Palladium-Doped Cs2AgBiBr6 with 1300 nm Near-Infrared Photoresponse.

Lead-free halide double perovskite (HDP) Cs2AgBiBr6 has set a benchmark for research in HDP photoelectric applications due to its attractive optoelectronic properties. However, its narrow absorption range is a key limitation of this material. Herein, a novel dopant, palladium (Pd), is doped into Cs2AgBiBr6 and significantly extends the absorption to ≈1400 nm. Pd2+ ions are partially doped in the host lattice, most probably replacing Ag atoms and introducing a sub-bandgap state within the host bandgap, as indicated by the combination of spectroscopical measurements and theoretical calculations. Importantly, this sub-bandgap state extends the photoresponse of Cs2AgBiBr6 up to the NIR-II region of 1300 nm, setting a new record for HDPs. This work demonstrates a novel and efficient dopant for HDPs and highlights the effectiveness of employing a sub-bandgap to broaden the absorption of HDPs, shedding new light on tailoring large bandgap HDPs for NIR optoelectronic applications.

Chronic exposure to ammonia induces oxidative stress and enhanced glycolysis in lung of piglets.

Ammonia is one of the major environmental pollutants in the pig industry that seriously affects the airway health of pigs. In this study, we aimed to investigate the metabolic profiling changes of piglets' lung tissue after the exposure of 0 ppm (CG), 20 ppm (LG) and 50 ppm (HG) ammonia for 30 days. Compared with the control group, the obvious lung lesions were observed in HG, including interstitial thickening, inflammatory cell infiltration and focal hemorrhage. The significantly increased content of malondialdehyde in HG, combined with the significantly decreased mRNA expression of antioxidase and inflammatory-regulators in exposure groups, implied that ammonia exposure induced oxidative stress and diminished the anti-inflammatory response in lung tissues. Metabolomic analyses of lung tissues revealed 15 significantly altered metabolites among the three groups including multiple amino acids, carbohydrates and lipids. The accumulation of succinic acid, linoleic acid and phosphorylethanolamine and consumption of glucose, quinolinic acid and aspartic acid in ammonia exposure groups, indicated that energy supply from glucose aerobic oxidation was suppressed and the glycolysis and lipolysis were activated in lung tissues induced by chronic ammonia exposure.

Thermography and machine learning techniques for tomato freshness prediction.

The United States and China are the world's leading tomato producers. Tomatoes account for over $2 billion annually in farm sales in the U.S. Tomatoes also rank as the world's 8th most valuable agricultural product, valued at $58 billion dollars annually, and quality is highly prized. Nondestructive technologies, such as optical inspection and near-infrared spectrum analysis, have been developed to estimate tomato freshness (also known as grades in USDA parlance). However, determining the freshness of tomatoes is still an open problem. This research (1) illustrates the principle of theory on why thermography might be able to reveal the internal state of the tomatoes and (2) investigates the application of machine learning techniques-artificial neural networks (ANNs) and support vector machines (SVMs)-in combination with transient step heating, and thermography for freshness prediction, which refers to how soon the tomatoes will decay. Infrared images were captured at a sampling frequency of 1 Hz during 40 s of heating followed by 160 s of cooling. The temperatures of the acquired images were plotted. Regions with higher temperature differences between fresh and less fresh (rotten within three days) tomatoes of approximately uniform size and shape were used as the input nodes for ANN and SVM models. The ANN model built using heating and cooling data was relatively optimal. The overall regression coefficient was 0.99. These results suggest that a combination of infrared thermal imaging and ANN modeling methods can be used to predict tomato freshness with higher accuracy than SVM models.

[The Effects of Skin Thickness on Optical Transmission Characteristics in Fruits Tissues].

Fruit quality inspection techniques play a very important role in the production and consumption of fruits. In the field of quality non-destructive inspection and grading for fruits, the light-based techniques using optical properties of fruit products were widely used as one of the most practical and the most successful techniques. Quantitative understanding of light interaction with fruits is critical to designing better optical systems for inspection of food quality. In this paper, a fruit model consisted of two layer tissues was developed using Monte Carlo simulations to explore the light transport process and properties in the pome fruits, such as apples and mandarins, which were used as the thin-skinned and thick-skinned fruits respectively. The simulation results obtained are based on the assumption that the light source is a Gaussian beam at the wavelength 808 nm. This paper reports that the effects of skin thickness on light transmission characteristics in fruit tissues, including diffuse reflectance, transmittance, absorptivity, penetration depth etc. The inspection efficiency of flesh tissues was also demonstrated. The results indicated that the transmittance and the penetration depth decreases with the fruit skin increasing. As for the absorbed energy density, the fruit skin tissues have the wider distribution at the radial distance than the fruit flesh tissues. The absorbed energy density always tended to decrease with the inside depth of the fruit tissues increasing, especially decreased more apparently at the radial direction. The diffuse reflectance at the radial distance from 0.2 to 1.2 cm decreased with the decreasing of fruit skin, however it showed the inverse relationship in the radial distance range from 1.2 to 4.0 cm, the diffuse reflectance decreases with the increasing fruit skin. This paper proposed that the interaction between light and fruits skin in transmission or reflective approach, should be considered for developing optical techniques of non-destructive fruit quality inspection. And it provided a theoretical basis for designing more efficient optical detection device, including how to confirm the light source power, size and position of the detector, etc. It has very important significance for fruit quality inspection by optical techniques.

Enhancing Emission and Stability in Na-Doped Cs3Cu2I5 Nanocrystals.

Lead-free Cs3Cu2I5 metal halides have garnered significant attention recently due to their non-toxic properties and deep-blue emission. However, their relatively low photoluminescence quantum efficiency and poor stability have limited their applications. In this work, sodium iodide (NaI) is used to facilitate the synthesis of Cs3Cu2I5 nanocrystals (NCs), demonstrating improved photoluminescence intensity, photoluminescence quantum yield, and stability. Systematic optoelectronic characterizations confirm that Na+ is successfully incorporated into the Cs3Cu2I5 lattice without altering its crystal structure. The improved Photoluminescence Quantum Yield (PLQY) and stability are attributed to the strengthened chemical bonding, which effectively suppresses vacancy defects in the lattice. Additionally, light-emitting diodes (LEDs) based on 10% NaI-doped Cs3Cu2I5 NCs were assembled, emitting vibrant blue light with a maximum radiant intensity of 82 lux and Commission Internationale de l'Eclairage (CIE) chromaticity coordinates of (0.15, 0.1). This work opens new possibilities for commercial lighting display applications.

Lead-Free Halide Double Perovskite for High-Performance Photodetectors: Progress and Perspective.

Lead halide perovskite has become a promising candidate for high-performance photodetectors (PDs) due to its attractive optical and electrical properties, such as high optical absorption coefficient, high carrier mobility, and long carrier diffusion length. However, the presence of highly toxic lead in these devices has limited their practical applications and even hindered their progress toward commercialization. Therefore, the scientific community has been committed to searching for low-toxic and stable perovskite-type alternative materials. Lead-free double perovskite, which is still in the preliminary stage of exploration, has achieved inspiring results in recent years. In this review, we mainly focus on two types of lead-free double perovskite based on different Pb substitution strategies, including A2M(I)M(III)X6 and A2M(IV)X6. We review the research progress and prospects of lead-free double perovskite photodetectors in the past three years. More importantly, from the perspective of optimizing the inherent defects in materials and improving device performance, we propose some feasible pathways and make an encouraging perspective for the future development of lead-free double perovskite photodetectors.

A solution-processed pillar[5]arene-based small molecule cathode buffer layer for efficient planar perovskite solar cells.

A room-temperature solution-processed pillar[5]arene-based small molecule material, termed C3, has been designed, synthesized, and incorporated between a conventional PCBM electron transport layer (ETL) and a metal electrode to function as a single-layer cathode buffer layer (CBL) for efficient planar p-i-n perovskite solar cells (PVSCs). It has been found that C3 has a work function tunneling effect, which can decrease the work function of the Ag electrode; therefore, introduction of C3 successfully enhances the interface contact and reduces the interface barriers, which usually exist between fullerene derivatives and metal electrodes. It was also found that the C3 capping layer could improve the surface quality of PCBM, forming a smooth, dense and pinhole-free morphology with fewer surface defects. Thus, C3 can modify the interface between PCBM and Ag, enhance the diode properties of devices and facilitate electron transport through the devices; therefore, it is a very promising CBL material for PVSCs. A device with a hybrid PCBM ETL and a single cathode buffer layer of C3 exhibited a high power conversion efficiency (PCE) of 17.42% with negligible hysteresis, which was dramatically higher than that of a device based on a pure PCBM ETL. With the major advantages of a low-temperature solution process and interface modification, the excellent PCE of PVSCs on flexible substrates can exceed 13%. These results demonstrate that solution-processed pillar[5]arene-based small molecule materials can serve as high performance CBLs in PVSCs.

Long distance invisibility system to hide dynamic objects with high selectivity.

With the development of invisibility technology, invisibility devices have now become more practical, with properties such as working at visible wavelengths, using natural materials, and hiding macroscopic objects. Recently, the cloaking of dynamic objects was experimentally realized using ray-optics. Here, based on a phase retrieval algorithm and phase conjugation technology, we design and fabricate a system to hide dynamic objects that changes at speeds faster than 8 seconds per frame. Different from shell cloaks and carpet-like cloaks, which conceal the entire region covered by the cloak, our system works when the object is at a distance and hides only the selected part of an object when the entire object is within the working area of the system. We experimentally demonstrate the concealment of a millimeter-scale object at different wavelengths. We believe that our work may provide a new approach to hiding objects in real life and may also be applicable in biological imaging and atmospheric imaging.

Analysis of Light Transport Features in Stone Fruits Using Monte Carlo Simulation.

The propagation of light in stone fruit tissue was modeled using the Monte Carlo (MC) method. Peaches were used as the representative model of stone fruits. The effects of the fruit core and the skin on light transport features in the peaches were assessed. It is suggested that the skin, flesh and core should be separately considered with different parameters to accurately simulate light propagation in intact stone fruit. The detection efficiency was evaluated by the percentage of effective photons and the detection sensitivity of the flesh tissue. The fruit skin decreases the detection efficiency, especially in the region close to the incident point. The choices of the source-detector distance, detection angle and source intensity were discussed. Accurate MC simulations may result in better insight into light propagation in stone fruit and aid in achieving the optimal fruit quality inspection without extensive experimental measurements.

A novel autofocusing method using the angle of Hilbert space for microscopy.

Autofocusing technology is indispensable for routine use of microscopes on a large scale in biological field. The autofocusing method using the angle of Hilbert space is brought forward to measure whether the image is focused or not. The angle of Hillbert space can be used to evaluate accurately the similarity degree of two images. The experiment results show that the autofocusing method can decrease the computational cost and get accuracy for real-time biological and biomedical images with noise robustness. The focus curves are smooth and possess the unimodality, the monotonicity and the symmetry. Compared with other classic and optimum focus method, the Hilbert method demonstrates its robustness to noise and can improve the focus speed. The experiments showed that the proposed method can increase the overall performance of an autofocus system and has strong applicability in various autofocusing algorithms.