scholarly journals Thermo-Mechanical Behaviour of Human Nasal Cartilage

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 177 ◽  
Author(s):  
Aureliano Fertuzinhos ◽  
Marta A. Teixeira ◽  
Miguel Goncalves Ferreira ◽  
Rui Fernandes ◽  
Rossana Correia ◽  
...  
Keyword(s):  
Mechanical Behaviour ◽  
Subcutaneous Tissue ◽  
Amorphous Region ◽  
Cartilage Matrix ◽  
Water Evaporation ◽  
Glass Transition Point ◽  
Crystalline Region ◽  
Scanning Calorimetry ◽  
Nasal Cartilage ◽  
Human Nose

The aim of this study was to undergo a comprehensive analysis of the thermo-mechanical properties of nasal cartilages for the future design of a composite polymeric material to be used in human nose reconstruction surgery. A thermal and dynamic mechanical analysis (DMA) in tension and compression modes within the ranges 1 to 20 Hz and 30 °C to 250 °C was performed on human nasal cartilage. Differential scanning calorimetry (DSC), as well as characterization of the nasal septum (NS), upper lateral cartilages (ULC), and lower lateral cartilages (LLC) reveals the different nature of the binding water inside the studied specimens. Three peaks at 60–80 °C, 100–130 °C, and 200 °C were attributed to melting of the crystalline region of collagen matrix, water evaporation, and the strongly bound non-interstitial water in the cartilage and composite specimens, respectively. Thermogravimetric analysis (TGA) showed that the degradation of cartilage, composite, and subcutaneous tissue of the NS, ULC, and LLC take place in three thermal events (~37 °C, ~189 °C, and ~290 °C) showing that cartilage releases more water and more rapidly than the subcutaneous tissue. The water content of nasal cartilage was estimated to be 42 wt %. The results of the DMA analyses demonstrated that tensile mode is ruled by flow-independent behaviour produced by the time-dependent deformability of the solid cartilage matrix that is strongly frequency-dependent, showing an unstable crystalline region between 80–180 °C, an amorphous region at around 120 °C, and a clear glass transition point at 200 °C (780 kJ/mol). Instead, the unconfined compressive mode is clearly ruled by a flow-dependent process caused by the frictional force of the interstitial fluid that flows within the cartilage matrix resulting in higher stiffness (from 12 MPa at 1 Hz to 16 MPa at 20 Hz in storage modulus). The outcomes of this study will support the development of an artificial material to mimic the thermo-mechanical behaviour of the natural cartilage of the human nose.

scholarly journals Effect of Potassium Permanganate Modification on Plasticized Spinning Polyacrylonitrile Fibers with Different Diameters

Polymers ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1330
Author(s):  
Xiang Li ◽  
Xiaonan Dang
Keyword(s):  
Potassium Permanganate ◽  
Large Diameter ◽  
Small Diameter ◽  
Amorphous Region ◽  
Treatment Temperature ◽  
Crystalline Region ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Different Diameters ◽  
First Time

Plasticized spinning polyacrylonitrile (PAN) fibers with different diameters were chemically modified by potassium permanganate (KMnO4). The modification effects of different diameter fibers were studied for the first time. Differential scanning calorimetry (DSC) results show that, compared with the large diameter ones, small diameter modified fibers show lower cyclization starting temperature (Ti) and activation energy (E). Both kinds of fibers exhibit better modification effects compared with solution-spun fibers. For the small diameter fibers, chemical modification can occur at low treatment temperature, even at 70 °C. X-ray diffraction analysis (XRD) results show that modification not only occurs in the amorphous region of the fibers but also in the crystalline region.

Technique to Measure Adhesive Forces Between Electrospun Nanofibers

2009 ◽  
Vol 1240 ◽  
Author(s):  
Qiang Shi ◽  
Kai-Tak Wan ◽  
Shing-Chung Wong ◽  
Pei Chen ◽  
Todd A. Blackledge
Keyword(s):  
Unit Area ◽  
Fiber Diameter ◽  
Electrospun Nanofibers ◽  
Amorphous Region ◽  
Adhesive Force ◽  
Degree Of Crystallinity ◽  
Scanning Calorimetry ◽  
Ultrafine Fibers ◽  
Dry Adhesion ◽  
Adhesive Forces

AbstractDue to the difficulty in handling nanofibers, little is reported and understood on the dry adhesion between electrospun nanofibers. In this study, we develop a technique to measure the dry adhesive forces between electrospun nanofibers. Of critical importance is the ability to mimic naturally occurring dry adhesion such as that between gecko's and spider's foot hairs and untreated surfaces. The adhesion test was performed on two poly(e-caprolactone) electrospun ultrafine fibers using a nanoforce tensile tester. It was found that the adhesive force per unit area increased with decreasing fiber diameter. The degree of crystallinity, order parameters of macromolecules in the amorphous region and crystallite orientation of the spun fibers were determined by the differential scanning calorimetry (DSC) and wide angle X-ray diffraction (WAXD). The high measured adhesion between single PCL fibers in comparison to other reported values was attributed to crystal orientation due to electrospinning and the increase of adhesive force per unit area with decreasing fiber diameter.

Diffusivity of solvents in semi-crystalline polyethylene using the Vrentas-Duda free-volume theory

2018 ◽  
Vol 38 (10) ◽  
pp. 925-931 ◽  
Author(s):  
Derek R. Sturm ◽  
Kevin J. Caputo ◽  
Siyang Liu ◽  
Ronald P. Danner
Keyword(s):  
Free Volume ◽  
Weight Fraction ◽  
Amorphous Region ◽  
Model Parameters ◽  
Crystalline Region ◽  
Free Volume Theory ◽  
Melt Temperature ◽  
Tortuosity Factor ◽  
Crystalline Polyethylene

Abstract Diffusion of penetrants in polyethylene below the melt temperature is heavily dependent on the crystallinity of the polyethylene, the temperature of the experiment, and the concentration of solvent in the polymer. As the crystallinity of the polyethylene increases, there is an increase in the path that the solvent must travel as the solvent cannot penetrate the tightly packed chains in the crystalline domain. This effect is typically accounted for by a tortuosity factor. In this work, a simple and effective characterization of the tortuosity factor based simply on the crystal weight fraction has been developed. Data have been collected for six polyethylenes having densities ranging from 0.912 to 0.961 g/cm3 and for three solvents – isopentane, cyclohexane, and 1-hexene. Diffusivity predictions have been obtained using the free-volume theory of Vrentas and Duda in conjunction with the new tortuosity factor. The polyethylenes had crystallinities varying from 40% to 82% effecting an approximately 60% change in the diffusivity. The decrease resulting from ignoring the crystallinity altogether was in some cases essentially a factor of 5. The error in the predicted diffusivities over all the systems was 25%. For cyclohexane, it is shown that the same model parameters characterize data below the melt temperature (in the semi-crystalline region) as well as above the melt temperature (in the amorphous region).

Morphological, structural and physicochemical properties of rice starch nanoparticles prepared via ultra-high pressure homogenization

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Chengyi Sun ◽  
Yuqing Hu ◽  
Xietian Yu ◽  
Zhijie Zhu ◽  
Shuai Hao ◽  
...  
Keyword(s):  
High Pressure ◽  
Physicochemical Properties ◽  
Particle Diameter ◽  
Amorphous Region ◽  
Rice Starch ◽  
Crystalline Region ◽  
High Pressure Homogenization ◽  
Relative Crystallinity ◽  
Ultra High Pressure ◽  
Starch Nanoparticles

Abstract Native rice starches were treated with five periods of ultra-high pressure homogenization (UHPH) under each of 60, 80, 100, 120, 140 and 160 MPa, respectively. The morphological, structural and physicochemical properties of starches treated with UHPH were examined. The mean particle diameter of starch nanoparticles ranged between 154.20 and 260.40 nm. SEM revealed that the granular amorphous region of starch granules was damaged under pressures between 60 and 80 MPa, and the crystalline region was further destroyed under pressures as high as 100–160 MPa. DSC demonstrated that the gelatinization temperatures and enthalpies of nanoparticles reduced. The relative crystallinity reduced from 22.90 to 13.61% as the pressure increased. FTIR showed that the absorbance ratio at 1047/1022 cm−1 decreased, and increased at 1022/995 cm−1. RVA results indicated that the viscosity of starch samples increased between 60 and 120 MPa, and the reverse effect was observed under 140 and 160 MPa.

Study on effect of supercritical CO2 on structural ordering and charge transporting property in thiophene-based block copolymer

2022 ◽  
Author(s):  
Satomi Hosokawa ◽  
Eri Tomita ◽  
Shinji Kanehashi ◽  
Kenji Ogino
Keyword(s):  
Supercritical Co2 ◽  
Hole Mobility ◽  
Amorphous Region ◽  
Crystalline Region ◽  
Space Charge Limited Current ◽  
Conjugation Length ◽  
Enhanced Mobility ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene ◽  
Effective Conjugation Length

Abstract We reported that supercritical (sc) annealing of poly(3-hexylthiophene) (P3HT), and its block copolymers with poly(ethylene oxide) (PEO) and polystyrene (PSt) brought about improvements in the crystal structure and hole mobility, determined by the space charge limited current (SCLC) measurement. P3HT-b-PEO showed the largest increase in mobility. From XRD profile, it was found that the treatment with scCO2 increased the crystallite size and crystallinity. UV-vis spectra showed that the effective conjugation length in the scCO2 treated films was increased compared to the as-spun, suggesting that CO2 molecules are incorporated into domains of the second block domains and P3HT amorphous region, and assist to alter the characteristics of the crystalline region. Then, it was considered that the change in the crystalline structure and the improvement of P3HT chains packing led to the enhanced mobility. Since PEO is known to have a higher affinity for CO2, the increase of mobility was specifically intensive.

Study on Structure of Amphoteric Starch and Its Reinforcing Effect on Secondary Fiber

2011 ◽  
Vol 236-238 ◽  
pp. 1112-1115
Author(s):  
Hong Wei Zhang ◽  
Guo Ping Zheng
Keyword(s):  
Control Sample ◽  
Amorphous Region ◽  
Crystalline Region ◽  
Paper Strength ◽  
Cationic Starch ◽  
Reinforcing Effect ◽  
Dry Process ◽  
Amphoteric Starch ◽  
Reinforcing Effects ◽  
Cationic Reagent

In the presented work, a series of the phosphate amphoteric cassava starch were synthesized by a two-step semi-dry process with 3-chloro-2-hydroxypropyltrimethyl ammonium chloride (CTA) as the cationic reagent and phosphate mixture as the anionic reagent. The structure of the amphoteric starch was characterized by FTIR and XRD. The reinforcing effects of the amphoteric starch on the secondary fiber were also studied. The results indicated that the reaction occurred not only in the amorphous region, but also in its crystalline region. When the cationic starch reacted with different amount of phosphates, the degree of cation substitution (DSc) of products was decreased with the dosage of the phosphates. When cationic starch with different DSc reacted with the same amount of phosphates, the degree of anion substitution (DSa) of products was decreased with the DSc. All the amphoteric starch showed reinforcing effect on the secondary fiber. The No. 7 sample showed better reinforcing effects on paper strength due to its higher total degree of substitution (0.095), proper DSa/DSc ratio (DSc = 0.067, DSa = 0.028) and interior modification of the starch granule. Compared with the control sample, the secondary fiber paper with 1.0 wt % (relative to dried pulp) of 7# modified starch showed 23.5%, 20.3% and 29.4% increases in tensile index, tearing index, and burst index, respectively.

scholarly journals Síntesis y caracterización de xerogeles de sílice obtenidos por la ruta de los atranos

2020 ◽  
Vol 5 (3) ◽  
pp. 37
Author(s):  
Lenin Jose Huerta ◽  
Rebeca Torres Fajardo ◽  
Juan Primera Ferrer
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Differential Scanning Calorimetry ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Water Evaporation ◽  
Scanning Calorimetry ◽  
Xerogel Sample ◽  
Scanning Electron

  En este trabajo se investigó la síntesis de xerogeles de sílice por la vía de los atranos, y se evaluó la influencia de la concentración del agente iniciador (HCl) y la presencia o no del surfactante (CTAB), sobre el tiempo de gelificación y las propiedades texturales de los materiales obtenidos. Las caracterizaciones se realizaron mediante: isotermas de adsorción-desorción de nitrógeno, microscopía electrónica de barrido y calorimetría diferencial de barrido. Los tiempos de gelificación aumentaron en la medida que se disminuyó la concentración del HCl y, en general, los xerogeles preparados presentaron una buena rigidez cuando estos se dejaron a tiempos mayores de 20 horas. La distribución de tamaño de poro (determinada mediante la técnica BJH) para los xerogeles calcinados preparados sin surfactante presentaron un sistema de poro bien definido de 16,4 nm en promedio, mientras los xerogeles calcinados preparados con surfactante no presentaron una distribución de tamaño de poro bien definida, ambos casos mostraron áreas superficiales de alrededor de 580 m2/g. Por calorimetría diferencial de barrido se observaron dos picos para la muestra de xerogel sin surfactante, uno alrededor de 80 °C debido a la evaporación del agua y el otro a 265 °C atribuido a la descomposición de la materia orgánica presente en el gel; para la muestra de xerogel con surfactante se observó un pico bien definido a 130 °C, atribuido a la pérdida del agua. Por microscopía electrónica de barrido, en los xerogeles calcinados se observaron poros con tamaños alrededor de los 15 nm.   Palabra clave: Xerogel, atrano, surfactante, sílice, gelificación.   Abstract In this work, the synthesis of silica xerogels by the atrane way was investigated, evaluating: concentration influence of the initiating agent (HCl) and the presence or not of the surfactant (CTAB), over gelation time, and the textural properties of the obtained materials. Characterizations were carried out by nitrogen adsorption-desorption isotherms, scanning electron microscopy, and differential scanning calorimetry. Gelation times increased as the HCl concentration decreased, and, in general, xerogels prepared presented good rigidity when they were aging for times greater than 20 hours. Pore size distribution (determined by the BJH technique) for the calcined xerogels prepared without surfactant presented a well-defined pore system of 16.4 nm on average, while the calcined xerogels prepared with surfactant did not present a well-defined pore size distribution, both cases showed surface areas of around 580 m2/g. In differential scanning calorimetry, two peaks were observed for the xerogel sample without surfactant, one around 80 °C due to water evaporation, and the other one at 265 °C attributed to the decomposition of organic matter present in the gel; for the surfactant xerogel sample, a well-defined peak was observed at 130 °C, attributed to the loss of water. By scanning electron microscopy, pores with sizes around 15 nm in calcined xerogels were observed.   Keywords: Xerogel, atrane, surfactant, silica, gelation.  

Chalcogenide glasses Ge–Sn–Se, Ge–Se–Te, and Ge–Sn–Se–Te for infrared optical fibers

1990 ◽  
Vol 5 (6) ◽  
pp. 1215-1223 ◽  
Author(s):  
I. Haruvi-Busnach ◽  
J. Dror ◽  
N. Croitoru
Keyword(s):  
Differential Scanning Calorimetry ◽  
Optical Fibers ◽  
Chalcogenide Glasses ◽  
Glass Composition ◽  
Amorphous Region ◽  
Maximum Power Density ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Ftir Spectrometry

Chalcogenide glasses of the systems Ge–Sn–Se, Ge–Se–Te, and Ge–Sn–Se–Te have been prepared. Several compositions were found suitable for drawing fibers for CO2 laser radiation (λ = 10.6 μm) transmission. The glasses were characterized by x-ray diffraction, DSC (Differential Scanning Calorimetry), SEM with EDX analysis, FTIR spectrometry, density, and microhardness measurements. The glass transition temperature and microhardness of Ge–Se–Sn and Ge–Sn–Se–Te glasses decreased with increasing Sn content, for most of the samples. The region of high IR transparency of Ge–Se–Sn, Ge–Se–Te, and Ge–Sn–Se–Te glasses was slightly expanded (1–2 μm) toward longer wavelengths, compared to Ge–Se glasses, mainly for the glasses containing 70 at.% Se. The intensity of the impurity absorption peak of Ge–O (at λ ∼ 12.8 μm), which usually appears in Ge–Se glasses, was reduced or absent in Ge–Sn–Se–Te glasses. The best fibers were produced with the glass composition Ge–0.8Sn0.2Se3.5Te0.5. An attenuation of 20 dB/m at 10.6 μm, and a transmitted maximum power density of 2.4 ⊠ 106 W/m2 were measured. The mechanical and optical characteristics of these glasses have been related to the glasses structure. Corresponding to the reduced masses of the bonds formed in the Ge–Sn–Se–Te system (in the amorphous region), it is expected that the multiphonon edge is slightly shifted. As a consequence, as was measured, the transparency region has been expanded by less than 2 μm toward longer wavelengths.

Starch-Chitosan Blend Films Prepared by Glutaraldehyde Cross-Linking

2011 ◽  
Vol 415-417 ◽  
pp. 1626-1629 ◽  
Author(s):  
Feng Hong Li ◽  
Yan Ming Chen ◽  
Liang Li ◽  
Xiao Lin Bai ◽  
Shu Li
Keyword(s):  
Tensile Strength ◽  
Corn Starch ◽  
Crosslinking Agent ◽  
Endothermic Peak ◽  
Water Evaporation ◽  
Solvent Evaporation Method ◽  
Scanning Calorimetry ◽  
Blend Films ◽  
Dsc Studies ◽  
Higher Temperature

The present study evaluated the properties of the polymeric blend films obtained from chitosan and corn starch using glutaraldehyde as crosslinking agent and glycerol as plasticizer by the casting/solvent evaporation method. Fourier transform infrared (FTIR) analyses confirmed that the groups interactions of starch and chitosan in starch-chitosan blend films were present especially when using glutaraldehyde as crosslinking agent. Differential scanning calorimetry (DSC) studies revealed an endothermic peak of starch film at 98 oC corresponding to water evaporation. DSC also indicated that the endothermic peak of blend films moved to higher temperature with adding chitosan and glutaraldehyde compared with native corn starch film. The tensile strength of the blend films increased with the increasing content of glutaraldehyde. The starch-chitosan blend films exhibited the highest tensile strength of 11 MPa when the content of starch was 9% (w/v in water), glutaraldehyde content was 1.0 mL, chitosan ratio is 0.35 (wchitosan/wstarch), glycerol ratio was 0.35 (wglycerol /wstarch).

Hyaluronate degradation as an alternative mechanism for proteoglycan release from cartilage during interleukin-1β-stimulated catabolism

2002 ◽  
Vol 362 (2) ◽  
pp. 473-479 ◽  
Author(s):  
Robert SZTROLOVICS ◽  
Anneliese D. RECKLIES ◽  
Peter J. ROUGHLEY ◽  
John S. MORT
Keyword(s):  
Core Protein ◽  
Cartilage Matrix ◽  
Interleukin 1Β ◽  
Alternative Mechanism ◽  
Human Articular Cartilage ◽  
Link Protein ◽  
Nasal Cartilage ◽  
Fetal Bovine ◽  
Proteoglycan Release ◽  
Aggrecan Core Protein

Data presented previously suggest that release of components of the cartilage matrix, in response to catabolic agents, cannot be accounted for by proteolytic mechanisms alone. In the present study, the release of glycosaminoglycan-containing components from bovine nasal cartilage cultured in the presence of interleukin-1β, and from bovine nasal, fetal bovine epiphyseal and adult human articular cartilage cultured in the presence of retinoic acid, was accompanied by the loss of link protein and hyaluronate into the culture medium. Chromatographic analysis of the released hyaluronate showed it to be markedly reduced in size relative to that extracted from the corresponding tissue. It is proposed that, under stimulation by catabolic agents, two independent, but concurrent, mechanisms act to promote the release of aggrecan from the cartilage matrix. First, proteolytic cleavage of the aggrecan core protein results in the production of glycosaminoglycan-containing fragments that are free to diffuse from the tissue. Secondly, cleavage of hyaluronate renders portions of the proteoglycan aggregate small enough so that complexes of aggrecan (or fragments containing its G1 domain) and link protein are released from the tissue. It is likely that both mechanisms contribute to cartilage metabolism in normal physiology and pathology.

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