We present optical spectra of 10 Galactic Wolf-Rayet(WR)stars that consist of five WN and five WC stars.The optical observation was conducted using a low-resolution spectrograph NEO-R1000(λ/Δλ~1000)at GAO-ITB RTS(2...We present optical spectra of 10 Galactic Wolf-Rayet(WR)stars that consist of five WN and five WC stars.The optical observation was conducted using a low-resolution spectrograph NEO-R1000(λ/Δλ~1000)at GAO-ITB RTS(27.94 cm,F/10.0),Bosscha Observatory,Lembang.We implemented stellar atmosphere Postdam Wolf-Rayet(PoWR)grid modeling to derive stellar parameters.The normalized optical spectrum can be used to find the best model from the available PoWR grid,then we could derive stellar temperature and transformation radius.To derive luminosity,stellar radius and color excess,we conducted a Spectral Energy Distribution(SED)analysis with additional data on the near-ultraviolet spectrum from the International Ultraviolet Explorer(IUE)database,and UBV and 2MASS JHK broadband filter data.Additional analysis to derive asymptotic terminal wind velocity was conducted from the P-Cygni profile analysis of the high-resolution IUE ultraviolet spectrum.With previously derived parameters,we could determine the mass loss rate of the WR stars.Furthermore,we compared our results with previous work that used PoWR code and the differences are not more than 20%.We conclude that the PoWR spectral grid is sufficient to derive WR stellar parameters quickly and could provide more accurate initial parameter input to the PoWR program code.展开更多
为探究锰渣对活性粉末混凝土(Reactive Power Concrete,RPC)在循环荷载与氯化钠冻融循环耦合作用下抗侵蚀性能的影响,文中研究锰渣掺量为0%~40%时,测试RPC在耦合侵蚀作用下的质量损失、相对动弹性模量、抗弯强度与抗压强度等指标。结果...为探究锰渣对活性粉末混凝土(Reactive Power Concrete,RPC)在循环荷载与氯化钠冻融循环耦合作用下抗侵蚀性能的影响,文中研究锰渣掺量为0%~40%时,测试RPC在耦合侵蚀作用下的质量损失、相对动弹性模量、抗弯强度与抗压强度等指标。结果表明随着锰渣掺量增加,RPC在耦合作用下的质量损失率逐渐降低,相对动弹性模量则相应提高。同时,锰渣的掺入显著延缓了冻融环境中RPC力学性能的衰减。综上所述,锰渣可有效提升RPC在氯化钠冻融与荷载耦合条件下的抗侵蚀性能。研究为锰渣的资源化利用与高耐久性混凝土的制备提供参考。展开更多
【目的】为了有效提升压缩空气储能(compressed air energy storage,CAES)系统的储能特性和系统效率,对各部件的性能及其耦合特性进行了建模分析。【方法】针对CAES系统,应用标准热阻方法考虑换热部件的传递特性,结合储气装置与做功部...【目的】为了有效提升压缩空气储能(compressed air energy storage,CAES)系统的储能特性和系统效率,对各部件的性能及其耦合特性进行了建模分析。【方法】针对CAES系统,应用标准热阻方法考虑换热部件的传递特性,结合储气装置与做功部件模型,构建传热、储气、做功耦合的完整热力学模型及能量、㶲分析模型,评价了压缩和膨胀过程中储(释)能质量流量比对系统性能的影响。揭示储气库最高储气压力与体积之间的关系对系统储能效率及储能密度的影响规律。【结果】随着储(释)能质量流量比的增加,压缩机的总能耗先降低后升高,膨胀机的输出功是先上升后降低,当储(释)能的质量比分别为1.2和1.3时,系统效率达到最高,为53.65%;另外,系统中首级压缩和膨胀机的㶲损最大,油-气换热器和压缩机的㶲损占系统总㶲损的69%。【结论】所建模型和研究结果对CAES运行策略具有一定的指导意义。展开更多
With a one-dimensional stellar evolution model,we find that massive main sequence stars can accrete mass at very high mass accretion rates without expanding much if they lose a significant fraction of this mass from t...With a one-dimensional stellar evolution model,we find that massive main sequence stars can accrete mass at very high mass accretion rates without expanding much if they lose a significant fraction of this mass from their outer layers simultaneously with mass accretion.We assume the accretion process is via an accretion disk that launches powerful jets from its inner zones.These jets remove the outer high-entropy layers of the mass-accreting star.This process operates in a negative feedback cycle,as the jets remove more envelope mass when the star expands.With the one-dimensional model,we mimic the mass removal by jets by alternating mass addition and mass removal phases.For the simulated models of 30M☉and 60M☉,the star does not expand much if we remove more than about half of the added mass in not-too-short episodes.This holds even if we deposit the energy the jets do not carry into the envelope.As the star does not expand much,its gravitational potential well stays deep,and the jets are energetic.These results are relevant to bright transient events of binary systems powered by accretion and the launching of jets,e.g.,intermediate luminosity optical transients,including some luminous red novae,the grazing envelope evolution,and the 1837–1856 Great Eruption of Eta Carinae.展开更多
目的调查分析办公室职员肌肉质量减少发生率及影响因素,构建并验证风险预测模型,为制定干预方案提供参考。方法选取2023年3月至2023年12月在四川大学华西医院健康管理中心体检的事业单位、机关单位办公室职员和退休者286人,采用食物频...目的调查分析办公室职员肌肉质量减少发生率及影响因素,构建并验证风险预测模型,为制定干预方案提供参考。方法选取2023年3月至2023年12月在四川大学华西医院健康管理中心体检的事业单位、机关单位办公室职员和退休者286人,采用食物频率调查问卷、运动情况调查问卷、体格检查、人体成分分析、实验室检查等进行分析。使用R语言(R Studio,版本4.4.1)分析肌肉质量影响因素,建立风险预测模型并进行验证。结果肌肉质量减少发生率26.22%;高血糖、低体质量指数(body mass index,BMI)为肌肉质量减少的危险因素,高血尿素/血肌酐(blood urea nitrogen to serum creatinine,BUN/Cr)、每天实际摄入能量/每日推荐摄入能量比、高新鲜水果、高握力评分、超重是肌肉质量减少的保护因素,并构建模型;验证该模型的ROC曲线下面积为0.83,Youden指数为0.52,最佳风险阈值取14.40%。Hosmer-Lemeshow检验和校准曲线评估模型拟合度较高(χ^(2)=11.98,P=0.152),预测模型的阈值概率值在0.07~0.93。结论本研究预测模型具有较好的预测效果和拟合程度,利于医技护人员评估发生肌肉质量减少的风险,有助于为办公室职员肌肉质量减少高危人群提供参考尽早预防。展开更多
基金supported through HLM’s Program Penelitian Pengabdian Masyarakat ITB(P2MI)Astronomy Division,FMIPA ITB grant 2022-2023Support for MAST for non-HST data is provided by the NASA Office of Space Science via grant NNX13AC07G and by other grants and contracts。
文摘We present optical spectra of 10 Galactic Wolf-Rayet(WR)stars that consist of five WN and five WC stars.The optical observation was conducted using a low-resolution spectrograph NEO-R1000(λ/Δλ~1000)at GAO-ITB RTS(27.94 cm,F/10.0),Bosscha Observatory,Lembang.We implemented stellar atmosphere Postdam Wolf-Rayet(PoWR)grid modeling to derive stellar parameters.The normalized optical spectrum can be used to find the best model from the available PoWR grid,then we could derive stellar temperature and transformation radius.To derive luminosity,stellar radius and color excess,we conducted a Spectral Energy Distribution(SED)analysis with additional data on the near-ultraviolet spectrum from the International Ultraviolet Explorer(IUE)database,and UBV and 2MASS JHK broadband filter data.Additional analysis to derive asymptotic terminal wind velocity was conducted from the P-Cygni profile analysis of the high-resolution IUE ultraviolet spectrum.With previously derived parameters,we could determine the mass loss rate of the WR stars.Furthermore,we compared our results with previous work that used PoWR code and the differences are not more than 20%.We conclude that the PoWR spectral grid is sufficient to derive WR stellar parameters quickly and could provide more accurate initial parameter input to the PoWR program code.
文摘为探究锰渣对活性粉末混凝土(Reactive Power Concrete,RPC)在循环荷载与氯化钠冻融循环耦合作用下抗侵蚀性能的影响,文中研究锰渣掺量为0%~40%时,测试RPC在耦合侵蚀作用下的质量损失、相对动弹性模量、抗弯强度与抗压强度等指标。结果表明随着锰渣掺量增加,RPC在耦合作用下的质量损失率逐渐降低,相对动弹性模量则相应提高。同时,锰渣的掺入显著延缓了冻融环境中RPC力学性能的衰减。综上所述,锰渣可有效提升RPC在氯化钠冻融与荷载耦合条件下的抗侵蚀性能。研究为锰渣的资源化利用与高耐久性混凝土的制备提供参考。
文摘【目的】为了有效提升压缩空气储能(compressed air energy storage,CAES)系统的储能特性和系统效率,对各部件的性能及其耦合特性进行了建模分析。【方法】针对CAES系统,应用标准热阻方法考虑换热部件的传递特性,结合储气装置与做功部件模型,构建传热、储气、做功耦合的完整热力学模型及能量、㶲分析模型,评价了压缩和膨胀过程中储(释)能质量流量比对系统性能的影响。揭示储气库最高储气压力与体积之间的关系对系统储能效率及储能密度的影响规律。【结果】随着储(释)能质量流量比的增加,压缩机的总能耗先降低后升高,膨胀机的输出功是先上升后降低,当储(释)能的质量比分别为1.2和1.3时,系统效率达到最高,为53.65%;另外,系统中首级压缩和膨胀机的㶲损最大,油-气换热器和压缩机的㶲损占系统总㶲损的69%。【结论】所建模型和研究结果对CAES运行策略具有一定的指导意义。
文摘目的基于“脑-肠-骨轴”初步探讨左归丸对老年性骨质疏松症(senile osteoporosis,SOP)模型小鼠海马区神经元退行性病变、肠道菌群变化及骨量丢失的作用。方法连续12周腹腔注射D-半乳糖(120 mg/kg)构建SOP模型,将小鼠随机分为空白组、模型组、左归丸高剂量组、左归丸低剂量组;予以左归丸药物干预8周,随后进行Morris水迷宫实验检测小鼠认知功能。取材后检测各组脑组织氧化应激指标,尼氏染色法检测海马尼式神经元完整性,16 S rRNA检测肠道菌群多样性,小动物X光机检测小鼠骨量丢失情况,小鼠血清检测骨代谢指标,免疫组织化学法检测骨代谢通路相关蛋白,采用spearman分析法对血清骨代谢因子、脑组织氧化应激因子与肠道菌群中的差异菌群进行关联分析。结果与Model组相比,左归丸给药组可显著缩短逃避潜伏期时间(P<0.05);显著增加海马区尼式小体数量(P<0.01);提高脑组织抗氧化酶含量(P<0.05);在门水平上,Model组小鼠肠道菌群中Bacteroidota相对丰度显著增高(P<0.01),左归丸给药组Verrucomicrobiota等菌群相对丰度显著升高(P<0.05),Bacteroidota相对丰度显著下降(P<0.05)。小鼠股骨干骺端与骨干区的骨量丢失得到改善,显著改善血清骨代谢指标(P<0.01),显著提高OPG/RANKL蛋白含量比值(P<0.01)。相关性分析显示,过氧化氢酶与肠道菌群中的Proteobacteria呈正相关(P<0.01),与Prevotellaceae_NK3B31_group呈负相关(P<0.01)。结论左归丸依据“脑-肠-骨轴”改善SOP小鼠肠道菌群丰度,进而缓解海马神经元退行性病变,调节OPG/RANK/RANKL通路缓解骨量丢失。
基金A grant from the Pazy Foundation supported this research.
文摘With a one-dimensional stellar evolution model,we find that massive main sequence stars can accrete mass at very high mass accretion rates without expanding much if they lose a significant fraction of this mass from their outer layers simultaneously with mass accretion.We assume the accretion process is via an accretion disk that launches powerful jets from its inner zones.These jets remove the outer high-entropy layers of the mass-accreting star.This process operates in a negative feedback cycle,as the jets remove more envelope mass when the star expands.With the one-dimensional model,we mimic the mass removal by jets by alternating mass addition and mass removal phases.For the simulated models of 30M☉and 60M☉,the star does not expand much if we remove more than about half of the added mass in not-too-short episodes.This holds even if we deposit the energy the jets do not carry into the envelope.As the star does not expand much,its gravitational potential well stays deep,and the jets are energetic.These results are relevant to bright transient events of binary systems powered by accretion and the launching of jets,e.g.,intermediate luminosity optical transients,including some luminous red novae,the grazing envelope evolution,and the 1837–1856 Great Eruption of Eta Carinae.
文摘目的调查分析办公室职员肌肉质量减少发生率及影响因素,构建并验证风险预测模型,为制定干预方案提供参考。方法选取2023年3月至2023年12月在四川大学华西医院健康管理中心体检的事业单位、机关单位办公室职员和退休者286人,采用食物频率调查问卷、运动情况调查问卷、体格检查、人体成分分析、实验室检查等进行分析。使用R语言(R Studio,版本4.4.1)分析肌肉质量影响因素,建立风险预测模型并进行验证。结果肌肉质量减少发生率26.22%;高血糖、低体质量指数(body mass index,BMI)为肌肉质量减少的危险因素,高血尿素/血肌酐(blood urea nitrogen to serum creatinine,BUN/Cr)、每天实际摄入能量/每日推荐摄入能量比、高新鲜水果、高握力评分、超重是肌肉质量减少的保护因素,并构建模型;验证该模型的ROC曲线下面积为0.83,Youden指数为0.52,最佳风险阈值取14.40%。Hosmer-Lemeshow检验和校准曲线评估模型拟合度较高(χ^(2)=11.98,P=0.152),预测模型的阈值概率值在0.07~0.93。结论本研究预测模型具有较好的预测效果和拟合程度,利于医技护人员评估发生肌肉质量减少的风险,有助于为办公室职员肌肉质量减少高危人群提供参考尽早预防。
