长链酰胺化纳米纤维素增强聚乳酸复合材料

以纳米纤维素(NCC)为原料,先采用四甲基哌啶氮氧化物(TEMPO)氧化制备氧化纳米纤维素(TONC),再与不同链长脂肪胺在催化剂作用下发生反应,得到脂肪胺改性纳米纤维素,当脂肪胺为十二胺(DOA)、十四胺(TEA)、十六胺(HEA)、十八胺(OCA)时,分别制得DOATONC、TEATONC、HEATONC和OCATONC。傅里叶变换红外光谱(FT-IR)、X射线衍射(XRD)和元素分析表明:脂肪链接枝成功,改性后纳米纤维素的晶形没有发生改变,为原有Ⅰ型晶型;接触角和分散性测试表明:随着脂肪链的增长,改性纳米纤维素表面的亲水性明显下降(接触角由65.8°上升至93.9°),而分散率由25.17%先降至11.97%,再升至71.71%。将1%的改性纳米纤维素添加到聚乳酸(PLA)中制得复合膜,机械性能测试结果表明:随着脂肪链的增长,复合膜的机械性能明显提高,其中PLA/OCATONC复合膜的拉伸强度和断裂伸长率分别达到40.2 MPa和6.39%。     

Mechanism and Progress About Protein Crystal Growth by Atomic Force Microscopy

Atomic Force Microscopy(AFM) plays a very important role in researching crystal growth mechanism, especially protein crystals. The principle of AFM for protein crystal examination is briefly described as well as the importance of research on protein crystal growth, known growth mechanisms including 2-D steps nucleation, spiral dislocation, normal growth, 3-D nucleation and anisotropic development, and latest progress about eucommia antifungal protein(EAFP) and Trichosanthin(TCS) protein crystal growth mechanism, respectively. Finally, protein growth under microgravity environment is also expounded here and their development tendency and practical prospect.     

生物质基光学材料研究进展

近年来由于不可再生资源的日益枯竭,以及全球能源危机等问题,生物质资源的研究和利用受到人们的广泛关注。以往材料的制备与合成往往以石油及其衍生物为原料,过程繁琐、成本高昂、原料不可再生,且对生态环境造成了不可逆转的破坏,而生物质基材料因绿色、可再生、环境友好等,其设计与构筑已成为基础科技研究的前沿与热点。在过去的研究中,国内外学者以相关生物质为基础构筑“基石”,利用其本征结构及特性原位合成或与异质单元复合,构筑了大量的功能光学材料。功能光学材料的应用领域包括但不限于催化、光动能转换、生物成像、光电器件、海水淡化、信息防伪等。笔者对生物质基光学功能性材料方面的代表性成果进行梳理与总结,主要包括林木芳香生物质荧光材料、多糖生物质荧光材料、林木生物质光热材料、纳米纤维素光子晶体材料、生物质基光热材料,以及以上材料在食品检测、生物成像、加密打印、发光器件、光 热 动能转换领域中的应用,并且对该领域内存在的问题及未来发展方向作了展望。     

Massive uric acid crystalluria and cylinduria in a dog after l‐asparaginase treatment for lymphoma

A 10‐year‐old golden retriever bitch was treated for diarrhea and vomiting that lasted about 1 month without a specific diagnosis until a hepatic biopsy provided a histopathologic diagnosis of lymphoma. The dog was referred to the Swedish University of Agricultural Science and treated with one dose of l ‐asparaginase. The day after chemotherapy, the urine was dark yellow, very turbid, and had large amounts of small amorphous crystals and many casts made of similar appearing material identified by infrared spectroscopy to be 100% uric acid dihydrate. Serum uric acid was elevated at 224 μmol/L (RI 0‐59). The dog's illness became worse after chemotherapy. Lymphoma treatment was not continued, and the dog was euthanized 9 days after the l ‐asparaginase treatment. Among other problems were persistent proteinuria with a urine protein‐to‐creatinine ratio of 2.3 and severe hypoalbuminemia. Serum protein electrophoresis performed 3 weeks prior to chemotherapy indicated hyperproteinemia (total protein 78 g/L) having a biclonal gammopathy with 35 g/L β‐2 globulins and 11 g/L γ globulins. Despite prominent cylinduria and crystalluria, the patient did not develop azotemia or isosthenuria.     

暗纹东方鲀冻藏品质劣化的原因解析

通过比较冰晶、内源蛋白酶以及氧化对冻藏暗纹东方鲀(Takifugu obscurus)品质的影响,确定冻藏暗纹东方鲀品质劣化的关键因素。实验通过液氮浸渍快速冻结抑制鱼肉组织中冰晶增长、碘乙酸浸泡前处理抑制鱼肉内源蛋白酶活性、复合抗氧化剂浸泡前处理抑制蛋白/脂质氧化作用的设计,区分冰晶、内源蛋白酶和氧化3种因素对冻藏鱼肉品质的影响;并以硬度、解冻流失率、蒸煮损失率、挥发性盐基氮含量、K值、Ca2+-ATPase活性、肌原纤维小片化指数和肌纤维长度作为鱼肉品质的评价指标。结果显示,冻结过程中控制冰晶增长对暗纹东方鲀冻藏品质的改善作用最大,冻藏24周后,速冻组的硬度比内源蛋白酶抑制组和氧化抑制组分别提高了26.8%和20.5%,解冻流失率分别降低了44.2%和44.8%,且该处理组TVB-N、K值和Ca2+-ATPase活性变化更慢,24周后分别为10.5 mg/100 g、6.8%和1.43 μmol Pi/mg/10 min。综合各项指标发现,冰晶、内源蛋白酶和氧化对冻藏暗纹东方鲀品质劣化均有影响;其中,冰晶作用是导致暗纹东方鲀在冻藏过程中品质下降的最主要影响因素,内源蛋白酶和氧化对冻藏暗纹东方鲀品质的影响次之,且二者对品质影响无显著性差异。     

4种方法从葎草中制备的纳米纤维素性能

以葎草(Humulus scandens)为原料,分别采用4种方法制备了纳米纤维素,分别为硫酸水解所制得的纤维素纳米晶须(sulfuric acid-cellulose nanocrystals,S-CNC)、盐酸水解法制得的纤维素纳米晶须(hydrochloric acid-cellulose nanocrystals,H-CNC)、大功率超声法制得的纤维素纳米纤维(ultrasound-cellulose nanofibrils,U-CNF)和高速搅拌法制得的纤维素纳米纤维(stirring-cellulose nanofibrils,S-CNF),然后采用透射电子显微镜(TEM)、傅利叶红外光谱仪(FTIR)、X射线衍射仪(XRD)、热重分析仪(TGA)分别对4种纤维素的形态、化学结构、晶体结构、热稳定性能进行了表征。结果表明,硫酸水解法和盐酸水解法制备的纳米纤维素呈棒状,大功率超声法和高速搅拌法制备的纳米纤维素呈网状;S-CNC具有最高的结晶度(70.05%),而S-CNF结晶度最低(58.94%);4种纳米纤维素均保持着纤维素Ⅰ型结构;U-CNF的热稳定性最佳,开始分解温度为261.9℃,而S-CNC的热稳定性最差,初始分解温度为217.8℃。     

Biomass,Mineral Accumulation,and Calcium Crystals in Trema micrantha (L.) Blume as a Function of Calcium Carbonate Addition

Trema micrantha (L.) Blume is a neotropical multipurpose tree species, which could be used in forest restoration and agroforestry. Several cultures, however, require liming to satisfactory yields in acid soils. Therefore, it is important to determine the effect of liming to this native species, in order to include it in agroforestry associations. The aim of this work was to evaluate the morphological changes of T. micrantha, including the calcium oxalate (druses) and cystolith density, as caused by the calcium carbonate (CaCO₃) addition. The assay included three treatments: control, pH 5.3; treatment 1, pH 5.5; treatment 2, pH 6.0. The liming reduced the root biomass and increased the shoot biomass. The leaf specific mass and nutrients concentration were not changed. The leaves presented higher density of druses in treatment 2. The cystolith density was not modified, but the cystolith size was increased by the liming. The results indicate liming tolerance in this species.     

Effect of quick-freezing temperature on starch retrogradation and ice crystals properties of steamed oat roll

Oat roll is one of the traditional oat wholemeal foods. The purpose of this work was to investigate the effects of quick freezing at −20 °C, −40 °C and −80 °C for 90 min before frozen storage on the quality of frozen steamed oat roll. Quick freezing at −40 °C and −80 °C inhibited the increase of peak gelatinization temperature, enthalpy and the ordered degree of oat roll starch, therefore postponing starch retrogradation. The cross-section microstructure confirmed that reducing the quick-freezing temperature could prevent the increase of ice crystals size, ruptured structures and maintain the integrity of internal structure. As the storage time extend, the ice recrystallization led to an increase in size of ice crystals, while a decrease in their number. Frozen steamed oat roll starch had the highest swelling power at the quick-freezing temperature of −80 °C, that indicated strongest water absorption and binding ability when gelatinized again. Texture analysis demonstrated that hardness increased during frozen storage, quick freezing at −80 °C had the best texture properties. Therefore, declining the quick-freezing temperature could obtain a higher quality of frozen steamed oat roll, by means of delaying the starch retrogradation and minimising the size of ice crystals.     

Manganese modulates the responses of nitrogen-supplied and Rhizobium-nodulated Phaseolus vulgaris L. to inoculation with arbuscular mycorrhizal fungi

In Venezuela, low yields of black bean crops are attributed, in part, to the low manganese (Mn) and phosphorus (P) contents in the Quartzipsamment soils where this crop is usually sown. To test this hypothesis, black bean plants were grown in sterilized sand to simulate soil physical properties, were fertilized with increasing Mn concentrations (0.1-20 μM) and inoculated with a commercial mixture of Rhizobium leguminosarum bv phaseoli strains 127K44, 127K89, 127K105 (+Rh), in combination with arbuscular mycorrhizal fungi Scutellospora heterogama and Entrophospora colombiana (+AMF). Non-inoculated plants fertilized with 6 mM NO₃ and 2 mM P served as controls. Plants were harvested at 18, 25, 33, and 40 days after emergence. At all harvests, the greatest growth and highest P and iron (Fe) leaf concentrations occurred in control plants grown in 5 μM Mn. The growth of +AMF plants was promoted at 0.1 μM Mn and inhibited at higher than 1 μM Mn. Whereas, concentrations of 5-10 μM Mn enhanced the growth and the Mn concentrations in leaves of +Rh plants 40 days after emergence. The tripartite symbiosis (+Rh+AMF) decreased growth, nodulation and leaf ureide and chlorophyll concentrations in plants grown in less than 20 μM Mn, imputed to severe ultrastructural alterations in the leaf and nodule tissues. Only +Rh+AMF plants grown in 20 μM Mn were effectively nodulated, AMF colonized and reached the flowering stage, although with diminished growth and low chlorophyll concentrations. Results confirm the high Mn requirement of +Rh plants for growth and nodulation and question the implementation of the tripartite symbiosis to improve yields in early flowering black bean varieties planted in soils deficient in Mn and P.