Polarization-stable single-mode 795†nm grating-coupled surface-emitting laser for quantum sensing.

We demonstrate a polarization-stable and single-mode grating-coupled surface-emitting laser (GCSEL) with high side-mode suppression ratio (SMSR) of ∼40 dB and orthogonal polarization suppression ratio (OPSR) of ∼25 dB around 795 nm. The fabricated devices have low threshold current of ∼4.8 mA and low electrical resistance of 53 Ω at 25 °C. Meanwhile, a low thermal resistance of ∼1 K/mW is achieved, which is comparable with that of the record of ever reported for vertical-cavity surface-emitting lasers (VCSELs). The far-field divergence angle of surface-emitting beam is ∼14.5°x14.7° at an injection current of 12 mA indicating a relatively good beam quality. Our results open what we believe is a new way to produce polarization-stable single-mode surface-emitting lasers with simple fabrication process. While the GCSEL is specifically designed for quantum sensing applications such as atomic clocks, magnetometers, and gyroscope, its performance in terms of low-power consumption, low thermal resistance, good beam qualities, and wafer-level testing are of particular interest for a wide range of applications.

Chiral graphene plasmonic Archimedes' spiral nanostructure with tunable circular dichroism and enhanced sensing performance.

Circular dichroism spectroscopy is frequently used to characterize the chiral biomolecules by measuring the absorption spectra contrast between the left-handed circularly polarized light and the right-handed circularly polarized light. Compared with biomolecules, chiral metal plasmonic nanostructures also produce a strong circular dichroism response in the range of near-infrared. However, due to the large damping rate, the non-adjustable resonant frequency of the conventional metals, the applications of chiral metal plasmonic nanostructures in the fields of photoelectric detection and chemical and biochemical sensing are restricted. Here, we present a chiral graphene plasmonic Archimedes' spiral nanostructure that displays a significant circular dichroism response under the excitation of two polarizations of circularly polarized light. By manipulating the material and geometric parameters of the Archimedes' spiral, the stronger circular dichroism responses and modulation of the resonant wavelength are achieved. The optimized plasmonic nanostructure has outstanding refractive index sensing performance, where the sensitivity and figure of merit reach 7000nm/RIU and 68.75, respectively. Our proposed chiral graphene plasmonic Archimedes' spiral nanostructure might find potential applications in the fields of optical detection and high performance of index sensing.

"Fast" Plasmons Propagating in Graphene Plasmonic Waveguides with Negative Index Metamaterial Claddings.

We propose the monolayer graphene plasmonic waveguide (MGPW), which is composed of graphene core sandwiched by two graphene metamaterial (GMM) claddings and investigate the properties of plasmonic modes propagating in the waveguide. The effective refraction index of the GMMs claddings takes negative (or positive) at the vicinity of the Dirac-like point in the band structure. We show that when the effective refraction index of the GMMs is positive, the plasmons travel forward in the MGPW with a positive group velocity (vg > 0, vp > 0). In contrast-for the negative refraction index GMM claddings-a negative group velocity of the fundamental mode (vg < 0, vp > 0) appears in the proposed waveguide structure when the core is sufficiently narrow. A forbidden band appears between the negative and positive group velocity regions, which is enhanced gradually as the width of the core increases. On the other hand, one can overcome this limitation and even make the forbidden band disappear by increasing the chemical potential difference between the nanodisks and the ambient graphene of the GMM claddings. The proposed structure offers a novel scheme of on-chip electromagnetic field and may find significant applications in the future high density plasmonic integrated circuit technique.

Spinal cord injury and its underlying mechanism in rats with temporal lobe epilepsy.

Numerous cases of spinal cord injury following seizure have been previously reported. However, whether spinal cord injury is a common occurrence after seizures and its underlying mechanisms remain unclear. The present study generated a Sprague-Dawley rat model of temporal lobe epilepsy (TLE), and Nissl staining and transmission electron microscopy were used to detect tissue damage. In addition, Evans blue staining was used to detect damage to the blood-brain barrier (BBB) and albumin extravasation. In addition, double-staining was used to detect the association between neurons and extravasated albumin. Furthermore, neuronal degeneration was assessed using Fluoro-Jade C staining, while fluorescence staining and western blotting were used to detect apoptosis and inflammation. In the present study, spinal cord injury was only observed in rats with grade IV-V seizures, whereas Nissl staining showed structural damage and decreased neuronal cell numbers in the brain and the spinal cord. The present study identified BBB damage and albumin extravasation in rats of the TLE groups. Double-staining for albumin and neurons showed a significant match of neurons positive for albumin. Fluoro-Jade C staining indicated neuronal degeneration in the brain, but not the spinal cord in the TLE rats. High levels of caspase-3 were also detected in the injured spinal cord. A small number of albumin+ neurons in the spinal cord presented caspase-3+ signals in rats of the TLE groups. The expression levels of intercellular adhesion molecule 1, CD11b and inflammatory factors such as tumor necrosis factor-α and interleukin-6 were significantly elevated in the injured spinal cord. The present results suggested that spinal cord injury occurred in rats as a result of severe seizure attacks, and that BBB damage, albumin extravasation, inflammation and apoptosis contributed to the pathological changes observed during spinal cord injury.

Multiple Fano Resonances with Tunable Electromagnetic Properties in Graphene Plasmonic Metamolecules.

Multiple Fano resonances (FRs) can be produced by destroying the symmetry of structure or adding additional nanoparticles without changing the spatial symmetry, which has been proved in noble metal structures. However, due to the disadvantages of low modulation depth, large damping rate, and broadband spectral responses, many resonance applications are limited. In this research paper, we propose a graphene plasmonic metamolecule (PMM) by adding an additional 12 nanodiscs around a graphene heptamer, where two Fano resonance modes with different wavelengths are observed in the extinction spectrum. The competition between the two FRs as well as the modulation depth of each FR is investigated by varying the materials and the geometrical parameters of the nanostructure. A simple trimer model, which emulates the radical distribution of the PMM, is employed to understand the electromagnetic field behaviors during the variation of the parameters. Our proposed graphene nanostructures might find significant applications in the fields of single molecule detection, chemical or biochemical sensing, and nanoantenna.

Differences in the regeneration traits of Potamogeton crispus turions from macrophyte- and phytoplankton-dominated lakes.

Potamogeton crispus is widely used in submerged macrophyte restoration in China. Turions are an important means of reproduction in this species. To compare the regeneration abilities of P. crispus turions in macrophyte- and phytoplankton-dominated lakes, we collected P. crispus turions from a macrophyte-dominated lake (Liangzi Lake) and a phytoplankton-dominated lake (Taihu Lake). Both lakes are important lakes in the middle and lower reaches of the Yangtze River in China. Our field survey revealed that the turions from the phytoplankton-dominated lake had smaller sizes and higher concentrations of total nitrogen (TN) and total phosphorus (TP) than did those from the macrophyte-dominated lake. Rapid sprouting of the turions from the phytoplankton-dominated lake in 32 days was observed under experimental conditions, although the sprout sizes (heights and biomass) were smaller than those from the macrophyte-dominated lake. Compared with sprouted turions from macrophyte-dominated lake, the sprouted turions from the phytoplankton-dominated lake accumulated higher soluble sugar (SS) but lower starch and free amino acid (FAA) concentrations. A 12-day interval sprout removal treatment significantly stimulated the re-sprouting of turions from both lakes, but scale-leaf-removal treatments had no effect. This study provides evidence that the regeneration strategies of P. crispus turions differ in macrophyte- and phytoplankton-dominated lakes.

[Effects of mild hypothemia on hemodynamics of systemic and renal of dog with septic shock].

OBJECTIVES: To explore the effects of mild hypothemia on hemodynamics of systemic and renal of dog with septic shock. METHODS: 40 healthy dogs were randomly and evenly divided into the normal temperature non-infected group (NTNS), normal temperature infected group (NTS), hypothermia non-infected group (MHNS) and hypothermia infected group (MHS). NTS and MHS were pumped through the femoral vein of Escherichia coli (E.coli 1 × 109 cfu/ml) by 0.5 ml·kg⁻¹·h⁻¹, producting septic shock model with high-power cycle. Combining with blood pump devices and low temperature thermostat bath, the MHNS and MHS implemented extracorporeal blood cooling method to maintain the blood in temperature (33 ± 1) °C. 0, 24, 48, 72 h point, tested specimens from femoral vein for renal function. In the 0-72 h. Pulse indicates the continuous cardiac output monitor (PiCCO) monitored systemic hemodynamics on each time point. In the 0-72 h, color Doppler ultrasound (CDFI) measured renal hemodynamic on each time point. RESULTS: There was an increase of SBP (P<0.05), SVR [(2 415 ± 651) dyn·s·cm⁻5 vs (1 613 ± 223) dyn·s·cm⁻5, P=0.01] and RI (P=0.04) in the MHS group comparing with the NTS group from 24 to 72 h. CO [(3.58 ± 0.44) L/min vs (4.18 ± 0.60) L/min, P=0.04], HR and PSV was decreased in the MHS group. BUN [(8.6 ± 1.6) mmol/L vs (21.2 ± 4.8) mmol/L, P<0.01] and Scr [(167.6 ± 31.2) µmol/L vs (383.8 ± 35.2) µmol/L, P<0.01] was decreased in MHS group comparing with the NTS group. There was a positively correlation between CO and PSV in the canine model of septic shock (P<0.01); and CO was negatively correlated with RI (P<0.01). CONCLUSIONS: In this canine model of septic shock, hypothermia can stable systemic and renal hemodynamics, and improve kidney function.

Estimation of leaf area index and plant area index of a submerged macrophyte canopy using digital photography.

Non-destructive estimation using digital cameras is a common approach for estimating leaf area index (LAI) of terrestrial vegetation. However, no attempt has been made so far to develop non-destructive approaches to LAI estimation for aquatic vegetation. Using the submerged plant species Potamogeton malainus, the objective of this study was to determine whether the gap fraction derived from vertical photographs could be used to estimate LAI of aquatic vegetation. Our results suggested that upward-oriented photographs taken from beneath the water surface were more suitable for distinguishing vegetation from other objects than were downward-oriented photographs taken from above the water surface. Exposure settings had a substantial influence on the identification of vegetation in upward-oriented photographs. Automatic exposure performed nearly as well as the optimal trial exposure, making it a good choice for operational convenience. Similar to terrestrial vegetation, our results suggested that photographs taken for the purpose of distinguishing gap fraction in aquatic vegetation should be taken under diffuse light conditions. Significant logarithmic relationships were observed between the vertical gap fraction derived from upward-oriented photographs and plant area index (PAI) and LAI derived from destructive harvesting. The model we developed to depict the relationship between PAI and gap fraction was similar to the modified theoretical Poisson model, with coefficients of 1.82 and 1.90 for our model and the theoretical model, respectively. This suggests that vertical upward-oriented photographs taken from below the water surface are a feasible alternative to destructive harvesting for estimating PAI and LAI for the submerged aquatic plant Potamogeton malainus.