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There is evidence that black carbon (BC) particles may affect cirrus formation and hence global climate by acting as potential ice nucleating particles (INPs) in the troposphere. Nevertheless, the ice nucleation (IN) ability of bare BC and BC coated with secondary organic aerosol (SOA) material remains uncertain. We have systematically examined the IN ability of 100–400 nm size-selected BC particles with different morphologies and different SOA coatings representative of anthropogenic (toluene and n-dodecane) and biogenic (β-caryophyllene) sources in the cirrus regime (−46 to −38 °C). Several aerosolized BC proxies were selected to represent different particle morphologies and oxidation levels. Atmospheric aging was further replicated with exposure of SOA-coated BC to OH. The results demonstrate that the 400 nm hydrophobic BC types nucleate ice only at or near the homogeneous freezing threshold (−42 to −46 ˚C). Deposition IN, as opposed to purely homogeneous freezing, was observed to occur for some BC types between 100–200 nm within the investigated temperature range. More fractal BC particles did not consistently act as superior deposition INPs over more spherical ones. SOA coating generated by oxidizing β-caryophyllene with O3 did not seem to affect BC IN ability. However, SOA coatings generated from OH oxidation of various organic species did exhibit higher IN onset supersaturation ratio with respect to ice (SSi) compared with bare BC particles, with toluene SOA coating showing an increase of SSi by 0.1–0.15 while still below the homogeneous threshold. n-dodecane and β-caryophyllene-derived SOA only froze in the homogeneous regime. We attribute the inhibition of IN ability to the filling of the pores on the BC surface by the SOA material coating. OH exposure levels of all SOA coating experiments, from an equivalent atmospheric 10 days to 90 days, did not render significant differences in IN potential. Our study suggests that BC particles with large sizes and/or oxidized surfaces generally exhibit better IN ability, and that the organic coating materials can inhibit ice formation.

Dissolved oxygen (DO) content is an essential indicator for evaluating the quality of the water body and the main parameter for water quality monitoring. The development of high-precision DO detection methods is of great significance. This paper reports an integrated optofluidic device for the high precision measurement of dissolved oxygen based on the characteristics of silver nanoprisms. Metal nanoparticles, especially silver nanoprisms, are extremely sensitive to their surroundings. In glucose and glucose oxidase systems, dissolved oxygen will be transformed into H2O2, which affects the oxidation and erosion process of nanoprisms, then influences the optical properties of nanoparticles. By detecting the shift in the plasma resonance peak of the silver nanoparticles, the dissolved oxygen (DO) content can be determined accurately. Great reconfigurability is one of the most significant advantages of the optofluidic device. By simply adjusting the flow rate ratio between the silver nanoprisms flow and the water sample flow, real-time continuous adjustment of the detection ranges of DO from 0 to 16 mg/L can be realized dynamically. The detection limit of this device is as low as 0.11 &micro, M (3.52 &micro, g/L) for DO measurement. Thus, the present optofluidic system has a wide range of potential applications in fields of biomedical analyses and water sensing.

Deposition ice nucleation (IN) is a heterogeneous pathway by which water vapor deposits directly onto a solid surface and forms ice. Deposition IN happens below water saturation. However, the pore condensation and freezing (PCF) mechanism offers another explanation to ice formation on porous particles at low ice supersaturation. A single black carbon (BC) aggregate consists of several primary particles, forming crevices between primary particles. Whether BC IN happens via deposition or PCF remains uncertain due to the fractal nature of BC particles.We estimated aggregate surface area, morphology, and primary particle size distribution directly from scanning electron microscopy (SEM) images of size-selected (200 nm, 300 nm, and 400 nm) commercial BC particles. Correlations between surface area data obtained from SEM image estimation and traditional BET tests were explored. Several shape parameters were chosen to characterize particle morphology. The IN ability of aerosolized BC particles was determined with the Spectrometer for Ice Nuclei (SPIN) in the cirrus regime (-46 to -38°C). Particle number concentration and chemical composition were monitored online by a Condensation Particle Counter (CPC) and the Particle Analysis by Laser Mass Spectrometry (PALMS) instrument, respectively.Preliminary experimental results suggest that larger (400 nm) BC particles are more fractal and branching compared with smaller (200-300 nm) particles. Larger, more fractal BC particles are superior ice nucleating particles (INP) when compared with smaller, more spherical ones. The primary particle size distribution of all samples peaks around 30-45 nm. To understand the relevance of the PCF mechanism with our experimental IN results, we established Young-Laplace equations for the potential liquid-vapor interfaces within inter-primary particle crevices and pores and inter-aggregate pores. Solutions of the Young-Laplace equation on a saddle surface was deducted. Whether ice nucleation happens via PCF mechanism or deposition still requires further investigation, since particle surface chemistry can also affect both ice formation pathways.

Parasitoid wasps represent a large proportion of hymenopteran species. They have complex evolutionary histories and are important biocontrol agents. To advance parasitoid research, a combination of Illumina short-read, PacBio long-read and Hi-C scaffolding technologies was used to develop a high-quality chromosome-level genome assembly for Pteromalus puparum, which is an important pupal endoparasitoid of caterpillar pests. The chromosome-level assembly has aided in studies of venom and detoxification genes. The assembled genome size is 338 Mb with a contig N50 of 38.7 kb and a scaffold N50 of 1.16 Mb. Hi-C analysis assembled scaffolds onto five chromosomes and raised the scaffold N50 to 65.8 Mb, with more than 96% of assembled bases located on chromosomes. Gene annotation was assisted by RNA sequencing for the two sexes and four different life stages. Analysis detected 98% of the BUSCO (Benchmarking Universal Single-Copy Orthologs) gene set, supporting a high-quality assembly and annotation. In total, 40.1% (135.6 Mb) of the assembly is composed of repetitive sequences, and 14,946 protein-coding genes were identified. Although venom genes play important roles in parasitoid biology, their spatial distribution on chromosomes was poorly understood. Mapping has revealed venom gene tandem arrays for serine proteases, pancreatic lipase-related proteins and kynurenine-oxoglutarate transaminases, which have amplified in the P. puparum lineage after divergence from its common ancestor with Nasonia vitripennis. In addition, there is a large expansion of P450 genes in P. puparum. These examples illustrate how chromosome-level genome assembly can provide a valuable resource for molecular, evolutionary and biocontrol studies of parasitoid wasps.

Toxoplasma gondii ROP16 is a virulence factor that modulates immune reposes acting in cis and in trans., The protozoan pathogen Toxoplasma gondii co-opts host immunity by secreting various effector proteins into host cells. In this issue of JEM, Chen et al. (https://doi.org/10.1084/jem.20181757) report that T. gondii injects an effector called ROP16 without invasion to polarize macrophages toward M2 cells.

We have conducted OH 18 cm survey toward 141 molecular clouds in various environments, including 33 optical dark clouds, 98 Planck Galactic cold clumps (PGCCs) and 10 Spitzer dark clouds with the Arecibo telescope. The deviations from local thermal equilibrium are common for intensity ratios of both OH main lines and satellite lines. Line intensity of OH 1667 MHz is found to correlate linearly with visual extinction $A\rm_V$ when $A\rm_V$ is less than 3 mag. It was converted into OH column density by adopting excitation temperature derived from Monte Carlo simulations with one sigma uncertainty. The relationship between OH abundance $X$(OH) relative to H$_2$ and $A\rm_V$ is found to follow an empirical formula, \begin{equation} \nonumber \frac{X(\textrm{OH})}{10^{-7}} = 1.3^{+0.4}_{-0.4} + 6.3^{+0.5}_{-0.5}\times \textrm{exp}(-\frac{A_\textrm{V}}{2.9^{+0.6}_{-0.6}}). \end{equation} Linear correlation is found between OH and $^{13}$CO intensity. Besides, nonthermal velocity dispersions of OH and $^{13}$CO are closely correlated. These results imply tight chemical evolution and spatial occupation between OH and $^{13}$CO. No obvious correlation is found between column density and nonthermal velocity dispersion of OH and HI Narrow Self-Absorption (HINSA), indicating different chemical evolution and spatial volume occupation between OH and HINSA. Using the age information of HINSA analysis, OH abundance $X$(OH) is found to increase linearly with cloud age, which is consistent with previous simulations. Fourteen OH components without corresponding CO emission were detected, implying the effectiveness of OH in tracing the `CO-dark' molecular gas., Comment: 22 pages, 15 figures, 3 tables, accepted for publication in ApJS

Co-Eating, i.e., eating meals in the company of other people, has been widely recognized as good for both physical and mental health. However, the chances of co-eating have drastically decreased for families living separately and for older people living alone. To cope with this problem, we propose a framework of “asynchronous co-eating” that enables virtual co-eating through video message exchanges, which does not necessarily require people to eat simultaneously. This framework is aimed to maintain frequent communication between family members and promote ordinary types of co-eating when possible. To make this process easy for both older people and their distant family members, we designed a video message exchange scheme with an omnidirectional camera and a topic recommendation mechanism. With preliminary experiments, we obtained results that suggest our framework has the potential to be beneficial.

The solar heating system coupled with seasonal thermal energy storage (STES) is a promising solution to solve the seasonal mismatch between the solar energy supply and heating demand. A pilot solar heating system integrating with a 3000 m3 underground pit seasonal storage (UWPS) was built in Hebei, China. A TRNSYS model was established to analyse a new space heating management coupling with the mature district heating methods considering the outlet temperature of the UWPS. The simulation results showed that on the basis of maintaining the set indoor temperature 18 ± 1 ℃, the application of proposed space heating management to the UWPS-solar heating system is good and the solar fraction is 85.6% at the mean heat load of 40 W/m2, with the management of the fluctuation of the heat source, ambient temperature and the heating load.

Semi-volatile organic compounds (SVOCs) from diesel engine emissions have detrimental impact on air quality and human health. This study aims at characterizing the compositional SVOC emissions of a commercial diesel engine in both gaseous and particulate phases concurrently by using a two-dimensional Gas-Chromatography Time-of-Flight Mass-Spectrometry (GC × GC-ToFMS). 52 SVOCs including n-alkanes, n-alkyl-cyclohexanes and PAHs have been identified and quantified, and the contributions of diesel fuel and lubricating oil to the SVOC emissions have been evaluated under different engine loads by using the Positive Matrix Factorization (PMF) method. The distributional patterns of the gaseous SVOC emissions were found to be similar to those of the diesel fuel, while those of the particulate SVOC emissions were strongly associated with the lubricating oil. The PMF analysis illustrated that diesel fuel contributed to the SVOC emissions by nearly 70% at low load (442 ± 38 ug/kg·fuel), while lubricating oil dominated the SVOC emissions by over 50% at high load (595 ± 93 ug/kg·fuel). Additionally, we found that combustion by-products had nontrivial contributions to the SVOC emissions, increasing from 13% to 38% (from 83 ± 10 ug/kg·fuel to 443 ± 63 ug/kg·fuel) as load increased. The results obtained in this study could facilitate a better understanding of the SVOC formation mechanisms, and hence provide guidance for engine optimization towards SVOCs mitigation.

Aircraft engine soot emissions have been a growing concern because of their adverse impacts on global climate and human health. In this study, soot emissions from a Jet-Stirred Reactor (JSR) which could be considered as a basic aero-engine combustor were investigated under different combustion conditions including varying combustion pressures, fuel flow rates, and inlet air temperatures. The emitted soot particles were collected onto quartz fiber filters and then examined using high-resolution transmission electron microscopic (HRTEM) and Raman techniques. The HRTEM images and Raman spectra of the filter-laden soot samples were analyzed to determine the morphology and the nanostructure characteristics of the soot particles. It turned out that compared to the reference point, both high combustion pressure and high flow rate led to an increase in primary particle size. The HRTEM and Raman studies showed that there was no amorphous carbon present in the soot particles generated under high combustion pressure. Inlet air temperature exhibited a significant influence on the size and the morphology of soot particles; a large quantity of amorphous carbon with a lower degree of graphitization was generated under the low inlet temperature condition presumably due to poor fuel spray breakup and atomization in the JSR. In addition, we found that nanostructure parameters, such as soot fringe length and fringe tortuosity could be strongly dependent upon the residence time and the inlet air temperature.

Vegetation fractional coverage is an important indicator for the ecological environment quality in the mining area. The relationship between vegetation fractional coverage and topographical and climatic factors has been studied intensively. However, in coal mining areas, anthropogenic factors are closely linked to vegetation cover for the frequent production activities, and should be accounted into the driving factors. In this study, we analyzed the spatio-temporal changes of vegetation fractional coverage in Yangquan Mining Area, China. To explore the dominant factors affecting vegetation fractional coverage, geographical weighted regression models combining four natural factors (temperature [T], precipitation [P], elevation [DEM], and slope [Slope]), two anthropogenic factors (population density [Pop] and GDP density [GDP]), three distance factors (distance from roads [D-road], towns [D-town] and water sources [D-water]) were established. We analyzed the model results of four periods (2000, 2005, 2010, 2015) in three parts (exploited area, unexploited area, Yangquan Mining Area overall), respectively. The results indicated that the vegetation fractional coverage demonstrated an overall increasing trend. The vegetation fractional coverage was higher in the unexploited than that in the exploited areas, and the differences increased over time. The impact intensity of nine factors in descending order was Pop > GDP > P > T > D-road > D-town > DEM > D-water > Slope. T, P, DEM, D-road, and D-town were positive factors, whereas Pop and GDP were negative factors. Between 2000 and 2010, the vegetation fractional coverage trends were mainly influenced by anthropogenic factors, whereas in 2015, natural factors exceeded anthropogenic factors as the dominant factors. Present study concluded that anthropogenic factors had a non-negligible negative impact on vegetation cover in mining areas. However, the impact of anthropogenic factors on vegetation presented a decreasing trend. Natural factors have exceeded anthropogenic factors as the dominant factors in recent years. This study provides a theoretical support for future ecological protection and restoration in the Yangquan Mining Area.

Ultrasonic vibration has been found to play a significant role in promoting surface nano-crystallization of sapphire in a liquid aluminum bath. And the distribution of the vibration field is critical in controlling the modification procedure. Here, distribution of the ultrasonic vibration in a liquid aluminum bath was investigated by finite element method (FEM). Effects of shape of the ultrasonic horn and distance between the horn and the sapphire plates were investigated. It was found that the ultrasonic vibration density is high in the area adjacent to the ultrasonic horn. The distance between the horn and the plates significantly influence the vibration distribution. And the vibration density decreased significantly at the liquid/solid interface, indicating obvious energy absorption there. Vibration energy grads can be formed on sapphire surface. And this phenomenon shall be used to achieve different aims.

Phenological responses of terrestrial ecosystems to climate extremes are of growing concern due to the increasing frequency and intensity of extreme climatic events associated with climate change which will in turn affect vegetation seasonality more than gradual changes. However, studies are rare in arid mountain regions where plant development is commonly regulated by both temperature and precipitation. To better understand how arid mountain (AM) ecosystems may respond to climate anomalies, we identified recent extreme climatic events (including intense warming, severe drought, and excessive wetness), and analyzed spring onset of vegetation growth in the Qilian Mountains of northwestern China. Phenological sensitivity was assessed from satellite-based data as departures from maps displaying mean onsets of growth for years 1983–2013. Our results revealed remarkable shifts in the start date of the growing season (SOS) under climate extremes, with different responses depending on ecosystem and altitude. Recent warming induced a general advancement of SOS. Higher spring temperatures enhanced the accumulation of heat needed for budburst and leaf expansion; elevated winter temperatures reduced the chilling days before bud dormancy release, significantly decreasing the risk of freezing injury in AM plants. Changes in SOS observed in this study suggested that AM plants may have relatively low chilling requirement for dormancy release. Contrary to warming, a drought resulted in a widespread delay in spring phenology, with sensitivity peaking over a shrubland ecosystem at medium elevations. This result demonstrated that subalpine shrubs were most susceptible of the studied ecosystems to hydroclimatic extremes, highlighting the great importance in this biome of concerns. Moreover, during the year when multiple extreme events (e.g. intense warming and heavy rainfall) coincided, their combined influence appeared to arise from synergistic mechanisms that are in urgent need of further research.

Comparative tests were conducted to investigate the flame spread characteristics of a typical hydrocarbon fuel mixture (0# diesel) and a typical pure alcohol fuel (n-butanol) in a reduced-scale (1:10) tunnel model. Experimental data with regard to flame spread appearance, flame spread rate, temperature profile, and subsurface convection flow were obtained and discussed in this study. Results showed that: (1) The diffusion flame of n-butanol propagated in a forward-stop-forward pattern, while diesel fuel pulsated in a forward-back-forward manner with less stability. The flash flame of diesel appeared periodically with significant higher spreading velocity than the enduring flash flame of n-butanol. (2) The average main flame spread rate of n-butanol was faster than that of diesel fuel, whereas the transient flame spread rate showed an opposite trend. (3) No sensitive difference was found in surface temperature profile between two fuels, but n-butanol retained higher vertical temperature due to its higher flame height than diesel. The infrared images discovered that the subsurface convection flow of diesel had a larger size and noticeable temperature gradient. Diesel burned with more luminous flame and denser soot than n-butanol, owing to its more complex fuel components.

Close-to-nature forest management has been proposed as an effective method for improving the quality of plantation forests. Knowledge of spatial distribution patterns, structure, and succession trajectories in natural forests can provide guidelines for the establishment of close-to-nature forest plantations. Such knowledge is lacking in natural spruce (Picea crassifolia) forests in the Qilian Mountains of China, impeding the establishment of production forests. We conducted a case study in the Qilian Mountains to analyze the relationships between the naturally-formed forest patches and terrain factors, spatial heterogeneity of stand characteristics, and stand structure following harvesting disturbance. Our results suggested that spruce plantations will be effective on the N, NE, and NW slopes, at elevations between 2700 and 3300 m, and on slopes ranging from 15° to 45°. Further, planted forest patches should occupy 64% of the slope area on semi-shady slopes (NE, NW). Spatial patterns in the studied forest exhibited a strong scale-effect, and an area of 0.25 ha could be used as the most efficient plot scale for the management of spruce plantations. Partial logging is an effective method for the conversion of spruce planted forests into nearnatural forests, and the intensity of partial logging can be determined from the negative exponential function relationship between stand density and DBH. Our results provided critical information for the development of spruce plantations and conversion of existing plantations.

This paper reports the study of a conceptual gasoline Internal Combustion Engine (ICE) using scroll type rotary device rather than conventional piston as the main engine component. The proposed innovation engine adopts Humphrey Cycle to maximise the power performance of ICE. A performance comparison of the Humphrey Cycle, Otto cycle and Brayton cycle has been conducted and studied. The effects of using different designed compression ratio under variable expansion ratio have been investigated, which identify the optimal operational conditions under different compression/expansion ratio of the engine. Optimal performance can be achieved under the compression/expansion ratio at 2:1/4.8:1, 4:1/7.4:1, 6:1/9.9:1, 8:1/11.8:1 and 10:1/14.1:1, when the energy efficiency of the system can be respectively achieved at 42.22%, 49.13%, 52.82%, 55.08% and 56.96%. A case study has been conducted to study the performance of small-scale scroll-type rotary ICE. Results pointed out under designed compression ratio from 2:1 to 10:1 the effective power from the system ranges from 3.343 to 19.01 kW. The analysis of fuel efficiency pointed out the Brake Specific Fuel Efficiency (BSFC) of the scroll-type rotary engine burning gasoline ranges from 130.5 to 148.5 g/kWh, which improve the fuel efficiency by 28.02% and 65.89% compared to that of the conventional gasoline engine.

It has been widely reported that natural gas dual-fuel combustion (DFC) can achieve much lower soot emissions in contrast to conventional diesel combustion (CDC). Thus, using low-pressure direct injection (LPDI) systems could be an alternative for current high-pressure common rail injection systems, which would significantly reduce the system cost. The present study aimed at exploring the feasibility of LPDI (low to 200 bar) for natural gas DFC in combination of the advanced low temperature combustion technology. The comparative study between natural gas DFC and CDC were carried out. For natural gas DFC, larger advanced injection timing was used to realize low temperature combustion and achieve long ignition delay in order to counteract the negative impact of relatively poor atomization quality caused by the low injection pressure. At DFC mode, higher CO and THC emissions were observed compared to CDC in the cases without EGR. However, DFC was much less sensitive to EGR rate and injection pressure. Natural gas DFC could break the trade-off between NOx and soot emissions, which could achieve low soot and NOx emissions (lower than Europe VI standard: 0.4 g/kW·h) simultaneously at the 42% EGR rate and the 200 bar injection pressure.

A number of major studies have demonstrated that the SVOC (Semi-volatile organic compounds) within engine emissions derive predominantly from unburned fuel and lubricants, and are a major contributor to primary atmospheric aerosol containing thousands of organic compounds. The GC × GC-ToF-MS (2 dimensional Gas Chromatography – Time of Flight – Mass Spectrometry) comprehensive analytical technique was utilized in this study, to resolve the complex mixtures and characterize the SVOC content in eight different commercial lubricants, including 5 W30 synthetic and semi-synthetic, mineral and base oil. In order to quantify the aliphatic isomers, which comprise the largest component of the lubricants, a TIC-M.Q./Mass (Total ion current ratio to the molar quantity/mass) method has been developed. The TIC intensity was observed to be proportional to the molar quantity of n-alkanes for carbon number C25. Additionally, the TIC intensity of the alkyl-cyclohexanes under the identical retention indices were found to have an equivalent response to those of the n-alkanes, showing that the quantitative calibrations derived for the n-alkane series could be applied to estimate the concentrations of isomeric aliphatic compounds with similar molecular weight. Furthermore, a mesh method was introduced to group the alkane species (n-alkanes, branched alkanes and cyclic alkanes etc.), combining with the use of a soft EI (electron impact) ionization (14 eV) to retain the distinct identity of the isomers with less fragmentation, which allowed the TIC-M.Q./Mass methodology to integrate all the constitutional isomers present in the lubricating oil samples. By utilizing this methodology, compositions from different samples were comprehensively compared, leading to the following conclusions: 1) the synthetic and semi-synthetic oils contained a larger abundance of HMW (high molecular weight) aliphatic compounds (carbon number C24–C29), while those in the LMW (low molecular weight range, carbon number C18–C25) were predominant in the mineral and base oil; 2) cycloalkanes were predominant in the synthetic and semi-synthetic oils; whereas the branched alkanes were more prominent in the mineral and base oils; 3) for lubricants used for a short period, a slight increase of LMW compounds was observed, while the HMW compounds underwent a decrease, whereas, there was an overall mass reduction for all the aliphatic compounds detected in the oil samples used for six-months.

The main objective of this study is to understand the mechanism of the spray collapse during flash boiling using multi-hole injectors. The spray characteristics of a five-hole gasoline direct injection (GDI) injector were investigated over a range of ambient pressures and fuel temperatures with high-speed imaging and phase Doppler particle measurement techniques. Spray collapses under both flash-boiling and non-flash-boiling (elevated ambient pressure) conditions were observed, but due to different mechanisms. In order to prove that the vapor condensation near the nozzle exit is the primary cause for the collapse under flash boiling conditions, careful analysis to examine the two necessary conditions for vapor condensation in multi-jet flash-boiling sprays was conducted: (1) existence of sub-cooled droplets and (2) existence of saturated vapor. The first condition could be supported by the previous studies and the other condition was numerically and experimentally demonstrated in the present study. It was found that the local static pressure significantly increased at the balance position, where the radial momentums of the droplets and vapor issued from the five holes could be counteracted. The increased static pressure was beyond the local saturation pressure, fulfilling the condition for vapor condensation. Furthermore, the bimodal size distribution under flash boiling conditions and the condensation core inside the spray observed under much reduced ambient pressure also prove the occurrence of vapor condensation at the nozzle exit.

Elevator evacuation has attracted increasing attention as an efficient transport method in high-rise buildings, which is one of the most complex and interesting areas of modern fire research. Throu...

This study proposed a new method for measuring planar Sauter Mean Diameter (SMD) of multi-component fuel spray using a SETScan optical patternator, a particle imaging velocimetry (PIV) and a previously validated evaporation model. Malvern experiments were conducted to obtain line-of-sight SMD, which could be considered as a reference value to compare with the planar SMD due to spray symmetry. The SETScan patternator provided the planar local surface area densities at two axial cross-sections of the spray (250 mm and 400 mm below the nozzle), and the total surface area was calculated by integrating local surface area density over the concerned cross-section area. The PIV was used to measure droplet velocities at the same cross-sections, so that the time for the droplets passing through the laser sheet of the patternator (concerned cross-sections) could be determined. The total droplet volume captured within the laser sheet was then calculated by multiplying the time and the initial flow rate. The planar SMD at the cross-section is the quotient of the total volume divided by the total surface area. However, there existed a noticeable discrepancy between the Malvern SMD and planar SMD at the lower cross-section due to the evaporation being ignored. Therefore, an evaporation model was adopted to correct the total droplet volume at the lower cross-section. In particular, the evaporation model based on the droplet heat and mass transfer incorporates the non-ideality consideration for multi-component fuel evaporation by determining the activity coefficients of fuel components. It turned out that the Malvern SMD was close to the proposed planar SMD at the upper cross-section (250 mm) for all the test fuels without evaporation consideration. For lower cross-section (400 mm), the proposed planar SMD modified by incorporating an evaporation model, fit the line-of-sight SMD value better than the planar SMD without evaporation correction. The planar SMD method provides relatively complete information on a planar basis and can be used for characterizing non-symmetry sprays as well.

This paper explored the transition of flow in an elevator shaft and analyzed how the gas flow is affected by the moving elevator car during a building fire. A 3D model was built through ANSYS Fluent, the elevator motion was resolved through dynamic mesh theory. Flow fields in the elevator shaft were compared to describe the flow transition. Pressure distributions were applied to explain how the transition was accomplished and how the gas flow was influenced by the moving elevator car. Chemical reaction in the room released large amounts of CO2 and CO. The change in CO2 and CO concentration in the shaft was applied to measure the influence of elevator motion on the flow. At the start of the simulation, the gas moved slowly and smoothly upwards in the area between the elevator car and the top. As the elevator car moved, this area shrank steadily and significantly. In the end, this area disappeared and the transition of flow status in the entire shaft had been accomplished. The elevator motion decreased the pressure inside the shaft as well as the lobby. While the elevator car moved upwards with 1.75 m/s, the pressure in the lobby was decreased by 142.9% while the CO2 and CO concentration was increased compared to the case with still elevator cars, which indicated that more fire smoke flew into the lobby when the elevator car moved in the shaft.

In order to remove Microcystis aeruginosa (M. aeruginosa) and hexavalent chromium Cr (VI) from wastewater, attapulgite was modified with hydrochloric acid and mixed with ferroferric oxide (Fe3O4) to prepare magnetic composite material (MCM), which could be utilized to flocculate M. aeruginosa and adsorb Cr (VI) effectively, and could be taken out from water easily under external magnetic field. The experimental results showed that the MCM could precipitate the M. aeruginosa with the removal rate over 96% within 10 min, and in the meantime, it could efficiently adsorb Cr (VI) with the removal rate of Cr (VI) reaching 95% within 5 min. The adsorption of Cr (VI) by MCM conforms to the pseudo-second-order kinetic model, and the isotherm model for the adsorption of Cr (VI) conforms to the Langmuir equation. The adsorption amount of Cr (VI) decreased with the increase of temperature, indicating that the adsorption process of Cr (VI) was exothermic. This work therefore proposes a new approach for treatment of wastewater containing M. aeruginosa and Cr (VI), and also elucidates the adsorption properties of the applied material.

A dual-species sensor based on scanned-wavelength-modulation spectroscopy (scanned-WMS) with the 2f/1f detection is developed for calibration-free CO and NH3 detection in high-temperature environments. A 2.3 μm distributed feedback (DFB) diode laser was used to exploit the CO and NH3 lines centred at 4300.7 cm−1 and 4301.13 cm−1, respectively. The DFB laser was scanned across the target absorption lines at 100 Hz with fast sinusoidal modulation at 5 kHz. The spectral fitting strategy was employed to least-square fit the simulated and measured WMS-2f/1f spectra. The integrated absorbance of target transitions inferred from the scanned-WMS-2f/1f spectral fitting was used to determine the species concentration. The performance of the developed sensor was validated by simultaneously measuring species concentrations under various temperatures (300–700 K) and at 1 atm in a high-temperature gas cell. The noise equivalent absorption (NEA) coefficient of 3.5 × 10-6 cm−1 for CO and 4.9 × 10-7 cm−1 for NH3 was achieved at 700 K with an absorption path length of 20 cm. The developed dual-species sensor has the potential to be applied in the exhaust of practical combustion systems such as NH3 monitoring for NOx abatement in selective catalytic reduction (SCR) aftertreatment and CO sensing for optimizing combustor efficiency.

A growing body of literature emphasizes important roles of microbial community in driving a variety of soil processes including soil respiration (Rs). However, empirical evidence for microbial regulation of Rs is still lacking in field observations. Here, we used an in situ approach to explore microbial mechanisms for the variability in Rs across elevational gradients in an alpine forest of northwestern China. Our results revealed significant differences in abundance, diversity, and composition of both bacterial and fungal community, and the variability in microbial communities was mainly explained by climatic (mean annual precipitation) and soil (C:N ratios, available phosphorus, and nitrate nitrogen) variables. Elevation also had a significant effect on Rs, and the inclusion of microbial community composition rather than microbial abundance or diversity greatly improved the prediction of Rs dynamics along elevational gradients. Other soil properties such as C:N ratios and pH were also significantly correlated to Rs, however, they were not able to account for the variability in Rs explained by microbial community composition. Our study further identified Alphaproteobacteria and Acidobacteria as the major microbial taxa driving changes in Rs along elevational gradients, with important implications for the use of these taxa to predict soil C feedbacks under climate change scenarios in alpine forest ecosystems. Overall, our findings provided important empirical evidence for microbial regulation of Rs in field observations.

The development of engine waste heat recovery technologies attracts ever increasing interests due to the rising strict policy requirements and environmental concerns. This paper presented the study of engine coolant and exhaust heat recovery using organic Rankine cycle (ORC). Eight working fluids were selected to evaluate and compare the performance of the integrated waste heat recovery system. Rather than the conventional engine ORC system mainly focusing on the utilization of exhaust energy, this work proposed to fully use the engine coolant energy by changing the designed parameters of the ORC system. The case study selected a small engine as the heat source to drive the ORC system using a scroll expander for power production. The evaluation results suggest that under the engine rated condition, the solution to fully recover the engine coolant energy can achieve a higher power generation performance than that of the conventional engine ORC system. The results suggest that adding a recuperator to the ORC system can potentially improve the system performance when the working fluids are dry and the overall dumped heat demand of the system can be reduced by 12% under optimal conditions. When the ORC evaporating and condensing temperature are respectively set at 85°C and 30°C, the integrated engine waste heat recovery system can improve the overall system efficiency by 9.3% with R600, R600a or n-Pentane as the working fluid.

This paper presents the study of four different engine coolant and exhaust heat recovery Organic Rankine Cycle systems using R245fa as working fluid and scroll expander as expansion machine. The parametric investigation suggested the fluid superheating temperature has limited influence on the simple structured ORC system (ORC_sim) with overall efficiency about 6.2% and average produced power around 0.59 kW under engine rated condition. The maximum rotational speed of the scroll expander is around 4000 rpm under different ratio of coolant and exhaust ratio of the Yanmar engine (6.8 kW), which means the designed ORC system can be easily used for electricity generation by directly connecting expander shaft to a conventional electrical generator. The BSFC reduction ratios of ICE + ORC_sim, ICE + ORCR_1 and ICE + ORC_pre under engine rated power are respectively 6.1%, 7.4% and 5.2%. And the overall effective energy efficiency by integrating ORC_sim, ORCR_1 and ORC_pre to the ICE can be improved by 6.5%, 8.0% and 5.4% under engine rated power condition.

Biodiesel is a promising alternative fuel for diesel engines. Polyoxymethylene Dimethyl Ethers (PODE), which features high cetane number, low viscosity and high oxygen content, is often used as a fuel additive. In this study, PODE is blended with biodiesel as a major components of the fuel to improve the low-temperature flow properties and the viscosity of biodiesel, aiming to achieve superior engine emission characteristics and efficiency compared with the baseline operation working with neat diesel. The experiments are conducted using diesel (D100), biodiesel (B100) and biodiesel/PODE blend fuel (B85P15) in a direct-injection diesel engine operating at different loads. Combustion data, fuel consumptions and gas emissions are measured. The results show that the engine operates smoothly with B100 and B85P15, at high load B85P15 has obviously higher diffusion combustion heat release rate, and the total combustion duration of B85P15 is 5 CAD shorter than that of D100. B85P15 produces the lowest soot emissions (

As PAHs (Polycyclic Aromatic Hydrocarbons) are the main precursor of soot formation during the combustion, the investigation of PAHs formation is essential for the understanding of the soot formation and soot reduction in combustion. In this study, a specially designed burner and the corresponding fueling system was used to stabilize a laminar diffusion flame of n-heptane up to 3.0 bar before it becomes unstable. Using the combination of LII (Laser Induced Incandescence) and LIF (Laser Induced Fluorescence) techniques, the PAHs and soot formation and their distributions in the studied flames were obtained and explained. The results showed that PAHs were almost surrounded by soot and were present in the lower part of the flame. Moreover, the integral soot and PAH intensities exhibited a power law dependence on the pressure, being proportional to pn with n of 1.38 ± 0.32 and 1.49 ± 0.25 respectively under the pressure range of 1.0–3.0 bar.

The front velocity of transient ceiling becomes an important consideration for tunnel fire safety, which provide a prediction of travel time of ceiling jet. The previous model predictions of ceiling jet front velocity were developed in a natural ventilation tunnel. The effect of central mechanical exhaust system on the ceiling jet front velocity have not been revealed in the past. This work experimentally revealed smoke front velocity of ceiling jet in a tunnel under the effect of central mechanical exhaust system, and the relative location between fire source and central exhaust system were considered. It is found that, the relative direction of fire source and ceiling mechanical extraction opening has a great influence on the smoke front velocity of ceiling jet. Some previous models (Jones, Benjamin, and CFAST) all overestimate the smoke flow velocity of ceiling front; the predicted ceiling jet front velocity deduced by Jones and Benjamin have the maximum excessive deviation of about 60% and 98%, respectively, but the CFAST model is closer to the measurements with relatively higher front velocity. The Hinkley’s model can be well used to predict it with different central mechanical exhaust system.

Soil moisture controls the functioning of semi-arid ecosystems. The response of soil moisture to forest stand thinning determines planting density and sustainability of forest development. However, consequences of stand thinning are poorly known in semi-arid ecosystems of the Qilian Mountains of China. We investigated long-term effects of three thinning intensities in Picea crassifolia plantations on soil hydrological responses and soil moisture dynamics at 10, 20, 40, 60, and 80 cm depths, and compared them to those of a natural Picea crassifolia forest. Results revealed that soil hydrological response may be temporarily modified by thinning according to changes in canopy structure, precipitation properties, and antecedent soil moisture conditions. Soil moisture in natural forest rapidly infiltrated into deep soil, which greatly improved the efficiency of precipitation use. Thinning significantly increased the capacity for soil infiltration, and moderate thinning intensity may be conducive to deep soil-water recharge. Soil moisture content changed drastically after thinning, with a significant decrease near-surface (10 cm), and a significant increase in sub-surface (60 and 80 cm) soil. High planting density was the main cause of severe soil moisture deficits in the long-term, but it could be mitigated by 20–40% thinning (∼3139 trees ha−1). Changes in precipitation patterns that include larger but less frequent rainfall events during the growing season will benefit the growth of vegetation planted at high densities in this semi-arid region.

Aviation Piston Engines for small general aviation aircrafts are currently facing a transition from being powered by AVGAS (aviation gasoline) to being powered by heavy fuels (diesel or kerosene). The present study compared the combustion and emission characteristics of diesel, aviation kerosene rocket propellant 3 (RP-3) and RP-3-pentanol blends in a single cylinder compression ignition (CI) engine. Heat release rate, indicated thermal efficiency, ignition delay, combustion duration, and coefficient of variation (COV) of indicated mean effective pressure were experimentally determined to reflect the engine combustion performance. The results demonstrated the feasibility of RP-3 and its mild pentanol blend (20% by volume) in modern CI engines whilst further optimisation of the injection strategy is needed if a higher ratio of pentanol (40% by volume) is used. The discrepancy in terms of combustion and emissions between diesel, RP-3 and its pentanol blends are appreciable, especially for ignition delay, combustion duration and soot emissions. Compared with diesel, RP-3 improved the indicated thermal efficiency by 1.4–12.4%, but pentanol addition decreased that by 1–6.5%. RP-3 and its pentanol blends reduced the soot emissions by nearly an order of magnitude at high engine loads compared with diesel without evident impact on nitrogen oxide (NOx) emissions. Meanwhile, Carbon monoxide (CO) and total hydrocarbon (THC) emissions of RP-3 and its pentanol blends experienced a significant increase at low loads, but CO showed a slight decrease at high loads.

The resurgence of aviation heavy fuel engines (HFEs) and the single fuel concept policy make it important to investigate the application of kerosene in aviation compression ignition engines. From the experience of automotive engines, biofuels, in particular higher alcohols, may offer better combustion and emission characteristics for HFEs. In this study, the combustion performance was analyzed in a commercial aircraft compression ignition engine burning diesel as a baseline fuel and Chinese aviation kerosene fuel (RP-3) blended with pentanol (so-called second generation biofuel) with different blending ratios. The injection timing as the most critical operational parameter was swept from 17 to 23°CA BTDC (crank angle before top dead center) under constant engine speed (1600 rpm) and fixed injection pressure (60 MPa). The indicated thermal efficiency of kerosene–pentanol blend (K60P40) was higher than those of all other test fuels, and the advancement in injection timing caused an increase in combustion te...

Currently, general aviation aircrafts have growing demand for internal combustion engines burning heavy fuels (i.e. diesel or kerosene) due to the concerns on the safety, costs and availability of aviation gasoline (AVGAS). The application of heavy fuels requires the change of combustion mode from pre-mixed mode to diffusion mode, which will inevitably increase the particulate matter (PM) emissions as incomplete combustion products. In this work, the size-resolved number concentrations of the PM emissions emitted from an internal compression ignition engine burning diesel, RP3 and Fischer-Tropsch (FT) kerosene were studied by a Scanning Mobility Particle Sizer Spectrometer (SMPS). An opacimeter was utilized to measure the opacity of the soot emissions (linearly related to the soot mass), which was in consistent with the SMPS data. Results demonstrated that the FT fuel produced the lowest PM emissions due to absence of sulfur and aromatic contents. Diesel turned out to have the greatest ‘sooting’ tendency and produced more accumulation mode PM in number than FT fuel by a factor of four, and more PM in mass by approximately three times. Moreover, the effects of fuel types and engine operational parameters were quantified in a systematic manner by adopting the Response Surface Method (RSM) in Design of Experiments (DoE). According to the ANOVA (Analysis of Variance), the DoE derived model was statistically significant and demonstrated that the engine load was the dominant factor for soot generation, followed by injection pressure and fuel types. Relevant combustion parameters and their link with PM emissions were further discussed, illustrating that atomization process had great impact on the ignition delay and thus affected soot generation.

It is well known that the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL/TNFSF10) is specifically expressed in various tumor cells, but less or no expression in most normal tissues and cells. While TRAIL engages with its native death receptors, TRAIL receptor 1 (TRAIL-R1) or 2 (TRAIL-R2), usually elicits the tumor cell death by apoptosis. In this study, we report that a novel humanized monoclonal antibody against TRAIL-R2 (named as zaptuzumab) well remain the biological activity of the parental mouse antibody AD5-10 inducing cell death in various cancer cells, but little effect on normal cells. Zaptuzumab also markedly inhibited the tumor growth in the mouse xenograft of NCI-H460 without toxicity to the liver and kidney, and the efficacy of tumor suppression was increased significantly while it combined with cis-dichlorodiamineplatinum. Especially, 131 I-labeled zaptuzumab injected into mouse tail vein specifically targeted to the xenograft of the lung cancer cells. Confocal analysis showed that zaptuzumab bound with TRAIL-R2 on cell surface could be quickly internalized and transferred into the lysosome. Furthermore, zaptuzumab possessed a high level of antibody-dependent cytotoxicity as well as complement-dependent cytotoxicity. Study on the mechanisms of cell death induced by zaptuzumab showed that it efficiently induced both caspase-dependent apoptosis and autophagic cell death. These data suggest that the humanized anti-TRAIL-R2 monoclonal antibody or the second generation of the antibody may have an important clinical usage for cancer immunotherapy. © 2017 IUBMB Life, 69(9):735-744, 2017.

Fibrous filters are commonly used for aerosol purification and sampling. The filtration efficiency has been extensively studied using standard aerosol generators, yet the literature on experimental data and theoretical study concerning the filtration of agglomerates from real engines remains scarce. A filtration efficiency test system was developed to determine the filtration efficiency of two types of filters (uncoated and fluorocarbon coated) loaded by particulate matter (PM) emissions from a gasoline direct injection (GDI) engine. The experimental results showed that the filtration efficiency in terms of PM mass and number increased over time for both types of filters. The fractional efficiency (penetration efficiency) curves for the test fibrous filters rendered a U-shaped curve for particle sizes from 70 to 500 nm, and the most penetrating particulate size (MPPS) decreased over time. A small fraction of accumulation mode particles with the size between 70 nm to 500 nm penetrated the filters while almost all nucleation mode particles with the size below 50 nm were captured by the filters. The filtration efficiency derived from an empirical model based on classical single-fiber theory for laden filters generally agreed with the experimental data for the first 500 s, but suffered a significant deviation by approximately one order of magnitude at 948 s. A better estimate of the filtration efficiency trend with the maximum deviation of about 20% (except for large particles at the high end of the measurement spectra) was obtained by using a revised model which incorporates the effects of the increase in filter solidity, local velocity, dynamic shape factor and effective total length of fibers during the filtration process. © 2017 American Association for Aerosol Research

The size-resolved counting efficiency of an in-house ultrafine condensation particle counter (IUCPC) being challenged by sodium chloride (NaCl) particles was experimentally determined with a reference electrometer TSI 3068B. The influence of several operational parameters including the saturator temperature (35 to 45 ℃), the condenser temperature (10 to 25 ℃), the capillary sample flow rate (30 to 60 mL/min) and the total flow rate (300 to 400 mL/min) on the cut-off size D50 (particle diameter with 50% counting efficiency) was investigated using response surface design of experiments (DoE). Thirty one test points with varying operational conditions including 7 replicated test points were performed to evaluate the primary effects of operational parameters and their interactive effects on the cut-off size D50 of the IUCPC. The results indicated that the saturator temperature and the condenser temperature had a greater impact on the cut-off size D50 than the capillary flow rate and the total flow rate. CFD simulation demonstrated that high capillary flow rate in the IUCPC could induce a wider diffusion zone for the core aerosol flow, making more particles enter low supersaturation area near the wall. According to the ANOVA (analysis of variance), the most influential factor for the cut-off size D50 was the condenser temperature, followed by the saturator temperature, the total flow rate and the capillary flow rate. Some interactive effects from combinations of factors on the D50 are also significant. R-squared value of 0.9176 implied that the ultimate model for the IUCPC D50 consistently fits the experimental results.

Ultrafine particle emissions from Gasoline Direct Injection (GDI) and Port Fuel Injection (PFI) vehicles under the New European Driving Cycle (NEDC) were measured by using the Differential Mobility Spectrometer 500 (DMS 500) for size distribution information and Transmission Electronic Microscopy (TEM) for morphological analysis. The first phase of the ECE 15 cycle (representing the urban driving condition) within the NEDC was examined to evaluate the cold start effect on particulate matter (PM) emissions. Even though the ECE 15 cycle1 only occupies 1/6th of the time of the NEDC, the cold start emissions accounted for more than 50% of the total particle number for GDI vehicles and approximately 70% for PFI vehicles. Further analysis in terms of the Count Medium Diameter (CMD) of the PM emissions is also discussed. A linear regression method was adopted to analyze the correlation between PM emissions and vehicle parameters. For GDI vehicles, acceleration demonstrated a strong correlation with PM emissions, particularly under warm start conditions. The effects of the after treatment device Three Way Catalyst (TWC) on PM emissions was also investigated.

The counting efficiency of an in-house laminar flow Condensation Particle Counter (CPC) was investigated experimentally. The CPC was challenged by different sources of particles (ambient particles, and combustion particles generated from CH4 and C2H4), and the counting efficiency of the in-house ultrafine CPC (IUCPC) was obtained by comparing particle concentration data measured by the IUCPC with that measured by a reference instrument, TSI CPC 3775. The counting efficiency is closely related to the contact angle (an indication of the wettability of particles by the working fluid) and the combination of the saturator and the condenser temperatures. The particles from different sources appeared to have different contact angles, in other words, different wettability by the working liquid.

The planar surface area and the spray nonuniformity are important parameters for determining spray evaporation characteristics. In this study, the effects of fuel compositions and two process variables (the injection pressure and axial distance from the measurement plane to the nozzle exit) on both planar surface area and spray nonuniformity were experimentally investigated via statistical extinction tomography. The design of experiment (DoE) was adopted to design the experiment procedure and analyze the data in a systematic way by establishing quadratic mixture models crossed with a linear process model. The planar surface area and the spray nonuniformity were calculated from spatial distributions of surface area density at three measurement planes, which were obtained by using an optical patternator SETSCAN OP-200. The results demonstrated that the axial distance had a significant influence on the planar surface area; whereas, the injection pressure did not show a definite trend for all the test fuels, yet the interaction between the injection pressure and fuel compositions played a noticeable role in determining the planar surface area. The spray nonuniformity was primarily influenced by injection pressure, while it exhibited little dependence on the axial distance. In general, the higher the injection pressure, the higher the spray nonuniformity would be. Fuel composition had an appreciable effect on the spray nonuniformity as well. The DoE-derived models were statistically significant according to analysis of variance analysis, and the optimal values in terms of planar surface area and spray nonuniformity were determined via numerical optimization.

DNA methylation is a key epigenetic modification which confers phenotypic plasticity and adaptation. Cyst-forming strains of Toxoplasma gondii undergo tachyzoite to bradyzoite conversion after initial acute infection of a host, and the reverse conversion may occur in immune-suppressed hosts. The formation of m5C is catalyzed by DNA methyltransferase (DNMT). We identified two functional DNA methyltransferases, TgDNMTa and TgDNMTb, in T. gondii that may mediate DNA methylation. The recombinant proteins showed intrinsic methyltransferase activity; both have higher transcription levels in bradyzoites than that in tachyzoites. We performed genome-wide analysis of DNA methylation in tachyzoites and bradyzoites. The results showed more methylation sites in bradyzoites than that in tachyzoites. The most significantly enriched GO-terms of genes with DNA methylation were associated with basal cellular processes such as energy metabolism and parasite resistance to host immunity. Tachyzoite proliferation in parasitophorous vacuoles (PV) can be inhibited by the DNA methyltransferase inhibitor 5-azacytidine, a chemical analogue of the nucleotide cytosine that can inactivate DNA methyltransferases. These findings provide the first confirmation of DNA methylation in T. gondii.

Outdoor wind is one of the important driving forces of fire smoke movement in high-rise buildings. This paper investigates the smoke spread velocity along a corridor induced by an adjacent compartment fire with outdoor wind. Based on momentum and mass conservation laws, a theoretical model predicting the smoke spread velocity was developed. Reduced-scale experiments were performed for model validation. Correlations for smoke spread velocity in the corridor under the effect of outdoor wind were proposed. It is found that the initial velocity can be very well predicted according to the stratification stability of smoke with the criterion of Fr. Moreover, the velocity profiles along the corridor decay exponentially.

To reduce the unnecessary gene clusters in the taxol-producing fungus Pestalotiopsis microspora, we report the development of an effective DNA deletion method that relies on a deletion cassette constructed with the Gateway-technique and overlap extension PCR, using the orotidine 5′-phosphate decarboxylase as recyclable marker for selection. By this approach, two adjacent DNA sequences can be sequentially deleted in a single transformation mediated by Agrobacterium tumefaciens, resulting in the deletion of a large DNA fragment. Additionally, the selection marker is spontaneously eliminated in this process. We used this method to successfully remove the mus53 locus of P. microspora.