Parametric knocking performance investigation of spark ignition natural gas engines and dual fuel engines

Both spark ignition (SI) natural gas engines and compression ignition (CI) dual fuel (DF) engines suffer from knocking when the unburnt mixture ignites spontaneously prior to the flame front arrival. In this study, a parametric investigation is performed on the knocking performance of these two engine types by using the GT-Power software. An SI natural gas engine and a DF engine are modelled by employing a two-zone zero-dimensional combustion model, which uses Wiebe function to determine the combustion rate and provides adequate prediction of the unburnt zone temperature, which is crucial for the knocking prediction. The developed models are validated against experimentally measured parameters and are subsequently used for performing parametric investigations. The derived results are analysed to quantify the effect of the compression ratio, air-fuel equivalence ratio and ignition timing on both engines as well as the effect of pilot fuel energy proportion on the DF engine. The results demonstrate that the compression ratio of the investigated SI and DF engines must be limited to 11 and 16.5, respectively, for avoiding knocking occurrence. The ignition timing for the SI and the DF engines must be controlled after −38 ◦CA and 3 ◦CA, respectively. A higher pilot fuel energy proportion between 5% and 15% results in increasing the knocking tendency and intensity for the DF Engine at high loads. This study results in better insights on the impacts of the investigated engine design and operating settings for natural gas (NG)-fuelled engines, thus it can provide useful support for obtaining the optimal settings targeting a desired combustion behaviour and engine performance while attenuating the knocking tendency

Social support, oral health knowledge, attitudes, practice, self-efficacy and oral health-related quality of life in Chinese college students

Abstract Oral health is crucial for health-related quality of life. However, the research on the factors affecting oral health status is not comprehensive enough. This investigation aimed to evaluate the multifaceted determinants of college students’ oral health status and explore the impact of social support, oral health literacy, attitudes, behaviors, and self-efficacy on OHRQoL. By surveying 822 students from a university. Baseline data included sociodemographics (gender, age), social support (MSPSS scale), oral health self-efficacy (SESS scale), oral health knowledge, attitudes, and practices (KAP questionnaire), and OHRQoL (OHIP-14 scale). Based on social cognitive theory, partial least squares structural equation modeling (PLS-SEM) and fuzzy set qualitative comparative analysis (fsQCA) were used to examine the relationship between the study variables. PLS-SEM results showed that knowledge, attitude, and practice predicted OHRQoL through self-efficacy. FsQCA results showed that the combination of different variables was sufficient to explain OHRQoL. The conclusion was that self-efficacy plays an important role and the combination of high-level knowledge, positive attitudes, and strong self-efficacy was important in improving OHRQoL. The results of this study provided a reference for the oral health strategy planning of college students in China

Changes of provenance of Permian and Triassic sedimentary rocks from the Ailaoshan suture zone (SW China) with implications for the closure of the eastern Paleotethys

Tectonic evolution of the Ailaoshan Ocean (eastern Paleotethys), especially on the timing of opening and closure, has long been debated. Published works on the Paleotethyan evolution were mainly dedicated to structural tectonics and magmatic and metamorphic rocks, whereas studies on sediment chemistry are rare. In this study, we present new chemical data on the Permian and Middle-Upper Triassic elastic sedimentary rocks from the Ailaoshan suture zone in southwestern Yunnan (SW China). Compared with the Post-Archean Australian Shale (PAAS) and the average upper continental crust, these Ailaoshan elastic rocks are generally depleted in LILEs (e.g. K and Rb) and HFSEs (e.g. Nb and Zr), and show varying LREE/HREE enrichments ((La/Yb)(N) = 1.32-11.86), flat HREE pattern and negative Eu anomalies (Eu/Eu* = 0.3-0.9). In spite of these similarities, the Permian samples have relatively low SiO2 (avg. 71.4 wt%) contents, K2O/Na2O (avg. 0.65) and Eu/Eu* (avg. 0.65) ratios, but high Al2O3 (avg. 14.1 wt%), TiO2 (avg. 0.60 wt%), (Fe2OT 3 + MgO) (avg. 6.96 wt%) contents, Al2O3/SiO2 (avg. 0.20) and (La/Yb)(N) (avg. 6.9) ratios, similar to greywackes from typical continental arcs. In contrast, the Upper Triassic samples have relatively high SiO2 (avg. 81.9 wt%) contents, K2O/Na2O (avg. 8.48) and La-N/Yb-N (avg. 9.74) ratios, but low Al2O3 (avg. 9.98 wt%), TiO2 (avg. 0.54 wt%), (Fe2OT 3 + MgO) (avg. 5.26 wt%) contents, Al2O3/SiO2 (avg. 0.12) and Eu/Eu* (avg. 0.64) ratios, similar to greywackes from typical passive continental margin. Moreover, the Permian samples have lower CIA values (Chemical Index of Alteration: 47-74, avg. 59) but higher ICV values (Index of Compositional Variability: 0.70-1.29, avg. 1.03) than those of PAAS, indicating relatively weak chemical weathering of the source rocks with low sediment maturity. In contrast, the Upper Triassic samples have relatively high CIA (77-84, avg. 80) but low ICV values (0.52-1.12, avg. 0.79), suggesting intense chemical weathering of the source rocks with high sediment maturity. The wide range of CIA (52-84, avg. 69) and ICV (0.50-1.14, avg. 0.88) values for the Middle Triassic samples suggest multiple detrital sources with varying degree of chemical weathering and diverse sediment maturity, as also supported by their wide range of detrital contents and chemical compositions. Based on the distinct chemical contrast between the Permian and Triassic sedimentary rocks, we infer that a significant change in detrital provenance and depositional setting may have occurred across the Middle and Late Triassic boundary, which was likely caused by the closure of the Ailaoshan Ocean

Design of Novel FBG-Based Sensor of Differential Pressure with Magnetic Transfer

In this paper, a differential pressure sensor with magnetic transfer is proposed, in which the non-electric measurement based on the fiber Bragg grating (FBG) with the position limiting mechanism is implemented without the direct contact of the sensing unit with the measuring fluid. The test shows that the designed sensor is effective for measuring differential pressure in the range of 0~10 kPa with a sensitivity of 0.0112 nm/kPa, which can be used in environments with high temperature, strong corrosion and high overload measurements

Decoding Roles of Exosomal lncRNAs in Tumor-Immune Regulation and Therapeutic Potential

Exosomes are nanovesicles secreted into biofluids by various cell types and have been implicated in different physiological and pathological processes. Interestingly, a plethora of studies emphasized the mediating role of exosomes in the bidirectional communication between donor and recipient cells. Among the various cargoes of exosomes, long non-coding RNAs (lncRNAs) have been identified as crucial regulators between cancer cells and immune cells in the tumor microenvironment (TME) that can interfere with innate and adaptive immune responses to affect the therapeutic efficiency. Recently, a few major studies have focused on the exosomal lncRNA-mediated interaction between cancer cells and immune cells infiltrated into TME. Nevertheless, a dearth of studies pertains to the immune regulating role of exosomal lncRNAs in cancer and is still in the early stages. Comprehensive mechanisms of exosomal lncRNAs in tumor immunity are not well understood. Herein, we provide an overview of the immunomodulatory function of exosomal lncRNAs in cancer and treatment resistance. In addition, we also summarize the potential therapeutic strategies toward exosomal lncRNAs in TME

Membrane vesicles derived from Streptococcus suis serotype 2 induce cell pyroptosis in endothelial cells via the NLRP3/Caspase-1/GSDMD pathway

Streptococcus suis serotype 2 (S. suis 2) is a zoonotic pathogen that clinically causes severe swine and human infections (such as meningitis, endocarditis, and septicemia). In order to cause widespread diseases in different organs, S. suis 2 must colonize the host, break the blood barrier, and cause exaggerated inflammation. In the last few years, most studies have focused on a single virulence factor and its influences on the host. Membrane vesicles (MVs) can be actively secreted into the extracellular environment contributing to bacteria-host interactions. Gram-negative bacteria-derived outer membrane vesicles (OMVs) were recently shown to activate host Caspase-11-mediated non-canonical inflammasome pathway via deliverance of OMV-bound lipopolysaccharide (LPS), causing host cell pyroptosis. However, little is known about the effect of the MVs from S. suis 2 (Gram-positive bacteria without LPS) on cell pyroptosis. Thus, we investigated the molecular mechanism by which S. suis 2 MVs participate in endothelial cell pyroptosis. In this study, we used proteomics, electron scanning microscopy, fluorescence microscope, Western blotting, and bioassays, to investigate the MVs secreted by S. suis 2. First, we demonstrated that S. suis 2 secreted MVs with an average diameter of 72.04 nm, and 200 proteins in MVs were identified. Then, we showed that MVs were transported to cells via mainly dynamin-dependent endocytosis. The S. suis 2 MVs activated NLRP3/Caspase-1/GSDMD canonical inflammasome signaling pathway, resulting in cell pyroptosis, but it did not activate the Caspase-4/-5 pathway. More importantly, endothelial cells produce large amounts of reactive oxygen species (ROS) and lost their mitochondrial membrane potential under induction by S. suis 2 MVs. The results in this study suggest for the first time that MVs from S. suis 2 were internalized by endothelial cells via mainly dynamin-dependent endocytosis and might promote NLRP3/Caspase-1/GSDMD pathway by mitochondrial damage, which produced mtDNA and ROS under induction, leading to the pyroptosis of endothelial cells

A machine learning model to predict efficacy of neoadjuvant therapy in breast cancer based on dynamic changes in systemic immunity

Objective: Neoadjuvant therapy (NAT) has been widely implemented as an essential treatment to improve therapeutic efficacy in patients with locally-advanced cancer to reduce tumor burden and prolong survival, particularly for human epidermal growth receptor 2-positive and triple-negative breast cancer. The role of peripheral immune components in predicting therapeutic responses has received limited attention. Herein we determined the relationship between dynamic changes in peripheral immune indices and therapeutic responses during NAT administration. Methods: Peripheral immune index data were collected from 134 patients before and after NAT. Logistic regression and machine learning algorithms were applied to the feature selection and model construction processes, respectively. Results: Peripheral immune status with a greater number of CD3+ T cells before and after NAT, and a greater number of CD8+ T cells, fewer CD4+ T cells, and fewer NK cells after NAT was significantly related to a pathological complete response (P < 0.05). The post-NAT NK cell-to-pre-NAT NK cell ratio was negatively correlated with the response to NAT (HR = 0.13, P = 0.008). Based on the results of logistic regression, 14 reliable features (P < 0.05) were selected to construct the machine learning model. The random forest model exhibited the best power to predict efficacy of NAT among 10 machine learning model approaches (AUC = 0.733). Conclusions: Statistically significant relationships between several specific immune indices and the efficacy of NAT were revealed. A random forest model based on dynamic changes in peripheral immune indices showed robust performance in predicting NAT efficacy