Rensselaer Polytechnic Institute

About: Rensselaer Polytechnic Institute is a education organization based out in Troy, New York, United States. It is known for research contribution in the topics: Terahertz radiation & Population. The organization has 19024 authors who have published 39922 publications receiving 1414699 citations. The organization is also known as: RPI & Rensselaer Institute.

Mechanistic analysis of ammonium cation stability for alkaline exchange membrane fuel cells

Abstract: Improving long-term cation stability is crucial for adopting anion exchange membrane fuel cells as a commercially viable technology in clean energy conversion applications. To reliably identify the most stable cation structures, we analyzed the cation stability of various synthetically prepared quaternary ammonium organic molecules via a silver oxide ion exchange reaction. This method enabled us to compare the stability of various structures of quaternary ammonium hydroxide in pure form in water without excess alkaline solution or inconsistencies faced in the presence of polymer backbones. By quantitatively comparing cation degradation via NMR, we were able to identify three cation structures with greater cation stability than the most well-known benzyltrimethylammonium. In addition, we were able to elucidate byproduct formation and degradation mechanisms as a result of hydroxide attack. From this study we concluded that alkyl-substituted cations seem to impart greater stability than benzylic-substituted cations in the presence of hydroxide anions in aqueous solution.

GenMax: An Efficient Algorithm for Mining Maximal Frequent Itemsets

Abstract: We present GenMax, a backtrack search based algorithm for mining maximal frequent itemsets. GenMax uses a number of optimizations to prune the search space. It uses a novel technique called progressive focusing to perform maximality checking, and diffset propagation to perform fast frequency computation. Systematic experimental comparison with previous work indicates that different methods have varying strengths and weaknesses based on dataset characteristics. We found GenMax to be a highly efficient method to mine the exact set of maximal patterns.

Constraining the Spin-Dependent WIMP-Nucleon Cross Sections with XENON1T

Abstract: We report the first experimental results on spin-dependent elastic weakly interacting massive particle (WIMP) nucleon scattering from the XENON1T dark matter search experiment. The analysis uses the full ton year exposure of XENON1T to constrain the spin-dependent proton-only and neutron-only cases. No significant signal excess is observed, and a profile likelihood ratio analysis is used to set exclusion limits on the WIMP-nucleon interactions. This includes the most stringent constraint to date on the WIMP-neutron cross section, with a minimum of 6.3×10-42 cm2 at 30 GeV/c2 and 90% confidence level. The results are compared with those from collider searches and used to exclude new parameter space in an isoscalar theory with an axial-vector mediator.

Methylmercury exposure in a subsistence fishing community in Lake Chapala, Mexico: an ecological approach.

Abstract: Elevated concentrations of mercury have been documented in fish in Lake Chapala in central Mexico, an area that is home to a large subsistence fishing community. However, neither the extent of human mercury exposure nor its sources and routes have been elucidated. Total mercury concentrations were measured in samples of fish from Lake Chapala; in sections of sediment cores from the delta of Rio Lerma, the major tributary to the lake; and in a series of suspended-particle samples collected at sites from the mouth of the Lerma to mid-Lake. A cross-sectional survey of 92 women ranging in age from 18-45 years was conducted in three communities along the Lake to investigate the relationship between fish consumption and hair mercury concentrations among women of child-bearing age. Highest concentrations of mercury in fish samples were found in carp (mean 0.87 ppm). Sediment data suggest a pattern of moderate ongoing contamination. Analyses of particles filtered from the water column showed highest concentrations of mercury near the mouth of the Lerma. In the human study, 27.2% of women had >1 ppm hair mercury. On multivariable analysis, carp consumption and consumption of fish purchased or captured from Lake Chapala were both associated with significantly higher mean hair mercury concentrations. Our preliminary data indicate that, despite a moderate level of contamination in recent sediments and suspended particulate matter, carp in Lake Chapala contain mercury concentrations of concern for local fish consumers. Consumption of carp appears to contribute significantly to body burden in this population. Further studies of the consequences of prenatal exposure for child neurodevelopment are being initiated.