A very promising recent trend in applied quantum physics is to combine the advantageous features of different quantum systems into what is called “hybrid quantum technology”. One of the key elements in this new field will have to be a quantum memory enabling to store quanta over extended periods of time. Systems that may fulfill the demands of such applications are comb‐shaped spin ensembles coupled to a cavity. Due to the decoherence induced by the inhomogeneous ensemble broadening, the storage time of these quantum memories is, however, still rather limited. Here we demonstrate how to overcome this problem by burning well‐placed holes into the spectral spin density leading to spectacular performance in the multimode regime. Specifically, we show how an initial excitation of the ensemble leads to the emission of more than a hundred well‐separated photon pulses with a decay rate significantly below the fundamental limit of the recently proposed “cavity protection effect”.
A facile method has been developed for the large‐scale synthesis of random copolypeptides composed of multiple (i.e., cationic, hydrophobic, and hydrophilic) amino acids and their relative ratios have been optimized for broad‐spectrum antibacterial effect. The copolypeptides obtained have measured compositions close to the design ratios in spite of the differing reactivities of the different amino acids. An optimized random copolypeptide of lysine, leucine, and serine (denoted as KLS‐3) mimicking the composition of LL‐37 host defense peptide gives broad spectrum antibacterial activity against clinically relevant Gram‐negative and Gram‐positive bacteria such as methicillin‐resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa (PAO1) with minimum inhibitory concentrations (MICs) of 32–64 μg mL−1, as well as good MICs against multidrug resistant Gram‐negative bacteria of Escherichia coli EC 958 (64 μg mL−1) and Klebseilla pneumoniae PTR3 (128 μg mL−1). This method can be applied to the facile large‐scale copolymerization of multiple amino acids, including unnatural amino acids, to make effective antibacterial copolypeptides.
13C Nuclear magnetic resonance proved to be an advantageous tool to determine the stereoregularity of polystyrene polymers. The latter was achieved through the analysis of the signal of the quaternary carbon and that of the carbon-p in the aromatic ring too. Styrene was polymerized through microwaves and conventional heating activation using two different polymerization techniques: emulsion and bulk. Microwave activation was performed in a mono-modal type device under the following experimental conditions: various initiator concentrations, an average irradiation power of 50?W, temperature of 70°C, and using a batch reactor for emulsion and bulk experiments. The results obtained in these experiments were compared with those obtained by conventional heating activation polymerization under the same initiator concentration and temperature conditions. Microwave-activated reactions resulted in shorter reaction times and higher yields. The tacticity of the polymer samples was not significantly altered, which lead to the conclusion that, in this case, the stereoregularity of polystyrene was not influenced by microwave irradiation. 相似文献
We report herein an efficient A1‐C≡C‐A2‐C≡C‐A1 type small‐molecule 4,4'‐difluoro‐4‐bora‐3a,4a‐diaza‐s‐ indacene (BODIPY) acceptor (A1=BODIPY and A2=diketopyrrolopyrrole (DPP)) by following the A‐to‐A excited electron delocalization via the BODIPY meso ‐position, the inherent directionality for the excited electron delocalization. The lowest unoccupied molecular orbital (LUMO) delocalizes across over whole the two flanking A1 and the central A2, and the highest occupied molecular orbital (HOMO) localizes dominantly on the ‐C≡C‐DPP‐C≡C‐ segment. The excited electron upon light excitation of the DPP segment delocalizes over both the BODIPY and DPP segments. The acceptor in chloroform shows an unprecedented plateau‐like broad absorption between 550 and 700 nm with a large FWHM value of 195 nm. Upon transition into solid film, the acceptor shows absorption in the whole near ultraviolet‐visible‐near infrared wavelength region (300‐830 nm) with a low band gap of 1.5 eV and a maximum absorptivity of 0.85×105 cm‐1. Introduction of the ethynyl spacer between the A1 and A2 and the close BODIPY‐to‐DPP LUMO energy levels are crucial for the excited π−electron delocalization across over whole the conjugation backbone. A power conversion efficiency of 6.60% was obtained from the ternary non‐fullerene solar cell with PTB7‐Th:p ‐DTS(FBTTh2)2 (0.5 : 0.5) as the donor materials, which is the highest value among the non‐fullerene organic solar cells with BODIPY as the electron acceptor material. 相似文献
In this study, an enantioselective analytical method based on microwave‐assisted chiral derivatization coupled with ultra high performance liquid chromatography and tandem mass spectrometry was developed for the determination of bambuterol enantiomers in human plasma. The chiral derivatization reaction was greatly accelerated by microwave irradiation. Under the optimized conditions, both the derivatization time and separation time on column was only 3 min, and the lower limit of quantification was 2.5 pg/mL. The recoveries were in the range of 90.1–93.0% without significant matrix effect. Compared with the conventional heating chiral derivatization, microwave‐assisted chiral derivatization obtained higher chiral derivatization yields with much shorter time due to the effect of microwave irradiation. Furthermore, the racemization during the derivatization reaction was systematically investigated. The results showed the concentration of acetic acid and the reaction time had significant effects on the racemization, which could be well controlled during microwave‐assisted chiral derivatization for the short reaction time. Finally, this novel approach was demonstrated by determining bambuterol in human plasma of a clinical pharmacokinetic study in eight healthy volunteers. On the basis of the results, microwave‐assisted chiral derivatization coupled with ultra high performance liquid chromatography and tandem mass spectrometry as a simple and effective enantioselective analysis technique for the determination of chiral drugs in complex biological samples showed great promise. 相似文献
A novel microextraction method, termed microwave‐assisted ionic liquid/ionic liquid dispersive liquid–liquid microextraction, has been developed for the rapid enrichment and analysis of triazine herbicides in fruit juice samples by high‐performance liquid chromatography. Instead of using hazardous organic solvents, two kinds of ionic liquids, a hydrophobic ionic liquid (1‐hexyl‐3‐methylimidazolium hexafluorophosphate) and a hydrophilic ionic liquid (1‐butyl‐3‐methylimidazolium tetrafluoroborate), were used as the extraction solvent and dispersion agent, respectively, in this method. The extraction procedure was induced by the formation of cloudy solution, which was composed of fine drops of 1‐hexyl‐3‐methylimidazolium hexafluorophosphate dispersed entirely into sample solution with the help of 1‐butyl‐3‐methylimidazolium tetrafluoroborate. In addition, an ion‐pairing agent (NH4PF6) was introduced to improve recoveries of the ionic liquid phase. Several experimental parameters that might affect the extraction efficiency were investigated. Under the optimum experimental conditions, the linearity for determining the analytes was in the range of 5.00–250.00 μg/L, with the correlation coefficients of 0.9982–0.9997. The practical application of this effective and green method is demonstrated by the successful analysis of triazine herbicides in four juice samples, with satisfactory recoveries (76.7–105.7%) and relative standard deviations (lower than 6.6%). In general, this method is fast, effective, and robust to determine triazine herbicides in juice samples. 相似文献