The nickel (Ni) hyperaccumulator Alyssum murale has been developed as a commercial crop for phytoremediation/phytomining Ni from metal-enriched soils. Here, metal co-tolerance, accumulation and ...localization were investigated for A. murale exposed to metal co-contaminants. A. murale was irrigated with Ni-enriched nutrient solutions containing basal or elevated concentrations of cobalt (Co) or zinc (Zn). Metal localization and elemental associations were investigated in situ with synchrotron X-ray microfluorescence (SXRF) and computed-microtomography (CMT). A. murale hyperaccumulated Ni and Co (> 1000 μg g⁻¹ dry weight) from mixed-metal systems. Zinc was not hyperaccumulated. Elevated Co or Zn concentrations did not alter Ni accumulation or localization. SXRF images showed uniform Ni distribution in leaves and preferential localization of Co near leaf tips/margins. CMT images revealed that leaf epidermal tissue was enriched with Ni but devoid of Co, that Co was localized in the apoplasm of leaf ground tissue and that Co was sequestered on leaf surfaces near the tips/margins. Cobalt-rich mineral precipitate(s) form on leaves of Co-treated A. murale. Specialized biochemical processes linked with Ni (hyper)tolerance in A. murale do not confer (hyper)tolerance to Co. A. murale relies on a different metal storage mechanism for Co (exocellular sequestration) than for Ni (vacuolar sequestration).
To test nanosize surface patterning for application as implant material, a suitable titanium composition has to be found first. Therefore we investigated the effect of surface chemistry on attachment ...and differentiation of osteoblast-like cells on pure titanium prepared by pulsed laser deposition (TiPLD) and different Ti alloys (Ti6Al4V, TiNb30 and TiNb13Zr13). Early attachment (30 min) and alkaline phosphatase (ALP) activity (day 5) was found to be fastest and highest, respectively, in cells grown on TiPLD and Ti6Al4V. Osteoblasts seeded on TiPLD produced most osteopontin (day 10), whereas expression of this extracellular matrix protein was an order of magnitude lower on the TiNb30 surface. In contrast, expression of the corresponding receptor, CD44, was not influenced by surface chemistry. Thus, TiPLD was used for further experiments to explore the influence of surface nanostructures on osteoblast adhesion, differentiation and orientation. By laser-induced oxidation, we produced patterns of parallel Ti oxide lines with different widths (0.2-10 microm) and distances (2-20 and 1,000 microm), but a common height of only 12 nm. These structures did not influence ALP activity (days 5-9), but had a positive effect on cell alignment. Two days after plating, the majority of the focal contacts were placed on the oxide lines. The portion of larger focal adhesions bridging two lines was inversely related to the line distance (2-20 microm). In contrast, the portion of aligned cells did not depend on the line distance. On average, 43% of the cells orientated parallel towards the lines, whereas 34% orientated vertically. In the control pattern (1,000 microm line distance), cell distribution was completely at random. Because a significant surplus of the cells preferred a parallel alignment, the nanosize difference in height between Ti surface and oxide lines may be sufficient to orientate the cells by contact guiding. However, gradients in electrostatic potential and surface charge density at the Ti/Ti oxide interface may additionally influence focal contact formation and cell guidance.
In-beam positron emission tomography (PET) is currently the only method for an in-situ monitoring of charged hadron therapy. However, in-beam PET data, measured at beams with a sub-/spl ...mu/s-microstructure due to the accelerator radio frequency (RF), are highly corrupted by random coincidences arising from prompt /spl gamma/ rays following nuclear reactions as the projectiles penetrate the tissue. Since random-correction techniques from conventional PET cannot be applied, the clinical in-beam PET at the therapy facility at the Gesellschaft fur Schwerionenforschung (GSI), Darmstadt, Germany, merely reconstructs events registered in the pauses (/spl sim/2--4 s) between the beam macropulses (/spl les/2 s). We have successfully tested two methods for suppressing the micropulse-induced random coincidences during beam extraction. Image statistics can be increased by about 90%. Both methods rely on the synchronization of the /spl gamma//spl gamma/ coincidences measured by the positron camera with the time microstructure of the beam, either by using the RF signal from the accelerator or the signal of a thin diamond detector placed in the beam path in front of the target. Energy and triple-coincidence time-correlated spectra first measured during beam extraction, combined with the corresponding tomographic images of the /spl beta//sup +/ activity induced by the beam in a plastic phantom, clearly confirm the feasibility of the proposed random suppression methods. These methods provide the solution for applying in-beam PET at synchrotron and cyclotron radiotherapy facilities with optimal use of the annihilation photon flux.
The high-acceptance dielectron spectrometer HADES Agakichiev, G.; Alvarez-Pol, H.; Balanda, A. ...
The European physical journal. A, Hadrons and nuclei,
08/2009, Letnik:
41, Številka:
2
Journal Article
Recenzirano
Odprti dostop
HADES is a versatile magnetic spectrometer aimed at studying dielectron production in pion, proton and heavy-ion-induced collisions. Its main features include a ring imaging gas Cherenkov detector ...for electron-hadron discrimination, a tracking system consisting of a set of 6 superconducting coils producing a toroidal field and drift chambers and a multiplicity and electron trigger array for additional electron-hadron discrimination and event characterization. A two-stage trigger system enhances events containing electrons. The physics program is focused on the investigation of hadron properties in nuclei and in the hot and dense hadronic matter. The detector system is characterized by an 85% azimuthal coverage over a polar angle interval from 18
°
to 85
°
, a single electron efficiency of 50% and a vector meson mass resolution of 2.5%. Identification of pions, kaons and protons is achieved combining time-of-flight and energy loss measurements over a large momentum range ( 0.1 <
p
< 1.0 GeV/
c
. This paper describes the main features and the performance of the detector system.
We studied five patients with clinical and radiological evidence of syringobulbia (SB) to determine whether the distribution of lesions in relationship to the cardiorespiratory control networks in ...the medullary intermediate reticular zone (IRt) correlates with the presence of abnormalities in autonomic cardiovascular and respiratory control in these patients. All patients underwent high resolution MRI to characterize the size, volume and distribution of the SB lesions, cardiovascular autonomic function testing and polysomnography. One patient with bilateral IRt involvement at both the rostral and caudal medulla had orthostatic hypotension (OH), absent HR(DB), abnormal Valsalva ratio, exaggerated fall of BP during phase II and absent phase IV during VM, and a dramatic fall of BP during head up tilt; this patient also had severe obstructive sleep apnea (OSA) and exhibited BP drops during each respiratory effort. A second patient, with bilateral IRt involvement restricted to the caudal medulla, had less severe cardiovascular autonomic dysfunction but also exhibited severe OSA. The other three patients had small SB cavities sparing the IRt and had sleep apnea but no autonomic dysfunction. Autonomic dysfunction could not be related to the size of the syrinx or the degree of atrophy in the cervical spinal cord in any of the five patients. Bilateral involvement of the IRt by SB produces cardiovascular autonomic failure and sleep apnea. In patients with more restricted lesions, autonomic and respiratory dysfunction may be dissociated. Clinico-radiological correlations using high resolution MRI assessment of medullary lesions can provide insight into the central organization of cardiovascular and respiratory control in humans.
We used a 6.5 m tall packed tower prototype to study the capturing rate of CO2 from air. The tower was operated at a pressure drop of less than 27 pa in the packing at 0.7 m/sec air speed with a ...counter current flow mode and with NaOH or KOH solution as the absorbent. The tower consumed an average of ∼30 kJe per mole CO2. We found that via an intermittent operation with a 5% duty cycle, the fluid pumping work reduced by 90%. A novel process for removing carbonates ions from alkaline solutions based on titanate compounds is compared to the traditional lime cycle for the caustic recovery. The titanate process reduces the high-grade heat requirement by ∼50%. The results from experimental data of leaching and precipitation test support process design of the titanate cycle. In this paper, we also present the chemical process design.
We have studied the performance of finger-like LSO:Ce (LSO) crystals coupled one by one to pixels of avalanche photodiode detector (APD) arrays during their operation in coincidence at /sup 12/C ion ...beams of parameters being typical for tumor irradiations. In a first step of these experiments the parameters of the detectors and the signal processing setup have been characterized off-beam, i.e., by means of /spl beta//sup +/ radioactive sources (/sup 22/Na, /sup 68/Ge). Afterwards, the apparatus was installed at the medical beam line of the heavy ion synchrotron (SIS) of the Gesellschaft fu/spl uml/r Schwerionenforschung (GSI) at Darmstadt, Germany. Here the /spl beta//sup +/ activity produced by nuclear fragmentation reactions of /sup 12/C 200.3 AMeV heavy ion beams with polymerized methyl methacrylate phantoms were measured. Furthermore, a /sup 68/Ge source was included into the in-beam experiment, in order to check the stability of the setup and to compare energy and time resolution before, during, and after the phantom irradiations. Additionally, it could be demonstrated by means of high resolution /spl gamma/-ray spectroscopy that LSO is not activated by the light projectile fragments escaping the patients downbeam during therapeutic irradiations The experimental results indicate that LSO scintillator is a suitable material for in-beam positron emission tomography (PET) and, furthermore, the LSO/APD array is a feasible detector concept for in-beam monitoring of the dose application by means of PET.
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