Synthesis of [60]Fullerene‐Fused Tetralones via Palladium‐ Catalyzed Ketone‐Directed sp2 C?H Activation and sp3 C?H Functionalization

The palladium‐catalyzed ketone‐directed dual sp² C H activation and sp³ C H functionalization has been applied for fullerene functionalization for the first time. The sec‐alkyl aryl ketones have been exploited to react with [60]fullerene (C₆₀) to provide the novel and scarce C₆₀‐fused tetralones. The combined use of a highly active cationic palladium(II) catalyst and trifluoromethanesulfonic acid is crucial for the improvement of the reaction yield. A plausible reaction mechanism leading to the observed products has been proposed, and the electrochemistry of the fullerene products has also been investigated.

     

Design and Synthesis of 2‐Methyl‐7‐aminobenzoxazole as Auxiliary in the Palladium(II)‐Catalyzed Arylation of a beta‐Positioned C(sp3)?H Bond

A palladium(II)‐catalyzed direct arylation of methylene C(sp³) H bonds by 2‐methyl‐7‐aminobenzoxazole as an effective auxiliary is reported. This process exhibited high beta‐site selectivity, broad substrate scope, and compatibility with different functional groups with moderate to high yields up to 89%.

     

Easy Access to 1‐Amino and 1‐Carbon Substituted Isoquinolines via Cobalt‐Catalyzed C?H/N?O Bond Activation

A green atom‐economical method for the synthesis of highly functionalized 1‐amino and 1‐carbon substituted isoquinolines from the reaction of N′‐hydroxybenzimidamides and aryl ketoximes, respectively, with alkynes via pentamethylcyclopentadienylcobalt(III)‐catalyzed C H/N O bond activation is described. The external oxidant‐free annulation reaction uses the =NOH moiety in N′‐hydroxybenzimidamides or N‐aromatic ketone oximes as the directing group and internal oxidant. This first row transition metal‐catalyzed annulation serves as an efficient alternative for the synthesis of isoquinolines, as water is the only by‐product and expensive noble metals such as rhodium(III), iridium(III), palladium(II), and ruthenium(II) are not required. The reaction proceeds via C H activation, alkyne insertion, reductive elimination, and N O activation.

     

Pneumocandin Biosynthesis: Involvement of a trans‐Selective Proline Hydroxylase

Echinocandins are cyclic nonribosomal hexapeptides based mostly on nonproteinogenic amino acids and displaying strong antifungal activity. Despite previous studies on their biosynthesis by fungi, the origin of three amino acids, trans‐4‐ and trans‐3‐hydroxyproline, as well as trans‐3‐hydroxy‐4‐methylproline, is still unknown. Here we describe the identification, overexpression, and characterization of GloF, the first eukaryotic α‐ketoglutarate/Fe^II‐dependent proline hydroxylase from the pneumocandin biosynthesis cluster of the fungus Glarea lozoyensis ATCC 74030. In in vitro transformations with L ‐proline, GloF generates trans‐4‐ and trans‐3‐hydroxyproline simultaneously in a ratio of 8:1; the latter reaction was previously unknown for proline hydroxylase catalysis. trans‐4‐Methyl‐L ‐proline is converted into the corresponding trans‐3‐hydroxyproline. All three hydroxyprolines required for the biosynthesis of the echinocandins pneumocandins A₀ and B₀ in G. lozoyensis are thus provided by GloF. Sequence analyses revealed that GloF is not related to bacterial proline hydroxylases, and none of the putative proteins with high sequence similarity in the databases has been characterized so far.     

大豆基碱性多孔碳材料的制备与性能研究

介绍了一种简单快速,低成本的制备碱性掺氮多孔碳材料的方法。以富含蛋白质的天然大豆为碳源和氮源,经过碳化和水蒸气活化制备出了碱性多孔碳材料。采用N2物理吸附,扫描电镜,Boehm滴定,傅里叶变换红外以及CO2-TPD,元素分析等技术对所得碳材料进行了表征。结果表明,大豆中蛋白质氨基酸的氮元素在制备过程中被原位保留下来,使制得的活性炭表面具有较大量的碱性基团。并且碱性基团的含量随着活化时间的延长逐渐增加。当活化温度为800℃,活化时间为20 min时,所得活性炭的碱性基团含量达到5.496mmol/g。所得碳材料用于低浓度CO2的吸附,研究发现样品BC-sa-800-5对CO2和N2混合气体具有很好的分离效果,分离因子达到8.334。     

戊二醛与链霉素反应动力学的光谱学研究

根据朗伯比尔定律,建立戊二醛与链霉素标准曲线,用紫外分光光度法测定不同温度、浓度和反应时间下反应物的吸光度,计算单位时间内反应物浓度变化,进而得到该反应的动力学方程。结果表明,戊二醛与链霉素的反应较容易进行,属于四级反应,反应速率与各自浓度的二次方成正比,反应速率方程为ν=K[C戊二醛]2[C链霉素]2,反应的表观活化能为21.06 k J/mol。     

核桃壳活性炭的制备及其对烟酸缓释性能的研究

以二氧化碳(CO2)物理活化法制备了核桃壳活性炭,考察了活化温度、活化时间对核桃壳活性炭得率及烟酸吸附量的影响。以所制备的核桃壳活性炭为烟酸载体,在不同的释放介质(蒸馏水、人工胃液或人工肠液)中进行烟酸释放性能研究。结果表明,人工胃液和人工肠液能促进活性炭对烟酸的释放,其累计释放率分别达到43.96%和47.69%。核桃壳活性炭在3种不同介质中的不同释放阶段的释放过程均符合Higuchi模型。     

CLAM钢焊缝在550℃流动的铅铋合金中的腐蚀行为

为了研究中国低活化马氏体(CLAM)钢TIG焊缝在流动的铅铋共晶合金(LBE)中的腐蚀行为,对CLAM钢TIG焊缝及母材在550 ℃,不同相对流速(1.70,2.31,2.98 m/s)的LBE中进行1 500 h的腐蚀试验. 结果表明,腐蚀试样表面均存在双层结构的氧化层,外氧化层由疏松的Fe₃O₄组成,内氧化层由致密的(Fe, Cr)₃O₄组成;随着LBE相对流速的增加,提高了CLAM基体材料中的Fe,Cr元素向LBE中的溶解速率和LBE中的O元素向CLAM基体材料中的扩散迁移速率,加剧了试样表面的腐蚀程度,最终导致试样表面氧化层的厚度不断增厚;经过相同条件的腐蚀试验后,CLAM钢焊缝试样的抗腐蚀性能比母材试样低.     

钕铁硼在CuCl-EMIC离子液体中 电沉积铜层的研究

目的 开发一种新型的环保型钕铁硼表面镀铜技术。方法 采用CuCl-EMIC离子液体,对钕铁硼基体进行阳极活化前处理,在其表面电沉积铜。通过电化学工作站测试CuCl-EMIC离子液体的循环伏安曲线和镀铜样品的动电位极化曲线,运用扫描电子显微镜、能谱分析仪和X射线粉末衍射仪,考察钕铁硼基体和铜镀层的微观形貌、成分组成和相结构,利用粗糙度仪和拉拔试验仪检测钕铁硼表面的粗糙度和其上铜镀层的结合力。结果 物质的量之比为2∶3~3∶2的CuCl-EMIC离子液体在室温下熔融,可在其中电沉积得到晶态铜。物质的量之比为1的CuCl-EMIC离子液体有更大的还原峰值电流密度。钕铁硼基体经过20~ 30 mA/cm2的电流密度阳极活化后,表面变得平整,孔洞减少,活化后钕铁硼表面的铜镀层均匀致密,结合力达9.2 MPa以上。钕铁硼表面铜镀层的孔隙率随着镀层厚度的增加而减小,当厚度为6 μm时,镀铜试样的腐蚀电位与纯铜相近,孔隙率为0.005 23%。结论 采用物质的量之比为1的CuCl-EMIC离子液体,可以通过阳极活化得到平整、孔洞少和无氧化膜的钕铁硼基体表面,在其上电沉积可得到致密均匀且结合力好的薄铜层。     

基于深度信念网络和多信息融合的复杂机电装备故障诊断方法

针对复杂机电装备故障诊断中存在的数据量大、提取故障特征困难等问题,结合深度学习理论强大的感知与自我学习能力,提出一种基于深度信念网络和多信息融合的复杂机电装备故障诊断方法。将多个传感器的原始时域信号数据输入深度信念网络进行训练,通过反向微调学习对深度信念网络进行整体微调,提高分类准确性,同时在训练过程采用ReLu激活函数和加入Batch Normalization,减少过拟合出现概率的同时提高了网络收敛的速度。将此方法运用到复杂数控加工中心刀具的故障诊断中,结果表明该方法相比传统BPNN算法和采用Sigmoid激活函数的深度神经网络算法准确率更高。