Synergistic Effect of Lithocholic Acid with Gentamicin against Gram-Positive Bacteria but Not against Gram-Negative Bacteria

Listeria monocytogenes (L. monocytogenes) is an important Gram-positive food-borne pathogen that severely threatens public health. A checkerboard microdilution method was performed to evaluate the synergistic effect of lithocholic acid (LCA) with Gentamicin (Genta) against L. monocytogenes. BacLight LIVE/DEAD staining, scanning electron microscopy and biofilm inhibition assays were further used to explore the bactericidal effect and antibiofilm effect of this combination on L. monocytogenes. Additionally, the synergistic effects of LCA derivatives with Genta were also evaluated against L. monocytogenes, S. aureus and S. suis. The results indicated that a synergistic bactericidal effect was observed for the combined therapy of LCA at the concentration without affecting bacteria viability, with Genta. Additionally, LCA in combination with Genta had a synergistic effect against Gram-positive bacteria (L. monocytogenes, S. aureus and S. suis) but not against Gram-negative bacteria (E. coli, A. baumannii and Salmonella). BacLight LIVE/DEAD staining and scanning electron microscopy analysis revealed that the combination of LCA with Genta caused L. monocytogenes membrane injury, leading to bacteria death. We found that 8 μg/mL LCA treatment effectively improved the ability of Genta to eradicate L. monocytogenes biofilms. In addition, we found that chenodeoxycholic acid, as a cholic acid derivative, also improved the bactericidal effect of Genta against Gram-positive bacteria. Our results indicate that LCA represents a broad-spectrum adjuvant with Genta for infection caused by L. monocytogenes and other Gram-positive pathogens.     

La1/3Sr2/3Fe1-xCoxO3体系中的Co替代效应研究

本文通过对La1/3Sr2/3Fe1-xCoxO3系列样品进行X射线衍射(XRD)和变温电阻率(p～T)、比热(C～T)、磁化率(M～T)等测试,研究了Co掺杂对该系列样品的晶体结构和电热磁性质的影响.结果表明,随着Co掺杂量的增加,晶胞体积单调减小;电阻中电荷有序(charge ordering,CO)的特征逐渐消失.Co含量低的样品随着温度降低发生顺磁-反铁磁(PM-AFM)转变和金属-绝缘体(M-I)转变;Co含量高的样品则在磁转变温度以下表现出团簇玻璃型短程铁磁有序行为,并且在整个测量温区内具有金属导电特性.这些证明Co掺杂引起电子的局域化效应是导致体系电磁和输运行为发生变化的主要原因.     

The Exponential Law Between Dwell Time and the Strength of PBX Substitute Material

Polymer-bonded sugars (PBSs) can be used as a substitute material for polymerbonded explosives (PBXs) due to their ability to simulate the mechanical properties...     

Preparation of Highly Stable and Photoluminescent Cadmium-Free InP/GaP/ZnS Core/Shell Quantum Dots and Application to Quantitative Immunoassay

Indium phosphide (InP) quantum dots (QDs) are ideal substitutes for widely used cadmium-based QDs and have great application prospects in biological fields due to their environmentally benign properties and human safety. However, the synthesis of InP core/shell QDs with biocompatibility, high quantum yield (QY), uniform particle size, and high stability is still a challenging subject. Herein, high quality (QY up to 72%) thick shell InP/GaP/ZnS core/shell QDs (12.8 ± 1.4 nm) are synthesized using multiple injections of shell precursor and extension of shell growth time, with GaP serving as the intermediate layer and 1-octanethiol acting as the new S source. The thick shell InP/GaP/ZnS core/shell QDs still keep high QY and photostability after transfer into water. InP/GaP/ZnS core/shell QDs as fluorescence labels to establish QD-based fluorescence-linked immunosorbent assay (QD-FLISA) for quantitative detection of C-reactive protein (CRP), and a calibration curve is established between fluorescence intensity and CRP concentrations (range: 1–800 ng mL⁻¹, correlation coefficient: R² = 0.9992). The limit of detection is 2.9 ng mL⁻¹, which increases twofold compared to previously reported cadmium-free QD-based immunoassays. Thus, InP/GaP/ZnS core/shell QDs as a great promise fluorescence labeling material, provide a new route for cadmium-free sensitive and specific immunoassays in biomedical fields.     

Tetra‐ammonium Zinc Phthalocyanine to Construct a Graded 2D–3D Perovskite Interface for Efficient and Stable Solar Cells

The crystallographic defects inevitably incur during the solution processed organic‐inorganic hybrid perovskite film, especially at surface and the grain boundaries (GBs) of perovskite film, which can further result in the reduced cell performance and stability of perovskite solar cells (PSCs). Here, a simple defect passivation method was employed by treating perovskite precursor film with a hydrophobic tetra‐ammonium zinc phthalocyanine (ZnPc). The results demonstrated that a 2D‐3D graded perovskite interface with a capping layer of 2D (ZnPc)_0.5MA_n ? 1Pb_nI_3n + 1 perovskite together with 3D MAPbI₃ perovskite was successfully constructed on the top of 3D perovskite layer. This situation realized the efficient GBs passivation, thus reducing the defects in GBs. As expected, the corresponding PSCs with modified perovskite revealed an improved cell performance. The best efficiency reached 19.6%. Especially, the significantly enhanced long‐term stability of the responding PSCs against humidity and heating was remarkably achieved. Such a strategy in this work affords an efficient method to improve the stability of PSCs and thus probably brings the PSCs closer to practical commercialization.     

Synthesis and Infrared Multi‐band Absorption Properties of Core‐shell NaYF4:Yb3+, Er3+@SiO2 Nanoparticles

Due to the unique size effects, nanomaterials in infrared absorption have attracted much attention for their strong absorption in the infrared region. To achieve the infrared multi‐band absorption, we propose to synthesize a core‐shell structure nanomaterial consisting of NaYF₄:Yb³⁺, Er³⁺ core and a layer of SiO₂ as shell. A series of NaYF₄:Yb³⁺, Er³⁺ nanocrystals were synthesized through hydrothermal method by adjusting the ratio of citric acid(CA)‐to‐NaOH, and the effects of CA concentration, and NaOH concentration were studied in detail. NaYF₄:Yb³⁺, Er³⁺@SiO₂ nanoparticles were synthesized by sol‐gel method using TEOS as silica source. The results show that the core‐shell NaYF₄:Yb³⁺, Er³⁺@SiO₂ nanoparticles were successfully synthesized. Up‐conversion spectra of these nanoparticles were recorded with 980 nm laser excitation under room temperature. There are no changes of the emission centers of nanoparticles before or after silica coating, but the emission intensities of nanoparticles after silica coating are weakened. Furthermore, the property of infrared multi‐band absorption was tested through ultraviolet‐visible‐near infrared spectrophotometer and infrared absorption spectra. The results illustrate that the multi‐band infrared absorption nanomaterial was successfully synthesized.     

Direct Dynamic Evidence of Charge Separation in a Dye‐Sensitized Solar Cell Obtained under Operando Conditions by Raman Spectroscopy

Interfaces play an important role in enhancing the energy conversion performance of dye‐sensitized solar cells (DSCs). The interface effects have been studied by many techniques, but most of the studies only focused on one part of a DSC, rather than on a complete solar cell. Hence, monitoring the interface evolution of a DSC is still very challenging. Here, in situ/operando resonance Raman (RR) spectroscopic analyses were carried out to monitor the dynamics of the photovoltaic conversion processes in a DSC. We observed the creation of new species (i.e., polyiodide and iodine aggregates) in the photosensitization process. We also obtained molecular‐scale dynamic evidence that the bands from the C=C and C=N bonds of 2,2′‐bipyridyl (bpy), the S=C=N bonds of the NCS ligand, and photochemical products undergo reasonably strong intensity and frequency changes, which clearly demonstrates that they are involved in charge separation. Furthermore, RR spectroscopy can also be used to quickly evaluate the performance of DSCs.     

A Conjugated Copolymer Bearing Imidazolium-based Ionic Liquid:Electrochemical Synthesis and Electrochromic Properties

An imidazolium-based ionic liquid(IL) modified triphenylamine derivative,namely 1-(4-((4-(diphenylamino)benzoyl) oxy)butyl)-3-methyl imidazole tetrafluoroborate(TPAC_6 IL-BF_4),was designed and synthesized,and further applied with 3,4-ethylene dioxythiophene(EDOT)to prepare conjugated copolymer P(EDOT:TPAC_6 IL-BF_4) via electrochemical polymerization.The cyclic voltammetry curves show that the copolymer P(EDOT:TPAC_6 IL-BF_4) possesses two pairs of redox peaks,which should be ascribed to the redox behaviors of EDOT and triphenylamine.The ultraviolet-visible(UV-Vis) absorption spectrum of P(EDOT:TPAC_6 IL-BF_4) exhibits one maximum absorption peak at 580 nm and a small shoulder characteristic peak at 385 nm under neutral state which are assigned to π-π~* conjugated structure of EDOT and triphenylamine.After being applied at the positive voltage,the copolymer color changes from dark blue to light blue,which is close to the color of poly(3,4-ethylenedioxythiophene)(PEDOT).Surprisingly,the copolymer P(EDOT:TPAC_6 IL-BF_4) shows shorter switching time of 0.37 s,0.30 s at 580 nm and 0.38 s,0.45 s at 1100 nm compared with PEDOT.It is more intriguing that the copolymer P(EDOT:TPAC_6 IL-BF_4) exhibits electrochromism even in free supporting electrolyte.The results confirm that the existence of imidazolium-based ionic liquid has an improvement on the ion diffusion properties and the switching time of conjugated polymer,which may provide a potential direction for the preparation of high-performance electrochromic materials.     

Inorganic–Organic Hybrid Molecular Clusters with Cu2I2 Rhomboid Dimer Core as Light-Emitting Coating Materials

Journal of Cluster Science - In this paper, a series of light-emitting copper(I) iodide inorganic–organic hybrid clusters has been synthesized, and they are 0D-Cu2I2(fmp)4 (1,...     

电化学部分氟化芳基研究进展

含氟芳香化合物具有生物活性好、稳定性高、易被生物体代谢等优点,在医药和农药领域有着广泛的用途.目前芳基部分氟化的方法主要分为依赖于氟化试剂的亲电氟化方法以及反应条件苛刻甚至需要过渡金属催化的亲核氟化方法,这些方法操作繁琐并且污染环境.电化学氟化将"电能"作为一种"强氧化剂"来实现氟化反应,是一种直接、绿色且温和的氟化手...