Browse Articles

Switchable linear to circular polarization conversion in reflection and transmission modes based on vanadium-dioxide

Abstract A design of a switchable dual-mode linear-to-circular polarization converter (LTC-PC) in the terahertz (THz) band is reported based on vanadium dioxide (VO2). Adjusting the VO2 state allows the converter to alternate between the transmission and reflection modes. In the insulating state, VO2 enables transmission mode operation for a forward x- or y-polarized wave. LTC polarization conversion occurs within the frequency bands of 1.26–1.47 THz and 1.83–1.85 THz. Moreover, this mode yields an LTC polarization conversion at a frequency of 1.7 THz. The polarizer operates in reflection mode when VO2 is in the metallic state. Two conversion bands are identified for circular polarization within the frequency bands of 0.93–1.67 THz and 1.80–1.86 THz. The dual-mode polarization converter achieves axial ratios below 3 dB and a polarization conversion efficiency greater than 0.8. Surface current distributions reveal the polarization conversion mechanisms. Furthermore, we analyze the polarization ellipses of both reflected and transmitted waves at various frequencies across the operational bands. We anticipate that the proposed design, featuring high performance and dual functionality, will be applicable in THz communication systems and sensors.

Robust direct voltage control of stand-alone DFIG wind systems using a fractional-order fuzzy logic approach

Well-Aligned Liquid Crystal Interface and Expanded Solvation Sheath Accelerate Zn²⁺ Desolvation Kinetics for Stable Zinc Batteries

Zearalenone and nanozeolite improve Arugula (Eruca sativa) drought tolerance by enhancing photosynthesis and water relations

The effect of cooling rate and content of niobium on the structure, wear and corrosion resistance of CoCrFeNiNbx high entropy alloys

Abstract In this work, CoCrFeNiNbx (x = 0.25, 0.45 and 0.65) high entropy alloys were prepared by two different methods to determine the effect of cooling rate and the niobium content on the structure and properties of ingots and plates. The structure was investigated extensively using X-ray diffraction, scanning electron microscopy, and Mössbauer spectroscopy. The results confirmed the dual-phase structure, consisting of the FCC solid solution and the Laves phase. The increase in niobium content changed the microstructure from hypoeutectic (x = 0.25 and 0.45) to hypereutectic (x = 0.65). The high cooling rate during solidification from the liquid state enabled the formation of ultrafine eutectic structures with an average lamellae thickness of only 130 ± 9 nm in the CoCrFeNiNb0.65 plate. The corrosion behaviour of the alloys was studied in solutions of 3.5% NaCl and 3.5% NaCl + H3BO3. The beneficial effect of increasing the niobium content in as-cast CoCrFeNiNbx alloys on the corrosion resistance was confirmed in both environments. Furthermore, the alloys solidified with a higher cooling rate exhibited a lower corrosion susceptibility in the 3.5% NaCl solution. The results of the EIS study indicated that a higher content of niobium contributed to the formation of a more stable and compact passivation layer. The hardness of the CoCrFeNiNbx alloys increased with a higher niobium content, achieving the highest value of 669 HV1 for the CoCrFeNiNb0.65 plate. The increase in the cooling rate positively affected the tribological properties of the CoCrFeNiNbx alloys, contributing to the decrease in the friction coefficient for the CoCrFeNiNb0.25 and CoCrFeNiNb0.45 plates.

Identification of Ni–N₄ Active Sites in Atomically Dispersed Ni Catalysts for Efficient Chlorine Evolution Reaction

Development and validation of a CT-measured body composition radiomics model for prognostic assessment in resected pancreatic adenocarcinoma

Cross-species comparison reveals therapeutic vulnerabilities halting glioblastoma progression

Abstract The growth of a tumor is tightly linked to the distribution of its cells along a continuum of activation states. Here, we systematically decode the activation state architecture (ASA) in a glioblastoma (GBM) patient cohort through comparison to adult murine neural stem cells. Modelling of these data forecasts how tumor cells organize to sustain growth and identifies the rate of activation as the main predictor of growth. Accordingly, patients with a higher quiescence fraction exhibit improved outcomes. Further, DNA methylation arrays enable ASA-related patient stratification. Comparison of healthy and malignant gene expression dynamics reveals dysregulation of the Wnt-antagonist SFRP1 at the quiescence to activation transition. SFRP1 overexpression renders GBM quiescent and increases the overall survival of tumor-bearing mice. Surprisingly, it does so through reprogramming the tumor’s stem-like methylome into an astrocyte-like one. Our findings offer a framework for patient stratification with prognostic value, biomarker identification, and therapeutic avenues to halt GBM progression.

A comprehensive study on the impact of He ion irradiation on the microstructure and mechanical properties of a Ni-Cr-Mo alloy

Author Correction: The role of charge in microdroplet redox chemistry

Contrastive representation learning with transformers for robust auditory EEG decoding

Switchable electrochemical pathways for the selective C(sp3)-Ge bond formation

Glial fibrillary acidic protein in plasma and intraocular fluids and the correlation with cognitive function in patients with vitreoretinal disease

Direct Cellular Screening of Pd-Mediated Arylation of Cyclic Peptide Binders Targeting Ubiquitin Chains: Toward Modulating NEMO Liquid–Liquid Phase Separation

How thoughtful experimental design can empower biologists in the omics era

Ginkgolide B attenuates hyperlipidemia by restoring sphingolipid homeostasis and activating PPARα and Nrf2 pathways

A Covalent Self-Reporting Peptide Degrader Enables Real-Time Monitoring of Targeted Protein Degradation In Vivo

Self-sustained frictional cooling in active matter

Abstract Cooling processes in nature are typically generated by external contact with a cold reservoir or bath. According to the laws of thermodynamics, the final temperature of a system is determined by the temperature of the environment. Here, we report a spontaneous internal cooling phenomenon for active particles, occurring without external contact. This effect, termed self-sustained frictional cooling, arises from the interplay between activity and dry (Coulomb) friction, and in addition is self-sustained from particles densely caged by their neighbors. If an active particle moves in its cage, dry friction will stop any further motion after a collision with a neighbor particle thus cooling the particle down to an extremely low temperature. We demonstrate and verify this self-sustained cooling through experiments and simulations on active granular robots and identify dense frictional arrested clusters coexisting with hot, dilute regions. Our findings offer potential applications in two-dimensional swarm robotics, where activity and dry friction can serve as externally tunable mechanisms to regulate the swarm’s dynamical and structural properties.

Multiscale investigation of thermally activated coal gangue aggregate concrete interfacial transition zone evolution and failure mechanisms

Ultra-Narrow Homogeneous Photoluminescence Line Width of Zinc-Blende CdSe-Based Core/Shell Nanocrystals: Dominating Role of Lattice–Ligands Interface