木材溶液中羟基与异氰酸酯反应的研究

以涂料工业广泛应用的新型助剂二元酸酯 (DBE)为液化试剂 ,盐酸为催化剂 ,将苯甲基化木材溶液化后 ,与不同结构的异氰酸酯反应 .利用FT IR及1 3C NMR分析液化苯甲基木质纤维素与不同结构异氰酸酯得到了聚氨酯树脂 ,证明了木材中羟基可以用来作为聚醚多元醇与异氰酸酯制备聚氨酯材料 .通过准确测量体系中游离的NCO含量 ,从而得出不同结构异氰酸酯与木材溶液中羟基的反应规律 .实验结果表明 ,异氰酸酯的存在大大促进了木材结构中羟基的释放 ,由于不同异氰酸酯的活性不同 ,使得羟基值变化亦不相同 ,其顺序为IPDI>HDI>TDI .为了保证最终的材料性能 ,选择TDI和IPDI作为木材溶液制备聚氨酯树脂的异氰酸酯组份较好     

通过脱碳控制全球平均温度

Establishing a reliable method to predict the global mean temperature (T_e) is of great importance because CO₂ reduction activities require political and global cooperation and significant financial resources. The current climate models all seem to predict that the earth's temperature will continue to increase, mainly based on the assumption that CO₂ emissions cannot be lowered significantly in the foreseeable future. Given the earth's multifactor climate system, attributing atmospheric CO₂ as the only cause for the observed temperature anomaly is most likely an oversimplification; the presence of water (H₂O) in the atmosphere should at least be considered. As such, T_e is determined by atmospheric water content controlled by solar activity, along with anthropogenic CO₂ activities. It is possible that the anthropogenic CO₂ activities can be reduced in the future. Based on temperature measurements and thermodynamic data, a new model for predicting T_e has been developed. Using this model, past, current, and future CO₂ and H₂O data can be analyzed and the associated T_e calculated. This new, esoteric approach is more accurate than various other models, but has not been reported in the open literature. According to this model, by 2050, T_e may increase to 15.5 ℃ under "business-as-usual" emissions. By applying a reasonable green technology activity scenario, T_e may be reduced to approximately 14.2 ℃. To achieve CO₂ reductions, the scenario described herein predicts a CO₂ reduction potential of 513 gigatons in 30 years. This proposed scenario includes various CO₂ reduction activities, carbon capturing technology, mineralization, and bio-char production; the most important CO₂ reductions by 2050 are expected to be achieved mainly in the electricity, agriculture, and transportation sectors. Other more aggressive and plausible drawdown scenarios have been analyzed as well, yielding CO₂ reduction potentials of 1051 and 1747 gigatons, respectively, in 30 years, but they may reduce global food production. It is emphasized that the causes and predictions of the global warming trend should be regarded as open scientific questions because several details concerning the physical processes associated with global warming remain uncertain. For example, the role of solar activities coupled with Milankovitch cycles are not yet fully understood. In addition, other factors, such as ocean CO₂ uptake and volcanic activity, may not be negligible.     

杯[6]芳烃-双金属卟啉仿P-450酶模型的研究Ⅳ.对异丙苯氧化的催化行为

研究了杯[6]芳烃-双金属卟啉在氧化异丙苯中的催化行为，结果表明杯[6]芳烃-双金属卟啉比之相应的金属卟啉具有更高的催化活性，并表现同样的选择性，生成苯乙酮和醇组份。此一结果同通常酞菁或其它如西弗碱大分子金属络合物催化下生成丙酮和酚不同。还考察了温度、轴向配体、催化剂用量及金属离子种类等对反应的影响，仔细地通过测定反应速度比较了反应的活性。     

呼出气体酒精含量探测器检定的注意事项

介绍呼出气体酒精含量探测器的工作原理和国家标准对使用探测器的要求,为确保探测器有效准确的量值溯源,采用呼出气体酒精含量探测器自动检测系统进行检定。该系统能够解决标准气体不易保存和定值容易发生改变的难题,同时控制吹气压力,保证探测器采样的一致性,并列举了检定操作时应注意的问题和细节。     

微波灰化重量法测定卷烟纸中灰分

卷烟纸灰分是卷烟纸质量控制的一项重要指标,产生卷烟纸灰分的主要成分是纸中添加了碳酸钙等无机填充物,这些填充物可起到改善卷烟纸的透气度、调节卷烟纸的燃烧速率、提高卷烟纸的白度和不透明度、改善卷烟纸的手感和外观质量以及节约纤维用量等作用[1]。     

拉曼光谱法检测三甘醇中的水分含量

三甘醇是具有强烈吸湿性的粘稠液体,被用作石油天然气产品的新型干燥剂及脱水剂,在对三甘醇品质进行评价时,水分的含量是非常重要的指标。本文利用拉曼光谱技术,对三甘醇样品的拉曼光谱图进行采集,三甘醇标准品在波数129cm-1、321cm-1、531cm-1、830cm-1、886cm-1有较强的拉曼信号,以特征波数886cm-1的信号强度与对应的水分含量做标准曲线,得回归方程为y=-42.95x+4583.5,相关系数R2=0.9986,说明拉曼信号强度与三甘醇水分含量有良好的线性关系。选择水分含量为10%、15%、85%、95%的三甘醇溶液作为回测,平均回收率在90.1%~115.86%,相对标准偏差在0.43%~10.1%,该方法可准确检测三甘醇中的水分含量,且快速、操作简便、样品用量少,可用于现场检测。     

功能化离子液体液化木粉及其酚醛复合材料

合成了氯代1-(2-羟乙基)-3-甲基咪唑离子液体[He MIM]Cl、溴代1-乙胺基-3-甲基咪唑离子液体[Ae MIM]Br和氯代1-羧乙基-3-甲基咪唑离子液体[Ce MIM]Cl 3种功能化咪唑离子液体,并分别进行了红外与氢核磁结构表征.然后用3种离子液体液化木粉,液化3 h后向体系直接加入苯酚、甲醛和氢氧化钠,制备酚醛复合材料,并采用FTIR、XRD、DSC和SEM对酚醛复合材料进行结构、性能与形貌测试,研究离子液体种类对木粉液化率及酚醛树脂性能的影响.结果表明,离子液体及其液化木粉产物制备的酚醛复合材料性能得到明显改善.[Ce MIM]Cl液化效果最好,90℃液化率高达24.6%,当[Ce MIM]Cl与木粉质量比为10∶1时,制备的酚醛复合材料的游离醛释放量由原来的3.64%降低到0.92%.离子液体[Ae MIM]Br能将酚醛复合材料的冲击强度由原来的0.93 k J/m2提高到6.96 k J/m2,而[Ae MIM]Br及其液化的木粉产物制备的酚醛复合材料拉伸强度从原来的3.28 MPa提高到9.70 MPa.     

火焰原子吸收分光光度法测定维血康颗粒中总铁

建立火焰原子吸收分光光度法测定维血康颗粒中总铁的含量,火焰类型选择空气–乙炔,测定波长为248.3 nm,测定时间为4.0 s,燃气流量为0.9 L/min,以氘灯作为背景校正。铁的质量浓度在2.4~28.8μg/mL范围内与吸光度呈良好的线性,线性相关系数r~2=0.999 8。6次测定结果的相对标准偏差小于1.0%,样品加样回收率为93.89%,方法检出限为0.011 3μg/mL。该方法具有准确度高,稳定性、重复性好等优点,可用于维血康颗粒中总铁含量的测定。     

手持技术测定钙尔奇D片中的钙含量

利用二氧化碳传感器测定钙尔奇D片中的钙含量，解决二氧化碳含量不好直接测定的问题，帮助学生提升定量认识，同时体验多种数据记录与处理方式，感受信息技术的魅力。