Advances in regenerated cellulosic aerogel from waste cotton textile for emerging multidimensional applications.

Rapid development of society and the improvement of people's living standards have stimulated people's keen interest in fashion clothing. This trend has led to the acceleration of new product innovation and the shortening of the lifespan for cotton fabrics, which has resulting in the accumulation of waste cotton textiles. Although cotton fibers can be degraded naturally, direct disposal not only causes a serious resource waste, but also brings serious environmental problems. Hence, it is significant to explore a cleaner and greener waste textile treatment method in the context of green and sustainable development. To realize the high-value utilization of cellulose II aerogel derived from waste cotton products, great efforts have been made and considerable progress has been achieved in the past few decades. However, few reviews systematically summarize the research progress and future challenges of preparing high-value-added regenerated cellulose aerogels via dissolving cotton and other cellulose wastes. Therefore, this article reviews the regenerated cellulose aerogels obtained through solvent methods, summarizes their structure, preparation strategies and application, aimed to promote the development of the waste textile industry and contributed to the realization of carbon neutrality.

A triple-crosslinking strategy for high-performance regenerated cellulose fibers derived from waste cotton textiles.

Regenerated cellulose fibers has attracted increasing attention for high-grade textile raw materials and industrial textiles, but the low mechanical property caused by differences in regenerated raw materials and production levels limits its commercial application in the product diversity. Herein, we proposed a novel triple-crosslinking strategy by coupling with hydrogen bonds, chemical crosslinking, and internal mineralization from multiple pulsed vapor phase infiltration (MPI) to improve the mechanical performance of regenerated cellulose fibers. A binary solvent composed of ionic liquid (IL) and dimethyl sulfoxide (DMSO) is used to dissolve waste cotton textile and then wet spinning. Dual-crosslinking is firstly achieved by coupling glutaraldehyde (GA) and cellulose reaction. Subsequently, a metal oxide is intentionally infiltrated into inner cellulosic through MPI technology to form a third form of crosslinking, accompanied by the ultra-thin metal oxide nano-layer onto the surface of regenerated cellulose fibers. Results showed that the triple-crosslinking strategy has increased the tensile stress of the fiber by 43.57 % to 287.03 MPa. In all, triple-crosslinking strategy provides a theoretical basis and technical approach for the reinforcement of weak fibers in waste cotton recycling, which is expected to accelerate the development of the waste textile recycling industry and promote of the added-value of regenerated products.

Three-state coherent control using narrowband and passband sequences.

In this work, we propose a comprehensive design for narrowband and passband composite pulse sequences by involving the dynamics of all states in the three-state system. The design is quite universal as all pulse parameters can be freely employed to modify the coefficients of error terms. Two modulation techniques, the strength and phase modulations, are used to achieve arbitrary population transfer with a desired excitation profile, while the system keeps minimal leakage to the third state. Furthermore, the current sequences are capable of tolerating inaccurate waveforms, detuning errors, and work well when rotating wave approximation is not strictly justified. Therefore, this work provides versatile adaptability for shaping various excitation profiles in both narrowband and passband sequences.

Effects of the turbocharged Miller cycle strategy on the performance improvement and emission characteristics of diesel engines.

The turbocharged Miller cycle strategy is studied to improve the power density of diesel engines and reduce emissions. A thermodynamic model and a 1D simulation model of turbocharged diesel engine are established. Results show that the introduction of the Miller cycle reduces the thermal efficiency under naturally aspirated conditions because of the low effective compression ratio, whereas it increases the thermal efficiency under a turbocharged condition owing to the energy recovered by the turbocharger. Under restricted combustion pressure and fixed intake mass, the thermal efficiency first increases and then decreases with increasing Miller cycle ratio, and the peaks occur at approximately 30%-50%. The gain of isochoric combustion ratio overlaps the loss of effective compression ratio due to the Miller cycle on the lower side, whereas it reverses on the higher side. With maximum and equal intake mass, the maximum power initially increases and subsequently decreases with increasing Miller cycle ratio, reaching a peak at 40%. Under a fixed isochoric combustion ratio, the thermal efficiency first increases and then decreases with increasing intake mass, and the optimum intake mass corresponding to the highest thermal efficiency decreases with increasing Miller cycle ratio. The lower the restricted combustion pressure is, the higher the gain in power and thermal efficiency by the Miller cycle strategy. Based on the calculation of the 1D model validated using a practical engine, the power can be increased from 41.6 kW/L to 100 kW/L while the brake thermal efficiency can be increased from 34.98% into 38.55% by increasing the Miller cycle ratio from 19% to 30% and the combustion pressure from 17.7 MPa to 35 MPa. With the application of the supercharged Miller cycle, when the Miller cycle ratio is 30% and the power intensity is increased from 60 kW/L to 100 kW/L, NOx decreases by 32.4%, CO decreases by 28%, showing a tendency to decrease and then stabilize, and HC increases by 5.3%. When the power is 80 kW/L and the Miller cycle ratio is increased from 10% to 30%, NOx decreases by 8.6%, CO decreases by 2%, and HC increases by 0.04%.

Progesterone Activates the Histone Lactylation-Hif1α-glycolysis Feedback Loop to Promote Decidualization.

Decidualization is a progesterone-dependent cellular differentiation process that is essential for establishing pregnancy. Robust activation of glycolysis and lactate synthesis during decidualization is remarkable, but their developmental functions remain largely unknown. Herein, we identify that endometrial lactate production plays a critical role in establishing local histone lactylation, a newly identified histone modification, and is important for ensuring normal decidualization. Enhanced endometrial glycolysis is the hallmark metabolic change and is tightly coupled with H4K12la during decidualization. Inhibition of histone lactylation impaired decidualization, in either physiological conception or in vivo and in vitro induced decidualization models. Mechanistic study based on CUT&Tag and ATAC-seq revealed that a transcriptional factor hypoxia-inducible factor 1 α (Hif1α) is the critical regulatory target of H4K12la, and in turn forms an H4K12la-Hif1α-glycolysis feedback loop to drive decidualization. Moreover, we demonstrate that the loop is directly activated by progesterone during decidualization. Our study not only advances the current knowledge of the role of lactate in regulating uterine function, but also establishes a novel functional link among the major endocrine factors, endometrial metabolic change, and epigenetic modification during endometrial remodeling. These findings present valuable clues to develop clinical intervention strategies to improve pregnancy outcomes following both natural conception and assisted reproduction.

Achieving remarkable energy storage enhancement in polymer dielectrics via constructing an ultrathin Coulomb blockade layer of gold nanoparticles.

High-energy density polymer dielectrics play a crucial role in various pulsed energy storage and conversion systems. So far, many strategies have been demonstrated to be able to effectively improve the energy density of polymer dielectrics, but sophisticated fabrication processes are usually needed which result in high cost and poor repeatability. Herein, an easy-operated sputtering and hot-pressing process is developed to significantly enhance the energy density of polymer dielectrics. Surprisingly, for the poly(vinylidene fluoride-hexafluoropropylene) films sputtered with merely 0.0064 vol% gold nanoparticles, the energy density is remarkably improved by 84.3% because of the concurrent enhancements in breakdown strength (by 37.5%) and dielectric permittivity (by 25.5%), which is demonstrated to have originated from the unique Coulomb blockade and micro-capacitor effect of the gold nanoparticles. It is further confirmed that this design strategy is also applicable for commercial biaxially oriented polypropylene and poly(methyl methacrylate). This work offers a novel, easy-operated and universally applicable route to improve the energy density of polymeric dielectrics, which paves the way for their application in modern electronics and power modules.

Gold Sputtering at the Interfaces: An Easily Operated Strategy for Enhancing the Energy Storage Capability of Laminated Polymer Dielectrics.

Polymers with excellent dielectric properties are strongly desired for pulsed power film capacitors. However, the adverse coupling between the dielectric constant and breakdown strength greatly limits the energy storage capability of polymers. In this work, we report an easily operated method to solve this problem via sputtering the interface of bilayer polymer films with ultralow content of gold nanoparticles. Interestingly, the gold nanoparticles can effectively block the movement of charge carriers because of the Coulomb blocking effect, yielding significantly enhanced breakdown strength. Meanwhile, the gold nanoparticles can act as electrodes to form numerous equivalent microcapacitors, resulting in an obviously enhanced dielectric constant. Impressively, the polymer film with merely 0.01 vol % gold nanoparticles exhibits an obvious dielectric constant and breakdown strength, which are 129 and 131% that of the pristine polymer film, respectively. Consequently, a high energy density which is 176% of that of the pristine polymer film is achieved, and a high efficiency of 79.2% is maintained. Moreover, this process can be well combined with the production process of commercial dielectric polymer films, which is beneficial for mass production. This work offers an easily operated way to improve the dielectric capacitive energy storage properties of polymers, which could also be applicable to other materials, such as ceramics and composites.

A Spatiotemporal Solution to Control COVID-19 Transmission at the Community Scale for Returning to Normalcy: COVID-19 Symptom Onset Risk Spatiotemporal Analysis.

BACKGROUND: Following the recent COVID-19 pandemic, returning to normalcy has become the primary goal of global cities. The key for returning to normalcy is to avoid affecting social and economic activities while supporting precise epidemic control. Estimation models for the spatiotemporal spread of the epidemic at the refined scale of cities that support precise epidemic control are limited. For most of 2021, Hong Kong has remained at the top of the "global normalcy index" because of its effective responses. The urban-community-scale spatiotemporal onset risk prediction model of COVID-19 symptom has been used to assist in the precise epidemic control of Hong Kong. OBJECTIVE: Based on the spatiotemporal prediction models of COVID-19 symptom onset risk, the aim of this study was to develop a spatiotemporal solution to assist in precise prevention and control for returning to normalcy. METHODS: Over the years 2020 and 2021, a spatiotemporal solution was proposed and applied to support the epidemic control in Hong Kong. An enhanced urban-community-scale geographic model was proposed to predict the risk of COVID-19 symptom onset by quantifying the impact of the transmission of SARS-CoV-2 variants, vaccination, and the imported case risk. The generated prediction results could be then applied to establish the onset risk predictions over the following days, the identification of high-onset-risk communities, the effectiveness analysis of response measures implemented, and the effectiveness simulation of upcoming response measures. The applications could be integrated into a web-based platform to assist the antiepidemic work. RESULTS: Daily predicted onset risk in 291 tertiary planning units (TPUs) of Hong Kong from January 18, 2020, to April 22, 2021, was obtained from the enhanced prediction model. The prediction accuracy in the following 7 days was over 80%. The prediction results were used to effectively assist the epidemic control of Hong Kong in the following application examples: identified communities within high-onset-risk always only accounted for 2%-25% in multiple epidemiological scenarios; effective COVID-19 response measures, such as prohibiting public gatherings of more than 4 people were found to reduce the onset risk by 16%-46%; through the effect simulation of the new compulsory testing measure, the onset risk was found to be reduced by more than 80% in 42 (14.43%) TPUs and by more than 60% in 96 (32.99%) TPUs. CONCLUSIONS: In summary, this solution can support sustainable and targeted pandemic responses for returning to normalcy. Faced with the situation that may coexist with SARS-CoV-2, this study can not only assist global cities in responding to the future epidemics effectively but also help to restore social and economic activities and people's normal lives.

Two-photon photodynamic therapy based on FRET using tumor-cell targeted riboflavin conjugated graphene quantum dot.

The photodynamic therapy (PDT) is considered as a noninvasive and photo-controlled treatment for various cancers. However, its potential is not fully developed as current clinically approved photosensitizers (PSs) mainly absorb the light in the UV-visible region (less than 700 nm), where the depth of penetration is inadequate for reaching tumor cells under deeper tissue layers. Furthermore, the lack of specific accumulation capability of the conventional PSs in the tumor cells may cause serious toxicity and low treatment efficiency. To address these problems, riboflavin (Rf) conjugated and amine-functionalized nitrogen-doped graphene quantum dots (am-N-GQD) are herein proposed. Rf functions as both photosensitizer and targeting ligand by indirect excitation through intra-particle fluorescence resonance energy transfer (FRET) via two-photon (TP) excited am-N-GQD, to enhance the treatment depth, and further am-N-GQD-Rf accumulation in cancer cells using Rf transporter family (RFVTs) and Rf carrier proteins (RCPs). The one-photon (OP) and two-photon(TP)-PDT effect and cellular internalization ability of the am-N-GQD-Rf were investigated in vitro in different cancel cell lines. Besides the excellent cellular uptake as well TP-PDT capability, the superior biocompatibility of am-N-GQD-Rf in vitro makes it promising candidate in PDT.

Surface wettability of various phases of titania thin films: Atomic-scale simulation studies.

In the paper, the wettability of different phases of TiO2 thin films (anatase, brookite, and rutile) have been studied using molecular-dynamics simulation. The principle of micro-wetting is discussed. The simulation results show that the contact angle decreases upon increasing the interaction energy between the water and the titanium dioxide interface during the wetting process. The values of contact angles from large to small are: rutile, brookite and anatase. The calculated equilibrium contact angles are 73.9°, 59.2°, and 43.7°, respectively. The reason is that the structural connection and the arrangement of the surface microtopography directly affect the movement of water droplets on the surface of the material, thus affecting the wettability. In addition, the amount of the interaction energy and the radial distribution function between these three interfaces and the droplets are calculated, and the density change of the droplet is analyzed further which indicate the difference in wetting between the three crystal structures. At the same time, by simulating and comparing the wettability of the trench surface and the original surface of anatase, it is inferred that the rough interface increases the contact angle with the droplet and reduces the wettability.

Predicting onset risk of COVID-19 symptom to support healthy travel route planning in the new normal of long-term coexistence with SARS-CoV-2.

Due to the increased outdoor transmission risk of new SARS-COV-2 variants, the health of urban residents in daily travel is being threatened. In the new normal of long-term coexistence with SARS-CoV-2, how to avoid being infected by SARS-CoV-2 in daily travel has become a key issue. Hence, a spatiotemporal solution has been proposed to assist healthy travel route planning. Firstly, an enhanced urban-community-scale geographic model was proposed to predict daily COVID-19 symptom onset risk by incorporating the real-time effective reproduction numbers, and daily population variation of fully vaccinated. On-road onset risk predictions in the next following days were then extracted for searching healthy routes with the least onset risk values. The healthy route planning was further implemented in a mobile application. Hong Kong, one of the representative highly populated cities, has been chosen as an example to apply the spatiotemporal solution. The application results in the four epidemic waves of Hong Kong show that based on the high accurate prediction of COVID-19 symptom onset risk, the healthy route planning could reduce people's exposure to the COVID-19 symptoms onset risk. To sum, the proposed solution can be applied to support the healthy travel of residents in more cities in the new normalcy.

Effective non-adiabatic holonomic quantum computation of cavity modes via invariant-based reverse engineering.

In this paper, we propose a protocol to realize non-adiabatic holonomic quantum computation (NHQC) of cavity modes via invariant-based reverse engineering. Coupling cavity modes with an auxiliary atom trapped in a cavity, we derive effective Hamiltonians with the help of laser pulses. Based on the derived Hamiltonians, invariant-based reverse engineering is used to find proper evolution paths for NHQC. Moreover, the systematic-error-sensitivity nullified optimal control method is considered in the parameter selections, making the protocol insensitive to the influence of systematic errors of pulses. We also estimate the imperfections induced by random noise and decoherence. Numerical results show that the protocol holds robustness against these imperfections. Therefore, the protocol may provide useful perspectives to quantum computation with optical qubits in cavity quantum electrodynamics systems. This article is part of the theme issue 'Shortcuts to adiabaticity: theoretical, experimental and interdisciplinary perspectives'.

Experimental and Theoretical Studies on Optical Properties of Tetra(Imidazole) of Palladium (II) Phthalocyanine.

In this work, the optical properties of tetra(imidazole) of palladium phthalocyanine (PdPc(Im)4) in solution form and thin films on glass and fluorine-doped tin oxide (FTO) substrates were investigated via the thermal evaporation technique. The optical band gap was evaluated by ultraviolet-visible spectroscopy (UV-Vis). The energy band gap values were determined based on the Tauc graph. In addition, time-dependent density functional theory (TD-DFT) was used to simulate the UV-Vis absorption spectrum of the (PdPc(Im)4) molecule in the Dimethyl Sulfoxide (DMSO) solution phase. A good correlation was found between the DFT results and the experimental optical results. The band gap values between the experimental and DFT-simulated values are presented. The energy band gap of (PdPc(Im)4) obtained from the DFT calculations showed that it can be efficiently regulated. Frontier molecular orbitals and molecular electrostatic potentials were also proposed in this work. The surface study of the layers deposited on FTO was considered by atomic force microscopy (AFM) and scanning electron microscopy (SEM), and the results demonstrated good homogeneity covering the entire surface. The SEM image showed a homogeneous distribution of the grains with some spherical or rod-shaped structures and no agglomeration structures. This work rendered a strategy for regulating the energy band gap and compared the experimental observations obtained with theoretical studies, which provides a fundamental insight into the optical band for optoelectronic and thin-film solar cells.

Understanding spatiotemporal symptom onset risk of Omicron BA.1, BA.2 and hamster-related Delta AY.127.

Purpose: Investigation of the community-level symptomatic onset risk regarding severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern, is crucial to the pandemic control in the new normal. Methods: Investigated in this study is the spatiotemporal symptom onset risk with Omicron BA.1, BA.2, and hamster-related Delta AY.127 by a joint analysis of community-based human mobility, virus genomes, and vaccinations in Hong Kong. Results: The spatial spread of Omicron BA.2 was found to be 2.91 times and 2.56 times faster than that of Omicron BA.1 and Delta AY.127. Identified has been an early spatial invasion process in which spatiotemporal symptom onset risk was associated with intercommunity and cross-community human mobility of a dominant source location, especially regarding enhancement of the effects of the increased intrinsic transmissibility of Omicron BA.2. Further explored is the spread of Omicron BA.1, BA.2, and Delta AY.127 under different full and booster vaccination rate levels. An increase in full vaccination rates has primarily contributed to the reduction in areas within lower onset risk. An increase in the booster vaccination rate can promote a reduction in those areas within higher onset risk. Conclusions: This study has provided a comprehensive investigation concerning the spatiotemporal symptom onset risk of Omicron BA.1, BA.2, and hamster-related Delta AY.127, and as such can contribute some help to countries and regions regarding the prevention of the emergence of such as these variants, on a strategic basis. Moreover, this study provides scientifically derived findings on the impact of full and booster vaccination campaigns working in the area of the reduction of symptomatic infections.

Numerical study on the wall-impinging diesel spray soot generation and oxidation in the cylinder under cold-start conditions of a diesel engine.

The combustion of wall-impinging diesel spray of heavy-duty diesel engines deteriorates combustion quality under cold-start conditions, making it difficult to control soot emissions. To investigate the causes of soot increase in the combustion of wall-impinging spray at low temperature and low speed starting conditions, the effect of the starting fuel mass on the soot formation and oxidation process was analyzed using a multidimensional computational fluid dynamics (CFD) model. The results show that the diesel spray is guided by the piston wall and the limited space, the spray impinged on the wall and the vapor-phase fuel flowed in the spray interaction zone. Thus, the soot mainly accumulates in the spray interaction zone, the region near the cylinder head and the bowl wall in the combustion chamber bowl. The soot from the vapor of deposited fuel film in the piston bowl wall and near wall region accumulates continuously in the after combustion stage, becoming the main source of soot emissions at the time of exhaust valve opening (EVO). Increasing the mass of starting fuel raises the mass of the rich mixture and wall-impinging fuel, which enhances the mismatch between fuel and air, resulting in higher soot generation, while soot is more difficult to be completely oxidized by OH radicals, and ultimately soot emissions increase significantly. It can be deduced that the engine-optimized injection strategy may mitigate the increase in soot emissions at high start-up fuel injection conditions.

Estimation of On-Road PM2.5 Distributions by Combining Satellite Top-of-Atmosphere With Microscale Geographic Predictors for Healthy Route Planning.

How to reduce the health risks for commuters, caused by air pollution such as PM2.5 has always been an urgent issue needing to be solved. Proposed in this study, is a novel framework which enables greater avoidance of pollution and hence assists the provision of healthy travel. This framework is based on the estimation of on-road PM2.5 throughout the whole city. First, the micro-scale PM2.5 is predicted by land use regression (LUR) modeling enhanced by the use of the Landsat-8 top-of-atmosphere (TOA) data and microscale geographic predictors. In particular, the green view index (GVI) factor derived, the sky view factor, and the index-based built-up index, are incorporated within the TOA-LUR modeling. On-road PM2.5 distributions are then mapped in high-spatial-resolution. The maps obtained can be used to find healthy travel routes with less PM2.5. The proposed framework was applied in high-density Hong Kong by Landsat 8 images. External testing was based on mobile measurements. The results showed that the estimation performance of the proposed seasonal TOA-LUR Geographical and Temporal Weighted Regression models is at a high-level with an R 2 of 0.70-0.90. The newly introduced GVI index played an important role in these estimations. The PM2.5 distribution maps at high-spatial-resolution were then used to develop an application providing Hong Kong residents with healthy route planning services. The proposed framework can, likewise, be applied in other cities to better ensure people's health when traveling, especially those in high-density cities.

CoZn Nanoparticles@Hollow Carbon Tubes Enabled High-Performance Potassium Metal Batteries.

Potassium-metal batteries (PMBs) are attractive candidates for low-cost and large-scale energy storage systems due to the abundance of potassium. However, its application is hampered by large volume change and serious dendrite growth. Herein, a CoZn semicoherent structure nanoparticle-embedded nitrogen-doped hollow carbon tube (CoZn@HCT) electrode is prepared via coaxial electrospinning. Due to the high potassiophilic CoZn semicoherent structure nanoparticles and large potassium metal storage space, the free-standing CoZn@HCT host for K metal exhibits uniform K nucleation and stable plating/stripping (stable cycling 1000 h at 1 mA cm-2 with 1 mA h cm-2). Furthermore, enhanced electrochemical performance with good cycling stability and rate capability is achieved in (CoZn@HCT@K||PTCDA) full batteries. Our results highlight a promising strategy for dendrite-free K metal anodes and high-performance PMBs.

Effect of injection timing on knock combustion and pollutant emission of heavy-duty diesel engines at low temperatures.

The knock combustion and pollutant emission of heavy-duty diesel engines at low temperatures are still unclear, especially under different injection timings. Therefore, this study illustrates the above issues through CONVERGE simulation. The results show that with the start of injection (SOI) sweeps from -7°CA to -32°CA, a large amount of liquid-phase fuel adheres to the wall, and the wet-wall ratio of fuel at SOI = -32°CA is as high as nearly 30%. The fuel film evaporates slowly, coupled with the effect of low temperature on chemical reactions, the high-temperature ignition (HTI) is delayed seriously until the end of injection. The amount of premixed mixture formed during long ignition delay is significantly increased, but its uniformity is better and the concentration is more suitable for ignition. Once HTI is triggered, high-frequency and strong pressure oscillation occurs in the cylinder, and the maximum oscillation amplitude is as high as nearly 10 MPa, far exceeding the threshold of destructive knock combustion. Delayed fuel injection can effectively alleviate the above problems, such as the best when the SOI in this study is -17°CA. In addition, HC emissions are positively correlated with the amount of fuel film, but the trend of CO quantity with injection timing shows the opposite result. NOx emission increases as the injection timing advances, while soot is the opposite, because the mixture concentration is leaner at the earlier SOI and the expanded high-temperature region leads to an accelerated oxidation rate of soot.

Effect of wall parameters on impinging combustion and soot emission characteristics of heavy-duty diesel engine at low temperature.

The effect of wall parameters on combustion and soot emission characteristics remains to be revealed so far, especially in the case of spray impingement at low temperatures. Therefore, the visualization experiments are carried out in a constant volume combustion chamber using the Mie scattering and direct photography techniques, and the two-color method was used to extract the flame temperature and soot volume. The results show that increased wall distance and wall angle contribute to fast and stable ignition, but result in more soot production. In addition, the lower the ambient temperature, the more prominent the above characteristics are. At Tamb = 820 K, as the wall distance increases from 40 mm to 60 mm, the liquid spray impingement changes to the vapor impingement, so the ignition delay shortens, and the flame area and natural luminance increase significantly. At lower Tamb = 770 K, a complete misfire is observed at Lw = 40 mm but the ignition remains stable at Lw = 60 mm. The variation of the ignition characteristic parameters with the wall angle is similar to that of the wall distance. Under Pinj = 40 MPa, as the wall angle increases from 0° to 70°, the time to reach luminance saturation advances from 0.60 ms to 0.27 ms. Under higher Pinj = 100 MPa, a complete misfire occurs at θ =0° but bright flames are observed at θ =30-70°. With the increase of wall distance, the mean flame temperature increases due to reduced wall cooling. Coupled with the expanded flame area and combustion duration, the high-temperature region (>1800K) of soot distribution and KL factor increase significantly, especially in the range of Lw = 40-50 mm.

Experimental study on combustion and emission characteristics of diesel engine with high supercharged condition.

The effect of diesel engine continuous strengthening on combustion and emission remains to be clarified. This study tested combustion and emission processes at different intake pressures on a single-cylinder diesel engine. The results show that the combustion of diesel engine after continuous strengthening is concentrated in diffusion and post-combustion periods, the overall heat release slows down, and the power increment decreases gradually. When the intake pressure increases to 0.25 MPa, the premixed heat release peak almost disappears, while the value of diffusion combustion period increases significantly. Meanwhile, the gravity center of combustion moves backward and the cumulative heat release rate decreases. The power increases by 95% as the intake pressure increases from 0.15 MPa to 0.25 MPa, but only 44% as it further increases to 0.36 MPa. Meanwhile, the exhaust temperature increases after high supercharging. The above effects are more prominent at high excess air coefficient and low speed. Moreover, with the decrease of excess air coefficient, the proportion of heat release in the post-combustion stage to the whole combustion increases and the power increment is limited. However, the thermal efficiency decreases approximately linearly and the fuel consumption rate increases sharply. In addition, as the excess air coefficient decreases, the exhaust temperature increases, PM increases and NOx decreases. The above effects are more pronounced at higher boost ratio.