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Colorectal cancer is diagnosed as the third most prevalent cancer; thus, effective therapeutic agents are urgently required. In this study, we synthesized six homoisoflavane derivatives of cremastranone and investigated their cytotoxic effects on the human colorectal cancer cell lines HCT116 and LoVo. We further examined the related mechanisms of action using two of the potent compounds, SH-19027 and SHA-035. They substantially reduced the cell viability and proliferation in a dose-dependent manner. Treatment with SH-19027 and SHA-035 induced cell cycle arrest at the G2/M phase and increased expression of p21 both of which are implicated in cell cycle control. In addition, the apoptotic cell population and apoptosis-associated marker expression were accordingly increased. These results suggest that the synthesized cremastranone derivatives have anticancer effects through the suppression of cell proliferation and induction of apoptosis. Therefore, the synthesized cremastranone derivatives could be applied as novel therapeutic agents against colorectal cancer.

Dracaeconolide B (

Homoisoflavonoids are in the subclass of the larger family of flavonoids but have one more alkyl carbon than flavonoids. Among them, 5,7,8-trioxygenated homoisoflavonoids have not been extensively studied for synthesis and biological evaluation. Our current objective is to synthesize 2 5,7,8-trioxygenated chroman-4-ones and 12 5,7,8-trioxygenated homoisoflavonoids that have been isolated from the plants Bellevalia eigii, Drimiopsis maculata, Ledebouria graminifolia, Eucomis autumnalis, Eucomis punctata, Eucomis pallidiflora, Chionodoxa luciliae, Muscari comosum, and Dracaena cochinchinensis. For this purpose, 1,3,4,5-tetramethoxybenzene and 4′-benzyloxy-2′,3′-dimethoxy-6′-hydroxyacetophenone were used as starting materials. Asymmetric transfer hydrogenation using Noyori’s Ru catalyst provided 5,7,8-trioxygenated-3-benzylchroman-4-ones with R-configuration in high yield and enantiomeric excess. By selective deprotection of homoisoflavonoids using BCl3, the total synthesis of natural products including 10 first syntheses and three asymmetric syntheses has been completed, and three isomers of the reported dracaeconolide B could be provided. Our research on 5,7,8-trioxygenated homoisoflavonoids would be useful for the synthesis of related natural products and pharmacological applications.

The zero field 53Cr nuclear magnetic resonance was measured at low temperatures to investigate the interactions in the bond-frustrated S = 3/2 Heisenberg helimagnet ZnCr2Se4. A quadratic decrease of the sublattice magnetization was determined from the temperature dependence of the isotropic hyperfine field. We calculated the magnetization using linear spin wave theory for the incommensurate spiral spin order and compared this outcome with experimental results to estimate the coupling constants. The hyperfine fields at Cr and Se ions provide evidences that the spin polarization of Cr ions is transferred to neighboring Se ions due to the covalent bonding between them, resulting in reduced magnetic moment in the Cr ion. This observation indicates that the Jahn-Teller effect, which leads to distortion inducing spin-lattice coupling, is not completely missing in ZnCr2Se4.

Euro 6 standards impose stringent nitrogen oxide (NOx) emission limits on diesel cars. NOx emissions are significantly different between Euro 6 diesel cars and the previous standards in real-world driving. In this research, the NOx concentrations of Euro 6 diesel engines during real-world driving were studied considering various factors. Real driving emission (RDE) tests were conducted using vehicles equipped with portable emissions measurement systems. Urban, rural, and motorway test routes were utilized. Road environment, atmospheric, and after-treatment performance factors were collected in each case. An artificial neural network was used for evaluation using RDE test data and various statistical parameters. It was found that the proposed method predicted the pollutant emissions effectively. Lastly, the relative importance of each predictor was derived, and the NOx concentrations were analyzed. These approaches provide accurate emission information for an environmental effect evaluation that reflects more realistic road conditions.

Activity of the heme synthesis enzyme ferrochelatase (FECH) is implicated in multiple diseases. In particular, it is a mediator of neovascularization in the eye and thus an appealing therapeutic target for preventing blindness. However, no drug-like direct FECH inhibitors are known. Here, we set out to identify small molecule inhibitors of FECH as potential therapeutic leads using a high throughput screening approach to identify potent inhibitors of FECH activity. A structure-activity relationship study of a class of triazolopyrimidinone hits yielded drug-like FECH inhibitors. These compounds inhibit FECH in cells, bind the active site in cocrystal structures, and are anti-angiogenic in multiple in vitro assays. One of these promising compounds was anti-angiogenic in vivo in a mouse model of choroidal neovascularization. This foundational work may be the basis for new therapeutic agents to combat not only ocular neovascularization, but also other diseases characterized by FECH activity.

This study used emission certification data for vehicles that met Korea's Euro-6 emission standards after 2018. It was analyzed that the distribution of nitrogen oxide (NOX) emission in accordance with the type of after-treatment system under cold and hot start conditions by classifying domestic and imported cars. In addition, the relationship between electronic control unit (ECU)/dosing control unit (DCU) signals and exhaust emissions were analyzed under NEDC and WLTP driving mode conditions. Three models of vehicles equipped with different after-treatment systems were selected among the vehicles subject to the 2019 real road driving test for this study. And it was acquired that ECU and DCU signals, which are expected to be related to emissions as well as emissions. In order to satisfy Euro-6, the LNT + SCR after-treatment system was applied to more than 76% of vehicle models. Among ECU signals, there was a direct relationship between the accelerator pedal and the EGR valve opening degree, and there was a deviation depending on the driving mode. Among the DCU signals, the catalyst temperature, urea-water injection quantity, and injection timing are controlled in accordance with the NOX emission measured by the sensor. In the future, it is necessary to analyze the correlation between the ECU signal and the DCU signal to derive a factor that can be used as a measure to suspect defeat devices.

Increasingly strict emissions standards are providing a major impetus to vehicle manufactures for developing advanced powertrain and after-treatment systems that can significantly reduce real driving emissions. The knowledge of the gaseous emissions from diesel engines under steady-state operation and under transient operation provides substantial information to analyze real driving emissions of diesel vehicles. While there are noteworthy advances in the assessment of road vehicle emissions from real driving and laboratory measurements, detailed information on real driving gaseous emissions are required in order to predict effectively the real-time gaseous emissions from a diesel vehicle under realistic driving conditions. In this work, experiments were performed to characterize the behavior of NOx, unburned HC, CO, and CO2 emitted from light-duty diesel vehicles that comply with Euro 6 emissions standards. The driving route fully reflected various real-world driving conditions such as urban, rural, and highway. The real-time emission measurements were conducted with a Portable Emissions Measurement System (PEMS) including a Global Positioning System (GPS). To investigate the gaseous emission characteristics, authors determined the road load coefficients of vehicle specific power (VSP) and regression coefficient between fuel use rate and VSP. Furthermore, this work revealed the correlation between the rates of average fuel use and each gaseous emission.

Advanced nitrogen oxides (NOx) after-treatment systems for diesel cars are effectively reducing tailpipe NOx emissions in laboratory test cycles; however, some de-NOx systems showed limitation for passing environmental standards during real-world driving conditions. In this study, the NOx concentration of a lean NOx trap (LNT)-equipped diesel engine were investigated over various vehicle certification cycles. The LNT performance was compared to the new European driving cycle (NEDC), world-harmonized light-duty vehicle test cycle (WLTC), federal test procedure (FTP)-75, highway fuel economy test (HWFET), and US06. The real-time NOx concentration behaviors were tracked using NOx sensors at the engine-out and downstream of the LNT to determine the NOx storage and regeneration phase. The NOx conversion efficiencies were 36.3–71.7% of which reflecting the mode severity and cycle duration of the diesel engine. The tailpipe NOx emissions were 0.059 g/km during the NEDC which was within the Euro-6 emissions regulations. The NOx emissions in the WLTC, FTP-75, and US06 modes were approximately 1.9, 1.5, and 6.6 times higher than the NEDC due to the higher frequency of LNT purge and higher engine-out NOx formation. During the diesel particulate filter (DPF) regenerating stage in WLTC mode, tailpipe NOx emissions substantially increased by more than 8.8-fold. The exhaust gas recirculation (EGR) supply and lambda control scheme were closely related with strong NOx increment at de-NOx and de-PM processes.

In this research, we tailor the phonon density of states (DOS) in thin superconducting films to suppress quasiparticle losses. We examine a model system of a proximity-enhanced three-layered Al/Nb/Al heterostructure and show that the local quantized phonon spectrum of the ultrathin Al cladding layers in the heterostructure has a pronounced effect on the superconducting resonator’s quality factors. Instead of a monotonic increase of quality factors with decreasing temperatures, we observe the quality factor reaches a maximum at 1.2 K in 5/50/5 nm Al/Nb/Al microstrip resonators, because of a quantized phonon ladder. The phonon DOS may be engineered to enhance the performance of quantum devices.

Emission characterization of particle number as well as particle mass from three diesel passenger cars equipped with diesel particulate filter (DPF), diesel oxidation catalyst (DOC) and exhaust gas recirculation (EGR) under the vehicle driving cycles and regulatory cycle. Total particle number emissions (PNEs) decreased gradually during speed-up of vehicle from 17.3 to 97.3km/hr. As the average vehicle speed increases, the size-segregated peak of particle number concentration shifts to smaller size ranges of particles. The correlation analysis with various particulate components such as particle number concentration (PNC), ultrafine particle number concentration (UFPNC) and particulate matter (PM) mass was conducted to compare gaseous compounds (CO, CO2, HC and NOx). The UFPNC and PM were not only emitted highly in Seoul during severe traffic jam conditions, but also have good correlation with hydrocarbons and NOx influencing high potential on secondary aerosol generation. The effect of the dilution temperature on total PNC under the New European Driving Cycle (NEDC), was slightly higher than the dilution ratio. In addition, the nuclei mode (DP: ≤13nm) was confirmed to be more sensitive to the dilution temperature rather than other particle size ranges. Comparison with particle composition between vehicle speed cycles and regulatory cycle showed that sulfate was slightly increased at regulatory cycle, while other components were relatively similar. During cold start test, semivolatile nucleation particles were increased due to effect of cold environment. Research on particle formation dependent on dilution conditions of diesel passenger cars under the NEDC is important to verify impact on vehicular traffic and secondary aerosol formation in Seoul.

Euro 6-compliant diesel passenger cars have tended to feature lean NO x traps (LNTs) to satisfy the increasingly stringent NO x regulations. This paper focused on NO x emission characteristics by the NO x sensors installed at both before and after LNT from a Euro 6 diesel vehicle on a chassis dynamometer. The vehicle was repeatedly driven according to the new European driving cycle (NEDC) and the world-harmonized light-duty vehicle test cycle (WLTC) at various ambient temperatures (23, 14 and −5 °C). LNT regeneration was detected twice in the NEDC but 5 times in the WLTC due to the longer period, increased mileage and more frequent acceleration in the WLTC. Accordingly, the NO x conversion rate was higher, and the NO x emission factor was lower for the NEDC than for the WLTC. Additionally, as the ambient temperature decreased, the NO x concentration increased considerably. Because of the poor mixing of fuel and air and the reduced combustion efficiency and stability, the exhaust gas recirculation (EGR) rates decreased. Because the LNT did not reach the light-off temperature (LOT) in the cold start phase, the chemical reactions in the LNT did not occur, and only NO was detected. For the LNT regeneration process, the EGR rates decreased, and the fuel rates increased to release the stored NO x in the LNT. The emissions characteristics of the products, such as NO, NO 2 , N 2 O and NH 3 , during regeneration varied depending on the stored NO x , the after-treatment temperature, and the vehicle driving condition. The results from this comparative study can contribute to monitoring the NO x emission characteristics and optimizing the engine management system to meet future emission regulations including WLTC and low ambient temperature conditions.

This paper presents the on-road nitrogen oxides (NOx) emissions measurements from Euro 6 light-duty diesel vehicles using a portable emissions measurement system on the predesigned test routes in the metropolitan area of Seoul, Korea. Six diesel vehicles were tested and the NOx emissions results were analyzed according to the driving routes, driving conditions, data analysis methods, and ambient temperatures. Total NOx emissions for route 1, which has higher driving severity than route 2, differed by -4-60% from those for route 2. The NOx emissions when the air conditioner (AC) was used were higher by 68% and 85%, on average, for routes 1 and 2, respectively, compared to when the AC was not used. The analytical results for NOx emissions by the moving averaging window method were higher by 2-31% compared to the power binning method. NOx emissions at lower ambient temperatures (0-5°C) were higher by 82-192% compared to those at higher ambient temperatures (15-20°C). This result shows that performance improvements of exhaust gas recirculation and the NOx after-treatment system will be needed at lower ambient temperatures.

Neovascular eye diseases are a major cause of blindness. Excessive angiogenesis is a feature of several conditions, including wet age-related macular degeneration, proliferative diabetic retinopathy, and retinopathy of prematurity. Development of novel anti-angiogenic small molecules for the treatment of neovascular eye disease is essential to provide new therapeutic leads for these diseases. We have previously reported the therapeutic potential of anti-angiogenic homoisoflavanone derivatives with efficacy in retinal and choroidal neovascularization models, although these are racemic compounds due to the C3-stereogenic center in the molecules. This work presents asymmetric synthesis and structural determination of anti-angiogenic homoisoflavanones and pharmacological characterization of the stereoisomers. We describe an enantioselective synthesis of homoisoflavanones by virtue of ruthenium-catalyzed asymmetric transfer hydrogenation accompanying dynamic kinetic resolution, providing a basis for the further development of these compounds into novel experimental therapeutics for neovascular eye diseases.

In this Tutorial, we introduce basic conceptual elements to understand and build a gate-based superconducting quantum computing system.

This study was conducted in order to estimate the exhaust emissions analysis method of the real driving emission(RDE). The Association for Emissions Control by Catalyst(AECC) has developed a test procedure by using a random cycle method based on the chassis dynamometer. In order to confirm this approach in Korea, Euro 5(DPF), Euro 6(DPF + LNT), and Euro 6(DPF + SCR) were performed on three different vehicles to determine the exhaust gas characteristics of the random cycle, real-road driving test(PEMS), and emission certification driving mode(NEDC). Six different random cycle driving modes were generated by the vehicle specifications(e.g. curb weight, engine power, gear ratio, and maximum acceleration). The NOx emissions were increased in the NEDC, random cycle, and PEMS order in this study regardless of the test vehicles. The random cycle method has the advantage because it utilizes a chassis dynamometer in the laboratories for a repeatable data collection, and it allows any eminent emission improvement checked prior to a real-road driving test with PEMS.

The number of investigation on the fuel efficiency and the emission characteristics of diesel vehicles under steady-state operation and under transient operation has been carried out, and the knowledge obtained from these research provides substantial information to analyze real driving emissions of diesel vehicles. Detailed information on the fuel use and the emission under the real driving condition, however, are still required in order to provide substantial information to analyze and predict the fuel use and gaseous emissions from a diesel vehicle driving various real-world conditions. This work aims to characterize the fuel use and the gaseous emissions such as NOx, unburned HC, CO, and CO2 from light-duty diesel vehicles, complying with Euro 6b emissions standards, driving the route fully reflected various real-world driving conditions. The experiment was carried out with a Portable Emissions Measurement System (PEMS) including a Global Positioning System (GPS). We evaluated the fuel used and the overall gaseous emissions in various road conditions, and the vehicle specific powers (VSPs) with determining the road load coefficients and regression coefficient by multiple linear regression analysis. Furthermore, this work also revealed the fuel use and the emissions per VSP of vehicles in these six different conditions.

The purpose of this study is evaluate emission characteristics, such as nitrogen oxides (NOx), hydrocarbon, carbon monoxide, and particulate matter (PM), of excavator with Tier-4f level diesel engine in the real work conditions. The test excavator has an engine power of 124 kW at an engine speed of 1800rpm, and it has various after-treatment devices, such as exhaust gas recirculation (EGR), selective catalytic reduction (SCR), and diesel oxidation catalyst (DOC), to reduce the engine-out emissions. The emissions including carbon monoxide (CO), carbon dioxides (CO2), and NOx, were measured by portable emission measurement system (PEMS). The PEMS device conducted a correlation analysis with the emission bench on the engine dynamometer before being used to measure the real-work to confirm the reliability of the equipment. The tests were carried out in four categories: idling, driving, excavations and flattening. It revealed that the average power output for each operation mode was higher in the order of flattening, excavation, and drive. On average, those are higher than that for the non-road transient cycle (NRTC) certification mode as 1.5 to 1.9 times. It may be determined that the power output is higher in conditions where there are more boom and bucket movements than the movement of the vehicle itself. In emission analysis, NOx and HC emission in driving mode are higher than other two modes: excavation and flattening. The real time NOx have been low in most test conditions, but large quantities of NOx have been released due to the deactivation of the SCR catalyst during cold start period or immediately after the non-working.

We describe an experimental protocol to characterize magnetic field dependent microwave losses in superconducting niobium microstrip resonators. Our approach provides a unified view that covers two well-known magnetic field dependent loss mechanisms: quasiparticle generation and vortex motion. We find that quasiparticle generation is the dominant loss mechanism for parallel magnetic fields. For perpendicular fields, the dominant loss mechanism is vortex motion or switches from quasiparticle generation to vortex motion, depending on the cooling procedures. In particular, we introduce a plot of the quality factor versus the resonance frequency as a general method for identifying the dominant loss mechanism. We calculate the expected resonance frequency and the quality factor as a function of the magnetic field by modeling the complex resistivity. Key parameters characterizing microwave loss are estimated from comparisons of the observed and expected resonator properties. Based on these key parameters, we find a niobium resonator whose thickness is similar to its penetration depth is the best choice for X-band electron spin resonance applications. Finally, we detect partial release of the Meissner current at the vortex penetration field, suggesting that the interaction between vortices and the Meissner current near the edges is essential to understand the magnetic field dependence of the resonator properties.

The Fe

* Korea Automotive Technology Institute** Transportation Pollution Research Center, National Institute of Environmental Research*** Dept. of Energy System Engineering, Korea Nat’l Univ. of Transportation**** Dept. of Mechanical Convergence Engineering, Hanyang Univ. (Received June 11, 2015 ; Revised September 18, 2015 ; Accepted November 18, 2015)Key Words: Portable Emissions Measurement System(PEMS, 이동식 배기가스 측정장치), Real Driving Emissions(RDE, 실제도로 주행 배기가스), Moving Averaging Window(MAW, 이동평균구간), Weighted emissions(가중평균 배출량)초록: PEMS(Portable Emissions Measurement System)를 이용한 배기가스 시험절차는 소형 디젤자동차의 실제도로 배출가스를 효과적으로 제어하기 위한 수단으로 최근에 많은 주목을 받고 있으며, 현재의 배기가스 인증규제 시험절차의 제도적 보완장치로 2017년에 한국과 유럽에서 시행될 예정이다. 본 연구에서는 국내에 운행 중인 유로 5 소형 디젤자동차 4대에 대한 실제도로 NOx 배출량을 도심, 교외 및 자동차 전용도로에서 측정하였으며, 측정 결과를 이동평균구간 및 가중평균 배출량 방법으로 분석하였다. 시험 차량 및 주행경로에 대한 두 방법의 실제도로 NOx 배출량 분석결과는 유사한 경향을 갖는 것으로 나타났으며, 이동평균구간 분석방법의 경우 배출 허용기준을 1.8~8.5배, 가중평균 배출량은 허용기준을 2.0~10.6배 초과하는 것으로 분석되었다. 본 결과를 바탕으로 실도로 주행 조건에서 NOx 배출량 분석에 대한 기술적 토대를 확보하였고, 향후 배출가스 관리를 위한 정책적 기반 데이터로 활용가능하다.Abstract: Recently, an emission test procedure using a portable emissions measurement system(PEMS) has received much attention as an effective means of controlling real driving emissions from light-duty diesel vehicles. The PEMS-based test procedure will be implemented from 2017 in Europe and Korea as a complementary test procedure for certification and regulation. In the present study, on-road NOx emissions were measured for four kinds of Euro 5 Korean light-duty diesel vehicles under real driving conditions, including urban, rural, and motorway test routes. The real driving emission characteristics were evaluated using both a moving averaging window(MAW) and the weighted emission method(WEM). The evaluated NOx emission results (under real driving conditions) from the MAW and WEM showed similar tendencies for the test vehicles and routes, while exceeding the certification emission limit by 1.8~8.5 and 2.0~10.6 times, respectively.

This study explores the carbon dioxide (CO2) emissions reduction potential of passenger vehicles in Republic of Korea, by assuming a number of CO2 reduction routes. Historical data pertaining to important factors affecting the CO2 emissions of passenger vehicles, such as the number of registered vehicles, annual mileage, and average CO2 emissions per vehicle, were analyzed to predict the extent by which these factors would change in 2020. The results show that the total CO2 emissions from passenger vehicles in 2015 would be approximately 37.1 Mton, assuming automobile manufacturers will meet the regulations for CO2 emissions reductions for 2015. The CO2 emissions reduction route is determined in accordance with a hypothetical regulation for CO2 emissions reductions in 2020. If the CO2 emissions rates of new passenger vehicles are reduced by 3–7% per year after complying with the 2015 regulation, then total CO2 emissions and required energy would be approximately 36.5–38.6 Mton and 12.9–13.6 Mtoe, respectively. Also, if the current fuel economy competition persists until 2020, the CO2 emissions reductions will follow the plausible reduction route and consequently reach 35.1 Mton CO2 and 12.4 Mtoe energy in 2020. As a result, in order to reduce the total CO2 emissions of passenger vehicles in 2020 (compared with 2015), the value of regulated CO2 emissions in 2020 should be set to less than 103 g/km per passenger vehicle.

In this work, we find that Al cladding on Nb microstrip resonators is an efficient way to suppress nonlinear responses induced by local Joule heating, resulting in improved microwave power handling capability. This improvement is likely due to the proximity effect between the Al and the Nb layers. The proximity effect is found to be controllable by tuning the thickness of the Al layer. We show that improving the film quality is also helpful as it enhances the microwave critical current density, but it cannot eliminate the local heating.

The objective of this study is to quantify the differences in NO(x) emissions between standard and non-standard driving and vehicle operating conditions, and to estimate by how much NO(x) emissions exceed the legislative emission limits under typical Korean road traffic conditions. Twelve Euro 3-5 light-duty diesel vehicles (LDDVs) manufactured in Korea were driven on a chassis dynamometer over the standard New European Driving Cycle (NEDC) and a representative Korean on-road driving cycle (KDC). NO(x) emissions, average speeds and accelerations were calculated for each 1-km trip segment, so called averaging windows. The results suggest that the NO(x) emissions of the tested vehicles are more susceptible to variations in the driving cycles than to those in the operating conditions. Even under comparable operating conditions, the NO(x) control capabilities of vehicles differ from each other, i.e., NO(x) control is weaker for the KDC than for the NEDC. The NO(x) emissions over the KDC for given vehicle operating conditions exceed those over the NEDC by more than a factor of 8. Consequently, on-road NO(x) emission factors are estimated here to exceed the Euro 5 emission limit by up to a factor of 8, 4 and 3 for typical Korean urban, rural, and motorway road traffic conditions, respectively. Our findings support the development of technical regulations for supplementary real-world emission tests for emission certification and the corresponding research actions taken by automotive industries.

This paper presents the on-road nitrogen oxides (NO

The unintended influence of exhaust plumes emitted from a vehicle ahead to on-road air quality surveying data measured with a mobile laboratory (ML) at 20–40 km h −1 in dense traffic areas was investigated by experiment and life-sized computational fluidic dynamics (CFD) simulation. The ML equipped with variable sampling inlets of five columns by four rows was used to measure the spatial distribution of CO 2 and NO x concentrations when following 5–20 m behind a sport utility vehicle (SUV) as an emitter vehicle equipped with a portable emission monitoring system (PEMS). The PEMS measured exhaust gases at the tailpipe for input data of the CFD simulations. After the CFD method was verified with experimental results of the SUV, dispersion of exhaust plumes emitted from a bus and a sedan was numerically analyzed. More dilution of the exhaust plume was observed at higher vehicle speeds, probably because of eddy diffusion that was proportional to turbulent kinetic energy and vehicle speed. The CO 2 and NO x concentrations behind the emitter vehicle showed less overestimation as both the distance between the two vehicles and their background concentrations increased. If the height of the ML inlet is lower than 2 m and the ML travels within 20 m behind a SUV and a sedan ahead at 20 km h −1 , the overestimation should be considered by as much as 200 ppb in NO x and 80 ppm in CO 2 . Following a bus should be avoided if possible, because effect of exhaust plumes from a bus ahead could not be negligible even when the distance between the bus and the ML with the inlet height of 2 m, was more than 40 m. Recommendations are provided to avoid the unintended influence of exhaust plumes from vehicles ahead of the ML during on-road measurement in urban dense traffic conditions.

This study was primarily focused on the experimental comparison of the particle emission characteristics for heavy duty engine. PM and particle number from various heavy duty engines and DPF type were analyzed with a golden particle measurement system recommended by the Particle Measurement Program. And the repeatability and reproducibility between test mode was analyzed. This study was conducted for the experimental comparison on particulate emission characteristics between the European and World-Harmonized test cycles for a heavy-duty diesel engine. To verify the particulate mass and particle number concentrations from various operating modes, ETC/ESC and WHTC/WHSC, both of which will be enacted in Euro VI emission legislation, were evaluated. Real-time particle formation of the transient cycles ETC and WHTC were strongly correlated with engine operating conditions and after-treatment device temperature. A higher particle number concentration during the ESC mode was ascribed to passive DPF regeneration and the thermal release of low volatile particles at high exhaust temperature conditions.

This investigation focused on the particle emission characteristics of a heavy-duty diesel engine and the effects of after-treatment systems such as diesel particulate filter and selective catalytic reduction. The test engine was operated on the worldwide harmonized transient cycle mode, which is a new transient cycle for Euro 6, and the conventional European transient cycle mode. Four combinations of after-treatment systems, engine-out, selective catalytic reduction, diesel particulate filter, and diesel particulate and nitrogen oxide reduction, were evaluated for the transient cycles, respectively. The whole test procedure, as part of the Korea particulate measurement programme and the inter laboratory correlation exercise for domestic heavy-duty diesel engines, complied with the recommended method of particulate measurement programme. The particles that were extracted through the golden particle measurement system the constant volume sampler tunnel consisted of solid particles like carbonaceous fraction, metal ash, etc. The particles emitted from the tail-pipe, as analyzed by the differential mobility spectrometer, included volatile or soluble particles like sulphate fraction, nitrate fraction, and organic fraction. The test results showed that the particle number and size distribution depended on the catalytic activity or filtration efficiency of the after-treatment system. Compared to the accumulation mode, the nucleation mode was easily caught or oxidized by the after-treatment system. Additionally, the nucleation mode was sharply increased by excessive ammonia injection because nitrogen dioxide-assisted diesel particulate filter regeneration resulted in reduced conversion efficiency of the selective catalytic reduction.

An experimental investigation was performed to investigate the effect of a split-injection strategy on the combustion and exhaust emission characteristics as well as on the particle number distribution for a single-cylinder compression ignition engine with gasoline–dimethyl ether dual fuelling. The gasoline–dimethyl ether dual-fuel injection system utilized port injection for gasoline and direct injection for dimethyl ether. In the present system, premixed fuel (i.e. gasoline) was injected into the premixing chamber at an injection pressure of 3 MPa using gasoline direct injection to mix the air–gasoline mixture sufficiently. However, dimethyl ether fuel was injected at an injection pressure of 50 MPa directly into a combustion chamber in order to control the combustion phase, resulting in a change in the direct-injection timing from −20° to +2° crank angle. The experimental results show that the gasoline–dimethyl ether dual-fuel engine exhibited benefits in the indicated mean effective pressure for early-injection cases (i.e. near −10° crank angle after top dead centre). However, the indicated mean effective pressure of the gasoline–dimethyl ether dual-fuel engine deteriorated for delayed-injection cases owing to incomplete combustion. In addition, a significant reduction in the nitrogen oxide emissions was observed using gasoline–dimethyl ether dual fuel compared with those obtained using conventional dimethyl ether combustion. In particular, soot emissions are almost at zero level for all the cases. On the other hand, hydrocarbon and carbon dioxide emissions increase with an increasing portion of premixed injection fuel (i.e. gasoline) in conventional injection timing, which is near top dead centre.

Time-resolved nanoparticle number concentrations and size distribution characteristics were investigated in gasoline direct-injection vehicles, according to fuel preparation methods. Particle number emissions were measured using the golden particle measurement system recommended by the Particle Measurement Programme, and the particle size spectrum was determined using a DMS500 spectrometer installed at the tailpipe of the vehicles. The wall-guided gasoline direct-injection vehicle exhibited the most temperature-dependent nanoparticulate matter exhaust characteristics, owing to direct accumulation of fuel on the piston head and cylinder liner and a high concentration of accumulation mode particles. The air-guided gasoline direct-injection vehicle emitted particle emissions mostly during cold transient driving conditions and high acceleration, which had a weak trimodal characteristic with evenly distributed nucleation and accumulation mode particles. The spray-guided gasoline direct-injection vehicle continuously discharged 105 particles/cm3 during constant-speed driving segments, because of the ultra-lean-burn operation and bulk quenching; particulate matter from the spray-guided gasoline direct-injection vehicle demonstrated a strong bimodal characteristic, spreading over 10–100 nm. The particle number emissions for the gasoline direct-injection vehicles for the New European Driving Cycle test mode were 1.48 × 1012 particles/km, 6.03 × 1011 particles/km and 3.17 × 1012 particles/km for the wall-guided type, the air-guided type and the spray-guided type respectively, and none of these were able to satisfy the proposed particle number regulations for the Euro 6 standard. For gasoline direct-injection vehicles, it should be considered that engine hardware modifications, as well as energy management system calibrations and even the application of the particle filter, may be needed to meet the upcoming particulate matter number regulation.

This study was conducted for the experimental comparison of particulate emission characteristics between the European and World-Harmonized test cycles for a heavy-duty diesel engine as part of the UN/ECE PMP ILCE of the Korea Particulate Measurement Program. To verify the particulate mass and particle number concentrations from various operating modes, ETC/ESC and WHTC/WHSC, were evaluated. Both will be enacted in Euro VI emission legislation. The real-time particle emissions from a Mercedes OM501 heavy-duty golden engine with a catalyst based uncoated golden DPF were measured with CPC and DMS during daily test protocol. Real-time particle formation of the transient cycles ETC and WHTC were strongly correlated with engine operating conditions and after-treatment device temperature. The higher particle number concentration during the ESC #7 to #10 mode was ascribed to passive DPF regeneration and the thermal release of low volatile particles at high exhaust temperature conditions. The detailed average particle number concentration equipped for golden DPF reached approximately 4.783E+11 #/kWh (weighted WHTC), 6.087E+10 #/kWh (WHSC), 4.596E+10 #/kWh (ETC), and 3.389E+12 #/kWh (ESC). Particle masses ranged from 0.0011 g/kWh (WHSC) to 0.0031 g/kWh (ESC). The particle number concentration and mass reduction of DPF reached about 99%, except for an ESC with a reduction of 95%.

Whether the torsional oscillator experiments on helium-4 reveal supersolid behaviour remains debatable, not least because the history of the sample matters. Many inconsistencies across different experiments may be explained by the presence of two hidden phases.

The Fe3+ and Co2+ NMR spectra for Ba0.3Sr1.7Co2(Fe0.96Al0.04)12O22 (BSCFAO) and Ba0.3Sr1.7Co2Fe12O22 (BSCFO) were obtained in a zero magnetic field at a low temperature. We observed change in the enhancement effect of the NMR signals depending on the setting field, which was varied when applied along the b-axis and then turned off before the measurement was taken. The experimental results indicate that the magnetic structure changes from an alternating longitudinal cone to a transverse cone when the setting field is 250 mT. They also show that the spins of Co2+ ions together with those of Fe3+ ions constitute a part of the overall magnetic structure and that the substitution of Al3+ for Fe3+ weakens the magnetic anisotropy within the easy plane. From a comparison of the enhancement factors of the Fe3+ NMR obtained with the RF pulse applied along the a-axis and the c-axis, we found that the magnetic easy plane anisotropy is approximately 16 times greater than the anisotropy within the easy plane. No changes of the NMR spectra were observed under an electric field of 1.2 MV m-1.