Microstructure of SiC fiber manufactured by chemical vapor deposition （CVD） onto tungsten （W） wire core was investigated by analytical electron microscopy （AEM）. The results reveal that the fiber consists of W c...Microstructure of SiC fiber manufactured by chemical vapor deposition （CVD） onto tungsten （W） wire core was investigated by analytical electron microscopy （AEM）. The results reveal that the fiber consists of W core, SiC sheath and C-coating. SiC sheath could be subdivided into two parts according to whether containing C rich stripe, or not. An emphasis was put on W/SiC interfacial reaction products and the transition zone between sub-layers in SiC sheath. The W/SiC interface consists of three layers of reaction production, namely, W2C, W5Si3 and WC. And there are amounts of facet faults existing in （100） face of WC crystalline and two classes of stack faults in WC have been revealed. The formation essence of different sublayers in SiC sheath was also discussed.展开更多
A new polymer named polyferrocarbosilane(PFCS) was prepared from polydimethylsilane and ferrocene. The spinnability of this polymer can be tailored by controlling the content of ferrocene in the polymer. The prepared ...A new polymer named polyferrocarbosilane(PFCS) was prepared from polydimethylsilane and ferrocene. The spinnability of this polymer can be tailored by controlling the content of ferrocene in the polymer. The prepared polymer was spun into a continuous polymer fiber that was subsequently cured in air and heat-treated finally in N2 up to 1 350 ℃ for conversion into Si-Fe-C-O fibers. The resulted Si-Fe-C-O fibers display low specific resistance and magnetic property due to the existence of Fe, which also reduces the specific resistance significantly to 10-2Ω·cm at room temperature when the amount of ferrocene in feed is as low as 3.0% (mass fraction). The resulted Si-Fe-C-O fibers, with C/Si molar ratio of about 1.3 and the maximum Fe content of about 2.0% (mole fraction), are composed of β-SiC and small amount of Fe3Si-like crystalline and have an average tensile strength of about 2.0 GPa.展开更多
Carbide ceramic fibers are of significant importance for application in the high-tech areas of advanced aircraft engines,aerospace vehicles,and the nuclear industry due to their excellent properties,such as high tensi...Carbide ceramic fibers are of significant importance for application in the high-tech areas of advanced aircraft engines,aerospace vehicles,and the nuclear industry due to their excellent properties,such as high tensile strength and elastic modulus,excellent high-temperature resistance,and oxidation resistance.This paper reviews the preparation and application of different carbide ceramic fibers,including SiC fibers and transition metal carbide(e.g.,ZrC,HfC,and TaC)ceramic fibers.The preparation methods of carbide ceramic fibers are discussed in terms of different fiber diameters,represented by SiC fibers with variable weaving properties and functions due to their differences in diameter.Subsequently,the application of carbide ceramic fibers as high-temperature-resistant structural materials,catalyst carriers,sensors,and supercapacitors are summarized,and strategies for the future development of carbide ceramic fibers are proposed.This review aims to help researchers enhance their understanding of the preparation and utilization of carbide ceramic micro/nanofibers,advancing the development of high-performance carbide ceramic fibers.展开更多
Long-term potentiation(LTP) of C-fiber evoked field potentials in spinal dorsal horn is first reported in 1995.Since then,the mechanisms underlying the long-lasting enhancement in synaptic transmission between primary...Long-term potentiation(LTP) of C-fiber evoked field potentials in spinal dorsal horn is first reported in 1995.Since then,the mechanisms underlying the long-lasting enhancement in synaptic transmission between primary afferent C-fibers and neurons in spinal dorsal horn have been investigated by different laboratories.In this article,the related data were summarized and discussed.展开更多
Using polymer-derived technology, continuous high-temperature resistant Si-Al-C fibers were prepared by one step method, which included melt-spinning of polyaluminocarbosilane (PACS), curing of continuous PACS fibers,...Using polymer-derived technology, continuous high-temperature resistant Si-Al-C fibers were prepared by one step method, which included melt-spinning of polyaluminocarbosilane (PACS), curing of continuous PACS fibers, and sintering of the cured products. The results show that the average diameter and tensile strength of continuous Si-Al-C fibers are 11 to 12 μm and 1.8 to 2.0 GPa, respectively. The chemical formula of Si-Al-C fibers is SiC1.01O0.0400Al0.024, which is nearly stoichometric. The fibers are mainly composed of β-SiC crystalline, small amount of α-SiC, and amorphous SiC. Continuous Si-Al-C fibers exhibit excellent thermal stability. When the fibers were exposed in argon for 1 h, the tensile strength did not decrease until 1500°C. After heat treatment at 1800°C in argon for 1 h, the fibers maintained about 80% of the initial strength. It was higher than that of Nicalon and Hi-Nicalon fibers.展开更多
The evolvement of oxygen from polyaluminocarbosilane(PACS) to Si-Al-C-(O) fibers and its effect on properties were investigated by element analysis, solid-state 27Al nuclear magnetic resonance(NMR), Fourier transform ...The evolvement of oxygen from polyaluminocarbosilane(PACS) to Si-Al-C-(O) fibers and its effect on properties were investigated by element analysis, solid-state 27Al nuclear magnetic resonance(NMR), Fourier transform infrared spectroscopy(FT-IR), thermo-gravimetric analyses(TGA), scanning electron microscope(SEM) and X-ray diffraction(XRD). Element analysis of PACS precursor polymer gives an empirical formula of SiC2.1H11.1O0.12Al0.024. 27Al NMR spectra mass gain shows that the oxygen of cured PACS fibers comes from aluminum aletylacetanate (Al(AcAc)3) and the curing process. Oxygen content can be regarded as a constant mass during the pyrolysis process. During the sintering process of Si-Al-C-O fibers into Si-Al-C fibers, oxygen and carbon decreases with the release of a small amount of CO and/or SiO. Oxygen has a positive effect on the ceramic yield while has a negative effect on the crystallization of Si-Al-C-O fibers. It has great influence on mechanical properties of Si-Al-C-O and excellent tensile strength is usually obtained at the oxygen content of 8%-10%. The Si-Al-C-(O) fibers have excellent thermal stability and creep resistance.展开更多
The animal experiment of viscose carbon fiber based C/C composites applied in bone defection intramedullary fixation was carried out in New Zealand white rabbits.The histological observation on the 100th day after sur...The animal experiment of viscose carbon fiber based C/C composites applied in bone defection intramedullary fixation was carried out in New Zealand white rabbits.The histological observation on the 100th day after surgical operation indicated that the experimental animals recovered well and the bone defect area was reconstructed by new bone trabecula.Immunohistochemical observation of leukocyte common antigen and macrophage suggested that intramedullary fixation materials did not induct any chronic toxicity reactions such as inflammatory reactions,macrophage reactions and formation of granulation tissue.The tissue compatibility of this material was excellent.Meanwhile,the impurity element species and the biological toxic element content of viscose fiber based C/C composites were determined by atomic fluorescence analyzer and inductively coupled plasma atomic emission spectrometry.The results reveal that there are few biological toxic elements in the viscose fiber based C/C composites and it can satisfy the constituent demands of surgical implants.展开更多
Quantitative assessment of the recovery of nerve function, especially sensory and autonomic nerve function, remains a challenge in the field of nerve regeneration research. We previously found that neural control of v...Quantitative assessment of the recovery of nerve function, especially sensory and autonomic nerve function, remains a challenge in the field of nerve regeneration research. We previously found that neural control of vasomotor activity could be potentially harnessed to evaluate nerve function. In the present study, five different models of left sciatic nerve injury in rats were established: nerve crush injury, nerve transection/ suturing, nerve defect/autografting, nerve defect/conduit repair, and nerve defect/non-regeneration. Laser Doppler perfusion imaging was used to analyze blood perfusion of the hind feet. The toe pinch test and walking track analysis were used to assess sensory and motor functions of the rat hind limb, respectively. Transmission electron microscopy was used to observe the density of unmyelinated axons in the injured sciatic nerve. Our results showed that axonotmesis-evoked vasodilatation in the foot 6 months after nerve injury/repair recovered to normal levels in the nerve crush injury group and partially in the other three repair groups;whereas the nerve defect/non-regeneration group exhibited no recovery in vasodilatation. Furthermore, the recovery index of axonotmesis-evoked vasodilatation was positively correlated with toe pinch reflex scores and the density of unmyelinated nerve fibers in the regenerated nerve. As C-fiber afferents are predominantly responsible for dilatation of the superficial vasculature in the glabrous skin in rats, the present findings indicate that axonotmesis-evoked vasodilatation can be used as a novel way to assess C-afferent function recovery after peripheral nerve injury. This study was approved by the Ethics Committee for Laboratory Animals of Nantong University of China (approval No. 20130410-006) on April 10, 2013.展开更多
Defects of polymer-derived Si-C-O fibers were intensively studied by the SEM and TEM techniques and their originations were also discussed on the basis of factors experiments.The defects were found mainly in the form ...Defects of polymer-derived Si-C-O fibers were intensively studied by the SEM and TEM techniques and their originations were also discussed on the basis of factors experiments.The defects were found mainly in the form of strumaes,pits and splits on surfaces as well as microflaw networks,porosity clusters and inclusions in the bulk.Factors experiments reveal that a nonuniform or an insufficient curing would result in larger-sized strumaes or interior microflaws.Gas evolution rates due to different firing rates have a great influence on the formation of internal microflaws or porosity clusters and some oxidation-induced pits or splits may be formed on surfaces because of a trace of oxygen or water vapor accumulated from the flowing inert atmosphere during pyrolysis.展开更多
C f/SiC composites were prepared by precursor pyrolysis hot pressing, and the effect of fiber characteristics on the fracture behavior of the composites was investigated. Because the heat treatment temperature of fibe...C f/SiC composites were prepared by precursor pyrolysis hot pressing, and the effect of fiber characteristics on the fracture behavior of the composites was investigated. Because the heat treatment temperature of fiber T300 (below 1?500?℃) was much lower than that of fiber M40JB (over 2?000?℃), fiber T300 had lower degree of graphitization and consisted of more impurities compared with fiber M40JB, suggesting that T300 exhibits higher chemical activity. As a result, the composite with T300 showed a brittle fracture behavior, which is mainly ascribed to a strongly bonded fiber/matrix interface as well as the degradation of fibers during the preparation of the composite. However, the composite with M40JB exhibits a tough fracture behavior, which is primarily attributed to a weakly bonded fiber/matrix interface and higher strength retention of the fibers.展开更多
In-situ magnesia-rich spinel fiber was formed resulting from the addition of ferrocene into MgO-C refractory matrixes. The formation of in-situ spinel fiber was detected to start at 1300 ℃. The amount, diameter and l...In-situ magnesia-rich spinel fiber was formed resulting from the addition of ferrocene into MgO-C refractory matrixes. The formation of in-situ spinel fiber was detected to start at 1300 ℃. The amount, diameter and length of the fibers increased with rising temperature. Ferrocene may have catalytic effects on the growth of the fibers in two aspects. First, the reaction between MgO and C and the decomposition of Al4C3 may be catalyzed at high temperature. Suitable concentration gaseous phase is then created for vapor-vapor reaction which could result in the in-situ formation of fibers. Second, Fe nanoparticle produced from ferrocene can act as catalytic droplets and catalyze the growth of the fibers. The fibers are formed via the vapor-liquid-solid and vapor-solid mechanisms. In terms of chemical thermodynamics, the partial pressure of CO and Mg（g） are found to play an important role in the in-situ fibers formation. Different concentration of vapors affects the size, amount and composition of the fibers at different temperatures. The mechanical properties of MgO-C brick was found to be improved by ferrocene addition.展开更多
Micrometer NbC_x-C three-dimensional netted fibers were synthesized by thecarbothermal method under 0.1 MPa of N_2 ambient atmosphere at a relatively low temperature. Rawmaterials were commercial powders of Nb_2O_5 (9...Micrometer NbC_x-C three-dimensional netted fibers were synthesized by thecarbothermal method under 0.1 MPa of N_2 ambient atmosphere at a relatively low temperature. Rawmaterials were commercial powders of Nb_2O_5 (99.95 percent), reactive carbon (99.99 percent), NaCl(99.95 percent) and sucrose (99.94 percent). The relationship of the fabrication processing with thecomposition, crystal structure and morphology of fibers was investigated. The formation mechanismwas also proposed and discussed.展开更多
The objective of this research was to determine the physicochemical characteristics of fiber residues from Jack bean (Canavalia ensiformis L.) obtained by two technological processes. The proximal composition of the f...The objective of this research was to determine the physicochemical characteristics of fiber residues from Jack bean (Canavalia ensiformis L.) obtained by two technological processes. The proximal composition of the fiber residues from Canavalia ensiformis registered values of moisture, ash, protein, fat, fiber and nitrogen-free extract (NFE) of 7.14%, 3.17%, 9.14%, 1.34%, ?23.84% and 62.51% for residue A and 4.74%, 2.68%, 7.73%, 1.39%, 23.76% and 64.44% for residue B. Total dietary fiber (TDF) contents in the fiber residues were 47.06 (Residue A) and 54.96 (Residue B) g/100g sample, with most of this content represented by insoluble dietary fiber (IDF) 45.46 g/100g sample in Residue A and 52.75 g/100g of sample in Residue B. The remainder was constituted by soluble dietary fiber (SDF). The neutral detergent fiber (NDF) content was slightly higher in residue B (41.8 g/100g sample). Acid detergent fiber (ADF) that includes principally cellulose, lignin and cutin, and acid detergent lignin (ADL) that include lignin and cutin were higher in residue B (32.5 g/100g sample) and similar for both residues (1.0 (A) and 1.2 (B) g/100g sample), respectively. Resistant starch (RS) was higher in residue B (0.607%) than in residue A (0.358%). No statistical difference (p > 0.05) was registered in the tannins content of both residues. However, the phytates content was higher in the fiber residue obtained by the fists technological process (A residue). In vitro digestibility was higher in residue A (85.81%) than that in B residue (81.51%). The results of the present study suggest the potential use of C. ensiformis fiber residues as a functional ingredient in foods, especially in the development of reduced calorie food and dietary fiber enriched foods.展开更多
The morphological structure of various epoxies toughened with a special amorphous thermoplastic PEK-C and their carbon fiber composites were studied by using SEM. For both cases, phase separation and inversion took pl...The morphological structure of various epoxies toughened with a special amorphous thermoplastic PEK-C and their carbon fiber composites were studied by using SEM. For both cases, phase separation and inversion took place to form fine epoxy-rich globules dispersing in the PEK-C matrix, in which the epoxy-rich phase had the absolutely higher volume fraction. The phase structure and the interfacial properties were also studied by means of FTIR, DSC, and DMTA as well. An accompanying mechanical determination revealed that an improved toughness was achieved both in the blend casts and in the carbon fiber composites. A composite structural model was hence suggested.展开更多
文摘Microstructure of SiC fiber manufactured by chemical vapor deposition （CVD） onto tungsten （W） wire core was investigated by analytical electron microscopy （AEM）. The results reveal that the fiber consists of W core, SiC sheath and C-coating. SiC sheath could be subdivided into two parts according to whether containing C rich stripe, or not. An emphasis was put on W/SiC interfacial reaction products and the transition zone between sub-layers in SiC sheath. The W/SiC interface consists of three layers of reaction production, namely, W2C, W5Si3 and WC. And there are amounts of facet faults existing in （100） face of WC crystalline and two classes of stack faults in WC have been revealed. The formation essence of different sublayers in SiC sheath was also discussed.
文摘A new polymer named polyferrocarbosilane(PFCS) was prepared from polydimethylsilane and ferrocene. The spinnability of this polymer can be tailored by controlling the content of ferrocene in the polymer. The prepared polymer was spun into a continuous polymer fiber that was subsequently cured in air and heat-treated finally in N2 up to 1 350 ℃ for conversion into Si-Fe-C-O fibers. The resulted Si-Fe-C-O fibers display low specific resistance and magnetic property due to the existence of Fe, which also reduces the specific resistance significantly to 10-2Ω·cm at room temperature when the amount of ferrocene in feed is as low as 3.0% (mass fraction). The resulted Si-Fe-C-O fibers, with C/Si molar ratio of about 1.3 and the maximum Fe content of about 2.0% (mole fraction), are composed of β-SiC and small amount of Fe3Si-like crystalline and have an average tensile strength of about 2.0 GPa.
基金support from the National Natural Science Foundation of China(No.52272100)the Natural Science Foundation of Hunan Province(No.2022JJ30662)the Science and Technology on Advanced Ceramic Fibers and Composites Laboratory(No.WDZC20215250507).
文摘Carbide ceramic fibers are of significant importance for application in the high-tech areas of advanced aircraft engines,aerospace vehicles,and the nuclear industry due to their excellent properties,such as high tensile strength and elastic modulus,excellent high-temperature resistance,and oxidation resistance.This paper reviews the preparation and application of different carbide ceramic fibers,including SiC fibers and transition metal carbide(e.g.,ZrC,HfC,and TaC)ceramic fibers.The preparation methods of carbide ceramic fibers are discussed in terms of different fiber diameters,represented by SiC fibers with variable weaving properties and functions due to their differences in diameter.Subsequently,the application of carbide ceramic fibers as high-temperature-resistant structural materials,catalyst carriers,sensors,and supercapacitors are summarized,and strategies for the future development of carbide ceramic fibers are proposed.This review aims to help researchers enhance their understanding of the preparation and utilization of carbide ceramic micro/nanofibers,advancing the development of high-performance carbide ceramic fibers.
基金the National Natural Science Foundation of China(No.30200076,30370474,30570599)Department of Science and Technology of Guangdong Province,China(No.2005A30801002)
文摘Long-term potentiation(LTP) of C-fiber evoked field potentials in spinal dorsal horn is first reported in 1995.Since then,the mechanisms underlying the long-lasting enhancement in synaptic transmission between primary afferent C-fibers and neurons in spinal dorsal horn have been investigated by different laboratories.In this article,the related data were summarized and discussed.
基金the National Natural Science Foundation of China (Grant No. 59972042)
文摘Using polymer-derived technology, continuous high-temperature resistant Si-Al-C fibers were prepared by one step method, which included melt-spinning of polyaluminocarbosilane (PACS), curing of continuous PACS fibers, and sintering of the cured products. The results show that the average diameter and tensile strength of continuous Si-Al-C fibers are 11 to 12 μm and 1.8 to 2.0 GPa, respectively. The chemical formula of Si-Al-C fibers is SiC1.01O0.0400Al0.024, which is nearly stoichometric. The fibers are mainly composed of β-SiC crystalline, small amount of α-SiC, and amorphous SiC. Continuous Si-Al-C fibers exhibit excellent thermal stability. When the fibers were exposed in argon for 1 h, the tensile strength did not decrease until 1500°C. After heat treatment at 1800°C in argon for 1 h, the fibers maintained about 80% of the initial strength. It was higher than that of Nicalon and Hi-Nicalon fibers.
基金Project(59972042) supported by the National Natural Science Foundation of China
文摘The evolvement of oxygen from polyaluminocarbosilane(PACS) to Si-Al-C-(O) fibers and its effect on properties were investigated by element analysis, solid-state 27Al nuclear magnetic resonance(NMR), Fourier transform infrared spectroscopy(FT-IR), thermo-gravimetric analyses(TGA), scanning electron microscope(SEM) and X-ray diffraction(XRD). Element analysis of PACS precursor polymer gives an empirical formula of SiC2.1H11.1O0.12Al0.024. 27Al NMR spectra mass gain shows that the oxygen of cured PACS fibers comes from aluminum aletylacetanate (Al(AcAc)3) and the curing process. Oxygen content can be regarded as a constant mass during the pyrolysis process. During the sintering process of Si-Al-C-O fibers into Si-Al-C fibers, oxygen and carbon decreases with the release of a small amount of CO and/or SiO. Oxygen has a positive effect on the ceramic yield while has a negative effect on the crystallization of Si-Al-C-O fibers. It has great influence on mechanical properties of Si-Al-C-O and excellent tensile strength is usually obtained at the oxygen content of 8%-10%. The Si-Al-C-(O) fibers have excellent thermal stability and creep resistance.
基金the Fundamental Research Funds for the Central Universities of China(No.11CX04033A)the Postdoctoral Innovation Projection of Shandong Province(No.201103085)
文摘The animal experiment of viscose carbon fiber based C/C composites applied in bone defection intramedullary fixation was carried out in New Zealand white rabbits.The histological observation on the 100th day after surgical operation indicated that the experimental animals recovered well and the bone defect area was reconstructed by new bone trabecula.Immunohistochemical observation of leukocyte common antigen and macrophage suggested that intramedullary fixation materials did not induct any chronic toxicity reactions such as inflammatory reactions,macrophage reactions and formation of granulation tissue.The tissue compatibility of this material was excellent.Meanwhile,the impurity element species and the biological toxic element content of viscose fiber based C/C composites were determined by atomic fluorescence analyzer and inductively coupled plasma atomic emission spectrometry.The results reveal that there are few biological toxic elements in the viscose fiber based C/C composites and it can satisfy the constituent demands of surgical implants.
基金supported in part by the National Natural Science Foundation of China,No.81100939 and 81773713(to WH),No.81501610(to XC)the Research Project funded by Jiangsu Provincial Government of China,No.BRA2018223(to DGM)+2 种基金the Public Health Center at Jiangnan University of China,No.JUPH201808(to XSW)the Wuxi Commission of Public Health and Family Planning of China,No.MS201717(to XSW)the Project of Academic Development Program by Governments of Jiangsu Province and Nantong City of China(to DGM)
文摘Quantitative assessment of the recovery of nerve function, especially sensory and autonomic nerve function, remains a challenge in the field of nerve regeneration research. We previously found that neural control of vasomotor activity could be potentially harnessed to evaluate nerve function. In the present study, five different models of left sciatic nerve injury in rats were established: nerve crush injury, nerve transection/ suturing, nerve defect/autografting, nerve defect/conduit repair, and nerve defect/non-regeneration. Laser Doppler perfusion imaging was used to analyze blood perfusion of the hind feet. The toe pinch test and walking track analysis were used to assess sensory and motor functions of the rat hind limb, respectively. Transmission electron microscopy was used to observe the density of unmyelinated axons in the injured sciatic nerve. Our results showed that axonotmesis-evoked vasodilatation in the foot 6 months after nerve injury/repair recovered to normal levels in the nerve crush injury group and partially in the other three repair groups;whereas the nerve defect/non-regeneration group exhibited no recovery in vasodilatation. Furthermore, the recovery index of axonotmesis-evoked vasodilatation was positively correlated with toe pinch reflex scores and the density of unmyelinated nerve fibers in the regenerated nerve. As C-fiber afferents are predominantly responsible for dilatation of the superficial vasculature in the glabrous skin in rats, the present findings indicate that axonotmesis-evoked vasodilatation can be used as a novel way to assess C-afferent function recovery after peripheral nerve injury. This study was approved by the Ethics Committee for Laboratory Animals of Nantong University of China (approval No. 20130410-006) on April 10, 2013.
文摘Defects of polymer-derived Si-C-O fibers were intensively studied by the SEM and TEM techniques and their originations were also discussed on the basis of factors experiments.The defects were found mainly in the form of strumaes,pits and splits on surfaces as well as microflaw networks,porosity clusters and inclusions in the bulk.Factors experiments reveal that a nonuniform or an insufficient curing would result in larger-sized strumaes or interior microflaws.Gas evolution rates due to different firing rates have a great influence on the formation of internal microflaws or porosity clusters and some oxidation-induced pits or splits may be formed on surfaces because of a trace of oxygen or water vapor accumulated from the flowing inert atmosphere during pyrolysis.
文摘C f/SiC composites were prepared by precursor pyrolysis hot pressing, and the effect of fiber characteristics on the fracture behavior of the composites was investigated. Because the heat treatment temperature of fiber T300 (below 1?500?℃) was much lower than that of fiber M40JB (over 2?000?℃), fiber T300 had lower degree of graphitization and consisted of more impurities compared with fiber M40JB, suggesting that T300 exhibits higher chemical activity. As a result, the composite with T300 showed a brittle fracture behavior, which is mainly ascribed to a strongly bonded fiber/matrix interface as well as the degradation of fibers during the preparation of the composite. However, the composite with M40JB exhibits a tough fracture behavior, which is primarily attributed to a weakly bonded fiber/matrix interface and higher strength retention of the fibers.
基金Funded by the National Natural Science Foundation of China (No.50872125)
文摘In-situ magnesia-rich spinel fiber was formed resulting from the addition of ferrocene into MgO-C refractory matrixes. The formation of in-situ spinel fiber was detected to start at 1300 ℃. The amount, diameter and length of the fibers increased with rising temperature. Ferrocene may have catalytic effects on the growth of the fibers in two aspects. First, the reaction between MgO and C and the decomposition of Al4C3 may be catalyzed at high temperature. Suitable concentration gaseous phase is then created for vapor-vapor reaction which could result in the in-situ formation of fibers. Second, Fe nanoparticle produced from ferrocene can act as catalytic droplets and catalyze the growth of the fibers. The fibers are formed via the vapor-liquid-solid and vapor-solid mechanisms. In terms of chemical thermodynamics, the partial pressure of CO and Mg（g） are found to play an important role in the in-situ fibers formation. Different concentration of vapors affects the size, amount and composition of the fibers at different temperatures. The mechanical properties of MgO-C brick was found to be improved by ferrocene addition.
基金This work was financially supported by the National Nature Science Foundation of China(No.59425007, No.59432033).
文摘Micrometer NbC_x-C three-dimensional netted fibers were synthesized by thecarbothermal method under 0.1 MPa of N_2 ambient atmosphere at a relatively low temperature. Rawmaterials were commercial powders of Nb_2O_5 (99.95 percent), reactive carbon (99.99 percent), NaCl(99.95 percent) and sucrose (99.94 percent). The relationship of the fabrication processing with thecomposition, crystal structure and morphology of fibers was investigated. The formation mechanismwas also proposed and discussed.
文摘The objective of this research was to determine the physicochemical characteristics of fiber residues from Jack bean (Canavalia ensiformis L.) obtained by two technological processes. The proximal composition of the fiber residues from Canavalia ensiformis registered values of moisture, ash, protein, fat, fiber and nitrogen-free extract (NFE) of 7.14%, 3.17%, 9.14%, 1.34%, ?23.84% and 62.51% for residue A and 4.74%, 2.68%, 7.73%, 1.39%, 23.76% and 64.44% for residue B. Total dietary fiber (TDF) contents in the fiber residues were 47.06 (Residue A) and 54.96 (Residue B) g/100g sample, with most of this content represented by insoluble dietary fiber (IDF) 45.46 g/100g sample in Residue A and 52.75 g/100g of sample in Residue B. The remainder was constituted by soluble dietary fiber (SDF). The neutral detergent fiber (NDF) content was slightly higher in residue B (41.8 g/100g sample). Acid detergent fiber (ADF) that includes principally cellulose, lignin and cutin, and acid detergent lignin (ADL) that include lignin and cutin were higher in residue B (32.5 g/100g sample) and similar for both residues (1.0 (A) and 1.2 (B) g/100g sample), respectively. Resistant starch (RS) was higher in residue B (0.607%) than in residue A (0.358%). No statistical difference (p > 0.05) was registered in the tannins content of both residues. However, the phytates content was higher in the fiber residue obtained by the fists technological process (A residue). In vitro digestibility was higher in residue A (85.81%) than that in B residue (81.51%). The results of the present study suggest the potential use of C. ensiformis fiber residues as a functional ingredient in foods, especially in the development of reduced calorie food and dietary fiber enriched foods.
文摘The morphological structure of various epoxies toughened with a special amorphous thermoplastic PEK-C and their carbon fiber composites were studied by using SEM. For both cases, phase separation and inversion took place to form fine epoxy-rich globules dispersing in the PEK-C matrix, in which the epoxy-rich phase had the absolutely higher volume fraction. The phase structure and the interfacial properties were also studied by means of FTIR, DSC, and DMTA as well. An accompanying mechanical determination revealed that an improved toughness was achieved both in the blend casts and in the carbon fiber composites. A composite structural model was hence suggested.
基金This work was supported by the National Natural Science Foundation of China (No. 30070256 and No.30200076) CMB-SUMSScholarship (No.98-766) and a grant from Health department of Guangdong Province.
