Coumarin oxime esters (COXEs) have received extensive attention for their outstanding photoinitiation performance, but their rational and efficient design is challenged by the vast combinatorial space of possible electron donor/acceptor substituents on the coumarin core. In this work, a two-dimensional quantitative structureactivity relationship (2D-QSAR) analysis of reported COXE structures was performed to examine the relationship between structural descriptors and photo-reactivity. It was revealed that the acceptor and donor of hydrogen bond (HA, DH), total energy (E), as well as energy gap (Eg) strongly influence the absorption wavelength (Amax). In particular, the phenyl ring with electron-withdrawing substituents enhances the charge asymmetry of the adjacent N-O bond and induces a red shift in the absorption wavelength. As a result, a novel COXE, namely C-5, was rationally designed and synthesized with a pentafluorophenyl substituent. The Amax of C-5 was predicted by DFT and confirmed by the UV-vis spectrum to be 424 nm in acetonitrile. Meanwhile, C-5 exhibits strong absorption (epsilon) of about 8.66 & times; 103 M- 1 cm-1 at 405 nm and shows rapid photobleaching under 405 nm irradiation. In addition, the GelNB system photocured by the C-5 photoinitiator enabled a polymerization conversion of about 25.8%, with an elastic modulus of 2878 MPa. This modulus is significantly higher than that of the samples cured by the LAP and Irgacure 2959. These results demonstrate that the 2D-QSAR-DFT collaborative design can identify and optimize novel COXE photoinitiators, thereby advancing the highly efficient, rational preparation of visible-light-active photoinitiators for visible-light photopolymerization.

In this study, the Sm doped BaCa2Y6O12 system, which exhibits high-quality orange-red luminescence and was anticipated to be utilized in white light-emitting diodes, has been prepared through the high-temperature solid phase method. The BaCa2Y6O12:Sm material exhibits two types of excitation: one at 304, 316, 344, 359, 375, 405, 425, 467 and 475 nm, resulting in the internal 4f-4f transition of the Sm ion; the other was the transition from the valence band to the conduction band of the BaCa2Y6O12 host, generated by 235 nm excitation. Irrespective of the 4f-4f transition of Sm ion or the interband transition of BaCa2Y6O12 host, the sample exhibited the capacity to produce strong emission at 564, 608, 654 and 713 nm, thereby yielding a bright orange-red visual effect. The measurement and analysis also demonstrated that the color purity of BaCa2Y6O12:Sm orange-red visible light emitted by 405 nm blue-violet light was more than 90 %, the average correlated color temperature was 1648 K, the highest quantum yield reached 100 %, and the fluorescence lifetime was 1.06 ms. Furthermore, the study demonstrated that the fluorescence emission intensity of BaCa2Y6O12:Sm at an temperature of 400 K was still more than 98 % of that at room temperature. The luminous performance parameters of BaCa2Y6O12:Sm indicate that it has broad application prospects in the field of white light emitting diodes. Finally, a comprehensive account has been furnished of the fluorescence emission mechanism and the thermal stability mechanism of BaCa2Y6O12:Sm.

In this work, we report on the recent research progress on watt-level all-solid-state single-frequency Pr:LiYF4 (YLF) lasers in the orange spectral region. Combining dual-end pumping and ring-cavity technologies, we have achieved a maximum singlefrequency output of 1.19 W at 607 nm with a linewidth of about 20.3 MHz. Based on this study, by inserting a 0.15 mm etalon inside the ring cavity, we find that the 607 nm lasing can be completely suppressed and a single-frequency laser at 604 nm with a 0.69 W output power and a linewidth of about 16.7 MHz can also be obtained. Moreover, the wavelengths of the two single-frequency lasers can be tuned from 607.16 to 607.61 nm and from 603.99 to 605.02 nm, respectively. Furthermore, the single-frequency Pr:YLF laser can also operate in a state of the two orange wavelengths, simultaneously, with a maximum output power of 0.97 W. We believe that this is the highest output power of a direct generation of single-frequency orange lasers and the first demonstration of the wavelength-tuned operation of the achieved single-frequency orange lasers, which could bring opportunities for the application of single-frequency orange lasers.

In this work, Mg2SnO4:Er3+ luminescent materials with anti spinel structure are prepared by high-temperature solid phase method, which display both photoluminescence properties, room-temperature long afterglow luminescence properties and thermoluminescence enhancement properties. Under excitation of 378 nm near the visible band, the sample exhibits a strong monochromatic green fluorescence emission at 533 nm, and the color purity is as high as 86.08 % compared to that of the standard green light; after excitation of 250 nm, the sample shows clear light blue-green afterglow with the lifetime of more than 2000 s at room temperature; after the afterglow stops under the condition of room temperature, the sample is heated to 405 K, the emission enhancement phenomenon occurs again. All the luminescence properties of Mg2SnO4:Er3+ depend on its special energy level structure. The doped system contains two types of emission centers, Er3+ and lattice defects; at the same time, the system also contains two types of electron traps, one is the very unusual conduction band (CB), and the other is the common lattice defects, which ensures the afterglow emission at room temperature and enhanced thermal induced emission at high temperature. Finally, the mechanism of fluorescence emission, afterglow emission and thermal induced emission based on the electron transition and transport behavior is also elaborated in this work.

Alumina is a widely used advanced ceramic material whose properties depend on the particle size, porosity and purity of the ceramic. Powder with high quality is the key to get high performance alumina. Among those powder synthesis methods, the sol-gel method is considered to be a good route to get high quality powders. However, the existing sol-gel methods for preparing alumina still have some disadvantages, such as complicated process and high production cost of the raw material (aluminum alkoxide). With the assistance of density functional theory, we aim to explain the reaction mechanism of alumina powder synthesis by an improved sol-gel routine. This is expected to solve the above-mentioned disadvantages. In this study, the hydrolysis-polymerization mechanism of tris(dimethylamino)aluminum (Al(NMe2)3) monomer and dimer were investigated at the level of B3LYP-D3BJ/6-311G(d,p) using Gaussian16 software. It provides a theoretical guidance for experimental studies on the synthesis of alumina powders. The results show that the hydrolysis reaction of Al(NMe2)3 monomer is completed in three steps, all of which are spontaneous and can occur rapidly. The calculated polymerization reaction is also spontaneous, but the depolymerization reaction can hardly occur due to the high energy barrier. The hydrolysis of the dimer is finished in six steps, all of which are spontaneous, including the calculated polymerization reaction. Our studies show that the hydrolysis-polymerization reaction of Al(NMe2)3 dimer is theoretically feasible and can be used to prepare alumina. In addition, alumina powder was synthesized using above method, verified the feasibility of it.

Azobenzene-based polymers have been prominent photochromic materials (PCMs) for decades but still suffer from low efficiency and instability in photallochromy due to hindered isomerization in the solid state. Here, a controlled charge interaction between additive SnO2 nanoparticles and azophenyl polyether was designed and established using density functional theory (DFT) prediction and experimental verification, aiming to disrupt π-π stacking among azobenzene moieties. Theoretical calculations, time-resolved fluorescence spectra, and zeta potential tests have proven that negative charges generated on the surface of SnO2 nanoparticles under UV-A (330-370 nm) irradiation transfer to positively charged carboxyl groups of azobenzene moieties, accelerating the isomerization speed (response time ≤ 10 s) and stabilizing the cis conformation of azobenzene. Compared to the pristine azophenyl polyether films, the azophenyl polyether/SnO2 composite film exhibits a more rapid and pronounced color-change behavior under both 450 nm blue light and 365 nm UV irradiation, enabling a stable and durable pattern writing/erasing functionality triggered by 450/365 nm light. Interestingly, owing to a 13.53% difference in reflectance at 410 nm between cis and trans isomers, the imprinted patterns on the composite films are nearly invisible under ambient light yet show a high contrast ratio (CR) of up to 2.4 under 405 nm violet light, demonstrating promising potential applications in anticounterfeiting and information encryption.

Crystal fiber is highly valued in high-power laser research due to its excellent thermo-optic property. In this paper, we report on the result of studying high-energy nanosecond pulse laser at 1064 nm using Nd:YAG single crystal fiber as gain medium based on electro-optic Q-switching. With a 808-nm continuous wave diode laser as pump source, we obtained an average output power of 6.06 W at a repetition rate of 500 Hz with a pulse width of 29 ns, corresponding to a pulse energy of 12.12 mJ, and a peak pulse power of 0.42 MW. To our knowledge, this is actually the first research combining electro-optic Q-switching technology and end-pumped crystal fiber laser technology, and the results have indicated that crystal fiber has advantages in improving laser performance for directly obtaining high pulse energy and peak power with less system complexity and cost.

The impact of the self-sealing band on interior ballistics is investigated during the gun launching, and a high-precision interior ballistics coupling algorithm that takes leakage into account is proposed. This study focuses on a 65 mm short-barrel, equal-caliber balanced cannon, integrating Abaqus finite element software with an interior ballistics calculation programme. It uses a User-defined AMPlication Load (VUAMP) subroutine to achieve real-time coupling calculations of the chamber pressure and self-sealing band deformation, correcting variations in the chamber pressure. Experimental results show that the coupling algorithm offers the higher precision compared to traditional interior ballistics models and can effectively capture the impact of leakage on the interior ballistics performance. Further research reveals that changes in the charge amount and assembly gap significantly affect the sealing performance of the self-sealing band and the leakage of propellant gases, which in turn influence the chamber pressure and projectile velocity. The high-precision coupling algorithm proposed in this paper provides the effective theoretical support for the design of the self-sealing band and the analysis of cannon performance.

Revealing the nature of enhanced electro-assisted uranium extraction activity by hetero-interface and M-O-H coordination bonds is an important and challenging task. Hence, Co3O4@FeOx nanosheet arrays with abundant M-O-H coordination bonds is fabricated as a binder-free and self-supporting electrocatalyst for electro-assisted uranium extraction from fluorine-containing uranium wastewater. As revealed by self-consistent energy band calculations and in-situ Kelvin Probe Force Microscopy (KPFM) analysis, the p-n heterojunction formed by Co3O4@FeOx provides a well-designed built-in electric field (BIEF), triggering the interfacial accumulation of uranium and accelerating the electro reduction kinetics of uranium. Consequently, Co3O4@FeOx shows remarkable U(VI) extraction ability (>95 %) in fluorine-containing uranium wastewater. By virtue of the XAFS spectra, free uranyl ions are captured by M-O-H on Co3O4@FeOx to form a sturdy 2 O-ax-1 U-3 O-eq configuration, confirming the electrically driven separation of uranium and fluorine. Furthermore, DFT calculation indicates that the existent of M-O-H enhances the adsorption energy of uranium species, thus promoting uranium extraction efficiency.

In recent years, aluminum nitride has undergone significant advancements and has found extensive application in optoelectronic and microelectronic devices due to its remarkable physicochemical properties. The quality of aluminum nitride powder plays a critical role in determining device performance, thus making the synthesis of high-quality powder a prominent area of research. The sol–gel method is a widely used approach for producing superior powders. In this study, we investigated the ammonolysis-polymerization mechanism of tris(dimethylamino)aluminum monomer and dimer using Gaussian16 software at the B3LYP-D3BJ/6-311G(d,p) level. Our objective was to provide theoretical guidance for the experimental synthesis of aluminum nitride powders using the sol–gel method. Our findings demonstrate that the ammonolysis reaction of tris(dimethylamino)aluminum dimer proceeds through six spontaneous steps. The two calculated polymerization steps also exhibit spontaneous behavior. All reactions demonstrate rapid occurrence, suggesting the theoretical feasibility of the ammonolysis-polymerization reaction of tris(dimethylamino)-aluminum dimer for synthesizing aluminum nitride.

Modifying photocatalysts for effective NO removal has profound implications for environmental protection. In this work, a novel g-C3N4 containing non-intrinsic oxygen vacancies (VO-CN) is synthesized via a facile oxygen pre-doping followed by elimination. Compared to pristine g-C3N4, VO-CN exhibits remarkably enhanced visible-light photocatalytic activity, increasing NO removal by 54.3%, with high NO3- selectivity. This photocatalytic enhancement is attributed to the non-intrinsic oxygen vacancies introduced in Vo-CN. As comprehensively revealed by experimental characterizations coupled with density functional theory (DFT) calculations. The results show that the midgap state generated in the VO-CN electronic band structure accelerates photogenerated electron-hole separation. Additionally, the unique surface structure of VO-CN provides favorable channels for carrier migration while enhancing O2 and NO adsorption. Consequently, the markedly improved generation of reactive oxygen species by Vo-CN promotes highly efficient NO removal. This work provides novel insights into designing high-performance g-C3N4-based photocatalysts for eliminating hazardous NO pollutants.

Within the realm of advancing photocatalysis, the investigation of material defects has perennially commanded paramount attention. However, a nuanced comprehension of the intricate interplay between these defects and the catalytic milieu necessitates deeper exploration. In the present study, oxygen vacancies (Vo) were adeptly harnessed to induce precise carrier localization, thereby effectuating a heightened augmentation of photocatalytic activity. This augmentation was deftly achieved through the deliberate modulation of external illumination parameters, resulting in the extension of carrier lifetimes. Specifically, the drastically enhanced carrier effective mass (m*) and the density of unoccupied state are directly uncovered by the density functional theory (DFT) calculation and Raman spectra. Through the utilization of wavelength dispersive in-situ fluorescence spectroscopy (WDIFS) experiments, it was observed that Vo-rich ZnO nanoparticles (NPs) displayed noteworthy photocatalytic activity around the central frequency of Vo (5.17 x 1014 Hz, 580 nm), owing to the highly efficient utilization of localized carriers. Moreover, based on Einstein rate equations, the charge carrier lifetime was found to be further prolonged with increased external illumination intensity and excitation wavelength. This work provides a methodology for optimizing the functionality of point defect on photocatalysis, where the photoinduced charge carrier localization is expected to be extensively used in further photocatalysis research.

Demographic data and clinical data were collected retrospectively from patients with pertussis at the Children's Hospital Affiliated to the Capital Institute of Pediatrics between March 2011 and February 2023. Among the 270 hospitalized patients, 151 cases were male and 119 were female. The youngest age of admission was 10 days and the eldest age of admission was 11 years. The 270 hospitalized patients were divided into two groups according to onset age: <3 months (n=143) and≥3 months (n=127). For those in the <3-month-old group, the incidence of severe pneumonia and severe pertussis were 21.0% and 38.5%, respectively, both were significantly higher than those in≥3-month-old group (7.9% and 11.0%, both P<0.05). For those in the <3-month-old group, paroxysmal spasmodic cough, post-tussive vomiting, paroxysmal cyanosis, apnea, and decreased heart rate after coughing were 86.7%, 25.2%, 38.5%, 7.0% and 16.8%, respectively, all were significantly higher than those in ≥3-month-old group (76.4%, 10.2%, 15.7%, 1.6% and 1.6%, all P<0.05). For those in the<3-month-old group, the incidence of hypoxemia, respiratory failure, were 36.4%, 16.8%, respectively, and both were significantly higher than those in≥3-month-old group (10.2%, 7.1%, P<0.05). It indicated that among the infants under 3 months, the incidence of vomiting after coughing, paroxysmal cyanosis, apnea, hypoxemia, respiratory failure, decreased heart rate after coughing and severe pneumonia were significantly higher than those above 3 months. Infants under 3 months were prone to severe pertussis.

Perovskite/silicon tandem solar cells (TSCs) have aroused much attentions in recent years. One of keys for achieving highly efficient and stable TSCs is to guarantee effective charge transfer, especially on the rough textured silicon substrate due to the poor adhesion between interlayers. Here, a 2-fluoroisonicotinic acid (2-FNA) additive that possesses fluorine (-F), carboxylic acid (-COOH), and pyridine nitrogen as functional groups in the perovskite precursor to assist the crystallization process is utilized. It shows that 2-FNA can efficiently reduce the defects and suppress non-radiative recombination of perovskite layers by bonding with the uncoordinated Pb2+ ions, formamidinium (FA+), and halide vacancies, leading to notably prolonged carrier lifetime. Most importantly, this found that 2-FNA aids in the formation of better interfacial contact between the perovskite and C60 layer on top, thus enhancing the interfacial electron extraction therein, eventually leading to an increased power conversion efficiency (PCE) of 28.61% on champion perovskite/silicon TSCs from 27.08% on control counterparts. This work provides a practical route to further advance the PV performance and applicability of perovskite/silicon TSCs. For achieving highly efficient and stable perovskite/silicon tandem solar cells on the fully-textured silicon substrate, triple-functional 2-fluoroisonicotinic acid (2-FNA) is used as passivator in the perovskite. 2-FNA can efficiently suppress non-radiative recombination and aid in the formation of better interfacial contact between perovskite and C60 layers, eventually leading to a top power conversion efficiency of 28.6%.image

A post-functionalized photosensitive polyether material prepared by ring-opening polymerization(ROP),as well as side group modification that conducted by"click chemistry"is reported in this work.Allyl glycidyl ether(AGE)was used as the precursor to prepare poly(allyl glycidyl ether)(PAGE)by anionic ring-opening polymerization under the catalysis of cesium pivalate.Then the photosensitive moieties of cinnamoyl chloride were introduced onto side chains of PAGE prepolymer by two-step reactions of thiol-ene"click chemistry"and esterification,aiming to prepare polyether with photosensitive properties.The main chain length of PAGE prepolymer and the grafting rate of cinnamoyl chloride side groups can be flexibly controlled by adjusting the monomer/initiator ratio and grafting reaction time,respectively.After casted and photocured,the photosensitive PAGE film possesses a low glass transition temperature(Tg),and exhibits rapid and reversible deformation characteristic undergoing a reversible[2+2]cycloaddition reaction triggered by ultraviolet light with a wavelength of 365 and 254 nm.From the aspect of designing and optimizing the polyether main chain/side branches structure via ring-opening polymerization and"click chemistry"reaction design,the results provide practical ideas for broadening the service temperature window of photo-functional polyether,and improving its photo-induced deformation sensitivity.The obtained polyether materials also show some potential applications in the fields of controlled drug release and flexible intelligent robots.

Single-frequency (SF) lasers in the visible spectral region are usually obtained through an indirect method, i.e., frequency doubling of near-infrared SF lasers. In this work, we report on the direct generation of a high-power continuous-wave (CW) SF laser in red based on a diode-pumped Pr:LiYF4 (YLF) ring cavity technology. A maximum output power is scaled to 3.98 W at 640 nm with a linewidth of about 17.2 MHz and a power stability of 0.6%. Moreover, by inserting a LBO crystal into the ring cavity for intracavity frequency doubling of the 640 nm SF laser, we have also successfully demonstrated an ultraviolet (UV) SF laser at 320 nm, for the first time to the best of our knowledge, with a maximum power of 670 mW. This work provides a promising route for the development of simple, compact, and high-power SF lasers operating in visible and UV spectral regions.

The assistance of alloying elements provides enormous opportunities for the discovery of highperformance face-centered cubic (FCC) medium-entropy alloys (MEAs). In this work, the influence of alloying element Mo on the phase stability, stacking fault energy (SFE), deformation mechanisms, lattice distortion, and mechanical properties of (CoCrNi)(100-x )Mox (0 <= x <= 10) MEAs was synthetically explored with the first-principles calculations. It indicates that the FCC phase remains metastable at 0 K, and its stability degenerates with increasing Mo content. The monotonous decrease of SFE is revealed with the rise of Mo content, which promotes the activation of stacking faults, deformation twinning, or martensitic transformation. Raising Mo content also causes the aggravation of lattice distortion and thus triggers intense solid solution strengthening. Significantly, the essential criterion for the composition design of FCC (CoCrNi)100-x Mo MEAs with superior strength-ductility combination was established based on the synergistic effects between multiple deformation mechanisms and solid solution strengthening. According to the criterion, the optimal composition is predetermined as (CoCrNi)(93) Mo-7 MEA. The criterion is proved to be effective, and it can provide valuable inspiration for the development of alloying-element reinforced FCC multi-principal element alloys. (c) 2024 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

The integration of perovskites with silicon for constructing tandem solar cells (TSCs) signifies a promising route in photovoltaic technology. To optimize the compatibility with silicon bottom cells, the perovskite absorbing layer necessitates an appropriate band gap of 1.68 eV. However, fabricating a wide-band-gap perovskite layer with conformal deposition on textured silicon bottom cells presents a significant challenge. Here, we investigate three different common bromide sources (formamidinium bromide (FABr), methylammonium bromide (MABr), and lead bromide (PbBr2)) to manipulate the band gaps of the resultant perovskite films, as fabricated by the vapor-solution hybrid method. Results show that incorporation of FABr facilitates the crystallization of wide-band-gap perovskite films with larger grain sizes and reduced PbI2 residues in comparison with MABr- and PbBr2-based counterparts. The perovskite film fabricated with the FABr source also exhibits the best energy-level alignment and the lowest defect density among the three precursor types, thus promoting an effective carrier transport and extraction at the device interfaces. As a result, the top power conversion efficiency of the target perovskite/silicon TSCs reaches 28.69% with an open-circuit voltage of 1.85 V and a fill factor of 79.13%. Our work reveals the fundamental differences in applying different Br- sources and offers a practical guideline for achieving highly efficient perovskite/silicon TSCs

The electro-driven extraction of uranium from fluorine-containing uranium wastewater is anticipated to address the challenge of separating fluoro-uranium complexes in conventional technologies. Herein, we developed hydroxy-rich cobalt-based oxides (CoOx) for electro-assisted uranium extraction from fluorine-containing wastewater. Relying on theoretical calculations and other spectral measurements, the hydroxy-rich CoOx nanosheets can enhance the affinity for uranium due to the existence of a substantial quantity of hydroxyl groups. Accordingly, the CoOx nanosheets exhibit outstanding U(VI) removal efficiency in the presence of fluorine ions. Through the utilization of X-ray absorption fine structure (XAFS), we confirm that hydroxy-rich CoOx nanosheets capture free uranyl ions to form a sturdy 2Oax-1U-3Oeq configuration, which can be achieved through electro-driven fluorine-uranium separation. Notably, for the first time, the whole reaction process of uranium species on the CoOx surface from the initial uranium single atom growth to uranium oxide nanosheets is monitored by aberration-corrected transmission electron microscopes (AC-TEM). This work provides a paradigm for the advancement of novel functional materials as electrocatalysts for uranium extraction, as well as a new approach for studying the evolution mechanism of uranium species.