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1.
Proc Natl Acad Sci U S A ; 120(15): e2220228120, 2023 Apr 11.
Artículo en Inglés | MEDLINE | ID: mdl-37011187

RESUMEN

Hydroxyl radical (OH) is a key oxidant that triggers atmospheric oxidation chemistry in both gas and aqueous phases. The current understanding of its aqueous sources is mainly based on known bulk (photo)chemical processes, uptake from gaseous OH, or related to interfacial O3 and NO3 radical-driven chemistry. Here, we present experimental evidence that OH radicals are spontaneously produced at the air-water interface of aqueous droplets in the dark and the absence of known precursors, possibly due to the strong electric field that forms at such interfaces. The measured OH production rates in atmospherically relevant droplets are comparable to or significantly higher than those from known aqueous bulk sources, especially in the dark. As aqueous droplets are ubiquitous in the troposphere, this interfacial source of OH radicals should significantly impact atmospheric multiphase oxidation chemistry, with substantial implications on air quality, climate, and health.

2.
J Am Chem Soc ; 146(30): 20963-20971, 2024 Jul 31.
Artículo en Inglés | MEDLINE | ID: mdl-39031612

RESUMEN

In the realm of nanoscale materials design, achieving precise control over the dimensions of nanotubular architectures poses a substantial challenge. In our ongoing pursuit, we have successfully engineered a novel class of single-molecule nanotubes─isoreticular covalent organic pillars (iCOPs)─by stacking formylated macrocycles through multiple dynamic covalent imine bonds, guided by principles of reticular chemistry. Our strategic selection of rigid diamine linkers has facilitated the synthesis of a diverse array of iCOPs, each retaining a homologous structure yet offering distinct cavity shapes influenced by the linker choice. Notably, three of these iCOP variants feature continuous one-dimensional channels, exhibiting length-dependent host-guest interactions with α,ω-dibromoalkanes, and each presenting a distinct critical guest alkyl chain length threshold for efficient guest encapsulation. This newfound capability not only provides a platform for tailoring nanotubular structures with precision, but also opens new avenues for innovative applications in molecular recognition and the purification of complex mixtures.

3.
J Am Chem Soc ; 146(40): 27429-27442, 2024 Oct 09.
Artículo en Inglés | MEDLINE | ID: mdl-39345027

RESUMEN

Orienting intelligence and multifunction, stretchable semiconductors are of great significance in constructing next-generation human-friendly wearable electronic devices. Nevertheless, rendering semiconducting polymers mechanical stretchability without compromising intrinsic electrical performance remains a major challenge. Combining geometry-innovated inorganic systems and structure-tailored organic semiconductors, a molecular-scale geometric design strategy is proposed to obtain high-performance intrinsically stretchable polymer semiconductors. Originating from the linear regioregular conjugated polymer and corresponding para-modified near-linear counterpart, a series of zigzag-structured semiconducting polymers are developed with diverse ortho-type and meta-type kinking units quantitatively incorporated. They showcase huge edges in realizing stretchability enhancement for conformational transition, likewise with long-range π-aggregation and short-range torsion disorder taking effect. Assisted by additional heteroatom embedment and flexible alkyl-chain attachment, mechanical stretchability and carrier mobility could afford a two-way promotion. Among zigzag-structured species, o-OC8-5% with the initial field-effect mobility up to 1.92 cm2 V-1 s-1 still delivers 1.43 and 1.37 cm2 V-1 s-1 under 100% strain with charge transport parallel and perpendicular to the stretching direction, respectively, accompanied by outstanding performance retention and cyclic stability. This molecular design strategy contributes to an in-depth exploration of prospective intrinsically stretchable semiconductors for cutting-edge electronic devices.

4.
J Chem Phys ; 160(4)2024 Jan 28.
Artículo en Inglés | MEDLINE | ID: mdl-38258926

RESUMEN

Optimizing mechanical performance is crucial for the practical utilization of stimuli-responsive polymers, while complex viscous and elastic behavior hinders a deep understanding of functional polymers under external field excitation. Here, we demonstrate the in situ dynamic and static mechanical responses under electric stimuli of poly(methyl methacrylate) (PMMA) above glass transition temperature (Tg) by applying a direct current electric field vertically to the mechanical loading. The results show that the electro-mechanical response of PMMA is directly correlated to chain relaxation modes with different length scales: for local segments, polarization provides resistance for molecular motion, manifested by enhanced moduli, increased transient viscosity, and a wider linear viscoelastic range, whereas in a larger spatial range, polarization-induced conformation change causes faster relaxation, reduced elastic modulus, and a lowered modulus plateau. Moreover, flow viscosity is reduced because of weaker friction between chain segments under polarization. Our results suggest effective strategies for precisely tuning the viscoelastic behavior of polymers above Tg through electric stimuli.

5.
J Chem Phys ; 160(21)2024 Jun 07.
Artículo en Inglés | MEDLINE | ID: mdl-38832730

RESUMEN

It is highly demanded to understand the confinement effect on nanoconfined polymers. Recent studies reported a strong perturbation of local dynamics and substantial alteration of glass transition temperature Tg at nanoscale. However, how confinement affects the mechanical properties of polymers is not fully understood. Here, we show that the modulus of thin polymer films could be remarkedly altered through a polymer-polymer interface. The modulus of a thin polystyrene (PS) film next to a polydimethylsiloxane (PDMS) was determined from the PS-PDMS bilayer bulging test. A series of experiments show that the modulus of PS can be increased up to 37%, when the modulus of the neighboring PDMS varies from 1.04 to 4.88 MPa. The results demonstrate a strong sensitivity of mechanical properties of thin polymers to the hard/soft environment, which we attribute to the change of high-mobility layer by the polymer-polymer interface.

6.
Appl Opt ; 63(14): D35-D40, 2024 May 10.
Artículo en Inglés | MEDLINE | ID: mdl-38856331

RESUMEN

Compact, magnetic field, B sensing is proposed and demonstrated by combining the two Faraday rotation elements and beam displacement crystals within a micro-optical fiber circulator with a fiber reflector and ferromagnets to allow high contrast attenuation in an optical fiber arm. Low optical noise sensing is measured at λ=1550n m as a change in attenuation, α, of optical light propagating through the rotators and back. The circulator's double-pass configuration, using a gold mirror as a reflector, achieves a magnetic field sensitivity s=Δ α/Δ B=(0.26±0.02)d B/m T with a resolution of Δ B=0.01m T, over a detection range B=0-89m T. The circulator as a platform provides direct connectivity to the Internet, allowing remote sensing to occur. The method described here is amenable to multisensor combinations, including with other sensor technologies, particularly in future integrated waveguide Faraday optical circuits and devices, extending its utility beyond point magnetic field sensing applications.

7.
Angew Chem Int Ed Engl ; 63(19): e202319027, 2024 May 06.
Artículo en Inglés | MEDLINE | ID: mdl-38488819

RESUMEN

Heterocycle-linked phthalocyanine-based COFs with close-packed π-π conjugated structures are a kind of material with intrinsic electrical conductivity, and they are considered to be candidates for photoelectrical devices. Previous studies have revealed their applications for energy storage, gas sensors, and field-effect transistors. However, their potential application in photodetector is still not fully studied. The main difficulty is preparing high-quality films. In our study, we found that our newly designed benzimidazole-linked Cu (II)-phthalocyanine-based COFs (BICuPc-COFs) film can hardly formed with a regular aerobic oxidation method. Therefore, we developed a transfer dehydrogenation method with N-benzylideneaniline (BA) as a mild reagent. With this in hand, we successfully prepared a family of high crystalline BICuPc-COFs powders and films. Furthermore, both of these new BICuPc-COFs films showed high electrical conductivity (0.022-0.218 S/m), higher than most of the reported COFs materials. Due to the broad absorption and high conductivity of BICuPc-COFs, synaptic devices with small source-drain voltage (VDS=1 V) were fabricated with response light from visible to near-infrared. Based on these findings, we expect this study will provide a new perspective for the application of conducting heterocycle-linked COFs in synaptic devices.

8.
Environ Sci Technol ; 57(41): 15580-15587, 2023 10 17.
Artículo en Inglés | MEDLINE | ID: mdl-37804225

RESUMEN

We present experimental evidence that atomic and molecular iodine, I and I2, are produced spontaneously in the dark at the air-water interface of iodide-containing droplets without any added catalysts, oxidants, or irradiation. Specifically, we observe I3- formation within droplets, and I2 emission into the gas phase from NaI-containing droplets over a range of droplet sizes. The formation of both products is enhanced in the presence of electron scavengers, either in the gas phase or in solution, and it clearly follows a Langmuir-Hinshelwood mechanism, suggesting an interfacial process. These observations are consistent with iodide oxidation at the interface, possibly initiated by the strong intrinsic electric field present there, followed by well-known solution-phase reactions of the iodine atom. This interfacial chemistry could be important in many contexts, including atmospheric aerosols.


Asunto(s)
Yodo , Agua , Agua/química , Yoduros/química , Yodo/química
9.
J Chem Phys ; 159(21)2023 Dec 07.
Artículo en Inglés | MEDLINE | ID: mdl-38054519

RESUMEN

The demand for applications, such as coatings, separation filters, and electronic packaging, has greatly driven the research of polymer films. At nanometer scale, mechanical properties of thin polymer films can significantly deviate from bulk. Despite outstanding progresses, there still lack deep discussions on nonlinear viscoelastic-viscoplastic response and their interactions under nanoconfinement. In this work, by conducting measurements via the bubble inflation method and modelling using Schapery and Perzyna equations, we demonstrate nonlinear viscoelastic-viscoplastic properties of freely standing thin polystyrene (PS) films. The results show the unchanged glassy compliance and the rubbery stiffening phenomenon for thin PS films, where the lower rubbery plateau in rubbery stiffening may originate from the induced molecular orientation by plastic deformation. With decreasing film thickness, viscosity and yield stress in viscoplasticity increase in an exponential and a linear trend, respectively, indicating the significant role of nanoconfinement effect on viscoplastic properties. These findings may reveal that there are many properties from linear viscoelasticity to nonlinear viscoelasticity-viscoplasticity that need to be explored and unveiled for sufficient understanding of the nanoconfinement effect on altering mechanical behavior of polymers.

10.
J Sep Sci ; 46(24): e2300473, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-37933715

RESUMEN

Angelica sinensis (Oliv.) Diels. has been used for women to enrich the blood, prevent and treat blood deficiency syndrome in Traditional Chinese Medicine for thousands of years. Wine-processed Angelica sinensis, soil-processed Angelica sinensis, oil-processed Angelica sinensis, and charred-processed Angelica sinensis are the most significant four processed products used in Chinese clinic. However, there have been few studies aimed at comparing their chemical differences. Ultra-high-performance liquid chromatography coupled with quadrupole-orbitrap mass spectrometry combining with nontargeted metabolomics was applied to investigate the diversity of processed products of Angelica sinensis. A total of 74 compounds with the variable importance in the projection value more than 1.5 and P less than 0.05 in ANOVA were highlighted as the compounds that contribute most to the discrimination of Angelica sinensis and four processed products. The results showed the metabolic changes between Angelica sinensis and its four processed products, there were 19 metabolites, 3 metabolites, 6 metabolites, and 45 metabolites were tentatively assigned in soil-processed Angelica sinensis, wine-processed Angelica sinensis, oil-processed Angelica sinensis, and charred-processed Angelica sinensis, respectively. These results suggested that the proposed metabolomics approach was useful for the quality evaluation and control of processed products of Angelica sinensis.


Asunto(s)
Angelica sinensis , Medicamentos Herbarios Chinos , Humanos , Femenino , Medicamentos Herbarios Chinos/análisis , Angelica sinensis/química , Cromatografía Líquida de Alta Presión , Cromatografía de Gases y Espectrometría de Masas , Espectrometría de Masas , Metabolómica , Suelo
11.
Sensors (Basel) ; 23(1)2023 Jan 02.
Artículo en Inglés | MEDLINE | ID: mdl-36617103

RESUMEN

This study presents the analogical assessment of the train-induced vibration and radiated noise in a proposed theater. The theater is to be constructed in a region with crowded metro lines, and the assessment is implemented in an analogical building with comparable structural type and metro condition. Prior to the assessment, the comparability of the analogical building with the theater is validated using the train-induced ground vibration. With the same horizontal distance from the metro line, the train-induced vibration level in the analogical building is 9 dB higher than that in the construction site of the theater. Such results indicate that the lack of soil layers may lead to a dramatic increase in train-induced vibration in the building. In the staircase of the analogical building, the train-induced radiated noise reached 55 dB (A), which is 10 dB (A) higher than the daytime allowable level. As the most important indicator, the noise rating number in the cinema of the analogical building is NR-43, which put forward an enormous challenge on the construction of the theater with a denoise demand of 23 dB. The analogical method applied in this study provides an effective and practical way for the assessment of train-induced vibration and radiated noise in proposed vibration-sensitive buildings. The assessment results that provide necessary reference and support for the anti-vibration design will help guarantee the stage effect of the theater.


Asunto(s)
Ruido del Transporte , Vías Férreas , Ambiente , Vibración , Modalidades de Fisioterapia
12.
Sensors (Basel) ; 23(12)2023 Jun 06.
Artículo en Inglés | MEDLINE | ID: mdl-37420549

RESUMEN

Vehicle-mounted ground-penetrating radar (GPR) has been used to non-destructively inspect and evaluate railway subgrade conditions. However, existing GPR data processing and interpretation methods mostly rely on time-consuming manual interpretation, and limited studies have applied machine learning methods. GPR data are complex, high-dimensional, and redundant, in particular with non-negligible noises, for which traditional machine learning methods are not effective when applied to GPR data processing and interpretation. To solve this problem, deep learning is more suitable to process large amounts of training data, as well as to perform better data interpretation. In this study, we proposed a novel deep learning method to process GPR data, the CRNN network, which combines convolutional neural networks (CNN) and recurrent neural networks (RNN). The CNN processes raw GPR waveform data from signal channels, and the RNN processes features from multiple channels. The results show that the CRNN network achieves a higher precision at 83.4%, with a recall of 77.3%. Compared to the traditional machine learning method, the CRNN is 5.2 times faster and has a smaller size of 2.6 MB (traditional machine learning method: 104.0 MB). Our research output has demonstrated that the developed deep learning method improves the efficiency and accuracy of railway subgrade condition evaluation.


Asunto(s)
Aprendizaje Profundo , Radar , Redes Neurales de la Computación , Aprendizaje Automático
13.
Angew Chem Int Ed Engl ; 62(4): e202215367, 2023 Jan 23.
Artículo en Inglés | MEDLINE | ID: mdl-36428269

RESUMEN

Chiral nanographenes with both high fluorescence quantum yields (ΦF ) and large dissymmetry factors (glum ) are essential to the development of circularly polarized luminescence (CPL) materials. However, most studies have been focused on the improvement of glum , whereas how to design highly emissive chiral nanographenes is still unclear. In this work, we propose a new design strategy to achieve chiral nanographenes with high ΦF by helical π-extension of strongly luminescent chromophores while maintaining the frontier molecular orbital (FMO) distribution pattern. Chiral nanographene with perylene as the core and two dibenzo[6]helicene fragments as the wings has been synthesized, which exhibits a record high ΦF of 93 % among the reported chiral nanographenes and excellent CPL brightness (BCPL ) of 32 M-1 cm-1 .

14.
J Am Chem Soc ; 144(6): 2488-2494, 2022 Feb 16.
Artículo en Inglés | MEDLINE | ID: mdl-35129958

RESUMEN

Chemically stable chromenoquinoline (CQ)-based covalent organic frameworks (COFs) were constructed by postsynthetic conversion of imine COFs. The key step of an intramolecular Povarov reaction can transform a preintegrated alkyne group to bridge the benzene rings on both sides of the imine linkage via chemical bonds, affording a ladder-type CQ linkage. This novel approach achieves a high cyclization degree of 80-90%, which endows the CQ-COFs with excellent chemical stability toward strong acid, base, and redox reagents. The synthetic approach can be applied to various monomers with different symmetries and functional core moieties. The absorption and fluorescence intensities of CQ-COFs are sensitive to acid, which allows for dual-mode sensing of strongly acidic environments.

15.
Sensors (Basel) ; 22(7)2022 Mar 22.
Artículo en Inglés | MEDLINE | ID: mdl-35408065

RESUMEN

In the past 20 years, many studies have been performed on ballast layer inspection and condition evaluation with ground penetrating radar (GPR). GPR is a non-destructive means that can reflect the ballast layer condition (fouling, moisture) by analysing the received signal variation. Even though GPR detection/inspection for ballast layers has become mature, some challenges still need to be stressed and solved, e.g., GPR indicator (for reflecting fouling level) development, quantitative evaluation for ballast fouling levels under diverse field conditions, rapid GPR inspection, and combining analysis of GPR results with other data (e.g., track stiffness, rail acceleration, etc.). Therefore, this paper summarised earlier studies on GPR application for ballast layer condition evaluation. How the GPR was used in the earlier studies was classified and discussed. In addition, how to correlate GPR results with ballast fouling level was also examined. Based on the summary, future developments can be seen, which is helpful for supplementing standards of ballast layer evaluation and maintenance.


Asunto(s)
Radar
16.
J Am Chem Soc ; 143(43): 17958-17963, 2021 Nov 03.
Artículo en Inglés | MEDLINE | ID: mdl-34665638

RESUMEN

The development of helicene molecules with significant chiroptical responses covering a broad range of the visible spectrum is highly desirable for chiral optoelectronic applications; however, their absorption dissymmetry factors (gabs) have been mostly lower than 0.01. In this work, we report unprecedented B,N-embedded double hetero[7]helicenes with nonbonded B and N atoms, which exhibit excellent chiroptical properties, such as strong chiroptical activities from 300 to 700 nm, record high gabs up to 0.033 in the visible spectral range, and tunable circularly polarized luminescence (CPL) from red to near-infrared regions (600-800 nm) with high photoluminescence quantum yields (PLQYs) up to 100%. As revealed by theoretical analyses, the high gabs values are related to the separate molecular orbital distributions owing to the incorporation of nonbonded B and N atoms. The new type of B,N-embedded double heterohelicenes opens up an appealing avenue to the future exploitation of high-performance chiroptical materials.

17.
Small ; 17(36): e2102820, 2021 09.
Artículo en Inglés | MEDLINE | ID: mdl-34319659

RESUMEN

Artificial intelligence vision systems (AIVSs) with information sensing, processing, and storage functions are increasingly gaining attention in the science and technology community. Although synapse phototransistor (SPT) is one of the essential components in AIVSs, solution-processed large-area photonic synapses that can detect and recognize multi-wavelength light are highly desirable. One of the major challenges in this area is the inability of the available materials to distinguish colors from the visible light to the near-infrared (NIR) light for single carrier (hole-only or electron-only) SPTs owing to lack of cognitive elements. Herein, 2D perovskite/organic heterojunction (PEA2 SnI4 /Y6) ambipolar SPTs (POASPTs) are developed via solution process. The POASPTs can display dual-mode learning process, which can convert light signals into postsynaptic currents with excitement/inhibition modes (hole-transporting region) or inhibition/excitement (electron-transporting region). The POASPTs exhibit high responsivity to visible light (104 A W-1 ) and NIR light (200 A W-1 ), and effectively perform learning and memory simultaneously. The flexible POASPT arrays can successfully recognize the images of different colors of light. This study reveals that the fabricated POASPTs have great potentials in the development of large-area, high-efficiency, and low-cost AIVSs.


Asunto(s)
Inteligencia Artificial , Compuestos de Calcio , Óxidos , Titanio
18.
Exp Eye Res ; 190: 107855, 2020 01.
Artículo en Inglés | MEDLINE | ID: mdl-31669404

RESUMEN

Although acute hyperoxia/hypoxia alternation can shift sharply physiological processes of vessel development, e.g. oxygen induced retinopathy (OIR), very little is known of metabolic products resulted from the neovascularization disorder. In this study, the influence of abnormal oxygen exposures on the plasma metabolomic profiles of rats with OIR was investigated by the gas chromatography mass spectrometry (GC-MS). Rat pups were divided into four groups, each with 12 individuals: (i) reared in room air and sampled at P12 (CT1); (ii) exposed to high oxygen for 5 days and sampled at P12 (HO1, simulating the vaso-obeliteration process (phase I)); (iii) reared in room air and sampled at P17 (CT2); (iv) exposed to high oxygen for 5 days then followed by room air for 5 days and sampled at P17 (HO2, simulating the neovasculization one (phase II)). Plasma samples were analyzed with GC-MS, resulted in 122 metabolite species. Distinct differences in the plasma metabolome were found between groups of CT1 vs. HO1, and HO1 vs. HO2, by using univariate and multivariate analyses. Alternating hyperoxia/hypoxia conditions induced significant changes of richness of proline, ornithine and glutamine, that were important components of 'arginine and proline metabolism' pathway. These metabolites contributed largely to plasma sample classification, determined with receiver operating characteristic curve analysis and were involved profoundly in the proline-dependent production of reactive oxygen species (ROS) related to the cellular redox reactions. Our results from the rat OIR model suggest proline and 'arginine and proline metabolism' pathway as the potential biomarkers for human retinopathy of prematurity (ROP) diagnosis.


Asunto(s)
Modelos Animales de Enfermedad , Hiperoxia/sangre , Hipoxia/sangre , Metaboloma/fisiología , Oxígeno/toxicidad , Neovascularización Retiniana/sangre , Retinopatía de la Prematuridad/sangre , Animales , Animales Recién Nacidos , Biomarcadores/sangre , Cromatografía de Gases y Espectrometría de Masas , Glutamina/sangre , Hiperoxia/etiología , Hipoxia/etiología , Metabolómica , Ornitina/sangre , Estrés Oxidativo , Prolina/sangre , Ratas , Ratas Sprague-Dawley , Neovascularización Retiniana/etiología , Retinopatía de la Prematuridad/etiología
19.
J Am Chem Soc ; 141(4): 1406-1414, 2019 Jan 30.
Artículo en Inglés | MEDLINE | ID: mdl-30592898

RESUMEN

Lead halide based organic-inorganic hybrid perovskite (HPVK) materials combine the advantages of solution processing, high absorption coefficient, long charge diffusion length, and high mobility of inorganic framework. The recent interest in this field is mainly focused on solution-processable HPVK for energy conversion and different types of optoelectronics. The performance of HPVK optoelectronics is rivaling now that of conventional devices, but the stability of the HPVK device is now a major challenge in the field where chemists are expected to play more active roles. This Perspective summarizes the progress in the understanding of mechanism of the HPVK formation, and various applications in different fields such as solar cells, light-emitting diodes, lasers, photodetectors, and field-effect transistors. A personal view of the past developments and future challenges is also provided.

20.
J Am Chem Soc ; 141(37): 14643-14649, 2019 09 18.
Artículo en Inglés | MEDLINE | ID: mdl-31448915

RESUMEN

Sensors based on graphene are promising devices for chemical and biological detection owing to their high sensitivity, biocompatibility, and low costs. However, for chiral recognition, which is very important in biological systems, graphene sensors remain unable to discriminate enantiomers. Here, using chiral pesticide molecules as an example, we realized a highly sensitive graphene chiral sensor by modification with acetylcholinesterase (AChE). Quantum chemical simulations indicate that the inhibition effect of the enantiomer on AChE was transferred to graphene, which allowed for the electrical detection of chiral molecules. Under an operating voltage of 1 V, the sensitivity of the device reached 0.34 µg/L and 0.32 µg/L for (+)/(-)-methamidophos, respectively, which is much higher than by circular dichroism (6.90 mg/L and 5.16 mg/L, respectively). Furthermore, real-time, rapid detection was realized by combining with smartphones and wireless transmission.


Asunto(s)
Acetilcolinesterasa/química , Grafito/química , Compuestos Organotiofosforados/análisis , Plaguicidas/análisis , Dicroismo Circular , Límite de Detección , Teoría Cuántica , Ondas de Radio , Teléfono Inteligente , Estereoisomerismo
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