267 research outputs found
Emergent Energy Dissipation in Quantum Limit
Energy dissipation is of fundamental interest and crucial importance in
quantum systems. However, whether energy dissipation can emerge inside
topological systems remains a question, especially when charge transport is
topologically protected and quantized. As a hallmark, we propose a microscopic
picture that illustrates energy dissipation in the quantum Hall (QH) plateau
regime of graphene. Despite the quantization of Hall, longitudinal, and
two-probe resistances (dubbed as the quantum limit), we find that the energy
dissipation emerges in the form of Joule heat. By analyzing the energy
distribution of electrons, it is found that electrons can evolve between
equilibrium and non-equilibrium without inducing extra two-probe resistance.
The relaxation of non-equilibrium electrons results in the dissipation of
energy along the QH edge states. Eventually, we suggest probing the phenomenon
by measuring local temperature increases in experiments and reconsidering the
dissipation typically ignored in realistic topological circuits.Comment: 7 pages, 4 figures
Transport theory in non-Hermitian systems
Non-Hermitian systems have garnered significant attention due to the
emergence of novel topology of complex spectra and skin modes. However,
investigating transport phenomena in such systems faces obstacles stemming from
the non-unitary nature of time evolution. Here, we establish the continuity
equation for a general non-Hermitian Hamiltonian in the Schr\"odinger picture.
It attributes the universal non-conservativity to the anti-commutation
relationship between particle number and non-Hermitian terms. Our work derives
a comprehensive current formula for non-Hermitian systems using Green's
function, applicable to both time-dependent and steady-state responses. To
demonstrate the validity of our approach, we calculate the local current in
models with one-dimensional and two-dimensional settings, incorporating
scattering potentials. The spatial distribution of local current highlights the
widespread non-Hermitian phenomena, including skin modes, non-reciprocal
quantum dots, and corner states. Our findings offer valuable insights for
advancing theoretical and experimental research in the transport of
non-Hermitian systems
Perspectives on Primary Blast Injury of the Brain: Translational Insights Into Non-inertial Low-Intensity Blast Injury
Most traumatic brain injuries (TBIs) during military deployment or training are clinically βmildβ and frequently caused by non-impact blast exposures. Experimental models were developed to reproduce the biological consequences of high-intensity blasts causing moderate to severe brain injuries. However, the pathophysiological mechanisms of low-intensity blast (LIB)-induced neurological deficits have been understudied. This review provides perspectives on primary blast-induced mild TBI models and discusses translational aspects of LIB exposures as defined by standardized physical parameters including overpressure, impulse, and shock wave velocity. Our mouse LIB-exposure model, which reproduces deployment-related scenarios of open-field blast (OFB), caused neurobehavioral changes, including reduced exploratory activities, elevated anxiety-like levels, impaired nesting behavior, and compromised spatial reference learning and memory. These functional impairments associate with subcellular and ultrastructural neuropathological changes, such as myelinated axonal damage, synaptic alterations, and mitochondrial abnormalities occurring in the absence of gross- or cellular damage. Biochemically, we observed dysfunctional mitochondrial pathways that led to elevated oxidative stress, impaired fission-fusion dynamics, diminished mitophagy, decreased oxidative phosphorylation, and compensated cell respiration-relevant enzyme activity. LIB also induced increased levels of total tau, phosphorylated tau, and amyloid Ξ² peptide, suggesting initiation of signaling cascades leading to neurodegeneration. We also compare translational aspects of OFB findings to alternative blast injury models. By scoping relevant recent research findings, we provide recommendations for future preclinical studies to better reflect military-operational and clinical realities. Overall, better alignment of preclinical models with clinical observations and experience related to military injuries will facilitate development of more precise diagnosis, clinical evaluation, treatment, and rehabilitation
Template synthesis of palladium nanotubes and their electrocatalytic properties
Palladium nanotubes were prepared by using silver nanowires as the template, which were prepared in a modified polyol reduction process. The morphology and structure of silver nanowires and palladium nanotubes were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Electrochemical experimental data showed that palladium nanotubes displayed high electrocatalytic activity toward the electrooxidation of alcohols, especially for ethanol. The formation mechanism of palladium nanotubes as well as the relationship between their structure and electrocatalytic activity was discussed based on the experimental results
Anomalous quantized plateaus in two-dimensional electron gas with gate confinement
Quantum information can be coded by the topological protected edges of
fractional quantum Hall (FQH) states. Investigation on FQH edges in the hope of
searching and utilizing non-Abelian statistics has been a focused challenge for
years. Manipulating the edges, e.g. to bring edges close to each other or to
separate edges spatially, is a common and essential step for such studies. The
FQH edge structures in a confined region are typically presupposed to be the
same as that in the open region in analysis of experimental results, but
whether they remain unchanged with extra confinement is obscure. In this work,
we present a series of unexpected plateaus in a confined single-layer
two-dimensional electron gas (2DEG), which are quantized at anomalous fractions
such as 3/2, 9/4, 17/11 and 16/13. We explain all the plateaus by assuming
surprisingly larger filling factors in the confined region, and determine the
edge structures of FQH states with and without confinement together simply from
the quantization value. The information of the 5/2, 5/3, 8/5 and 7/5 FQH edge
modes in the dimension of ~1 micron have been probed, which is crucial for the
experiments with quantum point contact and interferometer.Comment: 13 pages, 4 figures + 9 pages, 4 figure
Carvacrol, a Food-Additive, Provides Neuroprotection on Focal Cerebral Ischemia/Reperfusion Injury in Mice
Carvacrol (CAR), a naturally occurring monoterpenic phenol and food additive, has been shown to have antimicrobials, antitumor, and antidepressant-like activities. A previous study demonstrated that CAR has the ability to protect liver against ischemia/reperfusion injury in rats. In this study, we investigated the protective effects of CAR on cerebral ischemia/reperfusion injury in a middle cerebral artery occlusion mouse model. We found that CAR (50 mg/kg) significantly reduced infarct volume and improved neurological deficits after 75 min of ischemia and 24 h of reperfusion. This neuroprotection was in a dose-dependent manner. Post-treatment with CAR still provided protection on infarct volume when it was administered intraperitoneally at 2 h after reperfusion; however, intracerebroventricular post-treatment reduced infarct volume even when the mice were treated with CAR at 6 h after reperfusion. These findings indicated that CAR has an extended therapeutic window, but delivery strategies may affect the protective effects of CAR. Further, we found that CAR significantly decreased the level of cleaved caspase-3, a marker of apoptosis, suggesting the anti-apoptotic activity of CAR. Finally, our data indicated that CAR treatment increased the level of phosphorylated Akt and the neuroprotection of CAR was reversed by a PI3K inhibitor LY-294002, demonstrating the involvement of the PI3K/Akt pathway in the anti-apoptotic mechanisms of CAR. Due to its safety and wide use in the food industry, CAR is a promising agent to be translated into clinical trials
Electrostatic-Assembly-Driven Formation of Supramolecular Rhombus Microparticles and Their Application for Fluorescent Nucleic Acid Detection
In this paper, we report on the large-scale formation of supramolecular rhombus
microparticles (SRMs) driven by electrostatic assembly, carried out by direct
mixing of an aqueous HAuCl4 solution and an ethanol solution of
4,4β²-bipyridine at room temperature. We further demonstrate their use as
an effective fluorescent sensing platform for nucleic acid detection with a high
selectivity down to single-base mismatch. The general concept used in this
approach is based on adsorption of the fluorescently labeled single-stranded DNA
(ssDNA) probe by SRM, which is accompanied by substantial fluorescence
quenching. In the following assay, specific hybridization with its target to
form double-stranded DNA (dsDNA) results in desorption of ssDNA from SRM surface
and subsequent fluorescence recovery
A Bi-Functional Anti-Thrombosis Protein Containing Both Direct-Acting Fibrin(ogen)olytic and Plasminogen-Activating Activities
Direct-acting fibrin(ogen)olytic agents such as plasmin have been proved to contain effective and safety thrombolytic potential. Unfortunately, plasmin is ineffective when administered by the intravenous route because it was neutralized by plasma antiplasmin. Direct-acting fibrin(ogen)olytic agents with resistance against antiplasmin will brighten the prospect of anti-thrombosis. As reported in βCompendium of Materia Medicaβ, the insect of Eupolyphaga sinensis Walker has been used as traditional anti-thrombosis medicine without bleeding risk for several hundreds years. Currently, we have identified a fibrin(ogen)olytic protein (Eupolytin1) containing both fibrin(ogen)olytic and plasminogen-activating (PA) activities from the beetle, E. sinensis. Objectives: To investigate the role of native and recombinant eupolytin1 in fibrin(ogen)olytic and plasminogen-activating processes. Methods and Results: Using thrombus animal model, eupolytin1 was proved to contain strong and rapid thrombolytic ability and safety in vivo, which are better than that of urokinase. Most importantly, no bleeding complications were appeared even the intravenous dose up to 0.12 Β΅mol/kg body weight (3 times of tested dose which could completely lyse experimental thrombi) in rabbits. It is the first report of thrombolytic agents containing both direct-acting fibrin(ogen)olytic and plasminogen-activating activities. Conclusions: The study identified novel thrombolytic agent with prospecting clinical potential because of its bi-functional merits containing both plasmin- and PA-like activities and unique pharmacological kinetics in vivo
- β¦