背景随着人口老龄化的加剧,心力衰竭(heart failure,HF)患病率呈上升趋势,老年心力衰竭的预警、风险分层研究对改善预后具有重要意义。目的探讨血尿素氮-白蛋白比值(blood urea nitrogen to albumin ratio,BAR)对老年心力衰竭患者1年内...背景随着人口老龄化的加剧,心力衰竭(heart failure,HF)患病率呈上升趋势,老年心力衰竭的预警、风险分层研究对改善预后具有重要意义。目的探讨血尿素氮-白蛋白比值(blood urea nitrogen to albumin ratio,BAR)对老年心力衰竭患者1年内死亡的预测价值;建立包含BAR在内的列线图,并验证其临床价值。方法建模数据来自解放军总医院2016年1月—2021年10月诊断为心力衰竭的1259例老年患者,验证队列来自2021年10月—2022年10月诊断为心力衰竭的314例老年患者。以1年病死率为结局指标,采用Logistic回归分析筛选预后因素,根据预后因素构建列线图;ROC曲线、校准曲线和临床决策曲线分析(decision curve analysis,DCA)用于评估模型的区分度、一致性和临床效益;通过计算ROC曲线下面积和DCA,比较列线图与N端脑钠肽前体(N-terminal pro-B-type natriureticpeptide,NT-proBNP)及BIOSTATCHF预测模型的性能。结果训练队列和验证队列中分别有27.2%(343/1259)和25.2%(79/314)患者在1年内死亡。多因素Logistic回归结果显示,年龄、D-二聚体、NT-proBNP、BAR、血管紧张素转化酶抑制剂(angiotensin converting enzyme inhibitor,ACEI)/血管紧张素受体阻滞剂(angiotensin receptor blockers,ARB)使用与死亡结局独立关联(P<0.05)。基于以上5个因素构建列线图,列线图展现出良好的区分度(AUC=0.838,P<0.001)、一致性(Hosmer-Lemeshowχ2=4.251,P=0.834)和临床效益。列线图模型与NT-proBNP和欧洲BIOSTAT-CHF预测模型相比预测效能均更佳(0.838 vs 0.703和0.825,P<0.05)。DCA结果提示,列线图相比NT-proBNP、BIOSTAT-CHF预测模型均增加了更多的净获益。结论BAR是老年心力衰竭患者1年内死亡的独立预测因子。包含BAR在内的列线图展现出优异的辨别力和校准能力,为预后评估提供有力支持。展开更多
Graphitized carbon foams(GFms)were prepared using mesophase pitch(MP)as a raw material by foaming(450℃),pre-oxidation(320℃),carbonization(1000℃)and graphitization(2800℃).The differences in structure and properties...Graphitized carbon foams(GFms)were prepared using mesophase pitch(MP)as a raw material by foaming(450℃),pre-oxidation(320℃),carbonization(1000℃)and graphitization(2800℃).The differences in structure and properties of GFms prepared from different MP precursors pretreated by ball milling or liquid phase extraction were investigated and compared,and semi-quantitative calculations were conducted on the Raman and FTIR spectra of samples at each preparation stage.Semi-quantitat-ive spectroscopic analysis provided detailed information on the structure and chemical composition changes of the MP and GFm de-rived from it.Combined with microscopic observations,the change from precursor to GFm was analyzed.The results showed that ball milling concentrated the distribution of aromatic molecules in the pitch,which contributed to uniform foaming to give a GFm with a uniform pore distribution and good properties.Liquid phase extraction helped remove light components while retaining large aromatics to form graphitic planes with the largest average size during post-treatment to produce a GFm with the highest degree of graphitization and the fewest open pores,giving the best compression resistance(2.47 MPa),the highest thermal conductivity(64.47 W/(m·K))and the lowest electrical resistance(13.02μΩ·m).Characterization combining semi-quantitative spectroscopic ana-lysis with microscopic observations allowed us to control the preparation of the MP-derived GFms.展开更多
The Hexi Inland River Basin in an arid region of northwestern China was chosen as the study area for this research. The authors define the vulnerability of an oasis social-ecological system to glacier change; select 1...The Hexi Inland River Basin in an arid region of northwestern China was chosen as the study area for this research. The authors define the vulnerability of an oasis social-ecological system to glacier change; select 16 indicators from natural and socioeconomic systems according to exposure, sensitivity, and adaptive capacity; and construct a vulnerability-assessment indicator system aimed at an inland river basin in the arid region of Northwestern China. Vulnerability of the oasis socialecological system affected by glacier change in the study area is evaluated by Spatial Principal Component Analysis(SPCA) under the circumstance of glacier change. The key factors affecting the vulnerability are analyzed. The vulnerability of the oasis social-ecological system in the Hexi Inland River Basin affected by glacier change is of more than medium grade, accounting for about 48.0% of the total number of counties in the study area. In terms of the spatial pattern of the vulnerability, the oasis economic belt is the most vulnerable. With the rapid development of the area's society and economy, the exposure of the system to glacial changes is significantly increased; and an increase in glacial meltwater is not enough to overcome the impact of increased exposure, which is the main reason for the high vulnerability. Based on the result of the vulnerability analysis and combined with the present industrial structure in the Hexi Inland River Basin, near-,medium-, and long-term adaptation initiatives are put forward in the article.展开更多
文摘Graphitized carbon foams(GFms)were prepared using mesophase pitch(MP)as a raw material by foaming(450℃),pre-oxidation(320℃),carbonization(1000℃)and graphitization(2800℃).The differences in structure and properties of GFms prepared from different MP precursors pretreated by ball milling or liquid phase extraction were investigated and compared,and semi-quantitative calculations were conducted on the Raman and FTIR spectra of samples at each preparation stage.Semi-quantitat-ive spectroscopic analysis provided detailed information on the structure and chemical composition changes of the MP and GFm de-rived from it.Combined with microscopic observations,the change from precursor to GFm was analyzed.The results showed that ball milling concentrated the distribution of aromatic molecules in the pitch,which contributed to uniform foaming to give a GFm with a uniform pore distribution and good properties.Liquid phase extraction helped remove light components while retaining large aromatics to form graphitic planes with the largest average size during post-treatment to produce a GFm with the highest degree of graphitization and the fewest open pores,giving the best compression resistance(2.47 MPa),the highest thermal conductivity(64.47 W/(m·K))and the lowest electrical resistance(13.02μΩ·m).Characterization combining semi-quantitative spectroscopic ana-lysis with microscopic observations allowed us to control the preparation of the MP-derived GFms.
基金supported by the Global Change Research Program of China (2013CBA01808)the China National Natural Science Foundation (41271088)
文摘The Hexi Inland River Basin in an arid region of northwestern China was chosen as the study area for this research. The authors define the vulnerability of an oasis social-ecological system to glacier change; select 16 indicators from natural and socioeconomic systems according to exposure, sensitivity, and adaptive capacity; and construct a vulnerability-assessment indicator system aimed at an inland river basin in the arid region of Northwestern China. Vulnerability of the oasis socialecological system affected by glacier change in the study area is evaluated by Spatial Principal Component Analysis(SPCA) under the circumstance of glacier change. The key factors affecting the vulnerability are analyzed. The vulnerability of the oasis social-ecological system in the Hexi Inland River Basin affected by glacier change is of more than medium grade, accounting for about 48.0% of the total number of counties in the study area. In terms of the spatial pattern of the vulnerability, the oasis economic belt is the most vulnerable. With the rapid development of the area's society and economy, the exposure of the system to glacial changes is significantly increased; and an increase in glacial meltwater is not enough to overcome the impact of increased exposure, which is the main reason for the high vulnerability. Based on the result of the vulnerability analysis and combined with the present industrial structure in the Hexi Inland River Basin, near-,medium-, and long-term adaptation initiatives are put forward in the article.
