Synthesis and characterization of cyclophane: The highly selective recognition of Fe3+ in aqueous solution and H2PO4− in acetonitrile solution

In this work, we report a series of cyclophane fluorescent sensors based on acridine combining with imidazolium through ether linkages. X-ray crystal structures demonstrated the self-assembly behavior of these cyclophanes in the solid state driven by hydrogen bond and π–π interactions. Sensors showed excellent selectivity towards Fe³⁺ in aqueous solution (H₂O/CH₃CN?=?49:1, v/v) and H₂PO₄^? in acetonitrile solution with notable color change under UV light, evident changes were also noticed in fluorescence spectra. In fluorescence emission, the obvious turn-off was induced by Fe³⁺ in aqueous solution and the obvious turn-on as well as bathochromic-shift was induced by H₂PO₄^? in acetonitrile solution.     

不同碱基物质对燃煤烟气脱氯的影响

实验探究NaOH、Na₂CO₃、NaHCO₃这三种常见的碱基物质在模拟燃煤烟气中的实际表现,发现三种碱基物质均具有一定的脱氯性能,NaOH、Na₂CO₃、NaHCO₃的脱氯性能依次下降,以脱氯效率70%为目标,使用三种碱基物质Na/Cl比分别需要达到5.8、7.1、8.7。高浓度SO₂的存在对烟气脱氯有竞争作用,随着SO₂浓度的提高,脱氯效率线性下降,不同碱基物质下,SO₂浓度对脱氯效率的影响规律基本一致,SO₂浓度每增加100 mg/m³,脱氯效率下降约1.4%。由于三种碱基物质达到相同脱氯效率时的Na/Cl比不同,综合考虑成本和溶解性,NaOH最具工业应用价值。     

低阶煤热萃取物与瘦煤共炭化焦炭的微观结构及显微强度研究

以众唯瘦煤作为主炼焦煤,大同长焰煤萃取物作为添加剂,进行共炭化处理制备坩埚焦。利用偏光显微镜法定量研究焦炭光学显微组分,获得焦炭的各向异性指数(DRAS);采用XRD及分峰拟合的方法研究了焦炭的微晶粒径(L_c)、芳香缩合度(I_a)、石墨化度(g);利用Raman光谱结合分峰拟合的方法研究了焦炭中理想石墨微晶含量(I_g)。对所得焦炭的光学显微组分进行定量分析发现:大同长焰煤热解萃取产物的添加对共炭化焦炭的光学显微组分有显著的影响,利用偏光显微镜法计算出焦炭的DRAS与XRD和Raman计算的焦炭微晶参数呈现很好一致性。并且,焦炭的显微强度与其微观结构关联性极大。     

固定化β-葡萄糖醛酸酶反应器的制备及其在4-甲基亚硝胺基-1-(3-吡啶)-1-丁醇的O-糖苷化合物分析中的应用

采用溶胶-凝胶法,以丙烯酰胺作为单体,制备了基于有机-硅胶杂化整体柱的β-葡萄糖醛酸酶反应器。优化了硅酸甲酯和γ-(甲基丙烯酰氧)丙基三甲氧基硅的物质的量的比、丙烯酰胺和聚乙二醇的用量,以及水浴温度等制备条件,获得了孔隙均匀、通透性良好、机械强度高的有机-硅胶杂化整体柱。采用光学显微镜和扫描电镜表征杂化整体柱。进一步将β-葡萄糖醛酸酶共价键合在整体柱上,以4-甲基亚硝胺基-1-(3-吡啶)-1-丁醇(NNAL)的O-糖苷化合物(NNAL-O-Gluc)为底物研究酶反应器的水解效果,实验结果证明酶反应器在室温条件下的水解效率大大提高,实现了NNAL-O-Gluc高效水解与分析,解决了目前NNAL-O-Gluc分析中前处理水解效率低的问题。     

A Zeolite Family Nonjointly Built from the 1,3‐Stellated Cubic Building Unit

From a technological point of view, the synthesis of new high‐silica zeolites is of prime importance owing to their high potential as industrial catalysts and catalyst supports. Two such materials have been synthesized which are made up of the 1,3‐stellated cubic unit (hexahedral ([4²5⁴]) bre unit) as a secondary building unit, with the aid of existing imidazolium‐based structure‐directing agents under “excess fluoride” conditions. One of them, denoted PST‐21, is the first aluminosilicate zeolite consisting of 9‐ring apertures solely; it displays exceptional activity towards steering the skeletal isomerization of 1‐butene to isobutene and bridges the gap between small‐ and medium‐pore structures. A series of hypothetical structures are also described that are nonjointly built from the bre unit; all of these structures are chemically feasible and will thus be helpful in designing the synthesis of novel zeolites containing 9‐ring and/or 10‐ring channels.     

Another Unprecedented Wieland Mechanism Confirmed: Hydrogen Formation from Hydrogen Peroxide,Formaldehyde, and Sodium Hydroxide

In 1923, Wieland and Wingler reported that in the molecular hydrogen producing reaction of hydrogen peroxide with formaldehyde in basic solution, free hydrogen atoms (H^.) are not involved. They postulated that bis(hydroxymethyl)peroxide, HOCH₂OOCH₂OH, is the intermediate, which decomposes to yield H₂ and formate, proposing a mechanism that would nowadays be considered as a “concerted process”. Since then, several other (conflicting) “mechanisms” have been suggested. Our NMR and Raman spectroscopic and kinetic studies, particularly the determination of the deuterium kinetic isotope effect (DKIE), now confirm that in this base‐dependent reaction, both H atoms of H₂ derive from the CH₂ hydrogen atoms of formaldehyde, and not from the OH groups of HOCH₂OOCH₂OH or from water. Quantum‐chemical CBS‐QB3 and W1BD computations show that H₂ release proceeds through a concerted process, which is strongly accelerated by double deprotonation of HOCH₂OOCH₂OH, thereby ruling out a free radical pathway.     

Soft Phonon Modes Leading to Ultralow Thermal Conductivity and High Thermoelectric Performance in AgCuTe

Crystalline solids with intrinsically low lattice thermal conductivity (κ_L) are crucial to realizing high‐performance thermoelectric (TE) materials. Herein, we show an ultralow κ_L of 0.35 Wm^?1 K^?1 in AgCuTe, which has a remarkable TE figure‐of‐merit, zT of 1.6 at 670 K when alloyed with 10 mol % Se. First‐principles DFT calculation reveals several soft phonon modes in its room‐temperature hexagonal phase, which are also evident from low‐temperature heat‐capacity measurement. These phonon modes, dominated by Ag vibrations, soften further with temperature giving a dynamic cation disorder and driving the superionic transition. Intrinsic factors cause an ultralow κ_L in the room‐temperature hexagonal phase, while the dynamic disorder of Ag/Cu cations leads to reduced phonon frequencies and mean free paths in the high‐temperature rocksalt phase. Despite the cation disorder at elevated temperatures, the crystalline conduits of the rigid anion sublattice give a high power factor.     

几种乙酸铵离心法测定土壤阳离子交换量的方法探讨

乙酸铵离心交换法测定酸性和中性土壤阳离子交换量是经典方法,但此方法的蒸馏过程繁琐、时间长、效率低。本文引用纳氏试剂分光光度法测定土壤CEC值,并将结果与乙酸铵离心法常用的几种传统测定方法进行了实验对比和总结。通过对国家标准样品及实际土壤样品的CEC值测定,纳氏试剂比色法的精密度在2-4%之间,准确度与经典方法一致。与传统滴定法比较,取代了蒸馏的步骤,测定方法简单,干扰少,结果可靠,可操作性强。     

超声辅助制备Ni-Mo/USY催化剂上正庚烷异构化性能研究

以USY分子筛作为载体,Ni和Mo作为活性组分,利用超声辅助浸渍法（US-IM）和常规浸渍法（C-IM）制备了Ni/USY（US-IM）和Ni-Mo/USY催化剂.采用X射线衍射（XRD）、吡啶-红外光谱分析（Py-IR）和N₂吸附-脱附等对催化剂进行理化性质表征,综合考察了不同改性方法以及单金属和双金属改性前后分子筛酸性和孔结构性质等的变化及其对正庚烷异构化性能的影响.实验结果表明：Mo对于Ni在USY分子筛上的均匀分布以及异构化催化性能具有协同促进作用;超声条件对双金属改性的USY结构基本无影响;超声空化作用降低了催化剂金属粒子的团聚,使其在USY表面均匀分散,增加了催化反应中所需的金属活性位点.超声辅助浸渍制备的Ni-Mo/USY中较高的金属分散度导致了较强的金属-载体相互作用,使其活性和稳定性高于常规浸渍法.在优化超声条件下,反应温度和反应时间分别为250℃和3 h,还原温度和还原时间分别为550℃和5 h,H₂/C₇摩尔比为0.14时,正庚烷的转化率和异构化选择性分别可以达到65.7%和74.1%.     

黄葆同归国始末：1950年代留美学生回国因素探析

黄葆同院士（1921-2005）是我国高分子化学领域的资深专家。早年留学美国,1955年回国后一直在中国科学院长春应用化学研究所工作。在乙丙橡胶合成等研究领域走在全国前列。基于对“老科学家学术成长资料采集工程”所存大量书信和日记等的解读分析,论文还原了黄葆同在美留学期间加入进步组织、争取回国的历史过程以及求学经历。并以此为缩影,探讨当时促使留美学生回国的个体与社会因素,具体而微地揭示了那一代中国留学生在困境之中的家国情怀。