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Satellite navigation positioning has become an indispensable component of everyday life, where precise pinpointing and rapid convergence are crucial in delivering timely and accurate location information. However, due to the damping of integer ambiguities and system residual errors, the rapid convergence of Precise Point Positioning (PPP) implementation is a significant challenge. To address this, this paper proposes a novel Carrier Phase Zero-Baseline Self-Differencing Precise Point Positioning (CZS-PPP) technique and its ionosphere-free fusion model. By employing the proposed CZS-PPP approach in separate scenarios involving BDS-3, GPS, and dual-system settings, we systematically validate the efficacy of the method. The experimental results indicate that the convergence time of the method is less than 4 min in a single-system scenario. Furthermore, in a dual-system scenario, the method can achieve rapid convergence in less than 3 min. The CZS-PPP technique presented demonstrates the elimination of integer ambiguities and the effective suppression of system residuals, in comparison to the conventional method. The proposed approach has demonstrated remarkable performance across different systems, offering a promising new pathway for achieving PPP fast convergence in BDS/GNSS.
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OBJECTIVE: Eosinophilic solid and cystic renal cell carcinoma (ESC-RCC) is rare and difficult to diagnose. Therefore, we aim to investigate the imaging and pathologic features of ESC-RCC. METHODS: Fifteen cases of ESC-RCC with pathologically confirmed diagnoses were retrospectively collected: CT was performed in 15 cases and MRI in 9 cases. RESULTS: In these patients (6 males and 9 females) (age: mean, 53.3 ± 14.7 years; range, 27-72 years), all tumors were unilateral, renal, and solitary with no clinical symptoms and were classified into-type 1: cystic-solid component, with equal cystic and solid components, was the most common (8/15, 53.3%); type 2: predominantly cystic with a small solid component (4/15, 26.7%); and type 3: predominantly solid (3/15, 20%). The solid component showed equal/slightly higher density on the CT-plain-scan, equal/slightly high signal on the T1-weighted image (T1WI), and low signal on the T2-weighted image (T2WI). Ten cases showed progressive enhancement, while 5 showed a fast-wash-in and fast-wash-out enhancement. One patient experienced hemorrhage, while the others showed no signs of hemorrhage, necrosis, fat, or calcification. Pathologically, the tumor showed cystic solidity, with eosinophilic cytoplasm and granular basophilic-colored spots with focal or diffuse expression of CK20. Ten patients had componential nephrectomy and 5 had radical nephrectomy. No recurrence or metastasis was noted in any case at the follow-up (8-49 months). CONCLUSION: This study describes the imaging and pathologic features of a rare type of renal cancer and proposes 3 imaging types to enhance physicians' diagnosis of this disease and guide clinical diagnosis and treatment.
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Carcinoma de Células Renais , Neoplasias Renais , Imageamento por Ressonância Magnética , Tomografia Computadorizada por Raios X , Humanos , Masculino , Pessoa de Meia-Idade , Feminino , Carcinoma de Células Renais/diagnóstico por imagem , Carcinoma de Células Renais/patologia , Carcinoma de Células Renais/cirurgia , Neoplasias Renais/diagnóstico por imagem , Neoplasias Renais/patologia , Neoplasias Renais/cirurgia , Idoso , Adulto , Estudos Retrospectivos , Eosinofilia/diagnóstico por imagem , Eosinofilia/patologia , Eosinofilia/cirurgiaRESUMO
INTRODUCTION: Liver transplant (LT) recipients were at a high risk of infection during the coronavirus disease 2019 (COVID-19) pandemic. Our purpose was to compare the clinical characteristics of severe and non-severe groups of LT recipients with COVID-19, and to analyze their risk factors for severe disease. METHODOLOGY: 79 LT recipients with COVID-19 were divided into a non-severe group (n = 60) and a severe group (n = 19), and differences in clinical characteristics, laboratory tests, and chest computed tomography (CT) performance were analyzed. Logistic regression was used to identify risk factors with severe COVID-19. Receiver operating characteristic (ROC) curves were plotted and the area under curve (AUC) values were calculated to assess the predictive value for severe COVID-19. RESULTS: Age was statistically different (p < 0.001) between the two groups. The difference in neutrophil-to-lymphocyte ratio (NLR), serum creatinine (Scr), D-dimer, urea, C-reactive protein (CRP), lactate dehydrogenase (LDH), and the number of lung segments involved in inflammation between the two groups were statistically significant (p < 0.05). The results revealed that age (OR = 1.255, 95% CI 1.079-1.460), NLR (OR = 1.172, 95% CI 1.019-1.348), and Scr (OR = 1.041, 95% CI 1.016-1.066) were independent risk factors for severe COVID-19. The ROC results showed that high values for age, NLR and Scr predicted severe COVID-19, with AUC values of 0.775, 0.841 and 0.820, respectively, and 0.925 for the three factors combined. CONCLUSIONS: Advanced age, and elevated NLR and Scr are independent risk factors for severe COVID-19 in LT recipients.
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COVID-19 , Transplante de Fígado , SARS-CoV-2 , Transplantados , Humanos , COVID-19/diagnóstico , COVID-19/complicações , COVID-19/epidemiologia , Masculino , Fatores de Risco , Feminino , Pessoa de Meia-Idade , Adulto , Transplantados/estatística & dados numéricos , Índice de Gravidade de Doença , Fatores Etários , Estudos Retrospectivos , Idoso , Curva ROC , Tomografia Computadorizada por Raios X , NeutrófilosRESUMO
In recent years, the development of highly active and selective electrocatalysts for the electrochemical reduction of CO2 to produce CO and formic acid has aroused great interest, and can reduce environmental pollution and greenhouse gas emissions. Due to the high utilization of atoms, atom-dispersed catalysts are widely used in CO2 reduction reactions (CO2RRs). Compared with single-atom catalysts (SACs), multi-atom catalysts have more flexible active sites, unique electronic structures and synergistic interatomic interactions, which have great potential in improving the catalytic performance. In this study, we established a single-layer nitrogen-graphene-supported transition metal catalyst (TM-C2N1) based on density functional theory, facilitating the reduction of CO2 to CO or HCOOH with single-atom and multi-atomic catalysts. For the first time, the TM-C2N1 monolayer was systematically screened for its catalytic activity with ab initio molecular dynamics, density of states, and charge density, confirming the stability of the TM-C2N1 catalyst structure. Furthermore, the Gibbs free energy and electronic structure analysis of 3TM-C2N1 revealed excellent catalytic performance for CO and HCOOH in the CO2RR with a lower limiting potential. Importantly, this work highlights the moderate adsorption energy of the intermediate on 3TM-C2N1. It is particularly noteworthy that 3Mo-C2N1 exhibited the best catalytic performance for CO, with a limiting potential (UL) of -0.62 V, while 3Ti-C2N1 showed the best performance for HCOOH, with a corresponding UL of -0.18 V. Additionally, 3TM-C2N1 significantly inhibited competitive hydrogen evolution reactions. We emphasize the crucial role of the d-band center in determining products, as well as the activity and selectivity of triple-atom catalysts in the CO2RR. This theoretical research not only advances our understanding of multi-atomic catalysts, but also offers new avenues for promoting sustainable CO2 conversion.
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Conjugated polymers with tailorable composition and microarchitecture are propitious for modulating catalytic properties and deciphering inherent structure-performance relationships. Herein, we report a facile linker engineering strategy to manipulate the electronic states of metallophthalocyanine conjugated polymers and uncover the vital role of organic linkers in facilitating electrocatalytic oxygen reduction reaction (ORR). Specifically, a set of cobalt phthalocyanine conjugated polymers (CoPc-CPs) wrapped onto carbon nanotubes (denoted CNTs@CoPc-CPs) are judiciously crafted via in situ assembling square-planar cobalt tetraaminophthalocyanine (CoPc(NH2)4) with different linear aromatic dialdehyde-based organic linkers in the presence of CNTs. Intriguingly, upon varying the electronic characteristic of organic linkers from terephthalaldehyde (TA) to 2,5-thiophenedicarboxaldehyde (TDA) and then to thieno/thiophene-2,5-dicarboxaldehyde (bTDA), their corresponding CNTs@CoPc-CPs exhibit gradually improved electrocatalytic ORR performance. More importantly, theoretical calculations reveal that the charge transfer from CoPc units to electron-withdrawing linkers (i.e., TDA and bTDA) drives the delocalization of Co d-orbital electrons, thereby downshifting the Co d-band energy level. Accordingly, the active Co centers with more positive valence state exhibit optimized binding energy toward ORR-relevant intermediates and thus a balanced adsorption/desorption pathway that endows significant enhancement in electrocatalytic ORR. This work demonstrates a molecular-level engineering route for rationally designing efficient polymer catalysts and gaining insightful understanding of electrocatalytic mechanisms.
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Replication fork reversal, a critical protective mechanism against replication stress in higher eukaryotic cells, is orchestrated via a series of coordinated enzymatic reactions. The Bloom syndrome gene product, BLM, a member of the highly conserved RecQ helicase family, is implicated in this process, yet its precise regulation and role remain poorly understood. In this study, we demonstrate that the GCFC domain-containing protein TFIP11 forms a complex with the BLM helicase. TFIP11 exhibits a preference for binding to DNA substrates that mimic the structure generated at stalled replication forks. Loss of either TFIP11 or BLM leads to the accumulation of the other protein at stalled forks. This abnormal accumulation, in turn, impairs RAD51-mediated fork reversal and slowing, sensitizes cells to replication stress-inducing agents, and enhances chromosomal instability. These findings reveal a previously unidentified regulatory mechanism that modulates the activities of BLM and RAD51 at stalled forks, thereby impacting genome integrity.
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Tolerância ao Dano no DNA , Replicação do DNA , Humanos , RecQ Helicases/genética , RecQ Helicases/metabolismo , DNA/genética , DNA/metabolismo , Proteínas/metabolismo , Instabilidade Genômica , Rad51 Recombinase/genética , Rad51 Recombinase/metabolismo , Fatores de Processamento de RNA/metabolismoRESUMO
The cathodic oxygen reduction reaction (ORR) has been continuously attracting worldwide interest due to the increasing popularity of proton exchange membrane (PEM) fuel cells. So far, various Pt-group metal (PGM) or PGM-free catalysts have been developed to facilitate the ORR. However, there is still a gap to achieve the expected goals as proposed by the U.S. Department of Energy (DoE). Recently, PGM-free@PGM hybrid catalysts, such as the M/N/C@PtM catalyst, have achieved the milestones of oxygen reduction, as reviewed in our recent work. It is, nevertheless, still challenging to unravel the underlying structure-property relationships. Here, by applying different Pt/Co ratios, a series of Co/N/C@PtxCo catalysts are synthesized. Interestingly, the ORR activity and stability are not linear with the Pt content, but show a volcano-like curve with increased Pt usage. This relationship has been deeply unraveled to be closely related to the contents of pyrrolic N, pyridinic N, and graphitized carbon in catalysts. This work provides guidelines to rationally design the coupled PGM-free@PGM catalysts toward the ORR by appropriate surface engineering.
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Cost-effective and high-efficiency catalysts play a central role in various sustainable electrochemical energy conversion technologies that are being developed to generate clean energy while reducing carbon emissions, such as fuel cells, metal-air batteries, water electrolyzers, and carbon dioxide conversion. In this context, a recent climax in the exploitation of advanced earth-abundant catalysts has been witnessed for diverse electrochemical reactions involved in the above mentioned sustainable pathways. In particular, polymer catalysts have garnered considerable interest and achieved substantial progress very recently, mainly owing to their pyrolysis-free synthesis, highly tunable molecular composition and microarchitecture, readily adjustable electrical conductivity, and high stability. In this review, we present a timely and comprehensive overview of the latest advances in organic polymers as emerging materials for powerful electrocatalysts. First, we present the general principles for the design of polymer catalysts in terms of catalytic activity, electrical conductivity, mass transfer, and stability. Then, the state-of-the-art engineering strategies to tailor the polymer catalysts at both molecular (i.e., heteroatom and metal atom engineering) and macromolecular (i.e., chain, topology, and composition engineering) levels are introduced. Particular attention is paid to the insightful understanding of structure-performance correlations and electrocatalytic mechanisms. The fundamentals behind these critical electrochemical reactions, including the oxygen reduction reaction, hydrogen evolution reaction, CO2 reduction reaction, oxygen evolution reaction, and hydrogen oxidation reaction, as well as breakthroughs in polymer catalysts, are outlined as well. Finally, we further discuss the current challenges and suggest new opportunities for the rational design of advanced polymer catalysts. By presenting the progress, engineering strategies, insightful understandings, challenges, and perspectives, we hope this review can provide valuable guidelines for the future development of polymer catalysts.
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Root hairs are crucial in the uptake of essential nutrients and water in plants. This study showed that a zinc finger protein, GIS3 is involved in root hair growth in Arabidopsis. The loss-of-function gis3 and GIS3 RNAi transgenic line exhibited a significant reduction in root hairs compared to the wild type. The application of 1-aminocyclopropane-1-carboxylic acid (ACC), an exogenous ethylene precursor, and 6-benzyl amino purine (BA), a synthetic cytokinin, significantly restored the percentage of hair cells in the epidermis in gis3 and induced GIS3 expression in the wild type. More importantly, molecular and genetic studies revealed that GIS3 acts upstream of ROOT HAIR DEFECTIVE 2 (RHD2) and RHD4 by binding to their promoters. Furthermore, exogenous ACC and BA application significantly induced the expression of RHD2 and RHD4, while root hair phenotype of rhd2-1, rhd4-1, and rhd4-3 was insensitive to ACC and BA treatment. We can therefore conclude that GIS3 modulates root hair development by directly regulating RHD2 and RHD4 expression through ethylene and cytokinin signals in Arabidopsis.
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Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Inflorescência/metabolismo , Etilenos/metabolismo , Citocininas/metabolismo , Raízes de Plantas/metabolismo , Regulação da Expressão Gênica de Plantas , MutaçãoRESUMO
Highly robust flexible multifunctional film with excellent electromagnetic interference shielding and electrothermal/photothermal characteristics are highly desirable for aerospace, military, and wearable devices. Herein, an asymmetric gradient multilayer structured bacterial cellulose@Fe3O4/carbon nanotube/Ti3C2Tx (BC@Fe3O4/CNT/Ti3C2Tx) multifunctional composite film is fabricated with simultaneously demonstrating fast Joule response, excellent EMI shielding effectiveness (EMI SE) and photothermal conversion properties. The asymmetric gradient 6-layer composite film with 40% of Ti3C2Tx possesses excellent mechanical performance with exceptional tensile strength (76.1 MPa), large strain (14.7%), and good flexibility. This is attributed to the asymmetric gradient multilayer structure designed based on the hydrogen bonding self-assembly strategy between Ti3C2Tx and BC. It achieved an EMI SE of up to 71.3 dB, which is attributed to the gradient "absorption-reflection-reabsorption" mechanism. Furthermore, this composite film also exhibits excellent low-voltage-driven Joule heating (up to 80.3 °C at 2.5 V within 15 s) and fast-response photothermal performance (up to 101.5 °C at 1.0 W cm-2 within 10 s), which is attributed to the synergistic effect of heterostructure. This work demonstrates the fabrication of multifunctional bacterial cellulose@Fe3O4/carbon nanotube/Ti3C2Tx composite film has promising potentials for next-generation wearable electronic devices in energy conversion, aerospace, and artificial intelligence.
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Celulose , Nanotubos de Carbono , Dispositivos Eletrônicos Vestíveis , Celulose/química , Nanotubos de Carbono/química , Titânio/química , Bactérias , Nanocompostos/químicaRESUMO
Guinea pigs repeatedly exposed to Ixodes scapularis develop acquired resistance to the ticks (ATR). The molecular mechanisms of ATR have not been fully elucidated, and partially involves immune responses to proteins in tick saliva. In this study, we examined the metabolome of sera of guinea pigs during the development of ATR. Induction of components of the tyrosine metabolic pathway, including hydroxyphenyllactic acid (HPLA), were associated with ATR. We therefore administered HPLA to mice, an animal that does not develop ATR, and exposed the animals to I. scapularis. We also administered nitisinone, a known inhibitor of tyrosine degradation, to another group of mice. The mortality of I. scapularis that fed on mice given HPLA or nitisinone was 26 % and 72 % respectively, compared with 2 % mortality among ticks that fed on control animals. These data indicate that tick bites alter the guinea pig metabolome, and that the tyrosine metabolism pathway can potentially be targeted for I. scapularis control.
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Ixodes , Animais , Camundongos , Cobaias , Ixodes/fisiologia , Saliva , TirosinaRESUMO
Eukaryotic organisms constantly face a wide range of internal and external factors that cause damage to their DNA. Failure to accurately and efficiently repair these DNA lesions can result in genomic instability and the development of tumors (Canela et al., 2017). Among the various forms of DNA damage, DNA double-strand breaks (DSBs) are particularly harmful. Two major pathways, non-homologous end joining (NHEJ) and homologous recombination (HR), are primarily responsible for repairing DSBs (Katsuki et al., 2020; Li and Yuan, 2021; Zhang and Gong, 2021; Xiang et al., 2023). NHEJ is an error-prone repair mechanism that simply joins the broken ends together (Blunt et al., 1995; Hartley et al., 1995). In contrast, HR is a precise repair process. It involves multiple proteins in eukaryotic cells, with the RAD51 recombinase being the key player, which is analogous to bacterial recombinase A (RecA) (Shinohara et al., 1992). The central event in HR is the formation of RAD51-single-stranded DNA (ssDNA) nucleoprotein filaments that facilitate homology search and DNA strand invasion, ultimately leading to the initiation of repair synthesis (Miné et al., 2007; Hilario et al., 2009; Ma et al., 2017).
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Proteínas de Ligação a DNA , Reparo de DNA por Recombinação , Proteínas de Ligação a DNA/metabolismo , Reparo do DNA , Dano ao DNA , DNARESUMO
Regulating the local configuration of atomically dispersed transition-metal atom catalysts is the key to oxygen electrocatalysis performance enhancement. Unlike the previously reported single-atom or dual-atom configurations, we designed a new type of binary-atom catalyst, through engineering Fe-N4 electronic structure with adjacent Co-N2C2 and nitrogen-coordinated Co nanoclusters, as oxygen electrocatalysts. The resultant optimized electronic structure of the Fe-N4 active center favors the binding capability of intermediates and enhances oxygen reduction reaction (ORR) activity in both alkaline and acid conditions. In addition, anchoring M-N-C atomic sites on highly graphitized carbon supports guarantees of efficient charge- and mass-transports, and escorts the high bifunctional catalytic activity of the entire catalyst. Further, through the combination of electrochemical studies and in-situ X-ray absorption spectroscopy analyses, the ORR degradation mechanisms under highly oxidative conditions during oxygen evolution reaction processes were revealed. This work developed a new binary-atom catalyst and systematically investigates the effect of highly oxidative environments on ORR electrochemical behavior. It demonstrates the strategy for facilitating oxygen electrocatalytic activity and stability of the atomically dispersed M-N-C catalysts.
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Guinea pigs repeatedly exposed to Ixodes scapularis develop acquired resistance to the ticks (ATR). The molecular mechanisms of ATR have not been fully elucidated, and partially involve immune responses to proteins in tick saliva. In this study, we examined the metabolome of sera of guinea pigs during the development of ATR. Induction of components of the tyrosine metabolic pathway, including hydroxyphenyllactic acid (HPLA), were associated with ATR. We therefore administered HPLA to mice, an animal that does not develop ATR, and exposed the animals to I. scapularis . We also administered nitisinone, a known inhibitor of tyrosine degradation, to another group of mice. The mortality of I. scapularis that fed on mice given HPLA or nitisinone was 26% and 72% respectively, compared with 2% mortality among ticks that fed on control animals. These data indicate that metabolic changes that occur after tick bites contribute to ATR.
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Acquired resistance to ticks can develop when animals are repeatedly exposed to ticks. Recently, acquired resistance to Ixodes scapularis was induced in guinea pigs immunized with an mRNA-lipid nanoparticle vaccine (19ISP) encoding 19 I. scapularis proteins. Here, we evaluated specific mRNAs present in 19ISP to identify critical components associated with resistance to ticks. A lipid nanoparticle containing 12 mRNAs which included all the targets within 19ISP that elicited strong humoral responses in guinea pigs, was sufficient to induce robust resistance to ticks. Lipid nanoparticles containing fewer mRNAs or a single mRNA were not able to generate strong resistance to ticks. All lipid nanoparticles containing salp14 mRNA, however, were associated with increased redness at the tick bite site - which is the first manifestation of acquired resistance to ticks. This study demonstrates that more than one I. scapularis target within 19ISP is required for resistance to ticks, and that additional targets may also play a role in this process.
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Ixodes , Doença de Lyme , Animais , Cobaias , RNA Mensageiro , Ixodes/genéticaRESUMO
Pulmonary arterial hypertension (PAH) is a pathophysiological state of abnormally elevated pulmonary arterial pressure caused by drugs, inflammation, toxins, viruses, hypoxia, and other risk factors. We studied the therapeutic effect and target of tetramethylpyrazine (tetramethylpyrazine [TMP]; ligustrazine) in the treatment of PAH and we speculated that dramatic changes in myocardin levels can significantly affect the progression of PAH. In vivo, the results showed that administration of TMP significantly prolonged the survival of PAH rats by reducing the proliferative lesions, right ventricular systolic pressure (RVSP), mean pulmonary arterial pressure (mPAP), and the Fulton index in the heart and lung of PAH rats. In vitro, TMP can regulate the levels of smooth muscle protein 22-alpha (SM22-α), and myocardin as well as intracellular cytokines such as NO, transforming growth factor beta (TGF-ß), and connective tissue growth factor (CTGF) in a dose-dependent manner (25, 50, or 100 µM). Transfection of myocardin small interfering RNA (siRNA) aggravated the proliferation of pulmonary artery smooth muscle cells (PSMCs), and the regulatory effect of TMP on α-smooth muscle actin (α-SMA) and osteopontin (OPN) disappeared. The application of 10 nM estrogen receptor alpha (ERα) inhibitor MPP promoted the proliferation of PSMCs, but it does not affect the inhibition of TMP on PSMCs proliferation. Finally, we found that TMP promoted the nucleation of myocardin-related transcription factor-A (MRTF-A) and combined it with myocardin. In conclusion, TMP can inhibit the transformation of PSMCs from the contractile phenotype to the proliferative phenotype by promoting the formation of the nuclear (MRTF-A/myocardin) transcription complex to treat PAH.
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Hipertensão Arterial Pulmonar , Artéria Pulmonar , Ratos , Animais , Artéria Pulmonar/metabolismo , Artéria Pulmonar/patologia , Hipertensão Arterial Pulmonar/metabolismo , Hipertensão Arterial Pulmonar/patologia , Ratos Sprague-Dawley , Miócitos de Músculo Liso/metabolismo , Miócitos de Músculo Liso/patologiaRESUMO
BACKGROUND: Bone mesenchymal stem cell (BMSC)-derived exosomes (B-exos) are attractive for applications in enabling alloantigen tolerance. An in-depth mechanistic understanding of the interaction between B-exos and dendritic cells (DCs) could lead to novel cell-based therapies for allogeneic transplantation. OBJECTIVES: To examine whether B-exos exert immunomodulatory effects on DC function and maturation. MATERIAL AND METHODS: After mixed culture of BMSCs and DCs for 48 h, DCs from the upper layer were collected to analyze the expression levels of surface markers and mRNAs of inflammation-related cytokines. Then, before being collected to detect the mRNA and protein expression levels of indoleamine 2,3-dioxygenase (IDO), the DCs were co-cultured with B-exos. Then, the treated DCs from different groups were co-cultured with naïve CD4+ T cells from the mouse spleen. The proliferation of CD4+ T cells and the proportion of CD4+CD25+Foxp3+ T cells were analyzed. Finally, the skins of BALB/c mice were transplanted to the back of C57 mice in order to establish a mouse allogeneic skin transplantation model. RESULTS: The co-culture of DCs with BMSCs downregulated the expression of the major histocompatibility complex class II (MHC-II) and CD80/86 costimulatory molecules on DCs. Moreover, B-exos increased the expression of IDO in DCs treated with lipopolysaccharide (LPS). The proliferation of CD4+CD25+Foxp3+ T cells increased when cultured with B-exos-exposed DCs. Finally, mice recipients injected with B-exos-treated DCs had significantly prolonged survival after receiving the skin allograft. CONCLUSIONS: Taken together, these data suggest that the B-exos suppress the maturation of DCs and increase the expression of IDO, which might shed light on the role of B-exos in inducing alloantigen tolerance.
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Exossomos , Células-Tronco Mesenquimais , Camundongos , Animais , Exossomos/metabolismo , Transplante Homólogo , Células Dendríticas , Fatores de Transcrição Forkhead/metabolismo , Células da Medula ÓsseaRESUMO
Poor selectivity is a common problem faced by gas sensors. In particular, the contribution of each gas cannot be reasonably distributed when a binary mixture gas is co-adsorbed. In this paper, taking CO2 and N2 as an example, density functional theory is used to reveal the mechanism of selective adsorption of a transition metal (Fe, Co, Ni, and Cu)-decorated InN monolayer. The results show that Ni decoration can improve the conductivity of the InN monolayer while at the same time demonstrating an unexpected affinity for binding N2 instead of CO2. Compared with the pristine InN monolayer, the adsorption energies of N2 and CO2 on the Ni-decorated InN are dramatically increased from -0.1 to -1.93 eV and from -0.2 to -0.66 eV, respectively. Interestingly, for the first time, the density of states demonstrates that the Ni-decorated InN monolayer achieves a single electrical response to N2, eliminating the interference of CO2. Furthermore, the d-band center theory explains the advantage of Ni decorated in gas adsorption over Fe, Co, and Cu atoms. We also highlight the necessity of thermodynamic calculations in evaluating practical applications. Our theoretical results provide new insights and opportunities for exploring N2-sensitive materials with high selectivity.
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Bio-derived nanomaterials are promising candidates for spinning high-performance sustainable textiles, but the inherent flammability of biomass-based fibers seriously limits their applications. There is still an urgent need to improve fiber flame retardancy while maintaining excellent mechanical performance. Here, inspired by the structural properties of layered nanoclay, we report a novel and efficient strategy to synthesize the strong, super tough, and flame-retardant nanocellulose/clay/sodium alginate (CRS) macrofibers via wet-spinning and directional drying. Benefiting from the precise modulation of arrangement and orientation of nanoclay in macrofibers, the new inorganic structure exhibits excellent mechanical and thermal functional properties. The anisotropic structure contributes to high toughness: the tensile strength was 373.3 MPa and the toughness was 26.92 MJ·m-3. Remarkably, rectorite nanosheets as a thermal and qualitative insulator significantly improve the flame retardancy of the CRS fibers with a heat release rate as low as 6.07 W/g, thermal conductivity of 90.5 mW/(m·K), and good temperature tolerance (ranging from -196 to 100 °C). This facile and high-efficiency strategy may have great scalability in manufacturing high-strength, super tough, and flame-retardant fibers for emerging biodegradable next-generation artificial fibers.