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Emerging lead halide perovskite quantum dots (QDs) have attracted great research interest relative to conventional metal chalcogenide-based QDs for applications like solar cells.

Accurate crowd flow prediction has gained increasing importance for the development of social Internet-of-Things (IoT) systems. In this article, we provide an efficient crowd flow prediction for social IoT systems in urban space based on the mobile network big data. In particular, the usage detail records (UDRs) are used in the prediction. The feasibility of using UDRs in the prediction is first analyzed. Then, a graph data model is exploited to record and represent the mobile behavior of users. In particular, we propose to apply the heterogeneous information network (HIN) representing the UDR data and characterize the users' behavior through the embedding methods of HIN. Moreover, an attention-based spatiotemporal graph convolution network with embedded vectors (EA-STGCN) is proposed for the final prediction. Through experimental evaluation, the advantages of the proposed model are shown in comparison to benchmarks.

Solution processable semiconductors like organics and emerging lead halide perovskites (LHPs) are ideal candidates for photovoltaics combining high performance and flexibility with reduced manufacturing cost. Moreover, the study of hybrid semiconductors would lead to advanced structures and deep understanding that will propel this field even further. Herein, a novel device architecture involving block copolymer/perovskite hybrid bulk heterointerfaces is investigated, such a modification could enhance light absorption, create an energy level cascade, and provides a thin hydrophobic layer, thus enabling enhanced carrier generation, promoting energy transfer and preventing moisture invasion, respectively. The resulting hybrid block copolymer/perovskite solar cell exhibits a champion efficiency of 24.07% for 0.0725 cm

For emerging perovskite quantum dots (QDs), understanding the surface features and their impact on the materials and devices is becoming increasingly urgent. In this family, hybrid FAPbI

Vitreoretinal lymphoma (VRL) can commonly masquerade as chronic idiopathic uveitis due to its nonspecific clinical presentation. Thus, its early diagnosis is difficult. In this study, new logistic regression models were used to classify VRL and uveitis. Additionally, the diagnostic performance of interleukin (IL)-10, the IL-10/IL-6, and the Interleukin Score for IntraOcular Lymphoma Diagnosis (ISOLD) are evaluated.Sixty-nine aqueous humors (AH) (46 VRL, 23 uveitis) and 65 vitreous humors (VH) (49 VRL, 16 uveitis) were collected from a single-center retrospective cohort. Logistic regression models were conducted based on IL-6 and IL-10. The cut-off values, area under the receiver operating characteristic curve (ROC) curve (AUC), sensitivity and specificity of IL-10, the IL-10/IL-6, the ISOLD, and the models were calculated from the ROC. Furthermore, Spearman's rank correlation analysis was performed to determine cytokine levels in VH and AH.We redefined the cut-off values of IL-10, the IL-10/IL-6, the ISOLD, and the logistic regression models. In AH, the AUC values of IL-10, ISOLD, IL10/IL6, and the model were 0.91, 0.953, 0.952, and 0.967. In VH, they were 0.93, 0.95, 0.954, and 0.954, respectively. IL-6 (r = 0.7844) and IL-10 (r = 0.8506) in AH and VH showed a strong correlation.IL-6 and IL-10 levels were introduced into new logistic regression models. The diagnostic efficacy of the models improved compared to the indicators mentioned above among Chinese patients. Additionally, the models could predict the probability of VRL more accurately. A strong correlation of cytokine levels showed the great potential of AH as prioritized auxiliary diagnostic for VRL.

The mixed cation colloidal Cs1−XFAXPbI3 perovskite quantum dots (PQDs) obtained by cation exchange between CsPbI3 and FAPbI3 PQDs have been reported to exhibit enhanced photovoltaic performance. However, the cation exchange mechanism requires further in-depth investigation in terms of both material properties and device application. In this work, the impact of PQD weight ratio, PQD concentration, and host solvent polarity during cation exchange is comprehensively investigated for the first time. In addition, the whole exchange process under varying conditions is monitored by photoluminescence spectroscopy. As a result, we observe extremely fast cation exchange (∼20 min) under a condition at a CsPbI3/FAPbI3 PQD weight ratio of 1:1, a concentration of 70 mg/ml, and a host solvent using toluene. Moreover, we directly fabricate a PQD solar cell device using these obtained mixed cation Cs0.5FA0.5PbI3 PQDs and achieved an enhanced power conversion efficiency of 14.58%. We believe that these results would provide more insights into the cation exchange in emerging PQDs toward efficient photovoltaic fabrication and application.

Ruddlesden–Popper phase 2D perovskite solar cells (PSCs) exhibit improved lifetime while still facing challenges such as phase alignment and up-scaling to module-level devices. Herein, polyelectrolytes are explored to tackle this issue. The contact between perovskite and hole-transport layer (HTL) is important for decreasing interfacial non-radiative recombination and scalable fabrication of uniform 2D perovskite films. Through exploring compatible butylamine cations, we first demonstrate poly(3-(4-carboxybutyl)thiophene-2,5-diyl)-butylamine (P3CT-BA) as an efficient HTL for 2D PSCs due to its great hydrophilicity, relatively high hole mobility and uniform surface. More importantly, the tailored P3CT-BA has an anchoring effect and acts as the buried passivator for 2D perovskites. Consequently, a best efficiency approaching 18¿% was achieved and we further first report large-area (2×3 cm2, 5×5 cm2) 2D perovskite minimodules with an impressive efficiency of 14.81¿% and 11.13¿%, respectively.

Here, a pseudo-solution-phase ligand exchange (p-SPLE) strategy is developed for fabricating a CsPbI3 quantum dot (QD) solar cell. Using short organic aromatic ligands to partly replace the long-chain ligands in a QD solution, the p-SPLE treated CsPbI3 QD solar cell had an enhanced power conversion efficiency of up to 14.65% together with improved stability.

Organic–inorganic hybrid lead halide perovskite solar cells have made unprecedented progress in improving photovoltaic efficiency during the past decade, while still facing critical stability challenges. Herein, the natural organic dye Indigo is explored for the first time to be an efficient molecular passivator that assists in the preparation of high-quality hybrid perovskite film with reduced defects and enhanced stability. The Indigo molecule with both carbonyl and amino groups can provide bifunctional chemical passivation for defects. In-depth theoretical and experimental studies show that the Indigo molecules firmly binds to the perovskite surfaces, enhancing the crystallization of perovskite films with improved morphology. Consequently, the Indigo-passivated perovskite film exhibits increased grain size with better uniformity, reduced grain boundaries, lowered defect density, and retarded ion migration, boosting the device efficiency up to 23.22%, and ˜21% for large-area device (1 cm2). Furthermore, the Indigo passivation can enhance device stability in terms of both humidity and thermal stress. These results provide not only new insights into the multipassivation role of natural organic dyes but also a simple and low-cost strategy to prepare high-quality hybrid perovskite films for optoelectronic applications based on Indigo derivatives.

Facile hydrothermally synthesized PbSnS2 nanosheets with various morphologies were developed to obtain high performance electrode materials for supercapacitors. A precipitation–dissolution mechanism was proposed to demonstrate the growth process of PbSnS2. The as-prepared nanosheets exhibited superior capacitance (678.8 F g−1 at 50 mV s−1) and a long cycle life (95.5% capacitance retention after 100 000 cycles at 5 A g−1).

This work describes a facile one-step method to synthesize PbS hierarchical architectures with excellent supercapacitive performance. The as-prepared PbS sample shows a self-similar fern-like morphology. A unit has four or eight micro-trunks with the size of 10 ± 1 μm, which consist of ordered secondary nano-leaves with the thickness of 200 ± 20 nm and the spacing of about 100 nm. The fractal fern-like PbS sample owns a high specific capacitance of 498 F/g at a discharge current density of 2 A/g, while the value still retains 74% (369 F/g) at a big discharge current density of 20 A/g. The equivalent series resistance of the as-prepared sample is only 1.05 Ω. Moreover, the fractal fern-like PbS sample exhibits a surprising long-term durability which can keep 95.9% capacitance retention over 60,000 charge/discharge cycles at a charge/discharge current density of 5 A/g. The as-prepared PbS sample shows a stable energy density of 11.5 Wh/kg at the power density of 200 W/kg, and still remains 8.2 Wh/kg at 4000 W/kg.

Here, a pseudo-solution-phase ligand exchange (p-SPLE) strategy is developed for fabricating a CsPbI3 quantum dot (QD) solar cell. Using short organic aromatic ligands to partly replace the long-chain ligands in a QD solution, the p-SPLE treated CsPbI3 QD solar cell had an enhanced power conversion efficiency of up to 14.65% together with improved stability.

Facile hydrothermally synthesized PbSnS

A facile Co foam@Co3O4 porous nanosheet arrays (CPNA) has been synthesized via an in-situ oxidization reaction and there are tiny pores with diameter of 5 ± 2 nm that evenly distribute on the nanosheet with thickness of 3 ± 1 nm. The as-prepared Co foam@CPNA sample owns an ultrahigh specific capacitance of 2585 F g-1 at 5 mV s−1 and the resistance is only 1.09 Ω. It also shows a remarkable long-term stability of 77.5% capacitance retention over 20,000 charge/discharge cycles at 5 A g−1. The results suggest that the in-situ growth of Co3O4 porous nanosheet arrays on the Co foam plays an important role in its excellent electrochemical performance.

The solution-processed solar cells based on colloidal quantum dots (QDs) reported so far generally suffer from poor thickness tolerance and it is difficult for them to be compatible with large-scale solution printing technology. However, the recently emerged perovskite QDs, with unique high defect tolerance, are particularly well-suited for efficient photovoltaics. Herein, efficient CsPbI3 perovskite QD solar cells are demonstrated first with over 1 µm-thick active layer by developing an internal P/N homojunction. Specifically, an organic dopant 2,2'-(perfluoronaphthalene-2,6-diylidene) dimalononitrile (F6TCNNQ) is introduced into CsPbI3 QD arrays to prepare different carrier-type QD arrays. The detailed characterizations reveal successful charge-transfer doping of QDs and carrier-type transformation from n-type to p-type. Subsequently, the P/N homojunction perovskite QD solar cell is assembled using different carrier-type QDs, delivering an enhanced power conversion efficiency of 15.29%. Most importantly, this P/N homojunction strategy realizes remarkable thickness tolerance of QD solar cells, showing a record high efficiency of 12.28% for a 1.2 µm-thick QD active-layer and demonstrating great potential for the future printing manufacturing of QDs solar cells.

A new method was established for the determination of neohesperidin dihydrochalcone (NHDC) and naringin dihydrochalcone (Naringin DC) in feeds by solid phase extraction-high performance liquid chromatography (SPE-HPLC). The samples were extracted by methanol and were purified on an HLB solid-phase extraction column. Chromatographic separation was achieved on an XB-C18 column (150 mm×4.6 mm, 5 μm) by linear gradient elution using methanol/water as the mobile phase. The analytes were detected by the diode array detector (DAD). The results revealed a good linear correlation (r>0.999) between the peak areas and mass concentrations of dihydrochalcone sweeteners in the range of 0.2-49.0 mg/L. The limits of quantification (LOQs) of NHDC and Naringin DC were 0.02 and 0.01 mg/kg, respectively. Intra- and inter-day reproducibilities were 0.7%-4.1% and 0.9%-6.0%, respectively. The spiked recoveries for the samples and relative standard deviations (RSDs) were 86.2%-105.0% and 1.0%-6.3% (n=3), respectively. It is both sensitive and repeatable for the quantitative determination of neohesperidin dihydrochalcone and naringin dihydrochalcone in feeds, and thus, can be used to effectively reduce interference in feeds.

A method for the simultaneous detection of 21 plant growth regulators in fruits by QuEChERS-high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed. The samples were initially extracted with acetonitrile containing 1% (v/v) acetic acid, followed by clean-up using the powder of magnesium sulfate and C18. The resulting samples were separated on a C18 column, and detected under positive and negative multiple reactions monitoring (MRM) mode through polarity switching between time segments. The matrix-matched external standard calibration curves were used for quantitative analysis. The linearities of chlormequat chloride, mepiquat chloride, choline chloride, cyclanilide, forchlorfenuron, thidiazuron, inabenfide, paclobutrazol, uniconazole and triapenthenol were in the concentration range of 0.1-500 microg/L, daminozide and 6-benzylaminopurine in the concentration range of 1.0-500 microg/L, 2,3,5-triiodobenzoic acid, 2,4-D, cloprop, 4-chlorophenoxyacetic acid (4-CPA) and trinexapac-ethyl in the concentration range of 2.0-1 000 microg/L, abscisic acid (ABA), gibberellic acid (GA3), 1-naphthaleneacetic acid (NAA) and indol-3-ylacetic acid (IAA) in the concentration range of 10-1000 microg/L, with the correlation coefficients higher than 0.990. The limits of detection and the limits of quantification of the method were 0.020-6.0 microg/kg and 0.10-15.0 microg/kg, respectively. For all the samples, the average spiked recoveries ranged from 73.0% to 111.0%, and the relative standard deviations (RSDs, n = 6) were in the range of 3.0% - 17.2%. The method is quick, easy, effective, sensitive and accurate, and can meet the requirements for the determination of the 21 plant growth regulator residues in fruits.