunoogi” is smaller than “NiF8”, stalk yield is much higher compared to “NiF8” due to its large number of millable stalks in both plant and ratoon crops. Sucrose content of “Harunoogi” is comparable with “NiF8”. As a result, sugar yield of “Harunoogi” is much higher than “NiF8”. In addition, “Harunoogi” has good adaptability for mechanical harvesting because of its high lodging-resistance and vigorous initial growth in ratoon crop after mechanical harvesting. High ratoon yield under mechanical harvesting system has been recognized as one of the most important characteristics of sugarcane cultivar in the Kumage region where ratoon yield has been decreasing for recent years. “Harunoogi” is expected to play an important role in recovery from a decline of sugarcane yield in the region.「はるのおうぎ」は，農研機構九州沖縄農業研究センターおよび国際農林水産業研究センターが共同育成した，萌芽 性に優れる株出し多収のサトウキビ品種である．鹿児島県熊毛地域を普及見込み地域として 2019 年 3 月に品種登録出願した．本品種は，サトウキビ製糖用品種と野生種との種間雑種で株出し多収性を特徴とする飼料用サトウキビ品種KRFo93-1」を種子親，早期高糖性を特徴とする製糖用品種「NiN24」を花粉親とする交配に由来し，株出し多収性と高糖性を重視した選抜を経て育成された．萌芽性は “ 極高 ” であり，萌芽率は熊毛地域の主要品種「NiF8」を常に上回る分げつ性は “ 強 ” であり，熊毛地域では原料茎数が「NiF8」の 1.4 倍から 2.0 倍に達する．一茎重は「NiF8」より軽いが茎数が多いため，原料茎重は春植え，株出しともに「NiF8」に比べて多い．甘蔗糖度は「NiF8」と同程度である．原料茎重と甘蔗糖度の結果から，可製糖量は春植え，株出しともに「NiF8」を大きく上回る．また，耐倒伏性に優れるため機械収穫しやすく，機械収穫後の萌芽も良好である．株出し単収が減少傾向にある熊毛地域において，単収の回復に寄与することが期待され

Measurement of low-energy antiproton detection efficiency in BESS below 1 GeV

An accelerator experiment was performed using a low-energy antiproton beam to measure antiproton detection efficiency of BESS, a balloon-borne spectrometer with a superconducting solenoid. Measured efficiencies showed good agreement with calculated ones derived from the BESS Monte Carlo simulation based on GEANT/GHEISHA. With detailed verification of the BESS simulation, the relative systematic error of detection efficiency derived from the BESS simulation has been determined to be $\pm$5%, compared with the previous estimation of $\pm$15% which was the dominant uncertainty for measurements of cosmic-ray antiproton flux.Comment: 13 pages, 7 figure