Effects Of Gd3 Research Articles

Effects of Gd3+ doping on phase compositions, mechanical properties and thermophysical properties of (Yb1-xGdx)4Hf3O12 ceramics

A series of (Yb1-xGdx)4Hf3O12 (x=0, 0.1, 0.2, 0.3 and 0.4) ceramics were synthesized by a solid-state reaction at 1600 °C for 10 h. The phase compositions, microstructure, mechanical properties and thermophysical properties of (Yb1-xGdx)4Hf3O12 ceramics were investigated. Yb4Hf3O12 exhibited a δ-phase structure, while Gd3+ doped Yb4Hf3O12 had a defect fluorite structure. The Gd3+ doped Yb4Hf3O12 showed higher Vicker's hardness, fracture toughness and Young's modulus compared to Yb4Hf3O12. The thermal conductivities of (Yb1-xGdx)4Hf3O12 ceramics firstly decreased with increasing Gd3+ doping, but subsequently increased with further Gd3+ doping. The (Yb0.7Gd0.3)4Hf3O12 exhibited the lowest thermal conductivity of 1.33 W m-1·K-1 at 1200 °C. The thermal expansion coefficients (TECs) of Gd3+ doped Yb4Hf3O12 were higher than that of Yb4Hf3O12. The (Yb0.7Gd0.3)4Hf3O12 showed promising comprehensive properties, suggesting that it could be a potential candidate material for thermal/environmental barrier coatings (T/EBCs).

Effects of Gd3+-doping on the fabrication and performances of highly transparent (Lu,Gd)2O3:Eu solid-solution ceramics

By pre-treating and component design of the ceramic powders, cubic (Lu,Gd)2O3:Eu solid-solution ceramics with high optical quality were achieved by the solid-state reaction method combined with vacuum sintering. The effects of Gd3+ doping (x = 0.05–0.6) on powder characteristics, phase compositions, microstructures and optical performances of the (Lu0.95-xGdxEu0.05)2O3 ceramics were systematically investigated to obtain the optimum Gd3+ content. The results indicated that the incorporation of moderate amounts of Gd3+ (5–50 mol%) effectively promoted mass diffusion and grain growth during sintering. The 50 mol% Gd3+-doped Lu2O3:Eu transparent ceramic (using the powder calcined at 1200 °C) sintered at 1750 °C for 5 h exhibited the optimum transmittance of 77.0 % in the visible spectral region (∼1 mm in thickness), which was significantly higher than the reported transmittance of vacuum sintered (Lu,Gd)2O3:Eu ceramics (less than 65.0 %). Owing to the lower electronegativity of Gd3+ relative to Lu3+, the bandgap energies of the final ceramics decreased gradually with increasing Gd3+ substitution, and the redshift of the CTB centre was observed with more Gd3+ addition. Under CTB excitation, the incorporation of Gd3+ enhanced the red emission intensity and shortened the fluorescence lifetime.

Influence of Gd3+ Ions Substitution on the Structure and Properties of Bi-BTC for Photocatalysts

A novel material Bi1-xGdx-BTC was obtained in situ via the solvothermal method. The effects of Gd3+ substitution on the Bi-BTC structure and photocatalytic properties of Bi1-xGdx-BTC were investigated. A standard Bi-BTC structure was observed in the X-ray diffraction spectra of the Bi1-xGdx-BTC(x ≤ 0.07). However, some diffraction peaks were changed when the x is more than 0.07 due to the different ion radius. The developed Bi1-xGdx-BTC samples exhibited higher photocatalytic activity than the pure Bi-BTC material. In RhB degradation experiments, the Bi1-xGdx-BTC(x = 0.03 and x = 0.05) materials show degradation efficiency conversion of 71% within 60 min under visible light. The high photodegradation efficiency of Bi1-xGdx-BTC could be ascribed to efficient charge transfer between Bi(III) ions and Gd(III) ions. Moreover, an active species trapping experiment confirmed that photo-generated ·O2- and ·OH is the major species involved in RhB degradation.

Effects of Gd3+ and Ca2+ on Frog Heart Muscle Contractility and Respiration, Swelling and Inner Membrane Potential of Rat Heart Mitochondria

We studied the inotropic and chronotropic effects of gadolinium ions (Gd3+) on contractility of frog Rana ridibunda heart muscle preparations. In addition, the influence of Gd3+ on oxygen uptake rates, swelling and the mitochondrial inner membrane potential (ΔΨmito) were studied in glutamate- and malate-energized rat heart mitochondria (RHM). It was found that Gd3+ decreases the amplitude and frequency of spontaneous heart contractions. At the same time, Gd3+ prevents Ca2+-induced swelling of these organelles in saline media and falling of ΔΨmito. In this case, regardless of the presence of Ca2+ in the medium, Gd3+ has a weak effect on mitochondrial state 3 or 3UDNP respiration (in the presence of 2,4-dinitrophenol). In calcium free experiments, Gd3+ stimulates passive swelling of RHM. These effects of Gd3+ may indicate that Gd3+ has no toxic effect on RHM but, on the other hand, inhibits opening of the mitochondrial permeability transition pore (MPTP) in the inner membrane. Our data provide better insight into the mechanisms of action of rare earth elements on Ca2+-dependent processes in the myocardium of vertebrates.

ВЛИЯНИЕ Gd 3+ И Ca 2+ НА СОКРАТИМОСТЬ СЕРДЕЧНОЙ МЫШЦЫ ЛЯГУШКИ И ДЫХАНИЕ, НАБУХАНИЕ И ПОТЕНЦИАЛ ВНУТРЕННЕЙ МЕМБРАНЫ МИТОХОНДРИЙ СЕРДЦА КРЫСЫ

The inotropic and chronotropic effects of gadolinium ions (Gd3+) were studied in heart muscle preparations of the frog Rana ridibunda. In addition, the influence of Gd3+ on oxygen consumption rates, swelling and the inner membrane potential (∆Ψmito) were studied in glutamate and malate energized rat heart mitochondria (RHM). It was found that Gd3+ decreases the amplitude and frequency of spontaneous heart contractions. At the same time, Gd3+ prevents Ca2+ -induced swelling of these organelles in salt media and falling ∆Ψmito. In this case, regardless of the presence of Ca2+ in the medium, Gd3+ has a weak effect on mitochondrial state 3 or 3UDNP respiration (in the presence of 2,4-dinitrophenol). In calcium free experiments, Gd3+ stimulates passive swelling of RHM. These effects of Gd3+ may indicate that Gd3+ does not exert a toxic effect on RHM but, on the other hand, inhibits opening of the mitochondrial permeability transition pore (MPTP) in the inner membrane. Our data provide better insight into the mechanisms of action of rare earth elements on Ca2+ -dependent processes in the myocardium of vertebrates.

Enhanced photocatalytic activity of Gd3+ doped TiO2 and Gd2O3 modified TiO2 prepared via ball milling method

Gd3+/TiO2 and Gd2O3/TiO2 nanoparticles were prepared by ball milling method. The effects of Gd3+ ion and Gd2O3 on the structure and optical property of TiO2 were studied by XRD and UV-vis DRS. Specific surface area was determined by Brunauer-Emmett-Teller (BET) method. The morphology and elemental composition were characterized by SEM-EDS. XPS was used to determine the surface compositions and chemical character of elements. The sample sizes and microstructures were observed by TEM. The photocatalytic activities of TiO2 nanoparticles modified with rare earth metal gadolinium (Gd3+ ion or Gd2O3) were evaluated by degradation of methylene blue (MB) under UV light. Experimental results indicate that 2.5 mol% Gd3+/TiO2 shows the best photocatalytic activity compared with Gd2O3/TiO2 and pure TiO2. The existence of gadolinium can exhibit the aggregation and induce lattice distortion of TiO2 obtained from XRD, SEM and TEM results. The band gap energy of 2.5 mol% Gd3+/TiO2 decreases to 3.07 eV and it leads to visible light absorption response which can be seen from UV-vis absorption spectra. The surface area of 2.5 mol% Gd3+/TiO2 equals to 85.8 m2/g and average crystal size is 21.1 nm. EDS and XPS analyses reveal that gadolinium can be introduced either into TiO2 lattice or adsorbed on the surface of TiO2. The content of surface OH groups in 2.5 mol% Gd3+/TiO2 is 50.88% (1.55 times higher than that of pure TiO2) and the content of lattice oxygen decreases to 11.26%. The MB (25 mg/L) degradation reaction rate constants of 2.5 mol% Gd3+/TiO2, 0.5 mol% Gd2O3/TiO2 and pure TiO2 were 0.0713, 0.0588 and 0.0263 min−1, respectively. The degradation rates of rhodamine B (30 mg/L) in 60 min are 97.9%, 90.1% and 84.6% for 2.5 mol% Gd3+/TiO2, 0.5 mol% Gd2O3/TiO2 and pure TiO2, respectively.

Effects of Gd3+ codoping on the enhancement of the luminescent properties of a NaBi(MoO4)2:Eu3+ red-emitting phosphors

A series of NaBi(MoO4)2:Eu3+, Gd3+ phosphors were prepared using a sol-combustion method. NaBi(MoO4)2:Eu3+ with a tetragonal scheelite structure was obtained by heat treatment at 600–800 °C. The effects of the synthetic temperature and Eu3+ concentration on the luminescent properties of the NaBi(MoO4)2:Eu3+ phosphors were investigated. Under blue excitation at 464 nm, the NaBi(MoO4)2:Eu3+ sample exhibited a strong red emission peak at 618 nm, which originated from the 5D0→7F2 transition of Eu3+. Furthermore, Gd3+ ions were codoped into NaBi(MoO4)2:Eu3+ to enhance the luminescent intensity of NaBi(MoO4)2:Eu3+ due to energy transfer between Gd3+ and Eu3+. The results indicated that the NaBi(MoO4)2:Eu3+, Gd3+ red phosphor could be applied to white light-emitting diodes to achieve excellent properties, such as a high color rendering index and low correlated color temperature.

Magnetic anisotropy and magnetization enhancement of Gd3+-doped SmFeO3

Abstract The effects of Gd3+ ion doping on the lattice structure and magnetism properties of polycrystalline SmFeO3 were investigated by X-ray diffraction (XRD) and magnetic characterization. Both the magnetic susceptibility and saturation magnetization were significantly enhanced due to the larger spin number of Gd3+. The low doping sample of Sm0.95Gd0.05FeO3 showed great enhancement of magnetic energy product, which may be attributed to the local exchange of different grains.

Effects of Gd3+ doping on the microstructure and electrochemical properties of Li1.20[Mn0.54Ni0.13Co0.13]O2 as cathode for lithium-ion batteries

To enhance the electrochemical properties of the Mn-based lithium-rich layered cathode materials, Li1.20[Mn0.54−xGd x Ni0.13Co0.13]O2 (x = 0, 0.01, 0.02 and 0.03) were synthesized by using the carbonate co-precipitation method. The X-ray diffraction, scanning electron microscope, galvanostatic charge–discharge tests and electrochemical impedance spectroscopy techniques have been carried out to investigate the influences of the Gd3+ doping modification. And the results showed the lower cation mixing degree and superior electrochemical properties were obtained for the LMNCO by the Gd3+ doping. With the Gd3+ doping amount increasing, the capacity retentions after 100 cycles enhanced from 88.5 to 90.9% and then decrease to 86.7% with x = 0.01, 0.02 and 0.03, respectively. While the un-doped LMNCO only delivered the capacity retention of 85.1%. Besides, the discharge capacity of Li1.20[Mn0.52Gd0.02Ni0.13Co0.13]O2 was 29.4 mAh g−1 larger than that of un-doped sample at 5 C high rate. The electrochemical impedance spectroscopy results indicated that the Gd3+ doping modification could restrain the growth speed of charge transfer impedance of LMNCO during the charge and discharge process.

Study on the sensitization of Gd3 + on Ce3 +/Tb3 + co-doped GBS scintillating glass

The composition of the matrix glass has a significant effect on the luminescent property and density of the scintillating glass. In this paper, the Ce3+/Tb3+ co-doped Gd2O3-B2O3-SiO2 (GBS) scintillating glasses were melted in reducing atmosphere. The effects of Gd3+ on the luminescent property and density of scintillating glass were studied. The results show that increasing Gd3+ ions concentration can increase the density of the scintillating glass. The energy transfer from Gd3+ to Tb3+ in the glass can sensitizes the luminescence of Tb3+ ions. Meanwhile, the increase of Gd3+ ions concentration increases the optical basicity of the glass and the electrons on the Ce3+ ion 4f orbit are more likely to migrate to 5d orbit, which promotes the energy transfer from Ce3+ to Tb3+. However, the concentration of Gd3+ ions is too high to cause concentration quenching and Ce3+ ion charge transfer quenching, which are not conducive to the light of the glass.

Impact of Rare Earth Gd3+ Ions on Structural and Magnetic Properties of Ni0.5Zn0.5Fe2−x Gd x O4 Spinel Ferrite: Useful for Advanced Spintronic Technologies

In this article, we have synthesized the Gd3+-doped Ni0.5Zn0.5Fe2−x Gd x O4 (x = 0.05, 0.07, 1.0) ferrite samples using solid-state reaction route. The effects of Gd3+ doping on structural, vibrational, electrical and magnetic properties were studied. Structural and vibrational properties were characterized by x-ray diffraction (XRD), Raman, and FTIR spectroscopy. XRD data indicate that the Ni0.5Zn0.5Fe2−x Gd x O4 ceramics crystallize in single-phase spinel cubic (Fd3m space group) structure. Infrared spectra show two strong absorption bands in the frequency range of 400–600 cm−1 which were, respectively, attributed to tetrahedral and octahedral sites of the spinel ferrite. All the prepared samples show the typical dielectric dispersion having Maxwell–Wagner-type interfacial polarization. Decrease in dielectric constant and loss tangent has been observed with frequency and doping concentration. M − H plots reveal that all the samples exhibit ferrimagnetic nature at room temperature. A significant increase in the saturation magnetization has been observed upon the substitution of Gd3+ ions. All the as-prepared samples are isotropic and soft magnetic materials. These ferrite compounds are advantageous in advanced high-density data storage and high-frequency devices applications.

Cooperative Energy Transfer Up-/Down-Conversion Luminescence in Tb3+/Yb3+ Co-Doped Cubic Na5Lu9F32 Single Crystals by Gd3+ Co-Doping

The luminescence properties of Na5Lu9F32 single crystals tridoped Tb3+, Yb3+, and Gd3+ ions synthesized via a vertical Bridgman method were reported. Gd3+ was codoped as a sensitizer in Na5Lu9F32:Tb3+, Yb3+, thus increasing the absorption line-width and the absorption cross sections in the ultraviolet–visible region. Effects of Gd3+ concentration on the luminescence properties under ultraviolet and near-infrared were investigated. The energy transfer mechanism between the Gd3+and Tb3+ ion was witnessed by the detailed analyses of the excited-state lifetimes, emission quantum yields, and emission and excitation spectra for the Na5Lu9F32:Tb3+, Yb3+ single crystals codoping with various Gd3+ concentrations ranging from 0 to 0.25 mol %. Following the excitation light in ultraviolet region, Na5Lu9F32 single crystals tridoped Tb3+/Yb3+/Gd3+ showed dominant green emissions in the visible region and at 980 nm which were attributed to 5D4 → 7F5 transition of Tb3+ and 2D5/2 → 2F7/2 of Yb3+, respectively. Under the ...

Effects of Gd3+ modifications on the photoelectrochemical properties of TiO2-based dye-sensitized solar cells

In this paper, TiO2 particles (~30 nm) modified with Gd2O3-coating layer (~2 nm) for dye-sensitized solar cells (DSSCs) were fabricated via the hydrothermal method. Among the solar cells based on the Gd3+-doped TiO2 photoanodes, the optimal conversion efficiency was obtained from the 0.025Gd3+-modified TiO2-based cell, with a 17.7% improvement in the efficiency as compared to the unmodified one (7.18%). This enhancement was probably due to the improved UV radiation harvesting via a down-conversion luminescence process by Gd3+ ions, enhancement of visible light absorption and improved dye loading capacity. In addition, after Gd modification, a thin coating could be formed on the TiO2 nanoparticles, which worked as an energy barrier and resulted in a lower charge recombination.

Gadolinium/chloride co-doping of lithium vanadium phosphate cathodes for lithium-ion batteries

Lithium vanadium phosphate (LVP, Li3V2(PO4)3) composites co-doped with cations and anions were synthesized via a rheological phase method reaction. The effects of Gd3+–Cl− co-doping on the structure, morphology, and electrochemical performance of Li3V2(PO4)3 particles were then systematically investigated. This method of cation–anion co-doping did not change the structure of Li3V2(PO4)3. All co-doped samples exhibited better electrochemical performance than that of the undoped sample. The highest initial discharge capacity of co-doped samples was 169mAh/g and a capacity of 72.8mAh/g was obtained at 10C rate at 3.0–4.8V. This synergistic mechanism of anion–cation co-doping is a promising approach to optimize the performance of Li3V2(PO4)3.

Controlled synthesis and the effects of Gd3+ substitution, calcination, and particle size on photoluminescence of (Y0.95−xGdxTb0.05)2O3 green phosphor spheres

Uniform spheres are highly desired for the fabrication of advanced ceramics and as phosphor for lighting and display. Green emitting (Y0.95−xGdxTb0.05)2O3 phosphor spheres were successfully synthesized in this work via homogeneous precipitation, with particular emphases on size enlargement of the particles and the effects of particle size, Gd3+ incorporation and calcination on photoluminescence. Ammonium nitrate (NH4NO3) was originally used to effectively enlarge the precursor particles from ∼150±10 to 590±43nm, whose effects were found to tend to saturate at NH4NO3:rare-earth=1:1molar ratio. Size enlargement up to ∼630±57nm has also been achieved via a self-seeded growth approach. The optimal Gd3+ content for luminescence was determined to be 2at% (x=0.02) for the phosphors, and the spin-allowed 7F6→7DJ Tb3+ excitation at ∼278nm successively lowers at a higher Gd3+ content or calcination temperature owing to bandgap narrowing of the host lattice. Intensity of the 543nm green emission steadily improves with increasing temperature of calcination or particle size, and the lifetime of the 543nm emission, affected by particle size and calcination, falls in the range of ∼1.75–2.81ms. The phosphors have similar color coordinates of around (0.32,0.56), irrespective of the Gd content, particle size, and calcination temperature.

The effects of Gd3+ doping on the physical structure and photocatalytic performance of Bi2MoO6 nanoplate crystals

Gd3+ doped Bi2MoO6 nanoplate crystals were fabricated by solvothermal combined calcination method. The effects of Gd3+ doping with different concentrations on the texture, crystal and optical properties of Bi2MoO6 were investigated by N2 physical adsorption, X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR) and ultraviolet–visible diffuse reflection spectrum (UV–vis DRS), photoluminescence (PL) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Under simulated solar light irradiation, the influences of Gd3+doping on photocatalytic activity of Bi2MoO6 were evaluated by photocatalytic degradation of Rhodamine B. The characterization results showed that with Gd3+ doping, a contraction of lattice and a decrease in crystallite size occurred. Meanwhile, an increase in surface area over Gd3+ doped Bi2MoO6 was observed. Moreover, Gd3+ doping could obviously enhance the visible light harvesting of Bi2MoO6 and promoted the separation of photogenerated electrons and holes. With optimum Gd3+(6wt%) doping, Gd/Bi2MoO6 exhibited the best activity and stability in degradation of Rhodamine B.

Effects of Gd3+: Ag co-doping on structural and magnetic properties of lead tellurite glass ceramics

Lead tellurite glass ceramics doped with variable amounts of Gd3+ ions and co-doped with fixed amounts of silver (Ag2O or Ag metallic nanoparticles, AgNPs) have been prepared and investigated by X-ray diffraction (XRD), density, electron paramagnetic resonance (EPR) and magnetic susceptibility measurements. The EPR spectra of the studied samples exhibit the typical ‘‘U’’-type shape with effective g-values of ≈6, 2.8, 2.0 and a weaker feature at g≈4.8. At higher contents of Gd3+ ions the spectral features are broadened and finally are dominated by a broad absorption line located at g≈2.0 and a weaker feature at g≈6. The broad EPR line centered at g≈2.0 is associated to the Gd3+ ions present predominantly as clustered species. The paramagnetic susceptibility (χ) was measured at various temperatures and from the 1/χ versus T dependence the molar Curie constant (CM) and the paramagnetic Curie temperature (θp) have been evaluated. Magnetic susceptibility data show that for low Gd2O3 contents, x≤3mol%, the Gd3+ ions are randomly distributed in the host glass ceramics matrix and are present only as isolated species. For higher Gd2O3 contents, x>3mol%, the Gd3+ ions appear as both isolated and antiferromagnetically coupled species.

Upconversion luminescent materials of Y–Gd oxysulfide binary system codoped with Yb and Er

(Y1−xGdx)2O2S:0.08Yb/0.02Er powders doped with different concentrations of Gd3+ (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 and 1.0) were prepared by flux method. The effects of Gd3+ doping amount on the phase composition, the crystal structure, the luminescent intensity, the emission color, phonon energy and forbidden bandwidth of Y2O2S:Yb/Er were investigated by XRD, UPL, CIE, RAMAN and R%, respectively. (Y1−xGdx)2O2S:Yb/Er powders doped with different concentrations of Gd3+ were all pure oxysulfide phase. Upconversion luminescent intensity of (Y0.9Gd0.1)2O2S:Yb/Er was the maximum. Green and red emission intensity of Y2O2S:Yb/Er was increased by three times with doping 10 mol% Gd3+ ions. The emission color was basically yellow. Gd3+ ions optimized the crystal structure of Y2O2S, changed the crystal field of Er3+ and Yb3+ ions, and improved the upconversion luminescent properties.

Effects of Gd Substitution on Sintering and Optical Properties of Highly Transparent (Y0.95−xGdxEu0.05)2O3 Ceramics

Highly transparent (Y0.95−xGdxEu0.05)2O3 (x = 0.15–0.55) ceramics have been fabricated by vacuum sintering at the relatively low temperature of 1700°C for 4 h with the in‐line transmittances of 73.6%–79.5% at the Eu3+ emission wavelength of 613 nm (~91.9%–99.3% of the theoretical transmittance of Y1.34Gd0.6Eu0.06O3 single crystal), whereas the x = 0.65 ceramic undergoes a phase transformation at 1650°C and has a transparency of 53.4% at the lower sintering temperature of 1625°C. The effects of Gd3+ substitution for Y3+ on the particle characteristics, sintering kinetics, and optical performances of the materials were systematically studied. The results show that (1) calcining the layered rare‐earth hydroxide precursors of the ternary Y–Gd–Eu system yielded rounded oxide particles with greatly reduced hard agglomeration and the particle/crystallite size slightly decreases along with increasing Gd3+ incorporation; (2) in the temperature range 1100°C–1480°C, the sintering kinetics of (Y0.95−xGdxEu0.05)2O3 is mainly controlled by grain‐boundary diffusion with similar activation energies of ~230 kJ/mol; (3) Gd3+ addition promotes grain growth and densification in the temperature range 1100°C–1400°C; (4) the bandgap energies of the (Y0.95−xGdxEu0.05)2O3 ceramics generally decrease with increasing x; however, they are much lower than those of the oxide powders; (5) both the oxide powders and the transparent ceramics exhibit the typical red emission of Eu3+ at ~613 nm (the 5D0→7F2 transition) under charge transfer (CT) excitation. Gd3+ incorporation enhances the photoluminescence and shortens the fluorescence lifetime of Eu3+.

Mechanical control of cell biology. Effects of cyclic mechanical stretch on cardiomyocyte cellular organization

ObjectivesThe aim of our study was to elucidate how cyclic mechanical stretch is sensed by cardiomyocytes and in which way it affects cytoskeletal organization. MethodsNeonatal rat cardiomyocytes, cultured on flexible membranes, were subjected to cyclic mechanical stretch (1 Hz, 10% elongation) for 24 h using either round or rectangular loading posts for equibi-axial or uni-axial stretch, respectively, using the FlexCell stretch system. Cells were treated either with vehicle, the focal adhesion kinase (FAK) inhibitor PF-573,228 (200 nM), or the stretch-activated ion channel blocker gadolinium (Gd3+; 100 μM). ResultsCyclic mechanical stretch (36 mm diameter silicone membrane, equibi-axial stretch, 10% elongation, 1 Hz) induced elongation of the cardiomyocytes together with accentuation of Cx43 at the cell poles, and with an orientation of the cell axis between the radial axis and the circumferential axis (mean deviation: 11° from the circumference). Moreover, stretch resulted in ca. 1.4 fold increased Cx43 expression. FAK was found to be phosphorylated at the edges of the cells. In order to find out, how cardiomyocytes might sense stretch, we investigated possible effects of Gd3+and PF-573,228. Gd3+ had no effect on elongation or polarization and did not affect stretch-induced Cx43 expression. Interestingly, the FAK inhibitor completely antagonized the stretch-induced elongation, orientation and Cx43-polarization. However, the stretch-induced Cx43 expression was insensitive to this treatment. In order to clarify our result that the cells in equibi-axial stretch did not exactly organize to the circumference or to the radial axis, we decided to use a uni-axial stretch protocol. In uni-axially stretched cells, we found that the cardiomyocytes also showed elongation, Cx43 polarization, and orientation near to the stretch axis, but not exactly in the stretch axis but ca. 25° oblique to it. Furthermore, we investigated the tubular system, the Golgi apparatus, the SR and the nucleus. After 24 h stretch the microtubules were localized nearly (but not completely) parallel to the stretch axis (i.e. in longitudinal cell axis). Moreover, the localization of nucleus and the Golgi was also changed: while under static conditions, the Golgi was distributed more or less around the nucleus, after stretch the Golgi was accentuated at one site of the nucleus facing a cell pole with the nucleus facing the opposite cell pole. The plus motor protein kinesin accentuated at the cell poles and at the cell periphery, while the minus motor protein dynein was found near to the Golgi apparatus. ConclusionsThe stretch signal sensing is mediated via FAK and leads to intracellular re-organization and orientation. The oblique orientation of the cell with regard to the direction of stretch may define a directed force vector which could allow the cell to orientate.