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BACKGROUND: This trial aimed to assess the efficacy, acceptability and safety of a first-trimester screen-and-prevent strategy for preterm preeclampsia (PE) in Asia. METHODS: Between 1st August 2019 and 28th February 2022, this multicenter stepped wedge cluster randomized trial included maternity/diagnostic units from ten regions in Asia. The trial started with a period where all recruiting centers provided routine antenatal care without study-related intervention. At regular six-week intervals, one cluster was randomized to transit from non-intervention phase to intervention phase. In the intervention phase, women underwent first-trimester screening for preterm PE using a Bayes theorem-based triple-test. High-risk women, with adjusted risk for preterm PE ≥ 1 in 100, received low-dose aspirin from <16 weeks until 36 weeks. RESULTS: Overall, 88.04% (42,897/48,725) of women agreed to undergo first-trimester screening for preterm PE. Among those identified as high-risk in the intervention phase, 82.39% (2,919/3,543) received aspirin prophylaxis. There was no significant difference in the incidence of preterm PE between the intervention and non-intervention phases (adjusted odds ratio [aOR] 1.59; 95% confidence interval [CI] 0.91 to 2.77). However, among high-risk women in the intervention phase, aspirin prophylaxis was significantly associated with a 41% reduction in the incidence of preterm PE (aOR 0.59; 95%CI 0.37 to 0.92). Additionally, it correlated with 54%, 55% and 64% reduction in the incidence of PE with delivery at <34 weeks (aOR 0.46; 95%CI 0.23 to 0.93), spontaneous preterm birth <34 weeks (aOR 0.45; 95%CI 0.22 to 0.92) and perinatal death (aOR 0.34; 95%CI 0.12 to 0.91), respectively. There was no significant between-group difference in the incidence of aspirin-related severe adverse events. CONCLUSIONS: The implementation of the screen-and-prevent strategy for preterm PE is not associated with a significant reduction in the incidence of preterm PE. However, low-dose aspirin effectively reduces the incidence of preterm PE by 41% among high-risk women. The screen-and-prevent strategy for preterm PE is highly accepted by a diverse group of women from various ethnic backgrounds beyond the original population where the strategy was developed. These findings underpin the importance of the widespread implementation of the screen-and-prevent strategy for preterm PE on a global scale.
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The excitation energy transfer (EET) process for photosynthetic antenna complexes consisting of subunits, each comprised of multiple chromophores, remains challenging to describe. The multichromophoric Förster resonance energy transfer theory is a popular method to describe the EET process in such systems. This paper presents a new time-domain method for calculating energy transfer based on the combination of multichromophoric Förster resonance energy transfer theory and the Numerical Integration of the Schrödinger Equation method. After validating the method on simple model systems, we apply it to the Light-Harvesting antenna 2 (LH2) complex, a light harvesting antenna found in purple bacteria. We use a simple model combining the overdamped Brownian oscillators to describe the dynamic disorder originating from the environmental fluctuations and the transition charge from the electrostatic potential coupling model to determine the interactions between chromophores. We demonstrate that with this model, both the calculated spectra and the EET rates between the two rings within the LH2 complex agree well with experimental results. We further find that the transfer between the strongly coupled rings of neighboring LH2 complexes can also be well described with our method. We conclude that our new method accurately describes the EET rate for biologically relevant multichromophoric systems, which are similar to the LH2 complex. Computationally, the new method is very tractable, especially for slow processes. We foresee that the method can be applied to efficiently calculate transfer in artificial systems as well and may pave the way for calculating multidimensional spectra of extensive multichromophoric systems in the future.
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OBJECTIVES: To assess clinical utility of the urine Congo red dot test (CRDT) in predicting composite adverse maternal and neonatal outcomes in women with suspected preeclampsia (PE). METHODS: CRDT result and pregnancy outcomes were prospectively documented in women with new onset or pre-existing hypertension, new or pre-existing proteinuria, PE symptoms and suspected PE-related fetal growth restriction or abnormal Doppler presenting from 20 weeks' gestation between January 2020 and December 2022. Participants and clinicians were blinded to the CRDT result and managed according to internally agreed protocols. Composite maternal outcome was defined as PE, postpartum hemorrhage, intensive care unit admission, and maternal death. Composite neonatal outcome was defined as small for gestational age, preterm birth, 5-min Apgar score < 7, neonatal intensive care unit admission, and neonatal death. RESULTS: Two hundred and forty-four women out of two hundred and fifty-one (97.2%) had a negative CRDT. All seven women with positive CRDT had both adverse maternal and neonatal outcomes, giving positive predictive values (PPV) of 100%. Rates of composite adverse maternal and neonatal outcomes in CDRT negative women were 103/244 [42.2%, 95% confidence interval (CI) 36.2%-48.5%] and 170/244 (69.7%, 95% CI 63.6%-75.1%), respectively. CRDT negative predictive values (NPV) for adverse maternal and neonatal outcomes were, respectively, 141/244 (57.8%, 95% CI 48.6%-68.2%) and 74/244 (30.3%, 95% CI 23.8%-38.1%). CONCLUSION: CRDT had low NPV but high PPV for adverse maternal and neonatal outcomes in women with suspected PE. Its role in clinical management and triage of women with suspected PE is limited as it cannot identify those at low risk of developing adverse outcomes.
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Using two-dimensional electronic spectroscopy, we measured the Qx to Qy transfer dynamics of the chlorophyll a (Chl a) manifold in the photosystem II (PSII) monomeric core complex from Arabidopsis thaliana. A PSII monomeric core consists of 35 Chls a and no Chl b, thus allowing for a clear window to study Chl a Qx dynamics in a large pigment-protein complex. Initial excitation in the Qx band results in a transfer to the Qy band in less than 60 fs. Upon the ultrafast transfer, regardless of the excitation frequency within the Qx band, the quasi-transient absorption spectra are very similar. This observation indicates that Chl a's Qx to Qy transfer is not frequency selective. Using a simple model, we determined that this is not due to the lifetime broadening of the ultrafast transfer but predominantly due to a lack of correlation between the PSII core complex's Chl a Qx and Qy bands. We suggest the origin to be the intrinsic loss of correlation during the Qx to Qy internal conversion as observed in previous studies of molecular Chl a dissolved in solvents.
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Clorofila , Complexo de Proteína do Fotossistema II , Clorofila/química , Clorofila A , Eletrônica , Complexos de Proteínas Captadores de Luz , Complexo de Proteína do Fotossistema II/química , Análise Espectral/métodosRESUMO
Energy equilibration in light-harvesting antenna systems normally occurs before energy is transferred to a reaction center. The equilibration mechanism is a characteristic of the excitation energy transfer (EET) network of the antenna. Characterizing this network is crucial in understanding the first step of photosynthesis. We present our phenomenology-based analysis procedure and results in obtaining the excitonic energy levels, spectral linewidths, and transfer-rate matrix of Light-Harvesting Complex II directly from its 2D electronic spectra recorded at 77 K with waiting times between 100 fs to 100 ps. Due to the restriction of the models and complexity of the system, a unique EET network cannot be constructed. Nevertheless, a recurring pattern of energy transfer with very similar overall time scales between spectral components (excitons) is consistently obtained. The models identify a "bottleneck" state in the 664-668 nm region although with a relatively shorter lifetime (â¼4-6 ps) of this state compared to previous studies. The model also determines three terminal exciton states at 675, 677-678, and 680-681 nm that are weakly coupled to each other. The excitation energy equilibration between the three termini is found to be independent of the initial excitation conditions, which is a crucial design for the light-harvesting complexes to ensure the energy flow under different light conditions and avoid excitation trapping. We proposed two EET schemes with tentative pigment assignments based on the interpretation of the modeling results together with previous structure-based calculations and spectroscopic observables.
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Health sector decentralization has created an urgent need to strengthen public health management capacity in many countries throughout the developing world. This article describes the establishment of a national management training network in Vietnam that used Project-Based Learning to strengthen management competencies of HIV program workers and linked training to measurable improvement in HIV/AIDS public health program outcomes. Skills were taught using a combination of classroom learning and mentored fieldwork. From 2005 to 2015, 827 HIV/AIDS program managers were trained with this method throughout Vietnam by trainers in 3 regional training centers. A total of 218 applied learning projects were carried out by trainees during this period; 132 resulted in measurable improvements in HIV/AIDS program outputs, and 86 produced well-organized plans for implementing, monitoring, and evaluating HIV/AIDS intervention strategies. Vietnam's management training network represents an important advancement in public health workforce development that helps prepare workers for new roles and responsibilities in a decentralized health system.
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Fortalecimento Institucional/métodos , Atenção à Saúde/métodos , Saúde Pública/normas , Fortalecimento Institucional/organização & administração , Fortalecimento Institucional/tendências , Atenção à Saúde/tendências , Programas Governamentais , Humanos , Política , Saúde Pública/estatística & dados numéricos , Melhoria de Qualidade/tendências , VietnãRESUMO
OBJECTIVE: To evaluate the performance of maternal factors, biophysical and biochemical markers at 11-13 + 6 weeks' gestation in the prediction of gestational diabetes mellitus with or without large for gestational age (GDM ± LGA) fetus and great obstetrical syndromes (GOS) among singleton pregnancy following in-vitro fertilisation (IVF)/embryo transfer (ET). MATERIALS AND METHODS: A prospective cohort study was conducted between December 2017 and January 2020 including patients who underwent IVF/ET. Maternal mean arterial pressure (MAP), ultrasound markers including placental volume, vascularisation index (VI), flow index (FI) and vascularisation flow index (VFI), mean uterine artery pulsatility index (mUtPI) and biochemical markers including placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt-1) were measured at 11-13 + 6 weeks' gestation. Logistic regression analysis was performed to determine the significant predictors of complications. RESULTS: Among 123 included pregnancies, 38 (30.9%) had GDM ± LGA fetus and 28 (22.8%) had GOS. The median maternal height and body mass index were significantly higher in women with GDM ± LGA fetus. Multivariate logistic regression analysis demonstrated that in the prediction of GDM ± LGA fetus and GOS, there were significant independent contributions from FI MoM (area under curve (AUROC) of 0.610, 95% CI 0.492-0.727; p = 0.062) and MAP MoM (AUROC of 0.645, 95% CI 0.510-0.779; p = 0.026), respectively. CONCLUSION: FI and MAP are independent predictors for GDM ± LGA fetus and GOS, respectively. However, they have low predictive value. There is a need to identify more specific novel biomarkers in differentiating IVF/ET pregnancies that are at a higher risk of developing complications.
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Diabetes Gestacional , Placenta , Primeiro Trimestre da Gravidez , Ultrassonografia Pré-Natal , Humanos , Feminino , Gravidez , Adulto , Estudos Prospectivos , Placenta/diagnóstico por imagem , Placenta/irrigação sanguínea , Ultrassonografia Pré-Natal/métodos , Fertilização in vitro , Biomarcadores/sangue , Macrossomia Fetal/diagnóstico por imagem , Fator de Crescimento Placentário/sangue , Valor Preditivo dos Testes , Idade Gestacional , Transferência Embrionária , Artéria Uterina/diagnóstico por imagem , Complicações na Gravidez/diagnóstico por imagem , Técnicas de Reprodução AssistidaRESUMO
OBJECTIVES: To compare the temporal changes in mean arterial pressure (MAP), uterine artery pulsatility index (UtA-PI), placental growth factor (PlGF), and soluble fms-like tyrosine kinase-1 (sFlt-1) across gestation between assisted reproductive technology (ART) pregnancies complicated with great obstetrical syndromes (GOS) or gestational diabetes (GDM) ± large-for-gestational-age (LGA) fetus, and uncomplicated ART pregnancies. METHODS: This was a prospective longitudinal study of 143 women with singleton pregnancies who conceived through ART at the Department of Obstetrics and Gynecology, Prince of Wales Hospital, the Chinese University of Hong Kong, Hong Kong SAR between December 2017 and January 2020. The participants were followed up at 6-6+3, 11-13+6, 20-24+6, 30-34+6, and 35-37+6 weeks for the measurement of MAP, UtA-PI, PlGF, and sFlt-1. A linear mixed-effects analysis was performed to compare the biomarkers in the GOS, GDM ± LGA, and uncomplicated groups across gestation. RESULTS: Thirty-three (23.1%) and fifty-five (31.5%) women were diagnosed with GOS and GDM ± LGA, respectively. The GOS group had higher estimated marginal mean log10 MAP mulitples of the median (MoM) across gestation, compared with the uncomplicated group (0.00771 vs -0.02022; P < 0.001), when adjusting for clinical visits and days of embryo transfer. The absolute mean log10 MAP MoM in the GOS group was found to be significantly higher than that of the uncomplicated group at all clinical visits from 6 weeks onwards. Furthermore, the estimated marginal mean log10 PlGF MoM was significantly lower in the GOS group across gestation, compared with the uncomplicated group (-0.04226 vs 0.05566; P = 0.010). The significant difference in log10 PlGF MoM was observed from 11-13+6 to 30-34+6 week of gestation (P < 0.05). However, no significant differences in the estimated marginal means of log10 UtA-PI MoM and log10 sFlt-1 MoM between GOS and uncomplicated groups were observed. GDM ± LGA group had a lower estimated marginal mean log10 PlGF MoM throughout pregnancy compared with the uncomplicated group (-0.01536 vs 0.05572; P = 0.032). In the individual visit analysis, the significant difference was observed at the 20-24+6 and 35-37+6 weeks visits (P < 0.05). There were no significant differences in estimated marginal mean log10 MoM of MAP, UtA-PI, and sFlt-1 between GDM ± LGA and uncomplicated groups during pregnancy. CONCLUSION: Our study has revealed that among pregnancies conceived through ART, GOS is associated with higher MAP and lower PlGF from early gestation until late third trimester, while GDM ± LGA is associated with lower PlGF during the second half of pregnancy. The same degree of differences in MAP and PlGF persists from early until late gestation in the GOS group and these findings highlight the importance of early screening during the first trimester to identify women who are at risk for developing GOS following ART procedures. Lastly, the potential of PlGF in predicting the development of GDM from the second trimester of pregnancy requires further investigation.
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INTRODUCTION: Pre-eclampsia (PE) affects about 5% of Chinese pregnant women and is a major cause of maternal and perinatal morbidity and mortality. The first trimester screening model developed by the Fetal Medicine Foundation, which uses the Bayes theorem to combine maternal characteristics and medical history together with measurements of biomarkers, has been proven to be effective and has superior screening performance to that of the traditional risk factor-based approach for the prediction of PE. Prophylactic use of low-dose aspirin in women at risk for PE has resulted in a lower incidence of preterm-PE. However, there is no consensus on the preferred aspirin dosage for the prevention of preterm-PE. Evidence has also suggested that metformin has the potential benefit in preventing PE in pregnant women who are at high risk of the disorder. METHOD AND ANALYSIS: We present a protocol (V.2.0, date 17 March 2022) for the AVERT trial, which is a multicentre, double-blinded, 3-arm randomised controlled trial (RCT) that uses an effective PE screening programme to explore the optimal dosage of aspirin and the role of metformin for the prevention of PE among high-risk pregnant women in China. We intend to recruit 66 000 singleton pregnancies without treatment of low-dose aspirin and metformin at 11-13 weeks' gestation and all eligible women attending for their first trimester routine scan will be invited to undergo screening for preterm-PE by the combination of maternal factors, mean arterial pressure and placental growth factor. Women found to be at high risk of developing preterm-PE will be invited to take part in the RCT. This study will compare the incidence of preterm-PE with delivery at <37 weeks' gestation, as the primary outcome, of three different interventional groups: (1) aspirin 75 mg daily, (2) aspirin 150 mg daily and (3) aspirin 75 mg with metformin 1.5 g daily. 957 participants per treatment group are required to detect a significant difference of 59% in the reduction of the incidence of preterm-PE with 80% power and type I error of 5%. Pregnancy and neonatal outcomes will be collected and analysed. ETHICS AND DISSEMINATION: Ethical approval for the study was obtained from the Joint Chinese University of Hong Kong-New Territories East Cluster Clinical Research Ethics Committee (CREC Ref. No. 2021.406) in Hong Kong and the Ethics Committee of each participating hospital in Mainland China. The study is registered at ClinicalTrials.gov. The results of the AVERT trial will be disseminated at international academic conferences and published in high-impact factor journals. TRIAL REGISTRATION NUMBER: NCT05580523.
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Metformina , Pré-Eclâmpsia , Gravidez , Feminino , Recém-Nascido , Humanos , Aspirina , Pré-Eclâmpsia/epidemiologia , Método Duplo-Cego , China , Biomarcadores , Ensaios Clínicos Controlados Aleatórios como Assunto , Estudos Multicêntricos como AssuntoRESUMO
Two-dimensional electronic spectroscopy (2DES) has proven to be a highly effective technique in studying the properties of excited states and the process of excitation energy transfer in complex molecular assemblies, particularly in biological light-harvesting systems. However, the accurate simulation of 2DES for large systems still poses a challenge because of the heavy computational demands it entails. In an effort to overcome this limitation, we devised a coarse-grained 2DES method. This method encompasses the treatment of the entire system by dividing it into distinct weakly coupled segments, which are assumed to communicate predominantly through incoherent exciton transfer. We first demonstrate the efficiency of this method through simulation on a model dimer system, which demonstrates a marked improvement in calculation efficiency, with results that exhibit good concordance with reference spectra calculated with less approximate methods. Additionally, the application of this method to the light-harvesting antenna 2 (LH2) complex of purple bacteria showcases its advantages, accuracy, and limitations. Furthermore, simulating the anisotropy decay in LH2 induced by energy transfer and its comparison with experiments confirm that the method is capable of accurately describing dynamical processes in a biologically relevant system. This method presented lends itself to an extension that accounts for the effect of intrasegment relaxation processes on the 2DES spectra, which for computational efficiency are ignored in the implementation reported here. It is envisioned that the method will be employed in the future to accurately and efficiently calculate 2D spectra of more extensive systems, such as photosynthetic supercomplexes.
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OBJECTIVES: To evaluate the performance of an artificial intelligence (AI) and machine learning (ML) model for first-trimester screening for pre-eclampsia in a large Asian population. METHODS: This was a secondary analysis of a multicenter prospective cohort study in 10 935 participants with singleton pregnancies attending for routine pregnancy care at 11-13+6 weeks of gestation in seven regions in Asia between December 2016 and June 2018. We applied the AI+ML model for the first-trimester prediction of preterm pre-eclampsia (<37 weeks), term pre-eclampsia (≥37 weeks), and any pre-eclampsia, which was derived and tested in a cohort of pregnant participants in the UK (Model 1). This model comprises maternal factors with measurements of mean arterial pressure, uterine artery pulsatility index, and serum placental growth factor (PlGF). The model was further retrained with adjustments for analyzers used for biochemical testing (Model 2). Discrimination was assessed by area under the receiver operating characteristic curve (AUC). The Delong test was used to compare the AUC of Model 1, Model 2, and the Fetal Medicine Foundation (FMF) competing risk model. RESULTS: The predictive performance of Model 1 was significantly lower than that of the FMF competing risk model in the prediction of preterm pre-eclampsia (0.82, 95% confidence interval [CI] 0.77-0.87 vs. 0.86, 95% CI 0.811-0.91, P = 0.019), term pre-eclampsia (0.75, 95% CI 0.71-0.80 vs. 0.79, 95% CI 0.75-0.83, P = 0.006), and any pre-eclampsia (0.78, 95% CI 0.74-0.81 vs. 0.82, 95% CI 0.79-0.84, P < 0.001). Following the retraining of the data with adjustments for the PlGF analyzers, the performance of Model 2 for predicting preterm pre-eclampsia, term pre-eclampsia, and any pre-eclampsia was improved with the AUC values increased to 0.84 (95% CI 0.80-0.89), 0.77 (95% CI 0.73-0.81), and 0.80 (95% CI 0.76-0.83), respectively. There were no differences in AUCs between Model 2 and the FMF competing risk model in the prediction of preterm pre-eclampsia (P = 0.135) and term pre-eclampsia (P = 0.084). However, Model 2 was inferior to the FMF competing risk model in predicting any pre-eclampsia (P = 0.024). CONCLUSION: This study has demonstrated that following adjustment for the biochemical marker analyzers, the predictive performance of the AI+ML prediction model for pre-eclampsia in the first trimester was comparable to that of the FMF competing risk model in an Asian population.
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Photosystem II (PSII) is an integral part of the photosynthesis machinery, in which several light-harvesting complexes rely on inter-complex excitonic energy transfer (EET) processes to channel energy to the reaction center. In this paper, we report on a direct observation of the inter-complex EET in a minimal PSII supercomplex from plants, containing the trimeric light-harvesting complex II (LHCII), the monomeric light-harvesting complex CP26, and the monomeric PSII core complex. Using two-dimensional (2D) electronic spectroscopy, we measure an inter-complex EET timescale of 50 picoseconds for excitations from the LHCII-CP26 peripheral antenna to the PSII core. The 2D electronic spectra also reveal that the transfer timescale is nearly constant over the pump spectrum of 600 to 700 nanometers. Structure-based calculations reveal the contribution of each antenna complex to the measured inter-complex EET time. These results provide a step in elucidating the full inter-complex energy transfer network of the PSII machinery.
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Clorofila , Complexo de Proteína do Fotossistema II , Complexo de Proteína do Fotossistema II/química , Clorofila/metabolismo , Fotossíntese , Tilacoides/metabolismo , Plantas/metabolismo , Transferência de EnergiaRESUMO
Hypertensive disorders of pregnancy (HDP) are the most common causes of maternal and perinatal morbidity and mortality. They are responsible for 16% of maternal deaths in high-income countries and approximately 25% in low- and middle-income countries. The impact of HDP can be lifelong as they are a recognized risk factor for future cardiovascular disease. During pregnancy, the cardiovascular system undergoes significant adaptive changes that ensure adequate uteroplacental blood flow and exchange of oxygen and nutrients to nurture and accommodate the developing fetus. Failure to achieve normal cardiovascular adaptation is associated with the development of HDP. Hemodynamic alterations in women with a history of HDP can persist for years and predispose to long-term cardiovascular morbidity and mortality. Therefore, pregnancy and the postpartum period are an opportunity to identify women with underlying, often unrecognized, cardiovascular risk factors. It is important to develop strategies with lifestyle and therapeutic interventions to reduce the risk of future cardiovascular disease in those who have a history of HDP.
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Doenças Cardiovasculares , Sistema Cardiovascular , Hipertensão Induzida pela Gravidez , Pré-Eclâmpsia , Gravidez , Feminino , Humanos , Hipertensão Induzida pela Gravidez/epidemiologia , Doenças Cardiovasculares/epidemiologia , Doenças Cardiovasculares/etiologia , Fatores de RiscoRESUMO
We measure the ultrafast spectral diffusion, vibronic dynamics, and energy relaxation of a CdSe colloidal quantum wells (CQWs) system at room temperature using two-dimensional electronic spectroscopy (2DES). The energy relaxation of light-hole (LH) excitons and hot carriers to heavy-hole (HH) excitons is resolved with a time scale of â¼210 fs. We observe the equilibration dynamics between the spectroscopically accessible HH excitonic state and a dark state with a time scale of â¼160 fs. We use the center line slope analysis to quantify the spectral diffusion dynamics in HH excitons, which contains an apparent sub-200 fs decay together with oscillatory features resolved at 4 and 25 meV. These observations can be explained by the coupling to various lattice phonon modes. We further perform quantum calculations that can replicate and explain the observed dynamics. The 4 meV mode is observed to be in the near-critically damped regime and may be mediating the transition between the bright and dark HH excitons. These findings show that 2DES can provide a comprehensive and detailed characterization of the ultrafast spectral properties in CQWs and similar nanomaterials.
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Workplace violence is an increasing public health concern around the world. In Vietnam, attacks on healthcare workers have become a huge issue in recent years. Our study aims to shed more light on the issue and look at what variables affect acts of violence toward healthcare workers. We conducted this cross-sectional study by surveying 550 medical students from 3 universities in Vietnam. Following this survey on SurveyMonkey's platform (surveymonkey.com), the participants were suggested to invite their associates who met the selection criteria to join in this online survey. The structured questionnaire included demographics and details on the violence. There were 90.5% of respondents were medical students, the mean age was 23.3, and verbal abuse had a prevalence rate of 29.3%. Women respondents are less likely to suffer from violent experiences than men (OR = 0.48, 95% CI = 0.28-0.84), and those specializing in nurse and technician also faced a lower rate of acts of aggression (physical violence: OR = 0.35; 95% CI = 0.19-0.63, sexual harassment: OR = 0.36; 95% CI = 0.15-0.87, and any type of violence: OR = 0.55, 95% CI = 0.37-0.82). Medical students working in Ho Chi Minh City (OR = 0.55; 95% CI = 0.34-0.89), and other regions (OR = 0.40; 95% CI = 0.19-0.85) were significantly less likely to face verbal abuse than those working in Hanoi. The workplace culture needs to be changed to make sure that people feel comfortable reporting, especially those who are younger. Protecting medical students also ensures patient safety since victims of assault in the workplace can have severe aftereffects affecting their ability to provide good patient care. Hence, policies need to be implemented at both the government and hospital administration levels to keep health workers safe.
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Estudantes de Medicina , Violência no Trabalho , Masculino , Humanos , Feminino , Adulto Jovem , Adulto , Estudos Transversais , Hospitais , Local de TrabalhoRESUMO
We measure the two-dimensional electronic spectra of the LHCII(M)-CP29-CP24 complex in photosystem II (PSII) and provide the first study of the ultrafast excitation energy transfer (EET) processes of an asymmetric and native light-harvesting assembly of the antenna of PSII. With comparisons to LHCII, we observe faster energy equilibrations in the intermediate levels of the LHCII(M)-CP29-CP24 complex at 662 and 670 nm. Notably, the putative "bottleneck" states in LHCII exhibit faster effective dynamics in the LHCII(M)-CP24-CP29 complex, with the average lifetime shortening from 2.5 ps in LHCII to 1.2 ps in the bigger assembly. The observations are supported by high-level structure-based calculations, and the accelerated dynamics can be attributed to the structural change of LHCII(M) in the bigger complex. This study shows that the biological functioning structures of the complexes are important to understand the overall EET dynamics of the PSII supercomplex.
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Complexos de Proteínas Captadores de Luz , Complexo de Proteína do Fotossistema II , Transferência de Energia , Complexos de Proteínas Captadores de Luz/química , Complexo de Proteína do Fotossistema II/metabolismo , Plantas/metabolismo , TilacoidesRESUMO
We perform two-dimensional electronic spectroscopy on chlorophyll (Chl) a and b molecules in aprotic solvents of different Lewis basicity. By analyzing the ultrafast spectral diffusion dynamics of the Qy transition, we show that a certain timescale of the spectral diffusion dynamics is affected by the solvents' Lewis basicity. Control experiments with Chlorin-e6-a Chl molecule analog-and ab initio time-dependent density functional theory calculations confirm that we are directly probing the fluctuation dynamics of the dative bond between the solvent's lone pair and the Mg2+ center in Chls that is responsible for the Lewis basicity. The observation is indicative of dative bond length and angular fluctuations with timescales ranging between â¼30 and 150 ps and the dative bond-strength-dependent perturbation on the Qy transition frequency of Chls.
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In the heterobiaryl cross-coupling reaction between aryl halides (Ar-X) and N-methylpyrrole (N-MP) catalyzed by rhodamine 6G (Rh6G+) under irradiation with visible light, a highly active and long-lived (millisecond time range) rhodamine 6G radical (Rh6Gâ¢) is formed upon electron transfer from N,N-diisopropylethylamine (DIPEA) to Rh6G+. In this study, we utilized steady-state and time-resolved spectroscopy techniques to demonstrate the existence of another electron-transfer process occurring from the relatively electron-rich N-MP to photoexcited Rh6G+ that was neglected in the previous reports. In this case, the radical Rh6G⢠formed is short-lived and undergoes rapid recombination (nanosecond time-range), rendering it ineffective in reducing Ar-X to aryl radicals Ar⢠that can subsequently be trapped by N-MP. This is further demonstrated via two model reactions involving 4'-bromoacetophenone and 1,3,5-tribromobenzene with insignificant product yields after visible-light irradiation in the absence of DIPEA. The unproductive quenching of photoexcited Rh6G+ by N-MP leads to a lower concentration of photocatalyst available for competitive charge transfer with DIPEA and hence decreases the efficiency of the cross-coupling reaction.
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Elétrons , Pirróis , RodaminasRESUMO
Bryopsis corticulans is a marine green macroalga adapted to the intertidal environment. It possesses siphonaxanthin-binding light-harvesting complexes of photosystem II (LHCII) with spectroscopic properties markedly different from the LHCII in plants. By applying a phenomenological fitting procedure to the two-dimensional electronic spectra of the LHCII from B. corticulans measured at 77 K, we can extract information about the excitonic states and energy-transfer processes. The fitting method results in well-converged parameters, including excitonic energy levels with their respective transition dipole moments, spectral widths, energy-transfer rates, and coupling properties. The 2D spectra simulated from the fitted parameters concur very well with the experimental data, showing the robustness of the fitting method. An excitonic energy-transfer scheme can be constructed from the fitting parameters. It shows the rapid energy transfer from chlorophylls (Chls) b to a at subpicosecond time scales and a long-lived state in the Chl b region at around 659 nm. Three weakly connected terminal states are resolved at 671, 675, and 677 nm. The lowest state is higher in energy than that in plant LHCII, which is probably because of the fewer number of Chls a in a B. corticulans LHCII monomer. Modeling based on existing Hamiltonians for the plant LHCII structure with two Chls a switched to Chls b suggests several possible Chl a-b replacements in comparison with those of plant LHCII. The adaptive changes result in a slower energy equilibration in the complex, revealed by the longer relaxation times of several exciton states compared to those of plant LHCII. The strength of our phenomenological fitting method for obtaining excitonic energy levels and energy-transfer network is put to the test in systems such as B. corticulans LHCII, where prior knowledge on exact assignment and spatial locations of pigments are lacking.
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Clorófitas , Complexos de Proteínas Captadores de Luz , Clorofila , Clorófitas/metabolismo , Transferência de Energia , Complexos de Proteínas Captadores de Luz/metabolismo , Complexo de Proteína do Fotossistema II/metabolismo , Tilacoides/metabolismoRESUMO
We simulated two-dimensional electronic spectra (2DES) of the chlorophyll a manifold of light-harvesting complex II (LHCII) at various temperatures (77, 110, 150, 190, 230, 273, and 293â K) using the hierarchical equations of the motion-phase matching approach. We confirm the main excitation energy transfer pathways assignments within the chlorophyll a manifold of LHCII measured in a recent work (J. Phys. Chem. B 2019, 123, 6765-6775). The calculated transfer rates are also in general agreement with the measured rates. We also provided theoretical confirmation for the experimental assignments, as uphill and downhill energy transfer processes, of 2D spectral features that were reported in recent experimental reports. These temperature-dependent features were also ascertained to follow the detailed-balance principle.