Perfect excitation and attenuation-free propagation of graphene surface polaritons under optical admittance matching.

Graphene supports both transverse magnetic and electric modes of surface polaritons due to the intraband and interband transition properties of electrical conductivity. Here, we reveal that perfect excitation and attenuation-free propagation of surface polaritons on graphene can be achieved under the condition of optical admittance matching. With both vanished forward and backward far-field radiation, incident photons are fully coupled to surface polaritons. This requires an exact match between the admittance difference of sandwiching media and the conductivity of graphene, resulting in no decay of propagating surface polaritons. The dispersion relation has a completely different line shape for structures that support compared to those that do not support admittance matching. This work promotes complete comprehension of the excitation and propagation behaviors of graphene surface polaritons and may further inspire ideas for research on surface waves on two-dimensional materials.

Cognitive impairment and factors influencing depression in adolescents with suicidal and self-injury behaviors: a cross-sectional study.

BACKGROUND: Non-suicidal self-injury (NSSI) and suicide attempts (SAs) by adolescent patients with depression have become serious public health problems. There is still insufficient research evidence on the effects of NSSI and SAs on neurocognitive functioning in adolescents. Cognitive function alterations may be associated with SAs and self-injury. NSSI and SAs have different influencing factors. METHODS: Participants were recruited from outpatient clinics and included 142 adolescent patients with depression (12-18 years old). This cohort included the SAs group (n = 52), NSSI group (n = 65), and depression without SAs/NSSI control group (n = 25). All participants underwent a clinical interview and neuropsychological assessment for group comparisons, and post-hoc tests were performed. Finally, partial correlation analysis was used to explore factors related to changes in cognitive function. RESULTS: The SAs group performed significantly worse than the control group in executive function and working memory. The depression score was directly proportional to the executive function of the SAs group, whereas cognitive functioning in the NSSI group was associated with borderline traits and rumination. CONCLUSIONS: These findings suggest that impairment of executive function and working memory may be a common pattern in adolescent depressed patients with SAs. However, borderline traits and rumination may be indicative of NSSI but not SAs.

Visible-Band Chiroptical Meta-devices with Phase-Change Adjusted Optical Chirality.

Low-cost large-area chirality meta-devices (CMDs) with adjustable optical chirality are of great interest for polarization-sensitive imaging, stereoscopic display, enantioselectivity analysis, and catalysis. Currently, CMDs with adjusted chiroptical responses in the mid-infrared to terahertz band have been demonstrated by exploiting photocarriers of silicon, pressure, and phase-change of GSTs but are still absent in the visible band, which in turn limits the development of chiral nanophotonic devices. Herein, by employing a phase-change material (Sb2S3), we present a protocol for the fabrication of wafer-scale visible-band enantiomeric CMDs with handedness, spectral, and polarization adjustability. As measured by circular dichroism, the chirality signs of CMDs enantiomers can be adjusted with Sb2S3 from amorphous to crystalline, and the chirality resonance wavelength can also be adjusted. Our results suggest a new type of meta-devices with adjustable chiroptical responses that may potentially enable a wide range of chirality nanophotonic applications including highly sensitive sensing and surface-enhanced nanospectroscopy.

Enhancing electromagnetic field gradient in tip-enhanced Raman spectroscopy with a perfect radially polarized beam.

Tip-enhanced Raman spectroscopy (TERS) is a promising label-free super-resolving imaging technique, and the electric field gradient of nanofocusing plays a role in TERS performance. In this paper, we theoretically investigated the enhancement and manipulation of the electric field gradient in a bottom-illumination TERS configuration through a tightly focused perfect radially polarized beam (PRPB). Improvement and manipulation in electric field enhancement and field gradient of the gap-plasmon mode between a plasmonic tip and a virtual surface plasmons (SPs) probe are achieved by adjusting the ring radius of the incident PRPB. Our results demonstrate that the method of optimizing the ring radius of PRPB is to make the illumination angle of incident light as close to the surface plasmon resonance (SPR) excitation angle as possible. Under the excitation of optimal parameters, more than 10 folds improvement of field enhancement and 3 times of field gradient of the gap-plasmon mode is realized compared with that of the conventional focused RPB. By this feat, our results indicate that such a method can further enhance the gradient Raman mode in TERS. We envision that the proposed method, to achieve the dynamic manipulation and enhancement of the nanofocusing field and field gradient, can be more broadly used to control light-matter interactions and extend the reach of tip-enhanced spectroscopy.

Sex-Specific Difference in Outcomes after Transcatheter Mitral Valve Repair with MitraClip Implantation: A Systematic Review and Meta-Analysis.

Background: Implantation of the MitraClip is a safe and effective therapy for mitral valve repair in patients ineligible for surgery or at high risk of adverse surgical outcomes. However, only limited information is available concerning sex differences in transcatheter mitral valve repair. We therefore sought to conduct a comprehensive meta-analysis of studies that investigated differences between men and women in outcomes following MitraClip implantation. Methods: The PubMed and Embase databases were searched until November 2019 for studies reporting outcomes after MitraClip implantation in women versus men. Outcomes included all-cause mortality and major complications at 30 days and one year of follow-up. Results: Six studies (n = 1,109 women; n = 1,743 men) were analyzed. At 30 days, women had a similar risk of postoperative complications, such as stroke, major bleeding, and pericardium effusion, without differences in all-cause mortality, procedure success, or MitraClip usage. At one year, the all-cause mortality, the reduction of mitral regurgitation, and the risk of rehospitalization for heart failure were also comparable between male and female patients. Conclusion: Gender disparity was not found in complications or prognosis of patients undergoing MitraClip implantation. This study suggests that gender should not be considered as a critical factor in the selection of patients as candidates for MitraClip implantation of concern during follow-up.

Circular nanocavity substrate-assisted plasmonic tip for its enhancement in nanofocusing and optical trapping.

Plasmonic tip nanofocusing has widely been applied in tip-enhanced Raman spectroscopy, optical trapping, nonlinear optics, and super-resolution imaging due to its capability of high local field enhancement. In this work, a substrate with a circular nanocavity is proposed to enhance the nanofocusing and optical trapping characteristics of the plasmonic tip. Under axial illumination of a tightly focused radial polarized beam, the circular nanohole etched on a metallic substrate can form a nanocavity to induce an interference effect and further enhance the electric field intensity. When a plasmonic tip is placed closely above such a substrate, the electric field intensity of the gap-plasmon mode can further be improved, which is 10 folds stronger than that of the conventional gap-plasmon mode. Further analysis reveals that the enhanced gap-plasmon mode can significantly strengthen the optical force exerted on a nanoparticle and stably trap a 4-nm-diameter dielectric nanoparticle. Our proposed method can improve the performance of tip-enhanced spectroscopy, plasmonic tweezers and extend their applications. We anticipate that our methods allow simultaneously manipulating and characterizing single nanoparticles in-situ.

FABP4 inhibitor BMS309403 protects against hypoxia-induced H9c2 cardiomyocyte apoptosis through attenuating endoplasmic reticulum stress.

Acute myocardial infarction is characterized by ischaemia-induced cardiomyocyte apoptosis, in which the endoplasmic reticulum (ER) stress plays an important role. The fatty acid-binding protein-4 (FABP4) has been implicated in regulating ER stress and apoptosis. Yet, whether FABP4 is involved in modulating cardiomyocyte apoptosis remains unclarified. By applying an in vitro model of hypoxia-induced apoptosis of H9c2 cardiomyocytes, we found that FABP4 expression was elevated upon hypoxia stimulation, which was further demonstrated to be transcriptionally activated by the hypoxia-inducible factor 1a (HIF-1α). In addition, the pharmacological inhibition of FABP4 with BMS309403 protected against hypoxia-induced apoptosis in cardiomyocytes, indicating that FABP4 induction is detrimental for cardiomyocyte survival under hypoxic condition. Moreover, BMS309403 attenuated ER stress in cardiomyocytes exposed to hypoxia, which, however, was reversed by tunicamycin, an ER stress activator. More importantly, the protective effect of BMS309403 on cardiomyocytes vanished in the presence of tunicamycin. Thus, these observations establish that FABP4 inhibitor BMS309403 reduces hypoxia-induced cardiomyocyte apoptosis through attenuating excessive ER stress, implying that FABP4 inhibition may be of clinical benefit for MI treatment.

Plasmon-enhanced linear and second-order surface nonlinear optical response of silver nanoparticles fabricated using a femtosecond pulse.

We present the plasmon-enhanced linear and second-order surface nonlinear optical response of silver nanoparticles (Ag NPs) fabricated using a femtosecond pulse. Theoretical analysis indicates Ag NPs with a diameter of ∼100 nm have excellent linear response within the visible band, and the electric field intensity enhancement factor reaches ∼105 under excitation of continuous light of 632.8 nm. Meanwhile, the simulation result of second-order surface nonlinear optical response shows that the second harmonic conversion efficiency of the Ag NPs dimer is two orders of magnitude higher than that of a single Ag NP, under excitation of a femtosecond pulse. In experiment, the linear response of Ag NPs is examined using surface-enhanced Raman spectroscopy (SERS) with a Raman enhancement factor of ∼1.7 × 1010, revealing the excellent linear optical response of Ag NPs. Moreover, the spectra of the second harmonic can be measured clearly under conditions of an average pump power of 40 µW, revealing the excellent second-order surface nonlinear optical response of Ag NPs.

Near-infrared photodetection with plasmon-induced hot electrons using silicon nanopillar array structure.

A plasmon-induced hot-electron photodetector based on silicon nanopillar array is developed. The nanostructure is fabricated by reactive ion etching with a monolayer of self-assembled polystyrene nanosphere in hexagonal close-packed lattice as the mask. Light absorption and hot-electron generation are mainly enhanced by the surface plasmon polaritons formed at the surface of the gold film on the nanopillar sidewalls. The photoresponse spans two telecom wavebands, viz. the range of 1250-1600 nm, and has a value of 2.5 mA W-1 at 1310 nm. The proposed silicon nanopillar-based hot-electron infrared detector has great potentials for device integration in silicon photonics relying on the economic large-area fabrication process.

Surface-Enhanced Raman Spectroscopy Based on a Silver-Film Semi-Coated Nanosphere Array.

In this paper, we present a convenient and economical method to fabricate a silver (Ag)-film semi-coated polystyrene (PS) nanosphere array substrate for surface-enhanced Raman spectroscopy (SERS). The SERS substrate was fabricated using the modified self-assembled method combined with the vacuum thermal evaporation method. By changing the thickness of the Ag film, the surface morphology of the Ag film coated on the PS nanospheres can be adjusted to obtain the optimized localized surface plasmonic resonance (LSPR) effect. The 3D-finite-difference time-domain simulation results show that the SERS substrate with an Ag film thickness of 10 nm has tens of times the electric field intensity enhancement. The Raman examination results show that the SERS substrate has excellent reliability and sensitivity using rhodamine-6G (R6G) and rhodamine-B (RB) as target analytes, and the Raman sensitivity can reach 10-10 M. Meanwhile, the SERS substrate has excellent uniformity based on the Raman mapping result. The Raman enhancement factor of the SERS substrate was estimated to be 5.1 × 106. This kind of fabrication method for the SERS substrate may be used in some applications of Raman examination.

Aortic Valve Replacement with Bovine Pericardium in Patients with Aortic Valve Regurgitation.

This study aimed to analyze the early and mid-term outcomes of aortic valve replacement with bovine pericardium in the treatment of aortic valve regurgitation.From January 2015 to March 2018, 36 patients (19 men; mean ± standard deviation [SD] age, 46.70 ± 16.60 years) underwent aortic valve replacement with bovine pericardium. The bovine pericardium was intraoperatively measured and shaped using an Ozaki template, according to the shape and size of the individual patient's aortic valve leaflets. Additional procedures were performed, including ventricular septal defect repair in 5 cases, mitral valve reconstruction in 6 cases, tricuspid valve reconstruction in 6 cases, and coronary artery bypass grafting in 3 cases.There were no perioperative deaths. One elderly patient with postoperative respiratory failure recovered after symptomatic treatment. One patient with frequent ventricular tachycardia after intraoperative cardiac re-jump underwent intra-aortic balloon counterpulsation (IABP), and the IABP device was successfully removed on the second postoperative day. Within the first 6 months of follow-up, there were no death events, no reoperation events, and no additional thromboembolic events. Follow-up echocardiography was performed for 6 months, with average left ventricular ejection fraction of 62.01 ± 3.21%, mean transvalvular pressure gradient of 11.17 ± 4.90 mmHg, and mean aortic valve velocity of 1.60 ± 0.58 m/s. Compared with the preoperative transthoracic echocardiography findings, the results at the six-month follow-up were statistically significant (P < 0.05). Mild aortic valve regurgitation occurred in 2 patients (5.56%), whereas other patients had no or only minimal aortic valve regurgitation (n = 34, 94.44%). Moderate aortic valve regurgitation occurred in one patient at 9 months after the initial operation. This was found to be due to infective endocarditis, and a biological valve was finally implanted.Aortic valve replacement with bovine pericardium in the treatment of aortic valve regurgitation is feasible, and good early and mid-term results are achieved. Long-term results need to be followed up in the future.

Surface-enhanced Raman spectroscopy with Au-nanoparticle substrate fabricated by using femtosecond pulse.

Au-nanoparticle (Au-NP) substrates for surface-enhanced Raman spectroscopy (SERS) were fabricated by grid-like scanning a Au-film using a femtosecond pulse. The Au-NPs were directly deposited on the Au-film surface due to the scanning process. The experimentally obtained Au-NPs presented local surface plasmon resonance effect in the visible spectral range, as verified by finite difference time domain simulations and measured reflection spectrum. The SERS experiment using the Au-NP substrates exhibited high activity and excellent substrate reproducibility and stability, and a clearly present Raman spectra of target analytes, e.g. Rhodamine-6G, Rhodamine-B and Malachite green, with concentrations down to 10-9 M. This work presents an effective approach to producing Au-NP SERS substrates with advantages in activity, reproducibility and stability, which could be used in a wide variety of practical applications for trace amount detection.

Tip-Enhanced Raman Spectroscopy with High-Order Fiber Vector Beam Excitation.

We investigated tip-enhanced Raman spectra excited by high-order fiber vector beams. Theoretical analysis shows that the high-order fiber vector beams have stronger longitudinal electric field components than linearly polarized light under tight focusing conditions. By introducing the high-order fiber vector beams and the linearly polarized beam from a fiber vector beam generator based on an electrically-controlled acoustically-induced fiber grating into a top-illumination tip-enhanced Raman spectroscopy (TERS) setup, the tip-enhanced Raman signal produced by the high-order fiber vector beams was 1.6 times as strong as that produced by the linearly polarized light. This result suggests a new type of efficient excitation light beams for TERS.

Impact of atrial fibrillation on outcomes of patients treated by transcatheter mitral valve repair: A systematic review and meta-analysis.

BACKGROUND: Conflicting data have been reported related to the impact of atrial fibrillation (AF) on outcomes after transcatheter mitral valve repair with MitraClip (MC) implantation. In this study, we assessed the prognosis of MC-treated patients according to the presence of pre-existing AF. METHODS: Randomized and observational studies reporting outcomes of pre-existing AF or sinus rhythm in patients undergoing MC treatment were identified with an electronic search. Outcomes of interest were short-and long-term mortality, stroke, bleeding, rehospitalization, myocardial infarction (MI), cardiogenic shock, acute procedure success, the hospital stay, and the number of Clips implanted. RESULTS: Eight studies (8466 individuals) were eligible. Compared to sinus rhythm, long-term mortality, the risk of bleeding, rehospitalization, and longer hospital stay were significantly higher in AF groups, whereas similar correlations were found in the analysis of other outcomes. CONCLUSION: AF may be related with worse outcomes in patients undergoing MC implantation, including long-term mortality, major bleeding, and rehospitalization. AF should be taken into account when referring a patient for MC treatment.

Optical trapping of single nano-size particles using a plasmonic nanocavity.

Trapping and manipulating micro-size particles using optical tweezers has contributed to many breakthroughs in biology, materials science, and colloidal physics. However, it remains challenging to extend this technique to a few nanometers particles owing to the diffraction limit and the considerable Brownian motion of trapped nanoparticles. In this work, a nanometric optical tweezer is proposed by using a plasmonic nanocavity composed of the closely spaced silver coated fiber tip and gold film. It is found that the radial vector mode can produce a nano-sized near field with the electric-field intensity enhancement factor over 103 through exciting the plasmon gap mode in the nanocavity. By employing the Maxwell stress tensor formalism, we theoretically demonstrate that this nano-sized near field results in a sharp quasi-harmonic potential well, capable of stably trapping 2 nm quantum dots beneath the tip apex with the laser power as low as 3.7 mW. Further analysis reveals that our nanotweezers can stably work in a wide range of particle-to-tip distances, gap sizes, and operation wavelengths. We envision that our proposed nanometric optical tweezers could be compatible with the tip-enhanced Raman spectroscopy to allow simultaneously manipulating and characterizing single nanoparticles as well as nanoparticle interactions with high sensitivity.

Plasmon-enhanced nonlinear nanofocusing of gold nanoprisms driven via an ultrafast azimuthal vector beam.

We present the plasmon-enhanced nonlinear nanofocusing of a gold (Au) nanoprism array substrate (ANAS) driven via an ultrafast azimuthal vector beam (AVB). Theoretical calculations show that the electric-field intensity of the ANAS vertically excited via the femtosecond AVB is higher than that of LPB excitation. In this experiment, the second-order surface nonlinear optical response of the ANAS is adopted to examine the nonlinear plasmonic nanofocusing of the ANAS, and it was observed that the second harmonic (SH) intensity of the ANAS excited via the femtosecond AVB is ∼3.8 times higher than that of LPB excitation, revealing that the ANAS under AVB excitation has a better nonlinear plasmonic nanofocusing characteristic than that under LPB excitation. Furthermore, the GaSe nanosheets are transferred on the ANAS to examine the nonlinear plasmonic nanofocusing of the ANAS. The SH intensity of the GaSe nanosheets deposited on the ANAS via the femtosecond AVB excitation has been enhanced ∼4.7 times than that of LPB excitation, indicating that the ANAS via AVB excitation has better nonlinear plasmonic nanofocusing than that of LPB excitation. This method may be used as a nonlinear nanofocusing light source to increase the light-matter nonlinear interaction.

Laparoscopic omental flap for the treatment of thoracic aortic graft infection: report of two cases and review of the literature.

BACKGROUND: Thoracic aortic graft infection (TAGI) is a rare and serious complication after surgery for which the treatment is controversial and challenging. Rather than following the traditional surgical strategy of graft replacement and extensive debridement, we have chosen to preserve the graft and cover it by a laparoscopic omental flap. In this article, we describe the clinical manifestation, diagnostic modalities, and treatment of this disease and analyze the role of laparoscopic omental flaps in its treatment. CASE PRESENTATION: We present two cases of thoracic aortic graft infections that had undergone surgical graft replacement for acute Stanford type A dissection. Their clinical manifestation of infection was atypical, with computed tomography suggesting infection of the grafts. Both patients were successfully treated with debridement, laparoscopic omental transposition, and antibiotics. The first case, a 55-year-old male, was found to have an infection at the aortic arch. The second case is a 52-year-old male who was found to have infection at the ascending aorta and arch. Surprisingly, both intraoperative cultures were negative. The infections were brought under control and the patients recovered steadily after surgery. Early follow-up results showed no signs of graft infection. CONCLUSION: These findings suggest that graft replacement for the treatment of TAGI is not always necessary in selected patients. Conservative surgical treatment, including laparoscopic omental transposition, is effective and less invasive for treating TAGI.