Abstract Optoelectronic sampling is the ultimate method to perform ultra‐high frequency analog‐to‐digital conversion. Thanks to the ps photo‐thermo‐bolometric effect in high mobility hexagonal boron nitride (h‐BN) encapsulated graphene, a state‐of‐the‐art optoelectronic sampler over a 40 GHz bandwidth using a 4 ps pulsed laser is demonstrated. The superior transport and optoelectronic linearities of this graphene sampler lead to very high harmonic rejections below –43 dB above 20 GHz. With a physics‐based microscopic model, it is shown that harmonics are generated by optoelectronics saturation effects and only appear when carrier energy reaches that of optical phonons, which is very high in h‐BN encapsulated graphene. This device is the first ultra‐fast optoelectronic sampler based on the bolometric effect.

Understanding the phase transition mechanisms in two-dimensional (2D) materials is a key to precisely tailor their properties at the nanoscale. Molybdenum ditelluride (MoTe₂) exhibits multiple phases at room temperature, making it a promising candidate for phase-change applications. Here, we fabricate lateral 2<i>H</i>-<i>T</i>_d interfaces with laser irradiation and probe their phase transitions from micro- to atomic scales with <i>in situ</i> heating in the transmission electron microscope (TEM). By encapsulating the MoTe₂ with graphene protection layers, we create an <i>in situ</i> reaction cell compatible with atomic resolution imaging. We find that the <i>T</i>_d-to-<i>2H</i> phase transition initiates at phase boundaries at low temperatures (200-225 °C) and propagates anisotropically along the <i>b</i>-axis in a layer-by-layer fashion. We also demonstrate a fully reversible <i>2H</i>-<i>T</i>_d-<i>2H</i> phase transition cycle, which generates a coherent <i>2H</i> lattice containing inversion domain boundaries. Our results provide insights on fabricating 2D heterophase devices with atomically sharp and coherent interfaces.

We report on a detailed investigation of the shell-filling sequence in electrostatically defined elliptic bilayer graphene quantum dots (QDs) in the regime of low charge carrier occupation, $N\ensuremath{\le}12$, by means of magnetotransport spectroscopy and numerical calculations. We show the necessity of including both short-range electron-electron interaction and wave-function-dependent valley $g$-factors for understanding the overall fourfold shell-filling sequence. These factors lead to an additional energy splitting at half filling of each orbital state and different energy shifts in out-of-plane magnetic fields. Analysis of 31 different bilayer graphene (BLG) QDs reveals that both valley $g$-factor and electron-electron interaction-induced energy splitting increase with decreasing QD size, validating theory. However, we find that the electrostatic charging energy of such gate-defined QDs does not correlate consistently with their size, indicating complex electrostatics. These findings offer significant insights for future BLG QD devices and circuit designs.

Interest in ZrTe₅ has been reinvigorated in recent years owing to its potential for hosting versatile topological electronic states and intriguing experimental discoveries. However, the mechanism of many of its unusual transport behaviors remains controversial: for example, the characteristic peak in the temperature-dependent resistivity and the anomalous Hall effect. Here, through employing a clean dry-transfer fabrication method in an inert environment, we successfully obtain high-quality ZrTe₅ thin devices that exhibit clear dual-gate tunability and ambipolar field effects. Such devices allow us to systematically study the resistance peak as well as the Hall effect at various doping densities and temperatures, revealing the contribution from electron-hole asymmetry and multiple-carrier transport. By comparing with theoretical calculations, we suggest a simplified semiclassical two-band model to explain the experimental observations. Our work helps to resolve the longstanding puzzles on ZrTe₅ and could potentially pave the way for realizing novel topological states in the two-dimensional limit.

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Summary: Background: New blood vessel development can be induced by supplementation with angiogenic growth factors. In some older diabetic or hypercholesterolaemic patients, however, endothelial cells are defective and cannot support angiogenesis. Methods: Endothelial progenitor cells (EPC) can help to overcome this limitation, providing a source of viable endothelial cells. Results: It has been demonstrated that EPC can improve neovascularization in ischaemic hind limb, accelerate blood flow in diabetic mice, and improve cardiac function. Conclusions: In this review, we will summarize the effects of EPC in the treatment for experimental peripheral ischaemia. Zusammenfassung: Grundlagen: Die Entwicklung neuer Blutgefäße kann durch die Gabe von angiogenetischen Wachstumsfaktoren induziert werden. Bei älteren Zuckerkranken oder Hypercholesterinämie-Patienten sind die Endothelzellen geschädigt und können die Angiogenese nicht unterstützen. Methodik: Mit Hilfe der endothelialen Progenitorzellen (EPC) können funktionsfähige Endothelzellen gebildet werden. Ergebnisse: Es konnte gezeigt werden, daß die EPC zu einer Neovaskularisation in ischämischen Extremitäten führt, den Blutfluß bei diabetischen Mäusen und die Herzfunktion verbessert. Schlußfolgerungen: In diesem Review diskutieren wir die Effekte der EPC bei der Behandlung experimenteller peripherer Ischämien.

Two-dimensional (2D) semiconductors have attracted considerable interest for their unique physical properties. Here, we report the intrinsic cryogenic electronic transport properties in few-layer MoSe 2 field-effect transistors (FETs) that are fully encapsulated in ultraclean hexagonal boron nitride dielectrics and are simultaneously van der Waals contacted with gold electrodes. The FETs exhibit electronically favorable channel/dielectric interfaces with low densities of interfacial traps (&lt; 10 10 cm −2 ), which lead to outstanding device characteristics at room temperature, including near-Boltzmann-limit subthreshold swings (65 mV/dec), high carrier mobilities (53–68 cm 2 ⋅V −1 ⋅s −1 ), and negligible scanning hystereses (&lt; 15 mV). The dependence of various contact-related parameters with temperature and carrier density is also systematically characterized to understand the van der Waals contacts between gold and MoSe 2 . The results provide insightful information about the device physics in van der Waals contacted and encapsulated 2D FETs.

Drotrecogin alfa has a cost-effectiveness profile similar to that of many well-accepted healthcare strategies and below commonly quoted thresholds.

Editorial

Hypoxia, cytokines, and nitric oxide (NO) stimulate the generation of vascular endothelial growth factor (VEGF) and induce heme oxygenase-1 (HO-1) expression in vascular tissue. HO-1 degrades heme to carbon monoxide (CO), iron, and biliverdin, the latter being reduced to bilirubin by biliverdin reductase. In the present study, we investigated the role of HO-1 in the modulation of VEGF synthesis in rat vascular smooth muscle cells (VSMC). In VSMC stimulated with cytokines, inhibition of NO production significantly, but not completely, reduced VEGF release. In contrast, inhibition of HO activity by tin protoporphyrin IX (SnPPIX) totally prevented cytokine-induced increase in VEGF, despite an augmented synthesis of intracellular NO. Stimulation of HO-1 activity by hemin enhanced VEGF production; this effect was abrogated by blockade of the HO pathway. Similarly, VEGF synthesis induced by hypoxia was down-regulated by SnPPIX, but not by inhibitors of NO synthase. To elucidate further a direct involvement of HO-1 in the observed effects, we generated transfected cells that overexpressed the HO-1 gene. Notably, these cells synthesized significantly more VEGF protein than cells transfected with a control gene. Among the products of HO-1, biliverdin and bilirubin showed no effect, whereas iron ions inhibited VEGF synthesis. Exposure of cells to 1% CO resulted in a marked accumulation of VEGF (20-fold increase) over the basal level. Our data indicate that HO-1 activity influences the generation of VEGF in VSMC in both normoxic and hypoxic conditions. As CO and iron, respectively the inducer and the inhibitor of VEGF synthesis, are concomitantly produced during the degradation of heme, these data indicate that HO by-products may differentially modulate VEGF production.

The growing field of quantum information technology requires propagation of information over long distances with efficient readout mechanisms. Excitonic quantum fluids have emerged as a powerful platform for this task due to their straightforward electro-optical conversion. In two-dimensional transition metal dichalcogenides, the coupling between spin and valley provides exciting opportunities for harnessing, manipulating, and storing bits of information. However, the large inhomogeneity of single layers cannot be overcome by the properties of bright excitons, hindering spin-valley transport. Nonetheless, the rich band structure supports dark excitonic states with strong binding energy and longer lifetime, ideally suited for long-range transport. Here we show that dark excitons can diffuse over several micrometers and prove that this repulsion-driven propagation is robust across non-uniform samples. The long-range propagation of dark states with an optical readout mediated by chiral phonons provides a new concept of excitonic devices for applications in both classical and quantum information technology.