Quantitative study of peripapillary retinal nerve fiber layer thickness and peripapillary vessel density in patients with different stages of Parkinson's disease

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.

Quantifying peripapillary vessel density and retinal nerve fibre layer in type 1 diabetic children without clinically detectable retinopathy using OCTA

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.

High Brightness,High Power Density Fiber Coupling of High Power Laser Diode

The output radiation from the 100μm×1μm aperture of a high power Laser Diode (LD) is efficiently coupled into a 50μm multimode optical fiber.The fiber output of the high power LD with high brightness and high power density is achieved.The power density is up to 3 6×104W/cm2 and the coupling efficiency is 70%.The extreme divergence and the astigmatism of high power LDs require the optics with complex lens structures and high performance.A double-curved lens with two crossed cylindrical lenses structured on both sides of the glass substrate is used in the coupling system.

Peripapillary vessel density and retinal nerve fiber layer thickness changes in early diabetes retinopathy

·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.

Electron density measurement of laser-induced epoxy fiber reinforced polymer plasma

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.

Changes of peripapillary vascular density and its correlation with nerve fiber layer thickness in patients with unilateral retinal vein occlusion

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.

Structural measurements and vessel density of spectraldomain optic coherence tomography in early,moderate,and severe primary angle-closure glaucoma

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.

Responses of radial growth, wood density and fiber traits to planting space in poplar plantations at a lowland site

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.

Monte Carlo Computer Simulation of Nonuniform Field Emission Current Density for a Carbon Fiber

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.

Characterization and Comparison of Rheological Properties of Agro Fiber Filled High-Density Polyethylene Bio-Composites

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.

Low Density Linear Polyethylene Reinforced with Alkali and MAPE Treated Fibers from Coffee Pulp

In this work fibers derived from coffee, hulls have been incorporated into Linear Low Density Polyethylene (LLDPE). The influence of the filler content on the 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 fiber-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.

Improving Fiber Quality Output by Improving the Roll Box of the Gin Saw

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.

化学纤维烟密度试验标准方法

火灾中纤维材料燃烧所释放的有毒烟雾是引发人员伤亡的重要原因之一。然而,目前常用的评价方法并未涵盖烟雾密度的测定。针对这一问题,对24种化学纤维进行烟密度测试,并验证了测试方法的适用性,开发了一种准确评定纤维材料燃烧性能的测试方法,为建立适用于纤维材料的烟雾密度测试标准提供了参考。

LLDPE/碳纤维网复合膜的制备及性能

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。

高密度聚乙烯三维网状纳微米纤维的强伸性能

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。

竹纤维增强金尾矿砂加气混凝土性能研究

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。

基于堆积密实度的固废活性粉末混凝土配合比设计方法

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。

长玻纤/高密度聚乙烯复合材料的制备

以N406作为偶联剂,向双螺杆挤出机中连续加入玻璃纤维(玻纤GF),再经剪切、混合工艺,共混制备了长玻纤增强高密度聚乙烯(HDPE)复合材料。采用万能拉伸测试仪、冲击强度测试仪和熔体流动速率(MFR)测试仪,测试了复合材料的力学性能和流动性能;采用差式扫描量热仪(DSC)表征了复合材料的结晶温度、熔融温度;用热失重分析仪(TG)测量了复合材料的玻纤含量。研究结果表明,N406的用量对HDPE的拉伸强度的影响不大,但对冲击强度和MFR的影响较明显。偶联剂用量为8%时,相较未用偶联剂的长玻纤,增强HDPE复合材料的冲击强度提高了64.34%,MFR降低了40.07%。随着玻纤含量增加,拉伸强度、冲击强度升高,MFR降低;HDPE的结晶温度降低,熔融温度增加。玻纤含量为31.26%的复合材料,拉伸强度达到62.88MPa,较纯HDPE提高了180.97%。

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

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。

浆纤维对模塑墙体装饰材料物理性能的影响

通过设计并实施一系列试验,评估不同掺量(0%、5%、10%)的浆纤维对模塑材料密度、抗压强度和吸水率的影响。研究发现,随着浆纤维掺量的增加,模塑材料的密度显著下降,从1.798g/cm^(3)下降到1.708g/cm^(3);抗压强度显著提升,从50.04MPa增加到54.72MPa;吸水率显著增加,从1.22%上升到1.78%。因此,浆纤维的掺入对模塑材料的物理性能具有重要影响,可以在材料应用中根据具体需求进行相应调整。