Magnetic Resonance Water Proton Relaxation in Protein Solutions and Tissue: T1ρ Dispersion Characterization

BACKGROUND: Image contrast in clinical MRI is often determined by differences in tissue water proton relaxation behavior. However, many aspects of water proton relaxation in complex biological media, such as protein solutions and tissue are not well understood, perhaps due to the limited empirical data. PRINCIPAL FINDINGS: Water proton T(1), T(2), and T(1rho) of protein solutions and tissue were measured systematically under multiple conditions. Crosslinking or aggregation of protein decreased T(2) and T(1rho), but did not change high-field T(1). T(1rho) dispersion profiles were similar for crosslinked protein solutions, myocardial tissue, and cartilage, and exhibited power law behavior with T(1rho)(0) values that closely approximated T(2). The T(1rho) dispersion of mobile protein solutions was flat above 5 kHz, but showed a steep curve below 5 kHz that was sensitive to changes in pH. The T(1rho) dispersion of crosslinked BSA and cartilage in DMSO solvent closely resembled that of water solvent above 5 kHz but showed decreased dispersion below 5 kHz. CONCLUSIONS: Proton exchange is a minor pathway for tissue T(1) and T(1rho) relaxation above 5 kHz. Potential models for relaxation are discussed, however the same molecular mechanism appears to be responsible across 5 decades of frequencies from T(1rho) to T(1)

In Vitro Evaluation of Enterococcus faecalis Adhesion on Various Endodontic Medicaments

E. faecalis in endodontic infection represents a biofilm type of disease, which explains the bacteria’s resistance to various antimicrobial compounds and the subsequent failure after endodontic treatment. The purpose of this study was to compare antimicrobial activities and bacteria kinetic adhesion in vitro for three endodontic medicaments with a clinical isolate of E. faecalis. We devised a shake culture which contained the following intracanalar preparations: CPD, Endoidrox (EIX), PulpCanalSealer (PCS); these were immersed in a liquid culture medium inoculated with the microorganism. The shake system velocity was able to prevent non-specific bacteria adhesion and simulated the salivary flow. Specimens were collected daily (from both the medium and medicaments) for 10 days; the viable cells were counted by plate count, while the adhesion index AI° [E. faecalis fg DNA] /mm2 was evaluated in the pastes after DNA extraction, by quantitative real time PCR for the 16S rRNA gene. A partial growth inhibition, during the first 24 hours, was observed in the liquid medium and on the medicaments for EIX and subsequently for CPD (six logs). EIX showed the lowest adhesion coefficient (5*102 [fg DNA]/mm2) for nine days and was similar to the control. PCS showed no antimicrobial/antibiofilm properties. This showed that “calcium oxide” base compounds could be active against biofilm progression and at least in the short term (2-4 days) on E. faecalis cells growing in planktonic cultures

Binary and Millisecond Pulsars at the New Millennium

We review the properties and applications of binary and millisecond pulsars. Our knowledge of these exciting objects has greatly increased in recent years, mainly due to successful surveys which have brought the known pulsar population to over 1300. There are now 56 binary and millisecond pulsars in the Galactic disk and a further 47 in globular clusters. This review is concerned primarily with the results and spin-offs from these surveys which are of particular interest to the relativity community.Comment: 59 pages, 26 figures, 5 tables. Accepted for publication in Living Reviews in Relativity (http://www.livingreviews.org

The use of oil-based mud cuttings as an alternative raw material to produce high sulfate-resistant oil well cement

Oil-based mud (OBM) is used during the oil well drilling processes to cool drilling pits and remove the cuttings. As a result of these processes, the oil-based mud (OBM) cuttings are produced. The composition of the OBM cuttings depends on the geological conditions of the boreholes and the OBM used during the drilling operation. In this study, the OBM cuttings were used as an alternative material to produce a special cement known as oil-well cement (OWC). Raw meal mixtures were prepared with various percentages of OBM cuttings (5, 11, 13, 15, 18, and 20%). Then they were sintered up to a temperature of 1450 °C, and the resulting cement clinker was ground to produce highly sulfate resistant OWC. The burnability of the raw meal was studied to explore the effect of OBM cuttings on raw meal behavior during the clinkerization process. The results of the study indicated a decrease in the decarbonation temperature and an increase in the rate of clinkerization as the OBM cuttings increased. The produced cement was tested per American Petroleum Institute’s testing procedure for OWC. Also, the cement hydration for 2, 7 and 28 days was carried out to study the behavior of the produced OWC

Binary and Millisecond Pulsars

We review the main properties, demographics and applications of binary and millisecond radio pulsars. Our knowledge of these exciting objects has greatly increased in recent years, mainly due to successful surveys which have brought the known pulsar population to over 1700. There are now 80 binary and millisecond pulsars associated with the disk of our Galaxy, and a further 103 pulsars in 24 of the Galactic globular clusters. Recent highlights have been the discovery of the first ever double pulsar system and a recent flurry of discoveries in globular clusters, in particular Terzan 5.Comment: 77 pages, 30 figures, available on-line at http://www.livingreviews.org/lrr-2005-