Chemistry of the outer planets: Investigations of the chemical nature of the atmosphere of Titan

It is clear from the experiments that a variety of complex organic models can be produced by lightning in a Titan-like gas mixture. The dominant products were found to be acetylene and hydrogen cyanide, with smaller amounts of many other species. Any aerosol produced by lightning inititated process will consist of a complex mixture of organic compounds, many of which should easily be identified by pyrolytic gas chromatography. Work will continue to expand the data base of molecules produced by lightning and other processes in order to assist in the design of appropriate analytical instruments for the upcoming Saturn/Titan mission and any other planetary probes

Fundamental studies of the solid-particle erosion of silicon

The predictions of the theories of solid-particle erosion of brittle materials are compared to experimental results of studies in which angular Al2O3 particles with mean diameters D of 23 to 270 microns are used to erode (111) surfaces of silicon single crystals at impact angles alpha from 20 to 90 deg and velocities v from 30 to 150 m/s. The description of the steady state erosion rate by a power law, delta W varies directly as (v sin alpha)(n)D(m) must be modified to include threshold and plasticity effects. Furthermore the velocity exponent n depends on D. Results using abrasives of different sizes mixed together can be explained using a logarithmic-normal distribution. The results of transient experiments can be used to explain the synergistic effects which are observed using a biomodal distribution of abrasives

Primary primers: Wisconsin shows how the Covid-19 pandemic has made holding elections much more difficult

Wisconsin is set to hold its presidential primary on April 7th, the first to do so following directives for its citizens to stay at home during the Covid-19 outbreak. Ahead of the primary, Wendy Scattergood writes on the electoral challenges that now face the state, from the impending shortage of poll workers and ballots, court challenges over a purge of a registered voters list, to difficulties in obtaining identification for absentee voting

In Wisconsin’s Senate race, Johnson vs. Feingold has gone from a sure-thing to a potential trend-buster

Wisconsin has voted for the Democratic presidential candidate for the past seven elections, and yet since 2010, the state has seen a notable swing towards the Republican Party in statewide and legislative races. As part of our series covering key Senate races in the 2016 election, Wendy Scattergood writes that former Senator Russ Feingold has a good chance of winning his old job back from incumbent Republican Senator, Ron Johnson, though this will also depend on turnout and on the top-ticket influence of Hillary Clinton

Primary Primers: Wisconsin’s election shows that a pivot to absentee ballots is possible at short notice –though not without problems

Last week Wisconsin held its presidential primary election alongside contests for the state Suprem eCourt and other local offices. Wendy Scattergood reports on controversies and lawsuits in the leadup to the vote as well as the difficulties posed by a rise in the use of absentee ballots in a social distancing election

In Wisconsin, Governor Scott Walker may face a Democratic backlash against Donald Trump

While considerable attention is being paid to the coming elections for the US House and Senate, November 6th will also see a number of important gubernatorial contests. Wendy E. Scattergood takes a deep dive into Wisconsin’s race for governor, where eight-year incumbent Republican Scott Walker, faces Democrat Tony Evers. She writes that while Walker has incumbency and the GOP’s typical midterm turnout advantage in his favor, he also faces a rising tide of dissatisfaction with President Trump and a potentially energized Democratic Party

Titan

The following topics are discussed with respect to Titan: observations of the atmosphere; laboratory simulations and theoretical models of Titan's atmosphere; endpoints of atmospheric chemistry - aerosols and oceans; exobiology; and the next steps in understanding Titan

Organic chemistry on Titan

Observations of nonequilibrium phenomena on the Saturn satellite Titan indicate the occurrence of organic chemical evolution. Greenhouse and thermal inversion models of Titan's atmosphere provide environmental constraints within which various pathways for organic chemical synthesis are assessed. Experimental results and theoretical modeling studies suggest that the organic chemistry of the satellite may be dominated by two atmospheric processes: energetic-particle bombardment and photochemistry. Reactions initiated in various levels of the atmosphere by cosmic ray, Saturn wind, and solar wind particle bombardment of a CH4 - N2 atmospheric mixture can account for the C2-hydrocarbons, the UV-visible-absorbing stratospheric haze, and the reddish color of the satellite. Photochemical reactions of CH4 can also account for the presence of C2-hydrocarbons. In the lower Titan atmosphere, photochemical processes will be important if surface temperatures are sufficiently high for gaseous NH3 to exist. Hot H-atom reactions initiated by photo-dissociation of NH3 can couple the chemical reactions of NH3 and CH4 and produce organic matter

La Marqueta: Examining the Retail Landscape of East Harlem

Located in the East Harlem section of Manhattan, La Marqueta was established in the 1930s to house the abundance of pushcart vendors clogging the city’s streets, and is now one of only four remaining public markets in the five boroughs. At the peak of Spanish Harlem in the 1950’s and ‘60s, La Marqueta had more than 500 vendors. As the East Harlem neighborhood has changed, however, La Marqueta has dwindled in size to only eight vendors and continues to struggle to attract customers and support profitable businesses. This thesis will analyze the feasibility of La Marqueta’s future in East Harlem through a neighborhood demographic and retail analysis as well as a comparative analysis of other markets with similar characteristics to La Marqueta. Ultimately, this research will provide recommendations for La Marqueta to support profitable and sustainable businesses and increase foot traffic and sales at the market