The conformational distribution and mutual interconversion of thermally activated delayed fluorescence (TADF) emitters significantly affect the exciton utilization. However, their influence on the ...photophysics in amorphous film states is still not known due to the lack of a suitable quantitative analysis method. Herein, we used temperature‐dependent time‐resolved photoluminescence spectroscopy to quantitatively measure the relative populations of the conformations of a TADF emitter for the first time. We further propose a new concept of “self‐doping” for realizing high‐efficiency nondoped OLEDs. Interestingly, this “compositionally” pure film actually behaves as a film with a dopant (quasi‐equatorial form) in a matrix (quasi‐axial form). The concentration‐induced quenching that may occur at high concentrations is thus expected to be effectively relieved. The “self‐doping” OLED prepared with the newly developed TADF emitter TP2P‐PXZ as a neat emitting layer realizes a high maximum external quantum efficiency of 25.4 % and neglectable efficiency roll‐off.
Until now, the influence of the conformational distribution on the photophysics and device performance of thermally activated delayed fluorescence (TADF) emitters has not been clear. Herein, conformational populations in disordered solid states are quantitatively measured for the first time. A high‐performance “self‐doping” OLED with a maximum external quantum efficiency of 25.4 % is achieved.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Thermally activated delayed fluorescence (TADF) chiral emitters attract widespread attention due to their high exciton utilization as well as potential applications. In this work, we developed a pair ...of chiral donors, (R) and (S)-9-methyl-2,9-diphenyl-9,10-dihydroacridine (PMAc), for general TADF molecular design. The enantiomers (R) and (S)-TTR-PMAc are accordingly constructed. Interestingly, they are not only TADF emitters, but also possess dual stable conformations, i.e. nearly planar and nearly orthogonal conformations. (R) and (S)-TTR-PMAc show similar physical properties under conventional non-polarized environment. While under chiroptical environments, they exhibit obvious mirror-like circular dichroism (CD) and circularly polarized luminescence (CPL) properties. Moreover, by further comparing the CPL properties originated from each conformer, we confirm that molecular conformations can significantly influence the chiroptical performance.
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•Chiral donors (R/S)-PMAc with asymmetric carbons are for TADF molecular design.•Enantiomers (R/S)-TTR-PMAc with dual conformations are designed and synthesized.•(R/S)-TTR-PMAc show TADF and CPL properties.•Chiroptical properties can be significantly influenced by molecular conformations.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The conformational distribution and mutual interconversion of thermally activated delayed fluorescence (TADF) emitters significantly affect the exciton utilization. However, their influence on the ...photophysics in amorphous film states is still not known due to the lack of a suitable quantitative analysis method. Herein, we used temperature‐dependent time‐resolved photoluminescence spectroscopy to quantitatively measure the relative populations of the conformations of a TADF emitter for the first time. We further propose a new concept of “self‐doping” for realizing high‐efficiency nondoped OLEDs. Interestingly, this “compositionally” pure film actually behaves as a film with a dopant (quasi‐equatorial form) in a matrix (quasi‐axial form). The concentration‐induced quenching that may occur at high concentrations is thus expected to be effectively relieved. The “self‐doping” OLED prepared with the newly developed TADF emitter TP2P‐PXZ as a neat emitting layer realizes a high maximum external quantum efficiency of 25.4 % and neglectable efficiency roll‐off.
Until now, the influence of the conformational distribution on the photophysics and device performance of thermally activated delayed fluorescence (TADF) emitters has not been clear. Herein, conformational populations in disordered solid states are quantitatively measured for the first time. A high‐performance „self‐doping“ OLED with a maximum external quantum efficiency of 25.4 % is achieved.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Monolayer borophene, a novel kind of two-dimensional (2D) crystal, has been receiving intensive attention owing to its atomic thickness and metallic characteristics. Rational tuning the anisotropic ...electronic transport properties is essential to the application of monolayer borophene in electronic and optoelectronic devices. Herein, we developed an oxidation strategy to tune the anisotropic transport properties of borophene by changing O-defect coverage, using density functional theory combined with the nonequilibrium Green’s function formalism. It was found that for monolayer borophene, the preferable current flowing direction between armchair and zigzag could be reversed by modulating the surface O-defect coverage between 0 and 100%. The tunable anisotropic transport properties of oxidized borophene could be attributed to the interplay among several factors, including the surface charge transfer between O-defects and borophene layer, the scattering effects related to the coverage and orientation of O-B-O interfaces, and the additional transport channels through O-defects. Our work unveils the great potential of oxidization strategy in tuning the anisotropic electronic transport properties of monolayer borophene and is of significance to its application in high-performance electronic and optoelectronic nanodevices.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
p-n heterostructure (HTS) is a fundamental component for high-performance electronic and optoelectronic device. Vertical stacking through van der Waals (vdW) force is emerging as a feasible technique ...to construct p-n HTS. Herein, we designed a novel kind of direct-bandgap C
3
N monolayer,
via
adjusting the arrangement of C and N atoms in C
3
N hexagonal cell. On the basis of the density functional theory combined with the non-equilibrium Green’s function method, we built two-dimensional vdW-contact phosphorene (BP)/C
3
N p-n HTS, and analyzed its electronic and optical properties in comparison with the inplane-jointed ones. The strong charge transfer between BP and C
3
N segments results in a wide bandgap of 0.48 eV for joint-contact type BP/C
3
N HTS, whereas the effective interlayer coupling in vdW-contact type leads to an improved light adsorption as compared to the isolated C
3
N monolayer. By fabricating dual-gated BP/C
3
N HTS field-effect transistors (FETs), the dynamic transport behaviors demonstrated that the band bending under a lower threshold voltage makes band-to-band tunneling possible for vdW-contact type. Our work suggests that vdW-contact type is superior to joint-contact type in constructing p-n HTS for high-performance electronic and optoelectronic devices.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
We established a quick and reliable method for recovering cell-free seminal DNA （cfsDNA）, by using the binding-washing-elution procedure on the DNA purification column. Low variations （below 15%） ...among the triplicate values of cfsDNA quantity verified the reproducibility of our cfsDNA recovery method. Similar cfsDNA yield and size distribution between seminal plasma acquired by filtration and centrifugation confirmed the presence of cfsDNA. To investigate the general characterization of cfsDNA, the quantitation and size distribution of cfsDNA from normozoospermic and azoospermic semen were analyzed by real-time PCR and electrophoresis, respectively. CfsDNA concentration in semen with normozoospermia （n = 11） was 1.34 ± 0.65 μg ·mL^-1, whereas a higher cfsDNA concentration was observed in azoospermia （2.56 ± 1.43 μg ·mL^-1, n = 9）. The continuous distribution of DNA fragments ranging from -1 kb to 15 kb and a spectrum of multiples of 180-bp fragments were observed in each normozoospermic and azoospermic sample. Distinct characteristic DNA ladder fragmentations in some azoospermic samples implicated that cfsDNA originate partly from apoptotic cells. CfsDNAs of 36 selected azoospermic patients with known information of Y chromosome microdeletion were subjected to the same microdeletion analysis by multiplex PCR and PCR amplification of sY114 （1 450 bp）. All multiplex PCR reactions with cfsDNA amplified successfully and provided the same result as leukocyte DNA. PCR amplification of sY114 gave a 1 450-bp amplicon as expected. Our data suggested the potential use of cfsDNA in search of biomarker or diagnostic procedures.
Background The severity of respiratory distress was associated with neonatal prognosis. This study aimed to explore the clinical characteristics, therapeutic interventions and short-term outcomes of ...late preterm or term infants who required respiratory support, and compare the usage of different illness severity assessment tools.Methods Seven neonatal intensive care units in tertiary hospitals were recruited. From November 2008 to October 2009, neonates born at ≥34 weeks＇ gestational age, admitted at 〈72 hours of age, requiring continuous positive airway pressure （CPAP） or mechanical ventilation for respiratory support were enrolled. Clinical data including demographic variables, underlying disease, complications, therapeutic interventions and short-term outcomes were collected. All infants were divided into three groups by Acute care of at-risk newborns （ACoRN） Respiratory Score 〈5, 5-8, and 〉8.Results During the study period, 503 newborn late preterm or term infants required respiratory support. The mean gestational age was （36.8±2.2） weeks, mean birth weight was （2734.5±603.5） g. The majority of the neonates were male （69.4%）, late preterm （63.3%）, delivered by cesarean section （74.8%）, admitted in the first day of life （89.3%） and outborn （born at other hospitals, 76.9%）. Of the cesarean section, 51.1% were performed electively. Infants in the severe group were more mature, had the highest rate of elective cesarean section, Apgar score 〈7 at 5 minutes and resuscitated with intubation, the in-hospital mortality increased significantly. In total, 58.1% of the patients were supported with mechanical ventilation and 17.3% received high frequency oscillation. Adjunctive therapies were commonly needed.Higher rate of infants in severe group needed mechanical ventilation or high frequency oscillation, volume expansion,bicarbonate infusion or vasopressors therapy （P 〈0.05）. The incidence of complications was also increased significantly in severe group （P 〈0.05）. The in-hospital mortality in the severe group was significantly higher than other two groups （P〈0.05）. ACoRN Respiratory Score was correlated with Score for Neonatal Acute Physiology-Version Ⅱ （SNAP-Ⅱ） （P〈0.01）. High gestational age, high SNAP-Ⅱ score and oxygenation index （OI）, and Apgar score at 5 minutes 〈5 were independent risks for death.Conclusions Neonatal respiratory distress is still a common cause of hospitalization in China. Illness severity assessment is important for the management. ACoRN Respiratory Score which correlated with SNAP-Ⅱ score is easy to use and may be helpful in facilitating the caregivers in local hospital to identify the early signs and make the transfer decision promptly.
A strain of canine parvovirus （CPV） was isolated from feces of an ill puppy in an animal hospital in Wuhan, China. It was designated as CPV/WH02/06. This isolate was identified as serotype CPV-2a by ...the hemagglutination test, CPV Ag detection strip, electron microscopy, and PCR. The vp2 gene was cloned and sequenced and assigned GenBank accession number EU377537. A 1242 bp segment of the 5＇ region of the vp2 gene was cloned and inserted into the binary vector pBI121 and used for Agrobacterium-mediated tobacco transformation. Transgenic tobacco plants were selected on MS medium supplemented with 100 μg/mL kanamycin and 100 μg/mL timentin. Integration of the vp2 gene into the tobacco genome was confirmed by PCR using T1 progeny plants, and the expression of the VP2 protein was confirmed by Western blotting
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FZAB, GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UL, UM, UPUK, VKSCE, ZAGLJ
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