Localized vibrational characteristics of biphenylene strips resulting in length-dependent Raman spectra.

The length dependence of the Raman spectra and vibrational properties of biphenylene strips are explored using density functional theory. The Raman intensity of two bands increases and decreases with length due to the enlarging and shrinking of the proportion of effective vibrating units. The red shift of vibrational modes is observed with the increase in length, owing to the various vibrational characteristics of the effective vibrating units. More importantly, a linear relationship between the energy gap and the wavenumber of the shifting Raman bands is obtained. The results allow us to interpret the length-dependence of the Raman spectra from the perspective of localized vibrational characteristics and suggest that Raman spectroscopy can be used as a convenient method to determine the energy gap of nanomaterials.

Size-tunable energy gaps of hydrogen-terminated biphenylene segments.

The electronic properties of hydrogen-terminated biphenylene (BP) segments of different sizes on the sub-nanoscale are explored using density functional theory, and the size dependence of the energy gap is evaluated using a structural parameter as a function of the bond lengths and the electronic density contributions. More importantly, the energy gap is observed to decrease linearly with the reduced hydrogen-to-carbon ratio of the corresponding structures, while the decrease-rate undergoes a diminution of four times at a gap of 0.5 eV due to the transformed distribution of the lowest unoccupied molecular orbital. The results give a deep insight into the size-tunable energy gaps of BPs and provide a possibility for the preparation of hydrogen-terminated carbon materials with a desirable energy gap.

Selective Raman Enhancement with Electronic Sensitivity in Tip-Enhanced Raman Spectroscopy.

Chemical interaction between the tips and molecules is one of the main contributing mechanisms to tip-enhanced Raman spectroscopy (TERS). In this work, we calculate the TERS spectra of the biphenylene (BP) dimer at 13 nonequivalent tip sites by means of density functional theory and explore the influence of the TERS tip on vibrational mode characters and Raman intensity. The Raman intensity of the vibrational mode involving the antisymmetric stretching of tetra-rings is found to be specifically enhanced. We attribute this specific enhancement to the electronic sensitive atom vibrational character of the mode and infer that the vibrational strength of atoms can be tuned by the TERS tip. The results provide an intuitive interpretation on the effects of tip-induced electronic redistributions on specific vibrational modes in TERS and indicate the possibility to further improve the TERS resolution.

Prosthetic Reconstruction of Superior Vena Cava System for Thymic Tumor: A Retrospective Analysis of 22 Cases.

OBJECTIVE: This study aimed to report our experience in superior vena cava (SVC) resection and reconstruction for 22 thymic tumor patients and to make comparisons with previous related reports. METHODS: A retrospective study on 22 patients (15 thymomas, 7 thymic cancers) who underwent tumor resection with concomitant SVC reconstruction. All the patients underwent vascular conduit reconstruction by the cross-clamping technique. The corresponding data were reviewed, including clinical presentation, operation management (surgery procedure, selection of suitable graft, strategies against SVC syndrome, etc.), postoperative cares (antithrombotic agent application, treatments on brain edema, etc.), and follow-up information. RESULT: Two patients were myasthenic, well controlled by oral pyridostigmine. All resections were radical (R0). Ten patients received induction treatment. All the 15 thymoma patients were Masaoka stage III (type B1-B3). As for thymic cancer, six patients were Masaoka stage III and one was stage IVa. Wedge pulmonary resection was performed in three patients (two right upper lobe, one both upper lobe). Procedures included were single graft replacement in 12 patients, bilateral grafts in 9, and Y-shaped graft in 1 patient. Anticoagulation and dehydration agents were routinely applied after operation. No perioperative mortalities were observed. Major complication rate was 9.1%. The median survival time was 44.2 months (range, 4-92 months). Three- and 5-year overall survival rates were 80.8 and 44.0%, respectively. As for conduit patency, two grafts (9.1%) demonstrated evidence of occlusion during long-term follow-up, but no additional interventions were required due to no complications related. CONCLUSION: Our study, confirming data from existing literature, showed that the prosthetic reconstruction of the SVC system is a feasible additional procedure during resection of thymic tumor infiltrating the venous mediastinal axis, minimally increasing postoperative complications in experienced hands.

Plasmon-Driven Catalysis on Molecules and Nanomaterials.

As a new class of photocatalysts, plasmonic noble metal nanoparticles with the unique ability to harvest solar energy across the entire visible spectrum and produce effective energy conversion have been explored as a promising pathway for the energy crisis. The resonant excitation of surface plasmon resonance allows the nanoparticles to collect the energy of photons to form a highly enhanced electromagnetic field, and the energy stored in the plasmonic field can induce hot carriers in the metal. The hot electron-hole pairs ultimately dissipate by coupling to phonon modes of the metal nanoparticles, resulting in a higher lattice temperature. The plasmonic electromagnetic field, hot electrons, and heat can catalyze chemical reactions of reactants near the surface of the plasmonic metal nanoparticles. This Account summarizes recent theoretical and experimental advances on the excitation mechanisms and energy transfer pathways in the plasmonic catalysis on molecules. Especially, current advances on plasmon-driven crystal growth and transformation of nanomaterials are introduced. The efficiency of the chemical reaction can be dramatically increased by the plasmonic electromagnetic field because of its higher density of photons. Similar to traditional photocatalysis, energy overlap between the plasmonic field and the HOMO-LUMO gap of the reactant is needed to realize resonant energy transfer. For hot-carrier-driven catalysis, hot electrons generated by plasmon decay can be transferred to the reactant through the indirect electron transfer or direct electron excitation process. For this mechanism, the energy of hot electrons needs to overlap with the unoccupied orbitals of the reactant, and the particular chemical channel can be selectively enhanced by controlling the energy distribution of hot electrons. In addition, the local thermal effect following plasmon decay offers an opportunity to facilitate chemical reactions at room temperature. Importantly, surface plasmons can not only catalyze chemical reactions of molecules but also induce crystal growth and transformation of nanomaterials. As a new development in plasmonic catalysis, plasmon-driven crystal transformation reveals a more powerful aspect of the catalysis effect, which opens the new field of plasmonic catalysis. We believe that this Account will promote clear understanding of plasmonic catalysis on both molecules and materials and contribute to the design of highly tunable catalytic systems to realize crystal transformations that are essential to achieve efficient solar-to-chemical energy conversion.

Plasmon induced deprotonation of 2-mercaptopyridine.

Surface plasmons can provide a novel route to induce and simultaneously monitor selective bond formation and breakage. Here pH-induced protonation, followed by plasmon-induced deprotonation of 2-mercaptopyridine was investigated using surface- and tip-enhanced Raman scattering (SERS and TERS). A large difference in the deprotonation rate between SERS and TERS will be demonstrated and discussed with respect to hot-spot distribution.

Transurethral needle electrode resection and transurethral holmium laser resection of bladder cancer.

PURPOSE: The aim of the present study was to explore the efficacy and safety of transurethral needle electrode resection and transurethral holmium laser resection of non-muscular invasive bladder cancer (NMIBC). PATIENTS AND METHODS: In this prospective, case-control study, patients from the Urinary Surgery or Oncology Department who met the inclusion and exclusion criteria received transurethral needle electrode resection (n = 52) or transurethral holmium laser resection (n = 51). RESULTS: A total of 103 patients with NMIBC were included in the present study, with 68 males and 35 females. Their mean age was 57.3 years. Sixty-two patients had Ta, 15 patients had T1, and 26 patients had Tis. Operative time, intraoperative blood loss, postoperative gross hematuria time, bladder irrigation time, and postoperative hospitalization time were all significantly lower in the transurethral holmium laser resection group than the transurethral needle electrode resection group. After resection, transurethral holmium laser resection significantly decreased the value of HGF, TSH, and TNF-α versus the transurethral needle electrode resection group. The incidence of obturator reflex was significantly lower in the transurethral holmium laser resection group than the transurethral needle electrode resection group. There was no significant difference in disease-free survival rate and progression-free survival rate between the two groups. CONCLUSIONS: Transurethral holmium laser resection has clinical advantages in the treatment of NMIBC.

Plasmon-Driven Rapid In Situ Formation of Luminescence Single Crystal Nanoparticle.

Single crystal nanomaterials are very important for the fundamental investigation and application of luminescence. However, a very critical growth condition or high temperature treatment is always required for their preparation. Here, an easy and rapid in situ achievement of a single crystal luminescent material is realized by taking advantage of plasmon-induced thermal and catalysis effects. With the assistance of localized surface plasmon resonance of Au nanoparticles, polycrystalline NaYF4 transforms to single crystal Y2 O3 in tens of milliseconds, resulting in remarkable improvement of luminescence emission. It is important to point out that the single crystal transformation is also achieved even at a very low temperature, which is impossible with conventional approaches. Such a convenient and efficient plasmon assisted scheme provides a new technology for the rapid achievement of single crystal materials and extends the application of surface plasmon to a much broader field.

Plasmon induced polymerization using a TERS approach: a platform for nanostructured 2D/1D material production.

Plasmon-induced chemical reactions have recently attracted great attention as a promising method for high efficiency light-energy conversion and proved to be useful in a wealth of different domains of chemistry and physics. One of the interesting and, so far, less explored avenues of such reactions is their potential for efficient, highly localized and controlled polymer production. Here, we present the first example of a localized, directed plasmon catalyzed polymerization process of a self-assembled monolayer on both silver and gold surfaces monitored by surface- and tip-enhanced Raman spectroscopy (SERS and TERS). As a proof-of-concept, a bi-functionalized dibenzo(1,2)dithiine-3,8-diamine (D3ATP) molecule that undergoes a well-known plasmon-induced coupling via the amino group into an azo group has been used. Initial dimerization is demonstrated using established marker bands associated with the formation of the azo group. A subsequent indicator for a polymerization reaction, the appearance of a new characteristic band, is monitored by time-dependent SERS and TERS experiments. We demonstrate that the dimerization reaction and hence, the subsequent polymerization, can be induced by a plasmonic feature, e.g. a TERS tip, at specific nanoscale locations and, at a much larger micron scale, by continuously scanning the plasmonic probe. The presented results provide the basis for designing further plasmonic catalysis experiments in general, and offer a new platform for producing ultra-thin polymer films with a defined structural dimension.

Tip-Enhanced Raman Spectroscopy.

Tip-enhanced Raman spectroscopy (TERS), a combination of Raman spectroscopy and apertureless near-field scanning optical microscopy using a metallic tip which resonates with the local mode of the surface plasmon, can provide a high-sensitive and high-spatial-resolution optical analytical approach. The basic principle of TERS, common experimental setups, various SPM technologies, and excitation/collection configurations are introduced as well as recent research progress with respect to TERS.

Label-free monitoring of plasmonic catalysis on the nanoscale.

Plasmonics is the description of specific light matter interactions of metallic structures. In general the size of such structures is well in the nanometer regime and also determines such specific characteristics as color, field confinement etc. Plasmon-induced hot electrons play a vital role in so-called plasmonic catalysis, a field that has recently attracted attention as a new reaction platform. Current reports introduce such nanoscale catalysis as an effective approach to concentrate the energy of visible light and direct it to adsorbed molecules, thereby increasing the chemical reaction rate, and controlling the reaction selectivity. In this review, we present various plasmon-catalyzed reactions specifically monitored with Raman spectroscopy, namely surface-enhanced Raman scattering (SERS), remote SERS (Re-SERS) and tip-enhanced Raman scattering (TERS). These techniques utilize the signal enhancing effect of the metal nanoparticles. However, at the same time they can be used to control the actual reactivity. In the first part, the mechanism of plasmonic catalysis is introduced. Then it is shown how catalytic reactions can be spectroscopically investigated far beyond the diffraction limit using TERS. Finally, the sensitivity of the methods is discussed.

Near field plasmonic gradient effects on high vacuum tip-enhanced Raman spectroscopy.

Near field gradient effects in high vacuum tip-enhanced Raman spectroscopy (HV-TERS) are a recent developing ultra-sensitive optical and spectral analysis technology on the nanoscale, based on the plasmons and plasmonic gradient enhancement in the near field and under high vacuum. HV-TERS can not only be used to detect ultra-sensitive Raman spectra enhanced by surface plasmon, but also to detect clear molecular IR-active modes enhanced by strongly plasmonic gradient. Furthermore, the molecular overtone modes and combinational modes can also be experimentally measured, where the Fermi resonance and Darling-Dennison resonance were successfully observed in HV-TERS. Theoretical calculations using electromagnetic field theory firmly supported experimental observation. The intensity ratio of the plasmon gradient term over the linear plasmon term can reach values greater than 1. Theoretical calculations also revealed that with the increase in gap distance between tip and substrate, the decrease in the plasmon gradient was more significant than the decrease in plasmon intensity, which is the reason that the gradient Raman can be only observed in the near field. Recent experimental results of near field gradient effects on HV-TERS were summarized, following the section of the theoretical analysis.

Automatic Identification of Human Erythrocytes in Microscopic Fecal Specimens.

Traditional fecal erythrocyte detection is performed via a manual operation that is unsuitable because it depends significantly on the expertise of individual inspectors. To recognize human erythrocytes automatically and precisely, automatic segmentation is very important for extraction of characteristics. In addition, multiple recognition algorithms are also essential. This paper proposes an algorithm based on morphological segmentation and a fuzzy neural network. The morphological segmentation process comprises three operational steps: top-hat transformation, Otsu's method, and image binarization. Following initial screening by area and circularity, fuzzy c-means clustering and the neural network algorithms are used for secondary screening. Subsequently, the erythrocytes are screened by combining the results of five images obtained at different focal lengths. Experimental results show that even when the illumination, noise pollution, and position of the erythrocytes are different, they are all segmented and labeled accurately by the proposed method. Thus, the proposed method is robust even in images with significant amounts of noise.

Surface enhanced fluorescence from silver film substrate decorated with nanohole arrays.

The fluorescence enhancement effect of Rh6G molecules deposited on the silver film substrate decorated with nanohole arrays was investigated in this paper. The prepared substrate, decorated with nanohole arrays, was fabricated with the deposition of silver films onto the anodic aluminum oxide templates through magnetron sputtering method. Compared with the conventional continuous silver film substrate, the prepared substrate shows better enhanced effect. Particularly, the fluorescence enhancement factor has a relationship with the size and period of the nanohole arrays. The experimental observations were analyzed with local surface plasmon resonance model. The results of current work highlight the importance of strong electromagnetic coupling effect in surface enhanced fluorescence.

The causality between leisure sedentary behaviors, physical activity and obstructive sleep apnea: a bidirectional Mendelian randomization study.

Background: Previous observational studies have shown a correlation between leisure sedentary behaviors (LSB) and physical activity (PA) with the incidence of obstructive sleep apnea (OSA). However, the causal associations remain unknown. Therefore, our study used bidirectional two-sample Mendelian randomization (MR) to identify potential causal relationships between LSB/PA and OSA. Methods: We sourced genetic variation data for LSB and PA from the UK Biobank, while data on OSA were collected from the FinnGen study. The primary analysis method employed was the inverse variance weighted (IVW) approach, complemented by the weighted median and MR-Egger methods. For sensitivity analyses, we conducted Cochran's Q test, the MR-Egger intercept test, the MR-PRESSO global test, and the leave-one-out analysis. Results: IVW analyses showed that genetically predicted leisure television watching (odds ratio [OR] = 1.38, 95% confidence interval [CI] = 1.09-1.75, p = 0.007) and computer use (OR = 1.48, 95% CI = 1.15-1.92, p = 0.002) significantly increased the risk of OSA. Conversely, self-reported vigorous physical activity (VPA) (OR = 0.33, 95% CI = 0.11-0.98, p = 0.046) may reduce the risk of OSA. No causal effects on OSA risk were observed for driving or self-reported moderate-to-vigorous physical activity. Furthermore, the reverse MR analysis indicated no significant causal relationship between OSA and any LSB/PA phenotype. Sensitivity tests showed no significant heterogeneity or horizontal pleiotropy. Conclusion: This study suggests that leisurely television watching and computer use are risk factors for OSA, while VPA may be a protective factor. Additionally, OSA does not affect PA or LSB levels. We recommend reducing sedentary activities, particularly television watching and computer use, and prioritizing VPA to reduce the risk of OSA. Further research in diverse populations and settings is needed to validate these findings.

Interfacial Second-Harmonic Generation via Superposition of Symmetries in a Double-Resonance-Enhanced Plasmonic Nanocavity.

Second-harmonic generation (SHG) has rapidly advanced with the miniaturization of on-chip devices and has found many applications, including optical frequency conversion, nonlinear imaging, and quantum technology. However, owing to the obvious phase-matching constraints involved in nonlinear optical interactions in bulk crystals and the decrease in the length and strength of nonlinear interactions in nanophotonic and surface/interface systems, improving the SHG efficiency and manipulating its optical properties at the nanoscale are challenging tasks. Herein, a monocrystalline silver microplate and nanocube-coupled nanocavity with double-resonance plasmonic modes and an ultrasmall gap were constructed, resulting in efficiently enhanced SHG. In particular, the SHG from the silver microplate (111) is polarization-dependent, and the anisotropy of the SHG in the plasmonic nanocavity can be further controlled via the superposition of symmetries at the interface and plasmonic waveguide-cavity modes. The interfacial SHG provides technology for developing lattice surface atomic arrangement and nanostructure rapid characterization, nonlinear light sources, and on-chip nonlinear nanophotonic devices.

Thermal-effect dominated plasmonic catalysis on silver nanoislands.

Plasmonic metal nanostructures with the intrinsic property of localized surface plasmon resonance can effectively promote energy conversion in many applications such as photocatalysis, photothermal therapy, seawater desalinization, etc. It is known that not only are plasmonically excited hot electrons generated from metal nanostructures under light irradiation, which can effectively trigger chemical reactions, but also plasmonically induced heating simultaneously occurs. Although plasmonic catalysis has been widely explored in recent years, the underlying mechanisms for distinguishing the contribution of hot electrons from thermal effects are not fully understood. Here, a simple and efficient self-assembly system using silver nanoislands as plasmonic substrates is designed to investigate the photo-induced azo coupling reaction of nitro- and amino-groups at various temperatures. In the experiments, surface-enhanced Raman spectroscopy is employed to monitor the time and temperature dependence of plasmon-induced catalytic reactions. It was found that a combination of hot electrons and thermal effects contribute to the reactivity. The thermal effects play the dominant role in the plasmon-induced azo coupling reaction of nitro-groups, which suggests that the localized temperature must be considered in the development of photonic applications based on plasmonic nanomaterials.

Plasmonic scissors for molecular design.

Heterogeneous catalysts play an important role in surface catalytic reactions, but selective bond breaking and control of reaction products in catalytic processes remain significant challenges. High-vacuum tip-enhanced Raman spectroscopy (HV-TERS) is one of the best candidates to realize surface catalytic reactions. Herein, HV-TERS was employed in a new method to control dissociation by using hot electrons, generated from plasmon decay, as plasmonic scissors. In this method, the N=N bond in 4,4'-dimercaptoazobenzene was selectively dissociated by plasmonic scissors, and the reaction products formed from the radical fragment (SC6H5N) were controlled by varying the pH value. Under acidic conditions, p-aminothiophenol was produced from the radical fragment by attachment of hydrogen ions, whereas under alkaline conditions, 4-nitrobenzenethiol was obtained by attachment of oxygen ions to the substrate.

Editorial for Special Issue "Plasmon Assisted Near-Field Manipulation and Photocatalysis".

Accurately establishing the near field is crucial to enhancing optical manipulation and resolution, and is pivotal to the application of nanoparticles in the field of photocatalysis [...].

Surface-Ligand-Modified CdSe/CdS Nanorods for High-Performance Light-Emitting Diodes.

Colloidal nanocrystals (NCs) play an important role in the field of optoelectronic devices such as photovoltaic cells, photodetectors, and light-emitting diodes (LEDs). The properties of NC films are strongly affected by ligands attached to them, which constitute a barrier for charge transport between adjacent NCs. Therefore, the method of surface modification by ligand exchange has been used to improve the electrical conductivity of NC films. However, surface modification to NCs in LEDs can also affect emission characteristics. Among NCs, nanorods have unique properties, such as suppression of nonradiative Auger recombination and linearly polarized light emission. In this work, CdSe/CdS nanorods (NRs) were prepared by the hot injection method. To increase the charge transport into CdSe/CdS NRs, we adopted ligand modification to CdSe/CdS NRs. Using this technique, we could shorten the injection barrier length between CdSe/CdS NRs and adjacent layers. It leads to a more balanced charge injection of electron/hole and a greatly increased current efficiency of CdSe/CdS NR-LEDs. In the NR-LEDs, the ligand exchange boosted the electroluminance, reaching a sixfold increase from 848 cd/m2 of native surfactants to 5600 cd/m2 of the exchanged n-octanoic acid ligands at 12 V. The improvement of CdSe/CdS NR-LED performance is closely correlated to the efficient control of charge balance via ligand modification strategy, which is expected to be indispensable to the future NR-LED-based optoelectronic system.