Blue Edge Research Articles

Slow photon photocatalytic enhancement of H2 production in TaON inverse opal photonic crystals

In this study, tantalum oxynitride inverse opal (TaON IO) photonic crystals with different macropore diameters (D) were synthesized in a two-step process involving colloidal crystal templating and thermal nitridation, then applied as visible light-driven photocatalysts for hydrogen production. The TaON inverse opals showed photonic band gaps (PBGs) at visible wavelengths, with the PBG position redshifting as the diameter of the macropores increased in accordance with a modified Bragg's law expression. By aligning the electronic absorption edge of TaON (Eg ∼ 2.4 eV) with the blue edge (short-wavelength side) or red edge (long-wavelength side) of the PBGs, slow photon enhancement of photocatalytic H2 generation was realized. H2 production tests conducted in 10 vol% methanol containing H₂PtCl6 under Xe lamp irradiation (150 W) showed that the hydrogen production rate was enhanced by ∼1.3–1.4 times when the TaON absorption edge (∼510 nm) aligned with blue edge of the PBG (0.3421 mmol g−1 h−1) or the red edge of the PBG (0.3254 mmol g−1 h−1) in the inverse opals. The red edge enhancement was due to increased light absorption and charge carrier generation in TaON, whereas the blue edge effect was likely due to suppression of electron-hole pair recombination. Results demonstrate that photonic crystal engineering to exploit slow photon effects is a viable approach for boosting photocatalytic hydrogen production rates.

Inverse Opal Photonic Hydrogels for Blue‐Edge Slow Photon‐Enhanced Photodynamic Antibacterial Therapy

AbstractPhotodynamic therapy is promising for combating bacteria by reactive oxygen species. However, the therapeutic efficiency of photodynamic antibacterial therapy (PDAT) is largely hindered by limited photon absorption and the low quantum yield of photosensitizers. Herein, a novel light‐harvesting platform is designed by decorating photosensitizer chlorine e6 (Ce6) into an inverse opal photonic hydrogel (Ce6/IOPG) framework for efficient light utilization to enhance PDAT. It is shown that the generating efficiency of singlet oxygen (1O2) can be tuned by the relative positions of the photonic bandgap (PBG) of IOPG and the absorption band of Ce6. The coupling of the slow photon effect with the efficient dispersion of Ce6 allows for a maximum generation of 1O2 of approximately 69.5‐fold and markedly enhances PDAT activity upon low light irradiation when the blue edge of PBG overlaps with the absorption band of Ce6. Particularly, slow photons at the blue edge show advantages in improving 1O2 generation compared to those at the red edge. The variation in 1O2 generation by altering the incident angle of light provides direct evidence for the slow photon effect in Ce6/IOPG. This work provides insights into blue‐edge slow photons in photodynamic enhancement and offers an advisable design principle for efficient antibacterial therapy.

Photodissociation dynamics of methylamine in the blue edge of the A-band. II. The NH2 + CH3 channel.

The photodissociation dynamics leading to the C-N bond cleavage in methylamine (CH3NH2) are investigated upon photoexcitation in the blue edge of the first absorption A-band, in the 198-204nm range. Velocity map images of the generated methyl (CH3) fragment detected in specific vibrational modes, i.e., ν = 0, ν1 = 1, and ν2 = 1, through resonance enhanced multiphoton ionization, are presented along with the corresponding translational energy distributions and the angular analysis. The experimental results are complemented by high-level abinitio calculations of potential energy curves as a function of the C-N bond distance. While a similar single Boltzmann-type contribution is observed in all the translational energy distributions measured, the speed-dependent anisotropy parameter obtained through the angular analysis reveals the presence of two different mechanisms. Prompt dissociation through the conical intersection between the Ã1A' first excited state and the ground state located in the exit channel is, indeed, revealed as a minor channel. In contrast, slow dissociation on the ground state, presumably from frustrated N-H bond cleavage trajectories, constitutes the major reaction pathway leading to the methyl formation.

Estimation Model of Rice Aboveground Dry Biomass Based on the Machine Learning and Hyperspectral Characteristic Parameters of the Canopy

Accurately estimating aboveground dry biomass (ADB) is crucial. The ADB of rice has primarily been estimated using vegetation indices with several discrete bands; nevertheless, these indices cannot take advantage of continuous bands available with hyperspectral remote sensing. This study analyzed the quantitative relationship between canopy hyperspectral characteristic parameters (HCPs) and the ADB of rice. Twenty HCPs were used, including red edge area (SDr), blue edge area (SDb), and others. The variable-screening methods involved stepwise regression (SR), a regression coefficient (RC), variable importance in projection (vip), and random forest (RF). Stepwise and partial least squares regression methods were employed with traditional linear regression as well as machine learning methods including random forest (RF), a support vector machine (SVM), a BP artificial neural network (BPNN), and an extreme learning machine. Whole- and screening-variable models were constructed to estimate rice ADB at jointing, booting, heading, and maturing stages and across growth stages. Screening-variable models include SVM models based on SR (SVM-sr), RF models based on vip (RF-vip), and others. The results show that the HCPs had a significant correlation with ADB containing elements in the red edge region, namely SDr, SDr/SDb, and (SDr − SDb)/(SDr + SDb) at each growth stage. In addition, the screening performance of vip and SR was better than that of RC and RF, and fewer variables were screened. Moreover, the HCPs of the red edge region were screened using different screening methods at each growth stage. Among them, SDr/SDb and (SDr − SDb)/(SDr + SDb) appeared frequently, indicating they are important. Furthermore, at each growth stage, ADB could be well-estimated using diverse models with the RF modeling method based on vip screening variables found to be the best modeling method for ADB estimation; the independent variables of the RF-vip model involved the (SDr − SDb)/(SDr + SDb) at each growth stage.

Effect of Ge concentration on optical properties of films synthesized by vacuum-thermal evaporation of glassy Ge–Se alloys

Four non-crystalline GexSe100−x (x = 15−25 at. %) films were obtained by vacuum-thermal deposition of glassy Ge–Se alloys. With the use of spectroscopic ellipsometry, it was determined that the films are semiconductors with indirect band gap energy Eg = 2.0−2.07 eV. An anomalous dispersion of the refractive index n (λ) with nmax at λmax depending on x was revealed in the films at λ = 240−500 nm. It was established that as the concentration of Ge decreases, nmax increases, and λmax red shifts. Based on the Wemple-DiDomenico model, the nonlinear coefficients χ(3) and n2 characterizing the synthesized films were calculated as a function of x. The highest χ(3) and n2 values are achieved in the films at x = 15 at. %. The results obtained can be used for the development and creation of Ge–Se optical filters with an adjustable blue absorption band edge.

Photodissociation dynamics of methylamine in the blue edge of the A-band. I. The H-atom elimination channel.

The photodissociation dynamics of methylamine (CH3NH2) upon excitation in the blue edge of the first absorption A-band, in the 198-203nm range, are investigated by means of nanosecond pump-probe laser pulses and velocity map imaging combined with H(2S)-atom detection through resonance enhanced multiphoton ionization. The images and corresponding translational energy distributions for the H-atoms produced show three different contributions associated with three reaction pathways. The experimental results are complemented by high-level abinitio calculations. The potential energy curves computed as a function of the N-H and C-H bond distances allow us to draw a picture of the different mechanisms. Major dissociation occurs through N-H bond cleavage and it is triggered by an initial geometrical change, i.e., from a pyramidal configuration of the C-NH2 with respect to the N atom to a planar geometry. The molecule is then driven into a conical intersection (CI) seam where three outcomes can take place: first, threshold dissociation into the second dissociation limit, associated with the formation of CH3NH(Ã), is observed; second, direct dissociation after passage through the CI leading to the formation of ground state products; and third, internal conversion into the ground state well in advance to dissociation. While the two last pathways were previously reported at a variety of wavelengths in the 203-240nm range, the former had not been observed before to the best of our knowledge. The role of the CI and the presence of an exit barrier in the excited state, which modify the dynamics leading the two last mechanisms, are discussed considering the different excitation energies used.

Action spectrum for reorientations in bacteriorhodopsin of purple membrane in suspension

In the present study, the dependency of purple membrane (PM) dielectric responses on the wavelength of light in the range 380–750 nm has showed meaningful changes about the rotation of PM in suspension and about the rotation of bacteriorhodopsin (bR) trimer inside PM, as well. The action spectrum of PM random walk substantiates the existence of two states of bR. One of them (blue edge-state) lies at the blue edge and the other (red edge-state) at the red edge of the visible absorption of bR. The results might bear on correlation of these bands to some bR photocycle intermediates or bR photoproducts. The results implicate the protein–chromophore interactions that eventually underlie protein–lipid interactions. Disrupting the protein–lipid contact during the illumination with light of wavelength in ranges of (410–470 nm) and (610–720 nm) has resulted in emergence of distinct dielectric dispersion at 0.06–0.08 MHz which is comparable to the size of bR trimer or monomer.The work reports on the chromatic adaptation of bR in view of the dielectric spectral parameters of PM. It aimed to explore a correlation seemingly found between the light wavelength and the relaxations of bR trimer inside PM. Changes in rotational diffusion of bR trimer upon blue and red light illumination can influence the three dimensional data storage based on bR, which may implicate bR in bioelectronics.

Discrimination between protoporphyrinogen oxidase–inhibiting herbicide-resistant and herbicide-susceptible redroot pigweed (Amaranthus retroflexus) with spectral reflectance

AbstractThe current assays to confirm herbicide resistance can be time- and labor-intensive (dose–response) or require a skill set/technical equipment (genetic sequencing). Stakeholders could benefit from a rapid assay to confirm herbicide-resistant weeds to ensure sustainable crop production. Because protoporphyrinogen oxidase (PPO)-inhibiting herbicides rapidly interfere with chlorophyll production/integrity; we propose a new, rapid assay utilizing spectral reflectance to confirm resistance. Leaf disks were excised from two PPO-inhibiting herbicide-resistant (target-site [TSR] and non–target site [NTSR]) and herbicide-susceptible redroot pigweed (Amaranthus retroflexus L.) populations and placed into a 24-well plate containing different concentrations (0 to 10 mM) of fomesafen for 48 h. A multispectral sensor captured images from the red (668 nm), green (560 nm), blue (475 nm), and red edge (717 nm) wavebands after a 48-h incubation period. The green leaf index (GLI) was utilized to determine spectral reflectance ratios of the treated leaf disks. Clear differences of spectral reflectance were observed in the red edge waveband for all populations treated with the 10 mM concentration in the dose–response assays. Differences of spectral reflectance were observed for the NTSR population compared with the TSR and susceptible populations treated with the 10 mM concentration in the green waveband and the GLI in the dose–response assay. Leaf disks from the aforementioned A. retroflexus populations and two additional susceptible populations were subjected to a similar assay with the discriminating concentration (10 mM). Spectral reflectance was different between the PPO-inhibiting herbicide-resistant and herbicide-susceptible populations in the red, blue, and green wavebands. Spectral reflectance was not distinctive between the populations in the red edge waveband and the GLI. The results provide a basis for rapidly (∼48 h) detecting PPO-inhibiting herbicide-resistant A. retroflexus via spectral reflectance. Discrimination between TSR and NTSR populations was possible only in the dose–response assay, but the assay still has utility in distinguishing herbicide-resistant plants from herbicide-susceptible plants.

Evaluation of eight band SuperDove imagery for aquatic applications.

Planet's SuperDove constellation is evaluated for remote sensing of water targets. SuperDoves are small satellites with on board eight band PlanetScope imagers that add four new bands compared to the previous generations of Doves. The Yellow (612 nm) and Red Edge (707 nm) bands are of particular interest to aquatic applications, for example in aiding the retrieval of pigment absorption. The dark spectrum fitting (DSF) algorithm is implemented in ACOLITE for processing of SuperDove data, and its outputs are compared to matchup data collected using an autonomous pan-and-tilt hyperspectral radiometer (PANTHYR) installed in the turbid waters of the Belgian Coastal Zone (BCZ). Results for 35 matchups from 32 unique SuperDove satellites indicate on average low differences with PANTHYR observations for the first seven bands (443-707 nm), with mean absolute relative differences (MARD) 15-20%. The mean average differences (MAD) are between -0.01 and 0 for the 492-666 nm bands, i.e. DSF results show a negative bias, while the Coastal Blue (444 nm) and Red Edge (707 nm) show a small positive bias (MAD 0.004 and 0.002). The NIR band (866 nm) shows a larger positive bias (MAD 0.01), and larger relative differences (MARD 60%). Root mean squared differences (RMSD) are rather flat at around 0.01 with peaks in the bands with highest water reflectance of around 0.015. The surface reflectance products as provided by Planet (PSR) show a similar average performance to DSF, with slightly larger and mostly positive biases, except in both Green bands, where the MAD is close to 0. MARD in the two Green bands is a bit lower for PSR (9.5-10.6%) compared to DSF (9.9-13.0%). Higher scatter is found for the PSR (RMSD 0.015-0.020), with some matchups showing large, spectrally mostly flat differences, likely due to the external aerosol optical depth (τa) inputs not being representative for these particular images. Chlorophyll a absorption (aChl) is retrieved from PANTHYR measurements, and the PANTHYR data are used to calibrate aChl retrieval algorithms for SuperDove in the BCZ. Various Red band indices (RBI) and two neural networks are evaluated for aChl estimation. The best performing RBI algorithm, i.e. the Red band difference (RBD), showed a MARD of 34% for DSF and 25% for PSR with positive biases of 0.11 and 0.03 m-1 respectively for 24 PANTHYR aChl matchups. The difference in RBD performance between DSF and PSR can be largely explained by their respective average biases in the Red and Red Edge bands, which are opposite signs for DSF (negative bias in the red), and positive for both bands for PSR. Mapping of turbid water aChl and hence chlorophyll a concentration (C) using SuperDove is demonstrated for coastal bloom imagery, showing how SuperDove data can supplement monitoring programmes.

High-power supercontinuum lasers with a flat blue spectrum through pump modulation: a numerical study.

We numerically investigate high-power, modulational instability-based supercontinuum sources. Such sources have spectra that reach the infrared material absorption edge and as a result the spectrum has a strong narrow blue peak (dispersive wave group velocity matched to solitons at the infrared loss edge) followed by a significant dip in the neighboring longer-wavelength region. In a wide range of applications one prefers a broader and more flat blue part within a certain minimum and maximum power spectral density. From the perspective of fiber degradation it would be desirable to achieve this at reduced pump peak powers. We show that it is possible to improve the flatness by more than a factor of 3 by modulating the input peak power, although this comes at the expense of slightly higher relative intensity noise. Specifically, we consider a standard 6.6 W, 80 MHz supercontinuum source with a 455 nm blue edge, which uses 7 ps pump pulses. We then modulate its peak power to generate a pump pulse train having two and three different sub-pulses.

Multispectral UAV data for detection of weeds in a citrus farm using machine learning and Google Earth Engine: Case study of Morocco

Accurate and timely weed mapping between and within trees is considered one of the major challenges in the site-specific weed management systems. This research presents the first cloud computing approach based on the incorporation of multispectral Unmanned Aerial Vehicle (UAV) imagery in the Google Earth Engine (GEE) programming environment with the aim of improving the mapping of weed patches between and within trees in a citrus farm. For this purpose, the UAV multispectral bands (red, green, blue, near infrared, and red edge), as well as the estimated vegetation height from the UAV Digital Elevation Model (DEM) were analysed in terms of tree and weed discrimination and used as input into Random Forest (RF) and k-nearest neighbors (KNN) machine learning algorithms. From the DEM, the Digital Terrain Model (DTM) was estimated using the Inverse Distance Weighted Interpolation (IDW) of the elevation values of dense points on the soil. The plant height was derived by subtracting the DTM from the DEM, resulting in the Canopy Height Model (CHM). The experimental results show that: (i) the combination of spectral bands and the CHM can classify both trees and weeds with an overall accuracy reached 96.87%; (ii) the RF classifier was more robust compared to KNN in the classification performance; (iii) when compared to the use of UAV spectral bands, the addition of the CHM can improve the accuracy of crop classification by 13.36% (KNN) and 1.79% (RF). Furthermore, the integration of UAV imagery in the GEE was highly efficient in terms of automation of the UAV imagery processing.

High-throughput phenotyping salt tolerance in JUNCAOs by combining prompt chlorophyll a fluorescence with hyperspectral spectroscopy

The planting of salt-tolerant plants is regarded as the one of important measurements to improve the saline–alkali lands. The outstanding biological properties of JUNCAOs have made them candidates to improve and utilize saline–alkali lands. At present, little attention has been paid to developing a non-destructive and high throughput approach to evaluate the salt tolerance of JUNCAO. To close the gaps, three typical JUNCAOs (A.donax. No.1, A.donax. No.5 and A.donax. No.10) were evaluated by combining prompt chlorophyll a fluorescence (ChlF) with hyperspectral spectroscopy (HS). The results showed that salt stress reduced relative stem growth, water content, and total chlorophyll content but enhanced the malondialdehyde (MDA) content. It caused a significant change in chlorophyll a fluorescence kinetics with an appearance of L-, K- and J-band, implying damaging energetic connectivity between PSII units, uncoupling of the oxygen evolving complex (OEC) and inhibition of the QA−reoxidation. The negative impact of salt stress on JUNCAOs increased with the increasing level of salt concentration. Effect on spectral reflectance in the in the visible region with shifts on red edge position (REP) and blue edge position (BEP) to shorter wavelength was also found in salt stress plants. Combining principal component analysis (PCA) with the membership function method based on spectral indices and JIP-test parameters could well screen JUNCAOs salt tolerant ability with the highest for A.donax. NO.10 but lowest for A.donax. NO.1, which was the same as that of using conventional approach. The results demonstrate that prompt ChlF coupling with HS could provide potentials for non-invasively and high-throughput phenotyping salt tolerance in JUNCAOs.

Reaction Dynamics in the Chrimson Channelrhodopsin: Observation of Product-State Evolution and Slow Diffusive Protein Motions.

Chrimson is a red-light absorbing channelrhodopsin useful for deep-tissue optogenetics applications. Here, we present the Chrimson reaction dynamics from femtoseconds to seconds, analyzed with target analysis methods to disentangle spectrally and temporally overlapping excited- and product-state dynamics. We found multiple phases ranging from ≈100 fs to ≈20 ps in the excited-state decay, where spectral features overlapping with stimulated emission components were assigned to early dynamics of K-like species on a 10 ps time scale. Selective excitation at the maximum or the blue edge of the absorption spectrum resulted in spectrally distinct but kinetically similar excited-state and product-state species, which gradually became indistinguishable on the μs to 100 μs time scales. Hence, by removing specific protein conformations within an inhomogeneously broadened ensemble, we resolved slow protein backbone and amino acid side-chain motions in the dark that underlie inhomogeneous broadening, demonstrating that the latter represents a dynamic interconversion between protein substates.

Normality Effect on Characterization of Chemically Synthesized ZnO Nanoparticles

The current research activities that focus on the preparation of ZnO nanostructure material and their physical and optical properties characterization. ZnO nanoparticles were synthesized using sol-gel chemical precipitation technique with zinc acetate and sodium hydroxide in distil water as a starting materials. Stock solutions of zinc acetate and sodium hydroxide at different normality (0.10N, 0.25N, 0.50N, 0.75N and 1N) were used for preparation of ZnO‘s. Synthesized sample of ZnO precipitate was dried at ordinary temperature for 12 hours and calcinied at 1000C for 2 hours and were physically characterized by using XRD (X-ray diffraction), SEM (scanning electron microscope) and FTIR spectroscopy. The XRD spectra exhibit wurtzite hexagonal crystal structure. The particle size statistically estimated from XRD data show that the ZnO samples consist of nanosize particles. The optical properties of ZnO nanoparticles was studied by using UV-visible absorption and PL (photoluminescence ). The effect of normality of different precursors used in preparation of ZnO nanoparticles, on spectroscopic characterizations was investigated. UV-Visible spectra give blue luminescence near band edge. PL exhibits green luminescence that suggest surface defect due to oxygen vacancies effect in ZnO nanoparticles.

Empirical constraints for the instability strip from the analysis of LMC Cepheids

AbstractThe instability strip (IS) of classical Cepheids has been extensively studied theoretically. Comparison of the theoretical IS edges with those obtained empirically, using the most recent Cepheids catalogs available, can provide us with insights into the physical processes that determine the position of the IS boundaries. We investigate the empirical positions of the IS of the classical Cepheids in the Large Magellanic Cloud (LMC) using data of classical fundamental-mode and first-overtone LMC Cepheids from the OGLE-IV variable star catalog, together with a recent high-resolution reddening map from the literature. We studied their position on the Hertzsprung-Russell diagram and determined the IS borders by tracing the edges of the color distribution along the strip. We obtain the blue and red edges of the IS in V- and I-photometric bands, in addition to Teff and log L⊙. The results obtained show a break located at the Cepheids’ period of about 3 days, which was not reported before. This phenomenon is most likely explained by the depopulation of second and third crossing classical Cepheids in the faint part of the IS, since blue loops of evolutionary tracks in this mass range do not extend blueward enough to cross the IS at the LMC metallicity. Furthermore, our empirical borders show good agreement with theoretical ones published in the literature. This proves that our empirical IS is a useful tool to put constraints on theoretical models.

Light-Induced Self-Oscillations and Spoiling of the Bragg Resonance Due to Nonlinear Optical Propagation in Heliconical Cholesteric Liquid Crystals

In a recent paper, we have reported the results of a study of the nonlinear light propagation of a beam traveling along the helix direction of a heliconical cholesteric liquid crystal, showing that optical reorientation leads to instabilities in the optical transmission when the light wavelength is close to the Bragg resonance. Here we report a detailed study of this phenomenon, using Ambartsumian’s layer addition modified method to take into account the continuous modification of the wave field during propagation. We show that the whole transmission spectrum is modified by increasing the light intensity and point out that self-induced oscillations take place at lower intensities on the red side edge of the Bragg resonance while stable values of transmittivity are still observed on the blue side edge. A further increase in the intensity leads to oscillations of lower amplitude on the blue side while an irregular behavior of the transmission is achieved on the red side. At higher intensities, the Bragg resonance disappears and transmission becomes unstable for any light wavelength. A simple phenomenological model is proposed to account for the onset of the oscillations and the asymmetry of the behavior at the opposite side of the Bragg resonance. We also point out that the static electric field is a driving parameter to switch from stable to oscillatory to irregular behavior in the transmittivity at a given light wavelength.

Self-Efficacy and Stigma in Adults with Sickle Cell Disease: An Import Study Analysis

Background: Sickle cell disease (SCD) causes significant morbidity across the lifespan. Finding ways to manage the most common and debilitating complications, including chronic pain, is of utmost importance to restoring quality of life and decreasing health care utilization. Several studies have estimated that chronic daily pain affects 30-50% of adult patients with SCD (1) (2). Furthermore, in both pediatric and adult patients with SCD, those with more frequent chronic pain report more frequent depressive symptoms, more frequent hospital admission, and more significant functional disability (2) (3). Discrimination is associated with poor mental health and decreased self-efficacy. The Improving Patient Outcomes with Respect and Trust (IMPORT) study demonstrates that patients with SCD report higher rates of race-based discrimination compared to other Black patients (10). Disease-based discrimination was associated with more significant self-reported pain. Because virtually all patients with SCD identify as Black or other racial and ethnic minorities, it is important to understand how discrimination as experiences of bias, racism, and disease-related stigma interact to affect health and functioning. This study explores the relationship between SCD stigma, self-efficacy, and other factors in the IMPORT data set. Methods: We first analyzed the relationship between variables including trust in doctor (trust1), institutional trust (trust2), and depressive symptoms (depress) with a network analysis (NA). The weighted partial correlation network structure of these factors and self-care (care), self-efficacy (effic), bias, interpersonal communication-compassionate(ipc_c) and discrimination (ipc_d), pain attitudes (spa) and pain catastrophizing score (pcs) among SCD patients is shown in the figure (n= 245). The stronger a connection between two nodes, the thicker and more saturated the line. Positive and negative connections are denoted by blue and red edges, respectively. After identifying significant relationships by NA, Additional analysis explored the effect of provider and institution trust, perception of bias and stigma on pain catastrophizing score, self-care, and self-efficacy. We fit multivariable linear regression models of the three outcomes (pain catastrophizing score, self-care, and self-efficacy) with trust, perception, and stigma as covariates. We further adjusted for age, sex, income category, and education level in the regression models. Results:Figure 1- Network analysisTable 1- Multivariate Regression Model Trust in doctors, stigma and education level were significantly associated with the PCS score. Each unit increase in stigma was associated with increase in the PCS score by 1 (p<0.001). The higher the education level, the lower the PCS. Increase in trust in doctors was associated with increased PCS score. Trust in institutions and age were significantly associated with self-care behaviors. Higher trust in institution is associated with higher self-care. Also, older age is associated with increased self-care. Trust in institution and education level are positively associated with self-efficacy. Stigma is negatively associated with self-efficacy. Discussion: This novel analysis of self-efficacy and experiences of stigma in adults with SCD reveals a significant association between sigma and self-efficacy. Additionally, our network analysis demonstrates the centrality of self-efficacy and pain catastrophizing, 2 promising targets for future intervention. The centrality of compassionate interpersonal communication also underscores the importance of the bidirectional relationship between patients and clinicians. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

On weight-symmetric 3-coloured digraphs

We consider particular weighted directed graphs with edges having colour red, blue or green such that each red edge has weight 1, each blue edge has weight −1 and each green edge has weight i (the imaginary unit). Such a directed graph is called a 3-coloured digraph (for short, a 3-CD). Every mixed graph and every signed graph can be interpreted as a 3-CD. We first study some structural properties of 3-CDs by means of the eigenvalues of the adjacency matrix. In particular, we give spectral criteria for singularity of such digraphs. Second, we consider weight-symmetric 3-CDs, i.e. those 3-CDs that are switching isomorphic to their negation. It follows that the class of weight-symmetric 3-CDs is included in the class of 3-CDs whose spectrum is symmetric (with respect to the origin). We give some basic properties and several constructions of weight-symmetric 3-CDs and establish constructions of 3-CDs which have symmetric spectrum but are not weight-symmetric.

Construction of spectral index based on multi-angle spectral data for estimating cotton leaf nitrogen concentration

Rapid, non-destructive, and accurate monitoring is of great significance for determining crop nitrogen status and improving nitrogen fertilizer management. Multiple angle spectral data contains comprehensive and abundant information of crop canopy. In this study, the spectral data of cotton leaves at different leaf inclination angles (0°, 15°, 30°, and 45°) were collected using hyperspectral imaging technology at the seedling stage, bud stage, flowering stage, and boll-forming stage of cotton from 2018 to 2020, and indoor determination of cotton leaf nitrogen concentration (LNC) was conducted simultaneously. Based on the spectral features in blue edge and green edge regions, a new multi-angle blue-edge absorption vegetation index (MBEAVI) was constructed. Then, the MBEAVI and 16 vegetation indices (VI) reported in previous studies were constructed using single-angle and multi-angle spectral data of 2018 (320 sets) and 2019 (320 sets), and the inter-annual test was conducted with the data of 2020 (320 sets). The results showed that the VI models based on multi-angle spectral data (multi-angle models) had higher accuracy than the models based on single-angle spectral data (single-angle models). Among single-angle models, the model based on the optimized red edge absorption index (OREA) had the highest accuracy in cotton LNC estimation, with R2 of 0.735. However, the accuracy of multi-angle model, MBEAVI, was significantly higher than that of the OREA model, with R2 of 0.812. Besides, the R2 of the MBEAVI model reached 0.789 in the inter-annual test. Therefore, the MBEAVI model based on multi-angle spectral data had a higher accuracy and stability in predicting cotton LNC compared with the single-angle models. This study provides theoretical support for improving the accuracy of monitoring cotton nitrogen status by using multi-angle hyperspectral data.

Demonstration of C-Plane InGaN-Based Blue Laser Diodes Grown on a Strain-Relaxed Template

Electrically driven c-plane InGaN-based blue edge emitting laser diodes on a strain-relaxed template (SRT) are successfully demonstrated. The relaxation degree of the InGaN buffer was 26.6%, and the root mean square (RMS) roughness of the surface morphology was 0.65 nm. The laser diodes (LDs) on the SRT laser at 459 nm had a threshold current density of 52 kA/cm2 under the room temperature pulsed operation. The internal loss of the LDs on the SRT was 30–35 cm−1. Regardless of the high threshold current density, this is the first demonstrated laser diode using the strain-relaxed method on c-plane GaN.