铝合金在铈盐溶液中成膜过程的电化学阻抗谱研究

应用电化学阻抗谱(EIS)研究B95铝合金在0.01 mol.L-1CeCl3溶液中铈盐转化膜的形成过程和机制。结果表明:EIS变化可以清楚地显示B95铝合金在铈盐溶液中成膜的动态过程,稀土转化膜的成膜过程可以分成形成、成长和稳定平衡3个阶段;形成阶段以Al合金的溶解为主;在成长阶段随着时间的增加,转化膜不断增厚,铝合金基体的溶解已经被抑制;稳定平衡阶段,膜的成长与溶解已经达到平衡,通过EIS解析表明自然条件下生成的转化膜不致密,该阶段阻抗谱图等效电路与成长阶段相同,但阻抗谱包含两个时间常数;在成膜三阶段基础上提出了稀土转化膜的成膜模型;同时给出各阶段阻抗谱图等效电路及其阻抗表达式。     

在高效离子交换色谱上蛋白质累加进样分离法的研究

研究了离子交换色谱上的累加进样法，并用选择性累加进样法在ＳＣＸ－６柱上经了尿激酶粗品，结果较好。     

Numerical and experimental investigations of the unsteady aerodynamics and aero-acoustics characteristics of a backward curved blade centrifugal fan

A numerical study of the aerodynamic and aeroacoustic behaviors of a backward curved blade centrifugal fan was conducted under two important flow conditions: BEP and 1.3 × BEP. Three-dimensional numerical simulations of the complete unsteady flow field for the whole impeller-volute configuration were used to determine the aeroacoustic sources. To locate the unsteady flow and perturbations, the near field wall pressure fluctuations at different strategic points on the volute were computed using the URANS approach. Thus the intensities and positions of the aeroacoustic sources were identified by analyzing frequency spectra. The aeroacoustic sources caused by fluctuations in the interactions of the flows leaving the impeller and volute were close to the volute tongue, and the most effective noise sources related to the flow rate were near the impeller shrouds. In addition, the unsteady flow variables provided by CFD calculations were used as inputs in the Ffowcs Williams-Hawkings equation to estimate the noise tones of the fan. The aeroacoustic calculation results showed that the volute noise was much larger than the blade noise, and the noise mainly propagated from the outlet duct of the fan. Moreover, to account for the noise propagation, three calculation methods were used by applying different solid boundaries. Compared with the other methods, the FEM method, which accounted for the complex solid boundaries, produced good agreement and showed that the complex solid boundaries cannot be neglected in aeroacoustic predictions. The calculation results showed good agreement with the experimental results.     

Automatic crystal centring procedure at the SSRF macromolecular crystallography beamline

X‐ray diffraction is a common technique for determining crystal structures. The average time needed for the solution of a protein structure has been drastically reduced by a number of recent experimental and theoretical developments. Since high‐throughput protein crystallography benefits from full automation of all steps that are carried out on a synchrotron beamline, an automatic crystal centring procedure is important for crystallographic beamlines. Fully automatic crystal alignment involves the application of optical methods to identify the crystal and move it onto the rotation axis and into the X‐ray beam. Crystal recognition has complex dependencies on the illumination, crystal size and viewing angles due to effects such as local shading, inter‐reflections and the presence of antifreezing elements. Here, a rapid procedure for crystal centring with multiple cameras using region segment thresholding is reported. Firstly, a simple illumination‐invariant loop recognition and classification model is used by slicing a low‐magnification loop image into small region segments, then classifying the loop into different types and aligning it to the beam position using feature vectors of the region segments. Secondly, an edge detection algorithm is used to find the crystal sample in a high‐magnification image using region segment thresholding. Results show that this crystal centring method is extremely successful under fluctuating light states as well as for poorly frozen and opaque samples. Moreover, this crystal centring procedure is successfully integrated into the enhanced Blu‐Ice data collection system at beamline BL17U1 at the Shanghai Synchrotron Radiation Facility as a routine method for an automatic crystal screening procedure.     

Supramolecular Hydrogel from Nanoparticles and Cyclodextrins for Local and Sustained Nanoparticle Delivery

Injectable and biodegradable supramolecular hydrogel mPECT NP/α‐CD^gel composed of high‐concentration nanoparticle dispersion (≤20% W/V) and α‐cyclodextrins (α‐CD) are prepared by a two‐level physical cross‐linking using amphiphilic block polymer methoxy poly(ethylene glycol)‐b‐poly(ε‐caprolactone‐co‐1,4,8‐trioxa[4.6]spiro‐9‐undecanone) (mPECT) and α‐CD. The gelation behavior depends on the concentration of nanoparticles and α‐CD. The viscoelasticity and shear thinning of mPECT NP/α‐CD^gel are confirmed. In vitro hydrogel erosion is demonstrated to be mainly a concentration‐dependent dissociation process with general release of discrete mPECT nanoparticles about 50 nm that can be easily taken up by cells. The in vitro release behavior can be modulated by changing the concentration of nanoparticles or α‐CD. In vitro and in vivo cytotoxicity study demonstrates its biocompatibility and biosafety. Gel formation after subcutaneous injection is also confirmed and mPECT NP/α‐CD^gel shows about 2 weeks retention time. This work validates the potential application for this supramolecular hydrogel in local and sustained delivery of nanoparticles.

     

Gas-Mediated Tumor Energy Remodeling for Sensitizing Mild Photothermal Therapy

The metabolic reprogramming of tumors requires high levels of adenosine triphosphate (ATP) to maintain therapeutic resistance, posing a major challenge for photothermal therapy (PTT). Although raising the temperature helps in tumor ablation, it frequently leads to severe side effects. Therefore, improving the therapeutic response and promoting healing are critical considerations in the development of PTT. Here, we proposed a gas-mediated energy remodeling strategy to improve mild PTT efficacy while minimizing side effects. In the proof-of-concept study, a Food and Drug Administration (FDA)-approved drug-based hydrogen sulfide (H₂S) donor was developed to provide a sustained supply of H₂S to tumor sites, serving as an adjuvant to PTT. This approach proved to be highly effective in disrupting the mitochondrial respiratory chain, inhibiting ATP generation, and reducing the overexpression of heat shock protein 90 (HSP90), which ultimately amplified the therapeutic outcome. With the ability to reverse tumor thermotolerance, this strategy delivered a greatly potent antitumor response, achieving complete tumor ablation in a single treatment while minimizing harm to healthy tissues. Thus, it holds great promise to be a universal solution for overcoming the limitations of PTT and may serve as a valuable paradigm for the future clinical translation of photothermal nanoagents.     

Sequential Multistep Excited-State Structural Transformations in N,N′-Diphenyl-dihydrodibenzo[a,c]phenazine Fluorophores

We demonstrate that a single polycyclic π-scaffold can undergo sequential multistep excited-state structural evolution along the bent, planar, and twisted conformers, which coexist to produce intrinsic multiple fluorescence emissions in room-temperature solution. By installing a methyl or trifluoromethyl group on the ortho-site of N,N′-diphenyl-dihydrodibenzo[a,c]phenazine ( DPAC ), the enhanced steric effects change the fluorescence emission of DPAC from a dominant red band to well-resolved triple bands. The ultra-broadband triple emissions of ortho-substituted DPAC s range from ≈350 to ≈850 nm, which is unprecedented for small fluorophores with molecular weight of <500. Ultrafast spectroscopy and theoretical calculations clearly reveal that the above dramatic changes originate from the influence of steric hindrance on the shape of excited state potential energy surface (S₁ PES). Compared to the steep S₁ PES of parental DPAC , the introduction of ortho-substituent is shown to make the path of structural evolution in S₁ wider and flatter, so the ortho-substituted derivatives exhibit slower structural transformations from bent to planar and then to twisted forms, yielding intrinsic triple emission. The results provide the proof of concept that the bent, planar, and twisted emissive states can coexist in the same S₁ PES, which greatly expand the fundamental understanding of the excited-state structural relaxation.     

A phase separable polycarbonate polymerization catalyst

Polyisobutylene is shown to be a nonpolar phase tag that separates a highly colored salen Cr(III) complex from products but is otherwise kinetically similar to a low molecular weight salen Cr(III) complex in polycarbonate formation by Cr(III)-catalyzed copolymerization of CO2 and cyclohexene oxide.     

Total synthesis of (+)-komarovispirone

(+)-Komaroviquinone photolytically rearranges to (+)-komarovispirone. A rationalization of this isomerization is presented.     

Selective isolation of acidic proteins with a thin layer of multiwalled carbon nanotubes functionalized with polydiallyldimethylammonium chloride

The selective isolation of acidic proteins using a thin layer of multiwalled carbon nanotubes (MWNTs) functionalized with polydiallyldimethylammonium chloride (PDDA) was demonstrated. A certain amount (20 ml) of a suspension of PDDA-functionalized MWNTs that had been well dispersed by sonication was filtered through an MF-Millipore membrane with a pore aperture of 1.2 μm, and a uniform layer of PDDA-MWNT composites with a thickness of ca. 5 μm formed on the membrane. A 4 × 1 cm piece of the obtained membrane was supported by a stainless steel wire mesh and was then sandwiched between two PTFE films with grooved flow-through channels to form an extraction module. This module with a flow inlet and outlet was incorporated into a sequential injection system for performing the on-line separation and preconcentration of acidic protein, i.e., bovine serum albumin (BSA), and the BSA retained on the layer was eluted with a citrate buffer used as stripping reagent. In addition to a significant reduction in flow resistance, a dynamic sorption capacity of 3.8 mg mg⁻¹ or 1.4 mg cm⁻² for BSA was achieved using the layer-based system—a 146-fold improvement over that obtained using a packed microcolumn mode. A sample volume of 2.0 ml yielded an enrichment factor of 17, a retention efficiency of 100% and a recovery of 95%, along with a sampling frequency of 20 h⁻¹ and a RSD value of 2.8% at 25 μg ml⁻¹ for BSA. The practical applicability of the system was demonstrated by isolating acidic proteins (especially human serum albumin) from whole blood. Figure Selective isolation of acidic proteins with a composite thin layer of multi-walled carbon nanotubes functionalized with poly-diallyldimethylammonium chloride