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1.
以改性聚磷酸铵(MAPP)和改性淀粉(MST)分别作为酸源和碳源,以聚合物Jonctyl®ADR-4368(简称ADR)作为体系增容剂,通过共混及热压成型制备了阻燃聚乳酸(PLA)材料。采用极限氧指数(LOI)来表征共混物的阻燃性能,采用热重分析(TGA)表征共混物的热稳定性能,差示扫描量热仪(DSC)表征共混物的热学性能,扫描电镜(SEM)表征各样品以及刻蚀淀粉后样品的表面形貌,拉伸试验表征各样品的韧性以及强度。PLA复合材料的阻燃性能以及韧性相对聚乳酸有较大程度的提升,加入MAPP后复合材料热稳定性增加,加入聚合物ADR后体系相容性提高。  相似文献   

2.
选用甲基丙烯酸缩水甘油酯接枝乙烯辛烯共聚物(POE-GMA)和聚乳酸、木粉在Haake转矩流变仪中熔融共混。通过拉伸、冲击、差示扫描量热、扫描电镜等测试方法对共混复合材料的性能进行了研究。结果表明:聚乳酸木塑复合材料的拉伸强度和弯曲性能随POE-GMA添加量的增加而减小;POE-GMA的加入使聚乳酸木塑复合材料的结晶温度下降,结晶度升高;当m(PLA)∶m(WF)∶m(POE-GMA)=80∶20∶20时,复合材料的表面自由能最低,接触角最大,吸水性最低;随着木粉含量的增加,复合材料的起始热降解温度降低,POE-GMA的含量增加对聚乳酸木塑复合材料的起始热降解温度影响不大。  相似文献   

3.
以二乙酸甘油酯(GD)引发L-丙交酯(LLA)开环聚合合成了二乙酸甘油酯封端的齐聚L-丙交酯(OGLA),并以此为增塑剂,以溶液共混法制备了OGLA与高分子量聚L-丙交酯(PLLA)的共混膜。采用DSC研究了共混膜的Tg和结晶性变化,考察了共混膜的力学性能和渗出性。结果表明:随着OGLA含量的增加,共混物Tg下降,结晶度降低,柔性提高;与聚乳酸相比,随着OGLA含量的增加,拉伸强度、弹性模量有一定程度降低,但断裂伸长率有较大程度的提高,力学性能得到较好的平衡;OGLA增塑体系与GD增塑体系相比较,优势在于避免了小分子增塑剂的渗出。  相似文献   

4.
以丙三醇和癸二酸为单体通过熔融缩聚制得了聚癸二酸丙三醇酯(PGS),并用其预聚物(p-PGS)对聚L-丙交酯(PLLA)进行共混改性.利用傅立叶变换红外光谱(FT-IR)、核磁共振氢谱(1H-NMR)及凝胶渗透色谱(GPC)法对P-PGS的结构进行表征,并研究了改性后材料的力学性能、两相相容性、亲水性能和细胞相容性.结果表明:P-PGS具有支化分子结构,分散系数约为2.7;共混改性后的材料弹性模量和拉伸强度均有所下降,而断裂伸长率从7 %显著提高到150%左右;PLLA/PGS属于海岛式共混结构,PGS以小于10μm的尺寸均匀分布在PLLA基体中;共混后材料的亲水性也有一定的提高,且几乎保持了PLLA原有的细胞相容性.  相似文献   

5.
以丙三醇、己二酸为原料,通过熔融缩聚合成了新型聚乳酸(PLA)增韧改性剂聚己二酸丙三醇酯(PGA).利用傅立叶变换红外光谱(FT-IR),核磁共振氢谱(1H-NMR)及凝胶渗透色谱(GPC)等方法对不同反应温度条件下PGA的分子结构进行了表征.同时通过熔融共混制备了PGA/PLA共混物,并测试了共混物的冲击性能,利用差示扫描量热仪(DSC)和扫描电子显微镜(SEM)对其热性能及相形貌进行了表征.结果表明:PGA可以有效增韧聚乳酸,160℃下合成的PGA增韧性最佳,冲击强度达到48.0 J/m,较纯聚乳酸提高了3倍.PGA分子支化结构的差异对PGA/PIA的共混形态有明显的影响,从而进一步影响其增韧效果.  相似文献   

6.
以柠檬酸三丁酯(TBC)引发D,L丙交酯(DLLA)开环,聚合合成了柠檬酸三丁酯封端的低分子量聚D,L丙交酯(PBLA)。并以此聚合物为增塑剂,采用溶液共混法制备了与高分子量聚L丙交酯(PLLA)的共混膜,研究了增塑剂用量对共混物性能的影响。动态热机械性能(DTMA)和DSC分析结果表明:随着PBLA质量分数的增加,共混物Tg下降,结晶度降低,柔性提高。机械性能分析结果表明:与PLLA相比,随着PBLA质量分数的增加,共混物拉伸强度、弹性模量有一定程度降低,但断裂伸长率有较大程度提高,力学性能得到较好平衡。体外人体肾胚胎细胞培养结果显示材料的生物相容性未见统计学意义上的改变,体现出较高的潜在应用价值。  相似文献   

7.
以聚乳酸(PDLLA)和聚己内酯(PCL)为原材料,采用熔融共混法制备PDLLA-PCL共混物。采用拉伸试验机、差示扫描量热仪(DSC)、毛细管流变仪和原子力显微镜分别对共混材料的力学性能、热力学性能、流变性能和表面微观形貌进行了分析与表征。研究表明:随着PCL含量增加,共混物的柔韧性提高,拉伸强度逐渐降低,熔融峰向高温方向移动,熔融热焓和结晶热焓增加,表观黏度增大;PDLLA-PCL共混物制备的薄膜表面平整度优于PDLLA薄膜,当w(PCL)=30%时达到最好。  相似文献   

8.
以聚癸二酸甘油酯(PGS)和聚乳酸(PLA)为原料在Haake转矩流变仪中密炼制备了不同配比的PGSPLA共混材料。研究了共混材料的转矩流变性能、热性能、力学性能及其共混形态。结果表明PGSPLA共混材料的转矩流变过程与PLA有很大差异,其熔融塑化过程大幅延长。DSC分析表明:随着PGS含量的增加,PGS-PLA共混材料的玻璃化温度、结晶温度和熔融温度降低,而结晶度提高;共混材料的冲击强度最大可以达到65.6 J/m,较纯PLA提高了447%;SEM观测表明PGS和PLA是分相的,且随PGS含量的提高  相似文献   

9.
采用真空熔融缓冷方法合成了单相β-Zn4Sb3化合物,并通过水解钛酸四丁酯(TBOT)制备了TiO2/β-Zn4Sb3复合材料。采用放电等离子(SPS)烧结获得了致密的块材样品。研究了TiO2质量分数对复合材料热电性能的影响规律。结果发现,随着TiO2质量分数的增加,材料的Seebeck系数升高,电导率和热导率均显著下降,计算得出热电优值(ZT)在638 K时达0.68,比单相Zn4Sb3的ZT值提高了19%。  相似文献   

10.
通过缩聚反应制备聚乙二醇-柠檬酸共聚物(PEGCA),通过密炼制备了PEGCA与聚乳酸(PLA)的共混物,研究了PEGCA对共混物的形貌结构、热性能和力学性能的影响。结果表明,PEGCA与PLA部分相容,PEGCA呈球状颗粒分散在PLA基体中。PEGCA对PLA有良好的增韧效果,当PEGCA质量分数为15%时,材料的断裂伸长率提高到327.9%,冲击强度提高到63.0 J/m。同时利用空穴化理论解释PEGCA增韧PLA的机理,用临界韧带厚度理论和J积分定量描述增韧的效果。  相似文献   

11.
Objective To observe blood pressure change with age in salt-sensitive teenagers whose salt sensitivity were determined by repeated testing.Methods Salt sensitivity was determined through intravenous infusion of normal saline combined with volume-depletion by oral diuretic furosemide in 55 teenagers. After five years, salt sensitivity was re-examined and subject blood pressure was followed up. Blood pressure changes in salt-sensitive teenagers were compared to that of non-salt sensitive teenagers over five years.Results After 5 years, the repetition rate of salt sensitivity determined by intravenous saline loading is 92.7%. In teenagers with salt sensitivity on the baseline, both the systolic blood pressure increments and increment rates were much higher than non-salt sensitive teenagers (12.7±12.1 mmHg vs. 2.8±5.2 mmHg, P< 0.01; 12.2%± 12.0% vs. 2.5% ±4.4%, P< 0.001,respectively). There was a similar trend for diastolic blood pressure (8.4 ± 6.4 mmHg vs. 3.7 ± 6.4 mmHg, P = 0.052; 13.2% ±10.6 % vs. 6.8%± 10.1%, P = 0.053, respectively).Conclusions Salt sensitivity determined by intravenous saline loading showed good reproducibility. Blood pressure increments with age were much higher in salt-sensitive teenagers than non-salt sensitive teenagers, especially in terms of systolic blood pressure.  相似文献   

12.
Objective: To evaluatel the value of D-dimers in patients with acute aortic dissection (AAD). Methods: This study consisted of 16 patients with AAD and 27 non-AAD patients. Serum D-dimets were measured by Sta-Liatest D-DI immunoturbidimetric assay. Results: D-dimer level was higher (P < 0.001) in patients with AAD(7.91 ± 5.52 μg/ml) than that in non- AAD group(1.57±1.24 μg/ml). D-dimer was positive (>0.4 μg/ml) in all patients with AAD and in 10 control group patients (37%). Among patients with acute AAD, D-dimers tended to be higher in Stanford A than in Stanford B (8.67 ± 4.31 μg/ml vs. 3.24±1.27 μg/ml, P <0.01). D-dimer values tended to be higher in more extended disease(3.84 ± 1.65 μg/ml, 8.57 ± 3.58 μg/ml and 11.87 ± 5.69 μg/ml in thoracic aorta, thoracic and abdominal aorta, thoracic and abdominal aorta and iliacal arteries, respectively, P < 0.05 for both 8.57 ± 3.58 and 11.87 ± 5.69 vs. 3.84 ± 1.65 ). Including the control group into the analysis, we found a sensitivity of 100%, a negative predictive value of 100%, and a specificity of 66% and a positive predictive value of 64% for D-dimer in diagnosis of AAD in our patients with suspected AAD. Conclusion: D-dimer was elevated in patients with AAD. A negative D-dimer test result could be useful in excluding AAD.  相似文献   

13.
Objective: To set up a simple and reliable rat model of combined liver-kidney transplantation. Methods: SD rats served as both donors and recipients. 4℃ sodium lactate Ringer's was infused from portal veins to donated livers,and from abdominal aorta to donated kidneys, respectively. Anastomosis of the portal vein and the inferior vena cava (IVC) inferior to the right kidney between the graft and the recipient was performed by a double cuff method, then the superior hepatic vena cava with suture. A patch of donated renal artery was anastomosed to the recipient abdominal aorta. The urethra and bile duct were reconstructed with a simple inside bracket. Results: Among 65 cases of combined liver-kidney transplantation, the success rate in the late 40 cases was 77.5%. The function of the grafted liver and kidney remained normal. Conclusion: This rat model of combined liver-kidney transplantation can be established in common laboratory conditions with high success rate and meet the needs of renal transplantation experiment.  相似文献   

14.
Increasing maternal age is the only etiological factor unequivocally linked to Down's syndrome in humans. The occurrence rate of newborns with Down's syndrome is about 1/220 in women over 35 years old. However, the occurrence rate in embryos fertilized in vitro, of the elder woman is unclear. Using FISH we screened the number of chromosome 21 in preimplanted embryos of 5 elderly women (average age, 38.4 years) to study the feasibility and necessity of screening trisomy 21 in embryos in patients over 35 years old at the in vitro fertilization (IVF) center.  相似文献   

15.
Real-time three-dimensional echocardiography (RT3DE)is a new ultrasound technique that enables dynamic threedimensional visualization and quantification of the heart in real time. Investigation of feasibility and methodology of RT3DE in determining left ventricular (LV) and right ventricular (RV) volumes, RT3DE was performed in 35 normal adults using Philips SONOS 7500 system with a 2-4 MHz matrix array transducer. The 60°×60° "pyramid" volume database was obtained and analyzed on a TomTec echo workstation. Both LV and RV volumes were calculated with four 3DE methods (i.e. apical 2, 4, 8, and 16-plane) through manually tracing ventricular endocardial borders in end diastole and end systole. Stroke volumes were then calculated. LV volume was also measured by 2DE Simpson's rule using GE VIVID 7 ultrasound machine.  相似文献   

16.
A clinical guideline for the therapeutic interventions of integrative medicine may be defined as a written document which states a series of recommendations on therapeutic interventions of integrative medicine for a special disease or condition. The guideline may provide assistance to medical professionals in making clinical decisions aimed at improving the clinical outcome of patients and reducing the costs of medical care(~'4~. Recommendations issued by a guideline should be based on the best available evidence in both Western and Chinese medicine. For fulfilling this purpose, the development of clinical guidelines for therapeutic interventions in the field of integrative medicine should follow scientific principles and undergo a rigorous processes.  相似文献   

17.
Objective:To probe into the influence of changes of ovarian hormones on the pathogenesis of the specific sub-type premenstrual syndrome(PMS)and reveal partial microcosmic mechanisms of adverse flow of liver-qi.Methods:Estradiol(E2)and progesterone(P)levels in serum were determined at different phases of menstrual cycle by radioimmunoassay.Results:In the group of PMS with adverse flow of liver-qi.the secretive peak value Of E2 and P at the follicular phase significantly decreased,and the secretive peak value at the luteal phase did not come into being.Conclusions:Low E2 and P secretive peak at the follicular phase and absence of secretive peak at the luteal phase is one of the microcosmic mechanisms of PMS with adverse flow of liver-qi.One of the pathophysiologic mechanisms of specific sub-type PMS is probably the continuous low level of E2and P.  相似文献   

18.
Journal of Nanjing Medical University (English Edition) JNMU, sponsored by Nanjing Medical University, was established in 1987. It is a bimonthly comprehensive English medical journal published locally and abroad.Since 2007, Journal of Nanjing Medical University (English Edition )was granted Elsevier the full publishing and distribution rights worldwide for the Electronic Edition, excluding the People's Republic of China.  相似文献   

19.
目的:评价使用安心颗粒对急诊经皮冠状动脉介入术(PPCI)术后生活质量的影响.方法:将160例接受PPCI的急性ST段抬高型心肌梗死患者随机分为安心颗粒组(术前顿服安心颗粒8.8g,术后安心颗粒4.4 g/次,每日2次)和对照组(仅接受基础药物治疗).所有患者均服用阿司匹林、氯吡格雷和阿托伐他汀.分别在入院时、出院前1d、出院后180 d时,应用心肌梗死多维度量表(MIDAS)、中文版SF-36评价量表对患者生活质量评分.并观察术后30 d以内的出血并发症、血小板减少症发生情况.结果:入院时和出院前1d,两组患者的心肌梗死MIDAS、SF-36量表评分比较无差异(P>0.05);出院后180 d时,与对照组比较,安心颗粒组MIDAS、SF-36评分明显减低(P<0.05);组内与入院时比较,两组出院前1d、出院后180 d时,MIDAS、SF-36评分均降低(P<0.05).两组患者在随访期间均无大量出血、少量出血、重度和极重度血小板减少症发生,安心颗粒组有4例、对照组有7例发生不明显出血(P>0.05).两组发生轻度血小板减少症的患者数比较无差异(P>0.05).结论:PPCI使用安心颗粒,能改善急性ST段抬高型心肌梗死患者的生活质量,且不增加出血风险.  相似文献   

20.
Objective:To investigate the influences of urapidil and nicardipine on rabbit sinus function,atrio-ventricular node function and hemodynamics.Methods:Thirty-two Angora's rabbits were selected and randomly divided into four groups.U1 group:urapidil 0.25 mg/kg;U2 group:urapidil 0.5 mg/kg;N1 group:nicardipine 10 μg/kg;N2 group:nicardipine 20 μg/kg.All these medicine were administrated within 30 seconds.Measurements were taken before and after the administration of urapidil or nicardipine for the following data:mean blood pressure(MAP),heart rate(HR),sino-atrial conduction time(SACT),maximal sinoatrial recovery time(SNRTmax)corrected sinus node recovery time(CSNRT),index of sinus node recovery time(SNRTI),Wenckebach A-V conduction frequency (WB),and P-R interval.Results:Significant MAP and HR changes were identified in all of the four groups before and after administration of both urapidil and nicardipine.No significant changes could be found in the rest of the parameters.Intergroup analysis showed that SACT and CSNRT of N1 and N2 groups were shorter than those of the U2 group(P<0.01);the MAP decreased(P<0.01)and the HR increased drastically(P<0.01).Conclusions:Neither urapidil(0.25 mg/kg,0.5 mg/kg)nor nicardipine(10μg/kg,20μg/kg)has any significant influence on rabbit sinus function or rabbit atrio-ventricular node function.Nicardipine could be a better choice than urapidil for parafunctional sinus node patients.  相似文献   

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