Predicting Requirements Change Propagation Based on Software Architecture

Change propagation is a central issue in software development process. In early stages of software development, software architecture facilitates the component-based software development process and provides a platform for prediction of requirements change. Keywords: software architecture, requirements change propagation, architectural pattern This paper aims to predict change propagation in early stages of software development, and evaluate the architecture based on architectural pattern. In order to achieve this goal, the change propagation probability is formally defined, and the change propagation in five architectural patterns is discussed. Moreover, change propagation density is defined to extend the pattern-based propagation, which incorporates design metrics into software architecture evaluation. The efficiency of the proposed method is demonstrated through a computational experiment

Transcriptome Analysis Revealed the Possible Reasons for the Change of Ni Resistance in <i>Rhus typhina</i> after Spraying Melatonin

Melatonin (MT) plays an important role in alleviating the stress of soil heavy metal pollution on plants. However, its ability to improve the tolerance of Rhus typhina to Ni stress and its mechanism of action are still unclear. Therefore, MT (0, 50, 100, and 200 μmol·L−1) was sprayed on the leaf surface of R. typhina seedlings under Ni (0 and 250 mg·kg−1) stress to study the differences in growth, physiology, and gene expression. The results showed that exogenous MT could improve the ability of R. typhina to resist Ni stress by inhibiting the degradation of chlorophyll and carotenoid, enhancing photosynthesis, and augmenting the activity of antioxidant enzymes. Moreover, 100 μmol·L−1 MT could increase the Ni concentration in R. typhina seedlings and reduce the translocation factor. Transcriptome analysis showed that MT mainly regulated the expression of related genes in plant hormone signal transduction, starch and sucrose metabolism, and various amino acid metabolism pathways. This study combined physiological and transcriptomic analysis to reveal the molecular mechanism of MT enhancing Ni resistance in R. typhina, and provides a new direction for expanding its application in phytoremediation

Melatonin Mitigates Water Deficit Stress in <i>Cenchrus alopecuroides</i> (L.) Thunb through Up-Regulating Gene Expression Related to the Photosynthetic Rate, Flavonoid Synthesis, and the Assimilatory Sulfate Reduction Pathway

Melatonin can improve plant adaptability to water deficit stress by regulating the biosynthesis of flavonoids and improving the reactive oxygen species-scavenging enzyme system. However, it remains unclear whether melatonin mitigates the effects and causes of water deficit stress in Cenchrus alopecuroides. We conducted a PEG-simulated water stress pot experiment to determine whether and how exogenous melatonin alleviates water deficit in C. alopecuroides. The experiment was divided into four treatments: (1) normal watering (Control), (2) 40% PEG-6000 treatment (D), (3) 100 μmol·L−1 melatonin treatment (MT), and (4) both melatonin and PEG-6000 treatment (DMT). The results showed that melatonin can alleviate water deficit in C. alopecuroides by effectively inhibiting plant chlorophyll degradation and MDA accumulation while increasing antioxidant enzyme activities and photosynthetic rates under water deficit stress. The transcriptome results indicated that melatonin regulates the expression of genes with the biosynthesis pathway of flavonoids (by increasing the expression of PAL, 4CL, HCT, and CHS), photosynthesis-antenna proteins (by increasing the expression of LHC), and sulfur metabolism (the expression of PAPSS and CysC is up-regulated in the assimilatory sulfate reduction pathway), while up-regulating the transcription factors (AP2/ERF-ERF-, C2H2-, WRKY-, Tify-, bHLH-, NAC-, and MYB-related). These findings revealed the possible causes by which melatonin mitigates water deficit stress in C. alopecuroides, which provided novel insights into the role of melatonin in water deficit stress

Enhanced stability of lead-free double perovskite Cs2Na1-xBi1-xMn2xCl6 microcrystals and their optoelectronic devices under high humidity environment by SiO2 encapsulation

The current studies on lead-free double perovskites (DPs) have mainly focused on the optimization of their optical properties, while less attention has been paid to their optical stability under high humidity environment. However, optoelectronic devices will inevitably be exposed to high humidity environment in practical applications so that investigating the optical stability of lead-free DPs under high humidity environment will be especially important for its subsequent development. We prepared lead-free DP Cs2Na1−xBi1−xMn2xCl6 microcrystals (MCs) with different Mn2+ content by the solution method at room temperature, where the photoluminescence quantum yield (PLQY) of Cs2Na0.8Bi0.8Mn0.4Cl6 MCs achieved a maximum of 22.3% with 20% doping of Mn2+, subsequently tested for stability under high humidity environment. The results indicated that the structure and fluorescence properties of Cs2Na0.8Bi0.8Mn0.4Cl6 MCs were destroyed after being contacted with water molecules and that Cs2Na0.8Bi0.8Mn0.4Cl6 MCs was subsequently restored again by using hydrochloric acid solution, but its fluorescence was not able to reach initial intensity, which severely affected its application under high humidity environment. Therefore, the encapsulation of Cs2Na0.8Bi0.8Mn0.4Cl6 MCs using water stable and highly transparent SiO2 was proposed to obtain Cs2Na0.8Bi0.8Mn0.4Cl6@SiO2 core-shell MCs, its optical properties were unaffected after stored in aqueous solution for 10 days. The assembled light emitting diode devices kept constant illumination output in harsh environment of 85% relative humidity, which laid a solid foundation for the subsequent development of lead-free DP optoelectronic devices

Enhanced stability of lead-free double perovskite Cs2AgInxBi1-xCl6 crystals under a high humidity environment by surface capping treatment

Lead-free double perovskite (DP) crystals have received considerable attention for solving the toxicity and instability issues of traditional lead-based perovskites. However, recent studies have focused mainly on the improved optical performance of lead-free DP crystals, with less attention paid to their optical stability under high humidity environments. In this study, ligand-free lead-free DP Cs2AgIn0.93Bi0.07Cl6 nanocrystals (NCs) with excellent optical properties were prepared as research objects, and the larger surface area of the NCs caused them to be rapidly transformed into other phases after contact with water molecules, accompanied by a complete loss of optical properties, which significantly limited their application under high humidity environments. Therefore, surface capping treatment for Cs2AgIn0.93Bi0.07Cl6 NCs with an oleic acid (OA) ligand and polyvinylidene difluoride (PVDF) was proposed to achieve Cs2AgIn0.93Bi0.07Cl6 NCs-OA and Cs2AgIn0.93Bi0.07Cl6/PVDF composite films (CFs) with high water stability. In particular, the optically outstanding Cs2AgIn0.93Bi0.07Cl6/PVDF CFs exhibited stable fluorescence emission even after being stored in water solution for 10 days, and the assembled LED device operated well for a long time under 85% relative humidity (RH), which will bring a new dawn for the commercialization of next-generation lead-free DP optoelectronic devices

<p>Magnetic properties and giant cryogenic magnetocaloric effect in B-site ordered antiferromagnetic Gd2MgTiO6 double perovskite oxide</p>

The magnetic refrigeration (MR) technology by utilizing the magnetocaloric (MC) effects of magnetic solids have been realized to be a promising energy efficiency and environmentally friendly technology. Developing or discovering proper magnetic solids with promising MC performances is one of the most important tasks at present stage since a huge gap still exists between the requirement of practical MR application and the MC performances of the magnetic solids. Herein, we reported a combined theoretical and experimental investigation of the crystal structure together with the magnetic properties, magnetic phase transition (MPT) and MC performances in Gd2MgTiO6 oxide. The Gd2MgTiO6 is confirmed to crystalize in a B-site ordered monoclinic double perovskite (DP) crystal structure. A rather unstable anti ferromagnetic (AFM) interaction with large magnetic moment and semi-conductor characteristic with the band gap of 2.977 eV have been confirmed in Gd2MgTiO6 DP oxide at ground state. Giant reversible cryogenic MC effect together with excellent MC performances have been confirmed by a series of the figure of merits including the values of maximum magnetic entropy change (-delta S-M) and refrigerant capacity ( RC ), which are evaluated to be 46.21 J/kgK and 300.27 J/kg around 3.3 K with the magnetic change of 0-7 T, these values are much better than most of the recently reported famous cryogenic MC materials and the commercialized magnetic refrigerants gadolinium gallium garnet (GGG) as well. The observed excellent MC performances suggest that Gd2MgTiO6 DP oxide is a promising candidate material for cryogenic MR applications. (C)& nbsp;2022 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved

In Situ Fabrication of Lead-Free Double Perovskite/Polymer Composite Films for Optoelectronic Devices and Anticounterfeit Printing

Lead-free double perovskites (DP) have the potential to become a rising star in the next generation of lighting markets by addressing the toxicity and instability issues associated with traditional lead-based perovskites. However, high concentrations of hydrochloric acid (HCl) were often employed as a solvent in the preparation of most DPs, accompanied by slow crystallization at high temperatures, which not only raised the risk and cost in the preparation process, but also had a potential threat to the environment. Here, an in situ fabrication strategy was proposed to realize the crystallization of DP in the polymer at low temperature with a mild dimethyl sulfoxide (DMSO) solvent, and subsequently obtained optically well-behaved Cs2Na0.8Ag0.2BiCl6/ PMMA composite films (CFs) by doping with Ag+, generating bright orange luminescence with a photoluminescence quantum yield (PLQY) of up to 21.52%. Moreover, the growth dynamics of Cs2Na0.8Ag0.2BiCl6/PMMA CFs was further investigated by in situ optical transformation, which was extended to other DP-based polymer CFs. Finally, these CFs exhibited excellent performance in optoelectronic devices and anticounterfeit printing, the results of which provide a new pathway to advance the development of lead-free DP materials in the optical field

Preparation of CsPb(Cl/Br)3/TiO2:Eu3+ composites for white light emitting diodes

The inherent single narrow emission peak and fast anion exchange process of cesium lead halide perovskite CsPbX3 (X = Cl, Br, I) nanocrystals severely limited its application in white light-emitting diodes. Previous studies have shown that composite structures can passivate surface defects of NCs and improve the stability of perovskite materials, but complex post-treatment processes commonly lead to dissolution of NCs. In this study, CsPb(Cl/Br)3 NCs was in-situ grown in TiO2 hollow shells doped with Eu3+ ions by a modified thermal injection method to prepare CsPb(Cl/Br)3/TiO2:Eu3+ composites with direct excitation of white light without additional treatment. Among them, the well-crystalline TiO2 shells acted as both a substrate for the dopant, avoiding the direct doping of Eu3+ into the interior of NCs to affect the crystal structure of the perovskite materials, and also as a protection layer to isolate the contact between PL quenching molecules and NCs, which significantly improves the stability. Further, the WLED prepared using the composites had bright white light emission, luminous efficiency of 87.39 lm/W, and long-time operating stability, which provided new options for the development of perovskite devices

Ultrastable CsPbBr3@CsPb2Br5@TiO2 Composites for Photocatalytic and White Light-Emitting Diodes

Although cesium halide lead (CsPbX3, X = Cl, Br,I) perovskite quantum dots (QDs) have excellent photovoltaic properties, their unstable characteristics are major limitations to application. Previous research has demonstrated that the core−shell structure can significantly improve the stability of CsPbX3 QDs and form heterojunctions at interfaces, enabling multifunctionalization of perovskite materials. In this article, we propose a convenient method to construct core−shell-structured perovskite materials, in which CsPbBr3@CsPb2Br5 core−shell micrometer crystals can be prepared by controlling the ratio of Cs+/Pb2+ in the precursor and the reaction time. The materials exhibited enhanced optical properties and stability that provided for further postprocessing. Subsequently, CsPbBr3@CsPb2Br5@TiO2 composites were obtained by coating a layer of dense TiO2 nanoparticles on the surfaces of micrometer crystals through hydrolysis of titanium precursors. According to density functional theory (DFT) calculations and experimental results, the presence of surface TiO2 promoted delocalization of photogenerated electrons and holes, enabling the CsPbBr3@CsPb2Br5@TiO2 composites to exhibit excellent performance in the field of photocatalysis. In addition, due to passivation of surface defects by CsPb2Br5 and TiO2 shells, the luminous intensity of white light-emitting diodes prepared with the materials only decayed by 2%−3% at high temperatures (>100 °C) when working for 24 h

Arrays of Triangular Au Nanoparticles with Self-Cleaning Capacity for High-Sensitivity Surface-Enhanced Raman Scattering

In the realm of surface-enhanced Raman scattering (SERS) research, the precise detection and effective cleansing of substances are critical. This study introduces a novel Au nanotriangle/Cs2AgBiBr6 (Au NT/CABB) SERS array, synthesized through a meticulous two-step process, which demonstrates remarkable SERS effectiveness. Using Rhodamine 6G (R6G) as the probe molecule, this substrate accurately detects target molecules and achieves an exceptional detection threshold of 1 × 10–13 M. The integration of CABB into the substrate endows it with photocatalytic properties, thereby accelerating the degradation of adsorbed signaling molecules and significantly enhancing the reusability of the Au NT/CABB arrays. Furthermore, the arrays exhibit outstanding SERS and photocatalytic performance with methylene blue (MB) and MB&R6G mixed solutions, distinguishing between the two signal molecules with high fidelity. Additionally, the SERS enhancement mechanism of the Au NT/CABB array is analyzed by the finite-difference time-domain (FDTD) simulation and energy band structure. These findings highlight the substrate’s dual capability in leveraging both electromagnetic and chemical enhancement mechanisms for superior SERS performance, complemented by an integrated photocatalytic self-cleaning feature, making it a promising candidate for environmental detection applications