Colossal angular magnetoresistance in ferrimagnetic nodal-line semiconductors.

Efficient magnetic control of electronic conduction is at the heart of spintronic functionality for memory and logic applications1,2. Magnets with topological band crossings serve as a good material platform for such control, because their topological band degeneracy can be readily tuned by spin configurations, dramatically modulating electronic conduction3-10. Here we propose that the topological nodal-line degeneracy of spin-polarized bands in magnetic semiconductors induces an extremely large angular response of magnetotransport. Taking a layered ferrimagnet, Mn3Si2Te6, and its derived compounds as a model system, we show that the topological band degeneracy, driven by chiral molecular orbital states, is lifted depending on spin orientation, which leads to a metal-insulator transition in the same ferrimagnetic phase. The resulting variation of angular magnetoresistance with rotating magnetization exceeds a trillion per cent per radian, which we call colossal angular magnetoresistance. Our findings demonstrate that magnetic nodal-line semiconductors are a promising platform for realizing extremely sensitive spin- and orbital-dependent functionalities.

Quantum distance and anomalous Landau levels of flat bands.

Semiclassical quantization of electronic states under a magnetic field, as proposed by Onsager, describes not only the Landau level spectrum but also the geometric responses of metals under a magnetic field1-5. Even in graphene with relativistic energy dispersion, Onsager's rule correctly describes the π Berry phase, as well as the unusual Landau level spectrum of Dirac particles6,7. However, it is unclear whether this semiclassical idea is valid in dispersionless flat-band systems, in which an infinite number of degenerate semiclassical orbits are allowed. Here we show that the semiclassical quantization rule breaks down for a class of dispersionless flat bands called 'singular flat bands'8. The singular flat band has a band crossing with another dispersive band that is enforced by the band-flatness condition, and shows anomalous magnetic responses. The Landau levels of a singular flat band develop in the empty region in which no electronic states exist in the absence of a magnetic field, and exhibit an unusual 1/n dependence on the Landau level index n, which results in diverging orbital magnetic susceptibility. The total energy spread of the Landau levels of a singular flat band is determined by the quantum geometry of the relevant Bloch states, which is characterized by their Hilbert-Schmidt quantum distance. We show that there is a universal and simple relationship between the total Landau level spread of a flat band and the maximum Hilbert-Schmidt quantum distance, which can be verified in various candidate materials. The results indicate that the anomalous Landau level spectrum of flat bands is promising for the direct measurement of the quantum geometry of wavefunctions in condensed matter.

Exploring Molecular Genetic Alterations and RAF Fusions in Melanoma: A Belvarafenib Expanded Access Program in Patients with RAS/RAF-Mutant Melanoma.

BACKGROUND: Melanoma incidence is on the rise in East Asia, yet studies of the molecular landscape are lacking in this population. We examined patients with melanoma who underwent next-generation sequencing (NGS) at a single tertiary center in South Korea, focusing on patients harboring NRAS or RAF alterations who received belvarafenib, a pan-RAF dimer inhibitor, through the Expanded Access Program (EAP). PATIENTS AND METHODS: Data were collected from 192 patients with melanoma who underwent NGS between November 2017 and May 2023. Variant call format data were obtained and annotated. Patients in the EAP received 450 mg twice daily doses of belvarafenib. RESULTS: Alterations in the RAS/RTK pathway were the most prevalent, with BRAF and NRAS alteration rates of 22.4% and 17.7%, respectively. NGS enabled additional detection of fusion mutations, including 6 BRAF and 1 RAF1 fusion. Sixteen patients with NRAS or RAF alterations received belvarafenib through the EAP, and disease control was observed in 50%, with 2 patients demonstrating remarkable responses. CONCLUSIONS: Our study highlights the value of NGS in detecting BRAF, NRAS mutations and RAF fusions, expanding possibilities for targeted therapies in malignant melanoma. Belvarafenib showed clinical benefit in patients harboring these alterations. Ongoing trials will provide further insights into the safety and efficacy of belvarafenib.

Direct Observation of Orbital Driven Strong Interlayer Coupling in Puckered Two-Dimensional PdSe2.

Interlayer coupling between individual unit layers is known to be critical in manipulating the layer-dependent properties of two-dimensional (2D) materials. While recent studies have revealed that several 2D materials with significant degrees of interlayer interaction (such as black phosphorus) show strongly layer-dependent properties, the origin based on the electronic structure is drawing intensive attention along with 2D materials exploration. Here, the direct observation of a highly dispersive single electronic band along the interlayer direction in puckered 2D PdSe2 as an experimental hallmark of strong interlayer couplings is reported. Remarkably large band dispersion along the kz -direction near Fermi level, which is even wider than the in-plane one, is observed by the angle-resolved photoemission spectroscopy measurement. Employing X-ray absorption spectroscopy and density functional theory calculations, it is revealed that the strong interlayer coupling in 2D PdSe2 originates from the unique directional bonding of Pd d orbitals associated with unexpected Pd 4d9 configuration, which consequently plays a decisive role for the strong layer-dependency of the band gap.

First-line pembrolizumab versus dabrafenib/trametinib treatment for BRAF V600-mutant advanced melanoma.

BACKGROUND: Limited data are available to assist the selection between immune checkpoint inhibitors and BRAF/mitogen-activated protein kinase kinase inhibitors as first-line treatment for patients with BRAF-mutant advanced malignant melanoma. OBJECTIVE: To investigate the outcomes associated with first-line pembrolizumab or dabrafenib/trametinib treatment for advanced melanoma with activating BRAF V600 mutation. METHODS: Data of patients with BRAF V600-mutant melanoma who were treated with first-line pembrolizumab (n = 40) or dabrafenib/trametinib (n = 32) were analyzed. Tumor response, progression-free survival, and overall survival were evaluated. Immune evasion accompanied with emerging resistance to BRAF/mitogen-activated protein kinase kinase inhibitors was assessed. RESULTS: A longer overall survival was observed after first-line pembrolizumab treatment than after first-line dabrafenib/trametinib treatment (hazard ratio = 2.910, 95% CI: 1.552-5.459), although there were no significant differences in progression-free survival (P = .375) and response rate (P = .123). Emergence of resistance to dabrafenib/trametinib co-occurred with immune evasion, enabling melanoma cells to escape recognition and killing by Melan-A-specific CD8+ T cells. LIMITATIONS: Analysis was conducted in a retrospective manner. CONCLUSION: Pembrolizumab may be recommended over BRAF/mitogen-activated protein kinase kinase inhibitors as the first-line treatment in patients with advanced BRAF V600-mutant melanoma.

Molecular Detection and Genetic Diversity of Blastocystis in Korean Dogs.

Blastocystis is a genus of unicellular heterokont parasites belonging to a group of organisms known as Stramenopiles, which includes algae, diatoms, and water molds. Blastocystis includes several species that habitat in the gastrointestinal tracts of organisms as diverse as humans, farm animals, birds, rodents, reptiles, amphibians, fish, and cockroaches. It is important to public health and distributed globally, but its prevalence in dogs in Korea has not been reported to date. Here, we collected 787 canine fecal samples and assessed Blastocystis infection by age, sex, region, season, and diarrhea symptoms. We determined Blastocystis subtypes using phylogenetic analyses based on 18S rRNA gene sequences. We identified, 10 Blastocystis positive samples (1.3%). A higher proportion of infected dogs was asymptomatic; however, infection rates did not significantly differ according to region, age, sex, and season. Phylogenetic analysis showed that the Blastocystis sp. identified belonged to 4 subtypes (STs), ST1, ST5, ST10, and ST14, thus revealed the genetic diversity of Blastocystis sp. in dogs Korean. This is first report on the presence of Blastocystis sp. in dogs Korean. This study revealed a lower infection rate than expected and differed from previous studies in STs. Further studies are warranted to observe the national infection status of Blastocystis in dogs and the genetic characteristics of this genus.

Unusual Pressure-Induced Quantum Phase Transition from Superconducting to Charge-Density Wave State in Rare-Earth-Based Heusler LuPd_{2}In Compound.

We investigate the pressure effects on the electronic structures and phonon properties of rare-earth-based cubic-Heusler compound LuPd_{2}In, on the basis of ab initio density functional theory. We find the occurrence of intriguing phase transition from the superconducting (SC) to charge-density wave (CDW) state under pressure (P), which is quite unusual in that the pressure is detrimental to the CDW state in usual systems. The SC transition temperature T_{C} of LuPd_{2}In increases first with increasing pressure, up to P_{C}≈28 GPa, above which a quantum phase transition into the CDW state takes place. This extraordinary transition originates from the occurrence of phonon softening instability at a special q=M in the Brillouin zone. We thus propose that LuPd_{2}In is a quite unique material, in which the CDW quantum critical point is realized under the SC dome by applying the pressure.

Association between exposure to traffic-related air pollution and pediatric allergic diseases based on modeled air pollution concentrations and traffic measures in Seoul, Korea: a comparative analysis.

BACKGROUND: Pediatric allergic diseases are a major public health concern, and previous studies have suggested that exposure to traffic-related air pollution (TRAP) exposure is a risk factor. These studies have typically assessed TRAP exposure using traffic measures, such as distance to major roads, or by modeling air pollutant concentrations; however inconsistent associations with pediatric allergic diseases have often been found. Using road proximity and density, we previously found an association between TRAP and atopic eczema among approximately 15,000 children living in Seoul, Korea, heavily populated and highly polluted city in which traffic is a major emission source. We aimed to conduct a parallel analysis using modeled air pollution concentrations and thus examine the consistency of the association. Specifically, we examined the associations of individual-level annual-average concentrations of NO2, PM10, and PM2.5 with symptoms and diagnoses of three pediatric allergic diseases including asthma, allergic rhinitis, and atopic eczema. METHODS: The study population included 14,614 children from the Seoul Atopy Friendly School Project Survey in Seoul, Korea, in 2010. To assess individual exposures to TRAP among these children, we predicted annual-average concentrations of NO2, PM10, and PM2.5 at the children's home addresses in 2010 using universal kriging and land use regression models along with regulatory air quality monitoring data and geographic characteristics. Then, we estimated odds ratios (ORs) of the three allergic diseases for interquartile increases in air pollution concentrations after adjusting for individual risk factors in mixed effects logistic regression. RESULTS: Symptoms and diagnoses of atopic eczema symptoms showed an association with NO2 (OR = 1.07, 95% confidence interval = 1.02-1.13; 1.08, 1.03-1.14) and PM10 (1.06, 1.01-1.12; 1.07, 1.01-1.13). ORs of PM2.5 were positive but not statistically significant (1.01, 0.95-1.07; 1.04, 0.98-1.10). No association was found between asthma and allergic rhinitis, although PM2.5 showed a marginal association with allergic rhinitis. CONCLUSIONS: Our consistent findings regarding the association between TRAP and the prevalence of atopic eczema using traffic measures and surrogate air pollutants suggested the effect of TRAP on children's health. Follow-up studies should elucidate the causal link, to support subsequent policy considerations and minimize adverse health effects in children.

Large anomalous Hall current induced by topological nodal lines in a ferromagnetic van der Waals semimetal.

Topological semimetals host electronic structures with several band-contact points or lines and are generally expected to exhibit strong topological responses. Up to now, most work has been limited to non-magnetic materials and the interplay between topology and magnetism in this class of quantum materials has been largely unexplored. Here we utilize theoretical calculations, magnetotransport and angle-resolved photoemission spectroscopy to propose Fe3GeTe2, a van der Waals material, as a candidate ferromagnetic (FM) nodal line semimetal. We find that the spin degree of freedom is fully quenched by the large FM polarization, but the line degeneracy is protected by crystalline symmetries that connect two orbitals in adjacent layers. This orbital-driven nodal line is tunable by spin orientation due to spin-orbit coupling and produces a large Berry curvature, which leads to a large anomalous Hall current, angle and factor. These results demonstrate that FM topological semimetals hold significant potential for spin- and orbital-dependent electronic functionalities.

Giant Magnetic Anisotropy Induced by Ligand LS Coupling in Layered Cr Compounds.

We propose a novel origin of magnetic anisotropy to explain the unusual magnetic behaviors of layered ferromagnetic Cr compounds (3d^{3}) wherein the anisotropy field varies from ≲0.01 to ∼3 T on changing the ligand atom in a common hexagonal structure. The effect of the ligand p orbital spin-orbit (LS) coupling on the magnetic anisotropy is explored by using four-site full multiplet cluster model calculations for energies involving the superexchange interaction at different spin axes. Our calculation shows that the anisotropy energy, which is the energy difference for different spin axes, is strongly affected not only by the LS coupling strength but also by the degree of p-d covalency in the layered geometry. This anisotropy energy involving the superexchange appears to dominate the magnetic anisotropy and even explains the giant magnetic anisotropy as large as 3 T observed in CrI_{3}.

Hydrogen interaction with a sulfur-vacancy-induced occupied defect state in the electronic band structure of MoS2.

Identifying and designing defects are critical steps in the development of a semiconductor. We unveil that a sufficiently high concentration of the sulfur-vacancy defect on the MoS2 surface induces an occupied defect state in the electronic band structures, in addition to the in-gap defect states. The occupied defect state is expected to appear above and below the valence band maximum (VBM) of the mono- and bilayer or bulk band structures of MoS2, respectively. Furthermore, the hydrogen interaction with the sulfur-vacancy defect reconstructs the band structure of MoS2 to have multi VBMs or ambipolar valence bands depending on the layer thickness. Finally, we find that the polarity switching of MoS2 from n-type to p-type conductivity depends on the type of hydrogen bonds at/around the sulfur-vacancy defect.

Persistent Charge-Density-Wave Order in Single-Layer TaSe2.

We present the electronic characterization of single-layer 1H-TaSe2 grown by molecular beam epitaxy using a combined angle-resolved photoemission spectroscopy, scanning tunneling microscopy/spectroscopy, and density functional theory calculations. We demonstrate that 3 × 3 charge-density-wave (CDW) order persists despite distinct changes in the low energy electronic structure highlighted by the reduction in the number of bands crossing the Fermi energy and the corresponding modification of Fermi surface topology. Enhanced spin-orbit coupling and lattice distortion in the single-layer play a crucial role in the formation of CDW order. Our findings provide a deeper understanding of the nature of CDW order in the two-dimensional limit.

Emergence of Kondo Resonance in Graphene Intercalated with Cerium.

The interaction between a magnetic impurity, such as cerium (Ce) atom, and surrounding electrons has been one of the core problems in understanding many-body interaction in solid and its relation to magnetism. Kondo effect, the formation of a new resonant ground state with quenched magnetic moment, provides a general framework to describe many-body interaction in the presence of magnetic impurity. In this Letter, a combined study of angle-resolved photoemission (ARPES) and dynamic mean-field theory (DMFT) on Ce-intercalated graphene shows that Ce-induced localized states near Fermi energy, EF, hybridized with the graphene π-band, exhibit gradual increase in spectral weight upon decreasing temperature. The observed temperature dependence follows the expectations from the Kondo picture in the weak coupling limit. Our results provide a novel insight how Kondo physics emerges in the sea of two-dimensional Dirac electrons.

Regulation of proliferation and invasion by the IGF signalling pathway in Epstein-Barr virus-positive gastric cancer.

Several carcinomas including gastric cancer have been reported to contain Epstein-Barr virus (EBV) infection. EBV-associated gastric cancer (EBVaGC) is classified as one of four molecular subtypes of gastric cancer by The Cancer Genome Atlas (TCGA) group with increased immune-related signatures. Identification of EBV-dependent pathways with significant biological roles is needed for EBVaGC. To compare the biological changes between AGS gastric epithelial cells and EBV-infected AGS (AGS-EBV) cells, proliferation assay, CCK-8 assay, invasion assay, cell cycle analysis, RT-PCR, Western blot and ELISA were performed. BI836845, a humanized insulin-like growth factor (IGF) ligand-neutralizing antibody, was used for IGF-related signalling pathway inhibition. AGS-EBV cells showed slower proliferating rate and higher sensitivity to BI836845 compared to AGS cells. Moreover, invasiveness of AGS-EBV was increased than that of AGS, and BI836845 treatment significantly decreased the invasiveness of AGS-EBV. Although no apoptosis was detected, entry into the S phase of the cell cycle was delayed in BI836845-treated AGS-EBV cells. In conclusion, AGS-EBV cells seem to modulate their proliferation and invasion through the IGF signalling pathway. Inhibition of the IGF signalling pathway therefore could be a potential therapeutic strategy for EBVaGC.

Experimental Realization of Type-II Dirac Fermions in a PdTe_{2} Superconductor.

A Dirac fermion in a topological Dirac semimetal is a quadruple-degenerate quasiparticle state with a relativistic linear dispersion. Breaking either time-reversal or inversion symmetry turns this system into a Weyl semimetal that hosts double-degenerate Weyl fermion states with opposite chiralities. These two kinds of quasiparticles, although described by a relativistic Dirac equation, do not necessarily obey Lorentz invariance, allowing the existence of so-called type-II fermions. The recent theoretical discovery of type-II Weyl fermions evokes the prediction of type-II Dirac fermions in PtSe_{2}-type transition metal dichalcogenides, expecting experimental confirmation. Here, we report an experimental realization of type-II Dirac fermions in PdTe_{2} by angle-resolved photoemission spectroscopy combined with ab initio band calculations. Our experimental finding shows the first example that has both superconductivity and type-II Dirac fermions, which turns the topological material research into a new phase.

Observation of variable hybridized-band gaps in Eu-intercalated graphene.

We report europium (Eu)-induced changes in the π-band of graphene (G) formed on the 6H-SiC(0001) surface by a combined study of photoemission measurements and density functional theory (DFT) calculations. Our photoemission data reveal that Eu intercalates upon annealing at 120 °C into the region between the graphene and the buffer layer (BL) to form a G/Eu/BL system, where a band gap of 0.29 eV opens at room temperature. This band gap is found to increase further to 0.48 eV upon cooling down to 60 K. Our DFT calculations suggest that the increased band gap originates from the enhanced hybridization of the graphene π-band with the Eu 4f band due to the increased magnetic ordering upon cooling. These Eu atoms continue to intercalate further down below the BL to produce bilayer graphene (G/BL/Eu) upon annealing at 300 °C. The π-band stemming from the BL then exhibits another band gap of 0.37 eV, which appears to be due to the strong hybridization between the π-band of the BL and the Eu 4f band. The Eu-intercalated graphene thus illustrates an example of versatile band gaps formed under different thermal treatments, which may play a critical role for future applications in graphene-based electronics.

Nanoscale Superconducting Honeycomb Charge Order in IrTe2.

Entanglement of charge orderings and other electronic orders such as superconductivity is in the core of challenging physics issues of complex materials including high temperature superconductivity. Here, we report on the observation of a unique nanometer scale honeycomb charge ordering of the cleaved IrTe2 surface, which hosts a superconducting state. IrTe2 was recently established to exhibit an intriguing cascade of stripe charge orders. The stripe phases coexist with a hexagonal phase, which is formed locally and falls into a superconducting state below 3 K. The atomic and electronic structures of the honeycomb and hexagon pattern of this phase are consistent with the charge order nature, but the superconductivity does not survive on neighboring stripe charge order domains. The present work provides an intriguing physics issue and a new direction of functionalization for two-dimensional materials.

Characteristics of Workplace Injuries among Nineteen Thousand Korean Firefighters.

To determine the actual firefighter injury statistics in Korea, we conducted a survey on the nature of on-duty injuries among all male firefighters in Korea. We distributed questionnaires to all Korean male firefighters via email, and data from the 19,119 workers that responded were used for data analysis. The job types were categorized into fire suppression, emergency medical service (EMS) and officers. As estimated of age standardized injury prevalence per one thousand workers, 354 fire extinguishing personnel, 533 EMS workers, and 228 officers experienced one or more injuries during the previous 12 months. The odds ratio (95% confidence interval) of injuries was 1.86 (1.61-2.15) for fire suppression and 2.93 (2.51-3.42) for EMS personnel compared to officers after adjusting for age, marital status, smoking habit and career period. Age standardized absence days from work due to injuries per one thousand workers were 1,120, 1,337, and 676 for fire suppression, EMS and officers, respectively. Car accident (24.5%) was the most common cause and wound (42.3%) was the most common type of injuries. Our nationwide representative study showed that fire suppression and EMS workers are at greater risk of on-duty injuries compared to officers. We observed different injury characteristics compared to those reported in other countries.

Conditional ablation of LYVE-1+ cells unveils defensive roles of lymphatic vessels in intestine and lymph nodes.

To unveil the organotypic role and vulnerability of lymphatic vessels, we generated a lymphatic vessel endothelial hyaluronan receptor-1 (LYVE-1)-Cre/iDTR double-transgenic mouse and ablated LYVE-1-expressing lymphatic vessels in adult mice in a diphtheria toxin (DT)-inducible manner based on selective expression of LYVE-1 in most lymphatic vessels. Strikingly, lymphatic vessels in the small intestine and lymph nodes were rapidly ablated, but lymphatic vessels in the other organs were relatively intact at 24 hours after DT administration. Unexpectedly, LYVE-1-Cre/iDTR mice died of sepsis without visible edema at 24 and 60 hours after DT administration. The cause of death appeared to be related to acute failure of immune surveillance systems in the small intestine and draining lymph nodes. Of note, acute loss of lymphatic lacteals in intestinal villi appeared to trigger distortion of blood capillaries and the whole architecture of the villi, whereas acute loss of lymphatic vessels in lymph nodes caused dysfunction of lymph drainage and abnormal distribution of dendritic cells and macrophages. Thus, intact lymphatic vessels are required for structural and functional maintenance of surrounding tissues in an organotypic manner, at least in the intestine and lymph nodes.