Successful Decontamination of 99TcO4− in Groundwater at Legacy Nuclear Sites by a Cationic Metal‐Organic Framework with Hydrophobic Pockets

⁹⁹Tc contamination at legacy nuclear sites is a serious and unsolved environmental issue. The selective remediation of ⁹⁹TcO₄^? in the presence of a large excess of NO₃^? and SO₄^2? from natural waste systems represents a significant scientific and technical challenge, since anions with a higher charge density are often preferentially sorbed by traditional anion‐exchange materials. We present a solution to this challenge based on a stable cationic metal‐organic framework, SCU‐102 (Ni₂(tipm)₃(NO₃)₄), which exhibits fast sorption kinetics, a large capacity (291 mg g^?1), a high distribution coefficient, and, most importantly, a record‐high TcO₄^? uptake selectivity. This material can almost quantitatively remove TcO₄^? in the presence of a large excess of NO₃^? and SO₄^2?. Decontamination experiments confirm that SCU‐102 represents the optimal Tc scavenger with the highest reported clean‐up efficiency, while first‐principle simulations reveal that the origin of the selectivity is the recognition of TcO₄^? by the hydrophobic pockets of the structure.     

In Situ Formation of Frustrated Lewis Pairs in a Water‐Tolerant Metal‐Organic Framework for the Transformation of CO2

Frustrated Lewis pairs (FLPs) consist of sterically hindered Lewis acids and Lewis bases, which provide high catalytic activity towards non‐metal‐mediated activation of “inert” small molecules, including CO₂ among others. One critical issue of homogeneous FLPs, however, is their instability upon recycling, leading to catalytic deactivation. Herein, we provide a solution to this issue by incorporating a bulky Lewis acid‐functionalized ligand into a water‐tolerant metal‐organic framework (MOF), named SION‐105 , and employing Lewis basic diamine substrates for the in situ formation of FLPs within the MOF. Using CO₂ as a C1‐feedstock, this combination allows for the efficient transformation of a variety of diamine substrates into benzimidazoles. SION‐105 can be easily recycled by washing with MeOH and reused multiple times without losing its identity and catalytic activity, highlighting the advantage of the MOF approach in FLP chemistry.     

Hollow Multi‐Shelled Structure with Metal–Organic‐Framework‐Derived Coatings for Enhanced Lithium Storage

Herein, we present heterogeneous hollow multi‐shelled structures (HoMSs) prepared by exploiting the properties of the metal–organic framework (MOFs) casing. Through accurately controlling the transformation of MOF layer into different heterogeneous casings, we can precisely design HoMSs of SnO₂@Fe₂O₃(MOF) and SnO₂@FeO_x‐C(MOF), which not only retain properties of the original SnO₂‐HoMSs, but also structural information from the MOFs. Tested as anode materials in LIBs, SnO₂@Fe₂O₃ (MOF)‐HoMSs demonstrate superior lithium‐storage capacity and cycling stability to the original SnO₂‐HoMSs, which can be attributed to the topological features from the MOF casing. Making a sharp contrast to the electrodes of SnO₂@Fe₂O₃ (particle)‐HoMSs fabricated by hydrothermal method, the capacity retention after 100 cycles for the SnO₂@Fe₂O₃ (MOF)‐HoMSs is about eight times higher than that of the SnO₂@Fe₂O₃ (particle)‐HoMS.     

Hausdorff dimension of some kind of alternating Oppenheim series expansion

For Oppenheim series epansions, the authors of [7] discussed the exceptional sets Bm={x∈（0,1]：1〈dj（x）/h（j-1）（d（j-1）（x））≤m for any j ≥2} In this paper, we investigate the Hausdorff dimension of a kind of exceptional sets occurring in alternating Oppenheim series expansion. As an application, we get the exact Hausdorff dimension of the-set in Luroth series expansion, also we give an estimate of such dimensional number.     

BSB5-Bestimmung durch direkte coulometrische Bestimmung des verbrauchten Sauerstoffs

Zusammenfassung In einem geschlossenen System werden 250 ml der Probe zur Bestimmung des Sauerstoffbedarfs thermostatisiert bei 20° C angesetzt. Zu diesem System geh?rt der Anodenraum einer Wasserelektrolyse, die elektrisch gespeist wird mit einem Coulometer, das durch einen Quecksilberschalter, der aufΔp dieses Systems anspricht, gesteuert wird. Im gleichfalls angeschlossenen Natronkalkrohr wird gebildetes CO₂ gebunden. Die Einschaltzeiten des Coulometers werden mit einer mechanisch-elektrischen übertragung und einem mV-Schreiber festgehalten. Die Aufzeichnung stellt die Intensit?t des biologischen Wachstums im Verh?ltnis zur abgelaufenen Zeit dar. Aus dem Gesamtausschlag (mV) kann der Sauerstoffverbrauch nach 5 Tagen errechnet werden.

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Determination of the biochemical oxygen demand (BOD₅) by direct coulometric determination of the oxygen consumed

Summary 250 ml of the sample are given into a closed system thermostatically adjusted to 20° C. This system includes the anodic compartment of a water electrolysis cell connected to a coulometer, which is controlled by a mercury switch responding toΔp of the system. CO₂ is bound in a soda lime tube. The switching times of the coulometer are transmitted to a mV-recorder. Thus the diagram shows the intensity of biological growth in relation to time. The oxygen demand after 5 days can be calculated from the total response.

     

Dispersion Forces,Disproportionation, and Stable High‐Valent Late Transition Metal Alkyls

The transition metal tetra‐ and trinorbornyl bromide complexes, M(nor)₄ (M=Fe, Co, Ni) and Ni(nor)₃Br (nor=1‐bicyclo[2.2.1]hept‐1‐yl) and their homolytic fragmentations were studied computationally using hybrid density functional theory (DFT) at the B3PW91 and B3PW91‐D3 dispersion‐corrected levels. Experimental structures were well replicated; the dispersion correction resulted in shortened M−C bond lengths for the stable complexes, and it was found that Fe(nor)₄ receives a remarkable 45.9 kcal mol⁻¹ stabilization from the dispersion effects whereas the tetragonalized Co(nor)₄ shows stabilization of 38.3 kcal mol⁻¹. Ni(nor)₄ was calculated to be highly tetragonalized with long Ni−C bonds, providing a rationale for its current synthetic inaccessibility. Isodesmic exchange evaluation for Fe(nor)₄ confirmed that dispersion force attraction between norbornyl substituents is fundamental to the stability of these species.     

CoP‐Doped MOF‐Based Electrocatalyst for pH‐Universal Hydrogen Evolution Reaction

Although electrocatalysts based on transition metal phosphides (TMPs) with cationic/anionic doping have been widely studied for hydrogen evolution reaction (HER), the origin of performance enhancement still remains elusive mainly due to the random dispersion of dopants. Herein, we report a controllable partial phosphorization strategy to generate CoP species within the Co‐based metal‐organic framework (Co‐MOF). Density functional theory calculations and experimental results reveal that the electron transfer from CoP to Co‐MOF through N‐P/N‐Co bonds could lead to the optimized adsorption energy of H₂O (ΔG ) and hydrogen (ΔG_H*), which, together with the unique porous structure of Co‐MOF, contributes to the remarkable HER performance with an overpotential of 49 mV at a current density of 10 mA cm^?2 in 1 m phosphate buffer solution (PBS, pH 7.0). The excellent catalytic performance exceeds almost all the documented TMP‐based and non‐noble‐metal‐based electrocatalysts. In addition, the CoP/Co‐MOF hybrid also displays Pt‐like performance in 0.5 m H₂SO₄ and 1 m KOH, with the overpotentials of 27 and 34 mV, respectively, at a current density of 10 mA cm^?2.     

Nomenklatur metallorganischer Verbindungen der Übergangsmetalle

Die Übersetzung basiert auf der „Nomenclature of Organometallic Compunds of the Transition Elements“ der Commission on Nomenclature of Inorganic Chemistry der Inorganic Chemistry Division der International Union of Pure and Applied Chemistry, veröffentlicht in Pure Appl. Chem. 1999 , 71, 1557–1585. Das Original wurde von Albrecht Salzer (RWTH Aachen) für die Veröffentlichung vorbereitet.     

荒漠-绿洲交错地带典型植被光谱特征研究

植被对区域生态环境保护具有重要意义,尤其是在荒漠-绿洲交错地带,植被对土壤保持、提高土地的抗剪切性能有重要意义,对土壤风蚀和荒漠化防治的影响作用较大,利用高光谱技术测定并分析荒漠-绿洲交错带典型植被的光谱特性,不仅能够指导区域的植被遥感分类,还能够对植被实行远程监控提供依据。研究借助美国Field Spec 4高分辨率地物光谱仪,在研究区采集棉花、柽柳、梭梭和盐穗木等四种典型植被不同条件下的光谱数据,在对数据进行归类、筛选及综合处理后,分别对原始数据进行FDR(一阶导数反射率)和RLR(倒数取对数反射率)变换。利用原始数据、FDR和RLR分别分析不同植物的光谱敏感波段和表达方式。结果表明：植物的光谱曲线具有类似的变化特征,植被种类不同在“红边”区和近红外780～1 260 nm波段的表达方式区别较大;植物对可见光的吸收非常强烈,对不同波长的光吸收强弱变化会形成波峰和波谷;植物红边特征具有特殊性,蕴含植物自身的特有信息,三种方式的处理结果显示,光谱特征在经FDR计算后,植物光谱红边特征区差异性非常明显;利用三种不同方式处理后的光谱数据,分别来计算改进的植物NDVI值,经RLR变换后重新计算得到的NDVI值在植物不同种之间表现出较大差别,用于植物种类区分的效果明显。     

一种基于HLLC算法的Mie-Grüneisen多介质混合模型

建立一种修正的HLLC （Harten-Lax-Van Leer-Contact）格式下稳定的Mie-Grüneisen多介质混合计算模型.Mie-Grüneisen混合模型中的通量包括守恒和非守恒两个部分,原始的HLLC格式对守恒部分适用,但是原始的HLLC格式直接用于非守恒部分,很难控制住数值振荡的产生.在原始格式中,间断面的移动速度为间断网格的左侧或右侧速度,修正后替换为网格中的平均速度,经过修正后,对HLLC格式重新进行推导,并随之扩展到二维问题.数值实验表明,利用修改后的HLLC格式,Mie-Grüneisen混合模型可以取得较好的稳定性和准确性.