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A long 0.9 ps lifetime of the upper excited singlet state in perylene is resolved by femtosecond pump–probe measurements under ultraviolet (4.96 eV) excitation and further validated by theoretical simulations of transient absorption kinetics. This finding prompts exploration and development of novel perylene-based materials for upper excited state photochemistry applications. [ABSTRACT FROM AUTHOR]

Optical interferometry is a promising alternative for acoustic detection as it records the changes of interference patterns. Apart from interferometric sensor heads, readout systems also play a crucial role in sensing performance. Here, inspired by the soliton molecule vibrations in ultrafast lasers, we introduce an efficient real-time spectral interferometry (RSI) approach to read out the Fabry–Pérot interferometer (FPI) for acoustic detection. Broadband pulses, emitted from an ultrafast fiber laser, are launched into the FPI sensor. Pseudo dual-pulse molecule is constructed by virtue of the equivalent two-beam interference of the FPI and modulated by the diaphragm transducer. The acoustic driven "molecular vibration" conforms to the sound applied on the metal diaphragm. Hence, the acoustic signals can be directly recorded by the successive dual-pulse spectral interferograms, imaged as a spectral encoded "soundtrack." We experimentally achieve the real-time characterization of both the audible and ultra sounds by retrieving the relative phase evolutions with a phase resolution of 37.6 mrad and preliminarily verifying the feasibility of the RSI in acoustic detection. This approach to wideband acoustic detection highlights an advanced application of ultrafast laser sources and paves an efficient way for interrogating the interferometric fiber sensors. [ABSTRACT FROM AUTHOR]

Moving mass control (MMC) is considered a promising approach to regulating the attitude of an aircraft via the motion of internal moving masses. The present investigation proposes a moving mass control scheme for a high-altitude long-endurance (HALE) unmanned aerial vehicle (UAV) with a single slider moving longitudinally. To that end, a longitudinal nonlinear motion model is established, and pitch dynamics are analyzed. Furthermore, the influence of the slider parameters on the dynamic characteristics of the UAV and the change in control efficiency with speed are analyzed. Finally, a detailed root-locus-based stability and sensitivity analysis of the proposed control scheme is formulated. At an altitude of 20,000 m, the MMC scheme's efficiency coefficient was 200% of that of elevator scheme at the cruise speed. The simulation results show that the control efficiency of the moving mass control scheme was significantly higher than that of the traditional elevator control scheme under the conditions of high altitude and low speed. [ABSTRACT FROM AUTHOR]

Anti-resonant hollow core fibers (AR-HCFs) provide a promising solution for photothermal spectroscopy and photoacoustic imaging applications. Here, the AR-HCF serves as a micro platform to induce the photothermal/photoacoustic effect. Since the Bragg structure can induce multiple AR effects compared with the general AR-HCF, we proposed a novel device, the AR-BHCF (AR-HCF with Bragg cladding), to enhance the excitation efficiency. The simulation and experimental results validate that the AR-BHCF dominates in having a stronger ability to confine the optical field in the air core indeed. Then, the acoustic signal stimulated by the photoacoustic effect will propagate along with the fiber axial, and part of it will penetrate out of the AR-BHCF. The results revealed that the transmission bandwidth of the acoustic wave in the AR-BHCF ranges from 1 Hz to 1 MHz, covering infrasound to ultrasound. In particular, a constant coefficient of 0.5 exists in the acoustic wave fading process, related to the propagation frequency and time. The acoustic signal can be monitored in real time, assisted by the ultra-highly sensitive sensor head. Therefore, BHCF-based devices combined with photoacoustic techniques may accelerate their sensing applications. Meanwhile, this scheme shines a light on the theoretical foundation of novel short-haul distributed acoustic sensing. [ABSTRACT FROM AUTHOR]

To accurately unwrap the high-order orbital angular momentum (OAM) for multiplexed vortex beams is a challenge. In this work, over ±160 order OAM topological charges have been unwrapped in multiplexed optical links. Optical imaging based discrepancy identification enables the multiplexed OAM modes separating in physics, and the intelligent pattern recognition further promotes its unwrapping in numerical domain. Particularly, the combination of annular phase grating and auxiliary beams features compound spiral stripes, which paves the way for optical intensity recognition with low-complexity and high-commonality. Moreover, the spiral direction characterizes the symbol of the OAM states, which dramatically broadens the amount of multiplexed links. Here, optical separating means assisted by intelligent pattern recognition opens up a new route to high-speed and large-capacity optical communication, which may shed new light on 6G application. [ABSTRACT FROM AUTHOR]

The self-assembly of optical solitons propagating in nonlinear dissipative systems spreads the concept of soliton molecules. Assisted with the real-time spectral interferometry, plentiful internal dynamics has been probed within the multi-pulse patterns, emphasizing the striking analogies with the matter molecules. Therefrom, these particle-like behaviors would yield more intriguing landscapes toward the extended degrees of freedom considering increased constituents. Here, we transfer the concept of "isomer" to the experimental investigation on the unexplored isomeric dynamics of soliton molecules in parallel. Particularly, two isomers for soliton triplets and four isomers for soliton quadruplets are captured under different self-assembled forms, within each of which the binding separations and relative phases of the constituents are governed by mutual soliton interactions. With the diverse separation-phase evolving trajectories mapped in the interaction plane, detailed insights into the temporal distribution and the transient dynamics are displayed with respect to a panorama of the isomeric dynamics. The perspective of optical isomers shed new light on the analogy with matter molecules, and the underlying isomeric dynamics may stimulate the artificial manipulation of various soliton molecules for ultrafast applications. [ABSTRACT FROM AUTHOR]

The ultrafast dynamics of triplet excitons and polarons in hexaphenyl film was investigated by time-resolved fluorescence and femtosecond transient absorption techniques under various excitation photon energies. Two distinct pathways of triplet formation were clearly observed. Long-lived triplet states are populated within 4.5 ps via singlet fission-intersystem crossing, while the short-lived triplet states (1.5 ns) are generated via singlet fission from vibrational electronic states. In the meantime, polarons were formed from hot excitons on a timescale of <30 fs and recombined in ultrafast lifetime (0.37 ps). In addition, the characterization of hexaphenyl film suggests the morphologies of crystal and aggregate to wide applications in organic electronic devices. The present study provides a universally applicable film fabrication in hexaphenyl system towards future singlet fission-based solar cells. [ABSTRACT FROM AUTHOR]

A low-cost and easy-to-construct dye-sensitized photoanode for water oxidation was prepared by co-loading a new triphenylamine donor–acceptor organic chromophore (D1) and a Co4O4 cobalt cubane-based water oxidation catalyst (CoF) on TiO2 thin films. As the first example of a molecular catalyst-based, noble metal-free, dye-sensitized photoanode, the electrode, TiO2‖D1,CoF, produces a higher photocurrent than other noble metal-free, dye-sensitized photoanodes with a relatively high faradaic efficiency for O2 production. The success of the dyad system lies in retarded interfacial charge recombination and extended light absorption both of which take advantage of the pyridine anchor-functionalized chromophore. In addition, the CoF catalyst, decorated with hydrophobic aliphatic chains, serves as a protective layer for stabilizing the organic dyes on electrode surfaces. Transient absorption measurement suggests the accumulation of oxidative equivalents on CoF by electron transfer on the TiO2 surface. The results and design principles presented here demonstrate the use of molecular engineering as a powerful tool for the exploration of low-cost solar water-splitting devices. [ABSTRACT FROM AUTHOR]

Background. The role of HERV–H LTR-associating 2 (HHLA2) in cancer remains still unclear. This study analyzed the correlation between the prognosis and immune infiltrate function of HHLA2 in pan-cancers. Methods. HHLA2 expression in pan-cancers was analyzed using the databases of TCGA, GTEx, TIMER, GEPIA, UALCAN, and GSEA databases. Multiple bioinformatic methods were used to investigate the correlation of HHLA2 expression with survival, pathological stage, tumor mutation burden (TMB), microsatellite instability (MSI), tumor microenvironment (TME), immune cell infiltration, and immune checkpoint gene (ICG), and gene functional enrichment was performed by Gene Set Enrichment Analysis (GSEA) and Gene Set Variation Analysis (GSVA). Results. HHLA2 was aberrantly expressed and was strongly correlated with positive or negative prognosis in multiple human cancers, which revealed that HHLA2 might play a vital role during cancer formation and development. Kaplan–Meier (KM) curves across cancers revealed that HHLA2 expression was correlated with overall survival (OS) in eight cancers, disease-specific survival (DSS) in seven cancers, disease-free interval (DFI) in four cancers, and progression-free interval (PFI) in nine cancers. Furthermore, HHLA2 expression was positively correlated with TMB in 6 cancer types and negatively associated with TMB in 7 cancer types, respectively. The former included ESCA, HNSC, KIRP, PAAD, PRAD, and PCPG; the latter contained COAD, LGG, LUAD, LUSC, THYM, THCA, and UCEC. Additionally, we found HHLA2 expression was negatively related to MSI in ACC, COAD, PAAD, and UCEC. More importantly, HHLA2 expression was remarkably correlated with the degree of tumor-infiltrating immune in many cancers, including B cells, CD4+ T cells, CD8+ T cells, neutrophils, macrophages, and dendritic cells and strongly associated with immune checkpoint genes in 13 tumor types. Furthermore, KEGG pathway analyses indicated that HHLA2 could potentially impact cancer etiology or pathogenesis by functioning in amino sugar and nucleotide sugar metabolism, cytosolic DNA sensing pathway, and peroxisome pathways. Meanwhile, GSVA analysis results all indicate that HHLA2 was correlated with TSC/mTOR, RTK, RAS/MAPK, PI3K/AKT, EMT, DNA Damage Response, Cell Cycle, and Apoptosis pathways in various cancers. Conclusion. HHLA2 can function as a prognostic biomarker and correlate with tumor immunity in human pan-cancer due to its important role in tumorigenesis and immune infiltration, which provides new insight into developing new targeted treatments in cancers. [ABSTRACT FROM AUTHOR]

The potential to improve the efficiency of photovoltaic devices through singlet exciton fission (SF) has raised interest of researchers during the last decade. Organic small molecules of rubrene were fabricated into spherical nanoaggregates (NAs) of diameter ∼250 nm by the re-precipitation method. J-type aggregation inside the NA with pivotal electronic coupling occurs in NAs. Observed strong fluorescence quenching indicates the presence of competing pathways in the NAs: hot and thermally activated SF, triplet–triplet annihilation (TTA), and energy transfer between inhomogeneously broadened NA ensembles. SF which proceeds directly from upper excited electronic states within 340 fs (vs 200 fs in crystals; 30 fs in films) results in a triplet quantum yield of 162%. With an aim to apply rubrene in photovoltaics, a rubrene NA-integrated film was prepared on top of the CH3NH3PbI3 layer. Triplet formation within 25 ps in the NA layer was well-documented. Subsequently, the triplet excitons are accumulated and further upconverted via TTA to populate the conduction band of the perovskite within 39 ps (80%) and ≫10 ns (20%). Our findings are crucial for understanding photophysical mechanisms of rubrene/perovskite interaction after light absorption by rubrene. [ABSTRACT FROM AUTHOR]

Acid‐catalysed Friedländer cyclization of 2‐aminobenzophenones with 1,2‐, 1,3‐, and 1,4‐cyclohexadiones, followed by aromatization, has been used to prepare dibenzophenanthrolines (DBPs) containing 1,10‐, 1,7‐ and 4,7‐phenanthroline units, whose optoelectronic properties have been compared. The LUMO energies for all isomers were similar but the 4,7‐isomers possessed significantly higher HOMOs than the other isomers, resulting in them having smaller HOMO‐LUMO energy gaps. Compared with 1,10‐DBP isomers, the emission of 1,7‐DBPs is strongly quenched due to efficient charge transfer. The 4,7‐DBP isomers show strongly enhanced photoluminescence due to excimer formation but appear to be less photostable due to their higher HOMO levels. Bis(phenylethynyl)‐substituted derivatives demonstrated improved solubility and stronger luminescence properties than their unsubstituted analogues. [ABSTRACT FROM AUTHOR]

New Delhi metallo-β-lactamases (NDMs), including at least 28 variants, are a rapidly emerging family of β-lactamases worldwide, with a variety of infections caused by NDM-positive strains usually associated with very poor prognosis and high mortality. NDMs are the most prevalent carbapenemases in Escherichia coli (E. coli) worldwide, especially in China. The vast majority of bla NDM cases occur on plasmids, which play a vital role in the dissemination of bla NDM. To systematically explore the relationships between plasmids and bla NDM genes in E. coli and obtain an overall picture of the conjugative and mobilizable bla NDM-positive plasmids, we analyzed the variants of bla NDM, replicon types, phylogenetic patterns, conjugative transfer modules, host STs, and geographical distributions of 114 bla NDM-positive plasmids, which were selected from 3786 plasmids from 1346 complete whole genomes of E. coli from the GenBank database. We also established links among the characteristics of bla NDM-positive plasmids in E. coli. Eight variants of bla NDM were found among the 114 bla NDM-positive plasmids, with bla NDM–5 (74 bla NDM–5 genes in 73 plasmids), and bla NDM–1 (31 bla NDM–1 genes in 28 plasmids) being the most dominant. The variant bla NDM–5 was mainly carried by the IncX3 plasmids and IncF plasmids in E. coli , the former were mainly geographically distributed in East Asia (especially in China) and the United States, and the latter were widely distributed worldwide. IncC plasmids were observed to be the predominant carriers of bla NDM–1 genes in E. coli , which were mainly geographically distributed in the United States and China. Other bla NDM–1-carrying plasmids also included IncM2, IncN2, and IncHI1. Moreover, the overall picture of the conjugative and mobilizable bla NDM-positive plasmids in E. coli was described in our study. Our findings enhance our understanding of the genetic diversity and characteristics of bla NDM-positive plasmids in in E. coli. [ABSTRACT FROM AUTHOR]

With the low-carbon revolution, many firms face the continuous challenge for reducing carbon emissions in their supply chain activities. Built upon the strategic safety stock placement model, in this paper, we model the carbon emissions for each stage of a multi-echelon supply chain as a function of the service time guaranteed by this stage to its immediate downstream stages. We establish that there is a negative correlation between service time and carbon emissions at each stage. Based on this, we develop two models to study the trade-off between service time and carbon emissions for safety stock placement in multi-echelon supply chains by considering carbon cap and carbon tax, respectively. Both of them are solved using iterative piecewise linear approximations. We implement these two models to study how carbon cap, carbon emission cost rate and guaranteed service time affect the optimal safety stock placement using a real chain. [ABSTRACT FROM PUBLISHER]

Optical microfiber-based refractometer, which relies on modal interference operating near the dispersion turning point (DTP), has attracted a high level of research interest. The ultrahigh sensitivity can be achieved by mitigating the group effective refractive index difference between the modes in the coupling. Through modifying the microfiber diameter, the group effective refractive index difference can be modified to zero which is defined as DTP. However, all the DTP-based sensors report low fabrication tolerance and narrow operation bandwidth of probing wavelength for the high-sensitivity region where the refractive index (RI) sensitivities higher than 104 nm/RIU can be achieved, which extremely limits the practical applications. To address the challenge, we manipulate and optimize the mode dispersion by using a tapered specially-designed single stress-applying fiber (SSAF). By introducing the stress-applying part (SAP) into the cladding, the wavelength sensitivity of the group effective RI difference can be significantly reduced through the flexibly engineerable control over the material index. In this way, the operation bandwidth is dramatically broadened for 500 nm in comparison with that of conventional microfiber with the same diameter based on DTP, indicating a broad range of optional probing wavelength and high fabrication tolerance. We experimentally verify the ultrahigh sensitivity and broadband operation around the DTP using an SSAF-based microfiber with a waist diameter of about 2.3 μm. The maximum RI sensitivity of 30563 nm/RIU is obtained. [ABSTRACT FROM AUTHOR]

Bladder cancer is one of the most common urogenital malignancies in the world, and there are no adequate prognostic indicators. CNTD2 is one of the atypical cyclins, which may be related to the cell cycle and even the development of cancers. Early studies have shown that CNTD2 is closely related to the occurrence and development of many malignant tumors. However, the mechanism of CNTD2 in bladder cancer has not been reported. In our research, we explored the different expressions of CNTD2 between 411 bladder cancers and 19 normal bladder tissues based on the TCGA dataset. CNTD2 -related signaling pathways were identified through the GSEA. We analyzed the associations of CNTD2 expression and bladder cancer progression and survival using GSE13507. Compared with 19 cases of normal bladder tissue, CNTD2 gene expression was increased in 411 cases of bladder cancer. The high expression of CNTD2 strongly correlated with grade (P < 0.0001), T classification (P = 0.0001), N classification (P = 0.00011), M classification (P = 0.044), age (P = 0.027), and gender (P = 0.0012). Bladder cancer patients with high CNTD2 expression had shorter overall survival (P < 0.001). In the meantime, univariate and multivariate analyses showed that the increased expression of CNTD2 was an independent factor for poor prognosis in bladder cancer patients (P < 0.001 and P < 0.001, respectively). CNTD2 expression is closely related to bladder cancer progression, and the high expression of CNTD2 may be an adverse biomarker in bladder cancer patients. [ABSTRACT FROM AUTHOR]

Most existing facility location models assume that the facility cost is either a fixed setup cost or made up of a fixed setup and a problem-specific concave or submodular cost term. This structural property plays a critical role in developing fast branch-and-price, Lagrangian relaxation, constant ratio approximation, and conic integer programming reformulation approaches for these NP-hard problems. Many practical considerations and complicating factors, however, can make the facility cost no longer concave or submodular. By removing this restrictive assumption, we study a new location model that considers general nonlinear costs to operate facilities in the facility location framework. The general model does not even admit any approximation algorithms unless P = NP because it takes the unsplittable hard-capacitated metric facility location problem as a special case. We first reformulate this general model as a set-partitioning model and then propose a branch-and-price approach. Although the corresponding pricing problem is NP-hard, we effectively analyze its structural properties and design an algorithm to solve it efficiently. The numerical results obtained from two implementation examples of the general model demonstrate the effectiveness of the solution approach, reveal the managerial implications, and validate the importance to study the general framework. [ABSTRACT FROM AUTHOR]

Quasi-two-dimensional (2D) layered perovskites have lately attracted extensive research interest due to their superior environmental stability to their three-dimensional (3D) counterparts. While solar cells based on 2D layered perovskites have achieved remarkably high efficiencies over 18%, their intrinsic carrier dynamics after photoexcitation remain obscure due to the presence of bound excitons and the coexistence of multiple layered perovskite phases. Discrepancies were found in the interpretations of the reported ultrafast processes with hundreds of femto- or pico-second time scales in previous literature via transient absorption measurements. Here, carrier dynamics in (PEA)2(MA)2Pb3I10 (PEA = C6H5(CH2)2NH3; MA = CH3NH3) 2D layered perovskite was systematically studied through a combination of transient absorption and time-resolved photoluminescence measurements with femtosecond time resolution. The ultrafast sub-ps (100–400 fs) carrier dynamics is unambiguously demonstrated due to hot carrier relaxation. Carrier transport occurs from small n layered perovskites to their surrounding 3D like (large n) perovskite via energy transfer on the time scale of 2–300 ps. These results provide valuable information on the intrinsic carrier dynamics in 2D layered perovskites which would be helpful in further improving the device performance. [ABSTRACT FROM AUTHOR]

Acoustic measurement is the most widely used non-electric method to detect partial discharge (PD) signals by detect the ultrasonic waves arisen from partial discharge. To solve the shortages of low sensitivity and susceptibility to interferences, a gold diaphragm based Fabry-Perot interferometer ultrasonic sensor is proposed and experimentally demonstrated. Its high acoustic sensitivity and directional insensitivity shows great capability for PD detection and localization. Experimental results illustrate a well acoustic response from 20 kHz to 150 kHz when standard ultrasonic signals applied. The frequency range covers the acoustic frequencies derived from PD process. The ultrasonic signals from a discharge source is measured by the proposed fiber optic sensor with difference distances and incident angles. The output shows an attenuation of 1.32 dB/m and the sensor can detect weak signals as far as 3 m. The directional deviation coefficients are less than 10% for each measuring distance which exhibits directional independence. Two localization techniques with a sensor array (four sensors) are proposed and simulations are carried out to verify them feasible. The fiber-optic ultrasonic sensor may have a great potential in stability maintenance of electrical power systems due to its low cost, compact structure, environmentally robustness and simple manufacturing. [ABSTRACT FROM AUTHOR]

Dispersion distribution and optical gain dynamics introduce vivid pulse evolution in fiber lasers. Here, we report on a multi-output fiber laser mode-locked by nonlinear polarization rotation (NPR) in net normal-dispersion regime. In particular, the asymmetry settings of the laser parameters can introduce the spectral reshaping and pulse breathing process at different output ports. Both the transformation from gain-guided dissipative solitons (GGDSs) to similaritons and periodic stretching and compression of pulse widths are experimentally observed. Additionally, intriguing pulse fusion and splitting of GGDS molecules are recorded, which further validates the pulse breathing process during propagating in the laser cavity. To the best of our knowledge, we first experimentally investigate the pulse self-evolution based on a multi-output fiber laser in GGDS-similariton regime. All these findings can enrich our understanding towards the breathing dynamics of ultrashort pulses. [ABSTRACT FROM AUTHOR]

Recent research on nonlinear multimode interference (NL-MMI) based mode-locking method provides a new approach for ultrafast all-fiber lasers. Here, we report on the polarization dynamics of group velocity locked vector solitons (GVLVSs) and noise-like vector pulses (NLVPs) in a graded-index multimode fiber (GIMF) based all-fiber laser. Due to the non-polarization sensitive characteristic of the NL-MMI, emitted pulses automatically evolve into the vector multi-pulse complexes constituting two orthogonally polarized components. Beyond the traditional polarization resolved measurement, dispersive Fourier transform (DFT) and polarization beam splitting techniques are jointly adopted to enable insights into the transient polarization dynamics of the vector solitons. It is found in real time that the two orthogonally polarized components oppositely shift their central wavelengths to compensate the polarization dispersion. In addition, stationary and pulsating NLVPs are respectively unfolded by the DFT based polarization resolved measurement. Especially, the pulsating NLVPs before and after polarization resolved measurement are accompanied with the identical periodic spectral breathing process. All these findings reveal the vectorial nature in NL-MMI based ultrafast fiber lasers, as well as highlight the transient polarization dynamics and the long-term pulsation in dissipative systems. [ABSTRACT FROM AUTHOR]

A new optical fiber twist sensor with temperature compensation mechanism is designed and experimentally demonstrated. The main structure of this twist sensor is a torsion perturbation point cascaded with single mode-multimode-single mode (SMS) fiber structure. The experimental results show that the twist sensor has ability to distinguish the twist direction with sensitivities of 9.5 pm/° and 34.7 pm/° at the chosen dips in the range from −100° (CCW) to 140° (CW). Furthermore, the temperature response characteristic of the sensor is also researched through experiment. Temperature sensitivities of 71.8 pm/°C and 65.2 pm/°C can be obtained at the same dips in the range from 20 °C to 75 °C. In addition, the temperature's influence can be compensated with post-measurement calculation through the cross-matrix. The theoretical resolutions of twist and temperature simultaneous measurement are ±0.084° and ±0.32 °C, respectively. [ABSTRACT FROM AUTHOR]