化学合成纤维在土建工程领域中的应用及发展

本文综合分析了化纤织物近十年来在土建工程方面的应用情况，根据其发展速度预计出下一个五年使用量和品种。并综合了土建工程用各种织物的生产工艺。

关于织物组织设计的理念更新

针对织物组织设计现存的思维定势,提出了设计理念的更新:朝着面向市场终端产品,面向数字化CAD技术,面向基于CAD技术的织物工程方向转化。

欧美各国工程纺织品的开发动向

常规纤维性能正在逐渐提高,多数工业纤维已经基本达到最高性能和多功能,在实际应用中已基本能够满足需求;工程纤维及其纺织品的开发将是今后在纤维材料领域的重要方向。文章介绍欧美国家推出的几种具代表性的工程纤维、工程纱线与工程织物及其加工技术,指出欧美国家在工程纺织品领域的开发动向,并展望工程纺织品的发展前景。

土工织物加筋路堤筋-土界面摩擦力分布形式分析

编制了有限元程序,对大量工程实例进行了计算分析,提出了改进的筋-土界面摩擦力分布形式。

Tissue engineering for the repair of peripheral nerve injury

Peripheral nerve injury is a common clinical problem and affects the quality of life of patients. Traditional restoration methods are not satisfactory. Researchers increasingly focus on the field of tissue engineering. The three key points in establishing a tissue engineering material are the biological scaffold material, the seed cells and various growth factors. Understanding the type of nerve injury, the construction of scaffold and the process of repair are necessary to solve peripheral nerve injury and promote its regeneration. This review describes the categories of peripheral nerve injury, fundamental research of peripheral nervous tissue engineering and clinical research on peripheral nerve scaffold material, and paves a way for related research and the use of conduits in clinical practice.

Preparation of new tissue engineering bone-CPC/PLGA composite and its application in animal bone defects

To investigate the feasibility of implanting the biocomposite of calcium phosphate cement(CPC)/polylactic acid-polyglycolic acid(PLGA) into animals for bone defects repairing,the biocomposite of CPC/PLGA was prepared and its setting time,compressive strength,elastic modulus,pH values,phase composition of the samples,degradability and biocompatibility in vitro were tested.The above-mentioned composite implanted with bone marrow stromal cells was used to repair defects of the radius in rabbits.Osteogenesis was histomorphologically observed by using an electron-microscope.The results show that compared with the CPC,the physical and chemical properties of CPC/PLGA composite have some differences in which CPC/PLGA composite has better biological properties.The CPC/PLGA composite combined with seed cells is superior to the control in terms of the amount of new bones formed after CPC/PLGA composite is implanted into the rabbits,as well as the speed of repairing bone defects.The results suggest that the constructed CPC/PLGA composite basically meets the requirements of tissue engineering scaffold materials and that the CPC/PLGA composite implanted with bone marrow stromal cells may be a new artificial bone material for repairing bone defects because it can promote the growth of bone tissues.

3D Photo-Fabrication for Tissue Engineering and Drug Delivery

The most promising strategies in tissue engineering involve the integration of a triad of biomaterials, living cells, and biologically active molecules to engineer synthetic environments that closely mimic the healing milieu present in human tissues, and that stimulate tissue repair and regeneration. To be clinically effective, these environments must replicate, as closely as possible, the main characteristics of the native extracellular matrix(ECM) on a cellular and subcellular scale. Photo-fabrication techniques have already been used to generate 3D environments with precise architectures and heterogeneous composition, through a multi-layer procedure involving the selective photocrosslinking reaction of a light-sensitive prepolymer. Cells and therapeutic molecules can be included in the initial hydrogel precursor solution, and processed into 3D constructs. Recently, photofabrication has also been explored to dynamically modulate hydrogel features in real time, providing enhanced control of cell fate and delivery of bioactive compounds. This paper focuses on the use of 3D photo-fabrication techniques to produce advanced constructs for tissue regeneration and drug delivery applications. State-of-the-art photo-fabrication techniques are described, with emphasis on the operating principles and biofabrication strategies to create spatially controlled patterns of cells and bioactive factors. Considering its fast processing, spatiotemporal control, high resolution, and accuracy, photo-fabrication is assuming a critical role in the design of sophisticated 3D constructs. This technology is capable of providing appropriate environments for tissue regeneration, and regulating the spatiotemporal delivery of therapeutics.

The Biocompatibility of Wool Keratin

Keratin is the major structural fibrous protein providing outer covering such as hair,wool,feathers,etc.When being used as a kind of biomaterials,the biocompatibility of wool keratin is one of the most critical questions.By now,there has not been systemic study on the biocompatibility of keratin.Therefore,in this article we used the procedures of skin irritation,haemolysis and subcutaneous implantation according to ISO 10993 to study it.Moreover,the Fourier transform-infrared(FTIR) spectroscopy was utilized to analyse the impurity and structure modification of wool keratin film.The part of the animal tests showed that the wool keratin films prepared by authors were biocompatible.But the residual of sodium dodecyl sulfate(SDS) affected the results of other tests.Consequently,the wool keratin membrane is one kind of favourable and promising biomaterial for biomedical and histological utilization.The residual SDS used as an agent should be eliminated from the keratin solution or membrane completely if for biological usage.In conclusion,wool keratin,as a kind of natural protein,prospectively could be applied in biomedical materials and scaffolds of tissue engineering.

Recent Progress in Cartilage Tissue Engineering--Our Experience and Future Directions

Given the limited spontaneous repair that follows cartilage injury, demand is growing for tissue engi- neering approaches for cartilage regeneration. There are two major applications for tissue-engineered cartilage. One is in orthopedic surgery, in which the engineered cartilage is usually used to repair cartilage defects or loss in an articular joint or meniscus in order to restore the joint function. The other is for head and neck reconstruction, in which the engineered cartilage is usually applied to repair cartilage defects or loss in an auricle, trachea, nose, larynx, or eyelid. The challenges faced by the engineered car- tilage for one application are quite different from those faced by the engineered cartilage for the other application. As a result, the emphases of the engineering strategies to generate cartilage are usually quite different for each application. The statuses of preclinical animal investigations and of the clinical translation of engineered cartilage are also at different levels for each application. The aim of this review is to provide an opinion piece on the challenges, current developments, and future directions for cartilage engineering for both applications.

Preparation and Properties of Collagen-Chitosan/Glycosaminoglycans as Candidate Tissue Engineering Biomaterials

A novel biomaterial scaffold was created from collagen chitosan/GAG. Its tensile strength was 8.6MPa(wet state)and degree of swelling water was 60%～75% with higer ultimate elongation 300%. Rabbit corneas of collagen chitosan/GAG implantation samples in vivo for biodegradation showed that the inplantion samples was complets biodegrable and digested afere 120 day. There was enought time to maintain cell growth,immigrating and proliferation. This biomaterials scaffold can be used for cell culture and in various tissue engineering fields.

Study on Different Modification Methods of Collagen for Tissue Engineering

Because of the excellent biocompatibility and its specific amino sequences,collagen is an ideal biomedical material for tissue engineering applications. But collagen is usually lack of mechanical strength to form a rigid 3-D matrix and lack of ability to resist collagenase. In order to be a tissue engineering scaffold,collagen must strengthen its structures by modifying with chemical crosslinkers. Chemical crosslinkers used for modifying collagen fibers include glutaraldehyde(GA),epoxy compounds(PC) and carbodiimides (EDC). The aim of this study is to choose the best chemical crosslinker from the three reagents. In terms of the resistance to collagenase degradation,chemical cross-linking with PC provided the best protection; in terms of the mechanical characterization,chemical cross-linking with GA provided the best;and in terms of the biocompatibility,chemical cross-linking with EDC provided the best.There is not a reagent which has all merits for collagen crosslinking,so we should select the crosslinking reagent as the demands of use ask.

Study on biocompatibility of PDLLA/HA/DBM with co-cultured human osteoblasts in vitro

Objective: To evaluate the osteocompatibility of D, L-polylactic/hydroxyapatite/decalcifying bone matrix (PDLLA/HA/DBM), and compare with PDLLA and DBM. Methods: Human primary osteoblasts isolated from the femoral head of patients were inoculated onto PDLLA/HA/DBM, PLA and DBM respectively. The proliferation rate and collagen Ⅰ expression were detected. The interface between biomaterial and osteoblasts was investigated with phase contrast microscopy and electron scanning microscopy. Results: Best proliferation rate was observed with the PDLLA/HA/DBM and followed by DBM and PLA, suggesting that PDLLA/HA/DBM satisfying most requirements for the cultivation of human osteoblasts. Scanning electron microscopy showed the morphology of osteoblasts was correlated with the proliferation data. The cells, well spread and flattened, were attached closely on the surface of biomaterial with an arched structure and had normal morphology. The extracellular collagenous matrixs covered the surface of biomaterial and packed the granules of biomaterial. Conclusion: PDLLA/HA/DBM can form osteointerface early and have a good biocompability.

Tissue engineering for neuromuscular disorders of the gastrointestinal tract

The digestive tract is designed for the optimal processing of food that nourishes all organ systems.The esophagus,stomach,small bowel,and colon are sophisticated neuromuscular tubes with specialized sphincters that transport ingested food-stuffs from one region to another.Peristaltic contractions move ingested solids and liquids from the esophagus into the stomach;the stomach mixes the ingested nutrients into chyme and empties chyme from the stomach into the duodenum.The to-and-fro movement of the small bowel maximizes absorption of fat,protein,and carbohydrates.Peristaltic contractions are necessary for colon function and defecation.

The Experimental Study on Constructing the Tissue Engineered Myocardium-like Tissue in vitro with Bone Mesenchymal Stem Cells

Objective:Unlike other tissues,myocardium has not substitute whick can be used to repair damaged cardiac tissue.This paper proposes engineering 3-D myocardium-like tissue constructs in vitro with bone mesenchymal stem cells(BMSCs) of infant and poly-lactic-co-glycolic acid(PLGA)in vitro.Methods:Bone marrow was obtained from the sternal marrow cavum outflow of infant with congenital heart disease (CHD)undergoing cardiac operation.BMSCs were obtained by density gradient centrifugation.The cells in passages two were induced in DMED with 10 umol/L 5- Azacytidine(5-Aza)for 24 h.When the induced BMSCS were cultured nearly into filled,the cells were planted in the scaffold of PLGA in 5.5×106 cells/cm2.The cell- scaffold complex has been cultured in the shake cultivation for 1 week,then the complex has been planted in the dorse of the nude mouse.When the experiment had been finished,the histology,immunology,real time PCR and so on were done.Results: The BMSCs of infant with congenital heart disease have the properties of the stable growth and the rapid proliferation.The immunohistochemistry showed that tissue engineered myocardium constructed in vitro expressed some cardiac related proteins such asα-actin,Cx-43,Desmine,cTNI and so on.The transparent myofilaments,gap junctions and intercalated disk-like structure formation could be observed in the 3D tissue-like constructs by transmission electron microscope(TEM).The engineered myocardium-like tissue had the auto-myocardial property as assessed by real time- PCR and so on.Conclusion:The engineered myocardial tissue-like constructs could be built with infant BMSCs and PLGA in vitro.Our results may provide the first step on the long road toward engineering myocardial material for repairing the defect or augmenting the tract in CHD,such as ventricular septal defect,tetralogy of Fallot and so on.

Preparation and Biocompatibility of Porous Poly(vinylalcohol)-Glycosaminoglycan-Collagen Scaffold

This paper aims to prepare a PVA-GAG-COL composite with polyvinyl alcohol (PVA), glycosaminoglycan (GAG) and collagen (COL) by the method of freeze drying and to investigate the feasibility as a tissue engineering scaffold for tissue or organ repairing. In this study, SEM was used to observe the morphology. Biocompatibility was tested by cell culture with the extracted fluid of composite materials. Different proportional scaffolds could be obtained with different concentrations and alcoholysis degree of PVA. Different proportional scaffolds also had different porous structures. SEM proved that large amount of porous structure could be formed. Biocompatibility test showed that the extracted fluid of composite materials was nontoxic, which could promote the adhesion and proliferation of the fibroblast. Fibroblast could grow on the scaffold normally.A porous scaffold for tissue engineering with high water content can be fabricated by PVA, GAG and COL, which has excellent cell biocompatibility. The porous structure shows potential in tissue engineering and cell culture.

Regenerative medicine technology applied to gastroenterology:Current status and future perspectives

This special issue of World Journal of Gastroenterology has been conceived to illustrate to gastroenterology operators the role that regenerative medicine(RM) will have in the progress of gastrointestinal(GI) medicine.RM is a multidisciplinary field aiming to replace,regenerate or repair diseased tissues or organs.The past decade has been marked by numerous ground-breaking achievements that led experts in the field to manufacture functional substitutes of relatively simple organs.This progress is paving the ground for investigations that aims to the bioengineering and regeneration of more complex organs like livers,pancreas and intestine.In this special issue,the reader will be introduced,hand-in-hand,to explore the field of RM and will be educated on the progress,pitfalls and promise of RM technologies as applied to GI medicine.

The status and progress ofrevascularization on clinical applications

The development of biomedicine has offered new prospects for clinical tissue transplantation. In researching tissue engineering products, the key issue is the construction of micro-circulation network and effective induction of angiogenesis is the current continuous explore direction. Revascularization strategy currently focuses on angiogenesis and angiogenesis, but with the advent of microscopic engineering technology, direct construction of artificial micro-circulation pipe has been a new way of thinking.

Corneal regeneration by utilizing collagen based materials

Corneal disease is the main cause of blindness and keratoplasty is the only widely accepted treatment. Shortage of donor tissue makes the biomaterials for corneal regeneration a hot area of research. Collagen is the main component of corneal stroma, so collagen becomes a promising material for corneal repair. However, due to the drawbacks of collagen, it needs to be further modified to satisfy the requirement of corneal regeneration. In this article, we highlight the importance of collagen materials for corneal repair, and summarize several methods of preparing collagen based corneal regeneration materials, including chemical crosslinking, plastic compression of collagen, and collagen vitrigel. These modification methods can make collagen membranes with remarkable properties such as enough mechanical and suture retention strength, antibacterial property and excellent optical property. These materials may provide potential treatment for corneal disease.

Digital design of scaffold for mandibular defect repair based on tissue engineering

Mandibular defect occurs more frequently in recent years,and clinical repair operations via bone transplantation are difficult to be further improved due to some intrinsic flaws.Tissue engineering,which is a hot research field of biomedical engineering,provides a new direction for mandibular defect repair.As the basis and key part of tissue engineering,scaffolds have been widely and deeply studied in regards to the basic theory,as well as the principle of biomaterial,structure,design,and fabrication method.However,little research is targeted at tissue regeneration for clinic repair operations.Since mandibular bone has a special structure,rather than uniform and regular structure in existing studies,a methodology based on tissue engineering is proposed for mandibular defect repair in this paper.Key steps regarding scaffold digital design,such as external shape design and internal microstructure design directly based on triangular meshes are discussed in detail.By analyzing the theoretical model and the measured data from the test parts fabricated by rapid prototyping,the feasibility and effectiveness of the proposed methodology are properly verified.More works about mechanical and biological improvements need to be done to promote its clinical application in future.