Scientific investigations involving collagen have inspired tissue engineering and design of biomaterials since collagen fibrils and their networks primarily regulate and define most tissues. The collagen networks form a highly organized, three-dimensional architecture to entrap other ingredients. Biomaterials are expected to function as cell scaffolds to replace native collagen-based extracellular matrix. The composition and properties of biomaterials used as scaffold for tissue engineering significantly affect the regeneration of neo-tissues and influence the conditions of collagen engineering. The complex scenario of collagen characteristics, types, fibril arrangement, and collagen structure-related functions (in a variety of connective tissues including bone, cartilage, tendon, skin and cornea) are addressed in this review. Discussion will focus on nanofibrillar assemblies and artificial synthetic peptides that mimic either the fibrillar structure or the elemental components of type I collagen as illustrated by their preliminary applications in tissue engineering. Conventional biomaterials used as scaffolds in engineering collagencontaining tissues are also discussed. The design of novel biomaterials and application of conventional biomaterials will facilitate development of additional novel tissue engineering bioproducts by refining the currently available techniques. The field of tissue engineering will ultimately be advanced by increasing control of collagen in native tissue and by continual manipulation of biomaterials. GENERAL DESCRIPTION ON COLLAGEN IN CONNECTIVE TISSUESThe extracellular matrix (ECM), provides physical support to tissues by occupying the intercellular space, acting not only as benign native scaffolding for arranging cells within connective tissues, but also as a dynamic, mobile, and flexible substance defining cellular behaviors and tissue function (1). For most soft and hard connective tissues (bone, cartilage, tendon, cornea, blood vessels, and skin) collagen fibrils and their networks function as ECM, the highly organized, three-dimensional (3D) architecture surrounding various cells. Collagen plays a dominant role in maintaining the biologic and structural integrity of ECM and is highly dynamic, undergoing constant remodeling for proper physiologic functions (1). Hence, the ideal goal of tissue regeneration is to restore both the structural integrity and the vivid remodeling process of native ECM, especially restoring the delicate collagen networks under which normal physiologic regeneration occurs.Collagen molecules have a triple-helical structure and the presence of 4-hydroxyproline resulting from a posttranslational modification of peptide-bound prolyl residues provides a distinctive marker of these molecules (2). To date, 28 collagen types have been identified; I, II, III, and V are the main types that make up the essential part of collagen in bone, cartilage, tendon, skin, and muscle. They also exist in fibrillar forms with elaborate 3D arrays in ECM (3-5).Bone tissu...

Driven by deep neural networks and large scale datasets, scene text detection methods have progressed substantially over the past years, continuously refreshing the performance records on various standard benchmarks. However, limited by the representations (axis-aligned rectangles, rotated rectangles or quadrangles) adopted to describe text, existing methods may fall short when dealing with much more free-form text instances, such as curved text, which are actually very common in real-world scenarios. To tackle this problem, we propose a more flexible representation for scene text, termed as TextSnake, which is able to effectively represent text instances in horizontal, oriented and curved forms. In TextSnake, a text instance is described as a sequence of ordered, overlapping disks centered at symmetric axes, each of which is associated with potentially variable radius and orientation. Such geometry attributes are estimated via a Fully Convolutional Network (FCN) model. In experiments, the text detector based on TextSnake achieves state-of-the-art or comparable performance on Total-Text and SCUT-CTW1500, the two newly published benchmarks with special emphasis on curved text in natural images, as well as the widely-used datasets IC-DAR 2015 and MSRA-TD500. Specifically, TextSnake outperforms the baseline on Total-Text by more than 40% in F-measure.

Aerosol samples of PM 2.5 and PM 10 were collected in both summer and winter seasons from 2002 to 2003 synchronously at a traffic site, an industrial site, and a residential site in Beijing, which could basically be the representatives over Beijing. Twenty-three elements and 15 ions together with organic carbon and elemental carbon were analyzed systematically for characterization of Beijing aerosol. PM 2.5 was the major part of the inhalable particles (PM 10 ), as the ratios of PM 2.5 /PM 10 were 0.45-0.48 in summer and 0.52-0.73 in winter. SO 4 2À, NO 3 À , NH 4 + , organic matter, crustal matter, and element carbon were the six dominant species, which totally accounted for 85.8-97.7% of PM 2.5 . Secondary aerosol (SO 4 2À , NO 3 À , and NH 4 + ), road dust or/and long-range transported dust from outside Beijing, industry and motor vehicles emission, coal burning were the major contributors to the air-borne particulate pollution in Beijing. Overall, coal burning and the traffic exhausts, plus the dust from the long-range transport, could be the major sources of the aerosol pollution at Beijing. A relatively even spatial distribution of chemical species in PM 2.5 was found while in PM 10 a significant variation with the highest concentrations at the industrial site in summer and at the residential site in winter was observed. The concentrations of PM 10 , PM 2.5 as well as various chemical species were higher in winter than in summer. The contributions of mineral aerosol from outside Beijing were first estimated with a newly developed element tracer technique, which accounted for 79% and 37% of the total mineral in PM 10 and PM 2.5 in winter, and 19% and 20% in summer, respectively. During the dust storm period from 20 to 22 March, it reached up to 97% in TSP, 79% in PM 10 and 76% in PM 2.5 . This is the technique, firstly, developed for estimating the relative contributions of sources from inside and outside Beijing to the total mineral aerosol and it could provide the basic information in controlling the air-borne particulate pollution at Beijing. r

Background: Bone marrow-derived mesenchymal stem cells (BMSCs) are a widely researched adult stem cell population capable of differentiation into various lineages. Because many promising applications of tissue engineering require cell expansion following harvest and involve the treatment of diseases and conditions found in an aging population, the effect of donor age and ex vivo handling must be understood in order to develop clinical techniques and therapeutics based on these cells. Furthermore, there currently exists little understanding as to how these two factors may be influenced by one another.

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