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  • 1
    Electronic Resource
    Electronic Resource
    Energy-dependent deposition processes of size-selected Ag nanoclusters on highly-oriented pyrolytic graphite (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 9961-9966 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Singly charged cations of silver atoms and clusters (Agn+, n=1,3,5,7,9) were deposited on highly oriented pyrolytic graphite substrates at well-controlled, various collision energies. The total amount of Ag atoms remaining on the substrates after collision was quantified by measuring the Ag 3d5/2 photoelectron intensities. The collision energy dependence of the amount of deposited Ag atoms revealed that, for all the species, there are three distinct energy regions, for which soft landing, rebounding, or implantation is a dominant process, and that the energy ranges for the processes strongly depend on the cluster size. The deposition efficiency vs collision energy curve for each cluster is well fitted to that for Ag1, by considering the difference between the contact area of Ag1 with the surface and that of the cluster, reflecting the compactness of the clusters. Boundaries between the different deposition regimes for the clusters were less distinct than those for Ag1. Considering anisotropy in shape of a cluster, deposition efficiency around the implantation threshold was calculated, which well explains the indistinctness of the threshold observed in the experimental data. This supports the picture that the energy given to a unit surface area determines the collision process. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.481632
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  • 2
    Electronic Resource
    Electronic Resource
    Optical switching in polymer gels (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 131-136 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Soft materials have long been sought after for use in devices such as actuators, artificial muscles, separators, switches, sensors, memories, and so forth. We developed a soft, optically transparent material using polymer gels that can not only be activated by visible light (switched on) but also deactivated (switched off) by altering the local environment using three different means: pH, temperature, and light. This copolymer gel is a covalently cross-linked network of N-isopropylacrylamide, sodium acrylate, and a chromophore, which is found to undergo phase transitions exhibiting large hysteresis in the degree of swelling in response to pH, temperature, and light. In each system, between the transitions for swelling and shrinking, the gel can show either a swollen or a collapsed state, which can be selected according to the history of the variables. It has been established that a thermoresponsive gel with chromophore exhibits a local volume phase transition upon illumination with visible light. By making use of this phenomenon, we have successfully controlled the phase in which a gel exists with visible light: Without light illumination the gel stays in the swollen state. Upon illumination beyond a threshold intensity, however, a volume transition is locally induced, thereby forming a material in which both phases coexist stably for at least several hours after the light source has been removed. The phenomenological stability of the material in the coexistence state is discussed on the basis of the Landau theory. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.362768
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  • 3
    Electronic Resource
    Electronic Resource
    Bloch line propagation with film thickness modulation bit patterns (abstract) : 35th annual conference on magnetism and magnetic materials (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 5767-5767 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Bloch line (BL) propagation with a field-access scheme is necessary for the memory with low power consumption and high storage density. Previously we reported the field-access propagation using Co-Pt bit patterns.1 In these propagation patterns, (a) the drive field margins depend on the BL propagating direction to the magnetized direction of Co-Pt patterns and (b) the operating bias field margins are different at each corner of the stripe domain. The purpose of this paper is to solve these two problems. A new propagation method has been investigated using film thickness modulation patterns.2 The materials used here were magnetic bubble garnet films with composition of (YSmLuCa)3(FeGe)5O12. Fundamental characteristics of the samples are as follows: saturation induction 4πMs 200 G, anisotropy field Hk 1700 Oe, stripe width w and thickness h 5 μm. The thickness modulation patterns with an amplitude of about 1000 A were fabricated with the ion milling method. The stripe domains were stabilized around the 100% etched grooves, and aligned with 18 μm period. BL pair was propagated in the all part of the stripe domain walls at 500 kHz frequency, applying the triangular bias pulsed field with 50 ns rise time and 1000 ns fall time. As the result of the experiments, it has been found that the drive field margins are independent of BL propagation direction and the difference in the operating bias field margins at the each corner of the stripe domain becomes smaller. The BL propagation around the stripe domain was achieved with 5% bias field margin at the drive field of 8.5 Oe.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.347869
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  • 4
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    Discordant and heterogeneous expression of GPI-anchored membrane proteins on leukemic cells in a patient with paroxysmal nocturnal hemoglobinuria (1993)
    American Society of Hematology
    Details
    Publication Date: 1993-04-01
    Description: We performed a flow cytometric analysis using monoclonal antibodies to decay accelerating factor (DAF) and CD59/membrane attack complex inhibitory factor (CD59/MACIF) in order to investigate the leukemic cells and erythrocytes from a patient with paroxysmal nocturnal hemoglobinuria (PNH) who developed acute myelocytic leukemia. In May 1990, the leukemic cells comprised 70% of the mononuclear cells in the bone marrow and 76% of those in the peripheral blood. They consisted of a mixture of positive and negative populations, including single DAF- positive cells. In August 1990, almost 100% of the peripheral mononuclear cells were leukemic blasts, and these consisted of a single population with reduced DAF expression. Single-color flow cytometric analysis showed that the leukemic cells lacked CD59/MACIF, while control leukemic cells (n = 3) expressed both DAF and CD59/MACIF. Leukemic blasts from this patient and six control patients expressed lymphocyte function-associated antigen 3 and FcIII receptors (CD 16) both before and after treatment with phosphatidylinositol-specific phospholipase C. The patient's erythrocytes lacking DAF and CD59/MACIF expression corresponded to the proportion of complement-sensitive cells at the onset of acute leukemia. These DAF- and CD59/MACIF-deficient erythrocytes disappeared almost completely with progression of the leukemia. In conclusion, it appears that the expression of glycosylphosphatidylinositol-linked membrane proteins by leukemic cells was heterogeneous and discordant in our patient, and that the leukemic cells were derived from the PNH clone because of their deficiency of CD59/MACIF. It is also suggested that DAF could compete more effectively than CD59/MACIF for a limited number of anchor molecules available on the proliferating leukemic cells.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Published by American Society of Hematology
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  • 5
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    High expression of c-kit in K562YO cells due to the prolonged half-life of its mRNA: the effects of modification with serine/threonine kinase signals (1995)
    American Society of Hematology
    Details
    Publication Date: 1995-03-15
    Description: We previously reported that the K562 cell line K562YO expressed a high level of the c-kit gene. In this study, we analyzed the mechanism of this expression and investigated the effects of the serine/threonine kinases such as protein kinase C (PKC) and cyclic adenosine 3′,53′ monophosphate (cAMP)-dependent kinase (PKA) on it. The half-life of the c-kit mRNA in K562YO cells was greater than 10 hours, compared with 2 hours in the original K562 cells, which expressed a very low level of c- kit mRNA. This prolonged half-life can contribute to the high level of c-kit expression in K562YO cells. Cycloheximide (CHX), a protein synthesis inhibitor, caused increases in c-kit mRNA levels in K562YO cells. 12-O-tetradecanoylphorbol-13-acetate (TPA), by which PKC was activated at first and downregulated in a late phase, gradually decreased c-kit mRNA in K562YO cells until 9 hours and then returned to the control level 24 hours after treatment. TPA also rapidly decreased c-kit protein level on the membranes. In whole cells, c-kit protein was also decreased 6 hours after incubation with TPA. Calphostin C, a light- dependent PKC inhibitor, decreased c-kit mRNA levels within 30 minutes in a light-dependent manner. It also decreased c-kit protein in whole cells 2 hours after the addition. However, it increased the amount of c- kit protein on the cell surfaces. Dibutyryl cyclic AMP (dbc-AMP) increased c-kit mRNA as well as c-kit protein on membranes and in whole cells. Run-on transcriptional assay suggested that the agent (dbc-AMP) enhanced the transcription rate of the gene. These results suggest that c-kit protein on the membranes is downregulated by PKC activation and upregulated by PKC inhibition. In the whole cell lysate, c-kit proteins are decreased by PKC inhibition through downregulation of mRNA. On the other hand, the elevation of an intracellular cAMP level causes upregulation of both the mRNA and c-kit protein on membranes and in whole cells through enhanced transcription. Thus, c-kit gene expression is apparently modulated by PKC and PKA.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Published by American Society of Hematology
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  • 6
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    Interleukin-1 beta (IL-1 beta) induces thrombocytosis in mice: possible implication of IL-6 (1990)
    American Society of Hematology
    Details
    Publication Date: 1990-12-15
    Description: We administered recombinant human interleukin-1 beta (IL-1 beta), the common mediator of inflammation process, to C57B1/6 male mice (0.5 microgram, every 12 hours over five times) intraperitoneally and consequently induced a remarkable thrombocytosis. Day 1 was designated as the following day of the last injection in the morning. A significant thrombocytosis was observed on days 1 through 5 with a peak on day 2 (162 +/- 9 x 10(4)/mm3) compared with the control mice injected with heated IL-1 beta (101 +/- 11 x 10(4)/mm3). A striking increase in mean size of marrow megakaryocytes was noted on days 1 and 2. The incorporation of 75Se-selenomethionine into circulating platelets as a measure of platelet production was about 2.3 times higher in IL-1 beta-treated mice than in control mice. To determine which factor(s) is responsible for elicited thrombocytosis, the in vitro studies and bioassays for several hematopoietic factors were performed. IL-1 beta by itself did not stimulate megakaryocytopoiesis in vitro, suggesting that the thrombocytosis is attributed to other factor(s) via IL-1 beta stimulation. Serum colony-stimulating factor (CSF) activity after a single IL-1 beta (0.5 microgram) injection, monitored by colony assay with 10% tested serum, peaked at 3 hours. Formed colonies were mostly granulocyte (G) and granulocyte-macrophage (GM)-types, and studies using rabbit anti-mouse GM-CSF serum or using human marrow as target cells showed that the CSF activity of the tested serum consisted of, at least, GM-CSF and G-CSF. Addition of IL-3 concomitantly with the tested serum gave rise to a greater number of megakaryocytic colonies. Serum IL-3, monitored by IL-3-dependent cell line 32D clone 5, and erythropoietin activities were not detected at serum level in IL-1 beta-treated mice. Serum IL-6 assay by IL-6- dependent mouse hybridoma cell line MH-60.BSF2 showed high levels of the tested serum with a peak at 2.5 hours with no detection at 10 hours after the injection. Heated IL-1 beta caused an increase of neither IL- 6 nor CSF activities. Our data suggest that the thrombocytosis induced by IL-1 beta is mediated by IL-6 or a combination of IL-6 and other cytokine(s), and that IL-6 may play a regulatory role in platelet production in vivo.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Published by American Society of Hematology
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  • 7
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    Effect of recombinant granulocyte-macrophage colony-stimulating factor on murine thrombocytopoiesis in vitro and in vivo (1990)
    American Society of Hematology
    Details
    Publication Date: 1990-04-01
    Description: To investigate the effect of recombinant granulocyte-macrophage colony- stimulating factor (rGM-CSF) on murine megakaryocytopoiesis in vitro, the factor was added to both serum-free colony assays and liquid marrow cultures. GM-CSF had a significant megakaryocytic colony-stimulating activity. After 2 hours of preincubation with and without 10 ng/mL rGM- CSF, the percentage of megakaryocyte colony-forming cell (CFU-MK) in DNA synthesis was determined by tritiated-thymidine suicide using colony growth. The reduction of CFU-MK colony numbers in marrow culture was 47.5% +/- 9.9%, 20.9% +/- 5.2% (control), respectively, indicating that the factor affected cell cycle at CFU-MK levels. When acetylcholinesterase (AchE) production was measured fluorometrically after 4 days of liquid culture, rGM-CSF elicited an increase in AchE activity in a dose-dependent fashion. To determine if the hematopoietin acts directly on megakaryocytic differentiation, 2 ng/mL rGM-CSF was added to serum-free cultures of 295 single megakaryocytes isolated from CFU-MK colonies. An increase in size was observed in 65% of cells initially 10 to 20 microns in diameter, 71% of cells 20 to 30 microns, and 40% of cells greater than 30 microns. Conversely, in absence of GM- CSF, 17%, 31%, and 10% of cells in each group increased in diameter. These data suggest that rGM-CSF promotes murine megakaryocytopoiesis in vitro and that the response to the factor is direct. To determine if the factor influences megakaryocytic/thrombocytic lineage in vivo, 1 and 5 micrograms of rGM-CSF were administered intraperitoneally every 12 hours for 6 consecutive days. Although a two- to three-fold increase in peripheral granulocytes was observed, neither megakaryocytic progenitor cells or platelets changed. Histologic analysis of bone marrow megakaryocytes showed no increase in size and number. The in vivo studies demonstrated no effect of GM-CSF on thrombocytopoiesis. The discrepancies between the in vitro and in vivo effects of GM-CSF require additional investigations.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Published by American Society of Hematology
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  • 8
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    Discordant and heterogeneous expression of GPI-anchored membrane proteins on leukemic cells in a patient with paroxysmal nocturnal hemoglobinuria (1993)
    American Society of Hematology
    Details
    Publication Date: 1993-04-01
    Description: We performed a flow cytometric analysis using monoclonal antibodies to decay accelerating factor (DAF) and CD59/membrane attack complex inhibitory factor (CD59/MACIF) in order to investigate the leukemic cells and erythrocytes from a patient with paroxysmal nocturnal hemoglobinuria (PNH) who developed acute myelocytic leukemia. In May 1990, the leukemic cells comprised 70% of the mononuclear cells in the bone marrow and 76% of those in the peripheral blood. They consisted of a mixture of positive and negative populations, including single DAF- positive cells. In August 1990, almost 100% of the peripheral mononuclear cells were leukemic blasts, and these consisted of a single population with reduced DAF expression. Single-color flow cytometric analysis showed that the leukemic cells lacked CD59/MACIF, while control leukemic cells (n = 3) expressed both DAF and CD59/MACIF. Leukemic blasts from this patient and six control patients expressed lymphocyte function-associated antigen 3 and FcIII receptors (CD 16) both before and after treatment with phosphatidylinositol-specific phospholipase C. The patient's erythrocytes lacking DAF and CD59/MACIF expression corresponded to the proportion of complement-sensitive cells at the onset of acute leukemia. These DAF- and CD59/MACIF-deficient erythrocytes disappeared almost completely with progression of the leukemia. In conclusion, it appears that the expression of glycosylphosphatidylinositol-linked membrane proteins by leukemic cells was heterogeneous and discordant in our patient, and that the leukemic cells were derived from the PNH clone because of their deficiency of CD59/MACIF. It is also suggested that DAF could compete more effectively than CD59/MACIF for a limited number of anchor molecules available on the proliferating leukemic cells.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Published by American Society of Hematology
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  • 9
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    Effect of recombinant granulocyte-macrophage colony-stimulating factor on murine thrombocytopoiesis in vitro and in vivo (1990)
    American Society of Hematology
    Details
    Publication Date: 1990-04-01
    Description: To investigate the effect of recombinant granulocyte-macrophage colony- stimulating factor (rGM-CSF) on murine megakaryocytopoiesis in vitro, the factor was added to both serum-free colony assays and liquid marrow cultures. GM-CSF had a significant megakaryocytic colony-stimulating activity. After 2 hours of preincubation with and without 10 ng/mL rGM- CSF, the percentage of megakaryocyte colony-forming cell (CFU-MK) in DNA synthesis was determined by tritiated-thymidine suicide using colony growth. The reduction of CFU-MK colony numbers in marrow culture was 47.5% +/- 9.9%, 20.9% +/- 5.2% (control), respectively, indicating that the factor affected cell cycle at CFU-MK levels. When acetylcholinesterase (AchE) production was measured fluorometrically after 4 days of liquid culture, rGM-CSF elicited an increase in AchE activity in a dose-dependent fashion. To determine if the hematopoietin acts directly on megakaryocytic differentiation, 2 ng/mL rGM-CSF was added to serum-free cultures of 295 single megakaryocytes isolated from CFU-MK colonies. An increase in size was observed in 65% of cells initially 10 to 20 microns in diameter, 71% of cells 20 to 30 microns, and 40% of cells greater than 30 microns. Conversely, in absence of GM- CSF, 17%, 31%, and 10% of cells in each group increased in diameter. These data suggest that rGM-CSF promotes murine megakaryocytopoiesis in vitro and that the response to the factor is direct. To determine if the factor influences megakaryocytic/thrombocytic lineage in vivo, 1 and 5 micrograms of rGM-CSF were administered intraperitoneally every 12 hours for 6 consecutive days. Although a two- to three-fold increase in peripheral granulocytes was observed, neither megakaryocytic progenitor cells or platelets changed. Histologic analysis of bone marrow megakaryocytes showed no increase in size and number. The in vivo studies demonstrated no effect of GM-CSF on thrombocytopoiesis. The discrepancies between the in vitro and in vivo effects of GM-CSF require additional investigations.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Published by American Society of Hematology
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  • 10
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    Interleukin-1 beta (IL-1 beta) induces thrombocytosis in mice: possible implication of IL-6 (1990)
    American Society of Hematology
    Details
    Publication Date: 1990-12-15
    Description: We administered recombinant human interleukin-1 beta (IL-1 beta), the common mediator of inflammation process, to C57B1/6 male mice (0.5 microgram, every 12 hours over five times) intraperitoneally and consequently induced a remarkable thrombocytosis. Day 1 was designated as the following day of the last injection in the morning. A significant thrombocytosis was observed on days 1 through 5 with a peak on day 2 (162 +/- 9 x 10(4)/mm3) compared with the control mice injected with heated IL-1 beta (101 +/- 11 x 10(4)/mm3). A striking increase in mean size of marrow megakaryocytes was noted on days 1 and 2. The incorporation of 75Se-selenomethionine into circulating platelets as a measure of platelet production was about 2.3 times higher in IL-1 beta-treated mice than in control mice. To determine which factor(s) is responsible for elicited thrombocytosis, the in vitro studies and bioassays for several hematopoietic factors were performed. IL-1 beta by itself did not stimulate megakaryocytopoiesis in vitro, suggesting that the thrombocytosis is attributed to other factor(s) via IL-1 beta stimulation. Serum colony-stimulating factor (CSF) activity after a single IL-1 beta (0.5 microgram) injection, monitored by colony assay with 10% tested serum, peaked at 3 hours. Formed colonies were mostly granulocyte (G) and granulocyte-macrophage (GM)-types, and studies using rabbit anti-mouse GM-CSF serum or using human marrow as target cells showed that the CSF activity of the tested serum consisted of, at least, GM-CSF and G-CSF. Addition of IL-3 concomitantly with the tested serum gave rise to a greater number of megakaryocytic colonies. Serum IL-3, monitored by IL-3-dependent cell line 32D clone 5, and erythropoietin activities were not detected at serum level in IL-1 beta-treated mice. Serum IL-6 assay by IL-6- dependent mouse hybridoma cell line MH-60.BSF2 showed high levels of the tested serum with a peak at 2.5 hours with no detection at 10 hours after the injection. Heated IL-1 beta caused an increase of neither IL- 6 nor CSF activities. Our data suggest that the thrombocytosis induced by IL-1 beta is mediated by IL-6 or a combination of IL-6 and other cytokine(s), and that IL-6 may play a regulatory role in platelet production in vivo.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Published by American Society of Hematology
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