Molecular dynamics simulations of liquid nitromethane

A potential energy function with harmonic intramolecular and Lennard-Jones plus Coulombic intermolecular terms was tested in molecular dynamics simulations of liquid nitromethane. Parameter values were adjusted iteratively until satisfactory agreement with density functional pair calculations and experimental data was achieved. The properties computed using the NVT and NPT ensembles were the heat of vaporization, dielectric constant, self-diffusion coefficient, density, heat capacity at constant pressure, pair correlation functions, single molecule and collective dipole moment reorientation times, the vibrational spectrum, and the effect of increasing pressure upon the C−N stretching frequency. Overall, the results were in reasonable accord with experimental results, the greatest discrepancy being for the dielectric constant. It was concluded, on the basis of the reorientation times and the calculated molecular

Injury, intense dust exposure, and chronic disease among survivors of the World Trade Center terrorist attacks of September 11, 2001

Background: The World Trade Center attack of September 11, 2001 in New York City (9/11) exposed thousands of people to intense concentrations of hazardous materials that have resulted in reports of increased levels of asthma, heart disease, diabetes, and other chronic diseases along with psychological illnesses such as post-traumatic stress disorder (PTSD). Few studies have discriminated between health consequences of immediate (short-term or acute) intense exposures versus chronic residential or workplace exposures. Methods: We used proportional hazards methods to determine adjusted hazard ratios (AHRs) for associations between several components of acute exposures (e.g., injury, immersion in the dust cloud) and four chronic disease outcomes: asthma, other non-neoplastic lung diseases, cardiovascular disease, and diabetes, in 8701 persons free of those conditions prior to exposure and who were physically present during or immediately after the World Trade Center attacks. Participants were followed prospectively up to 11 years post-9/11. Results: Heart disease exhibited a dose-response association with sustaining injury (1 injury type: AHR =2.0, 95% CI (Confidence Interval) 1.1–3.6; 2 injury types: AHR = 3.1, 95% CI 1.2–7.9; 3 or more injury types: AHR = 6.8, 95% CI 2.0–22.6), while asthma and other lung diseases were both significantly associated with dust cloud exposure (AHR = 1.3, 95% CI 1.0–1.6). Diabetes was not associated with any of the predictors assessed in this study. Conclusion: In this study we demonstrated that the acute exposures of injury and dust cloud that were sustained on 9/11/2001 had significant associations with later heart and respiratory diseases. Continued monitoring of 9/11 exposed persons’ health by medical providers is warranted for the foreseeable future

Dancing to the Partisan Beat: A First Analysis of Political Communication on TikTok

TikTok is a video-sharing social networking service, whose popularity is increasing rapidly. It was the world's second-most downloaded app in 2019. Although the platform is known for having users posting videos of themselves dancing, lip-syncing, or showcasing other talents, user-videos expressing political views have seen a recent spurt. This study aims to perform a primary evaluation of political communication on TikTok. We collect a set of US partisan Republican and Democratic videos to investigate how users communicated with each other about political issues. With the help of computer vision, natural language processing, and statistical tools, we illustrate that political communication on TikTok is much more interactive in comparison to other social media platforms, with users combining multiple information channels to spread their messages. We show that political communication takes place in the form of communication trees since users generate branches of responses to existing content. In terms of user demographics, we find that users belonging to both the US parties are young and behave similarly on the platform. However, Republican users generated more political content and their videos received more responses; on the other hand, Democratic users engaged significantly more in cross-partisan discussions.Comment: Accepted as a full paper at the 12th International ACM Web Science Conference (WebSci 2020). Please cite the WebSci version; Second version includes corrected typo

Carbonylation reactions of iodoarenes with PAMAM dendrimer-palladium catalysts immobilized on silica

Palladium complexes immobilized onto generation 0-3 PAMAM dendrimers supported on silica were used as catalysts for the carbonylation of iodobenzene in methanol to form methyl benzoate. High yields were obtained and the catalyst was recycled 4-5 times without significant loss of activity. The carbonylation reaction was found to be applicable to a variety of iodoarenes regardless of the nature of the substituent.NRC publication: Ye

Cardiovascular Disease Hospitalizations in Relation to Exposure to the September 11, 2001 World Trade Center Disaster and Posttraumatic Stress Disorder

Background-—A cohort study found that 9/11-related environmental exposures and posttraumatic stress disorder increased self-reported cardiovascular disease risk. We attempted to replicate these findings using objectively defined cardiovascular disease hospitalizations in the same cohort. Methods and Results-—Data for adult World Trade Center Health Registry enrollees residing in New York State on enrollment and no cardiovascular disease history (n=46 346) were linked to a New York State hospital discharge–reporting system. Follow-up began at Registry enrollment (2003–2004) and ended at the first cerebrovascular or heart disease (HD) hospitalization, death, or December 31, 2010, whichever was earliest. We used proportional hazards models to estimate adjusted hazard ratios (AHRs) for HD (n=1151) and cerebrovascular disease (n=284) hospitalization during 302 742 person-years of observation (mean follow-up, 6.5 years per person), accounting for other factors including age, race/ethnicity, smoking, and diabetes. An elevated risk of HD hospitalization was observed among women (AHR 1.32, 95% CI 1.01 to 1.71) but not men (AHR 1.16, 95% CI 0.97 to 1.40) with posttraumatic stress disorder at enrollment. A high overall level of World Trade Center rescue and recovery–related exposure was associated with an elevated HD hospitalization risk in men (AHR 1.82, 95% CI 1.06 to 3.13; P for trend=0.05), but findings in women were inconclusive (AHR 3.29, 95% CI 0.85 to 12.69; P for trend=0.09). Similar associations were observed specifically with coronary artery disease hospitalization. Posttraumatic stress disorder increased the cerebrovascular disease hospitalization risk in men but not in women. Conclusions-—9/11-related exposures and posttraumatic stress disorder appeared to increase the risk of subsequent hospitalization for HD and cerebrovascular disease. This is consistent with findings based on self-reported outcomes

Heck reaction using palladium complexed to dendrimers on silica

Polyamidoamine dendrimers, constructed on the surface of silica, were phosphonated using diphenylphosphinomethanol (prepared in situ) and complexed to form a palladium-dimethyl TMEDA complex. This catalyst was found to be effective in the Heck reaction of aryl bromides with both butyl acrylate and styrene, affording coupling products in moderate to good yields. The heterogeneous palladium catalyst can also be recycled and reused with only moderate reduction in activity.Utilisant du diph\ue9nylphosphinom\ue9thanol (pr\ue9par\ue9 in situ), on a r\ue9alis\ue9 la phosphonation de dendrim\ue8res de polyamidoamines synth\ue9tis\ue9s sur une surface de silice et en a fait un complexe de palladium-"TMEDA" de dim\ue9thyle. On a trouv\ue9 que ce catalyseur est efficace dans la r\ue9action de Heck des bromures d'aryles avec aussi bien l'acrylate de butyle que le styr\ue8ne et que ces r\ue9actions fournissent des produits de couplage avec des rendements allant de mod\ue9r\ue9s \ue0 bons. On peut aussi r\ue9g\ue9n\ue9rer le catalyseur h\ue9t\ue9rog\ue8ne et le r\ue9utiliser avec une perte mineure d'activit\ue9.NRC publication: Ye

Solid-Phase Catalysis: A Biomimetic Approach toward Ligands on Dendritic Arms to Explore Recyclable Hydroformylation Reactions

Peer reviewed: YesNRC publication: Ye

A divergent, solid-phase approach to dendritic ligands on beads. Heterogeneous catalysis for hydroformylation reactions

NRC publication: Ye

Hydroformylation reactions with rhodium-complexed dendrimers on silica

Polyamidoamine dendrimers, constructed on the surface of silica, were phosphonated by using diphenylphosphinomethanol, prepared in situ, and complexed to rhodium by use of [Rh(CO)\u2082Cl]\u2082. Excellent selectivities, favoring the branched aldehydes obtained from aryl olefins and vinyl esters, were observed by using the Rh(I) complex as the catalyst in hydroformylation reactions. The heterogeneous Rh (I) catalyst can also be recycled and reused without significant loss of selectivity or activity.NRC publication: Ye

Risk factors for and consequences of persistent lower respiratory symptoms among World Trade Center Health Registrants 10 years after the disaster

Objectives: The prevalence of persistent lower respiratory symptoms (LRS) among rescue/recovery workers, local area workers, residents and passers-by in the World Trade Center Health Registry (WTCHR) was analysed to identify associated factors and to measure its effect on quality of life (QoL) 10 years after 9/11/2001. Methods: This cross-sectional study included 18 913 adults who completed 3 WTCHR surveys (2003–2004 (Wave 1 (W1)), 2006–2007 (Wave 2 (W2)) and 2011–2012 (Wave 3 (W3)). LRS were defined as self-reported cough, wheeze, dyspnoea or inhaler use in the 30 days before survey. The prevalence of three LRS outcomes: LRS at W1; LRS at W1 and W2; and LRS at W1, W2 and W3 (persistent LRS) was compared with no LRS on WTC exposure and probable mental health conditions determined by standard screening tests. Diminished physical and mental health QoL measures were examined as potential LRS outcomes, using multivariable logistic and Poisson regression. Results: Of the 4 outcomes, persistent LRS was reported by 14.7%. Adjusted ORs for disaster exposure, probable post-traumatic stress disorder (PTSD) at W2, lacking college education and obesity were incrementally higher moving from LRS at W1, LRS at W1 and W2 to persistent LRS. Half of those with persistent LRS were comorbid for probable PTSD, depression or generalised anxiety disorder. Enrollees with persistent LRS were 3 times more likely to report poor physical health and ∼ 50% more likely to report poor mental health than the no LRS group. Conclusions: LRS, accompanied by mental health conditions and decreased QoL, have persisted for at least 10 years after 9/11/2001. Affected adults require continuing surveillance and treatment