Molecular Trap Research Articles

Enhancing insulating properties of glass-fiber reinforced polymers using plasma fluorination-modified boron nitride nanosheets

The insulation failure of glass fiber-reinforced polymers (GFRP) limits their use in high-voltage insulation fields. In this study, boron nitride nanosheets (BNNS) were prepared using ball-milling and further fluorinated via dielectric barrier discharge (DBD) plasma treatment. The GFRP nanocomposites were fabricated using different filler types and doping concentrations. The test results indicated that fluorinated BNNS (F-BNNS) displays good dispersion and interfacial compatibility, enhances the interfacial bonding strength of the “fiber-matrix-filler” ternary system in GFRP, and reduces the internal defects of materials. In addition, the insulating properties of the composites were related to the filler concentration. Adding a trace amount of F-BNNSs increased the flashover and breakdown voltages of the GFRP by up to 28.77% and 21.62%, respectively. The results of molecular dynamics simulations and trap distribution calculations showed that plasma fluorination of BNNS increases the bandgap and deep trap energy level at the interface. The extremely strong charge-binding ability of the deep traps inhibits continuous charge injection and regulates carrier migration, which improves the insulating properties of the composites. The results of this study provide a novel, environmentally friendly, and efficient solution for improving the insulating properties of GFRP.

Highly Efficient Separation of Intermediate-Size m-Xylene from Xylenes via a Length-Matched Metal-Organic Framework with Optimal Oxygen Sites Distribution.

Xylene separation is crucial but challenging, especially for the preferential separation of the intermediate-size m-xylene from xylene mixtures. Herein, exploiting the differences in molecular length and alkyl distribution among xylenes, we present a length-matched metal-organic framework, formulated as Al(OH)[O2C-C4H2O-CO2], featuring an effective pore size corresponding to m-xylene molecular length combined with multiple negative O hydrogen bond donors distribution, can serve as a molecular trap for efficient preferential separation of the intermediate-size m-xylene. Benchmark separation performance was achieved for separating m-xylene from a ternary mixture of m-xylene/o-xylene/p-xylene, with simultaneous record-high m-xylene uptake (1.3 mmol g-1) and m-xylene/p-xylene selectivity (5.3) in the liquid-phase competitive adsorption. Both vapor- and liquid-phase fixed-bed tests confirmed its practical separation capability with benchmark dynamic m-xylene/p-xylene and m-xylene/o-xylene selectivities, as well as excellent regenerability. The selective and strong m-xylene binding affinity among xylene molecules was further elucidated by simulations, validating the effectiveness of such a pore environment for the separation of intermediate-size molecules.

Highly Efficient Separation of Intermediate‐Size m‐Xylene from Xylenes via a Length‐Matched Metal–Organic Framework with Optimal Oxygen Sites Distribution

AbstractXylene separation is crucial but challenging, especially for the preferential separation of the intermediate‐size m‐xylene from xylene mixtures. Herein, exploiting the differences in molecular length and alkyl distribution among xylenes, we present a length‐matched metal–organic framework, formulated as Al(OH)[O2C−C4H2O−CO2], featuring an effective pore size corresponding to m‐xylene molecular length combined with multiple negative O hydrogen bond donors distribution, can serve as a molecular trap for efficient preferential separation of the intermediate‐size m‐xylene. Benchmark separation performance was achieved for separating m‐xylene from a ternary mixture of m‐xylene/o‐xylene/p‐xylene, with simultaneous record‐high m‐xylene uptake (1.3 mmol g−1) and m‐xylene/p‐xylene selectivity (5.3) in the liquid‐phase competitive adsorption. Both vapor‐ and liquid‐phase fixed‐bed tests confirmed its practical separation capability with benchmark dynamic m‐xylene/p‐xylene and m‐xylene/o‐xylene selectivities, as well as excellent regenerability. The selective and strong m‐xylene binding affinity among xylene molecules was further elucidated by simulations, validating the effectiveness of such a pore environment for the separation of intermediate‐size molecules.

High-throughput phase field simulation and machine learning for predicting the breakdown performance of all-organic composites

All-organic dielectric polymers are materials of choice for modern power electronics and high-density energy storage, and their performance can be significantly improved by doping trace amounts of organic molecular semiconductors with strong electron-affinity energy to suppress charge conduction losses. Insight into the breakdown mechanism of polymers/organic molecular semiconductor composites is essential for the design of high-performance dielectric polymers. This study investigates the impact of the doping concentration of organic molecular semiconductors, dielectric constants, and trap depths on the breakdown performance of dielectric polymers under high temperature and electric fields. A modified phase-field model, incorporating deep traps and carriers’ coulomb capture radius, has been developed to facilitate high-throughput simulations of electrical breakdown in polymer/organic molecular semiconductor composites. This work accurately predicted the breakdown strength of all-organic composites using high-throughput phase-field simulation data as input for machine learning, which provides crucial theoretical support for designing all-organic composite dielectric polymers for energy storage capacitors under extreme conditions.

The SAMHD1-MX2 axis restricts HIV-1 infection at postviral DNA synthesis.

In contrast to most restriction factors that directly bind to viral components to exert their antiviral effects, SAMHD1, the only known deoxynucleotide triphosphate (dNTP) hydrolase in eukaryotes, indirectly inhibits viral replication in quiescent cells by reducing the pool of dNTP substrates available for viral cDNA synthesis. Our study provides a novel perspective on the antiviral functions of SAMHD1. In addition to its role in dNTP hydrolysis, SAMHD1 cooperates with MX2 to inhibit HIV-1 nuclear import. In this process, SAMHD1 acts as a sensor for incoming HIV-1 cores, detecting and binding to them, before subsequently delivering the complex to the molecular trap formed by MX2, thereby immobilizing the virus. This study not only reveals a new antiviral pathway for SAMHD1 but also identifies a unique collaboration and interaction between two distinct restriction factors, establishing a novel line of defense against HIV-1 infection, which challenges the traditional view of restriction factors acting independently. Overall, our findings further indicate the intricate complexity of the host immune defense network and provide potential targets for promoting host antiviral immune defense.

Star-shaped hosts based on phenyls substituted carbazole: Effects of trifluoromethyl and tert-butyl moieties

To investigate the effects of trifluoromethyl and tert-butyl moieties on the general optoelectronic properties of star-shaped hosts based on phenyls substituted carbazole, we used 3,6,9-tris (4-(tert-butyl)-phenyl)-9H-carbazole (M1) as a reference, and different numbers of electron-withdrawing 3,5-bis(trifluoromethyl) benzene were introduced into 3, 6 and 9 positions of carbazole to obtain compounds 9-(3,5-bis(trifluoromethyl)phenyl)-3,6-bis(4-(tert-butyl)phenyl)-9H-carbazole (M3), 3,6-bis(3,5-bis(trifluoromethyl)phenyl)-9-(4-(tert-butyl)phenyl)-9H-carbazole (M5) and 3,6,9-tris(3,5-bis(trifluoromethyl)phenyl)-9H-carbazole (M6). After the introduction of 3,5-bis (trifluoromethyl) benzene, the thermal temperature at 5 % mass loss of M3, M5 and M6 decreased to 344 °C, while the glass transition temperature and melting point of M3 and M5 showed a significant increase. However, M6 did not show obvious glass transition, but its melting point also showed a significant increase. M3 crystallized at 125 °C as evidenced by differential scanning calorimetry, and the linking model of M3 is helpful to crystalize. In addition, when compared with those of M1, the fluorescence emission peaks of M3 and M6 showed a blue-shift, while M5 showed a red-shift, all of which were in the deep blue emission range. The color purity of blue light for M1 in tetrahydrofuran solution is the highest, and M1 exhibit aggregation-induced emission characteristics. Compared to the photoluminescence quantum efficiency (PLQY) of compound M1 of 39 % in toluene, the PLQYs of M3 and M6 decreased to 34 % and 29 %, and the PLQY of M5 increased to 46 %. The function of the lowest unoccupied molecular orbital trap of M3 film under the external electrical field will increase, which not only offsets the increasing effect of the electrical field to the electron carrier and further decreases the carrier mobility when the electrical field increase, and the same situation is also feasible for the highest occupied molecular orbital traps in M5, M6 and M1. The organic blue light emitting diodes were prepared by using M1, M3, M5 and M6 as the hosts of bis [2-(4,6-difluorophenyl)pyridinato-C2,N](picolinato)iridium, and the optimized device of M1 as the host showed the best performance with a maximum luminescence brightness of 2978 cd/m2, maximum current efficiency of 39.42 cd/A and maximum external quantum efficiency of 18.36 %.

Mechanism Study of Molecular Trap in All-Organic Polystyrene-Based Dielectric Composite.

It is a huge challenge to explore how charge traps affect the electric breakdown of polymer-based dielectric composites. In this paper, alkane and aromatic molecules with different substituents are investigated according to DFT theoretical method. The combination of strong electron-withdrawing groups and aromatic rings can establish high electron affinity molecules. 4'-Nitro-4-dimethylaminoazobenzene (NAABZ) with a vertical electron affinity of 1.39eV and a dipole moment of 10.15 D is introduced into polystyrene (PSt) to analyze the influence of charge traps on electric properties. Marcus charge transfer theory is applied to calculate the charge transfer rate between PSt and NAABZ. The nature of charge traps is elaborated from a dynamic perspective. The enhanced breakdown mechanism of polymers-based composites stems from the constraint of carrier mobility caused by the change in transfer rate. But the electrophile nature of high electron affinity filler can decrease the potential barriers at the metal-polymer interface. Simultaneously, the relationship between the electron affinity of fillers and the breakdown strength of polymer-based composites is nonlinear because of the presence of the inversion region. Based on the deep understanding of the molecular trap, this work provides the theoretical calculation for the design and development of high-performance polymer dielectrics.

Porous materials with suitable pore size and dual‐functional sites for benchmark one‐step ethylene purification

AbstractMultiple impurities removal represents one of the most daunting challenges in gas purification, but the attainment of efficient adsorptive separation is hindered by the difficulty in designing adsorbents that could simultaneously capture different impurities. Herein, we revealed a molecular trap within Zn‐trz‐ox (trz = 1,2,4‐triazole; ox = oxalic acid) that featured positive H and negative O sites, and the suitable pore size, which exhibited remarkable one‐step C2H4 purification performance directly from quaternary C2H4/C2H2/C2H6/CO2 mixtures. The separation selectivities of C2H4 with respect to CO2, C2H2, and C2H6 are 9.8, 2.6, and 2.5, higher than the sole adsorbent yet reported. Meanwhile, polymer grade C2H4 (≥99.95%) could be directly obtained with record C2H4 productivity of 1.5 mol kg−1, over 10 times higher than that of the previous benchmark material. The deep insight into the binding behavior revealed by simulation studies offers important clues for the design of advanced adsorbent for multiple impurities capture.

Investigation of temperature-dependent DC breakdown characteristics of nano-Al2O3/epoxy composites at low temperatures

Epoxy resin is extensively utilized as an insulating material in low-temperature superconducting devices. Nevertheless, its breakdown behavior and mechanism at low temperatures have rarely been studied. This study aims to investigate the breakdown characteristics of bisphenol F epoxy resin and its nano-alumina composites under different temperatures. Additionally, a thermally stimulated current (TSC) platform was established to examine the molecular relaxation and trap charge parameters of epoxy from 4.2 K to 300 K. The epoxy resin matrix was modified by incorporating a series of nano-alumina particles (1%, 2%, 3%, 4%, 5%). In this paper, a breakdown transition temperature (Tb) between 77 K and 150 K was observed for epoxy resin, with a significant decline in insulation performance above and below Tb. This phenomenon can be attributed to the interplay between collisional ionization and thermal breakdown mechanisms. The inclusion of nano-alumina particles in the epoxy resin matrix demonstrates an improvement in insulation performance at low temperatures, with an optimal filler ratio of approximately 2%. However, an excessive amount of alumina nanoparticles may reduce the insulating capabilities of the epoxy resin. The experiments conducted on thermally stimulated currents revealed that trap charges within the resin are more readily excited at low temperatures.

Hierarchical porous MOFs@COFs-based molecular trap solid-phase microextraction for efficient capture of PAHs and adsorption mechanisms

In view of the serious carcinogenic, teratogenic and mutagenic properties of polycyclic aromatic hydrocarbons (PAHs), which cause significant harm to human beings and the environment. Therefore, developing rapid adsorption and efficient analytical methods are research topic with practical significance. Herein, an innovative MOFs@COFs-based molecular trap materials were prepared with hierarchical porous core–shell structure and used as solid-phase microextraction (SPME) fiber coating, which combined with high performance liquid chromatography (HPLC) to achieve the efficient separation, capture, and detection for 7 PAHs in real samples. The possible adsorption mechanism was systematically verified and explained. Under the optimized conditions, the method developed in this experiment had a wide linear range (0.005–400 µg·L−1) with a good linear correlation coefficient (R2 > 0.9984), low detection limits (0.002–0.405 µg·L−1, S/N = 3) and low quantification limits (0.005–1.351 µg·L−1, S/N = 10). The relative standard deviations of individual fibers and different batches of fibers were 0.26–3.64% and 0.40–5.91%, respectively. Besides, the fiber showed higher enrichment capacity and extraction efficiency for PAHs compared to commercial SPME fibers and other material fibers, and exhibited excellent acid-base stability and reproducibility. This work provided a favorable synthetic pathway for the preparation of MOFs@COFs composites by layer-modified assembly synthesis strategy, showed excellent practical applicability as a SPME fiber coating combined with HPLC, and could be realized to provide technical support for future studies on the separation, adsorption, and analysis of PAHs in the petrochemical industrial zone of the Yellow River Basin.

Blue-detuned molecular magneto-optical trap schemes based on Bayesian optimization

Blue-detuned molecular magneto-optical trap schemes based on Bayesian optimization

"Using the Power of Nature Against Pathogens Searching for Antiviral Peptides Effective Against SARS-CoV-2 (In Fish, Bats, and Humans)"

Today our society is under increasing threat due to infectious diseases. The current pandemic is just a warning sign of this problem. With the spread of antibiotic resistance, there is a growing need to discover new, effective, antimicrobial drugs. Antimicrobial peptides are “medicines” of nature which may be able to fill the role of lost antibiotics. They can be used not only against bacteria, but also against viruses and fungi. The main purpose of our research is a development of a molecular trap which can separate antimicrobials from hosts which synthetizing them against pathogens. These antimicrobials are produced likely in all living organisms.

Open-Cage Fullerene as a Selective Molecular Trap for LiF/[BeF

The insertion of ionic compounds into open-cage fullerenes is a challenging task due to the electropositive nature of the cavity. The present work reports the preparation of an open-cage C60 derivative with a hydroxy group pointing towards the centre of the cavity, which can coordinate to a metal cation, thus acting as a bait/hook to trap the metal cation such as the lithium cation in neutral LiF and the beryllium cation in the cationic [BeF]+ species. Other metal salts could not be inserted under similar conditions. The structure of MF in the cage was unambiguously determined by single-crystal X-ray diffraction. Owing to its tendency to undergo polycoordination, Li+ monomer salts have not been isolated before, despite extensive research on Li bonds. The present results provide a unique example of a Li bond.

Open‐Cage Fullerene as a Selective Molecular Trap for LiF/[BeF]+

AbstractThe insertion of ionic compounds into open‐cage fullerenes is a challenging task due to the electropositive nature of the cavity. The present work reports the preparation of an open‐cage C60 derivative with a hydroxy group pointing towards the centre of the cavity, which can coordinate to a metal cation, thus acting as a bait/hook to trap the metal cation such as the lithium cation in neutral LiF and the beryllium cation in the cationic [BeF]+ species. Other metal salts could not be inserted under similar conditions. The structure of MF in the cage was unambiguously determined by single‐crystal X‐ray diffraction. Owing to its tendency to undergo polycoordination, Li+ monomer salts have not been isolated before, despite extensive research on Li bonds. The present results provide a unique example of a Li bond.

Molecular Trap Engineering Enables Superior High‐Temperature Capacitive Energy Storage Performance in All‐Organic Composite at 200 °C

AbstractDielectric capacitors are essential components of advanced high‐power electrical and electronic systems for electrical energy storage. The drastic reductions in the energy density and the charge‐discharge efficiency of dielectric polymers at elevated temperatures, owing to sharply increased electrical conduction, remain a major challenge. While substantial progress has been made in enhancing the high‐temperature capacitive performance of dielectric polymers, the improvement has been rather limited when the temperature exceeds 150 °C. Here, a universal approach to the control of the energy level of charge traps in all‐organic polymer composites by substituent engineering of organic semiconductors, leading to significantly suppressed high‐field high‐temperature conduction loss and improved capacitive performance is reported. At 200 °C, the polymer/organic semiconductor composite delivers ultrahigh energy densities of 3.4 and 5.0 J cm−3 with an efficiency >90% at 10 and 100 Hz, respectively, outperforming the current dielectric polymers and composites. The underlying mechanism of the improved performance is revealed experimentally and confirmed computationally. Moreover, excellent cyclability and the ability to be fabricated into large‐area high‐quality films with uniform performance, along with an ultralow filler loading, further demonstrate the potential of molecularly engineered organic semiconductors for dielectric polymer composites operating under extreme conditions.

Effect of TiO2 modified with dopamine and Silane coupling agent on the electrical properties of PMIA insulation paper

AbstractPoly‐m‐phenyleneisophthalamide (PMIA) with excellent chemical stability and breakdown strenth is regarded as the next generation of insulating paper in power system. However, the basic intensity of PMIA is not enough to match its operating cost, and it is promising to enhance the performance by nano composition. In this paper, the influence of nano‐TiO2ith a mass fraction of 1 to 5 wt% on insulating properties is studied, including breakdown voltage and bulk conductivity. The silane coupling agent aminopropyltriethoxysilane (APTES) together with the polydopamine (PDA) are used for modifying the fillers interface. The results show that, APTES covalent grafting and PDA physically coating can improve the dispersion and compatibility of nano‐TiO2 in aramid fiber matrix, thus regulating the interface trap characteristics and reducing the probability of electric field distortion in insulating paper. When the modified TiO2 content is 2 wt%, the breakdown voltage is the highest, which is 23.9 kV/mm, 54% higher than that of pure aramid paper. In addition, this article discusses the modification mechanism from molecular dynamic simulation and trap characteristics. Based on molecular dynamics calculation, three interface models of PMIA‐TiO2, PMIA‐TiO2/APTES, PMIA‐TiO2/APTES/PDA are constructed, and the synergistic effect of PDA is confirmed from the microscopic level.

Interplay between Polaritonic and Molecular Trap States.

Strong exciton–photon coupling exhibits the possibility to modify the photophysical properties of organic molecules. This is due to the introduction of hybrid light–matter states, called polaritons, which have unique physical and optical properties. Those strongly coupled systems provide altered excited-state dynamics in comparison to the bare molecule case. In this study, we investigate the interplay between polaritonic and molecular trap states, such as excimers. The molecules used in this study show either prompt or delayed emission from trap states. For both cases, a clear dependency on the exciton–photon energy tuning was observed. Polaritonic emission gradually increased with a concurrent removal of aggregation-induced emission when the systems were tuned toward lower energies. For prompt emission, it is not clear whether the experimental results are best explained by a predominant relaxation toward the lower polariton after excitation or by a direct excimer to polariton transition. However, for the delayed emission case, trap states are formed on the initially formed triplet manifold, making it evident that an excimer-to-polariton transition has occurred. These results unveil the possibility to control the trap state population by creating a strongly coupled system, which may form a mitigation strategy to counteract detrimental trap states in photonic applications.

The Long Pentraxin PTX3 as a New Biomarker and Pharmacological Target in Age-Related Macular Degeneration and Diabetic Retinopathy.

Age related macular degeneration (AMD) and diabetic retinopathy (DR) are multifactorial, neurodegenerative and inflammatory diseases of the eye primarily involving cellular and molecular components of the outer and inner blood-retina barriers (BRB), respectively. Largely contributed by genetic factors, particularly polymorphisms in complement genes, AMD is a paradigm of retinal immune dysregulation. DR, a major complication of diabetes mellitus, typically presents with increased vascular permeability and occlusion of the retinal vasculature that leads, in the proliferative form of the disease, to neovascularization, a pathogenic trait shared with advanced AMD. In spite of distinct etiology and clinical manifestations, both pathologies share common drivers, such as chronic inflammation, either of immune (in AMD) or metabolic (in DR) origin, which initiates and propagates degeneration of the neural retina, yet the underlying mechanisms are still unclear. As a soluble pattern recognition molecule with complement regulatory functions and a marker of vascular damage, long pentraxin 3 (PTX3) is emerging as a novel player in ocular homeostasis and a potential pharmacological target in neurodegenerative disorders of the retina. Physiologically present in the human eye and induced in inflammatory conditions, this protein is strategically positioned at the BRB interface, where it acts as a “molecular trap” for complement, and modulates inflammation both in homeostatic and pathological conditions. Here, we discuss current viewpoints on PTX3 and retinal diseases, with a focus on AMD and DR, the roles therein proposed for this pentraxin, and their implications for the development of new therapeutic strategies.

Selective perrhenate/pertechnetate removal by a MOF-based molecular trap.

A rational design of anion-exchange materials for the selective elimination of radioactive anionic contaminants poses a great challenge. Rather than relying on a size-compatible effect, the combination of a nano-sieve pore, hydrophobic cationic cavity, and soft-acidic open metal sites within one sorbent is an emerging strategy for meeting the requirement. Here, we designed a porous cationic Ag(I) metal-organic framework (MOF), TNU-132, which combined multiple features and showed superior perrhenate/pertechnetate capture selectivity in the presence of a large excess of 300-fold NO3- and 2000-fold SO42-. The mechanism of this high selectivity can be well elucidated by the anion exchange experiments of TNU-132 in the Cr2O72-/ReO4- mixture. That is, the separation process underwent two sequential steps, the nano-sieving procedure and then a reconstruction process in the crystalline sorbent. These results were further confirmed by scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDS), and/or single-crystal X-ray diffraction (SC-XRD) of oxoanion-loaded materials.

BEHAVIOUR OF METHYLCELLULOSE GEL AT HIGHER CONCENTRATIONS FOR CLEANING OF ACRYLIC PAINTED SURFACES

This research demonstrates the application of methylcellulose (MC) as a gelator for cleaning acrylic painted surfaces. Highly thickened methylcellulose gels were predominantly tested to investigate the residue left after cleaning. The function of methylcellulose as a molecular trap was also assessed to minimize the clearance issue. The presence of residue, the efficacy of the methylcellulose as a cleaning agent and its physical impact on the paint surfaces were investigated using a digital microscope in normal, raking, and ultraviolet lights. Scanning electron microscopy (SEM), coupled with energy-dispersive X-ray spectroscopy (EDS) was used to study the compositional and topographical changes on the paint surface. Fourier transform infrared spectroscopy (FTIR) was performed in attenuated total reflectance (ATR) mode to observe the presence of residues after complete removal of the gelling agent. The experimental results indicated a minimum interaction of methylcellulose on the paint surface as the concentration increases in the gel formulation. The super-thickened hydrogels also worked like molecular traps useful for removal of soiling from the painted surfaces.