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The transfer of an oxygen atom from carbon dioxide (CO2) to a transition metal cation in the gas phase offers atomic level insights into single-atom catalysis for CO2 activation. Given that these reactions often involve open-shell transition metals, they may proceed through intersystem crossing between different spin manifolds. However, a definitive understanding of such spin-forbidden reaction requires dynamical calculations on multiple global potential energy surfaces (PESs) coupled by spin-orbit couplings. In this work, we report global PESs and spin-orbit couplings for three low-lying spin (quintet, triplet, and singlet) states for the reaction between the niobium cation (Nb+) and CO2, which are used to investigate the nonadiabatic reaction dynamics and kinetics. Comparison with experimental data of kinetics and collision dynamics shows satisfactory agreement. This reaction is found to be very similar to that between Ta+ + CO2. Specifically, our theoretical findings suggest that the rate-limiting step in this reaction is intersystem crossing, rather than potential barriers.
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Manganese complexes exhibit a rich redox chemistry, usually accompanied by structural reorganization during the redox processes often followed by ligand dissociation or association. The push-pull ligand 2,6-diguanidylpyridine (dgpy) stabilizes manganese in the oxidation states +II, +III, and + IV in the complexes [Mn(dgpy)2]n+ (n = 2-4) without change in the coordination sphere in the condensed phase [Heinze et al., Inorganic Chemistry, 2022, 61, 14616]. In the condensed phase, the manganese(IV) complex is a very strong oxidant. In the present work, we investigate the stability and redox activity of the MnIV complex and its counterion (PF6-) adducts in the gas phase, using two modified 3D Paul ion trap mass spectrometers. Six different cationic species of the type [Mnx(dgpy)2(PF6)y]n+ (x = II, III, IV, y = 0-3, n = 1-3) could be observed for the three oxidation states MnIV, MnIII, and MnII, of which one observed complex also contains a reduced dgpy ligand. MnII species showed the highest relative stability in collision induced dissociation and UV/vis photo dissociation experiments. The lowest stability is observed in the presence of one or more counterions, which correlates to a lower total charge n+. Gas phase UV/vis spectra show similar features as the condensed phase spectra only differing in relative band intensities. The strongly oxidizing MnIV complex reacts with triethylamine (NEt3) in the gas phase to give MnIII, while MnIII species show little reactivity toward NEt3.
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The activation of carbon dioxide (CO2) by a transition-metal cation in the gas phase is a unique model system for understanding single-atom catalysis. The mechanism of such reactions is often attributed to a "two-state reactivity" model in which the high-energy barrier of a spin state correlating with ground-state reactants is avoided by intersystem crossing (ISC) to a different spin state with a lower barrier. However, such a "spin-forbidden" mechanism, along with the corresponding dynamics, has seldom been rigorously examined theoretically, due to the lack of global potential energy surfaces (PESs). In this work, we report full-dimensional PESs of the lowest-lying quintet, triplet, and singlet states of the TaCO2+ system, machine-learned from first-principles data. These PESs and the corresponding spin-orbit couplings enable us to provide an extensive theoretical characterization of the dynamics and kinetics of the reaction between the tantalum cation (Ta+) and CO2, which have recently been investigated experimentally at high collision energies using crossed beams and velocity map imaging, as well as at thermal energies using a selected-ion flow tube apparatus. The multistate quasi-classical trajectory simulations with surface hopping reproduce most of the measured product translational and angular distributions, shedding valuable light on the nonadiabatic reaction dynamics. The calculated rate coefficients from 200 to 600 K are also in good agreement with the latest experimental measurements. More importantly, these calculations revealed that the reaction is controlled by intersystem crossing, rather than potential barriers.
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The controlled activation of methane has drawn significant attention throughout various disciplines over the last few decades. In gas-phase experiments, the use of model systems with reduced complexity compared to condensed-phase catalytic systems allows us to investigate the intrinsic reactivity of elementary reactions down to the atomic level. Methane is rather inert in chemical reactions, as the weakening or cleavage of a C-H bond is required to make use of methane as C1-building block. The simplest model system for transition-metal-based catalysts is a mono-atomic metal ion. Only a few atomic transition-metal cations activate methane at room temperature. One of the most efficient elements is tantalum, which forms a carbene and releases molecular hydrogen in the reaction with methane: Ta+ + CH4 â TaCH2+ + H2. The reaction takes place at room temperature due to efficient intersystem crossing from the quintet to the triplet surface, i.e., from the electronic ground state of the tantalum cation to the triplet ground state of the tantalum carbene. This multi-state reactivity is often seen for reactions involving transition-metal centres, but leads to their theoretical treatment being a challenge even today. Chemical reactions, or to be precise reactive collisions, are dynamic processes making their description even more of a challenge to experiment and theory alike. Experimental energy- and angle-differential cross sections allow us to probe the rearrangement of atoms during a reactive collision. By interpreting the scattering signatures, we gain insight into the atomistic mechanisms and can move beyond stationary descriptions. Here, we present a study combining collision energy dependent experimentally measured differential cross sections with ab initio calculations of the minimum energy pathway. Product ion velocity distributions were recorded using our crossed-beam velocity map imaging experiment dedicated to studying transition-metal ion molecule reactions. TaCH2+ velocity distributions reveal a significant degree of indirect dynamics. However, the scattering distributions also show signatures of rebound dynamics. We compare the present results to the oxygen transfer reaction between Ta+ and carbon dioxide, which we recently studied.
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The reactions of Ta+ and Nb+ with CO2 proceed only by a highly efficient oxygen atom transfer reaction to the respective oxide at room temperature in the gas phase. Although the product spin states are not determined, thermochemistry dictates that they must be different from ground state quintet Ta+ and Nb+, implying that intersystem crossing (ISC) has occurred. Recent reactive scattering experiments found dominant indirect dynamics for the reaction with Ta+ hinting at a bottleneck along the reaction path. The question on the nature of the bottleneck, whether it involves a crossing point or a transition state, could not be finally answered because theory located both close to each other. Here, we aim at shedding further light onto the impact of intersystem crossing on the reaction dynamics and ultimately the reactivity of transition metal ion reactions in the gas phase. We employ a combination of thermal kinetics for Ta+ and Nb+ with CO2 using a selected-ion flow tube (SIFT) apparatus and differential scattering cross sections for Nb+ + CO2 from crossed-beam velocity map imaging. The reaction with niobium again shows dominant indirect dynamics and in general very similar dynamics compared to Ta+ + CO2. At thermal energies, both reactions show sub-collisional rate constants with small negative temperature dependencies. Experiments are complemented by high level quantum chemical calculations of the minimum energy pathway. Statistical modelling well-reproduces the experimental thermal rate constants, and suggests that the Nb+ reaction is rate-limited by the intersystem crossing at thermal energies.
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Objectives: Identifying the key factors associated with vaccine hesitancy remains a challenge as has been highlighted throughout the COVID-19 vaccine roll out and pandemic. The aim of this study was to determine characteristics associated with vaccine safety and compare perceived safety by vaccine. Our hypothesis is that vaccine safety perception will vary by vaccine with COVID-19 as ranked lowest for safety. Study design: Cross sectional. Methods: A statewide sample (n = 1024) responded to an online 28-point questionnaire via anonymous linked invitation. Results: Among the eight vaccines assessed, COVID-19 had the lowest perceived safety (53.13%) followed by human papillomavirus HPV (63.38%). A binomial logistic regression assessed COVID-19 vaccine safety beliefs (safe v not safe) finding age, political orientation, and perceived safety of certain vaccines as statistically significant. As age increased by year, vaccine safety beliefs increased. Persons who identified as conservative demonstrated less belief in vaccine safety than all other groups. Among persons who did not perceive the COVID-19 vaccine as safe, 65.8% believed chicken pox was safe, 63.3% and 61.1% perceived hepatitis A& B were safe. Conclusions: These findings demonstrate that vaccine safety beliefs differ by vaccine and that persons who do not believe in the safety of the COVID-19 are not exclusively against all vaccines. Understanding factors that increase vaccine safety by vaccine could assist in developing an intervention which could increase belief in safety for all vaccines.
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The COVID-19 pandemic has caused social and economic disruption worldwide and spurred numerous mitigation strategies, including state investments in training a large contact tracing and case investigation workforce. A team at the University of Alaska Anchorage evaluated implementation of the COVID-19 contact tracing and case investigation program of the State of Alaska Department of Health and Social Services, Division of Public Health, Section of Public Health Nursing. As part of that evaluation, the team used COVIDTracer, a spreadsheet modeling tool. COVIDTracer generated projections of COVID-19 case counts that informed estimates of workforce needs and case prioritization strategies. Case count projections approximated the reported epidemiologic curve with a median 7% difference in the first month. The accuracy of case count predictions declined after 1 month with a median difference of 80% in the second month. COVIDTracer inputs included previous case counts, the average length of time for telephone calls to cases and outreach to identified contacts, and the average number of contacts per case. As each variable increased, so too did estimated workforce needs. Decreasing the average time from exposure to outreach from 10 to 5 days reduced case counts estimated by COVIDTracer by approximately 93% during a 5-month period. COVIDTracer estimates informed Alaska's workforce planning and decisions about prioritizing case investigation during the pandemic. Lessons learned included the importance of being able to rapidly scale up and scale down workforce to adjust to a dynamic crisis and the limitations of prediction modeling (eg, that COVIDTracer was accurate for only about 1 month into the future). These findings may be useful for future pandemic preparedness planning and other public health emergency response activities.
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COVID-19 , Humanos , Alaska/epidemiologia , COVID-19/epidemiologia , Saúde Pública , Pandemias , Mão de Obra em Saúde , Recursos Humanos , Busca de ComunicanteRESUMO
BACKGROUND: Vaccine hesitancy (VH) is a major public health problem which includes not only concerns about vaccine, but often includes beliefs not aligned with evidence. The etiology of VH is complicate, including genuine concerns about vaccine safety to beliefs in disproven or unsubstantiated theories. Understanding VH includes determining the factors associated with people most likely to be susceptible. OBJECTIVES: To identify characteristics of persons more likely to have VH based on perceived vaccine safety. DESIGN: We conducted a cross sectional, targeted online survey of 1,024 respondents. METHODS: The survey collected data on demographics and vaccine beliefs. A seven-question VH scale was created based on an extensive literature review. When measured, this scale had high internal validity based on Cronbach's Alpha (α = 0.80, 95% CI, 0.79, 0.82) and provided a continuous measurement to understand the VH degree. RESULTS: Persons reporting a conservative political ideology had the highest VH score ([Formula: see text] = 15.0), followed by other ([Formula: see text] =12.7), moderate ([Formula: see text] =9.29), and liberal ([Formula: see text] =6.72). Education level was another strong indicator of VH, decreasing from the highest score of high school graduates ( [Formula: see text] = 13.2) to graduate degree holders ([Formula: see text] = 9.22). CONCLUSION: The more conservative a person's political ideology, the higher the VHS. We asked for ideology, rather than political party, although they are related, they are not the same. Ideology influences more domains than voting patterns. Higher educational attainment shows a protective effect against VH. These findings have direct implication for public health interventions, new interventions should be designed to be more accessible for persons with less formal education and more amenable to persons who hold a more conservative ideology.
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Hesitação Vacinal , Vacinas , Humanos , Alaska , Estudos Transversais , Coleta de Dados , VacinaçãoRESUMO
We conducted an online survey of Alaskan adults between May and June, 2022 to identify factors associated with vaccine hesitancy. Of the 948 respondents, approximately 80% reported having received a COVID-19 vaccine. The factors significantly associated with ever receiving COVID-19 vaccine include perceived risk of harm if not vaccinated (PRH), the vaccination status of the respondent's social network (SNW), gender, and education. For each point increase in PRH score, there was more than three times the odds of having ever been vaccinated (OR = 3.42, p < 0.001); and for every point increase in SNW score, there was more than two times the odds of having ever been vaccinated (OR = 2.15, p < 0.001). Males had more than four times the odds of having ever been vaccinated compared to females (OR = 4.55, p < 0.001). Those with a college degree (OR = 2.80, p < 0.05) had greater odds of ever being vaccinated compared to their counterparts. Findings from this sample suggest that, among Alaskans, ever receiving a COVID-19 vaccine is associated with having a majority of their close social networks who have received COVID-19 vaccine and perceiving that not obtaining a COVID-19 vaccine can pose greater risk of harm to themselves than not getting vaccinated. Practical implications of these findings are provided.
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Vacinas contra COVID-19 , COVID-19 , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Alaska , COVID-19/prevenção & controle , Vacinas contra COVID-19/administração & dosagem , Estudos Transversais , Fatores Socioeconômicos , Hesitação Vacinal/estatística & dados numéricos , Pesquisas sobre Atenção à SaúdeRESUMO
Introduction: Adaptive learning opportunities and individualized, timely feedback are considered to be effective support measures for students' writing in educational contexts. However, the extensive time and expertise required to analyze numerous drafts of student writing pose a barrier to teaching. Automated writing evaluation (AWE) tools can be used for individual feedback based on advances in Artificial Intelligence (AI) technology. A number of primary (quasi-)experimental studies have investigated the effect of AWE feedback on students' writing performance. Methods: This paper provides a meta-analysis of the effectiveness of AWE feedback tools. The literature search yielded 4,462 entries, of which 20 studies (k = 84; N = 2, 828) met the pre-specified inclusion criteria. A moderator analysis investigated the impact of the characteristics of the learner, the intervention, and the outcome measures. Results: Overall, results based on a three-level model with random effects show a medium effect (g = 0.55) of automated feedback on students' writing performance. However, the significant heterogeneity in the data indicates that the use of automated feedback tools cannot be understood as a single consistent form of intervention. Even though for some of the moderators we found substantial differences in effect sizes, none of the subgroup comparisons were statistically significant. Discussion: We discuss these findings in light of automated feedback use in educational practice and give recommendations for future research.
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OBJECTIVES: Early Childhood Caries (ECC) can negatively impact the lives of young children, despite being preventable. The purpose of this study was to utilize available data in Alaska to describe changes in parent reports of ECC, and identify factors related to ECC. METHODS: The Childhood Understanding Behaviors Survey (CUBS) is a population-based survey of parents of 3-year-old children and was utilized to describe changes in: parent-reported ECC among children with a dental visit, access to and or utilization of dental care, and consumption of three or more cups of sweetened beverages between 2009-2011 and 2016-2019. Logistic regression modeling was used to explore factors associated with parent-reported ECC among children with a dental visit. RESULTS: Over time, a significantly smaller proportions of parents whose 3-year-old child had seen a dental professional reported ECC. Additionally, a smaller proportion of parents reported three or more cups of sweetened beverage consumption by their child, while larger proportions had seen a dental professional by age 3. Factors associated with parent-reported ECC included consumption of three or more cups of sweetened beverages, and enrollment in Medicaid or Tribal health care insurance, while protective factors included a parent earning a college degree, and military insurance. CONCLUSIONS: Although at the statewide level, improvements were observed in parent-reported measures over time, regional disparities were apparent. Social and economic factors as well as excessive consumption of sweetened beverages appear to play important roles in ECC. CUBS data can help identify trends in ECC within Alaska.
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Suscetibilidade à Cárie Dentária , Cárie Dentária , Humanos , Pré-Escolar , Alaska/epidemiologia , Cárie Dentária/epidemiologia , Inquéritos e Questionários , Renda , PrevalênciaRESUMO
The understanding of fundamental atomic-level processes often requires well-defined model systems. The oxygen atom transfer from CO2 to a transition metal cation in the gas phase presents such a model system. We investigate the reaction of Ta+ + CO2 for which the formation of TaO+ is highly efficient and attributed to multistate reactivity. Here, we study the atomistic dynamics of the oxygen atom transfer reaction by recording experimental energy and angle differential cross sections by crossed beam velocity map imaging supported by ab initio quantum chemical calculations. Product ion velocity distributions are dominated by signatures for indirect dynamics, despite the reaction being highly exothermic. Product kinetic energy distributions show little dependence on additional collision energy even with only four atoms involved, which hints at dynamical trapping behind a submerged barrier.
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AIMS: This study examined whether the Chronic Care Model can be successfully applied to improve health outcome measures for uninsured, undocumented immigrants with diabetes at a free, non-federally funded community clinic. METHODS: Data were collected from 128 uninsured, undocumented immigrants enrolled in Programa de diabetes, a comprehensive diabetes program at People's Health Clinic based on the six core elements of the Chronic Care Model. All study participants self-identified by the Hispanic ethnicity. A longitudinal study design was used to compare baseline diabetic health measures with outcome data after patient program participation over a 12-month enrollment period. Linear mixed effect model was used to determine the patient specific change in HbA1C across time, controlling for gender, age, food insecurity, income level, diabetes type, and literacy. In addition, McNemar tests were conducted to compare the coverage of eye exams and statin use before and after program enrollment. RESULTS: After program enrollment, individual specific change in HbA1C was expected to be - 0.201 [95% CI 0.244, - 0.158] % per month after controlling for baseline covariates. There were statistically significant improvements in both eye exam coverage (p < 0.01) and statin use (p < 0.01). CONCLUSIONS: The Chronic Care Model can be successfully applied to improve health outcome measures at a free, non-federally funded community clinic among uninsured, undocumented immigrants, who identify by the Hispanic ethnicity and have the diagnosis of diabetes. Barriers to care including food insecurity, federal poverty level and illiteracy do not preclude glycemic control.
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Diabetes Mellitus , Inibidores de Hidroximetilglutaril-CoA Redutases , Imigrantes Indocumentados , Humanos , Hemoglobinas Glicadas , Estudos Longitudinais , Diabetes Mellitus/epidemiologia , Diabetes Mellitus/terapiaRESUMO
BACKGROUND: Many empirical investigations focus on how personality traits and academic motivation are related to academic achievement. Regarding the personality traits described in the five-factor model, prior research has shown associations between openness to experience and language achievement in particular. Following the principle of trait activation, associations with intrinsic value can explain these domain-specific relationships of openness with achievement. AIMS: This study investigated whether intrinsic value mediates the associations of openness to experience with language achievement to understand these associations more closely. Based on the principle of trait activation, we combined openness to experience with intrinsic value as a motivational construct more proximal to behaviour. SAMPLES: We capitalized on two large-scale longitudinal data sets (N = 1994; M = 16.8 years; 51% female; and N = 2722; M = 17.34 years; 58% female) of German-speaking students in upper secondary education with two points of measurement, respectively. METHODS: We assessed achievement using report card grades and standardized test scores, capturing three language subskills: reading and listening, measured by standardized tests, and writing competencies, measured by essay assignments. We conducted mediation analysis using bootstrapped confidence intervals and robust standard errors to account for dependencies in the data due to students clustered within classrooms. RESULTS AND CONCLUSIONS: Overall, our results show that intrinsic value mediated the relationship between openness and achievement in English as a foreign language. The results remained stable when controlling for prior achievement, predicting achievement gains. Our investigation provides empirical insights into the manifestations of personality in academic contexts. We discuss the limitations of our approach, with a focus on the use of a mediation analysis in this research design.
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Logro , Personalidade , Humanos , Feminino , Masculino , Personalidade/fisiologia , Motivação , Estudantes , IdiomaRESUMO
Introduction: Learning English as a foreign language is necessary for many students to actively participate in an increasingly globalized world. This study explores the role of informal English language engagement for students' reading and listening skills, as well as motivation to learn English. In an era of global interconnectedness, informal learning gains importance as a supplement to formal education. Methods: This study extends the evidence base by analyzing extramural reading and listening activities in a large-scale longitudinal investigation involving secondary school learners (N = 1,994) in Germany. Results: Our results show that frequent informal reading significantly relates to increases in students' English comprehension skills and their motivation for language learning, reaffirming previous cross-sectional findings. Discussion: The results highlight the relevance of informal language activities for effective language learning and students' English as a foreign language motivation. Additionally, discrepancies between reading and listening outcomes are discussed.
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Persisting patellar maltracking following surgical realignment often remains unseen. The aim of this study was to analyze the effects of realignment procedures on patellofemoral kinematics in patients with patellofemoral instability (PFI) and patellofemoral maltracking (PM) by using dynamic magnetic resonance imaging (MRI). Patients planned for surgical patellar realignment due to PFI and a clinically and radiologically apparent PM between December 2019 and May 2022 were included. Patients without PM, limited range of motion, joint effusion, or concomitant injuries were excluded. Dynamic mediolateral translation (dMPT) and patella tilt (dPT) were measured preoperatively and three months postoperatively. In 24 patients (7 men, 17 women; mean age 23.0 years), 10 tibial tubercle transfers, 5 soft tissue patella tendon transfers, 6 trochleoplasties, 3 lateral lengthenings, 1 varizating distal femoral osteotomy (DFO), and 1 torsional DFO were performed. At final follow-up, dMPT (from 10.95 ± 5.93 mm to 4.89 ± 0.40 mm, p < 0.001) and dPT (from 14.50° ± 10.33° to 8.44° ± 7.46°, p = 0.026) were significantly improved. All static radiological parameters were corrected to physiological values. Surgical patellar realignment contributed to the significant improvement of patellofemoral kinematics, with an approximation to normal values. The postoperative application of dynamic MRI allowed for a quantification of the performed correction, allowing for a postoperative control of success.