Co−Co Dinuclear Active Sites Dispersed on Zirconium-doped Heterostructured Co9S8/Co3O4 for High-current-density and Durable Acidic Oxygen Evolution

Developing cost-effective and sustainable acidic water oxidation catalysts requires significant advances in material design and in-depth mechanism understanding for proton exchange membrane water electrolysis. Herein, we developed a single atom regulatory strategy to construct Co−Co dinuclear active sites (DASs) catalysts that atomically dispersed zirconium doped Co₉S₈/Co₃O₄ heterostructure. The X-ray absorption fine structure elucidated the incorporation of Zr greatly facilitated the generation of Co−Co DASs layer with stretching of cobalt oxygen bond and S−Co−O heterogeneous grain boundaries interfaces, engineering attractive activity of significantly reduced overpotential of 75 mV at 10 mA cm⁻², a breakthrough of 500 mA cm⁻² high current density, and water splitting stability of 500 hours in acid, making it one of the best-performing acid-stable OER non-noble metal materials. The optimized catalyst with interatomic Co−Co distance (ca. 2.80 Å) followed oxo-oxo coupling mechanism that involved obvious oxygen bridges on dinuclear Co sites (1,090 cm⁻¹), confirmed by in situ SR-FTIR, XAFS and theoretical simulations. Furthermore, a major breakthrough of 120,000 mA g⁻¹ high mass current density using the first reported noble metal-free cobalt anode catalyst of Co−Co DASs/ZCC in PEM-WE at 2.14 V was recorded.     

Selective Encapsulation and Chiral Induction of C60 and C70 Fullerenes by Axially Chiral Porous Aromatic Cages

Chiral induction has been an important topic in chemistry, not only for its relevance in understanding the mysterious phenomenon of spontaneous symmetry breaking in nature but also due to its critical implications in medicine and the chiral industry. The induced chirality of fullerenes by host–guest interactions has been rarely reported, mainly attributed to their chiral resistance from high symmetry and challenges in their accessibility. Herein, we report two new pairs of chiral porous aromatic cages (PAC), R- PAC-2 , S- PAC-2 (with Br substituents) and R- PAC-3 , S- PAC-3 (with CH₃ substituents) enantiomers. PAC-2 , rather than PAC-3 , achieves fullerene encapsulation and selective binding of C₇₀ over C₆₀ in fullerene carbon soot. More significantly, the occurrence of chiral induction between R- PAC-2 , S- PAC-2 and fullerenes is confirmed by single-crystal X-ray diffraction and the intense CD signal within the absorption region of fullerenes. DFT calculations reveal the contribution of electrostatic effects originating from face-to-face arene-fullerene interactions dominate C₇₀ selectivity and elucidate the substituent effect on fullerene encapsulation. The disturbance from the differential interactions between fullerene and surrounding chiral cages on the intrinsic highly symmetric electronic structure of fullerene could be the primary reason accounting for the induced chirality of fullerene.     

Facile Synthesis of Metallosalphen-Based 2D Conductive Metal-Organic Frameworks for NO2 Sensing: Metal Coordination Induced Planarization

As an emerging class of promising porous materials, the development of two-dimensional conductive metal organic frameworks (2D c-MOFs) is hampered by the few categories and tedious synthesis of the specific ligands. Herein, we developed a nonplanar hexahydroxyl-functionalized Salphen ligand (6OH-Salphen) through a facile two-step synthesis, which was further applied to construct layered 2D c-MOFs through in situ one pot synthesis based on the synergistic metal binding effect of the N₂O₂ pocket of Salphen. Interestingly, the C_2v-symmetry of ligand endows Cu-Salphen-MOF with periodically heterogeneous pore structures. Benefitting from the higher metal density and shorter in-plane metal-metal distance, Cu-Salphen-MOF showcased excellent NO₂ sensing performance with good sensitivity, selectivity and reversibility. The current work opens up a new avenue to construct 2D c-MOF directly from nonplanar ligands, which greatly simplifies the synthesis and provides new possibilities for preparing different topological 2D c-MOF based functional materials.     

Determination of 3-chloro-1,2-propanediol in biological samples by quick-easy-cheap-effective-rugged-and-safe extraction coupled with gas chromatography-mass spectrometry and its biodistribution in rats

3-Chloro-1,2-propanediol is a common food contaminant, but reports on its determination in biological tissues are lacking. In the present study, a method was developed to detect 3-chloro-1,2-propanediol contents in rat tissues by quick-easy-cheap-effective-rugged-and-safe extraction and gas chromatography-mass spectrometry analysis. Biological samples were extracted with ethyl acetate and purified with adsorbents. The optimized adsorbent for each sample was selected from 4–5 combinations of N-propylethylenediamine, octadecylsilane, graphitized carbon black, strong anion exchange, and florisil. Extracted 3-chloro-1,2-propanediol was derivatized with heptafluorobutyric anhydride and subjected to gas chromatography-mass spectrometry. This method had good linearity (correlation coefficients >0.99) in the range of 2–2000 ng/g for blood, kidney, liver, testis, and brain samples. The limits of detection were under 0.8 ng/g; the limits of quantification were 2 ng/g; the recovery rates were 85%–102%; and the matrix effects were 1.98%–7.67%. This method also had good precision. The dynamic changes in 3-chloro-1,2-propanediol in rats gavaged with 20 mg/kg b.w. for 24 h were detected using this method. The 3-chloro-1,2-propanediol content in each tissue sharply increased to a peak, rapidly decreased within 2 h, and stabilized at 12 h. 3-Chloro-1,2-propanediol persisted in the kidney, testis, and liver 24 h after gavage.     

关于Smarandache ceil函数的一个方程

研究了关于Sm arandache ceil函数的一个方程,并用初等方法得到了它的所有解.     

钛表面钠氢氧钛纳米线的结构、生物活性和MC3T3-E1细胞响应

采用化学方法处理微弧氧化(MAO)制备的含Si、Ca元素的Ti O2涂层(SC),获得钛氢氧钠(Na0.8H1.2Ti3O7)生物活性纳米线结构。化学处理过程中,SC涂料表面出现了Ca、Na元素溶解,Si元素沉积的现象。化学处理后的SC涂层比SC涂料具有更好的吸水性和诱导磷灰石形成能力。这与处理后涂层(SHTO)特殊的纳米结构有关,在模拟体液浸泡过程中更容易形成Ti-OH。同时,钠氢氧钛纳米线的表面形貌、相组成、OH基团以及良好的湿润能力使其更加适合于MC3T3-E1细胞的粘附和增值。     

Solvent free synthesis of trifluoromethyl tertiary alcohols by cross Aldol reaction

Exceedingly fast preparation of trifluoromethyl tertiary alcohols has been accomplished from methyl ketones and trifluoromethyl ketones under solvent free conditions by cross Aldol reaction. The reaction was achieved in the presence of common inorganic base by grinding method at ambient temperature to give β-trifluoromethyl-β-hydroxyl ketones in high yields (up to 95%).     

基于色谱–光谱联用和斜投影法分析丹皮酚含量

将色谱–光谱仪联用(HPLC–UV)法与斜投影法结合,建立了丹皮酚含量快速分析方法。通过色谱–光谱联用采集丹皮酚结晶母液的紫外多波长光谱三维数据,构建不含丹皮酚的背景数据库以及丹皮酚光谱数据库,基于斜投影法步骤测定了批量样本中丹皮酚含量。结果表明:该方法计算结果和高效液相色谱分析结果接近,相对误差小于5.0%。测定结果的相对标准偏差为0.4%~1.0%(n=5),回收率为98.8%~101.3%。该方法快速、准确,操作简单,可为丹皮酚结晶产品及各种制剂质量控制提供可行方案。     

Mono‐ and Dinuclear Heteroleptic Cobalt Complexes with α‐Diimine and Polyarene Ligands

Reactions of the dimeric cobalt complex [(L^?Co)₂] ( 1 , L=[(2,6‐iPr₂C₆H₃)NC(Me)]₂) with polyarenes afforded a series of mononuclear and dinuclear complexes: [LCo(η⁴‐anthracene)] ( 2 ), [LCo(μ‐η⁴:η⁴‐naphthalene)CoL] ( 3 ), and [LCo(μ‐η⁴:η⁴‐phenanthrene)CoL] ( 4 ). The pyrene complexes [{Na₂(Et₂O)₂}{LCo(μ‐η³:η³‐pyrene)CoL}] ( 5 ) and [{Na₂(Et₂O)₃}{LCo(η³‐pyrene)}] ( 6 ) were obtained by treating precursor 1 with pyrene followed by reduction with Na metal. These complexes contain three potential redox active centers: the cobalt metal and both α‐diimine and polyarene ligands. Through a combination of X‐ray crystallography, EPR spectroscopy, magnetic susceptibility measurement, and DFT computations, the electronic configurations of these complexes were studied. It was determined that complexes 2 – 4 have a high‐spin Co^I center coupled with a radical α‐diimine ligand and a neutral polyarene ligand. Whereas, the ligand L in complexes 5 and 6 has been further reduced to the dianion, the cobalt remains in a formal (I) oxidation state, and the pyrene molecule is either neutral or monoanionic.     

Fetal hematopoietic stem cells express MFG-E8 during mouse embryogenesis

The milk fat globule-EGF-factor 8 protein (MFG-E8) has been identified in various tissues, where it has an important role in intercellular interactions, cellular migration, and neovascularization. Previous studies showed that MFG-E8 is expressed in different cell types under normal and pathophysiological conditions, but its expression in hematopoietic stem cells (HSCs) during hematopoiesis has not been reported. In the present study, we investigated MFG-E8 expression in multiple hematopoietic tissues at different stages of mouse embryogenesis. Using immunohistochemistry, we showed that MFG-E8 was specifically expressed in CD34⁺ HSCs at all hematopoietic sites, including the yolk sac, aorta-gonad-mesonephros region, placenta and fetal liver, during embryogenesis. Fluorescence-activated cell sorting and polymerase chain reaction analyses demonstrated that CD34⁺ cells, purified from the fetal liver, expressed additional HSC markers, c-Kit and Sca-1, and that these CD34⁺ cells, but not CD34⁻ cells, highly expressed MFG-E8. We also found that MFG-E8 was not expressed in HSCs in adult mouse bone marrow, and that its expression was confined to F4/80⁺ macrophages. Together, this study demonstrates, for the first time, that MFG-8 is expressed in fetal HSC populations, and that MFG-E8 may have a role in embryonic hematopoiesis.