基于改进的模糊综合评价法的低渗油藏CO_2驱筛选体系的建立及应用

以某低渗透油藏为对象,首先在数据挖掘的基础上制定了低渗透油藏注CO_2驱筛选标准.基于模糊综合评价法,建立了适用于低渗透油藏CO_2驱适宜度评价的模糊综合评价模型,并运用该模型对目标油藏注CO_2的适宜度进行了评价.计算结果表明目标油藏注气驱开发适应性较好.评价过程有效地降低了直接进行注气开发的风险,为之后低渗透油藏注气开发提供了技术和经济上的指导.     

基于白化值的区间DEA建模

传统数据包络分析要求输入输出数据为精确数,然而在某些实际应用中,区间形式的数据相较于精确数更容易获得.将区间数转化为白化值,并基于传统C~2R模型提出了基于白化值的区间C~2R模型.考虑到决策单元的有效性不易通过基于白化值的区间C~2R模型来判断,因此将非阿基米德无穷小概念引入到上述模型,构建了具有非阿基米德无穷小的区间C~2R模型.此外,还给出了用于判断决策单元有效性的区间目标规划方法:分别通过G_(IC~2R)模型和WG_(IC~2R)模型判断决策单元是否为区间DEA有效与区间弱DEA有效.     

一种面板数据分位数回归模型的工具变量方法

本文将工具变量分位数回归模型(IVQR)应用到面板数据中,结合Canay对面板分位数回归的两步估计法以及Chernozhukov对IVQR模型的估计方法,提出了两步面板分位数工具变量估计法(2S-IVFEQR),并给出相应的参数估计。本文提出的方法较已有的方法计算复杂度低,蒙特卡洛模拟结果显示在数据量不大或者处理长面板数据时,2S-IVFEQR方法要优于传统的IVFEQR方法,且运算时间短。     

One‐stage Template‐free KOH Activation for Mesopore‐enriched Carbons and Their Application in CO2 Capture

Activated carbons with a high mesoporous structure were prepared by a one‐stage KOH activation process without the assistance of templates and further used as adsorbents for CO₂ capture. The physical and chemical properties as well as the pore structures of the resulting mesoporous carbons were characterized by N₂ adsorption isotherms, scanning electron microscopy (SEM ), X‐ray diffraction (XRD ), Raman spectroscopy, and Fourier transform infrared (FTIR ) spectroscopy. The activated carbon showed greater specific surface area and mesopore volume as the activation temperature was increased up to 600°C, showing a uniform pore structure, great surface area (up to ~815 m²/g), and high mesopore ratio (~55%). The activated sample exhibited competitive CO₂ adsorption capacities at 1 atm pressure, reaching 2.29 and 3.4 mmol/g at 25 and 0°C, respectively. This study highlights the potential of well‐designed mesoporous carbon as an adsorbent for CO₂ removal and widespread gas adsorption applications.     

Catalytic Applications of Nano‐Fe‐[Phenyl‐Salicylaldimine‐Methylpyranopyrazole]Cl2 as a Schiff Base Complex and Nanostructured Catalyst for the Synthesis of Hexahydroquinolines

By the four‐component condensation reaction of benzaldehyde with ethyl acetoacetate, malononitrile, and hydrazine hydrate using FeCl₂, a pyranopyrazole derivative was synthesized and then reacted with salicylaldehyde to give nano‐Fe‐[phenyl‐salicylaldimine‐methylpyranopyrazole]Cl₂ (nano‐[Fe‐PSMP]Cl₂). The prepared nano‐Schiff base complex was successfully used as an efficient catalyst for the synthesis of hexahydroquinolines.     

β‐AgVO3 Nanorods as Peroxidase Mimetic for Colorimetric Determination of Glucose

β‐AgVO₃ nanorods have been demonstrated to exhibit intrinsic peroxidase‐like activity. The oxidation of glucose can be catalyzed by glucose oxidase (GOx ) to generate H₂O₂ in the presence of O₂ . The β‐AgVO₃ nanorods can catalytically oxidize peroxidase substrates including o‐phenylenediamine (OPD ), 3,3′,5,5′‐tetramethylbenzidine (TMB ), and diammonium 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonate) (ABTS ) by H₂O₂ to produce typical color reactions: OPD from colorless to orange, TMB from colorless to blue, and ABTS from colorless to green. The catalyzed reaction by the β‐AgVO₃ nanorods was found to follow the characteristic Michaelis–Menten kinetics. Compared with horseradish peroxidase and AgVO₃ nanobelts, β‐AgVO₃ nanorods showed a higher affinity for TMB with a lower Michaelis–Menten constant (K _m) value (0.04118 mM ) at the optimal condition. Taking advantage of their high catalytic activity, the as‐synthesized β‐AgVO₃ nanorods were utilized to develop a colorimetric sensor for the determination of glucose. The linear range for glucose was 1.25–60 μM with the lower detection limit of 0.5 μM . The simple and sensitive GOx ‐β–AgVO₃ nanorods–TMB sensing system shows great promise for applications in the pharmaceutical, clinical, and biosensor detection of glucose.     

Theoretical Study of Substituent Effects on Geometric and Spectroscopic Parameters (IR, 13C, 29Si NMR) and Energy Decomposition Analysis of the Bonding in Molybdenum Silylidyne Complexes CpMo(CO)2(≡Si‐para‐C6H4X)

In this study, we report the substituent effect on the structures, frontier orbital analysis, and spectroscopic properties (IR , ¹³C , ²⁹Si NMR ) in the molybdenum silylidyne complexes CpMo (CO )₂(≡Si‐para ‐C₆H₄X ) (X = H, F, Cl, CN , NO₂ , Me, OMe , NH₂ , NHMe ) using MPW1PW91 quantum chemical calculations. The calculated structural parameters and spectral parameters are compatible with the experimental values in similar complexes. The nature of the chemical bond between the [Cp(OC ) ₂Mo ]⁻ and [Si‐para ‐C₆H₄X ]⁺ fragments was explored with energy decomposition analysis (EDA ). The percentage composition in terms of the defined groups of frontier orbitals for CpMo (CO )₂(≡Si‐para ‐C₆H₄X ) complexes was investigated to explore the character of the metal–ligand bonds. The linear correlations between the properties and Hammett constants (σ _p) were illustrated. Natural bond orbital analysis (NBO ) was used to illustrate the electronic structure of the complexes.     

COSY‐ und HSQC‐NMR‐Spektroskopie

The present state of the routine 2D COSY‐ and HSQC‐NMR spectroscopy is reported. After a short introduction into the basic theory of 2D NMR the pulse sequences of COSY and HSQC are explained. Using an example from natural product chemistry the procedures during the analysis of these 2D NMR spectra are demonstrated.     

Synthesis of Poly(2‐Hydroxyethyl Methacrylate)‐based Hybrid Nanoparticles via Visible‐Light‐Initiated Radical Polymerization

We report a new, unique process for the design of poly(2‐hydroxyethyl methacrylate) (PHEMA )‐based hybrid materials, which involves the coating of PHEMA on TiO₂ and TiO₂ /Ag nanoparticle surface under visible light. New hybrid materials initiated under different conditions were prepared under visible light, which could be used for the theoretical design of nanohybrid materials. The hybrid materials thus prepared were characterized by Fourier transform infrared spectroscopy (FTIR ), transmission electron microscopy (TEM ), and thermogravimetric analysis (TGA ). The experimental results confirmed the successful synthesis of TiO₂–PHEMA hybrid materials. Compared to other methods, the method reported here involving the direct combination of PHEMA on the TiO₂ surface was simply catalyzed by visible light without the addition of initiators.     

Are there reliable DFT approaches for 13C NMR chemical shift predictions of fullerene C60 derivatives?

The relationships between experimental and theoretical ¹³C NMR chemical shifts of a pristine fullerene C₆₀, monoadducts from [2 + n] cycloaddition (n = 1–3), and one [2 + 1] bis‐adduct are systematically analyzed for the first time by using diverse quantum‐chemical levels of theory. These levels involved B3LYP, B3PW91, B97‐2, mPW1PW91, PBE1PBE, and X3LYP hybrid functionals combined with 3‐21G, 6‐31G, 6‐31G(d), 6‐31G(d,p), 6‐31G(d,2p), LanL2DZ, and SDDAll basis sets. X3LYP/6‐31G approach is determined to have the lowest deviations from the ¹³C NMR experimental data compared to the other methods for all the fullerene compounds (mean absolute error value is 0.856 ppm and root mean squared error value is 1.197 ppm). The highest deviations are characteristic for α (sp² C2/C5/C8/C10) and β (sp² C6/C7/C11/C12) carbon atoms relative to a functionalization site and for those (sp³ C1/C9) directly attached with a side fragment in the [2 + n] monoadducts (n = 1–3). A probable reason of such deviation is that the approaches do not take into account a contribution of paramagnetic ring currents to ¹³C NMR chemical shifts. The results will be useful in design of novel fullerene derivatives and in performing unambiguous ¹³C NMR chemical shift assignments with modern quantum chemistry calculations.