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The development of high-temperature lead-free piezoelectric ceramics with excellent electromechanical properties under low field remains a key challenge. A series of 0.995(xBiFeO 3 -(1-x)BaTiO 3)-0.005Bi(Zn 0.5 Hf 0.5)O 3 ceramics were designed via modulating phase composition. The excellent electromechanical properties of d 33 * = 511 pm/V (45 kV/cm) at room temperature and S = 0.476 % (d 33 * = 1190 pm/V, 40 kV/cm) at 120 ℃ were achieved in the x = 0.67 ceramic owing to the synergistic contribution of phase composition and domain evolution. The XRD results verify that the x = 0.67 ceramic is dominated by the pseudocubic phase. The PFM results in the x = 0.67 and 0.71 ceramics confirm that the domain structures consist of nanodomains with strong and weak piezoelectric responses. More importantly, the temperature and voltage-dependent domain evolution testify the nanodomains are easier to switch in the x = 0.67 ceramic. This work provides a strategy to optimize the electromechanical performance at the low field and a deeper understanding of BF-BT-based piezoceramics. • The 0.995(xBF-(1-x)BT)-0.005BZH high temperature ceramics with multiple phases coexisting are successfully fabricated. • The ceramic with x = 0.67 obtained excellent electrostrain property of d 33 *= 511 pm/V under low electric field. • The voltage and temperature-dependent in-situ domain structure and dynamics evolutions are characterized systematically. [ABSTRACT FROM AUTHOR]

An increasing divergence regarding fuel consumption (and/or CO 2 emissions) between real-world and type-approval values for light-duty gasoline vehicles (LDGVs) has posed severe challenges to mitigating greenhouse gases (GHGs) and achieving carbon emissions peak and neutrality. To address this divergence issue, laboratory test cycles with more real-featured and transient traffic patterns have been developed recently, for example, the China Light-duty Vehicle Test Cycle for Passenger cars (CLTC-P). We collected fuel consumption and CO 2 emissions data of a LDGV under various conditions based on laboratory chassis dynamometer and on-road tests. Laboratory results showed that both standard test cycles and setting methods of road load affected fuel consumption slightly, with variations of less than 4%. Compared to the type-approval value, laboratory and on-road fuel consumption of the tested LDGV over the CLTC-P increased by 9% and 34% under the reference condition (i.e., air conditioning off, automatic stop and start (STT) on and two passengers). On-road measurement results indicated that fuel consumption under the low-speed phase of the CLTC-P increased by 12% due to the STT off, although only a 4% increase on average over the entire cycle. More fuel consumption increases (52%) were attributed to air conditioning usage and full passenger capacity. Strong correlations (R 2 > 0.9) between relative fuel consumption and average speed were also identified. Under traffic congestion (average speed below 25 km/hr), fuel consumption was highly sensitive to changes in vehicle speed. Thus, we suggest that real-world driving conditions cannot be ignored when evaluating the fuel economy and GHGs reduction of LDGVs. [Display omitted] [ABSTRACT FROM AUTHOR]

Chemical doping is an indispensable tool to tailor the properties of the commercial piezoelectric materials. However, a high piezoelectric coefficient with enhanced thermal stability is rarely achieved by one dopant in some high-performance ferroelectrics, e.g., the recently discovered eco-friendly (Ba 0.85 Ca 0.15)(Zr 0.1 Ti 0.9)O 3 (BCZT) ceramics. In order to optimize the piezoelectric property in BCZT system by a simple way, we investigated the doping effect of Fe3+, Nb5+ and Bi3+ cations in BCZT ceramics respectively. The results indicate that only Nb5+-doped BCZT ceramics display a combination of large piezoelectric coefficient and enhanced thermal stability, compared with others. Moreover, the established phase diagrams and in-situ transmission electron microscope (TEM) observations reveal that such optimized piezoelectric properties after Nb5+ doping originates from (i) the low polarization anisotropy near the ambient tetragonal (T)-orthorhombic (O) phase transition and (ii) the easy domain wall motion of persistent miniaturized ferroelectric domains upon heating. [ABSTRACT FROM AUTHOR]

The government of China has announced an ambitious plan to expand the mandatory use of ethanol blended gasoline fuels by 2020. Given the dissimilarity in fuel properties between China and other countries with ethanol blending practices, it is necessary to assess the energy and environmental impacts of ethanol blending. In this study, we prepared two types of ethanol blended fuels (E10, with ethanol contents of approximately 10%) with lower contents of aromatics (ELA) and olefins (ELO), respectively, compared with the market China 5 gasoline. Nine in-use gasoline vehicles varying by manufacturer, engine technology, model year, and emission standard level were analyzed using a chassis dynamometer, which followed the Worldwide Harmonized Light Vehicles Test Cycle (WLTC). Two major positive effects from using E10 fuels could be observed in this study. First, tested turbocharged gasoline direct injection (GDI) vehicles could gain reductions in CO 2 emission, fuel consumption and energy consumption by switching to the higher-octane-number ELO. This finding, along with the engine development trends in the automotive industry (e.g., downsizing and higher compression ratio), may have a synergistic effect to deliver greater energy efficiency in the future. Second, the two ethanol blended fuels could be more effective in reducing the particle mass (PM) and particle number (PN) emissions than the levels of using China 5 gasoline. Notably, the benefit of using ELO was more significant, with average emission reductions of 35% for the PM and of 44% for the PN. However, ELA and ELO possibly increased emissions of gaseous pollutants for certain vehicles in the study, but the intra-vehicle differences between the various fuel groups were not statistically significant (not significant, p > 0.05 , t -test). We suggest that more measurements under various environmental conditions and comprehensive air quality simulations should be conducted to better understand the environmental impacts of ethanol blending in China. Image 1 • Nine gasoline vehicles were tested over one dynamometer by comparing E10 and E0 fuels. • Lower carbon content of low-aromatics E10 (ELA) reduced CO 2 emissions. • GDI vehicles gained reductions in CO 2 emissions and fuel consumption by using low-olefins E10 (ELO). • Two E10 fuels reduced both particle mass and particle number emissions. • The impacts on gaseous pollutants were heterogenous among various vehicles. Capsule: Ethanol blended fuels can reduce particle mass and particle number emissions for gasoline vehicles in China, and an increased octane number can deliver energy efficiency improvement for turbocharged GDI vehicles. [ABSTRACT FROM AUTHOR]

Abstract Mileage of taxi fleets is significantly higher than regular passenger vehicles in China, which might trigger greater tailpipe emissions of air pollutants. To investigate their real-world gaseous emissions, we applied portable emissions measurement systems (PEMSs) to test 44 gasoline and 24 bi-fuel taxis in seven cities. Our real-world measurement results indicated that a major part of the tested China 3 and China 4 gasoline taxis, especially the samples with high mileage (>300,000 km), far exceeded the corresponding emission limits of NO X , THC and CO. Only the newest China 5 gasoline taxis with relatively lower mileage had effective emission controls and the gaseous emissions were below the limits. Illegal tampering, malfunction and deterioration of three-way catalytic converters (TWC) are major reasons for high emissions from high-mileage taxis. First, China 4 gasoline taxis without TWC (purposely removed by drivers) increased their gaseous emissions than TWC-equipped counterparts by more than one order of magnitude. Second, bi-fuel taxis when using compress natural gas (CNG) had much higher NO X and THC emissions than those when using gasoline, which might be probably attributed to unsophisticated engine calibration and unfavorable TWC working conditions. Furthermore, TWC renewal could bring immediate and substantial emission reductions (up to 70%) for high-mileage taxis. However, such benefits from TWC renewal would become less significant as the mileage levels further increase. We also found a good correlation between CO and THC emissions for gasoline taxis, whose cold start effects were both significant. This study poses significant concerns regarding real-world emissions of high-mileage taxi fleets in China, which could consist of many gross emitters in the urban areas. Stringent in-use compliance programs and in particular frequent TWC renewals for high-mileage taxis should be implemented by policy makers in China. Graphical abstract Unlabelled Image Highlights • Real-world emissions from 44 gasoline and 24 bi-fuel taxis were measured using PEMS. • A major part of high-mileage China 3 and 4 taxis far exceeded the emission limits. • Switching from gasoline to CNG for bi-fuel taxis increased NO X and THC emissions. • Purposed tampering and natural deterioration of TWC converters caused high emissions. • PEMS measurements show cold start has significant effects on THC and CO emissions. [ABSTRACT FROM AUTHOR]

The gasoline direct injection (GDI) engine has substantially penetrated light-duty gasoline vehicles to help reduce fleet-wide fuel consumption across the world. However, increased particle emissions from GDI vehicles rather than the conventional multi-port fuel injection (MPFI) vehicles are of great concern. To investigate the particle emissions for these two categories of gasoline engines, we employed a dynamometer and measured the emissions of solid particle number (PN) and black carbon (BC) for four GDI and four MPFI vehicles under various testing cycles and conditions. Under the reference cycle (30 °C and cold-start WLTC), a strong correlation between solid PN and BC emissions is identified for both GDI and MPFI vehicles, although GDI vehicles without particle filters have significantly higher emissions of solid PN and BC than those of MPFI vehicles. Furthermore, varying the testing conditions by including cold start, low temperature, aggressive driving and air conditioning use all increase the emissions of solid PN and BC. These affecting factors pose more significant changes to particle emissions from MPFI vehicles than GDI vehicles. For example, at −7 °C, the solid PN and BC emissions of MPFI vehicles are increased by 4.17 times and 16.5 times relative to the results under 30 °C, and they are comparable to or higher than the emissions of GDI vehicles. Our results indicate that modern gasoline vehicles available in China’s market are likely to fail to comply with the upcoming PN emission limit (China 6), suggesting a serious need to adopt gasoline particle filters (GPF) for both GDI and MPFI vehicles. Advanced after-treatment technologies and stringent regulations to control particle emissions from gasoline vehicles should fully consider varying real-world conditions to guarantee effective environmental benefits. [ABSTRACT FROM AUTHOR]

Fast development of electrostatic capacitors requires dielectric materials to perform large energy storage densities with high efficiency over a wide temperature range. Although antiferroelectric materials hold great potentials for achieving superior energy storage effect due to the field-induced antiferroelectric-ferroelectric transition, the strongly first-order transition is inevitably accompanied with a low energy storage efficiency and inferior thermal stability. Here, we found that a high polarization change and low hysteresis can be simultaneously achieved in a crossover composition between antiferroelectric and relaxor antiferroelectric states. As a result, a large recoverable energy storage density (W rec ∼ 8.6 J/cm3) with high efficiency (η ∼ 85%) is obtained in lead-free Ag 1-3 x La x Nb 0.9 Ta 0.1 O 3 (x =0.03) ceramics under 460 kV/cm. The x =0.03 ceramics also exhibit excellent energy storage properties (W rec > 6.8 J/cm3 with ultrahigh η ∼ 90%) in the temperature range of 20-120°C. This promising energy storage effect of the antiferroelectric crossover composition arises from the coexistence of micro- and nano-antiferroelectric domains, which can persist over a wide temperature range. Our work may push forward the development of high-performance lead-free antiferroelectric dielectrics for energy storage devices. [Display omitted] [ABSTRACT FROM AUTHOR]

Vehicles emit substantial amounts of pollutants during start periods. Engine starts mainly occur in urban areas, causing serious harm to humans. To investigate the impacts on extra cold start emissions (ECSEs), eleven China 6 vehicles with various control technologies (fuel injection, powertrain, and aftertreatment) were monitored with a portable emission measurement system (PEMS) at different temperatures. For conventional internal combustion engine vehicles (ICEVs), the average ECSEs of CO 2 increased by 24%, while the average ECSEs of NOx and particle number (PN) decreased by 38% and 39%, respectively, with air conditioning (AC) on. Gasoline direct injection (GDI) vehicles had 5% lower CO 2 ECSEs, but 261% higher NOx ECSEs and 318% higher PN ECSEs than port fuel injection (PFI) vehicles at 23 °C. The average PN ECSEs were significantly reduced by gasoline particle filters (GPFs). The GPF filtration efficiency was higher in GDI than PFI vehicles due to particle size distribution. Hybrid electric vehicles (HEVs) generated excessive PN extra start emissions (ESEs), resulting in a 518% increase compared to ICEVs. The start times of the GDI-engine HEV accounted for 11% of the whole test time, but the proportion of PN ESEs relative to total emissions were 23%. Linear simulation based on the decrease in ECSEs with increasing temperature underestimated the PN ECSEs from PFI and GDI vehicles by 39% and 21%, respectively. For ICEVs, CO ECSEs varied with temperature in a U shape with a minimum at 27 °C; NOx ECSEs decreased as ambient temperature increased; PFI vehicles generated more PN ECSEs at 32 °C than GDI vehicles, stressing the significance of ECSEs at high temperature. These results are useful for improving emission models and assessing air pollution exposure in urban aeras. [Display omitted] • Real-world extra cold start emissions (ECSEs) of eleven China 6 vehicles were measured. • GDI vehicles emitted 318% more ECSEs of PN than PFI vehicles did. • The GPF filtration efficiency for ECSEs was higher in GDI vehicles than PFI vehicles. • The ESE of PN from the GDI-engine HEV accounted for 23% of the total emission. • ECSEs of PN from PFI vehicles was 2.1 times those from GDI vehicles at 32 °C. [ABSTRACT FROM AUTHOR]

Vehicle emissions are greatly influenced by various factors that are related to engine technology and driving conditions. Only the fuel injection method and ambient temperature are investigated in this research. Regulated gaseous and particulate matter (PM) emissions from two advanced gasoline-fueled vehicles, one with direct fuel injection (GDI) and the other with port fuel injection (PFI), are tested with conventional gasoline and ethanol-blended gasoline (E10) at both −7 °C and 30 °C. The total particle number (PN) concentrations and size distributions are monitored with an Electrical Low Pressure Impactor (ELPI + ). The solid PN concentrations are measured with a condensation particle counter (CPC) after removing volatile matters through the particle measurement program (PMP) system. The results indicate that decreasing the ambient temperature from 30 °C to −7 °C significantly increases the fuel consumption and all measured emissions except for NO x . The GDI vehicle exhibits lower fuel consumption than the PFI vehicle but emits more total hydrocarbons (THC), PM mass and solid PN emissions at 30 °C. The adaptability of GDI technology appears to be better than that of PFI technology at low ambient temperature. For example, the CO, THC and PM mass emission factors of the PFI vehicle are higher than those of the GDI vehicle and the solid PN emission factors are comparable in the cold-start tests at −7 °C. Specifically, during start-up the particulate matter emissions of the PFI are much higher than the GDI. In most cases, the geometric mean diameter (GMD) of the accumulation mode particles is 58–86 nm for both vehicles, and the GMD of the nucleation mode particles is 10–20 nm. The results suggest that the gaseous and particulate emissions from the PFI vehicle should not be neglected compared to those from the GDI vehicle especially in a cold environment. [ABSTRACT FROM AUTHOR]

Engine start-stop (S&S) technology has been substantially incorporated into modern vehicles to save fuel during idling in congested urban areas because fuel economy regulations have become more stringent. However, the potential for increasing particle emissions after engine restarts, especially in cold environments, is of great concern. To investigate the effects of S&S systems on fuel consumption and tailpipe emissions, a chassis dynamometer was employed to measure the fuel consumption, particulate matter (PM), solid particle number (PN), particle number size distribution and black carbon (BC) for a typical gasoline direct injection vehicle when the S&S was on (S&S-on) and when the S&S was off (S&S-off) according to the worldwide harmonized light-duty test cycle in both hot (28 °C) and cold (5 °C) environments. S&S operation resulted in 3.1–4.3% fuel-savings at 28 °C but had a tendency to increase particulate emissions, especially of BC (21.8–31.8%) and PM (19.2–32.8%). Although PN emissions with S&S-on over the entire cycle were slightly lower than those with S&S-off, more particles were emitted during the engine restart moments. In a cold environment, the fuel-savings advantage of the S&S system was weakened, and the negative impacts on the particle emissions during the restart moment worsened. The S&S system resulted in higher abundances of accumulation mode particles, especially under cold ambient conditions. The relationship between the PN reduction rates and idling segments was determining to be exponential. Our results indicate that the S&S system, which may increase particle emissions during restarts, does save fuel, and that a comprehensive evaluation of the system in cold environments is needed to determine the serviceability of new engine technologies and after-treatments. [Display omitted] • The advantages of start-stop system (S&S) decrease in cold environments. • S&S operation uses 3.1–4.3% less gasoline at 28 °C, but increases particle emissions. • More large particles (>0.07 μm) are generated during engine restart moments. • Engine restarts with S&S-on result in more particles at 5 °C than at 28 °C. • Particles emitted during restart with S&S-on decrease as the idling time increases. [ABSTRACT FROM AUTHOR]

One of the key questions in the development of eco-friendly piezoelectrics lies in how to achieve large hysteresis-free electrostrain responses in a facile and effective manner, to meet the requirements of high-precision electromechanical devices. Here, through integrating phase-field modeling and experimental approach, a highly effective strategy is proposed for large electrostrain outputs with negligible hysteresis in lead-free perovskite oxide ferroelectrics, by building coexistent glasses with diverse local symmetries near a quadruple point rendering low energy barriers between different polar states. Guided by phase-field simulations, a superior electrostrain of ~ 0.21% with nearly-zero hysteresis is obtained at the constructed glasses region near the quadruple point of Bi-doped Ba(Zr 0.2 Ti 0.8)O 3 - x (Ba 0.7 Ca 0.3)TiO 3 ceramics, outperforming almost state-of-the-art lead-free piezoelectric substitutions when taking both electrostrain and hysteresis into account. The strategy of building coexistent glasses near the quadruple point provides a novel design paradigm for high-performance piezoelectric materials in the application of high-precision actuators. [Display omitted] • A novel approach is proposed theoretically for large hysteresis-free electrostrains in lead-free piezoceramics. • A large electrostrain ~ 0.21% with nearly-zero hysteresis is achieved in BaTiO 3 -based ceramics. • The work provides a facile manner to design superior eco-friendly piezoelectric materials for high-precision actuators. [ABSTRACT FROM AUTHOR]

A key challenge for the practical application of lead-free piezoelectrics is how to acquire high-piezoelectricity and good thermal-cycling stability simultaneously. Here, we report that excellent thermal-cycling stability was obtained in aged (Ba 0.85 Ca 0.15)(Ti 0.9 Zr 0.1) 99.75/100 Fe 0.25/100 O 3-δ lead-free piezoceramic with high-piezoelectricity (d 33 ~ 400 pC/N). No piezoelectricity degradation was found for the aged sample after 100 thermal cycles between -40 °C and 50 °C. Further studies on hysteresis loop and evolution of microstructures reveal that the excellent thermal-cycling stability is related to the point-defect migration during aging. This work indicates that aging is an effective way to obtain good thermal-cycling stability and high-piezoelectricity simultaneously. [Display omitted] [ABSTRACT FROM AUTHOR]

Emissions of major reactive nitrogen compounds, including nitric oxide (NO), nitrogen dioxide (NO 2) and ammonia (NH 3), from heavy-duty diesel vehicles (HDDVs) place substantial pressure on air quality for many large cities in China. To control nitrogen oxide (NO X) emissions from HDDVs, selective catalytic reduction (SCR) systems have been widely used since the China IV standards. To investigate the impacts of aftertreatment technologies and driving conditions on real-world emissions of reactive nitrogen compounds, a portable emissions measurement system was employed to test eighteen heavy-duty diesel trucks in China. The results showed that the China IV and China V HDDVs with appropriate SCR functionality could reduce NO X emissions by 36% and 53%, respectively, compared to the China III results, although their real-world emissions were still higher than the corresponding emission limits for regulatory engine tests. For these HDDVs, five samples were tested with NH 3 emissions, ranging from 1.67 ppm to 51.49 ppm. The NH 3 emission rates tended to significantly increase under high-speed driving conditions. The results indicate that the current SCR technology may have certain risks in exceeding the future China VI NH 3 limit. However, five China IV/V HDDVs were found to have SCR temperature sensors that were intentionally tampered with, resulting in comparable or even higher NO X emissions and zero NH 3 emissions. Increased NO 2 emissions due to the adoption of diesel oxidation catalysts and diesel particulate filters were also found from our experiments. This study highlights the importance of enhancing in-use compliance requirements and eliminating aftertreatment tampering for China IV and China V HDDVs. Image 1 • Tampered trucks emitted twice as much NO X as normal trucks although no NH 3 detected. • Current selective catalytic reduction may emit NH 3 above the China VI limit. • Oxidation catalysts increased NO 2 by 79%, but little effect on NO X and NH 3. [ABSTRACT FROM AUTHOR]

Heavy-duty diesel vehicles (HDDVs) are important sources of urban nitrogen oxides (NO X). Understanding real-world NO X emissions from HDDVs is important because it has been shown that NO X emissions could far exceed the desired limits and impact human health. On-vehicle sensors for real-time emission evaluations have become commercially available, and China has adopted an on-board sensing (OBS) pilot program in Beijing. The OBS system utilizes information from the engine data networks which including real-time NO X concentrations from on-road HDDVs. To evaluate the accuracy of OBS monitoring, one of the vehicles in the OBS pilot program was equipped with a portable emissions measurement system (PEMS) and was evaluated over the course of two days during on-road comparison testing. The vehicle was operated under normal conditions and under conditions simulating a tampered vehicle with no urea for the selective catalytic reduction (SCR) system. A comparison between the OBS and PEMS exhibited good NO X correlations on an instantaneous and moving-average basis. Although large OBS-to-PEMS discrepancies were found in a small portion of instantaneous measurements, the 60-s moving averaged NO X concentrations exhibited good agreements across all the test conditions (Pearson's R > 0.95 and mean relative errors from −13% to +22%). During the tampered SCR simulation, the average vehicle emissions increased from 22 g kg fuel−1 to 48 g kg fuel−1, where both the PEMS and OBS quantified consistent trends. The actual NO X emissions, registered by the OBS over fifteen consecutive days of normal vehicle operation, ranged from 3.29 g km−1 to 6.65 g km−1. A comparison with the PEMS suggests the OBS can effectively and accurately identify high-emitting situations for in-use diesel vehicles. Recommendations are provided to improve the implementation of OBS programs in future applications. • We used PEMS testing to evaluate the OBS technology for monitoring NO X emissions. • The NO X concentrations measured by OBS and PEMS nicely correlated to each other. • Moving-averaged NO X concentrations showed good agreements between OBS and PEMS. • The OBS monitoring can effectively reflect high NO X emitting events. • Recommendations are provided to improve the implementation of OBS monitoring. [ABSTRACT FROM AUTHOR]

Abstract Strain glass, a glassy state of lattice strain, has been found in Ti 50- x Ni 50+ x alloys and later in many metallic ferroelastic/martensitic systems, where shear or shuffle serves as a primary order parameter (POP). Another class of non-metallic ferroelastic ceramics are also known to widely exist and commonly possess a polyhedral tilt as the POP. So far, it is unclear whether a "tilt" strain glass exists. Here, we report a finding of a tilt strain glass in La 1- x Sr x Al 0.95 Nb 0.05 O 3-δ ceramics. With increasing Sr2+ dopants, the ferroelastic transition from cubic to rhombohedral phases is gradually suppressed. At a critical concentration (x c ∼10%), a strain glass transition emerges, characterized by five sets of evidence: (I) an invariance of average structure; (II) frequency dependence of elastic moduli at a strain glass transition temperature T g ; (III) non-ergodicity; (IV) formation of rhombohedral nanodomains; (V) a gradual increase of tilt angle upon cooling. Surprisingly, the established phase diagram shows an increase of T g with increasing dopants (a positive correlation), which is different from previous strain glass phase diagrams. The positive and negative correlations can be explained as a balance between two factors of strain glass transition: a global transition factor producing a negative contribution competes with a local field one producing a positive contribution. Our discovery of strain glass in ceramics may also bring novel properties as in metals. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

In recent years, with rapid increases in the number of vehicles in China, the contribution of vehicle exhaust emissions to air pollution has become increasingly prominent. To achieve the precise control of emissions, on-road remote sensing (RS) technology has been developed and applied for law enforcement and supervision. However, data quality is still an existing issue affecting the development and application of RS. In this study, the RS data from a cross-road RS system used at a single site (from 2012 to 2015) were collected, the data screening process was reviewed, the issues with data quality were summarized, a new method of data screening and calibration was proposed, and the effectiveness of the improved data quality control methods was finally evaluated. The results showed that this method reduces the skewness and kurtosis of the data distribution by up to nearly 67%, which restores the actual characteristics of exhaust diffusion and is conducive to the identification of actual clean and high-emission vehicles. The annual variability of emission factors of nitric oxide decreases by 60% – on average – eliminating the annual drift of fleet emissions and improving data reliability. [Display omitted] [ABSTRACT FROM AUTHOR]

Diesel vehicles have caused serious environmental problems in China. Hence, the Chinese government has launched serious actions against air pollution and imposed more stringent regulations on diesel vehicle emissions in the latest China VI standard. To fulfill this stringent legislation, two major technical routes, including the exhaust gas recirculation (EGR) and high-efficiency selective catalytic reduction (SCR) routes, have been developed for diesel engines. Moreover, complicated aftertreatment technologies have also been developed, including use of a diesel oxidation catalyst (DOC) for controlling carbon monoxide (CO) and hydrocarbon (HC) emissions, diesel particulate filter (DPF) for particle mass (PM) emission control, SCR for the control of NO x emission, and an ammonia slip catalyst (ASC) for the control of unreacted NH 3. Due to the stringent requirements of the China VI standard, the aftertreatment system needs to be more deeply integrated with the engine system. In the future, aftertreatment technologies will need further upgrades to fulfill the requirements of the near-zero emission target for diesel vehicles. [Display omitted] [ABSTRACT FROM AUTHOR]

The 0.63(1-x)Bi 1.02 FeO 3 -0.37BaTiO 3 -xBi(Zn 2/3 (Nb 0.85 Ta 0.15) 1/3)O 3 (abbreviated BF-BT-xBZNT) high temperature dielectric ceramics were prepared via a two-step sintering (TTS) method. The appropriate medium permittivity achieved in the BF-BT-0.13BZNT ceramic is conducive to mitigating the polarization saturation and improving the breakdown field strength. The domain evolution behavior from piezoresponse force microscopy (PFM) reveals that the introduction of BZNT promotes the formation and switching of more nanodomains of BF-BT ceramics, facilitating the enhancement of energy storage efficiency. The excellent energy storage performance of total energy storage density (W tot) of 6.06 J/cm3, recoverable energy storage density (W rec) of 4.85 J/cm3 and a high energy storage efficiency (η) of 80% are simultaneously obtained under 410 kV/cm in the BF-BT-0.13BZNT ceramic. Meanwhile, the ceramic exhibits excellent thermal endurance (10–130 ℃), frequency (1–100 Hz) and fatigue (105 cycles) stability. The current work provides a promising strategy for designing high-performance dielectric energy storage materials which operate in harsh environments. • Utilize a composition design strategy to simultaneously obtained optimized polarization and large electric field strength. • The excellent W rec (~ 4.85 J/cm3) and η (~ 80%) at a large field of 410 kV/cm were achieved in BiFeO 3 -based ceramics. • The domain dynamic evolution behavior is confirmed by PFM measurements. • The energy storage performance has a good frequency, temperature, and cycling stability. [ABSTRACT FROM AUTHOR]

Plants produce a large number of diverse metabolites when they grow and develop as well as when they respond to the changing external environment. These are an important source of human nutrition and medicine. In this review we emphasized the major issues of the primary-specialized metabolic interface in plant metabolism, described the metabolic flow from primary to specialized metabolism, and the conservation and diversity of primary and specialized metabolites. At the same time, we summarized the regulatory mechanisms underpinning the dynamic balance primary and specialized metabolism based on multi-omics integration analysis, as well as the natural variation of primary and specialized metabolic pathways and genes during the plant evolution. Moreover, the discovery and optimization of the synthesis and regulation elements of various primary to specialized metabolic flows provide the possibility for precise modification and personalized customization of metabolic pathways, which will greatly promote the development of synthetic biology. [ABSTRACT FROM AUTHOR]

Start emissions from gasoline light-duty passenger vehicles (LDPVs) remain an important source of emissions modeling. This study measured start emissions of gaseous pollutants and solid particle number based on dynamometer tests for a fleet of 111 LDPVs in China, and selected a portion of samples to be tested under low temperature or shorter soak conditions. The cold-start phase, defined to follow soak durations of more than 6 h, typically lasts less than 200 s but accounts for a high proportion of total tailpipe emissions under the regulatory cycle (e.g., ~60% for China 6 CO emissions). Low temperature predominantly increases start emissions rather than hot-running emissions, and the increase ratios vary by pollutant and vehicle technology. Metrological data and soak duration profiles informed by a large sample of LDPVs were used to quantify the seasonal, diurnal and spatial variabilities of LDPV emissions across China. One notable case indicates that tailpipe THC emissions in January could be 283% higher than those in July for the fleet in Beijing, and the emissions peak in the morning rush hour during a day due to long overnight soak durations. This study provides a comprehensive dataset and useful tools for addressing the seasonal, diurnal and spatial variations in tailpipe emissions of gasoline vehicles in China, and has the potential to improve future emission inventories and air quality simulations. Image 1 • Start emissions were tested for 111 light-duty passenger vehicles in China. • Impacts of ambient temperature and soak time on start emissions were characterized. • Vehicle emissions were modeled according to individual trip-chain profiles. • Territorial, seasonal and hourly variabilities of start emissions were quantified. • THC emissions in January could be 283% higher than July for the fleet in Beijing. [ABSTRACT FROM AUTHOR]

The reliability of piezoelectricity under thermal-cycling is an important consideration for the practical application of Pb-free piezoelectric materials. In this paper, we investigated the effect of thermal-cycling on the piezoelectricity of 0.5Ba(Zr 0.2 Ti 0.8)O 3 -0.5(Ba 0.7 Ca 0.3)TiO 3 (BZT-BCT) Pb-free piezoceramic. The results show that, in BZT-BCT, the tetragonal-orthorhombic (T-O) transition causes a strong piezoelectricity degradation (∼40% reduction after 60 thermal cycles between −40 °C and 50 °C), whereas the orthorhombic-rhombohedral (O-R) transition only leads to negligible degradation during the thermal-cycling test, indicating a weak depoling effect. The comparative studies made between BZT-BCT and BaTiO 3 (BT) reveal that the weak depoling effect results from the diffuseness of the O-R transition in BZT-BCT and weak domain pattern change across the transition. Our work implies that Pb-free piezoelectrics with good thermal-cycling stability can be achieved through engineering the normal ferroelectric-to-ferroelectric transition to a diffused one, which may help to design new Pb-free piezoelectric materials with good thermal-cycling stability. Image 1 • Normal ferroelectric-to-ferroelectric phase transition leads to a poor thermal-cycling stability. • Diffuse ferroelectric-to-ferroelectric phase transition causes a good thermal-cycling stability. • Good thermal-cycling stability roots in the weak domain pattern changes. [ABSTRACT FROM AUTHOR]

The latest China VI emission standard has introduced a remote monitoring rule for regulating in-use emissions of heavy-duty diesel vehicles (HDDVs). Real-time data regarding engine and aftertreatment operating conditions and tailpipe nitrogen oxides (NOx) concentrations are required to be collected through electronic control unit and on-board NOx sensors by vehicle original equipment manufacturers (OEMs), and then transmitted to environmental authorities. Beijing has developed a local standard that requires OEMs to design China VI-like on-board monitoring (OBM) systems for new China V HDDVs since September 2018. Additionally, Beijing has been a pioneer in retrofitting in-use China IV and China V HDDVs with OBM systems since 2017. This paper contains a timely technical and policy assessment for the state-of-the-art OBM programs in China with a focus on the recent progress in Beijing. Both OEM-performed and retrofitted OBM data were collected from a fleet of OBM-instrumented vehicles. First, our assessment shows high data integrity and quality of OEM-performed OBM systems. In contrast, a considerable fraction of HDDVs equipped with retrofitted OBM systems did not completely report NOx concentrations, intake mass air flow and other parameters. Next, eight OBM-instrumented HDDVs were tested on road by portable emissions measurement systems (PEMSs) to examine the reliability of sensor-based NOx concentrations. The majority (6 of 8) shows a good agreement between OBM and PEMS results with an average relative error of approximately −15%. Furthermore, calculation of NOx mass emissions, inter-trip variability, and alternative methods of enforcing in-use emissions management (e.g., to develop concentration metric-based emission limits) are discussed. This early-stage assessment suggests the OBM approach has the potential to play a central role in in-use emission inspections for HDDVs in China. The regulatory agency should focus more attention to the data integrity and the reliability of NOx sensors by developing effective verification processes. Unlabelled Image • China's on-board emission monitoring (OBM) standards for HDDVs are introduced. • Data integrity and quality of selected OBM-equipped HDDVs in Beijing are evaluated. • PEMS tests show good reliability of OBM NO X data for the majority of tested HDDVs. • Alternative methods based on OBM data are discussed for managing in-use emissions. • Verification of data quality and NO X concentrations is recommended for future inspections. [ABSTRACT FROM AUTHOR]

Thanks to its small hysteresis, large electrostrictive strain in relaxor ferroelectrics is superior than piezoelectric strain for applications in precision microactuators. Although relaxor ferroelectrics exhibit the largest electrostrictive strain in ceramics, the magnitude of the strain is limited to ∼0.20% at room temperature due to the large amount of non-ferroelectric defects existing in relaxors. In this work, we develop a relaxor with a morphotropic phase boundary (MPB) by doping a rhombohedral (R3m) ferroelectric BaZr 0.2 Ti 0.8 O 3 into a tetragonal (P4 mm) ferroelectric 0.89Bi 0.5 Na 0.5 TiO 3 -0.11BaTiO 3. A high electrostrictive strain of 0.27% is achieved at room temperature in the relaxor sample. Experimental results illustrate that the composition is near the MPB and exhibits the existence of nanodomains, favoring the achievement of high electrostrictive strain. Moreover, phase field simulations show that the high electrostrictive strain obtained at this composition originates from the low defect fields needed to induce relaxor as a result of small polarization anisotropy at the phase boundary as compared to conventional relaxors away from phase boundaries. Our work provides a new design strategy for the next generation of high-performance ferroelectric relaxors. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Tackling vehicle emissions is one important task for governmental stakeholders to develop cleaner cities. Gasoline-fueled light-duty passenger vehicles (LDPVs) are intensively used in populous urban areas to meet passenger transportation demand. However, gasoline vehicle emissions raise the health risk due to the proximity of exposure to gasoline exhaust. To better understand the genotoxicity of gasoline emissions, this study is focused on their emissions of particulate polycyclic aromatic hydrocarbons (p-PAHs). We combined dynamometer testing, filter sampling and offline chemical analysis to measure p-PAH emissions from five in-use gasoline LDPVs. The results indicate that the emission factors of tested vehicles under the Worldwide Harmonized Light Vehicles Test Cycle (WLTC) decrease significantly with emission standard, from 11.27 μg km −1 for one China 3 LDPV to below 6 μg km −1 for the other newer LDPVs (China 4 and 5). Different from the mass distribution of p-PAH species for diesel vehicles, medium-and high-molecular-weight PAHs (e.g., 4, 5, and 6-ring species) are considerably identified from the gasoline particle samples. These medium and high-weight PAHs, such as benzo [a]pyrene (BaP) and dibenzo [ah]anthracene (DaA), in general have much greater toxic equivalency factors than low-molecular-weight PAHs. Furthermore, this study also reports that engine type and driving cycle conditions would have discernible impacts on p-PAH emissions. The gasoline direct injection (GDI) engine-equipped LDPVs would increase p-PAH emissions compared with the counterparts using port-fuel injection (PFI) engines. Cold start and transient driving conditions could also result in increased p-PAH emissions, while high-speed driving conditions tend to reduce the p-PAH content in total particles. The significant health impacts caused by p-PAH emissions from gasoline LDPVs should be concerned, and more effective measures should be taken to eliminate gasoline particle emissions. [ABSTRACT FROM AUTHOR]

The limited understanding of vehicular emissions in China, especially evaporative emissions, is one obstacle to establishing tighter standards. To evaluate tailpipe and evaporative emissions, two typical China IV vehicles and one Tier 2 vehicle with an onboard refuelling vapour recovery (ORVR) system were selected and tested. One of the China IV vehicles was fuelled with gasoline, E10 and M15, respectively, to investigate the effect of fuel properties on vehicular emissions. For each vehicle, cold-start tailpipe emission tests were conducted first, followed by an evaporation test. Based on the emission factors and real-world vehicle activity data, the annual tailpipe and evaporative hydrocarbon (HC) emissions of each vehicle were calculated and compared. The results show that E10 and M15 significantly reduced the tailpipe CO and particle number (PN) emissions but seriously aggravated the NO x emissions, especially for M15. The hot soak losses (HSLs) and diurnal breathing losses (DBLs) were slightly impacted by the fuel properties. The annual evaporative emissions with E10 and M15 were higher than that with gasoline. The ORVR system effectively controlled the evaporative emissions, especially for DBLs. Evaporative emissions from the China IV vehicles were 1.1–1.4 times the tailpipe HC emissions. Additionally, the evaporative emission factors of the China IV vehicles were almost 50% lower than the standard (2.0 g/test), whereas their annual evaporative emissions were almost 1.8–2.8 times higher than those from the Tier 2 vehicle. Therefore, controlling evaporative emissions currently remains a great need in China, and the ORVR might be a recommended evaporative control technology. [ABSTRACT FROM AUTHOR]

Heusler alloys hold great potential to act as cooling medium for next-generation solid state refrigeration due to their substantial entropy changes at field-driven magnetostructural transitions. One of the key impediments in the use of Heusler alloys for efficient cooling lies in the poor reversibility of magnetocaloric effect (MCE). In this work, a highly reversible MCE with large isothermal heat Q of ∼ 4.83–5.3 kJ/kg near room temperature, is achieved in Ni 50 Mn 34 In 12 Ga 4 Heusler alloys at the transition between unfrozen canonical spin-glassy martensite and ferromagnetic austenite, crosschecked by indirect and direct methods. Phase field simulations reveal that the presence of spin glass in martensite state can result in reversible field-induced magnetostructural transitions in Heusler alloys, thus effectively circumventing the irreversibility of large MCE at strong first-order transitions without the need of any external stimuli such as mechanical load. The occurrence of such field-induced first-order transitions arose from the negative coupling between magnetic moment and the volume of the material. This work suggests the great power of ferroic glasses in improving the reversibility of promising MCE at first-order phase transitions and may push forward more Heusler alloys close to the practical refrigerant in highly efficient solid-state cooling protocols. [Display omitted] A new pathway by exploiting ferroic glasses around first-order transitions is developed theoretically and experimentally to enable giant reversible magnetocaloric effect in Heusler alloys, pushing the Heusler alloys one step further towards the practical refrigerant in MCE cooling protocols for continuous highly-efficient, eco-friendly and noise-free refrigeration. [ABSTRACT FROM AUTHOR]

• A W r of 4.6 J/cm3 under 430 kV/cm and η of 62.5% are achieved in Ag 0.97 Nd 0.01 NbO 3. • Ag 0.97 Nd 0.01 NbO 3 ceramics demonstrate excellent temperature stability from 25 ℃ up to 125 ℃. • Outstanding power density of 54.0 MW/cm3 and ultrafast discharge speed (t 0.9) of 59.2 ns were also obtained. Lead-free dielectric capacitors for energy storage device have attracted increasing attention recently because of their high-power density and superior temperature stability. In this work, Nd-doped silver niobate (AgNbO 3 , abbreviated as AN) lead-free antiferroelectric ceramics were prepared by utilizing traditional solid state reaction method. A large energy storage density of 4.6 J/cm3 and an efficiency of 62.5% were simultaneously obtained in the 1% Nd-doped AN sample with an outstanding power density of 54.0 MW/cm3 and an ultrafast discharge speed (t 0.9) of 59.2 ns. Additionally, the 1% Nd-doped AN ceramic demonstrates a good temperature stability from 25 ℃ to 130 ℃. The excellent energy storage properties of the 1% Nd-doped ceramic is ascribed to the enhanced breakdown electric field induced by grain size engineering and the construction of phase structure via heterovalent substitution at the A-site of the lattice structure at room temperature. Our present work suggests that the 1% Nd-doped AN ceramic show promise for energy storage application in miniaturized mobile electronic devices and high-power equipment. [ABSTRACT FROM AUTHOR]