Prediction-error expansion (PEE) is an important technique of reversible watermarking which can embed large payloads into digital images with low distortion. In this paper, the PEE technique is ...further investigated and an efficient reversible watermarking scheme is proposed, by incorporating in PEE two new strategies, namely, adaptive embedding and pixel selection. Unlike conventional PEE which embeds data uniformly, we propose to adaptively embed 1 or 2 bits into expandable pixel according to the local complexity. This avoids expanding pixels with large prediction-errors, and thus, it reduces embedding impact by decreasing the maximum modification to pixel values. Meanwhile, adaptive PEE allows very large payload in a single embedding pass, and it improves the capacity limit of conventional PEE. We also propose to select pixels of smooth area for data embedding and leave rough pixels unchanged. In this way, compared with conventional PEE, a more sharply distributed prediction-error histogram is obtained and a better visual quality of watermarked image is observed. With these improvements, our method outperforms conventional PEE. Its superiority over other state-of-the-art methods is also demonstrated experimentally.
Lead‐free halide perovskite nanocrystals (NCs) have drawn wide attention for solving the problem of lead perovskites toxicity and instability. Herein, we synthesize the direct band gap double ...perovskites undoped and Ag‐doped Cs2NaInCl6 NCs by variable temperature hot injection. The Cs2NaInCl6 NCs have little photoluminescence because of dark self‐trapped excitons (STEs). The dark STEs can be converted into bright STEs by doping with Ag+ to produce a bright yellow emission, with the highest photoluminescence quantum efficiency of 31.1 %. The dark STEs has been directly detected experimentally by ultrafast transient absorption (TA) techniques. The dynamics mechanism is further studied. In addition, the Ag‐doped NCs show better stability than the undoped ones. This result provides a new way to enhance the optical properties of lead‐free perovskites NCs for high‐performance light emitters.
Glow yellow: Lead‐free double perovskite Cs2NaInCl6 and Ag‐doped Cs2NaInCl6 nanocrystals (NCs) are synthesized. Ag‐doped NCs exhibit bright yellow emission with a photoluminescence quantum efficiency of 31.1 %. The self‐trapped exciton dynamics mechanism is also studied.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
•Effect of interdigital electrode gap size on the performance of capacitive humidity sensor was investigated.•SnO2-modified MoS2 nanocomposite was successfully synthesized.•Different humidity sensing ...mechanisms are analyzed in detail.
To improve the sensitivity of humidity sensors, the interdigital electrode size should be paid more attention, apart from the development of high performance sensing materials. This paper investigated the interaction between testing electrode and the performance of capacitive humidity sensor. To our best knowledge, no other reported papers have investigated it before. We found that the gap size of interdigital electrode had crucial influence on the response of SnO2/MoS2 based capacitive humidity sensors due to the different surface electrical conduction mechanisms. For the sensor with small gap interdigital electrode structure, the capacitance decreases exponentially as relative humidity (RH) rises so that high sensitivity is obtained at low humidity range (0%–45% RH). While the gap is wide enough, the capacitance increases exponentially as RH grows to get ultrahigh sensitivity at high humidity range (45%–90% RH). The experimental results show that the sensor with 5 μm gap have the largest sensitivity (161 μF/% RH) at low humidity range while the best sensitivity of 3170 pF/% RH is obtained at high humidity range for the sensor with gap of 100 μm. The as-prepared SnO2/MoS2 hybrid sensing nanocomposite was synthesized through a two-step hydrothermal route and its morphology and structure were further characterized using field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). Moreover, the SnO2/MoS2 based capacitive humidity sensors have fast response, short recovery time, little hysteresis and good repeatability.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Lead‐based perovskite nanocrystals (NCs) have outstanding optical properties and cheap synthesis conferring them a tremendous potential in the field of optoelectronic devices. However, two critical ...problems are still unresolved and hindering their commercial applications: one is the fact of being lead‐based and the other is the poor stability. Lead‐free all‐inorganic perovskite Cs3Bi2X9 (X=Cl, Br, I) NCs are synthesized with emission wavelength ranging from 400 to 560 nm synthesized by a facile room temperature reaction. The ligand‐free Cs3Bi2Br9 NCs exhibit blue emission with photoluminescence quantum efficiency (PLQE) about 0.2 %. The PLQE can be increased to 4.5 % when extra surfactant (oleic acid) is added during the synthesis processes. This improvement stems from passivation of the fast trapping process (2–20 ps). Notably, the trap states can also be passivated under humid conditions, and the NCs exhibited high stability towards air exposure exceeding 30 days.
Unleaded: Lead‐free, all‐inorganic perovskite Cs3Bi2X9 nanocrystals (NCs; X=Cl, Br, I) have been synthesized. The ligand‐capped Cs3Bi2Br9 NCs exhibit blue emission with photoluminescence quantum efficiency up to 4.5 % and show high stability for over one month.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Natural killer/T cell lymphoma (NKTCL) is an aggressive and heterogeneous entity of non-Hodgkin lymphoma, strongly associated with Epstein-Barr virus (EBV) infection. To identify molecular subtypes ...of NKTCL based on genomic structural alterations and EBV sequences, we performed multi-omics study on 128 biopsy samples of newly diagnosed NKTCL and defined three prominent subtypes, which differ significantly in cell of origin, EBV gene expression, transcriptional signatures, and responses to asparaginase-based regimens and targeted therapy. Our findings thus identify molecular networks of EBV-associated pathogenesis and suggest potential clinical strategies on NKTCL.
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•Integrated analysis provides insight into the molecular classification in NKTCL•EBV lytic genes play an important role on NKTCL pathogenesis•Genomic alteration-based molecular subtypes associate with clinical outcomes•MYC, histone acetylation, and PD-L1/2 are potential therapeutic targets of NKTCL
Xiong et al. propose an updated molecular subtyping scheme based on integrated analysis of the genomic and transcriptomic features of natural killer/T cell lymphoma from patient biopsies, and provide insights into pathogenesis and therapeutic targeting of the disease.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A series of lead‐free double perovskite nanocrystals (NCs) Cs2AgSb1−yBiyX6 (X: Br, Cl; 0≤y≤1) is synthesized. In particular, the Cs2AgSbBr6 NCs is a new double perovskite material that has not been ...reported for the bulk form. Mixed Ag–Sb/Bi NCs exhibit enhanced stability in colloidal solution compared to Ag–Bi or Ag–Sb NCs. Femtosecond transient absorption studies indicate the presence of two prominent fast trapping processes in the charge‐carrier relaxation. The two fast trapping processes are dominated by intrinsic self‐trapping (ca. 1–2 ps) arising from giant exciton–phonon coupling and surface‐defect trapping (ca. 50–100 ps). Slow hot‐carrier relaxation is observed at high pump fluence, and the possible mechanisms for the slow hot‐carrier relaxation are also discussed.
Caught in a trap: A series of new double perovskite nanocrystals Cs2AgSb1−yBiyX6 (X: Br, Cl; 0≤y≤1) is synthesized. Intrinsic self‐trapping (ca. 1–2 ps) arising from giant carrier–phonon scattering and surface‐defect trapping (ca. 50–100 ps) are revealed. Slow hot‐carrier cooling is observed at high pump fluence.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Seasonal drought will become more intense and frequent in some regions due to global climate change, which may lead to significant changes in the competitive interactions and uptake depths of plant ...water sources. Based on delta 18O and delta D in xylem and soil water, we investigated the impacts of seasonal drought on plant water sources from July 2011 to October 2013 for a subtropical coniferous plantation in southeastern China. Our results indicated that the studied tree species of Pinus massoniana, Pinus elliottii and Cunninghamia lanceolata appeared to have inter-specific competition for water resources from similar depths. There was a switch of the major water source from shallow soil during the non-drought periods (July to October) to deep soil during the drought periods (November-June). Similar seasonal trend of water uptake was estimated by delta 18O and delta D. However, relative to the results of delta D, water sources predicted by delta 18O showed that trees seemed to derive more deep soil water during the drought periods and more shallow soil water during the non-drought periods. The differences of plant water source partitioning based on delta 18O and delta D were significant during both the drought and non-drought periods, which probably resulted from the artifacts of the cryogenic vacuum distillation and spectral contamination correction. These findings will have important implications for further studies when just one of the dual stable isotopes of delta 18O and delta D is applied.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Typically, the enzymatic hydrolysis rate of lignocellulosic biomass is fast initially but then slows down more rapidly than can be explained by just consumption of substrate. Although several factors ...including enzyme inhibition, enzyme deactivation, a drop in substrate reactivity, or nonproductive binding of enzyme to lignin could be responsible for this loss of effectiveness, we recently reported evidence that xylose, xylan, and xylooligomers dramatically decrease conversion rates and yields, but clarification was still needed fors the magnitude of their effect. Therefore, in this study, xylan and various xylooligomers were added to Avicel hydrolysis at low enzyme loadings and found to have a greater effect than adding equal amounts of xylose derived from these materials or when added separately. Furthermore, xylooligomers were more inhibitory than xylan or xylose in terms of a decreased initial hydrolysis rate and a lower final glucose yield even for a low concentration of 1.67
mg/ml. At a higher concentration of 12.5
mg/ml, xylooligomers lowered initial hydrolysis rates of Avicel by 82% and the final hydrolysis yield by 38%. Mixed DP xylooligomers showed strong inhibition on cellulase enzymes but not on β-glucosidase enzymes. By tracking the profile change of xylooligomers, a large portion of the xylooligomers was found to be hydrolyzed by Spezyme CP enzyme preparations, indicating competitive inhibition by mixed xylooligomers. A comparison among glucose sugars and xylose sugars also showed that xylooligomers were more powerful inhibitors than well-established glucose and cellobiose.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Developing low-cost electrocatalysts to replace precious Ir-based materials is key for oxygen evolution reaction (OER). Here, we report atomically dispersed nickel coordinated with nitrogen and ...sulfur species in porous carbon nanosheets as an electrocatalyst exhibiting excellent activity and durability for OER with a low overpotential of 1.51 V at 10 mA cm
and a small Tafel slope of 45 mV dec
in alkaline media. Such electrocatalyst represents the best among all reported transition metal- and/or heteroatom-doped carbon electrocatalysts and is even superior to benchmark Ir/C. Theoretical and experimental results demonstrate that the well-dispersed molecular S|NiN
species act as active sites for catalyzing OER. The atomic structure of S|NiN
centers in the carbon matrix is clearly disclosed by aberration-corrected scanning transmission electron microscopy and synchrotron radiation X-ray absorption spectroscopy together with computational simulations. An integrated photoanode of nanocarbon on a Fe
O
nanosheet array enables highly active solar-driven oxygen production.
Sensitivity is an important parameter of molecularly imprinted electrochemical sensors, and various methods have been extensively investigated to improve this parameter. This review focuses on recent ...reports about different methods that can enhance the sensitivity of these sensors. To a great extent, the sensitivity of the molecularly imprinted sensor is limited by the number of cavities formed in a molecularly imprinted polymer on an electrode after elution. To enhance sensitivity and fabricate sensing devices, researchers employ signal amplification by labels, amplification by functional materials doped in imprinted membranes, sensitive film amplification, and other methods. Some perspectives in this research area, current problems, and challenges are also outlined.
Sensitivity is a critical issue of the performance of molecularly imprinted electrochemical sensors. This review focuses on recent reports of methods that can enhance their sensitivity. Perspectives in this research area, current problems, and challenges are also outlined. Display omitted
•Different methods for improving sensitivity of molecularly imprinted electrochemical sensors were overviewed.•Amplification strategies were discussed and divided into three categories.•Inherent advantages and limitations of these strategies for bioanalysis were discussed.•Prospects of highly sensitive molecularly imprinted electrochemical sensors were assessed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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