Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 114
Filtrar
Mais filtros

Base de dados
Tipo de documento
Intervalo de ano de publicação
1.
Proc Natl Acad Sci U S A ; 121(26): e2311009121, 2024 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-38885376

RESUMO

Public and academic discourse on ageism focuses primarily on prejudices targeting older adults, implicitly assuming that this age group experiences the most age bias. We test this assumption in a large, preregistered study surveying Americans' explicit sentiments toward young, middle-aged, and older adults. Contrary to certain expectations about the scope and nature of ageism, responses from two crowdsourced online samples matched to the US adult population (N = 1,820) revealed that older adults garner the most favorable sentiments and young adults, the least favorable ones. This pattern held across a wide range of participant demographics and outcome variables, in both samples. Signaling derogation of young adults more than benign liking of older adults, participants high on SDO (i.e., a key antecedent of group prejudice) expressed even less favorable sentiments toward young adults-and more favorable ones toward older adults. In two follow-up, preregistered, forecasting surveys, lay participants (N = 500) were generally quite accurate at predicting these results; in contrast, social scientists (N = 241) underestimated how unfavorably respondents viewed young adults and how favorably they viewed older adults. In fact, the more expertise in ageism scientists had, the more biased their forecasts. In a rapidly aging world with exacerbated concerns over older adults' welfare, young adults also face increasing economic, social, political, and ecological hardship. Our findings highlight the need for policymakers and social scientists to broaden their understanding of age biases and develop theory and policies that ponder discriminations targeting all age groups.


Assuntos
Etarismo , Humanos , Etarismo/psicologia , Idoso , Adulto , Estados Unidos , Pessoa de Meia-Idade , Masculino , Feminino , Adulto Jovem , Fatores Etários
2.
Circ Res ; 134(7): 892-912, 2024 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-38415360

RESUMO

BACKGROUND: Viral cardiac infection represents a significant clinical challenge encompassing several etiological agents, disease stages, complex presentation, and a resulting lack of mechanistic understanding. Myocarditis is a major cause of sudden cardiac death in young adults, where current knowledge in the field is dominated by later disease phases and pathological immune responses. However, little is known regarding how infection can acutely induce an arrhythmogenic substrate before significant immune responses. Adenovirus is a leading cause of myocarditis, but due to species specificity, models of infection are lacking, and it is not understood how adenoviral infection may underlie sudden cardiac arrest. Mouse adenovirus type-3 was previously reported as cardiotropic, yet it has not been utilized to understand the mechanisms of cardiac infection and pathology. METHODS: We have developed mouse adenovirus type-3 infection as a model to investigate acute cardiac infection and molecular alterations to the infected heart before an appreciable immune response or gross cardiomyopathy. RESULTS: Optical mapping of infected hearts exposes decreases in conduction velocity concomitant with increased Cx43Ser368 phosphorylation, a residue known to regulate gap junction function. Hearts from animals harboring a phospho-null mutation at Cx43Ser368 are protected against mouse adenovirus type-3-induced conduction velocity slowing. Additional to gap junction alterations, patch clamping of mouse adenovirus type-3-infected adult mouse ventricular cardiomyocytes reveals prolonged action potential duration as a result of decreased IK1 and IKs current density. Turning to human systems, we find human adenovirus type-5 increases phosphorylation of Cx43Ser368 and disrupts synchrony in human induced pluripotent stem cell-derived cardiomyocytes, indicating common mechanisms with our mouse whole heart and adult cardiomyocyte data. CONCLUSIONS: Together, these findings demonstrate that adenoviral infection creates an arrhythmogenic substrate through direct targeting of gap junction and ion channel function in the heart. Such alterations are known to precipitate arrhythmias and likely contribute to sudden cardiac death in acutely infected patients.


Assuntos
Células-Tronco Pluripotentes Induzidas , Miocardite , Humanos , Camundongos , Animais , Conexina 43/genética , Arritmias Cardíacas/genética , Arritmias Cardíacas/patologia , Miócitos Cardíacos/fisiologia , Junções Comunicantes , Adenoviridae/genética , Morte Súbita Cardíaca
3.
Proc Natl Acad Sci U S A ; 120(37): e2301532120, 2023 09 12.
Artigo em Inglês | MEDLINE | ID: mdl-37669375

RESUMO

Losing a job is one of life's most stressful events. Furthermore, maladaptive reactions to unemployment can trap people in a vicious cycle that derails their reemployment efforts. The current research tested whether a brief values-based self-affirmation intervention increases the odds of reemployment after a job loss and during unemployment, which presumably breaks this vicious cycle. Two field experiments, including one with a governmental employment agency, found that a 15-min self-affirmation exercise-i.e., reflecting on one's most important values-increased key employment-related outcomes after 4 wk, including the probability and speed of reemployment and the number of job offers. Because the ordeal of job loss and the probability of reemployment may be particularly challenging for individuals above the age of 50 y, we also explored whether the intervention was equally effective for those above and below 50 y of age. Demonstrating the generality of this effect, the efficacy of the intervention did not differ between individuals below and above the age of 50, and it was also effective for both recently unemployed and chronically unemployed individuals. Because self-affirmations have more typically been tested in educational contexts, the current research demonstrates the wide-ranging value of this intervention. By diminishing the vicious cycle of unemployment, the present studies show how a simple self-affirmation intervention can help individuals succeed in the labor market.


Assuntos
Emprego , Desemprego , Humanos , Ligante de CD40 , Exercício Físico , Órgãos Governamentais
4.
J Exp Bot ; 2024 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-38939967

RESUMO

Fundamental questions in bud dormancy remain, including what temperatures fulfill dormancy requirements (i.e., chill accumulation). Recent studies demonstrate freezing temperatures promote chill accumulation and cold hardiness influences time to budbreak - the phenotype used for dormancy evaluations. Here we evaluated bud cold hardiness (CH) and budbreak responses of grapevines (Vitis hybrids) throughout chill accumulation under three treatments: constant (5 °C), fluctuating (-3.5 to 6.5 °C daily), and field conditions (Madison, WI, USA). Chill treatments experiencing lower temperatures promoted greater gains in cold hardiness (CHfield>CHfluctuating>CHconstant). All treatments decreased observed time to budbreak with increased chill accumulation. However, perceived treatment effectiveness changed when time to budbreak was adjusted to remove cold acclimation effects. Among three classic chill models (North Carolina, Utah, and Dynamic), none were able to correctly describe adjusted time to budbreak responses to chill accumulation. Thus, a new model is proposed that expands the range of chill accumulation temperatures to include freezing temperatures and enhances chill accumulation under fluctuating temperature conditions. Most importantly, our analysis demonstrates adjustments for uneven acclimation change the perceived effectiveness of chill treatments. Therefore, future work in bud dormancy would benefit from simultaneously evaluating cold hardiness.

5.
Chemistry ; 30(6): e202303436, 2024 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-37877704

RESUMO

Five nitrogen sources (glycine, ß-alanine, urea, melamine and nicotinamide) and three heating methods (thermal, monomodal microwave and multimodal microwave) are used to prepare nitrogen-doped Starbons® derived from starch. The materials are initially produced at 250-300 °C (SNx 300y ), then heated in vacuo to 800 °C to produce nitrogen-doped SNx 800y 's. Melamine gives the highest nitrogen incorporation without destroying the Starbon® pore structure and the microwave heating methods give higher nitrogen incorporations than thermal heating. The carbon dioxide adsorption capacities of the nitrogen-doped Starbons® determined gravimetrically, in many cases exceed those of S300 and S800. The carbon dioxide, nitrogen and methane adsorption isotherms of the most promising materials are measured volumetrically. Most of the nitrogen-doped materials show higher carbon dioxide adsorption capacities than S800, but lower methane and nitrogen adsorption capacities. As a result, the nitrogen-doped Starbons® exhibit significantly enhanced carbon dioxide versus nitrogen and methane versus nitrogen selectivities compared to S800.

6.
Ann Bot ; 133(2): 217-224, 2024 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-37971306

RESUMO

BACKGROUND: Dormancy of buds is an important phase in the life cycle of perennial plants growing in environments where unsuitable growth conditions occur seasonally. In regions where low temperature defines these unsuitable conditions, the attainment of cold hardiness is also required for survival. The end of the dormant period culminates in budbreak and flower emergence, or spring phenology, one of the most appreciated and studied phenological events - a time also understood to be most sensitive to low-temperature damage. Despite this, we have a limited physiological and molecular understanding of dormancy, which has negatively affected our ability to model budbreak. This is also true for cold hardiness. SCOPE: Here we highlight the importance of including cold hardiness in dormancy studies that typically only characterize time to budbreak. We show how different temperature treatments may lead to increases in cold hardiness, and by doing so also (potentially inadvertently) increase time to budbreak. CONCLUSIONS: We present a theory that describes evaluation of cold hardiness as being key to clarifying physiological changes throughout the dormant period, delineating dormancy statuses, and improving both chill and phenology models. Erroneous interpretations of budbreak datasets are possible by not phenotyping cold hardiness. Changes in cold hardiness were very probably present in previous experiments that studied dormancy, especially when those included below-freezing temperature treatments. Separating the effects between chilling accumulation and cold acclimation in future studies will be essential for increasing our understanding of dormancy and spring phenology in plants.


Assuntos
Temperatura Baixa , Estações do Ano
7.
J Org Chem ; 87(24): 16410-16423, 2022 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-36454692

RESUMO

General routes for the synthesis of silica-immobilized symmetrical and unsymmetrical salophen and salen ligands and metal complexes have been developed starting from the natural product 4-allylanisole (methyl-chavicol and estragole). The key step of the syntheses is a microwave-assisted, platinum oxide catalyzed hydrosilylation of the terminal alkene of 5-allyl-2-hydroxybenzaldehyde to afford a sol-gel precursor which can be immobilized into silica before or after conversion to salen and salophen ligands to afford unsymmetrical and symmetrical silica-supported ligands, respectively. Both the symmetrical and unsymmetrical silica-supported salophens were found to catalyze the formation of cyclic carbonates from epoxides and carbon dioxide with catalytic activities at least comparable to those previously reported for non-immobilized homogeneous salophens. This reaction could also be carried out in a multi-phase flow reactor using ethyl acetate solutions of 3-phenoxypropylene oxide. Metal complexes of the silica-immobilized ligands could be prepared, and the aluminum complexes were also found to catalyze cyclic carbonate formation.

8.
Physiol Plant ; 174(3): e13717, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35592923

RESUMO

Woody perennials in temperate climates develop cold hardiness in the fall (acclimation) and lose cold hardiness in the spring (deacclimation) to survive freezing winter temperatures. Two main factors known to regulate deacclimation responses are dormancy status and temperature. However, the progression of deacclimation responses throughout the dormant period and across a range of temperatures is not well described. More detailed descriptions of dormancy status and temperature, as factors regulating deacclimation, are necessary to understand the timing and magnitude of freeze injury risks for woody perennials in temperate climates. In this study, we modeled deacclimation responses in cold-climate interspecific hybrid grapevine cultivars throughout the dormant period by integrating chill accumulation and temperature through the concept of deacclimation potential. We evaluated deacclimation and budbreak under multiple temperature treatments and chill unit accumulation levels using differential thermal analysis (DTA) and bud forcing assays. Deacclimation responses increased continuously following logistic trends for both increasing chill unit accumulation and increasing temperature. There are optimal temperatures where deacclimation rates increased but changes in deacclimation rates diminished below and above these temperatures. The cumulative chill unit range where deacclimation potential increased overlapped with the transition from endo- to ecodormancy. Therefore, deacclimation potential could provide a quantitative method for describing dormancy transitions that do not rely on the visual evaluation of budbreak. This information provides a more detailed understanding of when and how deacclimation contributes to increased risks by freezing injury. In addition, our descriptions could inform improvements to models predicting cold hardiness, dormancy transitions, and spring phenology.


Assuntos
Aclimatação , Temperatura Baixa , Vitis , Congelamento , Cinética , Estações do Ano , Vitis/fisiologia
9.
J Am Chem Soc ; 142(10): 4762-4768, 2020 03 11.
Artigo em Inglês | MEDLINE | ID: mdl-32069400

RESUMO

Developing future high performance adhesives is predicated upon achieving properties including strength and ductility. However, designing tough materials that are simultaneously strong and soft is usually contradictory in nature. Biological materials including shells and wood achieve impressive toughness by using weak bonds to connect larger structures at several length scales. Here, we show that this toughness design approach can be applied to synthetic adhesives. A biomimetic adhesive polymer, poly(catechol-acrylic acid), was examined in conjunction with several compounds containing two organic functional groups. In a typical example, the diol ethylene glycol decreased the overall system modulus. Performance was seen to increase significantly. Spectroscopic and physical methods indicated that these bifunctional additives created an interpolymeric network of weak hydrogen bonds. Material toughness was enhanced when breakable bonds were available to dissipate mechanical stresses while leaving the surrounding matrix intact. These discoveries illustrate how a biological materials strategy of interplay between strength and ductility can be achieved with sacrificial bonds in an adhesive. Such an approach may be a general principle applicable to designing higher performance electronics, transportation, and aerospace systems.


Assuntos
Resinas Acrílicas/química , Adesivos/química , Materiais Biomiméticos/química , Catecóis/química , Ligação de Hidrogênio
10.
Beilstein J Org Chem ; 16: 1124-1134, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32550927

RESUMO

The acid-base neutralization reaction of commercially available disodium 2,6-naphthalenedisulfonate (NDS, 2 equivalents) and the tetrahydrochloride salt of tetrakis(4-aminophenyl)methane (TAPM, 1 equivalent) in water gave a novel three-dimensional charge-assisted hydrogen-bonded framework (CAHOF, F-1). The framework F-1 was characterized by X-ray diffraction, TGA, elemental analysis, and 1H NMR spectroscopy. The framework was supported by hydrogen bonds between the sulfonate anions and the ammonium cations of NDS and protonated TAPM moieties, respectively. The CAHOF material functioned as a new type of catalytically active Brønsted acid in a series of reactions, including the ring opening of epoxides by water and alcohols. A Diels-Alder reaction between cyclopentadiene and methyl vinyl ketone was also catalyzed by F-1 in heptane. Depending on the polarity of the solvent mixture, the CAHOF F-1 could function as a purely heterogeneous catalyst or partly dissociate, providing some dissolved F-1 as the real catalyst. In all cases, the catalyst could easily be recovered and recycled.

11.
Chemistry ; 25(19): 4951-4964, 2019 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-30762275

RESUMO

The swelling of resins (Merrifield and HypoGel 200) in mixtures of two solvents was generally found not to vary linearly with the relative amount of each solvent in the mixture. Hansen solubility parameter (HSP) space could be used to define high, medium and low swelling regions for each resin. The variation of resin swelling with binary solvent composition could then be explained based on the HSP parameters of the two solvents and the way in which the line connecting the points corresponding to the two pure solvents bisected the swelling region for the resin. The applicability of the methodology was demonstrated by showing that an appropriate mixture of two green solvents was more effective for solid-phase peptide synthesis on Merrifield resin than use of either individual solvent and could completely replace the use of traditional polar aprotic and chlorinated solvents for this application. It was also shown that the high resin swelling area of Merrifield resin can be used to predict mixtures of green solvents that will dissolve linear, unfunctionalised polystyrene.

12.
Eur Radiol ; 29(11): 5784-5790, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30963278

RESUMO

OBJECTIVES: To determine if polyp detection at computed tomographic colonography (CTC) is associated with (a) the number of CTC examinations interpreted per day and (b) the length of time spent scrutinising the scan. METHODS: Retrospective observational study from two hospitals. We extracted Radiology Information System data for CTC examinations from Jan 2012 to Dec 2015. For each examination, we determined how many prior CTCs had been interpreted by the reporting radiologist on that day and how long radiologists spent on interpretation. For each radiologist, we calculated their referral rate (proportion deemed positive for 6 mm+ polyp/cancer), positive predictive value (PPV) and endoscopic/surgically proven polyp detection rate (PDR). We also calculated the mean time each radiologist spent interpreting normal studies ("negative interpretation time"). We used multilevel logistic regression to investigate the relationship between the number of scans reported each day, negative interpretation time and referral rate, PPV and PDR. RESULTS: Five thousand one hundred ninety-one scans were interpreted by seven radiologists; 892 (17.2%) were reported as positive, and 534 (10.3%) had polyps confirmed. Both referral rate and PDR reduced as more CTCs were reported on a given day (p < 0.001), the odds reducing by 7% for each successive CTC interpreted. Radiologists reporting more slowly than their colleagues detected more polyps (p = 0.028), with each 16% increase in interpretation time associated with a 1% increase in PDR. PPV was unaffected. CONCLUSIONS: Reporting multiple CTCs on a given day and rapid CTC interpretation are associated with decreased polyp detection. Radiologists should be protected from requirements to report too many CTCs or too quickly. KEY POINTS: • CT colonography services should protect radiologists from a need to report too fast (> 20 min per case) or for too long (> 4 cases consecutively without a break). • Professional bodies should consider introducing a target minimum interpretation time for CT colonography examinations as a quality marker.


Assuntos
Pólipos do Colo/diagnóstico por imagem , Colonografia Tomográfica Computadorizada/métodos , Neoplasias Colorretais/diagnóstico por imagem , Algoritmos , Competência Clínica/estatística & dados numéricos , Métodos Epidemiológicos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Padrões de Prática Médica/estatística & dados numéricos , Radiologistas/estatística & dados numéricos
13.
Molecules ; 24(2)2019 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-30642040

RESUMO

Seaweed powder has been found to act as an effective catalyst for the fixation of CO2 into epoxides to generate cyclic carbonates under solvent free conditions. Model background reactions were performed using metal halides and amino acids typically found in common seaweeds which showed potassium iodide (KI) to be the most active. The efficacy of the seaweed catalysts kelp (Laminaria digitata) and dulse (Palmaria palmata) was probed based on particle size, showing that kelp possessed greater catalytic ability, achieving a maximum conversion and selectivity of 63.7% to styrene carbonate using a kelp loading of 80% by weight with respect to epoxide, 40 bar of CO2, 120 °C for 3 h. Maximizing selectivity was difficult due to the generation of diol side product from residual H2O found in kelp, along with a chlorinated by-product thought to form due to a high quantity of chloride salts in the seaweeds. Data showed there was loss of organic matter upon use of the kelp catalyst, likely due to the breakdown of organic compounds and their subsequent removal during product extraction. This was highlighted as the likely cause of loss of catalytic activity upon reuse of the Kelp catalyst.


Assuntos
Produtos Biológicos/química , Dióxido de Carbono/química , Compostos de Epóxi/química , Alga Marinha/química , Carbonatos/química , Catálise , Reação de Cicloadição
14.
Chemistry ; 23(52): 12937-12943, 2017 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-28695990

RESUMO

Chromium(salphen) complex 10 is found to be a catalyst for the preparation of oxazolidinones from epoxides and isocyanates. Using the optimal reaction conditions (1.5 mol % of chromium(salphen) complex 10 at 80 °C in toluene for 4 hours), six epoxides were reacted with five isocyanates, providing 15 oxazolidinones in up to 90 % yield. With electron-deficient isocyanates, cyclotrimerisation of the isocyanate to the corresponding isocyanurates is a competing reaction, showing the importance of matching catalyst activity to that of the substrates.

15.
Chemistry ; 22(6): 2100-2107, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26743787

RESUMO

Chromium and aluminium salphen complexes have been found to display remarkable catalytic activity in the synthesis of cyclic carbonates from a range of epoxides and carbon dioxide. The Al(salphen) complex is more reactive towards terminal epoxides at ambient temperature and pressure, whereas the Cr(salphen) complex exhibits higher catalytic activity towards more challenging internal epoxides at elevated temperature and pressure.

19.
Angew Chem Int Ed Engl ; 55(32): 9173-7, 2016 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-27336368

RESUMO

Mesoporous carbonaceous materials (Starbons®) derived from low-value/waste bio-resources separate CO2 from CO2 /N2 mixtures. Compared to Norit activated charcoal (AC), Starbons® have much lower microporosities (8-32 % versus 73 %) yet adsorb up to 65 % more CO2 . The presence of interconnected micropores and mesopores is responsible for the enhanced CO2 adsorption. The Starbons® also showed three-four times higher selectivity for CO2 adsorption rather than N2 adsorption compared to AC.

20.
Chemistry ; 21(27): 9850-62, 2015 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-26032761

RESUMO

New aluminium scorpionate based complexes have been prepared and used for the synthesis of cyclic carbonates from epoxides and carbon dioxide. Bimetallic aluminium(heteroscorpionate) complexes 9-14 were synthesised in very high yields. The single-crystal X-ray structures of 12 and 13 confirm an asymmetric κ(2)-NO-µ-O arrangement in a dinuclear molecular disposition. These bimetallic aluminium complexes were investigated as catalysts for the synthesis of cyclic carbonates from epoxides and carbon dioxide in the presence of ammonium salts. Under the optimal reaction conditions, complex 9 in combination with tetrabutylammonium bromide acts as a very efficient catalyst system for the conversion of both monosubstituted and internal epoxides into the corresponding cyclic carbonates showing broad substrate scope. Complex 9 and tetrabutylammonium bromide is the second most efficient aluminium-based catalyst system for the reaction of internal epoxides with carbon dioxide. A kinetic study has been carried out and showed that the reactions were first order in complex 9 and tetrabutylammonium bromide concentrations. Based on the kinetic study, a catalytic cycle is proposed.

SELEÇÃO DE REFERÊNCIAS
Detalhe da pesquisa