Actinometry of Hydrogen Plasmas

Optical emission spectroscopy (OES) can be used to map the electron energy distribution of hydrogen plasmas. Using actinometry, a type of OES where trace amounts of noble gases are introduced, the effect of discharge power on the electron temperature of hydrogen plasmas was explored. This was done using argon and krypton as actinometers for low pressure hydrogen plasmas. It was determined that the electron temperature decreased with respect to power supplied to the discharge

ESSAY: A “SAFETY MODEL” PERSPECTIVE CAN AID DIAGNOSIS, PREVENTION, AND RESTORATION AFTER CRIMINAL JUSTICE HARMS

ESSAY: A “SAFETY MODEL” PERSPECTIVE CAN AID DIAGNOSIS, PREVENTION, AND RESTORATION AFTER CRIMINAL JUSTICE HARM

Diverted from Landfill: Reuse of Single-Use Plastic Packaging Waste

Low-density polyethylene (LDPE) based packaging films mostly end up in landfill after single-use as they are not commonly recycled due to their flexible nature, low strength and low cost. Additionally, the necessity to separate and sort different plastic waste streams is the most costly step in plastics recycling, and is a major barrier to increasing recycling rates. This cost can be reduced through using waste mixed plastics (wMP) as a raw material. This research investigates the properties of PE-based wMP coming from film packaging wastes that constitutes different grades of PE with traces of polypropylene (PP). Their properties are compared with segregated individual recycled polyolefins and virgin LDPE. The plastic plaques are produced directly from the wMP shreds as well as after extruding the wMP shreds into a more uniform material. The effect of different material forms and processing conditions on the mechanical properties are investigated. The results of the investigation show that measured properties of the wMP fall well within the range of properties of various grades of virgin polyethylene, indicating the maximum possible variations between different batches. Addition of an intermediate processing step of extrusion before compression moulding is found to have no effect on the tensile properties but results in a noticeably different failure behaviour. The wMP does not show any thermal degradation during processing that was confirmed by thermogravimetric analysis. The results give a scientific insight into the adoption of wMP in real world products that can divert them from landfill creating a more circular economy

Isolation of polymorphic microsatellites in the stemless thistle (Cirsium acaule) and their utility in other Cirsium species

The genus Cirsium includes species with both widespread and restricted geographical distributions, several of which are serious weeds. Nine polymorphic microsatellite loci were isolated from the stemless thistle Cirsium acaule. Eight were polymorphic in C. acaule, six in C. arvense and seven in C. heterophyllum. One locus monomorphic in C. acaule showed polymorphism in C. heterophyllum. The mean number of alleles per locus was 4.1 in C. acaule, 6.2 in C. arvense and 2.9 in C. heterophyllum. These nine loci were also amplified in C. eriophorum and C. vulgare, suggesting that these markers may be of use throughout the genus

Observation of two-dimensional Fermi surface and Dirac dispersion in YbMnSb2_2

We present the crystal structure, electronic structure, and transport properties of the material YbMnSb$_2$, a candidate system for the investigation of Dirac physics in the presence of magnetic order. Our measurements reveal that this system is a low-carrier-density semimetal with a 2D Fermi surface arising from a Dirac dispersion, consistent with the predictions of density functional theory calculations of the antiferromagnetic system. The low temperature resistivity is very large, suggesting scattering in this system is highly efficient at dissipating momentum despite its Dirac-like nature.Comment: 8 pages, 6 figure

Stepwise Quenching of Exciton Fluorescence in Carbon Nanotubes by Single Molecule Reactions

Single-molecule chemical reactions with individual single-walled carbon nanotubes were observed through near-infrared photoluminescence microscopy. The emission intensity within distinct submicrometer segments of single nanotubes changes in discrete steps after exposure to acid, base, or diazonium reactants. The steps are uncorrelated in space and time, and reflect the quenching of mobile excitons at localized sites of reversible or irreversible chemical attack. Analysis of step amplitudes reveals an exciton diffusional range of about 90 nanometers, independent of nanotube structure. Each exciton visits approximately 104 atomic sites during its lifetime, providing highly efficient sensing of local chemical and physical perturbations