High-pressure direct injection (HPDI) natural gas engines are a next-generation powertrain technology. They provide high efficiency and low emissions for future clean transportation. However, limited in-cylinder mixing restricts combustion speed and overall performance. Improving mixture formation is crucial for enhancing thermal efficiency and emission control. This study addresses this challenge through coordinated optimization of injector geometry and injection pressure. Five injectors with different structural designs were tested on a six-cylinder 11.59 L heavy-duty HPDI engine. Experiments were conducted under a medium-to-high load condition (BMEP approximate to 10.8 bar). The natural-gas injection pressure ranged from 200 to 300 bar with 10 bar intervals. The effects of nozzle geometry and injection pressure on combustion and emissions were analyzed. Results show that increasing the injector flow area strengthens turbulence and accelerates mixture formation. Moderate dispersion improves combustion and reduces HC and CO emissions. Excessive dispersion, however, increases wall impingement and unburned hydrocarbons. A narrow spray cone at high pressure enhances heat-release concentration and shortens combustion duration. With optimized injector design and higher injection pressure, the engine achieved a brake thermal efficiency of 46.85 %, 3.28 % higher than the original engine. HC and CO emissions decreased by 0.314 and 0.5 g/kW & sdot;h, while NOx emissions increased by 6.3 g/kW & sdot;h. The results confirm that coordinated design and pressure control effectively improve HPDI engine performance.

In recent years, organic-inorganic metal halides (OIMHs) have aroused widespread interests in the fields of information security, light-emitting devices, optical waveguides, chemical sensing and bioimaging owing to their outstanding optical characteristics, such as color-tunable photoluminescence (PL), long-lived and efficient luminescence. Metal and halogen atoms in OIMHs bring about stronger heavy atom effects and intermolecular interactions, which contribute to the formation of stable triplet excitons, making these materials excellent candidates for realizing long-lived room-temperature phosphorescence (RTP) or thermally activated delayed fluorescence (TADF). Moreover, the “substituent effect” derived from organic ligands provides an effective way to achieve color-tunable emissions. It is of great significance to gain an in-depth understanding of the intrinsic relationship between structure and emission performance for material design. This review begins with a concise overview of recent advances in OIMHs-based luminescent materials, followed by a discussion of their underlying luminescence mechanisms. Subsequently, multiple strategies, including metal cation selection, metal ion doping, halogen alteration, and organic ligand engineering, are illustrated for optimizing PL properties of OIMHs to achieve long-lasting luminescence, single-component white light, near-infrared (NIR) emission, color-tunable emission and so on. Furthermore, key applications of luminescent OIMHs in information encryption, optoelectronic devices, optical waveguides, and X-ray imaging are highlighted. Finally, future outlooks and challenges are propounded in regard to material construction, mechanism exploration, and further application of luminescence OIMHs.

Monitoring pH variations within living organisms is critically important. In this study, we report a novel dual-excitation ratiometric near-infrared (NIR) fluorescent probe (BNClBi-N), which employs hemicyanine dye as the fluorophore. BNClBi-N exhibits a response to pH changes through the protonation and deprotonation of nitrogen atoms on the benzoindole moiety, as confirmed by NMR studies. This protonation modulates the intramolecular charge transfer (ICT) process, causing a significant ratiometric fluorescence emission shift (I700 nm/I610 nm) with a pKa value of 3.46. Additionally, the fluorescent color transitioned from green to yellow within the pH range of 6.0 to 2.0. Additionally, the probe demonstrated good stability and anti-interference capability. Building on these outstanding characteristics, BNClBi-N enabled reliable monitoring exogenous pH in live cells and zebrafish with excellent lysosomal targeting ability.

Cylinder-to-cylinder variation (CTCV) is a prevalent issue for natural gas (NG) premixed engines with port fuel injection (PFI), which significantly impacts the engine’s power performance, fuel economy, and reliability. Focusing on this issue, this study established a three-dimensional simulation platform based on a six-cylinder natural gas premixed engine. Quantitative analysis was conducted to discuss the differences in the main boundaries, combustion process, and engine power between cylinders. Additionally, influencing factors of CTCV were explored in terms of mixture uniformity and distribution uniformity. The results indicate that, for the NG premixed engine, many parameters vary significantly between cylinders even under the economical operating condition of 1200 rpm. For example, the difference rate in the peak cylinder pressure and peak phase between cylinder 3 and cylinder 2 can reach 23.5% and 24.3%, respectively. Through the design of simulation cases, it was found that improving the mixture uniformity had a more significant impact on CTCV than improving the distribution uniformity. For example, the relative standard deviation (RSD) of peak pressure decreased by 2.15% through mixture uniformity improvement, while it only decreased by 0.39% through distribution uniformity improvement. At a high speed of 1800 rpm, the influence of distribution uniformity on CTCV increased notably, but the influence of mixture uniformity still remained greater than that of distribution uniformity.

Orientated-type gas flow channels are beneficial for the enhancement of Proton Exchange Membrane Fuel Cells (PEMFC) performance; however, higher flow losses are incurred as well. In this study, the flow characteristicss of the orientated gas flow channel are studied numerically; and the geometries of baffles are optimized using a Genetic Algorithm to minimize their flow losses. The results show that as the middle baffle length (L1) increases, the high-velocity zone expands, which leads to higher friction losses and pressure drops. Moreover, increasing the sloped leeward side baffle length (L2) reduces the vortices size on the leeward side, and increasing the inclination angle of the leeward side can mitigate the boundary layer separation and vortices formation. For lower baffle heights (R = H/4 and R = H/2), an increase in the mid-section length leads to a significant reduction in flow losses, indicated by pressure drop. However, for high baffle heights (R = 3H/4), the optimal L2 is insensitive to the variation of L1, indicating that the baffle height for high baffles dominates the flow resistance of channels. The pressure drop between the inlet and outlet of the optimized channel can be reduced by 4.8 % compared to that of the original geometry.

Regulating strategies for long persistent luminescence (LPL) are always in high demand. Herein, a series of coordination polymers (CPs) (SUST-Z1-Z4) are fabricated using 1,10-phenanthroline derivatives involving different substituents (─H, ─CH3, ─Cl, and ─Br) as ligands, respectively. Crystallographic data demonstrate that these CPs adopt alternating arrangements of cadmium halide chains and π-conjugated ligands. Cadmium halide chains not only bring about heavy atom effects but also introduce abundant intermolecular interactions, including halogen bonding and π-π stacking, favoring the generation of stable triplet excitons. Additionally, distinct substituents featured different electron-withdrawing abilities give rise to various spatial resistances between Phen planes, thereby resulting in diverse molecular packing modes and electronic structures. Thus, their aggregated state phosphorescence lifetimes range from 6.84 ms (SUST-Z4) to 91.10 ms (SUST-Z2), and the colors are modulated from orange to red at room temperature. SUST-Z2 presents the longest-lasting RTP and the most obvious red LPL, which is derived from the weakest electron-withdrawing capability of ─CH3 in ligands. Moreover, owing to the co-existence of single molecule and aggregated triplet excitons, these CPs also realize dynamic color-tunable LPL from green/orange to yellow/red depending on the excitation wavelength, temperature, and time-evolution. Based on quite different LPL of these CPs, multiple anti-counterfeiting methods are proposed.

α-In2Se3 is a promising two-dimensional (2D) ferroelectric semiconductor with unique phase transition behaviors and intrinsic n-type conductivity. However, the origin of this conductivity and the impact of defects on the phase transition remain unclear. In this study, we employed the WLZ method to calculate vacancies' formation energy and ionization energy in monolayer α-In2Se3 and identified the defect-bound band edge states. Our results reveal a strong polarization-defect coupling effect, where the bottom-layer selenium vacancy drives intrinsic n-type conductivity in the sample with upward polarization while reversing the polarization-induced deep p-type defect. Furthermore, we demonstrate that a vacancy stabilizes the ferroelectric phase and reduces the phase transition rate to the paraelectric phase. Finally, we propose a defect-engineered ferroelectric field-effect transistor model that controls the resistance by leveraging the polarization-defect coupling effect. This work highlights the significant roles of vacancy defects in 2D α-In2Se3, offering strategies to design In2Se3 electronic devices at the nanoscale.

Under the background of energy transition, natural gas serves as a low-carbon, clean energy source that reduces internal combustion engines' dependence on petroleum and promotes energy diversification. However, the efficient combustion of heavy-duty stoichiometric combustion natural gas engines is still constrained by the contradiction between low fuel consumption and knocking. It has been demonstrated that applying EGR combined with advancing spark timing can improve the thermal efficiency of the engine. However, this improvement is constrained by the EGR intake capacity, combustion stability, and knocking. In this context, research has shown that rapid combustion can enhance engine thermal efficiency under the same EGR rate and spark timing conditions. Additionally, rapid combustion shortens the time required for flame propagation to the end-gas. Therefore, this paper presents an experimental study on the influence of combustion chamber on achieving rapid combustion of a 13L heavy-duty stoichiometric combustion natural gas engine. By optimizing combustion chamber, the heat release process can be significantly enhanced. When the engine is equipped with eccentric half annular combustion chamber, the brake thermal efficiency is increased from 38.10 % to 40.12 %. By organizing the rapid combustion process, combined with EGR and spark timing, the peak heat release rate is controllable in the range of 417-678 J/degrees CA, and its corresponding phase is controllable in the range of 11-21 degrees CA ATDC. The controllable range of the engine's heat release process has been broadened, providing extensive support for achieving high efficiency and clean combustion in natural gas engines.

Although alpha-In2Se3 is theoretically predicted to exhibit an indirect bandgap semiconductor, its experimental optoelectronic response resembles that of a direct bandgap material. To provide a possible explanation for this issue, we combined first-principles calculations and femtosecond broad transient absorption spectroscopy-employing a supercontinuum white light probe (450-1700 nm)-to reveal the electronic structure and hot-carrier dynamics in mechanically exfoliated alpha-In2Se3 flakes with the 2H stacking arrangement. High-energy excitonic states arising from band-nesting regions are found by theoretical calculations, and the hot-carrier cooling and intra-band self-separation of hot holes for indirect bandgap excitons in the Gamma valley of 2H-alpha-In2Se3 is experimentally revealed. The resulting indirect bandgap exciton state possesses long-lifetime free carriers in the nanosecond timescale. These ultrafast processes, including the unique exciton dynamics and band structure evolution in alpha-In2Se3, are fundamental and crucial for understanding the optoelectronic performance of alpha-In2Se3-based devices.

The thickness-dependent atomic structures of two-dimensional (2D) few-layer (FL) ZnO are systematically investigated by the first-principles calculations. It is found that the structural transformation between thinner FL ZnO with graphitic structure (FL gZnO) and thicker FL ZnO with wurtzite structure (FL wZnO) takes place at the critical thickness of 9-12 Zn-O atomic layers. At the thickness of 9-12 layers, both graphitic and wurtzite structures can coexist at room temperature. In FL gZnO, the interlayer interaction is a long-range Coulomb interaction, and the charge population of Zn and O inside does not change during the structural transformation. Moreover, we demonstrate that the structural transformation of FL ZnO originates from the competition between the high energy of the O 2pz orbital in the graphitic structure and the polar-surface-induced dipole energy in the wurtzite structure. Our microscopic understanding guides a clear direction of regulating the atomic structure of FL ZnO, further optimizing its electronic properties, which benefits developing function-advanced 2D stacked devices.

Due to the increase in heat load, the demand for heat dissipation of the cabin cooling module has increased. The fan arrangement and the design of the fan cowl can significantly affect the intake air parameters, thereby affecting the performance of the heat exchangers. In this paper, the whole vehicle model was set up and the effect of the fan installation distance, the fan cowl coverage ratio, and the radial extension of the fan cowl outlet was researched by numerical simulation. The results show that due to the relative position of the layout of the cooling module, the effect of the fan arrangement and the fan cowl design on the intake parameters of the radiator is greater than that of the intercooler. The improvement of the air velocity uniformity can reduce the intake air average temperature for better heat dissipation; a 2% improvement in air intake velocity uniformity can lead to a 6% reduction in air intake average temperature event at a low air mass flow. The extended installation distance of the fan or the increased closure degree of the fan cowl leads to more favorable intake parameters, thereby optimizing the cooling performance of the heat exchangers. Moreover, when the fan cowl coverage ratio reaches 0.9, the air intake average temperature increases by 5.6%, which means that the fan cowl coverage should not be too high. This study will provide useful reference information for the design of cooling modules in the cabin.

Introduction: The spread of carbapenem-resistant Klebsiella pneumoniae (CRKP) is a substantial severe global public health burden. Non-carbapenemase-producing CRKP (non-CP-CRKP) is increasingly recognized as the source of severe infections. Methodology: We analyzed the genotypic, and phenotypic profiles of non-CP-CRKP strains with the whole-genome sequences isolated between 2017 and 2019 and the clinical characterization of non-CP-CRKP infection. Results: A total of 91 CRKP strains were collected, of which 5 (5.49%) strains were non-CP-CRKP. Four strains were from male patients; three strains were isolated from the bile of patients who underwent biliary interventional surgery and four had a history of antibiotic exposure. Three strains were sequence type (ST)11, one was ST1, and one was ST5523. The non-CP-CRKP strains were insusceptible to ertapenem. Three strains were susceptible to amikacin. All the strains were susceptible to imipenem, meropenem, tigecycline, ceftazidime/avibatam and polymyxin B. The β-lactamases of non-CP-CRKP predominantly included blaCTX-M, blaSHV, and blaTEM subtypes. Two site mutations in ompK36 (p.A217S and p.N218H) and four in ompK37 (p.I70M, p.I128M, p.N230G, and m233_None234insQ) were detected accounting for carbapenem resistance. Plasmids IncFI and IncFII were found in most strains. Genes encoding aerobactin, yersiniabactin and allantoin utilization were not detected in several isolates, and all non-CP-CRKP strains did not carry rmpA gene. Conclusions: Non-CP-CRKP infected patients had a history of previous antibiotic exposure or invasive procedures. Non-CP-CRKP strains were insusceptible to ertapenem. The mechanism of resistance includes β-lactamases production and the site mutations in ompK36 and ompK37. Several virulence genes were not detected in non-CP-CRKP.

The Miller cycle has significant advantages of suppressing knocking and improving nitrogen oxide (NOX) emissions without the penalties of reducing engine fuel consumption and power output. In the study, the effect of non -Miller cycle and Miller cycle on the exhaust gas recirculation (EGR) introduction capability and the knocking boundary were evaluated on a stoichiometric combustion natural gas engine at three different loads. Additionally, the effect of Miller cycle coupled EGR and ignition timing on engine performance and combustion process was discussed. The results indicate that, for the same condition, the Miller cycle could reduce peak temperature and pressure, increased combustion duration, and delayed combustion phase, which makes for effective knocking suppression. Therefore, the Miller cycle has less dependence on the EGR strategy to control knock. Moreover, the Miller cycle can also reduce the ability to introduce EGR, which could up to 3.8%. By matching the ignition timing and EGR rate, the BSFC of the Miller cycle were decreased by 0.6g/kW & sdot;h, 2.4 g/ kW & sdot;h and 2.9 g/kW & sdot;h respectively for three test conditions compared with non -Miller cycle. In terms of emissions, the Miller cycle and EGR can both suppress NOX emissions, while the EGR being more effective. The study will provide valid information for the application of the Miller cycle to achieve efficiency clean combustion of natural gas engine.

Two types of novel symmetric acylhydrazone derivatives (TPAPT and 1,4-BDH) with triphenylamine substituted terminal groups containing one acylhydrazone and two acylhydrazone groups, respectively, were designed and synthesized. TPAPT didn't show aggregation induced emission (AIE) behaviors, whereas 1,4-BDH exhibited uncommon AIE behaviors. TPAPT exhibited obviously reversible MFC behavior, the emission wavelength changed from 452 nm to 486 nm upon grinding, accompanied by fluorescence color change. However, MFC behavior was not observed for 1,4-BDH. The reason for such different MFC behavior was that the different hydrogen bonding patterns induced the different self-assembly crystalline structures. In addition, both TPAPT and 1,4-BDH exhibited significant photo-responsive behaviors.

Atomic and close-to-atom scale manufacturing is a promising avenue toward single-photon emitters, single-electron transistors, single-atom memory, and quantum-bit devices for future communication, computation, and sensing applications. Laser manufacturing is outstanding to this end for ease of beam manipulation, batch production, and no requirement for photomasks. It is, however, suffering from optical diffraction limits. Herein, we report a spatial resolution improved to the quantum limit by exploiting a threshold tracing and lock-in method, whereby the two-order gap between atomic point defect complexes and optical diffraction limit is surpassed, and a feature size of <5 nm is realized. The underlying physics is that the uncertainty of local atom thermal motion dominates electron excitation, rather than the power density slope of the incident laser. We show that the colour centre yield in hexagonal boron nitride is transformed from stochastic to deterministic, and the emission from individual sites becomes polychromatic to monochromatic. As a result, single colour centres in the regular array are deterministically created with a unity yield and high positional accuracy, serving as a step forward for integrated quantum technological applications.

Due to the unique physicochemical properties of hydrogen, the mixture organization is highly sensitive to boundary conditions, making it challenging to adjust. This study is based on a hydrogen direct injection (HDI) engine, constructing a three-dimensional simulation platform. The effect of hydrogen-injected parameters on the stratification and combustion of the engine is analyzed, and the multi-parameter hydrogen-injected boundaries for forming an ideal stratified mixture is explored. The results indicate that the deflector structure determines the first movement path of the hydrogen jet. When using a deflector structure with 1-hole tilted upwards by 12 degrees, degrees , the combustion chamber tends to form a concentrated region of hydrogen concentration, and the indicated thermal efficiency can reach 42.91%. Both the hydrogen-injected timing and pressure can affect the interaction between the hydrogen jet and the cylinder flow field, thereby altering the distribution of the mixture at ignition timing. This study also explores two hydrogen-injected schemes: delayed injection and two-stage injection, both of which can form a stratified mixture organization with higher concentration in the middle of the combustion chamber and lower concentration around the periphery. Under both schemes, weak stratification and strong stratification are formed in the cylinder, with indicated thermal efficiencies reaching 44.62% and 44.72%.

Durability is the key issue for the proton exchange membrane fuel cell application and its commercialization. Current research usually uses the accelerated stress test to decrease the experiment time, whereas the performance evolution—especially the internal state evolution—under real use may be different from that under the accelerated stress test. In addition, studies rarely report this kind of durability in real decay scenarios. This paper investigates the seldom-reported impact of dry–wet cycles on durability in terms of open circuit voltage (OCV), inner resistance, and hydrogen crossover current at the condition of 20,000 cycles or the equivalent 400 h, while simultaneously running the test for the same time interval in the control experiment. The mechanical and chemical test is independent. Frequent dry–wet cycles make the OCV decay over 14% compared to 6.9% under the normal decay. Meanwhile, the dry–wet cycle helps to alleviate deterioration in terms of the inner resistance decline (61% vs. 37%) and in terms of the hydrogen crossover current increase (−64% vs. 15%). The inner state evolution is irregular and against common sense. The relationship between the crack, platinum transfer, and the moisture which heals the crack is the potential reason for the above-mentioned phenomena. These findings are beneficial to navigating fuel cell storage.

Atomic and close-to-atom scale manufacturing is now considered an avenue toward single-photon emitters, single-electron transistors, single-atom memory, and quantum-bit devices for future communication, computation, and sensing applications. Laser manufacturing is outstanding to this end for ease of beam manipulation and batch production, and no requirement for photomasks. It is, however, suffering from optical diffraction limit and lacks atomic and close-to-atom scale precision. Herein, we circumvent this limitation by exploiting a threshold tracing-and-lock-in method, whereby the 2-order gap between atomic point defect complexes and optical diffraction limit is surpassed. As a result, bright (up to 10 Mcounts s − 1 ) single-photon color centers are deterministically created from few-layer hBN with feature size of less than 5 nm and a near-unity yield. Around 94% of them emit monochromatically at around 30 individual wavelengths from 500 nm to 800 nm. A turn-key monochromic single-photon emitter of demanded color is attained by integrating it with 5-V blue laser diodes.

The development of narrow emission bandwidth materials is a highly active research area in the field of organic light-emitting diodes (OLEDs). In addition to B- and N-heterocyclic compounds, known as multiple-resonance (MR) emitters, chromophores based on multi-N-heterocycles can also achieve ultra-narrow-band blue emission. However, the reliability of devices containing the latter has been rarely investigated. In this study, we designed a rigid and electron-rich chromophore diindolo[3,2,1-de:3 & PRIME;,2 & PRIME;,1 & PRIME;-kl]phenazine (DIPz) by fusing two 9Hcarbazole. This resulted in suppressed geometric distortion and vibration coupling during excitation. Furthermore, DIPz was modified with mesityl and 4-(tert-butyl)-N-phenylaniline groups, which finally evolved into a narrow-band blue emitter tDAmDIPz. The tDAmDIPz-based device showed an emission maximum at 458 nm with a narrow full-width at half-maximum of 17 nm, and a high maximum external quantum efficiency of 9.1%. Because the lowest unoccupied molecular orbital (LUMO) level of - 1.98 eV for tDAmDIPz was much shallower than - 2.47 eV for the anthracene-based host, electron trapping at emitters could be prevented, resulting in a very long LT95 lifetime of 338 h at a current density of 25 mA/cm2, which was higher than devices based on traditional BN-type MR emitters. This study suggested a general relationship between the operational lifetime and the LUMO energy difference between the emitter and the host, which opens a door to extremely stable blue OLEDs.