Search

Nitrate has become the primary inorganic compound in urban aerosol particles, but its effects on particle phase state, which is crucial in multiphase chemistry, remains largely unknown. Herein, particle rebound measurements were conducted to explore the relationship between the liquid–phase–transition threshold relative humidity (RHthreshold) and the inorganic compounds mass fraction in dry particles (Finorg). Results revealed negative correlations between RHthreshold and Finorg, with more nitrate leading to lower RHthreshold. Even with RH < 20%, particles with ∼50% nitrate mass fraction remained in non‐solid state. Taking Beijing as an example, decreases were observed in RHthreshold from 64% in 2015 to below 53% nowadays during the moderate‐pollution periods (PM2.5 = 35–75 μg/m3) due to an enhanced nitrate fraction. This allowed urban aerosol particles to exist in liquid state at lower RH, and consequently, kinetic limitation by bulk diffusion in nitrate‐dominated particles might be negligible, making them key seeds for secondary aerosol formation through multiphase reactions. Plain Language Summary: The phase state of aerosol particles plays a crucial role in the mass‐transfer processes between gas and particles, which is essential for determining particle mass concentration. Investigating the characteristics of the aerosol phase state is crucial for comprehending the mechanisms behind secondary particle formation and improving air quality. Currently, the chemical composition of urban aerosol particles has shown notable changes. The mass fraction of inorganic components has increased, with nitrate emerging as the dominant inorganic component. However, the impacts of these changes on the phase state of urban aerosol particles remain largely unknown. This study demonstrates that particles with a higher mass fraction of inorganic compounds, particularly nitrate, tend to exist in a liquid state. Consequently, an increased nitrate fraction allows urban aerosol particles to exist in a liquid state at lower relative humidity levels. These findings suggest that changes in the phase state of particles due to changes in chemical properties in urban aerosol particles should be considered to accurately gauge the mass‐transfer processes and promote the air quality improvements in urban cities. Key Points: Particles with more inorganic compounds, particularly nitrate, can exist in a liquid state at lower relative humidity levelsParticles with normalized aerosol liquid water content larger than 0.3 exist in a liquid stateNitrate‐dominated particles can serve as key seeds where secondary aerosol formation can occur via multiphase reactions [ABSTRACT FROM AUTHOR]

The epidemic of tuberculosis has posed a serious burden in Qinghai province, it is necessary to clarify the epidemiological characteristics and spatial-temporal distribution of TB for future prevention and control measures. We used descriptive epidemiological methods and spatial statistical analysis including spatial correlation and spatial-temporal analysis in this study. Furthermore, we applied an exponential smoothing model for TB epidemiological trend forecasting. Of 43 859 TB cases, the sex ratio was 1.27:1 (M:F), and the average annual TB registered incidence was 70.00/100 000 of 2009–2019. More cases were reported in March and April, and the worst TB stricken regions were the prefectures of Golog and Yushu. High TB registered incidences were seen in males, farmers and herdsmen, Tibetans, or elderly people. 7132 cases were intractable, which were recurrent, drug resistant, or co-infected with other infections. Three likely cases clusters with significant high risk were found by spatial-temporal scan on data of 2009–2019. The exponential smoothing winters' additive model was selected as the best-fitting model to forecast monthly TB cases in the future. This research indicated that TB in Qinghai is still a serious threaten to the local residents' health. Multi-departmental collaboration and funds special for TB treatments and control are still needed, and the exponential smoothing model is promising which could be applied for forecasting of TB epidemic trend in this high-altitude province. [ABSTRACT FROM AUTHOR]

We investigated the ice nucleation activities of humic‐like substances (HULIS), an important component of organic aerosol (OA), derived from atmospheric and biomass burning aerosols, and produced from aqueous‐phase chemical reactions. Respective HULIS can effectively trigger heterogeneous IN under mixed‐phase cloud conditions. HULIS ice active entities (IAE) were aggregates in size between 0.02 and 0.10 μm. At −20°C, the IAE numbers per unit HULIS mass varied from 213 to 8.7 × 104 mg−1. Such results were different than those detected in aquatic humic substances (HS) from previous studies, implying using HS as surrogates may not robustly estimate the IAE concentrations in the real atmosphere. Combining the abundance of atmospheric HULIS with the present results suggests that HULIS could be an important IAE contributor in the atmosphere where other ice nucleating particle species, such as dust and biological particles, are either low in concentration or absent. Plain Language Summary: Humic‐like substances (HULIS), a ubiquitous component of atmospheric organic aerosol, were found to nucleate ice under mixed‐phase cloud conditions. HULIS ice active entities (IAE) were shown to be aggregates in size between 0.02 and 0.10 μm. The concentration of IAE per unit mass of HULIS varied from 213 to 8.7 × 104 mg−1 at −20°C. Such results were different than those detected in aquatic humic substances done by previous studies. Combining the reported concentrations of HULIS in the atmosphere with the present results suggests that HULIS could be important ice nucleating particle contributor in the atmosphere. Key Points: Humic‐like substances (HULIS) originating from atmospheric and biomass burning aerosols, and produced from aqueous‐phase reactions, can trigger immersion freezingThe abundance of ice active entities (IAE) per unit HULIS mass varied from 213 to 8.7 × 104 mg−1 at −20°CHULIS could be an important IAE contributor in the atmosphere where other ice nucleating particle species are either low in concentration or absent [ABSTRACT FROM AUTHOR]

A new deformable mirror structure is presented, which mainly consists of a mirror, some transition layers, a preload structure and PZT actuators. Compared with the conventional deformable mirror, the new structure can smooth the surface shape and reduce residual errors, which are mainly affected by some structure parameters. The finite-element method is used to analyze the relationship between the structure parameters and the residual errors. The simulation results show that the structure parameters, including the diameter, thickness, and materials of transition layers and the stiffness of preload springs, can determine the residual errors. Based on the simulations, experimental comparisons between new and conventional deformable mirrors have verified that the new structure can effectively diminish residual errors. The new structure deformable mirror will play an important role in high power laser aberration correction. [ABSTRACT FROM AUTHOR]

NbC- SiC micro/nanowires (MNWs) with NbC content varying from 5 to 20 mol.-% were synthesised at 1600-1800°C via carbothermal reduction utilising silica sol, niobium pentoxide powder and carbon black as starting materials. The synthesis process and growth mechanism of NbC-SiC system were investigated. Results show that the morphology of the synthesised products mainly appears as curve shaped microwires or nanowires. The crystalline consists of both SiC and NbC phases which doped with each other by substitution and interstitial reactions in solid solution. NbC-SiC MNWs were developed by vapour-liquid-solid mechanism according to the existence of liquid droplet phase in the tip at reaction temperature. β-SiC twin crystal growing along [112] direction was formed in the stem, and NbC polycrystal was dissociated from Nb-Si liquid phase. The varied concentration of Nb and Si in the Nb-Si liquid phase could be a significant reason for the curved growth of NbC-SiC MNWs. [ABSTRACT FROM AUTHOR]

Behavioural and electrophysiological responses ofAnopheles gambiaeGilessensustricto (Diptera: Culicidae) to human skin emanations collected on glass beads were studied using a dual-port olfactometer and electroantannography. Glass beads to which skin emanations from human hands had been transferred elicited a level of attraction similar to a human hand. The attractiveness of these handled glass beads faded away 4 h after transfer onto the beads. Storage at−20°C for up to 8 weeks showed a decreased but still attractive effect of the beads. In a choice test between one individual and four others, the emanations from the reference individual were significantly more attractive in three out of four cases. The headspace of handled glass beads elicited a dose-dependent EAG response. The substances causing EAG activity could be removed partially by dichloromethane, ethanol and pentane-ether. Glass beads provide a suitable neutral substrate for the transfer of human odour to enable chemical analysis of the human skin emanations for identification of kairomones of anthropophilic mosquitoes. [ABSTRACT FROM AUTHOR]

The indole-derived compounds, which possessed side chains resembling those of changrolin (4-[3',5'-bis[(N-pyrrolidinyl)methyl]-4'-hydroxyaniline]-quinazoline) showed potent anti-arrhythmic activity by restoration of sinus rhythm from ouabain-induced tachycardia in guinea pigs. The potency was assessed by comparison of the maintenance time of sinus rhythm recovered from tachyarrhythmias induced by ouabain. The promising compound was MI2 with piperidyl residue on position 3 & 5 of phenol moiety. There was no difference in anti-arrhythmic activities resulting from substitutions between a benzene ring and methyl residue at position 2 of indole, but the latter had weaker parasympatholytic activity. The anti-arrhythmic activity of MI2 (greater than 60 min) was 2.4 times more potent then changrolin (25 min), but its anti-cholinergic activity was only half of the latter. To compare the suppressive effect on reperfusion-induced arrhythmias by iv MI2 at different time in relation to the ligation-reperfusion protocol, it was the most effective when administered either 30 min prior to coronary occlusion or at the moment of reperfusion. The compound MI might belong to the Ic group shown by the slowing impulse conduction within the heart.