Turbulent flame propagation with pressure oscillation in the end gas region of confined combustion chamber equipped with different perforated plates

Experiments were conducted in a newly designed constant volume combustion chamber with a perforated plate by varying the initial conditions. Hydrogen-air mixtures were used and the turbulent flame, shock wave, and the processes of flame-shock interactions were tracked via high-speed Schlieren photography. The effects of hole size and porosities on flame and shock wave propagation, intensity of the shock wave and pressure oscillation in closed combustion chamber were analyzed in detail. The effect of interactions between the turbulent flame and reflected shock or acoustic wave on the turbulent flame propagation was comprehensively studied during the present experiment. The results demonstrated that flame front propagation velocity and pressure oscillation strongly depend on the hole size and porosities of the perforated plate. The flame front propagation velocity in the end gas region increases as hole size increases and porosity decreases. The flame front propagation intensity in the end region of a confined space is strongly relevant to two competing effects: the initial turbulent formation and turbulent flame development. The experimental results indicated that an oscillating flame is associated with both the reflected shock wave and the acoustic wave. Meanwhile, different turbulent flame propagations and combustion modes were observed

Experimental Investigation of Turbulent Flame Propagation and Pressure Oscillation in a Constant Volume Chamber Equipped With an Orifice Plate

<p>In this work, the main contribution is an understanding of different combustion phenomena involving flame acceleration, flame propagation, and the pressure oscillation resulting from flame-shock interactions. These physical phenomena were experimentally studied using a newly developed confined combustion chamber equipped with one or two orifice plates. The results showed that there are five stages of flame propagation when a laminar flame passes through the orifice plate in a confined space. These include the deceleration of the laminar flame, jet flame formation and rapid acceleration, deceleration of the flame, turbulent flame formation and acceleration, and turbulent flame propagation in the end-gas region. Flame acceleration and pressure oscillation were found to be strongly related to the aperture size of the orifice plate. The high amplitudes of pressure oscillations were found to be the results of two combustion mechanisms: the end gas auto-ignition and the interactions between the accelerated turbulent flame and shock wave. To further accelerate the flame and promote stronger disturbance in the end gas, another identical orifice plate was employed. Subsequently, strong flame-shock interaction caused end-gas auto-ignition with an extremely high-amplitude pressure oscillation. Eventually, the maximum amplitude of pressure oscillation exceeded 8 MPa as end-gas auto-ignition occurred in the end region of the combustion chamber.</p

Rational Design of Cancer-Targeted Selenadiazole Derivative as Efficient Radiosensitizer for Precise Cancer Therapy

Chemical drug design based on the biochemical characteristics of cancer cells has become an important strategy for discovery of targeted therapies for personalized cancer medicine. Herein, cancer targeting RGD peptide has been covalently conjugated to selenadiazole derivative (<b>RGD-SeD</b>) to improve its cancer selectivity. The RGD decoration significantly enhances the anticancer efficacy of <b>RGD-SeD</b> in αVβ3 integrin-overexpressing HepG2 liver cancer cells but not in normal liver cells. Cellular uptake assay and fluorescent imaging confirmed the selectivity of <b>RGD-SeD</b> to integrin-overexpressing cancer cells. <b>RGD-SeD</b> strongly sensitizes HepG2 cells to clinically used X-ray radiotherapy through ROS overproduction, which triggers DNA damage-mediated apoptosis and G2/M cell cycle arrest. This X-ray-responsive DNA damage activates p53 signaling pathways by phosphorylation of ATM/ATR and γ-H2A.X. Furthermore, in a HepG2 nude mice xenograft model, the combined treatment of <b>RGD-SeD</b> and X-ray demonstrates potent <i>in vivo</i> antitumor efficacy via induction of apoptotic cell death but shows no toxicity on the functions of major organs. In summary, this study provides a strategy to design a selenium-based cancer targeting radiosensitizer for precise cancer therapy

Experimental investigation of the stochastic nature of end-gas autoignition with detonation development in confined combustion chamber

In the present work, end-gas autoignition formation, and the effects of oxygen concentration on the flame/shock waves propagation and pressure oscillation, are investigated in a self-designed constant-volume chamber equipped with a perforated plate. A hydrogen–oxygen–nitrogen mixture with adjustable oxygen to nitrogen ratio is chosen as the test fuel. In an oxygen-enriched condition, the probability of an end-gas autoignition occurrence increasessignificantly. End-gas autoignition with detonation development is further investigated, with a special emphasis on the stochasticity of the detonation development. In a low-oxygen condition, detonation occurs randomly owing to its stochastic physical behavior. However, when the oxygen concentration increases to 28%, the stochastic factors have a lower impact, and the detonation occurrence is certain. Nevertheless, the pressure and pressure oscillation in the autoignition exhibit random behaviors and are unrelated to the oxygen concentration. The variation tendency of the flame tip velocity remains constant under different oxygen concentrations. However, an increase in the oxygen concentration improves the flame tip velocity, thereby inducing stronger shock waves and promoting autoignition. Based on the start time of the autoignition, two types of autoignition modes were identified: Mode 1 and Mode 2. In Mode 2, the unburnt mixture experiences merely one compression by the shock wave before autoignition and only occurs under high oxygen concentrations of 27%–28%. Under equal oxygen concentrations, the pressure and pressure oscillation of Mode 2 are higher than those of Mode 1 owing to the larger amount 2 of unburnt mixture. Finally, the exhaust gas was introduced into the initial unburnt mixture to investigate the effect of an inert gas on the combustion

Meta-analysis of data for EML4-ALK.

<p>(A smokers vs no-smokers; B adenocarcinomas vs non-adenocarcinomas; C stages I-II vs stages III-IV; D male vs female). Forest plot of the Relative Risk (RR) of the clinicopathological characteristics with <i>EML4-ALK</i> fusion gene patients. The RR estimate of each individual trial corresponds to the middle of the squares and the horizontal line gives the 95% CI. On each line, the numbers of events are represented as fractions of the total number; random choices are shown for both treatment groups. For each subgroup, the sum of the statistics, along with the summary RR are represented by the middle of the solid diamonds. A test of heterogeneity between the trials within a subgroup is given below in summary of the statistics.</p

Clinicopathological Characteristics of Patients with Non-Small-Cell Lung Cancer Who Harbor <i>EML4-ALK</i> Fusion Gene: A Meta-Analysis

<div><p>Background</p><p>A novel fusion gene of echinoderm microtubule-associated protein-like 4 (<i>EML4</i>) and anaplastic lymphoma kinase (<i>ALK</i>) has been recently identified in non-small-cell lung cancers (NSCLCs). Patients with the <i>EML4-ALK</i> fusion gene demonstrate unique clinicopathological and physiological characteristics. Here we present a meta-analysis of large-scale studies to evaluate the clinicopathological characteristics of NSCLC patients harboring the <i>EML4-ALK</i> fusion gene.</p><p>Methods</p><p>Both English and Chinese databases were systematically used to search the materials of the clinicopathological characteristics of patients with NSCLC harboring the <i>EML4-ALK</i> fusion gene. Pooled relative risk (RR) estimates and the 95% confidence intervals (95% CI) were calculated with the fixed or random effect model. Publication bias and chi-square test were also calculated.</p><p>Results</p><p>27 retrospective studies were included in our meta-analysis. These studies included a total of 6950 patients. The incidence rate of <i>EML4-ALK</i> fusion in NSCLC patients was found to be 6.8% (472/6950). The correlation of the <i>EML4-ALK</i> fusion gene and clinicopathological characteristics of NSCLC patients demonstrated a significant difference in smoking status, histological types, stage, and ethnic characteristics. The positive rate of the <i>EML4-ALK</i> fusion gene expression in females were slightly higher than that in males, but not significantly (<i>P</i> = 0.52). In addition, the <i>EML4-ALK</i> fusion gene was mutually exclusive of the <i>EGFR</i> and <i>KRAS</i> mutation genes (<i>P</i> = 0.00).</p><p>Conclusion</p><p>Our pooled analysis revealed that the <i>EML4-ALK</i> fusion gene was observed predominantly in adenocarcinoma, non-smoking and NSCLC patients, especially those diagnosed in the advanced clinical stage of NSCLC. Additionally, the <i>EML4-ALK</i> fusion gene was exclusive of the <i>EGFR</i> and <i>KRAS</i> mutation genes. We surmise that IHC assay is a valuable tool for the prescreening of patients with <i>ALK</i> fusion gene in clinical practice, and FISH assay can be performed as a confirmation method. These insights might be helpful in guiding the appropriate molecular target therapy for NSCLC.</p></div

Short‑, Medium‑, and Long-Chain Chlorinated Paraffins in Wildlife from Paddy Fields in the Yangtze River Delta

Short-chain chlorinated paraffins (SCCPs) were added to Annex A of the Stockholm Convention on Persistent Organic Pollutants in April, 2017. As a consequence of this regulation, increasing production and usage of alternatives, such as medium- and long-chain chlorinated paraffins (MCCPs and LCCPs, respectively), is expected. Little is known about the environmental fate and behavior of MCCPs and LCCPs. In the present study, SCCPs, MCCPs, and LCCPs were analyzed in nine wildlife species from paddy fields in the Yangtze River Delta, China, using atmospheric pressure chemical ionization-quadrupole time-of-flight mass spectrometry. SCCPs, MCCPs, and LCCPs were detected in all samples at concentrations ranging from <91–43 000, 96–33 000, and 14–10 000 ng/g lipid, respectively. Most species contained primarily MCCPs (on average 44%), with the exception of collared scops owl and common cuckoo, in which SCCPs (43%) accumulated to a significantly (i.e., <i>p</i> < 0.05) greater extent than MCCPs (40%). Cl₆ groups were dominant in most species except for yellow weasel and short-tailed mamushi, which contained primarily Cl₇ groups. Principal components analysis, together with CP concentrations and carbon stable isotope analysis showed that habitat and feeding habits were key factors driving CP accumulation and congener group patterns in wildlife. This is the first report of LCCP exposure in wildlife and highlights the need for data on risks associated with CP usage

Comparison of Sedimentary PAHs in the Rivers of Ammer (Germany) and Liangtan (China): Differences between Early- and Newly-Industrialized Countries

As a proxy to trace the impact of anthropogenic activity, sedimentary polycyclic aromatic hydrocarbons (PAHs) are compared between the early industrialized and newly industrialized countries of Germany and China, respectively. Surface sediment samples in the Ammer River of Germany and the Liangtan River of China were collected to compare concentration levels, distribution patterns, and diagnostic plots of sedimentary PAHs. Total concentrations of 16 PAHs in Ammer sediments were significantly higher by a factor of ∼4.5 than those in Liangtan. This contrast agrees with an extensive literature survey of PAH levels found in Chinese versus European sediments. Distribution patterns of PAHs were similar across sites in the Ammer River, whereas they were highly varied in the Liangtan River. Pyrogenic sources dominated in both cases. Strong correlations of the sum of 16 PAHs and PAH groups with TOC contents in the Liangtan River may indicate coemission of PAHs and TOC. Poor correlations of PAHs with TOC in the Ammer River indicate that other factors exert stronger influences. Sedimentary PAHs in the Ammer River are primarily attributed to input of diffuse sources or legacy pollution, while sediments in the Liangtan River are probably affected by ongoing point source emissions. Providing further evidence of a more prolonged anthropogenic influence are the elevated black carbon fractions in sedimentary TOC in the Ammer compared to the Liangtan. This implies that the Liangtan River, like others in newly industrialized regions, still has a chance to avoid legacy pollution of sediment which is widespread in the Ammer River and other European waterways