金测定的方法验证及质量控制图的建立

对DZ/T 0279.19–2016 《区域地球化学样品分析方法第19部分:金量测定泡沫塑料富集–石墨炉原子吸收光谱法》进行了实验室方法验证,并建立了相应的质量控制图。结果表明,实验室具备采用泡沫塑料富集–石墨炉原子吸收光谱法测定金的资源和技术能力,建立的质量控制图能够对分析系统进行有效核查。     

Nonlinear rossby waves forced by topography

Using a barotropic semi-geostrophic model with topographic forcing the stability and solutions of the nonlinear Rossby waves are discussed. It is found that the effects of the W-E oriented topography and the N-S oriented topography on the stability and phase speed of the waves are quite different. It is also found that the nonlinear Rossby waves forced by the topography can be described by the well-known KdV equation.     

动力学过程的精确模拟

采用加权最小二乘法更精确地模拟了化学动力学过程,结出了几种常见动力学模型的权重函数。用普通最小二乘法和加权最小二乘法对聚时苯二甲酸乙二酯的结晶动力学过程进行了处理。方差分析表明,两种加权最小二乘法的标准差均小于普通最小二乘法的标准差,所得斜率和截距也有明显不同,示出了模拟的相对结晶度及其导数曲线。     

An experimental verification of statistical discrimination between the terminal and penultimate copolymerization models

In this article, the modified Buzzi–Ferraris model discrimination method was used to design experiments to discriminate between the terminal and penultimate models for styrene methyl methacrylate (STY/MMA) copolymerization. The measured variables were ¹³C-NMR peak areas. The peak area assignments of Aerdts⁸ were used. After nine experiments, the terminal model was picked over the penultimate model at 99.99% confidence. More importantly, the experimental data showed that computer simulated data used in previous studies were realistic, and the conclusions drawn from the simulation studies were valid. This experimental verification continues to show that the use of statistical model discrimination techniques can improve our ability to discriminate between competing copolymerization models. © 1996 John Wiley & Sons, Inc.     

Weight distributions of generalized quasi-cyclic codes over Fq+uFq

In this paper, by Gauss sums, we determine Hamming weight distributions of generalized quasi-cyclic (GQC) codes over the finite chain ring ${\mathbb{F}}_q+u{\mathbb{F}}_q$, where $u^2=0$. As applications, some new infinite families of minimal linear codes with $\frac{W_{\min }}{W_{\max }}\le \frac{q-1}{q}$ and projective two-weight codes are constructed.     

High-Pressure Fabrication of Binary Organic Solar Cells with High Molecular Weight D18 Yields Record 19.65 % Efficiency

In this work, inspired by the principles of a pressure cooker, we utilized a high-pressure method to address the processing challenges associated with high molecular weight polymers. Through this approach, we successfully dissolved high molecular weight D18 in chloroform at 100 °C within a pressure-tight vial. The increased steam pressure raised the boiling point and dissolving capacity of chloroform, enabling the creation of a hybrid film with superior properties, including more ordered molecular arrangement, increased crystallinity, extended exciton diffusion length, and improved phase morphology. Organic solar cells (OSCs) based on D18 : L8-BO prepared using this high-pressure method achieved an outstanding power conversion efficiency of 19.65 %, setting a new record for binary devices to date. Furthermore, this high-pressure method was successfully applied to fabricate OSCs based on other common systems, leading to significant enhancements in device performance. In summary, this research introduces a universal method for processing high molecular weight D18 materials, ultimately resulting in the highest performance reported for binary organic solar cells.     

A Supported Catalyst that Enables the Synthesis of Colorless CO2-Polyols with Ultra-Low Molecular Weight

Ultra-low molecular weight (ULMW) CO₂-polyols with well-defined hydroxyl end groups represent useful soft segments for the preparation of high-performance polyurethane foams. However, owing to the poor proton tolerance of catalysts towards CO₂/epoxide telomerization, it remains challenging to synthesize ULMW yet colorless CO₂-polyols. Herein, we propose an immobilization strategy of constructing supported catalysts by chemical anchoring of aluminum porphyrin on Merrifield resin. The resulting supported catalyst displays both extremely high proton tolerance (≈8000 times the equivalents of metal centers) and independence of cocatalyst, affording CO₂-polyols with ULMW (580 g mol⁻¹) and high polymer selectivity (>99 %). Moreover, the ULMW CO₂-polyols with various architectures (tri-, quadra-, and hexa-arm) can be obtained, suggesting the wide proton universality of supported catalysts. Notably, benefiting from the heterogeneous nature of the supported catalyst, colorless products can be facilely achieved by simple filtration. The present strategy provides a platform for the synthesis of colorless ULMW polyols derived from not only CO₂/epoxides, but also lactone, anhydrides etc. or their combinations.     

Two-weight or three-weight binary linear codes from cyclotomic mappings

Recently, linear codes with few weights have been studied extensively. These linear codes have wide applications in secret sharing schemes and authentication codes. In this paper, we introduce a new construction of defining sets using cyclotomic mappings and construct three new classes of binary linear codes with two or three weights. We also explicitly determine the weight distributions of these codes.     

Visible Light Photoiniferter Polymerization for Dispersity Control in High Molecular Weight Polymers

The synthesis of polymers with high molecular weights, controlled sequence, and tunable dispersities remains a challenge. A simple and effective visible-light controlled photoiniferter reversible addition-fragmentation chain transfer (RAFT) polymerization is reported here to realize this goal. Key to this strategy is the use of switchable RAFT agents (SRAs) to tune polymerization activities coupled with the inherent highly living nature of photoiniferter RAFT polymerization. The polymerization activities of SRAs were in situ adjusted by the addition of acid. In addition to a switchable chain-transfer coefficient, photolysis and polymerization kinetic studies revealed that neutral and protonated SRAs showed different photolysis and polymerization rates, which is unique to photoiniferter RAFT polymerization in terms of dispersity control. This strategy features no catalyst, no exogenous radical source, temporal regulation by visible light, and tunable dispersities in the unprecedented high molecular weight regime (up to 500 kg mol⁻¹). Pentablock copolymers with three different dispersity combinations were also synthesized, highlighting that the highly living nature was maintained even for blocks with large dispersities. T_g was lowered for high-dispersity polymers of similar MWs due to the existence of more low-MW polymers. This strategy holds great potential for the synthesis of advanced materials with controlled molecular weight, dispersity and sequence.