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1.
Int J Mol Sci ; 25(15)2024 Aug 02.
Artículo en Inglés | MEDLINE | ID: mdl-39126039

RESUMEN

Multidrug resistance (MDR) remains the most difficult problem facing conventional chemotherapy for cancers. Astragalus membranaceus is a historically traditional Chinese medicine. One of its bioactive components, formononetin, exhibits antitumor effects on various cancers. However, the effects of formononetin on MDR cancers have not been evaluated. Therefore, we investigated the defense's effects of formononetin on MDR. We used rhodamine 123 and doxorubicin efflux assays to analyze the inhibition kinetics of P-glycoprotein (P-gp) mediated-efflux. Cell viability was detected by sulforhodamine B assay, and the synergistic effects of formononetin combined with chemotherapeutic agents were further calculated using CompuSyn software. Molecular docking was performed with iGEMDOCK. We discovered that formononetin considerably induced oxidative stress and the disruption of mitochondrial membrane potential in MDR cancer cells. Furthermore, formononetin inhibits the P-gp efflux function by ATPase stimulation and the uncompetitive inhibition of P-gp-mediated effluxes of rhodamine 123 and doxorubicin. The molecular docking model indicates that formononetin may bind to P-gp by strong hydrogen bonds at Arginine (Arg) 489 and Glutamine (Gln) 912. Formononetin exhibits significant synergistic effects with vincristine and doxorubicin toward MDR cancer cells, and it synergistically suppressed tumor growth in vivo with paclitaxel. These results suggest that formononetin should be seen as a potential candidate for the adjuvant therapy of MDR cancers.


Asunto(s)
Doxorrubicina , Resistencia a Múltiples Medicamentos , Resistencia a Antineoplásicos , Isoflavonas , Simulación del Acoplamiento Molecular , Estrés Oxidativo , Isoflavonas/farmacología , Isoflavonas/química , Humanos , Resistencia a Antineoplásicos/efectos de los fármacos , Animales , Estrés Oxidativo/efectos de los fármacos , Resistencia a Múltiples Medicamentos/efectos de los fármacos , Ratones , Doxorrubicina/farmacología , Línea Celular Tumoral , Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/metabolismo , Potencial de la Membrana Mitocondrial/efectos de los fármacos , Ensayos Antitumor por Modelo de Xenoinjerto , Supervivencia Celular/efectos de los fármacos , Neoplasias/tratamiento farmacológico , Neoplasias/metabolismo , Neoplasias/patología , Sinergismo Farmacológico
2.
Insights Imaging ; 15(1): 210, 2024 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-39145877

RESUMEN

OBJECTIVES: To evaluate the diagnostic accuracy of liver dual-layer spectral-detector CT (SDCT) derived parameters of liver parenchyma for grading steatosis with reference to magnetic resonance imaging-based proton density fat fraction (MRI-PDFF). METHODS: Altogether, 320 consecutive subjects who underwent MRI-PDFF and liver SDCT examinations were recruited and prospectively enrolled from four Chinese hospital centers. Participants were classified into normal (n = 152), mild steatosis (n = 110), and moderate/severe(mod/sev) steatosis (n = 58) groups based on MRI-PDFF. SDCT liver parameters were evaluated using conventional polychromatic CT images (CTpoly), virtual mono-energetic images at 40 keV (CT40kev), the slope of the spectral attenuation curve (λ), the effective atomic number (Zeff), and liver to spleen attenuation ratio (L/S ratio). Linearity between SDCT liver parameters and MRI-PDFF was examined using Spearman correlation. Cutoff values for SDCT liver parameters in determining steatosis grades were identified using the area under the receiver-operating characteristic curve analyses. RESULTS: SDCT liver parameters demonstrated a strong correlation with PDFF, particularly Zeff (rs = -0.856; p < 0.001). Zeff achieved an area under the curve (AUC) of 0.930 for detecting the presence of steatosis with a sensitivity of 89.4%, a specificity of 82.4%, and an AUC of 0.983 for detecting mod/sev steatosis with a sensitivity of 93.1%, a specificity of 93.5%, the corresponding cutoff values were 7.12 and 6.94, respectively. Zeff also exhibited good diagnostic performance for liver steatosis grading in subgroups, independent of body mass index. CONCLUSION: SDCT liver parameters, particularly Zeff, exhibit excellent diagnostic accuracy for grading steatosis. CRITICAL RELEVANCE STATEMENT: Dual-layer SDCT parameter, Zeff, as a more convenient and accurate imaging biomarker may serve as an alternative indicator for MRI-based proton density fat fraction, exploring the stage and prognosis of liver steatosis, and even metabolic risk assessment. KEY POINTS: Liver biopsy is the standard for grading liver steatosis, but is limited by its invasive nature. The diagnostic performance of liver steatosis using SDCT-Zeff outperforms conventional CT parameters. SDCT-Zeff accurately and noninvasively assessed the grade of liver steatosis.

3.
Molecules ; 29(15)2024 Jul 29.
Artículo en Inglés | MEDLINE | ID: mdl-39124974

RESUMEN

In our ongoing work to create potential antifungal agents, we synthesized and tested a group of C1-substituted acylhydrazone ß-carboline analogues 9a-o and 10a-o for their effectiveness against Valsa mali, Fusarium solani, Fusarium oxysporum, and Fusarium graminearum. Their compositions were analyzed using different spectral techniques, such as 1H/13C NMR and HRMS, with the structure of 9l being additionally confirmed through X-ray diffraction. The antifungal evaluation showed that, among all the target ß-carboline analogues, compounds 9n and 9o exhibited more promising and broad-spectrum antifungal activity than the commercial pesticide hymexazol. Several intriguing findings regarding structure-activity relationships (SARs) were examined. In addition, the cytotoxicity test showed that these acylhydrazone ß-carboline analogues with C1 substitutions exhibit a preference for fungi, with minimal harm to healthy cells (LO2). The reported findings provide insights into the development of ß-carboline analogues as new potential antifungal agents.


Asunto(s)
Antifúngicos , Carbolinas , Fusarium , Hidrazonas , Pruebas de Sensibilidad Microbiana , Carbolinas/química , Carbolinas/farmacología , Carbolinas/síntesis química , Antifúngicos/farmacología , Antifúngicos/síntesis química , Antifúngicos/química , Relación Estructura-Actividad , Fusarium/efectos de los fármacos , Hidrazonas/farmacología , Hidrazonas/química , Hidrazonas/síntesis química , Estructura Molecular , Humanos
4.
J Clin Psychiatry ; 85(3)2024 Aug 14.
Artículo en Inglés | MEDLINE | ID: mdl-39145682

RESUMEN

Abstract.Background: There is growing evidence that understanding the role of sleep disturbance in bipolar disorder (BD) and major depressive disorder (MDD) is helpful when studying the high heterogeneity of patients across psychiatric disorders.Objective: The present study was designed to investigate the transdiagnostic role of sleep disturbance measured by polysomnography (PSG) in differentiating from MDD with BD.Methods: A total of 256 patients with MDD and 107 first-episode and never medicated patients with BD using the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, criteria were recruited. All patients completed 1 night of PSG recording, and the changes in objective sleep structure parameters were determined by PSG analysis.Results: We showed that patients with MDD had statistically longer rapid eye movement (REM) latency, a higher percentage of stage N2 sleep, and lower percentages of stage N3 sleep and REM sleep than those with BD after controlling for confounding factors (all P < .05). Moreover, using the logistic regression analysis, we identified that REM latency was associated with BD diagnosis among the PSG sleep features. The cutoff value for PSG characteristics to differentiate BD from MDD was 261 in REM latency (sensitivity: 41.4% and specificity: 84.1%).Conclusions: Our findings suggest that PSG-measured sleep abnormalities, such as reduced REM latency, may be a diagnostic differentiating factor between MDD and BD, indicating their roles in identifying homogeneous transdiagnostic subtypes across psychiatric disorders.


Asunto(s)
Trastorno Bipolar , Trastorno Depresivo Mayor , Polisomnografía , Humanos , Trastorno Depresivo Mayor/diagnóstico , Trastorno Depresivo Mayor/fisiopatología , Trastorno Bipolar/diagnóstico , Trastorno Bipolar/fisiopatología , Femenino , Masculino , Adulto , Diagnóstico Diferencial , Persona de Mediana Edad , Trastornos del Sueño-Vigilia/diagnóstico , Trastornos del Sueño-Vigilia/fisiopatología , Sueño REM/fisiología , Adulto Joven , Fases del Sueño/fisiología
5.
Chem Rev ; 2024 Aug 08.
Artículo en Inglés | MEDLINE | ID: mdl-39115179

RESUMEN

Radical C-H functionalization represents a useful means of streamlining synthetic routes by avoiding substrate preactivation and allowing access to target molecules in fewer steps. The first-row transition metals (Ti, V, Cr, Mn, Fe, Co, Ni, and Cu) are Earth-abundant and can be employed to regulate radical C-H functionalization. The use of such metals is desirable because of the diverse interaction modes between first-row transition metal complexes and radical species including radical addition to the metal center, radical addition to the ligand of metal complexes, radical substitution of the metal complexes, single-electron transfer between radicals and metal complexes, hydrogen atom transfer between radicals and metal complexes, and noncovalent interaction between the radicals and metal complexes. Such interactions could improve the reactivity, diversity, and selectivity of radical transformations to allow for more challenging radical C-H functionalization reactions. This review examines the achievements in this promising area over the past decade, with a focus on the state-of-the-art while also discussing existing limitations and the enormous potential of high-value radical C-H functionalization regulated by these metals. The aim is to provide the reader with a detailed account of the strategies and mechanisms associated with such functionalization.

6.
Int Immunopharmacol ; 140: 112827, 2024 Aug 07.
Artículo en Inglés | MEDLINE | ID: mdl-39116497

RESUMEN

AIM: Hyperhomocysteine has been recognized as an independent risk factor of multiple diseases, including several eye diseases. In this study, we aim to investigate whether increased homocysteine (Hcy) is related to cataracts, and to explore whether dysregulation of mTOR-mediated autophagy and connexin expression are underlying mechanisms. METHOD: We first developed a method of liquid chromatography tandem mass spectrometry to accurately measure serum concentrations of Hcy in 287 cataract patients and 334 healthy controls. Next, we treated human lens epithelial (HLC-B3) cells with Hcy at different concentrations and durations, and then analyzed expression of autophagy-related markers and connexins, as well as phosphorylated mTOR (p-mTOR) in these cells by Western blotting. Formation of autophagic vacuoles and intracellular Ca2+ in the Hcy-treated cells were observed by fluorescence microscopy. Further, we performed a rescue experiment in the Hcy-treated HLC-B3 cells by pre-incubation with rapamycin, an mTOR inhibitor. RESULTS: The serum levels of Hcy in patients with cataracts were significantly increased compared to those in healthy controls. In cultured HLC-B3 cells, expression of autophagy related markers (LC3B and Beclin1) and connexins (Cx43 and Cx50) was inhibited by Hcy treatment in a dose- and duration-dependent manner. Accumulation of Ca2+ in the Hcy-treated lens epithelial cells was observed as a consequence of reduced connexin expression. Meanwhile, expression of p-mTOR increased, representing up-regulation of the mTOR pathway. Importantly, inhibition of autophagy and connexin expression due to hyperhomocysteine was rescued via mTOR suppression by pretreatment with rapamycin in HLC-B3 cells. CONCLUSION: Our results demonstrate that hyperhomocysteine might promote cataract development through two mTOR-mediated pathways in the lens epithelial cells: 1) dysregulation of autophagy and 2) accumulation of intracellular calcium via decreased connexin expression.

7.
Zhongguo Zhong Yao Za Zhi ; 49(13): 3684-3692, 2024 Jul.
Artículo en Chino | MEDLINE | ID: mdl-39041141

RESUMEN

Coronary heart disease is a common cardiovascular disease, attacking about 11.4 million patients in China. With increasing prevalence and mortality year by year, coronary heart disease has become a major factor threatening human health and public health. Although primary and secondary prevention, intervention, coronary artery bypass grafting and other interventions have reduced the death rate, there are drug(aspirin) resistance, secondary nitroglycerin failure, post-intervention fatigue, chest tightness, and an-xiety, and complication with a high risk of bleeding, which have become the key clinical and scientific issues needed to be resolved. Coronary heart disease belongs to the category of chest impediment and heart pain in traditional Chinese medicine(TCM). The TCM etiology of this disease includes external contraction of cold, emotional disorders, constitutional insufficiency, physical weakness, and labor injury, which are closely related to sympathetic nerve activity, state of cardiac and psychological diseases, family history, and cardiovascular metabolic disorders in modern medicine. The TCM causes of coronary heart disease include Qi depression, phlegm turbidity, blood stasis, fire-heat, cold congealing, and healthy Qi deficiency, which are associated with emotional factors such as anxiety and depression, abnormal lipid metabolism, abnormalities in blood circulation and coagulation, inflammatory responses, hyperactive immune responses, and heart failure, chronic wasting disease, or aging, respectively. Accordingly, the patients with Qi depression should be treated with Chaihu Longgu Muli Decoction, and those with phlegm turbidity should be treated with Wendan Decoction and Gualou Xiebai Banxia Decoction. Xuefu Zhuyu Decoction and Guizhi Fuling Pills are recommended for blood stasis, Xiaoxianxiong Decoction and Sanhuang Xiexin Decoction for fire-heat, Zhishi Xiebai Guizhi Decoction for cold congealing, and Renshen Decoction for healthy Qi deficiency. Due to the changes in the spectrum of diseases from ancient to modern times as well as the differences in physical constitution, the key cause of coronary heart disease has evolved from the chest Yang deficiency and cold congealing to Qi depression, phlegm turbidity, phlegm combined with stasis, and fire-heat, showing a shift from cold to heat and from deficiency to excess. The combination of classic formulas presents a pattern. That is, the core formula-syndrome correspondence of a disease often fixedly appears with other formula-syndrome correspondence, which may be related to the development of the pathophysiological mechanism of the disease. In the clinical application of modern pharmacological results, the research team has formulated the clinical principle of pathogenesis corresponding to pathological changes and medicinal nature corresponding pharmacological effects. The modern pharmacological research on classic formulas is conducive to targeted treatment. Moreover, classic formulas help to ameliorate aspirin resistance, clopidogrel resistance, post-intervention anxiety, and high risk of bleeding and address the lack of effective blockade of critical lesions in the coronary artery and the progression of post-infarction heart failure. The innovative understanding of the etiology and pathogenesis of co-ronary heart disease helps to improve the clinical efficacy of TCM and the clinical system for treating coronary heart disease with classic formulas.


Asunto(s)
Enfermedad Coronaria , Medicamentos Herbarios Chinos , Medicina Tradicional China , Humanos , Medicamentos Herbarios Chinos/uso terapéutico , Enfermedad Coronaria/tratamiento farmacológico
8.
Nat Commun ; 15(1): 6183, 2024 Jul 23.
Artículo en Inglés | MEDLINE | ID: mdl-39039050

RESUMEN

The de novo construction of enantioenriched 3-hydroxyindolenines and 3-oxindoles from easily available starting materials has been highly desired. Herein, an enantioselectively intermolecular direct [3 + 2] annulation of aryl amine with 2,3-diketoesters to construct 3-hydroxyindolenines with a chiral tertiary alcohol has been disclosed. The results of control experiments and DFT calculation revealed that π - π interaction plays a pivotal role in the enantioselectivity-determining process of [3 + 2] annulation. The following unusual concerted [1,2]-ester migration provides a family of chiral 3-oxindoles in good to excellent yields with excellent enantioselectivity.

9.
Nat Commun ; 15(1): 6115, 2024 Jul 20.
Artículo en Inglés | MEDLINE | ID: mdl-39033136

RESUMEN

Reforming sustainable 3d-metal-based visible light catalytic platforms for inert bulk chemical activation is highly desirable. Herein, we demonstrate the use of a Brønsted acid to unlock robust and practical iron ligand-to-metal charge transfer (LMCT) photocatalysis for the activation of multifarious inert haloalkylcarboxylates (CnXmCOO-, X = F or Cl) to produce CnXm radicals. This process enables the fluoro-polyhaloalkylation of non-activated alkenes by combining easily available Selectfluor as a fluorine source. Valuable alkyl fluorides including potential drug molecules can be easily obtained through this protocol. Mechanistic studies indicate that the real light-harvesting species may derive from the in situ-assembly of Fe3+, CnXmCOO-, H+, and acetonitrile solvent, in which the Brønsted acid indeed increases the efficiency of LMCT between the iron center and CnXmCOO- via hydrogen-bond interactions. We anticipate that this Brønsted acid-unlocked iron LMCT platform would be an intriguing sustainable option to execute the activation of inert compounds.

10.
Dev Cell ; 2024 Jul 04.
Artículo en Inglés | MEDLINE | ID: mdl-38996461

RESUMEN

Hematopoietic stem cell (HSC)-independent lymphopoiesis has been elucidated in murine embryos. However, our understanding regarding human embryonic counterparts remains limited. Here, we demonstrated the presence of human yolk sac-derived lymphoid-biased progenitors (YSLPs) expressing CD34, IL7R, LTB, and IRF8 at Carnegie stage 10, much earlier than the first HSC emergence. The number and lymphopoietic potential of these progenitors were both significantly higher in the yolk sac than the embryo proper at this early stage. Importantly, single-cell/bulk culture and CITE-seq have elucidated the tendency of YSLP to differentiate into innate lymphoid cells and dendritic cells. Notably, lymphoid progenitors in fetal liver before and after HSC seeding displayed distinct transcriptional features, with the former closely resembling those of YSLPs. Overall, our data identified the origin, potential, and migratory dynamics of innate lymphoid-biased multipotent progenitors in human yolk sac before HSC emergence, providing insights for understanding the stepwise establishment of innate immune system in humans.

11.
J Am Chem Soc ; 146(28): 19286-19294, 2024 Jul 17.
Artículo en Inglés | MEDLINE | ID: mdl-38956888

RESUMEN

As one of the most powerful trifluoromethylation reagents, (trifluoromethyl)trimethylsilane (TMSCF3) has been widely used for the synthesis of fluorine-containing molecules. However, to the best of our knowledge, the simultaneous incorporation of both TMS- and CF3- groups of this reagent onto the same carbon of the products has not been realized. Herein, we report an unprecedented SmI2/Sm promoted deoxygenative difunctionalization of amides with TMSCF3, in which both silyl and trifluoromethyl groups are incorporated into the final product, yielding α-silyl-α-trifluoromethyl amines with high efficiency. Notably, the silyl group could be further transformed into other functional groups, providing a new method for the synthesis of α-quaternary α-CF3-amines.

12.
Emerg Infect Dis ; 30(8): 1-13, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-39043566

RESUMEN

Influenza A/H9 viruses circulate worldwide in wild and domestic avian species, continuing to evolve and posing a zoonotic risk. A substantial increase in human infections with A/H9N2 subtype avian influenza viruses (AIVs) and the emergence of novel reassortants carrying A/H9N2-origin internal genes has occurred in recent years. Different names have been used to describe the circulating and emerging A/H9 lineages. To address this issue, an international group of experts from animal and public health laboratories, endorsed by the WOAH/FAO Network of Expertise on Animal Influenza, has created a practical lineage classification and nomenclature system based on the analysis of 10,638 hemagglutinin sequences from A/H9 AIVs sampled worldwide. This system incorporates phylogenetic relationships and epidemiologic characteristics designed to trace emerging and circulating lineages and clades. To aid in lineage and clade assignment, an online tool has been created. This proposed classification enables rapid comprehension of the global spread and evolution of A/H9 AIVs.


Asunto(s)
Gripe Aviar , Gripe Humana , Filogenia , Terminología como Asunto , Animales , Humanos , Gripe Humana/epidemiología , Gripe Humana/virología , Gripe Aviar/virología , Gripe Aviar/epidemiología , Aves/virología , Subtipo H9N2 del Virus de la Influenza A/genética , Subtipo H9N2 del Virus de la Influenza A/clasificación , Glicoproteínas Hemaglutininas del Virus de la Influenza/genética
13.
Biosens Bioelectron ; 262: 116573, 2024 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-39018976

RESUMEN

Drug-induced liver injury (DILI) poses a severe threat to public health. Endoplasmic reticulum (ER) stress contributes significantly to DILI pathogenesis, with peroxynitrite (ONOO-) identified as a pivotal indicator. However, the temporal and spatial fluctuations of ONOO- associated with ER stress in the pathogenesis of DILI remain unclear. Herein, a novel ER-specific near-infrared (NIR) probe (QM-ONOO) with aggregation-induced emission (AIE) features for monitoring ONOO- fluctuations in DILI was elaborately constructed. QM-ONOO exhibited excellent ER-targeting specificity, a large Stoke's shift, and a low detection limit (26.9 nM) toward ONOO-. QM-ONOO performed well in imaging both exogenous and endogenous ONOO- in HepG2 cells. Furthermore, molecular docking calculations validated the ER-targeting mechanism of QM-ONOO. Most importantly, using this probe allowed us to intuitively observe the dynamic fluctuations of ONOO- during the formation and remediation processes of DILI in the acetaminophen (APAP)-induced mouse model. Consequently, this work provides a promising tool for in-depth research of ONOO- associated pathological processes in DILI.


Asunto(s)
Acetaminofén , Enfermedad Hepática Inducida por Sustancias y Drogas , Retículo Endoplásmico , Colorantes Fluorescentes , Ácido Peroxinitroso , Ácido Peroxinitroso/metabolismo , Ácido Peroxinitroso/química , Humanos , Animales , Enfermedad Hepática Inducida por Sustancias y Drogas/patología , Enfermedad Hepática Inducida por Sustancias y Drogas/metabolismo , Colorantes Fluorescentes/química , Retículo Endoplásmico/metabolismo , Ratones , Células Hep G2 , Acetaminofén/toxicidad , Acetaminofén/efectos adversos , Técnicas Biosensibles/métodos , Estrés del Retículo Endoplásmico/efectos de los fármacos , Simulación del Acoplamiento Molecular , Imagen Óptica/métodos
14.
Chem Commun (Camb) ; 60(62): 8008-8019, 2024 Jul 30.
Artículo en Inglés | MEDLINE | ID: mdl-39005163

RESUMEN

Reductive elimination is a key step in Ni-catalysed cross-couplings, which is often considered to result in new covalent bonds. Due to the weak oxidizing ability of Ni(II) species, reductive eliminations from Ni(II) centers are challenging. A thorough mechanistic understanding of this process could inspire the rational design of Ni-catalysed coupling reactions. In this article, we give an overview of recent advances in the mechanistic study of reductive elimination from Ni(II) species achieved by our group. Three possible models for reductive elimination from Ni(II) species were investigated and discussed, including direct reductive elimination, electron density-controlled reductive elimination, and oxidation-induced reductive elimination. Notably, the direct reductive elimination from Ni(II) species often requires a high activation energy in some cases. In contrast, the electron density-controlled and oxidation-induced reductive elimination pathways can significantly enhance the driving force for reductive elimination, accelerating the formation of new covalent bonds. The intricate reaction mechanisms for each of these pathways are thoroughly discussed and systematically summarized in this paper. These computational studies showcase the characteristics of three models for reductive elimination from Ni(II) species, and we hope that it will spur the development of mechanistic studies of cross-coupling reactions.

16.
Blood Sci ; 6(4): e00199, 2024 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-39027902

RESUMEN

Hematopoietic stem progenitor cells (HSPCs) are derived from a specialized subset of endothelial cells named hemogenic endothelial cells (HECs) via a process of endothelial-to-hematopoietic transition during embryogenesis. Recently, with the usage of multiple single-cell technologies and advanced genetic lineage tracing techniques, namely, "TIF" approaches that combining transcriptome, immunophenotype and function/fate analyses, massive new insights have been achieved regarding the cellular and molecular evolution underlying the emergence of HSPCs from embryonic vascular beds. In this review, we focus on the most recent advances in the enrichment markers, functional characteristics, developmental paths, molecular controls, and the embryonic site-relevance of the key intermediate cell populations bridging embryonic vascular and hematopoietic systems, namely HECs and pre-hematopoietic stem cells, the immediate progenies of some HECs, in mouse and human embryos. Specifically, using expression analyses at both transcriptional and protein levels and especially efficient functional assays, we propose that the onset of Kit expression is at the HEC stage, which has previously been controversial.

17.
J Acoust Soc Am ; 155(6): 3600-3603, 2024 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-38829157

RESUMEN

The drive-stack design principle for the Tonpilz transducer aiming to transmit the acoustic signal in an ultra-wideband has been proposed [(2023). J. Acoust. Soc. Am. 154, 3709-3725], in which the design method is obtained and validated through simulation. This letter presents the experimental investigation of a fabricated transducer prototype and gives the measurement results of electroacoustic performance, including the electrical admittance, transmitting voltage response, directivity beam pattern, electroacoustic efficiency, and source level. The results indicate that the transducer can operate in the frequency band from 20 to 80 kHz without deep response notches within the band.

18.
Nat Commun ; 15(1): 5479, 2024 Jun 28.
Artículo en Inglés | MEDLINE | ID: mdl-38942777

RESUMEN

1,2-Difunctionalization of alkynes offers a straightforward approach to access polysubstituted alkenes. However, simultaneous multi-component cascade transformations including difunctionalization of two alkynes with both syn- and anti-selectivity in one catalyst system is undeveloped and proves to be a significant challenge. Herein, we report a Nickel-catalyzed four-component reaction to access polysubstituted 1,3-dienes using two terminal alkynes, aryl boroxines, and perfluoroalkyl iodides, wherein the reaction forms three new C-C bonds in a single vessel and serve as a modular strategy to access polysubstituted 1,3-dienes with excellent chemoselectivity, good regioselectivity and exclusive stereoselectivity. Control experiments reveal the plausible reaction mechanism and DFT calculations explain the cause for the formation of this unusual four-component reaction. Furthermore, we successfully incorporate two biologically active units into 1,2,3,4-tetrasubstituted 1,3-dienes, which greatly increases the diversity of molecular scaffolds and brings more potential values to medicinal chemistry, the synthetic utility of our protocol is further demonstrated by the late-stage transformations.

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