硫脲络合–火焰原子吸收光谱法测定低硅铝合金中的银含量

采用硫脲络合–火焰原子吸收光谱法测定低硅铝合金中的银元素含量。实验探讨了酸度及硫脲用量对银测定的影响及铝合金中基体元素与共存元素对银元素分析线的干扰情况。结果表明:选用9%的盐酸和3%的硝酸溶解试样最好,加入5 mL 50 g/L硫脲溶液可消除氯离子对试验结果的影响,基体铝元素和其它共存元素不干扰银的测定。根据低硅铝合金中银元素的含量范围,合成系列标准溶液,建立工作曲线,工作曲线的线性范围为0.05%~0.50%。银元素含量为0.30%的样品测定结果的相对标准偏差为0.15%(n=8),标准加入回收率为96.8%~98.5%。该方法操作简便、重现性好、测量结果准确可靠。     

An E1-Catalyzed Chemoenzymatic Strategy to Isopeptide-N-Ethylated Deubiquitylase-Resistant Ubiquitin Probes

Triazole-based deubiquitylase (DUB)-resistant ubiquitin (Ub) probes have recently emerged as effective tools for the discovery of Ub chain-specific interactors in proteomic studies, but their structural diversity is limited. A new family of DUB-resistant Ub probes is reported based on isopeptide-N-ethylated dimeric or polymeric Ub chains, which can be efficiently prepared by a one-pot, ubiquitin-activating enzyme (E1)-catalyzed condensation reaction of recombinant Ub precursors to give various homotypic and even branched Ub probes at multi-milligram scale. Proteomic studies using label-free quantitative (LFQ) MS indicated that the isopeptide-N-ethylated Ub probes may complement the triazole-based probes in the study of Ub interactome. Our study highlights the utility of modern protein synthetic chemistry to develop structurally and new families of tool molecules needed for proteomic studies.     

Thermal and Nonthermal Effects in Plasmon-Mediated Electrochemistry at Nanostructured Ag Electrodes

Hot carriers (HCs) and thermal effects, stemming from plasmon decays, are crucial for most plasmonic applications. However, quantifying these two effects remains extremely challenging due to the experimental difficulty in accurately measuring the temperature at reaction sites. Herein, we provide a novel strategy to disentangle HCs from photothermal effects based on the different traits of heat dissipation (long range) and HCs transport (short range), and quantitatively uncover the dominant and potential-dependent role of photothermal effect by investigating the rapid- and slow-response currents in plasmon-mediated electrochemistry at nanostructured Ag electrode. Furthermore, the plasmoelectric surface potential is found to contribute to the rapid-response currents, which is absent in the previous studies.     

Metal–Organic Framework Membrane Nanopores as Biomimetic Photoresponsive Ion Channels and Photodriven Ion Pumps

Biological ion channels and ion pumps with sub-nanometer sizes modulate ion transport in response to external stimuli. Realizing such functions with sub-nanometer solid-state nanopores has been an important topic with wide practical applications. Herein, we demonstrate a biomimetic photoresponsive ion channel and photodriven ion pump using a porphyrin-based metal–organic framework membrane with pore sizes comparable to hydrated ions. We show that the molecular-size pores enable precise and robust optoelectronic ion transport modulation in a broad range of concentrations, unparalleled with conventional solid-state nanopores. Upon decoration with platinum nanoparticles to form a Schottky barrier photodiode, photovoltage across the membrane is generated with “uphill” ion transport from low concentration to high concentration. These results may spark applications in energy conversion, ion sieving, and artificial photosynthesis.     

Tailoring A Poly(ether sulfone) Bipolar Membrane: Osmotic-Energy Generator with High Power Density

Osmotic energy, obtained through different concentrations of salt solutions, is recognized as a form of a sustainable energy source. In the past years, membranes derived from asymmetric aromatic compounds have attracted attention because of their low cost and high performance in osmotic energy conversion. The membrane formation process, charging state, functional groups, membrane thickness, and the ion-exchange capacity of the membrane could affect the power generation performance. Among asymmetric membranes, a bipolar membrane could largely promote the ion transport. Here, two polymers with the same poly(ether sulfone) main chain but opposite charges were synthesized to prepare bipolar membranes by a nonsolvent-induced phase separation (NIPS) and spin-coating (SC) method. The maximum power density of the bipolar membrane reaches about 6.2 W m⁻² under a 50-fold salinity gradient, and this result can serve as a reference for the design of bipolar membranes for osmotic energy conversion systems.     

Meta Junction Promoting Efficient Thermally Activated Delayed Fluorescence in Donor-Acceptor Conjugated Polymers

The meta junction is proposed to realize efficient thermally activated delayed fluorescence (TADF) in donor–acceptor (D-A) conjugated polymers. Based on triphenylamine as D and dicyanobenzene as A, as a proof of concept, a series of D-A conjugated polymers has been developed by changing their connection sites. When the junction between D and A is tuned from para to meta, the singlet–triplet energy splitting (ΔE_ST) is found to be significantly decreased from 0.44 to 0.10 eV because of the increasing hole–electron separation. Unlike the para-linked analogue with no TADF, consequently, the meta-linked polymer shows a strong delayed fluorescence. Its corresponding solution-processed organic light-emitting diodes (OLEDs) achieve a promising external quantum efficiency (EQE) of 15.4 % (51.9 cd A⁻¹, 50.9 lm W⁻¹) and CIE coordinates of (0.34, 0.57). The results highlight the bright future of D-A conjugated polymers used for TADF OLEDs.     

Construction of Flexible-on-Rigid Hybrid-Phase Metal–Organic Frameworks for Controllable Multi-Drug Delivery

Multi-component MOFs contain multiple sets of unique and hierarchical pores, with different functions for different applications, distributed in their inter-linked domains. Herein, we report the construction of a class of precisely aligned flexible-on-rigid hybrid-phase MOFs with a unique rods-on-octahedron morphology. We demonstrated that hybrid-phase MOFs can be constructed based on two prerequisites: the partially matched topology at the interface of the two frameworks, and the structural flexibility of MOFs with acs topology, which can compensate for the differences in lattice parameters. Furthermore, we achieved domain selective loading of multiple guest molecules into the hybrid-phase MOF, as observed by scanning transmission electron microscopy–energy-dispersive X-ray spectrometry elemental mapping. Most importantly, we successfully applied the constructed hybrid-phase MOF to develop a dual-drug delivery system with controllable loading ratio and release kinetics.     

Engineering the Charge-Transfer State to Facilitate Spin–Orbit Charge Transfer Intersystem Crossing in Spirobis[anthracene]diones

Spiro conjugation has been proposed to dictate the efficiency of charge transfer, which could directly affect the spin–orbit charge transfer intersystem crossing (SOCT-ISC) process. However, this process has yet to be exemplified. Herein, we prepared three spirobis[anthracene]diones, in which two benzophenone moieties are locked in close proximity and differentially functionalized to fine-tune the charge transfer state. Its feasibility for SOCT-ISC was theoretically predicted, then experimentally evaluated. Through fine-tuning the spiro conjugation coupling and varying the solvent dielectric constants, ISC rate constants were engineered to vary in a dynamic range of three orders of magnitude, from 7.8×10⁸ s⁻¹ to 1.0×10¹¹ s⁻¹, which is the highest ISC rate reported for SOCT-ISC system to our knowledge. Our findings substantiate the key factors for effective SOCT-ISC and offer a new avenue for the rational design of heavy atom free triplet sensitizers.     

F-T组分改性KCuZrO2催化剂上CO加氢合成异丁醇的性能研究

采用共沉淀法分别制备了不同F-T组分(Fe、Co、Ni)改性的KCuZrO_2催化剂,并用于催化CO加氢合成异丁醇。通过BET、XRD、TEM、XPS、H_2-TPR、CO-TPD以及in-situ DRIFTS对催化剂进行了表征。结果显示,F-T组分的加入促进了乙醇和丙醇的形成,但是对异丁醇选择性影响不同。结果表明,Fe促进了催化剂中各组分的分散,活性组分Cu在催化剂表面发生了富集,提高了H_2/CO活化吸附;另外,KFeCuZrO_2的催化剂表面含有较多的C1物种,有利于乙醇和丙醇进一步发生β-加成反应得到异丁醇,而Co和Ni改性的催化剂上缺少足够的C1物种,因此,异丁醇的选择性并未明显增加。Co的引入对催化剂结构以及Cu的分散影响不大,但是Co改性后催化剂性能有所下降,其原因是催化剂发生了失活; Ni添加后催化剂比表面积有所减小,且催化剂表面Cu/Zr物质的量比也降低到0. 19,催化剂粒径增大,Cu-Zr之间相互作用减弱,异丁醇选择性降低。     

Ag-Y/MIL-101吸附剂的制备及其吸附脱硫性能

通过银、钇双金属改性制备了Ag-Y/MIL-101吸附剂,并对Ag-Y/MIL-101进行了X射线衍射(XRD)、电镜(SEMEDS)、比表面积(BET)和热重(TG-DTG)表征。考察了Ag-Y/M IL-101金属负载顺序、金属负载浓度、金属溶液用量、负载时间对脱硫性能的影响,优化了吸附脱硫条件。结果表明,金属改性得到的Ag-Y/MIL-101保持了MIL-101的晶格结构。与M IL-101相比,Ag-Y/MIL-101的比表面积和孔容均有所下降。适宜Ag-Y/MIL-101的制备条件为:先负载银后负载钇,银离子和钇离子的负载浓度均为30 mmol/L,金属溶液用量均为1 mL,负载时间为8 h。适宜Ag-Y/MIL-101的吸附脱硫条件为:吸附剂用量0.05 g,模拟油为10 mL,吸附温度为60℃,吸附时间为8 h。在此条件下,Ag-Y/MIL-101对噻吩的吸附量达到21.7 mg/g。Ag能显著提高MIL-101的吸附硫容,Y能显著提高MIL-101的吸附选择性,因此,Ag-Y/MIL-101吸附剂中Ag和Y的协同作用使其拥有比MIL-101更高的硫容和噻吩脱硫选择性。