利用扫描电子显微镜研究聚丙烯腈基碳纤维的形态结构

采用扫描电子显微镜(SEM)研究了聚丙烯腈(PAN)基原丝及其碳纤维的缺陷和表面沟槽等形态结构,并分析了表面处理后碳纤维与树脂基体的结合状态.结果显示:SEM可以直观地观察到PAN原丝及其碳纤维的表面及内部缺陷,这些缺陷主要遗传自原丝;经表面处理后,碳纤维与树脂基体间结合程度和强度显著提高.     

玻璃/水泥中空纤维膜的制备及碳素截留性能

以玻璃粉、水泥粉、聚偏氟乙烯和N,N-二甲基乙酰胺为原料,通过溶液法纺丝技术制备了玻璃/水泥中空纤维前驱体膜。利用前驱体膜对一定浓度的碳素溶液进行截留测试,同时利用扫描电子显微镜、紫外分光光度计分析前驱体膜的微观形貌和碳素截留性能,探究了水泥粉的掺杂对碳素颗粒截留性能的影响。     

血管内皮生长因子反义基因真核表达载体的构建及其对乳腺癌细胞的生长抑制作用

目的构建反义血管内皮生长因子(VEGF165)基因真核表达载体,分析该基因对乳腺癌细胞的生长抑制作用。方法将人VEGF165cDNA反向克隆至pcDNA3真核表达载体中,构建VEGF165反义基因的真核表达载体,转染人乳腺癌细胞MCF-7,观察转染前后MCF-7细胞的VEGF165表达及细胞生长周期。结果所构建的VEGF165反义基因真核表达载体转染MCF-7细胞后,VEGF165表达下降,细胞生存率下降,G1期细胞数量增加,S期细胞数量减少,细胞增殖能力降低。结论成功构建了VEGF165反义基因表达载体,该基因对乳腺癌细胞的生长具有明显的抑制作用。     

Isolation of Multipotent Nestin-Expressing Stem Cells Derived from the Epidermis of Elderly Humans and TAT-VHL Peptide-Mediated Neuronal Differentiation of These Cells

A specialized population of cells residing in the hair follicle is quiescent but shows pluripotency for differentiating into epithelial-mesenchymal lineage cells. Therefore, such cells are hoped to be useful as implantable donor cells for regenerative therapy. Recently, it was reported that intracellular delivery of TAT-VHL peptide induces neuronal differentiation of skin-derived precursors. In the present study, we successfully isolated multipotent stem cells derived from the epidermis of elderly humans, characterized these cells as being capable of sphere formation and strong expression of nestin, fibronectin, and CD34 but not of keratin 15, and identified the niche of these cells as being the outer root sheath of the hair follicles. In addition, we showed that TAT-VHL peptide induced their neuronal differentiation in vitro, and confirmed by fluorescence immunohistochemistry the neuronal differentiation of such peptide-treated cells implanted into rodent brains. These multipotent nestin-expressing stem cells derived from human epidermis are easily accessible and should be useful as donor cells for neuronal regenerative cell therapy.     

碳纳米管增强丁腈橡胶的性能研究

研究了碳纳米管用量对丁腈橡胶硫化特性、力学性能、高温拉伸性能、导热性能、耐磨性能、压缩疲劳性能和动态力学性能的影响,并通过扫描电子显微镜观察碳纳米管在橡胶中的分散情况。结果表明：随着碳纳米管含量的增加,胶料的最小扭矩和最大扭矩逐渐增大,焦烧时间和正硫化时间逐渐减少;拉伸强度和撕裂强度均是先提高后降低,拉断伸长率逐渐降低,100%定伸应力和300%定伸应力显著提高;高温拉伸性能中,性能保持率逐渐提高;导热系数逐渐提高,DIN磨耗体积逐渐降低;静压缩率逐渐降低,永久变形和疲劳温升逐渐增加。在动态力学性能中,加入碳纳米管后,橡胶的损耗因子峰值降低,储能模量在温度较低时较小。由扫描电子显微镜观察拉伸试样断面可知,碳纳米管在橡胶中整体分散均匀,局部存在团聚现象。     

肿瘤侵袭抑制因子-2对基因重组肝细胞生长因子诱导的人肺癌细胞运动和侵袭的抑制作用

应用基因重组肝细胞生长因子（HGF）可诱导人肺癌细胞运动和侵袭，通过细胞离散、集落扩散和基底膜侵袭实验证明，侵袭抑制因子-2（ⅡF-2）可明显地抑制由HGF诱导的作用。该抑制作用可被抗ⅡF-2抗体所阻断，表明ⅡF-2在肿瘤转移的预防和治疗方面可能具有重要意义。     

大鼠骨髓间充质干细胞向肝样细胞的定向诱导分化

目的 探讨肝细胞生长因子(Hepatocyte growth factor,HGF)和碱性成纤维细胞生长因子(Basic fibroblast growthfactor,bFGF)诱导大鼠骨髓间充质干细胞(Bone marrow mesenchymal stem cells,BM-MSCs)分化为肝样细胞的可行性。方法取SD大鼠股骨骨髓,直接贴壁法分离纯化BM-MSCs,并体外传代,流式细胞术和成骨诱导对其进行鉴定。取第3代BM-MSCs,分为2组:实验组用HGF(20 ng/ml)和bFGF(10 ng/ml)进行诱导,阴性对照组不加诱导剂,倒置显微镜下观察细胞形态变化;RT-PCR法检测诱导后细胞甲胎蛋白(Alpha fetoprotein,AFP)和白蛋白(Albumin,ALB)基因mRNA的转录水平;免疫细胞化学染色法检测诱导后细胞的AFP和ALB蛋白的表达。结果第3代BM-MSCs表型标志和功能特性均符合MSCs的特点。BM-MSCs经HGF和bFGF诱导后呈肝样细胞形态。实验组细胞可检测出AFP和ALB基因mRNA的表达。实验组细胞诱导后第7天,AFP蛋白开始表达,第14天时表达降低,第21天时不表达;ALB于诱导后第14天出现表达,并随诱导时间的延长表达逐渐增加。结论 HGF和bFGF具有体外诱导BM-MSCs向肝样细胞分化的作用。     

碳纤维复合材料层合板面内压缩损伤及声发射特征分析

针对碳纤维复合材料层合板面内压缩损伤问题,基于声发射技术分析不同损伤阶段的声发射信号特征。根据加载过程中时间–载荷曲线以及试样破坏断面微观形貌,将损伤过程分为三个阶段:初始损伤阶段主要产生少量基体开裂与纤维–基体界面脱粘,裂纹迅速扩展阶段开始产生纤维剪断以及失稳变形,平稳损伤阶段主要产生失稳变形以及分层裂纹扩展。结合声发射信号的振幅、振铃计数研究损伤过程,并基于小波变换进行损伤信号的时频分析,发现不同损伤类型可通过声发射振幅及频率特征有效识别。     

面神经损伤后TGF-β的表达与schwann细胞数量变化关系的研究

目的观察兔面神经夹伤后转化生长因子β(transforming growth factor beta,TGF-β)的表达及施万细胞(schwann cells,SCs)数量的变化,了解两者在面神经损伤修复过程中的相互关系及相互作用。方法取20只新西兰大白兔,造成面神经钳夹伤,于伤后1、3、7、14、21d取材分别进行组织学、免疫组化观察。结果 3d时神经夹伤处TGF-β抗原呈阳性反应,施万细胞增多;7d时TGF-β表达呈强阳性反应,为表达高峰,损伤处的施万细胞明显增多;14d时TGF-β表达的量有所减少,施万细胞数量亦无增多趋势;21d时施万细胞数量和TGF-β抗原表达的量均下降。结论 TGF-β参与面神经损伤的病理过程,并与施万细胞数量的变化存在一定的同步性,证实了两者之间存在相互作用。     

Electroactive Hydroxyapatite/Carbon Nanofiber Scaffolds for Osteogenic Differentiation of Human Adipose-Derived Stem Cells

Traditional bone defect treatments are limited by an insufficient supply of autologous bone, the immune rejection of allogeneic bone grafts, and high medical costs. To address this medical need, bone tissue engineering has emerged as a promising option. Among the existing tissue engineering materials, the use of electroactive scaffolds has become a common strategy in bone repair. However, single-function electroactive scaffolds are not sufficient for scientific research or clinical application. On the other hand, multifunctional electroactive scaffolds are often complicated and expensive to prepare. Therefore, we propose a new tissue engineering strategy that optimizes the electrical properties and biocompatibility of carbon-based materials. Here, a hydroxyapatite/carbon nanofiber (HAp/CNF) scaffold with optimal electrical activity was prepared by electrospinning HAp nanoparticle-incorporated polyvinylidene fluoride (PVDF) and then carbonizing the fibers. Biochemical assessments of the markers of osteogenesis in human adipose-derived stem cells (h-ADSCs) cultured on HAp/CNF scaffolds demonstrate that the material promoted the osteogenic differentiation of h-ADSCs in the absence of an osteogenic factor. The results of this study show that electroactive carbon materials with a fibrous structure can promote the osteogenic differentiation of h-ADSCs, providing a new strategy for the preparation and application of carbon-based materials in bone tissue engineering.     

活性炭再生方法及工艺设备的研究进展

介绍了近年来国内外活性炭再生的主要方法:加热再生法、化学药剂再生法、生物再生法、湿式催化氧化再生法、微波辐射再生法、电化学再生法等,并对加热再生的设备做了比较分析。     

Use of Natural Neural Scaffolds Consisting of Engineered Vascular Endothelial Growth Factor Immobilized on Ordered Collagen Fibers Filled in a Collagen Tube for Peripheral Nerve Regeneration in Rats

The search for effective strategies for peripheral nerve regeneration has attracted much attention in recent years. In this study, ordered collagen fibers were used as intraluminal fibers after nerve injury in rats. Vascular endothelial growth factor (VEGF) plays an important role in nerve regeneration, but its very fast initial burst of activity within a short time has largely limited its clinical use. For the stable binding of VEGF to ordered collagen fibers, we fused a collagen-binding domain (CBD) to VEGF through recombinant DNA technology. Then, we filled the ordered collagen fibers-CBD-VEGF targeting delivery system in a collagen tube to construct natural neural scaffolds, which were then used to bridge transected nerve stumps in a rat sciatic nerve transection model. After transplantation, the natural neural scaffolds showed minimal foreign body reactions and good integration into the host tissue. Oriented collagen fibers in the collagen tube could guide regenerating axons in an oriented manner to the distal, degenerating nerve segment, maximizing the chance of target reinnervation. Functional and histological analyses indicated that the recovery of nerve function in the natural neural scaffolds-treated group was superior to the other grafted groups. The guiding of oriented axonal regeneration and effective delivery systems surmounting the otherwise rapid and short-lived diffusion of growth factors in body fluids are two important strategies in promoting peripheral nerve regeneration. The natural neural scaffolds described take advantage of these two aspects and may produce synergistic effects. These properties qualified the artificial nerve conduits as a putative candidate system for the fabrication of peripheral nerve reconstruction devices.     

Nerve Growth Factor: A Potential Therapeutic Target for Lung Diseases

The lungs play a very important role in the human respiratory system. However, many factors can destroy the structure of the lung, causing several lung diseases and, often, serious damage to people’s health. Nerve growth factor (NGF) is a polypeptide which is widely expressed in lung tissues. Under different microenvironments, NGF participates in the occurrence and development of lung diseases by changing protein expression levels and mediating cell function. In this review, we summarize the functions of NGF as well as some potential underlying mechanisms in pulmonary fibrosis (PF), coronavirus disease 2019 (COVID-19), pulmonary hypertension (PH), asthma, chronic obstructive pulmonary disease (COPD), and lung cancer. Furthermore, we highlight that anti-NGF may be used in future therapeutic strategies.     

测试样品的扫描电镜图像缺陷原因及解决方法

扫描电子显微镜对待测样品的要求极其严格,样品一定要不含水分、无磁性、无毒性且成分稳定,不导电和导电性差的样品要通过离子溅射仪镀膜,它是样品进行微观分析时的重要实验手段。本研究以各研究室送的检测样品为材料,应用扫描电子显微镜对各类样品进行表征。在具体操作时会出现荷电效应、边缘效应、电子束损伤、污染这4种常见的扫描电镜图像缺陷,分析了其影响因素,提出可以通过使样品导电法、降低电压法、快速观察法及减少污染法等方法解决图像缺陷问题,并展示了结果。     

SEM and AFM characterization of surface of two RMGICs for degradation before and after modification with bioactive glass ceramic

Objectives: The aim of this study was to evaluate the effect of bioactive glass–ceramic particles (Biosilicate®) addition on surface nanoroughness and topography of Resin-modified glass ionomer cements (RMGICs).

Methods: Experimental materials were made by incorporating 2 wt% of Biosilicate® into Fuji II LC® (FL) and Vitremer® (VT) powders. Disks of RMGICs (with and without Biosilicate®) measuring 0.5 cm (diameter) × 0.5 mm (thickness) were fabricated and polished. Samples were stored at 37 °C in dry or immersed in distilled water for 30 days. Digital images (20 × 20 μm) from the surfaces were obtained by means of an atomic force microscopy. Three images were acquired for each sample, and four nanoroughness measurements were performed in each image. Nanoroughness (Ra, nm) was assessed by Nanoscope Software V7. Data were analyzed with ANOVA and Student–Newman–Keuls multiple comparisons (p < 0.05). SEM images were obtained for surface topography analysis.

Results: FL was significantly rougher than VT (p < 0.05) in wet and dry conditions. The addition of Biosilicate® increased the surface roughness in VT and decreased in FL, regardless of the storage media (p ≤ 0.05). No differences existed between materials and storage conditions after Biosilicate® addition. Significance: The Biosilicate® particles addition produced changes on the surface nanoroughness of the RMGICs. These changes depended on the particles size of the original cements in dry conditions. In water storage, dissolution of the Biosilicate® particles, a silica-rich gel formation, and a hydroxyl carbonate apatite precipitation on the surface of the materials changed the nanoroughness surface. FL was the roughest in both conditions.

Significance: The Biosilicate® particles addition produced changes on the surface nanoroughness of the RMGICs. These changes depended on the particles size of the original cements in dry conditions. In water storage, dissolution of the Biosilicate® particles, a silica-rich gel formation, and a hydroxyl carbonate apatite precipitation on the surface of the materials changed the nanoroughness surface. FL was the roughest in both conditions.     

气相生长碳纤维的实验探索

气相生长碳纤维是近年来兴起的一项新技术。它以其自身独特的优势吸引了众多研究者的关注。本文采用共沉淀法制备的含Ni^2 ,Cu^2 ,AP^ ,CO3^2-的Feitknecht化合物作为催化剂的母体,经煅烧、还原,制备得Ni-Cu/AI2O3催化剂,从而来考察金属Cu的加入对气相生长碳纤维的影响。     

Gellan-Xanthan Hydrogel Conduits with Intraluminal Electrospun Nanofibers as Physical,Chemical and Therapeutic Cues for Peripheral Nerve Repair

Optimal levels of functional recovery in peripheral nerve injuries remain elusive due to the architectural complexity of the neuronal environment. Commercial nerve repair conduits lack essential guidance cues for the regenerating axons. In this study, the regenerative potential of a biosimulated nerve repair system providing three types of regenerative cues was evaluated in a 10 mm sciatic nerve-gap model over 4 weeks. A thermo-ionically crosslinked gellan-xanthan hydrogel conduit loaded with electrospun PHBV-magnesium oleate-N-acetyl-cysteine (PHBV-MgOl-NAC) nanofibers was assessed for mechanical properties, nerve growth factor (NGF) release kinetics and PC12 viability. In vivo functional recovery was based on walking track analysis, gastrocnemius muscle mass and histological analysis. As an intraluminal filler, PHBV-MgOl-NAC nanofibers improved matrix resilience, deformation and fracture of the hydrogel conduit. NGF release was sustained over 4 weeks, governed by Fickian diffusion and Case-II relaxational release for the hollow conduit and the nanofiber-loaded conduit, respectively. The intraluminal fibers supported PC12 proliferation by 49% compared to the control, preserved up to 43% muscle mass and gradually improved functional recovery. The combined elements of physical guidance (nanofibrous scaffolding), chemical cues (N-acetyl-cysteine and magnesium oleate) and therapeutic cues (NGF and diclofenac sodium) offers a promising strategy for the regeneration of severed peripheral nerves.     

碳化硅陶瓷内筒服役过程中的结构演变和蚀损机理

通过对使用前后的碳化硅陶瓷预热器内筒样品进行扫描电镜显微观察和X射线衍射分析,得出陶瓷内筒在使用过程中的结构演变和蚀损机理.结果表明:碳化硅陶瓷内筒在热烟气的氧化作用下不断被氧化,随后氧化生成的Si02在高速物料的冲蚀磨损作用下断裂、剥落,最终导致的结构损坏.     

氧化铁超细颗粒的制备及其表征

以Fe(NO3)3·9H2O为原料,用水热法制备氧化铁超细粉体,并采用X-射线衍射(XRD)以及扫描电子显微镜(SEM)对制得的粒子进行表征.结果表明,实验中运用水热法制备得到的氧化铁超细颗粒晶型为斜方六面体系,颗粒为球状,直径在120～150nm之间,能够达到程度较高的分散效果.