Solution-processed metal halide perovskites have been recognized as one of the most promising semiconductors, with applications in light-emitting diodes (LEDs), solar cells and lasers. Various ...additives have been widely used in perovskite precursor solutions, aiming to improve the formed perovskite film quality through passivating defects and controlling the crystallinity. The additive's role of defect passivation has been intensively investigated, while a deep understanding of how additives influence the crystallization process of perovskites is lacking. Here, we reveal a general additive-assisted crystal formation pathway for FAPbI
perovskite with vertical orientation, by tracking the chemical interaction in the precursor solution and crystallographic evolution during the film formation process. The resulting understanding motivates us to use a new additive with multi-functional groups, 2-(2-(2-Aminoethoxy)ethoxy)acetic acid, which can facilitate the orientated growth of perovskite and passivate defects, leading to perovskite layer with high crystallinity and low defect density and thereby record-high performance NIR perovskite LEDs (~800 nm emission peak, a peak external quantum efficiency of 22.2% with enhanced stability).
A method of motion status estimation of airborne synthetic aperture radar (SAR) platform in short subapertures via parametric sparse representation is proposed for high-resolution SAR image ...autofocusing. The SAR echo is formulated as a jointly sparse signal through a parametric dictionary matrix, which converts the problem of SAR motion status estimation into a problem of dynamic representation of jointly sparse signals. A full synthetic aperture is decomposed into several subapertures to estimate the dynamic motion parameters of a platform, and SAR motion compensation is achieved by refining the estimation of the equivalent platform motion parameters, i.e., the azimuth velocity and the radial acceleration of the radar platform, at each subaperture in an iterative fashion. Experimental results based on both simulated and real data demonstrate that: 1) the proposed algorithm outperforms the map-drift algorithm and the phase gradient autofocus algorithm in terms of the imaging quality and 2) compared to the iterative minimum-entropy autofocus, the proposed algorithm produces the comparative imaging quality with less computational complexity in complex motion environment.
Efficiency roll-off is a major issue for most types of light-emitting diodes (LEDs), and its origins remain controversial. Here we present investigations of the efficiency roll-off in perovskite LEDs ...based on two-dimensional layered perovskites. By simultaneously measuring electroluminescence and photoluminescence on a working device, supported by transient photoluminescence decay measurements, we conclude that the efficiency roll-off in perovskite LEDs is mainly due to luminescence quenching which is likely caused by non-radiative Auger recombination. This detrimental effect can be suppressed by increasing the width of quantum wells, which can be easily realized in the layered perovskites by tuning the ratio of large and small organic cations in the precursor solution. This approach leads to the realization of a perovskite LED with a record external quantum efficiency of 12.7%, and the efficiency remains to be high, at approximately 10%, under a high current density of 500 mA cm
.
Lead‐free perovskite infrared light‐emitting diodes are achieved by using a halide perovskite CsSnI3 as an emissive layer. The film shows compact micrometer‐sized grains with only a few pinholes and ...cracks at the grain boundaries. The device exhibits maximum radiance of 40 W sr−1 m−2 at a current density of 364.3 mA cm−2 and maximum external quantum efficiency of 3.8% at 4.5 V.
Quasi‐2D layered organometal halide perovskites have recently emerged as promising candidates for solar cells, because of their intrinsic stability compared to 3D analogs. However, relatively low ...power conversion efficiency (PCE) limits the application of 2D layered perovskites in photovoltaics, due to large energy band gap, high exciton binding energy, and poor interlayer charge transport. Here, efficient and water‐stable quasi‐2D perovskite solar cells with a peak PCE of 18.20% by using 3‐bromobenzylammonium iodide are demonstrated. The unencapsulated devices sustain over 82% of their initial efficiency after 2400 h under relative humidity of ≈40%, and show almost unchanged photovoltaic parameters after immersion into water for 60 s. The robust performance of perovskite solar cells results from the quasi‐2D perovskite films with hydrophobic nature and a high degree of electronic order and high crystallinity, which consists of both ordered large‐bandgap perovskites with the vertical growth in the bottom region and oriented small‐bandgap components in the top region. Moreover, due to the suppressed nonradiative recombination, the unencapsulated photovoltaic devices can work well as light‐emitting diodes (LEDs), exhibiting an external quantum efficiency of 3.85% and a long operational lifetime of ≈96 h at a high current density of 200 mA cm−2 in air.
High‐crystallinity quasi‐2D perovskite films with oriented structure are fabricated by using 3‐bromobenzylammonium iodide, leading to perovskite solar cells with a high efficiency of 18.20%. Moreover, the unencapsulated devices exhibit excellent moisture resistance, retaining 82% of the initial efficiency after 2400 h under ambient conditions. Even after immersion into water for 60 s, the unsealed device shows little decay.
Solution-processed metal-halide perovskites are emerging as one of the most promising materials for displays, lighting and energy generation. Currently, the best-performing perovskite optoelectronic ...devices are based on lead halides and the lead toxicity severely restricts their practical applications. Moreover, efficient white electroluminescence from broadband-emission metal halides remains a challenge. Here we demonstrate efficient and bright lead-free LEDs based on cesium copper halides enabled by introducing an organic additive (Tween, polyethylene glycol sorbitan monooleate) into the precursor solutions. We find the additive can reduce the trap states, enhancing the photoluminescence quantum efficiency of the metal halide films, and increase the surface potential, facilitating the hole injection and transport in the LEDs. Consequently, we achieve warm-white LEDs reaching an external quantum efficiency of 3.1% and a luminance of 1570 cd m
at a low voltage of 5.4 V, showing great promise of lead-free metal halides for solution-processed white LED applications.
Nuclear factor-κB (NF-κB) is a central transcriptional factor and a pleiotropic regulator of many genes involved in acute lung injury. Andrographolide is found in the plant of Andrographis paniculata ...and widely used in Traditional Chinese Medicine, exhibiting potently anti-inflammatory property by inhibiting NF-κB activity. The purpose of our investigation was designed to reveal the effect of andrographolide on various aspects of LPS induced inflammation in vivo and in vitro.
In vivo, BALB/C mice were subjected to LPS injection with or without andrographolide treatments to induce ALI model. In vitro, MLE-12 cells were stimulated with LPS in the presence and absence of andrographolide. In vivo, pulmonary inflammation, pulmonary edema, ultrastructure changes of type II alveolar epithelial cells, MPO activity, total cells, neutrophils, macrophages, TNF-α, IL-6 and IL-1β in BALF, along with the expression of VCAM-1 and VEGF were dose-dependently attenuated by andrographolide. Meanwhile, in vitro, the expression of VCAM-1 and VEGF was also reduced by andrographolide. Moreover, our data showed that andrographolide significantly inhibited the ratios of phospho-IKKβ/total IKKβ, phospho-IκBα/total IκBα and phospho-NF-κB p65/total NF-κB p65, and NF-κB p65 DNA binding activities, both in vivo and in vitro.
These results indicate that andrographolide dose-dependently suppressed the severity of LPS-induced ALI, more likely by virtue of andrographolide-mediated NF-κB inhibition at the level of IKKβ activation. These results suggest andrographolide may be considered as an effective and safe drug for the potential treatment of ALI.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Objective Congenital hypothyroidism (CH), the most common neonatal metabolic disorder, is characterized by impaired neurodevelopment. Although several candidate genes have been associated with CH, ...comprehensive screening of causative genes has been limited. Design and methods One hundred ten patients with primary CH were recruited in this study. All exons and exon–intron boundaries of 21 candidate genes for CH were analyzed by next-generation sequencing. And the inheritance pattern of causative genes was analyzed by the study of family pedigrees. Results Our results showed that 57 patients (51.82%) carried biallelic mutations (containing compound heterozygous mutations and homozygous mutations) in six genes (DUOX2, DUOXA2, DUOXA1, TG, TPO and TSHR) involved in thyroid hormone synthesis. Autosomal recessive inheritance of CH caused by mutations in DUOX2, DUOXA2, TG and TPO was confirmed by analysis of 22 family pedigrees. Notably, eight mutations in four genes (FOXE1, NKX2-1, PAX8 and HHEX) that lead to thyroid dysgenesis were identified in eight probands. These mutations were heterozygous in all cases and hypothyroidism was not observed in parents of these probands. Conclusions Most cases of congenital hypothyroidism in China were caused by thyroid dyshormonogenesis rather than thyroid dysgenesis. This study identified previously reported causative genes for 57/110 Chinese patients and revealed DUOX2 was the most frequently mutated gene in these patients. Our study expanded the mutation spectrum of CH in Chinese patients, which was significantly different from Western countries.
Weyl semimetals are three-dimensional (3D) gapless topological phases with Weyl cones in the bulk band. According to lattice theory, Weyl cones must come in pairs, with the minimum number of cones ...being two. A semimetal with only two Weyl cones is an ideal Weyl semimetal (IWSM). Here we report the experimental realization of an IWSM band by engineering 3D spin-orbit coupling for ultracold atoms. The topological Weyl points are clearly measured via the virtual slicing imaging technique in equilibrium and are further resolved in the quench dynamics. The realization of an IWSM band opens an avenue to investigate various exotic phenomena that are difficult to access in solids.
Topological quantum states are characterized by nonlocal invariants. We present a new dynamical approach for ultracold-atom systems to uncover their band topology, and we provide solid evidence to ...demonstrate its experimental advantages. After quenching a two-dimensional (2D) Chern band, realized in an ultracold ^{87}Rb gas from a trivial to a topological parameter regime, we observe an emerging ring structure in the spin dynamics during the unitary evolution, which uniquely corresponds to the Chern number for the postquench band. By extracting 2D bulk topology from the 1D ring pattern, our scheme displays simplicity and is insensitive to perturbations. This insensitivity enables a high-precision determination of the full phase diagram for the system's band topology.
PDF
