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Precision assembly is one of the primary goals of robots in manufacturing. Assembly strategies combining active and passive compliant control are presented herein. In this article, we construct a high-dimensional configuration space of robot assembly and then divide the configuration space to its subspaces. We further map the active compliant motion and the passive compliant motion of the manipulator into different subspaces. In one subspace, we construct the constraint function and design the passive compliant motion of the manipulator in the constraint region, where the uncertainties of the system should be eliminated by the environment constraints. In another subspace, we design a force controller based on the low-resolution force sensory information to control the position of the robot. The proposed method avoids the design of precision mechanism systems and the usage of high-quality sensors. Several experiments pertaining to peg-in-hole insertions are conducted to demonstrate the efficiency of the proposed method. [ABSTRACT FROM AUTHOR]

Visual affordance detection is an important issue in the field of robotics and computer vision. This paper proposes a novel and practical convolutional neural network architecture that adopts an encoder-decoder architecture for pixel-wise affordance detection. The encoder network comprises two modules: a dilated residual network that is the backbone for feature extraction, and an attention mechanism that is used for modeling long-range, multi-level dependency relations. The decoder network consists of a novel up-sampling layer that maps the low-resolution encoder feature to a high-resolution pixel-wise prediction map. Specifically, integrating an attention mechanism into our network reduces the loss of salient details and improves the feature representation performance of the model. The results of experiments conducted on the University of Maryland dataset (UMD) verify that the proposed network with the attention mechanism and up-sampling layer improved performance compared with classical methods. The proposed method lays the foundation for subsequent research on multi-task learning by physical robots. [ABSTRACT FROM AUTHOR]

To design thermal fit parameters such as heating temperature and insertion force, it is generally necessary to conduct structural and thermal analyses, respectively. This study aims to build an integrated thermal assembly model to design the heating temperature and insertion force parameters simultaneously. A hierarchical multiple-kernel regression is proposed to map the two parameters and the thickness of the workpiece to the contact stress. Using the regression method, we can design the thermal fit parameters efficiently. The proposed model is validated experimentally based on two shaft-bearing assemblies. The results show that the model is capable of accurately predicting the contact stress in assembly. [ABSTRACT FROM AUTHOR]

Caging grasps provide a way to manipulate an object without full immobilization and enable dealing with the pose uncertainties of the object. Most previous works have constructed caging sets by using the geometric models of the object. This work aims to present a learning-based method for caging a novel object only with its image. A caging set is first defined using the constrained region, and a mapping from the image feature to the caging set is then constructed with kernel regression function. Avoiding the collection of large number of samples, a multi-task learning method is developed to build the regression function, where several different caging tasks are trained with a joint model. In order to transfer the caging experience to a new caging task rapidly, shape similarity for caging knowledge transfer is utilized. Thus, given only the shape context for a novel object, the learner is able to accurately predict the caging set through zero-shot learning. The proposed method can be applied to the caging of a target object in a complex real-world environment, for which the user only needs to know the shape feature of the object, without the need for the geometric model. Several experiments prove the validity of our method. [ABSTRACT FROM AUTHOR]

Developing radical‐induced afterglow emission under ambient conditions is challenging since newly formed radical species are susceptible to air and water. In this work, long afterglow materials (up to 4 s) are realized by doping a series of N,N'‐diaryl‐5,10‐dihydrophenazine (DPP)derivatives into rigid cycloaliphatic epoxy resins (CER). The afterglow is found to result from the interaction between the matrix and the excited states of the dopants through the generation of radical species under continuous UV excitation, which can be regulated by the peripheral functional groups of the N‐phenyl substituents. Density functional theory (DFT) calculations predict that the introduction of electron‐withdrawing groups hinders the afterglow emission, which may be related to the reducing reduction potential and inefficient spin‐orbit coupling (SOC) coefficients. The afterglow emission of the radical‐based systems demonstrates a bright opportunity for information encryption, anti‐counterfeiting, and photolithography. [ABSTRACT FROM AUTHOR]

For deeper understanding of the coupling of electronic processes with conformational motions, we exploit a tailored strategy to harness the excited-state planarization of N,N′-disubstituted dihydrodibenzo[a,c]phenazines by halting the structural evolution via a macrocyclization process. In this new approach, 9,14-diphenyl-9,14-dihydrodibenzo[a,c]phenazine (DPAC) is used as a prototype, in which the para sites of 9,14-diphenyl are systematically enclosed by a dialkoxybenzene-alkyl-ester or -ether linkage with different chain lengths, imposing various degrees of constraint to impede the structural deformation. Accordingly, a series of DPAC-n (n = 1-8) derivatives were synthesized, in which n correlates with the alkyl length, such that the strength of the spatial constraint decreases as n increases. The structures of DPAC-1, DPAC-3, DPAC-4, and DPAC-8 were identified by the X-ray crystal analysis. As a result, despite nearly identical absorption spectra (onset ∼400 nm) for DPAC-1-8, drastic chain-length dependent emission is observed, spanning from blue (n = 1, 2, ∼400 nm) and blue-green (n = 3-5, 500-550 nm) to green-orange (n = 6) and red (n = 7, 8, ∼610 nm) in various regular solvents. Comprehensive spectroscopic and dynamic studies, together with a computational approach, rationalized the associated excited-state structure responding to emission origin. Severing the linkage for DPAC-5 via lipase treatment releases the structural freedom and hence results in drastic changes of emission from blue-green (490 nm) to red (625 nm), showing the brightening prospect of these chemically locked DPAC-n in both fundamental studies and applications. [ABSTRACT FROM AUTHOR]

Background/Aims: Regulatory T cells (Treg) are critical regulators of asthma. Crocetin is isolated from Chinese herb saffron and is a natural carotenoid dicarboxylic acid with antiinflammatory potential. However, the effects of Crocetin on asthma as well as the underlying mechanisms have not been studied. Methods: We used Crocetin to treat mice with established ovalbumin (OVA)-induced asthma. We purified CD4+CD25+ Treg cells by flow cytometry and analyzed the levels of two immunoregulatory proteins Foxp3 and tumor necrosis factor (TNF)-alpha-induced protein 8-like 2 (TIPE2) in Treg cells. We depleted either Foxp3 or TIPE2 in mouse lung through lentivirus-mediated delivery of shRNA, and analyzed their effects on severity of asthma and Treg cells after Crocetin treatment. Results: Crocetin treatment significantly reduced the severity of an ovalbumin (OVA)-induced asthma in mice. Moreover, Crocetin significantly increased the levels of TIPE2 and Foxp3 in Treg cells and the number of Treg cells. Depletion of Foxp3 abolished the increased in Treg cells, and the effects of Crocetin on the severity of asthma, without affecting TIPE2 levels in Treg cells. On the other hand, depletion of TIPE2 abolished both the increased in Treg cells and the effects of Crocetin on the severity of asthma, through suppressing Foxp3. Conclusion: Crocetin may activate Foxp3 through TIPE2 in asthma-associated Treg cells to mitigate the severity of asthma. [ABSTRACT FROM AUTHOR]

Parallel-jaw gripper finds wide applications in various industrial sectors. In this paper, we mainly focus on the problem of form closure caging grasps of polygons with a parallel-jaw gripper equipped with four fingers. The form closure caging grasp is helpful for the fingers placements and contact region selections of a pneumatic gripper, as it is less sensitive to fingers misplacements.We firstly prove that there is always a path from a cage to a form closure grasp of the object that never breaks the cage, as long as the attractive region constructed in the configuration space has a local minimum. If such a minimum cannot be found, we further adjust the fingers arrangements to produce the form closure grasp. Meanwhile, we also develop an algorithm to compute the initial cage of the form closure grasp. Simulations of the grasping process witness the effectiveness of the above analysis results. [ABSTRACT FROM AUTHOR]

Development of a flexible low-cost robotic system to grasp various 3D workpieces is of practical important. Traditional approaches on 3D grasping usually need to compute the effective contact positions based on sufficient conditions, such as “force-closure” or “form-closure,” to prevent all the motions of the grasped objects. Compared with the previous work motivated by high-precision applications, caging provides a way to manipulate an object without needing to immobilize it. However, most caging conditions consider only 2D motions of the object in grasping. In some cases, other motions in 3D space, e.g., the pitch and roll rotations of the objects, would also possibly change a caging configuration to an uncaging configuration. This paper aims to discuss caging with frictionless contact, by taking into consideration of all the motions of the object. We first discuss the relationship between the gripper configuration and the state of the grasped object in grasping, where all the motions of the object are taken into account. We then establish the sufficient conditions to find a set of 3D caging configurations in terms of the width of the object's projection and the gap of the gripper, such that we can utilize the projection to find the feasible placements of the pins to determine the caging configuration. Furthermore, we discuss how to find the caging configuration that is capable of leading to a form-closure based on attractive region formed in the configuration space. [ABSTRACT FROM PUBLISHER]

Linked in: A rhodium(I) catalyst system [[Rh(cod)Cl]+DPPF] enables carbocyclization and chlorosulfonylation of 1,6‐enynes with sulfonyl chlorides, thus allowing the formation of three different bonds (CCl, CC, and CS) in a one‐step fashion (see scheme; cod=cyclooctadiene, DPPF=1,1′‐bis(diphenylphosphino)ferrocene). Sulfonyl chlorides are shown to be an efficient linker in this transformation, which complements other known element–element linkers. [ABSTRACT FROM AUTHOR]

Sensorless manipulation strategies have been successfully used in the precision robotic assembly. Most previous work in this area has concentrated on inserting a peg into a fixed hole. However, in some cases, e.g., the assembly of piston-peg-rod of the automotive engine, due to the motion of piston, the position of the hole in piston is hard to be fully constrained. The purpose of this paper is to give a novel sensorless manipulation strategy for the high-precision assembly of a peg into an unfixed hole. Firstly, a decomposition method of the high-dimensional configuration space of the peg hole is analyzed. Subsequently, the robotic manipulations are proposed in the two low-dimensional spaces decomposed from the high-dimensional configuration space. Then, the attractive regions formed in the two sub-spaces are constructed, thus, the position and orientation uncertainties of the peg hole can be eliminated by the attractive regions and the robotic manipulations. Finally, a typical industry application, fitting a peg into an unfixed piston rod hole of the automotive engine, is used to validate the presented strategy. [ABSTRACT FROM AUTHOR]

Parkinson's disease (PD) is a common neurological disorder worldwide, characterized by loss of dopaminergic neurons and decrease of dopamine content. Mitochondria plays an important role in the development of PD. Adenosine 5'-monophosphate-activated protein kinase (AMPK), glycogen synthase kinase 3 (GSK-3β) and protein phosphatase 2A (PP2A) are all key proteins that regulate mitochondrial metabolism and apoptosis, and they are involved in a variety of neurodegenerative diseases. Here, we aimed to explore the involvement of mitochondrial dysfunction and apoptosis in 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine hydrochloride (MPTP)-induced PD mice and MPP+ iodide-induced PC12 cells. MPTP-induced mice were subjected to behavioral testing to assess PD-like behaviors. Various molecular biological techniques including ELISA, Western blot, TUNEL assay, flow cytometry, and the important instruments Seahorse XF24 Extracellular and high performance liquid chromatography (HPLC), were used to identify the underlying molecular events of mitochondria. Treatment with the AMPK activator GSK621 dramatically ameliorated PD by increasing the levels of dopamine and rescuing the loss of dopaminergic neurons, which is dependent on the mitochondrial pathway. Moreover, regulation of AMPK/GSK-3β/PP2A pathway-related proteins by GSK621 was partially inhibited the development of PD, suggesting a negative feedback loop exists between AMPK action and mitochondrial dysfunction-mediated apoptosis. Our data preliminarily indicated that mitochondrial dysfunction and apoptosis in the pathogenesis of PD might be mediated by AMPK/GSK-3β/PP2A pathway action, which might be a promising new option for future therapy of PD. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: A novel fluorophore 1,3-bis(1,1,3-trimethyl-1H-benzo[e]indol-2(3H)-ylidene)propan-2-one (L) was synthesized and fully characterized by 1H NMR, 13C NMR, HRMS, and X-ray single-crystal structural analysis. Compound L is a pH-controlled molecular switch due to its protonation. The fluorescence change in protic polar solvents means that this compound also could be used as a protic solvent polarity sensor. Among the considered metal ions, the fluorescence of compound L could be quenched completely by Hg2+ ions with a high selectivity. Based on these fluorescence characters, this fluorescent dye L has promising applications as a multiple-mode molecular logic system. [Copyright &y& Elsevier]

A new approach in the synthesis of YBa2Cu3O7-δ (YBCO) films has been demonstrated, which uses a colloidal dispersion of nanoparticles of Y-Ba-Cu-0 as precursor. Since nanoscale particles tend to be very reactive, this precursor allows rapid processing. Moreover, since the starting composition is very similar to the final film, gaseous reaction products that cause porosity and toxicity in other methods can be minimized. This paper compares the microstructure and superconducting behavior of films prepared from nanoparticle suspensions to those fabricated by metal-organic deposition technique using trifluoroacetates. It is seen that these films show significantly reduced porosity and some enhancement in self-field critical current density (Jc). The enhancement of Jc is more significant in high magnetic fields, probably due to the nanoscale precipitates spontaneously formed. It also appears that there is scope of improving this further by adding small amounts of CeO2 nanoparticles in the precursor. However adding larger amounts may have a detrimental effect. Additional investigation on the role of nano-inclusions in flux pinning will be needed, but this work clearly shows that the use of nanoparticle colloids for making YBCO films is a very promising approach that will be scalable, non-toxic, and allow easy introduction of flux-pinning defects. [ABSTRACT FROM AUTHOR]

Studies the growth of Hg[sub 0.8]Pb[sub 0.2]Ba[sub 2]Ca[sub 2]Cu[sub 3]O[sub 8+gamma] semiconductor thick films on Ag using a modified process route. Microstructure and magnetization measurements; Magnetization hysteresis loop widths; Critical transport current of pre-pressed films.

Macrocyclic arenes have gained considerable attention for their structural diversity and widespread applications. In this research, a new kind of macrocyclic arenes, namely prism[2]dihydrophenazines (anti‐P2P20, syn‐P2P20, and P2P22), composed of two dihydrophenazine derivatives subunits bridged by methylene groups, were conveniently synthesized by AlCl3‐catalyzed one‐pot condensation in 1,2‐dichloroethane. Both anti‐P2P20 and its isomer syn‐P2P20 exhibited flexible and convertible conformation with narrow cavity, while P2P22 possessed rigid and rhombic‐like skeleton due to the more steric hindrance on subunits. In addition, the selection of electron‐deficient guest was found to influence the outside binding behavior of syn‐P2P20. Fantastic regular supramolecular tessellation was fabricated by tiling of syn‐P2P20 with tetrafluoro‐1,4‐benzoquinone (TFB) through the exo‐wall interactions. Using 1,5‐difluoro‐2,4‐dinitrobenzene (DFN) as a linker, only the regular 2D network superstructure with periodic units in a plane was obtained through cocrystallization. This work not only reports the construction of supramolecular tessellations by using prism[2]dihydrophenazines as building blocks, but also provides a new perspective for the design of macrocyclic arenes and fabrication of 2D supramolecular materials. [ABSTRACT FROM AUTHOR]

This research aimed to determine the relationships between the risk factors for nosocomial multidrug-resistant Acinetobacter baumannii (MDRAB) bacteremia and associated mortality. We analyzed 144 patients treated for A. baumannii bacteremia, including 120 patients with MDRAB bacteremia, from March 2015 to March 2020, in this retrospective study. The overall bacteremia-related mortality rate was 48.6%. The mortality rates were 25.0% and 53.3% for non-MDRAB and MDRAB bacteremia, respectively. Risk factors for the development of MDRAB bacteremia were prior use of cephalosporins [odds ratio (OR): 8.62; P  < .001], carbapenems (OR: 15.04; P  < .001), or quinolones (OR: 5.02; P  = .040); indwelling urinary catheters (OR: 21.38; P  < .001); and respiratory tract as the source of bacteremia (OR: 75.33; P  < .001). Patients with elective surgeries were inclined to develop non-MDRAB bacteremia (OR: 0.45; P  = .029). High scores in the Acute Physiology and Chronic Health Evaluation II (OR: 1.321; P  < .001) and Sequential Organ Failure Assessment (OR: 1.326; P  < .001) were risk factors for mortality from MDRAB infection. In summary, higher mortality rates occur in patients with MDRAB bacteremia, and risk factors include prior use of cephalosporins, carbapenems, or quinolones. Urinary catheters and the respiratory tract as sources of the infection increase the risk of MDRAB bacteremia. [ABSTRACT FROM AUTHOR]

A simple dynamic monitoring strategy for chiral self-assembly is achieved by confining the bent-to-planar evolution observed in N,N′-diphenyl-dihydrodibenzo[a,c]phenazine derivatives (DPAC-R/S-GLD). Besides, this approach provides a facile pathway to fabricate architectures with circularly polarized luminescence (CPL) properties. [ABSTRACT FROM AUTHOR]

Herein, two new spiro-cored hole-transporting materials (HTMs), termed HT1 and HT2, are designed and synthesized, breaking the symmetry of the classical HTM, spiro-OMeTAD, by introducing benzo[d]imidazole with diverse electron characteristics of two nitrogen atoms to improve their hole-transporting properties. Both HT1 and HT2 exhibited excellent thermal stability with glass transition temperatures (Tg) of 162 and 197 °C, respectively, and good hole transport capability with hole mobilities of 8.26 × 10−5 and 1.08 × 10−4 cm2 V−1 s−1, respectively. When utilized in green perovskite quantum dot light-emitting diodes (Pe-QLEDs), the devices achieved low turn-on voltages of 3.0 and 2.8 V, maximum external quantum efficiency (EQEmax) of 7.6 and 6.7% and high maximum luminance of 45 056 and 46 382 cd m−2, respectively. The excellent hole-transporting properties and great device performance show that HT1 and HT2 are promising HTMs for Pe-QLEDs. [ABSTRACT FROM AUTHOR]

We demonstrate that a single polycyclic π‐scaffold can undergo sequential multistep excited‐state structural evolution along the bent, planar, and twisted conformers, which coexist to produce intrinsic multiple fluorescence emissions in room‐temperature solution. By installing a methyl or trifluoromethyl group on the ortho‐site of N,N′‐diphenyl‐dihydrodibenzo[a,c]phenazine (DPAC), the enhanced steric effects change the fluorescence emission of DPAC from a dominant red band to well‐resolved triple bands. The ultra‐broadband triple emissions of ortho‐substituted DPACs range from ≈350 to ≈850 nm, which is unprecedented for small fluorophores with molecular weight of <500. Ultrafast spectroscopy and theoretical calculations clearly reveal that the above dramatic changes originate from the influence of steric hindrance on the shape of excited state potential energy surface (S1 PES). Compared to the steep S1 PES of parental DPAC, the introduction of ortho‐substituent is shown to make the path of structural evolution in S1 wider and flatter, so the ortho‐substituted derivatives exhibit slower structural transformations from bent to planar and then to twisted forms, yielding intrinsic triple emission. The results provide the proof of concept that the bent, planar, and twisted emissive states can coexist in the same S1 PES, which greatly expand the fundamental understanding of the excited‐state structural relaxation. [ABSTRACT FROM AUTHOR]

We demonstrate that a single polycyclic π‐scaffold can undergo sequential multistep excited‐state structural evolution along the bent, planar, and twisted conformers, which coexist to produce intrinsic multiple fluorescence emissions in room‐temperature solution. By installing a methyl or trifluoromethyl group on the ortho‐site of N,N′‐diphenyl‐dihydrodibenzo[a,c]phenazine (DPAC), the enhanced steric effects change the fluorescence emission of DPAC from a dominant red band to well‐resolved triple bands. The ultra‐broadband triple emissions of ortho‐substituted DPACs range from ≈350 to ≈850 nm, which is unprecedented for small fluorophores with molecular weight of <500. Ultrafast spectroscopy and theoretical calculations clearly reveal that the above dramatic changes originate from the influence of steric hindrance on the shape of excited state potential energy surface (S1 PES). Compared to the steep S1 PES of parental DPAC, the introduction of ortho‐substituent is shown to make the path of structural evolution in S1 wider and flatter, so the ortho‐substituted derivatives exhibit slower structural transformations from bent to planar and then to twisted forms, yielding intrinsic triple emission. The results provide the proof of concept that the bent, planar, and twisted emissive states can coexist in the same S1 PES, which greatly expand the fundamental understanding of the excited‐state structural relaxation. [ABSTRACT FROM AUTHOR]

A simple strategy is presented for the bifunctional detection of environmental organic vapor and temperature by utilizing H-bond interactions to trap a butterfly-vibration-based fluorophore (DPAC-OH) in a polyurethane (PU) matrix. The method opens up a new path for large-scale environmental inspections and the design of dual-response luminescent materials. [ABSTRACT FROM AUTHOR]

Optimized conditions are elaborated and applied to the reaction of various enynes bearing an N-linker and to one oxygen analogue (IV) with TosCl. [ABSTRACT FROM AUTHOR]

Objective. Creatine kinase (CK), cathepsin D (CTSD), Ki67, and tumour protein 63 (p63) have been proven to participate in the growth of some cancers. However, available literature suggested paucity of data on their involvement in oesophageal squamous-cell carcinoma (ESCC) development. Methods. We ascertained the presence of CK, CTSD, Ki67, and p63 expressions in ESCC to demonstrate the association between differentiation of ESCC and expressions of the abovementioned proteins. We collected related information on 48 patients prior to their division into well and poor differentiation groups, which were analysed retrospectively. Positive rates of protein expression were evaluated via immunohistochemistry. The proteins that were expressed positively in all the cases were selected. Comparison of the proteins within two groups was done to analyse the correlation between tumour differentiation and their expression. Results. We observed that CTSD, p63, and Ki67 were significantly and highly expressed in poorly differentiated patients with ESCC. Conclusions. This finding may suggest that the proteins were involved in ESCC progression, which may evidentially serve as potential markers of early identification and risk assessment of ESCC. [ABSTRACT FROM AUTHOR]

High thermal stability is of pivotal significance for hole transport materials (HTMs) owing to thermal evaporation and device operation stability requirements. In this study, two new HTMs, namely FCzTPA and FCzDPNA, were developed by using easily accessible carbazole/dibenzo[b,d]furan derivatives. The rigid structures bring about excellent thermal stability, with a decomposition temperature (Td) of up to 400 °C and glass transition temperature (Tg) above 190 °C. Moreover, benefiting from the twisted spatial configuration and constituent units, they both exhibit suitable triplet energy levels (ET = 2.56, 2.74 eV). When hosting red phosphorescent organic light emitting diodes (PhOLEDs), the FCzTPA-based device shows a turn-on voltage (Von) of 3.4 V and the maximum external efficiency (EQEmax) of 18.61%, indicating that the synthetic compounds are potential building blocks for highly efficient OLEDs. [ABSTRACT FROM AUTHOR]

Our previous study indicated that inhibition of NLRP1-dependent pyroptosis could decrease intracerebroventricular (ICV) injection of a protein kinase A (PKA) agonist– or streptozotocin (STZ)-induced hyperphosphorylated tau. In this study, we used a glycogen synthase kinase-3β (GSK-3β) overactivation rat model to reconfirm our previous results. ICV injection of wortmannin (WT, a PI3K inhibitor) and GF-109203X (GFX, a PKC inhibitor) was used to induce overactivation of GSK-3β in rats. We injected NLRP1 siRNA together with WT/GFX to evaluate the effect of the inhibition of NLRP1-dependent neuronal pyroptosis on hyperphosphorylated tau. Our results indicated that ICV injection of NLRP1 siRNA prevented ICV-WT/GFX-induced neuronal death, further improving the spatial memory of the rats in the Morris water maze test. ICV injection of NLRP1 siRNA downregulated the expression of ASC, caspase-1, and GSDMD and the contents of IL-1β and IL-18 in rat brains. ICV injection of NLRP1 siRNA also decreased hyperphosphorylated tau and the activity of GSK-3β. Thus, these results support our previous study that NLRP1-dependent pyroptosis could enhance hyperphosphorylation of tau protein. [ABSTRACT FROM AUTHOR]

Full colour display is vital to organic lighting-emitting diodes (OLEDs) and universal hosts for all red, green and blue (RGB) OLEDs are strongly desired. In this work, a universal bipolar host, namely BCz3PhCN, was synthesized by simply incorporating carbazole and isonicotinonitrile units. BCz3PhCN exhibits excellent thermal stability and a high triplet energy level (ET) of 2.76 eV; therefore, all RGB devices were fabricated to evaluate their electroluminescent (EL) performance. The blue device hosted by BCz3PhCN was lit at 3.0 V with the maximum external quantum efficiency (EQEmax) of 16.22%. Green PhOLEDs exhibited a better performance with the maximum luminance (Lmax) of 1 21 900 cd m−2, maximum current efficiency (ηc,max) of 69.30 cd A−1, maximum power efficiency (ηp,max) of 64.88 lm W−1 and EQEmax of 20.04%. Remarkably, the highest EQEmax of 26.84% was achieved by the red device in the low luminance range. The above excellent EL performance for all BCz3PhCN-based blue, green and red devices indicates a huge potential for BCz3PhCN as a universal host in developing high-performance monochrome and white OLEDs. [ABSTRACT FROM AUTHOR]

In this paper, two new bipolar host materials 7-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)benzo[5,6][1,4]dioxino[2,3-b]pyrazine (HF1) and 7-(4′-(9H-carbazol-9-yl)-[1,1′-biphenyl]-4-yl)benzo[5,6][1,4]dioxino[2,3-b]pyrazine (HF2) are reported through introducing dioxino[2,3-b]pyrazine as the acceptor unit and carbazole as the donor unit. The two compounds exhibit excellent thermal stability and morphological stability, and have appropriate frontier orbital energy levels. Employing HF1 and HF2 as the host, the fabricated Ir(pq)2acac-based devices exhibit intrinsic red emission at 600 nm, and the maximum brightness/maximum external quantum efficiency (EQE) reaches 49 760 cd m−2/15.1% and 57 990 cd m−2/12.8% for HF1- and HF2-hosted devices, respectively. These results show that HF1 and HF2 have huge potential in organic light-emitting diode (OLED) applications. [ABSTRACT FROM AUTHOR]

Herein, three novel bipolar host materials with D-π-A structure, termed 2CzPm , 3CzPm , and 9CzPm , were successfully synthesized by incorporating a pyrimidine moiety as an accepter and N -phenylcarbazole group as a donor through different connection sites. The three hosts exhibited good thermal stability with a glass transition temperature (T g) of 104, 103, and 102 °C, respectively. They also possessed high enough triplet energy level (E T = 2.58–2.75 eV) to be efficient hosts for red and green phosphorescent organic light-emitting diodes (PhOLEDs) (E T dopants <2.5 eV). Moreover, considerable hole and electron current density in the conventional voltage range were observed, suggesting their good bipolar transport properties. When utilized in green and red PhOLEDs, the devices hosted by 9CzPm exhibited the best electroluminescence (EL) performance with low turn-on voltages (V on) of 2.6 and 2.5 V, and maximum external quantum efficiency (EQE max) of 21.79% and 25.03%, respectively, indicating that pyrimidine moiety is a promising building block for bipolar host materials. [Display omitted] • Three novel bipolar host materials with the D-π-A structure were presented. • Using pyrimidine and pyridine units as an acceptor to facilitate electron transport. • They possess high E T of 2.58–2.75 eV to be efficient hosts for green and red PhOLEDs. • The green device hosted by 9CzPm exhibits the best performance with EQE max of 21.79%. • The red PhOLED based on 9CzPm shows V on of 2.5 V and EQE max of 25.03%, respectively. [ABSTRACT FROM AUTHOR]

Exploring the conformational evolution of organic molecules is a long-pursuit theme in the field of chemistry. Herein, interests are endeavored to unveil the conformational evolution of conformationally flexible dihydrophenazines with environment-sensitive and continuously-changeable fluorescence in the confined space exerted by the semi-rigid macrocyclic host ExBox4+. Co-crystals of the ExBox4+ and dihydrophenazines are obtained via vapor diffusion, facilitating direct clarification of the structural variations of the host and guests. The adaptive ground-state conformational evolution of the guests is fully deciphered via 1H NMR titration, crystallography analysis as well as systematic theoretical calculations. In contrast to the much smaller structural change of the well-noted conformationally adaptive host, the conformational variation in the central dihedral angle of the guest can be up to 22° in the crystal of the host-guest complex, which is completely different from the cases when ExBox4+ interacting with the rigid guests. Dynamic information encryption has been further achieved by harnessing the distinct fluorescence behaviors before and after host-guest complexation. This work not only provides new insights into the understanding of mutual interactions between a semi-rigid host and conformationally flexible guests, but also offers an alternative scheme for advanced information encryption based on the luminescent host-guest complexes. [Display omitted] • A novel host-guest system has been developed with a type of butterfly-like guests. • These molecular butterflies show conformational self-adaptivity in the confined space. • Mutual interactions between semi-rigid macrocycle and flexible guests are clarified. • Advanced information encryption is achieved based on the fluorescence change associated with the combination and dissociation. [ABSTRACT FROM AUTHOR]

Abstract: Bilinear models have been proposed to separate the factors from the observations for joint factors identification or translation tasks. However, the performance of existing bilinear models may degrade under challenging conditions when local image information cannot be obtained caused by occlusions or image noises. In this paper, a novel sub-pattern bilinear model (SpBM) is proposed. Different from existing bilinear models, SpBM constructs the sub-pattern bilinear model through a novel learning algorithm utilizing local patterns generated by dividing global patterns in a deterministic way. As a result, the specific factors of testing observation are identified by synthesizing the discriminative information provided by the local sub-patterns. To further improve the identification performance of SpBM, a new ridge regressive parameter estimation algorithm (RRPE) is also proposed. RRPE introduces the ridge regression into parameter estimation to stabilize the matrix inverse computation and alleviate the non-convergent cases. The proposed sub-pattern bilinear model is introduced into pose estimation of work-pieces to separate and estimate some key pose factors individually. Experimental results demonstrate the effectiveness of the proposed method. [Copyright &y& Elsevier]

A novel supramolecular self-assembly, where a pyridyl-substituted perylene bisimide dye (DPyPBI) axially binds to zinc phthalocyanine (ZnPc), has been designed. Their coordination properties have been studied by UV/vis, fluorescence techniques and 1H NMR spectroscopy, showing that 1:1 and 1:2 double sandwich complexes between DPyPBI and ZnPc are formed. [ABSTRACT FROM AUTHOR]

As an alternative mesenchymal stem cell- (MSC-) based therapy, MSC-derived extracellular vesicles (EVs) have shown promise in the field of regenerative medicine. We previously found that human umbilical cord mesenchymal stem cell-derived EVs (hUCMSC-EVs) improved functional recovery and nerve regeneration in a rat model of sciatic nerve transection. However, the underlying mechanisms are poorly understood. Here, we demonstrated for the first time that hUCMSC-EVs promoted the proliferation of Schwann cells by activating the PI3K/AKT signaling pathway. Furthermore, we showed that hUCMSC-EVs mediated Schwann cell proliferation via transfer of miR-21. Our findings highlight a novel mechanism of hUCMSC-EVs in treating peripheral nerve injury and suggest that hUCMSC-EVs may be an attractive option for clinical application in the treatment of peripheral nerve injury. [ABSTRACT FROM AUTHOR]

Novel polymeric metal complexes based on bis(8-hydroxyquinolinol) were synthesized by a concise route. Substitution effects on their fluorescence spectra in the solution and in the solid state were tested and discussed preliminarily. [Copyright &y& Elsevier]

Dynamically tuning the emission of circularly polarized luminescence (CPL) materials through external stimuli is fascinating because of their fundamental and application interests. In this work, light‐responsive and luminescence‐tunable CPL‐active materials are synthesized by mixing achiral helical polymer containing vibration‐induced emission (VIE) molecules and spiropyran (SP) with a chiral helical polymer. Through regulating the distinct emission of VIE molecules and the reversible photoisomerization of SP, the dynamic Förster resonance energy transfer (FRET) can be explored to reversibly control the emission color of CPL in different states after light‐controlled isomerization. This project is the first comprehensive investigation of CPL‐active materials with VIE properties. Finally, taking the advantage of the multistimuli responsive CPL signal in different states, an "INHIBIT" logic gate with CPL signal output based on the combination of control of UV/vis light irradiation time and state alternation is constructed. [ABSTRACT FROM AUTHOR]

Abstract: Pd(0)-catalyzed carboiodonation of but-3-enylcarbamic chloride has been developed with NaI as additive, which provides a ready access to substituted γ-lactam bearing an alkyl iodide group. This reaction features alkyl iodide reductive elimination as a key step in catalytic cycle, indicating the crucial role of additive NaI. [Copyright &y& Elsevier]

Herein, we introduce the cyclic 8π‐electron (C8π) molecule N,N′‐diaryl‐dihydrodibenzo[a,c]phenazine (DPAC) as a dual‐functional donor to establish a series of new donor–linker–acceptor (D–L–A) dyads DLA1–DLA5. The excited‐state bent‐to‐planar dynamics of DPAC regulate the energy gap of the donor, while the acceptors A1–A5 are endowed with different energy gaps and HOMO/LUMO levels. As a result, the rate and efficiency of the excited‐state electron transfer vs. energy transfer can be finely harnessed, which is verified via steady‐state spectroscopy and time‐resolved emission measurements. This comprehensive approach demonstrates, for the first time, the manifold of excited‐state properties governed by bifunctional donor‐based D–L–A dyads, including bent‐to‐planar, photoinduced electron transfer (PET) from excited donor to acceptor (oxidative‐PET), fluorescence resonance energy transfer (FRET), bent‐to‐planar followed by electron transfer (PFET), and PET from donor to excited acceptor (reductive‐PET). [ABSTRACT FROM AUTHOR]

Herein, we introduce the cyclic 8π‐electron (C8π) molecule N,N′‐diaryl‐dihydrodibenzo[a,c]phenazine (DPAC) as a dual‐functional donor to establish a series of new donor–linker–acceptor (D–L–A) dyads DLA1–DLA5. The excited‐state bent‐to‐planar dynamics of DPAC regulate the energy gap of the donor, while the acceptors A1–A5 are endowed with different energy gaps and HOMO/LUMO levels. As a result, the rate and efficiency of the excited‐state electron transfer vs. energy transfer can be finely harnessed, which is verified via steady‐state spectroscopy and time‐resolved emission measurements. This comprehensive approach demonstrates, for the first time, the manifold of excited‐state properties governed by bifunctional donor‐based D–L–A dyads, including bent‐to‐planar, photoinduced electron transfer (PET) from excited donor to acceptor (oxidative‐PET), fluorescence resonance energy transfer (FRET), bent‐to‐planar followed by electron transfer (PFET), and PET from donor to excited acceptor (reductive‐PET). [ABSTRACT FROM AUTHOR]

Organic fluorophores with dual‐emission and large Stokes shifts are attracting great attention due to their importance in fundamental research and technique applications. This Progress Report gives an account on how a novel luminescence mechanism termed vibration‐induced emission (VIE) is established. The VIE mechanism is coined for the rationalization of an alterable dual emission of V‐shaped N,N′‐disubstituded‐dihydribenzo[a,c]phenazines (DHPs), which are originated from a bent‐to‐planar vibration and the reverse in the excited state. The validation of the VIE mechanism is highlighted, such as the work reporting the utilization of chemically‐locked strategy to snapshot the excited‐state planarization of DHPs, and the application of the approach of steric hindrance‐induced planarization to tune the ground‐state geometry of DHPs. Moreover, the emerging applications of this VIE concept in photoelectric and biomedical disciplines are summarized. Additionally, further development of the VIE systems as well as the remaining challenges are prospected. This report could arouse wide interest from various fields to the specific area of VIE, which would not only broaden the VIE territory but also enlarge the scope of advanced functional materials. [ABSTRACT FROM AUTHOR]

Herein, we report a modular synthetic approach of (C-10 to C-13)-substituted 9,14-diaryl-9,14-dihydrodibenzo[a,c]phenazine derivatives. This synthetic route enables the aromatic substitution in a predictable and programmed manner to obtain products in synthetically useful isolated yield. [ABSTRACT FROM AUTHOR]

With the aim of generalizing the structure–properties relationship of bending heterocyclic molecules that undergo prominent photoinduced structural planarization (PISP), a series of new dihydrodibenzo[ac]phenazine derivatives in which one nitrogen atom is replaced by oxygen (PNO), sulfur (PNS), selenium (PNSe), or dimethylmethanediyl (PNC) was strategically designed and synthesized. Compounds PNO, PNS, and PNSe have significantly nonplanar geometries in the ground state, which undergo PISP to give a planarlike conformer and hence a large emission Stokes shift. A combination of femtosecond early relaxation dynamics and computational approaches established an R*→I* (intermediate)→P* sequential kinetic pattern for PNS and PNSe, whereas PNO undergoes R*→P* one‐step kinetics. The polarization ability of the substituted heteroatoms, which is in the order O

Phenothiazine derivatives based on the 10‐phenyl‐10H‐phenothiazine (NAS) chromophore, namely 7‐phenyl‐7H‐benzo[c]phenothiazine (NAS‐1) and 12‐phenyl‐12H‐benzo[a]phenothiazine (NAS‐2), were designed and synthesized. NAS‐1 and NAS‐2 are constitutional isomers with different steric strains imposed on the phenothiazine core moiety. In solution, the more‐strained NAS‐2 possesses a bent structure and undergoes photoinduced structural planarization (PISP). In the crystal, despite the absence of PISP, bent NAS‐2 exhibits prominent excimer emission as well as emission mechanochromism, which is not observed in the planar‐like NAS and NAS‐1. This unconventional observation results from the bent core structure facilitating π–π stacking of the peripheral naphthalene moieties. Two‐photon‐coupled depth‐dependent emission shows spectral differences between the surface and kernel of the NAS‐2 crystal, and is believed to be a general phenomenon, at least in part, for materials exhibiting emission mechanochromism. [ABSTRACT FROM AUTHOR]

Phenothiazine derivatives based on the 10‐phenyl‐10H‐phenothiazine (NAS) chromophore, namely 7‐phenyl‐7H‐benzo[c]phenothiazine (NAS‐1) and 12‐phenyl‐12H‐benzo[a]phenothiazine (NAS‐2), were designed and synthesized. NAS‐1 and NAS‐2 are constitutional isomers with different steric strains imposed on the phenothiazine core moiety. In solution, the more‐strained NAS‐2 possesses a bent structure and undergoes photoinduced structural planarization (PISP). In the crystal, despite the absence of PISP, bent NAS‐2 exhibits prominent excimer emission as well as emission mechanochromism, which is not observed in the planar‐like NAS and NAS‐1. This unconventional observation results from the bent core structure facilitating π–π stacking of the peripheral naphthalene moieties. Two‐photon‐coupled depth‐dependent emission shows spectral differences between the surface and kernel of the NAS‐2 crystal, and is believed to be a general phenomenon, at least in part, for materials exhibiting emission mechanochromism. [ABSTRACT FROM AUTHOR]

Abstract Three hole transport materials, FIPN- p -PCz, FIPN- p -TPA and FIPN-DPCz, incorporating fluorene/indole core with carbazole or triphenylamine unit were synthesized and fully characterized. The photophysical properties, thermal properties and electrochemical properties of these three compounds were fully investigated. The FIPN-based hole transport materials show high thermal stability (T d > 420 °C) and appropriate highest occupied molecular orbital (HOMO) level (∼-5.2 eV). Green phosphorescent organic light-emitting diodes (PhOLEDs) using these FIPN-based derivatives were fabricated to investigate the device performance, compared with NPB as the reference hole transport material. It turned out that the devices using these three compounds exhibited superior performance than that of the NPB-based PhOLED device. Especially, the FIPN- p -PCz based device showed outstanding electroluminescence performance with the maximum current efficiency and external quantum efficiency of 53.7 cd/A and 17.3%, respectively, which was almost twice that of the NPB based device. Graphical abstract Image 1 Highlights • The research was based on indole and fluorene, which is excellent hole transport moieties. • The three synthesized compounds possess high thermal stabilities, which can be used in OLED stably. • The OLEDs based on the three synthesized materials indicated much higher efficiency than NPB in the same device structure. [ABSTRACT FROM AUTHOR]

Single-molecular white-light emissions with CIE coordinates of (0.33, 0.37) and (0.33, 0.31) were achieved with DPAC-p-TPE in viscous solution and with DPAC-Tri(o1,2) in the aggregation state through the combination of vibration-induced emission (VIE) and aggregation-induced emission (AIE) mechanisms. [ABSTRACT FROM AUTHOR]

Abstract In this work, two host materials, 9-(4-(7-(9,9'-spirobi[fluoren]−2-yl)-[1,2,4]triazolo[1,5- a ]pyridin-2-yl)phenyl)−9H-carbazole (CzTPSp1) and 9-(4-(6-(9,9'-spirobi[fluoren]−2-yl)-[1,2,4]triazolo[1,5- a ]pyridin-2-yl)phenyl)−9H-carbazole (CzTPSp2) were designed and synthesized by utilizing carbazole as hole-transport units and [1,2,4]triazolo[1,5- a ]pyridine (TP) as electron-transport units. These two compounds exhibit good thermal stability, appropriate frontier orbital energy levels, high triplet energy levels, and balanced carrier transport properties. Red phosphorescent organic light-emitting devices (PhOLEDs) based on these two hosts and bis(1-phenylquinoline) (acetylacetonate)iridium (III) (Ir(pq) 2 acac) exhibit satisfactory efficiencies with the maximum external quantum efficiency (η ext, max) of 23.0% and 22.1%. To our knowledge, among the red-emitting OLEDs based on Ir(pq) 2 acac, the η ext, max (23.0%) of our device is the highest reported so far. Meanwhile, efficiency roll-off in these devices are far less obvious, at the luminance of 1000 cd m−2, the η ext of devices R1 and R2 can reach to be 22.0% and 21.6% with the efficiency roll-off value of 4.3% and 2.2%. Graphical abstract fx1 [ABSTRACT FROM AUTHOR]

Abstract A simple novel dihydrophenazine-based chemosensor R has been developed for the detection of SO 3 2− in DMSO-H 2 O solution with turn-on fluorescence. Upon the addition of sulfite, the ICT (intramolecular charge transfer) system of the probe was destroyed owing to the nucleophilic addition of sulfite to the formyl group of R. Thus a charming orange-red fluorescence centered at 603 nm appeared, which is favorable for potential biosensing. The reaction mechanism was confirmed by MS and 1H NMR titration. In addition, the detection limit for sulfite was determined as low as 71.4 nM, which is superior to many reported probes. All above results promote the probe as a promising candidate in practical and biological applications. Graphical abstract Image 1 Highlights • A simple novel dihydrophenazine-based chemosensor R has been synthesized for the detection of SO 3 2−. • The probe has a charming turn-on orange-red fluorescence centered at 603 nm. • The detection limit for sulfite was determined as low as 71.4 nM. [ABSTRACT FROM AUTHOR]

Two new organic small molecules composed of phenanthrene, carbazole and an electron deficient moiety were synthesized by a Suzuki coupling reaction. It is particularly intriguing to compare the electroluminescent (EL) properties of PBBM and PBTZ, which have the same molecular structure with the respective high Td at around 436 °C and 423 °C. By changing the electron deficient moiety of the C9-position of phenanthrene, the photophysical, electrochemical and electroluminescent properties of these two compounds showed significant differences. Furthermore, green and red phosphorescent organic light emitting diodes (OLEDs) employing PBBM and PBTZ as host materials exhibited low efficiency roll-off, and the red OLEDs based on both compounds revealed better EL performance than those of the green OLEDs. Especially, the PBBM-hosted green and red OLEDs achieved a maximum EQE of 14.3% and 18.2%, respectively. [ABSTRACT FROM AUTHOR]

By introducing pyridine, benzimidazole and triazine groups, three novel CBP derivatives host materials, 9,9'-(2-(pyridin-3-yl)-[1,1′-biphenyl]-4,4′-diyl)bis(9 H -carbazole) ( CBPPY ), 9,9'-(4''-(1- phenyl-1 H -benzo[ d ]imidazol-2-yl)-[1,1':2′,1″-terphenyl]-4,4′-diyl)bis(9 H -carbazole) ( CBPBM) and 9,9'-(3''-(4,6-diphenyl-1,3,5-triazin-2-yl)-[1,1':2′,1″-terphenyl]-4,4′-diyl)Bis (9 H -carbazole) ( CBPTZ ) were designed and synthesized. These three compounds exhibited high thermal stabilities, appropriate HOMO-LUMO energy levels and improved electroluminescent (EL) performance compared with CBP compound in Ir(ppy) 3 doped green organic light emitting diodes (OLED). In addition, devices based on CBPPY, CBPBM and CBPTZ showed lower driving voltages of 3.0, 2.6 and 2.5 V, and all devices achieved higher EL efficiencies. Especially, the CBPBM-based device reached the optimal external quantum efficiencies (EQE) of 18.9% with the maximum power efficiency (PE) of 56.7 l m/W, which suggested that CBPPY, CBPBM and CBPTZ were promising bipolar host materials for green OLEDs. [ABSTRACT FROM AUTHOR]

Abstract: Understanding excited‐state dynamics is critical for improving the photoluminescence (PL) efficiency of exciplexes. A series of exciplexes based on conventional hole‐transporting materials as donor and newly developed phenylpyridinato boron derivatives as acceptor were investigated. High PL efficiencies were achieved in only some combinations, and a large difference in performance among combinations provided insight into nonradiative processes in exciplex systems. Furthermore, the triplet local excited states (3LE) of each donor and acceptor were found play an important role in triplet exciplex harvesting. Significant contributions from triplets were clearly observed when the charge‐transfer excited states (1CT and 3CT) and 3LE were ideally aligned. We also demonstrated fine control of relative energy alignment via the concentration to improve the PL efficiency. [ABSTRACT FROM AUTHOR]