Phys Rev Lett
Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China.
Published: November 2023
An attosecond x-ray pulse with known spectrotemporal information is an essential tool for the investigation of ultrafast electron dynamics in quantum systems. Ultrafast free-electron lasers (FELs) have the unique advantage on unprecedented high intensity at x-ray wavelengths. However, no suitable method has been established so far for the spectrotemporal characterization of these ultrashort x-ray pulses. In this Letter, a simple method has been proposed based on self-referenced spectral interferometry for reconstructing the temporal profile and phase of ultrashort FEL pulses. We have demonstrated that the proposed method is reliable to completely characterize the attosecond x-ray FEL pulses with an error at the level of a few percent. Moreover, the first proof-of-principle experiment has been performed to achieve the single-shot spectrotemporal characterization of ultrashort pulses from a high-gain FEL. The precision of the proposed method will be enhanced with the decrease of the pulse duration, paving a new way for complete attosecond pulse characterization at x-ray FELs.
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http://dx.doi.org/10.1103/PhysRevLett.131.205002 | DOI Listing |
J Chromatogr A
February 2025
School of Pharmaceutical Sciences, University of Geneva, CMU - Rue Michel Servet 1, 1211 Geneva 4, Switzerland; Institute of Pharmaceutical Sciences of Western Switzerland, University of Geneva, CMU - Rue Michel Servet 1, 1211 Geneva 4, Switzerland. Electronic address:
Ion exchange chromatography (IEX) is an important analytical technique for the characterization of biotechnology-derived products, such as monoclonal antibodies (mAbs) and more recently, cell and gene therapy products such as messenger ribonucleic acid (mRNA) and adeno-associated viruses (AAVs). This review paper first outlines the basic principles and separation mechanisms of IEX for charge variant separation of biotherapeutics, and examines the different elution modes based on salt or pH gradients. It then highlights several recent trends when applying IEX for the characterization of biotechnology-derived products, including: i) the effective use of pH gradients, ii) the improvement of selectivity by using organic solvents in the mobile phase, multi-step gradients, or by combining ion pairing and ion exchange, and iii) the increase in analytical throughput using ultra-short columns or automated screening of conditions.
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January 2025
University of Minnesota Twin Cities, Chemical Engineering and Materials Science, 421 Washington Avenue SE, 55455, Minneapolis, UNITED STATES OF AMERICA.
Broader adoption of 4D ultrafast electron microscopy (UEM) for the study of chemical, materials, and quantum systems is being driven by development of new instruments as well as continuous improvement and characterization of existing technologies. Perhaps owing to the still-high barrier to entry, the full range of capabilities of laser-driven 4D UEM instruments has yet to be established, particularly when operated at extremely low beam currents (~fA). Accordingly, with an eye on beam stability, we have conducted particle tracing simulations of unconventional off-axis photoemission geometries in a UEM equipped with a thermionic-emission gun.
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January 2025
Leicester Institute for Pharmaceutical Innovation, Leicester School of Pharmacy, De Montfort University, The Gateway, Leicester, LE1 9BH, UK.
Guiding molecular assembly of peptides into rationally engineered nanostructures remains a major hurdle against the development of functional peptide-based nanomaterials. Various non-covalent interactions come into play to drive the formation and stabilization of these assemblies, of which electrostatic interactions are key. Here, the atomistic mechanisms by which electrostatic interactions contribute toward controlling self-assembly and lateral association of ultrashort β-sheet forming peptides are deciphered.
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December 2024
Hunan Provincial Key Laboratory of Anti-Resistance Microbial Drugs, Department of Pharmacy, The Third Hospital of Changsha, Changsha 410015, People's Republic of China. Electronic address:
Individualized medication with peptide antibiotics, guided by therapeutic drug monitoring, is essential to treat infections caused by multidrug-resistant bacteria. Peptide antibiotics exhibit an "on-off" elution mechanism on a C18 column, leading to adsorption at the column inlet in all-aqueous conditions. Unlike small molecules, column length minimally influences their retention, with longer columns simply broadening peptide antibiotic peaks due to unnecessary post-column volume.
View Article and Find Full Text PDFACS Appl Mater Interfaces
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College of Optical, Mechanical and Electrical Engineering, Zhejiang A&F University, Lin'an 311300, China.
As a member of the chalcogenide family, NiSe exhibits a direct bandgap of 1.74 eV, making it a promising candidate for nonlinear optical devices. However, its potential in the near-infrared region of the telecommunication band has not been fully explored.
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