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Shigella spp. are enteric pathogens that pose a serious threat to public health worldwide. A novel saltatory rolling circle amplification (SRCA) assay was developed to detect Shigella spp. in food targeting the ipaH gene. SRCA as an isothermal amplification method requires no expensive thermocycle instrument and could avoid electrophoresis as visualization results was successfully applied for SRCA. In order to confirm the specificity of this assay, 34 strains including 11 strains belonging to different Shigella species and 23 non-Shigella bacteria were detected with pure cultures. The sensitivity of Shigella flexneri by SRCA was evaluated using agarose gel electrophoresis, which was 7.3 × 101 fg/μL. In addition, the amplification results were also determined by adding the fluorochrome, SYBR Green I (1 μL of 1000×), allowing naked eye visualization of results, and the sensitivity was 7.3 × 100 fg/μL. Moreover, the sensitivity of PCR was 7.3 × 102 fg/μL, showing that the sensitivity of SRCA by electrophoresis and SYBR Green I fluorescence were 10- and 100-fold higher than that of PCR, respectively. The detection limit of SRCA was also evaluated with artificially inoculated vegetable salad without enrichment, and it was 4.7 × 102 and 4.7 × 101 CFU/g by electrophoresis and fluorescence, respectively. The detection limit by PCR was 4.7 × 103 CFU/g, which was 10- and 100-fold higher than that of SRCA. Therefore, SRCA is a potentially reliable tool for rapid and specific detection of Shigella in food and could be useful in underdeveloped countries with limited resources.

Flipped classroom is an instructional model in which basic subject matter knowledge is learned prior to in-class sessions, and active learning experiences happen in class. To address a gap in recent research regarding students' pre-class learning design and its effect in flipped classroom, an experimental study was conducted to investigate in a flipped classroom course, how pre-service teachers' pre-class learning effect differed according to different pre-class learning materials by using t-test. The control group completed their pre-class learning by viewing ordinary videos, while the treatment group completed their pre-class learning by viewing interactive videos designed based upon the Knowledge Integration theory. Both groups have the same instructor, classroom learning activities, and learning evaluation methods. This study found that the learning achievement, self-efficacy, the application of cognitive and the metacognitive skills of the learners in the treatment group were significantly higher than those in the control group. In addition, the interactive pre-class videos were generally well received by the learners in flipped classroom.

Based on the calculation method summed up by Sokolov with theory and experience, this paper designs the relevant structural parameters of the steam ejector and establishes a two-dimensional CFD(Computational Fluid Dynamics) model of the steam ejector. Then, the numerical simulation software FLUENT is used to study the influence of NXP (Nozzle Exit Position) on the performance of the injector and the optimum NXP is obtained. The results show that the remaining structural parameters are kept unchanged, and only Nozzle Exit Position is changed, that has an optimal value. At this time, the injection coefficient of the injector is optimal, and the injection coefficient can be improved accordingly.

Smoking is an established risk factor for atherosclerosis through several underlying pathways. Moreover, in the development of atherosclerotic plaque formation, obesity, defined as excess fat mass accumulation, also plays a vital role in dyslipidemia and insulin resistance. Substantial evidence shows that cigarette smoking induces multiple pathological effects in adipose tissue, such as differentiation of adipocytes, lipolysis, and secretion properties in adipose tissue. Therefore, there is an emerging speculation in which adipose tissue abnormality induced by smoking or nicotine is likely to accelerate the progression of atherosclerosis. Herein, this review aims to investigate the possible interplay between smoking and adipose tissue dysfunction in the development of atherosclerosis.

Atherosclerosis has been identified as a chronic inflammatory disease of the arterial vessel wall. Accumulating evidence indicates that different cells from the tunica intima, media, adventitia, and perivascular adipose tissue not only comprise the intact and normal arterial vessel wall but also participate all in the inflammatory response of atherosclerosis via multiple intricate pathways. For instance, endothelial dysfunction has historically been considered to be the initiator of the development of atherosclerosis. The migration and proliferation of smooth muscle cells also play a pivotal role in the progression of atherosclerosis. Additionally, the fibroblasts from the adventitia and adipocytes from perivascular adipose tissue have received considerable attention given their special functions that contribute to atherosclerosis. In addition, numerous types of cytokines produced by different cells from the arterial vessel wall, including endothelium-derived relaxing factors, endothelium-derived contracting factors, tumor necrosis factors, interleukin, adhesion molecules, interferon, and adventitium-derived relaxing factors, have been implicated in atherosclerosis. Herein, we summarize the possible roles of different cells from the entire arterial vessel wall in the pathogenesis of atherosclerosis.

Lean-burn natural gas engines offer enhanced thermal efficiencies and reduced soot and NOx emissions. However, cycle-to-cycle variability in combustion that can result from unreliable ignition, variability in equivalence ratio and quenching is a challenge. Reliability of ignition can be improved by employing a dual-fuel ignition strategy in which a small quantity of diesel fuel is injected to initiate ignition. Computational studies of n-heptane/methane-air mixing layers are performed to provide insight into the fundamental physics of dual-fuel ignition. The results show that the characteristic time required for steady premixed flame propagation has three components: time for autoignition to occur, time for peak temperature to be achieved following autoignition, and time for steady flame propagation in the premixed fuel/air mixture to be achieved. The autoignition time correlates well with pressure and temperature of the unburned premixed charge. The time to achieve peak temperature is relatively short, but correlates with mixing layer thickness and premixed equivalence ratio. The time to achieve steady propagation correlates with mixing layer thickness and laminar flame speed and thickness. Subsequent work focuses on turbulent flame propagation in lean homogeneous mixtures by employing direct numerical simulations (DNS) under conditions that are relevant to lean-burn engines. Attention is specifically focused on the turbulent flame speed (ST) as a parameter of interest because of its importance in modeling combustion in engines. The studies are carried out in the thin reaction zone (TRZ) regime of turbulent premixed combustion. Normalized turbulence intensity (urms/SL) varies from 2 to 25 and the ratio of integral length scale to flame thickness (L o/δL) varies from 3.2 to 12.8. Initial studies show that the normalized turbulent flame speed (ST/SL) depends on more parameters than urms/SL suggested by some models. Although it is known that the turbulent flame speed varies with equivalence ratio, it is shown that the normalized turbulent flame speed does not change with equivalence ratio provided the Karlovitz (Ka) and Damköhler (Da) numbers are fixed. This suggests that Kaand/or Da are important parameters in characterizing the turbulent flame speed. Furthermore, ST/SL can be related to the flame area enhancement AT/AL and an efficiency factor Io which is close to unity. AT/AL is raised by increasing turbulent Reynolds number ReT and by reducing Ka. Increasing ReT leads to a broader spectrum of turbulent eddies that generate flame surface area. Increasing Karesults in fine wrinkling at the expense of larger scale wrinkling. This results in a net reduction in the effective surface area enhancement. Based on these insights, a correlation for ST that shows a dependence on Re T and Ka is proposed. Modeling of the Flame Surface Density (FSD) evolution is also considered. FSD is influenced by tangential strain rate and flame displacement speed. Surface averaged tangential strain rate is found to scale linearly with Ka. The effects of Ka on flame displacement speed are modeled using a Probability Density Function (PDF) based approach. The effects of premixed combustion on turbulence are investigated. For flames in the TRZ regime, the turbulence kinetic energy (TKE) decays monotonically across the flame brush. Scaling analyses of the terms in the transport equation of TKE reveal that viscous dissipation is the dominant contribution in the TKE equation. The relative importance of the other terms in the TKE equation decreases with increasing Ka.