[en] To construct an effective method to analyze the combustion process of dual fuel engines at low loads, effects of combustion boundaries on the combustion process of an electronically controlled diesel natural gas dual-fuel engine at low loads were investigated. Three typical combustion modes, including h, m and n, appeared under different combustion boundaries. In addition, the time-sequenced characteristic and the heat release rate-imbalanced characteristic were found in the dual fuel engine combustion process. To quantify these characteristics, two quantitative indicators, including the TSC (time-sequenced coefficient) and the HBC (HRR-balanced coefficient) were defined. The results show that increasing TSC and HBC can decrease HC (hydrocarbon) emissions and improve the BTE (brake thermal efficiency) significantly. The engine with the n combustion mode can obtain the highest BTE and the lowest HC emissions, followed by m, and then h. However, the combustion process of the engine will deteriorate sharply if boundary conditions are not strictly controlled in the n combustion mode. Based on the n combustion mode, advancing the start of diesel injection significantly, using large EGR (exhaust gas recirculation) rate and appropriately intake throttling can effectively reduce HC emissions and improve the BTE of dual fuel engines at low loads with relatively high natural gas PES (percentage energy substitution). - Highlights: • We reported three typical combustion modes of a dual-fuel engine at low loads. • Time-sequenced characteristic was put forward and qualified. • HRR-imbalanced characteristic was put forward and qualified. • Three combustion modes appeared as equivalence ratio/diesel injection timing varied. • The engine performance varied significantly with different combustion mode.

No abstract available

[en] Highlights: • We report the thermal and diluent effects of, EGR gases including CO₂ and N₂. • Ar was introduced to the test to define the diluent effect of EGR gases. • The thermal effect of CO₂ is often larger than the diluent effect on NOx reduction. • The thermal effect of N₂ is often less than the diluent effect on NOx reduction. • Increasing Ar improves the thermal efficiency and decreases NOx emissions. - Abstract: Exhaust gas recirculation (EGR) is one of effective measures used in natural gas (NG) engines to reduce nitrogen oxides (NOx) emissions. Each component of EGR gases can exert different effects on NG combustion and NOx formation rates, such as thermal effect, diluent effect, and chemical effect. In this study, the thermal and diluent effects of the main components of EGR gases, including carbon dioxide (CO₂) and nitrogen (N₂), were experimentally investigated. The experiments were arranged based on an electronically controlled heavy-duty natural gas spark-ignition (SI) engine with multi-point injection and 6-cylinder. In order to define the diluent effect of EGR components, argon (Ar) was introduced to the test, for its low and unchangeable specific heat capacity under different temperatures. The results showed that the contribution of the diluent effect on NOx reductions was 50–60% and 41–53% for N₂ and CO₂ respectively, and the relevant contribution of the thermal effect was 40–50% and 47–59% respectively. CO₂ had greater effects on NG combustion and NOx formation rates than N₂ at the same dilution ratio. Increasing Ar improved the thermal efficiency due to the higher specific heat ratio provided. Meanwhile, NOx emissions were found to be decreased with increasing DR as a result of the diluent effect of Ar on combustion and NOx formations

[en] The PM_2_._5 concentration in 31% of China's territorial areas was less than 10 μg/m"3, and in 26% of China's territorial areas was higher than 35 μg/m"3. High concentrations of PM_2_._5 were found in the East China Plain, Sichuan province, and the Taklimakan desert. East China Plain was also found with strong significant positive trends. 73% of artificial surface (L01) was found with significant positive trends, but only 2% with significant negative trends. 76% of cropland (L02) was observed with significant positive trends, but only 2% with significant negative trends. The mean significant trends of PM_2_._5 concentration were 1.81 μg/m"3·year for L01 and 1.71 μg/m"3·year for L02, higher than that for the rest land covers. The PM_2_._5 pollution brought potential health risk to susceptible population: only 1% of thm lives at a safe level (<10 μg/m"3), but 69% of them were exposed to heavy PM_2_._5 pollution (>35 μg/m"3). - Highlights: • PM_2_._5 concentration in 31% of China's territorial was less than 10 μg/m"3. • PM_2_._5 concentration in 26% of China's territorial was higher than 35 μg/m"3. • Significant increases of PM_2_._5 were observed at 73% urban areas and 76% cropland. • PM_2_._5 increased 1.81 μg/m"3·year at urban areas and 1.71 μg/m"3·year at cropland. • In 2000, 69% susceptible population exposed to heavy PM_2_._5 pollution (>35 μg/m"3). - Significant increases of PM_2_._5 were observed for 73% of artificial surface and 76% of cropland, with PM_2_._5 increasing 1.81 μg/m"3·year and 1.71 μg/m"3·year respectively.

[en] Highlights: • We defined 7 effects of excess air and quantitative indicators on NOx emissions. • Contributions of N_2, O_2 and Ar on the thermal effect are separately 85%, 14% and 1%. • Contributions of N_2 and Ar on the dilution effect are 98.8% and 1.2%, respectively. • The high level of N_2 in air is the main reason why NOx emissions decrease with λ. - Abstract: This paper presents the effects of N_2, O_2 and Ar in excess air on combustion and NOx emissions of a natural gas spark-ignition engine. Based on Arrhenius Law and Zeldovich Mechanism, seven different kinds of effects were defined as well as their quantitative indicators. Excess air and N_2 were separately added into the intake charge with fuel remaining unchanged in a 6-cylinder turbocharged natural gas engine. The results show that the essential reason why NOx emissions vary with increasing excess air ratio (λ) is that the oxidation effect of O_2 varies with the in-cylinder temperature, which is controlled by the thermal effect of excess air. The contributions of N_2, O_2 and Ar on the thermal effect are 82.6–86.1%, 13.3–16.7% and 0.6–0.7%, respectively. The chemical effect of O_2 is fully offset by the dilution effect of N_2 and Ar. The contributions of N_2 and Ar on the dilution effect are 98.31% and 1.69%, respectively. The increase of NOx emissions caused by O_2 is found to be increased first and then decreased with increasing λ. From the view of the composition of air, the high level of N_2 is the main reason why NOx emissions decrease significantly with increasing λ

[en] Diethanol-isopropanolamine (DEIPA) is a tertiary alkanolamine used in the formulation of cement grinding-aid additives and concrete early-strength agents. In this research, isothermal calorimetry was used to study the hydration kinetics of Portland cement with DEIPA. A combination of X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC)–thermogravimetric (TG) analysis and micro-Raman spectroscopy was used to investigate the phase development in the process of hydration. Mercury intrusion porosimetry was used to study the pore size distribution and porosity. The results indicate that DEIPA promotes the formation of ettringite (AFt) and enhances the second hydration rate of the aluminate and ferrite phases, the transformation of AFt into monosulfoaluminate (AFm) and the formation of microcrystalline portlandite (CH) at early stages. At later stages, DEIPA accelerates the hydration of alite and reduces the pore size and porosity

[en] A pulse constant-current source based on capacitor discharge was developed for LIA accelerator. Theoretic analysis and simulation for this source was proceeded. Numerical simulation has consistent result with experiment. The experiment result shows that this kind of source can work in pulse and its input power has reduced greatly. When the output current is 500 A and current duration is 0.3 s, this source has an output current of 0.2%, input power of 400 W and output power of 25 kW. This kind of source is very suitable for LIA. (authors)

[en] A novel method of atomistic modelling and characterization of both pure ceramide and mixed lipid bilayers is being developed, using only the General Amber ForceField. Lipid bilayers modelled as pure ceramides adopt hexagonal packing after equilibration, and the area per lipid and bilayer thickness are consistent with previously reported theoretical results. Mixed lipid bilayers are modelled as a combination of ceramides, cholesterol, and free fatty acids. This model is shown to be stable after equilibration. Green tea extract, also known as epigallocatechin-3-gallate, is introduced as a spherical cluster on the surface of the mixed lipid bilayer. It is demonstrated that the cluster is able to bind to the bilayers as a cluster without diffusing into the surrounding water

[en] Objective: To evaluate susceptibility-weighted imaging for diagnosing developmental venous anomaly (DVA). Methods: The conventional MRI (30), SWI (30) and MRV (10) of 30 patients with diagnosis of DVA on MRI were retrospectively analyzed. Results: On unenhanced MRI draining veins were clearly demonstrated as hypointensity on T₁WI and T₂WI in 3 cases, hypointensity on T₁WI and hyperintensity on T₂WI in 5 cases. In 22 patients the draining veins were not seen. MRV showed the draining veins in all 10 patients. On contrast-enhanced MRI, medullary and draining veins were enhanced with the characteristic hyperintense caput medusa appearance. Hypointense caput medusa pattern was visible on SWI. Conclusions: The draining veins of DVA were not well shown on conventional MRI but clearly demonstrated on contrast-enhanced MRI and SWI. More medullary veins are visible on SWI, which is valuable for diagnosing DVA. (authors)

[en] Excessive alcohol consumption can lead to gastric ulcer and the present work was aimed to examine the protective effect of tetrahydrocoptisine (THC) in the model of ethanol-induced gastric ulcer in mice. Fasted mice treated with ethanol 75% (0.5 ml/100 g) were pre-treated with THC (10 or 20 mg/kg, ip), cimetidine (100 mg/kg, ip) or saline in different experimental sets for a period of 3 days, and animals were euthanized 4 h after ethanol ingestion. Gross and microscopic lesions, immunological and biochemical parameters were taken into consideration. The results showed that ethanol induced gastric damage, improving nitric oxide (NO) level, increased pro-inflammatory cytokine (TNF-α and IL-6) levels and myeloperoxidase (MPO) activity, as well as the expression of nuclear factor-κB (NF-κB) in the ethanol group. Pretreatment of THC at doses of 10 and 20 mg/kg bodyweight significantly attenuated the gastric lesions as compared to the ethanol group. These results suggest that the gastroprotective activity of THC is attributed to reducing NO production and adjusting the pro-inflammatory cytokine, inhibited neutrophil accumulation and NF-κB expression. - Highlights: • THC decreased ethanol-induced pro-inflammatory cytokine release. • THC inhibited the production of NO in serum and gastric tissue. • THC reduced NF-κB expression and MPO accumulation in ethanol-induced gastric tissue