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1.
Cureus ; 16(8): e68136, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-39350800

RESUMO

Persistent left superior vena cava (PLSVC) is a relatively rare anatomical anomaly, with a higher prevalence in those with congenital heart defects. While typically asymptomatic, its presence can complicate certain medical procedures, particularly cardiac interventions, such as the implantation of cardiac resynchronization therapy (CRT) devices, due to acute angulation. In this report, we discuss the challenges posed by the unanticipated presence of PLSVC during CRT device implantation and describe the technique used for lead placement using Judkins Right catheter for support, placing coronary wire, and later placing the left ventricle (LV) lead with the help of buddy wire technique, resulting in successful insertion of all three CRT leads despite the anatomical challenges.

2.
Chempluschem ; : e202400393, 2024 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-39388622

RESUMO

The Co(salen) ([LCo(II)]) mediated hydrofunctionalization of alkenes is a highly significant method for forming enantioselective products. In this work, we conducted comprehensive computational investigations to gain insights of the reaction mechanism. The orbital analysis and intrinsic bond orbital analysis (IBO) were utilized to unravel the flow of electrons during the progress of the reaction. We explored various spin state surfaces to understand the possible pathways for the reaction. Initially, [LCo(II)] reacts with an oxidant tertbutyl peroxybenzoate, yielding [LCo(III)OC(O)Ph] and [LCo(III)OtBu]. Subsequently, [LCo(III)OC(O)Ph] reacts with silane to form cobalt hydride ([LCo(III)H]), with the triplet spin state surface being the preferred pathway, featuring an energy barrier of 14.2 kcal mol-1. IBO analysis across this step revealed that it involves the transfer of hydrogen as a hydride. Subsequently, the [LCo(III)H] complex in a triplet spin state undergoes a minimum energy crossing point (MECP) to transition into the singlet spin state, representing its most stable configuration. The [LCo(III)H] complex further reacts with styrene via hydrogen atom transfer on the singlet spin state surface, followed by oxidation and subsequent reaction with indole on the doublet spin surface to yield the hydrofunctionalized product. This work also explores potential enantioselective steps in the reaction.

3.
JACS Au ; 4(9): 3679-3689, 2024 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-39328765

RESUMO

Site-selective C-H borylation is an important strategy for constructing molecular diversity in arenes and heteroarenes. Although transition-metal-catalyzed borylation is well explored, developing metal-free strategies remains scarce. Herein, we developed a straightforward approach for BBr3-mediated selective C-H borylation of naphthamide and phenyl acetamide derivatives under metal-free conditions. This methodology appears to be economical and cost-effective. Successful borylation of drug molecules such as ibuprofen and indoprofen demonstrates the versatility and utility of this metal-free borylation. An exclusive monoselectivity was observed without a trace of diboration. Despite the possibility of forming a 5-membered boronated intermediate at the ortho-position, the selectively 6-membered intermediate paved the way for the formation of the peri-product, which was further supported by detailed computational investigation.

4.
Stud Health Technol Inform ; 318: 156-160, 2024 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-39320198

RESUMO

Reoperation is the most significant complication following any surgical procedure. Developing machine learning methods that predict the need for reoperation will allow for improved shared surgical decision making and patient-specific and preoperative optimisation. Yet, no precise machine learning models have been published to perform well in predicting the need for reoperation within 30 days following primary total shoulder arthroplasty (TSA). This study aimed to build, train, and evaluate a fair (unbiased) and explainable ensemble machine learning method that predicts return to the operating room following primary TSA with an accuracy of 0.852 and AUC of 0.91.


Assuntos
Artroplastia do Ombro , Aprendizado de Máquina , Reoperação , Humanos , Complicações Pós-Operatórias , Salas Cirúrgicas , Masculino , Feminino
5.
Mycoses ; 67(9): e13790, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-39278818

RESUMO

BACKGROUND AND OBJECTIVES: Candidaemia is a potentially life-threatening emergency in the intensive care units (ICUs). Surveillance using common protocols in a large network of hospitals would give meaningful estimates of the burden of candidaemia and central line associated candidaemia in low resource settings. We undertook this study to understand the burden and epidemiology of candidaemia in multiple ICUs of India, leveraging the previously established healthcare-associated infections (HAI) surveillance network. Our aim was also to assess the impact that the pandemic of COVID-19 had on the rates and associated mortality of candidaemia. METHODS: This study included adult patients from 67 Indian ICUs in the AIIMS-HAI surveillance network that conducted BSI surveillance in COVID-19 and non-COVID-19 ICUs during and before the COVID-19 pandemic periods. Hospitals identified healthcare-associated candidaemia and central line associated candidaemia and reported clinical and microbiological data to the network as per established and previously published protocols. RESULTS: A total of 401,601 patient days and 126,051 central line days were reported during the study period. A total of 377 events of candidaemia were recorded. The overall rate of candidaemia in our network was 0.93/1000 patient days. The rate of candidaemia in COVID-19 ICUs (2.52/1000 patient days) was significantly higher than in non-COVID-19 ICUs (1.05/patient days) during the pandemic period. The rate of central line associated candidaemia in COVID-19 ICUs (4.53/1000 central line days) was also significantly higher than in non-COVID-19 ICUs (1.73/1000 central line days) during the pandemic period. Mortality in COVID-19 ICUs associated with candidaemia (61%) was higher than that in non-COVID-19 ICUs (41%). A total of 435 Candida spp. were isolated. C. tropicalis (26.7%) was the most common species. C. auris accounted for 17.5% of all isolates and had a high mortality. CONCLUSION: Patients in ICUs with COVID-19 infections have a much higher risk of candidaemia, CLAC and its associated mortality. Network level data helps in understanding the true burden of candidaemia and will help in framing infection control policies for the country.


Assuntos
COVID-19 , Candidemia , Infecção Hospitalar , Unidades de Terapia Intensiva , Humanos , COVID-19/epidemiologia , Candidemia/epidemiologia , Índia/epidemiologia , Unidades de Terapia Intensiva/estatística & dados numéricos , Masculino , Pessoa de Meia-Idade , Feminino , Adulto , Infecção Hospitalar/epidemiologia , SARS-CoV-2 , Idoso , Infecções Relacionadas a Cateter/epidemiologia , Infecções Relacionadas a Cateter/microbiologia , Pandemias
6.
Eur Heart J Case Rep ; 8(9): ytae482, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-39308926

RESUMO

Background: Amoebiasis is a prevalent infection in the tropics and can sometimes present as liver abscess. Cardiac tamponade is an uncommon complication of ruptured amoebic liver abscess requiring urgent pericardiocentesis, which has a high success rate, but procedural complications can include injury to cardiac chambers, abdominal viscera, and even death. This case underscores the approach to diagnose and manage an unintended visceral puncture during pericardiocentesis, which is a rare but life-threatening complication. Case summary: A 41-year-old male presented with intermittent fever over 2 months and chest pain for 15 days. Echocardiography revealed a significant pericardial effusion causing cardiac tamponade. In an emergency setting, percutaneous pericardiocentesis was attempted to drain the effusion. However, the pigtail inadvertently punctured a sizable liver abscess. Consequently, another pigtail was inserted into the pericardial cavity to successfully drain the effusion. Patient was discharged on Day 12 and is doing well at 6 months follow-up. Discussion: A previously undiagnosed case of a ruptured amoebic liver abscess presented with the uncommon complication of cardiac tamponade, necessitating emergency pericardiocentesis, which inadvertently led to the cannulation of the liver abscess. This case underscores the significance of image-guided pericardiocentesis in minimizing procedural complications. This case also highlights the intricacies of addressing accidental visceral puncture during pericardiocentesis, specially involving the liver. It also underscores the need to consider the possibility of a ruptured amoebic liver abscess when anchovy sauce-like pus is drained from pericardial cavity, especially in high epidemiologically prevalent country like India.

7.
JBJS Rev ; 12(8)2024 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-39172870

RESUMO

BACKGROUND: Hip arthroscopy has seen a significant surge in utilization, but complications remain, and optimal functional outcomes are not guaranteed. Artificial intelligence (AI) has emerged as an effective supportive decision-making tool for surgeons. The purpose of this systematic review was to characterize the outcomes, performance, and validity (generalizability) of AI-based prediction models for hip arthroscopy in current literature. METHODS: Two reviewers independently completed structured searches using PubMed/MEDLINE and Embase databases on August 10, 2022. The search query used the terms as follows: (artificial intelligence OR machine learning OR deep learning) AND (hip arthroscopy). Studies that investigated AI-based risk prediction models in hip arthroscopy were included. The primary outcomes of interest were the variable(s) predicted by the models, best model performance achieved (primarily based on area under the curve, but also accuracy, etc), and whether the model(s) had been externally validated (generalizable). RESULTS: Seventy-seven studies were identified from the primary search. Thirteen studies were included in the final analysis. Six studies (n = 6,568) applied AI for predicting the achievement of minimal clinically important difference for various patient-reported outcome measures such as the visual analog scale and the International Hip Outcome Tool 12-Item Questionnaire, with area under a receiver-operating characteristic curve (AUC) values ranging from 0.572 to 0.94. Three studies used AI for predicting repeat hip surgery with AUC values between 0.67 and 0.848. Four studies focused on predicting other risks, such as prolonged postoperative opioid use, with AUC values ranging from 0.71 to 0.76. None of the 13 studies assessed the generalizability of their models through external validation. CONCLUSION: AI is being investigated for predicting clinical outcomes after hip arthroscopy. However, the performance of AI models varies widely, with AUC values ranging from 0.572 to 0.94. Critically, none of the models have undergone external validation, limiting their clinical applicability. Further research is needed to improve model performance and ensure generalizability before these tools can be reliably integrated into patient care. LEVEL OF EVIDENCE: Level IV. See Instructions for Authors for a complete description of levels of evidence.


Assuntos
Artroscopia , Inteligência Artificial , Humanos , Artroscopia/métodos , Articulação do Quadril/cirurgia , Resultado do Tratamento
8.
Artigo em Inglês | MEDLINE | ID: mdl-39039684

RESUMO

Alzheimer's disease (AD) is a progressive neurodegenerative disease that falls under the umbrella of dementia and is characterized by the presence of enormously neurotoxic amyloid- beta (Aß) plaques and neurofibrillary tangles (NFTs) of tau protein inside the brain. AD remains an intractable global health challenge with limited therapeutic options. Early diagnosis, enabled by biomarkers and neuroimaging, is pivotal for optimizing treatment outcomes. Immunotherapeutic strategies, including monoclonal antibodies, active vaccination, and passive immunization, have been developed to target hallmark AD pathology, such as amyloid-beta aggregation. Here we summarized the emerging role of immunotherapies in the early stages of AD, shedding light on recent breakthroughs and clinical progress. Challenges, including treatment response variability and safety concerns, are discussed alongside evolving approaches, such as personalized immunotherapy and combinatorial treatments. This concise review underscores the promise of immunotherapies as a transformative approach to AD intervention, offering hope for a brighter future in the quest to combat this devastating neurodegenerative disease.

9.
Cureus ; 16(6): e62998, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-39050293

RESUMO

Background and objective Tuberculosis (TB), caused by Mycobacterium tuberculosis, remains a significant global health concern, with India being a hotspot for the disease burden. Central nervous system (CNS) tuberculosis, though comprising a smaller proportion of total TB cases, is associated with significant morbidity and mortality. This study aimed to explore the utility of diffusion tensor imaging (DTI) in assessing the microstructural changes in white matter tracts associated with CNS tuberculosis. Materials and methods This study was conducted over two years at the All India Institute of Medical Sciences, Rishikesh. We employed a cross-sectional observational design and included patients with definite or highly probable tuberculous meningitis, alongside healthy controls. Results Our findings revealed a significant reduction in fractional anisotropy (FA) values in various white matter tracts of patients with CNS tuberculosis compared to healthy individuals. This reduction in FA correlated with the severity of tuberculous meningitis, particularly in the corpus callosum. Additionally, DTI highlighted distinct patterns of white matter involvement around intraparenchymal lesions, suggesting potential implications for clinical outcomes. The study emphasizes the utility of FA values in grading disease severity and prognosticating treatment outcomes in CNS tuberculosis. Conclusions Overall, this study provides valuable insights into the microstructural alterations in white matter tracts associated with CNS tuberculosis, highlighting the potential of DTI in early diagnosis, grading disease severity, and monitoring treatment response. We believe these findings will pave the way for further research to optimize the clinical management of this debilitating disease.

10.
Nanoscale ; 16(31): 14940-14952, 2024 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-39046356

RESUMO

Inspired by natural metallopeptides, our work focuses on engineering self-assembling nanostructures of C2-symmetric metallopeptide conjugates (MPC) from a pyridine-bis-tripeptide bioprobe that uniquely detects lead (Pb2+) ions by emitting a fluorescence signal at 450 nm, which is further intensified in the presence of DAPI (λem = 458 nm), enhancing the bioimaging quality. This study enables precise lead quantification by modulating the ionic conformation and morphology. Experimental and theoretical insights elucidate the nanostructure formation mechanism, laying the groundwork for materials encapsulation and advancing lead detoxification. Our proof-of-principle experiment, demonstrating actin filament recovery in lead-treated cells, signifies therapeutic potential for intracellular lead aggregation and introduces novel avenues in biotechnological applications within biomaterials science.


Assuntos
Chumbo , Humanos , Chumbo/química , Epitélio Pigmentado da Retina/metabolismo , Epitélio Pigmentado da Retina/citologia , Nanoestruturas/química , Linhagem Celular , Peptídeos/química , Peptídeos/metabolismo , Oligopeptídeos/química , Oligopeptídeos/metabolismo , Piridinas/química
11.
Anticancer Res ; 44(7): 2769-2774, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38925845

RESUMO

BACKGROUND/AIM: Chemotherapy-induced peripheral neuropathy (CIPN) continues to be a major source of chronic morbidity in patients with cancer. Current treatment options and efficacy are limited; thus, there is a need to investigate more effective therapeutic options. Spinal neuromodulation including dorsal column spinal cord stimulation (SCS) and dorsal root ganglion stimulation (DRG-S) are being explored for these patients. The purpose of this narrative review was to critically summarize and evaluate the advancements that have been made in utilizing SCS and DRG-S for CIPN. MATERIALS AND METHODS: A thorough literature search was conducted using PubMed for any research on patients with CIPN who underwent DRG-S or SCS. Studies involving patients with general cancer-related pain were not included. Only articles that were published in English, had original, extractable data, and were available on or before August 1, 2023, were included. RESULTS: This study evaluated twelve studies with a total of 13 patients that reported using SCS for CIPN and four studies with a total of 12 patients that reported using DRG-S for CIPN. Many of the studies demonstrated that DRG-S or SCS can assist in reducing opioid consumption, lowering pain scores, and improving sensory deficits. CONCLUSION: DRG-S and SCS have the potential to improve symptoms and lower medication usage in patients suffering from CIPN. Spinal neuromodulation could be considered as an alternative therapy for patients with persistent symptoms.


Assuntos
Antineoplásicos , Doenças do Sistema Nervoso Periférico , Estimulação da Medula Espinal , Humanos , Doenças do Sistema Nervoso Periférico/induzido quimicamente , Doenças do Sistema Nervoso Periférico/terapia , Estimulação da Medula Espinal/métodos , Antineoplásicos/efeitos adversos , Gânglios Espinais , Neoplasias/tratamento farmacológico , Neoplasias/terapia , Manejo da Dor/métodos
12.
Recent Adv Drug Deliv Formul ; 18(2): 138-154, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38808393

RESUMO

BACKGROUND: Nanophytosomes represent an effective choice for topical drug delivery systems thanks to their small size, general non-toxicity, ease of functionalization and high surface to volume ratio. The goal of the current study was to investigate the potential benefits of using Hypericum perforatum extract nanogel as a means of improving skin penetration and prolonging skin deposition in dermatitis similar to psoriasis. METHODS: Nanophytosomes (NPs) were developed, optimised and thoroughly characterised. The optimised NPs were then placed in a Carbopol gel base matrix and tested ex-vivo (skin penetration and dermatokinetic) and in-vivo (antipsoriatic activity in an Imiquimod-induced psoriatic rat model). RESULTS: The optimised NPs had a spherical form and entrapment efficiency of 69.68% with a nanosized and zeta potential of 168 nm and -10.37mV, respectively. XRD spectra and transmission electron microscopy tests confirmed the plant botanical encapsulation in the NPs. Following 60 days of storage at 40 ± 2°C/75 ± 5% RH, the optimised formula remained relatively stable. As compared to extract gel, nano-gel showed a much-improved ex vivo permeability profile and considerable drug deposition in the viable epidermal-dermal layers. When developed nano-gel was applied topically to a rat model of psoriasis, it demonstrated distinct in vivo anti-psoriatic efficacy in terms of drug activity and reduction of epidermal thickness in comparison to other formulations and the control. ELISA and histopathologic studies also demonstrated that nano-organogel had improved skin integrity and downregulated inflammatory markers (IL-17, IL-6, IFN-γ and MCP-1). CONCLUSION: Findings suggest that a developed plant botanicals-based nanogel has a potential for the treatment of psoriasis-like dermatitis with better skin retention and effectiveness.


Assuntos
Administração Cutânea , Hypericum , Nanogéis , Psoríase , Absorção Cutânea , Animais , Psoríase/tratamento farmacológico , Psoríase/patologia , Hypericum/química , Absorção Cutânea/efeitos dos fármacos , Nanogéis/química , Ratos , Extratos Vegetais/administração & dosagem , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Extratos Vegetais/farmacocinética , Masculino , Pele/metabolismo , Pele/efeitos dos fármacos , Pele/patologia , Imiquimode/administração & dosagem , Imiquimode/farmacologia , Modelos Animais de Doenças , Polietilenoglicóis/química , Polietilenoglicóis/administração & dosagem , Polietilenoimina/química , Polietilenoimina/administração & dosagem , Nanopartículas/química , Nanopartículas/administração & dosagem , Portadores de Fármacos/química , Ratos Sprague-Dawley , Tamanho da Partícula
13.
Chem Asian J ; 19(14): e202400282, 2024 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-38627954

RESUMO

The Cu-O-Cu core exhibits methane-to-methanol conversion, mirroring the reactivity of the copper-containing enzyme pMMO. Herein, we computationally examined the reactivity of a biomimetic Cu-O-Cu core towards methane-to-methanol conversion. The oxygen atom of the Cu-O-Cu core abstracts hydrogen present in the C-H bond of methane. The spin density at the bridging oxygen helps to abstract hydrogen from the C-H bond. We modulated the spin density of the bridging oxygen by substituting only a single copper atom of the Cu-O-Cu core by metals (M) such as Fe, Co, and Ag. These substitutions result in bimetallic [Cu-O-M]2+ models. We observed that the energy barriers for the C-H activation step and the subsequent rebound step vary with the metal M. [Cu-O-Ag]2+ exhibits the highest reactivity for M2M conversion, while [Cu-O-Fe]2+ displays the lowest reactivity. To understand the different reactivity of these models towards M2M conversion, we employed distortion-interaction analysis, orbital analysis, spin density analysis, and quantum theory of atoms in molecules analysis. Orbital analysis reveals that all four adducts follow a hydrogen atom transfer mechanism for C-H activation. Further, spin density analysis reveals that a higher spin density on the bridging oxygen leads to a lower C-H activation barrier.

14.
J Phys Chem A ; 128(20): 4114-4127, 2024 May 23.
Artigo em Inglês | MEDLINE | ID: mdl-38659086

RESUMO

In recent years, noninnocent pyridine diimine (PDI) complexes featuring first-row transition metals have emerged as prominent catalysts, demonstrating efficacy in a diverse range of vital organometallic transformations. However, the inherent complexity of the fundamental reactivity paradigm in these systems arises from the presence of a noninnocent ligand and the multispin feasibility of 3d metals. While density functional theory (DFT) has been widely used to unravel mechanistic insights, its limitations as a single-reference method can potentially misrepresent spin-state energetics, compromising our understanding of these intricate systems. In this study, we employ extensive high-level ab initio state averaged-complete active space self-consistent field/N-electron valence state perturbation theory (SA-CASSCF/NEVPT2) calculations in combination with DFT to investigate an iron-PDI-catalyzed [2 + 2] cycloaddition reaction of alkenes. The transformation proceeds through two major steps: oxidative cyclization and reductive elimination. Contrary to the predictions of DFT calculations, which suggest two-state reactivity in the reaction and identify reductive elimination as the turnover-limiting step, SA-CASSCF/NEVPT2-corrected results unequivocally establish a single-state reactivity scenario with oxidative cyclization as the turnover-limiting step. SA-CASSCF/NEVPT2-based insights into electronic ground states and electron distribution elucidate the intriguing interactions between the PDI ligand and the iron center, revealing the highly multiconfigurational nature of these species and providing a precise depiction of metal-ligand cooperativity throughout the transformation. A comparative assessment of several widely recognized DFT functionals against SA-CASSCF/NEVPT2-corrected data indicates that single-point energy calculations using the modern density functional MN15 on TPSSh geometries offer the most reliable density functional methodology, in scenarios where SA-CASSCF/NEVPT2 computational cost is a consideration.

15.
Chemistry ; 30(38): e202401050, 2024 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-38606609

RESUMO

Metal-free boron-based catalysts such as boron oxide (B2O3) and boron nitride (h-BN) are promising catalysts for methane oxidation to HCHO and CO. The B2O3 catalyst contains various probable boron sites (B1 to B6), which may be responsible for methane oxidation. In this work, we utilized density functional theory to compare two relevant geometrically identical boron sites (B2 and B4) for their reactivities. The two sites are explored in-detail for the conversion of methane to formaldehyde (M2F), carbon monoxide and carbon dioxide. The B4 site activates the methane C-H bond easily as compared to the B2 site. In M2F conversion, the rate-determining step for the B2 site is the co-activation of dioxygen and methane, whereas over the B4 site, formaldehyde formation is the rate-determining step. The computationally-determined RDS for the B4 site coincides well with the reported experiments. It is further revealed that this site also prefers the formation of CO over CO2, which is in-line with the experiments in literature. It is also shown through orbital analysis that methanol formation does not occur during methane oxidation. We employed descriptors such as condensed Fukui functions and global electrophilicity index to chemically distinct these twin sites.

16.
Pharmaceuticals (Basel) ; 17(2)2024 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-38399427

RESUMO

The current study was conducted to examine the possible advantages of Heydotis corymbosa (L.) Lam. extract nanogel as a perspective for enhanced permeation and extended skin deposition in psoriasis-like dermatitis. Optimised nanophytosomes (NPs) were embedded in a pluronic gel base to obtain nanogel and tested ex vivo (skin penetration and dermatokinetics) and in vivo. The optimised NPs had a spherical form and entrapment efficiency of 73.05 ± 1.45% with a nanosized and zeta potential of 86.11 nm and -10.40 mV, respectively. Structural evaluations confirmed encapsulation of the drug in the NPs. Topical administration of prepared nanogel to a rat model of psoriasis-like dermatitis revealed its specific in vivo anti-psoriatic efficacy in terms of drug activity compared to the control and other formulations. Nanogel had improved skin integrity and downregulation of inflammatory cytokines. These findings suggest that developed phytoconstituent-based nanogel has the potential to alleviate psoriasis-like dermatitis with better skin retention and effectiveness.

17.
Chemistry ; 30(14): e202303722, 2024 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-38168869

RESUMO

The Cu-O-Cu core has been proposed as a potential site for methane oxidation in particulate methane monooxygenase. In this work, we used density functional theory (DFT) to design a mixed-valent CuIII -O-CuII species from an experimentally known peroxo-dicopper complex supported by N-donor ligands containing phenolic groups. We found that the transfer of two-protons and two-electrons from phenolic groups to peroxo-dicopper core takes place, which results to the formation of a bis-µ-hydroxo-dicopper core. The bis-µ-hydroxo-dicopper core converts to a mixed-valent CuIII -O-CuII core with the removal of a water molecule. The orbital and spin density analyses unravel the mixed-valent nature of CuIII -O-CuII . We further investigated the reactivity of this mixed-valent core for aliphatic C-H hydroxylation. Our study unveiled that mixed-valent CuIII -O-CuII core follows a hydrogen atom transfer mechanism for C-H activation. An in-situ generated water molecule plays an important role in C-H hydroxylation by acting as a proton transfer bridge between carbon and oxygen. Furthermore, to assess the relevance of a mixed-valent CuIII -O-CuII core, we investigated aliphatic C-H activation by a symmetrical CuII -O-CuII core. DFT results show that the mixed-valent CuIII -O-CuII core is more reactive toward the C-H bond than the symmetrical CuII -O-CuII core.

18.
Chemistry ; 30(17): e202303371, 2024 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-38221895

RESUMO

Transition-metal based catalysts have been widely employed to catalyze partial oxidation of light alkanes. Recently, metal-free hexagonal-boron nitride (h-BN) has emerged as a promising catalyst for the oxidation of CH4 to HCHO and CO; however, the intricate catalytic surface of h-BN at molecular and electronic levels remains inadequately understood. Key questions include how electron-deficient boron atoms in h-BN reduce O2, and whether the partial oxidation of methane over h-BN exhibits similarities to traditional transition-metal catalysts. In our study, we computationally-mapped in-detail the surface catalytic-space of h-BN for methane oxidation. We considered different structures of h-BN and show that these structures contain numerous sites for O2 binding and therefore various routes for methane oxidation are possible. The activation barriers for methane oxidation via various paths varies from ~83 to ~123 kcal mol-1. To comprehend the differences in activation barriers, we employed geometrical, orbital and distortion/interaction analysis (DIA). Orbital analysis reveals that methane activation over h-BN in presence of dioxygen follows a standard hydrogen atom transfer mechanism. It is also shown that water plays an intriguing role in reducing the barrier for HCHO and CO formation by acting as a bridge.

19.
Dalton Trans ; 53(3): 986-995, 2024 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-38088032

RESUMO

Copper complexes [Cu(L1H)ClO4] (1) and [Cu(L2)NO3] (2), which are relevant to the metal site of the galactose oxidase enzyme, were synthesized and characterized by different spectroscopic methods. L1H2 and L2H2 [where L1H2 stands for 2,2'-((1E,1'E)(2,2'-(pyridine-2,6-diyl)bis(2-phenylhydrazin-2-yl-1-ylidene))bis(methanylylidene))diphenol and L2H2 stands for 6,6'-((1E,1'E)-(2,2'-(pyridine-2,6-diyl)bis(2-phenylhydrazin-2-yl-1-ylidene))bis(methanylylidene))bis(2,4-di-tert-butylphenol), H stands for dissociable proton] are pentadentate ligands. These ligands provide pyridyl N, two imine N, and two non-innocent phenoxyl and phenolato O donors, forming complex 1 as a non-radical complex, while complex 2 is a phenoxyl radical complex. The molecular structures of complexes 1 and 2 were authenticated by X-ray crystallography. Benzyl alcohol oxidation was investigated, and the conversion of 9,10-dihydroanthracene to anthracene was examined to scrutinize the H-atom abstraction reaction. Nuclease activity with complexes 1 and 2 was investigated by self-activated plasmid DNA (pBR322) cleavage. Non-innocent properties of the ligand-containing phenolato function were investigated by DFT calculations.


Assuntos
Cobre , Hidrogênio , Fenóis , Cobre/química , Galactose Oxidase/química , Clivagem do DNA , Metais , Piridinas , Ligantes , Cristalografia por Raios X
20.
Air Med J ; 43(1): 34-36, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38154837

RESUMO

OBJECTIVE: The Los Angeles County Fire Department Lifeguard Division responds to water rescues and medical and dive emergencies across 72 miles of Southern California coastline and Catalina Island. Limited advanced life support resources make cardiac arrest resuscitations logistically challenging during transport to shore or the hyperbaric chamber. This proof-of-concept study looked to determine if an i-Gel (Intersurgical Complete Respiratory Systems, Wokingham, Berkshire, UK) supraglottic airway device would either become dislodged or compromise ventilations during prolonged resuscitation at high speeds over open water with an ongoing automatic chest compression device (ACCD). METHODS: A simulated resuscitation was performed on the Los Angeles County Lifeguard rescue boat while underway at speeds up to 25 knots. A LUCAS ACCD (Jolife AB, Ideon Science Park, Lund, Sweden) and a size 3 i-Gel were used. The volume of ventilations and depth of compressions were continuously monitored using the AmbuMan Advanced manikin (Ambu, Ballerup, Denmark). RESULTS: The i-Gel supraglottic airway device delivered appropriate ventilations measuring between 300 and 400 mL/breath when delivered on the upstroke of compression. The i-Gel did not dislodge during transport. CONCLUSION: The i-Gel supraglottic airway device appears to provide adequate ventilations without dislodgment during ongoing compressions with an ACCD during high-speed water transport.


Assuntos
Reanimação Cardiopulmonar , Parada Cardíaca , Humanos , Los Angeles , Navios , Parada Cardíaca/terapia , Manequins , Água
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