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Enhancing chimeric fragmentation spectra deconvolution using direct infusion–tandem mass spectrometry across high-resolution mass spectrometric platforms
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Chemical synthesis of the highly functionalized O-antigen repeating unit from Pseudomonas aeruginosa serotype O3 for glycoconjugate vaccine development
No full textPseudomonas aeruginosa is an opportunistic pathogen responsible for severe nosocomial infections. This multidrug-resistant bacterium can cause pneumonia and cystic fibrosis, both of which are associated with high morbidity and mortality rates. The lipopolysaccharide of P. aeruginosa serves as an attractive target for the development of effective glycoconjugate vaccines. In this article, we report the first chemical synthesis of the highly challenging tetrasaccharide repeating unit of the P. aeruginosa serotype O3 O-antigen using a two-directional [1+(2 + 1)] glycosylation strategy. The synthesis is particularly challenging due to the poor nucleophilicity of the axial C4 hydroxyl group of l-galactose and the steric hindrance imposed by the 3S-hydroxybutyryl (Hb) chain. Furthermore, the presence of an acetyl group at the ortho position relative to the glycosylation site on l-galactose can lead to undesirable acetyl migration. Additionally, it is noteworthy that the selective removal of a 2-naphthylmethyl ether (Nap) during the late stages of synthesis, particularly in the presence of multiple benzyl groups, can be somewhat challenging to predict. Through the careful selection of synthetic strategies, building blocks, and optimized reaction conditions, we achieved the stereoselective glycosylations, selective oxidation of primary alcohols, remarkable enhancement of acceptor activity, and efficient introduction of the 3S-Hb group. The synthetic methodology presented in this work serves as a valuable reference for the preparation of structurally related oligosaccharides. By incorporating an aminopropyl linker, the target tetrasaccharide facilitates glycan microarray preparation and in vivo immunological assessments, thereby accelerating progress toward a synthetic glycoconjugate vaccine for P. aeruginosa
Cyclopenta[cd]azulene Trimer: A Unique Nonbenzenoid Nanographene with High Pentagon-Heptagon Density
No full textThe synthesis of nonbenzenoid nanographenes (NGs) with a high density of nonhexagonal rings remains a significant challenge, leaving this structural class largely unexplored. In this work, we report the efficient synthesis of a novel nonbenzenoid isomer of decacyclene, namely cyclopenta[cd]azulene trimer ( CPAT), derived from the natural product guaiazulene. The key step involves an acid–base buffer-assisted cyclotrimerization of cyclopenta[cd]azulen-2(1H)-one that can be further extended to produce halogenated derivative, enabling structural tunability. The resulting molecules feature a unique backbone comprising nine nonhexagonal rings arranged around a central benzenoid core, representing the highest pentagon–heptagon ring density among all reported π-extended NGs with ten or more fused rings. Compared to the pristine decacyclene, the synthesized compounds exhibit excellent ambient stability, narrower bandgaps, and distinct aromaticity profiles. Moreover, femtosecond transient absorption measurements of CPAT-a reveal an ultrafast singlet-state relaxation (∼14 ps), significantly shorter than that of decacyclene, highlighting the pronounced impact of nonbenzenoid topology on excited-state dynamics. This study introduces a new family of nonbenzenoid NGs and paves the way for the synthesis of new sp2 carbon allotrope featuring exclusively nonhexagonal ring systems
Speed meets precision: rapid intraoperative diagnostics in neuro-oncologic surgery
No full textSurgical resection of brain tumors is guided by radiology, anatomical relationships to critical neurological structures, and clinical metrics including patient age and neurological status. Intraoperative decision-making relies on histological assessment through smear and frozen section analysis of tissue; however, such approaches may be insufficient in the era of precision neuro-oncology. Molecular characterization now informs diagnosis, prognosis, and therapeutic response – factors that may directly influence surgical decisions. The integration of novel and rapid intraoperative diagnostic modalities holds the potential to enhance neurosurgical precision, reduce procedure-related morbidity, and maximize the overall effectiveness of modern multimodal brain tumor management
Analysis of clock accuracy and its low-frequency characterization in the inter-satellite K-Band ranging system
No full textTracing social mechanisms and interregional connections in Early Bronze Age Societies in Lower Austria
No full textIn this study, we present the results of archaeogenetic investigations of Early Bronze Age individuals from Lower Austria, specifically associated with the Únětice and Unterwölbling cultural groups. Through analysing newly generated genome-wide data of 129 individuals, we explore the social structure and genetic relationships within and between these communities. Our results reveal a predominantly patrilocal society with non-strict female exogamic practices. Additionally, Identity-by-Descent analysis detects long-distance genetic connections, emphasizing the complex network of interactions in Central Europe during this period. Despite shared social dynamics, notable genetic distinctions emerge between the Únětice and Unterwölbling groups. These insights contribute to our understanding of Bronze Age population interconnections and call for a nuanced interpretation of social dynamics in this historical contex
Vacuum-dressed superconductivity in NbN observed in a high-Q terahertz cavity
No full textEmerging theoretical frameworks suggest that physical properties of matter can be altered within an optical cavity by harnessing quantum vacuum electromagnetic fluctuations, even in the total absence of external driving fields. Among the most intriguing predictions is the potential to noninvasively manipulate superconductivity. Here, we experimentally observe modified superconductivity in niobium nitride (NbN) thin films within high-quality-factor (Q) terahertz cavities. Using terahertz time-domain spectroscopy, we characterize the NbN response both in free space and within a high-Q photonic-crystal cavity. Our analysis reveals significant cavity-induced modifications to the optical conductivity. A theoretical model indicates that these changes originate from a substantial (∼ 13 %) reduction in the superfluid density and a minor (∼ 2 %) reduction in the superconducting gap, driven by cavity vacuum fluctuations. These results demonstrate a platform for engineering ground states via vacuum–matter coupling, opening frontiers in cavity materials science