Optical Upconversion in Mononuclear Lanthanide Co-Crystal Assemblies.

In this work, we developed two kinds of co-crystal assemblies systems, consisting of discrete mononuclear Yb3+ and Er3+ and mononuclear Yb3+ and Pr3+, which can achieve Er3+ and Pr3+ upconversion luminescence, respectively, by Yb3+ sensitization under 980 nm excitation. The structure and composition of two co-crystal assemblies were determined by single crystal X-ray diffraction. By investigation of the series of two assemblies, respectively, it is found that the strongest upconversion luminescence is both obtained when the molar ratio of Yb3+ and Ln3+ (Ln=Er or Pr) is 1 : 1. The energy transfer mechanism of Er3+ assemblies is determined as energy transfer upconversion, while that of Pr3+ assemblies is determined as energy transfer upconversion and cooperative sensitization upconversion. This is the first example of Pr3+ upconversion luminescence at the molecular dimension at room temperature, which enriches the research in the field of upconversion luminescence with lanthanide complexes.

Ultrahigh-Q Polarization-Independent Terahertz Metamaterial Absorber Using Pattern-Free Graphene for Sensing Applications.

In contrast to noble metals, graphene exhibits significantly lower loss, especially useful for optical sensing applications that require ultrahigh Q factors, and offer wide range tunability via an adjustable Fermi level. However, precise graphene patterning is difficult, especially for large areas, severely limiting its applications. Here, a tunable terahertz metamaterial absorber (TMMA) with ultrahigh Q factors consisting of a continuous, pattern-free graphene is demonstrated. A graphene sheet is overlaid on an Al metal array, forming a structure that supports strong localized surface plasmon polaritons (LSPPs) with fields tightly confined in the graphene, minimizing loss. Theoretical results show that this TMMA exhibits an ultrahigh Q factor of 1730, a frequency sensitivity of 2.84 THz/RIU, and an excellent figure of merit (FoM) of 365.85 RIU-1, independent of polarization. A tunability from ~2.25 to ~3.25 THz is also achieved by tuning Ef of graphene from 0.3 to 0.7 eV. The proposed graphene-based TMMA holds many potential applications, particularly in the field of sensing.

Concave Version Printing of High-Performance Polymer THz Filters.

The development of high Q and tunable narrowband filters that can efficiently manipulate THz beams is critical for various THz applications, such as imaging and sensing. However, for filters made of metals and dielectrics, issues such as high losses, limited tunability, and lengthy process flows exist. Here, a scalable concave version reprinting technique to mass produce high-performance microstructured polymer filters is presented. The technique is extremely simple, eliminating the demand for the use of any large equipment including injection molding and thermal press printing machines, and is reliable; in the reprinted structures, there are no defects including gaps and air bubbles. The produced narrowband filters exhibit a high Q factor of 57 with wide tunability over the THz band from ∼80 to 160 µm in wavelength. The presented technique can be adopted to realize other devices as well using polymer materials with simplicity and high precision.

Effect of biochar with various pore characteristics on heavy metal passivation and microbiota development during pig manure composting.

Understanding the porosity of biochar (BC) that promotes the heavy metal (HM) passivation during composting can contribute to the sustainable management of pig manure (PM). The current work aimed to explore the influence of BC with varying pore sizes on the physicochemical properties and morphological changes of HMs (including Zn, Cu, Cr, As, and Hg), and microbiota development during PM composting. The various pore sizes of BC were generated by pyrolyzing pine wood at 400 (T1), 500 (T2), 600 (T3) and 700 (T4) °C, respectively. The results revealed a positive correlation between specific surface area of BC and pyrolysis temperature. BC addition contributed to a significantly extended compost warming rate and duration of high-temperature period, as well as HM passivation, reflected in the decrease in Exc-Zn (63-34%) and Red-Cu (28-13%) content, and the conversion of Oxi-Cr (29-21%) and Red-Hg (16-5%) to more stable forms. Moreover, BC at T4 exhibited the best effect on Zn and Cu passivation due to the highest specific surface area (380.03 m2/g). In addition to its impact on HM passivation, BC addition improved the microbial environment during PM composting, leading to enhanced microbial diversity and richness. Notably, Chloroflexi and Bacteroidota played key roles in promoting the transformation of Exc-Cu and Red-Hg into stable forms. This phenomenon further stimulated the enhanced decomposition of organic matter (OM) when BC prepared at 600-700 °C was added. Therefore, it can be concluded that the regulation of BC porosity is an effective strategy to improve HM passivation and the overall effectiveness of PM composting.

Er3+-Sensitized Upconversion/Down-Shifting Luminescence in Metal-Organic Frameworks.

Photoluminescent metal-organic frameworks (MOFs) are used as optical materials with excellent properties, of which the lanthanide-doped MOFs are able to emit in a broad region from visible to near-infrared due to their unique 4f-orbital electronic structure. Herein, Er3+ and Y3+ ions are selected as the metal centers of the MOFs and Er3+ is used as a sensitizer to absorb 980 nm excitation light. At the same time, Er3+ ions also act as activators that emit upconverting visible light and down-shifting near-infrared light. In addition, Tm3+, Ho3+, and Eu3+ ions were individually doped into the Er3+-doped MOFs to investigate the variation of energy-transfer paths in the presence of different lanthanide activators. Finally, the pathway of energy transfer in these Er3+-sensitized luminescent-MOFs was summarized. This work provides new insights for further development of both upconversion and down-shifting luminescence of MOFs.

Polarization- and angle-insensitive broadband long wavelength infrared absorber based on coplanar four-sized resonators.

In many potential applications, there is a high demand for long wavelength infrared (LWIR) absorbers characterized by a compact configuration, broad operational bandwidth, high absorption efficiency, and polarization- and angle-insensitive characteristics. In this study, we design and demonstrate a high-performance broadband LWIR absorber based on coplanar four-sized resonators, consisting of arrays of titanium (Ti) disks with different diameters supported by a continuous zinc selenide (ZnSe) layer and by a Ti film acting as a back-reflector. Particle swarm optimization (PSO) is employed to optimize the complicated geometry parameters, and the final optimized device exhibits near-unity absorption (∼96.7%) across the entire operational bandwidth (8 µm∼14 µm) under unpolarized normal incidence, benefiting from the impedance-matching condition and the multiple surface plasmon resonances of this configuration. Furthermore, the proposed absorber is insensitive to the angle of incidence due to the localized surface plasmon resonances supported by these four-sized resonators, and is insensitive to the state of polarization thanks to the highly symmetric feature of the circular pattern. The measured absorption of the fabricated sample exhibits a relatively high coincidence with the simulation, with an average absorption of 88.9% ranging from 8 µm to 14 µm. The proposed absorber, which can be easily integrated into a standardized micro/nano manufacture process for cost-effective large-scale production, provides a feasible solution for improving optical performance in thermal emitter, infrared detection, and imaging applications. Furthermore, the generalized design principle employing the optimized method opens up new avenues for realizing target absorption, reflection, and transmission based on more complicated structure configurations.

THz transmissive all-dielectric guided-mode resonance filter with high Q and tunability using suspended gratings.

Most currently available THz narrowband filters employ metal that introduces loss, or work in reflection mode, which limits their scope of application. Here, a transmissive all-dielectric guided-mode resonance filter in the THz region is presented. It contains a suspended grating layer and a waveguide layer, separated by an air layer. A fabrication process of the filter is proposed. Simulation results show that the designed filter exhibits excellent transmittance of ∼97.5% with a high Q value of ∼1500 at 1.64 THz. Furthermore, this transmission peak is surrounded by a wide and flat sideband with width of ∼0.75T H z and transmission below 10%. Moreover, tunability of the filter is realized by geometric scaling and by varying the thickness of the air layer. Using geometric scaling, the filtering frequency can be widely tuned from 0.54 to 1.64 THz, covering the 625-725 and 780-910 GHz wireless communication windows. Additionally, fine tuning achieved by varying the air layer thickness could be used to compensate for a tiny shift of the designed filtering frequency caused by errors introduced in the fabrication process. The Q value can be further boosted to ∼11,500 by adding another layer of waveguide. Due to its transmissive nature and high-Q resonant mode with a wide sideband and tunability, the presented filter exhibits great potential in THz applications such as spectroscopy, imaging, and communication.

Upconversion Luminescence in Mononuclear Yb/Sm Co-crystal Assemblies at Room Temperature.

Metal-based upconversion luminescence transforming high-energy photons into low-energy photons is an attractive anti-Stokes shift process for fundamental research and promising applications. In this work, we developed the upconversion luminescence in co-crystal assemblies consisting of discrete mononuclear Yb and Sm complexes. The characteristic visible emissions of Sm3+ were observed under the excitation of absorption band of Yb3+ at 980 nm. A series of co-crystal assemblies were investigated based on mononuclear Yb and Sm complexes, and the strongest luminescence was obtained when the molar concentration between Yb3+ and Sm3+ is equivalent. The crystal structure was fully characterized by the single crystal X-ray diffraction and upconverting energy transfer mechanisms were verified as cooperative sensitization upconversion and energy transfer upconversion. This is the first example of Sm3+ -based upconverting luminescence in discrete lanthanide complexes which present as co-crystal assemblies at room temperature.

Research on the Differences in Phenotypic Traits and Nutritional Composition of Acer Truncatum Bunge Seeds from Various Regions.

Acer truncatum Bunge (ATB) is an excellent edible woody oil tree species since it bears a huge amount of fruit and has strong adaptability to be widely cultivated. Selecting an optimal cultivation region for ATB is crucial to improving China's woody oil industrialization. Chemical analysis, correlation analysis, and affiliation function values were used in the present research to systematically analyze the phenotypic traits, organic compound content, and seed oil chemical composition of the seeds of ATB from nine regions. The average contents of oil, protein, and soluble sugar in ATB seeds were 43.30%, 17.40%, and 4.57%, respectively. Thirteen fatty acids were identified from ATB seed oil, the highest content of which was linoleic acid (37.95%) and nervonic acid content was 5-7%. The maximum content of unsaturated fatty acids in ATB seed oil was 90.09%. Alpha-tocopherol content was up to 80.75 mg/100 g. The degree of variation in seed quality traits (25.96%) was stronger than in morphological traits (14.55%). Compared to environmental factors, the phenotypic traits of seeds contribute more to organic compounds and fatty acids. Combining the values of the indicator affiliation functions, Gilgarang, Tongliao, Inner Mongolia was selected as the optimal source of ATB for fruit applications from nine regions.

Fluorescent deactivation behaviors based on ESIPT and TICT of novel double target fluorescent probe and its sensing mechanism for Al3+/Mg2+: A TD-DFT study.

Based on density functional theory (DFT) and time-dependent DFT (TD-DFT) methods with integral equation formula polarized continuum model (IEFPCM), the fluorescent behavior and recognizing mechanism of probe N'-((1-hydroxynaphthalen-2-yl)methylene)isoquinoline-3-carbohydrazide (NHMI) for Al3+/Mg2+ ion were investigated in more detail. Excited state intramolecular proton transfer (ESIPT) process in probe NHMI occurs in the stepwise pattern. The proton H5 of enol structure (E1) firstly moves from O4 to N6 to form single proton-transfer (SPT2) structure, and then the proton H2 of SPT2 transfers from N1 to N3 to form the stable double proton-transfer (DPT) structure. Subsequently, the transformation from DPT to its isomer (DPT1) induces the twisted intramolecular charge transfer (TICT) process. Two non-emissive TICT states (TICT1 and TICT2) were obtained, and TICT2 state quenches the fluorescence observed in the experiment. With the addition of aluminum (Al3+) or magnesium (Mg2+) ion, TICT process is prohibited by the coordination interaction between NHMI and Al3+/Mg2+, and the strong fluorescent signal is turned on. For probe NHMI, the twisted C-N single bond of acylhydrazone part leads to the TICT state. This sensing mechanism may inspire researchers to develop new probes from a different direction.

Cooperative Sensitization Upconversion in Solution Dispersions of Co-Crystal Assemblies of Mononuclear Yb3+ and Eu3+ Complexes.

Lanthanide upconversion luminescence in nanoparticles has prompted continuous breakthroughs in information storage, temperature sensing, and biomedical applications, among others. Achieving upconversion luminescence at the molecular scale is still a critical challenge in modern chemistry. In this work, we explored the upconversion luminescence of solution dispersions of co-crystals composed of discrete mononuclear Yb(DBM)3 Bpy and Eu(DBM)3 Bpy complexes (DBM: dibenzoylmethane, Bpy: 2,2'-bipyridine). The 613 nm emission of Eu3+ was observed under excitation of Yb3+ at 980 nm. From the series of molecular assemblies studied, the most intense luminescence was obtained for a 1 : 1 molar ratio of Yb3+ : Eu3+ , resulting in a high quantum yield of 0.67 % at 2.1 W cm-2 . The structure and energy transfer mechanism of the assemblies were fully characterized. This is the first example of an Eu3+ -based upconverting system composed of two discrete mononuclear lanthanide complexes present as co-crystals in non-deuterated solution.

Computational Insights into Sensing Mechanism for Al3+ in a New Acylhydrazone Fluorescent Probe Based on Excited-State Intramolecular Proton Transfer (ESIPT) and Twisted Intramolecular Charge Transfer (TICT).

The work explored the fluorescent properties of probe N'-(2, 4-dihydroxy-benzylidene)pyridine-3-carbohydrazide (HL) and its sensing mechanism for the Al3+ ion in detail. HL has two competing deactivation processes: ESIPT and TICT. Upon light-excitation, only one proton can transfer, and the SPT1 structure is generated. The SPT1 form is highly emissive, which is inconsistent with the colorless emission observed in the experiment. Then a nonemissive TICT state was obtained by rotating the C-N single bond. The energy barrier of the TICT process is lower than that of the ESIPT process, which indicates that probe HL will decay to the TICT state and quench the fluorescence. When Al3+ is recognized by probe HL, strong coordinate bonds are formed between HL and Al3+, and then the TICT state is prohibited, and the fluorescence of HL is turned on. Al3+ as a coordinated ion can effectively remove the TICT state but cannot influence the photoinduced electron transfer (PET) process of HL.

Upconversion Luminescence through Cooperative and Energy-Transfer Mechanisms in Yb3+ -Metal-Organic Frameworks.

Lanthanide-doped metal-organic frameworks (Ln-MOFs) have versatile luminescence properties, however it is challenging to achieve lanthanide-based upconversion luminescence in these materials. Here, 1,3,5-benzenetricarboxylic acid (BTC) and trivalent Yb3+ ions were used to generate crystalline Yb-BTC MOF 1D-microrods with upconversion luminescence under near infrared excitation via cooperative luminescence. Subsequently, the Yb-BTC MOFs were doped with a variety of different lanthanides to evaluate the potential for Yb3+ -based upconversion and energy transfer. Yb-BTC MOFs doped with Er3+ , Ho3+ , Tb3+ , and Eu3+ ions exhibit both the cooperative luminescence from Yb3+ and the characteristic emission bands of these ions under 980 nm irradiation. In contrast, only the 497 nm upconversion emission band from Yb3+ is observed in the MOFs doped with Tm3+ , Pr3+ , Sm3+ , and Dy3+ . The effects of different dopants on the efficiency of cooperative luminescence were established and will provide guidance for the exploitation of Ln-MOFs exhibiting upconversion.

A visualized and scientometric analysis of research trends of weight loss in overweight/obese children and adolescents (1958-2021).

Background: Weight loss is an appropriate approach to reduce the health risks associated with overweight/obese children and adolescents, and the optimal method of weight loss requires further research. This study systematically explores scientific co-operation, disciplinary interaction, hotspots and trends in the field of weight loss in overweight/obese children and adolescents (WLOCA), and provides references for further research. Methods: Citespace 5.8.R1 (64-bit) was adopted to conduct a comprehensive visualization analysis of the literature on WLOCA from Web of Science Core Collection, including publication, institution, country/region, author, journal, keywords and reference. Results: 2,513 papers were found in the Web of Science Core Collection, and the annual number of papers published has increased significantly since 2003. Cincinnati Children's Hospital is the institution with the largest number of publications, while Washington University plays a pivotal role in the collaboration network. In terms of nations, USA has made greater contributions than the rest in terms of the number of publications and global co-operation research. The most influential authors in this field are Thomas H. Inge, Thomas Reinehr, Todd M. Jenkins, Epstein LH, Ogden CL, etc. The most active journals are "Obesity," "International Journal of Obesity," "Obesity Surgery," "Pediatrics," etc. which are characterized by interdisciplinary interactions. Research hot topics mainly include "assessment of obesity and pathophysiological mechanism," "comprehensive intervention," and "bariatric surgery," and there's a gradual shift from "lifestyle intervention" and "pathophysiological mechanism" to "clinical surgical application." In addition, disciplinary integration and comprehensive research, targeted intervention and treatment, and prospective research are the future research trends. Conclusion: The overall trend in WLOCA study is positive. The main contribution of this study is to reveal the overall picture of the research in this field with visual maps and detailed data by combining quantitative with qualitative approaches, which can provide valuable references for relevant researchers to quickly understand the status of studies on WLOCA, to seek co-operation, and grasp research hotspots and frontier trends.

Aerobic exercises and cognitive function in post-stroke patients: A systematic review with meta-analysis.

OBJECTIVE: To study the effect of aerobic exercise on cognitive function of post-stroke patients, especially to identify specific interventions that the most likely to maximize cognitive benefits of stroke patients. METHODS: According to the PRISMA principle, the databases of Web of Science, EMBASE, PubMed and Cochrane library were searched to collect randomized controlled trial data of aerobic exercise on cognitive function intervention of post-stroke patients. The Cochrane bias risk evaluation instrument was used to assess the methodological quality of included studies. Review Manager 5.4.1 software was used to analyze heterogeneity and potential publication bias. RESULTS: A total of 11 criteria studies that satisfied the association between aerobic exercise and cognitive function following stroke were selected to be included in the review. Global cognition ability was significantly improved after aerobic exercise intervention (0.51; 95% confidence interval [CI] 0.16-0.86; P = .004), moderate intensity had the largest effect size on improving global cognition ability (0.98; 95% CI 0.48-1.47; P = .0001), none of cognitive flexibility, working memory, selective attention and conflict resolution showed the significant difference from zero. CONCLUSION: Aerobic exercise has a good impact on enhancing the cognitive dysfunction of patients after stroke, which stroke patients were found to benefit the most from moderate-intensity exercise. However, our studies did not found that aerobic exercise had an active result on cognitive flexibility, working memory, selective attention and contention resolution.

Greenhouse gas reduction and nitrogen conservation during manure composting by combining biochar with wood vinegar.

The constant greenhouse gases (GHGs) and ammonia emissions during pig manure (PM) composting have made large contributions to air pollution and global temperature rise. This study aimed to evaluate the addition of biochar (B) and wood vinegar (WV) to reduce GHGs emissions and improve nitrogen retention and microbial activities during PM composting. Different treatments, carried out under a 1:2 ratio (dry weight) of PM and sawdust mixture with the addition of B (5%) and various proportions of WV, include a control treatment (CT) without the addition of B and WV and, B, B+0.5%WV, B+1.0%WV, B+1.5%WV, and B+2.0%WV treatments. The results indicated that the addition of B could accelerate the composting process in contrast to CT. In addition, various amounts of WV with B decreased NH3, CO2, CH4 and N2O emissions by 18.82-35.88%, 1.38-15.39%, 16.98-62.73%, and 4.47-19.91%, respectively. Furthermore, in contrast to the B treatment, WV addition was more effective in decreasing GHGs and NH3 emissions, and the B+1.0% WV treatment displayed the lowest nitrogen loss (2.12%) and GHGs emissions (11.62 g/kg). The bacterial community analysis demonstrated that synergistic application of WV and B can increase the relative abundance of Proteobacteria which can contribute to nitrogen fixation and reduction of nitrogen loss. The results proved that combining B with WV can be a feasible strategy to effectively reduce GHGs emissions and improve nitrogen conservation in the composting industry.

Achieving Photon Upconversion in Mononuclear Lanthanide Molecular Complexes at Room Temperature.

Photon upconversion luminescence at the molecule scale is a rarely observed phenomenon despite possessing colossal potential for basic research and reality applications. Here we show that the eight-coordinate erbium molecular complex composed of Er3+ ion, dibenzoylmethane, and 2,2'-bipyridine exhibits upconversion emission. Under direct excitation at the absorption band of Er3+ ion at 980 nm, the complex shows upconverted green emissions of Er3+ ion at 525 and 545 nm at room temperature. Noticeably, upon the introduction of fluoride ions into this complex, an additional upconverted red emission at 667 nm appears as well, and the luminescence intensities of both the green and red emissions increase by a factor of 13 at most. This study not only provides a strategy to adjust the green and red emissions in mononuclear erbium complexes but also broadens the horizons of designing lanthanide-based molecular upconversion systems.

Upconversion/Downshifting Multimode Luminescence of Lanthanide-doped Nanocrystals for Multidimensional Information Encoding Security.

Information encoding security has always been a research hotspot in the optical field. Although many studies focused on luminescent materials and techniques for information security, the optical information encoding is limited by low information capacity and security. Herein, we present new core-shell-shell (CSS) lanthanide-doped nanocrystals which display multi-stimuli-responsive and multimode emission. In the designed CSS nanostructure, the Stokes and anti-Stokes processes can be both achieved in the same nanocrystals under the excitation of 1532, 980, and 254 nm via self-excited Er3+ and Ce3+ -sensitized mechanisms. Subsequently, a group of unique multimode emission CSS nanocrystals were designed as optical modules and successfully utilized in multidimensional information encoding, which demonstrates high-level information encoding capability and security. This work brings a powerful idea for information encoding security designs based on multimode luminesce materials.

Lanthanide-doped heterostructured nanocomposites toward advanced optical anti-counterfeiting and information storage.

The continuously growing importance of information storage, transmission, and authentication impose many new demands and challenges for modern nano-photonic materials and information storage technologies, both in security and storage capacity. Recently, luminescent lanthanide-doped nanomaterials have drawn much attention in this field because of their photostability, multimodal/multicolor/narrowband emissions, and long luminescence lifetime. Here, we report a multimodal nanocomposite composed of lanthanide-doped upconverting nanoparticle and EuSe semiconductor, which was constructed by utilizing a cation exchange strategy. The nanocomposite can emit blue and white light under 365 and 394 nm excitation, respectively. Meanwhile, the nanocomposites show different colors under 980 nm laser excitation when the content of Tb3+ ions is changed in the upconversion nanoparticles. Moreover, the time-gating technology is used to filter the upconversion emission of a long lifetime from Tb3+ or Eu3+, and the possibilities for modulating the emission color of the nanocomposites are further expanded. Based on the advantage of multiple tunable luminescence, the nanocomposites are designed as optical modules to load optical information. This work enables multi-dimensional storage of information and provides new insights into the design and fabrication of next-generation storage materials.