Temperature and layer thickness dependent in situ investigations on epindolidione organic thin-film transistors.

We report on in situ performance evaluations as a function of layer thickness and substrate temperature for bottom-gate, bottom-gold contact epindolidione organic thin-film transistors on various gate dielectrics. Experiments were carried out under ultra-high vacuum conditions, enabling quasi-simultaneous electrical and surface analysis. Auger electron spectroscopy and thermal desorption spectroscopy (TDS) were applied to characterize the quality of the substrate surface and the thermal stability of the organic films. Ex situ atomic force microscopy (AFM) was used to gain additional information on the layer formation and surface morphology of the hydrogen-bonded organic pigment. The examined gate dielectrics included SiO2, in its untreated and sputtered forms, as well as the spin-coated organic capping layers poly(vinyl-cinnamate) (PVCi) and poly((±)endo,exo-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid, diphenylester) (PNDPE, from the class of polynorbornenes). TDS and AFM revealed Volmer-Weber island growth dominated film formation with no evidence of a subjacent wetting layer. This growth mode is responsible for the comparably high coverage required for transistor behavior at 90-95% of a monolayer composed of standing molecules. Surface sputtering and an increased sample temperature during epindolidione deposition augmented the surface diffusion of adsorbing molecules and therefore led to a lower number of better-ordered islands. Consequently, while the onset of charge transport was delayed, higher saturation mobility was obtained. The highest, bottom-contact configuration, mobilities of approximately 2.5 × 10-3cm2/Vs were found for high coverages (50 nm) on sputtered samples. The coverage dependence of the mobility showed very different characteristics for the different gate dielectrics, while the change of the threshold voltage with coverage was approximately the same for all systems. An apparent decrease of the mobility with increasing coverage on the less polar PNDPE was attributed to a change in molecular orientation from upright standing in the thin-film phase to tilted in the bulk phase. From temperature-dependent mobility measurements we calculated activation barriers for the charge transport between 110 meV and 160 meV, depending on the dielectric configuration.

Optimizing pentacene thin-film transistor performance: Temperature and surface condition induced layer growth modification.

In this work we present in situ electrical and surface analytical, as well as ex situ atomic force microscopy (AFM) studies on temperature and surface condition induced pentacene layer growth modifications, leading to the selection of optimized deposition conditions and entailing performance improvements. We prepared p++-silicon/silicon dioxide bottom-gate, gold bottom-contact transistor samples and evaluated the pentacene layer growth for three different surface conditions (sputtered, sputtered + carbon and unsputtered + carbon) at sample temperatures during deposition of 200 K, 300 K and 350 K. The AFM investigations focused on the gold contacts, the silicon dioxide channel region and the highly critical transition area. Evaluations of coverage dependent saturation mobilities, threshold voltages and corresponding AFM analysis were able to confirm that the first 3-4 full monolayers contribute to the majority of charge transport within the channel region. At high temperatures and on sputtered surfaces uniform layer formation in the contact-channel transition area is limited by dewetting, leading to the formation of trenches and the partial development of double layer islands within the channel region instead of full wetting layers. By combining the advantages of an initial high temperature deposition (well-ordered islands in the channel) and a subsequent low temperature deposition (continuous film formation for low contact resistance) we were able to prepare very thin (8 ML) pentacene transistors of comparably high mobility.

In situ preparation, electrical and surface analytical characterization of pentacene thin film transistors.

The fabrication of organic thin film transistors with highly reproducible characteristics presents a very challenging task. We have prepared and analyzed model pentacene thin film transistors under ultra-high vacuum conditions, employing surface analytical tools and methods. Intentionally contaminating the gold contacts and SiO2 channel area with carbon through repeated adsorption, dissociation, and desorption of pentacene proved to be very advantageous in the creation of devices with stable and reproducible parameters. We mainly focused on the device properties, such as mobility and threshold voltage, as a function of film morphology and preparation temperature. At 300 K, pentacene displays Stranski-Krastanov growth, whereas at 200 K fine-grained, layer-like film growth takes place, which predominantly influences the threshold voltage. Temperature dependent mobility measurements demonstrate good agreement with the established multiple trapping and release model, which in turn indicates a predominant concentration of shallow traps in the crystal grains and at the oxide-semiconductor interface. Mobility and threshold voltage measurements as a function of coverage reveal that up to four full monolayers contribute to the overall charge transport. A significant influence on the effective mobility also stems from the access resistance at the gold contact-semiconductor interface, which is again strongly influenced by the temperature dependent, characteristic film growth mode.

[Fibronectin and insulin-like growth factor-1 in pathogenesis of open-angle and pseudoexfoliative glaucoma].

The aim of the present investigation was to study the role of fibronectin and insulin-like growth factor-1 (IGF-1) in pathogenesis of primary open-angle and pseudoexfoliative glaucoma. Immune enzyme analysis was performed on aqueous humour of 480 patients with complicated cataracts on the background of primary open-angle and pseudoexfoliative glaucoma. The aqueous humour of patients with senile cataracts was used as control. The content of fibronectin and IGF-1 in aqueous humour was determined using appropriate kits (DRG-International Inc., USA) in the absorbance wavelength range 420-450 nm. The obtained results were analyzed using Student's criteria and application of SPSS-13/80. Relatively high levels of fibronectin and IGF-1 were recorded in aqueous humour of patients with complicated cataracts (cataracts on the background of open-angle and pseudoexfoliative glaucoma), as compared to indices of both cytokines in the aqueous humour of control group patients. In mechanisms of eye drainage function impairment and intraocular pressure increase an important role belongs to in situ (i.e. in the eye membranes) produced fibronectin and IGF-1.

[Disorders of ion balance in intraocular liquid at patients with senile and complicated cataracts].

Nowadays the regional mechanisms underlying disorders of drainage function and the increased intraocular pressure at various types of glaucoma are the subject of wide discussion in ophthalmology. In the specified aspect and to this day there are no comprehensive data concerning the roles of the broken ion exchange in hydrostatic systems of an eye, in particular, potassium-sodium pomp in mechanisms of ophtalmohypertension induction. The object of research was intraocular liquid of patients with the senile and complicated cataracts proceeding on the background of anterior open-angle glaucoma, pseudoexfoliative glaucoma, cataracts proceeding on the background of idiopathic hypertension, diabetes and the previous trauma. Samples of intraocular liquid were subjected to ion-selective analysis for definition of sodium, calcium and potassium ions content that was expressed in mmol/L. The analyzer Kone-microlyte (Finland) was used at definition of ionic composition. Program coefficient was defined using the refractometer of Shibuya Optical CO (Japan). The results were subjected to the statistical analysis using Student's criteria, with application of computer program SPSS version 13 ANOVA. At the cataract proceeding on the background of anterior open-angle glaucoma and pseudoexfoliative glaucoma in intraocular liquid relatively high indexes of the diffraction index and level of sodium and calcium ions were registered on the background of potassium ions decreased content. At the complicated cataracts: the cataract proceeding on the background of open-angle glaucoma and pseudoexfoliative cataract, in intraocular liquid the alterations in its protein and ionic composition are found to be considered as the risk factors resulting in disorders of drainage function and increase of intraocular pressures.

[Post-operational acute inflammation of an eye in patients with cataracts].

Despite the implementation of the newest highly efficient equipment into the practice of modern clinical ophthalmology, improvement of technical skills of ophthalmologist surgeons, the cases of post-operational acute endophthalmitis development, toxic syndrome of anterior segment of an eye, reactive aseptic inflammatory process are rather negatively reflected in the course of a post-operational process of rehabilitation. Under our supervision there were 1100 patients with the senile and complicated cataracts, who underwent operational intervention microcoaxial phacoemulsification. Differential diagnostics was carried out on the basis of the standard objective and subjective methods of research accepted in ophthalmology. On the basis of obtained data is found that clinical symptomatology of autoimmune aseptic anterior uveitis, in particular, the eye inflammation associated with the broken syndrome of an eye anterior chamber-associated immune deviation (ACAID), considerably differs from clinical implications of acute endophthalmitis and a toxic syndrome of the anterior chamber of an eye. In overwhelming majority of cases under the complicated cataracts, precisely the autoimmune aseptic inflammatory process, which originated due to withdrawal of regional immune reactions responsible for ACAID, was observed in postoperative period.

[Post-operational acute iridocyclitis and immune shifts in intraocular humor of patients with cataracts].

The negative tendency of cataracts growth, which is a consequence of various diseases of the organism including those of eyes, combined in the concept "the complicated cataract" is clearly traced now. In the concept of such a complication of cataracts as the acute autoimmune iridocyclitis, the important role, in our opinion, should be given to regional immunopathological disorders, which testify to the withdrawal of the known phenomenon underlying in the immunological tolerance of post-barrier eye membrane "a syndrome of eye anterior chamber-associated immune deviation (ACAID). Microcoaxial phacoemulsification was carried in three hundred patients with senile and complicated cataracts. The intraocular humor of the operated patients was subjected to immune-enzyme immunomorphological analysis for СD4, СD8, IgG and B-lymphocytic populations. On the base of performed clinical-laboratory research we found that the gravest inflammatory process in eye tissues manifested in the form of autoimmune aseptic iridocyclitis was observed particularly in patients with complicated cataracts, proceeding on the background of glaucoma, diabetes and the previous trauma of an eye. The high indicators of IgG, СD4 were registered on the background of low СD8 indicators in the intraocular humour at these patients. The revealed regional inflammatory reaction in eye tissues testifies, in our opinion, in favour of in situ withdrawal of ACAID; this latter brings to origination of acute aseptic autoimmune iridocyclitis in the early post-operational course of the complicated cataracts.

AFM, ellipsometry, XPS and TEM on ultra-thin oxide/polymer nanocomposite layers in organic thin film transistors.

Here we report on the fabrication and characterization of ultra-thin nanocomposite layers used as gate dielectric in low-voltage and high-performance flexible organic thin film transistors (oTFTs). Reactive sputtered zirconia layers were deposited with low thermal exposure of the substrate and the resulting porous oxide films with high leakage currents were spin-coated with an additional layer of poly-alpha-methylstyrene (P alphaMS). After this treatment a strong improvement of the oTFT performance could be observed; leakage currents could be eliminated almost completely. In ellipsometric studies a higher refractive index of the ZrO(2)/P alphaMS layers compared to the "as sputtered" zirconia films could be detected without a significant enhancement of the film thickness. Atomic force microscopy (AFM) measurements of the surface topography clearly showed a surface smoothing after the P alphaMS coating. Further studies with X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) also indicated that the polymer definitely did not form an extra layer. The polymer chains rather (self-)assemble in the nano-scaled interspaces of the porous oxide film giving an oxide-polymer "nanocomposite" with a high oxide filling grade resulting in high dielectric constants larger than 15. The dielectric strength of more than 1 MV cm(-1) is in good accordance with the polymer-filled interspaces.

Study on tip-substrate interactions by STM and APFIM.

Processes occurring at the interface of two materials coming in contact, separating or moving with respect to each other have been studied with the scanning tunnelling microscope (STM) and atom-probe (AP) field ion microscopy (APFIM). STM probe tips have been first characterised by field ion microscopy (FIM), brought into well-defined contact in the STM and afterwards inspected by time-of-flight AP. The results from mechanical contact and indentation experiments, showing material transfer and neck formation, are in reasonable good agreement with computer-based simulations on metal tip-surface interactions.

[The persistence of Ureaplasma and its arthritogenic action in the experimental infection of rabbits]. / Persistentsiia ureaplazm i ikh artritogennoe deistvie pri éksperimental'nom infitsirovanii krolikov.

In the experimental intraperitoneal infection of rabbits with U. urealyticum, serotype VIII, transitory polyarthritis with immunomorphological characteristics different from those of human rheumatoid arthritis has been shown to develop in the animals. The pathological process develops simultaneously with Ureaplasma infection. U. urealyticum persists in the body of infected rabbits during 12 weeks of observation. The mechanism of the resorption process in the bone tissue of joints, running similarly to periosteocytic osteolysis, is discussed.

[Mast-cell mechanism of the pathogenesis of bronchial asthma and peroxidation of membrane lipids]. / Tuchnokletochnyi mekhanizm patogeneza bronkhial'noi astmy i perekisnoe okislenie membrannykh lipidov.

Examination of 155 patients with atopic, infection-dependent bronchial asthma (BA) and chronic asthmatic bronchitis in the phase of the disease exacerbation and remission has shown that hyperhistaminemia is common not only to atopic but also to infection-dependent BA. It is established that activation of lipid peroxidation of the membranes more pronounced during exacerbation and attacks of asthma is one of the most important alternative mechanisms of mast cell activation, that is supported by the data of experimental morphologic and biochemical studies of the effect exerted by peroxidized fatty acids on histamine liberation and mast cell degranulation.

[Mycoplasma arthritis in man and mechanisms of its pathogenesis]. / Mikoplazmennye artrity cheloveka i nekotorye mekhanizmy ikh patogeneza.

Possible etiologic contribution of mycoplasma to human rheumatoid arthritis (RA) is supported by their recovery from synovial fluid of RA patients, as well as Mycoplasma antigens and antibodies detection in the bloodstream. The detectability of free antigens of M. arthritidis (Ma) and M. fermentans (Mf) in the sera of patients was 22.4%, and that of antibodies against those, 52.7%. Considerable difference between the detectability of Mycoplasma antigens and antibodies can be attributed to the fact that the bulk of the antigens form part of immune complexes and cannot be detected by serologic tests. Mitogenic effect of arthritogenic Mycoplasma and their ability to produce a cytotoxic effect on various cells, including lymphocytes, appears to be a mechanism of immune process developing in association with human RA. A study of immunobiological properties of individual Ma and Mf cell components has shown that a protein factor translocated into the culture medium is responsible for mitogenic action. Ma cytotoxicity in respect of target cells is related to its cytoplasmatic membrane. Mf produces a factor, acting directly on rat lymphocytes; its synthesis is apparently taking place on the cell membrane.

[Cytotoxic action of the individual membrane components of Mycoplasma arthritidis and M. fermentans on rat lymphocytes]. / Tsitotoksicheskoe deistvie otdel'nykh komponentov membran Mycoplasma arthritidis i M. fermentans na limfotsity krys.

Study of the toxic properties of the preparations obtained from M. arthritidis has revealed that the cytotoxic activity of M. arthritidis is mainly linked with the cytoplasmic membrane and, partially, with the cytoplasmic fraction. The membrane substances of M. fermentans and the products of its vital activity are toxic with respect to target cells, the component translocated into the culture medium consisting of globular proteins. Interaction of the cytoplasmic membranes of these Mycoplasma species, as well as of the fractions of M. fermentans globular proteins, with rat lymphocytes is accompanied by a cytodestructive effect and an increased permeability for toxic dyes.

[Effect of an external electrostatic field on catecholamine secretion by rat adrenals]. / Vliianie vneshnego élektrostaticheskogo polia na sekretsiiu katekholaminov nadpochechnikami krys.

Experimental rats were exposed to an electrostatic field of 200 kW/m for 1, 24 or 6 hours a day for 6 days. The effect of this exposure on the structure and function of adrenal chromaffin bodies and the concentration of catecholamines and their precursors in blood and adrenals was investigated. Using histochemical, fluorescent-microscopic and spectrofluorimetric methods, it was found that the exposure may modify the structure and function of adrenal chromaffins and the concentration of catecholamines in blood and adrenals. These changes depended on the exposure time. An hour exposure activated the secretory apparatus of adrenal chromaffins and enhanced catecholamine secretion to blood. A 24-hour exposure led to an increase in the concentration of catecholamines in adrenals and blood and a change in the organ cytoangioarchitectonics. A 6-day fractionated exposure resulted in a decrease of catecholamines both in blood and adrenals.

[Experimental polyarthritis in rabbits induced by Mycoplasma fermentans]. / Eksperimental'nyi poliartrit krolikov, vyzvannyi Mycoplasma fermentans.

The time course of the distribution of M. fermentans antigen in the body of rabbits infected by a single intraperitoneal injection, as well as morphological and immunological changes occurring in the joints of the infected animals during 12 weeks of observation have been studied. M. fermentans, or its antigen, has been shown to persist mainly in immunocompetent organs and articular tissues, its localization in articular cartilage corresponding to the areas of dystrophic changes. The character of the pathological process in the joints is similar to rheumatoid arthritis in humans, which is confirmed by the results of immuno-morphological studies. The local synthesis of IgG and rheumatoid factor, the deposition of immune complexes and the presence of phagocytes in synovia have been detected.

[Comparative characteristics of joint changes in rats infected with Mycoplasma fermentans and Mycoplasma arthritidis]. / Sravnitel'naia kharakteristika sustavnykh izmenenii u krys, infitsirovannykh Mycoplasma fermentans i Mycoplasma arthritidis.

Experiments on Wistar rats have shown that a single injection of M. fermentans or M. arthritidis causes various forms of polyarthritis differing in their course and morphological characteristics. M. arthritidis causes acute purulent arthritis. M. fermentans causes polyarthritis characterized mainly by a subacute course and early involvement of the articular cartilage. Plasma cells producing a factor similar to the rheumatoid factor of humans have been detected in the synovial membrane.