Science Progress最新文献

With the progress of deep space exploration activities, low freezing point propellants are required to ensure the normal operation of aerospace engines in deep space environments. Blending NO and nitrogen tetroxide is a commonly used method to decrease freezing point of propellant, which is called MON-X. Researches on MON-X/methyl hydrazine thruster with impinging injection and influences of initial temperature are rare, and there hasn't been a comparison between nitrogen tetroxide/methyl hydrazine thrusters and MON-X/methyl hydrazine thrusters. In order to study the operation characteristics of nitrogen tetroxide/methyl hydrazine and MON-25/methyl hydrazine bipropellant thrusters with impinging injection and investigate the influence of initial temperature on performances, simulation model was developed for a 25 N thruster, starting and stable working process of thrusters was numerically simulated with different oxidant types and initial temperatures. The results show that NO in the oxidant leads to differences in operating characteristics of nitrogen tetroxide thruster and MON-25 thruster. During starting and stable operating processes, dominant reactions of methyl hydrazine dehydrogenation are self-decomposition of methyl hydrazine and extraction of H from methyl hydrazine by NO₂, respectively. The main reactions that affect the temperature rise of combustion chamber are the oxidation of CH₃ to H₂O by OH, as well as small molecule oxidation-reduction reactions such as CO generated by HCN and OH. In a stable operating state, the smaller mass fraction of N₂O₄ in MON-25 leads to a lower temperature in the middle of the cylindrical section of MON-25 thruster than that in nitrogen tetroxide thruster. The combustion chamber pressure of MON-25 thruster does not change significantly in the initial temperature range from 293 K to 263 K. When the initial temperature of MON-25 thruster is 243 K and lower, severe lost on working performance of thruster occurred due to the impact of temperature on propellant gasification.

With the severity of global climate change becoming increasingly evident, the shift to renewable energy has become the key to achieving sustainable development. Using data from the prefecture level in China, we construct a comprehensive FinTech index from the institutional and individual levels using the entropy method, aiming to capture the multi-dimensional value of FinTech comprehensively. This paper quantifies the momentum that FinTech provides to the urban renewable energy transition. Our investigation shows that FinTech can play a crucial role in enhancing urban renewable energy transition, especially in cities with strict environmental policies, relatively developed economies, and eastern and midland cities. This study further reveals the impact path of FinTech-driven urban renewable energy transformation, and we find that the key path is to curb capital misallocation, strengthen public environmental attention, and improve green innovation. These results expand the research perspective of renewable energy transition and provide a path choice for China to realize renewable energy transition under the dual-carbon goal.

Objective: Percutaneous vertebroplasty (PVP) is a primary treatment for osteoporotic vertebral compression fractures (OVCF). Historically, surgeons preferred a bilateral approach for PVP; however, this approach may impose greater financial strain on patients. This retrospective study examines the efficacy of the unilateral approach compared to the bilateral approach.

Methods: A total of193 patients were categorized into Group A (unilaterally extrapedicular approach) and Group B (bilateral approach) based on the operative method. Efficacy was evaluated using perioperative indicators, follow-up results, and imaging evaluation results.

Results: Out of the 193 patients involved, 169 were eligible for analysis. All patients completed follow-up visits lasting 49-70 months. Compared to Group B, Group A exhibited significantly shorter operation time, puncture duration, amount of bone cement injected, and number of X-ray fluoroscopies (P < 0.05). While initial pain reduction, as measured by the visual analog scale and Oswestry Disability Index scores, was lower in Group A, the difference between the groups narrowed by the final follow-up. At the final imaging follow-up, no statistically significant differences were observed between the two groups regarding the relative height of the injured vertebral bodies and local Cobb angle measurements.

Conclusions: This technique holds the potential for accelerated patient rehabilitation and reduced hospitalization expenses, presenting a promising treatment option for OVCF patients.

Background: Following successful canalith repositioning procedures (CRPs), some patients with benign paroxysmal positional vertigo (BPPV) may experience residual symptoms. There is currently no consensus on whether these residual symptoms are related to the disease duration.

Objective: To examine the impact of BPPV duration on the persistence of residual symptoms following successful CRP.

Methods: A total of 102 idiopathic BPPV patients were enrolled and categorized into short-course and long-course groups based on the duration of the disease. The course of disease in the short-course group was less than or equal to 7 days. The long course of disease was longer than 7 days. All patients underwent swivel-chair-assisted CRP and were followed up 7-10 days after successful CRP. The Dizziness Handicap Inventory (DHI) questionnaire was administered to all patients before and after CRP.

Results: Before CRP, significant differences were observed between the two groups in total DHI score and its subdomains: Physical (DHI-P), Functional (DHI-F), and Emotional (DHI-E) (p < 0.05), indicating that long disease duration significantly affected all patient aspects. After CRP, significant differences remained in total DHI, DHI-P, DHI-F, and DHI-E scores (p < 0.05), with the long-course group consistently scoring higher. However, no significant differences were found in the changes in DHI scores across dimensions before and after CRP between the two groups.

Conclusion: The duration of BPPV did not influence CRP outcomes, but patients with a longer disease course were more likely to experience residual symptoms after successful CRP.

Objectives: Human papillomavirus (HPV) infection is closely related to upper respiratory mucosal lesions, and the most common disease is adult upper respiratory papilloma, which has a certain probability of cancer transformation.This study conducted in vitro tissue and cell experiments to explore the inflammatory mechanisms associated with HPV + adult laryngeal papilloma.

Methods: We compared differential expression of AIM2 and IL-1β between HPV (High-risk) negative and positive adult laryngeal papilloma patients. In vitro experiments were conducted to investigate the differences in expression of AIM2, Caspase-1, and IL-1β in HPV- and HPV+ upper respiratory mucosal cells.

Results: The expression level of AIM2 and IL-1β was higher in HPV (High-risk) positive papilloma tissue than HPV (High-risk) negative papilloma tissue. The expression of AIM2, Caspase-1, and IL-1β in HPV+ cells was also significantly higher than in HPV- cells.

Conclusions: The expression of IL-1β mediated by AIM2 was associated with chronic inflammation of upper respiratory mucosal tissue caused by HPV infection, and it may yet be associated with further pathological changes.

Objective: The aim of this study is to establish a population pharmacokinetic (PK) model for patients undergoing continuous veno-venous hemodiafiltration (CVVHDF) and optimize the dosing regimen of colistin sulfate.

Methods: A prospective observational study in a single center was conducted on patients who were administrated with colistin sulfate and CVVHDF for at least 48 h. Blood samples were obtained prior to dosing and four to six blood samples (primarily C_0.5h, C_1h, C_2h, C_4h, and C_6h) after dosing. The blood concentration of colistin sulfate was determined by ultra-high performance liquid chromatography-tandem mass spectrometry assay. The NONMEM program was used to establish the population PK model and perform Monte Carlo simulations. The predictability and stability of the model were internally evaluated by the goodness of fit plots, visual prediction check, and bootstraps.

Results: A total of 86 plasma concentrations from 20 patients were used for population PK modeling. A two-compartment model with first-order linear elimination best described the population PK characteristics of colistin sulfate. Cystatin C (CysC) and body weight (WT) were identified as covariates for clearance (CL). Internal evaluation results showed that the final model had good stability and prediction performance. Monte Carlo simulations showed that only when the body WT was 50 kg with CysC ≥3.07 mg/l, and when the body WT was 65 kg with CysC = 5.11 mg/l, and minimum inhibitory concentration (MIC) = 0.25 mg/l, the target attainment probability (PTA) of the daily dose of 1.5 million U regimen was ≥90%. All treatment regimens fail to achieve the target PTA when MIC = 1 mg/l.

Conclusions: With the decrease of CysC levels and the increase of WT, the dose of colistin sulfate may need to be increased. It may be prudent for colistin sulfate to consider an initial dose doubling and subsequent maintenance dosing regimen of 200-225 million unit daily, administered in 2-3 divided doses, to attain PTA standard. This study was registered at the Chinese Clinical Trial Registry (www.chictr.org.cn) (trial registration number ChiCTR2300072191).

Objective: Coronary artery disease (CAD) remains a significant global health burden, characterized by the narrowing or blockage of coronary arteries. Treatment decisions are often guided by angiography-based scoring systems, such as the Synergy Between Percutaneous Coronary Intervention with Taxus and Cardiac Surgery (SYNTAX) and Gensini scores, although these require invasive procedures. This study explores the potential of electrocardiography (ECG) as a noninvasive diagnostic tool for predicting CAD severity, alongside traditional risk factors.

Methods: This retrospective cross-sectional study was conducted on 348 CAD patients who underwent coronary angiography. Demographic data, ECG findings, SYNTAX, and Gensini scores were collected. The association between ECG findings and demographic information with the severity of coronary artery stenosis, as assessed by SYNTAX and Gensini scores, was investigated using SPSS software, version 23.

Results: Significant associations were observed between CAD severity and risk factors such as male gender, diabetes mellitus (DM), and smoking. Additionally, certain ECG indicators, including Q waves and ST depression (STD), showed significant correlations with CAD severity, particularly according to the Gensini score.

Conclusion: This study underscores the utility of ECG and clinical factors in identifying severe CAD, offering cost-effective diagnostic alternatives to angiography. Integrating various parameters into a single score is crucial in clinical practice, providing a stronger diagnostic and prognostic tool without increasing costs. Further comprehensive studies are warranted to refine risk prediction models and improve CAD management strategies.

Vangl2, a core component of the PCP signaling pathway, serves as a scaffold protein on the cell membrane, playing a crucial role in organizing protein complexes. Cilia, dynamic structures on the cell surface, carry out a wide range of functions. Research has highlighted a bidirectional regulatory interaction between Vangl2 and cilia, underscoring their interconnected roles in cellular processes. This relationship is demonstrated by the localization of Vangl2 at the base and proximal regions of cilia, where it plays essential roles in ciliary positioning, asymmetric distribution, and ciliogenesis. In contrast, the absence of cilia can disrupt Vangl2-mediated signal transduction processes. This review offers a narrative review of recent research on Vangl2's function in cilia and examines the regulatory effects of cilia on Vangl2-mediated signaling.

Objective: In this feasibility study, firstly, we aimed to assess whether intramuscular pH (IMpH) could be measured with a glass-tipped electrode. Secondly, we aimed to explore whether we could monitor changes in skeletal muscle pH before and throughout static (isometric) and after dynamic (treadmill) exercise, comparing individuals with intermittent claudication (IC) to a group of healthy controls.

Methods: Forty participants with IC (mean age ± SD) 68 ± 8) and 40 healthy volunteers (63 ± 10) were recruited. Participants in the IC group had an ankle brachial pressure index of <0.7 (mean: 0.62 ± 0.13). The first 20 participants in each group underwent isometric ankle dorsiflexion for 120 s at 30% of maximum voluntary contraction and the remainder underwent treadmill exercise (3.6 km/h, 5° incline) to maximal walking distance. A sterilised reusable 1.5 mm shatterproof, heat strengthened glass tipped pH probe inserted using a peripheral venous cannula and in combination with a pH meter was used to measure IMpH of the tibialis anterior muscle prior to, during and continuously for 1 h after exercise.

Results: Resting IMpH was similar between the groups (median 6.8 (interquartile range (IQR) 6.7-6.9)) for IC individuals and 6.7 (6.6 to 6.8) for controls). Following isometric exercise, the magnitude of the decrease in IMpH was greatest in the IC group (median ΔpH max. in patients -0.2 (IQR: -0.2 to -0.1) versus -0.1 (IQR: -0.2 to -0.1) in the control group (p = 0.002). After treadmill exercise, the magnitude of the decrease in IMpH (ΔpH max) was greatest in individuals with IC (median ΔpH max. in patients -0.3 (IQR: -0.3 to -0.3) versus 0 (IQR: -0.2 to 0) in the control group, p = 0.04.

Conclusions: IMpH monitoring with a flexible glass probe inserted into the tibialis anterior muscle is viable and changes in IMpH during static and dynamic exercises are detected.

Zika virus (ZIKV) is a flavivirus of significant epidemiological importance, utilizing various transmission strategies and infecting "immune privileged tissues" during both the pre- and postnatal periods. One such transmission method may involve extracellular vesicles (EVs). EVs can travel long distances without degrading, carrying complex messages that trigger different responses in recipient cells. They can easily cross specialized tissue barriers, such as the placental barrier and the blood-brain barrier, which protects the central nervous system. It is known that some viruses can hijack and exploit the EVs biogenesis machinery to package regulatory elements, viral segments, and even complete viral genomes. This allows them to evade the immune system, amplify their tropism, and enhance their spread. ZIKV likely uses EVs produced by infected cells to insert its genomic RNA or parts of it. This mechanism can ensure viral entry and infection of the nervous tissue, partly explaining its broad viral tropism and silent persistence in various tissues and organs for months. This narrative review summarizes the main features of ZIKV and EVs, highlighting the most recent evidence on the involvement and effects of EVs during ZIKV infection. It also discusses the possibility of EVs acting as carriers of ZIKV through the nervous tissue.