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In recent years, the frequency and intensity of exposure to heat stress have increased gradually, seriously hampering the production of maize. This paper presents a study designed to analyze how the development, physiology and dispersal of pollen from the heat‐resistant maize variety Zhengdan958 and the heat‐sensitive maize variety Xianyu335 are affected by exposure to heat stress during the tasselling stage. Our results showed That exposure to heat stress significantly increased the antioxidant enzyme activity in pollen. Upon visual inspection of the pollen, we found that the lower water content had given rise to wrinkles in the pollen surface, sunken germination pores, and morphological deformations. In addition, the anther dehiscence process was hindered, resulting in a reduced amount of pollen being dispersed. We also found elevated levels of abscisic acid (ABA), jasmonic acid (JA) and its derivatives, indole acetic acid (IAA) and gibberellin‐3 (GA3) in heat‐pollens, as well as elevated ratios of IAA to ABA and ABA to GA3. Ultimately impaired pollen fertility. Summarizing, our experiment revealed that reduced pollen quantity and quality are significant contributors to fertility losses in summer maize exposed to heat stress at anthesis, and we hope that our analysis of the physiological mechanisms involved can contribute to the development of crop management measures aimed at countering the increasingly detrimental effects of heat stress on the production of summer maize. [ABSTRACT FROM AUTHOR]

Global climate changes have led to frequent and recurrent heat stress, which has seriously affected the world maize production. The experiment presented in this paper was carried out during the maize‐growing season in 2021 and 2022 at the Huang–Huai–Hai Region Maize Science and Technology Innovation Center (36°09′N, 117°09′E) in Tai'an, Shandong province, China. The test site is located in the semi‐humid warm temperate continental monsoon climate zone, soil is brown loam. We selected different heat‐sensitive maize varieties: heat‐tolerant variety Zhengdan 958 (ZD958) and heat‐sensitive variety Xianyu335 (XY335) to study the stress effects of high temperature on the development of tassel in the key stage of its differentiation (the 12‐leaf stage, V12). We found that exposure to heat stress during the V12 stage significantly reduced the tassel size and the anther dehiscence area, making it difficult to disperse pollen, thus effectively reducing pollen production. In addition, heat stress had significant negative effects on pollen development, resulting in deformed pollen and lower pollen viability and germination rate. Our results also showed that heat stress significantly increased the activities of key reactive oxygen species‐scavenging enzymes including superoxide dismutase, peroxidase and catalase, and that the malondialdehyde and H2O2 content in tassels exposed to heat stress were significantly higher than those control group, where it should be noted that for the XY335, these effects were more pronounced than for the ZD958. The endogenous hormone content of tassels exhibited a variety of responses. After heat stress, the zeatin and salicylic acid content in tassels of both maize varieties were significantly lower than those in the respective control groups, while the abscisic acid and gibberellin acid content were significantly higher. With respect to the jasmonic acid and 3‐indoleacetic acid content, the two maize varieties exhibited opposite responses: in tassels from ZD958 plants subjected to heat stress were higher than those in the respective control group, while in tassels from XY335 plants, they were lower. The observed changes in protective enzyme activities and endogenous hormone contents induced by heat stress significantly affected the development of maize tassels and significantly reduced the amount, activity and germination rate of pollen. [ABSTRACT FROM AUTHOR]

Device simplification is of practical significance for organic light emitting diodes (OLEDs), and remains the great challenge for deep‐red emitters. Herein, a deep‐red thermally activated delayed fluorescence molecule (pTPA‐DPPZ) is reported which features a T shaped structure containing two triphenylamine (TPA) donors, one either side of a planar dipyridophenazine (DPPZ) acceptor. The rational spatial arrangement of the functional groups leads to limited but sufficient molecular packing for effective carrier transport. The neat pTPA‐DPPZ film achieves an around 90‐fold improved radiation rate constant of 107 s−1 and the nearly unitary reverse intersystem crossing (RISC) efficiency, as well as accelerated emission decays for quenching suppression. The high radiation and RISC result in a photoluminescence quantum yield of 87 %. The bilayer OLED based on the pTPA‐DPPZ emissive layer achieved the record external quantum efficiencies of 12.3 % for maximum and 10.4 % at 1000 nits, accompanied by the deep‐red electroluminescence with the excellent color purity. [ABSTRACT FROM AUTHOR]

Device simplification is of practical significance for organic light emitting diodes (OLEDs), and remains the great challenge for deep‐red emitters. Herein, a deep‐red thermally activated delayed fluorescence molecule (pTPA‐DPPZ) is reported which features a T shaped structure containing two triphenylamine (TPA) donors, one either side of a planar dipyridophenazine (DPPZ) acceptor. The rational spatial arrangement of the functional groups leads to limited but sufficient molecular packing for effective carrier transport. The neat pTPA‐DPPZ film achieves an around 90‐fold improved radiation rate constant of 107 s−1 and the nearly unitary reverse intersystem crossing (RISC) efficiency, as well as accelerated emission decays for quenching suppression. The high radiation and RISC result in a photoluminescence quantum yield of 87 %. The bilayer OLED based on the pTPA‐DPPZ emissive layer achieved the record external quantum efficiencies of 12.3 % for maximum and 10.4 % at 1000 nits, accompanied by the deep‐red electroluminescence with the excellent color purity. [ABSTRACT FROM AUTHOR]

The elongation factor Tu (EF-Tu) receptor (EFR) in cruciferous plants specifically recognizes the N-terminal acetylated elf18 region of bacterial EF-Tu and thereby activates plant immunity. It has been demonstrated that Arabidopsis EFR confers broad-spectrum bacterial resistance in the EFR transgenic solanaceous plants. Here, the transgenic rice plants (Oryza sativa L. ssp. japonica cv. Zhonghua 17) and cell cultures with constitutive expression of AtEFR were developed to investigate whether AtEFR senses EF-Tu and thus enhances bacterial resistance in the monocot plants. We demonstrated that the Xanthomonas oryzae-derived elf18 peptide induced oxidative burst and mitogen-activated protein kinase activation in the AtEFR transgenic rice cells and plants, respectively. Pathogenesis-related genes, such as OsPBZ1, were upregulated dramatically in transgenic rice plant and cell lines in response to elf18 stimulation. Importantly, pretreatment with elf18 triggered strong resistance to X. oryzae pv. oryzae in the transgenic plants, which was largely dependent on the AtEFR expression level. These plants also exhibited enhanced resistance to rice bacterial brown stripe, but not to rice fungal blast. Collectively, the results indicate that the rice plants with heterologous expression of AtEFR recognize bacterial EF-Tu and exhibit enhanced broad-spectrum bacterial disease resistance and that pattern recognition receptor-mediated immunity may be manipulated across the two plant classes, dicots and monocots. [ABSTRACT FROM AUTHOR]

ABSTRACT A July-May precipitation reconstruction for the period AD 1816-2010 was developed from a tree-ring width chronology of Picea wilsonii for the Xinglong Mountains area of Lanzhou. The reconstruction explains 55.8% of the actual precipitation variance during the calibration period from 1951 to 2010. Wet conditions prevailed during the periods 1822-1835, 1843-1858, 1870-1877, 1884-1891, 1911-1921, 1933-1938, 1944-1979 and 2009-2010. Dry episodes occurred during 1816-1821, 1836-1842, 1859-1869, 1878-1883, 1892-1910, 1922-1932, 1939-1943 and 1980-2008. Multi-taper method spectral analysis indicates the existence of some significant peaks at 2.8, 3.0 and 3.5 years. Spatial correlations with gridded land surface precipitation data revealed that our reconstruction represents regional precipitation signal for a large area of North China linked to the East Asian summer monsoon (EASM). Comparison with other tree-ring-based precipitation/drought reconstructions from surrounding areas implies a high degree of confidence for our reconstruction. Precipitation variations in the study area are significantly correlated with sea surface temperatures in eastern equatorial Pacific Ocean and tropical western Pacific Ocean, suggesting a possible connection of regional precipitation variations to the EASM and the El Niño-Southern Oscillation (ENSO). [ABSTRACT FROM AUTHOR]

Efficient ultraviolet (UV) electroluminescent materials remain a great challenge, since short peak wavelength <400 nm and narrow full width at half maximum (FWHM) <50 nm are simultaneously required. In this sense, multi‐resonance (MR) thermally activated delayed fluorescence (TADF) emitters featuring narrow‐band emissions hold the promise for UV applications. Herein, a novel MR‐TADF skeleton featuring carbazole‐phosphine oxide (P=O) fused aromatics is developed to construct the first two UV MR emitters named CzP2PO and tBCzP2PO. In addition to synergistic resonance effects of P=O and N atom, sp3‐hybrid P atom renders the curved polycyclic planes of CzP2PO and tBCzP2PO, giving rise to their narrowband UV emissions with peak wavelengths <390 nm and FWHM<35 nm. Besides configuration quasi‐planarization for radiation enhancement and quenching suppression, P=O moiety further enhances singlet‐triplet coupling to facilitate reverse intersystem crossing, resulting in the state‐of‐the‐art photoluminescence quantum yield of 62 % in tBCzP2PO doped films. As consequence, tBCzP2PO endowed its UV organic light‐emitting diodes with the peak at 382 nm and FWHM of 32 nm, and especially the record‐high external quantum efficiency (EQE) of 15.1 % among all kinds of UV devices. Our results demonstrate great potential of P=O based MR emitters in practical applications including optoelectronics, biology and medicine science. [ABSTRACT FROM AUTHOR]

Efficient ultraviolet (UV) electroluminescent materials remain a great challenge, since short peak wavelength <400 nm and narrow full width at half maximum (FWHM) <50 nm are simultaneously required. In this sense, multi‐resonance (MR) thermally activated delayed fluorescence (TADF) emitters featuring narrow‐band emissions hold the promise for UV applications. Herein, a novel MR‐TADF skeleton featuring carbazole‐phosphine oxide (P=O) fused aromatics is developed to construct the first two UV MR emitters named CzP2PO and tBCzP2PO. In addition to synergistic resonance effects of P=O and N atom, sp3‐hybrid P atom renders the curved polycyclic planes of CzP2PO and tBCzP2PO, giving rise to their narrowband UV emissions with peak wavelengths <390 nm and FWHM<35 nm. Besides configuration quasi‐planarization for radiation enhancement and quenching suppression, P=O moiety further enhances singlet‐triplet coupling to facilitate reverse intersystem crossing, resulting in the state‐of‐the‐art photoluminescence quantum yield of 62 % in tBCzP2PO doped films. As consequence, tBCzP2PO endowed its UV organic light‐emitting diodes with the peak at 382 nm and FWHM of 32 nm, and especially the record‐high external quantum efficiency (EQE) of 15.1 % among all kinds of UV devices. Our results demonstrate great potential of P=O based MR emitters in practical applications including optoelectronics, biology and medicine science. [ABSTRACT FROM AUTHOR]

Near‐infrared (NIR) organic light‐emitting diodes (OLEDs) show great potential in a variety of applications including sensors, night vision, and information security. Despite the superiority of thermally activated delayed fluorescence (TADF) in 100 % exciton harvesting, the development of NIR TADF OLEDs is still a great challenge, especially in terms of solution‐processing technology. In this work, a multicyano acceptor of 2‐dicyanomethylene‐3‐cyano‐4,5,5‐trimethyl‐2,5‐dihydrofurance (TCF) with strong electron‐withdrawing ability was employed to construct solution‐processible NIR emitters, CzTCF and tBCzTCF, with the feature of donor–π–acceptor (D–π–A) structure. The significantly enhanced intermolecular charge transfer effects not only render the deep‐red and NIR emissions of CzTCF and tBCzTCF films, respectively, but also lead to their typical TADF characteristics. Consequently, the nondoped solution‐processed NIR OLED based on tBCzTCF was successfully demonstrated with the peak wavelength of 715 nm, which paves the way for developing NIR emitters without polycyclic aromatic cores and heavy‐metal ions. A multicyano‐substituted acceptor and styryl π‐conjugate linker were both optimized to realize efficient NIR thermally activated delayed fluorescence (TADF) emitters (CzTCF and tBCzTCF) with simple D–π–A structure. The three linearly distributed cyano groups in TCF and the longer conjugation in the styryl π‐linker effectively regulated the D–A interactions and the frontier molecular orbital distributions (see scheme). [ABSTRACT FROM AUTHOR]

This study investigated the feasibility of sulfate modification of Lycium barbarum polysaccharides (LBPs) and their potential anti‐HIV‐1 application. LBPs with different molecular weights were prepared by fractional precipitation from crude LBP via aqueous extraction, ethanol precipitation, and deproteinization. The purified LBPs (G1, G2, and G3) were sulfated using the chlorosulfonic acid pyridine method to obtain sulfated LBPs (G1S1–G1S4, G2S1–G2S4, and G3S1–G3S4) with different sulfur degrees of substitution. The anti‐HIV‐1 activity in vitro was evaluated via the TD50 from the cytotoxicity test and the IC50 inhibitory activity. The cytotoxicity and inhibitory activity in vitro were carried out using the CCK‐8 assay and MAGI test with Azidothymidine (AZT) as a positive control. The results show that the LBPs and the sulfated derivatives were not toxic towards CCK‐8 cells with TD50>100 μg/mL and they had strong anti‐HIV‐1 activity with IC50 values of 0.02–0.12 μg/mL. Compared with the LBPs, the anti‐HIV‐1 activity of the sulfated LBPs increased with IC50 values from 0.0924–0.1206 μg/mL to 0.0206–0.0722 μg/mL. Sulfate modification of LBPs can increase their anti‐HIV pharmacological activity, the G1S4 (Mw=2.13×104 Da and DS=1.12) showed relatively good in vitro anti‐HIV‐1 activity with an IC50 value near that of AZT (0.0200 μg/mL). The results suggest further detailed in vivo studies are warranted for these promising candidates with anti‐HIV‐1 activity. [ABSTRACT FROM AUTHOR]

Herein, we report a deep‐red TADF emitter pCNQ–TPA, composed of quinoxaline‐5,8‐dicarbonitrile (pCNQ) acceptor and triphenylamine (TPA) donor. pCNQ–TPA supported its OLED with desired CIE coordinates of (0.69, 0.31) and the record maximum external quantum efficiency of 30.3 %, which is the best red TADF diode with Rec.2020 gamut for UHDTV. It is showed that through tuning pCNQ–TPA doping concentration, intra‐ and inter‐molecular charge transfer are balanced to synchronously improve emission color saturation and TADF radiation, and remedy aggregation‐induced quenching, rendering photoluminescence quantum yield (PLQY) reaching 90 % for deep‐red emission peaked at ≈690 nm. Quasi‐planar structure further endows pCNQ–TPA with an improved horizontal ratio of emitting dipole orientation, which increases light out‐coupling ratio to 0.34 for achieving the state‐of‐the‐art device efficiencies. [ABSTRACT FROM AUTHOR]

Herein, we report a deep‐red TADF emitter pCNQ–TPA, composed of quinoxaline‐5,8‐dicarbonitrile (pCNQ) acceptor and triphenylamine (TPA) donor. pCNQ–TPA supported its OLED with desired CIE coordinates of (0.69, 0.31) and the record maximum external quantum efficiency of 30.3 %, which is the best red TADF diode with Rec.2020 gamut for UHDTV. It is showed that through tuning pCNQ–TPA doping concentration, intra‐ and inter‐molecular charge transfer are balanced to synchronously improve emission color saturation and TADF radiation, and remedy aggregation‐induced quenching, rendering photoluminescence quantum yield (PLQY) reaching 90 % for deep‐red emission peaked at ≈690 nm. Quasi‐planar structure further endows pCNQ–TPA with an improved horizontal ratio of emitting dipole orientation, which increases light out‐coupling ratio to 0.34 for achieving the state‐of‐the‐art device efficiencies. [ABSTRACT FROM AUTHOR]

Near‐infrared (NIR) thermally activated delayed fluorescence (TADF) materials have great potential for applications in many fields. However, it is more challenging for such kinds of materials to achieve efficient NIR emission in comparison to visible light. Herein, as a proof of concept, three acceptors are regularly aligned to optimize intramolecular charge transfer (ICT) interactions in donor‐π‐acceptor molecules to improve bathochromic shift and TADF performance, which successfully supports the application in NIR OLEDs. More information can be found in the Full Paper by C. Han, H. Xu, et al. on page 1010. [ABSTRACT FROM AUTHOR]

Invited for the cover of this issue are Prof. Hui Xu and co‐workers at Heilongjiang University and Wuhan University. The image depicts a simple strategy for realizing a near‐infrared thermally activated delayed fluorescence (NIR TADF) emitter. Read the full text of the article at 10.1002/chem.201805201. "This work demonstrated a feasible strategy for NIR TADF emitters through linear distribution of donors to optimize the donor/acceptor interactions." Read more about the story behind the cover in the Cover Profile and about the research itself on page 1010 ff. (DOI: 10.1002/chem.201805201). [ABSTRACT FROM AUTHOR]

We present a drought reconstruction for southeastern China based on a tree-ring width chronology of Cryptomeria fortunei developed from two sampling sites in central Fujian. A reconstruction of July-February drought variability, spanning AD 1855-2011, was developed by calibrating total tree-ring width data with the self-calibrating Palmer drought severity index (sc PDSI). The reconstruction was verified against an independent data set, and accounts for 36% of the actual sc PDSI variance during the period 1955-2011. Relatively dry intervals were reconstructed between AD 1859-1880, 1899-1911, 1927-1933, 1946-1959, 1964-1970 and 1987-1997. Relatively wet conditions prevailed during 1855-1858, 1881-1898, 1912-1926, 1934-1945, 1960-1963, 1971-1986 and 1998-2011. Comparisons between our scPDSI reconstruction and a moisture-sensitive tree-ring width record from Vietnam revealed consistencies between the two data sets, suggesting similar drought regimes. Spectral peaks of 2.2-6.4 years may be indicative of El Niño-Southern Oscillation ( ENSO) activity, as also suggested by the significant correlations with sea surface temperatures ( SSTs) in the eastern equatorial and southeastern Pacific Ocean and an extreme event analysis. The analysis of links between our sc PDSI reconstruction and the large-scale regional climatic variation shows that there is a relationship between regional drought variation and East Asian summer monsoon (EASM) intensity. [ABSTRACT FROM AUTHOR]