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The deposition of ash on a diesel particulate filter (DPF) results in an increase in pressure drop across aftertreatment system, which leads to reduced capacity for soot and an increase in frequency of regeneration to eliminate the soot. To estimate the amount of ash and design a reduction method for the accumulated ash on the DPF, a deeper understanding of the ash generation mechanism is required. Previous studies have found that ash sampled at exhaust manifolds mainly comprises typical metal oxides, whereas ash accumulated on DPFs primarily comprises typical metal sulfates. However, the conversion mechanism from metal oxides to metal sulfates is not well understood. Herein, the formation mechanism of calcium sulfate (CaSO4), which is the main component of ash on DPFs, was investigated using a flow reactor. Calcium oxide (CaO), which is the main component of ash sampled at exhaust manifolds, was made to react with SO2, SO3, O2, and H2O, when passed through a diesel oxidation catalyst. Quantitative analysis of the ash components in the products was performed using high-performance liquid chromatography. The concentrations of SO2, SO3, and H2O during the reaction were analyzed by Fourier-transform infrared spectroscopy. Based on the experimental results, it was found that CaSO4 mainly formed from the reaction of CaO with SO2 and SO3; whereas, H2O inhibited CaSO4 formation owing to the change in physicochemical properties of CaO.

The Real Driving Emissions (RDE) test method has been introduced after 2017 to regulate the vehicle emissions in real-world driving situations by means of on-board emissions measurements. This paper aims to estimate the detailed on-board gaseous emissions from a light-duty direct-injection gasoline vehicle simultaneously using both portable emissions measurement system (PEMS) and sensor-based emissions measurement system (SEMS). Test route is typical urban route and tests environment factors followed the RDE regulation. Carbon dioxide (CO2), carbon monoxide (CO), nitrogen oxides (NOx), and ammonia (NH3) emissions were analyzed according to cold start once and followed by hot start conditions. The mass emissions of gas components were calculated based on the exhaust flowrate obtained from OBD parameters, NH3 emission was calculated based on NO sensor’s data. Two drivers participated in the tests and their emissions difference has been compared. The results indicating cold start caused much more emission than hot start in CO, NOx and NH3; and aggressive driving behavior would cause more emissions. Simultaneous tests gave chances to better combine the advantages of both measurement systems, and figure out the cause of NH3 emission, two different patterns of NH3 emission which depending on cold/hot start method have been found, and the results showed CO emission and catalytic temperature can both be crucial factors to form NH3 in exhaust gas.

Collagen is a major structural protein, and abnormalities in collagen structure can lead to several connective tissue diseases such as osteoporosis. We report the preparation of a collagen sensor using a synthetic peptide as proof of concept for detecting the collagen like peptides. The synthetic peptide 9-fluorenylmethyloxycarbonyl (Fmoc)-(prolyl-prolyl-glycine)

The pressure rise caused by end-gas auto-ignition in spark-ignited engines is discussed using numerical simulation and theoretical approaches. The main objective of this study is to explain the mechanism by which the end-gas expansion during auto-ignition suppresses the pressure rise in spark-ignited engines, and theoretically to demonstrate using asymptotic analysis that the pressure rise depends on the Damköhler number. A one-dimensional direct numerical simulation (DNS) of end-gas auto-ignition is performed, and the modelling assumptions for it are discussed based on the DNS results. The Damköhler number, defined as the acoustic time scale and the characteristic time scale of the chemical reaction, is introduced in the modelling. The end-gas auto-ignition model is solved numerically, and it is shown that the pressure rise increases with the Damköhler number. Additionally, it is shown that the tendency of the pressure rise is due to the balance between the propagation rate of the expansion wave generated in the end gas and the reaction rate at auto-ignition, which varies with the Damköhler number. To derive the analytical solution of the relationship between the pressure rise and Damköhler number, the end-gas auto-ignition model is simplified based on the numerical results. The simplified model for end-gas auto-ignition is then solved using Newton’s method, and the analytical solution of the pressure rise is derived.

The major cytoskeleton protein actin undergoes cyclic transitions between the monomeric G-form and the filamentous F-form, which drive organelle transport and cell motility. This mechanical work is driven by the ATPase activity at the catalytic site in the F-form. For deeper understanding of the actin cellular functions, the reaction mechanism must be elucidated. Here, we show that a single actin molecule is trapped in the F-form by fragmin domain-1 binding and present their crystal structures in the ATP analog-, ADP-Pi-, and ADP-bound forms, at 1.15-Å resolutions. The G-to-F conformational transition shifts the side chains of Gln137 and His161, which relocate four water molecules including W1 (attacking water) and W2 (helping water) to facilitate the hydrolysis. By applying quantum mechanics/molecular mechanics calculations to the structures, we have revealed a consistent and comprehensive reaction path of ATP hydrolysis by the F-form actin. The reaction path consists of four steps: 1) W1 and W2 rotations; 2) P G –O 3B bond cleavage; 3) four concomitant events: W1–PO 3 − formation, OH − and proton cleavage, nucleophilic attack by the OH − against P G , and the abstracted proton transfer; and 4) proton relocation that stabilizes the ADP-Pi–bound F-form actin. The mechanism explains the slow rate of ATP hydrolysis by actin and the irreversibility of the hydrolysis reaction. While the catalytic strategy of actin ATP hydrolysis is essentially the same as those of motor proteins like myosin, the process after the hydrolysis is distinct and discussed in terms of Pi release, F-form destabilization, and global conformational changes.

Offshore manmade structures, termed artificial reefs (e.g., wind farms, oil platforms, and manmade islands), affect the movement and migration of wild migratory marine animals. Certain types of migratory pelagic and benthic fish are known to utilize artificial reefs as feeding areas, for spatial reference (landmarks for their navigation), or as meeting points. However, little is known about the impact of artificial reefs on the migratory behavior of demersal flatfish. The marbled flounder (Pseudopleuronectes yokohamae), an important commercial flatfish species, exhibits seasonal migration between shallow water for spawning in winter and deeper water to avoid high water temperatures in summer. In this study, 39 tagged marbled flounders were released in the shallow water of the inner Osaka Bay area in June 2016, and then actively tracked, predominantly in deeper waters (100–140 m), from a fishing boat every week until mid-September 2016. Our active tracking detected no tagged fish in the deeper waters, whereas 36% of the fish were detected in the shallow water (10–15 m) around an artificial reef (offshore manmade island) at a high water temperature (26 °C). We suggest that a portion of the marbled flounder population did not show seasonal migration but remained in the shallow water around the artificial reef, even though the water temperature was high in summer. We suggest that this is related to the abundant food supply associated with the artificial reef.

Relatively little is known about spinner dolphins in Malaysian waters and the wider Southeast Asian region. This note represents the first known acoustic recording of the species sighted opportunistically in the northern Straits of Malacca. Over a brief 20 min sighting, 46 whistles were recorded and four tonal types were detected, with 54.4% being upsweep whistles. The whistle duration ranged from 36 to 977 ms and the frequency ranged from 6.6 to 23.8 kHz. Fifty-seven click trains with a mean interclick interval of 41.5 ± 19.3 ms were detected. These findings provide a baseline for future regional acoustic research on this species.

Polycyclic aromatic hydrocarbons (PAHs) are important precursors to the formation of soot and are also pollutant emissions from combustion devices, including internal combustion engines. To underst...

Fuel crossover is a crucial issue for polymer electrolyte fuel cells (PEFCs) supplied directly with liquid fuels. Therefore, finding a type of fuel with a low fuel crossover rate is required. In this study, we investigated fuel crossover characteristics for oxymethylene dimethyl ether (OME), which has attracted attention for use in engines, and compared it with methanol. Cell performance tests and exhaust gas analyses showed that fully hydrolyzed OME (h-OME), which consisted of methanol and formaldehyde, yields high cell performance at high fuel concentrations, due to the low fuel crossover rate, compared with a direct methanol fuel cell (DMFC). To clarify a factor suppressing fuel crossover, h-OME's effective diffusion coefficient in the membrane was measured. Although an effective diffusion coefficient for fuels like methanol commonly increases with increased fuel's concentration, h-OME's effective diffusion coefficient decreased with increased fuel concentration, leading to a low fuel crossover rate at high h-OME concentrations.

For hydrogen-based polymer electrolyte fuel cells (PEFCs), water transport control in gas diffusion layers (GDLs) by wettability distribution is useful to suppress the flooding problem. In this study, the water transport of a novel GDL with hydrophilic-hydrophobic patterns was investigated. First, we clarified that the water motion in the hydrophilic GDL with microstructures could be reproduced by the enlarged scale model. The scale model experiment also showed that the same water behavior in hydrophilic GDL can be obtained from Capillary numbers (Ca) in a range of Ca ~ 10−5 to 10−3. As the computational load is inversely proportional to Ca, the computational load could be reduced by 1/100th by using Ca ~ 10−3, which is 100 times higher than PEFC operation (Ca ~ 10−5). Finally, the simulation with Ca ~ 10−3 was performed, and we showed that the GDL with straight region of contact angle 50° minimized the water accumulation.

Time-resolved quantitative measurements of hydrogen peroxide (H2O2) in the low-temperature oxidation of iso-octane in a rapid compression machine have been performed using mid-infrared absorption s...

Interest in polycyclic aromatic hydrocarbons (PAHs) including a functional group in its chemical structure, particularly oxygenated PAHs (OPAHs), has been growing due to the toxicity and wide prese...

Here, we report the discovery of a ParM protein fromClostridium botulinum(CBgs-ParM), which forms a double-stranded polar filament. CBgs-ParM shares many similarities in its basic filament architecture with actin, however, Pi release after nucleotide hydrolysis induces a large lateral strand shift of ~2.5 nm. We identified the ParR (CBgs-ParR) that acts as a nucleation factor in the initial stage of polymerization, similar to ParR fromEscherichia coliplasmid R1. CBgs-ParR also functions as a depolymerization factor, probably by recognizing the structural change in the CBgs-ParM filament after Pi release. Comparison with CBH-ParM, another ParM fromClostridum botulinum, showed that subunit-subunit interacting regions largely differ, preventing co-polymerization, implying a selection pressure in evolution to prevent interference between different ParMRC systems.

MrgD, a member of the Mas-related G protein-coupled receptor (MRGPR) family, has high basal activity for Gi activation. It recognizes endogenous ligands, such as β-alanine, and is involved in pain and itch signaling. The lack of a high-resolution structure for MrgD hinders our understanding of whether its activation is ligand-dependent or constitutive. Here, we report two cryo-EM structures of the MrgD-Gi complex in the β-alanine-bound and apo states at 3.1 Å and 2.8 Å resolution, respectively. These structures show that β-alanine is bound to a shallow pocket at the extracellular domains. The extracellular half of the sixth transmembrane helix undergoes a significant movement and is tightly packed into the third transmembrane helix through hydrophobic residues, creating the active form. Our structures demonstrate a structural basis for the characteristic ligand recognition of MrgD. These findings provide a framework to guide drug designs targeting the MrgD receptor.

In this study, the effects of hydrogen addition on the engine performance were investigated using spark ignition engine fueled gasoline with a compression ratio of 15 at an air excess ratio (λ) of 1.8 and above. At λ = 1.8, the indicated thermal efficiency at the spark timing of the knock limit reached the maximum level under the conditions in which the hydrogen fraction was set to 4% of the heating value of the total fuel. Based on a heat balance analysis, the best hydrogen fraction was found as a balance between the improvement in the burning efficiency and the increase in heat loss. The lean limit was extended when the hydrogen fraction was increased from λ = 1.80 to λ = 2.28. The hydrogen addition achieved the maximum indicated thermal efficiency at spark timing of the knock limit was obtained at λ = 2.04, where the hydrogen fraction was 10%.

To improve the flooding performance of a polymer electrolyte fuel cell (PEFC), the effect of fiber direction of gas diffusion layer (GDL) is investigated by a lattice Boltzmann method (LBM). Because much water is generally accumulated in the GDL under the ribs, transport of the water into the channel is the focus in this report. The results show that the anisotropic GDL with the fibers approximately distributed in the direction perpendicular to the rib reduces the water accumulated in the GDL compared with an isotropic GDL, but the anisotropic GDL with the strongly aligned fibers increases the water accumulation. This is because the water transport in the direction perpendicular to the rib is improved due to the flow along the anisotropic fibers, but the water transport characteristic in the thickness direction deteriorates due to the sharp and narrow pores in case of the strongly aligned fibers. The experiment developed in our previous study demonstrates that the anisotropic GDL with somewhat oriented fibers reduces the water in the GDL. Next, an attempt to improve the water transport is carried out. By the surface treatment reducing the contact angle of the GDL surface, the water accumulated in the anisotropic GDL is reduced.

Recently, polycyclic aromatic hydrocarbons (PAHs) and oxygenated PAHs (OPAHs) have been attracting considerable attention owing to their high toxicity. Understanding their formation mechanism during combustion processes is important to control their emission. However, there are few studies that have quantitatively investigated OPAH formation in the fuel-rich oxidation of hydrocarbons, despite the availability of several studies on PAH formation. In this study, benzofuran and dibenzofuran as OPAHs were quantified in the fuel-rich oxidation of toluene using a flow reactor at atmospheric pressure in a temperature range of 1050-1350 K at equivalence ratios from 3.0 to 12.0 and residence times from 0.2 to 1.5 s. In addition to benzofuran and dibenzofuran, 4 types of monocyclic aromatic hydrocarbons and 19 types of PAHs were also evaluated. The experimental data obtained in this study were compared with those of the ethylene oxidation performed in our previous study. The existing kinetic model for PAH growth was modified based on several theoretical studies to predict the behavior of OPAHs with furan structures. The modified model showed significant improvements in the prediction of benzofuran and dibenzofuran formation. Based on the rate of production and sensitivity analysis using the modified model, the dominant reaction pathways of benzofuran and dibenzofuran were investigated.

Every year, exhaust gas regulations are getting stricter with the intention to solve the average air pollution problem, however, local roadside pollution is still a pressing issue. In order to solve this local roadside pollution problem, it is necessary to evaluate and/or predict “where” and “how much” pollutants such as NOx are emitted. To predict the local roadside pollution, it is necessary to collect emissions data from various kinds of vehicles driving on realworld and analyze them. In recent years, Real Driving Emission regulations using PEMS (Portable Emission Measurement System) have been introduced mainly in Europe. A typical PEMS configuration can weigh close to 100 kg however, and its weight affects the driving conditions of vehicles running on actual roads. In this study, we focused on the analysis of real-world emissions using SEMS (Sensorbased Emission Measurement System). Whereas PEMS is a method of sampling and analyzing exhaust gas, SEMS directly attaches a NOx sensor and PM sensor to the exhaust pipe and measures the concentration. Although SEMS has a limited number of items that can be measured compared to PEMS, other analysis is possible by devising the analysis method. This paper focuses on the analysis method of real-world emissions using SEMS and aims to examine the analysis method of CO2 emission concentration, exhaust gas flowrate, and local roadside emissions from the measured value of SEMS. In addition, an example of applying this analysis method using on-road test data of a diesel passenger car equipped with SEMS is shown. The NOx sensor can measure not only the NOx concentration but also the O2 concentration and air-fuel ratio. It is clarified that the CO2 concentration at wet condition can be calculated with high accuracy by using the measured values of the O2 concentration. Also, the exhaust flowrate is obtained by combining the intake air flow rate acquired through the vehicle's OBD and the air-fuel ratio measured by the NOx sensor. At that time, the exhaust gas density is also calculated based on the air-fuel ratio, so that the exhaust flowrate can be calculated with higher accuracy.

To improve the performance of polymer electrolyte fuel cells under high current density operation, the flooding problem in gas diffusion layers (GDLs) should be solved. In this study, a novel GDL with a relatively hydrophilic surface, consisting of hydrophilic and hydrophobic pores, which yielded a wettability distribution in the thickness direction, was proposed to achieve smooth water transport. First, we fabricated GDLs with surfaces partially hydrophilized by Nafion, and we demonstrated that the cell performance improved with this treatment. Cell performance tests suggest that a GDL with optimized surface treatment could reduce the water accumulation compared with the hydrophobic GDL used in this study; it could also improve cell performance owing to low mass transport losses. To verify the surface treatment-induced improvement in the oxygen diffusivity of the GDL, the water transport in the GDL was simulated using a lattice Boltzmann method. The results showed that the water accumulation in the GDL with surface treatment was small because the water flow was limited to the thin relatively hydrophilic region. Consequently, the oxygen diffusivity was higher than that of the hydrophobic GDL. Therefore, the flooding problem can be suppressed by the surface treatment, which yields a relatively hydrophilic surface.