Study of Gasoline Pre-chamber combustion at Lean Operation

Regulations and other demands to enhance automobile fuel economy are growing increasingly strict to reduce CO2 as a measure to address the issues of global warming. The goal of this study was to enhance the fuel economy in high-load operation of a gasoline engine for hybrid vehicles, which is a useful means of addressing this issue. Technology for achieving lean combustion in high-load operation was studied to realize higher brake thermal efficiency by increasing the ratio of specific heat compared to theoretical air-fuel ratio (stoichiometric) EGR combustion. Issues for applying lean combustion to high-load operation include 1) the increased oxygen molarity results in increased knocking tendency compared to stoichiometric EGR combustion, and 2) increased leanness results in greater combustion variation due to the ignition delay period and the delayed second half of the combustion period. In order to solve these issues at lean operation, several combustion methods are examined on test bench. In this test study, Pre-chamber stratified combustion has an advantage of lean operation performance. Ignitability and high-speed combustion period of pre-chamber combustion was secured by setting the ignition areas inside the pre-chamber to the rich side relative to the total air-fuel ratio (A/F). NOx emissions are an issue for stratified combustion, but NOx emissions can be reduced by setting the pre-chamber A/F to approximately 23 and by making the pre-chamber volume sufficiently small compared to the main combustion chamber volume. Tests were performed using a single-cylinder engine to determine the pre-chamber volume and the diameter and number of jet nozzles. The pre-chamber volume and the diameter and number of jet nozzles were set under the restriction of dP/dθ, which is the index of combustion noise, as the target value or less. This specification realized minimum advance for the best torque (MBT) operation with an A/F of 35 at 2000 rpm, IMEP 810 kPa. The heat release characteristics of prechamber combustion shows that unlike the typical combustion pattern using strong flow, the heat release characteristics have two peaks. The first peak is the flame state wherein the jet flame has spread throughout the entire combustion chamber. This shows that the amount of heat released inside the pre-chamber enabled the flame jets from the jet nozzles to spread within the main combustion chamber. The second peak is the state wherein the unburned gas around the spread jet flames is all burning instantaneously. This combustion state results in rapid and stable combustion during the second half of combustion. This combustion characteristic realized MBT lean combustion in high-load operation. The balance between the compression ratio and the surface volume ratio (S/V) was reviewed to counter the drop in efficiency due to the increased S/V as a result of adding a pre-chamber, and this enabled MBT operation at 2000 rpm, IMEP 870 kPa, A/F 35 with an IMEP variation rate of 1.2 %, a main combustion period of 18 deg, and NOx of 30 ppm. Together with the effects of heat insulation coating inside the pre-chamber, this enhanced the brake thermal efficiency by +2 point compared to stoichiometric EGR combustion

ジゾク セイ シンボウサイドウ アブレーション ゴ ノ サイハツ ヨソク インシ ノ ケントウ : サボウ ケイタイ ・ サ シンジ キノウ ノ ユウヨウ セイ

持続性心房細動に対するカテーテルアブレーション(CA)治療後の再発予測を,術前の心エコー図検査から行い,その有用性について検討した.対象は2011 年1 月からの1 年間,心房細動(AF)に対し,初回CA を施行したAF 連続80 例のうち持続性AF32 例である.CA 前に経胸壁心エコー図検査(TTE)および経食道心エコー図検査(TEE)を施行し,各指標を計測し,術後再発予測因子を検討した.CA 後1 年で14 例(44%)にAF の再発を認めた.再発群は非再発群に比し,左房長径が有意に大きく,左心耳壁運動速度は先端と外側の陰性波計測値が有意に低下していた.多変量解析では左房長径および左心耳先端壁運動速度陰性波(LAAWV apex-d)がCA 後AF 再発の予測因子であった.ROC 曲線にて,左房長径はカットオフ値を58 mmとすると感度92.3%,特異度66.7%,LAAWV apex-d はカットオフ値を9.4 cm/s とすると感度78.6%,特異度83.3%で,両者共CA 後AF の再発を予測し得た.TTE およびTEE からCA 後の再発予測が可能であった.Background:Catheter ablation( CA) of persistent atrial fibrillation (PsAF) has been widely performed. However, echocardiographic predictions for the AF recurrence are not completely understood.Objective:The purpose of this study was to evaluate the value of both the left atrial( LA) longitudinal diameter and left atrial appendage wall velocity (LAAWV) for predicting AF recurrences after CA of PsAF.Methods: We retrospectively analyzed 32 patients with PsAF who had undergone CA. Both the transthoracic and transesophageal echocardiographic parameters, and clinical parameters were assessed.Results:During a one-year follow-up period, 14 patients (44 %) had AF recurrences after a single CA procedure. There was a significant difference in the LA longitudinal diameter (63±3.3 mm vs. 58±5.4 mm;p=0.0029) and LAAWV apex-d (7.9±2.1 cm/s vs. 11.7±3.0 cm/s;p= 0.0003) in the patients with and without AF recurrences. A multivariate analysis revealed that the LA longitudinal diameter (p=0.0247) and LAAWV apex-d (p=0.047) were significant predictors of arrhythmia recurrences. In the receiver operator curve analysis, a longitudinal diameter> 58 mm demonstrated a sensitivity of 92.3 % and specificity of 66.7%, and a LAATDI apex-d of 9.4 cm/s demonstrated a sensitivity of 78.6 % and specificity of 83.3%, in predicting an arrhythmia recurrence.Conclusion:The LA longitudinal diameter and LAAWV could be used as non-invasive pre-procedural predictors of arrhythmia recurrences after single CA procedures in patients with PsAF

Effect of cation addition on silica scale on glass surfaces

Abstract Mineral components in tap water generally contaminate sanitary ware. In this study, various cations (Mg, Ca, and Al) were added to an aqueous solution containing silica to prevent water stains on sanitary ware. The particle size in the aqueous solution was measured and observed to increase for all cations. To create artificial water stains, a solution containing the cations and silica was dropped onto glass and allowed to dry. When these water stains were removed by sliding, the removal rate was higher for the water stains that contained the cations. This trend was attributed to the formation of precipitates owing to the reaction of silica with the added cations in the aqueous solution. The formation of these precipitates possibly increased the particle size and brittleness of water stains owing to their sparse structure. These findings provide insights into silica‐scale removal, which can improve the cleanliness of sanitary ware and reduce the frequency of maintenance

A Cell System-Assisted Strategy for Evaluating the Natural Antioxidant-Induced Double-Stranded DNA Break (DSB) Style

Natural antioxidants derived from plants exert various physiological effects, including antitumor effects. However, the molecular mechanisms of each natural antioxidant have not yet been fully elucidated. Identifying the targets of natural antioxidants with antitumor properties in vitro is costly and time-consuming, and the results thus obtained may not reliably reflect in vivo conditions. Therefore, to enhance understanding regarding the antitumor effects of natural antioxidants, we focused on DNA, one of the targets of anticancer drugs, and evaluated whether antioxidants, e.g., sulforaphane, resveratrol, quercetin, kaempferol, and genistein, which exert antitumor effects, induce DNA damage using gene-knockout cell lines derived from human Nalm-6 and HeLa cells pretreated with the DNA-dependent protein kinase inhibitor NU7026. Our results suggested that sulforaphane induces single-strand breaks or DNA strand crosslinks and that quercetin induces double-strand breaks. In contrast, resveratrol showed the ability to exert cytotoxic effects other than DNA damage. Our results also suggested that kaempferol and genistein induce DNA damage via unknown mechanisms. Taken together, the use of this evaluation system facilitates the analysis of the cytotoxic mechanisms of natural antioxidants

In vitro myelination using explant culture of dorsal root ganglia: An efficient tool for analyzing peripheral nerve differentiation and disease modeling.

Peripheral nerves conducting motor and somatosensory signals in vertebrate consist of myelinated and unmyelinated axons. In vitro myelination culture, generated by co-culturing Schwann cells (SCs) and dorsal root ganglion (DRG) neurons, is an indispensable tool for modeling physiological and pathological conditions of the peripheral nervous system (PNS). This technique allows researchers to overexpress or downregulate molecules investigated in neurons or SCs to evaluate the effect of such molecules on myelination. In vitro myelination experiments are usually time-consuming and labor-intensive to perform. Here we report an optimized protocol for in vitro myelination using DRG explant culture. We found that our in vitro myelination using DRG explant (IVMDE) culture not only achieves myelination with higher efficiency than conventional in vitro myelination methods, but also can be used to observe Remak bundle and non-myelinating SCs, which were unrecognizable in conventional methods. Because of these characteristics, IVMDE may be useful in modeling PNS diseases, including Charcot Marie Tooth disease (CMT), in vitro. These results suggest that IVMDE may achieve a condition more similar to peripheral nerve myelination observed during physiological development