Cross-linked starch nanocrystals (CStN)/polylactic acid (PLA) nanocomposites were prepared by blending CStN and PLA, wherein CStN were homogeneously dispersed in the nanocomposites. The structure and morphology of the nanocomposites were studied through FTIR, XRD, and SEM. The results of mechanical test showed that the strength and toughness of the nanocomposites could be improved when the additive amount of hydrophobic CStN was 3% (weight ratio). Meanwhile, the microstructures of tensile fracture surface showed that CStN were uniformly dispersed in PLA matrix, and the tensile fracture surface was presented as ductile fracture. Moreover, water vapor permeability experiments illustrated that the addition of CStN reduced the water vapor permeability of PLA nanocomposites, so CStN have some resistance to water vapor. Those above indicated that CStN have functions of reinforcement and toughness in PLA matrix; therefore, they are expected to be used as functional additives in polymer matrix such as PLA, polycaprolactone (PCL), and polybutylene succinate (PBS).

The modified starch nanocrystals were prepared through multicomponent reaction of polydimethylsiloxane with isocyanate terminal groups,diphenylmethane diisocyanate and hydroxyl groups of the starch nanocrystals.The modified starch nanocrystals with low surface energy polydimethylsiloxane chains have good dispersion.The structure and morphology of the modified starch nanocrystals were studied through Fourier Transform Infrared Spectroscopy(FT-IR),proton Nuclear Magnetic Resonance(1 HNMR)Spectroscopy,X-ray Photoelectron Spectroscopy(XPS),X-ray Diffraction(XRD),Scanning Electron Microscopy(SEM),etc.Results showed that low surface energy polydimethylsiloxane and diphenylmethane diisocyanate reacted with the starch nanocrystals to obtain synergistic modified starch nanocrystals.The diameter of nanoparticles was 50—100nm.Moreover,wettability experiment showed that the modified starch nanocrystals suspension was dispersed stably in distilled water,dichloromethane,ethyl acetate and acetone.

ABSTRACTStarch nanocrystals‐g‐polystyrene (StN‐g‐PS) was synthesized by free radical emulsion copolymerization of starch nanocrystals with styrene. The effect of polymerization conditions on grafting efficiency (GE) and grafting ratio (GR) were investigated. It was found that during graft copolymerization procedure both GE and GR increase with increasing monomer concentration and reaction time. As a result the high GE and high GR can be achieved. The good linear fit of the GR with ASt/AOH (the absorption strength ratio of aromatic ring peaks and hydroxyl group peaks) confirmed that during graft copolymerization, FTIR spectra can be used as a simple method for determining GR. X‐ray diffraction showed that the crystallinity of StN‐g‐PS decreased slightly with increasing GR. Grafted polystyrene side chains can improve the interface compatibility of starch nanocrystals with the hydrophobic polymer matrix. The mechanical properties of StN‐g‐PS/rubber nanocomposites can be obviously enhanced. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40571.

通过异氰酸酯与端羟基聚己内酯反应制备端异氰酸酯基预聚体,再接枝到淀粉纳米晶表面,制备了端基分子量可控的聚己内酯接枝淀粉纳米晶.分别用FTIR和1H NMR对所制备的聚己内酯接枝淀粉纳米晶进行表征,结果表明,有少量聚己内酯接枝到淀粉纳米晶表面.XRD结果表明,接枝了少量聚己内酯后的淀粉纳米晶的晶型和结晶度与未接枝的淀粉纳米晶基本一致.聚己内酯接枝淀粉纳米晶的熔融温度由115℃左右提高到122℃左右,并且温度范围变宽.浸润性实验表明,聚己内酯接枝淀粉纳米晶与水不浸润,其表面已具有疏水性.聚己内酯仅接枝在淀粉纳米晶的表面,改善了淀粉纳米晶表面的疏水性能和与聚酯类聚合物的界面相容性.聚己内酯接枝淀粉纳米晶有望用于可降解聚酯类高分子材料,如聚乳酸(PLA)、聚己内酯(PCL)、聚丁二酸丁二醇酯(PBS)等,改善其力学性能和生物降解性能等.

Starch nanocrystals of platelet nanoparticles 50–100 nm are prepared by acid hydrolysis of natural starch. To improve both the dispersion stability of starch nanocrystals and the interphase compatibility with polymer matrix, hydrophobic benzyl groups were introduced for the surface modification. The modified benzyl starch nanocrystals were characterized using Fourier transform infrared spectra, proton nuclear magnetic resonance spectroscopy (1H NMR) and X-ray diffraction. The characterization results showed that the molecular structure and crystalline structure of prepared benzyl starch nanocrystals have little changes and that the degree of substitution of benzyl starch nanocrystals was about 0.05. The morphology study indicated that after modification the nanoparticles’ size decreased and the homogenous distribution of size increased. Wettability tests showed that the low substituted benzyl starch nanocrystals have appropriate hydrophilicity and can be uniformly dispersed in water. Since its excellent reinforcing effect and antistatic properties of benzyl starch nanoparticles, it can be used in rubber composites. The composites were prepared by co-mixing the benzyl starch nanocrystals with the natural rubber and silica. The mechanical properties and the antistatic properties of benzyl starch nanocrystals/natural rubber nanocomposites were dramatically enhanced. As expected the benzyl starch nanocrystals obtained is a new functional biopolymer filler or additive for the polymer composites.

通过环氧氯丙烷与淀粉纳米晶表面羟基活性基团反应,制备交联淀粉纳米晶,并经傅里叶变换红外光谱、核磁共振氢谱、X射线衍射及扫描电镜等对其结构与形态进行表征.交联淀粉纳米晶在化学结构上变化不大,由交联反应形成的化学键仍为醚键,与淀粉纳米晶本身的化学键类似.交联淀粉纳米晶的结晶结构也基本不变,得到的是分散比较稳定的50 nm左右的颗粒.而热性能分析表明,交联淀粉纳米晶的熔融温度略有提高.浸润性实验结果表明,交联淀粉纳米晶具有一定的疏水性,可在水、丙酮、二氯甲烷中均匀分散,但在乙酸乙酯中无法分散.交联淀粉纳米晶与聚丁二酸丁二醇酯复合材料的力学性能表明,当交联淀粉纳米晶含量为3％时,拉伸强度增加约11％,拉伸模量增加约13％,断裂伸长提高约10％,说明交联淀粉纳米晶可以增强、增韧聚丁二酸丁二醇酯.

将具有双亲性表面结构的聚苯乙烯接枝淀粉纳米晶与天然橡胶共混,制备了双亲性淀粉纳米晶/天然橡胶复合材料.利用扫描电子显微镜表征了聚苯乙烯接枝淀粉纳米晶的微观结构,粒径在50 ～ 100 nm.聚苯乙烯接枝淀粉纳米晶对天然橡胶具有很好的增强效果,优于淀粉纳米晶.所制备的橡胶复合材料抗湿滑性显著提高,而添加10％聚苯乙烯接枝淀粉纳米晶的橡胶复合材料滚动阻力也同时降低,可用于绿色轮胎材料.

将具有双亲性表面结构的聚苯乙烯接枝淀粉纳米晶与天然橡胶共混,制备了双亲性淀粉纳米晶/天然橡胶复合材料。利用扫描电子显微镜表征了聚苯乙烯接枝淀粉纳米晶的微观结构,粒径在50～100 nm。聚苯乙烯接枝淀粉纳米晶对天然橡胶具有很好的增强效果,优于淀粉纳米晶。所制备的橡胶复合材料抗湿滑性显著提高,而添加10%聚苯乙烯接枝淀粉纳米晶的橡胶复合材料滚动阻力也同时降低,可用于绿色轮胎材料。

This study is to examine if hydrogen-rich saline reduced amyloid-beta (A beta) induced neural inflammation and oxidative stress in a rat model by attenuation of activation of JNK and NF-kappa B. Sprague-Dawley male rats (n = 18,280-330 g) were divided into three groups, sham operated, A beta 1-42 injected and A beta 1-42 plus hydrogen-rich saline treated animals. Hydrogen-rich saline (5 ml/kg, i.p., daily) was injected for 10 days after intraventricular injection of A beta 1-42. The levels of IL-1 beta were assessed by ELISA analysis, 8-OH-dG by immunohistochemistry in the brain slides, and JNK and NF-kappa B by immunohistochemistry and western blotting. After A beta 1-42 injection, the level of IL-1 beta, 8-OH-dG, JNK and NF-kappa B all increased in brain tissues, while hydrogen-rich saline treatment decreased the level of IL-1 beta, 8-OH-dG and the activation of INK and NF-kappa B. In conclusion, hydrogen-rich saline prevented A beta-induced neuroinflammation and oxidative stress, possibly by attenuatation of activation of c-Jun NH2-terminal kinase (JNK) and nuclear factor-kappa B (NF-kappa B) in this rat model. (C) 2011 Elsevier Ireland Ltd. All rights reserved.

BACKGROUND:Amyloid β(1-42) (Aβ(42)) peptide vaccination has been proved to be effective in reducing amyloid burden in brain and improving cognitive function in Alzheimer's disease (AD) mouse models. But the phase II trial of Aβ(42) peptide vaccine was halted because of T cell-mediated meningoencephalitis. In this study, a DNA vaccine, p(Aβ(3-10))(10)-CpG, was constructed to test whether it would induce predominant T(H)2 immune response upon immunization of BALB/c mice.METHODS:BALB/c mice were vaccinated intramuscularly with p(Aβ(3-10))(10)-CpG plasmids. Aβ(42) peptide, pcDNA3.1(+) empty vector and PBS were injected to the control groups. Expression of interesting gene in injected muscle was identified by immunohistochemistry. Anti-Aβ antibody titers, isotype profiles as well as cytokines in ex vivo splenocytes culture supernatants were analyzed by enzyme-linked immunosorbent assay (ELISA).RESULTS:P(Aβ(3-10))(10)-CpG plasmid was expressed in muscle after injection detected by immunohistochemistry. The p(Aβ(3-10))(10)-CpG vaccine induced high titers of anti-Aβ antibodies in BALB/c mice. And isotype of the antibodies was mainly IgG1, the IgG1/IgG2a ratio for the p(Aβ(3-10))(10)-CpG group was approximately 5 times greater than that for the Aβ(42) peptide group. Ex vivo cultured splenocytes isolated from mice immunized with p(Aβ(3-10))(10)-CpG exhibited high interleukin-4 response and low interleukin-γ (IFN-γ) response.CONCLUSIONS:Immunization with p(Aβ(3-10))(10)-CpG vaccine primarily induces a T(H)2 type of response, thus reduces the probability of inflammation. This p(Aβ(3-10))(10)-CpG vaccine possesses the basic factors required for a safe and effective AD vaccine.

Alzheimer's disease(AD) is a common neurodegenerative disorder in aged humans.More and more evidence indicates that amyloid-β protein(Aβ),which is the major component of senile plague,plays critical roles in the onset and progression of AD.Rapid developments in molecular biology enable a new therapy strategy—DNA vaccine therapy.Genetic immunization:It's the method that the expression of the proteins encoded by genes in the animal's own cells induces immune response to combat the disease related specific proteins.It has been demonstrated in animal models and human clinical trials that DNA vaccine is effective in reducing and eliminating the Aβ burden.Combined literatures,this article summarized as follows on immune mechanism,active and passive immunotherapy of vaccine.

This study is to examine if hydrogen-rich saline reduced amyloid β (Aβ) induced neural inflammation, and learning and memory deficits in a rat model. S-D male rats (n = 84, 280–330 g) were divided into three groups, sham-operated, Aβ1-42 injected and Aβ1-42 plus hydrogen-rich saline-treated animals. Hydrogen-rich saline (5 ml/kg, i.p., daily) was injected for 14 days after intracerebroventricular injection of Aβ1-42. The levels of MDA, IL-6 and TNF-α were assessed by biochemical and ELISA analysis. Morris Water Maze and open field task were used to assess the memory dysfunction and motor dysfunction, respectively. LTP were used to detect the electrophysiology changes, HNE and GFAP immunohistochemistry were used to assess the oxidative stress and glial cell activation. After Aβ1-42 injection, the levels of MDA, IL-6, and TNF-α were increased in brain tissues and hydrogen-rich saline treatment suppressed MDA, IL-6, and TNF-α concentration. Hydrogen-rich saline treatment improved Morris Water Maze and enhanced LTP in hippocampus blocked by Aβ1-42. Furthermore, hydrogen-rich saline treatment also decreased the immunoreactivitiy of HNE and GFAP in hippocampus induced by Aβ1-42. In conclusion, hydrogen-rich saline prevented Aβ-induced neuroinflammation and oxidative stress, which may contribute to the improvement of memory dysfunction in this rat model.

We have successfully expressed recombinant mitochondrial‐type ferredoxin (mtFd) and ferredoxin:NADP+ reductase (mtFNR) from Cryptosporidium parvum and characterized their biochemical features for the first time for an apicomplexan. Both C. parvum mtFd (CpmtFd) and FNR (CpmtFNR) were obtained and purified as holo‐proteins, in which the correct assembly of [2Fe–2S] cluster in Fd and that of FAD in FNR were confirmed and characterized by UV/vis and electron paramagnetic resonance. These proteins were fully functional and CpmtFNR was capable of transferring electrons from NADPH to CpmtFd in a cytochrome c‐coupled assay that followed a typical Michaelis‐Menten kinetics. Apicomplexan mtFd and mtFNR proteins were evolutionarily divergent from their counterparts in humans and animals and could be explored as potential drug targets in Cryptosporidium and other apicomplexans.

通过磷酸酸解的方法制备了淀粉纳米晶,与天然胶乳共混沉淀,制备了淀粉纳米晶/天然橡胶纳米复合材料.利用扫描电镜研究了该纳米复合材料的微观结构,表明淀粉纳米晶以50～100 nm的片状颗粒分散在天然橡胶基体中.力学性能结果表明,淀粉纳米晶对天然橡胶具有较好的补强效果.动态力学性能分析表明,添加质量分数为5%的淀粉纳米晶的淀粉纳米晶/天然橡胶纳米复合材料抗湿滑性显著提高,可用作绿色轮胎材料.

Polystyrene-g-starch nanocrystals with different MS (mole ratio of grafted polystyrene and starch nanocrystals) were prepared by the grafting polymerization of starch crystals and styrene and characterized by FTIR and ~1H NMR. When the mole ratio of styrene monomer and starch nanocrystals (M/SN) was 2 and reaction time was between 8 and 12 h, the MS of copolymer was between 0.15 and 0.67. XRD experiments showed that the grafted polystyrene nearly had no change on the crystal type of starch nanocrystals, but induced the decrease of crystallinity with the increase of MS.

The pith of sunflowers is a kind of natural cellular material.In this paper,through scanning electron microscope(SEM) and optical microscope,a sunflower′s pith with compound structure and morphology was studied.The single cell shape deduced is a tetrakaidehedron.The compressive yield stress and modulus of the pith of the sunflower were tested.The effects of the cell shapes and structures of the pith on their mechanics properties and deformation mechanisms on compress have been studied and discussions about their reasons are made on the basis of the different models.The results show that the change of cell shape,from a normal tetrakaidehedron to the elongated one,is the main reason why the compressive modulus in the elongated direction increases 3 to 4 times than others,and the compressive yield stress over 2 times.

向日葵髓芯、高梁秆芯和玉米秆芯是一类具有良好力学性能的低密度天然泡沫体.基于仿生目的, 利用化学分析方法、光学显微镜和扫描电子显微镜对三种天然泡沫的化学组分、胞体形态结构与泡沫力学性能的关系进行研究.化学组分分析显示, 三种天然泡沫体的主要成分是纤维素、半纤维素和木质素, 它们的含量之和约为干基总量的75%.它们对泡沫性能的影响程度取决于一种与主成分含量有关的比值R, 并随R值的减小, 泡沫的回弹性下降, 而抗压强度和抗弯硬度则提高.通过对三种泡沫芯切面泡孔结构的比较观察, 得出向日葵髓芯由一种近似十四面体形状的胞体构成.而高粱秆芯和玉米秆芯则由一种近似六棱柱和一定数量的圆管状胞体构成, 这两种胞体形状对高粱秆芯和玉米秆芯的轴向力学性能有明显的增强作用.