Electrochemically Enabled Intramolecular Aminooxygenation of Alkynes via Amidyl Radical Cyclization

An electrochemical synthesis of oxazol‐2‐ones and imidazol‐2‐ones has been developed via 5‐exo‐dig cyclization of propargylic carbamates‐ and ureas‐derived amidyl radicals. The electrosynthesis relies on the dual function of 2,2,6,6‐tetramethylpiperidin‐ 1‐yl)oxyl (TEMPO) as a redox mediator for amidyl radical formation and an oxygen atom donor. The reactions are conducted under mild conditions using a simple setup and provide convenient access to functionalized oxazol‐2‐ones and imidazol‐2‐ones from readily available materials.     

Evaluation of minimum detectable amounts of iodine in biological samples by neutron activation analysis

Evaluation of minimal detectable amounts (MDA) of iodine in various or specified irradiation and measurement conditions is described. Interfering contributions due to Na and Cl to the spectral background as well as the dead time of detection system were calculated in details based on an experimental approach. The MDA of iodine for some important biological samples with various Na and Cl concentrations can be evaluated and predicted according to the specified irradiation and measurement arrangements to meet the requirement of analytical purposes.     

Two N,N′‐diaryl‐2,2,2‐trichloroethane‐1,1‐diamines: hydrogen‐bonded supramolecular structures in one and two dimensions

The molecules of 2,2,2‐trichloro‐N,N′‐diphenylethane‐1,1‐diamine, C₁₄H₁₃Cl₃N₂, are linked into (040) sheets by a combination of C—H...Cl and C—H...π(arene) hydrogen bonds. In 2,2,2‐trichloro‐N,N′‐bis(4‐methylphenyl)ethane‐1,1‐diamine, C₁₆H₁₇Cl₃N₂, the molecules are linked into C(7) chains by two independent C—H...Cl hydrogen bonds and one Cl...Cl contact.     

Microfluidic three-dimensional biomimetic tumor model for studying breast cancer cell migration and invasion in the presence of interstitial flow

Cell migration and invasion are critical steps in cancer metastasis, which are the major cause of death in cancer patients. Tumor-associated macrophages(TAMs) and interstitial flow(IF) are two important biochemical and biomechanical cues in tumor microenvironment, play essential roles in tumor progression. However, their combined effects on tumor cell migration and invasion as well as molecular mechanism remains largely unknown. In this work, we developed a microfluidic-based 3 D breast cancer model by co-culturing tumor aggregates, macrophages, monocytes and endothelial cells within 3 D extracellular matrix in the presence of IF to study tumor cell migration and invasion. On the established platform, we can precisely control the parameters related to tumor microenvironment and observe cellular responses and interactions in real-time. When co-culture of U937 with human umbilical vein endothelial cells(HUVECs) or MDA-MB-231 cells and tri-culture of U937 with HUVECs and MDA-MB-231 cells, we found that mesenchymal-like MDA-MB-231 aggregates activated the monocytes to TAM-like phenotype macrophages. MDA-MB-231 cells and IF simultaneously enhanced the macrophages activation by the stimulation of colony-stimulating factor 1(CSF-1). The activated macrophages and IF further promoted vascular sprouting via vascular endothelial growth factor(VEGFα) signal and tumor cell invasion. This is the first attempt to study the interaction between macrophages and breast cancer cells under IF condition. Taken together, our results provide a new insight to reveal the important physiological and pathological processes of macrophages-tumor communication. Moreover, our established platform with a more mimetic 3 D breast cancer model has the potential for drug screening with more accurate results.     

Synthesis of Derivatives of Pyrido[4,3‐d]pyrimidin‐4(3H)‐one via an Iminophosphorane

A series of new, 2‐substituted 3‐aryl‐8,9,10,11‐tetrahydro‐5‐methyl[1]benzothieno[3′,2′ : 5,6]pyrido[4,3‐d]pyrimidin‐4(3H)‐ones, compounds 5a – q , were designed and synthesized via the aza‐Wittig reaction as the key step. The iminophosphorane 1 reacted with phenyl isocyanate (or 4‐chlorophenyl isocyanate) to the carbodiimide 4 , which was cyclized to 5 upon addition of different amines, EtOH, or phenols in the presence of a catalytic amount of EtONa or K₂CO₃ (Schemes 1 and 2). The structures of compounds 5 were confirmed by IR, ¹H‐ and ¹³C‐NMR, EI‐MS, elemental analyses, and, in the case of 5l , by single‐crystal X‐ray diffraction (Figure).     

HZSM-5分子筛焙烧脱铝的27Al MQMAS NMR研究

用29Si、27Al魔角旋转固体核磁共振(MAS NMR)结合二维多量子魔角旋转(2D MQMAS)技术对焙烧脱铝的HZSM-5分子筛中铝的配位状态进行了研究.结果表明,HZSM-5分子筛经焙烧后,在化学位移(δ)45处出现一宽峰信号,其主要来自扭曲四配位铝.通过二维三量子铝谱计算出扭曲四配位铝的四极作用常数约为5.2 MHz.对700和750 ℃焙烧样品的铝谱进行分峰拟合,发现在δ 30处又出现一个小峰,归属为非骨架五配位铝.同时,在750 ℃焙烧样品的二维多量子铝谱中直接观察到非骨架五配位铝的信号.焙烧温度低于700 ℃,脱铝不明显；高于700 ℃,引起分子筛骨架的显著脱铝.焙烧还造成部分骨架铝的信号变得“不可观测”.     

多壁碳纳米管-炭复合泡沫材料的制备和吸附性能

通过在聚氨酯泡沫模板中沉积多壁碳纳米管，用炭的预制体酚醛树酯将碳纳米管粘接固定在一起，经过高温碳化过程制备了碳纳米管-炭复合泡沫材料。红外光谱结果表明利用浓硫酸和浓硝酸的混合溶液处理可以使复合泡沫表面活化形成羧基和羟基，从而使复合泡沫具备较强的分子吸附能力。扫描电镜和氮吸附实验表明这种复合泡沫同时具备大孔和介孔，大孔能够满足流体自由流动的通畅性，介孔可以满足中分子的吸附需要。对标定物维生素B12的吸附实验证明这种复合泡沫对中分子量的生化分子具有有效的吸附能力。这种宏观尺寸的泡沫材料与传统的颗粒状活性炭相比具有简化工艺，提高吸附效率的应用潜力。     

微乳液中球形及棒状SrTiO3纳米粒子的控制合成

以氢氧化锶和钛酸四丁酯为原料, 在水溶液/Triton X-100/环己烷/正己醇反相微乳液体系中制备了直径约为20～80 nm的钛酸锶球形纳米粒子和长约300～1200 nm、直径约为30～150 nm的钛酸锶纳米棒. 用XRD, ICP, TEM, SAED和SEM对样品的结构、成分和形貌进行了表征; 用DLS分析了样品的粒度分布. 结果显示, 水与表面活性剂的物质的量比(ω₀)、反应物浓度、陈化时间等因素都能影响钛酸锶纳米粒子的形貌和尺寸. 所得钛酸锶的锶钛物质的量比约为1.0, 粒度分布较窄, 为立方相单晶结构.     

Temperature and metal composition dependence of lateral photovoltaic effect in Al-Alq3/SiO2/Si structures

A series of Al=-（Alq3）l-x granular films is prepared on Si wafer with native oxide layer using co-evaporation technique. Large lateral photovoltaic effect （LPE） is observed, with an optimal LPV sensitivity of 75 mV/mm in x=0.35 sample. The dependence of LPE on temperature and A1 composition is investigated, and the possible mechanism is discussed.     

Seed‐Mediated Synthesis of Gold Tetrahedra in High Purity and with Tunable,Well‐Controlled Sizes

We report a facile synthesis of Au tetrahedra in high purity and with tunable, well‐controlled sizes via seed‐mediated growth. The success of this synthesis relies on the use of single‐crystal, spherical Au nanocrystals as the seeds and manipulation of the reaction kinetics to induce an unsymmetrical growth pattern for the seeds. In particular, the dropwise addition of a precursor solution with a syringe pump, assisted by cetyltrimethylammonium chloride and bromide at appropriate concentrations, was found to be critical to the formation of Au tetrahedra in high purity. Their sizes could be readily tuned in the range of 30–60 nm by simply varying the amount of precursor added to the reaction solution. The current strategy not only enables the synthesis of Au tetrahedra with tunable and controlled sizes but also provides a facile and versatile approach to reducing the symmetry of nanocrystals made of a face‐centered cubic lattice.