Cold-Sintered All-Inorganic Perovskite Bulk Composite Scintillators for Efficient X-ray Imaging.

Cost-effective bulk scintillators with high density, large-area, and long-term stability are desirable for high-energy radiation detections. Conventional bulk polycrystalline or single-crystal scintillators are generally synthesized by high-temperature approaches, and it is challenging to realize simultaneously high detectivity/responsivity, spatial resolution, and rapid time response. Here, we report the cold sintering of bulk scintillators (at 90 °C) based on an "emitter-in-matrix" principle, in which emissive CsPbBr3 nanocrystals are embedded in a durable and transparent Cs4PbBr6 matrix. These bulk scintillators exhibit high light yield (33,800 photons MeV-1), low detection limit (79 nGyair s-1), fast decay time (9.8 ns), and outstanding spatial resolution of 8.9 lp mm-1 to X-ray radiation and an energy resolution of 19.3% for γ-ray (59.6 keV) detection. The composite scintillator also shows exceptional stability against environmental degradation and cyclic X-ray radiation. Our results demonstrate a cost-effective strategy for developing perovskite-based bulk transparent scintillators with exceptional performance and high radioluminescence stability for high-energy radiation detection and imaging.

Genome assembly of Ottelia alismoides, a multiple-carbon utilisation aquatic plant.

OBJECTIVES: Ottelia Pers. is in the Hydrocharitaceae family. Species in the genus are aquatic, and China is their centre of origin in Asia. Ottelia alismoides (L.) Pers., which is distributed worldwide, is a distinguishing element in China, while other species of this genus are endemic to China. However, O. alismoides is also considered endangered due to habitat loss and pollution in some Asian countries. Ottelia alismoides is the only submerged macrophyte that contains three carbon dioxide-concentrating mechanisms, i.e. bicarbonate (HCO3-) use, crassulacean acid metabolism and the C4 pathway. In this study, we present its first genome assembly to help illustrate the various carbon metabolism mechanisms and to enable genetic conservation in the future. DATA DESCRIPTION: Using DNA and RNA extracted from one O. alismoides leaf, this work produced ∼ 73.4 Gb HiFi reads, ∼ 126.4 Gb whole genome sequencing short reads and ∼ 21.9 Gb RNA-seq reads. The de novo genome assembly was 6,455,939,835 bp in length, with 11,923 scaffolds/contigs and an N50 of 790,733 bp. Genome assembly completeness assessment with Benchmarking Universal Single-Copy Orthologs revealed a score of 94.4%. The repetitive sequence in the assembly was 4,875,817,144 bp (75.5%). A total of 116,176 genes were predicted. The protein sequences were functionally annotated against multiple databases, facilitating comparative genomic analysis.

Draft genome of Brasenia schreberi, a worldwide distributed and endangered aquatic plant.

OBJECTIVES: Brasenia is a monotypic genus in the family of Cabombaceae. The only species, B. schreberi, is a macrophyte distributed worldwide. Because it requires good water quality, it is endangered in China and other countries due to the deterioration of aquatic habitats. The young leaves and stems of B. schreberi are covered by thick mucilage, which has high medical value. As an allelopathic aquatic plant, it can also be used in the management of aquatic weeds. Here, we present its assembled and annotated genome to help shed light on medial and allelopathic substrates and facilitate their conservation. DATA DESCRIPTION: Genomic DNA and RNA extracted from B. schreberi leaf tissues were used for whole genome and RNA sequencing using a Nanopore and/or MGI sequencer. The assembly was 1,055,148,839 bp in length, with 92 contigs and an N50 of 22,379,495 bp. The repetitive elements in the assembly were 555,442,205 bp. A completeness assessment of the assembly with BUSCO and compleasm indicated 88.4 and 90.9% completeness in the Eudicots database and 95.4 and 96.6% completeness in the Embryphyta database. Gene annotation revealed 67,747 genes that coded for 73,344 proteins.

Chromosome-level genome assembly and demographic history of Euryodendron excelsum in monotypic genus endemic to China.

Euryodendron excelsum is in a monotypic genus Euryodendron, endemic to China. It has intermediate morphisms in the Pentaphylacaceae or Theaceae families, which make it distinct. Due to anthropogenic disturbance, E. excelsum is currently found in very restricted and fragmented areas with extremely small populations. Although much research and effort has been applied towards its conservation, its long-term survival mechanisms and evolutionary history remain elusive, especially from a genomic aspect. Therefore, using a combination of long/short whole genome sequencing, RNA sequencing reads, and Hi-C data, we assembled and annotated a high-quality genome for E. excelsum. The genome assembly of E. excelsum comprised 1,059,895,887 bp with 99.66% anchored into 23 pseudo-chromosomes and a 99.0% BUSCO completeness. Comparative genomic analysis revealed the expansion of terpenoid and flavonoid secondary metabolite genes, and displayed a tandem and/or proximal duplication framework of these genes. E. excelsum also displayed genes associated with growth, development, and defence adaptation from whole genome duplication. Demographic analysis indicated that its fluctuations in population size and its recent population decline were related to cold climate changes. The E. excelsum genome assembly provides a highly valuable resource for evolutionary and ecological research in the future, aiding its conservation, management, and restoration.

Large-Area Uniaxial-Oriented Growth of Free-Standing Thin Films at the Liquid-Air Interface with Millimeter-Sized Grains.

Manipulating materials at the atomic scale and assembling them into macroscopic structures with controlled dimensionalities and single-crystal quality are grand scientific challenges. Here, we report a general solvent evaporation method to synthesize large-area uniaxial-oriented growth of free-standing thin films at the liquid-air interface. Crystals nucleate at the solution surface and rotate into the same orientation under electrostatic interaction and then merge as large crystals and grow laterally into a large-area uniform thin film with millimeter-sized grains. The lateral dimension is confined only by the size of containers. The film thickness can be tuned by adjusting solvent evaporation rate (R) and solute diffusivity (D), and a characteristic length, L*∼DR, was derived to estimate the film thickness. Molecular dynamic (MD) simulations reveal a concentration spike at the liquid-air interface during fast solvent evaporation, leading to the lateral growth of thin films. The large-area uniaxial oriented films are demonstrated on both inorganic metal halides and hybrid metal halide perovskites. The solvent evaporation approach and the determination of key parameters enabling film thickness prediction are beneficial to the high throughput and scalable production of single crystal-quality thin film materials under controlled evaporation conditions.

Poly(vinylidene fluoride)-Stabilized Black γ-Phase CsPbI3 Perovskite for High-Performance Piezoelectric Nanogenerators.

Halide perovskite materials have been recently recognized as promising materials for piezoelectric nanogenerators (PENGs) due to their potentially strong ferroelectricity and piezoelectricity. Here, we report a new method using a poly(vinylidene fluoride) (PVDF) polymer to achieve excellent long-term stable black γ-phase CsPbI3 and explore the piezoelectric performance on a CsPbI3@PVDF composite film. The PVDF-stabilized black-phase CsPbI3 perovskite composite film can be stable under ambient conditions for more than 60 days and over 24 h while heated at 80 °C. Piezoresponse force spectroscopy measurements revealed that the black CsPbI3/PVDF composite contains well-developed ferroelectric properties with a high piezoelectric charge coefficient (d 33) of 28.4 pm/V. The black phase of the CsPbI3-based PVDF composite exhibited 2 times higher performance than the yellow phase of the CsPbI3-based composite. A layer-by-layer stacking method was adopted to tune the thickness of the composite film. A five-layer black-phase CsPbI3@PVDF composite PENG exhibited a voltage output of 26 V and a current density of 1.1 µA/cm2. The output power can reach a peak value of 25 µW. Moreover, the PENG can be utilized to charge capacitors through a bridge rectifier and display good durability without degradation for over 14 000 cyclic tests. These results reveal the feasibility of the all-inorganic perovskite for the design and development of high-performance piezoelectric nanogenerators.

Gender Specificity and Local Socioeconomic Influence on Association of GHR fl/d3 Polymorphism With Growth and Metabolism in Children and Adolescents.

Objective: Growth hormone receptor (GHR) mediates most GH biological actions. This study is aimed to evaluate whether GHR fl/d3 polymorphism contributes to the inter-individual variability of growth and metabolism in healthy children and adolescents. Methods: A total of 4,730 students aged 6-16 years from Yixing and Suqian City in China were included in this cross-sectional study. Height and body mass index (BMI) were transformed into the form of z-score corresponding to age and gender. Logistic regression was used to evaluate the associations of GHR fl/d3 polymorphism with height, BMI, metabolic traits, and hypertension by estimating the odds ratios (ORs) and 95% confidence intervals (CIs). Results: GHR d3 allele was inversely associated with overweight, total cholesterol (TC) and triglyceride (TG) levels (OR [95% CI] for overweight: 0.754 [0.593-0.959], P = 0.021; OR [95% CI] for TC: 0.744 [0.614-0.902], P = 0.003; OR [95% CI] for TG: 0.812 [0.654-0.998], P = 0.047). GHR d3 allele was associated with decreased odds of pre-hypertension in boys (OR [95% CI]: 0.791 [0.645-0.971], P = 0.025), but associated with increased odds of pre-hypertension and hypertension in girls (ORs [95% CIs]: 1.379 [1.106-1.719], P = 0.004; OR [95% CI]: 1.240 [1.013-1.519], P = 0.037). Interaction of GHR fl/d3 polymorphism with gender contributed to increased odds of pre-hypertension and hypertension (interactive ORs [95% CIs]: 1.735 [1.214-2.481], P = 0.003; OR [95% CI]: 1.509 [1.092-2.086], P = 0.013). Stratification analysis showed that the correlation tendencies of GHR fl/d3 polymorphism and BMI with age were different between two cities with discrepant economic development levels. Conclusion: GHR fl/d3 polymorphism is associated with growth, metabolism, and hypertension in children and adolescents with the gender specificity, and the genetic effect of GHR fl/d3 may be modified by the local socioeconomic levels.

Performance-Improved Highly Integrated Uniaxial Tristate Hybrid Nanogenerator for Sustainable Mechanical Energy Harvesting.

Despite advances in the development of individual nanogenerators, the level of output energy generation must be increased to meet the demands of commercial electronic systems and to broaden their scope of application. To harvest low-frequency ambient mechanical energy more efficiently, we proposed a highly integrated hybridized piezoelectric-triboelectric-electromagnetic (tristate) nanogenerator in a uniaxial structure. In its highly integrated approach, a piezoelectric nanogenerator (PENG) based on CsPbBr3 (cesium lead bromide) nanoparticles (NPs) and poly(dimethylsiloxane) (PDMS) nanocomposite was fabricated on a triboelectrically negative nanostructured polyimide (PI) substrate. A cylindrical aluminum electrode grooved with permanent magnets was directed to move along a spring-less metallic guide bounded by these nanocomposites, thus essentially forming two single-electrode mode triboelectric nanogenerators (TENGs). By its optimized material design and novel integration approach of the PENGs, TENGs, and electromagnetic generators (EMGs), this uniaxial tristate hybrid nanogenerator (UTHNG) can synergistically produce an instantaneous electrical power of 49 mW at low-frequency ambient vibration (5 Hz). The UTHNG has excellent charging characteristics, ramping up the output voltage of a 22 µF capacitor to 2.7 V in only 12 s, which is much faster than individual nanogenerators. This work will be a superior solution for harvesting low-frequency ambient energies by improving the performance of hybrid nanogenerators, potentially curtailing the technology gap for self-powered micro/nanosystems for the Internet of Things.

Perovskite-Derived Cs2SnCl6-Silica Composites as Advanced Waste Forms for Chloride Salt Wastes.

Advanced materials and processes are required to separate halides and fission products from complex salt waste streams associated with the chemical reprocessing of used nuclear fuels and molten salt reactor technologies for immobilization into chemically durable waste forms. In this work, we explore an innovative concept using metal halide perovskites as advanced host phases to incorporate Cs and Cl with very high waste loadings. Wet chemistry-synthesized Cs2SnCl6 powders from CsCl salt solutions are successfully encapsulated into a silica matrix to form a composite using low-temperature spark plasma sintering with tunable Cs and Cl loadings up to 31 and 26 wt %, respectively. Chemical durability testing of the composite waste forms by semi-dynamic leaching experiments demonstrates that an incongruent leaching mechanism dominates the release of Cs and Cl. The metal halide perovskite-silica composite waste forms display exceptional chemical durability with the long-term release rates of Cs and Cl comparable to or outperforming the state-of-the-art waste form materials but with significantly higher waste loadings. The scalable synthesis of the metal halide perovskite from wet chemistry processes opens up new opportunities in designing advanced waste forms for salt wastes with very high waste loadings and exceptional chemical durability for the sustainable development of advanced fuel cycles and next-generation reactor technologies.

Immobilization of cesium and iodine into Cs3Bi2I9 perovskite-silica composites and core-shell waste forms with high waste loadings and chemical durability.

Cs3Bi2I9, a defect perovskite derivative, is a potential host phase to immobilize iodine and cesium with high waste loadings. In this work, two strategies were explored to form Cs3Bi2I9-silica composites and a core-shell structure in order to improve chemical durability of waste form materials meanwhile maintaining high waste loadings. Cs3Bi2I9 loadings as high as 70 wt.% were incorporated into a silica matrix to form silica-ceramic composites, and 20 wt.% Cs3Bi2I9 was encapsulated into silica to form a core-shell structure by low temperature spark plasma sintering. Chemical durability of the composite and core-shell waste forms was evaluated by semi-dynamic leaching experiments, and Cs and I were incongruently released from waste form matrices. A BiOI alteration layer formed, acting as a passivation layer to reduce the release of radionuclides. The long-term iodine release rate was low (30 mg m-2 day-1) for the 70 wt.% Cs3Bi2I9-silica composite leached in deionized water at 90 °C, which can be further reduced to 5 × 10-3 mg m-2 day-1 for the 20 wt.% core-shell structure. This work highlights a robust way to immobilize the highly mobile radionuclides with high waste loadings through encapsulation into durable matrices and a surface passivating mechanism that can greatly reduce the elemental transport from waste form materials and significantly enhance their chemical durability.

Kinetically Controlled Growth of Sub-Millimeter 2D Cs2 SnI6 Nanosheets at the Liquid-Liquid Interface.

Cs2 SnI6 perovskite displays excellent air stability and a high absorption coefficient, promising for photovoltaic and optoelectronic applications. However, Cs2 SnI6 -based device performance is still low as a result of lacking optimized synthesis approaches to obtain high quality Cs2 SnI6 crystals. Here, a new simple method to synthesize single crystalline Cs2 SnI6 perovskite at a liquid-liquid interface is reported. By controlling solvent conditions and Cs2 SnI6 supersaturation at the liquid-liquid interface, Cs2 SnI6 crystals can be obtained from 3D to 2D growth with controlled geometries such as octahedron, pyramid, hexagon, and triangular nanosheets. The formation mechanisms and kinetics of complex shapes/geometries of high quality Cs2 SnI6 crystals are investigated. Freestanding single crystalline 2D nanosheets can be fabricated as thin as 25 nm, and the lateral size can be controlled up to sub-millimeter regime. Electronic property of the high quality Cs2 SnI6 2D nanosheets is also characterized, featuring a n-type conduction with a high carrier mobility of 35 cm2 V-1 s-1 . The interfacial reaction-controlled synthesis of high-quality crystals and mechanistic understanding of the crystal growth allow to realize rational design of materials, and the manipulation of crystal growth can be beneficial to achieve desired properties for potential functional applications.

Ultrasensitive UV Photodetector Based on Interfacial Charge-Controlled Inorganic Perovskite-Polymer Hybrid Structure.

In this work, we demonstrate an ultrasensitive, visible-blind ultraviolet (UV) photodetector based on perovskite-polymer hybrid structure. A novel wide-band-gap vacancy-ordered lead-free inorganic perovskite Cs2SnCl6 with Nd3+ doping is employed in the active layer of this hybrid photodetector. Remarkably, with interfacial charge-controlled hole-injection operating mechanism, our device achieves a maximum detectivity of 6.3 × 1015 Jones at 372 nm, fast photoresponse speed with rise time and fall time in the order of milliseconds, and a large linear dynamic range of 118 dB. The performance is significantly better than most of the existing organic and inorganic semiconductor UV photodetectors reported so far, and its detectivity is close to 1 order of magnitude higher than that of the photomultiplication tube (PMT) in the UV region. In addition, the photodetector demonstrated excellent environmental stability, which is critical for commercial deployment of perovskite-based optoelectronic devices. The results presented in this work open a new route toward development of high-performance optoelectronic devices using perovskite-based hybrid nanomaterial systems.

Microfluidics-enabled orientation and microstructure control of macroscopic graphene fibres.

Macroscopic graphene structures such as graphene papers and fibres can be manufactured from individual two-dimensional graphene oxide sheets by a fluidics-enabled assembling process. However, achieving high thermal-mechanical and electrical properties is still challenging due to non-optimized microstructures and morphology. Here, we report graphene structures with tunable graphene sheet alignment and orientation, obtained via microfluidic design, enabling strong size and geometry confinements and control over flow patterns. Thin flat channels can be used to fabricate macroscopic graphene structures with perfectly stacked sheets that exhibit superior thermal and electrical conductivities and improved mechanical strength. We attribute the observed shape and size confinements to the flat distribution of shear stress from the anisotropic microchannel walls and the enhanced shear thinning degree of large graphene oxide sheets in solution. Elongational and step expansion flows are created to produce large-scale graphene tubes and rods with horizontally and perpendicularly aligned graphene sheets by tuning the elongational and extensional shear rates, respectively.

DFT Study on Intermetallic Pd-Cu Alloy with Cover Layer Pd as Efficient Catalyst for Oxygen Reduction Reaction.

Detailed density functional theory (DFT) calculations of the adsorption energies (Ead) for oxygen on monolayer Pd on top of the Pd-Cu face-centered cubic (FCC) alloy and intermetallic B2 structure revealed a linear correspondence between the adsorption energies and the d-band center position. The calculated barrier (Ebarrier) for oxygen dissociation depends linearly on the reaction energy difference (ΔE). The O2 has a stronger adsorption strength and smaller barrier on the intermetallic Pd-Cu surface than on its FCC alloy surface. The room-temperature free energy (ΔG) analysis suggests the oxygen reduction reaction (ORR) pathways proceed by a direct dissociation mechanism instead of hydrogenation into OOH. These results might be of use in designing intermetallic Pd-Cu as ORR electrocatalysts.

HIV-1 diversity in infected individuals in Suzhou and Suqian, China.

Jiangsu is one province with severe HIV-1 epidemic in China. However, the molecular epidemiological characterizations of HIV-1 in many cities of Jiangsu remain unclear. A molecular epidemiological investigation was performed based on 38 HIV-positive samples collected from Suzhou and Suqian during 2011-2013. Five HIV-1 genomic fragments, p17, pol, vif-vpr, vpr-env, and C2V3 were amplified and sequenced from these samples. HIV-1 group M subtype of each sample was determined by phylogenetic analyses with the standard reference sequences. Among these infected individuals, 81.6 % (31/38) self-reported to be infected via sexual contacts, including 50.0 % (19/38) via heterosexual contact and 31.6 % (12/38) via homosexual contact. Among 34 samples with available pol or vif-env sequence, 19 (55.9 %) CRF01_AE, 7 (20.6 %) CRF07_BC, 3 (8.8 %) CRF08_BC, and 5 (14.7 %) inter-subtype recombinants were identified. No pure B, B' and C subtypes were found in this cohort. The five recombinants contain one B/C, three CRF01/B and one CRF01/B/C recombinants. These results suggest that CRF01_AE was the most predominant HIV-1 group M subtype and CRF01_AE-involved recombinants were the major recombinant forms. Comparison showed that there was no obvious difference in HIV-1 group M subtype distribution between Jiangsu (including Suzhou and Suqian) and the surrounding provinces (e.g., Shanghai, Anhui, and Shandong). CRF01_AE and CRF07_BC were the top two predominant HIV-1 genotypes in Jiangsu, and less and/or no pure subtype B and C was currently circulating here. We predicted that more CRF01/CRF07 recombinants, but fewer B/C recombinants will be generated in Jiangsu in future.

Thickness-Induced Metal-Insulator Transition in Sb-doped SnO2 Ultrathin Films: The Role of Quantum Confinement.

A thickness induced metal-insulator transition (MIT) was firstly observed in Sb-doped SnO2 (SnO2:Sb) epitaxial ultrathin films deposited on sapphire substrates by pulsed laser deposition. Both electrical and spectroscopic studies provide clear evidence of a critical thickness for the metallic conductivity in SnO2:Sb thin films and the oxidation state transition of the impurity element Sb. With the shrinkage of film thickness, the broadening of the energy band gap as well as the enhancement of the impurity activation energy was studied and attributed to the quantum confinement effect. Based on the scenario of impurity level pinning and band gap broadening in quantum confined nanostructures, we proposed a generalized energy diagram to understand the thickness induced MIT in the SnO2:Sb system.

Gate-tuned quantum oscillations of topological surface states in ß-Ag2Te.

We report the strong experimental evidence of the existence of topological surface states with large electric field tunability and mobility in ß-Ag2Te. Pronounced 2D Shubnikov-de Haas oscillations have been observed in ß-Ag2Te nanoplates. A Berry phase is determined to be near π using the Landau level fan diagram for a relatively wide nanoplate while the largest electric field ambipolar effect in topological insulator so far (~2500%) is observed in a narrow nanoplate. The π Berry phase and the evolution of quantum oscillations with gate voltage (Vg) in the nanoplates strongly indicate the presence of topological surface states in ß-Ag2Te. Moreover, the mobility of the narrow Ag2Te nanoplate is about several thousand cm(2)s(-1)V(-1). Our results suggest that ß-Ag2Te has the potential to become an important material in the investigation of topological insulators.

An epitaxial ferroelectric tunnel junction on silicon.

Epitaxially grown functional perovskites on silicon (001) and the ferroelectricity of a 3.2 nm thick BaTiO3 barrier layer are demonstrated. The polarization-switching-induced change in tunneling resistance is measured to be two orders of magnitude. The obtained results suggest the possibility of integrating ferroelectric tunnel junctions as binary data storage media in non-volatile memory cells on a silicon platform.

Vertically oriented graphene bridging active-layer/current-collector interface for ultrahigh rate supercapacitors.

Dense networks of graphene nanosheets standing vertically on a current collector can work as numerous electrically conductive bridges to facilitate charge transport and mitigate the constriction/spreading resistance at the interface between the active material and the current collector. The vertically oriented graphene-bridged supercapacitors present excellent rate and power capabilities.

Evaluation of the association between the AC3 genetic polymorphisms and obesity in a Chinese Han population.

BACKGROUND: AC3 is one of adenylyl cyclase isoforms involved in cAMP and insulin signaling pathway. Recent reports have demonstrated that the AC3 genetic polymorphisms are associated with obesity in a Swedish population. AC3 knock out mice exhibit obese when they age. These findings suggest that AC3 plays an important role in the regulation of body weight. METHODOLOGY/PRINCIPAL FINDINGS: In the present study, we evaluated the association between the AC3 genetic polymorphisms and obesity in a Han Chinese population. A total of 2580 adults, including 1490 lean (BMI = 18.5-23.9), 677 overweight (BMI 24.0-27.9) and 413 obese (BMI ≥28.0) subjects were genotyped for 5 TagSNPs in the AC3 gene. Single maker association analyses indicated that SNP rs753529 was significantly associated with BMI in obese subjects (P = 0.022, OR = 0.775 95%CI = 0.623-0.963), but not in overweight subjects (P = 0.818). Multiple maker association analyses showed that the haplotype (G-G-G) constructed with SNPs rs1127568, rs7604576 and rs753529 was significantly associated with obesity (P = 0.029). Further genotyping of SNP rs753529 in 816 children, including 361 overweight subjects (BMI>P(80)) and 455 controls (BMI = P(20-50)) were performed, and no significant association with BMI was found. All tests were adjusted for age, sex, physical activity index, household income and/or diet expenses. CONCLUSIONS: The present study provides replication evidence that the AC3 genetic polymorphisms are associated with decreased risk of obesity among adults but not in children in a Chinese Han population. The data also suggest that the AC3 genetic effects on BMI may have interaction with the factors related to ageing and environment.