Rubbing Events Research Articles

Quercetin-crosslinked chitosan nanoparticles: a potential treatment for allergic rhinitis

Allergic rhinitis (AR) remains a major health problem worldwide. Compared with traditional oral drugs, nasal administration avoids first-pass metabolism and achieve faster and more effective efficacy. In this study, we used the ion crosslinking method to prepare quercetin–chitosan nasal adaptive nanomedicine (QCS) delivery system and evaluated in the treatment of allergic rhinitis mice models. The obtained positively charged nanoparticles with a particle size of 229.2 ± 0.2 nm have excellent characteristics in encapsulation efficiency (79.604%), drug loading rate (14.068%), drug release (673.068 μg) and stability(> 7 days). Excitingly, QCS treatment significantly reduced the number of sneezing and nasal rubbing events in AR mice, while reducing the levels of inflammatory factors such as immunoglobulin E (IgE), interleukin (IL)-17, tumor necrosis factor (TNF)-α, and (IL)-6 to alleviate AR symptoms. Hematoxylin–eosin (HE) staining also showed the damaged nasal mucosa was improved. These experimental results suggest that QCS can effectively suppress allergic inflammation in a mouse model and hold promise as a therapeutic option for allergic rhinitis.

Open NASA Blade Models for Nonlinear Dynamics Simulations

Abstract This contribution presents a catalogue of open turbomachinery blade models dedicated to nonlinear dynamics simulations. Based on a specifically developed in-house computer code, three-dimensional computer-aided design (CAD) models and finite element (FE) models of multiple-circular-arc (MCA) NASA airfoils are generated. Both the in-house code and the models are made freely accessible online. To cover a wide range of geometries, 39 blades are considered from different stages and with different aspect ratios. It is expected that this blade catalogue will provide an opportunity for the direct comparison of recently developed methodologies relative to nonlinear vibration phenomena in turbomachines, including rubbing events and blade-tip/casing contacts. To this end, the paper also contains original results for some of the most emblematic NASA blades, with an emphasis on nonlinear interaction maps and a detailed presentation of redesign operations to mitigate high amplitude of vibrations when blade-tip/casing contacts occur.

Assessment of Geometric Nonlinearities Influence On NASA Rotor 37 Response to Blade Tip/Casing Rubbing Events

Abstract This paper uses a recently derived reduction procedure to study the contact interactions of an industrial blade undergoing large displacements. The reduction technique consists in projecting the dynamical problem onto a reduction basis composed of Craig-Bampton modes and a selection of their modal derivatives. The internal nonlinear forces due to large displacements are evaluated with the stiffness evaluation procedure and contact is numerically handled using Lagrange multipliers. The numerical strategy is applied on an open industrial compressor blade model based on the NASA rotor 37 blade in order to promote reproducibility of results. Two contact scenarios are investigated: one with direct contact between the blade and the casing and one with an abradable material deposited on the casing. The influence of geometric nonlinearities is assessed in both cases. In particular, contact interaction maps and abradable coating wear pattern maps are used to identify the main interactions that can be detrimental for the engine integrity.

Protective effect of miR-138-5p inhibition modified human mesenchymal stem cell on ovalbumin-induced allergic rhinitis and asthma syndrome.

The objective of the study is to evaluate the protective effects of human mesenchymal stem cells (hMSCs) modified with miR‐138‐5p inhibitor against the allergic rhinitis and asthma syndrome (ARAS). MiR‐138‐5p or negative control was transfected into hMSCs, and fluorescence‐activated cell sorting was used to evaluate hMSC surface markers. Quantitative real‐time PCR (qRT‐PCR) was used to evaluate miR‐138‐5p, SIRT1, caspase‐3, IL‐6, IL‐1β and TNF‐α levels after TNF‐α and IL‐6 stimulations. hMSCs with or without miR‐138‐5p inhibition was intranasally administered into ARAS mice (n = 10 each group), followed by monitoring sneezing and nasal rubbing events to evaluate the allergic symptoms. Histamine, ovalbumin‐specific IgE, IgG2a, IgG1 and LTC4 release were monitored in the serum and nasal lavage fluid using enzyme‐linked immunosorbent assay. Expression of SIRT1 and HMGB1/TLR4 pathway in nasal mucosa was assessed. After miR‐138‐5p inhibitor transfection, the hMSC lineage was preserved. Binding between SIRT1 and miR‐138‐4p was observed, and miR‐138‐5p inhibition led to upregulation of SIRT1. Inhibition of miR‐138‐5p led to attenuated inflammatory responses of hMSCs upon TNF‐α and IL‐6 stimulation, and allergic symptoms in mice, as well as histamine and ovalbumin‐specific IgG release. hMSCs with miR‐138‐5p inhibition showed characteristics of activated SIRT1 and inhibited HMGB1/TLR4 pathway. Inhibition of miR‐138‐5p in hMSCs enhanced its effects in attenuating inflammatory responses and allergic reaction in the ARAS model, which is presumably regulated by SIRT1 and the HMGB1/TLR4 pathway.

Overexpression of miR-224-5p alleviates allergic rhinitis in mice via the TLR4/MyD88/NF-κB pathway.

Inflammatory allergic reaction is the main cause of allergic rhinitis (AR). Previous studies indicated that miR-224-5p was downregulated in the nasal mucosa of patients with AR, while the function of miR-224-5p in AR remains unclear. To explore this issue, AR mouse model was established using ovalbumin (OVA). For treatment group, lentivirus (LV)-miR-224-5p or its control was intranasally administrated to AR mice. miR-224-5p expression was detected by reverse transcription-quantitative PCR, followed by assessing the immunoglobulin E (IgE) level. Pathological alterations in nasal mucosa were detected using Hematoxylin-Eosin staining and Sirius red staining, followed by assessing the levels of inflammatory cells and factors. The NLRP3 inflammasome and TLR4/MyD88/NF-κB pathway were measured by Western blot, and then the relationship between miR-224-5p and toll-like receptor 4 (TLR4) was verified. The results showed that miR-224-5p was significantly decreased in nasal mucosa of AR mice. AR mice exhibited increased sneezing and nasal rubbing events, IgE level in serum, and pathological alterations in nasal mucosa, while overexpression of miR-224-5p markedly attenuated these changes. The levels of inflammatory cells in nasal lavage fluid and pro-inflammatory factors in serum and nasal mucosa were significantly increased in AR mice, which were reduced by miR-224-5p overexpression. Of note, LV-miR-224-5p treatment remarkably suppressed the activations of NLRP3 inflammasome and the TLR4/MyD88/NF-κB pathway in AR mice. Furthermore, miR-224-5p could bind to 3’-untranslated region (3’-UTR) of TLR4 and negatively regulate TLR4 level. Overall, we conclude that miR-224-5p may relieve AR by negatively regulating TLR4/MyD88/NF-κB pathway, indicating that miR-224-5p may be a promising target for AR treatment.

Light-guided nudging and data-driven performance feedback improve hand hygiene compliance among nurses and doctors

Evidence-based practices to increase hand hygiene compliance (HHC) among health care workers are warranted. We aimed to investigate the effect of a multimodal strategy on HHC. During this 14-month prospective, observational study, an automated monitoring system was implemented in a 29-bed surgical ward. Hand hygiene opportunities and alcohol-based hand rubbing events were measured in patient and working rooms (medication, utility, storerooms, toilets). We compared baseline HHC of health care workers across periods with light-guided nudging from sensors on dispensers and data-driven performance feedback (multimodal strategy) using the Student's t test. The doctors (n = 10) significantly increased their HHC in patient rooms (16% vs 42%, P< .0001) and working rooms (24% vs 78%, P= .0006) when using the multimodal strategy. The nurses (n = 26) also increased their HHC significantly from baseline in both patient rooms (27% vs 43%, P = .0005) and working rooms (39% vs 64%, P< .0001). The nurses (n = 9), who subsequently received individual performance feedback, further increased HHC, compared with the period when they received group performance feedback (patient rooms: 43% vs 55%, P< .0001 and working rooms: 64% vs 80%, P< .0001). HHC of doctors and nurses can be significantly improved with light-guided nudging and data-driven performance feedback using an automated hand hygiene system.

MiR-31 attenuates murine allergic rhinitis by suppressing interleukin-13-induced nasal epithelial inflammatory responses.

The present study aimed to investigate whether microRNA (miR)-31 exerted therapeutic potential in allergic rhinitis (AR) and to explore its underlying mechanism. Firstly, the expression levels of miR-31 were detected by reverse transcription-quantitative PCR in the nasal mucosa of patients and mice. Subsequently, an ovalbumin (OVA)-induced animal model of AR was constructed. Allergic symptom score, histopathological characteristics, OVA-specific immunoglobulin E (IgE) titers, and T-helper (Th)1 and Th2 cell-related cytokine levels were analyzed in OVA-sensitized mice, miR-31-overexpressing mice, miR-negative control mice and control mice. Furthermore, interleukin (IL)-13-stimulated nasal epithelial cells (NECs) were used to assess the effects of miR-31 on the production of IL-13-induced inflammatory cytokines and mucin 5AC by performing western blotting and ELISA. The expression levels of miR-31 were significantly decreased in the nasal mucosa of the AR group compared with those in the control group. Moreover, upregulation of miR-31 markedly attenuated sneezing and nasal rubbing events, reduced nasal eosinophil infiltration and goblet cell hyperplasia, and decreased the levels of OVA-specific IgE and Th2-related cytokines. In addition, subsequent in vitro experiments showed that upregulation of miR-31 inhibited IL-13 receptor α1 chain expression and signal transducer and activator of transcription 6 phosphorylation in NECs. Furthermore, miR-31 suppressed IL-13-induced expression of thymic stromal lymphopoietin, granulocyte-macrophage colony-stimulating factor, eotaxin and mucin 5AC in NECs. In conclusion, these data revealed that miR-31 could ameliorate AR by suppressing IL-13-induced nasal epithelial inflammatory responses, and thus may serve as a novel therapeutic target for AR.

Nanomedicine-mediated prevention of inflammatory monocytes infiltration ameliorate ovalbumin-induced allergic rhinitis in mouse model

Th2 immune cells infiltration into nasal mucosa is one of the characters of allergic rhinitis (AR). We aimed to explore whether inhibition of Th2 immune cells infiltration would attenuate AR progression. AR mouse model was established by i.p. injection of ovalbumin (OVA). The infiltrated immune cells into nasal lavage fluid were detected by flow cytometry. Cytokine concentration in serum was determined by ELISA. AR mice symptoms were indicated by the number of sneezing and nasal rubbing events. In AR mice, CCL2 expression levels and CD45+CD11b+Ly6Chi inflammatory monocytes cells significantly increased as compared with control mice. CCL2 siRNA encapsulated nanoparticles (NPsiCCL2) prevent CCL2 expression and inflammatory monocytes infiltration in AR mice. NPsiCCL2 treatment dramatically decreased the number of sneezing and nasal rubbing events in AR mice. Moreover, NPsiCCL2 treatment attenuated serum OVA-specific IgE, OVA-specific IgG1 and histamine levels. Mechanically, NPsiCCL2 treatment attenuates AR symptoms via inhibiting Th2 cytokine (IL-4, IL-5 and IL-13) production. Nanomedicine-mediated prevention of inflammatory monocytes infiltration ameliorates ovalbumin-induced allergic rhinitis in mouse model.

Multi-physics numerical simulation of an experimentally predicted rubbing event in aircraft engines

This paper provides new insight on the simulation of blade-tip/casing rubbing events within aircraft engines accounting for thermomechanical effects within the casing. A multi-physics numerical strategy is presented in order to simulate an interaction experimentally witnessed on a full-scale low-pressure compressor. Experimental data are used for an accurate representation of the blade's incursion depth within the abradable coating. This numerical strategy combines Safran's in-house tool for rotor/stator interaction simulations with a finite element based thermomechanical analysis carried out with Ansys. This work underlines the distinct contributions of both dynamical and thermomechanical phenomena in the simulated interaction. Competition between wear and thermal expansions is investigated as well as their consequences on blade dynamics. The proposed numerical strategy yields an accurate description of the interaction phenomenon as wear patterns, critical speed, amplitude growth rate of the blade vibration and temperature levels may be predicted.

MiR-146a mimic attenuates murine allergic rhinitis by downregulating TLR4/TRAF6/NF-κB pathway.

Aim: This study aims to investigate whether microRNA (miR)-146a exerts therapeutic potential to allergic rhinitis (AR). Methods: Female BALB/c mice were randomly divided into the AR and miR-146a groups. miR-146a was administered into the nostril before ovalbumin (OVA) challenge daily on days 21-28. Results: The expression level of miR-146a in AR nasal mucosa was significantly decreased. miR-146a mimic markedly attenuated sneezing and nasal rubbing events, decreased the levels of ovalbumin-specific IgE as well as mastocyte- and basophil-related inflammatory cytokines, reduced inflammatory cells, affected the T-helper 2-released cytokines. Furthermore, miR-146a mimic inhibited the expressions of proteins relevant to Toll-like receptor 4 (TLR4)/TRAF6/NF-κB signaling pathway. Conclusion: The anti-inflammatory effects of miR-146a on AR might exert through the inhibition of the toll-like receptor 4 (TLR4)/TRAF6/NF-κB signaling pathway to some extent.

Effect of teeth bending and mushrooming damages on leakage performance of a labyrinth seal

To achieve higher aerodynamic performance, turbine usually works at tight clearance, which results in inevitable rub between the rotor and stator parts of labyrinth seal due to vibrations, misalignment, mechanical force, thermal stress, etc. In the rubbing events, contact between labyrinth fin and rotor part will commonly induce the teeth bending and mushrooming damages, which significantly affect the discharge performance of a labyrinth seal. To account for the influence of teeth bending and mushrooming on leakage performance of a straight-through labyrinth seal, the leakage rates and flow fields in the worn labyrinth seal are measured and also compared with the original design cases. With numerical methods, the discharge behaviors of the labyrinth seal with different degrees of bending and mushroom damages are analyzed. It shows that the predicted leakage performance and flow fields in the labyrinth seals match well with the experimental tests. For the bending cases, the leakage rates and flow patterns in labyrinth seals are dependent on the effective clearance and bending angle. The leakage ratio of forward bending case is smaller than that of backward bending case with the same geometrical dimensions. However, for the mushroomed labyrinth seals, the leakage rates and flow patterns are much dependent on the effective clearance but slightly dependent on the mushroom radius.

Continued Experimental Study on the Friction Contact between a Labyrinth Seal Fin and a Honeycomb Stator: Slanted Position

Labyrinth seals are a state-of-the-art sealing technology to prevent and control leakage flows at rotor–stator interfaces in turbomachinery. Higher pressure ratios and the economical use of cooling air require small clearances, which lead to potential rubbing events. The use of honeycomb liners allows for minimal leakage by tolerating rub events to a certain extent. A previous study within an EU project investigated the complex contact conditions of honeycomb liners, with the idealized contact of a seal fin and a single parallel metal foil representing the honeycomb double foil section. In the present work, the results for the slanted foil position are shown and compared to the previous results. The variation of rub velocity, incursion speed, incursion rate, and seal geometry in a test rig allows for the identification of the influence on contact forces, temperatures, and wear. For the slanted position, significantly lower friction temperatures are observed, leading to a higher ratio of abrasive wear. Overall, the rub test results demonstrate strong interactions between the contact forces, friction temperatures, and wear.

SIRT1 attenuates murine allergic rhinitis by downregulated HMGB 1/TLR4 pathway.

Conventional allergic rhinitis (AR) treatments have limitations due to the lack of safety and complete cure strategy. We evaluated the effects of silent information regulator 1 (SIRT1), a multifunctional molecule involved in a variety of inflammatory pathways, on murine AR model. Ovalbumin (OVA)-induced murine model was constructed, and recombinant SIRT1 was administered into the nostril continuously. The expression of SIRT1 was measured at mRNA and protein levels, and the allergic symptoms were evaluated. Protein levels of OVA-specific IgE, leukotriene C4 (LTC4), eosinophil cation protein (ECP), prostaglandin D2 (PGD2), as well as different inflammatory cytokine mediators in the serum and nasal lavage fluid (NLF), were assessed by ELISA. The effects of SIRT1 on human primary nasal epithelial cells challenged with tumour necrosis factor (TNF)-α were also evaluated by investigating the HMGB1/TLR4 signalling pathway. Administration of SIRT1 significantly alleviated OVA-induced AR symptoms with lower numbers of sneezing and nasal rubbing events, decreased levels of OVA-specific IgE, LTC4, ECP, PGD2, less inflammatory cells and downregulated levels of Th2 type cytokines. SIRT1 also reduced the genes of HMGB1/TLR4 signalling pathway in the murine model and cultured human nasal epithelial cells. Expression of SIRT1 is impaired in OVA-induced AR model. The administration of SIRT1 alleviates the allergic symptoms of mice, regulates the production of pro-inflammatory mediators predominantly produced by Th2 cells in AR and attenuates expressions of proteins relevant to HMGB1/TLR4 signalling pathway. All the results showed that SIRT1 is promising as a therapeutic agent of AR.

Temperature distribution of a simplified rotor due to a uniform heat source

In gas turbines, high combustion efficiency as well as operational safety are required. Thus, labyrinth seal systems with honeycomb liners are commonly used. In the case of rubbing events in the seal system, the components can be damaged due to cyclic thermal and mechanical loads. Temperature differences occurring at labyrinth seal fins during rubbing events can be determined by considering a single heat source acting periodically on the surface of a rotating cylinder. Existing literature analysing the temperature distribution on rotating cylindrical bodies due to a stationary heat source is reviewed. The temperature distribution on the circumference of a simplified labyrinth seal fin is calculated using an available and easy to implement analytical approach. A finite element model of the simplified labyrinth seal fin is created and the numerical results are compared to the analytical results. The temperature distributions calculated by the analytical and the numerical approaches coincide for low sliding velocities, while there are discrepancies of the calculated maximum temperatures for higher sliding velocities. The use of the analytical approach allows the conservative estimation of the maximum temperatures arising in labyrinth seal fins during rubbing events. At the same time, high calculation costs can be avoided.

Suppressive Effect of a Thioamide-Related Compound SH-2251 on a Murine Allergic Rhinitis Model

Background: SH-2251 inhibits IL-5 production and type2 airway inflammation in a murine bronchial asthma model. However, the therapeutic effect of SH-2251 on allergic rhinitis (AR) has not been tested. We investigated whether or not SH-2251 could improve the nasal symptoms and inflammation in the nasal mucosa of a murine model of AR.Methods: AR was induced via intraperitoneal injection of ovalbumin (OVA) followed by daily intranasal challenge with OVA. SH-2251 (10 mg/kg) or vehicle (DMSO+Tween80) was administered orally once a day in the same period as the nasal challenge. Nasal symptoms were evaluated by counting the number of sneezing and nasal rubbing events on days 14, 17, 21, 28 and 35. On day 35, the levels of Il4, Il5, Il13, Ifnγ and Il1rl1 mRNA in the nasal mucosa were examined. The histological findings were examined on day 36.Results: The numbers of sneezing and nasal rubbing events were significantly decreased by the administration of SH-2251. Both eosinophil infiltration and the hickness of the nasal mucosa were improved in the SH-2251- administered mice compared that in vehicle-treated control mice. The mRNA expression of Il5, Il13 and Il1rl1 in the nasal mucosa was significantly decreased in the SH-2251-treated group compared to the vehicle group.Conclusion: These results suggest that SH-2251 may be a new therapeutic candidate for AR. In addition, SH-2251 might improve the pathogenesis of type2 chronic inflammation by targeting the IL-33 signaling via the inhibition of Il1rl1 expression.

Anti-Allergic Properties of a Matured Fruit Extract of the Date Palm Tree (Phoenix dactylifera L.) in Mite-Sensitized Mice

The effects of oral ingestion of a hot water extract of matured fruit of the date palm tree (Phoenix dactylifera L.) on allergic responses were investigated in mite-sensitized mice. Sneezing and nose rubbing events in mice given a date extract-added diet were significantly lower than in those given an extract-free (control) diet. The serum total and mite antigen-specific immunoglobulin (Ig) E levels, and the number of spleen interleukin-4(+)CD4(+), IgE(+)B220(+) and FcεRIα(+)CD117(+) cells was significantly lower in mice given the date extract-added diet than in those given the control diet. Chlorogenic acid, pelargonin and ferulic acid significantly reduced the number of IgE(+)B220(+) cells, while chlorogenic acid and pelargonin significantly decreased the number of FcεRIα(+)CD117(+) cells in mouse spleen cell cultures. These results suggest that some polyphenols in the date may reduce mite-induced allergic symptoms in mice via a decrease in the number of IgE-producing plasma cells and high-affinity IgE receptor-expressing mast cells.

Down-regulation of K +–Cl − co-transporter 2 in mouse medullary dorsal horn contributes to the formalin-induced inflammatory orofacial pain

Cation chloride co-transporters, including K +–Cl − co-transporter 2 (KCC2) and Na +–K +–Cl − co-transporter 1 (NKCC1), are of particular importance to GABAergic transmission and thus involved in the development of hyperalgesia at the spinal level. However, there are fewer relevant reports in the trigeminal system. In this study, we investigated the behavioral changes and the accompanying change in the expressions of KCC2 and NKCC1 mRNAs in mouse medullary dorsal horn (MDH) after subcutaneous injection of formalin into the left vibrissa pad. Furthermore, we observed the behavioral changes following intracisternal injection of KCC2 antisense oligodeoxynucleotides (ASO) into naïve mice. Subcutaneous injection of formalin-induced a significant increase in the number of face rubbing events which are the indicators of spontaneous pain. Real-time reverse transcriptase-polymerase chain reaction (RT-PCR) results indicated that, compared to the saline control or the contralateral side, the ipsilateral mRNA level of KCC2 but not NKCC1, was significantly reduced in formalin-injected mice during phase 1 observation, followed by gradual recovery. Intracisternal injection of KCC2 ASO into naïve mice led to behavioral hypersensitivity similar to the hyperalgesia observed in formalin experiments. These findings indicate that peripheral inflammation induces down-regulation of KCC2 in the MDH, which may in turn facilitate the development of acute inflammatory pain. These results also suggest that preventing the down-regulation of KCC2 is a possible way to combat orofacial pain.