Tunable magnetophoretic method for distinguishing and separating wear debris particles in an Fe-PDMS-based microfluidic chip

Wear debris analysis provides an early warning of mechanical transmission system aging and wear fault diagnosis, which has been widely used in machine health monitoring. The ability to detect and distinguish the ferromagnetic and nonmagnetic debris in oil is becoming an effective way to assess the health status of machinery. In this work, an Fe-poly(dimethylsiloxane) (PDMS)-based magnetophoretic method for the continuous separation of ferromagnetic iron particles by diameter and the isolation of ferromagnetic particles and nonmagnetic particles with similar diameter by type is developed. The particles experience magnetophoretic effects when passing through the vicinity of the Fe-PDMS where the strongest gradient of the magnetic fields exists. By choosing a relatively short distance between the magnet and the sidewall of the horizontal main channel and the length of Fe-PDMS with controlled particles flow rate, the diameter-dependent separation of ferromagnetic iron particles, that is, smaller than 7 µm, in the range of 8–12 µm, and larger than 14 µm, and the isolation of ferromagnetic iron particles and nonmagnetic aluminum particles based on opposite magnetophoretic behaviors by types are demonstrated, providing a potential method for the detection of wear debris particles with a high sensitivity and resolution and the diagnostic of mechanical system.     

Genetic Fusion of Thermoresponsive Polypeptides with UCST-type Behavior Mediates 1D Assembly of Coiled-Coil Bundlemers

Thermoresponsive resilin-like polypeptides (RLPs) of various lengths were genetically fused to two different computationally designed coiled coil-forming peptides with distinct thermal stability, to develop new strategies to assemble coiled coil peptides via temperature-triggered phase separation of the RLP units. Their successful production in bacterial expression hosts was verified via gel electrophoresis, mass spectrometry, and amino acid analysis. Circular dichroism (CD) spectroscopy, ultraviolet-visible (UV/Vis) turbidimetry, and dynamic light scattering (DLS) measurements confirmed the stability of the coiled coils and showed that the thermosensitive phase behavior of the RLPs was preserved in the genetically fused hybrid polypeptides. Cryogenic-transmission electron microscopy and coarse-grained modeling revealed that functionalizing the coiled coils with thermoresponsive RLPs leads to their thermally triggered noncovalent assembly into nanofibrillar assemblies.     

Enhanced Electrocatalytic Water Oxidation by Interfacial Phase Transition and Photothermal Effect in Multiply Heterostructured Co9S8/Co3S4/Cu2S Nanohybrids

The rational design of advanced nanohybrids (NHs) with optimized interface electronic environment and rapid reaction kinetics is pivotal to electrocatalytic schedule. Herein, we developed a multiple heterogeneous Co₉S₈/Co₃S₄/Cu₂S nanoparticle in which Co₃S₄ germinates between Co₉S₈ and Cu₂S. Using high-angle annular-dark-field imaging and theoretical calculation, it was found that the integration of Co₉S₈ and Cu₂S tends to trigger the interface phase transition of Co₉S₈, leading to Co₃S₄ interlayer due to the low formation energy of Co₃S₄/Cu₂S (−7.61 eV) than Co₉S₈/Cu₂S (−5.86 eV). Such phase transition not only lowers the energy barrier of oxygen evolution reaction (OER, from 0.335 eV to 0.297 eV), but also increases charge carrier density (from 7.76×10¹⁴ to 2.09×10¹⁵ cm⁻³), and creates more active sites. Compared to Co₉S₈ and Cu₂S, the Co₉S₈/Co₃S₄/Cu₂S NHs also demonstrate notable photothermal effect that can heat the catalyst locally, offset the endothermic enthalpy change of OER, and promote carrier migrate, reaction intermediates adsorption/deprotonation to improve reaction kinetics. Profiting from these favorable factors, the Co₉S₈/Co₃S₄/Cu₂S catalyst only requires an OER overpotential of 181 mV and overall water splitting cell voltage of 1.43 V to driven 10 mA cm⁻² under the irradiation of near-infrared light, outperforming those without light irradiation and many reported Co-based catalysts.     

A Dissipative Reaction Network Drives Transient Solid–Liquid and Liquid–Liquid Phase Cycling of Nanoparticles

Transient states maintained by energy dissipation are an essential feature of dynamic systems where structures and functions are regulated by fluxes of energy and matter through chemical reaction networks. Perfected in biology, chemically fueled dissipative networks incorporating nanoscale components allow the unique properties of nanomaterials to be bestowed with spatiotemporal adaptability and chemical responsiveness. We report the transient dispersion of gold nanoparticles in water, powered by dissipation of a chemical fuel. A dispersed state that is generated under non-equilibrium conditions permits fully reversible solid–liquid or liquid–liquid phase transfer. The molecular basis of the out-of-equilibrium process is reversible covalent modification of nanoparticle-bound ligands by a simple inorganic activator. Activator consumption by a coupled dissipative reaction network leads to autonomous cycling between phases. The out-of-equilibrium lifetime is tunable by adjusting the pH value, and reversible phase cycling is reproducible over several cycles.     

Synergistic Nitrogen Binding Sites in a Metal-Organic Framework for Efficient N2/O2 Separation

Porous materials with d₃ electronic configuration open metal sites have been proved to be effective adsorbents for N₂ capture and N₂/O₂ separation. However, the reported materials remain challenging to address the trade-off between adsorption capacity and selectivity. Herein, we report a robust MOF, MIL-102Cr, that features two binding sites, can synergistically afford strong interactions for N₂ capture. The synergistic adsorption site exhibits a benchmark Q_st of 45.0 kJ mol⁻¹ for N₂ among the Cr-based MOFs, a record-high volumetric N₂ uptake (31.38 cm³ cm⁻³), and highest N₂/O₂ selectivity (13.11) at 298 K and 1.0 bar. Breakthrough experiments reveal that MIL-102Cr can efficiently capture N₂ from a 79/21 N₂/O₂ mixture, providing a record 99.99 % pure O₂ productivity of 0.75 mmol g⁻¹. In situ infrared spectroscopy and computational modelling studies revealed that a synergistic adsorption effect by open Cr(III) and fluorine sites was accountable for the strong interactions between the MOF and N₂.     

Separation and purification of quinolyridine alkaloids from seeds of Thermopsis lanceolata R. Br. by conventional and pH-zone-refining counter-current chromatography

In this work, the preparative separation of quinolyridine alkaloids from seeds of T. lanceolata by conventional and pH-zone-refining counter-current chromatography. Traditional counter-current chromatography separation was performed by a flow-rate changing strategy with a solvent system of ethyl acetate-n-butanol-water (1:9:10, v/v) and 200 mg sample loading. Meanwhile, the pH-zone-refining mode was adopted for separating 2.0 g crude alkaloid extracts with the chloroform-methanol-water (4:3:3, v/v) solvent system using the stationary and mobile phases of 40 mM hydrochloric acid and 10 mM triethylamine. Finally, six compounds, including N-formylcytisine (two conformers) ( 1 ), N-acetycytisine (two conformers) ( 2 ), (-)-cytisine ( 3 ), 13-β-hydroxylthermopsine ( 4 ), N-methylcytisine ( 5 ), and thermopsine ( 6 ) were successfully obtained in the two counter-current chromatography modes with the purities over 96.5%. Moreover, we adopted nuclear magnetic resonance and mass spectrometry for structural characterization. Based on the obtained findings, the pH-zone-refining mode was the efficient method to separate quinolyridine alkaloids relative to the traditional mode.     

Simple high-performance liquid chromatography-ultraviolet method for simultaneous separation and detection of 14 bisphenol pollutants in building materials

A high-performance liquid chromatography-ultraviolet method was developed for rapidly and simultaneously analyzing novel and typical bisphenols in building materials, including bisphenol S, diphenolic acid, bisphenol F, bisphenol E, bisphenol A, bisphenol B, bisphenol AF, bisphenol AP, bisphenol C, bisphenol FL, bisphenol Z, bisphenol BP, bisphenol M, and bisphenol P. By using a Kromasil 100–5 C18 column, these bisphenols were completely separated in 40 min via gradually increasing the concentration of methanol in the mobile phase from 45 to 80% during the elution process. In particular, this method achieved the synchronous analysis of bisphenol S, diphenolic acid, bisphenol FL, bisphenol BP, and bisphenol M through HPLC, which were difficult to separate and had to be identified and detected through mass spectrometry. The limits of detection of the method ranged from 0.002 to 0.040 mg/L for these 14 bisphenols, with a precision of less than 4.9% (n = 7, c = 0.05 mg/L). The analytical results for five types of building materials (phenolic, epoxy, polycarbonate, polyester, and polysulfone resins) indicated that the proposed method is appropriated for the rapid measurement of bisphenols in real samples.     

电感耦合等离子体质谱(ICP-MS)法测定土壤中的碘

通过电感耦合等离子体质谱法(ICP-MS)测定土壤中的碘。样品预处理采用艾斯卡试剂熔融、热水提取和阳离子树脂静态交换,试验加入了不同剂量的阳离子交换树脂在不同程度上降低了溶液中Na+ 和Zn2+^{等阳离子的盐效应干扰。研究了乙醇在}ICP-MS中对碘元素的增强效应,用3%的氨水溶液清洗进样系统,有效减少的碘的记忆效应和清洗时间。该方法线性范围宽,方法灵敏度高,检出限低,试剂用量少,环境友好。对苏州及周边区域若干非污染土壤点位进行采样、制备和测试,碘平均含量为2.7μg.g_-1^;同步测试国家有证标准物质,精密度和准确度良好。     

Preparation of open tubular capillary column covalently coated with polystyrene sulfonate with 4,4′-Azobis(4-cyanopentanoyl chloride) as polymerization initiator for electrochromatographic separation of alkaloids,sulfonamides, and peptides

An open tubular capillary electrochromatography column covalently bonded with polystyrene sulfonate was prepared via in situ polymerization using functionalized Azo-initiator 4,4′-Azobis(4-cyanopentanoyl chloride). Scanning electron, fluorescence, and atomic force microscopy techniques showed the formation of a relatively rough layer of polymer. In addition, –CN and C = O stretching vibrations from infrared spectroscopy proved the successful immobilization of the azo-initiator through covalent bonding and X-ray photoelectron spectroscopy confirmed the elemental composition of the formed polymer layer. The prepared column was found to be appropriate for small and medium-sized molecules separation. Compared to bare fused silica capillary column higher selectivity and resolution were obtained for the separation of alkaloids, sulfonamides, and peptides as a result of the electrostatic and pi-pi stacking interactions between the small organic molecules and the coated column without compromising the electroosmotic flow mobility. Separation efficiency was also increased compared to the bare capillary for the separation of alkaloids (about 1.5 times). Moreover, intraday, inter-day, intra-batch, and inter-batch relative standard deviation values of retention time and peak area of peptides were within 2% and 10%, respectively, indicating good repeatability of the column preparation procedure. The developed method for the covalent bonding of polymers through a functionalized azo-initiator could represent a promising stable method for the preparation of an open tubular column.     

锂参与合成MOF-5用于CO_2/CH_4混合气体分离

利用溶剂热法合成了不同锂含量的MOF-5(x Li-MOF-5,x=0,1,3,5)。在MOF-5结晶过程中,锂离子被合并入其骨架结构中。实验表明,合并入骨架的锂能够改变MOF-5的结构和表面化学性质。不同的x Li-MOF-5能够不同程度降低骨架相互穿插的程度从而导致其吸附分离能力的大幅改变。其中,3Li-MOF-5具有最高的二氧化碳捕获能力(5.47 mmol·g-1),对40%CO2/60%CH4混合气体具有最优吸附选择性。