Ultrafast Rejuvenation of Aged CsPbI3 Quantum Dots and Efficiency Improvement by Sequential 1-Dodecanethiol Post-Treatment Strategy.

Metal halide perovskite CsPbI3 quantum dots (QDs) have sparked widespread research due to their intriguing optoelectronic. However, the CsPbI3 QDs undergo inevitable aging and luminescence quenching caused by the weak binding ability of oleate (OA-)/oleylammonium (OAm+), hindering further practical application. Herein, we have realized ultrafast rejuvenation of the aged CsPbI3 QDs that have lost their photoluminescence performance based on a 1-dodecanethiol (DDT) surface ligand to restore the outstanding red light emission with a high photoluminescence quantum yield (PLQY) from 25 to 90%. Furthermore, CsPbI3 QDs with DDT surface treatment maintain a cubic phase and high PLQY value even after 35 days. The DDT ligands can form a strong bond with Pb2+ and passivate I- ion vacancies, enhancing radiative recombination efficiency and thereby improving the PLQY of the QDs. The stable yet easily accessible surface of the DDT-capped CsPbI3 QDs was successfully employed as white LEDs and exhibited considerable enhanced luminous performance, suggesting promising application in solid-state lighting fields.

Impact of different processing methods of Ligustrum lucidum Ait. on kidney-yin deficiency: a study based on pharmacodynamics and metabolomics research.

This study aimed to explore the pharmacodynamics and mechanisms of different processing methods of Ligustrum lucidum Ait. (LLA) in addressing kidney-yin deficiency (KYD). Forty-eight Sprague-Dawley rats were divided into eight groups based on their weight. The KYD model was established by intragastric administration of levothyroxine sodium. Each group was administered the corresponding treatment for 15 consecutive days. The general condition of the rats during the treatment period was observed. In addition, the levels of cyclic adenosine monophosphate (cAMP), cyclic guanosine monophosphate (cGMP), and the ratio of cAMP to cGMP in the serum of rats from different groups were measured. Serum samples were analyzed using the ultra-performance liquid chromatography (UPLC)-Orbitrap Fusion MS technique for metabolomics analysis. Compared with the model group, the general condition of the rats in the wine-steamed L. lucidum group (WL) and salt-steamed L. lucidum group (SSL) groups showed significant improvement. The serum levels of cAMP, cGMP, and the cAMP-to-cGMP ratio tended to return to normal. Metabolic analysis identified 38 relevant biomarkers and revealed 3 major metabolic pathways: phenylalanine, tyrosine, and tryptophan biosynthesis; phenylalanine metabolism; and sphingolipid metabolism. The different processing methods of LLA demonstrated therapeutic effects on KYD in rats, likely related to the restoration of disturbed metabolism by adjusting the levels of endogenous metabolites in the kidney. The SSL demonstrated significantly superior effects compared with the other four types of LLA processed products.

Nanoscale covalent organic frameworks for enhanced photocatalytic hydrogen production.

Nanosizing confers unique functions in materials such as graphene and quantum dots. Here, we present two nanoscale-covalent organic frameworks (nano-COFs) that exhibit exceptionally high activity for photocatalytic hydrogen production that results from their size and morphology. Compared to bulk analogues, the downsizing of COFs crystals using surfactants provides greatly improved water dispersibility and light-harvesting properties. One of these nano-COFs shows a hydrogen evolution rate of 392.0 mmol g-1 h-1 (33.3 µmol h-1), which is one of the highest mass-normalized rates reported for a COF or any other organic photocatalysts. A reverse concentration-dependent photocatalytic phenomenon is observed, whereby a higher photocatalytic activity is found at a lower catalyst concentration. These materials also show a molecule-like excitonic nature, as studied by photoluminescence and transient absorption spectroscopy, which is again a function of their nanoscale dimensions. This charts a new path to highly efficient organic photocatalysts for solar fuel production.

Lag projective synchronization of discrete-time fractional-order quaternion-valued neural networks with time delays.

This paper deals with the lag projective synchronization (LPS) problem for a class of discrete-time fractional-order quaternion-valued neural networks(DTFO QVNNs) systems with time delays. Firstly, a DTFOQVNNs system with time delay is constructed. Secondly, linear and adaptive feedback controllers with sign function are designed respectively. Furthermore, through Lyapunov direct method, DTFO inequality technique and Razumikhin theorem, some sufficiency criteria are obtained to ensure that the system in this article can achieve LPS. At last, the significance of the theoretical part of this paper is verified through numerical simulation.

Application effect of the online and offline mixed education mode in nursing practice based on the SMCR communication model.

Objective: To explore the application effect of the online and offline mixed teaching mode in nursing practice teaching based on the Source Message Channel Receiver (SMCR) communication model. Methods: By using the convenience sampling method, 15 nursing students who practiced their internship in the Department of Critical Care Medicine at Beijing Friendship Hospital affiliated to Capital Medical University for 4 weeks, from 1 April 2022 to 31 December 2023, were selected as the experimental group. A total of 16 nursing students who practiced in the same hospital in 2021 were selected as the control group. The control group used traditional teaching mode for teaching, and the experimental group used the online and offline teaching mode for teaching. The theoretical and practical achievements, competency, and teaching satisfaction of the two groups of nursing students were compared and analyzed after the internship. Results: The theoretical knowledge, operational performance, competence of the nurses, and satisfaction with the teaching in the experimental group were higher than those of the control group (P < 0.05). Conclusion: Based on the SMCR communication model, exploring the online and offline mixed teaching mode plays an important role in the teaching process of nursing practice, which can not only effectively improve the comprehensive performance of nursing students but also help to improve their satisfaction with teaching and has a positive impact on the cultivation of high-quality nursing talents.

Influence of a diet meal plan on pepsinogen I and II, gastrin-17, and nutritional status in gastric ulcer patients.

BACKGROUND: Gastric ulcers (GUs) have a high risk of clinical morbidity and recurrence, and further exploration is needed for the prevention, diagnosis, and treatment of the disease. AIM: To investigated the effects of a diet plan on pepsinogen (PG) I, PG II, gastrin-17 (G-17) levels and nutritional status in patients with GUs. METHODS: A total of 100 patients with GUs treated between May 2022 and May 2023 were enrolled, with 47 patients in the control group receiving routine nursing and 53 patients in the experimental group receiving dietary nursing intervention based on a diet plan. The study compared the two groups in terms of nursing efficacy, adverse events (vomiting, acid reflux, and celialgia), time to symptom improvement (burning sensation, acid reflux, and celialgia), gastric function (PG I, PG II, and G-17 levels), and nutritional status [prealbumin (PA) and albumin (ALB) levels]. RESULTS: The experimental group showed a markedly higher total effective rate of nursing, a significantly lower incidence of adverse events, and a shorter time to symptom improvement than the control group. Additionally, the experimental group's post-intervention PG I, PG II, and G-17 levels were significantly lower than pre-intervention or control group levels, whereas PA and ALB levels were significantly higher. CONCLUSION: The diet plan significantly reduced PG I, PG II, and G-17 levels in patients with GUs and significantly improved their nutritional status.

Exploring autism via the retina: Comparative insights in children with autism spectrum disorder and typical development.

Autism spectrum disorder (ASD) is a widely recognized neurodevelopmental disorder, yet the identification of reliable imaging biomarkers for its early diagnosis remains a challenge. Considering the specific manifestations of ASD in the eyes and the interconnectivity between the brain and the eyes, this study investigates ASD through the lens of retinal analysis. We specifically examined differences in the macular region of the retina using optical coherence tomography (OCT)/optical coherence tomography angiography (OCTA) images between children diagnosed with ASD and those with typical development (TD). Our findings present potential novel characteristics of ASD: the thickness of the ellipsoid zone (EZ) with cone photoreceptors was significantly increased in ASD; the large-caliber arteriovenous of the inner retina was significantly reduced in ASD; these changes in the EZ and arteriovenous were more significant in the left eye than in the right eye. These observations of photoreceptor alterations, vascular function changes, and lateralization phenomena in ASD warrant further investigation, and we hope that this work can advance interdisciplinary understanding of ASD.

Association between Human Blood Proteome and the Risk of Myocardial Infarction.

Background: The objective of this study is to estimate the causal relationship between plasma proteins and myocardial infarction (MI) through Mendelian randomization (MR), predict potential target-mediated side effects associated with protein interventions, and ensure a comprehensive assessment of clinical safety. Methods: From 3 proteome genome-wide association studies (GWASs) involving 9775 European participants, 331 unique blood proteins were screened and chosed. The summary data related to MI were derived from a GWAS meta-analysis, incorporating approximately 61,000 cases and 577,000 controls. The assessment of associations between blood proteins and MI was conducted through MR analyses. A phenome-wide MR (Phe-MR) analysis was subsequently employed to determine the potential on-target side effects of protein interventions. Results: Causal mediators for MI were identified, encompassing cardiotrophin-1 (CT-1) (odds ratio [OR] per SD increase: 1.16; 95% confidence interval [CI]: 1.13-1.18; p = 1.29 × 10 - 31 ), Selenoprotein S (SELENOS) (OR: 1.16; 95% CI: 1.13-1.20; p = 4.73 × 10 - 24 ), killer cell immunoglobulin-like receptor 2DS2 (KIR2DS2) (OR: 0.93; 95% CI: 0.90-0.96; p = 1.08 × 10 - 5 ), vacuolar protein sorting-associated protein 29 (VPS29) (OR: 0.92; 95% CI: 0.90-0.94; p = 8.05 × 10 - 13 ), and histo-blood group ABO system transferase (NAGAT) (OR: 1.05; 95% CI: 1.03-1.07; p = 1.41 × 10 - 5 ). In the Phe-MR analysis, memory loss risk was mediated by CT-1, VPS29 exhibited favorable effects on the risk of 5 diseases, and KIR2DS2 showed no predicted detrimental side effects. Conclusions: Elevated genetic predictions of KIR2DS2 and VPS29 appear to be linked to a reduced risk of MI, whereas an increased risk is associated with CT-1, SELENOS, and NAGAT. The characterization of side effect profiles aids in the prioritization of drug targets. Notably, KIR2DS2 emerges as a potentially promising target for preventing and treating MI, devoid of predicted detrimental side effects.

Spatial metabolomics method to reveal the differences in chemical composition of raw and honey-fried Stemona tuberosa Lour. by using UPLC-Orbitrap Fusion MS and desorption electrospray ionization mass spectrometry imaging.

INTRODUCTION: Stemona tuberosa Lour. (ST) is a significant traditional Chinese medicine (TCM) renowned for its antitussive and insecticidal properties. ST is commonly subjected to processing in clinical practice before being utilized as a medicinal substance. Currently, the customary technique for processing ST is honey-fried. Nevertheless, the specific variations in chemical constituents of ST before and after honey-fried remain unclear. OBJECTIVE: This work aimed to analyze the variations in chemical constituents of ST before and after honey-fried and to study the distribution of differential markers in the roots. METHODS: UPLC-Orbitrap Fusion MS combined with molecular network analysis was used to analyze the metabolome of ST and honey-fried ST (HST) and to screen the differential metabolites by multivariate statistical analysis. Spatial metabolomics was applied to study the distribution of differential metabolites by desorption electrospray ionization mass spectrometry imaging (DESI-MSI). RESULTS: The ST and HST exhibited notable disparities, with 56 and 61 chemical constituents found from each, respectively. After processing, the types of alkaloids decreased, and 12 differential metabolites were screened from the common compounds. The notable component variations were epibisdehydro-tuberostemonine J, neostenine, tuberostemonine, croomine, neotuberostemonine, and so forth. MSI visualized the spatial distribution of differential metabolites. CONCLUSIONS: Our research provided a rapid and effective visualization method for the identification and spatial distribution of metabolites in ST. Compared with the traditional method, this method offered more convincing data supporting the processing mechanism investigations of Stemona tuberosa from a macroscopic perspective.

Generalized Telangiectasia as a Hallmark of Intravascular Lymphoma: A Case Report and Literature Review.

A 55-year-old woman had remarkably generalized telangiectasia. Large atypical lymphoid cells were found within the lumen of small vessels, and CD20 was positive in her third skin biopsy. She was diagnosed with intravascular large B-cell lymphoma (IVLBCL) and went into remission of the skin manifestations after seven courses of R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone) and four courses of intravenous high-dose methotrexate (HD MTX). To our knowledge, this is the first case report of IVLBCL with generalized telangiectasia in China. From a review of the literature, we found that generalized telangiectasia is a remarkable manifestation of intravascular lymphoma, and the differential diagnosis of intravascular lymphoma and panniculitis or vasculitis is very important. When the diagnosis is confusing, multiple skin biopsies are useful.

Design and performance of double-layered artificial chordae.

Surgical repair with artificial chordae replacement has emerged as a standard treatment for mitral regurgitation. Expanded polytetrafluoroethylene (ePTFE) sutures are commonly employed as artificial chordae; however, they have certain limitations, such as potential long-term rupture and undesired material/tissue response. This study introduces a novel approach to artificial chordae design, termed the New Artificial Chordae (NAC), which incorporates a double-layered structure. The NAC comprises a multi-strand braided core composed of ultra-high molecular weight polyethylene (UHMWPE) fibers as the inner core, and an outer tube made of hydrophobic porous ePTFE. Compared to traditional ePTFE sutures, NAC exhibits increased flexibility, enhanced tensile strength, longer elongation and improved fatigue resistance. Moreover, NAC exhibits a more hydrophobic surface, which contributes to enhanced hemocompatibility. The study also includes in vivo investigations conducted on animal models to evaluate the biocompatibility and functional efficacy of the artificial chordae. These experiments demonstrate the enhanced durability and biocompatibility of the NAC, characterized by improved mechanical strength, minimal tissue response and reduced thrombus formation. These findings suggest the potential application of NAC as a prosthetic chordae replacement, offering promising prospects to address the limitations associated with current artificial chordae materials and providing novel ideas and approaches for the development of sustainable and biocompatible regenerative biomaterials.

Correction: Assessing the dynamic impacts of non-pharmaceutical and pharmaceutical intervention measures on the containment results against COVID-19 in Ethiopia.

[This corrects the article DOI: 10.1371/journal.pone.0271231.].

tRNA-derived fragment tRF-30 propels diabetes-induced retinal microvascular complications by regulating STAT3 signaling.

Transfer RNA-derived fragments (tRFs) represent a novel class of non-coding RNA transcripts that possess specific biological functions. However, the involvement of tRFs in retinal microvascular diseases remains poorly understood. In this study, we aimed to reveal whether modulation of tRF-30 expression could attenuate pathological retinal neovascular diseases. Our findings demonstrate a significant upregulation of tRF-30 expression levels in both in vivo models of diabetic retinopathy (DR) and in vitro endothelial sprouting models. Conversely, inhibition of tRF-30 expression suppressed the formation of abnormal neovascularization in the retina in vivo, while reducing the proliferation and migration activity of retinal vascular endothelial cells in vitro. We also found that tRF-30 modulates retinal neovascularization through the tRF-30/TRIB3/signal transducer and activated transcription 3 signaling pathway. Furthermore, we validated a significant upregulation of tRF-30 expression levels in the vitreous humor of DR patients, with high levels of both validity and specificity in diagnostic testing. Collectively, our findings highlight a pro-angiogenic role for tRF-30 in DR. Intervening in the tRF-30 signaling pathway may represent a promising prevention and treatment strategy for retinal angiogenesis.

Efficacy of urokinase in maintaining patency of hemodialysis catheters: A meta-analysis.

BACKGROUND: Catheter malfunctions are associated with reduced blood flow and interrupted dialysis during hemodialysis. AIM: This meta-analysis aimed to determine whether the use of urokinase to lock hemodialysis catheters can maintain their patency and prevent catheter-related bloodstream infections (CRBSIs). MATERIALS AND METHODS: The PubMed, Cochrane Library, Web of Science, Embase, and Chinese medical databases were searched for controlled trials of hemodialysis catheter locking using urokinase from database inception until July 15, 2021. The primary outcome was catheter malfunction, and the secondary outcomes were the peak catheter blood flow rate (Qb) and CRBSIs. RESULTS: Across 16 trials, 1,041 patients were randomized to receive either urokinase/urokinase mixture (treated) or heparin (control) locks once or thrice a week. Locking with urokinase alone or in combination with another substance significantly prevented catheter malfunction. The effect on Qb was significant, with that in the treated group being better than in the control group. Similarly, the incidence of CRBSIs in the treated group was lower. CONCLUSION: Urokinase locking maintains catheter patency more effectively than heparin. Prophylactic locking with urokinase or urokinase mixtures reduces incidences of catheter malfunction, which ensures the smooth progression of hemodialysis and reduces patient medical costs. The results of this study have important clinical implications and will provide guidance to medical practitioners globally.

Clinicopathologic features and outcomes of acute leukemia harboring PICALM::MLLT10 fusion.

The PICALM::MLLT10 fusion is a rare but recurrent cytogenetic abnormality in acute leukemia, with limited clinicopathologic and outcome data available. Herein, we analyzed 156 acute leukemia patients with PICALM::MLLT10 fusion, including 12 patients from our institutions and 144 patients from the literature. The PICALM::MLLT10 fusion preferentially manifested in pediatric and young adult patients, with a median age of 24 years. T-lymphoblastic leukemia/lymphoma (T-ALL) constituted 65% of cases, acute myeloid leukemia (AML) 27%, and acute leukemia of ambiguous lineage (ALAL) 8%. About half of T-ALL were classified as an early T-precursor (ETP)-ALL. In our institutions' cohort, mediastinum was the most common extramedullary site of involvement. Eight of 12 patients were diagnosed with T-ALL exhibiting a pro-/pre-T stage phenotype (CD4/CD8-double negative, CD7-positive), and frequent CD79a expression. NGS revealed pathogenic mutations in 5 of 6 tested cases, including NOTCH1, and genes in RAS and JAK-STAT pathways and epigenetic modifiers. Of 138 cases with follow-up, pediatric patients (<18 years) had 5-year overall survival (OS) of 71%, significantly better than adults at 33%. The 5-year OS for AML patients was 25%, notably shorter than T-ALL patients at 54%; this distinction was observed in both pediatric and adult populations. Furthermore, adult but not pediatric ETP-ALL patients demonstrated inferior survival compared to non-ETP-ALL patients. Neither karyotype complexity nor transplant status had a discernible impact on OS. In conclusion, PICALM::MLLT10 fusion is most commonly seen in T-ALL patients, particularly those with an ETP phenotype. AML and adult ETP-ALL patients had adverse prognosis. PICALM::MLTT10 fusion testing should be considered in T-ALL, AML, and ALAL patients.

Positive effects and mechanism of mulberry leaf extract on alleviating fatty liver hemorrhagic syndrome in laying hens.

This experiment was conducted to investigate the effects of mulberry leaf extract (MLE) on alleviating fatty liver hemorrhagic syndrome (FLHS) in laying hens. The 576 Jing Fen laying hens of 56 weeks of age with good health and similar weights (1.76 ± 0.17 kg) were randomly divided into 6 groups, with 8 replicates in each group and 12 chickens in each replicate. The experiment lasted 56 d. The control group was fed a corn-soybean meal diet. The FLHS group was fed a high energy-low protein (HELP) diet, and the other four experimental groups were fed HELP diets supplemented with 0.04, 0.40, 0.80, and 1.20% MLE, respectively. The results showed that HELP treatment significantly induced liver injury, which indicated that the FLHS model was successfully established. MLE supplementation could alleviate the FLHS by reducing the liver index, abdominal fat percentage, total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL), and very low-density lipoprotein (VLDL) in the serum (P < 0.05), and subsequently increase the egg production rate (P < 0.05). The laying hens fed 0.8% MLE exhibited the greatest production performance (P < 0.05) and could improve serum lipid levels. In addition, the genes associated with fatty acid synthesis (ACC, HMGR and SREBP-1C) were downregulated (P < 0.05), and genes related to fatty acid oxidation (CPT1A, AMPK, and ATGL) were found to be upregulated (P < 0.05). Supplementation with 1.2% MLE significantly reduced the relative abundance of Firmicutes and Desulfurized Bacillus (P < 0.05) and significantly increased the relative abundance of Fecal Bacillus (P < 0.05). In conclusion, MLE may regulate the mRNA expression of lipid metabolism-related genes through the AMPK signaling pathway and improve cecal microbiota balance and serum lipid levels to alleviate FLHS in laying hens and subsequently improve egg production performance.

Ferroptosis regulating lipid peroxidation metabolism in the occurrence and development of gastric cancer.

BACKGROUND: Gastric cancer is one of the most common malignant tumors in the world, and its occurrence and development involve complex biological processes. Iron death, as a new cell death mode, has attracted wide attention in recent years. However, the regulatory mechanism of iron death in gastric cancer and its effect on lipid peroxidation metabolism remain unclear. AIM: To explore the role of iron death in the development of gastric cancer, reveal its relationship with lipid peroxidation, and provide a new theoretical basis for revealing the molecular mechanism of the occurrence and development of gastric cancer. METHODS: The process of iron death in gastric cancer cells was simulated by cell culture model, and the occurrence of iron death was detected by fluorescence microscopy and flow cytometry. The changes of gene expression related to iron death and lipid peroxidation metabolism were analyzed by high-throughput sequencing technology. In addition, a mouse model of gastric cancer was established, and the role of iron death in vivo was studied by histology and immunohistochemistry, and the level of lipid peroxidation was detected. These methods comprehensively and deeply reveal the regulatory mechanism of iron death on lipid peroxidation metabolism in the occurrence and development of gastric cancer. RESULTS: Iron death was significantly activated in gastric cancer cells, and at the same time, associated lipid peroxidation levels increased significantly. Through high-throughput sequencing analysis, it was found that iron death regulated the expression of several genes related to lipid metabolism. In vivo experiments demonstrated that increased iron death in gastric cancer mice was accompanied by a significant increase in lipid peroxidation. CONCLUSION: This study confirmed the important role of iron death in regulating lipid peroxidation metabolism in the occurrence and development of gastric cancer. The activation of iron death significantly increased lipid peroxidation levels, revealing its regulatory mechanism inside the cell.

"Coir Raincoat"-Boosted Biomimetic Hydrogel for Efficient Solar Desalination and Wastewater Purification.

Solar-driven interfacial evaporation is an efficient method for purifying contaminated or saline water. Nonetheless, the suboptimal design of the structure and composition still necessitates a compromise between evaporation rate and service life. Therefore, achieving efficient production of clean water remains a key challenge. Here, a biomimetic dictyophora hydrogel based on loofah/carbonized sucrose@ZIF-8/polyvinyl alcohol is demonstrated, which can serve as an independent solar evaporator for clean water recovery. This special structural design achieves effective thermal positioning and minimal heat loss, while reducing the actual enthalpy of water evaporation. The evaporator achieves a pure water evaporation rate of 3.88 kg m-2 h-1 and a solar-vapor conversion efficiency of 97.16% under 1 sun irradiation. In comparison, the wastewater evaporation rate of the evaporator with ZIF-8 remains at 3.85 kg m-2 h-1 for 30 days, which is 16.3% higher than the light irradiation without ZIF-8. Equally important, the evaporator also showcases the capability to cleanse water from diverse sources of contaminants, including those with small molecules, oil, heavy metal ions, and bacteria, greatly improving the lifespan of the evaporator.

Assessing rural land use in contemporary China: Data compilation and methodology.

In rural areas, land use decisions are not only shaped by economic considerations but also deeply influenced by cultural and social factors. The objective of this research is to examine the complex and diverse aspects of making decisions about how land is used in rural communities, specifically by investigating the influence of cultural and social elements. Using empirical data and rigorous analysis, this research examine how traditional practices, social norms, and community dynamics influence land use patterns. The research topic focuses on the need to have a thorough understanding of the fundamental elements that affect land use choices in rural regions, going beyond only economic incentives. This research objective is to address a significant vacuum in the current literature by examining the cultural and social aspects of land usage. This research provides vital insights for policymakers and stakeholders engaged in land management and rural development projects. This research utilizes a mixed-methods approach, using qualitative interviews, participatory observations, and quantitative surveys to collect comprehensive data on the cultural and socioeconomic elements that impact land use choices. The research sample includes a wide range of rural areas, guaranteeing a thorough representation of various cultural settings and socioeconomic backgrounds. Our study reveals that cultural traditions, social networks, and power structures have a substantial impact on land use practices in rural regions. Traditional land tenure systems, community ownership arrangements, and customary land-use practices play a vital role in influencing land-use choices and resource distribution within communities. The significance of these results is substantial for policymakers, land managers, and rural development practitioners. Policymakers may create land use policies and actions that are more appropriate to the specific cultural and socioeconomic environment by understanding the complex relationship between these aspects. Furthermore, promoting community involvement and allowing local actors to participate in decision-making may result in land management results that are both more sustainable and fair.