Here, we have performed a series of molecular dynamics simulations to investigate the solvation structures and dynamics of imidazolium-based ionic liquids (i.e., EmimBF4 and BmimBF4) around ...single-walled carbon nanotubes (CNTs) with two different diameters. We make an effort to address the effects of both the alkyl chains of cations and the CNT diameters on the interfacial properties as well as the reasons behind these effects. Our simulation results demonstrate that increasing the CNT diameter can lead to a larger interaction between the ions and the CNTs so that more cations and anions tend to aggregate around the larger CNT, while the alkyl chain is found to have a negligible effect on the relevant structures in the first solvation shell. Meanwhile, the imidazolium rings of cations prefer to be almost parallel to the CNT surface and the preference can be further enhanced by the larger CNT diameter and the longer alkyl chain. On the other hand, either increasing the CNT diameter or the alkyl chain length can result in slower rotational motions of cations around the CNT, but the latter has a more considerable effect, which is significantly different from their effects on the solvation structures. In addition, the anions have the same dependence of their rotational motions around the CNTs on the alkyl chain length as the cations. Our simulation analysis further reveals that the same dependence results from that the alkyl chains of cations can affect the hydrogen bonds between cations and anions so that they have an indirect and considerable influence on the rotational motions of anions.
Full text
Available for:
IJS, KILJ, NUK, PNG, UL, UM
In the synthesis of traditional AIE‐active polymers with conjugate or multi‐benzene system, the troublesome process is still faced such as consuming time, high temperature, catalysis, no water or ...vacuum, and so on. In this study, the polydihydropyrimidone derivatives (PDPMDs) with AIE properties are facilely synthesized by the introduction of 4‐dihydropyrimidone rings onto non‐AIE‐active intermediate polyureas (PUs) in Biginelli reaction. It is found that the unsymmetrical L‐lysine ethyl diisocyanate and butylenediamine played a very important role in the smooth preparation and fluorescence enhancement of PDPMDs. Compared with the intermediate PUs, the fluorescence of PDPMDs is significantly enhanced (35‐fold increase), which is mainly due to the intramolecular aggregation of dihydropyrimidone rings on PUs chains. At the same time, with the increase of the content of dihydropyrimidone rings, the fluorescence intensity of PDPMDs also increases, and the emission wavelength shows an obvious red shift. The fluorescence of PDPMDs also showed obvious dependence on excitation wavelength, which further reveals the clusterization‐triggering emission (CTE) mechanism. In summary, the strategy of endowing AIE properties to non‐AIE active polymer by introducing heterocycles into the backbone through multi‐component reaction provides useful guidance for AIE functionalization of other non‐AIE materials.
AIE‐active polydihydropyrimidones (PDPMDs) can be facilely synthesized by Biginelli reaction through introducing dihydropyrimidone rings onto non‐AIE‐active polyureas chains. The enhanced fluorescence of PDPMDs is actually regulated by the intramolecular “aggregation” of dihydropyrimidone rings based on the cluster triggering emission mechanism.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Aerosol vertical distribution plays a crucial role in cloud development and thus precipitation since both aerosol indirect and semi-direct effects significantly depend on the relative position of ...aerosol layer in reference to cloud, but its precise influence on cloud remains unclear. In this study, we integrated multi-year Raman Lidar measurements of aerosol vertical profiles from the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) facility with available Value-Added Products of cloud features to characterize aerosol vertical distributions and their impacts on warm clouds over the continental and marine ARM atmospheric observatories, i.e., Southern Great Plains (SGP) and Eastern North Atlantic (ENA). A unimodal seasonal distribution of aerosol optical depths (AODs) with a peak in summer is found at upper boundary layer over SGP, while a bimodal distribution is observed at ENA for the AODs at lower levels with a major winter-spring maximum. The diurnal mean of upper-level AOD at SGP shows a maximum in the early evening. According to the relative positions of aerosol layers to clouds we further identify three primary types of aerosol vertical distribution, including Random, Decreasing, and Bottom. It is found that the impacts of aerosols on cloud may or may not vary with aerosol vertical distribution depending on environmental conditions, as reflected by the wide variations of the relations between AOD and cloud properties. For example, as AOD increases, the liquid water paths (LWPs) tend to be reduced at SGP but enhanced at ENA. The relations of cloud droplet effective radius with AOD largely depend on aerosol vertical distributions, particularly showing positive values in the Random type under low-LWP condition (<50 g m−2). The distinct features of aerosol-cloud interactions in relation to aerosol vertical distribution are likely attributed to the continental-marine contrast in thermodynamic environments and aerosol conditions between SGP and ENA.
Display omitted
•Upper-level AOD at SGP peaks in summer and early evening.•A bimodal seasonal distribution is observed at ENA for lower-level AOD.•Random, Decreasing, and Bottom are the primary vertical distributions at both sites.•Aerosols tend to suppress cloud water production at SGP but invigorate it at ENA.•AOD-droplet effective radius relations vary with aerosol vertical distributions.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Fluoride is a common pollutant from nature, normal life, and production. Adsorption, electro-adsorption, and precipitation are dominant mechanisms corresponding to the adsorption and ...electro-adsorption technologies for removing fluoride. This paper presents Ti3AlC2 as an effective reagent for removing fluoride under acidic conditions. The adsorption mechanisms of adsorption and electro-adsorption were compared to sedimentation at pH 2 and 1, leading to a higher removal rate of adsorption by pH 2 than at pH 1. The adsorptive behavior of Ti3AlC2 with fluoride includes both multilayer sorption and chemisorption. Furthermore, the precipitation reaction induced a partial change of Ti3AlC2 to MXene. Notably, electro-adsorption was more effective rather than sedimentation at pH 1 in capacitive deionization technology. The Al adsorption sites made it easier to combine fluoride than Ti, and aluminum fluoride was easier to produce than titanium (III) fluoride. These adsorption and electro-adsorption experiments were carried out to elucidate and delineate the performance of Ti3AlC2 for removing fluoride. A molecular model of Ti3AlC2 was also built to calculate adsorption using the density functional theory. Hence, the Ti3AlC2 molecular model combined with XPS and other characterizations of materials provided an effective, easy-to-understand combinative mechanism for removing fluoride.
Display omitted
•Ti3AlC2 was applied to remove fluoride.•The removal of fluoride was investigated by comparison of adsorption and electro-adsorption.•Different ratios of reaction mechanisms were analyzed by adsorption and electro-adsorption.•The reaction mechanisms were studied by combining experiments and density functional theory.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Type-V-F Cas12f proteins, also known as Cas14, have drawn significant interest within the diverse CRISPR-Cas nucleases due to their compact size. This study involves analyzing and comparing ...Cas14-homology proteins in prokaryotic genomes through mining, sequence comparisons, a phylogenetic analysis, and an array/repeat analysis. In our analysis, we identified and mined a total of 93 Cas14-homology proteins that ranged in size from 344 aa to 843 aa. The majority of the Cas14-homology proteins discovered in this analysis were found within the Firmicutes group, which contained 37 species, representing 42% of all the Cas14-homology proteins identified. In archaea, the DPANN group had the highest number of species containing Cas14-homology proteins, a total of three species. The phylogenetic analysis results demonstrate the division of Cas14-homology proteins into three clades: Cas14-A, Cas14-B, and Cas14-U. Extensive similarity was observed at the C-terminal end (CTD) through a domain comparison of the three clades, suggesting a potentially shared mechanism of action due to the presence of cutting domains in that region. Additionally, a sequence similarity analysis of all the identified Cas14 sequences indicated a low level of similarity (18%) between the protein variants. The analysis of repeats/arrays in the extended nucleotide sequences of the identified Cas14-homology proteins highlighted that 44 out of the total mined proteins possessed CRISPR-associated repeats, with 20 of them being specific to Cas14. Our study contributes to the increased understanding of Cas14 proteins across prokaryotic genomes. These homologous proteins have the potential for future applications in the mining and engineering of Cas14 proteins.
In this study, two simultaneous MALI and Ugi polymerizations in one‐pot was performed by combining binary amines, glutaraldehyde, mercaptoacetic acid and t‐butylisonitrile into one four‐component ...reaction system. The resulting poly(4‐thiazolidinone‐amide)s (PTZAs) contains both thiazolidinone rings from MALI reaction and amide/thiol groups from Ugi reaction, respectively. Unexpectedly, the strong fluorescence emission at 500 nm of PTZA‐E solution is observed under the excitation of 378 nm, which is attributed to the intramolecular “aggregation” of thiazolidinone rings and amide/thiol groups. And also, PTZAs solution showed an excellent aggregation‐induced emission (AIE) by the clusterization‐triggered emission (CTE) mechanism when adding different amount of precipitant. More interestingly, Fe3+ ion violently quenched the fluorescence of PTZA‐E via the redox reaction and spectrum overlaps, and the limit of detection (LOD) of PTZA‐E to Fe3+ ion was measured as 10−4 mol/L. In brief, the two simultaneous polymerizations in one pot provide a great possibility for the polymer with special structure and performance, also including the direct synthesis of AIE‐active polymers from the accessible non‐AIE monomers.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Display omitted
•Alkyl chain has a less effect on the structure and association/dissociation behavior.•Cations with longer alkyl chain have more and stronger hydrogen bonds with anions.•Longer alkyl ...chains lead to slower diffusion and rotation of imidazolium cations.
Here we employ molecular dynamics simulation to study structures, dynamics, and hydrogen bonds of the imidazolium-based ionic liquid mixture, which consists of equimolar EmimBF4 and BmimBF4. Our simulation results demonstrate that the imidazolium rings of both different cations almost show identical structures with BF4− anions regardless of the alkyl chain length. Meanwhile, both kinds of cations almost display the same association/dissociation dynamics with anions. By comparison, the order of diffusion speed is Emim+ > Bmim+ > BF4− while that of rotation speed is BF4− > Emim+ > Bmim+ in the ionic liquid mixture. By analyzing the average numbers of hydrogen bonds (HBs) and the relevant HB dynamics between cations and anions, we find that Bmim+ cations have more and stronger HBs with anions than Emim+ cations, which should be partly responsible for slower diffusion and rotation of Bmim+ cations than those of Emim+ cations. Therefore, this simulation study provides a molecular-level understanding of the role of alkyl chain and HB on the relevant structure and dynamics properties in the imidazolium-based ionic liquid mixture.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Front Cover: In article number 2100284 by Kuilin Deng and co‐workers, AIE‐active polydihydropyrimidones (PDPMDs) can be facilely synthesized by Biginelli reaction through introducing ...dihydropyrimidone rings onto non‐AIE‐active polyureas chains. The enhanced fluorescence of PDPMDs is actually regulated by the intramolecular “aggregation” of dihydropyrimidone rings based on the cluster triggering emission mechanism.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Loop closure detection is a key component of visual simultaneous localization and mapping (VSLM), which can effectively reduce the cumulative error of the system and improve the accuracy of mapping. ...The current loop closure detection method using deep learning can obtain accurate scene descriptions, but it is difficult to cope with the challenge of scene changes. This paper obtains complementary feature maps by fusing the shallow and deep image features of the ResNet50 network, and we incorporate a multiscale channel attention mechanism and a spatial attention mechanism after each layer of the ResNet50 network. The model can effectively extract discriminative scene landmarks, suppress the effects of irrelevant local features on similarity and be more robust to the problem of scene change. The method in this paper has been tested on several publicly available datasets and compared with mainstream methods. The experimental results show that the proposed method significantly outperforms mainstream methods in terms of accuracy-recall performance.
Natural disasters such as debris flow caused by earthquakes seriously threaten the local infrastructure and economy, as well as the lives of people in the area. As the material source of debris flow, ...it has significance to accurately and effectively study the underground structure of the landslide to prevent debris flow disasters. A landslide has a complex structural system, and its underground characteristics play an important role in its stability. The early identification of fracture surfaces and unstable bodies, and assessment of potential hazards are essential for prevention and protection. The research object of this paper is a landslide that occurred in Yige Village, Xianshui Town, Daofu County, which is on the Xianshui River Earthquake Zone, an area subject to frequent earthquakes. In western Sichuan, the frequent occurrence of landslides has caused considerable economic losses. Developing methods for efficient and accurate risk assessment is a top priority. The Daofu landslide is a typical example of a landslide directly threatening the road below and forming a debris flow channel. The lithology is composed of Jurassic sedimentary rocks, such as marl and clay, covered by limestone. In this study, we combined traditional methods (drilling and field investigation) with two geophysical techniques, multichannel analysis of surface waves (MASW) and electrical resistivity tomography (ERT) to effectively determine the electrical characteristics, velocity characteristics and spatial structure of the landslide. It is found that the buried depth of the sliding surface of the landslide is about 16–20 m. The sliding body above the sliding surface forms a low velocity and low resistivity Quaternary cover. The rock mass below the sliding surface is Triassic Zhuwo Formation sandstone and slate with high velocity and high resistivity. According to comprehensive analysis, the landslide lacks sufficient stability under rainstorm. Our study shows that the use of MASW and ERT can quickly and effectively characterize the subsurface of landslides to assess landslide risk and prevent debris flow hazards.
PDF
