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2.
Physiol Mol Biol Plants ; 30(6): 877-891, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38974354

RESUMEN

Natural leaf senescence is critical for plant fitness. Drought-induced premature leaf senescence affects grape yield and quality. However, reports on the regulatory mechanisms underlying premature leaf senescence under drought stress are limited. In this study, two-year-old potted 'Muscat Hamburg' grape plants were subjected to continuous natural drought treatment until mature leaves exhibited senescence symptoms. Physiological and biochemical indices related to drought stress and senescence were monitored. Transcriptome and transgenic Arabidopsis were used to perform expression analyses and functional identification of drought-induced senescence-associated genes. Twelve days of continuous drought stress was sufficient to cause various physiological disruptions and visible senescence symptoms in mature 'Muscat Hamburg' leaves. These disruptions included malondialdehyde and H2O2 accumulation, and decreased catalase activity and chlorophyll (Chl) levels. Transcriptome analysis revealed that most genes involved in photosynthesis and Chl synthesis were downregulated after 12 d of drought treatment. Three key Chl catabolic genes (SGR, NYC1, and PAO) were significantly upregulated. Overexpression of VvSGR in wild Arabidopsis further confirmed that SGR directly promoted early yellowing of cotyledons and leaves. In addition, drought treatment decreased expression of gibberellic acid signaling repressors (GAI and GAI1) and cytokinin signal components (AHK4, AHK2, RR22, RR9-1, RR9-2, RR6, and RR4) but significantly increased the expression of abscisic acid, jasmonic acid, and salicylic acid signaling components and responsive transcription factors (bZIP40/ABF2, WRKY54/75/70, ANAC019, and MYC2). Moreover, some NAC members (NAC0002, NAC019, and NAC048) may also be drought-induced senescence-associated genes. These results provide extensive information on candidate genes involved in drought-induced senescence in grape leaves. Supplementary Information: The online version contains supplementary material available at 10.1007/s12298-024-01465-2.

3.
Microbiol Res ; 286: 127815, 2024 Jun 26.
Artículo en Inglés | MEDLINE | ID: mdl-38944943

RESUMEN

Saccharomyces cerevisiae is commonly used as a microbial cell factory to produce high-value compounds or bulk chemicals due to its genetic operability and suitable intracellular physiological environment. The current biosynthesis pathway for targeted products is primarily rewired in the cytosolic compartment. However, the related precursors, enzymes, and cofactors are frequently distributed in various subcellular compartments, which may limit targeted compounds biosynthesis. To overcome above mentioned limitations, the biosynthesis pathways are localized in different subcellular organelles for product biosynthesis. Subcellular compartmentalization in the production of targeted compounds offers several advantages, mainly relieving competition for precursors from side pathways, improving biosynthesis efficiency in confined spaces, and alleviating the cytotoxicity of certain hydrophobic products. In recent years, subcellular compartmentalization in targeted compound biosynthesis has received extensive attention and has met satisfactory expectations. In this review, we summarize the recent advances in the compartmentalized biosynthesis of the valuable compounds in S. cerevisiae, including terpenoids, sterols, alkaloids, organic acids, and fatty alcohols, etc. Additionally, we describe the characteristics and suitability of different organelles for specific compounds, based on the optimization of pathway reconstruction, cofactor supplementation, and the synthesis of key precursors (metabolites). Finally, we discuss the current challenges and strategies in the field of compartmentalized biosynthesis through subcellular engineering, which will facilitate the production of the complex valuable compounds and offer potential solutions to improve product specificity and productivity in industrial processes.

4.
Insects ; 15(6)2024 May 29.
Artículo en Inglés | MEDLINE | ID: mdl-38921111

RESUMEN

A phylogeny of Cyrtophyllitinae Zeuner, 1935 sensu Gorochov, Jarzembowski & Coram, 2006, based on wing morphology, is presented including all genera. Cyrtophillitinae is found to be paraphyletic. Except for Cyrtophyllites rogeri Oppenheim, 1888, all other species were moved from the subfamily Cyrtophyllitinae (Hagloidea, Haglidae). Consequently, a new subfamily Archaboilinae subfam. nov. was erected and accommodates most of the previous cyrtophillitine taxa, except Cyrtophyllites rogeri. The type genus Archaboilus Martynov, 1937 of the new subfamily was designated; a new genus, Pararchaboilus gen. nov., was erected with the designation of type species Pararchaboilus cretaceus comb. nov. From the Middle Jurassic deposits of China, two new species, Archaboilus ornatus sp. nov. and Vitimoilus gigantus sp. nov., are described.

5.
J Agric Food Chem ; 72(26): 15027-15039, 2024 Jul 03.
Artículo en Inglés | MEDLINE | ID: mdl-38886897

RESUMEN

Abscisic acid (ABA) is a major regulator of nonclimacteric fruit ripening, with its processes involving epigenetic mechanisms. It remains unclear whether DNA methylation is associated with ABA-regulated ripening. In this study, we investigated the patterns of DNA methylation and gene expression following ABA treatment in grape berries by using whole-genome bisulfite sequencing and RNA-sequencing. ABA application changed global DNA methylation in grapes. The hyper-/hypo-differently methylated regions were enriched in defense-related metabolism, degreening processes, or ripening-related metabolic pathways. Many differentially expressed genes showed an alteration in DNA methylation after ABA treatment. Specifically, ten downregulated genes with hypermethylation in promoters were involved in the ripening process, ABA homeostasis/signaling, and stress response. Nine upregulated genes exhibiting hypo-methylation in promoters were related to the ripening process and stress response. These findings demonstrated ABA-induced DNA alteration of ripening related and stress-responsive genes during grape ripening, which provides new insights of the epigenetic regulation of ABA on fruit ripening.


Asunto(s)
Ácido Abscísico , Metilación de ADN , Epigénesis Genética , Frutas , Regulación de la Expresión Génica de las Plantas , Proteínas de Plantas , Vitis , Vitis/genética , Vitis/crecimiento & desarrollo , Vitis/metabolismo , Vitis/efectos de los fármacos , Ácido Abscísico/metabolismo , Ácido Abscísico/farmacología , Metilación de ADN/efectos de los fármacos , Frutas/genética , Frutas/crecimiento & desarrollo , Frutas/metabolismo , Frutas/efectos de los fármacos , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Epigénesis Genética/efectos de los fármacos , Estrés Fisiológico/genética , Reguladores del Crecimiento de las Plantas/farmacología , Reguladores del Crecimiento de las Plantas/metabolismo , Regiones Promotoras Genéticas
6.
Environ Res ; 257: 119286, 2024 May 31.
Artículo en Inglés | MEDLINE | ID: mdl-38824987

RESUMEN

BACKGROUND: Recent evidences highlight the potential impact of outdoor Light at Night (LAN) on executive function. However, few studies have investigated the association between outdoor LAN exposure and executive function. METHODS: We employed data from 48,502 Chinese children aged 5-12 years in a cross-sectional study conducted in Guangdong province during 2020-2021, to examine the association between outdoor LAN and executive function assessed using the validated parent-completed Behavior Rating Inventory of Executive Function. We assessed children's outdoor LAN exposure using the night-time satellite images based on the residential addresses. We used generalized linear mixed models to estimate the association between outdoor LAN exposure and executive function scores and executive dysfunction. RESULTS: After adjusting for potential covariates, higher quintiles of outdoor LAN exposure were associated with poorer executive function. Compared to the lowest quintile (Q1), all higher quintiles of exposure showed a significant increased global executive composite (GEC) score with ß (95% confidence intervals, CI) of 0.58 (0.28, 0.88) in Q2, 0.59 (0.28, 0.9) in Q3, 0.85 (0.54, 1.16) in Q4, and 0.76 (0.43, 1.09) in Q5. Higher quintiles of exposure were also associated with higher risks for GEC dysfunction with odd ratios (ORs) (95% CI) of 1.34 (1.18, 1.52) in Q2, 1.40 (1.24, 1.59) in Q3, 1.40 (1.23, 1.59) in Q4, and 1.39 (1.22, 1.58) in Q5. And stronger associations were observed in children aged 10-12 years. CONCLUSIONS: Our study suggested that high outdoor LAN exposure was associated with poor executive function in children. These findings suggested that future studies should determine whether interventions to reduce outdoor LAN exposure can have a positive effect on executive function.

7.
Zhongguo Shi Yan Xue Ye Xue Za Zhi ; 32(3): 945-951, 2024 Jun.
Artículo en Chino | MEDLINE | ID: mdl-38926993

RESUMEN

OBJECTIVE: To explore the application value of simultaneous monitoring of voriconazole (VRCZ) and voriconazole N-oxide (VNO) in efficacy and safety of VRCZ in the prevention and treatment of fungal infections in allogeneic hematopoietic stem cell transplantation (allo-HSCT) patients before engraftment (i.e., days +1 to +30 after transplantation). METHODS: The influencing factors of VRCZ, VNO concentration and MR (CVNO/CVRCZ) and the difference of VRCZ in the prevention and treatment of fungal infection and liver and kidney injury were analyzed. The receiver operating characteristic curve (ROC) was used to analyze the differences (the corresponding to the maximum of the Youden index on the curve was set as the cut-off value) to confirm the critical value. RESULTS: The factors affecting VRCZ concentration (CVRCZ), VNO concentration (CVNO) and MR were patient weight, VRCZ daily dose, and transplantation type (all P < 0.05). CVRCZ and CVNO in the effective group were higher than those in the ineffective group (P < 0.001), the opposite of MR (P < 0.001); the liver and renal injury group had lower MR than the normal group (P < 0.05). ROC showed that CVRCZ, C VNO and MR had important value in predicting VRCZ in the prevention and treatment of invasive fungal infections in allo-HSCT patients before engraftment, and their cutoff of concentrations were 0.95 µg/ml, 1.35 µg/ml and 1.645, respectively (AUC: 0.9677, 0.7634, 0.9564). CVRCZ and MR can assist in indicating liver ï¼»cutoff values: 0.65 µg/ml, 1.96 (AUC: 0.5971, 0.6663)ï¼½ and renal injury ï¼»cutoff values: 0.95 µg/ml, 1.705 (AUC: 0.6039, 0.6164)ï¼½. CONCLUSION: The great value of simultaneous monitoring of VRCZ, VNO and MR can predict in the efficacy and safety of VRCZ in allo-HSCT patients before engraftment. The prediction accuracy of CVRCZ was higher than that of MR, followed by that of CVNO. Increased CVRCZ and decreased MR increase the risk of liver and kidney injury.


Asunto(s)
Antifúngicos , Trasplante de Células Madre Hematopoyéticas , Trasplante Homólogo , Voriconazol , Humanos , Trasplante de Células Madre Hematopoyéticas/efectos adversos , Micosis , Monitoreo de Drogas/métodos
8.
Heliyon ; 10(10): e31197, 2024 May 30.
Artículo en Inglés | MEDLINE | ID: mdl-38807876

RESUMEN

Electroacupuncture (EA) is an effective alternative for the treatment of functional dyspepsia (FD). It reduces low-grade duodenal inflammation and improves the symptoms of FD by downregulating the expression of NF-κB p65 and NLRP3, but its mechanism needs to be elucidated. To examine the regulatory effect of electroacupuncture (EA) on intestinal flora and NF-κB p65/NLRP3 pyroptosis pathway in FD rats. The FD rat model was established via multi-factor stress intervention for two weeks. The rats were randomly divided into the NC group, model group, NF-kB inhibitor group (NF-κB inhibitor BAY 11-7082 was administered), EA group, and EA + NF-kB inhibitor group. After 14 days of treatment, the rats were sacrificed, and the protein and mRNA levels of NF-κB p65, IκB, and NLRP3 in the duodenum were evaluated by Western blotting assays and real-time fluorescent quantitative PCR. The Illumina MiSeq sequencing platform was used to analyze the V4 region of the 16S rRNA gene of intestinal flora and predict functional genes. The concentration of short-chain fatty acids (SCFAs) in feces was assessed by metabolomics. EA can decrease low-grade duodenal inflammation and promote gastrointestinal motility in FD rats. This effect is mediated by inhibition of the NF-κB p65/NLRP3 pyroptosis pathway, an increase in the alpha and beta diversity of gut microbiota in the duodenum, an increase in the abundance of beneficial bacteria at the phylum and genus levels, and an increase in the content of SCFAs. The protective effect of EA against FD might involve multiple hierarchy and pathways. EA may remodel intestinal flora by inhibiting the NF-κB p65/NLRP3 pyroptosis pathway, thereby improving low-grade duodenal inflammation in FD rats.

9.
J Mol Graph Model ; 130: 108778, 2024 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-38652998

RESUMEN

SIRT6 is of interest for its promising effect in the treatment of aging-related diseases. Studies have shown quercetin (QUE) and its derivatives have varying degrees of effect on the catalytic effect of SIRT6. In the research, the effect of QUE on the protein-substrate interaction in the SIRT6-mediated mono-ADP ribosylation system was investigated by conventional molecular dynamics (MD) simulations combined with MM/PBSA binding free energy calculations. The results show that QUE can bind stably to SIRT6 with the binding energy of -22.8 kcal/mol and further affect the atomic interaction between SIRT6 and NAD+ (or H3K9), resulting in an increased affinity between SIRT6-NAD+ and decreased SIRT6-H3K9 binding capacity. At the same time, the binding of QUE can also alter some structural characteristics of the protein, with large shifts occurring in the residue regions involving the N-terminal (residues 1-27), Rossmann fold regions (residues 55-92), and ZBD (residues 164-179). Thus, QUE shows great potential as a scaffold for the design of novel potent SIRT6 modulators.


Asunto(s)
Simulación de Dinámica Molecular , Unión Proteica , Quercetina , Sirtuinas , Quercetina/química , Quercetina/farmacología , Sirtuinas/química , Sirtuinas/metabolismo , Humanos , Sitios de Unión , NAD/química , NAD/metabolismo , Termodinámica , Simulación del Acoplamiento Molecular , Especificidad por Sustrato , Enlace de Hidrógeno , Conformación Proteica
10.
Lancet Infect Dis ; 2024 Apr 10.
Artículo en Inglés | MEDLINE | ID: mdl-38614117

RESUMEN

BACKGROUND: The Oka varicella vaccine strain remains neurovirulent and can establish lifelong latent infection, raising safety concerns about vaccine-related herpes zoster. In this study, we aimed to evaluate the immunogenicity and safety of a skin-attenuated and neuro-attenuated varicella vaccine candidate (v7D vaccine). METHODS: We did this randomised, double-blind, controlled, phase 2a clinical trial in Jiangsu, China. Healthy children aged 3-12 years with no history of varicella infection or vaccination were enrolled and randomly assigned (1:1:1:1) to receive a single subcutaneous injection of the v7D vaccine at 3·3 log10 plaque forming units (PFU; low-dose v7D group), 3·9 log10 PFU (medium-dose v7D group), and 4·2 log10 PFU (high-dose v7D group), or the positive control varicella vaccine (vOka vaccine group). All the participants, laboratory personnel, and investigators other than the vaccine preparation and management staff were masked to the vaccine allocation. The primary outcome was assessment of the geometric mean titres (GMTs) and seroconversion rates of anti-varicella zoster virus immunoglobulin G (IgG) induced by different dose groups of v7D vaccine at 0, 42, 60, and 90 days after vaccination in the per-protocol set for humoral immune response analysis. Safety was a secondary outcome, focusing on adverse events within 42 days post-vaccination, and serious adverse events within 6 months after vaccination. This study was registered on Chinese Clinical Trial Registry, ChiCTR2000034434. FINDINGS: On Aug 18-21, 2020, 842 eligible volunteers were enrolled and randomly assigned treatment. After three participants withdrew, 839 received a low dose (n=211), middle dose (n=210), or high dose (n=210) of v7D vaccine, or the vOka vaccine (n=208). In the per-protocol set for humoral immune response analysis, the anti-varicella zoster virus IgG antibody response was highest at day 90. At day 90, the seroconversion rates of the low-dose, medium-dose, and high-dose groups of v7D vaccine and the positive control vOka vaccine group were 100·0% (95% CI 95·8-100·0; 87 of 87 participants), 98·9% (93·8-100·0; 87 of 88 participants), 97·8% (92·4-99·7; 91 of 93 participants), and 96·4% (89·8-99·2; 80 of 83 participants), respectively; the GMTs corresponded to values of 30·8 (95% CI 26·2-36·0), 31·3 (26·7-36·6), 28·2 (23·9-33·2), and 38·5 (31·7-46·7). The v7D vaccine, at low dose and medium dose, elicited a humoral immune response similar to that of the vOka vaccine. However, the high-dose v7D vaccine induced a marginally lower GMT compared with the vOka vaccine at day 90 (p=0·027). In the per-protocol set, the three dose groups of the v7D vaccine induced a similar humoral immune response at each timepoint, with no statistically significant differences. The incidence of adverse reactions in the low-dose, medium-dose, and high-dose groups of v7D vaccine was significantly lower than that in the vOka vaccine group (17% [35 of 211 participants], 20% [41 of 210 participants], and 13% [27 of 210 participants] vs 24% [50 of 208 participants], respectively; p=0·025), especially local adverse reactions (10% [22 of 211 participants], 14% [30 of 210 participants] and 9% [18 of 210 participants] vs 18% [38 of 208 participants], respectively; p=0·016). None of the serious adverse events were vaccine related. INTERPRETATION: The three dose groups of the candidate v7D vaccine exhibit similar humoral immunogenicity to the vOka vaccine and are well tolerated. These findings encourage further investigations on two-dose vaccination schedules, efficacy, and the potential safety benefit of v7D vaccine in the future. FUNDING: The National Natural Science Foundation of China, CAMS Innovation Fund for Medical Sciences, the Fundamental Research Funds for the Central Universities, and Beijing Wantai. TRANSLATION: For the Chinese translation of the abstract see Supplementary Materials section.

11.
Phytochemistry ; 222: 114108, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38663825

RESUMEN

Twelve undescribed 2-(2-phenethyl)chromone dimers (1-12) were isolated from EtOAc extract of agarwood originating from Aquilaria filaria in the Philippines, guided by a UHPLC-MS analysis. Their structures were elucidated by 1D NMR, 2D NMR, and HR-ESI-MS spectra. The absolute configuration of 2-(2-phenylethyl)chromone dimers was determined by single-crystal X-ray diffraction analysis and comparison of the experimental and calculated ECD spectra. Compounds 1, 2, 5 and 9-12 exhibited potent to moderate anti-inflammatory activity with IC50 values in the range of 22.43 ± 0.86 to 53.88 ± 4.06 µM.


Asunto(s)
Cromonas , Thymelaeaceae , Madera , Thymelaeaceae/química , Filipinas , Cromonas/química , Cromonas/aislamiento & purificación , Cromonas/farmacología , Estructura Molecular , Madera/química , Animales , Relación Estructura-Actividad , Ratones , Relación Dosis-Respuesta a Droga , Cristalografía por Rayos X , Flavonoides
12.
Int J Hematol ; 119(5): 564-572, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38441775

RESUMEN

OBJECTIVE: To describe the features of ETV6::ABL1 AML as well as the clinical treatment and outcomes. METHODS: Clinical data were collected from three patients diagnosed with ETV6::ABL1 AML at Hebei Yanda Lu Daopei Hospital and Beijing Lu Daopei Hospital. Their clinical and laboratory features were analyzed, and the treatment process and outcomes were described. Ten reported cases of ETV6::ABL1 AML from the literature were also included for analysis. RESULTS: The median age of the patients was 34 years, and 2 patients were male. No patient had a history of blood disorders before diagnosis. After relapse, they were referred to our hospital, where the ETV6::ABL1 gene was detected. Unfortunately, Patient 1 died rapidly after leukemia relapse due to severe infection. Patients 2 and 3 received salvage therapy with a dasatinib-containing regimen, followed by allo-HSCT, and are currently alive and disease-free. CONCLUSION: ETV6::ABL1 is a rare but recurrent genetic aberration in AML, and the combined use of fluorescence in situ hybridization and PCR can better identify this fusion gene. Patients carrying ETV6::ABL1 have a high relapse rate and a poor prognosis. TKIs are a reasonable treatment option for this group, and allo-HSCT may be curative.


Asunto(s)
Proteína ETS de Variante de Translocación 6 , Leucemia Mieloide Aguda , Proteínas de Fusión Oncogénica , Proteínas Proto-Oncogénicas c-ets , Proteínas Represoras , Adulto , Femenino , Humanos , Masculino , Persona de Mediana Edad , Trasplante de Células Madre Hematopoyéticas , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/diagnóstico , Leucemia Mieloide Aguda/terapia , Proteínas de Fusión Oncogénica/genética , Proteínas Proto-Oncogénicas c-abl/genética , Proteínas Proto-Oncogénicas c-ets/genética , Proteínas Represoras/genética , Resultado del Tratamiento
14.
World J Gastrointest Surg ; 16(2): 409-418, 2024 Feb 27.
Artículo en Inglés | MEDLINE | ID: mdl-38463374

RESUMEN

BACKGROUND: Advancements in laparoscopic technology and a deeper understanding of intrahepatic anatomy have led to the establishment of more precise laparoscopic hepatectomy (LH) techniques. The indocyanine green (ICG) fluorescence navigation technique has emerged as the most effective method for identifying hepatic regions, potentially overcoming the limitations of LH. While laparoscopic left hemihepatectomy (LLH) is a standardized procedure, there is a need for innovative strategies to enhance its outcomes. AIM: To investigate a standardized cranial-dorsal strategy for LLH, focusing on important anatomical markers, surgical skills, and ICG staining methods. METHODS: Thirty-seven patients who underwent ICG fluorescence-guided LLH at Qujing Second People's Hospital between January 2019 and February 2022 were retrospectively analyzed. The cranial-dorsal approach was performed which involves dissecting the left hepatic vein cephalad, isolating the Arantius ligament , exposing the middle hepatic vein, and dissecting the parenchyma from the dorsal to the foot in order to complete the anatomical LLH. The surgical methods, as well as intra- and post-surgical data, were recorded and analyzed. Our hospital's Medical Ethics Committee approved this study (Ethical review: 2022-019-01). RESULTS: Intraoperative blood loss during LLH was 335.68 ± 99.869 mL and the rates of transfusion and conversion to laparotomy were 13.5% and 0%, respectively. The overall incidence of complications throughout the follow-up (median of 18 months; range 1-36 months) was 21.6%. No mortality or severe complications (level IV) were reported. CONCLUSION: LLH has the potential to become a novel, standardized approach that can effectively, safely, and simply expose the middle hepatic vein and meet the requirements of precision surgery.

15.
Aquat Toxicol ; 268: 106854, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-38309221

RESUMEN

The interactions between estrogen and androgen in aquatic animals remain largely unknown. In this study, two generations (F0 and F1) of western mosquitofish (Gambusia affinis) were continuously exposed to 17α-ethinylestradiol (EE2, 10 ng/L), methyltestosterone (MT, 10 ng/L (MTL); 50 ng/L (MTH)), and mixtures (EE2+MTL and EE2+MTH). Various endpoints, including sex ratio (phenotypic and genetic), secondary sex characteristics, gonadal histology, and transcriptional profile of genes, were examined. The results showed that G. affinis exposed to MTH and EE2+MTH had a > 89.7 % of phenotypic males in F1 generation, with 34.5 and 50.0 % of these males originated from genetic females, respectively. Moreover, females from F0 and F1 generations exposed to MTH and EE2+MTH exhibited masculinized anal fins and skeletons. The combined effect of MT and EE2 on most endpoints was dependent on MT. Furthermore, significant transcriptional alterations in certain target genes were observed in both the F0 and F1 generations by EE2 and MT alone and by mixtures, showing some degree of interactions. These findings that the effects of EE2+MTH were primarily on the phenotypic sex of G. affinis in offspring generation suggest that G. affinis under chronic exposure to the binary mixture contaminated water could have sex-biased populations.


Asunto(s)
Ciprinodontiformes , Contaminantes Químicos del Agua , Masculino , Femenino , Animales , Etinilestradiol/toxicidad , Metiltestosterona/toxicidad , Contaminantes Químicos del Agua/toxicidad , Estrógenos , Ciprinodontiformes/genética
16.
Opt Lett ; 49(2): 242-245, 2024 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-38194538

RESUMEN

The theory of band topology has inspired the discovery of various topologically protected states in the regime of photonics. It has led to the development of topological photonic devices with robust property and versatile functionalities, like unidirectional waveguides, compact power splitters, high-Q resonators, and robust lasers. These devices mainly rely on the on-chip photonic crystal (PhC) in Si or III-V compound materials with a fairly large bandgap. However, the topological designs have rarely been applied to the ultra-low-loss silicon nitride (SiN) platform which is widely used in silicon photonics for important devices and integrated photonic circuits. It is mainly hindered by the relatively low refractive index. In this work, we revealed that a rhombic PhC can open a large bandgap in the SiN slab, and thus support robust topological corner states stemming from the quantization of the dipole moments. Meanwhile, we propose the inclination angle of rhombic lattice, as a new degree of freedom, to manipulate the characteristics of topological states. Our work shows a possibility to further expand the topological protection and design flexibility to SiN photonic devices.

20.
ACS Omega ; 8(47): 45109-45114, 2023 Nov 28.
Artículo en Inglés | MEDLINE | ID: mdl-38046303

RESUMEN

The mechanism underlying the rhodium(III)-catalyzed reaction of the C-H alkenylation/annulation reaction of salicylaldehydes with enynes has been thoroughly investigated using DFT calculations. Based on mechanistic studies, our focus primarily lies on the regioselectivity of asymmetric alkynes inserting into the Rh-C bond and the involvement of the auxiliary group OAc- in these reactions. Our theoretical study uncovers that, with acetate assistance, a stepwise SN2' cyclization, 1,3-Rh migration, ß-H elimination, and reductive elimination process occur. Furthermore, we also explore the role of substitution at Cα (CH3 vs H) in the reaction. As demonstrated in this work, these findings are applicable to other related reactions.

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