Copolyesters having secondary and tertiary amine salt groups in the main and side chains are prepared by chemoselective polymerization. These copolyesters are soluble in a 10% aqueous solution of poly(vinyl alcohol) ...Copolyesters having secondary and tertiary amine salt groups in the main and side chains are prepared by chemoselective polymerization. These copolyesters are soluble in a 10% aqueous solution of poly(vinyl alcohol) (PVA) at 90 degree C and act as plasticizer in the blend films cast from the solution. Only a glass transition temperature is observed for all these blends indicating the formation of compatible blends from these polyesters with PVA. These blends exhibit manifold characteristics such as ionic conductivity, complex formation with metal ions, absorption of moisture and color changes. The electric conductivity of the copolyesters and blends is in the range of 10** minus **6 Scm** minus **1. The blends with PVA forms complexes with Cu**2** plus and Co**2** plus . The coordination structure with two chelate rings is suggested for these polymer blend/metal complexes. (Author abstract) 10 Refs.展开更多
X-ray diffraction line profiles of low density polyethylene(LDPE)/ (ethylene-propylene-octene-1)copolymer(EPO)blends have been analyzed with variance range function method.Theories for determining the microparacrystal...X-ray diffraction line profiles of low density polyethylene(LDPE)/ (ethylene-propylene-octene-1)copolymer(EPO)blends have been analyzed with variance range function method.Theories for determining the microparacrystallite size and the distortion parameter from single reflection have been described,and the value of these two parameters at (110)and(200)directions have been determined.展开更多
Melt extrusion-based additive manufacturing(ME-AM)is a promising technique to fabricate porous scaffolds for tissue engi-neering applications.However,most synthetic semicrystalline polymers do not possess the intrinsi...Melt extrusion-based additive manufacturing(ME-AM)is a promising technique to fabricate porous scaffolds for tissue engi-neering applications.However,most synthetic semicrystalline polymers do not possess the intrinsic biological activity required to control cell fate.Grafting of biomolecules on polymeric surfaces of AM scaffolds enhances the bioactivity of a construct;however,there are limited strategies available to control the surface density.Here,we report a strategy to tune the surface density of bioactive groups by blending a low molecular weight poly(ε-caprolactone)5k(PCL5k)containing orthogonally reactive azide groups with an unfunctionalized high molecular weight PCL75k at different ratios.Stable porous three-dimensional(3D)scaf-folds were then fabricated using a high weight percentage(75 wt.%)of the low molecular weight PCL 5k.As a proof-of-concept test,we prepared films of three different mass ratios of low and high molecular weight polymers with a thermopress and reacted with an alkynated fluorescent model compound on the surface,yielding a density of 201-561 pmol/cm^(2).Subsequently,a bone morphogenetic protein 2(BMP-2)-derived peptide was grafted onto the films comprising different blend compositions,and the effect of peptide surface density on the osteogenic differentiation of human mesenchymal stromal cells(hMSCs)was assessed.After two weeks of culturing in a basic medium,cells expressed higher levels of BMP receptor II(BMPRII)on films with the conjugated peptide.In addition,we found that alkaline phosphatase activity was only significantly enhanced on films contain-ing the highest peptide density(i.e.,561 pmol/cm^(2)),indicating the importance of the surface density.Taken together,these results emphasize that the density of surface peptides on cell differentiation must be considered at the cell-material interface.Moreover,we have presented a viable strategy for ME-AM community that desires to tune the bulk and surface functionality via blending of(modified)polymers.Furthermore,the use of alkyne-azide“click”chemistry enables spatial control over bioconjugation of many tissue-specific moieties,making this approach a versatile strategy for tissue engineering applications.展开更多
The thermal decomposition analysis of coal-pharmaceutical waste sludge,coal-sewage waste sludge blends and coal-sunflower seed husk blends are studied by TG dynamic runs at the heating rate of 20 ℃/min within the tem...The thermal decomposition analysis of coal-pharmaceutical waste sludge,coal-sewage waste sludge blends and coal-sunflower seed husk blends are studied by TG dynamic runs at the heating rate of 20 ℃/min within the temperature range of 25 ℃-900 ℃.The effect of different kinetic models on the determination of kinetic parameters of thermal decomposition has been investigated.Results show that for coal-pharmaceutical sludge blend,coal-sewage sludge blend and coal-sunflower seed husk blend the optimal model functions are the three-dimensional diffusion reaction,2-dimensional and 3-diemensional nucleation and growth reactions,respectively.The Arrhenius kinetic parameters of the pre-exponential factor and activation energy of blends,as well waste sludge and sunflower seed husk only are proposed.展开更多
文摘Copolyesters having secondary and tertiary amine salt groups in the main and side chains are prepared by chemoselective polymerization. These copolyesters are soluble in a 10% aqueous solution of poly(vinyl alcohol) (PVA) at 90 degree C and act as plasticizer in the blend films cast from the solution. Only a glass transition temperature is observed for all these blends indicating the formation of compatible blends from these polyesters with PVA. These blends exhibit manifold characteristics such as ionic conductivity, complex formation with metal ions, absorption of moisture and color changes. The electric conductivity of the copolyesters and blends is in the range of 10** minus **6 Scm** minus **1. The blends with PVA forms complexes with Cu**2** plus and Co**2** plus . The coordination structure with two chelate rings is suggested for these polymer blend/metal complexes. (Author abstract) 10 Refs.
文摘X-ray diffraction line profiles of low density polyethylene(LDPE)/ (ethylene-propylene-octene-1)copolymer(EPO)blends have been analyzed with variance range function method.Theories for determining the microparacrystallite size and the distortion parameter from single reflection have been described,and the value of these two parameters at (110)and(200)directions have been determined.
基金the European Research Council starting grant “Cell Hybridge” for financial support under the Horizon2020 framework program (Grant#637308)the Province of Limburg for support and funding
文摘Melt extrusion-based additive manufacturing(ME-AM)is a promising technique to fabricate porous scaffolds for tissue engi-neering applications.However,most synthetic semicrystalline polymers do not possess the intrinsic biological activity required to control cell fate.Grafting of biomolecules on polymeric surfaces of AM scaffolds enhances the bioactivity of a construct;however,there are limited strategies available to control the surface density.Here,we report a strategy to tune the surface density of bioactive groups by blending a low molecular weight poly(ε-caprolactone)5k(PCL5k)containing orthogonally reactive azide groups with an unfunctionalized high molecular weight PCL75k at different ratios.Stable porous three-dimensional(3D)scaf-folds were then fabricated using a high weight percentage(75 wt.%)of the low molecular weight PCL 5k.As a proof-of-concept test,we prepared films of three different mass ratios of low and high molecular weight polymers with a thermopress and reacted with an alkynated fluorescent model compound on the surface,yielding a density of 201-561 pmol/cm^(2).Subsequently,a bone morphogenetic protein 2(BMP-2)-derived peptide was grafted onto the films comprising different blend compositions,and the effect of peptide surface density on the osteogenic differentiation of human mesenchymal stromal cells(hMSCs)was assessed.After two weeks of culturing in a basic medium,cells expressed higher levels of BMP receptor II(BMPRII)on films with the conjugated peptide.In addition,we found that alkaline phosphatase activity was only significantly enhanced on films contain-ing the highest peptide density(i.e.,561 pmol/cm^(2)),indicating the importance of the surface density.Taken together,these results emphasize that the density of surface peptides on cell differentiation must be considered at the cell-material interface.Moreover,we have presented a viable strategy for ME-AM community that desires to tune the bulk and surface functionality via blending of(modified)polymers.Furthermore,the use of alkyne-azide“click”chemistry enables spatial control over bioconjugation of many tissue-specific moieties,making this approach a versatile strategy for tissue engineering applications.
基金Sponsored by the National Natural Science Foundation of China(Grant No.21076043)China Postdoctoral Science Foundation(Grant No.20090460070)+1 种基金Heilongjiang Province Postdoctoral Science Foundation(Grant No.LBH-Z09292)Educational Committee of Heilongjiang Privince Science Foundation(Grant No.11551006)
文摘The thermal decomposition analysis of coal-pharmaceutical waste sludge,coal-sewage waste sludge blends and coal-sunflower seed husk blends are studied by TG dynamic runs at the heating rate of 20 ℃/min within the temperature range of 25 ℃-900 ℃.The effect of different kinetic models on the determination of kinetic parameters of thermal decomposition has been investigated.Results show that for coal-pharmaceutical sludge blend,coal-sewage sludge blend and coal-sunflower seed husk blend the optimal model functions are the three-dimensional diffusion reaction,2-dimensional and 3-diemensional nucleation and growth reactions,respectively.The Arrhenius kinetic parameters of the pre-exponential factor and activation energy of blends,as well waste sludge and sunflower seed husk only are proposed.
文摘目的:探讨芪参还五胶囊对血管性痴呆(vascular dementia,VD)痰瘀互结型患者认知功能及血清标志物的影响。方法:将痰瘀互结型VD患者80例应用计算机随机数字发生器分为对照组和观察组各40例。对照组应用吡拉西坦片治疗,观察组采用芪参还五胶囊治疗,两组患者均连续服药6周。观察治疗前后两组患者中医证候积分、认知功能[简易智力状态检查量表(Mini-mental state examination,MMSE)]与日常生活能力量表(ability of daily life,ADL)评分、血清神经元特异性烯醇化酶(neuron specific enolase,NSE)、超敏C反应蛋白(high-sensitive C-reactive protein,hs-CRP)、脑源性神经营养因子(brain derived neurotrophic factor,BDNF)、乙酰胆碱(acetylcholine,Ach)、乙酰胆碱酯酶(acetylcholinesterase,AChE)、胆碱乙酰转移酶(choline acetyltransferase,ChAT)水平变化情况及临床疗效。分析血清指标变化与认知功能变化的相关性。结果:治疗后两组患者智能减退、神情呆钝、形盛体胖、呕吐痰涎、唇甲青紫及肌肤甲错症状均较治疗前减轻,观察组效果优于对照组(P<0.05)。总有效率观察组为90%,高于对照组的60%(P<0.05)。治疗后两组患者MMSE、ADL评分均升高(P<0.05),观察组高于对照组(P<0.05);血清NSE、hs-CRP及AchE水平均降低(P<0.05),观察组低于对照组(P<0.05);BDNF及Ach、ChAT水平均升高(P<0.05),观察组高于对照组(P<0.05)。Pearson相关系数分析显示MMSE、ADL评分均与血清Ach、ChAT、BDNF呈正相关,与血清AchE、NSE及hs-CRP呈负相关,且差异具有统计学意义(P<0.05)。结论:芪参还五胶囊能改善VD患者临床症状,调节血清NSE、hs-CRP、BDNF与胆碱能神经递质水平,提高认知功能和日常生活功能,效果优于吡拉西坦片。
