Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 219
Filtrar
Mais filtros

Intervalo de ano de publicação
1.
Phys Chem Chem Phys ; 26(3): 1829-1844, 2024 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-38170796

RESUMO

On-the-fly non-adiabatic dynamics methods are becoming more important as tools to characterise the time evolution of a system after absorbing light. These methods, which calculate quantities such as state energies, gradients and interstate couplings at every time step, circumvent the requirement for pre-computed potential energy surfaces. There are a number of different algorithms used, the most common being Tully Surface Hopping (TSH), but all are approximate solutions to the time-dependent Schrödinger equation and benchmarking is required to understand their accuracy and performance. For this, a common set of systems and observables are required to compare them. In this work, we validate the on-the-fly direct dynamics variational multi-configuration Gaussian (DD-vMCG) method using three molecular systems recently suggested by Ibele and Curchod as molecular versions of the Tully model systems used to test one-dimensional non-adiabatic behaviour [Ibele et al., Phys. Chem. Chem. Phys. 2020, 22, 15183-15196]. Parametrised linear vibronic potential energy surfaces for each of the systems were also tested and compared to on-the-fly results. The molecules, which we term the Ibele-Curchod models, are ethene, DMABN and fulvene and the authors used them to test and compare several versions of the Ab Initio Multiple Spawning (AIMS) method alongside TSH. The three systems present different deactivation pathways after excitation to their ππ* bright states. When comparing DD-vMCG to AIMS and TSH, we obtain crucial differences in some cases, for which an explanation is provided by the classical nature and the chosen initial conditions of the TSH simulations.

2.
J Chem Phys ; 160(11)2024 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-38488082

RESUMO

To simulate a 200 nm photoexcitation in cyclobutanone to the n-3s Rydberg state, classical trajectories were excited from a Wigner distribution to the singlet state manifold based on excitation energies and oscillator strengths. Twelve singlet and 12 triplet states are treated using TD-B3LYP-D3/6-31+G** for the electronic structure, and the nuclei are propagated with the Tully surface hopping method. Using time-dependent density functional theory, we are able to predict the bond cleavage that takes place on the S1 surface as well as the ultrafast deactivation from the Rydberg n-3s state to the nπ*. After showing that triplet states and higher-lying singlet states do not play any crucial role during the early dynamics (i.e., the first 300 fs), the SA(6)-CASSCF(8,11)/aug-cc-pVDZ method is used as an electronic structure and the outcome of the non-adiabatic dynamic simulations is recomputed. Gas-phase ultrafast electron diffraction spectra are computed for both electronic structure methods, showing significantly different results.

3.
Orthod Craniofac Res ; 2024 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-38247223

RESUMO

OBJECTIVE: This study aims to utilize the finite element method (FEM) to compare the dentoalveolar and mandibular effects associated with anterior mandibular repositioning using AdvanSync® (ADV) and Twin Block (TB). METHODS: A patient with Class II skeletal malocclusion and mandibular retrognathism was selected. A TB appliance was subsequently applied. Computed Tomography (CT) scans were acquired at the beginning of treatment (T1) and 8 months later (T2). Concurrently, a numerical TB model was validated through FEM simulations, which were compared with the T2 results. The ADV appliance was virtually simulated to evaluate stress and deformation on the condyle, symphysis, first lower molar and lower central incisors. RESULTS: Both simulations demonstrated significant mandibular advancement. However, ADV led to less incisor proclination and more molar intrusion compared to TB. ADV exhibited increased stress in the lower molar area, while TB had higher stress in the lower incisor region. Stress and deformations in the condyle and mandibular symphysis were similar in both simulations, with the highest stress observed at the condylar neck and the lowest at the upper pole of the condylar head. CONCLUSIONS: Both appliances achieved similar levels of mandibular advancement, with greater proclination of the lower central incisors and more widespread distribution of stress and molar intrusion when using ADV compared to TB.

4.
Adicciones ; 0(0): 1912, 2024 Jun 28.
Artigo em Inglês, Espanhol | MEDLINE | ID: mdl-39033527

RESUMO

Integrated treatments are often recommended for adolescents with substance use disorders (SUD) and comorbid pathologies. This study aims to compare the effectiveness of two different intervention programs (integrated and parallel) and to investigate treatment outcome predictors. Seventy-five adolescents (13-17 years old) with substance use and comorbid disorders referred to our outpatient program were randomized to integrated (n = 33) or parallel (n = 32) treatment groups. Their sociodemographic variables, psychopathology, substance use problems, and global functioning were assessed at baseline and 12 months after treatment initiation. Both treatments were associated with positive pre-post changes in several outcome variables (severity of school, family, and psychiatric problems; global functioning; and stage of change). Integrated treatment showed better outcome on adherence (χ2 = 14.328; p > .001) and a composite global measure based on the severity of drug-related problems (χ2 = 8.833, p = .003). Following an adaptive treatment strategy, we offered patients who dropped out of parallel treatment (n = 12) the possibility of entering integrated treatment. Eleven of them accepted and constituted a third comparison group (parallel-to-integrated). Multivariate logistic regression analysis showed that the likelihood of a positive global treatment outcome increased with integrated or parallel-to-integrated treatment, internalizing or mixed comorbid disorders, older age, and fewer legal issues. Integrated treatment showed better adherence and global treatment outcomes than parallel treatment in adolescent patients with dual disorders. Older age and fewer legal issues were also related to a positive global treatment outcome.


Los tratamientos integrados suelen recomendarse para adolescentes con trastornos por uso de sustancias (TUS) y patologías comórbidas. Este estudio compara la eficacia de dos programas de intervención (integrado y paralelo) e investiga factores predictores de resultados del tratamiento. Setenta y cinco adolescentes (13-17 años) con TUS y trastorno comórbido, remitidos a un programa ambulatorio, fueron asignados aleatoriamente a un tratamiento integrado (n = 33) o paralelo (n = 32). Se evaluaron variables sociodemográficas, psicopatología, consumo de sustancias y funcionamiento global al inicio del tratamiento y 12 meses después. Ambos tratamientos se asociaron con cambios positivos pre-post en diferentes variables (problemas escolares, familiares, psiquiátricos, funcionamiento global y estadio de cambio). El tratamiento integrado mostró mejores resultados en adherencia (χ2 = 14,328; p > ,001) y en una medida global compuesta basada en la gravedad de problemas relacionados con drogas (χ2 = 8,833; p = ,003). Siguiendo una estrategia de tratamiento adaptativa, ofrecimos a los pacientes que abandonaron el tratamiento paralelo (n = 12) la posibilidad de entrar en el integrado. Once aceptaron, constituyendo un tercer grupo de comparación («paralelo a integrado¼). El análisis de regresión logística multivariante mostró que la probabilidad de resultado global positivo aumentaba en los pacientes de los grupos integrado y «paralelo a integrado¼, con trastornos comórbidos internalizantes o mixtos, mayor edad y menores problemas legales. El tratamiento integrado mostró mejor adherencia y resultados globales que el paralelo en adolescentes con patología dual. Una mayor edad y menos problemas legales también se relacionaron con un resultado global positivo.

5.
Chemistry ; 29(69): e202302204, 2023 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-37743319

RESUMO

The design of π-extended conjugation 'V'-shaped red shifted bioluminescent D-luciferin analogues based on a novel benzobisthiazole core is described. The divergent synthetic route allowed access to a range of amine donor substituents through an SN Ar reaction. In spectroscopic studies, the 'V'-shaped luciferins exhibited narrower optical band gaps, more red-shifted absorption and emission spectra than D-luciferin. Their bioluminescence characteristics were recorded against four different luciferases (PpyLuc, FlucRed, CBR2 and PLR3). With native luciferase PpyLuc, the 'V'-shaped luciferins demonstrated more red-shifted emissions than D-luciferin (λbl =561 nm) by 60 to 80 nm. In addition, the benzobisthiazole luciferins showed a wide range of bioluminescence spectra from the visible light region (λbl =500 nm) to the nIR window (>650 nm). The computational results validate the design concept which can be used as a guide for further novel D-luciferin analogues based upon other 'V'-shaped heterocyclic cores.


Assuntos
Luciferina de Vaga-Lumes , Luz , Luciferina de Vaga-Lumes/química , Luciferases/química , Análise Espectral , Medições Luminescentes/métodos , Luciferases de Vaga-Lume
6.
Org Biomol Chem ; 21(14): 2941-2949, 2023 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-36928464

RESUMO

A new rationally designed fully rotationally restricted luciferin has been synthesised. This synthetic luciferin, based upon the structure of infraluciferin, has two intramolecular H-bonds to reduce degrees of freedom, an amine group to enhance ICT process, and an alkenyl group to increase π-conjugation. In the spectroscopic measurements and computational calculations, enamine luciferin showed more red-shifted absorption and fluorescence emission than LH2 and iLH2. With PpyWT luciferase enamine luciferin gave bioluminescence at 564 nm which is similar to LH2 at 561 nm. Further investigation by docking studies revealed that the emission wavelength of enamine luciferin might be attributed to the unwanted twisted structure caused by Asp531 within the enzyme. With mutant luciferase FlucRed, the major emission peak was shifted to 606 nm, a distinct shoulder above 700 nm, and 21% of its spectrum located in the nIR range.


Assuntos
Luciferina de Vaga-Lumes , Luciferinas , Simulação de Acoplamento Molecular , Luciferina de Vaga-Lumes/química , Luciferases/química , Medições Luminescentes/métodos
7.
Phys Chem Chem Phys ; 26(1): 174-184, 2023 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-37811951

RESUMO

Assuming a delta pulse excitation, quantum wavepackets are propagated on the excited state manifold in the energy range from 3.4-5.0 eV for coronene and 2.4-3.5 eV for circumcoronene to study the time evolution of the states as well as their lifetimes. The full-dimensional (102 and 210 degrees of freedom for coronene and circumcoronene respectively) non-adiabatic dynamics simulated with the ML-MCTDH method on twelve coupled singlet electronic states show that the different absorption spectra are only due to electronic delocalisation effects that change the excited state energies, but the structural dynamics in both compounds are identical. Breathing and tilting motions drive the decay dynamics of the electronic states away from the Frank-Condon region independently of the size of the aromatic system. This promising result allows the use of coronene as a model system for the dynamics of larger polycyclic aromatic hydrocarbons (PAHs) and graphene one dimensional sheets or nanoflakes.

8.
J Pediatr Hematol Oncol ; 45(6): e671-e677, 2023 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-37314943

RESUMO

The outcome of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in cancer pediatric patients was initially uncertain. The objective of this study was to describe the characteristics and outcome of cancer patients and hematopoietic stem cell transplant recipients from 0 to 19 years with detectable SARS-CoV-2 from April 23, 2020, to April 30, 2022, treated in a tertiary-level hospital in Argentina. A total of 348 cases were registered in 339 patients. The median age was 89.5 (3 to 224) months. The sex was predominantly male: 193 (55.5%). The most common malignant disease was leukemia (42.8%). One hundred four cases (29.9%) had comorbidities. Of the 346 cases with an available blood count, 17.6% had a lymphocyte count <300/mm 3 . Fever was the most common symptom. In most cases (93.1%) presented asymptomatic or mild disease. Twenty-one cases (6%) presented severe or critical status. Eleven of 24 admissions to the intensive care unit were due to COVID-19 (coronavirus disease 2019). Eight patients (2.3%) died. Two deaths were attributable to SARS-CoV-2 (0.6%). Being older, having fever, lymphopenia at diagnosis, and having received hematopoietic stem cell transplant were associated with a more severe disease. Around 90% of the children continued their cancer treatment without any change.


Assuntos
COVID-19 , Transplante de Células-Tronco Hematopoéticas , Neoplasias , Humanos , Masculino , Criança , Idoso de 80 Anos ou mais , Feminino , COVID-19/epidemiologia , SARS-CoV-2 , Centros de Atenção Terciária , Argentina/epidemiologia , Neoplasias/epidemiologia , Neoplasias/terapia , Transplante de Células-Tronco Hematopoéticas/efeitos adversos
9.
J Minim Invasive Gynecol ; 30(11): 912-918, 2023 11.
Artigo em Inglês | MEDLINE | ID: mdl-37463650

RESUMO

STUDY OBJECTIVE: To determine whether a postoperative 5-day treatment schedule with vaginal metronidazole added to conventional antibiotic prophylaxis with 2 g cefazolin modifies the risk of pelvic cellulitis (PC) and pelvic abscess (PA) after total laparoscopic hysterectomy (TLH). DESIGN: A randomized, controlled, triple-blind, multicenter clinical trial. SETTING: Two centers dedicated to minimally invasive gynecologic surgery in Colombia. PATIENTS: A total of 574 patients were taken to TLH because of benign diseases. INTERVENTION: Patients taken to TLH were divided into 2 groups (treatment group, cefazolin 2 g intravenous single dose before surgery + metronidazole vaginal ovules for 5 days postoperatively, control group: cefazolin 2 g intravenous single dose + placebo vaginal ovules for 5 days postoperatively). MEASUREMENTS AND MAIN RESULTS: The absolute frequency (AF) of PC and PA and their relationship with the presence of bacterial vaginosis (BV) were measured. There was no difference in AF of PC (AF, 2/285 [0.7%] vs 5/284 [1.7%] in the treatment and placebo groups, respectively; risk ratio, 1.75; 95% confidence interval, 0.54-5.65; p = .261), nor for PA (AF, 0/285 [0%] vs 2/289 [0.7%]; p = .159, in the treatment and placebo groups, respectively). The incidence of BV was higher in the metronidazole group than the placebo group (42.5% vs 33.4%, p = .026). CONCLUSION: The use of vaginal metronidazole ovules during the first 5 days in postoperative TLH added to conventional cefazolin prophylaxis does not prevent the development of PC or PA, regardless of the patient's diagnosis of BV.


Assuntos
Laparoscopia , Parametrite , Vaginose Bacteriana , Humanos , Feminino , Metronidazol/uso terapêutico , Abscesso/etiologia , Abscesso/prevenção & controle , Cefazolina/uso terapêutico , Parametrite/tratamento farmacológico , Histerectomia/efeitos adversos , Vaginose Bacteriana/diagnóstico , Vaginose Bacteriana/tratamento farmacológico , Laparoscopia/efeitos adversos , Método Duplo-Cego , Antibacterianos/uso terapêutico
10.
Chemistry ; 28(57): e202203016, 2022 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-36202627

RESUMO

Invited for the cover of this issue is the group of G. A. Worth, F. Santoro and R. Improta at UCL, ICOOM-CNR and IBB-CNR. The image depicts charge transfer from guanine to cytosine in solvent after the absorption of light. Read the full text of the article at 10.1002/chem.202201731.


Assuntos
Citosina , Guanina , Clorofórmio , Solventes
11.
Chemistry ; 28(57): e202201731, 2022 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-35950519

RESUMO

We study the ultrafast photoactivated dynamics of the hydrogen bonded dimer Guanine-Cytosine in chloroform solution, focusing on the population of the Guanine→Cytosine charge transfer state (GC-CT), an important elementary process for the photophysics and photochemistry of nucleic acids. We integrate a quantum dynamics propagation scheme, based on a linear vibronic model parameterized through time dependent density functional theory calculations, with four different solvation models, either implicit or explicit. On average, after 50 fs, 30∼40 % of the bright excited state population has been transferred to GC-CT. This process is thus fast and effective, especially when transferring from the Guanine bright excited states, in line with the available experimental studies. Independent of the adopted solvation model, the population of GC-CT is however disfavoured in solution with respect to the gas phase. We show that dynamical solvation effects are responsible for this puzzling result and assess the different chemical-physical effects modulating the population of CT states on the ultrafast time-scale. We also propose some simple analyses to predict how solvent can affect the population transfer between bright and CT states, showing that the effect of the solute/solvent electrostatic interactions on the energy of the CT state can provide a rather reliable indication of its possible population.


Assuntos
Citosina , Ácidos Nucleicos , Clorofórmio , Guanina , Hidrogênio , Teoria Quântica , Solventes
12.
Clin Infect Dis ; 72(11): e711-e719, 2021 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-32964223

RESUMO

BACKGROUND: Up to 30% of patients admitted to hospitals with invasive pneumococcal disease (IPD) experience major adverse cardiovascular event (MACE) including new/worsening heart failure, new/worsening arrhythmia, and/or myocardial infarction. Streptococcus pneumoniae (Spn) is the most frequently isolated bacterial pathogen among community-acquired pneumonia (CAP) patients and the only etiological agent linked independently to MACE. Nevertheless, no clinical data exist identifying which serotypes of Spn are principally responsible for MACE. METHODS: This was an observational multicenter retrospective study conducted through the Public Health Secretary of Bogotá, Colombia. We included patients with a confirmed clinical diagnosis of IPD with record of pneumococcal serotyping and clinical information between 2012 and 2019. Spn were serotyped using the quellung method by the National Center of Microbiology. MACE were determined by a retrospective chart review. RESULTS: The prevalence of MACE was 23% (71/310) in IPD patients and 28% (53/181) in patients admitted for CAP. The most prevalent S. pneumoniae serotype identified in our study was the 19A, responsible for the 13% (42/310) of IPD in our cohort, of which 21% (9/42) presented MACE. Serotypes independently associated with MACE in IPD patients were serotype 3 (odds ratio [OR] 1, 48; 95% confidence interval [CI] [1.21-2.27]; P = .013) and serotype 9n (OR 1.29; 95% CI [1.08-2.24]; P = .020). Bacteremia occurred in 87% of patients with MACE. Moreover, serum concentrations of C-reactive protein were elevated in patients with MACE versus in non-MACE patients (mean [standard deviation], 138 [145] vs 73 [106], P = .01). CONCLUSIONS: MACE are common during IPD with serotype 3 and 9n independently of frequency.


Assuntos
Insuficiência Cardíaca , Infecções Pneumocócicas , Colômbia , Humanos , Lactente , Vacinas Pneumocócicas , Estudos Retrospectivos , Sorogrupo , Sorotipagem
13.
Exp Physiol ; 106(7): 1470-1481, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33945170

RESUMO

NEW FINDINGS: What is the central question of this study? To what extent does testosterone influence haemoglobin formation during male puberty? What is the main finding and its importance? In boys, testosterone might be responsible for about 65% of the increase in haemoglobin mass during puberty. The underlying mechanisms are assumed to be twofold: (i) indirectly, mediated by the increase in lean body mass, and (ii) directly by immediate testosterone effects on erythropoiesis. Thereby, an increase in testosterone of 1 ng/ml is associated with an increase in haemoglobin mass of ∼65 g. These processes are likely to determine endurance performance in adulthood. ABSTRACT: The amount of haemoglobin during puberty is related to endurance performance in adulthood. During male puberty, testosterone stimulates erythropoiesis and could therefore be used as a marker for later endurance performance. This cross-sectional study aimed to determine the relationship between serum testosterone concentration and haemoglobin mass (Hbmass) in both male and female children and adolescents and to evaluate the possible influences of altitude and training. Three-hundred and thirteen differentially trained boys and girls aged from 9 to 18 years and living at altitudes of 1000 and 2600 m above sea level entered the study. The stage of sexual maturation was determined according to the classification of Tanner. Testosterone was measured by ELISA. Hbmass was determined by CO-rebreathing. Haemoglobin concentration did not change during maturation in girls and was 11% higher during puberty in boys, while Hbmass was elevated by 33% in Tanner stage V compared to stage II in girls (498 ± 77 vs. 373 ± 88 g) and by 95% in boys (832 ± 143 vs. 428 ± 95 g). This difference can most likely be attributed to indirect testosterone influences through an increase in lean body mass (LBM) and to direct testosterone effects on erythropoiesis, which increase the Hbmass by ∼65 g per 1 ng/ml. Altitude and training statuses were not associated with testosterone, but with an increase in Hbmass (altitude by 1.1 g/kg LBM, training by 0.8 g/kg LBM). Changes in Hbmass are closely related to testosterone levels during male puberty. Further studies will show whether testosterone and Hbmass during childhood and adolescence can be used as diagnostic tools for endurance talents.


Assuntos
Eritropoese , Testosterona , Adolescente , Adulto , Composição Corporal , Criança , Estudos Transversais , Feminino , Humanos , Masculino , Puberdade
14.
BMC Infect Dis ; 21(1): 1059, 2021 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-34641809

RESUMO

BACKGROUND: The incidence of invasive pneumococcal disease (IPD) varies depending on a number of factors, including vaccine uptake, in both children and adults, the geographic location, and local serotype prevalence. There are limited data about the burden of Streptococcus pneumoniae (Spn), serotype distribution, and clinical characteristics of adults hospitalized due to IPD in Colombia. The objectives of this study included assessment of Spn serotype distribution, clinical characteristics, mortality, ICU admission, and the need for mechanical ventilation. METHODS: This was an observational, retrospective, a citywide study conducted between 2012 and 2019 in Bogotá, Colombia. We analyzed reported positive cases of IPD from 55 hospitals in a governmental pneumococcal surveillance program. Pneumococcal strains were isolated in each hospital and typified in a centralized laboratory. This is a descriptive study stratified by age and subtypes of IPD obtained through the analysis of medical records. RESULTS: A total of 310 patients with IPD were included, of whom 45.5% were female. The leading cause of IPD was pneumonia (60%, 186/310), followed by meningitis. The most frequent serotypes isolated were 19A (13.87%, 43/310) and 3 (11.94%, 37/310). The overall hospital mortality rate was 30.3% (94/310). Moreover, 52.6% (163/310 patients) were admitted to the ICU, 45.5% (141/310) required invasive mechanical ventilation and 5.1% (16/310) non-invasive mechanical ventilation. CONCLUSION: Pneumococcal pneumonia is the most prevalent cause of IPD, with serotypes 19A and 3 being the leading cause of IPD in Colombian adults. Mortality due to IPD in adults continues to be very high.


Assuntos
Infecções Pneumocócicas , Adulto , Criança , Colômbia/epidemiologia , Feminino , Humanos , Infecções Pneumocócicas/epidemiologia , Vacinas Pneumocócicas , Estudos Retrospectivos , Streptococcus pneumoniae
15.
BMC Vet Res ; 17(1): 84, 2021 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-33602243

RESUMO

BACKGROUND: Osteosarcoma is a malignant mesenchymal bone tumor. Although it is a common tumor in the appendicular skeleton of dogs and cats, it is rarely reported in birds. Retroviruses are usually associated with solid tumor development in different avian species. CASE PRESENTATION: This report aims to describe a case of osteosarcoma associated with the avian leukosis virus in a captive bare-faced curassow (Crax fasciolata). A captive adult female bare-faced curassow presented with lameness, hyporexia, and a non-ulcerative and firm tumor in the right femur. The bird was euthanized due to the poor prognosis. Histopathology revealed an infiltrative mesenchymal neoplasm consisting of spindle cells with moderate cell pleomorphism, organized in bundles and interspersed by marked deposition of the osteoid matrix, which was compatible with osteosarcoma affecting both femur and tibiotarsus, with renal metastasis. Immunohistochemistry of the primary and metastatic tumor demonstrated vimentin expression by neoplastic cells. Samples of the neoplasm, bone marrow, and spleen were processed for PCR, which enabled the demonstration of proviral avian leukosis virus (ALV) DNA. CONCLUSIONS: To the best of our knowledge, this is the first report of an osteosarcoma in a bare-faced curassow with an unusual polyostotic manifestation and associated with ALV infection.


Assuntos
Leucose Aviária , Doenças das Aves/patologia , Neoplasias Ósseas/veterinária , Osteossarcoma/veterinária , Animais , Vírus da Leucose Aviária/isolamento & purificação , Doenças das Aves/virologia , Medula Óssea/virologia , Neoplasias Ósseas/virologia , Feminino , Galliformes/virologia , Neoplasias Renais/secundário , Neoplasias Renais/veterinária , Osteossarcoma/virologia , Baço/virologia , Vimentina/metabolismo
16.
Molecules ; 26(23)2021 Nov 29.
Artigo em Inglês | MEDLINE | ID: mdl-34885829

RESUMO

In this work, we report a complete analysis by theoretical and spectroscopic methods of the short-time behaviour of 4-(dimethylamino)benzonitrile (DMABN) in the gas phase as well as in cyclohexane, tetrahydrofuran, acetonitrile, and water solution, after excitation to the La state. The spectroscopic properties of DMABN were investigated experimentally using UV absorption and fluorescence emission spectroscopy. The computational study was developed at different electronic structure levels and using the Polarisable Continuum Model (PCM) and explicit solvent molecules to reproduce the solvent environment. Additionally, excited state quantum dynamics simulations in the diabatic picture using the direct dynamics variational multiconfigurational Gaussian (DD-vMCG) method were performed, the largest quantum dynamics "on-the-fly" simulations performed with this method until now. The comparison with fully converged multilayer multiconfigurational time-dependent Hartree (ML-MCTDH) dynamics on parametrised linear vibronic coupling (LVC) potentials show very similar population decays and evolution of the nuclear wavepacket. The ring C=C stretching and three methyl tilting modes are identified as the responsible motions for the internal conversion from the La to the Lb states. No major differences are observed in the ultrafast initial decay in different solvents, but we show that this effect depends strongly on the level of electronic structure used.

17.
J Am Chem Soc ; 142(17): 7947-7955, 2020 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-32275150

RESUMO

Luminescence from Earth-abundant metal ions in solution at room temperature is a very challenging objective due to the intrinsically weak ligand field splitting of first-row transition metal ions, which leads to efficient nonradiative deactivation via metal-centered states. Only a handful of 3dn metal complexes (n ≠ 10) show sizable luminescence at room temperature. Luminescence in the near-infrared spectral region is even more difficult to achieve as further nonradiative pathways come into play. No Earth-abundant first-row transition metal complexes have displayed emission >1000 nm at room temperature in solution up to now. Here, we report the vanadium(III) complex mer-[V(ddpd)2][PF6]3 yielding phosphorescence around 1100 nm in valeronitrile glass at 77 K as well as at room temperature in acetonitrile with 1.8 × 10-4% quantum yield (ddpd = N,N'-dimethyl-N,N'-dipyridine-2-ylpyridine-2,6-diamine). In addition, mer-[V(ddpd)2][PF6]3 shows very strong blue fluorescence with 2% quantum yield in acetonitrile at room temperature. Our comprehensive study demonstrates that vanadium(III) complexes with d2 electron configuration constitute a new class of blue and NIR-II luminophores, which complement the classical established complexes of expensive precious metals and rare-earth elements.

18.
Phys Chem Chem Phys ; 22(43): 25272-25283, 2020 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-33135692

RESUMO

The first two excitation bands below 7 eV in the electronic absorption spectrum of maleimide are investigated using a model Hamiltonian including four low-lying singlet excited states within the manifold of 24 vibrational modes. The role of non-adiabatic effects is studied and shines light on both the broad, inter-state coupling-dominated spectral band as well as the fine-structured, not-so-strong coupled band. Calculations have been performed using the Multiconfigurational Time-Dependent Hartree (MCTDH) wavepacket propagation method as well as its multilayer version (ML-MCTDH) using a quadratic vibronic coupling (QVC) Hamiltonian model where parameters are obtained from fitting adiabatic potential energy surfaces computed by ab initio methods. The quantum dynamics calculations provide information on the relaxation dynamics and the vibrational modes involved. Already with a low-order vibronic coupling model and only a few modes being considered, a quantitative agreement with the experimental spectrum is obtained. However, it is found that all modes need to be considered to get a full picture of the photo-excited relaxation dynamics of this molecule.

19.
Tob Control ; 29(1): 81-88, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-30705247

RESUMO

INTRODUCTION: While a large body of literature suggests that tobacco control legislation-including fiscal measures such as excise taxes-effectively reduces tobacco smoking, the long-run (10+ years) relationship between cigarettes excise taxes and life expectancy has not been directly evaluated. Here, we test the hypothesis that increases in state cigarette excise taxes are positively associated with long-run increases in population-level life expectancy. METHODS: We studied age-standardised life expectancy among all US counties from 1996 to 2012 by sex, in relation to state cigarette excise tax rates by year, controlling for other demographic, socioeconomic and county-specific features. We used an error-correction model to assess the long-run relationship between taxes and life expectancy. We additionally examine whether the relationship between cigarette taxes and life expectancy was mediated by changes to county smoking prevalence and varied by the sex, income and rural/urban composition of a county. RESULTS: For every one-dollar increase in cigarette tax per pack (in 2016 dollars), county life expectancy increased by 1 year (95% CI 0.60 to 1.40 years) over the long run, with the first 6-month increase in life expectancy taking 10 years to materialise. The association was mediated by changes in smoking prevalence and the magnitude of the association steadily increased as county income decreased. CONCLUSIONS: Results suggest that increasing cigarette excise tax rates translates to consequential population-level improvements in life expectancy, with larger effects in low-income counties.


Assuntos
Fumar Cigarros/epidemiologia , Expectativa de Vida/tendências , Impostos/tendências , Produtos do Tabaco/economia , Adulto , Causas de Morte , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Mortalidade , Adulto Jovem
20.
Proc Natl Acad Sci U S A ; 114(13): 3397-3402, 2017 03 28.
Artigo em Inglês | MEDLINE | ID: mdl-28289213

RESUMO

The Middle Pleistocene is a crucial time period for studying human evolution in Europe, because it marks the appearance of both fossil hominins ancestral to the later Neandertals and the Acheulean technology. Nevertheless, European sites containing well-dated human remains associated with an Acheulean toolkit remain scarce. The earliest European hominin crania associated with Acheulean handaxes are at the sites of Arago, Atapuerca Sima de los Huesos (SH), and Swanscombe, dating to 400-500 ka (Marine Isotope Stage 11-12). The Atapuerca (SH) fossils and the Swanscombe cranium belong to the Neandertal clade, whereas the Arago hominins have been attributed to an incipient stage of Neandertal evolution, to Homo heidelbergensis, or to a subspecies of Homo erectus A recently discovered cranium (Aroeira 3) from the Gruta da Aroeira (Almonda karst system, Portugal) dating to 390-436 ka provides important evidence on the earliest European Acheulean-bearing hominins. This cranium is represented by most of the right half of a calvarium (with the exception of the missing occipital bone) and a fragmentary right maxilla preserving part of the nasal floor and two fragmentary molars. The combination of traits in the Aroeira 3 cranium augments the previously documented diversity in the European Middle Pleistocene fossil record.


Assuntos
Hominidae/anatomia & histologia , Crânio/anatomia & histologia , Animais , Evolução Biológica , Fósseis/anatomia & histologia , Hominidae/genética , Humanos , Paleontologia , Portugal
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA