Influence of neutron irradiation on the thermal conductivity of vapor‐deposited diamond

The influence of neutron irradiation on the thermal conductivity κ of diamond films fabricated by hot filament (HF) and microwave plasma assisted (MPA) deposition has been studied. The additional thermal resistivity induced by irradiation is similar to that found in single crystal diamond and is due mainly to the formation of clusters of disordered carbon material. Despite a significant difference in κ prior to irradiation, the thermal conductivity of the HF and MPA films is almost the same after a cumulative dose of 2.7×1017 neutrons cm−2.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69811/2/JAPIAU-76-3-1515-1.pd

Correlating optical absorption and thermal conductivity in diamond

The presence of defects in diamond induces one‐phonon infrared absorption which is not allowed in the perfect crystal due to symmetry. Concomitantly the thermal conductivity is reduced by additional phonon‐defect scattering. For single crystal diamonds irradiated with fast neutrons, we find a correlation between the one‐phonon absorption and the room‐temperature thermal conductivity valid over three orders of magnitude in defect concentration. This relation holds for both unannealed and annealed crystals for which the detailed configuration of defects is different, as well as for a synthetic diamond film containing a similar type of disorder. Infrared absorption can thus be used to determine the thermal conductivity of diamonds containing vacancy‐related defect centers.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70107/2/APPLAB-63-2-165-1.pd

Electrical resistivity of single crystal arsenic at very low temperatures

The authors have carried out high-precision measurements of the electrical resistivity on very high-quality arsenic single crystals along the binary direction below 4K. The results show that rho approximately Tn with n increasing from 3 to 4 below 2K. This strong temperature dependence is a signal of carrier-phonon scattering in this temperature regime. No evidence of a superconducting transition was observed down to as low as 15 mK on the samples.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/49181/2/jfv16i6pL103.pd

Thermal transport properties of SbCl5-graphite and of HOPG in the c-direction

We report measurements of the c-axis thermal conductivity and thermoelectric power of SbCl5-GIC's. Thermal conduction is dominated by the lattice, with defects being the dominant scatterers. The thermopower is in good agreement with theoretical predictions for GICs. Finally, results for the very low temperature thermal conductivity of pure graphite in the c-direction are presented and discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25507/1/0000048.pd

Distinguishing low frequency mutations from RT-PCR and sequence errors in viral deep sequencing data

There is a high prevalence of coronary artery disease (CAD) in patients with left bundle branch block (LBBB); however there are many other causes for this electrocardiographic abnormality. Non-invasive assessment of these patients remains difficult, and all commonly used modalities exhibit several drawbacks. This often leads to these patients undergoing invasive coronary angiography which may not have been necessary. In this review, we examine the uses and limitations of commonly performed non-invasive tests for diagnosis of CAD in patients with LBBB

Thermoelectric materials with filled skutterudite structure for thermoelectric devices

A class of thermoelectric compounds based on the skutterudite structure with heavy filling atoms in the empty octants and substituting transition metals and main-group atoms. High Seebeck coefficients and low thermal conductivities are achieved in combination with large electrical conductivities in these filled skutterudites for large ZT values. Substituting and filling methods are disclosed to synthesize skutterudite compositions with desired thermoelectric properties. A melting and/or sintering process in combination with powder metallurgy techniques is used to fabricate these new materials

Thermoelectric materials with filled skutterudite structure for thermoelectric devices

A class of thermoelectric compounds based on the skutterudite structure with heavy filling atoms in the empty octants and substituting transition metals and main-group atoms. High Seebeck coefficients and low thermal conductivities are achieved in combination with large electrical conductivities in these filled skutterudites for large ZT values. Substituting and filling methods are disclosed to synthesize skutterudite compositions with desired thermoelectric properties. A melting and/or sintering process in combination with powder metallurgy techniques is used to fabricate these new materials

Cerium LIII-Edge X-ray Absorption Study of the CeₓFe\u3csub\u3e4-y\u3c/sub\u3eCo\u3csub\u3ey\u3c/sub\u3eSb₁₂ Skutterudites

The cerium LIII-edge x-ray absorption near-edge spectra of the CexFe4-yCoySb12 compounds have been obtained at 295 K and unambiguously indicate that cerium is in the 4f1 electronic ground state for all values of 0.22≤x≤0.98 and 0.0≤y≤3.5. This stable trivalent state of cerium is in agreement with the proposed (CeFe4Sb12) 1-α(Co4Sb12)α, solid solution structure, in which the cerium atoms are always surrounded by twelve antimony first neighbors and six iron second neighbors, the observed magnetic properties of CeFe4Sb12 and Ce0.9Fe3CoSb12, and the electronic structure of CeFe4Sb12 obtained from band-structure calculations

Electronic transport in Mo/Ni superlattices

An experimental relationship between superconductivity, magnetism and localization is explored in short-wavelength (14A [les] [logical or operator] [les] 40A) sputtered Mo/Ni superlattices. A crossover to a superconducting state is observed for [logical or operator] < 9A consistent with the observed paramagnetic behavior when the Ni strata are four atomic layers thick, or less. All samples show localization effects at helium temperatures and non-superconducting samples develop an unusual resistance plateau below T [reverse similar, equals] 0.5K.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25845/1/0000408.pd

Beyond the consensus: dissecting within-host viral population diversity of foot-and-mouth disease virus using next-generation genome sequencing

The sequence diversity of viral populations within individual hosts is the starting material for selection and subsequent evolution of RNA viruses such as foot-and-mouth disease virus (FMDV). Using next-generation sequencing (NGS) performed on a Genome Analyzer platform (Illumina), this study compared the viral populations within two bovine epithelial samples (foot lesions) from a single animal with the Inoculum used to initiate experimental infection. Genomic sequences were determined in duplicate sequencing runs, and the consensus sequence determined by NGS, for the Inoculum, was identical to that previously determined using the Sanger method. However, NGS reveals the fine polymorphic sub-structure of the viral population, from nucleotide variants present at just below 50% frequency to those present at fractions of 1%. Some of the higher frequency polymorphisms identified encoded changes within codons associated with heparan sulphate binding and were present in both feet lesions revealing intermediate stages in the evolution of a tissue-culture adapted virus replicating within a mammalian host. We identified 2,622, 1,434 and 1,703 polymorphisms in the Inoculum, and in the two foot lesions respectively: most of the substitutions occurred only in a small fraction of the population and represent the progeny from recent cellular replication prior to onset of any selective pressures. We estimated an upper limit for the genome-wide mutation rate of the virus within a cell to be 7.8 x 10-4 per nt. The greater depth of detection, achieved by NGS, demonstrates that this method is a powerful and valuable tool for the dissection of FMDV populations within-hosts