Dimensionality Engineering of Organic-Inorganic Halide Perovskites for Next-Generation X-Ray Detector

The next-generation X-ray detectors require novel semiconductors with low material/fabrication cost, excellent X-ray response characteristics, and robust operational stability. The family of organic-inorganic hybrid perovskites (OIHPs) materials comprises a range of crystal configuration (i.e., films, wafers, and single crystals) with tunable chemical composition, structures, and electronic properties, which can perfectly meet the multiple-stringent requirements of high-energy radiation detection, making them emerging as the cutting-edge candidate for next-generation X-ray detectors. From the perspective of molecular dimensionality, the physicochemical and optoelectronic characteristics of OIHPs exhibit dimensionality-dependent behavior, and thus the structural dimensionality is recognized as the key factor that determines the device performance of OIHPs-based X-ray detectors. Nevertheless, the correlation between dimensionality of OIHPs and performance of their X-ray detectors is still short of theoretical guidance, which become a bottleneck that impedes the development of efficient X-ray detectors. In the review, the advanced studies on the dimensionality engineering of OIHPs are critically assessed in X-ray detection application, discussing the current understanding on the "dimensionality-property" relationship of OIHPs and the state-of-the-art progresses on the dimensionality-engineered OIHPs-based X-ray detector, and highlight the open challenges and future outlook of this field.

Promoting Ruddlesden-Popper Perovskite Formation by Tailoring Spacer Intramolecular Interaction for Efficient and Stable Solar Cells

Low-dimensional Ruddlesden-Popper phase (LDRP) perovskites are widely studied in the field of photovoltaics due to their tunable energy-band properties, enhanced photostability, and improved environmental stability compared to the 3D perovskites. However, the insulating spacers with weak intramolecular interaction used in LDRP materials limit the out-of-plane charge transport, leading to poor device performance of LDRP perovskite solar cells (PSCs). Here, a functional ligand, 3-guanidinopropanoic acid (GPA), which is capable of forming strong intramolecular hydrogen bonds through the carboxylic acid group, is employed as an organic spacer for LDRP PSCs. Owing to the strong interaction between GPA molecules, high-quality LDRP (GPA)2 (MA)n-1 Pbn I3n+1 film with promoted formation of n = 5 phase, improved crystallinity, preferential vertical growth orientations, reduced trap-state density, and prolonged carrier lifetime is achieved using GPAI as the dimensionality regulator compared to butylamine hydroiodide (BAI). As a result, GPA-based LDRP PSC exhibits a champion power conversion efficiency of 18.16% that is much superior to the BA-based LDRP PSC (15.43%). Importantly, the optimized GPA-based LDRP PSCs without encapsulation show enhanced illumination, thermal, storage, and humidity stability compared to BA-based ones. This work provides new insights into producing high n value LDRP films and their efficient and stable PSCs.

Screen-Printing Technology for Scale Manufacturing of Perovskite Solar Cells

As a key contender in the field of photovoltaics, third-generation thin-film perovskite solar cells (PSCs) have gained significant research and investment interest due to their superior power conversion efficiency (PCE) and great potential for large-scale production. For commercialization consideration, low-cost and scalable fabrication is of primary importance for PSCs, and the development of the applicable film-forming techniques that meet the above requirements plays a key role. Currently, large-area perovskite films are mainly produced by printing techniques, such as slot-die coating, inkjet printing, blade coating, and screen-printing. Among these techniques, screen printing offers a high degree of functional layer compatibility, pattern design flexibility, and large-scale ability, showing great promise. In this work, the advanced progress on applying screen-printing technology in fabricating PSCs from technique fundamentals to practical applications is presented. The fundamentals of screen-printing technique are introduced and the state-of-the-art studies on screen-printing different functional layers in PSCs and the control strategies to realize fully screen-printed PSCs are summarized. Moreover, the current challenges and opportunities faced by screen-printed perovskite devices are discussed. This work highlights the critical significance of high throughput screen-printing technology in accelerating the commercialization course of PSCs products.

Improving the Air Resistance of the Precursor Solution for Ambient-Air Coating of an Sn-Pb Perovskite Film with Superior Photovoltaic Performance

Owing to narrow band gap and low toxicity, tin-lead (Sn-Pb) hybrid perovskites have shown great potential in photovoltaic applications, and the highest power conversion efficiency (PCE) of Sn-Pb perovskite solar cells (PSCs) has recently reached 23.6%. However, it is still challenging to prepare Sn-Pb films in open-air condition due to the Sn²⁺ oxidation of the precursor solution under this condition. In this work, we report the stabilizing of the Sn-Pb perovskite precursor solution by using ionic liquid methylammonium acetate (MAAc) as the solvent, which enables the fabrication of Sn-Pb films in air. MAAc is found to coordinate with the Sn-Pb precursor via abundant hydrogen bonding, which stabilizes the colloids and protects the Sn²⁺ stability in the precursor solution in air. Therefore, the durability of the Sn-Pb precursor solution based on the MAAc solvent is greatly improved, which enables the fabrication of efficient PSCs and achieves a champion PCE of ∼16% with robust device stability. Moreover, due to the chemical interactions of MAAc with Sn-Pb perovskites, the Pb leakage is also suppressed in the MAAc-based Sn-Pb PSCs. This work demonstrates a feasible strategy for reliable fabrication of Sn-Pb PSCs, which could also be applied in many other optoelectronic devices.

Unraveling the Role of Chloride in Vertical Growth of Low-Dimensional Ruddlesden-Popper Perovskites for Efficient Perovskite Solar Cells

Recently, low-dimensional Ruddlesden-Popper (LDRP) perovskite-based solar cells (PSCs) have been extensively studied because of their robust stability. However, because of the poor conductivity of the organic spacer, the charge transport across the spacers in the LDRP perovskite is considerably poor, and thus regulation of the growth orientation of LDRP cells is of primary importance. So far, the key role of organic cations in controlling the growth orientation of LDRP films has been widely studied, but the impact of halogens has not been sufficiently investigated. Herein, we demonstrate the important role of halogens in determining the characteristics of benzylamine (BZA)-based LDRP perovskite films, where different BZAX salts (X = Cl, Br, I) are adopted. Compared to Br and I, Cl is shown to prominently enlarge the grain size, promote the vertical orientation, reduce the trap state density, and prolong the carrier lifetime of LDRP film, and all these merits effectively accelerate the carrier transport within the film. As a result, a PSC device based on BZACl delivers a champion PCE of 17.25% with much improved device stability. This work unravels the vital role of Cl in regulating the crystallization process of LDRP films, which provides a facile approach for boosting the performance of LDRP-based PSCs.

SnO2 Passivation and Enhanced Perovskite Charge Extraction with a Benzylamine Hydrochloric Interlayer

Perovskite solar cells (PSCs) have gained much attention because of their expressive power conversion efficiency (PCE) of up to 25.5%. A good contact and a well-aligned energy level at the buried interfaces between electron transport layers (ETLs) and perovskite films play an essential role in promoting charge-carrier collection and suppressing nonradiative recombination. Currently, low-temperature-processed SnO₂ thin films are widely used as the ETLs to achieve efficient and stable planar PSCs. However, fabricating proper SnO₂/perovskite interfaces with a good contact and a well-aligned energy level is necessary but implies a great challenge. Herein, we modify the SnO₂ ETL using benzylamine hydrochloride (BH), which is expected to facilitate the energy level alignment and to enhance perovskite crystallization. Moreover, the BH interlayer is found to effectively reduce the trap-state density and thereby improve the charge-carrier extraction between the ETL and the perovskite layer. Consequently, the PSC with BH modification yields a higher PCE, a lower hysteresis, and better stability than the device without a BH interlayer. This study highlights the key role of molecule modification of ETLs in designing efficient and stable PSCs.

Designing Ionic Liquids as the Solvent for Efficient and Stable Perovskite Solar Cells

As a green solvent, ionic liquids (ILs) are considered as a promising alternative to conventional polar aprotic solvents for the production of efficient and stable perovskite solar cells (PSCs). Moreover, with the use of IL solvents, perovskite films can be prepared without antisolvent treatments in an ambient environment instead of in a glovebox with inert gases, which simplifies the film manufacturing process and is favorable for industrialization production. However, the type of IL solvents that have been studied is limited, and the influence of IL molecular structures on the perovskite-film crystallization and device performance is not completely understood. In this work, four different ILs, methylammonium formate (MAF), methylammonium acetate (MAAc), methylammonium propionate (MAP), and mthylammonium isobutyrate (MAIB), are synthesized as the perovskite precursor solvents. The interaction between the functional groups of the synthesized solvents and Pb2+ in the precursor solution is studied, which has a direct impact on the morphology and crystallization of the deposited perovskite film. It is found that MAP solvent gives a high-quality perovskite film, which leads to the best photovoltaic performance with a champion PCE of 20.56% compared to the devices based on the other IL solvents. Moreover, the MAP-based device maintains 88% of its original PCE after 1000 h of storage in a N2 atmosphere, demonstrating excellent device stability. Therefore, it is concluded that MAP is the most suitable solvent for MAPbI3 films with respect to photovoltaic applications as compared to the other ILs.

In Situ Interfacial Passivation of Sn-Based Perovskite Films with a Bi-functional Ionic Salt for Enhanced Photovoltaic Performance

Environment-friendly Tin (Sn)-based perovskite solar cells (PSCs) have lately made significant development, showing tremendous promise in addressing the hazardous problems associated with Pb-based PSCs. However, even in N₂ atmospheres, the thermodynamic stability of Sn-based perovskite films and long-term stability of Sn-based PSCs are demonstrated to be poor due to the presence of interfacial defect trap states. Here, we demonstrate the post-treatment of Sn-based perovskite films with ethylenediamine formate (EDAFa₂) ion salt, serving as a bi-functional interface layer to in situ passivate the interfacial defect and improve the stability of Sn²⁺ by creating a thermodynamic chemical environment pathway. Moreover, the presence of EDAFa₂ is shown to promote the interfacial energy level alignment, which is beneficial for the charge extraction at the interface. As a result, PSC devices with a bi-functional interface achieve a champion power conversion efficiency (PCE) as high as 9.40% and enhanced stability, retaining ∼95% of the original PCE stored in a N₂ environment after ∼1960 h without encapsulation. This work highlights the significant role of an interfacial design in efficient and stable Sn-based PSCs.

Solvent Engineering of the Precursor Solution toward Large-Area Production of Perovskite Solar Cells

Solar cells based on emerging organic-inorganic hybrid perovskite materials have reached certified power conversion efficiency as high as 25.5%, showing great potential in the next generation of photovoltaics toward large-scale industrialization. The most competitive feature of perovskite solar cells (PSCs) is that the perovskite light absorber can be fabricated by a low-cost solution method. For the solution method, the characteristics of the solvent play a key role in determining the crystallization kinetics, growth orientation, and optoelectronic properties of the perovskite film. Although significant progress has been made in the field of solvent engineering in PSCs, it is still challenging for the solution method to sustainably produce industrial-scale PSCs for future commercialization applications. Herein, the advanced progress of solvent engineering of precursor solution in terms of coordination regulation and toxicity reduction is highlighted. The physical and chemical characteristics of different solvents in reducing the toxicity of the solvent system, regulating the coordination property of the precursor solution, controlling the film-forming process of the perovskite film, and adjusting the photovoltaic performance of the PSC are systematically discussed. Lastly, important perspectives on solvent engineering of the perovskite precursor solution toward future industrial production of high-performance PSCs are provided.

Stabilizing black-phase formamidinium perovskite formation at room temperature and high humidity

The stabilization of black-phase formamidinium lead iodide (α-FAPbI3) perovskite under various environmental conditions is considered necessary for solar cells. However, challenges remain regarding the temperature sensitivity of α-FAPbI3 and the requirements for strict humidity control in its processing. Here we report the synthesis of stable α-FAPbI3, regardless of humidity and temperature, based on a vertically aligned lead iodide thin film grown from an ionic liquid, methylamine formate. The vertically grown structure has numerous nanometer-scale ion channels that facilitate the permeation of formamidinium iodide into the lead iodide thin films for fast and robust transformation to α-FAPbI3. A solar cell with a power-conversion efficiency of 24.1% was achieved. The unencapsulated cells retain 80 and 90% of their initial efficiencies for 500 hours at 85°C and continuous light stress, respectively.

Polarization-Sensitive Halide Perovskites for Polarized Luminescence and Detection: Recent Advances and Perspectives

While halide perovskites (HPs) have achieved enormous success in the field of optoelectronic applications, much attention has been recently drawn to the unique polarization sensitivity of HPs, either intrinsic or extrinsic, which makes HPs a potential candidate for innovative applications in directly polarized luminescence and detection. Herein, the research status in the field of polarization-sensitive HPs, including linear polarization and circular polarization, is comprehensively summarized. To evaluate the effectiveness of HPs in generating and detecting linearly or circularly polarized light, the principles and characterization methods of polarized luminescence and detection are introduced. Sequentially, the state-of-the-art development of the strategies that induce the linear or circular polarization characteristics of HPs is systematically reviewed, based on which the application of polarization-sensitive HPs in the field of polarization luminescence and detection are summarized. Moreover, the current challenges and opportunities are discussed, and prospects of the future development in this promising field are outlined.

All-inorganic Sn-based Perovskite Solar Cells: Status, Challenges, and Perspectives

Recently, the power conversion efficiency (PCE) of perovskite solar cells (PSC) based on organic-inorganic hybrid Pb halide perovskites has reached 25.2 %. However, the toxicity of Pb has still been a main concern for the large-scale commercialization of Pb-based PSCs. Efforts have been made during the past few years to seek eco-friendly Pb-free perovskites, and it is a growing consensus that Sn is the best choice as Pb alternative over any other Pb-free metal elements. Among Sn-based perovskites, all-inorganic cells are promising candidates for PSCs owing to their more suitable bandgap, better stability, and higher charge mobility compared to the organic-inorganic hybrid counterparts. However, the poor phase stability of all-inorganic Sn-based perovskites (AISPs) and low PCE of their PSCs are most challenging in the field at present. Herein, recent developments on PSCs based on AISPs, including CsSnX₃ and Cs₂ SnX₆ (X=Br, I), are comprehensively reviewed. Primarily, the intrinsic characteristics of the two AISPs are overviewed, including crystallographic property, band structure, charge carrier property, and defect property. Sequentially, state-of-the-art progress, regarding the photovoltaic application of AISPs as light absorber, is summarized. At last, current challenges and future opportunities of AISP-based PSCs are also discussed.

Correlation study between the magnetic resonance imaging features of breast cancer and expression of immune molecular subtypes

OBJECTIVE

To investigate the correlation between breast cancer magnetic resonance imaging features and immune molecular subtypes.

PATIENTS AND METHODS

A total of 129 breast cancer patients were selected as the research object. All the patients were diagnosed by histopathology. All of them had breast magnetic resonance imaging and examination data of immunohistochemical (IHC) ER, PR, HER-2, and Ki-67. The correlation of breast cancer magnetic resonance imaging features with different immune molecular subtypes was retrospectively analyzed.

RESULTS

Breast cancer is divided into different molecular subtypes. There were 72 cases with Luminal A type (55.81%), 20 cases with Luminal B type (15.50%), 14 cases with HER-2+ type (HER-2 type for over-expression) (10.85%), 23 cases with TNBC type (ER, PR and HER-2 were negative) (17.84%). The magnetic resonance imaging features of breast cancer were included, the post-enhanced morphology, margins, internal enhancement features, time-signal intensity curve (TIC) and molecular subtype expression of lesions were significantly correlated with the immune molecular subtypes (C=0.602, 0.439, 0.350 and 0.407, p=0.000, 0.000, 0.006 and 0.000). Lesion morphology: Luminal A type was mainly oval, accounting for 76.39% (55/76). Luminal B type and HER-2+ type was mainly irregular, accounting for 75.00% (15/20) and 64.29% (9/14) respectively. TNBC type was mainly shown as lobulation, accounting for 60.87% (14/23). Margin of the lesion: Luminal A type was mainly smooth margin, accounting for 73.61% (53/72). Luminal B type and TNBC type were mainly irregular margin, accounting for 70.00% (14/20) and 56.52% (13/23) respectively. The margin of HER-2+ type was mainly spiculation, accounting for 64.29% (9/14). The internal enhancement features: Luminal A type was mainly even enhancement, accounting for 62.50% (45/72). Luminal B type and HER-2+ type were mainly heterogeneous enhancement, accounting for 65.00% (13/20) and 64.29% (9/14) respectively. TNBC type was mainly annular enhancement, accounting for 73.91% (17/23). TIC type: Luminal A type was mainly Type II, accounting for 66.67% (48/72). Luminal B, HER-2+ type and TNBC type was mainly Type III, accounting for 70.00% (14/20), 64.29% (9/14) and 60.87% (14/23) respectively. The clinical signs include painless breast lumps, bloody breast discharge, and orange peel-like skin changes, nipple retraction and nipple elevation. There is no significant correlation between the above signs and the expression of molecular subtypes (C=0.014, 0.129, 0.154, 0.097 and 0.057, p=0.999, 0.533, 0.447, 0.747 and 0.935 respectively), the difference is not statistically significant (p>0.05).

CONCLUSIONS

The characteristics of breast cancer magnetic resonance imaging was certainly correlated with the expression of immune molecular subtypes. The breast cancer molecular subtypes can be predicted by the imaging signs, which can provide valuable information for preoperative neoadjuvant treatment of breast cancer.

In Situ Interface Engineering for Highly Efficient Electron-Transport-Layer-Free Perovskite Solar Cells

Electron-transport-layer free perovskite solar cells (ETL-free PSCs) have attracted great attention due to their low cost and simple manufacturing process. However, an additional interface layer has to be introduced, and the currently achieved efficiency remains far from full-structure PSCs. Here, we report an in situ interface engineering strategy by the methylammonium acetate (MAAc) ionic liquid perovskite precursor. We found that a dipole layer was in situ constructed through the physical adsorption of the residual MAAc polar molecules on the indium tin oxide electrode, which is significantly different from the treatment by the interface layer in previous reports. This allows a decrease of the effective work function and enables in situ band bending in the perovskite semiconductor. The in situ band bending facilitates charge collection and hinders interfacial charge recombination, leading to ETL-free PSCs with a maximum power conversion efficiency of 21.08%, which is the highest report to date.

The correlation of 18F-FDG PET/CT metabolic parameters, clinicopathological factors, and prognosis in breast cancer

PURPOSE

To study the imaging parameters of ¹⁸F-fluorodeoxy glucose (¹⁸F-FDG) in breast cancer on positron emission tomography/computed tomography (PET/CT)-the correlation of clinical pathological factors and prognosis among the maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) of lesions for patients.

METHODS

From January 2012 to December 2014, a total of 125 female patients were treated in our hospital for the first time and were diagnosed as breast cancer by histopathology. They were selected as the research subjects. All of them had complete ¹⁸F-FDG PET/CT examination data before surgery, the postoperative clinicopathological information, and follow-up data. They were divided into the event group (38 cases) and the event-free group (87 cases) according to whether local recurrence or distant metastasis occurred after the follow-up, with the follow-up time 4-60 months. The correlation on ¹⁸F-FDG PET/CT metabolic parameters of breast cancer with clinicopathological factors and prognosis was retrospectively evaluated.

RESULTS

The primary lesions of 125 cases with breast cancers all had higher ¹⁸F-FDG uptake, and the SUVmax, MTV, and TLG of the primary tumors in the event group were significantly higher than those in the event-free group (t = 2.645, 2.782, 15.263, p = 0.011, 0.008, 0.000), p < 0.05; SUVmax, MTV, and TLG of primary breast cancer have no correlation with age and tumor site of patient (p > 0.05); there were statistically significant differences in the SUVmax, MTV, and TLG of primary tumor in the comparison of different tumor size, T stage, N stage, and histological grades (p < 0.05); all of SUVmax, MTV, and TLG in the estrogen receptor (ER) and/or progesterone receptor (PR) positive groups were lower than those in the negative group, with statistically significant difference (p < 0.05); the SUVmax, MTV, and TLG of human epidermal growth factor receptor 2 (HER2) positive group, proliferating cell nuclear antigen (Ki-67) high expression group were higher than those in the negative group and low expression group, with statistically significant difference (p < 0.05). There were 38 recurrence and metastasis cases within 125 cases with breast cancer in 5 years after operation, with the total recurrence and metastasis rate as 30.40% (38/125). The event-free survival rate in the SUVmax ≥ 8.64 group was significantly lower than that in the SUVmax < 8.64 group (p < 0.01).

CONCLUSIONS

The metabolic parameters of ¹⁸F-FDG PET/CT in breast cancer can reflect the biological behavior of the tumor indirectly; therefore, it was studied on the related correlation to provide the guidance of clinical individualized comprehensive treatment and prognostic judgment.

Origin of High Efficiency and Long-Term Stability in Ionic Liquid Perovskite Photovoltaic

Environment-friendly protic amine carboxylic acid ionic liquids (ILs) as solvents is a significant breakthrough with respect to traditional highly coordinating and toxic solvents in achieving efficient and stable perovskite solar cells (PSCs) with a simple one-step air processing and without an antisolvent treatment approach. However, it remains mysterious for the improved efficiency and stability of PSCs without any passivation strategy. Here, we unambiguously demonstrate that the three functions of solvents, additive, and passivation are present for protic amine carboxylic acid ILs. We found that the ILs have the capability to dissolve a series of perovskite precursors, induce oriented crystallization, and chemically passivate the grain boundaries. This is attributed to the unique molecular structure of ILs with carbonyl and amine groups, allowing for strong interaction with perovskite precursors by forming C=O…Pb chelate bonds and N-H…I hydrogen bonds in both solution and film. This finding is generic in nature with extension to a wide range of IL-based perovskite optoelectronics.

MicroRNA-19a-3p suppresses invasion and metastasis of prostate cancer via inhibiting SOX4

OBJECTIVE

To explore the role of microRNA-19a-3p in regulating invasion, metastasis and EMT (epithelial mesenchymal transition) of prostate cancer (PCa) cells, as well as its underlying mechanism.

MATERIALS AND METHODS

MicroRNA-19a-3p mimic and negative control plasmid were first constructed. After transfection of microRNA-19a-3p mimic or negative control in DU145 cells, expression levels of microRNA-19a-3p and SOX4 were detected by quantitative Real-time-polymerase chain reaction (qRT-PCR) and Western blot. The regulatory effects of microRNA-19a-3p on migration and invasion of DU145 cells were detected by wound healing assay and transwell assay, respectively. Protein levels of matrix metalloproteinase-2 (MMP2), matrix metalloproteinase-9 (MMP9), N-cadherin, Vimentin, alpha-smooth muscle actin (α-SMA) and E-cadherin in DU145 cells transfected with microRNA-19a-3p mimic or negative control were detected by Western blot.

RESULTS

Overexpression of microRNA-19a-3p inhibited protein level of SOX4 in DU145 cells. The migration and invasion of DU145 cells were inhibited after transfection of microRNA-19a-3p mimic. Protein levels of MMP2, MMP9, N-cadherin, Vimentin and α-SMA were downregulated, whereas E-cadherin was upregulated after microRNA-19a-3p overexpression.

CONCLUSIONS

MicroRNA-19a-3p inhibits migration, invasion and EMT of PCa cells via inhibiting SOX4.

Screening of reference genes using real-time quantitative PCR for gene expression studies in Neoseiulus barkeri Hughes (Acari: Phytoseiidae)

A stable reference gene is a key prerequisite for accurate assessment of gene expression. At present, the real-time reverse transcriptase quantitative polymerase chain reaction has been widely used in the analysis of gene expression in a variety of organisms. Neoseiulus barkeri Hughes (Acari: Phytoseiidae) is a major predator of mites on many important economically crops. Until now, however, there are no reports evaluating the stability of reference genes in this species. In view of this, we used GeNorm, NormFinder, BestKeeper, and RefFinder software tools to evaluate the expression stability of 11 candidate reference genes in developmental stages and under various abiotic stresses. According to our results, β-ACT and Hsp40 were the top two stable reference genes in developmental stages. The Hsp60 and Hsp90 were the most stable reference genes in various acaricides stress. For alterations in temperature, Hsp40 and α-TUB were the most suitable reference genes. About UV stress, EF1α and α-TUB were the best choice, and for the different prey stress, β-ACT and α-TUB were best suited. In normal conditions, the β-ACT and α-TUB were the two of the highest stable reference genes to respond to all kinds of stresses. The current study provided a valuable foundation for the further analysis of gene expression in N. barkeri.

Robust Stability of Efficient Lead-Free Formamidinium Tin Iodide Perovskite Solar Cells Realized by Structural Regulation

The instability issue of Pb-free Sn-based perovskite is one of the biggest challenges for its application in optoelectronic devices. Herein, a structural regulation strategy is demonstrated to regulate the geometric symmetry of formamidiniumtin iodide (FASnI₃) perovskite. Experimental and theoretical works show that the introduction of cesium cation (Cs⁺) could improve the geometric symmetry, suppress the oxidation of Sn²⁺, and enhance the thermodynamical structural stability of FASnI₃. As a result, the inverted planar Cs-doped FASnI₃-based perovskite solar cell (PSC) is shown to maintain 90% of its initial power-conversion efficiency (PCE) after 2000 h stored in N₂, which is the best durability to date for 3D Sn-based PSCs. Most importantly, the air, thermal, and illumination stabilities of the PSCs are all improved after Cs doping. The PCE of the Cs-doped PSC shows a 63% increase compared to that of the control device (from 3.74% to 6.08%) due to the improved quality of the Cs-doped FASnI₃ film.

A Strategy for Architecture Design of Crystalline Perovskite Light-Emitting Diodes with High Performance

All present designs of perovskite light-emitting diodes (PeLEDs) stem from polymer light-emitting diodes (PLEDs) or perovskite solar cells. The optimal structure of PeLEDs can be predicted to differ from PLEDs due to the different fluorescence dynamics and crystallization between perovskite and polymer. Herein, a new design strategy and conception is introduced, "insulator-perovskite-insulator" (IPI) architecture tailored to PeLEDs. As examples of FAPbBr₃ and MAPbBr₃ , it is experimentally shown that the IPI structure effectively induces charge carriers into perovskite crystals, blocks leakage currents via pinholes in the perovskite film, and avoids exciton quenching simultaneously. Consequently, as for FAPbBr₃ , a 30-fold enhancement in the current efficiency of IPI-structured PeLEDs compared to a control device with poly(3,4ethylenedioxythiophene):poly(styrene sulfonate) as hole-injection layer is achieved-from 0.64 to 20.3 cd A^-1 -while the external quantum efficiency is increased from 0.174% to 5.53%. As the example of CsPbBr₃ , compared with the control device, both current efficiency and lifetime of IPI-structured PeLEDs are improved from 1.42 and 4 h to 9.86 cd A^-1 and 96 h. This IPI architecture represents a novel strategy for the design of light-emitting didoes based on various perovskites with high efficiencies and stabilities.

High-Quality Cs2 AgBiBr6 Double Perovskite Film for Lead-Free Inverted Planar Heterojunction Solar Cells with 2.2 % Efficiency

All-inorganic double-metal perovskite materials have recently gained much attention due to their three dimensionality (3D) and non-toxic nature to replace lead-based perovskite materials. Among all those double perovskite materials, theoretical works have demonstrated that Cs₂ AgBiBr₆ shows high stability and possesses a suitable band gap for solar-cell applications. However, the film-forming ability of Cs₂ AgBiBr₆ is found to be the utmost challenge hindering its development in thin-film solar-cell devices. In this work, a high-quality Cs₂ AgBiBr₆ film with ultra-smooth morphology, micro-sized grains, and high crystallinity is realized via anti-solvent dropping technology and post-annealing at high temperature. After optimization, the first example of an inverted planar heterojunction solar-cell device based on Cs₂ AgBiBr₆ exhibits a power conversion efficiency of 2.23 % with V_OC =1.01 V, J_SC =3.19 mA/cm² , and FF=69.2 %. Besides, the device shows no hysteresis and a high stability.

Gene cloning and difference analysis of vitellogenin in Neoseiulus barkeri (Hughes)

Neoseiulus barkeri (HUGHES) is the natural enemy of spider mites, whiteflies and thrips. Screening for chemically-resistant predatory mites is a practical way to balance the contradiction between the pesticide using and biological control. In this study, the number of eggs laid by fenpropathrin-susceptible and resistant strains of N. barkeri was compared. Additionally, we cloned three N. barkeri vitellogenin (Vg) genes and used quantitative real-time polymerase chain reaction to quantify Vg expression in susceptible and resistant strains. The total number of eggs significantly increased in the fenpropathrin-resistant strain. The full-length cDNA cloning of three N. barkeri Vg genes (NbVg1, NbVg2 and NbVg3) revealed that the open reading frames of NbVg1, NbVg2 and NbVg3 were 5571, 5532 and 4728 bp, encoding 1856, 1843 and 1575 amino acids, respectively. The three N. barkeri Vg possessed the Vitellogenin-N domain (or lipoprotein N-terminal domain (LPD_N)), von Willebrand factor type D domain (VWD) and the domain with unknown function 1943 (DUF1943). The NbVg1 and NbVg2 expression levels were significantly higher in the resistant strain than in the susceptible strain, while the NbVg3 expression level was lower in the resistant strain. Thus, we speculate that the increased number of eggs laid by the fenpropathrin-resistant strain of N. barkeri may be a consequence of changes in Vg gene expression.

Rubidium Doping for Enhanced Performance of Highly Efficient Formamidinium-Based Perovskite Light-Emitting Diodes

Organometal halide perovskites (OHPs) have become the most promising optoelectronic material in the past few years with a myriad of applications in the photovoltaic, light-emitting, and laser fields. However, for light-emitting applications, the low photoluminescence quantum yield (PLQY) of OHP film is critical to hinder the efficiency improvement of OHP-film-based light-emitting diodes (PeLEDs). Herein, we study the effects of rubidium incorporation on the crystal growth, structure, and photoelectric and optical properties of formamidinium-lead-bromide-based (FAPbBr₃-based) perovskite films and light-emission performance of PeLEDs. It is found that rubidium incorporation can significantly enhance the PLQY of FAPbBr₃ film by suppressing the trap density and thus improve the withstand voltage as well as the performance of PeLEDs. When FAPbBr₃ film with optimal Rb doping ratio is employed as the light emitter of PeLEDs, the maximum luminance and current efficiency is enhanced by ∼10-fold and ∼5-fold to 66 353 cd/m² and 24.22 cd/A compared to the controlled device, respectively, the record performance based on FAPbBr₃ PeLEDs so far. The enhanced performance can be chiefly attributed to the increase of PLQY and decrease of trap defect density of perovskite film with rubidium incorporation. Our research is expected to stimulate the development of OHPs for the next-generation lighting and display fields.

Defects in metal triiodide perovskite materials towards high-performance solar cells: origin, impact, characterization, and engineering

The progress of defect science in metal triiodide perovskite is critically reviewed, including the origin, impacts, characterization, and engineering.

Multichannel Interdiffusion Driven FASnI3 Film Formation Using Aqueous Hybrid Salt/Polymer Solutions toward Flexible Lead-Free Perovskite Solar Cells

Tin (Sn)-based perovskites are increasingly attractive because they offer lead-free alternatives in perovskite solar cells. However, depositing high-quality Sn-based perovskite films is still a challenge, particularly for low-temperature planar heterojunction (PHJ) devices. Here, a "multichannel interdiffusion" protocol is demonstrated by annealing stacked layers of aqueous solution deposited formamidinium iodide (FAI)/polymer layer followed with an evaporated SnI₂ layer to create uniform FASnI₃ films. In this protocol, tiny FAI crystals, significantly inhibited by the introduced polymer, can offer multiple interdiffusion pathways for complete reaction with SnI₂ . What is more, water, rather than traditional aprotic organic solvents, is used to dissolve the precursors. The best-performing FASnI₃ PHJ solar cell assembled by this protocol exhibits a power conversion efficiency (PCE) of 3.98%. In addition, a flexible FASnI₃ -based flexible solar cell assembled on a polyethylene naphthalate-indium tin oxide flexible substrate with a PCE of 3.12% is demonstrated. This novel interdiffusion process can help to further boost the performance of lead-free Sn-based perovskites.

Construction of Compact Methylammonium Bismuth Iodide Film Promoting Lead-Free Inverted Planar Heterojunction Organohalide Solar Cells with Open-Circuit Voltage over 0.8 V

A bismuth-based organohalide material, methylammonium bismuth iodide (MA₃Bi₂I₉), has been recently explored as an efficient lead-free light absorber in photovoltaic applications. However, the poor surface morphology of the MA₃Bi₂I₉ film fabricated via conventional one-step spin-coating methods has limited the performance of the device. In this work, a smooth, uniform, and compact MA₃Bi₂I₉ thin film was realized by a novel two-step evaporation-spin-coating film fabrication strategy for the first time. Taking advantage of the superior MA₃Bi₂I₉ thin film, the best-performing inverted planar heterojuncion photovoltaic device exhibited a power conversion efficiency of 0.39% with open-circuit voltage as high as 0.83 V, which demonstrated the lowest loss-in-potential to date in MA₃Bi₂I₉-based solar cells. Moreover, the facile film fabrication strategy utilized in this work paves the way for high reproducibility of lead-free organohalide films and devices.

The role of reduction extent of graphene oxide in the photocatalytic performance of Ag/AgX (X = Cl, Br)/rGO composites and the pseudo-second-order kinetics reaction nature of the Ag/AgBr system

The role of reduction extent of GO in a graphene-based photocatalyst has been studied using Ag/AgX (X = Cl, Br)/rGO composites as a model. The pseudo-second-order kinetics reaction nature of the Ag/AgBr system was also observed.

Facile one-pot synthesis of MoS2 quantum dots-graphene-TiO2 composites for highly enhanced photocatalytic properties

We reported a simple one-pot solvothermal approach to fabricate a MoS2 quantum dots (QDs)-graphene-TiO2 (MGT) composite photocatalyst with significantly improved photocatalysis properties, which is caused by the increased charge separation, visible-light absorbance, specific surface area and reaction sites upon the introduction of MoS2 QDs.

The synthesis and mechanism exploration of europium-doped LiYF4 micro-octahedron phosphors with multilevel interiors

Multi-layered hollow LiYF4:Eu(3+) micro-octahedrons, with about 400 nm of single-layer thickness and 300 nm of interlayer space, have been synthesized via a facile hydrothermal route in the presence of surfactant ethylenediamine tetraacetic acid (EDTA). The mechanisms of the morphology evolution of the LiYF4:Eu micro-octahedrons are investigated in detail. Time-dependent experiments indicate that the growth of the micro-octahedrons undergoes four different stages including the aggregation growth of the primary YF3 particle, the transformation of the substance from the orthorhombic-phase YF3 to the tetragonal-phase LiYF4 by the Kirkendall effect with the inward diffusion of quasi-steady state LiF species, adsorption and in situ crystallization, and local Ostwald ripening. The Ostwald ripening process is terminated by the organic adsorption of interlaminar leading to a hollow structure with multilevel interiors. The LiYF4:Eu micro-octahedrons are annealed under the designed temperatures, which leads to the collapse of octahedral structures indicating the role of EDTA on building the octahedron. The spectral measurements show that the calcination approach has a stronger effect on the luminescence tuning of the LiYF4:Eu micro-octahedrons due to the modification of the crystal phase, structure and size. The present study is of great importance in the preparation of rare-earth ion doped LiYF4 hollow materials as well as in applications as building blocks for functional devices.

First Report on the Occurrence of Cucumber mosaic virus on Fragaria ananassa in China

More than 20 viruses are known to infect strawberry (Fragaria ananassa), and a substantial number of these include new viruses identified since 2000 that can contribute to disease complexes (2). The most serious virus related losses in commercial strawberries are caused by aphid transmitted viruses (3,4,5). A survey was undertaken from 2012 to 2013 to investigate virus prevalence in commercial strawberries in rural areas of Hebei Province around Beijing, China, that were exhibiting virus symptoms. Visual observations revealed that the incidence of virus-like symptoms ranged from 30 to 50% of the plants and these symptoms included yellowing, leaf malformation, sometimes combined with severe stunting and deformed flowers or fruits. Leaf samples were tested for Strawberry vein banding virus (SVBV), Strawberry mottle virus (SMoV), Strawberry mild yellow edge virus (SMYEV), and Strawberry crinkle virus (SCV), which are the four most prevalent aphid-transmitted viruses in single or mixed infections (2). Testing was conducted by RT-PCR using total RNA extracted from fresh symptomatic strawberry leaves (3). SVBV was detected in 58 of 190 samples, but all of the samples tested negative for SMoV, SMYEV, and SCV. Aphids were present on many of the plants, so the samples were tested for Cucumber mosaic virus (CMV) because CMV is prevalent in Beijing gardens and farms, and recently had been shown to infect maize in China (5). This RT-PCR was carried out with the CMV primer pair CM420-F (5'-TGATTCTACCGTGTGGGTGA-3') and CM420-R (5'-CCGTAAGCTGGATGGACAAC-3') to amplify a portion of the capsid protein coding region and the conserved 3'non-translated regions of the genomic RNAs. This test revealed the presence of 43 CMV-positives out of 190 samples, and only 16 of these samples were co-infected with both SVBV and CMV. Samples infected with CMV only had leaf malformations and yellowing, while no CMV was found in symptomless samples. One of the amplified, CMV-specific DNA fragments was sequenced directly from the PCR product and showed 93.8% nucleotide sequence identity and 100% amino acid sequence identity to the CMV subgroup I (GenBank Accession No. D10538) (1). Subsequent ELISA tests for the CMV presence verified the RT-PCR results (Agdia, Elkhart, IN), and transmission electron microscopy observations revealed 28 nm spherical particles characteristic of CMV in strawberry samples tested positive for CMV. However, we were unable to detect either CMV or SVBV in 89 of the 169 samples from symptomatic plants, which suggested possible presence of the other pathogen(s). To the best of our knowledge, this is the first report of natural infections of CMV in strawberry plants. These data suggests that CMV is a potential threat to strawberry production. References: (1) M. Q. K. Andrew et al. Virus taxonomy: IXth Report of the ICTV, 970, Elsevier, 2012. (2) R. R. Martin and I. E. Tzanetakis. Plant Dis. 97:1358, 2013. (3) J. R. Thompson et al. J. Virol. Methods 111:85, 2003. (4) I. E. Tzanetakis et al. Plant Dis. 90:1343, 2006. (5) R. Wang et al. J. Phytopathol. 161: 880, 2013.

One-pot synthesis of Ag/r-GO/TiO2 nanocomposites with high solar absorption and enhanced anti-recombination in photocatalytic applications

In this paper, we reported a simple one-pot solvothermal approach to fabricate Ag/reduced graphene oxide (r-GO)/TiO2 composite photocatalyst under atmospheric pressure. Based on the experimental data, we concluded that the introduction of Ag into classical graphene-TiO2 system (i) efficiently enlarges the absorption range, (ii) improves photogenerated electron separation and (iii) increases photocatalysis reaction sites. The optimized sample exhibits prominent photocatalysis ability as compared to pure TiO2 under simulated sunlight. We further proposed that besides the above three advantages of Ag, a different size of Ag nanoparticles is also responsible for the improved photocatalysis ability, where small size Ag nanoparticles (2-5 nm) could store a photoexcited electron that was generated from TiO2, while large-size Ag nanoparticles could utilize visible light due to their localized surface plasmon resonance (LSPR) absorption. Our present work gives new insights into the photocatalysis mechanism of noble metal/r-GO/TiO2 composites and provides a new pathway into the design of TiO2-based photocatalysts and promote their practical application in various environmental and energy issues.

A general route to enhance the fluorescence of graphene quantum dots by Ag nanoparticles

Graphene quantum dots (GQDs)/Ag nanoparticles with an unexpected quantum yield of 16.3% are synthesized by an efficient simple solvothermal method at atmospheric pressure.

One-step preparation and assembly of aqueous colloidal CdS(x)Se(1-x) nanocrystals within mesoporous TiO2 films for quantum dot-sensitized solar cells

In the field of quantum dots (QDs)-sensitized solar cells, semiconductor QDs sensitizer with a moderate band gap is required in order to sufficiently match the solar spectrum and achieve efficient charge separation. At present, changing the size of QDs is the main method used for adjusting their band gap through quantum size effect, however, the pore sizes of mesoporous TiO2 film set a limit on the allowed size of QDs. Therefore, the tuning of electronic and optical properties by changing the particle size could be limited under some circumstances. In this paper, high-quality aqueous CdS(x)Se(1-x) QDs sensitizer is successfully synthesized and effectively deposited on a mesoporous TiO2 film by a one-step hydrothermal method. In addition to size, alloy QDs provide composition as an additional dimension for tailoring their electronic properties. The alloy composition and band gap can be precisely controlled by tuning the precursor (Se/Na2S·9H2O) ratio while maintaining the similar particle size. By using such CdS(x)Se(1-x) sensitized TiO2 films as photoanodes for solar cell, a maximum power conversion efficiency of 2.23% is achieved under one sun illumination (AM 1.5 G, 100 mW cm(-2)).

Application of autologous peripheral blood stem cell transplantation in children with malignant tumor

OBJECTIVE

To investigate if low dose total body irradiation (TBI, 6.0-9.0 Gy) combined with intensified chemotherapy followed by autologous peripheral blood stem cell transplantation results in better survival in children with refractory leukemia or solid tumors.

METHODS

Twenty-one children with malignant tumors were included in this study. There were 14 males and 7 females aged 3.5-12 years. Underlying disease included high-risk acute lymphoblastic leukemia (ALL, CR1 in 3 children and CR2 in 5 children), acute myeloblastic leukemia (AML, 9 children), non-Hodgkin's lymphoma stage IV (2 children), and neuroblastoma stage IV (2 children). The peripheral hematopoietic stem cells were collected six to eleven months after complete response, mobilized with high dose chemotherapy alone or combined with GM-CSF or G-CSF. The conditioning regimen consisted of chemotherapy with two to three combinations of the following drugs: cyclophosphamide, arabinosylcytosine, McNU, etopside, and ldarubicin on the basis of TBI (6.0-9.0 Gy). A mean of (1.8 +/- 0.5) x 10(8)/kg autologous mononuclear cells were transplanted. The patients were followed up after transplantation.

RESULTS

Severe bone marrow suppression occurred in all patients around day +7. Peripheral white blood cell count decreased to 0 in all patients at day +4.8 +/- 2.9, and platelet count decreased to less than 20 x 10(9)/L at day +9.0 +/- 2.6. Successful engraftment was achieved in 21 patients, but four died of infection at day +17, +20, +31 and +67, respectively. Recovery of white blood cell (WBC) to 10 x 10(9)/L, absolute neutrophil count to 0.5 x 10(9)/L, platelet count to 20 x 10(9)/L occurred on 21 +/- 12, 26 +/- 13, and 27 +/- 10 days, respectively. During the follow up period, three patients relapsed at months, +1.5 years, and +2 years 10 months, respectively. One patient died of intracranial hemorrhage at +8 months. Thirteen patients had event-free survival for 2-12 years, with a mean of 6.7 +/- 3.4 years.

CONCLUSION

Our preliminary data suggest that myeloablative therapy with low dose TBI (6.0-9.0 Gy) combined with intensified chemotherapy followed by autologous peripheral blood stem cell transplantation might be associated with favorable results in children with refractory leukemia or solid tumors.

[Detection of minimal residual disease in childhood hematological malignancies and its clinical significance]

OBJECTIVE

Exploring the detection of minimal residual malignant cells in bone marrow from children with hematological malignancies to predict the prognosis.

METHODS

Seventy-five patients with acute lymphoblastic leukemia (ALL), stage IV non-Hodgkin's lymphoma or stage IV neuroblastoma were studied. Complete remission was maintained for over 3 months before the detection. Minimal residual disease was detected by polymerase chain reaction (PCR) for IgH and TcRgamma rearrangements in lymphoid tumors by reverse transcriptase-polymerase chain reaction (RT-PCR) for neuroblastoma patients.

RESULTS

Thirty five patients were positive for minimal residual disease, and 21 of them (60%) relapsed 3 - 40 months later, while only 7 (17%) negative patients relapsed (chi(2) = 12.59, P < 0.01).

CONCLUSION

Minimal residual disease detection in bone marrow by PCR might predict prognosis in some childhood hematological malignancies.

A glimpse of community-based rehabilitation in China

As in other developing countries, community-based rehabilitation (CBR) in China is very important. However, because of differences in the social system, economy, and cultural level, it is impossible to implement a uniform model of CBR. This paper introduces material to show how CBR in China tends to be spontaneous. Experience of CBR stations in Shenyang has initiated a new approach to CBR within the cultural characteristics of China.

[Study of serological diagnosis in ocular chlamydial infection with IPAZYME]

We employed a indirect immunoperoxidase assay (IPAZYME in the evaluation of IgG and IgA antibody for Chlamydia trachomatis in serum samples from 218 patients such as cicatricial trachoma 55 cases, culture-positive adult inclusion conjunctivitis 48 cases and culture-negative conjunctivitis 47 cases, aged people, 68 cases as controls respectively. Frequency of positive IgG antibody showed a significant difference between adult inclusion conjunctivitis or cicatricial trachoma and controls. IgA antibody was positive in 25/48 (52%) in adult inclusion conjunctivitis and in 7/55 (12%) in cicatricial trachoma cases. Serum IgA antibody against Chlamydia trachomatis is of value to be an index of active ocular chlamydial inflammation. The correlation between severity of conjunctival cicatrix or corneal punnus and titers of IgG antibody was also significant.