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Quantitative study of peripapillary retinal nerve fiber layer thickness and peripapillary vessel density in patients with different stages of Parkinson's disease 被引量:1
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作者 Ting-Yu Yang Tian-Qi Zhang +5 位作者 Lai-Qing Xie Ying Zhang Shi-Mei Liu Xin-Wei Zeng Wei-Feng Luo Guo-Xu Xu 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2023年第5期762-769,共8页
AIM: To observe the changes in the thickness of peripapillary retinal nerve fiber layer(p RNFL) and peripapillary vessel density(pVD) in patients with different stages of Parkinson's disease(PD).METHODS: Totally 4... AIM: To observe the changes in the thickness of peripapillary retinal nerve fiber layer(p RNFL) and peripapillary vessel density(pVD) in patients with different stages of Parkinson's disease(PD).METHODS: Totally 47 patients(47 eyes) with primary PD were divided into the mild group and the moderateto-severe group according to Hoehn & Yahr(H&Y) stage. Among them, there were 27 cases(27 eyes) in mild group and 20 cases(20 eyes) in moderate-to-severe group. And 20 cases(20 eyes) who were included in the control group were healthy people who came to our hospital for health screening at the same time. All participants underwent optical coherence tomography angiography(OCTA) examinations. The pRNFL thickness, total vessel density(tVD) and capillary vessel density(cVD) of the optic disc in average, superior half, inferior half, superior nasal(SN), nasal superior(NS), nasal inferior(NI), inferior nasal(IN), inferior temporal(IT), temporal inferior(TI), temporal superior(TS), and superior temporal(ST) were measured. One-way ANOVA was used to compare the differences of optic disc parameters among the three groups, and Pearson and Spearman correlations were used to analyze the correlation between pRNFL, pVD and the disease duration, H&Y stage and UPDRS-Ⅲ score in patients with PD, respectively.RESULTS: There were significant differences in p RNFL thickness in average, superior half, inferior half, SN, NS, IN, IT and ST quadrants among the three groups(P<0.05). In PD group, the pRNFL thickness in average, superior half, inferior half, NS and IT quadrants were negatively correlated with H&Y stage and UPDRS-Ⅲ score, respectively(P<0.05). There were statistically significant differences in the cVD of whole image, inferior half, NI and TS quadrants, the tVD of the whole image, inferior half, and peripapillary among the three groups(P<0.05). In PD group, the tVD of whole image and the c VD of NI and TS quadrants were negatively correlated with the H&Y stage, respectively(P<0.05);the cVD of TS quadrant was negatively correlated with UPDRS-Ⅲ score(P<0.05).CONCLUSION: The thickness of pRNFL in PD patients is significantly decreased, and it is negatively correlated with H&Y stage and UPDRS-Ⅲ score. With the increase of the severity of the disease, the pVD parameters in PD patients increase at first in the mild group, and then decrease in the moderate-to-severe group, and negatively correlate with H&Y stage and UPDRS-Ⅲ score. 展开更多
关键词 Parkinson's disease optic disc nerve fiber vascular density
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Quantifying peripapillary vessel density and retinal nerve fibre layer in type 1 diabetic children without clinically detectable retinopathy using OCTA
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作者 Ling Chen Yun Feng +2 位作者 Sha-Sha Zhang Yan-Fang Liu Ping Lin 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2024年第2期278-281,共4页
AIM:To quantify changes in radial peripapillary capillary vessel density(ppVD)and the peripapillary retinal nerve fiber layer(pRNFL)in children with type 1 diabetes without clinical diabetic retinopathy by optical coh... AIM:To quantify changes in radial peripapillary capillary vessel density(ppVD)and the peripapillary retinal nerve fiber layer(pRNFL)in children with type 1 diabetes without clinical diabetic retinopathy by optical coherence tomography angiography(OCTA),providing a basis for early retinopathy in children with type 1 diabetes.METHODS:This was a retrospective study.A total of 30 patients(3–14y)with type 1 diabetes without clinical diabetic retinopathy(NDR group)were included.A total of 30 age-matched healthy subjects were included as the normal control group(CON group).The HbA1c level in the last 3mo was measured once in the NDR group.The pRNFL thickness and ppVD were automatically measured,and the mean pRNFL and ppVD were calculated in the nasal,inferior,temporal,and superior quadrants.The changes in ppVD and pRNFL in the two groups were analyzed.RESULTS:Compared with CON group,the nasal and superior ppVDs decreased in the NDR group(all P<0.01).The thickness of the nasal pRNFL decreased significantly(P<0.01),while the inferior,temporal and superior pRNFLs slightly decreased but not significant in the NDR group(all P>0.05).Person and Spearman correlation analysis of ppVD and pRNFL thickness in each quadrant of the NDR group showed a positive correlation between nasal and superior(all P<0.01),while inferior and temporal had no significant correlation(all P>0.05).There was no significant correlation between the HbA1c level and ppVD and pRNFL in any quadrant(all P>0.05).There was no significant correlation between the course of diabetes mellitus and ppVD and pRNFL in any quadrant(all P>0.05).CONCLUSION:ppVD and pRNFL decrease in eyes of children with type 1 diabetes before clinically detectable retinopathy and OCTA is helpful for early monitoring. 展开更多
关键词 diabetic retinopathy CHILDREN peripapillary vessel density peripapillary retinal nerve fiber layer optical coherence tomography angiography
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Electron density measurement of laser-induced epoxy fiber reinforced polymer plasma 被引量:1
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《强激光与粒子束》 EI CAS CSCD 北大核心 2016年第7期54-59,共6页
Interferograms of laser-induced epoxy fiber reinforced polymer plasmas are obtained through aMach-Zehnder interferometry system. An improved digital double-exposure Fourier method is applied to extractinitial wrapped ... Interferograms of laser-induced epoxy fiber reinforced polymer plasmas are obtained through aMach-Zehnder interferometry system. An improved digital double-exposure Fourier method is applied to extractinitial wrapped phases from interferograms, and then an improved phase unwrapping algorithm based on a maskand a branch-cut method is proposed to solve the problem of phase unwrapping. After the inverse Abel transfor-mation of the unwrapped phase, spatial distributions of the electron density of laser-induced epoxy fiber rein-forced polymer plasma at various delays are acquired. Results show that the measured electron density of theplasma is mainly distributed on the order of 10^18 cm^3. The experiment also indicates that the total amount oflaser plasma electrons changes slightly within the recorded time and the change of the electron density is approx-imately inversely proportional to the change of the plasma volume. 展开更多
关键词 ELECTRON density laser induced PLASMA EPOXY fiber REINFORCED POLYMER phase of inter-ferogram
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Peripapillary vessel density and retinal nerve fiber layer thickness changes in early diabetes retinopathy 被引量:1
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作者 Xiang-Ning Wang Xuan Cai +2 位作者 Ting-Ting Li Da Long Qiang Wu 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2022年第9期1488-1495,共8页
·AIM:To perform a quantitative analysis of the peripapillary vessel density(VD)and retinal nerve fiber layer(RNFL)thickness changes in patients with early stage of diabetic retinopathy(DR).·METHODS:In this c... ·AIM:To perform a quantitative analysis of the peripapillary vessel density(VD)and retinal nerve fiber layer(RNFL)thickness changes in patients with early stage of diabetic retinopathy(DR).·METHODS:In this case-control study,swept-source optical coherence tomography angiography(SS-OCTA)imaging was used to examine diabetic and age-matched healthy subjects.The optic disc HD 6×6 mm^(2) blood flow imaging scan mode was selected.Automatic software was used to measure the peripapillary VD,capillary vessel density(CVD),and RNLF in an optic nerve head(ONH)filed based on the Garway-Heath map.In addition,the correlation between peripapillary VD,CVD,and RNFL was further investigated.·RESULTS:The cohort consisted of 32 healthy individuals and 72 patients with diabetes(34 eyes with no DR and 38 eyes with mild-moderate NPDR).Peripapillary VD decreased in the mild-moderate NPDR group compared to the control group in most regions(P<0.05).Peripapillary CVD and RNFL thickness were significantly lower in the mild-moderate NPDR group in the superior temporal(ST)quadrants(P=0.018.P=0.030).In the correlation analysis of each region,the RNFL thickness in the NS region was positively correlated with the peripapillary VD and CVD(r=0.233,P=0.05;r=0.288.P=0.015).In the TI region,the RNFL thickness was positively correlated with the peripapillary CVD(r=0.237,P=0.047).·CONCLUSION:The measurement based on the ONH topographic map may be helpful in detecting functional and structural impairments in DR.The peripapillary VD,CVD and RNFL decrease in early DR,and the RNFL thickness altered in association with the CVD or/and VD in some regions. 展开更多
关键词 vessel density retinal nerve fiber layer diabetic retinopathy OCTA swept-source
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Changes of peripapillary vascular density and its correlation with nerve fiber layer thickness in patients with unilateral retinal vein occlusion 被引量:1
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作者 Fang Zhao Chao Pei +1 位作者 Jia-Xian Li Hong Zhang 《Journal of Hainan Medical University》 2021年第21期28-32,共5页
Objective:To observe the changes of peripapillary vascular density(VD)and its correlation with retinal nerve fiber layer(RNFL)thickness in patients with unilateral retinal vein occlusion(RVO)by optical coherence tomog... Objective:To observe the changes of peripapillary vascular density(VD)and its correlation with retinal nerve fiber layer(RNFL)thickness in patients with unilateral retinal vein occlusion(RVO)by optical coherence tomography angiography(OCTA).Methods:Prospective case-control study.Thirty-two patients(32 eyes)with RVO diagnosed at the Eye Hospital of China Academy of Chinese Medical Sciences from September 2020 to June 2021 were selected.Another 32 outpatients(32 eyes)with normal ocular examination were selected as the normal control group.Optic disc blood flow imaging was performed in all subjects using the OCTA to measure peripapillary RNFL thickness,peripapillary vessel density,optic disc area,and disc rim area.The correlation between peripapillary vascular density and RNFL,optic disc area and disc rim area in eyes with unilateral RVO was analyzed.Results:Compared with the normal control group,the prevalence of hypertension was higher in the unilateral RVO group,and the difference was statistically significant(P<0.05).Compared with the normal control group,the overall,inferior and temporal RNFL thickness around the optic disc was thinner in patients with unilateral RVO,and the difference was statistically significant(P<005).Compared with the normal control group,the overall VD,internal ring,external ring and inferior VD around the optic disc were slightly decreased in patients with unilateral RVO,and the differences were statistically significant(P<0.05).The results of Pearson correlation analysis indicated that RNFL thickness was positively correlated with peripapillary global VD(r=0.648,P<0.001),RNFL thickness was positively correlated with intrapapillary ring VD(r=0.427,P=0.015),and RNFL thickness was positively correlated with peripapillary VD(r=0.666,P<0.001).Conclusion:The results showed that the RNFL thickness around the optic disc was thinner in patients with unilateral RVO,especially in the inferior and temporal area,and the full area VD around the optic disc was decreased,especially in the internal ring,external ring and inferior area.In patients with unilateral RVO,peripapillary RNFL was positively correlated with peripapillary global,internal ring and external ring VD. 展开更多
关键词 Retinal vein occlusion Parapapapillary vessel density Retinal nerve fiber layer thickness Optical coherence tomography ANGIOGRAPHY
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Structural measurements and vessel density of spectraldomain optic coherence tomography in early,moderate,and severe primary angle-closure glaucoma 被引量:2
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作者 Wei Jiang Nan Jiang +3 位作者 Gui-Bo Liu Jing Lin Cui Li Gui-Qiu Zhao 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2023年第7期1100-1109,共10页
AIM:To compare the macular ganglion cell-inner plexiform layer(GCIPL)thickness,retinal nerve fiber layer(RNFL)thickness,optic nerve head(ONH)parameters,and retinal vessel density(VD)measured by spectral-domain optical... AIM:To compare the macular ganglion cell-inner plexiform layer(GCIPL)thickness,retinal nerve fiber layer(RNFL)thickness,optic nerve head(ONH)parameters,and retinal vessel density(VD)measured by spectral-domain optical coherence tomography(SD-OCT)and analyze the correlations between them in the early,moderate,severe primary angle-closure glaucoma(PACG)and normal eyes.METHODS:Totally 70 PACG eyes and 20 normal eyes were recruited for this retrospective analysis.PACG eyes were further separated into early,moderate,or severe PACG eyes using the Enhanced Glaucoma Staging System(GSS2).The GCIPL thickness,RNFL thickness,ONH parameters,and retinal VD were measured by SD-OCT,differences among the groups and correlations within the same group were calculated.RESULTS:The inferior and superotemporal sectors of the GCIPL thickness,rim area of ONH,average and inferior sector of the retinal VD were significantly reduced(all P<0.05)in the early PACG eyes compared to the normal and the optic disc area,cup to disc ratio(C/D),and cup volume were significantly higher(all P<0.05);but the RNFL was not significant changes in early and moderate PACG.In severe group,the GCIPL and RNFL thickness were obvious thinning with retinal VD were decreasing as well as C/D and cup volume increasing than other three groups(all P<0.01).In the early PACG subgroup,there were significant positive correlations between retinal VD and GCIPL thickness(except superonasal and inferonasal sectors,r=0.573 to 0.641,all P<0.05),superior sectors of RNFL thickness(r=0.055,P=0.049).More obvious significant positive correlations were existed in moderate PACG eyes between retinal VD and superior sectors of RNFL thickness(r=0.650,P=0.022),and temporal sectors of RNFL thickness(r=0.740,P=0.006).In the severe PACG eyes,neither GCIPL nor RNFL thickness was associated with retinal VD.CONCLUSION:The ONH damage and retinal VD loss appears earlier than RNFL thickness loss in PACG eyes.As the PACG disease progressed from the early to the moderate stage,the correlations between the retinal VD and RNFL thickness increases. 展开更多
关键词 optic coherence tomography primary angle-closure glaucoma ganglion cell-inner plexiform layer retinal nerve fiber layer optic nerve head retinal vessel density
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Responses of radial growth, wood density and fiber traits to planting space in poplar plantations at a lowland site
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作者 Yanhua Zhang Shengzuo Fang +2 位作者 Ye Tian Linlin Wang Yi Lv 《Journal of Forestry Research》 SCIE CAS CSCD 2022年第3期963-976,共14页
Poplar is raw material for various panel, paper and fiber products. The 12 sample trees of clone Nanlin-895 from four spacings were destructively harvested after thirteen growing seasons to assess the influence of spa... Poplar is raw material for various panel, paper and fiber products. The 12 sample trees of clone Nanlin-895 from four spacings were destructively harvested after thirteen growing seasons to assess the influence of spacing on radial growth and wood properties. Spacing significantly affected tree-ring width and wood basic density (p < 0.05) but not fiber traits. The highest diameter and wood basic density at breast height (1.3 m) was in 6 m × 6 m and 3 m × 8 m spacings, respectively. However, no significant differences in tree-ring width, wood basic density and fiber traits were observed among the four sampling directions in discs taken at 1.3 m for each spacing. Growth rings from the pith and tree heights had significant effects on wood basic density and fiber anatomical characteristics, highlighting obvious temporal-spatial variations. Pearson correlation analysis showed a significantly negative relationship of tree-ring width to wood basic density, fiber length and fiber width, but a significantly positive relationship to hemicellulose. There was no relationship with cellulose and lignin contents. Based on a comprehensive assessment by the TOPSIS method, the 6 m × 6 m spacing is recommended for producing wood fiber at similar sites in the future. 展开更多
关键词 Planting density Growth ring fiber morphology Chemical composition Temporal-spatial variation
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Monte Carlo Computer Simulation of Nonuniform Field Emission Current Density for a Carbon Fiber
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作者 P. A. Golovinski A. A. Drobyshev 《Journal of Electromagnetic Analysis and Applications》 2014年第1期8-14,共7页
The field emission current from a carbon fiber is considered. As a model of emission of an elementary carbon tube, tunnel ionization of an electron from a short-range potential is taken. The exact solution for the wav... The field emission current from a carbon fiber is considered. As a model of emission of an elementary carbon tube, tunnel ionization of an electron from a short-range potential is taken. The exact solution for the wave function in such a model allows obtaining an asymptotic expression for electron current. A computer model of transverse distribution of emission current of a carbon fiber is built on the basis of the Monte Carlo method that allows taking into account the random character of distribution of local emitter sources and the distribution of gains of an electric field in carbon nanotubes. 展开更多
关键词 Field Emission Carbon fiber Current density SHORT-RANGE Potential MONTE Carlo Method
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Characterization and Comparison of Rheological Properties of Agro Fiber Filled High-Density Polyethylene Bio-Composites 被引量:1
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作者 Anselm O. Ogah Joseph N. Afiukwa A. A. Nduji 《Open Journal of Polymer Chemistry》 2014年第1期12-19,共8页
The rheological behavior of composites made with high-density polyethylene (HDPE) and different agro fiber by-products such as corncob (CCF), Rice hull (RHF), Flax shives (FSF) and Walnut shell (WSF) flour of 60 - 100... The rheological behavior of composites made with high-density polyethylene (HDPE) and different agro fiber by-products such as corncob (CCF), Rice hull (RHF), Flax shives (FSF) and Walnut shell (WSF) flour of 60 - 100 mesh were studied. The experimental results were obtained from samples containing 65 vol.% agro fiber and 3 wt.% lubricant. Particle sizes distribution of the agro fibers was in the range of 0.295 mm to ?0.125 mm. SEM showed evidence of complete matrix/fiber impregnation or wetting. The melt rheological data in terms of complex viscosity (η*), storage modulus (G'), loss modulus (G"), and loss tangent (tanδ) were evaluated and compared for different samples. Due to higher probability of agglomeration formation in the samples containing 65 vol.% of agro fillers, the storage modulus, loss modulus and complex viscosity of these samples were high. The unique change in all the samples is due to the particle size distribution of the agro fibers. The storage and loss modulus increased with increasing shear rates for all the composites, except for Walnut shell composite which exhibited unusual decrease in storage modulus with increasing shear rate. Damping factor (tanδ) decreased with increasing shear rate for all the composites at 65 vol.% filler load although there were differences among the composites. Maximum torque tended to increase at the 65 vol.% agro fiber load for all composites. Corncob and Walnut shell composites gave higher torque and steady state torque values in comparison with Flax shives and Rice hull composites due to differences in particle sizes distribution of the agro fibers. 展开更多
关键词 MELT RHEOLOGY Agro fiber BIO-COMPOSITES VISCOELASTICITY HIGH-density Polyethylene
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Low Density Linear Polyethylene Reinforced with Alkali and MAPE Treated Fibers from Coffee Pulp
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作者 Ahmat Tom Abel Tame +2 位作者 Paul Nestor Djomou Djonga Bakary Tigana Djonse Justin Eugenie Géraldine Nga Abena 《Open Journal of Composite Materials》 2021年第4期94-110,共17页
In this work fibers derived from coffee</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> hulls ha</span><span style="font-f... In this work fibers derived from coffee</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> hulls ha</span><span style="font-family:Verdana;">ve</span><span style="font-family:Verdana;"> been incorporated into Linear Low Density Polyethylene (LLDPE). The influence of the filler content on </span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">thermal and physicomechanical properties of the composites obtained was assessed. The results showed that the incorporation of fibers was able to improve the thermostability of LLDPE/Coffee hulls fibers;comparing the treated fiber composite with untreated fiber composites, the chemical treatment reduces by 58.3% the water absorption, while increasing the elongation and tensile strength by about 48% and 17% respectively. Moreover, due to better interfacial interaction induced by MAPE, the corresponding composite exhibited better properties compared to the untreated fiber composite. Results are indicative of the fact that both mercerization and MAPE (coupling agent) have significant positive effects on the fib</span><span style="font-family:Verdana;">er</span><span style="font-family:Verdana;">-matrix interaction in terms of adhesion, wetting and dispersion, this treatment produced a better fiber distribution and consequently a more uniform composite morphology without voids and gaps between the fibers and the matrix, allowing the possibility to use higher fiber contents (up to 30% wt.) with acceptable mechanical properties. 展开更多
关键词 fiber from Coffee fiber Hull Linear Low density Polyethylene Composite MAPE
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Improving Fiber Quality Output by Improving the Roll Box of the Gin Saw
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作者 Sarimsakov Akramjon Isroilov Sardorbek Komilov Shukhratjon 《Engineering(科研)》 CAS 2023年第4期261-268,共8页
It has been proven that the increase in the productivity of the gin machine necessarily occurs along with the increase in the density of the raw material. However, with increasing density, productivity increases up to... It has been proven that the increase in the productivity of the gin machine necessarily occurs along with the increase in the density of the raw material. However, with increasing density, productivity increases up to a certain limit, and then productivity begins to decrease. In this article, the authors analyzed the scientific work on improving the quality of fiber. 展开更多
关键词 COTTON fiber Saw Gin density SAW DRUM Seed Husk SEED Fluff
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LLDPE/碳纤维网复合膜的制备及性能
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作者 石素宇 张学锋 +2 位作者 白雨 王利娜 辛长征 《化工新型材料》 CAS CSCD 北大核心 2024年第3期98-101,108,共5页
为了提高线型低密度聚乙烯(LLDPE)的拉伸强度和模量,将碳纤维(CF)梳理成均匀的碳纤维网,将其作为增强材料与LLDPE复合制备LLDPE/CF复合膜,综合利用热失重分析(TG)、扫描示差量热分析(DSC)、扫描电子显微镜(SEM)及拉伸测试等手段分析碳... 为了提高线型低密度聚乙烯(LLDPE)的拉伸强度和模量,将碳纤维(CF)梳理成均匀的碳纤维网,将其作为增强材料与LLDPE复合制备LLDPE/CF复合膜,综合利用热失重分析(TG)、扫描示差量热分析(DSC)、扫描电子显微镜(SEM)及拉伸测试等手段分析碳纤维网含量对复合膜结构及性能的影响。结果表明:与LLDPE膜相比,LLDPE/CF复合膜的拉伸强度和杨氏模量显著提高并随碳纤维网含量增加而增大,当碳纤维网质量分数仅为1%时,拉伸强度从10.6MPa提高到28.7MPa,提高了171%,杨氏模量由75MPa增大到1119MPa,约提高到原来的15倍;碳纤维网的引入有利于LLDPE/CF复合膜热稳定性能的提高,当碳纤维网含量仅为1%时,LLDPE/CF的初始热分解温度和最大热分解速率温度与LLDPE相比分别提高了21℃和11℃;碳纤维网的引入促进了LLDPE分子链的结晶,使LLDPE/CF复合膜的结晶度增大,有利于拉伸强度和模量提高;SEM结果显示碳纤维网与LLDPE基体间的界面结合较强,有利于力学性能的提高。研究成果可为高性能聚合物/碳纤维复合材料的制备提供实验依据和理论指导价值。 展开更多
关键词 线型低密度聚乙烯 碳纤维网 复合膜 热压成型 高性能
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高密度聚乙烯三维网状纳微米纤维的强伸性能
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作者 西鹏 李永康 +2 位作者 程博闻 夏磊 舒登坤 《天津工业大学学报》 CAS 北大核心 2024年第2期10-15,共6页
为实现高密度聚乙烯三维网状纳微米纤维(PENFs)的自主化规模化生产,以高密度聚乙烯和二氯甲烷为原料,通过高压闪喷纺丝设备成功制备了性能优异的PENFs,采用响应面法对纺丝过程中各工艺参数进行优化,并对其力学性能和耐候性能进行分析。... 为实现高密度聚乙烯三维网状纳微米纤维(PENFs)的自主化规模化生产,以高密度聚乙烯和二氯甲烷为原料,通过高压闪喷纺丝设备成功制备了性能优异的PENFs,采用响应面法对纺丝过程中各工艺参数进行优化,并对其力学性能和耐候性能进行分析。结果表明:PENFs的最佳制备工艺条件为纺丝温度176.3℃、纺丝压力8.6 MPa、纺丝溶液质量分数8.0%,此时制得的PENFs的断裂强度和断裂伸长率分别可达到29.1 cN/dtex和99.9%,优于芳纶和涤纶等常规纤维;定伸长和定载荷条件下,PENFs的弹性回复能力随着拉伸次数和载荷的增加而逐渐降低,拉伸伸长为5%时PENFs纤维的弹性回复率可达到92.8%且拉伸10次后降低至75.5%,拉伸载荷为1.2 N时PENFs纤维的弹性回复率为84.6%;放置在室外20 d内PENFs纤维的强伸性能损失较小,30 d后断裂强度和断裂伸长率明显降低,但纤维外貌并无明显变化。 展开更多
关键词 高密度聚乙烯 纳微米纤维 三维网状结构 力学性能
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竹纤维增强金尾矿砂加气混凝土性能研究
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作者 卜显忠 李致剑 +3 位作者 黄炜 张崇辉 王森 权文立 《新型建筑材料》 2024年第2期98-102,121,共6页
以竹纤维为增强材料制备B06级金尾矿砂加气混凝土,分析了竹纤维掺量和长度对竹纤维砂加气混凝土(BFAAC)料浆流动性、发气高度、干密度和抗压强度等的影响;采用XRD及SEM分析了BFAAC的物相组成和微观结构。结果表明:随着竹纤维掺量的增加,... 以竹纤维为增强材料制备B06级金尾矿砂加气混凝土,分析了竹纤维掺量和长度对竹纤维砂加气混凝土(BFAAC)料浆流动性、发气高度、干密度和抗压强度等的影响;采用XRD及SEM分析了BFAAC的物相组成和微观结构。结果表明:随着竹纤维掺量的增加,BFAAC的料浆流动性、发气高度逐渐下降,试样干密度逐渐增大,抗压和抗折强度先提高后降低,竹纤维的最佳掺量为0.3%。竹纤维长度对BFAAC浆料性能和制品基本物理力学性能影响不明显。XRD和SEM分析表明,BFAAC的水化产物主要是托贝莫来石和少量C-S-H;竹纤维不参与基体材料之间的水化反应,而是通过物理作用达到增强效果。 展开更多
关键词 金尾矿 加气混凝土 竹纤维 干密度 抗压强度 抗折强度 绿色建材
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基于堆积密实度的固废活性粉末混凝土配合比设计方法
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作者 王德弘 卢文启 鞠彦忠 《新型建筑材料》 2024年第2期1-7,共7页
采用固废掺合料(粉煤灰、矿渣和玻璃粉)进行了活性粉末混凝土(RPC)制备及性能研究,研究了固废种类、掺量和掺入方式对RPC堆积密实度、工作性能、力学性能和微观结构的影响,提出了固废RPC强度模型。结果表明:粉煤灰、矿渣和玻璃粉的替代... 采用固废掺合料(粉煤灰、矿渣和玻璃粉)进行了活性粉末混凝土(RPC)制备及性能研究,研究了固废种类、掺量和掺入方式对RPC堆积密实度、工作性能、力学性能和微观结构的影响,提出了固废RPC强度模型。结果表明:粉煤灰、矿渣和玻璃粉的替代水泥量分别为15%、10%~15%和20%时,RPC强度更具有优势,工作性能和微观性能更好;固废合理的掺入可使立方体抗压强度最高提高25.8%,而且随着堆积密实度的增大,固废RPC立方体抗压强度先提高后稍有降低;结合鲍罗米公式和密度堆积模型,考虑影响RPC性能的主要因素,提出了固废掺合料RPC配合比的设计方法,为RPC的工程应用提供依据。 展开更多
关键词 活性粉末混凝土 固废掺合料 堆积密实度 配制强度模型 钢纤维
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冻融循环下秸秆纤维混凝土损伤特性及动态力学性能研究
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作者 孙霄 刘茂野 《混凝土》 CAS 北大核心 2024年第2期114-119,125,共7页
为研究冻融循环对不同纤维掺量的秸秆纤维混凝土动态力学性能的影响,采用非金属超声波检测仪测量不同冻融循环次数下秸秆纤维混凝土试件纵波波速,利用直径74 mm变截面分离式霍普金森压杆试验装置对试件开展动态单轴压缩试验,分析试件纵... 为研究冻融循环对不同纤维掺量的秸秆纤维混凝土动态力学性能的影响,采用非金属超声波检测仪测量不同冻融循环次数下秸秆纤维混凝土试件纵波波速,利用直径74 mm变截面分离式霍普金森压杆试验装置对试件开展动态单轴压缩试验,分析试件纵波波速、峰值应力、劣化度、韧性及破碎耗能密度与冻融循环次数及秸秆纤维掺量间的关系。结果表明:纤维的掺入能够提高混凝土材料的纵波波速及整体性,随着冻融循环次数的增加,秸秆纤维混凝土纵波波速随之降低,冻融循环会对试件造成损伤;秸秆纤维的掺入会增强混凝土材料的力学性能,掺量为0.2%时效果最佳,冻融循环作用试件峰值应力不断降低,劣化度不断增加,相较于冻融循环0次素混凝土试件,冻融循环30、60、90、120次试件峰值应力分别降低6.96%、19.4%、34.2%、53.3%,冻融循环后期应力降幅显著增加,纤维的掺入在一定程度上减缓了冻融作用下试件劣化程度;纤维掺量为0.2%时试件的韧性与破碎耗能密度提升最大,冻融循环会对试件造成劣化,降低其韧性及吸能效果。秸秆纤维的掺入使混凝土材料力学性能大幅增加,秸秆纤维的绿色可再生性对秸秆纤维混凝土的推广具有重大意义。 展开更多
关键词 冻融循环 秸秆纤维 纵波波速 峰值应力 劣化度 韧性 破碎耗能密度
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光子带隙光纤背向散射次波建模及实验验证
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作者 王晓阳 滕飞 +5 位作者 徐小斌 王琪伟 周晓娜 田亚男 马官营 李勇 《光学精密工程》 EI CAS CSCD 北大核心 2024年第6期765-773,共9页
光子带隙光纤有着独特的结构形式、传输介质和导光机制,这使其具有传统光纤无法比拟的优点,是未来光纤陀螺的理想选择。但光子带隙光纤粗糙的纤芯内壁导致其产生强烈的背向散射次波,会使光子带隙光纤陀螺产生额外的非互易误差。为了定... 光子带隙光纤有着独特的结构形式、传输介质和导光机制,这使其具有传统光纤无法比拟的优点,是未来光纤陀螺的理想选择。但光子带隙光纤粗糙的纤芯内壁导致其产生强烈的背向散射次波,会使光子带隙光纤陀螺产生额外的非互易误差。为了定量分析光子带隙光纤背向散射次波强度大小,论文基于电偶极子辐射理论建立了一种简单的光子带隙光纤背向散射次波理论模型。通过聚焦离子束微纳加工法和原子力显微镜测量得到了准确的纤芯内壁表面形貌功率谱密度,进而计算得到HC-1550-02型光子带隙光纤背向散射系数理论值为2.61×10^(-9)/mm。通过光频域背向反射散射仪得到HC-1550-02型光子带隙光纤背向散射系数测量值为~1.82×10^(-9)/mm,初步验证了背向散射次波模型的正确性,为背向散射次波抑制技术研究奠定了基础。 展开更多
关键词 光子带隙光纤 背向散射次波 功率谱密度
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聚丙烯腈纤维径向致密结构的光密度法研究
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作者 邓卓寅 刘宇涛 +3 位作者 赵德明 周铮钰 徐樑华 李常清 《化工新型材料》 CAS CSCD 北大核心 2024年第3期109-112,共4页
凝固过程聚丙烯腈(PAN)初生纤维在径向上各点的双扩散程度不同,可能会造成PAN纤维在径向上致密结构的差异。首先采用光密度法测定PAN初生纤维径向的致密结构及其差异性的可行性和影响因素,在此基础上采用光密度法研究了凝固浴温度对PAN... 凝固过程聚丙烯腈(PAN)初生纤维在径向上各点的双扩散程度不同,可能会造成PAN纤维在径向上致密结构的差异。首先采用光密度法测定PAN初生纤维径向的致密结构及其差异性的可行性和影响因素,在此基础上采用光密度法研究了凝固浴温度对PAN初生纤维致密性结构差异的影响。结果表明:对于PAN初生纤维,采用纤维切片厚度为4μm、调整入射光强使背景灰度为140时进行PAN初生纤维光密度的测定;保持凝固浴浓度恒定不变,凝固浴温度从25℃升高到65℃会导致PAN初生纤维的灰度降低、光密度值增大、纤维径向皮部与芯部的光密度差值增大,这表明随着凝固浴温度的升高,纤维的致密性降低、径向致密结构差异增大。光密度法可以用来定量表征PAN纤维的径向结构及其差异。 展开更多
关键词 聚丙烯腈初生纤维 径向结构 致密结构 光密度 凝固浴温度
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宝天曼8种阔叶树木材密度的解剖学决定因素及其与叶性状的协同与权衡
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作者 杭宇杰 陈志成 +5 位作者 王林 牛保亮 刘松松 于博 王晓 刘世荣 《林业科学》 EI CAS CSCD 北大核心 2024年第4期62-70,共9页
【目的】探究影响木材密度的解剖学机制,揭示茎叶解剖和生理性状的协同与权衡关系,有助于阐明不同树种适应环境的生理生态机制。【方法】选择宝天曼天然林中常见的8种落叶阔叶树,测定木材密度、木质部导管及纤维等解剖性状、叶片压力-... 【目的】探究影响木材密度的解剖学机制,揭示茎叶解剖和生理性状的协同与权衡关系,有助于阐明不同树种适应环境的生理生态机制。【方法】选择宝天曼天然林中常见的8种落叶阔叶树,测定木材密度、木质部导管及纤维等解剖性状、叶片压力-容积曲线参数等21个茎叶性状,探究决定木材密度的解剖学性状,分析茎叶性状的协同和权衡关系。【结果】1) 8个树种的木材密度与组成木质部的导管、薄壁组织和纤维组织这3大组织的比例都不相关,更多受到纤维细胞性状的影响。2)对木材密度影响最大的木质部性状是纤维细胞腔占横截面的比例,其次是纤维细胞壁占纤维细胞的比例、纤维细胞壁厚与腔直径比、纤维细胞壁厚度等性状。3)木材密度与叶片单叶面积、失膨压时相对含水量和弹性模量呈负相关。4)失膨压时相对含水量与导管水力直径、最大导管直径、平均导管直径、纤维细胞腔面积、纤维细胞腔直径呈正相关;与导管密度、纤维细胞壁厚与腔直径比、纤维细胞壁占横截面比例呈负相关。【结论】木材密度主要由纤维细胞性状决定,而非导管和薄壁组织性状;高的叶片忍耐失水能力耦合于致密的茎纤维细胞和木材密度。 展开更多
关键词 木材密度 功能性状 木质部解剖 纤维性状 失膨压时相对含水量
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PEDOT∶PSS/石墨烯复合纤维的制备及其电化学性能研究
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作者 王圣玉 杜苑 +1 位作者 李宏伟 张梅 《北京服装学院学报(自然科学版)》 CAS 2024年第1期65-73,共9页
为了更好地实现石墨烯基纤维在柔性可穿戴储能器件领域的应用,采用改进的Hummers法制备氧化石墨烯水分散液与聚(3,4-亚乙二氧基噻吩)-聚(苯乙烯磺酸)(PEDOT∶PSS)分散液制备一定浓度的复合纺丝液;以氯化钙溶液为凝固浴,通过湿法纺丝技... 为了更好地实现石墨烯基纤维在柔性可穿戴储能器件领域的应用,采用改进的Hummers法制备氧化石墨烯水分散液与聚(3,4-亚乙二氧基噻吩)-聚(苯乙烯磺酸)(PEDOT∶PSS)分散液制备一定浓度的复合纺丝液;以氯化钙溶液为凝固浴,通过湿法纺丝技术制备不同比例的PEDOT∶PSS/氧化石墨烯复合纤维,经氢碘酸还原获得PEDOT∶PSS/石墨烯复合纤维。对PEDOT∶PSS/石墨烯复合纤维的结构形貌进行表征,PEDOT/PSS质量分数为20%时复合纤维的直径约为95μm,表面具有褶皱卷曲的形貌。以PEDOT∶PSS/石墨烯复合纤维组装柔性超级电容器,在不同凝胶电解质体系中进行电化学性能评价。结果表明,PEDOT∶PSS质量分数为20%的PEDOT∶PSS/石墨烯复合纤维在PVA/H_(2)SO_(4)凝胶电解质体系中的电化学性能最佳;当电流密度为0.14 mA/cm^(-2)时,面积比电容为420.7 mF/cm^(2),能量密度为9.35μW h/cm^(2),表现出良好的电化学性能,可为温湿度计供电,并显现出在智能可穿戴储能器件中的潜在应用前景。 展开更多
关键词 PEDOT∶PSS 石墨烯纤维 湿法纺丝 柔性超级电容器 能量密度
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