We address the question of what is the smallest spot size that hard x rays can be focused to using refractive optics. A thick refractive x-ray lens is considered, whose aperture is gradually ...(adiabatically) adapted to the size of the beam as it converges to the focus. These adiabatically focusing lenses are shown to have a relatively large numerical aperture, focusing hard x rays down to a lateral size of 2 nm (FWHM), well below the theoretical limit for focusing with waveguides C. Bergemann, Phys. Rev. Lett.912003204801.
Abstract Revision knee data from six joint arthroplasty centers were compiled for 2010 and 2011 to determine mechanism of failure and time to failure. Aseptic loosening was the predominant mechanism ...of failure (31.2%), followed by instability (18.7%), infection (16.2%), polyethylene wear (10.0%), arthrofibrosis (6.9%), and malalignment (6.6%). Mean time to failure was 5.9 years (range 10 days to 31 years). 35.3% of all revisions occurred less than 2 years after the index arthroplasty, 60.2% in the first 5 years. In contrast to previous reports, polyethylene wear is not a leading failure mechanism and rarely presents before 15 years. Implant performance is not a predominant factor of knee failure. Early failure mechanisms are primarily surgeon-dependent.
Abstract Liposomal bupivacaine periarticular injection (PAI) offers sustained bupivacaine release after TKA, but few prospective independent studies exist. In this prospective, blinded study, ...liposomal bupivacaine was randomized against bupivacaine and incorporated into a comprehensive multimodal pain management protocol. 111 primary TKAs were randomized to receive PAI: 58 patients received 266 mg (20 cc) liposomal bupivacaine mixed with 75 mg (30 cc) 0.25% bupivacaine, and 53 patients received 150 mg (60 cc) 0.25% bupivacaine. Visual analog pain scores and narcotic use were determined. No pain score differences occurred between study and control patients: Day 1: 4.5/4.6 ( P = 0.73); Day 2: 4.4/4.8 ( P = 0.27); or Day 3: 3.5/3.7 ( P = 0.58). Narcotic use was similar during hospitalization, 51.8/54.2 ( P = 0.34). The study medication costs $285, and the control medication costs $2.80. This finding does not justify the routine use of liposomal bupivacaine.
Abstract
Cavitation bubbles can be seeded from a plasma following optical breakdown, by focusing an intense laser in water. The fast dynamics are associated with extreme states of gas and liquid, ...especially in the nascent state. This offers a unique setting to probe water and water vapor far-from equilibrium. However, current optical techniques cannot quantify these early states due to contrast and resolution limitations. X-ray holography with single X-ray free-electron laser pulses has now enabled a quasi-instantaneous high resolution structural probe with contrast proportional to the electron density of the object. In this work, we demonstrate cone-beam holographic flash imaging of laser-induced cavitation bubbles in water with nanofocused X-ray free-electron laser pulses. We quantify the spatial and temporal pressure distribution of the shockwave surrounding the expanding cavitation bubble at time delays shortly after seeding and compare the results to numerical simulations.
Intense femtosecond x-ray pulses from free-electron laser sources allow the imaging of individual particles in a single shot. Early experiments at the Linac Coherent Light Source (LCLS) have led to ...rapid progress in the field and, so far, coherent diffractive images have been recorded from biological specimens, aerosols, and quantum systems with a few-tens-of-nanometers resolution. In March 2014, LCLS held a workshop to discuss the scientific and technical challenges for reaching the ultimate goal of atomic resolution with single-shot coherent diffractive imaging. This paper summarizes the workshop findings and presents the roadmap toward reaching atomic resolution, 3D imaging at free-electron laser sources.
Several steels were exposed to either static or flowing liquid lead–bismuth eutectic under various exposure conditions. Steels T91, EP-823, S2439 and S2440 were exposed to oxygen-rich static LBE at ...490°C for ∼5016h. The experiments in flowing LBE were carried out in the CORRIDA loop at 550°C and around 10−6mass% dissolved oxygen. The steels tested in the CORRIDA loop included the reduced activation steel EUROFER 97 and two heats of an oxide dispersion strengthened steel produced by mixing EUROFER 97 and yttria powders. The exposure time varied between 1007 and 7511h for the EUROFER 97 steel and between 5012 and 20039h for the two ODS heats. The exposed steels were characterized by means of scanning electron microscopy and energy-dispersive X-ray spectrometry.
3D and 2D-cross-sectional X-ray fluorescence analysis of biological material is a powerful tool to image the distribution of elements and to understand and quantify metal homeostasis and the ...distribution of anthropogenic metals and nanoparticles with minimal preparation artifacts. Using tomograms recorded on cryogenically prepared leaves of Allium schoenoprasum, the cross-sectional distribution of physiologically relevant elements like calcium, potassium, manganese, and zinc could be tomographically reconstructed by peak fitting followed by a conventional maximum-likelihood algorithm with self-absorption correction to reveal the quantitative cross-sectional element distribution. If light elements such as S and P are located deep in the sample compared to the escape depth of their characteristic X-ray fluorescence lines, the quantitative reconstruction becomes inaccurate. As a consequence, noise is amplified to a magnitude where it might be misinterpreted as actual concentration. We show that a tomographic MCA hyperspectral reconstruction in combination with a self-absorption correction allows for fitting of the XRF spectra directly in real space, which significantly improves the qualitative and quantitative analysis of the light elements compared to the conventional method as noise and artifacts in the tomographic reconstruction are reduced. This reconstruction approach can substantially improve the quantitative analysis of trace elements as it allows the fitting of summed voxel spectra in anatomical regions of interest. The presented method can be applied to XRF 2D single-slice tomography data and 3D tomograms and is particularly relevant for, but not limited to, biological material in order to help retrieve self-absorption corrected quantitative reconstructions of the spatial distribution of light elements and ultra-trace-elements.
The recent success in the development of high-precision printing techniques allows one to manufacture free-standing polymer structures of high quality. Two-photon polymerization lithography is a ...mask-less technique with down to 100 nm resolution that provides full geometric freedom. It has recently been applied to the nanofabrication of X-ray compound refractive lenses (CRLs). In this article we report on the characterization of two sets of CRLs of different design produced by two-photon polymerization-induced lithography.
We present light induced refractive index changes in iron doped lithium niobate detected with a novel microscopy technique called ptychography. This method determines the change of the refractive ...index together with the intensity distribution of the writing beam from a single scan with a reconstructed spatial resolution of 3 μm and a sensitivity of the refractive index change of 10-5. We show that the light induced refractive index change is strongly connected to the intensity shape of the writing beam and that it shows the expected nonlocal behaviour. Applying the novel method to the investigation of the photorefractive effect offers an excellent opportunity to study this nonlocal response to the spatial distribution of the writing beam.
We present light induced refractive index changes in iron doped lithium niobate detected with a novel microscopy technique called ptychography. This method determines the change of the refractive ...index together with the intensity distribution of the writing beam from a single scan with a reconstructed spatial resolution of 3 μm and a sensitivity of the refractive index change of 10
. We show that the light induced refractive index change is strongly connected to the intensity shape of the writing beam and that it shows the expected nonlocal behaviour. Applying the novel method to the investigation of the photorefractive effect offers an excellent opportunity to study this nonlocal response to the spatial distribution of the writing beam.
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