A recent paper by Siraj & Loeb (2021) entitled "Breakup of a long-period comet as the origin dinosaur extinction" attempts to revive perennial debate about what type body hit Earth 66 million years ago, triggering end-Cretaceous extinction. Here we critique and assess evidence it presents. To consider more likely than an asteroid requires extreme assumptions how comets fragment, conflation carb...

The 1ACFM cascade impactor and the High Volume cascade impactors are the instruments that mainly used to define the activity size distribution of radioactive aerosols in the environmental air. The impactors are instruments designed to collect and separate particulate matter according to its aerodynamic size, determining the penetration of particles in the human lung, as well as the transport an...

One of the key issues associated with the understanding of large scale impacts is how the observable complex crater structural features (e.g., central peaks and pits, flat floors, ring shaped ridges and depressions, tratigraphic modifications, and faults) relate to the impactor's parameters (e.g., radius, velocity, and density) and the nonobservable transient crater measures (e.g., depth of pen...

Chemical looping combustion of wood pellets (WP), char (WC), and straw (SP) was conducted in a 60 kW CLC pilot with ilmenite braunite oxygen carriers (OCs). Alkali emissions were investigated impactor-based surface ionization detector (SID) measurements. Particle size distributions for WP WC fuels dominated by coarse particles formed refractory species. For SP fuel, the distribution bimodal dis...

As a bioaerosol sampling standard, Andersen type impactor is widely used since its invention in 1950s, including the investigation of the anthrax attacks in the United States in 2001. However, its related problems such as impaction and desiccation stress as well as particle bounce have not been solved. Here, we improved its biological collection efficiencies by plating a mineral oil layer (100 ...