POSITRON LIFETIME STUDY OF THERMALLY INDUCED MICROSTRUCTURAL CHANGES IN NISTARI SILK FIBER

Positron lifetime measurements have been made in natural polymer-Nistari silk fibers as a function of isochronalannealing temperature in the range of 27℃ to 280℃. The variations in the positron results indicate the structural changesoccurring in the Nistari silk fibers and determine the glass transition temperature as 170℃. Activation energies weremeasured separately for the crystalline and amorphous regions indicating the versatility of the technique. These values areclose to the N--H bond dissociation energy, suggesting N--H bond dissociation as the most probable process occurringduring thermal treatment As an extension of the positron results, the molecular weight of the Nistari silk fibers wasdetermined to be 10.7×10~5 based on free volume, which lies within the range suggested for the silk fibers. There seems to bean indication that cross-linking changes the spiral structure of cotton fibers to network type. However, this needs to be validated by other techniques.

Structures of Silk Fibers Grafted with Hexafluorobutyl Methacrylate

The relationship between the graft yield and the effect of hexafiuorobutyl methacrylate graft treatment on the structural changes of the silk fibers was studied on the basis of the results of scanning electron micrograph photographs （SEM）, infrared spectroscopy （IR）, Raman spectrum, wide-angle X-ray diffraction patterns （WAXD）, nuclear magnetic resonance（NMR） and amion acid analysis. The results showed that the crystalline regions of grafted fibers were hardly affected and the fiber fission occurred on the cross sections of grafted fibers. The surface of fibers was covered with a high polymer film. The Raman spectrum showed there was little change in the conformation of grafted fibers which mainly remained β-sheet conformation. The IR of the grafted silk fibers showed new absorption of bands occurred which belonged to the stretching-vibrationabsorption-peak bands of Vo-o and VC-F of aliphatic ester species. The CF3-, -CF2- and -CFH- grafted silk macromodecul were verified in the NMR spectrum. The amion acid analysis indicated fluoride monomers were inclined to graft with TYR, ARG and CLU silk fibers.

Chemical Modification of Silk Fibers with Ethylene Glycol Dimethacrylate

Silk fibers have been grafted with ethylene glycol dimethacrylate (EGDMA) and characteristics of the grafted silk fibers were analyzed in relation to the graft yield on the basis of the tensile properties, dyeing behaviour, durability during laundering and solubility of the specimen in NaOH solution. The amount of the acid dye absorbed by the fibers decreased with increasing graft yield, while the value of rating for washing fastness on silk fibers was almost unchanged by the graft treatment. The breaking loads of the fiber were almost unchanged whereas rigidity of the fibers increased after graft treatment. Graft treatment enhanced silk fiber durability during laundering and in NaOH solution.

Study of Spider Silk Fibers by Raman Microscopy

Spider silk fibers of species of the genera Araneus, Gasteracantha, and Linothele sericata were studied. The fibers are composed of axial threads and lateral villi, allowing adhesion to surfaces. Raman spectroscopy was used to determine the surface and internal composition of the threads forming the structure. In the three species, the characteristic amino acid peaks of the spider web were found between 2871 and 2975 cm-1, which belong to L-glycine, L-alanine, L-glutamine, and L-proline. The threads are composed of a protective layer mainly composed of amides, alanine, and glycine. The fibrils surrounding the axial fibers consist mainly of amide II (1533 cm-1), which allows adhesion between the thread and the surfaces onto which the spider weaves the web. For the genus Linothele sericata, there is a peak on the surface of this spider web located at 2145 cm-1, which is associated with isonitriles with R-N-C bonds.

Research on the Development of Fibroin and Nano-Fiber from Silk Cocoons for Regenerated Tissue Engineering Applications by Electro-Spinning

In this paper, the main goal is to prepare silk fibroin nano-fiber, which is used for regenerated tissue applications. Silk scaffold nano-fibers made by electro-spinning technology can be used in regenerated tissue applications. The purpose of the research is to prepare a silk-fibroin nano-fiber solution for potential applications in tissue engineering. Using a degumming process, pure silk fibroin protein is extracted from silk cocoons. The protein solution for fibroin is purified, and the protein content is determined. The precise chemical composition, exact temperature, time, voltage, distance, ratio, and humidity all have a huge impact on degumming, solubility, and electro-spinning nano-fibers. The SEM investigates the morphology of silk fibroin nano-fibres at different magnifications. It also reveals the surface condition, fiber orientation, and fiber thickness of the silk fibroin nano-fiber. The results show that regenerated silk fibroin and nano-fiber can be used in silk fibroin scaffolds for various tissue engineering applications.

Wet-spinning of Regenerated Silk Fiber from Aqueous Silk Fibroin Solutions: Influence of Calcium Ion Addition in Spinning Dope on the Performance of Regenerated Silk Fiber

Ca（II） ions are added in the spinning dope to adjust the solidification rate of regenerated silk fibroin （RSF） solution during the wet-spinning process since Ca（II） ions are proved to be favorable to maintain the stable silk fibroin network in our previous work. The results show that when Ca（II）/RSF ratios are 1/50 and 1/20, the resulted RSF fibers exhibit good performance with the breaking energy more than 70 kJ/kg. However, higher Ca（II）/RSF ratio （for example, 1/10） hinders the solidification of spinning dope and results in poor RSF fibers. These observations together with earlier papers from this laboratory confirm that to produce tough silk fibers the spinning conditions must allow sufficient time for the adjustment of silk fibroin molecular chains.

Micro/nano processing of natural silk fibers with near-field enhanced ultrafast laser

Silkworm silk fiber is an attractive material owing to its remarkable mechanical characteristics,excellent optical properties,and good biocompatibility and biodegradability.However,nano-processing of the silk fiber is still a challenge limiting its applications in nanoengineering and related fields.Herein,we report localized near-field enhancement-assisted ablation with an ultrafast laser to break this bottleneck.Localized processing of silk fiber,including nano-holing,nano-grooving,and cutting could retain the key molecular structure building blocks and the pristine functionality of the silk fiber.An extremely narrow nanohole with a width of^64 nm was successfully achieved.The processed silk fiber can be used to transfer micro/nanoparticles and drugs,showing potential for biomedical engineering.The processing strategy developed in this study can also be extended to other materials,paving a new way for fabricating functional nanostructures with precisely controlled size and morphology.

A host-guest approach to fabricate metallic cobalt nanoparticles embedded in silk-derived N-doped carbon fibers for efficient hydrogen evolution

Hydrogen evolution reaction(HER) plays a key role in generating clean and renewable energy. As the most effective HER electrocatalysts, Pt group catalysts suffer from severe problems such as high price and scarcity. It is highly desirable to design and synthesize sustainable HER electrocatalysts to replace the Pt group catalysts. Due to their low cost, high abundance and high activities, cobalt-incorporated N-doped nanocarbon hybrids are promising candidate electrocatalysts for HER. In this report, we demonstrated a robust and eco-friendly host-guest approach to fabricate metallic cobalt nanoparticles embedded in N-doped carbon fibers derived from natural silk fibers. Benefiting from the onedimensional nanostructure, the well-dispersed metallic cobalt nanoparticles and the N-doped thin graphitized carbon layer coating, the best Cobased electrocatalyst manifests low overpotential(61 mV@10 mA/cm^2) HER activity that is comparable with commercial 20% Pt/C, and good stability in acid. Our findings provide a novel and unique route to explore high-performance noble-metal-free HER electrocatalysts.

Blended Yarns of Modacrylic Fibers with Silk Protein

The fiber properties of modacrylic fibers with silk protein and spinning technology for blended knitting yarns are studied. By testing the fiber properties, fiber spinnability is analysed. Modacrylic fibers with silk protein are brittle and have poor cohesion, so the key to process modacrylic fibers with silk protein lies in forming lap and sliver. During opening and carding, low speed is used to decrease fiber damage and the proper static resistant oil is applied to eliminate lapping fibers. Besides, the temperature and relative humidity have to be strictly controlled. The applications of modacrylic fibers with silk protein are also put forward.

THE SCROOPING TREATMENT OF POLYESTER SILKLIKE FIBERS

In this paper the mechanism producing scrooping sound has been discussedtheoretically.It has been recognized that the continuous stick-slip vibrationhaving a certain period and the bigger △E(△E——enery released by stick-slipvibration at one time)are the requisite and surfficient conditions producingscrooping sound.For fiber sample,its surface properties and internal structureare two principal factors influencing scrooping sound. Considering the surface properties of polyester fiber after scrooping treatmentare the synthetic reflection of the properties used treatment reagents and thesurface properties of the fiber,how selecting proper reagents for scroopingtreatment would be the key factor influencing the scrooping effect.Sometreatment solutions having better scrooping effect have been obtained in the paper. In order to cause better scrooping effect,not only the treatment reagent andsurface properties of the fiber,but also the internal structure of the fiber must beconsidered,It has been shown in

PREPARATION AND CATALYTIC ACTIVITY OF BIOACTIVE FIBERS

Two kinds of water-soluble metallophthalocyanines, binuclear cobalt phthalocyanine （Co2Pc2） and binuclear ferric phthalocyanine （Fe2Pc2）, were synthesized through phenylanhydride-urea route and characterized by elemental analysis and FT-IR spectra. Binuclear metallophthalocyanine derivatives （Mt2Pc2） were immobilized on silk fibers and modified viscose fibers to construct bioactive fibers of mimic enzyme. Mt2Pc2 was used as the active center of bioactive fibers, viscose and silk fibers as the microenvironments. The catalytic oxidation ability of bioactive fibers on the malodors of methanthiol and hydrogen sulfide was investigated at room temperature. The experimental results indicated that the catalytic activity of such bioactive fibers was closely correlative to the types ofbioactive fibers and substrates.

STUDY ON THE CATALYTIC ABILITY OF BIOACTIVE FIBERS

Two kinds of water-soluble metallophthalocyanines （Mt2Pc2）, binuclear cobalt phthalocyanine （Co2Pc2） and binuclear ferric phthalocyanine （Fe2Pc2）, were supported on silk fibers and modified viscose fibers to construct bioactive fibers of mimic enzyme, Mt2Pc2 used as the active center of bioactive fibers, viscose and silk fibers as the microenvironments. The catalytic oxidation ability of bioactive fibers on the malodors of methanthiol and hydrogen sulfide was investigated at room temperature. The experimental results demonstrated that the catalytic activity of such bioactive fibers was tightly correlative to the types of bioactive fibers and substrates.

Preparation of Silk-Like PET Microfilament and Its Properties

The polyester microfilament was prepared by means ofnormal fully drawn yarn(FDY)equipment.The effectof water content in chips,the molecular weight of thechips,the jet stretch ratio and the lateral blow on thespinnability and the finest titre of filament that could bereach were discussed.Under convenient conditions,thefiber with linear density of about 1.4 dtex could be ob-tained.By means of wide angle X-ray diffractometer(WAXD),differential scanning calorimeter(DSC)andInstrontester,the structure and properties of the mi-crofilament were discussed.

玉米须不溶性膳食纤维分析及其对面包品质和消化特性的影响研究

首先分析玉米须不溶性膳食纤维(corn silk insoluble dietary fiber,CSIDF)的组分和物理特性,再研究其添加量及粒径对面包比容、色泽、质构、孔隙度、感官等品质和消化特性的影响。结果表明,其主要含80.64%膳食纤维和10.15%蛋白质,以及少量的灰分和脂肪,主要由50.41%纤维素和28.80%半纤维素组成,具有良好的持水、持油和膨胀特性,且粒径越大,3种特性越好;添加玉米须不溶性膳食纤维后面包比容减小,色泽加深,硬度增大,孔隙度降低,不同CSIDF添加量及粒径间存在差异,面包品质与CSIDF添加量及粒径基本呈现负相关,综合分析确定粒径最小的D_(1)(平均粒径为24.91μm)最适宜添加,其添加量为3%时较合适;体外消化试验表明,CSIDF可以通过降低面包中RDS含量、提高SDS和RS含量来延缓淀粉的消化吸收,维持血糖稳定。

盐浓度对再生丝素蛋白纤维降解性能的影响分析

降解性是再生丝素蛋白材料在组织工程支架材料中应用的重要性能之一,为了探究再生丝素蛋白纤维的可控降解性能,讨论了丝素溶解体系中盐浓度对再生丝素蛋白纤维降解性能的影响。结果表明:当CaCl_(2)质量分数为6%时,再生丝素蛋白纤维表面光滑、结构致密,在降解过程中表现出相对稳定的性质,降解25 d后,纤维表面只出现少许裂痕,降解率为3.8%,断裂强度下降了22.7%;当CaCl_(2)质量分数为2%和10%时,25 d后的降解率分别为9.4%和16.5%,断裂强度分别下降了43.2%和75.4%,纤维的可纺性变差,降解过程中纤维性能不稳定。在实际应用中可以通过调节溶解体系中盐的浓度来调控再生丝素蛋白纤维的降解性能。

功能性蚕丝纤维研究新进展

蚕丝纤维因其优异的穿着舒适性,出色的力学性能、生物相容性、生物可降解性及其对人体无毒无炎症的特点,逐渐在多学科交叉融合应用方面表现出巨大的潜力,但同时也因其存在光致发黄、老化、细菌引起的变形甚至降解、不能机洗、难打理等缺陷,急需实现技术创新,开发具有更广阔应用场景的高性能/多功能蚕丝纤维。本文系统总结了高性能/多功能蚕丝纤维制备新技术,包括基因编辑法、添食法、物理改性法、化学改性法,并指出其所存在的问题和面临的挑战。在此基础上,进一步探讨了高性能/多功能蚕丝纤维的未来发展方向,以期为我国桑蚕产业的转型升级提供理论支撑。

聚合物光纤发光面料的设计与开发

为了满足人们对纺织品个性化和多样化的需求,以聚合物光纤(POF)为发光体,依据光纤侧面发光原理设计开发聚合物光纤发光机织面料,介绍面料的灵感来源、光纤分布设计、组织设计、纱线设计及其排列、穿综设计、上机织造工艺等,在半自动打样机上进行试织并说明织造要点。结果表明:合理利用发光体和其他纱线,结合纬向管状组织、平纹小提花组织以及缂丝技术等,开发出更加时尚化、个性化的发光面料。发光面料主要应用于装饰纺织品,其结构独特、配色协调、立体感强,具有较强的装饰性和乐趣性,在一定程度上也起到安全警示作用。

二化螟盘绒茧蜂茧丝纤维的形态结构与理化性能

本文通过扫描电镜(SEM)、氨基酸分析、傅立叶红外光谱(FTIR)、X射线晶体衍射(XRD)和热重分析(TG)等技术对二化螟盘绒茧蜂Cotesia chilonis茧丝纤维的微观形态、氨基酸类别与组成、二级结构和热稳定性等作了分析。结果表明,二化螟盘绒茧蜂的茧丝纤维表面较为粗糙,直径为1.89±0.04μm。茧丝纤维主要由碳(60.67%)、氮(21.17%)和氧(17.22%)等元素组成,其丝蛋白主要成分包括天冬氨酸/天冬酰胺、丝氨酸和丙氨酸等;蛋白二级结构主要为β-折叠;其峰值降解温度为332.27℃±2.58℃。本文研究揭示了二化螟盘绒茧蜂茧丝纤维的结构特征与理化性能,为拓展该蜂的应用领域、开发性能优越的非蚕丝蛋白以及设计改造新型丝蛋白纤维提供基础。

茶梗儿茶素的制备及其对蚕丝织物的染色和功能改性

为提高茶梗废弃物的利用率,从中提取天然色素用于蚕丝织物的染色和功能改性。采用LC-MS、FTIR以及UV对茶梗提取物进行结构鉴定及表征;探究染色时间、染色温度、染色pH值等工艺参数对染色蚕丝颜色性能的影响,比较铁观音茶梗、铁观音茶叶、高山绿茶的提取物对蚕丝织物的染色性能以及抗紫外、抗氧化性能差异。结果表明:该茶梗提取物主要成份为儿茶素,对蚕丝染色的最佳工艺条件为染色时间70 min、染色温度80℃、染色pH值为7.5;3种不同来源儿茶素染色性能相比,铁观音茶梗儿茶素染色蚕丝的表面得色量稍高,色牢度三者相当;3种儿茶素染色蚕丝的抗氧化和抗紫外性能较未处理蚕丝有大幅度提高,直接染色蚕丝的紫外防护系数UPF值均大于150,抗氧化活性均大于60%;采用铝离子前媒染后染色蚕丝的UPF值均大于230,抗氧化活性均大于70%,铁观音茶梗儿茶素染色蚕丝的抗紫外性能优于另外两种茶叶,抗氧化性能比绿茶低、与铁观音绿茶相当。

力学增强且降解延缓的编织型丝素纤维人工韧带材料研究

针对人工韧带产品在临床应用中存在的问题,如不可降解、应力遮挡、中远期疲劳松弛、慢性炎症等,研究力学性能优良的可降解人工韧带材料是新的发展方向。以丝素纤维为原材料,设计并制备了一种“壳芯”结构的人工韧带原型材料(artificial ligament, AL),并以负载纳米羟基磷灰石(hydroxyapatite, Hap)的聚氨酯(polyurethane, PU)溶液对AL进行涂层得到人工韧带材料(coated artificial ligament, CAL),并对CAL的形态结构、显微结构、力学性能、降解性能、细胞和组织相容性等进行了系统表征。研究结果表明:“壳芯”结构的CAL结构规整、表面平整、孔隙均匀。相较于AL,CAL的力学性能得到了显著提高(P<0.05),且体外降解速率明显延缓。此外,CAL的细胞及组织相容性良好,炎症反应低。该项研究可为开发新型高强可降解人工韧带产品提供理论依据及实践参考。