Co-crystallization and Clustering Afforded Simultaneously Boosted Efficiency, Lifetime, and Color Tunability of Organic Afterglows.

Pure organic persistent room-temperature phosphorescence (p-RTP) is in urgent demand for advanced optoelectronic and bioelectronic applications. However, it remains an enormous challenge to modulate the emission colors while simultaneously boosting the phosphorescence lifetimes and efficiencies. Herein, we report the co-crystallization between melamine and cyclic imide-based non-conventional luminophores, which affords co-crystals owning multiple hydrogen bonds and effective clustering of electron-rich units, thus resulting in diverse emissive species with highly rigidified conformations and promoted spin-orbit coupling. Consequently, p-RTP co-crystals with simultaneously enhanced efficiencies and lifetimes of up to 12.0% and 898 ms, alongside remarkably improved color tunability, are obtained. These results may spur the future rational design of high-performance p-RTP materials and advance the mechanism of understanding of the origin of color-tunable phosphorescence.

Polymeric Emissive Materials Based on Dynamic Covalent Bonds.

Dynamic covalent polymers, composed of dynamic covalent bonds (DCBs), have received increasing attention in the last decade due to their adaptive and reversible nature compared with common covalent linked polymers. Incorporating the DCBs into the polymeric material endows it with advanced performance including self-healing, shape memory property, and so forth. However, the emissive ability of such dynamic covalent polymeric materials has been rarely reviewed. Herein, this review has summarized DCBs-based emissive polymeric materials which are classified according to the different types of DCBs, including imine bond, acylhydrazone bond, boronic ester bond, dynamic C-C bond, as well as the reversible bonds based on Diels-Alder reaction and transesterification. The mechanism of chemical reactions and various stimuli-responsive behaviors of DCBs are introduced, followed by typical emissive polymers resulting from these DCBs. By taking advantage of the reversible nature of DCBs under chemical/physical stimuli, the constructed emissive polymeric materials show controllable and switchable emission. Finally, challenges and future trends in this field are briefly discussed in this review.

Icariin promotes mouse Leydig cell testosterone synthesis via the Esr1/Src/Akt/Creb/Sf-1 pathway.

Icariin (ICA), extracted from Epimedium, is a flavonoid used in traditional Chinese medicine. Di(2-ethylhexyl) phthalate (DEHP) is a phthalate used in commercial products as a plasticizer that can influence the human endocrine and reproduction system. We previously found that ICA reversed DEHP-induced damage through the prevention of reactive oxygen species accumulation and promotion of testosterone secretion. Here we investigated the mechanisms of ICA in promoting testosterone secretion from murine Leydig cells. We used ICA, DEHP, the Akt agonist SC-79, the Akt inhibitor MK2206, and the Creb inhibitor KG501 to determine the effect of these treatments on the expression levels of the steroidogenic enzymes, Cyp11a1 and Hsd3b, which play critical roles in androgen production, in Leydig cells. Bioinformatic analysis was used to search for ICA-targeted proteins and their associated pathways. We found that icariin interacted with estrogen receptor on the cell membrane, leading to increased phosphorylation levels of Akt and Creb proteins and enhanced transcription of genes encoding steroidogenic enzymes and testosterone synthesis. We further investigated ICA activity in vivo using male mice pretreated with 100 mg/kg ICA and then treated with 750 mg/kg DEHP. ICA pretreatment reversed the reduced protein expression levels of Cyp11a1 and Hsd3b induced by DEHP in Leydig cells in vivo. Furthermore, while the phosphorylation levels of Akt and Creb were decreased in testes of mice exposed to DEHP alone, these effects were reversed by ICA pretreatment. These findings indicate that ICA promotes testosterone synthesis via the Esr1/Src/Akt/Creb/Sf-1 signaling pathway.

Halogen Bonded Chiral Emitters: Generation of Chiral Fractal Architecture with Amplified Circularly Polarized Luminescence.

Self-assembled chiroptical materials have attracted considerable attention due to their great applications in wide fields. During the chiral self-assembly, it remains unknown how achiral molecules can affect the assembly process and their final chiroptical performance. Herein, we report an achiral molecule directed chiral self-assembly via halogen bonds, exhibiting not only an unprecedented chiral fractal architecture but also significantly amplified circularly polarized luminescence (CPL). Two axially chiral emitters with halogen bond sites co-assemble with an achiral 1,4-diiodotetrafluorobenzene (F4 DIB) and well-ordered chiral fractal structures with asymmetry amplification are obtained. The enhancement of the dissymmetry factors of the assemblies was up to 0.051 and 0.011, which was approximately 100 folds than those of the corresponding molecules. It was found that both the design of the chiral emitter and the highly directional halogen bond played an important role in hierarchically chirality transfer from chiral emitters to the micrometer scale chiral fractal morphology and amplified dissymmetry factors. We hope that this strategy can give a further insight into the fabrication of structurally unique featured highly efficient chiroptical materials.

Effective Internal and External Modulation of Nontraditional Intrinsic Luminescence.

The rational modulation of the nontraditional intrinsic luminescence (NTIL) of nonconventional luminophores remains difficult, on account of the limited understanding on the structure-property relationships and emission mechanisms. Herein, the effective modulation of NTIL is demonstrated based on a group of nonaromatic anhydrides and imides. Mutual bridging of isolated subgroups effectively promotes intramolecular through-space conjugation (TSC), leading to red-shifted emission, enhanced efficiency, and prolonged persistent room-temperature phosphorescence (p-RTP). The substitution of heteroatoms from oxygen to nitrogen drastically changes the TSC and enhances intermolecular interactions, resulting in enhanced emission efficiency. In addition, upon freezing, compression, or embedding into polymer matrices, the emission intensity and color remain well regulated. These results shed new light on the rational modulation of the NTIL and p-RTP of nonconventional luminophores.

An innovative strategy for control of fungus gnats using entomopathogenic nematodes alone or in combination with waterlogging.

Chive gnat (Bradysia odoriphaga) is a soil-borne pest of Chinese chives, which causes millions of dollars in yield losses per year. Traditional methods, such as chemical pesticides leave detrimental chemical residues on plants, which potentially threaten human health. To find a sustainable method of reducing the chive gnat, the authors evaluated the effects of waterlogging and the addition of entomopathogenic nematode (EPN) on reducing chive gnat in Chinese chives via three pot experiments and one field demonstration. Results indicated that increasing the duration of waterlogging markedly increases chive gnat mortality. The presence of EPN also caused chive gnat mortality to increase with exposure time. Most importantly, the combination of waterlogging and EPN had synergistic effects on chive gnat mortality; the combination led to higher mortality than using waterlogging and EPN alone. The study demonstrated that a combination of two environmental friendly methods of fungus gnat control could lead to synergistic effects, which may provide novel approaches to economic and environmentally sustainable pest management measures.Chive gnat (Bradysia odoriphaga) is a soil-borne pest of Chinese chives, which causes millions of dollars in yield losses per year. Traditional methods, such as chemical pesticides leave detrimental chemical residues on plants, which potentially threaten human health. To find a sustainable method of reducing the chive gnat, the authors evaluated the effects of waterlogging and the addition of entomopathogenic nematode (EPN) on reducing chive gnat in Chinese chives via three pot experiments and one field demonstration. Results indicated that increasing the duration of waterlogging markedly increases chive gnat mortality. The presence of EPN also caused chive gnat mortality to increase with exposure time. Most importantly, the combination of waterlogging and EPN had synergistic effects on chive gnat mortality; the combination led to higher mortality than using waterlogging and EPN alone. The study demonstrated that a combination of two environmental friendly methods of fungus gnat control could lead to synergistic effects, which may provide novel approaches to economic and environmentally sustainable pest management measures.

[Application of item response theory to immunology test questions from the comprehensive test of basic medicine].

Objective The comprehensive test is adaptable to medical integration education and is an effective way to evaluate students' performance and assess the effects of teaching reform. Given the special characteristics of the comprehensive test, this paper is designed to apply item response theory to immunology test question analysis in the comprehensive test of basic medicine, illustrating the method of applying the theory to the medical test evaluation and elaborating its role and significance in quality control of medical comprehensive test. Methods The software e-irt and SPSS were used to analyze 180 immunology test questions from the comprehensive test of basic medicine for six years. All parameters were calculated and then equated to produce characteristic curve and information function curve. Results The immunology test questions from the comprehensive test of basic medicine was of high reliability, but of lower difficulty value and discrimination value than the overall level of the comprehensive test paper. The test parameters and examinees' ability showed significant differences among the six years. The quality of certain immunology test questions did not meet the ideal standard, which is required to be analyzed. Conclusion Medical integration education facilitates the process of our students acquiring immunology knowledge. The item response theory can be effectively applied to comparing the papers, questions and examinees' abilities among the years on the same scale, thus presenting the existing problems in terms of question quality, teaching process and examines' abilities, improving the quality of test questions, and facilitating the establishment of a standardized examination database.

Accessing Tunable Afterglows from Highly Twisted Nonaromatic Organic AIEgens via Effective Through-Space Conjugation.

Nonaromatic, cross-conjugated, and highly twisted luminogens consisting of acylated succinimides demonstrate aggregation-induced emission characteristics along with tunable multicolor photoluminescence and afterglows in their single crystals. Effective through-space conjugation among different moieties bearing n/π electrons promote the spin-orbit coupling and intersystem crossing and lead to diverse emissive clusters with concurrently rigidified conformations, thus allowing readily tunable emissions. Derived from it, the proof-of-concept application for advanced anti-counterfeiting is illustrated. These results should spur the rational design of novel nonaromatic AIEgens, and moreover advance understandings of the non-traditional intrinsic luminescence and the origin of tunable multicolor afterglows.

Solvent polarity driven helicity inversion and circularly polarized luminescence in chiral aggregation induced emission fluorophores.

Development of functional materials capable of exhibiting chirality tunable circularly polarized luminescence (CPL) is currently in high demand for potential technological applications. Herein we demonstrate the formation of both left- and right-handed fluorescent helical superstructures from each enantiomer of a chiral tetraphenylethylene derivative through judicious choice of the solution processing conditions. Interestingly, both the aggregation induced emission active enantiomers exhibit handedness inversion of their supramolecular helical assemblies just by varying the solution polarity without any change in their molecular chirality. The resulting helical supramolecular aggregates from each enantiomer are capable of emitting circularly polarized light, thus enabling both right- and left-handed CPL from a single chiral material. The left- and right-handed supramolecular helical aggregates in the dried films have been characterized using spectroscopy, scanning electron microscopy, and transmission electron microscopy techniques. These new chiral aggregation induced emission compounds could find applications in devices where CPL of opposite handedness is required from the same material and would facilitate our understanding of the formation of helical assemblies with switchable supramolecular chirality.

Clustering-Triggered Efficient Room-Temperature Phosphorescence from Nonconventional Luminophores.

Pure organic room-temperature phosphorescence (RTP) and luminescence from nonconventional luminophores have gained increasing attention. However, it remains challenging to achieve efficient RTP from unorthodox luminophores, on account of the unsophisticated understanding of the emission mechanism. Herein, we propose a strategy to realize efficient RTP in nonconventional luminophores through incorporation of lone pairs together with clustering and effective electronic interactions. The former promotes spin-orbit coupling and boosts the consequent intersystem crossing, whereas the latter narrows energy gaps and stabilizes the triplets, thus synergistically affording remarkable RTP. Experimental and theoretical results of urea and its derivatives verify the design rationale. Remarkably, RTP from thiourea solids with unprecedentedly high efficiency of up to 24.5 % is obtained. Further control experiments testify the crucial role of through-space delocalization on the emission. These results will spur the future fabrication of nonconventional phosphors and advance the understanding of the underlying emission mechanism.

Achieving Persistent, Efficient, and Robust Room-Temperature Phosphorescence from Pure Organics for Versatile Applications.

Pure organic persistent room-temperature phosphorescence (p-RTP) under ambient conditions is attractive but challenging due to the slow intersystem crossing process and susceptibility of triplet excitons. Fabrication of pure organic RTP luminogens with simultaneously high efficiency and ultralong lifetime still remains a daunting job, owing to their conflicting requirements for the T1 nature of (n,π*) and (π,π*) characteristics, respectively. Herein, a group of amide-based derivatives with efficient p-RTP is developed through the incorporation of spin-orbital-coupling-promoting groups of carbonyl and aromatic π units, giving impressive p-RTP with lifetime and efficiency of up to 710.6 ms and 10.2%, respectively. Furthermore, two of the luminogens demonstrate intense p-RTP after vigorous mechanical stimulation, indicating their robust nature, which is rarely encountered. Efficient and robust p-RTP even in the amorphous state endows them promising potential for encryption and bioimaging with facile fabrication processes. A bioimaging study with live mice indicates that such highly robust p-RTP is tremendously beneficial for in vivo afterglow imaging with an ultrahigh signal-to-background ratio of 428. These results strongly imply the possibility of realizing efficient and robust p-RTP from pure organics even without meticulous protection, thus paving the way to their promising and versatile applications.

Emission and Emissive Mechanism of Nonaromatic Oxygen Clusters.

Nonaromatic luminophores without remarkable conjugates have aroused great attention. Their emission mechanism, however, remains an open question. Meanwhile, previous studies generally focus on aliphatic amine and/or carbonyl-containing systems; those with merely oxygen moieties (i.e., ether, hydroxyl) are scarcely touched. Recently, the clustering-triggered emission (CTE) mechanism is proposed to rationalize the emission of nonconventional luminophores, according to which compounds bearing purely oxygen moieties can also be emissive. To check this conjecture, herein, both nonaromatic compound of xylitol and polymers of PEG and F127 are studied, which are found to be emissive in concentrated solutions and solids. Furthermore, cryogenic-persistent phosphorescence of the compounds and even persistent room temperature phosphorescence of xylitol crystals are observed. Additionally, their potential application as Fe3+ sensors is demonstrated. These results not only verify the rationality of the CTE mechanism but also suggest the possibility to discover and design new luminophores according to it.