272 research outputs found
Autotaxin: Its Role in Biology of Melanoma Cells and as a Pharmacological Target
Autotaxin (ATX) is an extracellular lysophospholipase D (lysoPLD) released from normal cells and cancer cells. Activity of ATX is detected in various biological fluids. The lysophosphatidic acid (LPA) is the main product of ATX. LPA acting through specific G protein-coupled receptors (LPA1-LPA6) affects immunological response, normal development, and malignant tumors' formation and progression. In this review, the impact of autotoxin on biology of melanoma cells and potential treatment is discussed
Rola nerek w regulacji gospodarki wodnej ustroju
Nerki pełnią kluczową rolę w gospodarce wodnej organizmu poprzez regulację wydalania wody z moczem. Działanie regulacyjne nerek można rozpatrywać w trzech obszarach anatomiczno-funkcjonalnych: kłębuszka nerkowego (filtracja osocza), cewek nerkowych (reabsorpcja płynu cewkowego) oraz śródmiąższu nerki (absorpcji wody do kapilar okołocewkowych). Centralne miejsce w regulacji gospodarki wodnej odgrywa akwaporyna-2 (AQP2). Błonowa ekspresja AQP2 w komórkach głównych przewodów zbiorczych jest procesem zależnym od wazopresyny i receptorów V2, ale również może być modyfikowana poprzez hormony żołądkowo-jelitowe (np. sekretyna) czy też poprzez czynniki auto-/parakrynne (np. dopamina, pozakomórkowe nukleotydy) wywierające swój efekt na drodze niezależnej od wazopresyny. Mechanizm ten stwarza nowe możliwości interwencji farmakologicznej w stanach chorobowych przebiegających z zaburzeniem receptorów V2
Downconverting Module Architectures for High Performance Multipixel Cameras
Multipixel cameras represent an emerging topology for arrays receivers, improving speed and accuracy of both security scanning systems and radioastronomical sky surveys by means of a matrix of phased elements. Difficulties in the generation and proper distribution to each pixel of the local oscillator signal still limit their use to frequency ranges below a few GHz or at least seriously affect the complexity of the implementable cameras. This work presents a full comparison between two possible system architectures, alternatively based on LO frequency multiplication or subharmonic mixing strategies, aiming to overcome the aforesaid limitations: design and performance of two compact test vehicles in MMIC technology, both operating in the Q-band frequency range with ultrabroadband IF section, are reported
Alloying, de-alloying and reentrant alloying in (sub-)monolayer growth of Ag on Pt(111)
An in-situ nanoscopic investigation of the prototypical surface alloying
system Ag/Pt(111) is reported. The morphology and the structure of the
ultrathin Ag-Pt film is studied using Low Energy Electron Microscopy during
growth at about 800 K. An amazingly rich dynamic behaviour is uncovered in
which stress relieve plays a governing role. Initial growth leads to surface
alloying with prolonged and retarded nucleation of ad-islands. Beyond 50%
coverage de-alloying proceeds, joined by partial segregation of Pt towards the
centre of large islands in violent processes. Upon coalescence the irregularly
shaped vacancy clusters are filled by segregating Pt, which then take a compact
shape (black spots). As a result at around 85% coverage the strain of the
initially pseudo-morphological film is almost completely relieved and
Pt-segregation is at its maximum. Further deposition of Ag leads to transient
re-entrant alloying and recovery of the pseudo-morphological layer. The black
spots persist even in/on several layers thick films. Ex-situ atomic force
microscopy data confirm that these are constituted by probably amorphous
Pt(-rich) structures. The (sub-)monolayer films are very much heterogeneous
Visualization of steps and surface reconstructions in Helium Ion Microscopy with atomic precision
Helium Ion Microscopy is known for its surface sensitivity and high lateral
resolution. Here, we present results of a Helium Ion Microscopy based
investigation of a surface confined alloy of Ag on Pt(111). Based on a change
of the work function of 25\,meV across the atomically flat terraces we can
distinguish Pt rich from Pt poor areas and visualize the single atomic layer
high steps between the terraces. Furthermore, dechanneling contrast has been
utilized to measure the periodicity of the hcp/fcc pattern formed in the 2--3
layers thick Ag/Pt alloy film. A periodicity of 6.65\,nm along the
surface direction has been measured. In terms of
crystallography a hcp domain is obtained through a lateral displacement of a
part of the outermost layer by of a nearest neighbour spacing
along . This periodicity is measured with atomic
precision: coincidence between the Ag and the Pt lattices is observed for 23 Ag
atoms on 24 Pt atoms. The findings are perfectly in line with results obtained
with Low Energy Electron Microscopy and Phase Contrast Atomic Force Microscopy.Comment: 15 pages, 7 figure
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