Narrow Width Research Articles

Directive giant upconversion by supercritical bound states in the continuum

Photonic bound states in the continuum (BICs), embedded in the spectrum of free-space waves1,2 with diverging radiative quality factor, are topologically non-trivial dark modes in open-cavity resonators that have enabled important advances in photonics3,4. However, it is particularly challenging to achieve maximum near-field enhancement, as this requires matching radiative and non-radiative losses. Here we propose the concept of supercritical coupling, drawing inspiration from electromagnetically induced transparency in near-field coupled resonances close to the Friedrich–Wintgen condition2. Supercritical coupling occurs when the near-field coupling between dark and bright modes compensates for the negligible direct far-field coupling with the dark mode. This enables a quasi-BIC field to reach maximum enhancement imposed by non-radiative loss, even when the radiative quality factor is divergent. Our experimental design consists of a photonic-crystal nanoslab covered with upconversion nanoparticles. Near-field coupling is finely tuned at the nanostructure edge, in which a coherent upconversion luminescence enhanced by eight orders of magnitude is observed. The emission shows negligible divergence, narrow width at the microscale and controllable directivity through input focusing and polarization. This approach is relevant to various physical processes, with potential applications for light-source development, energy harvesting and photochemical catalysis.

Simulation comparison of modified confidence intervals based on robust estimators for coefficient of variation: skewed distributions case with real applications

In this article, we propose confidence intervals for the population coefficient of variation based on some robust estimators such as trimmed mean, winsorized mean, Hodges-Lehmann estimator and trimean. The proposed confidence intervals and their bootstrap versions were compared with the existing confidence intervals for the population coefficient of variation. The performances of the proposed confidence intervals were evaluated via a Monte-Carlo simulation study by considering the coverage probability, average width, standard deviation of widths, and coefficient of variation of widths as comparison criteria. The proposed confidence intervals performed well in terms of coverage probability on symmetrical distributions. In the case of skewed distributions, they were closer to the nominal confidence level and had narrower widths than the others. As a result, we proposed to use confidence intervals based on the Hodges-Lehmann estimator and winsorized mean for small sample sizes ( n = 10 and 15 ) and larger sample sizes for skewed distributions, respectively. The real-life datasets were analyzed to support the simulation results and confirm the practical applications of the proposed confidence intervals.

Solvent Suppression in Pure Shift NMR.

Intense solvent signals in 1H solution-state NMR experiments typically cause severe distortion of spectra and mask nearby solute signals. It is often infeasible or undesirable to replace a solvent with its perdeuterated form, for example, when analyzing formulations in situ, when exchangeable protons are present, or for practical reasons. Solvent signal suppression techniques are therefore required. WATERGATE methods are well-known to provide good solvent suppression while enabling retention of signals undergoing chemical exchange with the solvent signal. Spectra of mixtures, such as pharmaceutical formulations, are often complicated by signal overlap, high dynamic range, the narrow spectral width of 1H NMR, and signal multiplicity. Here, we show that by combining WATERGATE solvent suppression with pure shift NMR, ultrahigh-resolution 1H NMR spectra can be acquired while suppressing intense solvent signals and retaining exchangeable 1H signals. The new method is demonstrated in the analysis of cyanocobalamin, a vitamin B12 supplement, and of an eye-drop formulation of atropine.

Switching characteristics of MgO-based MTJ with intermediate state

The resistance change of magnetic tunnel junctions (MTJs) is used to store digital information in spin-transfer-torque magnetoresistive random-access memory. In some MTJs, intermediate (IM) states occur between two stable resistance states just after the application of a switching pulse. In this study, the effect of IM states on switching is investigated. IM states increase the switching voltage, and their probability is significantly high at a narrow pulse width. For no-error switching, MTJs with IM states require higher voltages and wider pulse widths compared with MTJs without IM states. A 300 nm MTJ has multiple IM states, whereas a 120 nm MTJ has only one IM state. Overall, a large MTJ’s free layer has multiple regions with different switching characteristics, and switching occurs stepwise through IM states.

Perovskite Nanocrystals: Superior Luminogens for Food Quality Detection Analysis.

With the global limited food resources receiving grievous damage from frequent climate changes and ascending global food demand resulting from increasing population growth, perovskite nanocrystals with distinctive photoelectric properties have emerged as attractive and prospective luminogens for the exploitation of rapid, easy operation, low cost, highly accurate, excellently sensitive, and good selective biosensors to detect foodborne hazards in food practices. Perovskite nanocrystals have demonstrated supreme advantages in luminescent biosensing for food products due to their high photoluminescence (PL) quantum yield, narrow full width at half-maximum PL, tunable PL in the entire visible spectrum, easy preparation, and various modification strategies compared with conventional semiconductors. Herein, we have carried out a comprehensive discussion concerning perovskite nanocrystals as luminogens in the application of high-performance biosensing of foodborne hazards for food products, including a brief introduction of perovskite nanocrystals, perovskite nanocrystal-based biosensors, and their application in different categories of food products. Finally, the challenges and opportunities faced by perovskite nanocrystals as superior luminogens were proposed to promote their practicality in the future food supply.

Near‐Unity Quantum Yield ZnSeTe Quantum Dots Enabled by Controlling Shell Growth for Efficient Deep‐Blue Light‐Emitting Diodes

AbstractCore–shell structural ZnSeTe/ZnSe/ZnS quantum dots (QDs) have attracted great attention for advanced illumination and displays because of their environmentally friendly composition, but still suffering from poor photoluminescence (PL) and electroluminescence (EL) performance due to severe non‐radiative charge recombination. Herein, a stepwise injection shell growth process to manipulate the monomer concentration and ensure adequate growth interval is devised, which enables the controllable uniform epitaxial growth of ZnSe and ZnS shells on the ZnSeTe core, thus relieving the lattice distortion and defects to greatly suppress the non‐radiative charge recombination. The ZnSeTe/ZnSe/ZnS QDs presented deep‐blue emission at 448 nm with narrow full width at half maximum (FWHM, 23 nm), and near‐unity PL quantum yield (PLQY, ≈100%) The light‐emitting diodes (LEDs) based on the QDs exhibited a high external quantum efficiency (EQE) of 10.9%, a maximum brightness of 10240 cd cm−2, and a high current efficiency of 7.9 cd A−1, demonstrating a good performance for deep blue QDs LEDs (QLEDs) This shell growth strategy will be an effective approach to achieving efficient QDs and QLEDs.

High-Efficiency Blue-Emitting Mn-Ligand passivated CsPbBr3 nanoplatelets

Perovskite nanoplatelets (NPLs), as a promising material to achieve pure blue emission, have attracted significant attention in high gamut displays. However, the high surface-to-volume ratio and the loosely connected ligands of NPLs make them susceptible to degradation from light, air and heat. As a result, NPLs often exhibit low photoluminescence (PL) intensity and instability. Here, an Mn-ligand passivation strategy is proposed, in which Mn-doped DMAPbBr3 is used as a precursor. During the perovskite transformation, Mn2+ ions migrate from the lattice of DMAPbBr3 to the surface of CsPbBr3 NPLs, which have strong binding forces with ligands. The final products Mn-CsPbBr3 (M−CPB) NPLs are then acquired by the ligand-induced ripening growth process, which not only exhibit pure blue emission with narrow full width at half maximum (FWHM), but also possess near-unity PL quantum yields (QYs). Besides, M−CPB NPLs show excellent stability due to the strong Mn-ligand passivation layer. Based on the new growth mechanism discovery, the reaction time can be shortened to several minutes by heating. The innovative growth model proposed in this work will provide a paradigm for designing and optimizing future synthesis schemes.

Tetradentate Pt(II) Complexes with Bulky Carbazole Moieties for High-Efficiency and Narrow-Emitting Blue Organic Light-Emitting Devices.

Blue tetradentate Pt(II) complexes, Pt-tBuCz and Pt-dipCz, are synthesized by introducing carbazoles with bulky substituents for improving the rigidity and inhibiting intermolecular interactions of phosphorescent emitter. tert-Butyl and 2,6-diisopropylphenyl groups are substituted as the blocking groups at 3 position of the carbazole in Pt-tBuCz and Pt-dipCz, respectively. These new phosphorescent emitters exhibit a narrow full width at half maximum (FWHM) and a high horizontal emitting dipole orientation ratio. Pt-dipCz demonstrates a small FWHM of 24nm, a high emitting dipole orientation ratio of 81%, and a high photoluminescence quantum yield value of 94%. As a result, the Pt-tBuCz and Pt-dipCz devices exhibited external quantum efficiencies (EQEs) of 23.7% and 25.0% with small FWHMs of 25 and 22nm, respectively. For the Pt-dipCz device, the small FWHM and high EQE of >20% are maintained even at a doping concentration of 20 wt%. Furthermore, phosphor-sensitized organic light-emitting diodes fabricated using Pt-dipCz as a sensitizer achieved a high EQE of 31.4% with an FWHM of 18nm. This result indicates that the 2,6-diisopropylphenyl group is a effective blocking group for Pt(II) complexes to develop highly efficient, color stable, doping concentration resistant, and efficiently sensitizing blue phosphors.

Development of friction stir welding method using a tilted spherical tool

The feasibility of friction stir welding (FSW) with a simple spherical tool, which has neither a shoulder nor a probe, was studied. The spherical tool allows for localised welding with narrow weld widths and extended tool life but tends to generate flashes and weld thinning. The material flow around the spherical tool during FSW of the aluminium alloys was observed in detail, and the flash generation behaviour was discussed. As a result, a new FSW method in which a spherical tool tilted to the retreating side (RS) was developed, and by expanding the flow path of the leading surface on the RS, the flow of hot material was controlled to reduce flash and smooth the weld surface.

Multifaceted effects on even-skipped transcriptional dynamics upon Krüppel dosage changes.

Although fluctuations in transcription factor (TF) dosage are often well tolerated, TF dosage modulation can change the target gene expression dynamics and result in significant non-lethal developmental phenotypes. Using MS2/MCP-mediated quantitative live imaging in early Drosophila embryos, we analyzed how changing levels of the gap gene Krüppel (Kr) affects transcriptional dynamics of the pair-rule gene even-skipped (eve). Halving the Kr dosage leads to a transient posterior expansion of the eve stripe 2 and an anterior shift of stripe 5. Surprisingly, the most significant changes are observed in eve stripes 3 and 4, the enhancers of which do not contain Kr-binding sites. In Kr heterozygous embryos, both stripes 3 and 4 display narrower widths, anteriorly shifted boundaries and reduced mRNA production levels. We show that Kr dosage indirectly affects stripe 3 and 4 dynamics by modulating other gap gene dynamics. We quantitatively correlate moderate body segment phenotypes of Kr heterozygotes with spatiotemporal changes in eve expression. Our results indicate that nonlinear relationships between TF dosage and phenotypes underlie direct TF-DNA and indirect TF-TF interactions.

Anatomical and morphometric studies on the axial skeleton of ostrich (Struthio camelus)

The present study showed a descriptive anatomical study of the parts of the axial skeleton in the ostrich (Struthio camelus) in addition to a morphometric study of each bone. We studied 7 male ostriches aged from 1 to 3 years with an average weight of 120.00 kg. The cranium exhibited two vast orbits supported by a sclerotic ring. Hyoid apparatus was fine delicate horseshoe-shaped and comprised Basihyale, Urohyale, and Cornu branchiale. Cornu branchiale were paired and long rod-shaped, consisting of a proximal bony part Ceratobranchiale and slightly curved distal cartilaginous process, the Epibranchiale located on either side of the hyoid apparatus. The whole vertebral column comprised 54 vertebrae, including 18 cervical vertebrae, 7 separated thoracic vertebrae, a synsacrum, and 9 separated caudal vertebrae. Atlas had a butterfly-shape with a narrow width and large vertebral foramen. Axis had a protruded dens with a rounded tip that arose from the cranial surface of the body for articulation with the Incisura fossae of atlas. Several Pneumatic foramina were found in the cervical vertebrae. The transverse foramen was found in all the cervical vertebrae except atlas. The ribs were nine pairs in number, the sternal ribs extended from the third to the seventh rib while the rest were asternal floating ribs. The sternum was a broad quadrilateral extensive bone, lacking the keel bone. It had dorsally several Pneumatic foramina.

Molecular dyad exhibiting strong multi‐resonance blue fluorescence

AbstractA multi‐resonance (MR) fluorophore exhibiting circularly polarized luminescence (CPL) holds a significant promise for enhancing the utility of organic light‐emitting devices. To meet this demand, we have devised molecular dyads having azaoxaborin MR emitters based on homochiral (R)‐ and (S)‐1,1′‐bi‐2‐naphthol. The synthesized 12,12′‐di‐tert‐butyl‐9,9′‐bi(8,8′‐dioxa‐4b,4′b‐diaza‐14b,14′b‐diborafluorantheno[1,2,3‐de]tetracene) products (TBNBOCz) exhibit strong blue fluorescence, with a remarkable 100% fluorescence quantum yield and an extremely narrow full width at half‐maximum of 22 nm. However, unexpectedly, TBNBOCz exhibits negligible electric circular dichroism and CPL activities. Chiroptical investigations into the reaction precursors reveals an occurrence of racemization in the borylation step. This result emphasizes the importance of understanding synthetic processes and their impact on the chiroptical properties.

Applications of Raman spectroscopy in the diagnosis and monitoring of neurodegenerative diseases.

Raman scattering is an inelastic light scattering that occurs in a manner reflective of the molecular vibrations of molecular structures and chemical conditions in a given sample of interest. Energy changes in the scattered light can be assessed to determine the vibration mode and associated molecular and chemical conditions within the sample, providing a molecular fingerprint suitable for sample identification and characterization. Raman spectroscopy represents a particularly promising approach to the molecular analysis of many diseases owing to clinical advantages including its instantaneous nature and associated high degree of stability, as well as its ability to yield signal outputs corresponding to a single molecule type without any interference from other molecules as a result of its narrow peak width. This technology is thus ideally suited to the simultaneous assessment of multiple analytes. Neurodegenerative diseases represent an increasingly significant threat to global public health owing to progressive population aging, imposing a severe physical and social burden on affected patients who tend to develop cognitive and/or motor deficits beginning between the ages of 50 and 70. Owing to a relatively limited understanding of the etiological basis for these diseases, treatments are lacking for the most common neurodegenerative diseases, which include Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis. The present review was formulated with the goal of briefly explaining the principle of Raman spectroscopy and discussing its potential applications in the diagnosis and evaluation of neurodegenerative diseases, with a particular emphasis on the research prospects of this novel technological platform.

Phase Engineering Reinforced Energy Transfer for High-Performance Blue Perovskite Light-Emitting Diodes.

Layered metal-halide perovskites, a category of self-assembled quantum wells, are of paramount importance in emerging photonic sources, such as lasers and light-emitting diodes (LEDs). Despite high trap density in two-dimensional (2D)perovskites, efficient non-radiative energy funneling from wide- to narrow-bandgap components, sustained by the Förster resonance energy transfer (FRET) mechanism, contributes to efficient luminescence by light or electrical injection. Herein, it is demonstrated that bandgap extension of layered perovskites to the blue-emitting regime will cause sluggish and inefficient FRET, stemming from the tiny spectral overlap between different phases. Motivated by the importance of blue LEDs and inefficient energy transfer in materials with phase polydispersity, wide-bandgap quasi-2D perovskites with narrow phase distribution, improved crystallinity, and the pure crystal orientation perpendicular to the charge transport layer are developed. Based on this emitter, high-performance blue perovskite LEDs with improved electroluminescence (EL) external quantum efficiency (EQE) of 7.9% at 478nm, a narrow full width at half-maximum (FWHM) of 22nm and a more stable EL spectra are achieved. These results provide an important insight into spectrally stable and efficient blue emitters and EL devices based on perovskites.

Exploiting Thin-Film Properties and Guided-Mode Resonance for Designing Ultrahigh-Figure-of-Merit Refractive Index Sensors

Guided-mode resonance (GMR) gratings have emerged as a promising sensing technology, with a growing number of applications in diverse fields. This study aimed to identify the optimal design parameters of a simple-to-fabricate and high-performance one-dimensional GMR grating. The structural parameters of the GMR grating were optimized, and a high-refractive-index thin film was simulated on the grating surface, resulting in efficient confinement of the electric field energy within the waveguide. Numerical simulations demonstrated that the optimized GMR grating exhibited remarkable sensitivity (252 nm/RIU) and an extremely narrow full width at half maximum (2 × 10−4 nm), resulting in an ultra-high figure of merit (839,666) at an incident angle of 50°. This performance is several orders of magnitude higher than that of conventional GMR sensors. To broaden the scope of the study and to make it more relevant to practical applications, simulations were also conducted at incident angles of 60° and 70°. This holistic approach sought to develop a comprehensive understanding of the performance of the GMR-based sensor under diverse operational conditions.

Enhancing hydrological model calibration through hybrid strategies in data‐scarce regions

AbstractCalibration of a hydrological model is a challenging task, especially in basins that are data scarce. With the incorporation of regional information and integration with satellite data, the parameters of hydrological models can be estimated for a basin with scant or no discharge records. The main objective of this study is to calibrate and validate a hydrological model based on a limited amount of in‐situ measured and remote sensing satellite datasets in a data‐sparse region. Multiple techniques were applied for the model calibration: (1) stage‐discharge curves using a spatial proximity approach, (2) Simplified Surface Energy Balance actual evapotranspiration, (3) river discharge using a physical similarity regionalization approach, and (4) a new hybrid approach by integrating remote sensing datasets along with field measured river bathymetry data to estimate the river discharge. To demonstrate the methodology, we employed the widely used Soil and Water Assessment Tool (SWAT) hydrological model in Manipur River Basin, India. The sensitivity, calibration, and validation of the SWAT model were carried out by using the Sequential Uncertainty Fitting Technique. During calibration, the coefficient of determination (R2) and the Kling Gupta Efficiency (KGE) were found to be in the range of 0.46–0.81 and 0.41–0.83, whereas during validation R2 and KGE were found to be in the range of 0.40–0.79 and 0.53–0.77 for the four different techniques. Among all the four techniques applied in this study, calibration based on (i) stage‐discharge curve using spatial proximity approach and (ii) new hybrid approach by integrating remote sensing datasets and river bathymetry were found as the better approaches as indicated by the statistical indices. The performance evaluation of the model through a new hybrid approach by integrating remote sensing and in‐situ measured datasets for rivers with narrow width represents a promising technique for use in a data sparse region.

Performance of Orbital Angular Momentum Communication for a Non-Uniformly Correlated High-Order Bessel–Gaussian Beam in a Turbulent Atmosphere

We derived the formula for the detection probability, signal-to-noise ratio (SNR), and average bit error rate (BER) for the signal orbital angular momentum (OAM) state carried via non-uniformly correlated high-order Bessel–Gaussian beam propagation in a turbulent atmosphere. The wavelength, receiver aperture, beam width, strength of the turbulent atmosphere, and topological charge effect on detection probability, SNR, and average BER of the signal OAM state were demonstrated numerically. The results show that the signal OAM state with low topological charge, a small receiver aperture, a narrow beam width, and a long wavelength can improve the performance of optical communications systems under conditions of weak atmospheric turbulence. Our results will be useful in long-distance free space optical (FSO) communications.

Validate robot-assisted total laparoscopic hysterectomy with four equally-spaced ports without an assistant port.

To evaluate the usefulness of robot-assisted total laparoscopic hysterectomy with four equally-spaced ports (RA-TLH/4e) without an assistant port. In RA-TLH/4e, four da Vinci ports were placed horizontally at a height of 4cm above the umbilicus with 8cm equal spacing. Poor development of the surgical field or difficult forceps manipulations were handled with the endoscope and forceps movement (port-hopping). Patient background, surgical outcomes, complications, port-hopping frequency were compared in three groups: RA-TLH/4e, RA-TLH with four unequally-spaced ports (RA-TLH/4u), and conventional RA-TLH with five ports (RA-TLH/5). There were no significant differences in patient background or surgical outcomes among the three groups except for age, preparation time, and hospital stay, and no cases of laparotomy conversion or serious complications. RA-TLH/4e had fewer port-hoppings than RA-TLH/4u. The minimum abdominal width showed a weak negative correlation with port-hopping frequency in RA-TLH/4u, but not in RA-TLH/4e. RA-TLH/4e allowed for a reduction in personnel and costs compared to RA-TLH/5. The equal placement of four ports allowed sufficient port spacing even for patients with narrow abdominal widths. In addition, the port-hopping technique was able to fully compensate for the lack of an assistant port. RA-TLH/4e is a highly useful technique that not only excels in safety but also reduces costs.

Phosphorus supply and floodplain design govern phosphorus reduction capacity in remediated agricultural streams

Abstract. Agricultural headwater streams are important pathways for diffuse sediment and nutrient losses, requiring mitigation strategies beyond in-field measures to intercept the transport of pollutants to downstream freshwater resources. As such, floodplains can be constructed along existing agricultural streams and ditches to improve fluvial stability and promote deposition of sediments and particulate phosphorus. In this study, we evaluated 10 remediated agricultural streams in Sweden for their capacity to reduce sediment and particulate phosphorus export and investigated the interplay between fluvial processes and phosphorus dynamics. Remediated streams with different floodplain designs (either on one side or both sides of the channel, with different width and elevation) were paired with upstream trapezoidal channels as controls. We used sedimentation plates to determine seasonal patterns in sediment deposition on channel beds and floodplains and monthly water quality monitoring. This was combined with continuous flow discharge measurements to examine suspended sediment and particulate phosphorus dynamics and reduction along reaches. Remediated streams with floodplains on both sides of the channel reduced particulate phosphorus concentrations and loads (−54 µg L−1, −0.21 kg ha−1 yr−1) along reaches, whereas increases occurred along streams with one-sided floodplains (27 µg L−1, 0.09 kg ha−1 yr−1) and control streams (46.6 µg L−1). Sediment deposition in remediated streams was five times higher on channel beds than on floodplains and there was no evident lateral distribution of sediments from channel to floodplains. There was no effect from sediment deposition on particulate phosphorus reduction, suggesting that bank stabilization was the key determinant for phosphorus mitigation in remediated streams, which can be realized with two-sided but not one-sided floodplains. Further, the overall narrow floodplain widths likely restricted reach-scale sediment deposition and its impact on P reductions. To fully understand remediated streams' potential for reductions in both nitrogen and different phosphorus species and to avoid pollution swapping effects, there is a need to further investigate how floodplain design can be optimized to achieve a holistic solution towards improved stream water quality.

Failure mechanisms of a silicon-based CMOS image sensor irradiated by a 1550 nm nanosecond laser.

Cameras, LiDAR, and radars are indispensable for accurate perception of the surrounding environment and autonomous driving. Failure mechanisms of silicon-based CMOS image sensor (CIS) irradiated by 1550 nm nanosecond laser were investigated systematically in this paper. The damages of CIS were divided into point damage, line damage, and cross damage according to different damage performances. The damage thresholds under different irradiation conditions (different repetition rates, pulse widths, and irradiation times) were explored. Large repetition rates and long irradiation times would induce more heat accumulation, more temperature increase, and a low point damage threshold. The damage threshold for a pulse with a narrow pulse width is lower than that for a pulse with a long pulse width. The damaged CIS was analyzed further by focused ion beam (FIB) and scanning electron microscope (SEM). The damage location in the internal CIS structure was analyzed and the overall failure process was summarized. The results we get could enrich the database of laser damage mechanisms and laser damage thresholds of CIS, which will provide meaningful guidance for the camera design technology and anti-laser reinforcement technology of optoelectronic devices.