Search Results (40)

Near-infrared spectroscopy (NIRS) is widely used for rapid and non-destructive evaluation of feed nutritional quality, but robust calibration remains challenging for heterogeneous multi-product feed datasets. This study evaluated convolutional neural network (CNN)-based models for predicting crude protein (CP) and acid detergent fiber (ADF) using a previously published NIR database containing forage and grain-based feeds. A one-dimensional CNN and two hybrid models, CNN combined with partial least squares regression (CNN+PLS) and XGBoost (CNN+XGBoost), were developed and compared with conventional PLSR calibration models based on either the pooled multi-product dataset or product-specific subsets. Model performance was assessed using an independent internal hold-out test set generated within the same database. For CP prediction, CNN-based models achieved strong performance on the hold-out test set, with testing R² values of 0.98 and RMSEP values of 0.60–0.62, showing a clear reduction in prediction error compared with the global PLSR model. For ADF, CNN and CNN+PLS provided only modest improvements over global PLSR, whereas CNN+XGBoost showed weaker generalization for ADF. Product-wise results further indicated that ADF prediction was more strongly affected by feed matrix and product category than CP prediction. Grad-CAM examples suggested that CNN activation patterns were broadly consistent with known protein- and fiber-related absorption regions, although this interpretation should be regarded as illustrative evidence of spectral coherence rather than direct chemical causality. Overall, CNN-based models, particularly CNN+PLS, showed promise for improving NIRS prediction of CP in heterogeneous feed datasets, while their advantage for ADF was limited. Further validation using independent external datasets and multi-instrument conditions is required before routine implementation. Full article

Metal–organic frameworks (MOFs), particularly Zeolitic Imidazolate Framework-8 (ZIF-8), are promising photocatalysts; however, their practical application is limited by a wide band gap (~3.85 eV), which restricts light absorption mainly to the ultraviolet region. This limitation was addressed by synthesizing a series of cobalt-doped ZIF-8 materials, Co(x)ZIF-8 (x = 0, 2.5, 5, 7.5, and 10 wt%), using a cost-effective aqueous synthesis route. Structural and compositional analyses using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and energy-dispersive X-ray spectroscopy (EDS) confirmed the formation of phase-pure ZIF-8 topology, with no significant change in nanoparticle morphology upon the partial substitution of Zn²⁺ by Co²⁺ ions within the framework. UV–Vis diffuse reflectance and Tauc plot analysis revealed a systematic and substantial reduction in the optical band gap (Eg) with increasing Co content, indicating enhanced visible-light absorption capability. All Co(x)ZIF-8 samples exhibited superior photocatalytic activity compared to pristine ZIF-8 under light irradiation. Among them, Co(2.5)ZIF-8 displayed the highest apparent reaction rate constant for pollutant degradation, while Co(5)ZIF-8 achieved the highest overall degradation efficiency (~87%) after 40 min. The enhanced photocatalytic performance is attributed to the synergistic effects of band-gap narrowing and the presence of Co²⁺ ions, which act as effective charge-trapping centers and suppress electron–hole recombination. Electrochemical measurements further demonstrated that Co(5)ZIF-8 exhibits the highest current density (most negative J) at large negative potentials (e.g., J ≈ −0.105 A cm⁻² at E = −2.0 V), indicating superior intrinsic catalytic activity. These findings highlight cobalt-doped ZIF-8 as a highly tunable and efficient photocatalyst with strong potential for environmental remediation applications. Full article

Photoacoustic imaging (PAI) integrates the high-contrast merits of optical imaging with the high-spatial-resolution advantages of acoustic imaging, enabling the acquisition of three-dimensional images with deep tissue penetration (up to several centimeters) for in vivo disease detection and diagnosis. Among various photoacoustic nanoagents, gold nanomaterials (GNMs) have been widely explored for the PAI-based imaging analysis and photothermal therapy of diseases, owing to their strong near-infrared (NIR) absorption, which can generate distinct photoacoustic signals in deep tissues. This review focuses on recent advances and achievements in the development of functionalized gold nanoprobes, including Janus gold nanoprobes, gold nanocomposite probes (such as functionally coated GNMs and GNMs-loaded nanocarriers), and gold nanoaggregate probes (e.g., pre-assembly of GNMs and in situ aggregation of GNMs). The multifunctionalization of GNMs can enhance their PAI performance by shifting absorption to the NIR-I and NIR-II regions, while simultaneously imparting additional functionalities such as targeted delivery to disease sites and specific responsiveness to disease biomarkers. These features can render functionalized GNMs-based nanoprobes highly suitable for PAI-based analysis and the precise detection of various pathological conditions, including bacterial infections, tumors, kidney injury, and disorders affecting the ocular, gastrointestinal, cardiovascular, visceral, and lymphatic systems. Finally, this review provides a concise summary of biosafety evaluation and outlines the current challenges and future perspectives in optimizing the GNMs-based PAI methods, highlighting their potential to enhance the rapid and precise diagnosis of diseases in the future. Full article

Infrared thermal cameras can noninvasively measure the surface temperatures of objects and are widely used as fever-screening systems for infectious diseases. However, body temperature measurements alone are often insufficient for identifying people with infections. To address the inherent limitations of fever-based screening, this study aimed to develop analytical methods that enable multi-vital sensing alongside body temperature measurement using a single mid-wave infrared (MWIR) camera. Respiratory parameters were assessed by visualizing exhaled airflow based on MWIR absorption by carbon dioxide, whereas the heart rate was estimated from subtle temperature fluctuations captured using high thermal resolution. The experimental results validated the proposed method, showing that the developed system achieved good agreement with reference measurements; the respiratory rate, heart rate, and body temperature showed strong correlations (r = 0.864–0.987) and acceptable limits of agreement in Bland–Altman analyses. The exhalation volume was quantified from the visualized airflow and was found to align with the expected physiological ranges. These results demonstrate that noncontact multi-vital sensing can be achieved using a single MWIR camera, without the need for complex instrumentation. The proposed method holds promise for high-precision infection screening, remote health monitoring, and in-home physiological assessment. Full article

A photovoltaic-integrated broadband photodetector based on vertically-stacked lateral-aligned III–V nanowire arrays is proposed and investigated. The staggered arrangement configuration drastically reduces the competition between solar cell and photodetector that is difficult to avoid in vertically-stacked planar structures, which enables broadband strong absorption. The lower GaAs nanowires (NWs) act as Mie scattering centers, which scatter the incident light passing through the gaps back to the upper layer, enhancing the absorption of InAs NWs over a wide wavelength range from the ultraviolet to the infrared. Meanwhile, the light trapping effect of the upper InAs nanowires improves the absorption of lower GaAs NWs. At a near-infrared wavelength of 1400 nm, the photovoltaic-integrated InAs nanowire photodetector exhibits a photocurrent density of 168.83 mA/cm² and responsivity of 0.168 A/W, 90% and 93% higher than the single layer InAs nanowires. The conversion efficiency of the GaAs nanowire solar cell is also improved after integration. This work may pave the way for the development of self-powered miniaturized broadband photodetectors. Full article

The Gross Calorific Value (GCV) is a key indicator used to assess the energy potential and quality of coal. Conventional oxygen bomb calorimetry, though widely used, is inherently time-consuming due to the combustion process involved. Similarly, regression models for GCV prediction based on ultimate or proximate analyses require extensive laboratory procedures and sample preparation. To address these challenges, this study investigates the use of mid-infrared Fourier Transform Infrared (FTIR) spectroscopy coupled with supervised variable selection to enable rapid, non-destructive, and cost-effective assessment of coal properties. In this work, a detailed mid-infrared FTIR spectral analysis of coal was conducted to identify fifty-six selective absorption bands (supervised input variables) sensitive to the organic functional group content in coal, coupled with several machine learning (ML) techniques to model the GCV of coal samples from the Johilla coal basin, India. The ML techniques employed here are piecewise linear regression (PLR), partial least squares regression (PLSR), support vector regression (SVR), random forest regression (RFR), artificial neural networks (ANN), and extreme gradient boosting regression (XGB). A multi-model estimation of GCV using the simple average output of the three models (PLSR, RFR, and XGB) achieved the best predictive performance (R² = 0.951, RMSE = 19.050%, MBE = 1.420%, MAE = 4.053 cal/g), reflecting strong consistency between predictions and actual measurements. The FTIR-based approach achieves competitive or improved results relative to conventional methods and models documented in prior studies. The GCVs derived through modeling of FTIR data are also statistically proven (using t-test and F-test at alpha = 0.01) to be significantly similar to those of the bomb calorimeter, an industry standard for GCV measurements. Consequently, this novel FTIR-based methodology establishes an efficient, dependable tool for GCV determination that operates independently of conventional techniques, thereby enabling rapid quality assessment critical for industrial applications. Full article

Galactomannans, like locust bean gum, are polysaccharides widely used in the food and pharmaceutical industries because of their rheological and functional properties. However, their optical and thermal characterization is challenging due to their viscous and highly dispersive nature, which hinders the applicability of conventional spectroscopic and calorimetric techniques. In this study, photopyroelectric techniques were used to simultaneously determine, for the first time, the optical absorption coefficients and thermal diffusivity of locust bean gum in aqueous suspension at various concentrations. Optical characterization was performed at 660 nm (visible) and 1550 nm (near-infrared), revealing strong absorption at 1550 nm associated with hydroxyl group overtones and allowing reliable quantification at concentrations as low as 0.5 g/100 mL. Thermal characterization yielded diffusivity values ranging from 1.50 × 10⁻³ to 1.47 × 10⁻³ cm²/s, with a slight decreasing trend as concentration increased. These results confirm the applicability of photopyroelectric methods for the dual optical and thermal characterization of galactomannans and highlight their potential for analyzing complex biopolymer suspensions where traditional methods fall short. Full article

Sunset yellow (SY) is a synthetic azo dye widely used in food and cosmetics. However, concerns have been raised about its potential health risks, including its nephrotoxicity and genotoxicity, when used in excessive amounts. Illegal addition of SY may cause allergic reactions or genetic damage. Therefore, a rapid method for detecting SY is needed. To develop a rapid detection method for sunset yellow (SY) with the aim of preventing its illegal addition in food, this study utilized agricultural waste asparagus peel (AP) as a carbon source and synthesized amino-functionalized carbon quantum dots (AP-CDs) via a green hydrothermal method. A highly sensitive detection platform was established based on the fluorescence quenching mechanism of AP-CDs in the presence of SY. The microstructure of AP-CDs was characterized using transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Their optical properties were assessed via ultraviolet–visible absorption spectroscopy (UV-vis) and fluorescence spectroscopy (FS). Furthermore, key experimental parameters affecting SY detection were systematically optimized. Results revealed that the synthesized AP-CDs possessed surface hydrophilic functional groups, including hydroxyl, amide, and carboxyl groups, and were composed of carbon (C), oxygen (O), and nitrogen (N) elements. Optical performance studies demonstrated that AP-CDs exhibited a strong fluorescence emission at 470 nm under 380 nm excitation, with a quantum yield (Φ) of 15.9%. Under the optimized conditions (pH 7.0, 0.5 mg/mL AP-CDs), the fluorescence intensity showed a linear response to the concentration of SY over the range of 0.1 to 100 μM (R² = 0.9929), achieving a detection limit of 0.92 μM. This strategy not only enables sustainable resource utilization but also provides a sensitive and practical approach for food safety monitoring, demonstrating significant potential for real-world applications. Full article

This work presents a high-performance novel photodetector based on two-dimensional boron nitride (BN) nanosheets functionalized with gold nanoparticles (Au NPs), offering ultra-broadband photoresponse from 0.25 to 5.9 μm. Operating in both photovoltaic and photoconductive modes, the device features rapid response times (<0.5 ms), high responsivity (up to 1015 mA/W at 250 nm and 2.5 V bias), and thermal stability up to 100 °C. The synthesis process involved CO₂ laser exfoliation of hexagonal boron nitride, followed by gold NP deposition via RF sputtering and thermal annealing. Structural and compositional analyses confirmed the formation of a three-dimensional network of atomically thin BN nanosheets decorated with uniformly distributed gold nanoparticles. This architecture facilitates plasmon-enhanced absorption and efficient charge separation via heterojunction interfaces, significantly boosting photocurrent generation across the deep ultraviolet (DUV), visible, near-infrared (NIR), and mid-infrared (MIR) spectral regions. First-principles calculations support the observed broadband response, confirming bandgap narrowing induced by defects in h-BN and functionalization by gold nanoparticles. The device’s self-driven operation, wide spectral response, and durability under elevated temperatures underscore its strong potential for next-generation broadband, self-powered, and wearable sensing and optoelectronic applications. Full article

Transition metal dichalcogenide (TMD) materials have demonstrated promising potential for applications in photodetection due to their tunable bandgaps, high carrier mobility, and strong light absorption capabilities. However, limited by their intrinsic bandgaps, TMDs are unable to efficiently absorb photons with energies below the bandgap, resulting in a significant attenuation of photoresponse in spectral regions beyond the bandgap. This inherently restricts their broadband photodetection performance. By introducing metasurface structures consisting of subwavelength optical elements, localized plasmon resonance effects can be exploited to overcome this absorption limitation, significantly enhancing the light absorption of TMD films. Additionally, the heterogeneous integration process between the metasurface and two-dimensional materials offers low-temperature compatibility advantages, effectively avoiding the limitations imposed by high-temperature doping processes in traditional semiconductor devices. Here, we systematically investigate metasurface-enhanced two-dimensional MoSe₂ photodetectors, demonstrating broadband responsivity extension into the mid-infrared spectrum via precise control of metasurface structural dimensions. The optimized device possesses a wide spectrum response ranging from 808 nm to 10 μm, and the responsivity (R) and specific detection rate (D*) under 4 μm illumination achieve 7.1 mA/W and 1.12 × 10⁸ Jones, respectively. Distinct metasurface configurations exhibit varying impacts on optical absorption characteristics and detection spectral ranges, providing experimental foundations for optimizing high-performance photodetectors. This work establishes a practical pathway for developing broadband optoelectronic devices through nanophotonic structure engineering. Full article

The increasing demand for optical technologies with dynamic spectral control has driven interest in chromogenic materials, particularly for applications in tunable infrared metasurfaces. Phase-change materials such as vanadium dioxide and germanium–antimony–tellurium, for instance, have been widely used in the infrared regime. However, their reliance on thermal and electrical tuning introduces challenges such as high power consumption, limited emissivity tuning, and slow modulation speeds. Photochromic materials may offer an alternative approach to dynamic infrared metasurfaces, potentially overcoming these limitations through rapid, light-induced changes in their optical properties. This manuscript explores the potential of thiazolothiazole-embedded polymers, known for their reversible photochromic transitions and strong infrared absorption changes, for use in tunable infrared metasurfaces. The material exhibits low absorption and a strong photochromic contrast in the spectral range from 1500 ${\mathrm{cm}}^{-1}$ to 1700 ${\mathrm{cm}}^{-1}$, making it suitable for dynamic infrared light control. This manuscript reports on infrared imaging experiments demonstrating the photochromic contrast in thiazolothiazole-embedded polymer, and thereby provides compelling evidence for its potential applications in dynamic infrared metasurfaces. Full article

Spectrally selective infrared absorbers play a pivotal role in enabling optoelectronic applications such as infrared detection, thermal imaging, and photothermal conversion. In this paper, a dual-band wide-spectrum infrared selective absorber based on a metal–dielectric multilayer structure is designed. Through optimized design, the absorptance of the absorber reaches the peak values of 0.87 and 1.0 in the target bands (3–5 μm and 8–14 μm), while maintaining a low absorptance of about 0.2 in the non-working bands of 5–8 μm, with excellent spectral selectivity. By analyzing the Poynting vector and loss distribution, the synergistic mechanism of the ultra-thin metal localized enhancement effect, impedance matching, and intrinsic absorption of the material is revealed. This structure exhibits good polarization-insensitive characteristics and angle robustness within a large incident angle range, showing strong adaptability to complex optical field environments. Moreover, the proposed planarized structure design is compatible with standard fabrication processes and has good scalability, which can be applied to other electromagnetic wave bands. This research provides new design ideas and technical solutions for advanced optoelectronic applications such as radiation cooling, infrared stealth, and thermal radiation regulation. Full article

Graphene-based photodetectors exhibit relatively low spectral absorption and rapid recombination of photogenerated carriers, which can limit their response performance. On the other hand, nanostructured lead sulfide (PbS) demonstrates a wide spectral absorption range from visible to near-infrared light. High-quality and evenly distributed PbS nanofilms were synthesized by chemical bath deposition and were applied to a graphene-PbS heterostructure photodetector. The heterostructure creates an inherent electric field that extends the lifetime of photogenerated carriers, leading to enhanced device response. We achieved a high-responsivity graphene-PbS photodetector by combining the high carrier mobility of graphene and the strong infrared absorption of PbS. The photodetector exhibits a responsivity of 72 A/W at 792 nm and 5.8 A/W at 1550 nm, with a response time of less than 20 ms. The optimized device features a broad spectral response ranging from 265 nm to 2200 nm. Full article

Cyanoacrylates, known for their rapid polymerization and strong bonding capabilities, are widely used in industrial and medical applications. This study investigates the impacts of different process atmospheres with varying water and oxygen contents—air, argon, and argon/silane—on the curing and adhesion mechanisms of cyanoacrylate adhesives on oxidized copper substrates. Raman spectroscopy indicated that the curing process in argon and argon/silane atmospheres was slower compared to ambient air, likely due to the reduced moisture content of the atmosphere. However, the degree of curing and the inter- and intramolecular interactions within the adhesive volume showed no significant differences across atmospheres. X-ray photoelectron spectroscopy (XPS) and infrared reflection absorption spectroscopy (IRRAS) revealed that strong ionic interactions between cyanoacrylate and the copper surface oxide were absent in the low-moisture argon atmosphere. The introduction of silane resulted in the formation of silicon oxides and other silane-derived compounds, which probably contributed to the formation of these ionic interactions, similar to those observed in air. This study highlights the critical influence of the surrounding atmosphere on the adhesive properties of cyanoacrylates, with implications for optimizing bonding processes in various environments. Full article

Photodetectors converting light into electrical signals are crucial in various applications. The pursuit of high-performance photodetectors with high sensitivity and broad spectral range simultaneously has always been challenging in conventional semiconductor materials. Graphene, with its zero bandgap and high electron mobility, is an attractive candidate, but its low light absorption coefficient restricts its practical application in light detection. Integrating graphene with light-absorbing materials like PbS quantum dots (QDs) can potentially enhance its photodetection capabilities. Here, this work presents a broadband photodetector with enhanced sensitivity based on a graphene–PbS QD heterostructure. The device leverages the high carrier mobility of graphene and the strong light absorption of PbS QDs, achieving a wide detection range from ultraviolet to near-infrared. Employing a simple spinning method, the heterostructure demonstrates ultrahigh responsivity up to the order of 10⁷ A/W and a specific detectivity on the order of 10¹³ Jones, showcasing significant potential for photoelectric applications. Full article