An Analysis Oncrude Oil Price Mutation in View of Zeeman's Catastrophe Machine

AbstractWith the acceleration of internationalmarket integration and the frequent outbreak of international political and economic events, the volatility of oil priceshas continued toincrease in recent years. As the main source of energy, crude oil plays an important role in the development of a country's economy. Therefore, it is meaningful to study the mutation of oil prices. Based on the Zeeman's catastrophe machine, USDX and excess demand are selected as two main factors to construct the catastrophe model, which helps to explain the structural relationship between USDX and excess demand when the crude oil price mutates

3D printed architected hollow sphere foams with low-frequency phononic band gaps

We experimentally and numerically investigate elastic wave propagation in a class of lightweight architected materials composed of hollow spheres and binders. Elastic wave transmission tests demonstrate the existence of vibration mitigation capability in the proposed architected foams, which is validated against the numerically predicted phononic band gap. We further describe that the phononic band gap properties can be significantly altered through changing hollow sphere thickness and binder size in the architected foams. Importantly, our results indicate that by increasing the stiffness contrast between hollow spheres and binders, the phononic band gaps are broadened and shifted toward a low-frequency range. At the threshold stiffness contrast of 50, the proposed architected foam requires only a volume fraction of 10.8% while exhibiting an omnidirectional band gap size exceeding 130%. The proposed design paradigm and physical mechanisms are robust and applicable to architected foams with other topologies, thus providing new opportunities to design phononic metamaterials for low-frequency vibration control

High mobility in a van der Waals layered antiferromagnetic metal

Magnetic van der Waals (vdW) materials have been heavily pursued for fundamental physics as well as for device design. Despite the rapid advances, so far magnetic vdW materials are mainly insulating or semiconducting, and none of them possesses a high electronic mobility - a property that is rare in layered vdW materials in general. The realization of a magnetic high-mobility vdW material would open the possibility for novel magnetic twistronic or spintronic devices. Here we report very high carrier mobility in the layered vdW antiferromagnet GdTe3. The electron mobility is beyond 60,000 cm2 V-1 s-1, which is the highest among all known layered magnetic materials, to the best of our knowledge. Among all known vdW materials, the mobility of bulk GdTe3 is comparable to that of black phosphorus, and is only surpassed by graphite. By mechanical exfoliation, we further demonstrate that GdTe3 can be exfoliated to ultrathin flakes of three monolayers, and that the magnetic order and relatively high mobility is retained in approximately 20-nm-thin flakes

Effect of Esketamine on Hypotension in Women With Preoperative Anxiety Undergoing Elective Cesarean Section: A Randomized, Double-Blind, Controlled Trial

To investigate the effect of low-doses esketamine on spinal anesthesia-induced hypotension in women with preoperative anxiety undergoing elective cesarean section, the randomized controlled trial enrolled 120 women aged 18-35 years who preoperative State-Trait Anxiety Inventory State scores \u3e 40, conducted from September 2022 to August 2023 in Xuzhou Central Hospital, China. Women in the esketamine group received a single intravenous injection of 0.2 mg/kg esketamine after sensory block level achieved. The incidence of hypotension in the esketamine group was significantly lower than the control group at T2 (10% [6 of 60]; P \u3c 0.001), T3 (5.0% [3 of 60]; P = 0.007) and T4(5.0% [3 of 60]; P = 0.004). Despite being higher in the esketamine group, the overall rates of hypertension (11.7% [7 of 60]; P = 0.186), tachycardia (23.3% [14 of 60]; P = 0.246), and bradycardia (0.0% [0 of 60]; P = 0.079) were no significantly difference between the two groups. STAI-S scores was significantly lower in the esketamine group (mean [SD] 37.52[7.14]) than in the control group (mean [SD] 41.03[9.66], P = 0.39) in postoperative day 1. Spinal anesthesia combined with intravenous low-doses esketamine infusion can significantly reduce the incidence of hypotension in women with preoperative anxiety undergoing elective cesarean section

A Platform for Far-Infrared Spectroscopy of Quantum Materials at Millikelvin Temperatures

Optical spectroscopy of quantum materials at ultralow temperatures is rarely explored, yet it may provide critical characterizations of quantum phases not possible using other approaches. We describe the development of a novel experimental platform that enables optical spectroscopic studies, together with standard electronic transport, of materials at millikelvin temperatures inside a dilution refrigerator. The instrument is capable of measuring both bulk crystals and micron-sized two-dimensional van der Waals materials and devices. We demonstrate the performance by implementing photocurrent-based Fourier transform infrared spectroscopy on a monolayer WTe$_2$ device and a multilayer 1T-TaS$_2$ crystal, with a spectral range available from near-infrared to terahertz range and in magnetic fields up to 5 T. In the far-infrared regime, we achieve spectroscopic measurements at a base temperature as low as ~ 43 mK and a sample electron temperature of ~ 450 mK. Possible experiments and potential future upgrades of this versatile instrumental platform are envisioned.Comment: 13 pages, 6 figures, typos correcte

Surface-Confined Two-Dimensional Crystal Growth on a Monolayer

Conventional vapor deposition or epitaxial growth of two-dimensional (2D) materials and heterostructures is conducted in a large chamber in which masses transport from the source to the substrate. Here we report a chamber-free, on-chip approach for growing a 2D crystalline structures directly in a nanoscale surface-confined 2D space. The method is based on a surprising discovery of a rapid, long-distance, non-Fickian transport of a uniform layer of atomically thin palladium (Pd) on a monolayer crystal of tungsten ditelluride (WTe2), at temperatures well below the known melting points of all materials involved. The resulting nanoconfined growth realizes a controlled formation of a stable new 2D crystalline material, Pd7WTe2 , when the monolayer seed is either free-standing or fully encapsulated in a van der Waals stack. The approach is generalizable and highly compatible with nanodevice fabrication, promising to expand the library of 2D materials and their functionalities

Unconventional Superconducting Quantum Criticality in Monolayer WTe2

The superconductor to insulator or metal transition in two dimensions (2D) provides a valuable platform for studying continuous quantum phase transitions (QPTs) and critical phenomena. Distinct theoretical models, including both fermionic and bosonic localization scenarios, have been developed, but many questions remain unsettled despite decades of research. Extending Nernst experiments down to millikelvin temperatures, we uncover anomalous quantum fluctuations and identify an unconventional superconducting quantum critical point (QCP) in a gate-tuned excitonic quantum spin Hall insulator (QSHI), the monolayer tungsten ditelluride (WTe2). The observed vortex Nernst effect reveals singular superconducting fluctuations in the resistive normal state induced by magnetic fields or temperature, even well above the transition. Near the doping-induced QCP, the Nernst signal driven by quantum fluctuations is exceptionally large in the millikelvin regime, with a coefficient of ~ 4,100 uV/KT at zero magnetic field, an indication of the proliferation of vortices. Surprisingly, the Nernst signal abruptly disappears when the doping falls below the critical value, in striking conflict with conventional expectations. This series of phenomena, which have no prior analogue, call for careful examinations of the mechanism of the QCP, including the possibility of a continuous QPT between two distinct ordered phases in the monolayer. Our experiments open a new avenue for studying unconventional QPTs and quantum critical matter

Evidence for a Monolayer Excitonic Insulator

The interplay between topology and correlations can generate a variety of unusual quantum phases, many of which remain to be explored. Recent advances have identified monolayer WTe2 as a promising material for exploring such interplay in a highly tunable fashion. The ground state of this two-dimensional (2D) crystal can be electrostatically tuned from a quantum spin Hall insulator (QSHI) to a superconductor. However, much remains unknown about the nature of these ground states, including the gap-opening mechanism of the insulating state. Here we report systematic studies of the insulating phase in WTe2 monolayer and uncover evidence supporting that the QSHI is also an excitonic insulator (EI). An EI, arising from the spontaneous formation of electron-hole bound states (excitons), is a largely unexplored quantum phase to date, especially when it is topological. Our experiments on high-quality transport devices reveal the presence of an intrinsic insulating state at the charge neutrality point (CNP) in clean samples. The state exhibits both a strong sensitivity to the electric displacement field and a Hall anomaly that are consistent with the excitonic pairing. We further confirm the correlated nature of this charge-neutral insulator by tunneling spectroscopy. Our results support the existence of an EI phase in the clean limit and rule out alternative scenarios of a band insulator or a localized insulator. These observations lay the foundation for understanding a new class of correlated insulators with nontrivial topology and identify monolayer WTe2 as a promising candidate for exploring quantum phases of ground-state excitons.Comment: 37 pages, 4 Main Figures + 15 SI Figur