TaNBR1, a Novel Wheat NBR1-like Domain Gene Negatively Regulates Drought Stress Tolerance in Transgenic Arabidopsis

Drought stress is an important factor that severely affects crop yield and quality. Autophagy has a crucial role in the responses to abiotic stresses. In this study, we explore TaNBR1 in response to drought stress. Expression of the TaNBR1 gene was strongly induced by NaCl, PEG, and abscisic acid treatments. The TaNBR1 protein is localized in the Golgi apparatus and autophagosome. Transgenic Arabidopsis plants overexpressing TaNBR1 exhibited reduced drought tolerance. When subjected to drought stress, compared to the wild-type (WT) lines, the transgenic overexpressing TaNBR1 plants had a lower seed germination rate, relative water content, proline content, and reduced accumulation of antioxidant enzymes, i.e., superoxide dismutase, peroxidase, and catalase, as well as higher chlorophyll losses, malondialdehyde contents, and water loss. The transgenic plants overexpressing TaNBR1 produced much shorter roots in response to mannitol stress, in comparison to the WT plants, and they exhibited greater sensitivity to abscisic acid treatment. The expression levels of the genes related to stress in the transgenic plants were affected in response to drought stress. Our results indicate that TaNBR1 negatively regulates drought stress responses by affecting the expression of stress-related genes in Arabidopsis.     

共混改性提高PVC耐热性的研究进展

从共混高分子耐热改性剂、添加无机填料及耐热性聚氯乙烯(PVC)树脂等方面总结了提高PVC耐热性的主要方法,并对各种改性方法进行了比较。     

‘Living’ free radical graft copolymers,II: Structure

Poly(vinyl chloride)–n-propyl xanthate (PVC–nPX) macroinitiators with 3 to 14 bonded xanthate groups per molecule were synthesized using PVC and potassium n-propyl xanthate. The reaction took place rapidly between 30 and 45°C. Ultraviolet (UV) and nuclear magnetic resonance studies confirmed the presence of xanthyl groups on these macroinitiators. The PVC–nPX macroinitiators were grafted by methyl methacrylate under UV irradiation of 254, 302 and 336 nm producing graft copolymers and homopolymers. The molecular weights increased with increasing conversion, which is consistent with a ‘living’ polymerization process. The active species in these polymerizations are believed to be macroradicals and xanthyl radicals.     

Effect of microwave heating on the migration of dioctyladipate and acetyltributylcitrate plasticizers from food-grade PVC and PVDC/PVC films into olive oil and water

Migration of dioctyladipate (DOA) and acetyltributylcitrate (ATBC) plasticizers from plasticized Polyvinylchloride (PVC) and polyvinylidene chloride (PVDC/PVC (Saran) films into both olive oil and distilled water during microwave heating has been studied. The plasticizer migrating into olive oil and water was determined using an indirect GC method after saponification of the ester-type plasticizer (DOA or ATBC) and subsequent collection of the alcohol component of the ester, namely: 2-ethyl-1-hexanol and 1-butanol, respectively. Migration was dependent on heating time, microwave power setting, the nature of the food simulant and the initial concentration of the plasticizer in the film. Migration of DOA into olive oil reached equilibrium after heating for 10 min at full power (604.6 mg DOA/1). Migration into distilled water was 74.1 mg/1 after 8 min of microwave cooking at full power. The amount of ATBC migrating into olive oil reached equilibrium after heating for 10 min at full power (73.9 mg ATBC/1). Migration into distilled water was 4.1 mg/1 after heating at full power for 8 min. Control samples containing olive oil gave DOA migration values which were significantly higher than the upper limit for global migration (60 mg/1) set by the European Community. It is proposed that PVC should not be used in direct contact with food in the microwave oven, while Saran may be used with caution in microwave heating and reheating applications, avoiding its direct contact with high fat foodstuffs.     

氯碱产品进出口状况分析

通过对1998年以来烧碱及聚氯乙烯的进出口情况的分析,指出在加入WTO以后国内 市场逐步国际化,提出了应对措施和建议。     

PVC蘸塑工艺研究

介绍在引发剂，反应活性增塑性的存在下，采用蘸塑工艺在异型金属表面包覆聚氯乙烯资料的工艺过程和工艺条件。     

聚氯乙烯抗冲击剂的研究进展

概述了聚氯乙烯抗冲击剂的性能要求、作用机理,介绍了主要的抗冲击剂品种和性能,并对聚氯乙烯抗冲击剂的应用现状及前景进行了综述。     

聚氯乙烯树脂热稳定性探讨

通过对聚氯乙烯降解机理的分析,提出在聚合体系中添加助剂并控制单体质量,改进工艺措施,提高PVC树脂制品的热稳定性。     

改性超细重质碳酸钙在硬质PVC中的应用

对超细重质CaCO3进行了湿法改性和复合改性,采用红外光谱图对改性后的超细重质CaCO3进行了表征,采用SEM观察了其在PVC基体中的分散情况及试样的冲击断面,测试了其对试样力学性能的影响。结果表明：对超细重质CaCO3进行表面改性后,铝酸酯接枝到了超细重质CaCO3表面,提高了超细重质CaCO3在PVC中的分散性,试样冲击断面存在着大量牵伸结构和拉丝现象,因而提高了试样的拉伸强度和冲击强度（当超细重质CaCO3用量为5份时拉伸强度最高,当超细重质CaCO.用量为15份时冲击强度最高）,且复合改性比湿法改性的效果好。     

PVC生产中电石粉尘的危害和治理

介绍了电石粉尘的危害和回收利用的方法及经济效益和环境效益。