Amino-modified IONPs potentiates ferroptotic cell death due to the release of Fe ion in the lysosome.

Iron oxide nanoparticles (IONPs) have wide applications in the biomedical field due to their outstanding physical and chemical properties. However, the potential adverse effects and related mechanisms of IONPs in human organs, especially the lung, are still largely ignored. In this study, we found that group-modified IONPs (carboxylated, aminated and silica coated) induce slight lung cell damage (in terms of the cell cycle, reactive oxygen species (ROS) production, cell membrane integrity and DNA damage) at a sublethal dosage. However, aminated IONPs could release more iron ions in the lysosome than the other two types of IONPs, but the abnormally elevated iron ion concentration did not induce ferroptosis. Intriguingly, amino-modified IONPs aggravated the accumulation of intracellular peroxides induced by the ferroptosis activator RSL3 and thus caused ferroptosis in vitro, and the coadministration of amino-modified IONPs and RSL3 induced more severe lung injury in vivo. Therefore, our data revealed that the surface functionalization of IONPs plays an important role in determining their potential pulmonary toxicity, as surface modification influences their degradation behavior. These results provide guidance for the design of future IONPs and the corresponding safety evaluations and predictions.

Polyoxometalate Reinforced Perovskite Phase for High-Performance Perovskite Photovoltaics.

Ionic hybrid perovskites face challenges in maintaining their structural stability against non-equilibrium phase degradation, therefore, it is essential to develop effective ways to reinforce their corner-shared [PbI6]4- octahedral units. To strengthen structural stability, redox-active functional polyoxometalates (POMs) are developed and incorporated into perovskite solar cells (PSCs) to form a robust polyoxometalates/perovskite interlayer for stabilizing the perovskite phase. This approach offers several advantages: 1) promotes the formation of an interfacial connecting layer to passivate interfacial defects in addition to stabilize the [PbI6]4- units through exchanged ammonium cations in POMs with perovskites; 2) facilitates continuous structural repairing of Pb0- and I0-rich defects in the [PbI6]4- unit through redox electron shuttling of the electroactive metal ions in POMs; 3) provides guidance for selecting suitable redox mediators based on the kinetic studies of POM's effectiveness in reacting with targeted defects. The POM-reinforced device maintains 97.2% of its initial PCE after 1500 h of shelf-life test at 65 °C, while also enhancing the long-term operational stability. Additionally, this approach can be generally applicable across scalable sizes and various bandgap perovskites in devices, showing the promise of using functional POMs to enhance perovskite photovoltaic performance.

Highly Efficient and Stable Perovskite Solar Modules Based on FcPF6 Engineered Spiro-OMeTAD Hole Transporting Layer.

Li-TFSI doped spiro-OMeTAD is widely recognized as a beneficial hole transport layer (HTL) in perovskite solar cells (PSCs), contributing to high device efficiencies. However, the uncontrolled migration of lithium ions (Li+) during device operation has impeded its broad adoption in scalable and stable photovoltaic modules. Herein, an additive strategy is proposed by employing ferrocenium hexafluorophosphate (FcPF6) as a relay medium to enhance the hole extraction capability of the spiro-OMeTAD via the instant oxidation function. Besides, the novel Fc-Li interaction effectively restricts the movement of Li+. Simultaneously, the dissociative hexafluorophosphate group is cleverly exploited to regulate the unstable iodide species on the perovskite surface, further inhibiting the formation of migration channels and stabilizing the interfaces. This modification leads to power conversion efficiencies (PCEs) reaching 22.13% and 20.27% in 36 cm2 (active area of 18 cm2) and 100 cm2 (active area of 56 cm2) perovskite solar modules (PSMs), respectively, with exceptional operational stability obtained for over 1000 h under the ISOS-L-1 procedure. The novel FcPF6-based engineering approach is pivotal for advancing the industrialization of PSCs, particularly those relying on high-performance spiro-OMeTAD- based HTLs.

Efficient mineralization of cadmium and arsenic by poorly crystalline CaFe-layered double hydroxide in soil: Performance and mechanism.

The co-contamination of arsenic (As) and cadmium (Cd) in the environment is of most concern. In this work, poorly crystalline CaFe-layered double hydroxide (CaFe-LDH) was synthesized with a Ca-to-Fe molar ratio of 4 to ensure effective immobilization of Cd and As in soil. The application of Ca4Fe-LDH in soil remediation demonstrated that the targeted heavy metals gradually mineralized into a relatively stable oxidizable and residual state. At a soil remediation dosage of 1.6%, the availability levels of Cd and As decreased significantly, achieving stabilization efficiencies of 99% and 85.2% respectively. Cd is trapped through isomorphic substitution and dissolution-reprecipitation of calcium (Ca) laminate, resulting in the formation of CdCaFe-LDH mineralization products. As is immobilized through ion exchange with interlayer anions, redox with Fe(III), and Fe-Cd-As complexation. Moreover, the results of the characterization and density functional theoretical (DFT) calculations demonstrate that the CdCaFe-LDH formed by isomeric substitution of Ca for Cd enhanced the adsorption of As on the (110) plane of LDH, indicating that the trap mechanism of Cd and As by Ca4Fe-LDH is synergistically promoted. Overall, the above results prove that mineralization using Ca4Fe-LDH is a promising method to remediate soils combined contaminated by both Cd and As.

The influence of eight cognitive training regimes upon cognitive screening tool performance in post-stroke survivors: a network meta-analysis.

Background: Traditional meta-analysis offers only direct comparative evidence. The optimal cognitive training for poststroke cognitive impairment (PSCI) remains largely undetermined. Objectives: This study aims to assess and compare the effectiveness of selected cognitive training methods for PSCI patients and to identify and rank the most effective intervention programs. Methods: Searches were conducted in PubMed, Embase, Cochrane Library, Web of science, China National Knowledge Infrastructure, China Science and Technology Journal Database, Wanfang Database, and China Biomedical Database for randomized controlled trials up to September 30, 2023. Two researchers independently performed literature screening, data extraction, and quality assessment. Network meta-analysis was utilized to synthesize the main findings. The primary outcome focused on the intervention's impact on subjective cognitive function, with secondary outcomes including effects on activities of daily living, motor function, and functional independence. This study is registered with PROSPERO (CRD42023463282). Results: Fifty eligible randomized controlled trials were identified, revealing eight distinct interventions. These interventions collectively demonstrate efficacy in enhancing cognition. Traditional cognitive training significantly improves overall cognitive function, daily living function, motor function, and functional independence. In Loewenstein Occupational Therapy Cognitive Assessment, Barthel Index, Fugl-Meyer Assessment, and Functional Independence Measure scales, a combination of computer-based and traditional cognitive training outperformed the conventional control group MD = 29.97 (95%CI: 16.3, 44.2), MD = 18.67 (95%CI: 9.78, 27.45), MD = 28.76 (95%CI: 5.46, 51.79) and MD = 42.2 (95%CI: 5.25, 78.99). In the MMSE scale, virtual reality cognitive training combined with traditional training was most effective MD = 8.01 (95%CI: 3.6, 12.4). On the MoCA scale, the combination of exercise and cognitive training showed superior results MD = 6.68 (95%CI: 2.55, 10.78). Only the combined computer-based and traditional cognitive training, as well as traditional cognitive training alone, significantly enhanced functional independence, with no notable differences in other pairwise interventions. Conclusion: The network meta-analysis suggests that augmenting traditional training with other modalities may enhance overall effectiveness. Specifically, interventions incorporating computer-based cognitive training appear to surpass other methods in improving cognition, daily living function, motor skills, and functional independence. The findings of this network meta-analysis provide evidence-based guidance for clinical decision-making. Systematic Review Registration: https://www.crd.york.ac.uk/PROSPERO/, identifier in PROSPERO (CRD42023463282).

Single-cell RNA sequencing of OSCC primary tumors and lymph nodes reveals distinct origin and phenotype of fibroblasts.

Desmoplasia in fibroblasts within metastatic lymph nodes (MLNs) serves as an indicator of extranodal extension (ENE), which led mortality in oral squamous cell carcinoma (OSCC). However, systematic studies on fibroblasts in MLNs are lacking. Therefore, this study characterized the differences in phenotype, function, and origin of fibroblasts between primary tumors (PTs) and lymph nodes (LNs) in OSCC. We generated single-cell maps of PTs and paired MLNs and draining LNs from three OSCC patients. The transcriptomic atlas, pseudotime analysis, intercellular communication networks and enrichment analysis of the single cells were characterized. Phenotype and function heterogeneity of fibroblast cells between PTs and MLNs were further verified in vitro. Among 44,052 fibroblasts, we identified two distinct subpopulations of cancer-associated myofibroblastic cells (mCAFs): RGS4+ mCAF1 and COMP + mCAF2. Notably, they exhibited distinct distributions, with mCAF1 predominantly localized in the PTs and mCAF2 in the MLNs. Moreover, pseudotime analysis revealed their distinct origins: mCAF1 originated from inherent normal myofibroblastic cells in the PT, whereas mCAF2 originated from fibroblastic reticular cells in the LNs. Further functional experiments using primary fibroblasts revealed that, compared to mCAF1, mCAF2 in MLNs exhibited weaker crosstalk with immune cells but enhanced extracellular matrix activity, which is closely linked to ENE formation in OSCC. Additionally, we identified two fibroblast subgroups in a transforming state, indicating a potential epithelial-mesenchymal transition. Our research offers profound insights into the heterogeneity of fibroblasts between the PT and MLN in OSCC, serving as an essential resource for future drug discovery endeavors.

Maxillary impacted canine replacing a central incisor with root resorption: Multidisciplinary treatment in a preadolescent patient.

Maxillary canines are often impacted, which can result in tooth disorders and adversely affect occlusal and facial development. The case report describes complete bilateral impaction of maxillary canines and significant root resorption of a central incisor. The multidisciplinary approach is the optimal strategy for addressing impacted maxillary canines.

Associations of childhood and adulthood body size, and child-to-adult body size change with adult telomere length.

AIM: To comprehensively examine the associations of childhood and adulthood body size, and child-to-adult body size change with adult leucocyte telomere length (LTL). METHODS: We included 453 602 participants from the UK Biobank. Childhood body size at the age of 10 years was collected through a questionnaire. Adulthood body size was assessed using body mass index (BMI), waist circumference (WC), waist-to-hip ratio (WHR), fat mass index (FMI), and fat-free mass index (FFMI). RESULTS: Individuals with plumper body size in childhood exhibited shorter LTL in adulthood (-0.0086 [-0.0017, -0.0004]). Adulthood BMI (-0.0286 [-0.0315, -0.0258]), WC (-0.0271 [-0.0303, -0.0238]), WHR (-0.0269 [-0.0308, -0.0230]) and FMI (-0.0396 [-0.0438, -0.0351]) were negatively associated with LTL, whereas FFMI (0.0095 [0.0039, 0.0152]) was positively associated with LTL. Compared to individuals consistently having an average/normal weight in both childhood and adulthood, those who maintained or developed overweight/obesity from childhood to adulthood had a shorter adult LTL, regardless of childhood body size. Notably, the LTL shortening effect was not observed in individuals with plumper body size in childhood but normal weight in adulthood. CONCLUSIONS: Childhood and adulthood obesity are both associated with LTL shortening in adulthood. Transitioning to or maintaining overweight/obese status from childhood to adulthood is associated with shorter adult LTL, whereas this effect can be reversed if plumper children become normal weight.

Unified ionic and radical C-4 alkylation and arylation of pyridines.

C-H Functionalization of pyridines is an efficient strategy to access pyridine derivatives occurring in pharmaceuticals, agrochemicals, and materials. Nucleophilic additions to pyridiniums via both ionic and radical species have proven particularly useful. However, these reactions suffer from poor regioselectivity. By identifying an enzyme-mimic pocket-type urea activation reagent, we report a general platform for pyridine C-4 functionalization. Both ionic and radical nucleophiles can be incorporated to achieve the alkylation and arylation. Notably, the highly regioselective C-4 radical arylation is disclosed for the first time. The broad scope of nucleophiles and pyridines renders this platform applicable to the late-stage functionalization of drug-like molecules and the preparation of complex biologically important molecules.

Highly Durable Inverted Inorganic Perovskite/Organic Tandem Solar Cells Enabled by Multifunctional Additives.

Inverted perovskite/organic tandem solar cells (P/O TSCs) suffer from poor long-term device stability due to halide segregation in organic-inorganic hybrid wide-band gap (WBG) perovskites, which hinders their practical deployment. Therefore, developing all-inorganic WBG perovskites for incorporation into P/O TSCs is a promising strategy because of their superior stability under continuous illumination. However, these inorganic WBG perovskites also face some critical issues, including rapid crystallization, phase instability, and large energy loss, etc. To tackle these issues, two multifunctional additives based on 9,10-anthraquinone-2-sulfonic acid (AQS) are developed to regulate the perovskite crystallization by mediating the intermediate phases and suppress the halide segregation through the redox-shuttle effect. By coupling with organic cations having the desirable functional groups and dipole moments, these additives can effectively passivate the defects and adjust the alignment of interface energy levels. Consequently, a record Voc approaching 1.3 V with high power conversion efficiency (PCE) of 18.59 % could be achieved in a 1.78 eV band gap single-junction inverted all-inorganic PSC. More importantly, the P/O TSC derived from this cell demonstrates a T90 lifetime of 1000 h under continuous operation, presenting the most stable P/O TSCs reported so far.

Lung cancer brain metastasis and hemorrhagic cerebral venous thrombosis: experiences and lessons.

The incidence of lung cancer brain metastasis combined with hemorrhagic cerebral venous sinus thrombosis (CVST) is very rare, and the understanding and treatment experience of this case is insufficient. We reported a case of lung cancer brain metastasis accompanied by venous sinus thrombosis, and describe the diagnosis and treatment plan for colleagues to learn from experience and lessons.

Molecular response to the influences of Cu(II) and Fe(III) on forming biogenic manganese oxides by Pseudomonas putida MnB1.

The biogeochemical cycle of biogenic manganese oxides (BioMnOx) is closely associated with the environmental behavior and fate of various pollutants. It is significantly interfered by many metals, such as Cu and Fe. However, the bacterial molecular responses are not clear. Here, the effects of Cu(II) and Fe(III) on oxidation of manganese by Pseudomonas putida MnB1 and the bacterial molecular response mechanisms have been studied. The bacterial oxidation of manganese were promoted by both Fe(III) and Cu(II) and the final manganese oxidation rate of the Cu(II) group exceeded 16 % that of the Fe(III) group. The results of transcriptome indicated that Cu(II) promoted manganese oxidation by up-regulating the expression levels of multicopper oxidase (MCO) and peroxidase(POD), and by stimulating electron transfer, while Fe(III) promoted this process by accelerating the electron transfer and nitrogen cycling, and activating POD. The protein-protein interaction (PPI) network indicated that the MCO genes (mnxG and mcoA) were directly linked to the copper homeostasis proteins (cusA, cusB, czcC and cusF). Cytochrome c was closely related to the genes related to nitrogen cycling (glnA, glnL, and putA) and electrons transfer (cycO, cycD, nuoA, nuoK, and nuoL), which also promoted manganese oxidation. This study provides a molecular level insight into the oxidation of Mn(II) by Pseudomonas putida MnB1 with Cu(II) and/or Fe(III) ions.

Reproductive factors, genetic susceptibility and risk of type 2 diabetes: A prospective cohort study.

AIM: To explore the relationships of multiple reproductive factors with type 2 diabetes mellitus (T2DM) risk and the joint effects of reproductive factors and genetic susceptibility. METHODS: We included 262,368 women without prevalent T2DM from the UK biobank. Cox proportional hazards regression models were employed to estimate the relationships of reproductive factors with T2DM risk and the joint effects of reproductive factors and genetic susceptibility. RESULTS: During a mean follow-up of 12.2 years, 8,996 T2DM cases were identified. Early menarche (<12 years, hazard ratio (HR) 1.08 [95 % confidence interval (CI) 1.02;1.13]), late menarche (≥15 years, HR 1.11 [1.04;1.17]), early menopause (<45 years, HR 1.20 [1.12;1.29]), short reproductive lifespan (<30 years, HR 1.25 [1.16;1.35]), hysterectomy (1.31, HR [1.23;1.40]), oophorectomy (HR 1.28 [1.20;1.36]), high parity (≥4, HR 1.25 [1.17;1.34]), early age at first live birth (<20 years, HR 1.23 [1.16;1.31]), miscarriage (HR 1.13 [1.07;1.19]), stillbirth (HR 1.14 [1.03;1.27]), and ever used hormonal replacement therapy (HR 1.19 [1.14;1.24]) were related to a higher T2DM risk, while ever used oral contraceptives (HR 0.93 [0.89;0.98]) was related to a lower T2DM risk. Furthermore, women with reproductive risk factors and high genetic risk had the highest T2DM risk compared to those with low genetic risk and without reproductive risk factors. CONCLUSION: Our findings show that multiple reproductive factors are related to T2DM risk, particularly in women with high genetic risk.

Interaction between CAFs and apoptotic cancer cells promotes OSCC proliferation via STING signaling.

BACKGROUND: Apoptosis can fuel oncogenesis by the education of surrounding stromal cells. However, the function of cancer-associated fibroblasts (CAFs), which interacted with apoptotic cancer cells, in oral squamous cell carcinoma (OSCC) progression is still unknown. OBJECTIVES: This study aimed to explore the prognostic value of apoptosis and the biological effects of CAFs, interacted with apoptotic cancer cells, on OSCC. METHODS: A total of 166 samples from OSCC patients were stained via TUNEL reaction to evaluate the correlation between apoptosis and clinical characteristics. Cell viability and proliferation were assessed through flow cytometry and CCK-8 assays, respectively. Levels of mRNA and protein were examined through qRT-PCR, western blot and immunofluorescence. RESULTS: Higher percentage of apoptotic cancer cells in OSCC positively correlated with more Ki67+ cells and predicted poor clinical outcomes. Conditioned medium from CAFs exposed to apoptotic cancer cells significantly facilitated cell proliferation. Co-culture CAFs with apoptotic cancer cells dampened the phosphorylation of STING/IRF3 signaling, as well as the production of type I interferon, which was required for the inhibition of OSCC cell proliferation. CONCLUSION: These results demonstrate the interplay between apoptotic cancer cells and CAFs promotes OSCC proliferation via STING signaling, identifying a potential therapy targeted CAFs surrounded with apoptotic cancer cells for OSCC.

Transcriptome analysis of human dental pulp cells cultured on a novel cell-adhesive fragment by RNA sequencing.

AIM: The aim of the present work was to find an efficient method for safe and reliable expansion of human dental pulp cells (hDPCs) in vitro. Here, we examined the effect of a novel recombinant E8 fragment of Laminin-511 (iMatrix-511) in hDPCs regarding viability and cell spreading. Further, we investigated the underlying mechanisms governing its effects in hDPCs using RNA sequencing (RNA-seq). METHODOLOGY: hDPCs were obtained from caries-free maxilla third molars (n = 3). CCK-8 assay was conducted to measure the viability of cells cultured on iMatrix-511 and two other ECM proteins. Cell morphology was observed by phase contrast microscope. RNA-seq of hDPCs cultured on iMatrix-511 or noncoated control was performed on Illumina NovaseqTM 6000 platform. RESULTS: iMatrix-511 (0.5 µg/cm2) enhanced the viability of hDPCs to an extent better than COL-1 and gelatin. Short term culture of hDPCs on iMatrix-511 resulted in 233 differentially expressed genes (DEGs). The top 12 most upregulated genes were XIAP, AL354740, MRFAP1, AC012321, KCND3, TMEM120B, AC009812, GET1-SH3BGR, CNTN3, AC090409, GEN1 and PIK3IP1, whereas the top 12 most downregulated genes were SFN, KRT17, RAB4B-EGLN2, CSTA, KCTD11, ATP6V1G2-DDX39B, AC010323, SBSN, LYPD3, FOSB, AC022400 and CHI3L1. qPCR validation confirmed the significant upregulation of GEN1, KCND3, PIK3IP1 and MRFAP1. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed, with genes enriched in various extracellular matrix interaction, estrogen and fat metabolism-related functions and pathways. CONCLUSIONS: iMatrix-511 facilitated spreading and proliferation of hDPCs. It enhances expression of anti-apoptotic genes, while inhibits expression of epidermis development-related genes.

Annexin A5 is a novel prognostic biomarker in oral squamous cell carcinoma.

BACKGROUND: ANXA5, a notable tumor marker, displays irregular expression in diverse solid cancers, and links to local recurrence and metastasis rates. We aimed study the expression of ANXA5 in oral squamous cell carcinoma (OSCC) and its diagnostic and prognostic values. METHODS: 520 head and neck squamous cell carcinoma (HNSCC) patients in TCGA database and 124 OSCC patients in Nanjing stomatology hospital were enrolled in our study. Immunohistochemical analyses were performed using ANXA5 antibodies. Chi-square test was used to analyze the clinicopathological features. Survival rates were determined using the Kaplan-Meier method and log-rank test. RESULTS: Our results showed significantly elevated ANXA5 at the gene and protein levels in HNSCC and OSCC compared to non-tumor tissues. Histopathologically, ANXA5 was broadly present in OSCC tumor cells and fibroblast-like cells but absent in tumor-infiltrating lymphocytes, particularly at the invasive tumor front. Patients exhibiting high ANXA5 expression in these cells demonstrated poor differentiation, aggressive invasion patterns, and heightened lymph node metastasis risk, contributing to poorer postoperative outcomes. Remarkably, ANXA5 in fibroblast-like cells emerged as an independent risk factor impacting survival in OSCC patients. Gene set enrichment analysis (GSEA) highlighted ANXA5's involvement in key pathways like epithelial-mesenchymal transformation (EMT), TGF-beta signaling, and hypoxia, which correlated with adverse clinical outcomes in OSCC. CONCLUSION: ANXA5 emerges as a significant prognostic biomarker for OSCC, potentially influencing its metastasis via the EMT pathway.

Association of exposure to multiple metals with hemoglobin levels in Chinese children and adolescents.

BACKGROUND: Previous studies have linked single metal to hemoglobin levels in children and adolescents; however, studies with regards to metal mixtures are still limited. OBJECTIVE: We aimed to investigate the associations of single metal and metal mixtures with hemoglobin levels in children and adolescents. METHODS: We conducted a cross-sectional study of 2064 children and adolescents aged 6 to 19 years in Liuzhou, China in 2018. The concentrations of 15 metals in urine were determined by inductively coupled plasma mass spectrometry. Generalized linear regression and weighted quantile sum (WQS) regression were used to estimate the associations of single metal and metal mixtures with hemoglobin levels, respectively. RESULTS: The multivariable-adjusted ß-values for the highest versus the first quartiles of urinary metal concentrations were - 1.57 (95 % confidence interval [CI]: -3.01, -0.13) for chromium, -2.47 (95 % CI: -3.90, -1.05) for nickel and 1.88 (95 % CI: 0.49, 3.28) for copper. In addition, we found a significant negative association between the WQS index and hemoglobin levels (adjusted ß = -0.93, 95 % CI: -1.69, -0.19), with nickel contributing the most to the WQS index at 59.0 %. Subgroup analyses showed that exposure to urinary nickel or metal mixtures were associated with decreased hemoglobin levels in adolescents, but not in children (all Pinteration < 0.001). CONCLUSION: Among children and adolescents, urinary chromium and nickel concentrations were associated with decreased hemoglobin levels, while copper showed a positive relationship. Moreover, a negative association was observed between exposure to metal mixtures and hemoglobin levels. These findings need to be further validated in prospective studies.

Development of a Non-Target Screening and Quantitative Analysis Strategy Based on UPLC-Q-TOF/MS and UPLC-QQQ/MS to Improve the Quality Control of Wuling Capsule.

Herbal medicine has been widely valued because of its remarkable efficacy and minimal side effects. The quantitative analysis of herbal medicines is essential to ensure their safety and efficacy. The simultaneous detection of multiple quality markers (Q-markers) has emerged as an important approach and trend in herbal medicine quality control. In recent years, non-targeted screening has become an effective strategy for the discovery and identification of unknown compounds. This study developed a non-targeted screening and quantitative analysis strategy to discover, identify and quantify the multiple components that truly represent the efficacy of Wuling capsule. Within this strategy, 18 types of flavonoids were tentatively discovered and identified from Wuling capsule by analyzing mass cleavage pathways, the precise molecular weights of compounds, and comparing the data with a database. Ten types of flavonoids were determined after the comparison of the standards. Additionally, following the evaluation of the regression equation, linear range, limit of detection (LOD), limit of quantitation (LOQ), precision, repeatability, and recovery of the proposed quantitative method, six flavonoids were quantified. This method successfully screened, identified, and quantified the potential active components in Wuling capsule, providing insights for improving the quality control standards in other herbal medicines.

Ozone sensitivity regimes vary at different heights in the planetary boundary layer.

The sensitivity of tropospheric ozone (O3) to its precursors volatile organic compounds (VOCs) and nitrogen oxides (NOX) determines the emission reduction strategy for O3 mitigation. Due to the lack of comprehensive vertical measurements of VOCs, the vertical distribution of O3 sensitivity regimes has not been well understood. O3 precursor sensitivity determined by ground-level measurements has been generally used to guide O3 control strategy. Here, to precisely diagnose O3 sensitivity regimes at different heights in the planetary boundary layer (PBL), we developed a vertical measurement system based on an unmanned aerial vehicle platform to conduct comprehensive vertical measurements of VOCs, NOX and other relevant parameters. Our results suggest that the O3 precursor sensitivity shifts from a VOC-limited regime at the ground to a NOX-limited regime at upper layers, indicating that the ground-level O3 sensitivity cannot represent the situation of the whole PBL. We also found that the state-of-the-art photochemical model tends to underestimate oxygenated VOCs at upper layers, resulting in overestimation of the degree of VOCs-limited regime. Therefore, thorough vertical measurements of VOCs to accurately diagnose O3 precursor sensitivity is in urgent need for the development of effective O3 control strategies.

Evaluation of the re-bond strength of debonded metal and ceramic brackets following Er: YAG laser treatment.

BACKGROUND: Failure of orthodontic bracket bonds is a common occurrence during orthodontic treatment. This study investigated the impact of Er: YAG laser-based removal of adhesive from the bases of metal and ceramic brackets for re-bonding. METHODS: A total of 168 extracted premolars were collected from patients. 84 metal brackets were used to be bonded on the buccal surface of the premolars in Groups 1, 2, 3 and 4, while 84 ceramic brackets were applied in Groups I, II, III and IV. Group 1/I represented the initial bonding group, with Group 2/II being the re-bonding group with new brackets, while Groups 3/III and 4/ IV received recycled brackets treated by Er: YAG laser or flaming respectively. Both the first and second de-bonding were performed in all samples using a universal testing machine to determine the shear bond strength (SBS). The adhesive remnant index (ARI) was evaluated using a stereo-microscope. The new and the treated bracket bases were evaluated using scanning electron microscopy (SEM). Differences in initial bonding and re-bonding ability were analyzed through one-way ANOVAs, and differences in ARI were assessed with the Kruskal-Wallis test. RESULTS: Greater amounts of adhesive residue were observed on ceramic brackets treated by laser. The SBS values for recycled metal brackets in Group 3 (26.13 MPa) were comparable to Group 1 (23.62 MPa) whereas they differed significantly from Group 4 (12.54 MPa). No significant differences in these values were observed when comparing the 4 groups with ceramic brackets. ARI score in Group 4 (2-3 points) differed significantly from the three other groups (P < 0.05). For Group I, II, III and IV, similar ARI scores were observed (P > 0.05). SEM analysis didn't show apparent damage of bracket bases consisting of either metal or ceramic material treated by Er: YAG laser. CONCLUSIONS: Er: YAG laser treatment was superior to flame treatment as a means of removing adhesive without damaging the brackets. SBS values and ARI scores following Er: YAG laser treatment were similar to those for new brackets, offering further support for Er: YAG laser treatment as a viable means of recycling debonded brackets.