Radical-directed protein fragmentation techniques, particularly free radical-initiated peptide sequencing (FRIPS) mass spectrometry (MS), offer significant potential for elucidating protein structures in the gas phase. This study presents a novel approach to protein structural analysis in vacuo, combining FRIPS MS with genetic code expansion (GCE) technology. By incorporating unnatural amino acids (UAAs) at specific sites within an Affibody protein, we effectively introduced a radical precursor at six distinct positions.
View Article and Find Full Text PDFThe interlayer stacking shift in van der Waals (vdW) crystals represents an important degree of freedom to control various material properties, including magnetism, ferroelectricity, and electrical properties. On the other hand, the structural phase transitions driven by interlayer sliding in vdW crystals often exhibit thickness-dependent, sample-specific behaviors with significant hysteresis, complicating a clear understanding of their intrinsic nature. Here, the stacking configuration of the recently identified vdW crystal, γ-GeSe, is investigated, and the disordering manipulation of stacking sequence is demonstrated.
View Article and Find Full Text PDFPoint defects play a crucial role in determining the properties of atomically thin semiconductors. This work demonstrates the controlled formation of different types of defects and their comprehensive optical characterization using hyperspectral line imaging (HSLI). Distinct optical responses are observed in monolayer semiconductors grown under different stoichiometries using metal-organic chemical vapor deposition.
View Article and Find Full Text PDFAs the global population ages, the prevalence of Parkinson's disease (PD) is steadily on the rise. PD demonstrates chronic and progressive characteristics, and many cases can transition into dementia. This increases societal and economic burdens, emphasizing the need to find effective treatments.
View Article and Find Full Text PDFNSCLC, the most common type of lung cancer, is often diagnosed late due to minimal early symptoms. Its high risk of recurrence or metastasis post-chemotherapy makes DC-based immunotherapy a promising strategy, offering targeted cancer destruction, low side effects, memory formation, and overcoming the immune evasive ability of cancers. However, the limited response to DCs pulsed with single antigens remains a significant challenge.
View Article and Find Full Text PDFBackground: Urine-derived stem cells (UDSCs) can be easily isolated from urine and possess excellent stem cell characteristics, making them a promising source for cell therapeutics. Due to their kidney origin specificity, UDSCs are considered a superior therapeutic alternative for kidney diseases compared to other stem cells. To enhance the therapeutic potential of UDSCs, we developed a culture method that effectively boosts the expression of Klotho, a kidney-protective therapeutic factor.
View Article and Find Full Text PDFMesoscopic-scale stacking reconfigurations are investigated when van der Waals (vdW) films are stacked. A method to visualize complicated stacking structures and mechanical distortions simultaneously in stacked atom-thick films using Raman spectroscopy is developed. In the rigid limit, it is found that the distortions originate from the transfer process, which can be understood through thin film mechanics with a large elastic property mismatch.
View Article and Find Full Text PDFAlthough hydraulic accumulators play a vital role in the hydraulic system, they face the challenges of being broken by continuous abnormal pulsating pressure which occurs due to the malfunction of hydraulic systems. Hence, this study develops anomaly detection algorithms to detect abnormalities of pulsating pressure for hydraulic accumulators. A digital pressure sensor was installed in a hydraulic accumulator to acquire the pulsating pressure data.
View Article and Find Full Text PDFMoS nanoscrolls that have inner core radii of ∼250 nm are generated from MoS monolayers, and the optical and transport band gaps of the nanoscrolls are investigated. Photoluminescence spectroscopy reveals that a MoS monolayer, originally a direct gap semiconductor (∼1.85 eV (optical)), changes into an indirect gap semiconductor (∼1.
View Article and Find Full Text PDFRenal fibrosis is an irreversible and progressive process that causes severe dysfunction in chronic kidney disease (CKD). The progression of CKD stages is highly associated with a gradual reduction in serum Klotho levels. We focused on Klotho protein as a key therapeutic factor against CKD.
View Article and Find Full Text PDFTEMPO ((2,2,6,6-tetramethylpiperidine-1-yl)oxyl)-assisted free-radical-initiated peptide sequencing mass spectrometry (FRIPS MS) is applied to the top-down tandem mass spectrometry of guanidinated ubiquitin (UB(Gu)) ions, i.e., -TEMPO-Bn-Sc-guanidinated ubiquitin (UBT(Gu)), to shed a light on gas-phase ubiquitin conformations.
View Article and Find Full Text PDFA low-density polyethylene (LDPE) degrading bacterial strain (ATKU1) was isolated (99.86% similar with Bacillus siamensis KCTC 13613) from a plastic dumping site to study interactions between microplastics (< 5 mm) and microorganisms. The strain was found (by scanning electron microscopy) to form biofilm on the microplastic surface after its interaction with LDPE (avg.
View Article and Find Full Text PDFCyclodextrins (CDs) have drawn a lot of attention from the scientific communities as a model system for host-guest chemistry and also due to its variety of applications in the pharmaceutical, cosmetic, food, textile, separation science, and essential oil industries. The formation of the inclusion complexes enables these applications in the condensed phases, which have been confirmed by nuclear magnetic resonance (NMR) spectroscopy, X-ray crystallography, and other methodologies. The advent of soft ionization techniques that can transfer the solution-phase noncovalent complexes to the gas phase has allowed for extensive examination of these complexes and provides valuable insight into the principles governing the formation of gaseous noncovalent complexes.
View Article and Find Full Text PDFAn exciton is the bosonic quasiparticle of electron-hole pairs bound by the Coulomb interaction. Bose-Einstein condensation of this exciton state has long been the subject of speculation in various model systems, and examples have been found more recently in optical lattices and two-dimensional materials. Unlike these conventional excitons formed from extended Bloch states, excitonic bound states from intrinsically many-body localized states are rare.
View Article and Find Full Text PDFTuning electrical conductivity of semiconducting materials through substitutional doping is crucial for fabricating functional devices. This, however, has not been fully realized in two-dimensional (2D) materials due to the difficulty of homogeneously controlling the dopant concentrations and the lack of systematic study of the net impact of substitutional dopants separate from that of the unintentional doping from the device fabrication processes. Here, we grow wafer-scale, continuous MoS monolayers with tunable concentrations of Nb and Re and fabricate devices using a polymer-free approach to study the direct electrical impact of substitutional dopants in MoS monolayers.
View Article and Find Full Text PDFCorrection for 'Anomalous polarization dependence of Raman scattering and crystallographic orientation of black phosphorus' by Jungcheol Kim et al., Nanoscale, 2015, 7, 18708-18715, DOI: 10.1039/C5NR04349B.
View Article and Find Full Text PDFRaman spectroscopy has been established as one of the core experimental tools to study two-dimensional materials (2DMs) including graphene, black phosphorus, transitional metal chalcogenides, and other layered materials. If the polarization of the incident photons and the scattered photons are carefully controlled, the selection rules for the Raman scattering from phonon modes allow accurate mode assignments, which is not always possible in Raman scattering measurements using unpolarized light. Furthermore, polarized Raman spectroscopy can be used to determine the crystallographic orientation of isotropic 2DMs with in-plane strain or anisotropic 2DMs.
View Article and Find Full Text PDFThree types of carbon nanoscroll (CNS) structures that are formed when scrolling up graphene sheets are investigated using Raman spectroscopy and atomic force microscopy (AFM). The CNSs were produced from exfoliated monolayer graphene deposited on a Si chip by applying a droplet of isopropyl alcohol (IPA) solution. The three types of CNS are classified as single-elliptical-core, double-elliptical-core (both with large internal volumes) and collapsed ribbon-like, based on AFM surface profile measurements.
View Article and Find Full Text PDFGallium selenide (GaSe) is one of the layered group-III metal monochalcogenides, which has an indirect bandgap in the monolayer and a direct bandgap in bulk unlike other conventional transition metal dichalcogenides (TMDs) such as MoX and WX (X = S and Se). Four polytypes of bulk GaSe, designated as β-, ε-, γ-, and δ-GaSe, have been reported. Since different polytypes result in different optical and electrical properties even with the same thickness, identifying the polytype is essential in utilizing this material for various optoelectronic applications.
View Article and Find Full Text PDFGraph theory-based reaction pathway searches (ACE-Reaction program) and density functional theory calculations were performed to shed light on the mechanisms for the production of [a + H], x, y, z, and [y + 2H] fragments formed in free radical-initiated peptide sequencing (FRIPS) mass spectrometry measurements of a small model system of glycine-glycine-arginine (GGR). In particular, the graph theory-based searches, which are rarely applied to gas-phase reaction studies, allowed us to investigate reaction mechanisms in an exhaustive manner without resorting to chemical intuition. As expected, radical-driven reaction pathways were favorable over charge-driven reaction pathways in terms of kinetics and thermodynamics.
View Article and Find Full Text PDFThe large-scale synthesis of high-quality thin films with extensive tunability derived from molecular building blocks will advance the development of artificial solids with designed functionalities. We report the synthesis of two-dimensional (2D) porphyrin polymer films with wafer-scale homogeneity in the ultimate limit of monolayer thickness by growing films at a sharp pentane/water interface, which allows the fabrication of their hybrid superlattices. Laminar assembly polymerization of porphyrin monomers could form monolayers of metal-organic frameworks with Cu linkers or covalent organic frameworks with terephthalaldehyde linkers.
View Article and Find Full Text PDFNanotechnology
November 2019
Two-dimensional magnetic van der Waals (vdW) materials have attracted much interest recently. Magnetism in two dimensions is one of the most fascinating topics in condensed matter physics whereas atomically thin magnetic materials present new opportunities for novel spintronic devices. Raman spectroscopy has been established as an invaluable tool in the studies of such magnetic vdW materials as it has been found that the magnetic ordering, which is often difficult to probe directly in atomically thin samples, can be reliably monitored by Raman spectroscopy.
View Article and Find Full Text PDFScreening and identifying unknown erectile dysfunction (ED) drugs and analogues, which are often illicitly added to health supplements, is a challenging analytical task. The analytical technique most commonly used for this purpose, liquid chromatography-tandem mass spectrometry (LC-MS/MS), is based on the strategy of searching the LC-MS/MS spectra of target compounds against database spectra. However, such a strategy cannot be applied to unknown ED drugs and analogues.
View Article and Find Full Text PDFEstrogen receptor alpha (ERα) is a sex hormone nuclear receptor that regulates various physiological events, including the immune response. Although there have been some recent studies on ERα regarding subsets of T cells, such as Th1, Th2, Th17, and Treg cells, its role in follicular helper T (TFH) cells has not yet been elucidated. To determine whether ERα controls TFH response and antibody production, we generated T cell-specific ERα knockout (KO) mice by utilizing the CD4-Cre/ERα flox system (CD4-ERα KO) and then analyzed their phenotype.
View Article and Find Full Text PDFAs the elements of integrated circuits are downsized to the nanoscale, the current Cu-based interconnects are facing limitations due to increased resistivity and decreased current-carrying capacity because of scaling. Here, the bottom-up synthesis of single-crystalline WTe nanobelts and low- and high-field electrical characterization of nanoscale interconnect test structures in various ambient conditions are reported. Unlike exfoliated flakes obtained by the top-down approach, the bottom-up growth mode of WTe nanobelts allows systemic characterization of the electrical properties of WTe single crystals as a function of channel dimensions.
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