Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 256
Filtrar
1.
Quant Imaging Med Surg ; 14(5): 3289-3301, 2024 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-38720846

RESUMEN

Background: The blood volume of intraparenchymal vessels is reported to be increased in smokers. However, the blood volume can be affected by many confounders besides tobacco exposure. This study aimed to investigate the association between cigarette smoking and pulmonary blood volume after adjusting the related factors in a large cohort of Chinese males. Methods: In this retrospective study, male participants admitted to the First Affiliated Hospital of Xi'an Jiaotong University for annual health assessment between February 2017 and February 2018 were enrolled. All subjects underwent non-contrast chest computed tomography (CT) scans, and 152 subjects underwent a review CT scan 2-3 years later. A three-dimensional approach was employed to segment the lung and intrapulmonary vessels and quantitative CT (QCT) measurements, including lung volume (LV), intrapulmonary vessel volume (IPVV), low-attenuation area <-950 Hounsfield unit (LAA-950 and LAA-950%), and mean lung density (MLD). Linear regression was used to estimate the association between IPVV and the smoking index (SI). A paired t-test was used to compare the QCT parameters between the initial and follow-up CT scans. Results: A total of 656 male participants were enrolled and classified into three subgroups: non-smokers (n=311), current smokers (n=267), and former smokers (n=78). The IPVV of current smokers (134.62±23.96 vs. 120.76±25.52 mL) and former smokers (130.79±25.13 vs. 120.76±25.52 mL) were significantly larger than that of non-smokers (P<0.05). A higher SI was associated with greater IPVV [non-standardized coefficient: 0.167, 95% confidence interval (CI): 0.086-0.248]. For current smokers, the IPVV of the follow-up scan significantly increased compared to its baseline scan (135.49±28.60 vs. 129.73±29.75 mL, t=-2.326, P=0.02), but for the non-smokers and former smokers, the IPVV of the follow-up scan did not increase or decrease compared to the baseline scan (P>0.05). Conclusions: Pulmonary vascular volumes detectable on non-contrast CT are associated with cigarette exposure, and smoking cessation may prevent pulmonary vasculature remodeling.

2.
Angew Chem Int Ed Engl ; : e202405062, 2024 May 06.
Artículo en Inglés | MEDLINE | ID: mdl-38711169

RESUMEN

Palladium-catalyzed enantioselective C(sp3)-H functionalization reactions has attracted considerable attention due to its ability for the synthesis of enantiomerically enriched molecules and stimulation of novel retrosynthetic disconnections. Understanding the reaction mechanism, especially the stereochemical process of the reaction, is crucial for the rational design of more efficient catalytic systems. Previously, we developed a Pd(II)/sulfoxide-2-hydroxypridine (SOHP) catalytic system for asymmetric C(sp3)-H functionalization reactions. In this study, we focused on unraveling the chemistry of chiral palladacycles involved in the Pd(II)-catalyzed enantioselective C(sp3)-H functionalization. We have isolated key palladacycle intermediates involved in the enantioselective ß-C(sp3)-H arylation of carboxylic acids catalyzed by the Pd(II)/SOHP system. These palladacycles, exhibiting ligand-induced chirality, provided a significant opportunity to investigate the stereochemical process and the ligand effect in this asymmetric C-H functionalization. Our investigation provided direct evidence for the C-H palladation step as the enantioselectivity-determining step, which forms diastereomeric palladacycles that exhibited preservation of chirality in the functionalization step. DFT calculations provided insights into the chiral induction in palladacycle formation. This work highlights the value of chiral palladacycle chemistry in offering mechanistic insights into the Pd(II)-catalyzed asymmetric C(sp3)-H functionalization reactions.

3.
Sci China Life Sci ; 2024 May 16.
Artículo en Inglés | MEDLINE | ID: mdl-38761356

RESUMEN

Cardiac conduction regulatory RNA (CCRR) has been documented as an antiarrhythmic lncRNA in our earlier investigation. This study aimed to evaluate the effects of CCRR on SERCA2a and the associated Ca2+ homeostasis in myocardial infarction (MI). Overexpression of CCRR via AAV9-mediated delivery not only partially reversed ischemia-induced contractile dysfunction but also alleviated abnormal Ca2+ homeostasis and reduced the heightened methylation level of SERCA2a following MI. These effects were also observed in CCRR over-expressing transgenic mice. A conserved sequence domain of CCRR mimicked the protective function observed with the full length. Furthermore, silencing CCRR in healthy mice led to intracellular Ca2+ overloading of cardiomyocytes. CCRR increased SERCA2a protein stability by upregulating FTO expression. The direct interaction between CCRR and FTO protein was characterized by RNA-binding protein immunoprecipitation (RIP) analysis and RNA pulldown experiments. Activation of NFATc3 was identified as an upstream mechanism responsible for CCRR downregulation in MI. This study demonstrates that CCRR is a protective lncRNA that acts by maintaining the function of FTO, thereby reducing the m6A RNA methylation level of SERCA2a, ultimately preserving calcium homeostasis for myocardial contractile function in MI. Therefore, CCRR may be considered a promising therapeutic strategy with a beneficial role in cardiac pathology.

4.
J Am Chem Soc ; 146(11): 7140-7145, 2024 Mar 20.
Artículo en Inglés | MEDLINE | ID: mdl-38466365

RESUMEN

Molecular photocatalysis has shown tremendous success in sustainable energy and chemical synthesis. However, visualizing the transient open-shell intermediates in photocatalysis is a significant and long-standing challenge. By employing our recently developed innovative time-resolved electron paramagnetic resonance technique, we directly observed all radicals and radical ions involved in the photocatalytic addition of pempidine to tert-butyl acrylate. The full picture of the photocatalytic cycle is vividly illustrated by the fine structures, chemical kinetics, and dynamic spin polarization of all open-shell intermediates directly observed in this prototypical system. Given the universality of this methodology, we believe it greatly empowers the research paradigm of direct observation in both photocatalysis and radical chemistry.

5.
Chem Commun (Camb) ; 60(26): 3575-3578, 2024 Mar 26.
Artículo en Inglés | MEDLINE | ID: mdl-38470032

RESUMEN

ZnO quantum dots (QDs) supported on porous nitrogen-doped carbon (ZnOQDs/P-NC) exhibited excellent electrochemical performance for the electroreduction of CO2 to CO with a faradaic efficiency of 95.3% and a current density of 21.6 mA cm-2 at -2.2 V vs. Ag/Ag+.

6.
Chem Commun (Camb) ; 60(25): 3405-3408, 2024 Mar 21.
Artículo en Inglés | MEDLINE | ID: mdl-38440822

RESUMEN

A multicomponent covalent organic framework (COF-Tfp-BpyDaaq) integrating bipyridine with diaminoanthraquinone through a triformylphoroglucinol linkage was synthesized for the first time as a photocatalyst for overall H2O2 photosynthesis. It exhibits enhanced photo-charge separation and H2O2 production rate over its two-component counterparts, demonstrating the pivotal role of multicomponent synthesis in designing efficient photocatalysts.

7.
Anal Chem ; 2024 Feb 07.
Artículo en Inglés | MEDLINE | ID: mdl-38324915

RESUMEN

Nanozymes with peroxidase (POD)-like activity have garnered significant attention due to their exceptional performance in colorimetric assays. However, nanozymes often possess oxidase (OD) and POD-like activity simultaneously, which affects the accuracy and sensitivity of the detection results. To address this issue, inspired by the catalytic pocket of natural POD, a single-atom nanozyme with FeN5 configuration is designed, exhibiting enhanced POD-like activity in comparison with a single-atom nanozyme with FeN4 configuration. The axial N atom in FeN5 highly mimics the amino acid residues in natural POD to optimize the electronic structure of the metal active center Fe, realizing the efficient activation of H2O2. In addition, in the presence of both H2O2 and O2, FeN5 enhances the activation of H2O2, effectively avoiding the interference of dissolved oxygen in colorimetric sensing. As a proof-of-concept application, a colorimetric detection platform for uranyl ions (UO22+) in seawater is successfully constructed, demonstrating satisfactory sensitivity and specificity.

8.
Nano Lett ; 24(9): 2912-2920, 2024 Mar 06.
Artículo en Inglés | MEDLINE | ID: mdl-38391386

RESUMEN

Nanozymes with peroxidase-like activity have been extensively studied for colorimetric biosensing. However, their catalytic activity and specificity still lag far behind those of natural enzymes, which significantly affects the accuracy and sensitivity of colorimetric biosensing. To address this issue, we design PdSn nanozymes with selectively enhanced peroxidase-like activity, which improves the sensitivity and accuracy of a colorimetric immunoassay. The peroxidase-like activity of PdSn nanozymes is significantly higher than that of Pd nanozymes. Theoretical calculations reveal that the p-d orbital hybridization of Pd and Sn not only results in an upward shift of the d-band center to enhance hydrogen peroxide (H2O2) adsorption but also regulates the O-O bonding strength of H2O2 to achieve selective H2O2 activation. Ultimately, the nanozyme-linked immunosorbent assay has been successfully developed to sensitively and accurately detect the prostate-specific antigen (PSA), achieving a low detection limit of 1.696 pg mL-1. This work demonstrates a promising approach for detecting PSA in a clinical diagnosis.


Asunto(s)
Técnicas Biosensibles , Peróxido de Hidrógeno , Masculino , Humanos , Antígeno Prostático Específico , Inmunoensayo/métodos , Antioxidantes , Peroxidasas , Colorimetría/métodos , Técnicas Biosensibles/métodos
9.
Biochim Biophys Acta Mol Cell Res ; 1871(3): 119656, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-38182060

RESUMEN

Diabetic cardiomyopathy remains a formidable health challenge with a high mortality rate and no targeted treatments. Growth differentiation factor 11 (GDF11) has shown promising effects on cardiovascular diseases; however, its role and the underlying mechanism in regulating diabetic cardiomyopathy remain unclear. In this study, we developed mouse models of diabetic cardiomyopathy using leptin receptor-deficient (db/db) mice and streptozocin-induced C57BL/6 mice. The diabetic cardiomyopathy model mice exhibited apparent structural damage in cardiac tissues and a significant increase in the expression of apoptosis-related proteins. Notably, we observed a significant decreased expression of GDF11 in the myocardium of mice with diabetic cardiomyopathy. Moreover, GDF11 cardiac-specific knock-in mice (transgenic mice) exhibited improved cardiac function and reduced apoptosis. Moreover, exogenous administration of GDF11 mitigated high glucose-induced cardiomyocyte apoptosis. Mechanistically, we demonstrated that GDF11 alleviated high glucose-induced cardiomyocytes apoptosis by inhibiting the activation of the alkylation repair homolog 5 (ALKBH5)-forkhead box group O3a (FOXO3)-cerebellar degeneration-related protein 1 transcript (CDR1as)/Hippo signaling pathway. Consequently, this novel mechanism effectively counteracted myocardial cell apoptosis, providing valuable insights into potential therapeutic strategies for clinical diabetic cardiomyopathy.


Asunto(s)
Cardiomiopatías Diabéticas , Miocitos Cardíacos , Ratones , Animales , Miocitos Cardíacos/metabolismo , Cardiomiopatías Diabéticas/inducido químicamente , Cardiomiopatías Diabéticas/metabolismo , Vía de Señalización Hippo , Ratones Endogámicos C57BL , Factores de Diferenciación de Crecimiento/genética , Factores de Diferenciación de Crecimiento/metabolismo , Factores de Diferenciación de Crecimiento/farmacología , Glucosa/farmacología , Glucosa/metabolismo , Apoptosis/genética
10.
Dalton Trans ; 53(2): 666-674, 2024 Jan 02.
Artículo en Inglés | MEDLINE | ID: mdl-38073603

RESUMEN

Although antibacterial platforms involving nanozymes have been extensively investigated, there are still problems of poor reactive oxygen species generation efficiency and obstinate bacterial biofilms. Developing a nanozyme-photothermal therapy nanoplatform with superior sterilization effects and minimal side effects would be a good alternative for completely eliminating bacteria and biofilms. Herein, an ultrathin PdMo bimetallene nanozyme with a planar topology and boosted metal utilization, exhibiting excellent photothermal and peroxidase-like activity, is designed for synergistic nanozyme-photothermal sterilization applications and accelerated wound healing. The superior catalytic activity of PdMo bimetallene nanozymes could convert a biosafe concentration of hydrogen peroxide (H2O2) into large quantities of toxic hydroxyl radicals (•OH) under laser irradiation, enhancing bacterial membrane permeability and thermal sensitivity for efficient removal of bacteria and biofilms. In addition, PdMo bimetallene presents a good wound-healing ability according to the results of fibroblast proliferation and collagen deposition with minor side effects. This work would provide an innovative avenue for developing metallene-based nanozymes for biomedical applications.


Asunto(s)
Peróxido de Hidrógeno , Cicatrización de Heridas , Peróxido de Hidrógeno/farmacología , Antibacterianos/farmacología , Biopelículas , Permeabilidad de la Membrana Celular
11.
Can J Cardiol ; 40(4): 710-725, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38081511

RESUMEN

BACKGROUND: Timely and proper suppression of inflammation can effectively reduce myocardial injury and promote the postmyocardial infarction (post-MI) wound-healing process. We have previously found that cardiac conduction regulatory RNA (CCRR), a long noncoding RNA (lncRNA) transcribed by the gene located on chromosome 9, with abundant expression in the heart, elicits antiarrhythmic effects in heart failure, and this is a continuing study on the role of CCRR in MI. METHODS: CCRR was overexpressed in CCRR transgenic mice or after injection of adeno-associated virus-9 (AAV-9). MI surgery was performed, and cardiac function was assessed in vivo by echocardiography, followed by histologic analyses. Western blot analysis and qRT-PCR were performed to investigate the effects of CCRR on macrophages, cardiomyocytes, and cardiomyocytes cocultured with macrophages. Through microarray analysis and RNA-binding protein immunoprecipitation (RIP) and other related techniques were also employed to study the effects of CCRR on Toll-like receptor (TLR)2 and TLR4. RESULTS: We found that CCRR level was significantly decreased with increases in proinflammatory cytokines and activation of the TLR signalling pathway in the heart of the 3-day MI mice. CCRR overexpression downregulated TLR2 and TLR4 in MI and effectively inhibited the inflammatory responses in primary cardiomyocytes and macrophages cultured under hypoxic conditions. Downregulation of CCRR induced excessive inflammatory responses by activating the TLR signalling pathway. CCRR acted by suppressing TLR2 and TLR4 to inhibit the secretion of proinflammatory factors to reduce infarct size, thereby improving cardiac function. CONCLUSIONS: CCRR protected cardiomyocytes against MI injury by suppressing inflammatory response through targeting the TLR signalling pathway.


Asunto(s)
Infarto del Miocardio , ARN Largo no Codificante , Ratones , Animales , ARN Largo no Codificante/genética , ARN Largo no Codificante/metabolismo , Receptor Toll-Like 2/metabolismo , Receptor Toll-Like 4/metabolismo , Transducción de Señal , Miocitos Cardíacos/metabolismo
12.
Org Lett ; 26(1): 29-34, 2024 Jan 12.
Artículo en Inglés | MEDLINE | ID: mdl-38127514

RESUMEN

The Pd(II)/sulfoxide-2-hydroxypyridine catalytic system shows promising activity in C-H activation chemistry. In this study, we showcase how this catalytic system solves the problem of native primary amine-directed γ-C(sp3)-H arylation. Primary amines with different complexities are compatible with the established methodology, and the range of applicable substrates can be expanded to include pyridine, oxime ether, and pyridine N-oxide.

13.
ACS Nano ; 17(22): 22844-22858, 2023 11 28.
Artículo en Inglés | MEDLINE | ID: mdl-37942890

RESUMEN

The immune checkpoint blockade (ICB) antibody immunotherapy has demonstrated clinical benefits for multiple cancers. However, the efficacy of immunotherapy in tumors is suppressed by deficient tumor immunogenicity and immunosuppressive tumor microenvironments. Pyroptosis, a form of programmed cell death, can release tumor antigens, activate effective tumor immunogenicity, and improve the efficiency of ICB, but efficient pyroptosis for tumor treatment is currently limited. Herein, we show a mild hyperthermia-enhanced pyroptosis-mediated immunotherapy based on hollow carbon nanozyme, which can specifically amplify oxidative stress-triggered pyroptosis and synchronously magnify pyroptosis-mediated anticancer responses in the tumor microenvironment. The hollow carbon sphere modified with iron and copper atoms (HCS-FeCu) with multiple enzyme-mimicking activities has been engineered to induce cell pyroptosis via the radical oxygen species (ROS)-Tom20-Bax-Caspase 3-gasdermin E (GSDME) signaling pathway under light activation. Both in vitro and in vivo antineoplastic results confirm the superiority of HCS-FeCu nanozyme-induced pyroptosis. Moreover, the mild photothermal-activated pyroptosis combining anti-PD-1 can enhance antitumor immunotherapy. Theoretical calculations further indicate that the mild photothermal stimulation generates high-energy electrons and enhances the interaction between the HCS-FeCu surface and adsorbed oxygen, facilitating molecular oxygen activation, which improves the ROS production efficiency. This work presents an approach that effectively transforms immunologically "cold" tumors into "hot" ones, with significant implications for clinical immunotherapy.


Asunto(s)
Hipertermia Inducida , Neoplasias , Humanos , Piroptosis , Especies Reactivas de Oxígeno , Inmunoterapia , Carbono , Oxígeno , Microambiente Tumoral , Línea Celular Tumoral
14.
iScience ; 26(11): 108051, 2023 Nov 17.
Artículo en Inglés | MEDLINE | ID: mdl-37942009

RESUMEN

Long non-coding RNAs (lncRNAs) play widespread roles in various processes. However, there is still limited understanding of the precise mechanisms through which they regulate early stage cardiomyocyte differentiation. In this study, we identified a specific lncRNA called LHX1-DT, which is transcribed from a bidirectional promoter of LIM Homeobox 1 (LHX1) gene. Our findings demonstrated that LHX1-DT is nuclear-localized and transiently elevated expression along with LHX1 during early differentiation of cardiomyocytes. The phenotype was rescued by overexpression of LHX1 into the LHX1-DT-/- hESCs, indicating LHX1 is the downstream of LHX1-DT. Mechanistically, we discovered that LHX1-DT physically interacted with RNA/histone-binding protein PHF6 during mesoderm commitment and efficiently replaced conventional histone H2A with a histone variant H2A.Z at the promoter region of LHX1. In summary, our work uncovers a novel lncRNA, LHX1-DT, which plays a vital role in mediating the exchange of histone variants H2A.Z and H2A at the promoter region of LHX1.

15.
Anal Chim Acta ; 1283: 341977, 2023 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-37977794

RESUMEN

Development of highly sensitive and accurate biosensors still faces a great challenge. Herein, glucose oxidase (GOx) is efficiently immobilized on the AuCu hydrogels owing to their porous structure and interfacial interaction, demonstrating enhanced catalytic activity, satisfactory stability and recyclability. Besides, by integration of AuCu@GOx and electrochromic material of Prussian blue, a sensitive and stable biosensing platform based on the excellent electrochromic property of Prussian blue and the enhanced enzyme activity of AuCu@GOx is developed, which enables the electrochemical and visual dual-mode detection of glucose. The as-constructed biosensing platform possesses a wide linear range, and good selectivity for glucose detection with a limit of detection of 0.82 µM in visual mode and 0.84 µM in electrochemical mode. This easy-to-operate biosensing platform opens a door for the practical application of the multi-mode strategy for glucose detection.


Asunto(s)
Técnicas Biosensibles , Glucosa Oxidasa , Glucosa Oxidasa/química , Enzimas Inmovilizadas/química , Glucosa , Ferrocianuros
16.
Int Immunopharmacol ; 124(Pt B): 111060, 2023 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-37862738

RESUMEN

Tuberculosis poses a significant threat to human health due to the lack of an effective vaccine. Although promising progress has been made in the development of tuberculosis vaccines, new vaccines that broaden the antigenic repertoire need to be developed to eradicate this illness. In this study, we used Mycobacterium tuberculosis ferritin BfrB and heat-shock protein GrpE to construct a novel multi-antigenic fusion protein, BfrB-GrpE (BG). BG protein was stably overexpressed in the soluble form in Escherichia coli at a high yield and purified via sequential salt fractionation and hydrophobic chromatography. Purified BG was emulsified in an adjuvant containing N, N'-dimethyl-N, N'-dioctadecylammonium bromide, polyinosinic-polycytidylic acid, and cholesterol (DPC) to construct the BG/DPC vaccine, which stimulated strong cellular and humoral immune responses in mice. Moreover, combination of BG with our previously developed vaccine, Mtb10.4-HspX (MH), containing antigens from both the proliferating and dormant stages, significantly reduced the bacterial counts in the lungs and spleens of M. tuberculosis-infected mice. Importantly, mice that received BG + MH/DPC after M. tuberculosis H37Rv infection survived slightly better (100% survival) than those that received the BCG vaccine (80% survival), although the difference was not statistically significant. Our findings can aid in the selection of antigens and optimization of vaccination regimens to improve the efficacy of tuberculosis vaccines.


Asunto(s)
Mycobacterium tuberculosis , Vacunas contra la Tuberculosis , Tuberculosis , Animales , Ratones , Humanos , Antígenos Bacterianos/genética , Tuberculosis/prevención & control , Vacuna BCG , Vacunas de Subunidad , Proteínas Bacterianas/genética
18.
Pediatr Investig ; 7(3): 153-162, 2023 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-37736364

RESUMEN

Importance: Preserving skin health is crucial for atopic dermatitis control as well as for the thriving of children. However, a well-developed and validated tool that measures the knowledge, attitude, and practice of skin care is lacking. Objective: To develop and validate the atopic dermatitis and infant skincare knowledge, attitude, and practice (ADISKAP 1.0) scale that measures parental health literacy on atopic dermatitis and skin care. Methods: We conducted a review of the literature, a focus group (two dermatologists and 12 parents), and a panel discussion in order to generate the ADISKAP prototype. Two samples of parents with knowingly superior (dermatologists, n = 59) and inferior (general population, n = 395) knowledge traits participated in the validation of ADISKAP. Cronbach's alpha was reported as a measure of internal consistency, and the intraclass correlation coefficient (ICC) was calculated to assess the test-retest validity. The known-groups technique was used to evaluate construct validity. Results: The ADISKAP scale contained 17 items after content and face validity validation. After removing items that displayed poor test-retest reliability (n = 4) and construct validity (n = 3), 12 items were retained in the ADISKAP 1.0. Interpretation: ADISKAP 1.0 is a reliable and valid tool for assessing parental knowledge, attitude, and practice on infantile atopic dermatitis and skin care.

19.
Sensors (Basel) ; 23(18)2023 Sep 07.
Artículo en Inglés | MEDLINE | ID: mdl-37765792

RESUMEN

Video anomaly event detection (VAED) is one of the key technologies in computer vision for smart surveillance systems. With the advent of deep learning, contemporary advances in VAED have achieved substantial success. Recently, weakly supervised VAED (WVAED) has become a popular VAED technical route of research. WVAED methods do not depend on a supplementary self-supervised substitute task, yet they can assess anomaly scores straightway. However, the performance of WVAED methods depends on pretrained feature extractors. In this paper, we first address taking advantage of two pretrained feature extractors for CNN (e.g., C3D and I3D) and ViT (e.g., CLIP), for effectively extracting discerning representations. We then consider long-range and short-range temporal dependencies and put forward video snippets of interest by leveraging our proposed temporal self-attention network (TSAN). We design a multiple instance learning (MIL)-based generalized architecture named CNN-ViT-TSAN, by using CNN- and/or ViT-extracted features and TSAN to specify a series of models for the WVAED problem. Experimental results on publicly available popular crowd datasets demonstrated the effectiveness of our CNN-ViT-TSAN.

20.
Rev Sci Instrum ; 94(8)2023 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-37540121

RESUMEN

A time-resolved electron paramagnetic resonance (TREPR) method with 40 ns time resolution and a high sensitivity suitable for the detection of short-lived radicals under thermal equilibrium is developed. The key is the introduction of a new detection technique named ultrawide single sideband phase sensitive detection (U-PSD) to the conventional continuous-wave EPR, which remarkably enhanced the sensitivity for the detection of broadband transient signals compared with the direct detection protocol. By repeatedly triggering a transient kinetic event f(t) (e.g., by laser flash photolysis) under a 100 kHz magnetic field modulation with precise phase control, this technique can build an ultrawide single sideband modulated signal. After single sideband demodulation, the flicker noise-suppressed signal f(t) with wide bandwidth is recovered. A U-PSD TREPR spectrometer prototype has been built, which integrated timing sequence control, laser flash excitation, data acquisition systems, and the U-PSD algorithm with a conventional continuous-wave EPR. It exhibited excellent performance in monitoring a model transient radical system, laser flash photolysis of benzophenone in isopropanol. Both the intense chemically induced dynamic electron polarization signals and the much weaker thermal equilibrium EPR signals of the generated acetone ketyl radical and benzophenone ketyl radical were clearly observed within a wide timescale ranging from sub-microsecond to milliseconds. This prototype validated the feasibility of the U-PSD technique and demonstrated its superior performance in studying complex photochemical systems containing various transient radicals, which complements the established TREPR techniques and provides a powerful tool for deep mechanistic understandings, such as in photoredox catalysis and artificial photosynthesis.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...