Strong Absorption Research Articles

Influence of Absorber Contents and Temperatures on the Dielectric Properties and Microwave Absorbing Performances of C@TiC/SiO2 Composites

TiC provides a promising potential for high-temperature microwave absorbers due to its unique combination of thermal stability, high electrical conductivity, and robust structural integrity. C@TiC/SiO2 composites were successfully fabricated using a simple blending and cold-pressing method. The effects of C@TiC’s absorbent content and temperature on the dielectric and microwave absorption properties of C@TiC/SiO2 composites were investigated. The addition of C@TiC from 10 wt.% to 30 wt.% not only endows the composites with a higher dielectric constant and dielectric loss, but also with a greater high-temperature stability in terms of dielectric and microwave absorption properties. The composite with 30 wt.%C@TiC demonstrates a strong microwave absorption capability with a minimum reflection loss (RLmin) of −55.87 dB, −48.49 dB, and −40.36 dB at room temperature, 50 °C, and 100 °C, respectively; the 50 wt.%C@TiC composite exhibits an enhanced high-temperature microwave absorption performance with an RLmin of −16.13 dB and −15.72 dB at 200 °C and 300 °C, respectively. This study demonstrates that the TiC-based absorbers present an innovative solution for high-temperature microwave absorption, providing stability, versatility, and adaptability in extreme operational environments.

Quinoidal Semiconductor Nanoparticles for NIR-II Photoacoustic Imaging and Photoimmunotherapy of Cancer.

Photoagents with ultra-high near-infrared II (NIR-II) light energy conversion efficiency hold great promise in tumor phototherapy due to their ability to penetrate deeper tissues and minimize damage to surrounding healthy cells. However, the development of NIR-II photoagents remain challenging. In this study, an all-fused-ring quinoidal acceptor-donor-acceptor (A-D-A) molecule, SKCN, with a BTP core is synthesized, and nanoparticles named FA-SNPs are prepared. The unique quinoidal structure enhances π-electron delocalization and bond length uniformity, significantly reducing the bandgap of SKCN, resulting in strong NIR-II absorption, a high molar extinction coefficient, and a photothermal conversion efficiency of 75.14%. Enhanced molecular rigidity also facilitates efficient energy transfer to oxygen, boosting reactive oxygen species generation. By incorporating the immunomodulator R848, FA-SRNPs nanoparticles are further developed, effectively modulating the tumor immune microenvironment by reducing Tregs and M-MDSCs infiltration, promoting dendritic cell maturation, M1 macrophage polarization, and activating CD8+ T cells and NK cells. Comprehensive studies using orthotopic ovarian cancer models demonstrated strong tumor targeting, photoacoustic imaging capabilities, and significant tumor suppression and metastasis inhibition, and also showing excellent therapeutic efficacy in an orthotopic breast cancer model. This study provides strong evidence for the potential application of quinoidal A-D-A molecules in cancer photoimmunotherapy.

Exploring the Role of Flexoelectric Effect in Band Modulation in 1D MoS2/Boron Phosphide Nanotube Heterostructures.

Designing and discovering superior type-II band alignment are crucial for advancing optoelectronic device technologies. Here, we employ first-principles calculations to investigate the evolution of band edges in monolayer MoS2, boron phosphide (BP), and MoS2/BP heterostructures before and after their rolling into nanotubes. Our research results indicate that the intrinsic MoS2/BP vertical heterostructures exhibit a type-II direct bandgap, but this feature is not robust under strain. For MoS2/BP coaxial heterotubes, the type of bandgap is influenced by both chirality and diameter. Specifically, when the diameter exceeds 19 Å under zigzag chirality, the system undergoes a transition from a type-I direct bandgap to a type-II direct bandgap, which remains stable within a strain range of -6 to 6%. Furthermore, we delve into the alterations in band edge positions in single-walled nanotubes induced by curvature-driven flexoelectric effects and circumferential tensile strain. In coaxial heterotubes, the transfer of electrons between the inner and outer tubes forms a cylindrical capacitor-like structure. Incorporating the inherent flexoelectric voltage in single-walled nanotubes, we have derived a functional relationship between the counteracting voltage (Vhyb) and their diameter. Finally, the system was explored for its strong light absorption capabilities with absorption levels up to 105, and it was found that strain can effectively modulate the range of light absorption. The findings of this research contribute to new insights and theoretical foundations for the development of novel one-dimensional (1D) van der Waals (vdW) optoelectronic devices.

Enhancing Multispectral Breast Imaging Quality Through Frame Accumulation and Hybrid GA-CPSO Registration

Multispectral transmission imaging has emerged as a promising technique for imaging breast tissue with high resolution. However, the method encounters challenges such as low grayscale, noisy transmission images with weak signals, primarily due to the strong absorption and scattering of light in breast tissue. A common approach to improve the signal-to-noise ratio (SNR) and overall image quality is frame accumulation. However, factors such as camera jitter and respiratory motion during image acquisition can cause frame misalignment, degrading the quality of the accumulated image. To address these issues, this study proposes a novel image registration method. A hybrid approach combining a genetic algorithm (GA) and a constriction factor-based particle swarm optimization (CPSO), referred to as GA-CPSO, is applied for image registration before frame accumulation. The efficiency of this hybrid method is enhanced by incorporating a squared constriction factor (SCF), which speeds up the registration process and improves convergence towards optimal solutions. The GA identifies potential solutions, which are then refined by CPSO to expedite convergence. This methodology was validated on the sequence of breast frames taken at 600 nm, 620 nm, 670 nm, and 760 nm wavelength of light and proved the enhancement of accuracy by various mathematical assessments. It demonstrated high accuracy (99.93%) and reduced registration time. As a result, the GA-CPSO approach significantly improves the effectiveness of frame accumulation and enhances overall image quality. This study explored the groundwork for precise multispectral transmission image segmentation and classification.

Optical and Electrochemical Analysis of Surface‐Enhanced ZnZrO3:Eu3+ Nanostructures for Forensic Applications

AbstractThe surface‐enhanced local crystal structure of a series of ZnZrO3:Eu3+(1 to 5 mol.%) (ZZE) orange–red nanophosphors synthesized using a sol‐gel combustion process is investigated. X‐ray diffraction (XRD) with the Rietveld refinement analysis reveals a monoclinic ZnZrO3:Eu3+ structure with a space group 14. Field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM) analyses reveal the honeycomb alignment of nanoparticles in structure formation. The UV–vis‐diffuse reflectance spectroscopy (UV–vis‐DRS) analysis reveals strong absorption in the UV region, with an increase in the energy bandgap upon the addition of Eu3+ ions (1 to 5 mol.%). The optimized ZnZrO3:Eu3+(2 mol.%) nanophosphor exhibits high‐intensity orange‐red emission at 615 nm, as revealed by photoluminescence (PL) spectroscopy. Cyclic voltammetry (CV) analysis confirms the surface‐modified ZnZrO3:Eu3+ (2 mol.%) nanophosphor and hence reveals its electrochemical stability and selectivity to form stable suspensions with liquids or solids. ZnZrO3:Eu3+ (1 to 5 mol.%) exhibits fluorophore (Eu3+) embedded, surface‐enhanced Raman scattering, which opens new bioimaging applications. Further, the optimized ZnZrO3:Eu3+ (2 mol.%) nanophosphor investigated for the identification of latent fingerprint patterns (LFP) under visible light indicates its potential as a strong LFP‐revealing material in forensics without alternate light sources or chemical reagents.

Unlocking high-performance near-infrared photodetection: polaron-assisted organic integer charge transfer hybrids

Room temperature femtowatt sensitivity remains a sought-after attribute, even among commercial inorganic infrared (IR) photodetectors (PDs). While organic IR PDs are poised to emerge as a pivotal sensor technology in the forthcoming Fourth-Generation Industrial Era, their performance lags behind that of their inorganic counterparts. This discrepancy primarily stems from poor external quantum efficiencies (EQE), driven by inadequate exciton dissociation (high exciton binding energy) within organic IR materials, exacerbated by pronounced non-radiative recombination at narrow bandgaps. Here, we unveil a high-performance organic Near-IR (NIR) PD via integer charge transfer between Poly[2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene] (C-14PBTTT) donor (D) and Tetrafluorotetracyanoquinodimethane (TCNQF4) acceptor (A) molecules, showcasing strong low-energy subgap absorptions up to 2.5 µm. We observe that specifically, polaron excitation in these radical and neutral D-A blended molecules enables bound charges to exceed the Coulombic attraction to their counterions, leading to an elevated EQE (polaron absorption region) compared to Frenkel excitons. As a result, our devices achieve a high EQE of ∼107%, femtowatt sensitivity (NEP) of ~0.12 fW Hz-1/2 along a response time of ~81 ms, at room temperature for a wavelength of 1.0 µm. Our innovative utilization of polarons highlights their potential as alternatives to Frenkel excitons in high-performance organic IR PDs.

Ultrathin, Wavelength‐Multiplexed and Integrated Holograms and Optical Neural Networks Based on 2D Perovskite Nanofilms

AbstractHolography, as a technique for coherent wavefront reconstruction, is extensively used in numerous optical applications such as optical imaging, 3D display, photolithography, and optical artificial intelligence. In order to achieve highly compact and functional integration with optoelectronic devices, the hologram needs to possess ultrathin thickness as well as multicolor functionality. However, its thickness is typically limited to optical wavelength ranges due to the requirement for pronounced amplitude or phase modulation, and it generally operates at a single wavelength band without wavelength‐multiplexed channels. Here, the hologram is decreased thickness to sub‐ten nanometers by exploiting the large refractive index and strong exciton absorption of 2D perovskites. Ultrathin perovskite holograms and holographic neural networks with high stability are successfully developed by using femtosecond laser direct writing, and their operation wavelength can be rationally tuned from 400–515 nm through halide anion engineering. Consequently, the wavelength can be multiplexed with low cross‐talks by stacked perovskite nanolayers for applications of holographic display and neural networks without the usages of complex optical structures or filters. This work provides a feasible and promising technical route for integrating ultrathin, high pixel density, and multiplexed holographic structures with flat optoelectronic devices for next‐generation integrated optical systems.

Investigation of the Effect of Copper Nanoparticle Deposition on Low-Carbon Steel using Physical Vapor Deposition for Solar Cooling Application

The use of nanomaterials in solar cooling applications has gained significant attention in recent years. This study aimed to increase thermal conductivity by depositing copper nanoparticles (Cu-NP) on low-carbon steel using thermal evaporation and a physical vapor deposition (PVD) method. Low-carbon steel was selected as the substrate due to its wide use in thermal applications and strong absorption properties. The presence of Cu-NP on the surface was analysed using XRD and thermal characteristics of the thin layer were determined using Thermal Constant Analyzer (TCA) and Transient Plane Source (TPS) measurements. Results showed that the copper nanoparticle coating sample on the carbon steel substrate had better heat emission and absorption compared to the carbon steel alone. It also shows some improvement of around 1% in the thermal conductivity results. This study demonstrates the potential of using Cu-NP deposited on low-carbon steel as a promising material for solar thermal/cooling applications.

Portfolio of colloidally stable gold-gold sulfide nanoparticles and their use in broad-band photoacoustic imaging.

There is an increasing interest in non-invasive photoacoustic imaging and hence demand for non-toxic, stable, optical solid absorbers, particularly in the visible and near-infrared regions enabling deep tissue penetration. The most popular gold nanorods (GNR) suffer from cumbersome synthesis with poor reproducibility and stability under moderate laser exposure. Recently, a new class of nanoparticle, gold-gold sulfide (GGS), was recognized to have strong NIR absorption but lack colloidal stability. Here, we successfully synthesized a portfolio of aqueous GGS nanoparticles (NP) with excellent stability through a one-step, reproducible synthesis: Anionic, cationic, and protein-coated GGS NPs were obtained by using 3-mercaptopropionic acid (3MPA), branched poly(ethyleneimine) (bPEI) and bovine serum albumin (BSA) as a coating. All GGS NPs comprise small (<10 nm) and large anisotropic (>30 nm) morphologies and display two absorption bands centered at 530-540 nm and 800-900 nm. The photoacoustic activity (PA) of GGS NPs in solution at the visible (532 nm) and NIR (800 nm) region is similar and independent of the coating. Remarkably, they outperformed the spherical gold NPs and performed comparable to GNRs. In vitro PA microscopy images recorded with visible and NIR lasers revealed that GGS NPs are successfully internalized by triple-negative MDA-MB-231 breast cancer cells, used for the proof of principle. A coating-dependent intracellular PA signal in favor of GGS-3MPA was observed. The weakest signal was obtained with the GGS-BSA, indicating a low cellular uptake. These stable, aqueous GGS NPs emerge as promising candidates for broad-band PAI and further biomedical applications.

Investigation on the effect of complex formation on prominent high static/dynamic first and second hyperpolarizability of Co(II) complex including 4-chloro-Pyridine-2-Carboxylic acid

Nonlinear optical (NLO) materials with promising first- and second-order hyperpolarizabilities play a crucial role in the fields of electronics and optoelectronics. For the metal-organic coordination complexes, the logical selection of an appropriate ligand and metal ion is vital in designing such materials to enhance their NLO response. In this study, a novel Co(II) complex, including 4-Chloro-pyridine-2-carboxylic acid ligand, was synthesized. The crystal structure and spectroscopic properties were determined by XRD, FT-IR, and UV–Vis spectroscopies. B3LYP and CAM-B3LYP level calculations demonstrated that there is a strong electronic absorption band at 356 nm, originating from the metal-ligand charge transfer (MLCT) transfer in the UV–Vis spectrum. Both XRD and FT-IR data demonstrated that the Co(II) complex has a distorted octahedral coordination geometry. The calculations of static and frequency-dependent α, β, and γat frequencies of ω = 0.0856252 a.u (λ = 532 nm) and w = 0.0428126 au. (λ = 1064 nm) for 4Clpca and Co(II) complex have been also carried out using B3LYP and CAM-B3LYP levels. The dc-Kerr effect γ(-ω; ω,0,0) and SHG γ(-2ω; ω,ω,0) parameters for Co(II) complex calculated as 329.59 × 10−36 and 433.93 × 10−36 esu are found as dramatically higher those for single pca ligand (6.0267 × 10−36 and 163.70 × 10−36 esu). So, a significant increase was detected in the parameters of frequency-dependent α (-w; 0), β(-w; w,0), and γ (-w; w,0,0) with complex formation.

Structural Reconfiguration via Alternating Cation Intercalation of Chiral Hybrid Perovskites for Efficient Self-Driven X-ray Detection.

2D hybrid perovskites (HPs) have great potential for high-performance X-ray detection due to their strong radiation absorption and flexible structure. However, there remains a need to explore avenues for enhancing their detection capabilities. Optimizing the detection performance through modification of their structural properties presents a promising strategy. Herein, we explore the impact of modifying the organic spacer layer in two distinct 2D layered HPs, namely, Ruddlesden-Popper (R-MPA)2PbBr4 (R-1, R-MPA = methylphenethylammonium) and (R-MPA)EAPbBr4 (EA = ethylammonium) (R-2) with alternating cation intercalation (ACI), on their X-ray detection performance. The insertion of EA into R-2 results in a flatter inorganic skeleton, narrower spacing, and higher density compared to R-1. This structural modification effectively optimizes carrier transport and X-ray absorption in R-2, enhancing the X-ray detection performance. Notably, R-2 exhibits a polar structure with intrinsic spontaneous polarization, contributing to a bulk photovoltaic of 0.4 V. This feature enables R-2 single-crystal detectors to achieve self-driven X-ray detection with a low detection limit of 82.5 nGy s-1 under a 0 V bias. This work highlights the efficacy of the ACI strategy in structural modification and its significant effect on X-ray detection properties, providing insights for the design and optimization of new materials.

Real-time three-dimensional monitoring and analysis of perovskite solar cell using short wavelength infrared digital holography

The quality and crystallization process of all-inorganic perovskite films play a crucial role in the performance of solar cells. However, traditional detection methods lack three-dimensional depth information and real-time capabilities, hindered by strong visible light absorption, posing challenges to research. Here, a simple digital holography technique is proposed that offers real-time, nondestructive, three-dimensional phase imaging with low absorption characteristics in the short-wave infrared range. The use of short-wave infrared reduces the negative impact of visible light and vibrations in the environment on detection accuracy, while being nearly non-absorbing. The proposed method operates at a speed of 15 Hz, combining a lensless vertical structure, holographic reconstruction algorithm, and phase unwrapping algorithm to achieve real-time three-dimensional observation without image distortion and with low noise of the crystallization process of CsPbBr3 perovskite quantum dots (PQDs)/ethylene-vinyl acetate solution, which crystallizes in 39 s. Subsequently, employing minimum bounding rectangle, field stitching, intensity registration, and sub-pixel level calibration algorithms, real-time characterization is performed on the large-sized droplet of polymethyl methacrylate-matrix-encapsulated CsPbBr3 perovskite quantum dots, which has a crystallization time of 1285 s, without being limited by the field of view. Finally, using this system, the surface quality of the film is assessed, revealing fluctuations at the edge and fabrication defects of the perovskite film. Experimental results demonstrate the potential of short-wave infrared digital holography in enhancing the film formation process and quality inspection. By leveraging this technology, advancements in the development of high-performance all-inorganic perovskite solar cells can be fostered, optimizing global energy output.

Improved absorption of phosphates through interface junctions and photothermal–energy–storage capability of Ca(OH)2–[Co3O4–Co3(PO4)2]

Strong absorption in the full solar spectrum is required for efficient usage of solar energy. Near-infrared (NIR) light absorption mainly depends on surface plasmon resonance and a high density of free charge carriers (FCCs). However, increasing FCC density in semiconductors is still a challenge. In this work, we demonstrated that multitudinous S-scheme interface junctions can be constructed within nanoscale Co3O4–Co3(PO4)2, leading to enhanced light absorption of phosphates over the entire solar spectrum due to the increased FCC density and charge-carrier configurations. This absorber can also boost the photothermal performance of Ca(OH)2. The photothermal dehydration conversion of Ca(OH)2 is considerably improved (13.7 times). The reversibility of the photothermal hydration–dehydration cycles of Ca(OH)2 is improved by 39 times. This composite is promising for photothermal conversion and thermal energy storage in one-step.

Metal-nitrilotriacetic acid chelate derived strategy to selectively produce porous Ni/C, CoNi/C and Co/C magnetic heterostructured nanorods for lightweight and strong microwave absorption

Because of tempting magnetic-dielectric synergies and interfacial effects, designing a simple and low-cost route for producing multidimensional carbon-based magnetic nanocomposites is very important for the development of microwave absorbers (MAs). In this paper, a facile and propagable Ni-nitrilotriacetic acid chelate (NAC) derived strategy was proposed to selectively fabricate zero-dimensional (0D)/one-dimensional (1D) porous Ni/C magnetic heterostructured nanorods (MHNRs) consisting of 1D carbon nanorod, lots of pores and 0D Ni nanoparticles via a combined hydrothermal and thermally treated methods. The porous Ni/C MHNRs displayed the progressively improved Ni and C crystallinity by controlling the temperature, which resulted in the tunable electromagnetic and microwave absorption properties (MAPs). Additionally, 0D/1D porous CoNi/C and Co/C MHNRs could be selectively produced through this strategy by adopting CoNi-NAC and Co-NAC as precursors. Benefiting from desirable interface and magnetic/dielectric synergies, the acquired 0D/1D porous Ni/C, CoNi/C and Co/C MHNRs presented excellent MAPs and certain corrosion resistance properties. In especial, Co/C MHNRs displayed a strong absorption capacity (−47.89 dB), an ultrawide effective absorption bandwidth (8.40 GHz) and small matching thicknesses (∼2 mm), which were a desirable candidate for MAs. Consequently, a facile, low-cost and propagable metal-NAC derived strategy was proposed to synthesize 0D/1D porous carbon-based MHNRs, which presented an alternative technique to develop lightweight efficient MAs.

On-chip integrated plasmon-induced high-performance self-powered Pt/GaN ultraviolet photodetector

The advantages of on-chip integrated photodetectors, such as miniaturization, high integration, and reliability, make them an indispensable and important part of electronic devices and systems. Herein, we experimentally exhibit a monolithically integrated ultraviolet photodetector utilizing GaN microcylinder epitaxial-structure on Si wafer, with its photoresponse properties plasmonically-boosted using Pt nanoparticles via specific sizes. When illuminated upon ultraviolet light at 0 V bias, the Pt/GaN device has significant photovoltaic performances, including a peak responsivity of 200.1 mA W-1, external quantum efficiency of 65% and other figures-of-merit. Finite element analysis and energy band theory confirm that the excellent photodetection properties of the Pt/GaN device are related to the strong plasmon absorption and the increase of hot electrons injected into the GaN conduction band, which make its photoresponse performance and robustness in application much better. To realize the multipurpose capability of the devices, we validate the application of Pt/GaN as turbidity sensing and achieve a resolution of up to 100 NTU. Moreover, the prepared devices can be used as optical data receivers for optical communication. These findings provide references for on-chip detectors to improve overall system performance and drive the realization of more complex applications.

A Spectroscopic and Interferometric Study of W Serpentis Stars. I. Circumbinary Outflow in the Interacting Binary W Serpentis

W Serpentis is an eclipsing binary system and the prototype of the Serpentid class of variable stars. These are interacting binaries experiencing intense mass transfer and mass loss. However, the identities and properties of both stars in W Ser remain a mystery. Here, we present an observational analysis of high-quality, visible-band spectroscopy made with the Apache Point Observatory 3.5 m telescope and Astrophysical Research Consortium Echelle Spectrograph spectrograph plus the first near-IR, long-baseline interferometric observations obtained with the Center for High Angular Resolution Astronomy Array. We present examples of the appearance and radial velocities of the main spectral components: prominent emission lines, strong shell absorption lines, and weak absorption lines. We show that some of the weak absorption features are associated with the cool mass donor, and we present the first radial velocity curve for the donor star. The donor’s absorption lines are rotationally broadened, and we derive a ratio of donor to gainer mass of 0.36 ± 0.09 based on the assumptions that the donor fills its Roche lobe and that it rotates synchronously with the orbit. We use a fit of the All-Sky Automated Survey light curve to determine the orbital inclination and mass estimates of 2.0M ⊙ and 5.7M ⊙ for the donor and gainer, respectively. The partially resolved interferometric measurements of orbital motion are consistent with our derived orbital properties and the distance from Gaia EDR3. Spectroscopic evidence indicates that the gainer is enshrouded in an opaque disk that channels the mass transfer stream into an outflow through the L3 region and into a circumbinary disk.

The Featherweight Giant: Unraveling the Atmosphere of a 17 Myr Planet with JWST

The characterization of young planets (<300 Myr) is pivotal for understanding planet formation and evolution. We present the 3–5 μm transmission spectrum of the 17 Myr, Jupiter-size (R ∼10R ⊕) planet, HIP 67522b, observed with JWST NIRSpec/G395H. To check for spot contamination, we obtain a simultaneous g-band transit with the Southern Astrophysical Research Telescope. The spectrum exhibits absorption features 30%–50% deeper than the overall depth, far larger than expected from an equivalent mature planet, and suggests that HIP 67522b’s mass is <20 M ⊕ irrespective of cloud cover and stellar contamination. A Bayesian retrieval analysis returns a mass constraint of 13.8 ± 1.0 M ⊕. This challenges the previous classification of HIP 67522b as a hot Jupiter and instead, positions it as a precursor to the more common sub-Neptunes. With a density of <0.10 g cm−3, HIP 67522 b is one of the lowest-density planets known. We find strong absorption from H2O and CO2 (≥7σ), a modest detection of CO (3.5σ), and weak detections of H2S and SO2 (≃2σ). Comparisons with radiative-convective equilibrium models suggest supersolar atmospheric metallicities and solar-to-subsolar C/O ratios, with photochemistry further constraining the inferred atmospheric metallicity to 3 × 10 solar due to the amplitude of the SO2 feature. These results point to the formation of HIP 67522b beyond the water snowline, where its envelope was polluted by icy pebbles and planetesimals. The planet is likely experiencing substantial mass loss (0.01–0.03 M ⊕ Myr−1), sufficient for envelope destruction within a gigayear. This highlights the dramatic evolution occurring within the first 100 Myr of its existence.

An advanced deep learning-driven Terahertz metamaterial sensor for distinguishing different red wines

Terahertz time-domain spectroscopy (THz-TDS) encounters two issues in the detection field, which refer to the detection target for solid samples caused by the strong absorption of water and the large content target substance led by the low sensitivity. Fortunately, terahertz metamaterial (THz-MM) that can carry liquid samples and amplify signals solves the above problems well. In addition, the THz-MM can achieve the detection of trace substances through the resonance peak shift generated by designing suitable structures. However, since most researchers focus on designing complex structures rather than analyzing data, deep learning (DL) that can mine new features from original features and construct decision models is used to research the rich information in THz-MM sensor data. In the current research, a flexible transmissive THz-MM in the shape of a circle (‘O’ shape) was designed by depositing the gold on the polyimide substrate. Firstly, the structures referring to substrate thickness (ST), metal thickness (MT) and ring width (RW) were optimized, and the performances referring to principle, stability and sensitivity were evaluated. Next, the best THz-MM (ST: 16 µm, MT: 0.2 µm, RW: 6 µm) was prepared and characterized from morphology, thickness and consistency. Then, different concentrations of anthocyanins (R2: 0.9982) and tannic acid (R2: 0.9736) were successfully predicted by combining the resonance peak shifts. Finally, resonance peak descriptors were constructed and combined with DL referring to a fully connected neural network (FCNN) model to successfully identify different varieties of red wines (Precision: 91.11 %; Recall: 90.74 %, F1-score: 90.83 %; Accuracy: 90.74 %). Overall, the current research presents an advanced DL-driven THz-MM sensor, which promotes the process of THz-TDS technology in the food detection field

Lightweight dielectric-magnetic synergistic necklace-shaped Co@NCP/carbon nanofiber composites for enhanced electromagnetic wave absorption

In order to solve the problem of impedance mismatch of carbon fiber absorbing materials, it is crucial to create a carbon-based absorbing material with a special structure, synergistic magnetic and dielectric properties. In this paper, necklace-shaped Co@N-doped carbon polyhedron /carbon nanofiber (Co@NCP/CNF) composites with synergistic magnetic and dielectric properties are successfully fabricated by electrospinning. Compared with Co@NCP and CNF, the optimal minimum reflection loss of Co@NCP/CNF composite is -66.14 dB at 2.89 mm and the maximum effective absorption bandwidth is 6.24 GHz (11.76-18.00 GHz) at 2.25 mm at a low filler load of 10 wt.%. The necklace-like structure, the coupling effect of dielectric and magnetic materials and the heterogeneous interface form multiple polarizations, conductive losses and multiple loss mechanisms to optimize impedance matching and attenuation performance, which is conducive to excellent absorption performance. More importantly, the radar cross section (RCS) reduction is as high as 24.02 dB·m2, which has proven to have a good absorption effect in actual application environments. This work combines the advantages of Co@NCP and CNF very well, which provides guidance for designing EM waves nanocomposite fiber absorbers with lightweight and strong absorbing properties.

Role of LED (Light Emitting Diode) Light Illumination on the Growth of Plants in Greenhouse Farming-Hydroponics: IOT Technology

This review paper of literature highlights role of Light Emitting Diode (LED) on the growth of plants under controlled conditions of greenhouse farming particularly hydroponics. “Internet of Things (IOT)” is a system of interconnected computing devices, sensors, objects, microcontrollers, and cloud servers that can transmit data across a network and control other devices remotely without human intervention. Light Emitting Diode (LED) is a more efficient, versatile, lasts longer, highly energy-efficient, directional, narrow light spectrum, low power consumption, and little heat production. Common LED colors include amber, red, green, and blue. Hydroponic grow lights are designed to mimic the natural light that plants need for photosynthesis. Plants can only use the spectrum of visible light to produce photosynthesis, and this narrow spectrum (400 to 700 nanometer) is recognized as the Photosynthetically Active Radiation (PAR). The development and growth of diverse plant species can be influenced differently by a variety of colored LED lights. LED illumination provides an efficient way to improve yield and modify plant properties. Therefore, LED systems plays an important role in controlling morphological, genetic, physiological, chemical properties, increasing the synthesis of a variety of beneficial secondary metabolites, and optobiological interactions of plants in greenhouse farming. In general, red and blue light is essential for maximizing the photosynthesis process due to their strong absorption by the plant chlorophyll molecules. LED illumination sources are increasingly being utilized to enhance the growth rate of vegetables and herbs cultivated in greenhouses worldwide. LED illumination spectrum manipulation could enable significant morphological adaptations, and identification of the wavelength ranges is required to increase the plant photosynthesis process.