which can manipulate electromagnetic (EM) waves in unconventional ways, and have enabled many exotic physical phenomena and effects, also inspiring novel devices and engineering applications. [1] Their 2D versions, commonly referred to as metasurfaces, are experiencing a strong surge of interest owing to a number of attractive features, including ultrathin thickness, low loss, easy fabrication, and potential conformability. In the wake of the pioneering work by Yu et al. [2] on generalized Snell's laws enabled by imparting an abrupt phase shift, metasurfaces have demonstrated unprecedented capabilities in wavefront engineering, amplitude modulation, and polarization conversion, just to mention a few. [2][3][4][5][6] However, metasurfaces that only impart space-gradient phase discontinuities are inherently constrained by Lorentz reciprocity. This implies, for instance, that the time-reversed version of a reflected wave propagates along the same direction as the original incident wave at the same frequency.The quest for breaking reciprocity is of longstanding interest in EM engineering, and is currently eliciting renewed attention in view of its pivotal role in lifting some fundamental limitations in communication systems as well as energy harvesting and heat management. [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] For instance, in wireless communication systems, a nonreciprocal antenna could radiate a very directive beam without being bound to receiving its reflected echo. [20] A common way to attain nonreciprocal effects, especially at microwave frequencies, is to break the time-reversal symmetry by means of biased magnetic materials (e.g., ferrites). These, however, are typically bulky, costly, and difficult to integrate and scale up to optical wavelengths, [10] which motivates the strong interest in magnetless approaches. Some of these are based on nonlinear materials, which are not bound by the reciprocity theorem, but are power-dependent and require sufficiently high signal intensity. [11,12] Other magnetless approaches rely on transistor-based devices [13] and moving media, [14,15] but are limited in terms of operating frequency, and are difficult to extend to the optical regime. Timevarying approaches have emerged as attractive alternatives based on time-modulated devices, [16][17][18][19][20][21][22][23][24] which have smaller size, lower cost, and better integrability. In 2015, Shaltout et al. [19] Metasurfaces are artificially engineered ultrathin structures that can finely tailor and control electromagnetic wavefronts. There is currently a strong interest in exploring their capability to lift some fundamental limitations dictated by Lorentz reciprocity, which have strong implications in communication, heat management, and energy harvesting. Time-varying approaches have emerged as attractive alternatives to conventional schemes relying on magnetic or nonlinear materials, but experimental evidence is currently limited to devices such as circulators and antennas. Here, the recently...

Photoemission electron microscopy (PEEM) excited by X‐ray and UV sources is used to investigate epitaxial anatase thin films with embedded rutile nanocrystals, a model system for the study of heterocatalysis on mixed‐phase TiO2. Both excitation sources show distinct contrast between the two TiO2 phases; however, the contrast is reversed. Rutile nanocrystals appear darker than the anatase film in X‐ray PEEM images but brighter in UV‐PEEM images. We observe that topography‐induced contrast is dominant in X‐ray PEEM imaging, whereas work function and density‐of‐state‐based contrast, dominates in UV‐PEEM. This assertion is confirmed by UPS and conducting AFM data that shows the rutile work function to be 0.2 eV lower and a greater occupied valence band density‐of‐states in rutile (100) than in anatase (001). Since the boundaries between rutile nanocrystals and the anatase film are clearly resolved, these results indicate that PEEM studies of excited state dynamics and heterocatalysis are possible at chemically intriguing mixed‐phase TiO2 interfaces and grain boundaries.

of the device: the cell is assembled in a way that allows a gradient of the dopant concentration. Consequently, a smooth variation of the helical pitch was obtained inside the same cell. The main aspect of this second method is that a simple translation of the cell with respect to the exciting beam enables the fine-tuning of the laser wavelength. In both methods, a shift of the lasing wavelength by 30±40 nm was obtained. ExperimentalInvestigations on photoexcitation were performed using the third harmonic of a Q-switched Nd:YAG laser (Continuum, Surelite II) as the source. The pulse wavelength, width, and repetition rate were 355 nm, 6 ns, and 5±10 Hz, respectively. The excitation beam energy was strongly attenuated, combining a k/2 waveplate, a polarizer, and several neutral density filters. The laser beam was focused using a cylindrical lens (f = 150 mm) to reduce the spot size on the cell to a few hundred micrometers. The pump beam irradiated the sample at an angle of 45 with respect to the cell normal, the usual experimental geometry for this kind of experiment [8,13]. An optical fiber coupled to the spectrometer (an Avantes Fiberoptics mod. AVS-S2000, with a resolution of 1.5 nm) collected the light emitted from the sample.

BackgroundSeptic shock is a major healthcare problem with a high mortality rate that might be caused by immunosuppression. Programmed cell death receptor-1 (PD-1) and programmed cell death receptor ligand-1 (PD-L1), which are co-inhibitory receptor molecules, participate in sepsis-induced immunosuppression. In this study, we investigated which PD-1-related molecules can be used to evaluate the risk stratification and prognosis of septic patients. Furthermore, we explored the prognostic significance of a combination of ideal predictors and conventional clinical risk parameters in septic shock patients.MethodsIn total, 29 healthy controls, 59 septic patients, and 76 septic shock patients were enrolled in this study. Considering that the focus of the research was on the second phase of sepsis, blood samples were obtained at days 3–4 after the onset of systemic inflammatory response syndrome (SIRS). PD-1 and PD-L1 expression were measured on circulating CD4+ T cells, CD8+ T cells, and monocytes (PD-L1 only) by flow cytometry.ResultsOur results showed that only monocyte PD-L1 expression gradually increased, based on the increasing severity of disease (P < 0.001). Similarly, multivariate logistic regression analysis showed that only monocyte PD-L1 expression was an independent predictor of 28-day mortality in septic shock patients. Area under the receiver operating characteristic curve analysis of the combination of monocyte PD-L1 expression and conventional clinical risk parameters indicated a more significant prognostic ability than analysis of each parameter alone.ConclusionOur study demonstrated that, among PD-1-related molecules, only monocyte PD-L1 expression after 3–4 days of sepsis was associated with risk stratification and mortality in septic patients. Furthermore, measurement of monocyte PD-L1 expression was a promising independent prognostic marker for septic shock patients.

A current detection scanning probe technique is developed that quantifies frequency-dependent local transport properties. The approach, referred to as nanoimpedance microscopy/spectroscopy (NIM), is based on impedance spectroscopy with a conductive atomic force microscopy (AFM) tip. NIM is applied to study the quality of a tip/surface contact and transport behavior of individual grains and grain boundaries in polycrystalline ZnO. Impedance spectra were measured in the frequency range 40 Hz to 110 MHz, and the grain boundary properties are studied by nonlinear fitting of experimental data to an equivalent circuit. Two-terminal measurements are performed in the vicinity of a single ZnO grain boundary and the Cole–Cole plot indicates two major relaxation processes attributed to grain boundary relaxation and tip/surface contact.