The adsorption of CO and desorption of CO
2
interacting with the Pt (111) surface was investigated using Kinetic Monte Carlo (kMC) simulation. The processes involved an elementary oxidation/reduction ...reaction (ORR). In comparison with standard density functional theory (DFT), kMC can simulate systems at practical time scale since it is concerned with the elementary reactions of the CO and O
2
molecules adsorbed in the surface of the Pt system. The DFT results provide reliable estimates for adsorption and desorption energy barriers. The standard Arrhenius' equation serves as a working model to define the temperature dependence of individual elementary reaction rates (k). By incorporating the proper k obtained from DFT calculations into the kMC simulations, the study was able to reproduce acceptable result in agreement with practical microscopic reaction step occurring in the exhaust of gasoline engines. Thus, the kMC provides useful insight in the involved ORR steps in the interaction of CO and O
2
with Pt. The ORR is sensitive to O–O dissociation compared with CO adsorption
Immigration is profoundly changing the racial demographics of America. In this article, we seek to understand if and how immigration and increasing racial diversity are shaping the partisan politics ...of individual white Americans. We show that whites' views on immigration and Latinos are strongly related to their core political identities and vote choices. Using a range of different surveys, we find that, all else equal, whites with more anti-immigrant views or more negative views of Latinos are less apt to identify as Democrats and less likely to favor Democratic candidates. This rightward shift harkens back to an earlier period of white defection from the Democratic Party and highlights the enduring but shifting impact of race on American politics.
Body size is a key life-history trait influencing all aspects of an organism's biology. Ants provide an interesting model for examining body-size variation because of the high degree of worker ...polymorphism seen in many taxa. We review worker-size variation in ants from the perspective of factors internal and external to the colony that may influence body-size distributions. We also discuss proximate and ultimate causes of size variation and how variation in worker size can promote worker efficiency and colony fitness. Our review focuses on two questions: What is our current understanding of factors influencing worker-size variation? And how does variation in body size benefit the colony? We conclude with recommendations for future work aimed at addressing current limitations and ask, How can we better understand the contribution of worker body-size variation to colony success? And, what research is needed to address gaps in our knowledge?
This research focuses on how the gender composition of a multinational board and linguistic gender marking gaps between home and host countries impact the extent of cross-border M&A activity. We ...argue, both theoretically and empirically, that the presence of female directors impacts cross-border M&As. Using an instrumental variable approach, we demonstrate that this effect is causal. Innovatively, we measure gaps in linguistic gender marking between home and host countries, and find that larger gaps also reduce cross-border M&As. Finally, we show that small gaps in linguistic gender marking moderate the effect of female presence in boardroom on cross-border M&As.
Regional input-output tables and trade flows: an integrated and interregional non-survey approach. Regional Studies. Regional analyses require detailed and accurate information about dynamics ...happening within and between regional economies. However, regional input-output tables and trade flows are rarely observed and they must be estimated using up-to-date information. Common estimation approaches vary widely but consider tables and flows independently. By using commonly used economic assumptions and available economic information, this paper presents a method that integrates the estimation of regional input-output tables and trade flows across regions. Examples of the method implementation are presented and compared with other approaches, suggesting that the integrated approach provides advantages in terms of estimation accuracy and analytical capabilities.
Like the music projects of HIV/AIDS, government agencies, foreign-based nongovernmental organizations (NGOs), and local artists promoted songs of awareness, hope, and unity during the 2014 Ebola ...crisis. Drawing from online music and media sources, this study analyzes the discourse, structure, and musical style of Ebola songs in Liberia funded and composed by NGO initiatives (UNICEF and Liberian Crusaders for Peace) and those produced by independent artists (Shadow, D-12, and Kuzzy of 2Kings). While many would consider the primary value of Ebola music to be educational utility, I argue that these songs represent the cultural and political identities of their composers and establish relationships of power involved in a disease-stricken music scene.
The hydrogen adsorption capabilities of Titanium functionalized single-walled BN nanotubes (BNNTs) with B–N defects was assessed by density-functional theory tight binding (DFTB) method. According to ...the DFTB molecular dynamics simulations, the BNNT structures were thermodynamically stable, the Ti atom once incorporated with the B–N defects present in BNNT (Ti–BNNT) protrudes to the external surface of the BNNT sidewall. The titanium atoms does not agglomerate to form any metal clusters. The results revealed that at 77 K and 10,000 KPa, the H
2
–Ti–BNNT has a gravimetric hydrogen storage capacity above 7 wt% ideal for department of energy specifications. Further calculations suggest that the Ti–BNNT has a good affinity towards H
2
molecules and under low pressure of 500 KPa. The H
2
stays close to the Ti metal due to its partially cationic character with some H
2
attaching itself at the BNNT surface due to heteropolar bonding. H
2
atoms is physisorbed in analogous to or resembling something molecular near the Ti sites which gives rise to a significant storage capacity for H
2
in these modified BNNT.
The follicular variant of papillary thyroid carcinoma usually presents as an encapsulated tumor and less commonly as a partially/non-encapsulated infiltrative neoplasm. The encapsulated form rarely ...metastasizes to lymph node, whereas infiltrative tumor often harbors nodal metastases. The molecular profile of the follicular variant was shown to be close to the follicular adenoma/carcinoma group of tumors with a high RAS and very low BRAF mutation rates. A comprehensive survey of oncogenic mutations in the follicular variant of papillary thyroid carcinoma according to its encapsulated and infiltrative forms has not been performed. Paraffin tissue from 28 patients with encapsulated and 19 with infiltrative follicular variant were subjected to mass spectrometry genotyping encompassing the most significant oncogenes in thyroid carcinomas: 111 mutations in RET, BRAF, NRAS, HRAS, KRAS, PIK3CA, AKT1 and other related genes. There was no difference in age, gender, tumor size and angioinvasion between encapsulated or infiltrative tumors. Infiltrative carcinomas had a much higher frequency of extrathyroid extension, positive margins and nodal metastases than encapsulated tumors (P<0.05). The BRAF 1799T>A mutation was found in 5 of 19 (26%) of the infiltrative tumor and in none of the encapsulated carcinomas (P=0.007). In contrast, RAS mutations were observed in 10 of 28 (36%) of the encapsulated group (5 NRAS_Q61R, 3 HRAS_Q61, 1 HRAS_G13C and 1 KRAS_Q61R) and in only 2 of 19 (10%) of infiltrative tumors (P=0.09). One encapsulated carcinoma showed a PAX8/PPARgamma rearrangement, whereas two infiltrative tumors harbored RET/PTC fusions. Encapsulated follicular variant of papillary thyroid carcinomas have a molecular profile very close to follicular adenomas/carcinomas (high rate of RAS and absence of BRAF mutations). Infiltrative follicular variant has an opposite molecular profile closer to classical papillary thyroid carcinoma than to follicular adenoma/carcinoma (BRAF>RAS mutations). The molecular profile of encapsulated and infiltrative follicular variant parallels their biological behavior (ie, metastatic nodal and invasive patterns).
The continuous release of pharmaceuticals from WWTP effluents to freshwater is a matter of concern, due to their potential effects on non-target organisms. The occurrence of pharmaceuticals in WWTPs ...and their associated hazard have been scarcely studied in Latin American countries. This study aimed at monitoring for the first time the occurrence of 70 pharmaceutical active compounds (PhACs) in WWTPs across Costa Rica; the application of the hazard quotient (HQ) approach coupled to ecotoxicological determinations permitted to identify the hazard posed by specific pharmaceuticals and toxicity of the effluents, respectively. Thirty-three PhACs were found, with 1,7-dimethylxanthine, caffeine, acetaminophen, ibuprofen, naproxen, ketoprofen and gemfibrozil being the most frequently detected (influents/effluents). HQ for specific pharmaceuticals revealed 24 compounds with high/medium hazard in influents, while the amount only decreased to 21 in effluents. The top HQ values were obtained for risperidone, lovastatin, diphenhydramine and fluoxetine (influent/effluent samples), plus caffeine (influent) and trimethoprim (effluent). Likewise, the estimation of overall hazard in WWTP samples (sum of individual HQ, ∑HQ) demonstrated that every influent and 96% of the effluents presented high hazard towards aquatic organisms. Ecotoxicological analysis (Daphnia magna, Lactuca sativa and Microtox test) revealed that 16.7% of the effluents presented toxicity towards all benchmark organisms; the phytotoxicity was particularly frequent, as inhibition values ≥20% in the germination index for L. sativa were obtained for all the effluents. The ∑HQ approach estimated the highest hazard in urban wastewater, while the ecotoxicological results showed the highest toxicity in hospital and landfill wastewater. Likewise, ecotoxicological results and ∑HQ values showed a rather poor correlation; instead, better correlations were obtained between ecotoxicological parameters and HQ values for some individual pharmaceuticals such as cephalexin and diphenhydramine. Findings from this study provide novel information on the occurrence of pharmaceuticals and the performance of WWTPs in the tropical region of Central America.
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•Occurrence of 70 pharmaceutical compounds in WWTPs in Costa Rica.•High hazard estimated in every influent and 96% effluents towards aquatic organisms.•Risperidone, lovastatin and diphenhydramine exhibited the highest hazard in influents/effluents.•Toxicity of 16.7% effluents towards all benchmark organisms experimentally tested.•Phytotoxicity (inhibition in seed germination test) particularly critical in effluents.
The realistic shapes of N doped graphene nanoribbons (GNRs) can be realized by considering nearly zigzag-edged (NZE) imperfections and pyridine defects (3NV). The paper focuses on NZE-GNRs with 3NV ...that is populated by Scandium abbreviated as Sc/NZE-3NVGNRs. Systematic calculations have clarified roles of the nano-shapes of NZE-3NVGNRs in its formation, energetics, stability and electron states functionalized with Sc using density functional theory (DFT) formalisms. According to DFT calculations, the magnitude of the spin that is attributed to the rise of magnetic order is closely linked to the altered shape of the ribbon edges. Also, calculations show that the stability of Sc functionalization at the 3NV and NZE site is thermodynamically stable and is dictated by a strong binding energy (BE). The magnitude of the BE is enhanced when the zigzag edge is short or the ribbon width is narrow, suggesting a reduced clustering of Sc atoms over the Sc-doped NZE-3NVGNRs. Results also show that as the length of the zigzag edge in Sc/NZE-3NVGNRs increases it creates considerable distortion on the appearance of the structure. Finally, the Sc/NZE-3NVGNRs as a potential candidate for hydrogen storage was evaluated and it was found that it could adsorb multiple hydrogen molecules.
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