High Efficiency Formamidinium-Cesium Perovskite-Based Radio-Photovoltaic Cells

Radio-photovoltaic cell is a micro nuclear battery for devices operating in extreme environments,which converts the decay energy of a radioisotope into electric energy by using a phosphor and a photovoltaic converter.Many phosphors with high light yield and good environmental stability have been developed,but the performance of radio-photovoltaic cells remains far behind expectations in terms of power density and power conversion efficiency,because of the poor photoelectric conversion efficiency of traditional photovoltaic converters under low-light conditions.This paper reports an radio-photovoltaic cell based on an intrinsically stable formamidinium-cesium perovskite photovoltaic converter exhibiting a wide light wavelength response from 300 to 800 nm,high open-circuit voltage(V_(oc)),and remarkable efficiency at low-light intensity.When a He ions accelerator is adopted as a mimickedαradioisotope source with an equivalent activity of 0.83 mCi cm^(-2),the formamidinium-cesium perovskite radio-photovoltaic cell achieves a V_(oc)of 0.498 V,a short-circuit current(J_(sc))of 423.94 nA cm^(-2),and a remarkable power conversion efficiency of 0.886%,which is 6.6 times that of the Si reference radio-photovoltaic cell,as well as the highest among all radio-photovoltaic cells reported so far.This work provides a theoretical basis for enhancing the performance of radio-photovoltaic cells.

In situ luminescence measurements of GaN/Al_(2)O_(3) film under different energy proton irradiations

Ion beam-induced luminescence(IBIL) experiments were performed to investigate the in situ luminescence of GaN/Al_(2)O_(3) at varying ion energies,which allowed for the measurement of defects at different depths within the material.The energies of H^(+)were set to 500 keV,640 keV and 2 MeV,the Bragg peaks of which correspond to the GaN film,GaN/Al_(2)O_(3) heterojunction and Al_(2)O_(3) substrate,respectively.A photoluminescence measurement at 250 K was also performed for comparison,during which only near band edge(NBE) and yellow band luminescence in the GaN film were observed.The evolution of the luminescence of the NBE and yellow band in the GaN film was discussed,and both exhibited a decrease with the fluence of H^(+).Additionally,the luminescence of F centers,induced by oxygen vacancies,and Cr^(3+),resulting from the ^(2)E →^(4)A_(2) radiative transition in Al_(2)O_(3),were measured using 2 MeV H^(+).The luminescence intensity of F centers increases gradually with the fluence of H^(+).The luminescence evolution of Cr^(3+)is consistent with a yellow band center,attributed to its weak intensity,and it is situated within the emission band of the yellow band in the GaN film.Our results show that IBIL measurement can effectively detect the luminescence behavior of multilayer films by adjusting the ion energy.Luminescence measurement can be excited by various techniques,but IBIL can satisfy in situ luminescence measurement,and multilayer structural materials of tens of micrometers can be measured through IBIL by adjusting the energy of the inducing ions.The evolution of defects at different layers with ion fluence can be obtained.

Green synthesis of Chlorin e6 and tests of its photosensitive bactericidal activities

Phototoxic treatments of pathogenic bacteria and fungi of trees induce oxidative damage that is preferable to toxic chemical treatment.Here,we used green methods to synthesize Chlorin e6 from chlorophyll a,which was extracted from crude silkworm excrement using concentrated(strong)alkali hydrolysis and acidification.The photosensitive bactericidal activities of the new chlorin were tested in vitro,and possible mechanisms of action are discussed.The results showed that Chlorin e6 can be lightactivated to have bactericidal activity against Escherichia coli,Bacillus subtilis and Fusarium oxysporum,but it had little bactericidal effect in the dark.This kind of chlorin compounds has great potential as a natural phototoxic antimicrobial compound to control harmful bacteria on the leaves in forestry systems.

The Polymeric Heterogemeous Matrix for Carbon and Glass Reinforced Plastic

This article presents the results of deformation-strength properties measurement and microstructural analysis of heterogeneous polymer matrix consisting of thermoset and thermoplastic polymers. Thermosetting material is a diamino-diphenil sulfon-cured epoxy oligomer. Polysulfone was used as thermoplastic material. Two different technological processes were used to obtain heterogeneous polymer matrix: the material was mixed in the block, or layered material was produced in which a layer of thermoplastic material alternated with a layer of epoxy oligomer.

High Damping and Mechanical Properties of Hydrogen-bonded Polyethylene Materials with Variable Contents of Hydroxyls:Effect of Hydrogen Bonding Density

Hydrogen bonding is considered to have significant effect on the interaction between polymeric chains and on the viscoelasticity of the polymeric materials. In this paper, we attempt to discuss the relationship between hydrogen bonding density and damping behavior and mechanical properties of polyethylene-based polymeric materials. For this reason, a series of pendant chain hydrogen bonding polymers （PCHBP） with different hydrogen bonding density （HBD） were prepared by quantitatively changing the content of pendent hydroxyl groups on the main chain of polyethylene. It was found that PCItBP with low HBD showed similar properties to polyethylene, indicating that the property of the materials was dependent mainly on the structure of the main chain. However, PCHBP with high HBD exhibited two tandpeaks and a platform of loss modulus as well as a high storage modulus （about 400 MPa） at the second tand peak temperature, demonstrating that a polymeric material with high strength and damping properties was obtained. More importantly, the maximum of loss modulus showed a linear increase with the HBD, indicating that a higher HBD greatly improved the damping properties of the polymeric materials.

Accurate reconstruction of soft X-ray energy spectrum in detector response matrix

In this paper, we report the design of a Monte Carlo simulation for the energy spectrum measurement system based on the ladderabsorption method. Herein, the detector response matrix can be calculated using the detector responses to several monochromatic X-ray beams. A novel soft X-ray spectrum unfolding method based on the two-step reverse iteration(TSRI) algorithm is applied to acquire the primary spectrum. This paper provides examples of the use of TSRI, and the unfolded energy spectra for the soft Xray beams show excellent agreement with the references. The unfolded energy spectra obtained using the TSRI exhibit better accuracy than those obtained from the commonly used unfolding code GRAVEL.

Latest developments in room-temperature semiconductor neutron detectors: Prospects and challenges

Semiconductor-based neutron-detectors are characterized by small size, high energy-resolution, good spatial resolution, and stable response(at the depletion voltage). Consequently, these neutron-detectors are important for the fields of nuclear proliferation prevention, oil exploration, monitoring neutron-scattering experiments, cancer treatments, and space radiation effect research. However, there are some well-known problems for conventional silicon-based neutron detectors: low neutron-detection efficiency and limited resistance to radiation. Therefore, critical improvements are needed to enable sufficiently effective and practical neutron detection. To address these problems, direct-conversion neutron detectors as well as wide bandgap semiconductor-based detectors have been developed and studied intensely during the past years. Significant progress with respect to detection efficiency, radiation resistance, and room temperature operation was achieved. This paper reviews the latest research highlights, remaining challenges, and emerging technologies of direct-conversion neutron detectors as well as wide-bandgap semiconductor neutron detectors. This compact review serves as a reference for researchers interested in the design and development of improved neutron detectors in the future.

Solution-processed lead-free bulk 0D Cs3Cu2I5 single crystal for indirect gamma-ray spectroscopy application

Bulk scintillators that are with high density,low cost,and fine pulse-height energy spectral resolution,and are nonhygroscopic and user friendly,are desired for high-energy gamma-ray spectroscopy application.Recently,low-cost solution-processed perovskite nanoscintillators have been demonstrated with outstanding performances for indirect low-energy X-ray detection;however,the stability and thickness are not suitable for high-energy gamma-ray detection.Here,we report scintillation performances of a low-cost solution-processed bulk 0D Cs3Cu2I5 single crystal.The self-trapped exciton emission results in a large Stokes shift (109 nm) that is reabsorption free.A broad X-ray excited emission matches well with the sensitivity of a silicon photodiode.The unique Cs+ surrounded isolated [Cu2I5]3-cluster scintillator provides ultra-stability in air and strong radiation hardness under high-dose gammaray exposure from a 60Co source.This solution-processed Cs3Cu2I5 scintillator is expected with low-cost and has detection performances comparable to commercial alkali-halide scintillator products.

High Impact Resistance Epoxy Resins by Incorporation of Quadruply Hydrogen Bonded Supramolecular Polymers

A bisphenol A based epoxy was incorporated with a quadruply hydrogen bonded supramolecular polymer as a toughening agent to prepare a composite epoxy resin with higher impact resistance. The supramolecular polymer comprising poly-（propylene glycol） bis（2-aminopropyl） ether chains and 2-ureido-4[1H]-pyrimidinone moieties（UPy） self-assembled into spherical domains with sizes of 300 nm to 600 nm in diameter by micro phase separation in bulk epoxy matrixes. A significant improvement of 300% in impact resistance of the supramolecular polymer incorporated epoxy resin was obtained when the content of supramolecular polymer was 10 wt%. Tensile tests showed that the mechanical properties of the modified epoxy resin containing the hydrogen-bonded supramolecular polymers are also improved compared with those of the neat epoxy resin.

Multi-Label Image Classification with Weak Correlation Prior

Image classification is vital and basic in many data analysis domains.Since real-world images generally contain multiple diverse semantic labels,it amounts to a typical multi-label classification problem.Traditional multi-label image classification relies on a large amount of training data with plenty of labels,which requires a lot of human and financial costs.By contrast,one can easily obtain a correlation matrix of concerned categories in current scene based on the historical image data in other application scenarios.How to perform image classification with only label correlation priors,without specific and costly annotated labels,is an important but rarely studied problem.In this paper,we propose a model to classify images with this kind of weak correlation prior.We use label correlation to recapitulate the sample similarity,employ the prior information to decompose the projection matrix when regressing the label indication matrix,and introduce the L_(2,1) norm to select features for each image.Finally,experimental results on several image datasets demonstrate that the proposed model has distinct advantages over current state-of-the-art multi-label classification methods.