Pavel Stepanov

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Positron emission mammography (PEM) provides images of biochemical activity in the breast with spatial resolution matching individual ducts (1.5 mm full-width at half-maximum). This spatial resolution, supported by count efficiency that results in high signal-to-noise ratio, allows confident visualization of intraductal as well as invasive breast cancers.(More)
The principle of magnetic drug targeting, wherein therapy is attached to magnetically responsive carriers and magnetic fields are used to direct that therapy to disease locations, has been around for nearly two decades. Yet our ability to safely and effectively direct therapy to where it needs to go, for instance to deep tissue targets, remains limited. To(More)
PURPOSE A time-varying magnetic field can cause unpleasant peripheral nerve stimulation (PNS) when the maximum excursion of the magnetic field (ΔB) is above a frequency-dependent threshold level [P. Mansfield and P. R. Harvey, Magn. Reson. Med. 29, 746-758 (1993)]. Clinical and research magnetic resonance imaging (MRI) gradient systems have been designed to(More)
The ability to use magnets external to the body to focus therapy to deep tissue targets has remained an elusive goal in magnetic drug targeting. Researchers have hitherto been able to manipulate magnetic nanotherapeutics in vivo with nearby magnets but have remained unable to focus these therapies to targets deep within the body using magnets external to(More)
Silicon is a convenient and inexpensive platform for radiation detection, but has low stopping power for x-rays and gamma-rays with high energy (e.g., 100 keV, as used in computed tomography and digital radiography, or 1 MeV, as desired for detection of nuclear materials). We have effectively increased the stopping power of silicon detectors by producing a(More)
Applying magnetic fields to guide and retain drug-loaded magnetic particles in vivo has been proposed as a way of treating illnesses. Largely, these efforts have been targeted at tumors. One significant barrier to long range transport within tumors is the extracellular matrix (ECM). We perform single particle measurements of 18 nm diameter nanorods(More)
Molecular genetic techniques (FISH and metagenomic analysis) were used to investigate prokaryotic complexes in native soils (gray forest soil and urbostratozema typical), soils contaminated by petroleum products (gasoline or diesel fuel), and soils subject to remediation by addition of a nitrogen-containing polysaccharide biopolymer chitin. The share of(More)
Surface-swimming nano- and micromotors hold significant potential for on-chip mixing, flow generation, sample manipulation, and microrobotics. Here we describe rotating microrods magnetized nearly orthogonally to their long axes. When actuated near a solid surface, these microrods demonstrate precessing motion, with rods describing a double cone similar to(More)