Stimulating Phonon Bottleneck Effect in Organic Semiconductors by Charge-Transfer-Mediated J-Aggregation.

Hot carriers rapidly lose kinetic energies on a subpicosecond time scale, posing significant limitations on semiconductors' photon-conversion efficiencies. To slow the hot carrier cooling, the phonon bottleneck effect is constructed prevalently in quantum-confined structures with discrete energy levels. However, the maximum energy separation (ΔEES) between the energy levels is in a range of several hundred meV, leading to unsatisfactory cooling time. To address this, we design a novel organic semiconductor capable of forming intermolecular charge transfer (CT) in J-aggregates, where the lowest singlet excited state (S1) splits into two states due to the significant interplay between the Coulomb interaction and intermolecular CT coupling. The ΔEES between the two states can be adjusted up to 1.02 eV, and an extremely slow carrier cooling process of ∼72.3 ps was observed by femtosecond transient absorption spectroscopy. Moreover, the phonon bottleneck effect was identified in organic materials for the first time, and CT-mediated J-aggregation with short-range interactions was found to be the key to achieving large ΔEES. The significantly prolonged carrier cooling time, compared to <100 fs in the isolated molecule (10-6 M), highlights the potential of organic molecules with diversified aggregation structures in achieving long-lived hot carriers. These findings provide valuable insights into the intrinsic photophysics of electron-phonon scattering in organic semiconductors.

High-Quality Circularly Polarized Organic Afterglow from Nonconjugated Amorphous Chiral Copolymers.

Organic materials featuring circularly polarized luminescence (CPL) and/or afterglow emission represent an active research frontier with promising applications in various fields, but the achievement of high-performance CPL organic afterglow (CPOA) remains a huge challenge due to the intrinsic contradictions between the luminescent lifetime/dissymmetry factor (glum) and phosphorescent quantum efficiency (PhQY). Herein, we report a simple and universal approach to design efficient CPOA from amorphous copolymers by incorporating chiral chromophores into a nonconjugated clusterization-triggered emissive polymer with plenty of hydron-bonding interactions, followed by aggregation engineering using water dissolution and evaporation. With this chiral copolymerization and aggregation engineering (CCAE) strategy, high-performance CPOA polymers with PhQYs of up to 6.32%, ultralong lifetimes of over 650 ms, glum values of 3.54 × 10-3, and the highest figure-of-merit were achieved at room temperature. Given the impressive CPOA performance of these polymers, the applications in multilevel data anticounterfeiting and reversible displays with high stability were demonstrated. These findings through the CCAE strategy to overcome the inherent restraints of CPOA materials lay the foundation for the development of amorphous polymers with superior CPOA, significantly expanding the understanding of CPL and the design of organic afterglow materials.

Highly Efficient and Robust Full-Color Organic Afterglow through 2D Superlattices Embedment.

Purely organic afterglow (POA) originating from the slow radiative decay of stabilized triplet excited states has shown amazing potential in many fields. However, achieving highly stable POA with high phosphorescent quantum yield (PhQY) and long lifetime is still a formidable challenge owing to the intrinsically active and sensitive nature of triplet excitons. Here, triplet excitons of phosphors are protected and stabilized by embedding in tricomponent trihapto self-assembled 2D hydrogen-bonded superlattices, which not only enables deep-blue POA with high PhQY (up to 65%), ultralong lifetime (over 1300 ms) and the highest figure-of-merit at room temperature, but also achieves excellent stability capable of resisting quenching effects of oxygen, solvent, pressure, light, and heat. In addition, the POA color is tuned from deep-blue to red via efficient Förster resonance energy transfer from the deep-blue POA emitters to the fluorophores. Moreover, with the high-performance, robust, and full-color POA materials, flexible anti-counterfeit displays and direct-current (DC)-driven lifetime-encrypted color Morse Code applications are facilely realized.

On-demand modulating afterglow color of water-soluble polymers through phosphorescence FRET for multicolor security printing.

Developing full-color organic ultralong room temperature phosphorescence (OURTP) materials with continuously variable afterglow emission is of considerable practical importance in diverse optoelectronic applications but remains a formidable challenge. Here, we present an effective strategy for on-demand engineering of afterglow color in water-soluble polymeric systems via efficient phosphorescence Förster resonance energy transfer. Using a blue afterglow emitting water-soluble polymer as host and a series of fluorescent emitters with varied emissive colors as guests, afterglow emission is rationally modulated, conferring the full-color afterglow emission ranging from blue to red and even white with ultralong lifetimes up to 4.2 s and photoluminescence quantum yields of 36%.These water-soluble multicolor-emitting polymeric afterglow systems can function as OURTP security inks, and multilevel information encryption was successfully established by RGB-based multicolor security printing. These results present important guidance in developing high-performance afterglow polymers with on-demand color tuning ability for remarkable optoelectronic applications.

Research Advances in Hierarchically Structured PVDF-Based All-Organic Composites for High-Energy Density Capacitors.

Polymer film capacitors have been widely applied in many pulsed power fields owing to their fastest energy-released rates. The development of ferroelectric polyvinylidene fluoride (PVDF)-based composites has become one of the hot research directions in the field of high-energy storage capacitors. Recently, hierarchically-structured all-organic composites have been shown to possess excellent comprehensive energy storage performance and great potential for application. In this review, most research advances of hierarchically-structured all-organic composites for the energy storage application are systematically classified and summarized. The regulating strategies of hierarchically structured all-organic composites are highlighted from the perspective of preparation approaches, tailored material choices, layer thicknesses, and interfaces. Systematic comparisons of energy storage abilities are presented, including electric displacement, breakdown strength, energy storage density, and efficiency. Finally, we present the remaining problems of hierarchically structured all-organic composites and provide an outlook for future energy storage applications.

Overexpression of a Cotton Aquaporin Gene GhTIP1;1-like Confers Cold Tolerance in Transgenic Arabidopsis.

Cold stress can significantly affect the development, yield, and quality of crops and restrict the geographical distribution and growing seasons of plants. Aquaporins are the main channels for water transport in plant cells. Abiotic stresses such as cold and drought dehydrate cells by changing the water potential. In this study, we cloned a gene GhTIP1;1-like encodes tonoplast aquaporin from the transcriptome database of cotton seedlings after cold stress. Expression analysis showed that GhTIP1;1-like not only responds to cold stress but was also induced by heat, drought and salt stress. Subcellular localization showed that the protein was anchored to the vacuole membrane. Promoter deletion analysis revealed that a MYC motif within the promoter region of GhTIP1;1-like were the core cis-elements in response to low temperature. Virus-induced gene silencing (VIGS) and histochemical staining indicate that GhTIP1;1-like plays a positive role in plant cold tolerance. Overexpression of GhTIP1;1-like in Arabidopsis delayed the senescence process and enhanced the cold tolerance of transgenic plants. Compared with the wild type, the soluble protein concentration and peroxidase activity of the transgenic lines under cold stress were higher, while the malondialdehyde content was lower. In addition, the expression levels of cold-responsive genes were significantly increased in transgenic plants under cold stress. Our results indicate that GhTIP1;1-like could respond to different abiotic stresses and be positively involved in regulating the cold tolerance of cotton.

Modulating Tri-Mode Emission for Single-Component White Organic Afterglow.

Achieving single-component white organic afterglow remains a great challenge owing to the difficulties in simultaneously supporting long-lived emissions from varied excited states of a molecule for complementary afterglow. Here, an extraordinary tri-mode emission from the radiative decays of singlet (S1 ), triplet (T1 ), and stabilized triplet (T1 * ) excited states was proposed to afford white afterglow through modulating the singlet-triplet splitting energy (ΔEST ) and exciton trapping depth (ETD ). Low-lying T1 * for yellow afterglow was constructed by H-aggregation engineering with large ETD and trace isomer doping, while high-lying T1 and S1 for blue afterglow with thermally activated emission feature were realized by reducing ΔEST through donor-acceptor molecular design. Therefore, the single-component white afterglow with high efficiency of 14.1 % and a lifetime of 0.61 s was achieved by rationally regulating the afterglow intensity ratios of complementary emissions from S1 , T1 , and T1 *.

Stimuli-Responsive Deep-Blue Organic Ultralong Phosphorescence with Lifetime over 5 s for Reversible Water-Jet Anti-Counterfeiting Printing.

Organic ultralong room temperature phosphorescence (OURTP) materials with photophysical properties sensitive to external stimulus are highly attractive for advanced applications. However, most OURTP molecules are in crystal and OURTP materials with good practicability and stimulus-responsive character are hard to be achieved. Here, we report, for the first time, the highly efficient, ultralong-lived and deep-blue OURTP materials by simply doping boron phosphor into cyanuric acid host. Host-guest OURTP composites with abundant and tunable H-bond network are highly stable in air with ultralong lifetime of 5.08 s at room temperature. They are sensitive to water, which can strength the H-bond network to significantly enhance OURTP quantum yield from 16.1 % to 37.6 %. Anti-counterfeiting paper was easily prepared for water-jet printing; the jet-printed high-resolution OURTP patterns can be easily erased by solvent fuming for another printing/erasing cycle with high reversibility.

Transcriptome Analysis Reveals a Gene Expression Pattern Associated with Fuzz Fiber Initiation Induced by High Temperature in Gossypium barbadense.

Gossypium barbadense is an important source of natural textile fibers, as is Gossypium hirsutum. Cotton fiber development is often affected by various environmental factors, such as abnormal temperature. However, little is known about the underlying mechanisms of temperature regulating the fuzz fiber initiation. In this study, we reveal that high temperatures (HT) accelerate fiber development, improve fiber quality, and induced fuzz initiation of a thermo-sensitive G. barbadense variety L7009. It was proved that fuzz initiation was inhibited by low temperature (LT), and 4 dpa was the stage most susceptible to temperature stress during the fuzz initiation period. A total of 43,826 differentially expressed genes (DEGs) were identified through comparative transcriptome analysis. Of these, 9667 were involved in fiber development and temperature response with 901 transcription factor genes and 189 genes related to plant hormone signal transduction. Further analysis of gene expression patterns revealed that 240 genes were potentially involved in fuzz initiation induced by high temperature. Functional annotation revealed that the candidate genes related to fuzz initiation were significantly involved in the asparagine biosynthetic process, cell wall biosynthesis, and stress response. The expression trends of sixteen genes randomly selected from the RNA-seq data were almost consistent with the results of qRT-PCR. Our study revealed several potential candidate genes and pathways related to fuzz initiation induced by high temperature. This provides a new view of temperature-induced tissue and organ development in Gossypium barbadense.

Transcriptomic Profiling of Young Cotyledons Response to Chilling Stress in Two Contrasting Cotton (Gossypium hirsutum L.) Genotypes at the Seedling Stage.

Young cotyledons of cotton seedlings are most susceptible to chilling stress. To gain insight into the potential mechanism of cold tolerance of young cotton cotyledons, we conducted physiological and comparative transcriptome analysis of two varieties with contrasting phenotypes. The evaluation of chilling injury of young cotyledons among 74 cotton varieties revealed that H559 was the most tolerant and YM21 was the most sensitive. The physiological analysis found that the ROS scavenging ability was lower, and cell membrane damage was more severe in the cotyledons of YM21 than that of H559 under chilling stress. RNA-seq analysis identified a total of 44,998 expressed genes and 19,982 differentially expressed genes (DEGs) in young cotyledons of the two varieties under chilling stress. Weighted gene coexpression network analysis (WGCNA) of all DEGs revealed four significant modules with close correlation with specific samples. The GO-term enrichment analysis found that lots of genes in H559-specific modules were involved in plant resistance to abiotic stress. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that pathways such as plant hormone signal transduction, MAPK signaling, and plant-pathogen interaction were related to chilling stress response. A total of 574 transcription factors and 936 hub genes in these modules were identified. Twenty hub genes were selected for qRT-PCR verification, revealing the reliability and accuracy of transcriptome data. These findings will lay a foundation for future research on the molecular mechanism of cold tolerance in cotyledons of cotton.

Adaptability of the structure and biomass of Arundinaria spanostachya clonal populations grazing by wild giant pandas.

To understand the defense mechanism of Arundinaria spanostachya clonal populations in response to grazing by giant pandas, dynamic variations in A. spanostachya clonal population structure and biomass allocation in a wild giant panda habitat at the Liziping Nature Reserve were evaluated, as well as whether the clonal populations would be continuously used by the wild giant pandas. The population density of each age-class in the grazed and control plots after grazing (2014a and 2015a) was similar to that before grazing (2013a). The effects of grazing on the size-class and height-class structures were relatively lower. Before and after grazing, the perennial individuals showed the highest total biomass, followed by the biennial and annual individuals, and the maximum dry matter content in each module was found in the culm, followed by the branch and leaf. The dry matter content of A. spanostachya individuals increased as the age class increased, whereas the total water content decreased. The maximum water content allocation in the modules was observed in the culm, and no significant differences were found between the shoot and leaf. Thus, foraging by the wild giant pandas had no impact on the size-class and height-class structures and biomass allocation of A. spanostachya clonal populations, and the clonal populations have established an adaptive mechanism against grazing by giant pandas. After grazing, the A. spanostachya clonal populations showed greater self-adjustment ability to restore the status to that before grazing and, thus, continuously supply food for the giant pandas. Further management intervention of A. spanostachya clonal populations after the foraging of wild giant pandas is not needed, which has implications for understanding the impact of co-evolutionary mechanisms between giant panda and its staple bamboo species.

A cross-sectional serum investigation of a clustering hepatitis C virus infection in Southwest China.

Serum samples were collected in a village with a clustering hepatitis C virus (HCV) infection. HCV antibody, HCV RNA loads, liver function indexes, HCV envelope antibody, and neutralizing activity were assessed. Among 851 adult sera, 342 samples were positive for anti-HCV. Of these positive samples, 254 (74.3%) were HCV RNA positive (≥800 copies/mL). None of the 69 children's sera were positive for HCV antibody or RNA. Among the HCV antibody positive sera, alanine aminotransferase, and aspartate aminotransferase levels increased with the higher virus loads, but decreased when virus loads were higher than 1 × 10 6 copies/mL. HCV envelope antibody and neutralizing antibody levels increased with viral load.

Reduction of selenite to red elemental selenium by Rhodopseudomonas palustris strain N.

The trace metal selenium is in demand for health supplements to human and animal nutrition. We studied the reduction of selenite (SeO3⁻²) to red elemental selenium by Rhodopseudomonas palustris strain N. This strain was cultured in a medium containing SeO3⁻² and the particles obtained from cultures were analyzed using transmission electron microscopy (TEM), energy dispersive microanalysis (EDX) and X ray diffraction analysis (XRD). Our results showed the strain N could reduce SeO3⁻² to red elemental selenium. The diameters of particles were 80-200 nm. The bacteria exhibited significant tolerance to SeO3⁻² up to 8.0 m mol/L concentration with an EC50 value of 2.4 m mol/L. After 9 d of cultivation, the presence of SeO3²â» up to 1.0 m mol/L resulted in 99.9% reduction of selenite, whereas 82.0% (p<0.05), 31.7% (p<0.05) and 2.4% (p<0.05) reduction of SeO3⁻² was observed at 2.0, 4.0 and 8.0 m mol/L SeO3²â» concentrations, respectively. This study indicated that red elemental selenium was synthesized by green technology using Rhodopseudomonas palustris strain N. This strain also indicated a high tolerance to SeO3⁻². The finding of this work will contribute to the application of selenium to human health.