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Yanzhong Zhang - One of the best experts on this subject based on the ideXlab platform.

  • Stiffness of Aligned Fibers Regulates the Phenotypic Expression of Vascular Smooth Muscle Cells.
    ACS Applied Materials & Interfaces, 2019
    Co-Authors: Bingcheng Yi, Xianliu Wang, Yanbing Shen, Han Tang, Bin Li, Yanzhong Zhang
    Abstract:

    Electrospun uniaxially aligned ultrafine fibers show great promise in constructing vascular grafts mimicking the anisotropic architecture of native blood vessels. However, understanding how the stiffness of aligned fibers would impose influences on the functionality of vascular cells has yet to be explored. The present study aimed to explore the stiffness effects of electrospun aligned fibrous substrates (AFSs) on phenotypic modulation in vascular smooth muscle cells (SMCs). A Stable Jet coaxial electrospinning (SJCES) method was employed to generate highly aligned ultrafine fibers of poly(l-lactide-co-caprolactone)/poly(l-lactic acid) (PLCL/PLLA) in shell–core configuration with a remarkably varying stiffness region from 0.09 to 13.18 N/mm. We found that increasing AFS stiffness had no significant influence on the cellular shape and orientation along the fiber direction with the cultured human umbilical artery SMCs (huaSMCs) but inhibited the cell adhesion rate, promoted cell proliferation and migration,...

  • fabrication of high performance silk fibroin fibers via Stable Jet electrospinning for potential use in anisotropic tissue regeneration
    Journal of Materials Chemistry B, 2018
    Co-Authors: Huilan Zhang, Huihua Yuan, Xianliu Wang, Yanzhong Zhang
    Abstract:

    Regenerated silk fibroin (SF) from Bombyx mori silkworm cocoons is a highly regarded natural protein-biomaterial suitable for engineering a variety of biological tissues. Electrospinning offers a unique approach to fiber formation that can readily produce micro- and nano-scale fibers recapitulating the ultrastructure of a native extracellular matrix. However, SF fibers from conventional electrospinning suffer from the problem of poor mechanical properties for load-bearing relevant tissue regeneration applications. In this study, highly aligned high-strength SF fibers were fabricated by a recently emerged Stable Jet electrospinning (SJES) approach, with the aid of high molecular weight poly(ethylene oxide) (PEO) acting as a fiber-forming ingredient to increase control over the Jetting instability during electrospinning. The results showed that 90% of the collected SF/PEO (mass ratio 88 : 12) fiber assembly via SJES oriented unidirectionally with an angle variation of <1° and displayed obvious anisotropic wettability. Mechanically, the as-electrospun highly aligned SF/PEO fibers exhibited a 22.0-fold increase in ultimate tensile strength (50.85 ± 1.13 MPa) and a 49.3-fold increase in Young's modulus (1185.99 ± 164.56 MPa) compared with the randomly oriented SF fibers. A subsequent methanol treatment further remarkably boosted the tensile strength to 73.91 ± 5.15 MPa and Young's modulus to 2426.13 ± 86.67 MPa. The mechanical performance of the SF fibers via SJES was also impressive, even when tested in the wet state. The substantial improvement in the mechanical properties of the electrospun SF fibers is attributed to the SJES-enabled higher molecular orientation and contents of the secondary structure (α-helix and β-pleated sheet), as well as the high degree of fiber alignment. Moreover, biological tests verified that these SF-based fibrous scaffolds supported the induced pluripotent stem cell derived mesenchymal stem cells to adhere, migrate and grow in a manner of orienting along the fiber axis. We speculate that these high-performance biomimicking SF fibers might give rise to improved efficacy while being utilized to architecturally regenerate anisotropic load-bearing tissues (e.g., tendon, ligament, and blood vessel).

  • Fabrication of high performance silk fibroin fibers via Stable Jet electrospinning for potential use in anisotropic tissue regeneration.
    Journal of materials chemistry. B, 2018
    Co-Authors: Huilan Zhang, Huihua Yuan, Xianliu Wang, Yanzhong Zhang
    Abstract:

    Regenerated silk fibroin (SF) from Bombyx mori silkworm cocoons is a highly regarded natural protein-biomaterial suitable for engineering a variety of biological tissues. Electrospinning offers a unique approach to fiber formation that can readily produce micro- and nano-scale fibers recapitulating the ultrastructure of a native extracellular matrix. However, SF fibers from conventional electrospinning suffer from the problem of poor mechanical properties for load-bearing relevant tissue regeneration applications. In this study, highly aligned high-strength SF fibers were fabricated by a recently emerged Stable Jet electrospinning (SJES) approach, with the aid of high molecular weight poly(ethylene oxide) (PEO) acting as a fiber-forming ingredient to increase control over the Jetting instability during electrospinning. The results showed that 90% of the collected SF/PEO (mass ratio 88 : 12) fiber assembly via SJES oriented unidirectionally with an angle variation of

  • Direct printing of patterned three-dimensional ultrafine fibrous scaffolds by Stable Jet electrospinning for cellular ingrowth.
    Biofabrication, 2015
    Co-Authors: Huihua Yuan, Qihui Zhou, Min Bao, Xiangxin Lou, Yanzhong Zhang
    Abstract:

    Electrospinning has been widely used to produce ultrafine fibers in microscale and nanoscale; however, traditional electrospinning processes are currently beset by troublesome limitations in fabrication of 3D periodic porous structures because of the chaotic nature of the electrospinning Jet. Here we report a novel strategy to print 3D poly(L-lactic acid) (PLLA) ultrafine fibrous scaffolds with the fiber diameter of approximately 2 μm by combining a Stable Jet electrospinning method and an X-Y stage technique. Our approach allows linearly deposited electrospun ultrafine fibers to assemble into 3D structures with tunable pore sizes and desired patterns. Process conditions (e.g., plotting speed, feeding rate, and collecting distance) were investigated in order to achieve Stable Jet printing of ultrafine PLLA fibers. The proposed 3D scaffold was successfully used for cell penetration and growth, demonstrating great potential for tissue engineering applications.

  • Implication of Stable Jet length in electrospinning for collecting well-aligned ultrafine PLLA fibers
    Polymer, 2013
    Co-Authors: Qihui Zhou, Huihua Yuan, Shifang Zhao, Min Bao, Wen Dong, Yanzhong Zhang
    Abstract:

    Abstract Stable Jet based electrospinning (SJES) has recently emerged as a straight-forward approach for the continuous fabrication of well-aligned ultrafine fibers and fiber assemblies. This article reports on the influences of some pivotal solution parameters including solvent, polymer molecular weight, and concentration on the formation of a Stable Jet length (SJL) in electrospinning of a biodegradable polymer, poly( l -lactide acid) (PLLA). Our results reveal that enhanced critical SJL can be achieved at lower solvent dielectric constant and higher viscoelasticity of solutions contributed by the molecular weight and concentration, beneficial for achieving higher degree of fiber alignment. Moreover, hierarchical orderliness including the macroscopic fiber alignment, the elongation along the fiber direction of microscopic pores on the fiber surface and the molecular orientation within the electrospun PLLA fibers, can be modulated by the SJL. The molecular orientation and crystallinity of the aligned PLLA fibers from SJES increased with increasing the SJLs. Also, the measured tensile properties data suggest a positive trend associated with the SJL. This study thus allows establishing a solid correlation of SJL with respect to the macroscopic alignment, internal molecular structural development, and mechanical performance of the electrospun ultrafine PLLA fibers pertaining to the SJES.

Harold H. Schobert - One of the best experts on this subject based on the ideXlab platform.

  • Direct liquefaction for production of high yields of feedstocks for specialty chemicals or thermally Stable Jet fuels
    Fuel Processing Technology, 2000
    Co-Authors: Caroline E. Burgess, Harold H. Schobert
    Abstract:

    Abstract This work was done to test the proposition that it is possible to produce high yields of two-ring compounds via direct liquefaction by selecting appropriate coal feedstock, catalyst, and reaction conditions. These products are valuable as starting materials for monomers of engineering plastics, for other specialty chemicals, and as constituents of a Jet fuel having a high stability toward pyrolytic decomposition. An initial suite of eight coals was reduced to four candidates, based on reactivity in catalytic and non-catalytic liquefaction and on previously published structural characterization data. Further testing reduced the four candidates to two, Blind Canyon (Utah) highly volatile C and Pittsburgh No. 8 highly volatile A bituminous coals. The Pittsburgh seam coal is particularly attractive as a feedstock for this process. Liquefaction with a dispersed, sulfided molybdenum catalyst, followed by caustic washing to remove by-product phenols, provides ≈50% of yield of light liquid rich in two-ring compounds. Subsequent hydrotreating of a blended mixture of model compounds simulating the composition of the liquefaction product produces a material of exceptionally high stability in thermal stressing experiments. This liquid could be converted to a thermally Stable Jet fuel with further hydrotreating and use of appropriate additive packages.

  • Advanced Thermally Stable Jet Fuels
    1999
    Co-Authors: Harold H. Schobert
    Abstract:

    The Penn State program in advanced thermally Stable Jet fuels has five components: 1) development of mechanisms of degradation and solids formation; 2) quantitative measurement of growth of sub-micrometer and micrometer-sized particles during thermal stressing; 3) characterization of carbonaceous deposits by various instrumental and microscopic methods; 4) elucidation of the role of additives in retarding the formation of carbonaceous solids; and 5) assessment of the potential of producing high yields of cycloalkanes and hydroaromatics from coal.

  • Advanced thermally Stable Jet fuels. Technical progress report, April 1996--June 1996
    1996
    Co-Authors: Harold H. Schobert, S. Eser, C. Song
    Abstract:

    The Penn State program in advanced thermally Stable Jet fuels has five components: (1) development of mechanisms of degradation and solids formation: (2) quantitative measurement of growth of sub-micrometer and micrometer-sized particles during thermal stressing; (3) characterization of carbonaceous deposits by various instrumental and microscopic methods: (4) elucidation of the role of additives in retarding the formation of carbonaceous solids; and (5) assessment of the potential of producing high yields of cycloalkanes and hydroaromatics from coal.

  • Advanced thermally Stable Jet fuels. Technical progress report, January 1996--March 1996
    1996
    Co-Authors: Harold H. Schobert, Semih Eser, Chunshan Song
    Abstract:

    A reactive structure index was developed to correlate the molecular structures of saturated hydrocarbons with their reactivities using a linear group contribution method. The index is composed of several sub-indices determined from the structure, including carbon group indices, ring index, and conformation index. The effects on decomposition of ring structure, side-chain length, steric isomers, and branching were examined. Good correlations were obtained for two sets of saturated hydrocarbons. The reactivity of alkanes and cycloalkanes increases with increasing chain or side-chain length. Cycloalkanes are desirable components of advanced Jet fuels, in terms of having higher thermal stability and density than n-alkanes of the same carbon number. The cis-isomer is usually more reactive than the trans-isomer, except for cis-1,3-dimethylcyclohexane. which is more Stable than its trans-isomer. The presence of a branch or branches appears to decrease the decomposition rate compared to n-alkanes.

  • Advanced thermally Stable Jet fuels. Technical progress report, 1995
    1996
    Co-Authors: Harold H. Schobert, S. Eser, C. Song
    Abstract:

    The Penn State program in advanced thermally Stable Jet fuels has five components:(1) development of mechanisms of degradation and solids formation; (2) quantitative measurement of growth of sub- micrometer and micrometer sized particles suspended in fuels during thermal stressing; (3) characterization of carbonaceous deposits by various instrumental and microscopic methods; (4) elucidation of the role of additives in retarding the formation of carbonaceous solids; and (5) assessment of the potential of producing high yields of cycloalkanes and hydroaromatics by direct liquefaction of coal. Progress reports for these tasks are presented.

Huihua Yuan - One of the best experts on this subject based on the ideXlab platform.

  • fabrication of high performance silk fibroin fibers via Stable Jet electrospinning for potential use in anisotropic tissue regeneration
    Journal of Materials Chemistry B, 2018
    Co-Authors: Huilan Zhang, Huihua Yuan, Xianliu Wang, Yanzhong Zhang
    Abstract:

    Regenerated silk fibroin (SF) from Bombyx mori silkworm cocoons is a highly regarded natural protein-biomaterial suitable for engineering a variety of biological tissues. Electrospinning offers a unique approach to fiber formation that can readily produce micro- and nano-scale fibers recapitulating the ultrastructure of a native extracellular matrix. However, SF fibers from conventional electrospinning suffer from the problem of poor mechanical properties for load-bearing relevant tissue regeneration applications. In this study, highly aligned high-strength SF fibers were fabricated by a recently emerged Stable Jet electrospinning (SJES) approach, with the aid of high molecular weight poly(ethylene oxide) (PEO) acting as a fiber-forming ingredient to increase control over the Jetting instability during electrospinning. The results showed that 90% of the collected SF/PEO (mass ratio 88 : 12) fiber assembly via SJES oriented unidirectionally with an angle variation of <1° and displayed obvious anisotropic wettability. Mechanically, the as-electrospun highly aligned SF/PEO fibers exhibited a 22.0-fold increase in ultimate tensile strength (50.85 ± 1.13 MPa) and a 49.3-fold increase in Young's modulus (1185.99 ± 164.56 MPa) compared with the randomly oriented SF fibers. A subsequent methanol treatment further remarkably boosted the tensile strength to 73.91 ± 5.15 MPa and Young's modulus to 2426.13 ± 86.67 MPa. The mechanical performance of the SF fibers via SJES was also impressive, even when tested in the wet state. The substantial improvement in the mechanical properties of the electrospun SF fibers is attributed to the SJES-enabled higher molecular orientation and contents of the secondary structure (α-helix and β-pleated sheet), as well as the high degree of fiber alignment. Moreover, biological tests verified that these SF-based fibrous scaffolds supported the induced pluripotent stem cell derived mesenchymal stem cells to adhere, migrate and grow in a manner of orienting along the fiber axis. We speculate that these high-performance biomimicking SF fibers might give rise to improved efficacy while being utilized to architecturally regenerate anisotropic load-bearing tissues (e.g., tendon, ligament, and blood vessel).

  • Fabrication of high performance silk fibroin fibers via Stable Jet electrospinning for potential use in anisotropic tissue regeneration.
    Journal of materials chemistry. B, 2018
    Co-Authors: Huilan Zhang, Huihua Yuan, Xianliu Wang, Yanzhong Zhang
    Abstract:

    Regenerated silk fibroin (SF) from Bombyx mori silkworm cocoons is a highly regarded natural protein-biomaterial suitable for engineering a variety of biological tissues. Electrospinning offers a unique approach to fiber formation that can readily produce micro- and nano-scale fibers recapitulating the ultrastructure of a native extracellular matrix. However, SF fibers from conventional electrospinning suffer from the problem of poor mechanical properties for load-bearing relevant tissue regeneration applications. In this study, highly aligned high-strength SF fibers were fabricated by a recently emerged Stable Jet electrospinning (SJES) approach, with the aid of high molecular weight poly(ethylene oxide) (PEO) acting as a fiber-forming ingredient to increase control over the Jetting instability during electrospinning. The results showed that 90% of the collected SF/PEO (mass ratio 88 : 12) fiber assembly via SJES oriented unidirectionally with an angle variation of

  • an epigenetic bioactive composite scaffold with well aligned nanofibers for functional tendon tissue engineering
    Acta Biomaterialia, 2018
    Co-Authors: Huihua Yuan, Huilan Zhang, Xianliu Wang, Can Zhang, Erchen Zhang, Long Yang, Wenjing Tu, Weiliang Shen, Xiao Chen
    Abstract:

    Abstract Poor tendon repair is often a clinical challenge due to the lack of ideal biomaterials. Electrospun aligned fibers, resembling the ultrastructure of tendon, have been previously reported to promote tenogenesis. However, the underlying mechanism is unclear and the aligned fibers alone are not capable enough to commit teno-differentiation of stem cells. Here, based on our observation of reduced expression of histone deacetylases (HDACs) in tendon stem/progenitor cells (TSPCs) cultured on aligned fibers, we proposed a strategy to enhance the tenogenesis effect of aligned fibers by using a small molecule Trichostatin A (TSA), an HDAC inhibitor. Such a TSA-laden poly ( l -lactic acid) (PLLA) aligned fiber (A-TSA) scaffold was successfully fabricated by a Stable Jet electrospinning method, and demonstrated its sustained capability in releasing TSA. We found that TSA incorporated aligned fibers of PLLA had an additive effect in directing tenogenic differentiation. Moreover, the in situ implantation study in rat model further confirmed that A-TSA scaffold promoted the structural and mechanical properties of the regenerated Achilles tendon. This study demonstrated that HDAC was involved in the teno-differentiation with aligned fiber topography, and the combination of HDAC with aligned topography might be a more efficient strategy to promote tenogenesis of stem cells. Statement of Significance Electrospun aligned fibers, resembling the ultrastructure of tendon, have been previously reported to promote tenogenesis. However, the underlying mechanism is unclear and the aligned fibers alone are not capable enough to commit teno-differentiation of stem cells. The uniqueness of our studies are as follows, based on our observation of reduced expression of histone deacetylases (HDACs) in tendon stem/progenitor cells (TSPCs) cultured on aligned fibers, we proposed a strategy to enhance the tenogenesis effect of aligned fibers by using a small molecule Trichostatin A (TSA), a HDAC inhibitor. Such a TSA-laden poly ( l -lactic acid) (PLLA) aligned fiber (A-TSA) scaffold was successfully fabricated by a Stable Jet electrospinning method, and demonstrated its sustained capability in releasing TSA. The incorporation and subsequent release of bioactive small molecule TSA into electrospun aligned fibers allows a controllable manner for both biochemical and physical regulation of tenogenesis of stem cells both in vitro and in vivo. Collectively, the present study provides a model of “translating the biological knowledge learned from cell-material interaction into optimizing biomaterials (from Biomat-to-Biomat)”.

  • Direct printing of patterned three-dimensional ultrafine fibrous scaffolds by Stable Jet electrospinning for cellular ingrowth.
    Biofabrication, 2015
    Co-Authors: Huihua Yuan, Qihui Zhou, Min Bao, Xiangxin Lou, Yanzhong Zhang
    Abstract:

    Electrospinning has been widely used to produce ultrafine fibers in microscale and nanoscale; however, traditional electrospinning processes are currently beset by troublesome limitations in fabrication of 3D periodic porous structures because of the chaotic nature of the electrospinning Jet. Here we report a novel strategy to print 3D poly(L-lactic acid) (PLLA) ultrafine fibrous scaffolds with the fiber diameter of approximately 2 μm by combining a Stable Jet electrospinning method and an X-Y stage technique. Our approach allows linearly deposited electrospun ultrafine fibers to assemble into 3D structures with tunable pore sizes and desired patterns. Process conditions (e.g., plotting speed, feeding rate, and collecting distance) were investigated in order to achieve Stable Jet printing of ultrafine PLLA fibers. The proposed 3D scaffold was successfully used for cell penetration and growth, demonstrating great potential for tissue engineering applications.

  • Implication of Stable Jet length in electrospinning for collecting well-aligned ultrafine PLLA fibers
    Polymer, 2013
    Co-Authors: Qihui Zhou, Huihua Yuan, Shifang Zhao, Min Bao, Wen Dong, Yanzhong Zhang
    Abstract:

    Abstract Stable Jet based electrospinning (SJES) has recently emerged as a straight-forward approach for the continuous fabrication of well-aligned ultrafine fibers and fiber assemblies. This article reports on the influences of some pivotal solution parameters including solvent, polymer molecular weight, and concentration on the formation of a Stable Jet length (SJL) in electrospinning of a biodegradable polymer, poly( l -lactide acid) (PLLA). Our results reveal that enhanced critical SJL can be achieved at lower solvent dielectric constant and higher viscoelasticity of solutions contributed by the molecular weight and concentration, beneficial for achieving higher degree of fiber alignment. Moreover, hierarchical orderliness including the macroscopic fiber alignment, the elongation along the fiber direction of microscopic pores on the fiber surface and the molecular orientation within the electrospun PLLA fibers, can be modulated by the SJL. The molecular orientation and crystallinity of the aligned PLLA fibers from SJES increased with increasing the SJLs. Also, the measured tensile properties data suggest a positive trend associated with the SJL. This study thus allows establishing a solid correlation of SJL with respect to the macroscopic alignment, internal molecular structural development, and mechanical performance of the electrospun ultrafine PLLA fibers pertaining to the SJES.

C. Song - One of the best experts on this subject based on the ideXlab platform.

  • Advanced thermally Stable Jet fuels. Technical progress report, April 1996--June 1996
    1996
    Co-Authors: Harold H. Schobert, S. Eser, C. Song
    Abstract:

    The Penn State program in advanced thermally Stable Jet fuels has five components: (1) development of mechanisms of degradation and solids formation: (2) quantitative measurement of growth of sub-micrometer and micrometer-sized particles during thermal stressing; (3) characterization of carbonaceous deposits by various instrumental and microscopic methods: (4) elucidation of the role of additives in retarding the formation of carbonaceous solids; and (5) assessment of the potential of producing high yields of cycloalkanes and hydroaromatics from coal.

  • Advanced thermally Stable Jet fuels. Technical progress report, 1995
    1996
    Co-Authors: Harold H. Schobert, S. Eser, C. Song
    Abstract:

    The Penn State program in advanced thermally Stable Jet fuels has five components:(1) development of mechanisms of degradation and solids formation; (2) quantitative measurement of growth of sub- micrometer and micrometer sized particles suspended in fuels during thermal stressing; (3) characterization of carbonaceous deposits by various instrumental and microscopic methods; (4) elucidation of the role of additives in retarding the formation of carbonaceous solids; and (5) assessment of the potential of producing high yields of cycloalkanes and hydroaromatics by direct liquefaction of coal. Progress reports for these tasks are presented.

  • Advanced thermally Stable Jet fuels. Technical progress report, July 1995--September 1995
    1995
    Co-Authors: Harold H. Schobert, S. Eser, C. Song
    Abstract:

    The Penn State program in advanced thermally Stable Jet engine fuels has five components: development of mechanisms of degradation and solids formation; quantitative measurement of growth of sub-micrometer-sized and micrometer particles suspended in fuels during thermal stresses; characterization of carbonaceous deposits by various instrumental and microscopic methods; elucidation of the role of additives in retarding the formation of carbonaceous solids; and assessment of the potential of producing high yields of cycloalkanes and hydroaromatics by direct coal liquefaction. Progress is described.

  • Advanced thermally Stable Jet fuels. Technical progress report, January 1995--March 1995
    1995
    Co-Authors: Harold H. Schobert, S. Eser, C. Song
    Abstract:

    Quantitative structure-property relationships have been applied to study the thermal stability of pure hydrocarbons typical of Jet fuel components. A simple method of chemical structure description in terms of Benson groups was tested in searching for structure-property relationships for the hydrocarbons tested experimentally in this program. Molecular connectivity as a structure-based approach to chemical structure-property relationship analysis was also tested. Further development of both the experimental data base and computational methods will be necessary. Thermal decomposition studies, using glass tube reactors, were extended to two additional model compounds: n-decane and n-dodecane. Efforts on refining the deposit growth measurement and characterization of suspended matter in stressed fuels have lead to improvements in the analysis of stressed fuels. Catalytic hydrogenation and dehydrogenation studies utilizing a molybdenum sulfide catalyst are also described.

  • Advanced thermally Stable Jet fuels: Technical progress report, July 1994--September 1994
    1994
    Co-Authors: Harold H. Schobert, André L. Boehman, S. Eser, C. Song, P.g. Hatcher, M.m. Coleman
    Abstract:

    There are five tasks within this project on thermally Stable coal-based Jet fuels. Progress on each of the tasks is described. Task 1, Investigation of the quantitative degradation chemistry of fuels, has 3 subtasks which are described: Pyrolysis of n-alkylbenzenes; Thermal decomposition of n-tetradecane in near-critical region; and Re-examining the effects of reactant and inert gas pressure on tetradecane pyrolysis--Effect of cold volume in batch reactor. Under Task 2, Investigation of incipient deposition, the subtask reported is Uncertainty analysis on growth and deposition of particles during heating of coal-derived aviation gas turbine fuels; under Task 3, Investigation of the quantitative degradation chemistry of fuels, is subtask, Effects of high surface area activated carbon and decalin on thermal degradation of Jet A-1 fuel and n-dodecane; under Task 4, Coal-based fuel stabilization studies, is subtask, Screening potential Jet fuel stabilizers using the model compound dodecane; and under Task 5, Exploratory studies on the direct conversion of coal to high quality Jet fuels, is subtask, Shape-selective naphthalene hydrogenation for production of thermally Stable Jet fuels. 25 refs., 64 figs., 22 tabs.

Sylvester Abanteriba - One of the best experts on this subject based on the ideXlab platform.