872 research outputs found
Interaction of Liposomal Drug Delivery Systems with Cells and Tissues: Microscopic Studies
Liposomes , as drug carriers, can be administered into the body by several routes e.g. intravenously, intraperitoneally, intramuscularly, intratracheally and topically among others. Radiolabelled markers are suitable to monitor the distribution and elimination of liposomes, but the tissue deposition of intact liposomes, the mode and sites of drug release from the liposomes and liposome-cell interactions cannot be investigated morphologically. Microscopic techniques could provide information regarding the intact state of liposomes and possibly the dynamics of liposomes in tissues provided that they can be identified with certainty in vivo. This is a formidable problem and in spite of several attempts, there is still a lot of work and new ideas needed to overcome this problem.
This paper gives a detailed review of liposome markers used in light and electron microscopy. The use of markers or the technique involved in the identification of liposomes in cells or t issues is discussed.
The feasibility of using colloidal iron, a new electron dense marker, as a marker for intravenously injected liposomes was investigated in mice. Intact multilamellar vesicles containing colloidal iron were identified in the liver, spleen and lung of mice injected with liposomes. The liver and the spleen are organs for the storage of iron containing proteins (ferritin, hemosiderin), therefore studying the disposition of colloidal iron from the liposomes was not possible. However, in organs not containing iron, e.g. lung, the presence of colloidal iron can easily be recognized. The colloidal iron marker may be suitable to label liposomes targeted to the brain , heart or certain tumors
A természet, kultúra és részvétel alapú posztmodern fejlődés helyi társadalmi feltételei elmaradott rurális térségekben = Conditions of rural communities for postmodern (nature, culture and social participation based) revitalization of rural spaces
A vidĂ©ki tĂ©rsĂ©gekben zajlĂł változások megĂ©rtĂ©sĂ©re Ă©s a vidĂ©kfejlesztĂ©s feltĂ©telrendszerĂ©nek feltárására irányulĂł empirikus kutatásunkat három posztmodern Ă©rtĂ©kre: a termĂ©szeti környezetre, a kultĂşrára Ă©s a társadalmi rĂ©szvĂ©telre fĂłkuszáltuk. A helyi társadalmak Ă©rtĂ©krendjĂ©nek mĂ©rĂ©sĂ©re kifejlesztett eszközökkel sikerĂĽlt igazolnunk, hogy a helyi társadalom viszonya a posztmodern Ă©rtĂ©kekhez a környezĹ‘ terĂĽlet gazdasági fejlettsĂ©gĂ©tĹ‘l Ă©s a kĂĽlsĹ‘ kapcsolatrendszer működĂ©sĂ©tĹ‘l fĂĽggĹ‘en változik. A nyitottabb tĂ©rsĂ©gekben – jellemzĹ‘en kĂĽlsĹ‘ hatásra – megjelentek a posztmodern kultĂşra elemei. A zárt tĂ©rsĂ©gekben pedig a tradicionális kultĂşra fennmaradt elemei nyĂşjtanak alapot a posztmodernizáciĂłhoz. A nyitott Ă©s a zárt vidĂ©ki társadalmak kulturális sajátosságainak, erĹ‘forráskĂ©szletĂ©nek Ă©s intĂ©zmĂ©nyi struktĂşráinak összehasonlĂtása segĂt megĂ©rteni a vidĂ©kfejlesztĂ©s stratĂ©giáinak Ă©s eddigi eredmĂ©nyessĂ©gĂ©nek kĂĽlönbsĂ©geit. A vidĂ©k lehetsĂ©ges fejlĹ‘dĂ©si irányainak elfogadottsága Ă©s az azokhoz valĂł kapcsolĂłdási szándĂ©kok, valamint az erĹ‘forráskĂ©szlet Ă©s az azok hasznosĂtásához szĂĽksĂ©ges kĂ©pessĂ©gek közötti kĂĽlönbsĂ©gek a fejlesztĂ©sben a motiválás Ă©s a kultĂşraközvetĂtĂ©s szerepĂ©re, valamint a differenciált, a gazdasági versenykĂ©pessĂ©g Ăşj Ă©rtelmezĂ©sĂ©re Ă©pĂĽlĹ‘ vidĂ©kpolitika lĂ©tjogosultságára világĂtanak rá. | The aims of this empirical research project were to understand processes going in rural areas and exploration of conditions of rural development policies. We focused on three post-modern values like environmental sustainability, cultural determination and social participation. Tools to indentify dominant values of local communities were developed and using these tools we verified that the relation between a local society and post modern values were various due to the stage of economic development and the function of external relationships. Elements of post-modern culture were presented – mainly affected by external effects - in “open” local societies. Whereas in “closed” local societies the sustained elements of traditional culture gave basis to post-modernisation. Comparing cultural characteristics, local resources and institutional structures of both societies helped understanding differences in results of rural development strategies. Differences of acceptance of possible rural development directions and the motivations to participate within them as well as the stock of local resources and the capability to utilize them reflect the role of motivation and culture intermediation as well as the reason of a differentiated rural development policy based on a new interpretation of economic competition
Large Scales - Long Times: Adding High Energy Resolution to SANS
The Neutron Spin Echo (NSE) variant MIEZE (Modulation of IntEnsity by Zero
Effort), where all beam manipulations are performed before the sample position,
offers the possibility to perform low background SANS measurements in strong
magnetic fields and depolarising samples. However, MIEZE is sensitive to
differences \DeltaL in the length of neutron flight paths through the
instrument and the sample. In this article, we discuss the major influence of
\DeltaL on contrast reduction of MIEZE measurements and its minimisation.
Finally we present a design case for enhancing a small-angle neutron scattering
(SANS) instrument at the planned European Spallation Source (ESS) in Lund,
Sweden, using a combination of MIEZE and other TOF options, such as TISANE
offering time windows from ns to minutes. The proposed instrument allows
studying fluctuations in depolarizing samples, samples exposed to strong
magnetic fields, and spin-incoherently scattering samples in a straightforward
way up to time scales of \mus at momentum transfers up to 0.01 {\AA}-1, while
keeping the instrumental effort and costs low.Comment: 5 pages, 8 figure
Interrelations Between the Neutron's Magnetic Interactions and the Magnetic Aharonov-Bohm Effect
It is proved that the phase shift of a polarized neutron interacting with a
spatially uniform time-dependent magnetic field, demonstrates the same physical
principles as the magnetic Aharonov-Bohm effect. The crucial role of inert
objects is explained, thereby proving the quantum mechanical nature of the
effect. It is also proved that the nonsimply connectedness of the field-free
region is not a profound property of the system and that it cannot be regarded
as a sufficient condition for a nonzero phase shift.Comment: 18 pages, 1 postscript figure, Late
Accumulation of three-body resonances above two-body thresholds
We calculate resonances in three-body systems with attractive Coulomb
potentials by solving the homogeneous Faddeev-Merkuriev integral equations for
complex energies. The equations are solved by using the Coulomb-Sturmian
separable expansion approach. This approach provides an exact treatment of the
threshold behavior of the three-body Coulombic systems. We considered the
negative positronium ion and, besides locating all the previously know -wave
resonances, we found a whole bunch of new resonances accumulated just slightly
above the two-body thresholds. The way they accumulate indicates that probably
there are infinitely many resonances just above the two-body thresholds, and
this might be a general property of three-body systems with attractive Coulomb
potentials.Comment: 4 pages, 3 figure
Ready to Use Detector Modules for the NEAT Spectrometer Concept, Design, First Results
The paper presents the detector system developed by Datalist Systems, Ltd. previously ANTE Innovative Technologies for the NEAT II spectrometer at HZB. We present initial concept, design and implementation highlights as well as the first results of measurements such as position resolution. The initial concept called for modular architecture with 416 3He detector tubes organized into thirteen 32 tube modules that can be independently installed and removed to and from the detector vacuum chamber for ease of maintenance. The unalloyed aluminum mechanical support modules for four 8 tube units each also house the air boxes that contain the front end electronics preamplifiers that need to be on atmospheric pressure. The modules have been manufactured and partly assembled in Hungary and then fully assembled and installed on site by Datalist Systems crew. The signal processing and data acquisition solution is based on low time constant 60 ns preamplifier electronics and sampling ADC s running at 50 MS s i.e. a sample every 20 ns for all 832 data channels. The preamplifiers are proprietary, developed specifically for the NEAT spectrometer, while the ADC s and the FPGA s that further process the data are based on National Instruments products. The data acquisition system comprises 26 FPGA modules each serving 16 tubes providing for up to 50 kHz count rate per individual tube and it is organized into two PXI chassis and two data acquisition computers that perform post processing, event classification and provide appropriate preview of the collected data. The data acquisition software based on Event Recording principles provides a single point of contact for the scientific software with an Event Record List with absolute timestamps of 100ns resolution, timing data of 100 ns resolution for the seven discs chopper system as well as classification data that can be used for flexible data filtering in off line analysis of the gathered data. A unique 3 tier system of filtering criteria of events is in operation a hard threshold in the FPGA s to reduce the effect of noise, a pulse shape based classification to eliminate gamma sensitivity and an additional flexible feature based classification to filter out pileup and other unwanted phenomena. This ensures high count rates 50kHz per tube, 1MHz overall while maintaining good quality of measurements e.g. position resolution .The first measurement results show that the delivered detector system meets the initial requirements of 20 mm position resolution along the 2000mm long detector tubes. This is partly due to the innovative event classification system that provides vital pulse shape data that can be used for sophisticated position resolution algorithms implemented on the DAQ computer
Theory of the Fano Resonance in the STM Tunneling Density of States due to a Single Kondo Impurity
The conduction electron density of states nearby single magnetic impurities,
as measured recently by scanning tunneling microscopy (STM), is calculated,
taking into account tunneling into conduction electron states only. The Kondo
effect induces a narrow Fano resonance in the conduction electron density of
states, while scattering off the d-level generates a weakly energy dependent
Friedel oscillation. The line shape varies with the distance between STM tip
and impurity, in qualitative agreement with experiments, but is very sensitive
to details of the band structure. For a Co impurity the experimentally observed
width and shift of the Kondo resonance are in accordance with those obtained
from a combination of band structure and strongly correlated calculations.Comment: 4 pages, ReVTeX + 4 figures (Encapsulated Postscript), submitted to
PR
Non exponential relaxation in fully frustrated models
We study the dynamical properties of the fully frustrated Ising model. Due to
the absence of disorder the model, contrary to spin glass, does not exhibit any
Griffiths phase, which has been associated to non-exponential relaxation
dynamics. Nevertheless we find numerically that the model exhibits a stretched
exponential behavior below a temperature T_p corresponding to the percolation
transition of the Kasteleyn-Fortuin clusters. We have also found that the
critical behavior of this clusters for a fully frustrated q-state spin model at
the percolation threshold is strongly affected by frustration. In fact while in
absence of frustration the q=1 limit gives random percolation, in presence of
frustration the critical behavior is in the same universality class of the
ferromagnetic q=1/2-state Potts model.Comment: 7 pages, RevTeX, 11 figs, to appear on Physical Review
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