5-取代氧化呋咱并[3,4-b]吡啶衍生物的合成与表征

以廉价易得的2,6-二氯吡啶为原料,经过硝化、叠氮化、热解环化步骤得到中间体[1,2,5]噁二唑并[3,4-e]四唑并[1,5-a]吡啶-3-氧化物(4b),再与浓硫酸/硝酸钾、甲醇钠和甲胺水溶液反应分别得到5-取代的氧化呋咱并[3,4-b]吡啶衍生物5~7。 研究了化合物4b结构的稳定性,发现其中的氧化呋咱环在强酸性、强碱性和弱碱性条件下较稳定,而吡啶环与叠氮基形成的四唑环结构则不太稳定。     

前轮驱动自行车机器人定车运动的鲁棒控制实现

针对一种前轮驱动的自行车机器人,研究其在具有内部结构参数和外部环境不确定性因素下实现原地定车的控制方法;给出基于Lagrange方法的定车运动简化力学模型;提出以欠驱动的车架横滚角为输出,将有驱动的前轮转角作为系统内部动态考虑的鲁棒控制器;仿真结果表明,控制器可以实现快速稳定的定车,并且对系统50%的结构参数误差、幅值为1N.m正弦干扰力矩和幅值为10N.m的脉冲干扰力矩体现了较强的鲁棒性;物理样机实验进一步证明,控制器可以在凹凸不平的地面环境、传感器数据不精确及脉冲干扰力矩下实现±3°车架倾角范围的定车运动。     

Accelerated,untargeted metabolomics analysis of cutaneous T‐cell lymphoma reveals metabolic shifts in plasma and tumor adjacent skins of xenograft mice

Cutaneous T‐cell lymphoma (CTCL) is a heterogeneous group of skin‐homing T‐cell neoplasms. Clinical management is stage based but diagnosis and prognosis could be extremely challenging. The presented study aims to explore the metabolic profiling of CTCL by an accelerated untargeted metabolomics data analysis tool “Mummichog” to facilitate the discoveries of potential biomarkers for clinical early stage diagnosis, prognosis, and treatments in CTCL. Ultra high‐performance liquid chromatography–quadrupole time‐of‐flight–based untargeted metabolomics were conducted on the skin and plasma of CTCL mice. It showed that the metabolism of skin changed greatly versus control samples in the development of CTCL. Increased l ‐glutamate and decreased adenosine monophosphate were the most essential metabolic features of CTCL tumor and tumor adjacent skins. Unique metabolism changes in tumor adjacent non‐involved skin tissues (ANIT) occurred in the progress of carcinogenesis, including upregulated cytidine‐5′‐triphosphate, aberrant biosynthesis of prostaglandins, pyrimidine, mevalonate pathway, and tryptophan degradation. Sharply elevated 5‐phospho‐α‐d ‐ribose 1‐diphosphate (PRPP) marked the final state of tumor in CTCL. In the plasma, systematic shifts in corticosterone, sphingolipid, and ceramide metabolism were found. These uncovered aberrant metabolites and metabolic pathways suggested that the metabolic reprogramming of PRPP in tumor tissues may cause the disturbance of cytidine and uridine metabolic homeostasis in ANIT. Accumulative cytidine‐5′‐triphosphate in ANIT may exert positive feedback on the PRPP level and leads to CTCL further development. In addition, the accelerated data analysis tool “Mummichog” showed good practicability and can be widely used in high‐resolution liquid chromatography mass spectrometry–based untargeted metabolomics.     

Preparation of polypropylene/silica composites by in-situ sol–gel processing using hyperbranched polyethoxysiloxane

Based on a volatile-free silica liquid precursor polymer—hyperbranched polyethoxysiloxane (PEOS), an industrial compatible in situ sol–gel process for the preparation of polymer/silica nanocomposites has been developed. It has been shown that in the presence of a catalyst water vapor induced a fast conversion of liquid PEOS to solid silica in polypropylene (PP) melt in a twin-screw microcompounder. Solid state NMR showed that the in situ conversion of PEOS proceeded to a large extent. With small amounts of PEOS this procedure yielded PP/silica composites with particle size less than 100 nm. The particle size increased with the PEOS amount blended with PP. Nevertheless, the particles were observed to be homogeneously dispersed within the polymer matrix. PP/silica composites prepared by in situ sol–gel technology showed improved thermal properties, but almost not affected mechanical properties in comparison with pure PP.     

Graphical Abstract: HCA 1/2003

The low solubility of pterins can drastically be improved by N²‐acylation or formation of the N²‐[(dimethylamino)methylene] derivatives. Both types of compounds can be alkylated under Mitsunobu conditions to form from N²‐acylpterins (see 2 and 3 ) and their derivatives (see 5, 6, 8, 9, 11, 13, 15 , and 17 ) selectively the O⁴‐alkyl derivatives 22 – 31 , whereas the electron‐donating [(dimethylamino)methyleneamino function in 46 – 51 gives, in a selective reaction, the N(3)‐substitution (→ 52 – 61 ). N²,N²‐Dimethylpterins and 18 and 19 and N²‐methylpterins 20 and 21 direct alkylation also to the O⁴‐position (→ 32 – 35, 38 and 39 ). Deacylation can be achieved under very mild conditions by solvolysis with MeOH ( 22 → 40, 26 → 41 ), and displacement of the O⁴‐[2‐(4‐nitrophenyl)ethyl] group proceeds with ammonia at room temperature to the corresponding pteridin‐2,4‐diamines 42 – 45 . Cleavage of the N²‐[(dimethylamino)methylene] group works well with ammonia (→ 62 – 67 ). The advantage of applying the 2‐(4‐nitrophenyl)ethyl (npe) group as blocking group is seen in its selective removal by 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) under aprotic conditions without harming the other substituents.     

毛细抽吸回路中反向式蒸发器内汽、液两相流动的理论分析

本文在建立物理模型的基础上，采用了一个二维计算模型对CPL的单个蒸发器的管内两相流动状态进行了分析和数值计算，分别得出汽、液相流体的速度、压力的分布．并完成系统的过程分析．     

光解苯半醌自由基的CIDEP谱

用高时间分辨ESR谱仪实验给出了光解对苯醌产生的苯半醌自由基的CIDEP发射谱.用三重态机理,同时考虑了自由基对机理的影响,从理论上分析了极化强度,计算出了增强因子V(Ⅰ)=-0.66,V(R)=0.2,一级反应速率k_1,A=0.05/μs,二级反应速率β=0.02/μs,横向和纵向弛豫时间T₁≈T₂=2.3μs.     

Unveiling Atom Migration Abilities Affected Anode Performance of Sodium-Ion Batteries

In sodium-ion batteries (SIBs), the low initial coulombic efficiency (ICE) is commonly induced by irreversible phase conversion and difficult desodiation, especially on transition metal compounds (TMCs). Yet the underlying physicochemical mechanism of poor reaction reversibility is still a controversial issue. Herein, by using in situ transmission electron microscopy and in situ X-ray diffraction, we demonstrate the irreversible conversion of NiCoP@C is caused by the rapid migration of P in carbon layer and preferential formation of isolated Na₃P during discharge. By modifying the carbon coating layer, the migration of Ni/Co/P atoms is inhibited, thus the improvement of ICE and cycle stability is realized. The inhibiting of fast atom migration which induces component separation and rapid performance degradation might be applied to a wide range of electrode materials, and guides the development of advanced SIBs.     

半透明平板边界入射辐射热流密度的反问题

对一维半透明平板内辐射、导热及边界对流耦合换热过程进行了研究。提出了一种由一侧边界出射辐射强度反演另一侧边界入射辐射热流密度的方法。通过对各向异性散射、吸收系数、散射系数、边界外侧来流温度、对流换热系数、半透明平板的导热系数和平板厚度等参数对反演精度影响的分析表明,方法是可行的。     

求解辐射传递方程的离散坐标法

阐述了含吸收散射性介质三维空腔内辐射传递方程的离散坐标解法。讨论了入射散射项积分格式的选取,以及假散射和射线效应对解精度的影响。对三维矩形炉膛内辐射传递过程进行了数值模拟,并与区域法和离散传递法进行比较。比较结果表明离散坐标法具有较好的精度,是目前燃烧室内辐射传热过程数值模拟的一种较好的方法。