An improved method for extraction of sorghum polymeric protein complexes

A method for fractionating sorghum proteins using extraction solvents and techniques designed to obtain polymeric protein structures (especially disulfide linked) was developed. Extraction and separation conditions were optimized in terms of completeness of protein extraction, sample stability, and analytical resolution. After pre-extraction of albumins and globulins, a 3-step sequential procedure involving no reducing agents was applied to ground whole sorghum flour. The three fractions obtained represented proportionally different protein polymer contents and molecular weight distribution as evidenced by comparative size exclusion chromatography. Protein composition also varied among the extracts with differences in kafirin composition and non-kafirin proteins detected in the fractions by RP-HPLC and SDS-PAGE analysis. The ability to quantify and further characterize sorghum polymeric protein complexes will be useful for additional studies linking protein structures with functionality and digestibility and variations for these properties within diverse sorghum germplasm.     

The effects of sodium reduction on the mechanical properties of doughs made from flours with a range of strengths using a mixograph

To devise strategies for meeting Health Canada's target for reduced-sodium bread production, relationships between dough formula (i.e., red spring wheat flour, salt (NaCl) and water content) and dough mechanical properties were examined. Mixograph energy to peak (ETP), peak height (PKH), and peak bandwidth (PBW) were used to define changes in the properties of doughs induced by sodium reduction. ETP measurements indicated that dough strength characteristics were less responsive to sodium reduction as water content was increased. ETP was a good indicator of the cultivar-dependent response of doughs to sodium reduction, with doughs made from stronger flours being more sensitive to sodium reduction. According to ETP results, sodium reduction led to a decrease in flour strength discrimination. Sodium reduction at NaCl contents below ~1.5% led to more obvious changes in dough mixing characteristics (indicated by the ratio of PBW to PKH). Mixograph analyses of dough tolerance to sodium reduction will guide wheat breeding programs to select cultivars suitable for reduced sodium breadmaking.     

Gelation characteristics of Mesona chinensis polysaccharide-maize starches gels: Influences of KCl and NaCl

An investigation was conducted into the effects of potassium chloride (KCl) and sodium chloride (NaCl) on the gelation properties of maize starch-Mesona chinensis polysaccharide (MCP) gels. Waxy maize starch (WS), normal maize starch (NS), and high amylose maize starch (HS) were used to compare the effects of different amylose contents on the gel properties of maize starch-MCP gels. The results showed that KCl and NaCl have similar effects on the gelation, rheological, and structural properties of maize starch-MCP gels. The addition of KCl and NaCl increased the pasting viscosity, breakdown values, setback values, dynamic modulus, and apparent viscosity of maize starch-MCP gels, especially for HS-MCP gels. LF-NMR (Low-field nuclear magnetic resonance) showed that salts reduced bound water content while increasing the free water content of maize starch-MCP gels. CLSM (Confocal laser scanning microscopy) results also indicated that salt can restrict the expansion and maintain the integrity of starch granules, especially for WS-MCP gels.     

不同浓度褪黑素对氯化钠胁迫下宝岛蕉幼苗的影响

为了研究不同浓度褪黑素对于宝岛蕉幼苗氯化钠胁迫的影响，通过不同浓度褪黑素处理宝岛蕉幼苗叶片，研究其对宝岛蕉幼苗叶片和根系的可溶性糖含量、MDA含量、脯氨酸含量及叶质膜透性的影响。结果表明，100μmol/L褪黑素能够降低宝岛蕉幼苗叶质膜透性，提高叶片和根系可溶性糖含量，降低叶片和根系MDA含量，提高叶片和根系脯氨酸含量，提高幼苗的耐盐性，以缓解氯化钠胁迫对宝岛蕉幼苗的伤害。     

磺胺间甲氧嘧啶钠注射液含量测定的能力比对结果分析

为加强兽药检验检测机构能力建设,进一步提升检测技术水平,组织开展了全国省级兽药检验机构磺胺间甲氧嘧啶钠注射液含量测定的能力比对。依据《中国兽药典》2020年版一部附录0701电位滴定法与永停滴定法以及中国合格评定国家认可委员会（CNAS）规定的程序进行本次能力比对。分别采用单因子方差分析法和Ss≤0.3σ准则对测试样品进行均匀性检验,采用t检验方法和■准则对样品进行稳定性考察,采用Z比分数评价各参加实验室的测试结果。参加本次能力比对的36家兽药检测实验室中,33家结果为满意,满意率91.7%。     

胶合板用硅镁系环保无机胶黏剂制备与阻燃性能研究

以硅酸钠、硅酸铝、氧化镁和硅烷偶联剂为原料,制备胶合板用硅镁系硅酸盐无机胶黏剂。采用单因素试验和正交试验考察了主要成分用量对胶黏剂的胶合性能的影响,并采用锥形量热分析技术和热重法分别测试其阻燃抑烟性能以及耐热性能。结果表明,当硅酸钠的质量分数为92.5%,硅酸铝的质量分数为4.7%,氧化镁的质量分数为2.8%,硅烷偶联剂的百分比含量为0.6%(相对于硅酸钠的质量而言)时,改性胶黏剂的综合性能最好,其胶合强度达到0.85MPa,阻燃抑烟性能效果显著,热释放总量和热释放速率明显降低。     

有机改良剂对温室土壤及番茄质量的影响

研究了优培-海藻生物有机肥(Y)、微生物菌肥(W)和腐植酸有机肥对日光温室土壤的理化性质、有效态微量元素含量、酶活性以及番茄品质等方面的影响,旨在探索快速、简易且廉价的土壤改良方法,为日光温室土壤改良及有机蔬菜生产提供理论依据。结果表明,不同土壤改良剂对土壤p H无显著影响,在番茄生育期内土壤p H值始终在7.0以上,没有出现酸化问题;拉秧后,除中量腐植酸有机肥(FM)外,其他各处理均能有效降低土壤EC值并达到极显著水平;各处理对提升有效态Mn、Zn和Fe含量的效果不显著,其中,仅高量腐植酸有机肥处理(FH)能同时提高开花结果盛期0~20 cm和20~40 cm土层的有效态Zn含量,与CK相比,分别增加10.8%和13.2%;不同土壤改良剂均可提高土壤脲酶和蔗糖酶活性;不同土壤改良剂对碱性磷酸酶的酶活性影响较小;微生物菌肥对酸性磷酸酶和过氧化氢酶的酶活性影响相对明显;不同土壤改良剂均能提高番茄可溶性固形物、可溶性糖、可滴定酸和维生素C的含量,其中,中量腐植酸有机肥处理提高了番茄的糖酸比。土壤改良剂可有效改善日光温室土壤特性及番茄品质。     

海藻酸钠-聚乙烯醇交联微球制备参数优化研究

采用海藻酸钠和聚乙烯醇为包埋剂，选取交联时间、海藻酸钠和聚乙烯醇用量比（SA ∶ PVA）以及海藻酸钠和聚乙烯醇的总浓度为影响因素设计L49（52×7）正交实验，探讨包埋的最佳理化条件。以包埋材料的成球效果，包埋小球的硬度、弹性及微观结构为考察指标，比较包埋小球性能，探讨包埋条件。结果发现当SA ∶ PVA为7 ∶ 3，总浓度为4％，交联时间为24 h时包埋效果最佳。     

Semi-quantitative method to evaluate the α-carbonyl content in lignin

A method to estimate the content of -carbonyl structures in lignin was developed. This method consists of two successive treatments: NaBD₄ treatment of pulp to reduce an -carbonyl structure in lignin, and nitrobenzene oxidation. NaBD₄ was used to convert an -carbonyl structure to a deuterium-labeled hydroxymethine structure. The ratio of D-vanillin [(HO)(H₃CO)C₆H₃CDO] to H-vanillin [(HO)(H₃CO)C₆H₃CHO] or that of their syringyl analogues obtained by nitrobenzene oxidation was used as the measure of the content of -carbonyl structure. Model experiments demonstrated that when sodium hydroxide was used as alkali for the nitrobenzene oxidation, the retention of deuterium at the side chain -position was very low due to the displacement of deuterium with hydrogen by an unknown reaction mechanism. In order to depress this unexpected displacement, the reaction conditions of the nitrobenzene oxidation were modified. The modified nitrobenzene oxidation employs 0.5mol/l of lithium hydroxide as a reaction medium instead of 2.0mol/l sodium hydroxide. By this modification, this method could successfully trace the formation and the degradation of the -carbonyl structure in milled wood lignins.This paper was presented in part at the 11th International Symposium on Wood and Pulping Chemistry, Nice, France, June 2001 and at the 46th Lignin Symposium, Kyoto, Japan, November 2001