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Riemerella anatipestifer is a pathogenic bacterium that causes duck serositis and meningitis, leading to significant harm to the duck industry. To escape from the host immune system, the meningitis-causing bacteria must survive and multiply in the bloodstream, relying on specific virulence factors such as capsules. Therefore, it is essential to study the genes involved in capsule biosynthesis in R. anatipestifer. In this study, we successfully constructed gene deletion mutants Δ3820 and Δ3830, targeting the GE296_RS03820 and GE296_RS03830 genes, respectively, using the RA-LZ01 strain as the parental strain. The growth kinetics analysis revealed that these two genes contribute to bacterial growth. Transmission and scanning electron microscopy (TEM and SEM) and silver staining showed that Δ3820 and Δ3830 produced the altered capsules and compounds of capsular polysaccharides (CPSs). Serum resistance test showed the mutants also exhibited reduced C3b deposition and decreased resistance serum killing. In vivo, Δ3820 and Δ3830 exhibited markedly declining capacity to cross the blood-brain barrier, compared to RA-LZ01. These findings indicate that the GE296_RS03820 and GE296_RS03830 genes are involved in CPSs biosynthesis and play a key role in the pathogenicity of R. anatipestifer. Furthermore, Δ3820 and Δ3830 mutants presented a tendency toward higher survival rates from RA-LZ01 challenge in vivo. Additionally, sera from ducklings immunized with the mutants showed cross-immunoreactivity with different serotypes of R. anatipestifer, including 1, 2, 7 and 10. Western blot and SDS-PAGE assays revealed that the altered CPSs of Δ3820 and Δ3830 resulted in the exposure of some conserved proteins playing the key role in the cross-immunoreactivity. Our study clearly demonstrated that the GE296_RS03820 and GE296_RS03830 genes are involved in CPS biosynthesis in R. anatipestifer and the capsule is a target for attenuation in vaccine development.
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Cápsulas Bacterianas , Patos , Infecciones por Flavobacteriaceae , Riemerella , Riemerella/genética , Riemerella/patogenicidad , Riemerella/metabolismo , Animales , Patos/microbiología , Cápsulas Bacterianas/genética , Cápsulas Bacterianas/metabolismo , Infecciones por Flavobacteriaceae/microbiología , Infecciones por Flavobacteriaceae/veterinaria , Enfermedades de las Aves de Corral/microbiología , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Polisacáridos Bacterianos/biosíntesis , Factores de Virulencia/genética , Eliminación de GenRESUMEN
We propose a large viewing angle integral imaging 3D display system based on a symmetrical compound lens array (SCLA). The display system comprises a high-resolution 2D display panel, an SCLA, and a light shaping diffuser. The high-resolution 2D display panel presents an elemental image array, the SCLA modulates the light rays emitted from the 2D display panel to form 3D images in space, and the light shaping diffuser eliminates the gaps between 3D pixels of the 3D images. We find that the lateral aberration is a crucial factor that affects the resolution of the reconstructed 3D image. The symmetrical structure of the SCLA enables a reduced focal length and the elimination of lateral aberration, improving the viewing angle and the 3D image resolution simultaneously. The experimental results confirm that the proposed display system increases the viewing angle to 68.6°, achieving a comparable resolution of the full field of view while maintaining a simple structure.
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OBJECTIVES: To explore the risk factors associated with cow's milk protein allergy (CMPA) in infants. METHODS: This study was a multicenter prospective nested case-control study conducted in seven medical centers in Beijing, China. Infants aged 0-12 months were included, with 200 cases of CMPA infants and 799 control infants without CMPA. Univariate and multivariate logistic regression analyses were used to investigate the risk factors for the occurrence of CMPA. RESULTS: Univariate logistic regression analysis showed that preterm birth, low birth weight, birth from the first pregnancy, firstborn, spring birth, summer birth, mixed/artificial feeding, and parental history of allergic diseases were associated with an increased risk of CMPA in infants (P<0.05). Multivariate logistic regression analysis revealed that firstborn (OR=1.89, 95%CI: 1.14-3.13), spring birth (OR=3.42, 95%CI: 1.70-6.58), summer birth (OR=2.29, 95%CI: 1.22-4.27), mixed/artificial feeding (OR=1.57, 95%CI: 1.10-2.26), parental history of allergies (OR=2.13, 95%CI: 1.51-3.02), and both parents having allergies (OR=3.15, 95%CI: 1.78-5.56) were risk factors for CMPA in infants (P<0.05). CONCLUSIONS: Firstborn, spring birth, summer birth, mixed/artificial feeding, and a family history of allergies are associated with an increased risk of CMPA in infants.
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Hipersensibilidad a la Leche , Nacimiento Prematuro , Lactante , Embarazo , Femenino , Animales , Bovinos , Recién Nacido , Humanos , Hipersensibilidad a la Leche/etiología , Estudios de Casos y Controles , Estudios Prospectivos , Nacimiento Prematuro/inducido químicamente , Factores de Riesgo , Proteínas de la LecheRESUMEN
BACKGROUND: Water deficiency is likely to become more frequent and intense as a result of global climate change, which may severely impact agricultural production in the world. The positive effects of melatonin (MEL) on alleviation drought or osmotic stress-induced water deficiency in plants has been well reported. However, the underlying mechanism of MEL on the detailed process of plant water uptake and transport under water deficiency condition remains largely unknown. RESULTS: Application of 1 µM MEL led to enhanced tolerance to water deficiency stress in maize seedlings, as evidenced by maintaining the higher photosynthetic parameters, leaf water status and plant transpiration rate. The relatively higher whole-plant hydraulic conductance (Kplant) and root hydraulic conductance (Lpr) in MEL-treated seedlings suggest that exogenous MEL alleviated water deficiency stress by promoting root water absorption. HgCl2 (aquaporin inhibitor) treatment inhibit the transpiration rate in MEL-treated plants greater than those of MEL-untreated; after recovery by dithiothreitol (DTT, anti-inhibitor), the transpiration rate in MEL-treated plants increased much higher than those of untreated plants. Moreover, under water deficiency, the transcription level of aquaporin genes was up-regulated by MEL application, and the H2O2 was less accumulated in MEL-treated root. CONCLUSIONS: Exogenous MEL promoted aquaporin activity, which contributed to the maintaining of Lpr and Kplant under short-term water deficiency. The increased water uptake and transport lead to improved water status and thus increased tolerance to PEG-induced short-term water deficiency in maize seedlings.
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Melatonina/farmacología , Transpiración de Plantas , Polietilenglicoles/administración & dosificación , Agua/metabolismo , Zea mays/fisiología , Zea mays/efectos de los fármacosRESUMEN
Aluminium (Al) is a key element that plays a major role in inhibiting plant growth and productivity under acidic soils. While lipids may be involved in plant tolerance/sensitivity to Al, the role of monogalactosyldiacylglycerol (MGDG) in Al response remains unknown. In this study, Arabidopsis MGDG synthase (AtMGD) mutants (mgd1, mgd2 and mgd3) and wild-type (Col-0) plants were treated with AlCl3; the effect of aluminium on root growth, aluminium distribution, plasma membrane integrity, lipid peroxidation, hydrogen peroxide content and membrane lipid compositions were analysed. Under Al stress, mgd mutants exhibited a more severe root growth inhibition, plasma membrane integrity damage and lipid peroxidation compared to Col-0. Al accumulation in root tips showed no difference between Col-0 and mutants under Al stress. Lipid analysis demonstrated that under Al treatment the MGDG content in all plants and MGDG/DGDG (digalactosyldiacylglycerol) remarkably reduced, especially in mutants impairing the stability and permeability of the plasma membrane. These results indicate that the Arabidopsis mgd mutants are hypersensitive to Al stress due to the reduction in MGDG content, and this is of great significance in the discovery of effective measures for plants to inhibit aluminium toxicity.
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Aluminio/toxicidad , Arabidopsis/efectos de los fármacos , Galactolípidos/metabolismo , Estrés Oxidativo/efectos de los fármacos , Contaminantes del Suelo/toxicidad , Aluminio/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Galactolípidos/genética , Galactosiltransferasas/genética , Galactosiltransferasas/metabolismo , Peroxidación de Lípido/efectos de los fármacos , Lípidos de la Membrana/metabolismo , Mutación , Raíces de Plantas/efectos de los fármacos , Raíces de Plantas/genética , Raíces de Plantas/metabolismo , Contaminantes del Suelo/metabolismoRESUMEN
Industrial robots are the main piece of equipment of intelligent manufacturing, and array-type tactile sensors are considered to be the core devices for their active sensing and understanding of the production environment. A great challenge for existing array-type tactile sensors is the wiring of sensing units in a limited area, the contradiction between a small number of sensing units and high resolution, and the deviation of the overall output pattern due to the difference in the performance of each sensing unit itself. Inspired by the human somatosensory processing hierarchy, we combine tactile sensors with artificial intelligence algorithms to simplify the sensor architecture while achieving tactile resolution capabilities far greater than the number of signal channels. The prepared 8-electrode carbon-based conductive network achieves high-precision identification of 32 regions with 97% classification accuracy assisted by a quadratic discriminant analysis algorithm. Notably, the output of the sensor remains unchanged after 13,000 cycles at 60 kPa, indicating its excellent durability performance. Moreover, the large-area skin-like continuous conductive network is simple to fabricate, cost-effective, and can be easily scaled up/down depending on the application. This work may address the increasing need for simple fabrication, rapid integration, and adaptable geometry tactile sensors for use in industrial robots.
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Tert-butylhydroquinone (tBHQ) has emerged as a promising candidate for mitigating the adverse effects of T-2-induced reproductive toxicity. The protective effects of tBHQ on rat sperm quality, testicular injury, apoptosis, and inflammation induced by T-2 toxin exposure were investigated. Histopathological examination of testicular tissues revealed severe damage in the T-2-treated group, characterized by disorganized germ cell arrangement, thinning of the convoluted seminiferous tubule walls, and significant cellular necrosis. However, tBHQ administration, either as a preventive or therapeutic measure, mitigated this structural damage. Image analysis confirmed an increase in the cross-sectional area and height of the convoluted seminiferous tubules in the tBHQ-treated groups compared to the T-2-treated group (p < 0.05), indicating tBHQ's efficacy in alleviating testicular damage. Additionally, tBHQ treatment significantly inhibited T-2-induced apoptosis of testicular tissue cells, as evidenced by the results showing reduced apoptotic cell counts and downregulation of the BAX/BCL2 ratio and caspase-3 expression (p < 0.05). tBHQ significantly increased the concentrations of the antioxidant factors SOD, CAT, TAC, and GSH-PX. Furthermore, tBHQ attenuated the inflammatory response induced by T-2 exposure, as indicated by the decreased mRNA expression of the proinflammatory cytokines Tnf, Il1, and Il10 in testicular tissue (p < 0.05). Additionally, tBHQ treatment alleviated the decline in serum testosterone induced by the T-2 and promoted testosterone synthesis gene expression, including for the genes 17ß-HSD and Cyp11a1, in rat testes (p < 0.05). These findings underscore tBHQ's role as a therapeutic agent combatting T-2-induced reproductive toxicity, highlighting its antioxidative, anti-apoptotic, and anti-inflammatory properties. Further elucidation of tBHQ's mechanisms of action may offer novel strategies for preventing and treating reproductive disorders induced by environmental toxins.
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INTRODUCTION: This study aimed to investigate the effect of electro-nape-acupuncture (ENA) on the differentiation of microglia and the secondary brain injury in rats with acute-phase intracerebral hemorrhage (ICH) through the programmed cell death protein-1/ligand-1 (PD-1/PD-L1) pathway. METHODS: A total of 27 male Sprague-Dawley rats were randomly divided into three groups: sham group, ICH group, and ENA group. The autologous blood infusion intracerebral hemorrhage model was used to study the effects of ENA by administering electroacupuncture at GB20 (Fengchi) and Jiaji (EX-B2) acupoints on 24 h after the modeling, once per day for 3 days. The neurological function damage, hematoma lesion, and inflammatory cell infiltration were measured by the beam walking test and hematoxylin-eosin staining. The expression of PD-1, PD-L1, CD86, CD206, and related cytokines around the hematoma was measured by western blot, quantitative reverse transcription polymerase chain reaction, and immunofluorescence. RESULTS: The ICH group had significant neurological deficits (p < .001), hematoma lesions, and inflammatory cell infiltration. The levels of CD86 protein, inflammatory factors tumor necrosis factors (TNF)-α, interleukin (IL)-1ß, and IL-6 were increased (p < .001), while CD206 protein was reduced (p < .01), and the number of CD86+ /CD11b+ cells was also increased (p < .001) compared to the sham group. However, after ENA intervention, there was a significant reduction in neurological function damage (p < .05), infiltration of inflammatory cells, and the expression levels of CD86+ /CD11b+ cells (p < .05), resulting in the increased expression of PD-1 protein and differentiation of M2 phenotype significantly (p < .001). CONCLUSION: The study concludes that ENA could reduce neurological function damage, inhibit the expression of pro-inflammatory cytokines, and improve the infiltration of inflammatory cells to improve secondary brain injury in acute-phase intracerebral hemorrhage rats. These effects could be related to the increased expression of PD-1 around the lesion, promoting the differentiation of microglia from M1 to M2 phenotype.
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Terapia por Acupuntura , Lesiones Encefálicas , Neoplasias Encefálicas , Ratas , Masculino , Animales , Ratas Sprague-Dawley , Receptor de Muerte Celular Programada 1/metabolismo , Microglía , Antígeno B7-H1/metabolismo , Antígeno B7-H1/farmacología , Ligandos , Hemorragia Cerebral/terapia , Hemorragia Cerebral/metabolismo , Lesiones Encefálicas/metabolismo , Neoplasias Encefálicas/patología , Citocinas/metabolismo , Diferenciación Celular , Hematoma/terapiaRESUMEN
Capacitive pressure sensors based on porous structures have been widely researched and applied to a variety of practical applications. To date, it remains a big challenge to develop a capacitive pressure sensor with a high sensitivity and good linearity over a wide pressure range. In this paper, a sensitive, flexible, porous capacitive pressure sensor was designed and manufactured by means of the "salt template method" and man-made grooves. To this aim, the size of the salt particles used for forming pores/air voids, time taken for thorough dissolution of salt particles, and the depth of the man-made groove by a pin were taken into consideration to achieve a better effect. With pores and the groove, the sensor is more liable be compressed, which will result in a dramatic decrease in distance between the two electrodes and a conspicuous increase of the effective dielectric constant. The optimize-designed sensor represents a sensitivity 6-8 times more than the sensor without the groove in the pressure range of 0-10 kPa, not to mention the sensor without pores or the groove, and it can keep good linearity within the measurement range (0-50 kPa). Besides, the sensor shows a low detection limit of 3.5 Pa and a fast response speed (≈50 ms), which makes it possible to detect a tiny applied pressure immediately. The fabricated sensor can be applied to wearable devices to monitor finger and wrist bending, and it can be used in the object identification of mechanical claws and object cutting of mechanical arms, and so on.
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Hybrid rigid-soft electronic system combines the biocompatibility of stretchable electronics and the computing capacity of silicon-based chips, which has a chance to realize a comprehensive stretchable electronic system with perception, control, and algorithm in near future. However, a reliable rigid-soft interconnection interface is urgently required to ensure both the conductivity and stretchability under a large strain. To settle this demand, this paper proposes a graded Mxene-doped liquid metal (LM) method to achieve a stable solid-liquid composite interconnect (SLCI) between the rigid chip and stretchable interconnect lines. To overcome the surface tension of LM, a high-conductive Mxene is doped for the balance between adhesion and liquidity of LM. And the high-concentration doping could prevent the contact failure with chip pins, while the low-concentration doping tends to maintain the stretchability. Based on this dosage-graded interface structure, the solid light-emitting diode (LED) and other devices integrated into the stretchable hybrid electronic system could achieve an excellent conductivity insensitive to the exerted tensile strain. In addition, the hybrid electronic system is demonstrated for skin-mounted and tire-mounted temperature-test applications under the tensile strain up to 100%. This Mxene-doped LM method aims to obtain a robust interface between rigid components and flexible interconnects by attenuating the inherent Young's modulus mismatch between rigid and flexible systems and makes it a promising candidate for effective interconnection between solid electronics and soft electronics.
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Nitrogen (N) and phosphorus (P) are two primary components of fertilizers for crop production. Coordinated acquisition and utilization of N and P are crucial for plants to achieve nutrient balance and optimal growth in a changing rhizospheric nutrient environment. However, little is known about how N and P signaling pathways are integrated. We performed transcriptomic analyses and physiological experiments to explore gene expression profiles and physiological homeostasis in the response of rice (Oryza sativa) to N and P deficiency. We revealed that N and P shortage inhibit rice growth and uptake of other nutrients. Gene Ontology (GO) analysis of differentially expressed genes (DEGs) suggested that N and Pi deficiency stimulate specific different physiological reactions and also some same physiological processes in rice. We established the transcriptional regulatory network between N and P signaling pathways based on all DEGs. We determined that the transcript levels of 763 core genes changed under both N or P starvation conditions. Among these core genes, we focused on the transcription factor gene NITRATE-INDUCIBLE, GARP-TYPE TRANSCRIPTIONAL REPRESSOR 1 (NIGT1) and show that its encoded protein is a positive regulator of P homeostasis and a negative regulator of N acquisition in rice. NIGT1 promoted Pi uptake but inhibited N absorption, induced the expression of Pi responsive genes PT2 and SPX1 and repressed the N responsive genes NLP1 and NRT2.1. These results provide new clues about the mechanisms underlying the interaction between plant N and P starvation responses.
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Flourishing in recent years, intelligent electronics is desirably pursued in many fields including bio-symbiotic, human physiology regulatory, robot operation, and human-computer interaction. To support this appealing vision, human-like tactile perception is urgently necessary for dexterous object manipulation. In particular, the real-time force perception with strength and orientation simultaneously is critical for intelligent electronic skin. However, it is still very challenging to achieve directional tactile sensing that has eminent properties, and at the same time, has the feasibility for scale expansion. Here, a fully soft capacitive omnidirectional tactile (ODT) sensor was developed based on the structure of MWCNTs coated stripe electrode and Ecoflex hemisphere array dielectric. The theoretical analysis of this structure was conducted for omnidirectional force detection by finite element simulation. Combined with the micro-spine and the hemispheric hills dielectric structure, this sensing structure could achieve omnidirectional detection with high sensitivity (0.306 ± 0.001 kPa-1 under 10 kPa) and a wide response range (2.55 Pa to 160 kPa). Moreover, to overcome the inherent disunity in flexible sensor units due to nano-materials and polymer, machine learning approaches were introduced as a prospective technical routing to recognize various loading angles and finally performed more than 99% recognition accuracy. The practical validity of the design was demonstrated by the detection of human motion, physiological activities, and gripping of a cup, which was evident to have great potential for tactile e-skin for digital medical and soft robotics.
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Robótica , Dispositivos Electrónicos Vestibles , Electrodos , Humanos , Estudios Prospectivos , TactoRESUMEN
Soft and stretchable sensors are essential to the development of electronic skin, especially their potential applications in health care and intelligent robots, which have increasingly attracted attentions. Herein, inspired by the epidermal tissue hierarchy, we propose a high-sensitivity fully soft capacitive pressure sensor with bionic spine-pillar microstructure. Benefiting from the combination of the random microscale spines and the millimeter-sized pillar array prepared based on polydimethylsiloxane, the proposed sensor exhibits a well deformability, a high sensitivity up to 2.87 k/Pa at low-pressure range, and a broad linear pressure dynamic range from 5 Pa to 100 kPa. A simple equivalent circuit model was established to demonstrate the sensing mechanism and geometric effect. For practical application demonstrations, the sensor was utilized to monitor local subtle and large movements of the skin, such as finger bending, wrist bending, swallowing, and facial muscle movements. The sensor shows a conformality with human skin to follow the skin extension closely. Furthermore, the proposed sensing strategy can provide a distinguishable tactile feedback for controlling robot arm and soft claw in various tasks, illustrating its potential applications in robotics.
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Robótica , Dispositivos Electrónicos Vestibles , Biónica , Humanos , Movimiento (Física) , TactoRESUMEN
Flexible pressure sensors have been widely applied in wearable devices, e-skin, and the new generation of robots. However, most of the current sensors use connecting wires for energy supply and signal transmission, which presents an obstacle for application scenarios requiring long endurance and large movement, especially. Flexible sensors combined with wireless technology is a promising research field for realizing efficient state sensing in an active state. Here, we designed and fabricated a soft wireless passive pressure sensor, with a fully flexible Ecoflex substrate and a multi-walled carbon nanotube/polydimethylsiloxane (MWCNT/PDMS) bilayer pyramid dielectric structure. Based on the principle of the radio-frequency resonator, the device achieved pressure sensing with a changeable capacitance. Subsequently, the effect of the pyramid density was simulated by the finite element method to improve the sensitivity. With one-step embossing and spin-coating methods, the fabricated sensor had an optimized sensitivity of 14.25 MHz/kPa in the low-pressure range. The sensor exhibited the potential for application in limb bending monitoring, thus demonstrating its value for long-term wireless clinical monitoring. Moreover, the radio frequency coupling field can be affected by approaching objects, which provides a possible route for realizing non-contact sensing in applications such as pre-collision warning.
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Continuous monitoring of physical motion, which can be successfully achieved via a wireless flexible wearable electronic device, is essential for people to ensure the appropriate level of exercise. Currently, most of the flexible LC pressure sensors have low sensitivity because of the high Young's modulus of the dielectric properties (such as PDMS) and the inflexible polymer films (as the substrate of the sensors), which don't have excellent stretchability to conform to arbitrarily curved and moving surfaces such as joints. In the LC sensing system, the metal rings, as the traditional readout device, are difficult to meet the needs of the portable readout device for the integrated and planar readout antenna. In order to improve the pressure sensitivity of the sensor, the Ecoflex microcolumn used as the dielectric of the capacitive pressure sensor was prepared by using a metal mold copying method. The Ecoflex elastomer substrates enhanced the levels of conformability, which offered improved capabilities to establish intimate contact with the curved and moving surfaces of the skin. The pressure was applied to the sensor by weights, and the resonance frequency curves of the sensor under different pressures were obtained by the readout device connected to the vector network analyzer. The experimental results show that resonant frequency decreases linearly with the increase of applied pressure in a range of 0-23,760 Pa with a high sensitivity of -2.2 MHz/KPa. We designed a coplanar waveguide-fed monopole antenna used to read the information of the LC sensor, which has the potential to be integrated with RF signal processing circuits as a portable readout device and a higher vertical readout distance (up to 4 cm) than the copper ring. The flexible LC pressure sensor can be attached to the skin conformally and is sensitive to limb bending and facial muscle movements. Therefore, it has the potential to be integrated as a body sensor network that can be used to monitor physical motion.
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With the development of the environment and human society, the removal of metal ions and dyes in wastewater treatment remains an urgent problem to solve. In this work, two biomass carbon adsorbents were synthesized by a KOH activation and carbonization route using sorghum stem and root as carbon precursors. In comparison with the samples without KOH activation, the pore structure of the KOH-activated carbon has been dramatically improved. The findings show that the specific surface areas of the adsorbents by sorghum stem (S1) and sorghum root (R1) were 948.6 and 168.1 m2 g-1, respectively. Meanwhile, the abundant OH- and COO- groups on the surface of these adsorbents endow them with negative polarity, thereby exhibiting excellent adsorption performance for removing methylene blue (MB) and Pb(II) from wastewater. The adsorption amount and removal rate of S1 were 98.1 mg g-1 and 98.08%, respectively, for MB, whereas those of R1 were 197.6 mg g-1 and 98.82% for the Pb(II) ion, respectively. Our findings offer an invaluable insight into designing and synthesizing a highly efficient sustainable adsorbent to remove MB and Pb(II) based on biomass agricultural waste.
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A new class of white luminescent materials, white-light-emitting graphene quantum dots (WGQDs), have attracted increasing attention because of their unique features and potential applications. Herein, we designed and synthesized a novel WGQDs via a solvothermal molecular fusion strategy. The modulation of chlorine doping amount and reaction temperature gives the WGQDs a single-crystalline structure and bright white fluorescence properties. In particular, the WGQDs also exhibit novel and robust white phosphorescence performance for the first time. An optimum fluorescence quantum yield of WGQDs is 34%, which exceeds the majority of reported WGQDs and other white luminescent materials. The WGQDs display broad-spectrum absorption within almost the entire visible light region, broad full width at half maximum and extend their phosphorescence emission to the entire white long-wavelength region. This unique dual-mode optical characteristic of the WGQDs originates from the synergistic effect of low-defect and high chlorine-doping in WGQDs and enlarges their applications in white light emission devices, cell nuclei imaging, and information encryption. Our finding provides us an opportunity to design and construct more advanced multifunctional white luminescent materials based on metal-free carbon nanomaterials.
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Quantum dots have innate advantages as the key component of optoelectronic devices. For white light-emitting diodes (WLEDs), the modulation of the spectrum and color of the device often involves various quantum dots of different emission wavelengths. Here, we fabricate a series of carbon quantum dots (CQDs) through a scalable acid reagent engineering strategy. The growing electron-withdrawing groups on the surface of CQDs that originated from acid reagents boost their photoluminescence wavelength red shift and raise their particle sizes, elucidating the quantum size effect. These CQDs emit bright and remarkably stable full-color fluorescence ranging from blue to red light and even white light. Full-color emissive polymer films and all types of high-color rendering index WLEDs are synthesized by mixing multiple kinds of CQDs in appropriate ratios. The universal electron-donating/withdrawing group engineering approach for synthesizing tunable emissive CQDs will facilitate the progress of carbon-based luminescent materials for manufacturing forward-looking films and devices.
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Sustainable, inexpensive, and environmentally friendly biomass waste can be exploited for large-scale production of carbon nanomaterials. Here, alkali lignin was employed as a precursor to synthesize carbon quantum dots (CQDs) with bright green fluorescence through a simple one-pot route. The prepared CQDs had a size of 1.5-3.5â nm, were water-dispersible, and showed wonderful biocompatibility, in addition to their excellent photoluminescence and electrocatalysis properties. These high-quality CQDs could be used in a wide range of applications such as metal-ion detection, cell imaging, and electrocatalysis. The wide range of biomass lignin feedstocks provide a green, low-cost, and viable strategy for producing high-quality fluorescent CQDs and enable the conversion of biomass waste into high-value products that promote sustainable development of the economy and human society.
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The compensation effect of re-watering after drought has been widely reported in various crops during different growth stages. It is considered as an important self-regulation mechanism for plants to resist abiotic stresses and also an efficient utilization of limited water resource. In this study, two rounds of re-watering after drought treatments were carried out during tuber expansion period of potato, to investigate the drought threshold of potato and explore the potential mechanisms of compensation effect with source-sink aspect. We used virus-free plantlets of "Atlantic" potato as experimental materials. Four treatments were included: sufficient water supply (W), re-watering after mild drought (D1-W), re-watering after medium drought (D2-W) and re-watering after severe drought (D3-W). The results showed that potato yield exhibited an over-compensation effect after two rounds of D1-W treatment, with water use efficiency and yield being increased by 17.5% and 6.3%, respectively, compared with the sufficient water supply. D2-W treatment had no significant effect on potato yield, but water use efficiency was increased by 8.4%, indicating a near-equivalent compensation effect. On the contrary, D3-W treatment did not show any compensation effect in yield. In addition, leaf chlorophyll content, net photosynthetic rate, and leaf area were all reduced after drought treatment, indicating a reduction in "source" size and activity. After re-watering, D1-W and D2-W treatments showed over-compensation and compensation effects through improving source supply capacity. Meanwhile, re-watering after moderate drought increased the sink activity through significantly enhancing the activities of key enzymes in tubers (sink), thus increased the average weight of tubers. In conclusion, re-watering after moderate drought stress during potato tuber expansion period had compensation and over-compensation effects on both source and sink, and thus could compensate for the drought-induced yield loss and improve water use efficiency.