Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 183
Filtrar
1.
EMBO J ; 2024 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-39009676

RESUMO

Anthelmintics are drugs used for controlling pathogenic helminths in animals and plants. The natural compound betaine and the recently developed synthetic compound monepantel are both anthelmintics that target the acetylcholine receptor ACR-23 and its homologs in nematodes. Here, we present cryo-electron microscopy structures of ACR-23 in apo, betaine-bound, and betaine- and monepantel-bound states. We show that ACR-23 forms a homo-pentameric channel, similar to some other pentameric ligand-gated ion channels (pLGICs). While betaine molecules are bound to the classical neurotransmitter sites in the inter-subunit interfaces in the extracellular domain, monepantel molecules are bound to allosteric sites formed in the inter-subunit interfaces in the transmembrane domain of the receptor. Although the pore remains closed in betaine-bound state, monepantel binding results in an open channel by wedging into the cleft between the transmembrane domains of two neighboring subunits, which causes dilation of the ion conduction pore. By combining structural analyses with site-directed mutagenesis, electrophysiology and in vivo locomotion assays, we provide insights into the mechanism of action of the anthelmintics monepantel and betaine.

2.
Nat Methods ; 21(6): 1082-1093, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38831208

RESUMO

The point spread function (PSF) of a microscope describes the image of a point emitter. Knowing the accurate PSF model is essential for various imaging tasks, including single-molecule localization, aberration correction and deconvolution. Here we present universal inverse modeling of point spread functions (uiPSF), a toolbox to infer accurate PSF models from microscopy data, using either image stacks of fluorescent beads or directly images of blinking fluorophores, the raw data in single-molecule localization microscopy (SMLM). Our modular framework is applicable to a variety of microscope modalities and the PSF model incorporates system- or sample-specific characteristics, for example, the bead size, field- and depth- dependent aberrations, and transformations among channels. We demonstrate its application in single or multiple channels or large field-of-view SMLM systems, 4Pi-SMLM, and lattice light-sheet microscopes using either bead data or single-molecule blinking data.


Assuntos
Microscopia de Fluorescência , Imagem Individual de Molécula , Imagem Individual de Molécula/métodos , Microscopia de Fluorescência/métodos , Algoritmos , Processamento de Imagem Assistida por Computador/métodos , Corantes Fluorescentes/química , Modelos Teóricos
3.
Nano Lett ; 24(22): 6761-6766, 2024 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-38775803

RESUMO

Orbital angular momentum (OAM) multiplexed holograms have attracted a great deal of attention recently due to their physically unbounded set of orthogonal helical modes. However, preserving the OAM property in each pixel hinders fine sampling of the target image in principle and requires a fundamental filtering aperture array in the detector plane. Here, we demonstrate the concept of metasurface-based vectorial holography with cylindrical vector beams (CVBs), whose unlimited polarization orders and unique polarization distributions can be used to boost information storage capacity. Although CVBs are composed of OAM modes, the holographic images do not preserve the OAM modes in our design, enabling fine sampling of the target image in a quasi-continuous way like traditional computer-generated holograms. Moreover, the images can be directly observed by passing them through a polarizer without the need for a fundamental mode filter array. We anticipate that our method may pave the way for high-capacity holographic devices.

4.
J Am Chem Soc ; 146(11): 7118-7123, 2024 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-38437170

RESUMO

High-entropy oxides (HEOs) with an ultrathin geometric structure are especially expected to exhibit extraordinary performance in different fields. The phase structure is deemed as a key factor in determining the properties of HEOs, rendering their phase control synthesis tempting. However, the disparity in intrinsic phase structures and physicochemical properties of multiple components makes it challenging to form single-phase HEOs with the target phase. Herein, we proposed a self-lattice framework-guided strategy to realize the synthesis of ultrathin HEOs with desired phase structures, including rock-salt, spinel, perovskite, and fluorite phases. The participation of the Ga assistor was conducive to the formation of the high-entropy mixing state by decreasing the formation energy. The as-prepared ultrathin spinel HEOs were demonstrated to be an excellent catalyst with high activity and stability for the oxygen evolution reaction in water electrolysis. Our work injects new vitality into the synthesis of HEOs for advanced applications and undoubtedly expedites their phase engineering.

5.
Small ; 20(30): e2310887, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38409520

RESUMO

The gradient modulus in beetle setae plays a critical role in allowing it to stand and walk on natural surfaces. Mimicking beetle setae to create a modulus gradient in microscale, especially in the direction of setae radius, can achieve reliable contact and thus strong adhesion. However, it remains highly challenging to achieve modulus gradient along radial directions in setae-like structures. Here, polydimethylsiloxane (PDMS) micropillar with radial gradient modulus, (termed GM), is successfully constructed by making use of the polymerization inhibitor in the photosensitive resin template. GM gains adhesion up to 84 kPa, which is 2.3 and 4.7 times of soft homogeneous micropillars (SH) and hard homogeneous micropillars (HH), respectively. The radial gradient modulus facilitates contact formation on various surfaces and shifts stress concentration from contact perimeter to the center, resulting in adhesion enhancement. Meanwhile, GM achieves strong friction of 8.1 mN, which is 1.2 and 2.6 times of SH and HH, respectively. Moreover, GM possesses high robustness, maintaining strong adhesion and friction after 400 cycles of tests. The work here not only provides a robust structure for strong adhesion and friction, but also establishes a strategy to create modulus gradient at micron-scale.

6.
Small ; 20(24): e2308995, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38168894

RESUMO

Practical applications of lithium metal batteries are limited by unstable solid electrolyte interphase (SEI) and uncontrollable dendrite Li deposition. Regulating the solvation structure of Li+ via modifying electrolyte components enables optimizing the structure of the SEI and realizing dendrite-free Li deposition. In this work, it is found that the ionic-dipole interactions between the electron-deficient B atoms in lithium oxalyldifluoro borate (LiDFOB) and the O atoms in the DME solvent molecule can weaken the interaction between the DME molecule and Li+, accelerating the desolvation of Li+. On this basis, the ionic-dipole interactions facilitate the entry of abundant anions into the inner solvation sheath of Li+, which promotes the formation of inorganic-rich SEI. In addition, the interaction between DFOB- and DME molecules reduces the highest occupied molecular orbital energy level of DME molecules in electrolytes, which improves the oxidative stability of the electrolytes system. As a result, the Li||Li cells in LiDFOB-containing electrolytes exhibit an excellent cyclability of over 1800 h with a low overpotential of 18.2 mV, and the Li||LiFePO4 full cells display a high-capacity retention of 93.4% after 100 cycles with a high Coulombic efficiency of 99.3%.

7.
Small ; : e2404483, 2024 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-39046318

RESUMO

Lithium-oxygen (Li-O2) battery with large theoretical energy density (≈3500 Wh kg-1) is one of the most promising energy storage and conversion systems. However, the slow kinetics of oxygen electrode reactions inhibit the practical application of Li-O2 battery. Thus, designing efficient electrocatalysts is crucial to improve battery performance. Here, Ti3C2 MXene/Mo4/3B2-x MBene superlattice is fabricated its electrocatalytic activity toward oxygen redox reactions in Li-O2 battery is studied. It is found that the built-in electric field formed by a large work function difference between Ti3C2 and Mo4/3B2-x will power the charge transfer at the interface from titanium (Ti) site in Ti3C2 to molybdenum (Mo) site in Mo4/3B2-x. This charge transfer increases the electron density in 4d orbital of Mo site and decreases the d-band center of Mo site, thus optimizing the adsorption of intermediate product LiO2 at Mo site and accelerating the kinetics of oxygen electrode reactions. Meanwhile, the formed film-like discharge products (Li2O2) improve the contact with electrode and facilitate the decomposition of Li2O2. Based on the above advantages, the Ti3C2 MXene/Mo4/3B2-x MBene superlattice-based Li-O2 battery exhibits large discharge specific capacity (17 167 mAh g-1), low overpotential (1.16 V), and superior cycling performance (475 cycles).

8.
Small ; : e2404001, 2024 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-39072918

RESUMO

Graphene has tremendous potential in future electronics due to its superior force, electrical, and thermal properties. However, the development of graphene devices is limited by its complex, high-cost, and low-efficiency preparation process. This study proposes a novel laser bidirectional graphene printing (LBGP) process for the large-scale preparation of patterned graphene films. In LBGP, a sandwich sample composed of a thermoplastic elastomer (TPE) substrate, carbon precursor powder, and a glass cover is irradiated by a nanosecond pulsed laser. The laser photothermal effect converts the carbon precursor into graphene, with partial graphene sheets deposited directly on the TPE substrate and the remaining transferred to the glass cover via a laser-induced plasma plume. This method simultaneously prepares two face-to-face graphene films in a single laser irradiation, integrating synthesis, transfer, and patterning. The resulting graphene patterns demonstrate good performance in flexible pressure sensing and Joule heating, showcasing high sensitivity (7.7 kPa-1), fast response (37 ms), and good cycling stability (2000 cycles) for sensors, and high heating rate (1 °C s-1) and long-term stability (3000 s) for heaters. It is believed that the simple, low-cost, and efficient LBGP process can promote the development of graphene electronics and laser manufacturing processes.

9.
Small ; 20(31): e2309874, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38453676

RESUMO

Garnet-type solid-state electrolytes attract abundant attentions due to the broad electrochemical window and remarkable thermal stability while their poor ionic conductivity obstructs their widespread application in all-solid-state batteries. Herein, the enhanced ionic conductivity of garnet-type solid electrolytes is achieved by partially substituting O2- sites with Cl- anions, which effectively reduce Li+ migration barriers while preserving the highly conductive cubic phase of garnet-type solid-state electrolytes. This substitution not only weakens the anchoring effect of anions on Li+ to widen the size of Li+ diffusion channel but also optimizes the occupancy of Li+ at different sites, resulting in a substantial reduction of the Li+ migration barrier and a notable improvement in ionic conductivity. Leveraging these advantageous properties, the developed Li6.35La3Zr1.4Ta0.6O11.85-Cl0.15 (LLZTO-0.15Cl) electrolyte demonstrates high Li+ conductivity of 4.21×10-6 S cm-1. When integrated with LiFePO4 (LFP) cathode and metallic lithium anode, the LLZTO-0.15Cl electrolyte enables the solid-state battery to operate for more than 100 cycles with a high capacity retention of 76.61% and superior Coulombic efficiency of 99.48%. This work shows a new strategy for modulating anionic framework to enhance the conductivity of garnet-type solid-state electrolytes.

10.
Mol Phylogenet Evol ; 197: 108113, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38796071

RESUMO

A robust and stable phylogenetic framework is a fundamental goal of evolutionary biology. As the third largest insect order in the world following Coleoptera and Diptera, Lepidoptera (butterflies and moths) play a central role in almost every terrestrial ecosystem as indicators of environmental change and serve as important models for biologists exploring questions related to ecology and evolutionary biology. However, for such a charismatic insect group, the higher-level phylogenetic relationships among its superfamilies are still poorly resolved. Compared to earlier phylogenomic studies, we increased taxon sampling among Lepidoptera (37 superfamilies and 68 families containing 263 taxa) and acquired a series of large amino-acid datasets from 69,680 to 400,330 for phylogenomic reconstructions. Using these datasets, we explored the effect of different taxon sampling with significant increases in the number of included genes on tree topology by considering a series of systematic errors using maximum-likelihood (ML) and Bayesian inference (BI) methods. Moreover, we also tested the effectiveness in topology robustness among the three ML-based models. The results showed that taxon sampling is an important determinant in tree robustness of accurate lepidopteran phylogenetic estimation. Long-branch attraction (LBA) caused by site-wise heterogeneity is a significant source of bias giving rise to unstable positions of ditrysian groups in phylogenomic reconstruction. Phylogenetic inference showed the most comprehensive framework to reveal the relationships among lepidopteran superfamilies, and presented some newly relationships with strong supports (Papilionoidea was sister to Gelechioidea and Immoidea was sister to Galacticoidea, respectively), but limited by taxon sampling, the relationships within the species-rich and relatively rapid radiation Ditrysia and especially Apoditrysia remain poorly resolved, which need to increase taxon sampling for further phylogenomic reconstruction. The present study demonstrates that taxon sampling is an important determinant for an accurate lepidopteran tree of life and provides some essential insights for future lepidopteran phylogenomic studies.


Assuntos
Teorema de Bayes , Borboletas , Mariposas , Filogenia , Animais , Mariposas/genética , Mariposas/classificação , Funções Verossimilhança , Borboletas/genética , Borboletas/classificação , Modelos Genéticos
11.
J Vasc Surg ; 80(1): 153-162.e4, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38460766

RESUMO

OBJECTIVE: Selection criteria for carotid duplex ultrasonography screening (DUS) before coronary artery bypass grafting (CABG) is primarily based on limited observational analysis, and the risks associated with carotid artery stenosis (CAS) detected by this approach to preoperative DUS are uncertain. This study aimed to determine the association of carotid DUS with stroke and mortality among patients undergoing CABG. METHODS: Adult patients with coronary artery disease who underwent isolated CABG or CABG with concomitant valvular or congenital procedure were identified. CHA2DS2-VASc score was assessed before CABG, and patients were recorded as high risk if they had a score of 3 or higher. The primary outcomes were stroke and all-cause mortality. Secondary outcomes included ischemic stroke, non-ischemic stroke, transient ischemic attack, and cardiovascular mortality. RESULTS: Among 8958 patients who underwent CABG, 70.9% (n = 6347) received carotid DUS preoperatively (low-risk, 57.3%; high-risk, 42.7%). In the low-risk cohort, there was no significant difference in the risk of stroke (20.7 per 1000 patient-years for CAS vs 13.1 per 1000 patient-years for no CAS; adjusted hazard ratio [aHR], 1.14; 95% confidence interval [CI], 0.78-1.68) or mortality (20.5 per 1000 patient-years for CAS vs 16.8 per 1000 patient-years for no CAS; aHR, 1.33; 95% CI, 0.97-1.83) at 15 years. In the high-risk cohort, CAS was associated with significantly higher risks of stroke at 30 days (433.2 vs 279.5 per 1000 patient-years; aHR, 1.92; 95% CI, 1.00-3.70) and mortality at 15 years (38.4 vs 32.7 per 1000 patient-years; aHR, 1.25; 95% CI, 1.01-1.57) compared with no CAS. CONCLUSIONS: CAS did not impact the incidence of stroke or mortality in the low-risk cohort who underwent CABG. However, in the high-risk cohort, CAS was associated with a significant increase in the risks of 30-day stroke and 15-year mortality, indicating selective carotid DUS is necessarily recommended for these patients.


Assuntos
Estenose das Carótidas , Ponte de Artéria Coronária , Doença da Artéria Coronariana , Valor Preditivo dos Testes , Acidente Vascular Cerebral , Ultrassonografia Doppler Dupla , Humanos , Masculino , Feminino , Ponte de Artéria Coronária/mortalidade , Ponte de Artéria Coronária/efeitos adversos , Idoso , Medição de Risco , Estenose das Carótidas/diagnóstico por imagem , Estenose das Carótidas/mortalidade , Estenose das Carótidas/complicações , Estenose das Carótidas/cirurgia , Pessoa de Meia-Idade , Fatores de Risco , Estudos Retrospectivos , Acidente Vascular Cerebral/mortalidade , Acidente Vascular Cerebral/etiologia , Doença da Artéria Coronariana/diagnóstico por imagem , Doença da Artéria Coronariana/mortalidade , Doença da Artéria Coronariana/cirurgia , Doença da Artéria Coronariana/complicações , Resultado do Tratamento , Fatores de Tempo
12.
Rev Cardiovasc Med ; 25(5): 186, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-39076468

RESUMO

Background: Coronary artery calcification (CAC) is a crucial marker for coronary atherosclerosis, and the extent of CAC is closely linked to the incidence and progression of cardiovascular diseases. The interleukin-2 (IL-2) receptor (IL-2R), which plays a critical role in mediating the proliferation and differentiation of immune cells, may also be involved in the development of CAC. The study aimed to investigate the relationship between IL-2R and CAC, with the goal of providing new insights into cardiovascular diseases. Methods: In this study, we enrolled 606 patients diagnosed with coronary artery disease to assess CAC. Based on coronary artery calcification score (CACS), patients were divided into two groups: the non-severe CAC group (CACS ≤ 400 Agatston units, AU) and the severe CAC group (CACS > 400 AU). Results: The results showed that IL-2R levels were significantly higher in patients with severe CAC compared to those with non-severe CAC (383 vs. 352 pg/mL, p = 0.002). Moreover, the level of IL-2R was positively correlated with the severity of CAC, independent of other clinical risk factors. According to Receiver Operating Characteristic (ROC) curve, the IL-2R prediction model demonstrated a good capability in distinguishing severe CAC with the Area Under the Curve (AUC) value of 0.726. Conclusions: Our study suggests that IL-2R is independently associated with the occurrence of severe CAC in coronary artery disease (CAD) patients. Additionally, IL-2R may play a crucial role in the development of advanced atherosclerosis. Consequently, therapeutic strategies targeting the IL-2/IL-2R pathway may be effective in preventing or treating CAD.

13.
Opt Lett ; 49(10): 2573-2576, 2024 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-38748108

RESUMO

We propose a new, to the best of our knowledge, type of metalens of which the phase profile is extracted from the higher-order Bessel function. A light beam passing through this metalens would focus along the circular trajectory and produces a tightly focusing field. Utilizing phase binarization, we provide a method to design the geometric-phase dielectric metasurface both for phase and polarization modulations. We demonstrate two metalenses for circularly and radially polarized output beams at 633 nm, with the measured 0.737λ and 0.616λ focal spots, respectively. Theoretically, it can realize a super-diffraction-limit spot (0.38λ). This work can extend the way of realizing tightly focused optical devices.

14.
Phys Rev Lett ; 132(13): 133603, 2024 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-38613308

RESUMO

An integrated quantum light source is increasingly desirable in large-scale quantum information processing. Despite recent remarkable advances, a new material platform is constantly being explored for the fully on-chip integration of quantum light generation, active and passive manipulation, and detection. Here, for the first time, we demonstrate a gallium nitride (GaN) microring based quantum light generation in the telecom C-band, which has potential toward the monolithic integration of quantum light source. In our demonstration, the GaN microring has a free spectral range of 330 GHz and a near-zero anomalous dispersion region of over 100 nm. The generation of energy-time entangled photon pair is demonstrated with a typical raw two-photon interference visibility of 95.5±6.5%, which is further configured to generate a heralded single photon with a typical heralded second-order autocorrelation g_{H}^{(2)}(0) of 0.045±0.001. Our results pave the way for developing a chip-scale quantum photonic circuit.

15.
Langmuir ; 40(1): 853-859, 2024 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-38146180

RESUMO

Precision manipulation of various liquids is essential in many fields such as various thermal, optical, and medical applications. This paper proposes an effective noncontact microdroplet separation method that is based on the action of corona discharge. A blade-plate electrode is constructed to generate an ionic wind, thereby enabling the droplet to be separated according to the shape of the blade electrode. Line, curve, S-shape, and parallel separation of the droplet can be realized in the experiment setup. Furthermore, experiment parameters, including the driving voltage, cutting speed, the distance of the upper and lower electrodes, cutting depth, etc., are discussed. Experimental results show that the proposed method is feasible and effective and can be used in application scenarios that require precise manipulation of droplets.

16.
Pharmacol Res ; 202: 107122, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38428703

RESUMO

The ectonucleotidase CD39 has been regarded as a promising immune checkpoint in solid tumors. However, the expression of CD39 by tumor-infiltrating CD8+ T cells as well as their potential roles and clinical implications in human gastric cancer (GC) remain largely unknown. Here, we found that GC-infiltrating CD8+ T cells contained a fraction of CD39hi cells that constituted about 6.6% of total CD8+ T cells in tumors. These CD39hi cells enriched for GC-infiltrating CD8+ T cells with features of exhaustion in transcriptional, phenotypic, metabolic and functional profiles. Additionally, GC-infiltrating CD39hiCD8+ T cells were also identified for tumor-reactive T cells, as these cells expanded in vitro were able to recognize autologous tumor organoids and induced more tumor cell apoptosis than those of expanded their CD39int and CD39-CD8+ counterparts. Furthermore, CD39 enzymatic activity controlled GC-infiltrating CD39hiCD8+ T cell effector function, and blockade of CD39 efficiently enhanced their production of cytokines IFN-γ and TNF-α. Finally, high percentages of GC-infiltrating CD39hiCD8+ T cells correlated with tumor progression and independently predicted patients' poor overall survival. These findings provide novel insights into the association of CD39 expression level on CD8+ T cells with their features and potential clinical implications in GC, and empowering those exhausted tumor-reactive CD39hiCD8+ T cells through CD39 inhibition to circumvent the suppressor program may be an attractive therapeutic strategy against GC.


Assuntos
Linfócitos T CD8-Positivos , Neoplasias Gástricas , Humanos , Neoplasias Gástricas/patologia , Citocinas/metabolismo , Fator de Necrose Tumoral alfa/metabolismo
17.
J Endovasc Ther ; : 15266028241266235, 2024 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-39058276

RESUMO

PURPOSE: Our study aimed to investigate the relationship between fluctuations in different blood pressure (BP) components within 72 hours following endovascular therapy (EVT) and the prognosis of acute ischemic stroke (AIS) patients. METHODS: This prospective multicenter study included 283 AIS patients who underwent EVT and had available BP data. The primary outcome was the ordinal modified Rankin Scale (mRS) score evaluated at 90 days. The secondary outcome was a combination of death and major disability, defined as an mRS score of 3 to 6 within 3 months. RESULTS: After adjusting for imbalanced variables, the highest tertile of systolic blood pressure (SBP) fluctuation had an odds ratio (OR) of 1.747 (95% confidence interval [CI]=1.031-2.961; p for trend=0.035) for the primary outcome and 1.889 (95% CI=1.015-3.516; p for trend=0.039) for the secondary outcome, respectively. Fluctuations in diastolic blood pressure (DBP) (OR=1.914, 95% CI=1.134-3.230, p for trend=0.015) and mean arterial pressure (MAP) (OR=1.759, 95% CI=1.026-3.015, p for trend=0.039) were only associated with the primary outcome. The multivariate-adjusted restricted cubic spline analyses supported these findings. Furthermore, the fluctuations in both SBP and MAP exhibited the significant discriminatory capability in predicting the prognosis, comparable to their mean values. CONCLUSION: Our study revealed that larger fluctuations in SBP, DBP, and MAP within 72 hours after EVT were associated with a higher risk of poor clinical outcomes within 3 months in AIS patients. Controlling BP fluctuations may be valuable for improving the prognosis in patients undergoing EVT. CLINICAL IMPACT: How will this change clinical practice?It provides physicians a new approach to directly monitor BP fluctuations over an extended observation period in AIS patients after EVT in routine clinical practice.What does it mean for the clinicians?These results underscore the importance of giving equal attention to controlling long-term BP fluctuations, in addition to managing mean BP, as a means to improve the prognosis of AIS patients after EVT.What is the innovation behind the study?This study systematically evaluated the association between fluctuations in different blood pressure components and clinical outcomes in AIS patients over an extended period following EVT.

18.
J Org Chem ; 89(11): 7812-7820, 2024 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-38779840

RESUMO

In this paper, the regioselectivity of electrochemical Co(II)-catalyzed [2 + 2 + 2] cycloaddition of terminal alkynes was investigated using density functional theory. We explored in detail the energy profiles for both 1,2,4- and 1,3,5-regioselectivity pathways and revealed the origin of the regioselectivity. Two kinds of conformational isomers derived from the different coordination modes of alkynes with cobaltacyclopentadiene have been found, which were formed through electrochemically mediated redox processes. The regioselectivity of the reaction depends on the two coordination modes. When the Co(II) center attacks α-C of the third alkyne, while ß2-C in cyclopentadiene bonds to ß-C of the alkyne, the reaction favors the formation of 1,2,4-products. In contrast, when the Co(II) center connects to ß-C of the alkyne, it forms only the 1,3,5-products via [4 + 2] cycloaddition because of the steric repulsion between the bulky ligand on Co(II) and the phenyl group in the alkyne.

19.
BMC Neurol ; 24(1): 5, 2024 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-38166773

RESUMO

BACKGROUND: Spinal subarachnoid hematoma (SSH) is a known but rare entity that can cause cauda equina compression. The occurrence of SSH associated with aneurysmal subarachnoid hemorrhage has rarely been described in the literature. CASE PRESENTATION: A 56-year-old woman presented with subarachnoid hemorrhage secondary to a ruptured middle cerebral artery aneurysm and was managed with coiling embolization without stent assistance. There was no history of either lumbar puncture or the use of anticoagulants. The patient developed severe lumbago radiating to bilateral legs nine days after the procedure. Subsequent magnetic resonance imaging demonstrated a SSH extending from L5 to S2 and wrapping around the cauda equina. The patient was treated with intravenous methylprednisolone (250 mg/day) for four consecutive days, followed by a taper of oral prednisolone (20 mg/day) until complete recovery. Magnetic resonance imaging at one month follow-up revealed complete resolution of the SSH. CONCLUSIONS: Here, we report a case of acute cauda equina syndrome caused by a SSH after aneurysmal subarachnoid hemorrhage, which will facilitate timely intervention of patients with this disorder.


Assuntos
Síndrome da Cauda Equina , Cauda Equina , Hemorragia Subaracnóidea , Feminino , Humanos , Pessoa de Meia-Idade , Hemorragia Subaracnóidea/complicações , Hemorragia Subaracnóidea/diagnóstico por imagem , Síndrome da Cauda Equina/complicações , Síndrome da Cauda Equina/diagnóstico por imagem , Hematoma/etiologia , Espaço Subaracnóideo , Imageamento por Ressonância Magnética
20.
Org Biomol Chem ; 22(13): 2558-2561, 2024 03 27.
Artigo em Inglês | MEDLINE | ID: mdl-38450726

RESUMO

An efficient and biomimetic synthetic approach to 3,4-diindolylpyrrole-2,5-dicarboxylate derivatives, including lycogarubin C, lynamicin D and related analogues, was discovered. The crucial transformation included the one-pot formation of two C-N bonds and one C-C bond to construct characteristic pyrrole rings.


Assuntos
Biomimética , Pirróis , Pirróis/química , Indóis/química
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA