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  1. Article ; Online: Effect of environmental parameters on the nano mechanical properties of hyaluronic acid/poly(l-lysine) multilayers.

    Hellwig, Johannes / Strebe, Julia / V Klitzing, Regine

    Physical chemistry chemical physics : PCCP

    2018  Volume 20, Issue 28, Page(s) 19082–19086

    Abstract: Atomic force microscopy (AFM) was used to determine the mechanical properties as the indentation modulus of native and crosslinked poly(l-lysine) (PLL)/hyaluronic acid (HA) multilayer films by static force measurements. The influence of the surrounding ... ...

    Abstract Atomic force microscopy (AFM) was used to determine the mechanical properties as the indentation modulus of native and crosslinked poly(l-lysine) (PLL)/hyaluronic acid (HA) multilayer films by static force measurements. The influence of the surrounding medium on the mechanical properties of the films after preparation is investigated. The indentation modulus of native and crosslinked film was measured at different pH values, ionic strengths and temperatures. The native HA/PLL films, which behave like a physical gel, show the highest values of the indentation modulus for an intermediate pH value and low ionic strength. Any changes in the pH or an increase in the ionic strength/temperature decreases the measured indentation modulus. In contrast, the crosslinked films show an increase by a factor of 80 in the indentation modulus but no response to changes in the pH, ionic strength or temperature; they behave like a chemical gel. The pH, ionic strength and temperature used in this work are close to the in vivo conditions and thus give a fundamental point of view on the nanomechanical response of the PLL/HA films. Furthermore, information about the mechanical properties can be used for the understanding and manipulation of cell adhesion.
    MeSH term(s) Biomechanical Phenomena ; Environment ; Hyaluronic Acid/chemistry ; Polylysine/chemistry
    Chemical Substances Polylysine (25104-18-1) ; Hyaluronic Acid (9004-61-9)
    Language English
    Publishing date 2018-07-18
    Publishing country England
    Document type Journal Article
    ZDB-ID 1476244-4
    ISSN 1463-9084 ; 1463-9076
    ISSN (online) 1463-9084
    ISSN 1463-9076
    DOI 10.1039/c8cp02621a
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Separation of Storage and Loss Modulus of Polyelectrolyte Multilayers on a Nanoscale: A Dynamic AFM Study.

    Hellwig, Johannes / Micciulla, Samantha / Strebe, Julia / von Klitzing, Regine

    Langmuir : the ACS journal of surfaces and colloids

    2016  Volume 32, Issue 41, Page(s) 10505–10512

    Abstract: Atomic force microscopy (AFM) is used to carry out rheology measurements on the nanoscale and to determine the mechanical properties of poly(l-lysine) (PLL)/hyaluronic acid (HA) multilayer films. Storage (G') and loss modulus (G″) of the films are ... ...

    Abstract Atomic force microscopy (AFM) is used to carry out rheology measurements on the nanoscale and to determine the mechanical properties of poly(l-lysine) (PLL)/hyaluronic acid (HA) multilayer films. Storage (G') and loss modulus (G″) of the films are calculated and compared with the values obtained from quartz crystal microbalance with dissipation monitoring measurements (QCM-D). A predominant elastic behavior independently of the applied frequencies (5-100 Hz) is observed for native HA/PLL films consisting of 36 double layer. If the layers are cross-linked, the value of G' increases by 2 orders of magnitude, while the loss modulus becomes negligible, making these films a purely elastic chemical gel. The values of G' and G'' extracted from QCM-D measurements on native films are much higher, due to the different frequency regime of the applied shear stress. However, the viscoelastic ratio from the two methods is the same and proves the elastic dominated response of the multilayer in both frequency regimes.
    Language English
    Publishing date 2016-10-04
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2005937-1
    ISSN 1520-5827 ; 0743-7463
    ISSN (online) 1520-5827
    ISSN 0743-7463
    DOI 10.1021/acs.langmuir.6b02764
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Interlayer Coupling of a Two-Dimensional Kondo Lattice with a Ferromagnetic Surface in the Antiferromagnet CeCo

    Poelchen, Georg / Rusinov, Igor P / Schulz, Susanne / Güttler, Monika / Mende, Max / Generalov, Alexander / Usachov, Dmitry Yu / Danzenbächer, Steffen / Hellwig, Johannes / Peters, Marius / Kliemt, Kristin / Kucherenko, Yuri / Antonov, Victor N / Laubschat, Clemens / Chulkov, Evgueni V / Ernst, Arthur / Kummer, Kurt / Krellner, Cornelius / Vyalikh, Denis V

    ACS nano

    2022  Volume 16, Issue 3, Page(s) 3573–3581

    Abstract: The f-driven temperature scales at the surfaces of strongly correlated materials have increasingly come into the focus of research efforts. Here, we unveil the emergence of a two-dimensional Ce Kondo lattice, which couples ferromagnetically to the ... ...

    Abstract The f-driven temperature scales at the surfaces of strongly correlated materials have increasingly come into the focus of research efforts. Here, we unveil the emergence of a two-dimensional Ce Kondo lattice, which couples ferromagnetically to the ordered Co lattice below the P-terminated surface of the antiferromagnet CeCo
    Language English
    Publishing date 2022-02-14
    Publishing country United States
    Document type Journal Article
    ISSN 1936-086X
    ISSN (online) 1936-086X
    DOI 10.1021/acsnano.1c10705
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Macroscopic and Microscopic Elasticity of Heterogeneous Polymer Gels.

    Di Lorenzo, Fany / Hellwig, Johannes / von Klitzing, Regine / Seiffert, Sebastian

    ACS macro letters

    2015  Volume 4, Issue 7, Page(s) 698–703

    Abstract: Polymer-network gels often exhibit local defects and spatial heterogeneity of their cross-linking density, which may differently affect their elasticity on microscopic and macroscopic scales. To appraise this effect, we prepare polymeric gels with ... ...

    Abstract Polymer-network gels often exhibit local defects and spatial heterogeneity of their cross-linking density, which may differently affect their elasticity on microscopic and macroscopic scales. To appraise this effect, we prepare polymeric gels with defined extents of nanostructural heterogeneity and use atomic force microscopy to probe their local microscopic Young's moduli in comparison to their macroscopic elastic moduli measured by shear rheology. In this comparison, the moduli of the heterogeneous gels are found to be progressively smaller if the length scale of the probed gel region exceeds the size of the purposely imparted polymer-network heterogeneities. This finding can be explained with a conceptual picture of nonaffine deformation of the densely cross-linked polymer network domains in the heterogeneous gels.
    Language English
    Publishing date 2015-06-18
    Publishing country United States
    Document type Journal Article
    ISSN 2161-1653
    ISSN (online) 2161-1653
    DOI 10.1021/acsmacrolett.5b00228
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article: Separation of Storage and Loss Modulus of Polyelectrolyte Multilayers on a Nanoscale: A Dynamic AFM Study

    Hellwig, Johannes / Micciulla Samantha / Strebe Julia / von Klitzing Regine

    Langmuir. 2016 Oct. 18, v. 32, no. 41

    2016  

    Abstract: Atomic force microscopy (AFM) is used to carry out rheology measurements on the nanoscale and to determine the mechanical properties of poly(l-lysine) (PLL)/hyaluronic acid (HA) multilayer films. Storage (G′) and loss modulus (G″) of the films are ... ...

    Abstract Atomic force microscopy (AFM) is used to carry out rheology measurements on the nanoscale and to determine the mechanical properties of poly(l-lysine) (PLL)/hyaluronic acid (HA) multilayer films. Storage (G′) and loss modulus (G″) of the films are calculated and compared with the values obtained from quartz crystal microbalance with dissipation monitoring measurements (QCM-D). A predominant elastic behavior independently of the applied frequencies (5–100 Hz) is observed for native HA/PLL films consisting of 36 double layer. If the layers are cross-linked, the value of G′ increases by 2 orders of magnitude, while the loss modulus becomes negligible, making these films a purely elastic chemical gel. The values of G′ and G′′ extracted from QCM-D measurements on native films are much higher, due to the different frequency regime of the applied shear stress. However, the viscoelastic ratio from the two methods is the same and proves the elastic dominated response of the multilayer in both frequency regimes.
    Keywords atomic force microscopy ; crosslinking ; electrolytes ; gels ; loss modulus ; lysine ; mechanical properties ; quartz crystal microbalance ; rheology ; shear stress ; viscoelasticity
    Language English
    Dates of publication 2016-1018
    Size p. 10505-10512.
    Publishing place American Chemical Society
    Document type Article
    ZDB-ID 2005937-1
    ISSN 1520-5827 ; 0743-7463
    ISSN (online) 1520-5827
    ISSN 0743-7463
    DOI 10.1021%2Facs.langmuir.6b02764
    Database NAL-Catalogue (AGRICOLA)

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  6. Article ; Online: Carbohydrate gel beads as model probes for quantifying non-ionic and ionic contributions behind the swelling of delignified plant fibers.

    Karlsson, Rose-Marie Pernilla / Larsson, Per Tomas / Yu, Shun / Pendergraph, Samuel Allen / Pettersson, Torbjörn / Hellwig, Johannes / Wågberg, Lars

    Journal of colloid and interface science

    2018  Volume 519, Page(s) 119–129

    Abstract: Macroscopic beads of water-based gels consisting of uncharged and partially charged β-(1,4)-d-glucan polymers were developed to be used as a novel model material for studying the water induced swelling of the delignified plant fiber walls. The gel beads ... ...

    Abstract Macroscopic beads of water-based gels consisting of uncharged and partially charged β-(1,4)-d-glucan polymers were developed to be used as a novel model material for studying the water induced swelling of the delignified plant fiber walls. The gel beads were prepared by drop-wise precipitation of solutions of dissolving grade fibers carboxymethylated to different degrees. The internal structure was analyzed using Solid State Cross-Polarization Magic Angle Spinning Carbon-13 Nuclear Magnetic Resonance and Small Angle X-ray Scattering showing that the internal structure could be considered a homogeneous, non-crystalline and molecularly dispersed polymer network. When beads with different charge densities were equilibrated with aqueous solutions of different ionic strengths and/or pH, the change in water uptake followed the trends expected for weak polyelectrolyte gels and the trends found for cellulose-rich fibers. When dried and subsequently immersed in water the beads also showed an irreversible loss of swelling depending on the charge and type of counter-ion which is commonly also found for cellulose-rich fibers. Taken all these results together it is clear that the model cellulose-based beads constitute an excellent tool for studying the fundamentals of swelling of cellulose rich plant fibers, aiding in the elucidation of the different molecular and supramolecular contributions to the swelling.
    Language English
    Publishing date 2018-06-01
    Publishing country United States
    Document type Journal Article
    ZDB-ID 241597-5
    ISSN 1095-7103 ; 0021-9797
    ISSN (online) 1095-7103
    ISSN 0021-9797
    DOI 10.1016/j.jcis.2018.02.052
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Bonn / Germany

    Z 71/707: Show issues

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  7. Article ; Online: Growth behaviour and mechanical properties of PLL/HA multilayer films studied by AFM.

    Uzüm, Cagri / Hellwig, Johannes / Madaboosi, Narayanan / Volodkin, Dmitry / von Klitzing, Regine

    Beilstein journal of nanotechnology

    2012  Volume 3, Page(s) 778–788

    Abstract: Scanning- and colloidal-probe atomic force microscopy were used to study the mechanical properties of poly(L-lysine)/hyaluronan (PLL/HA)(n) films as a function of indentation velocity and the number of polymer deposition steps n. The film thickness was ... ...

    Abstract Scanning- and colloidal-probe atomic force microscopy were used to study the mechanical properties of poly(L-lysine)/hyaluronan (PLL/HA)(n) films as a function of indentation velocity and the number of polymer deposition steps n. The film thickness was determined by two independent AFM-based methods: scratch-and-scan and newly developed full-indentation. The advantages and disadvantages of both methods are highlighted, and error minimization techniques in elasticity measurements are addressed. It was found that the film thickness increases linearly with the bilayer number n, ranging between 400 and 7500 nm for n = 12 and 96, respectively. The apparent Young's modulus E ranges between 15 and 40 kPa and does not depend on the indenter size or the film bilayer number n. Stress relaxation measurements show that PLL/HA films have a viscoelastic behaviour, regardless of their thickness. If indentation is performed several times at the same lateral position on the film, a viscous/plastic deformation takes place.
    Language English
    Publishing date 2012-11-21
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 2583584-1
    ISSN 2190-4286 ; 2190-4286
    ISSN (online) 2190-4286
    ISSN 2190-4286
    DOI 10.3762/bjnano.3.87
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Book: Johannis Ottonis de Helbig, Magnæ Britanniæ Equitis & Ser. Principis-Electoris Palatini Consiliarii, Judicium De Duumviris Hermeticis Fœderatis, & horum Epistola buccinatoria secunda

    Hellwig, Johannes Otto de

    Amico Tale petenti per Epistolam responsoriam communicatum, debitoque in bonum publicum amore nunc editum

    1683  

    Title variant Judicium De Duumviris Hermeticis Foederatis, & horum Epistola buccinatoria secunda ; Iudicium
    Language Latin
    Size 46 S., [1] Bl., 12°
    Publisher Janssonius
    Publishing place Amstelodami
    Document type Book
    Note Fingerprint nach Ex. der SUB Hamburg, UB Erfurt ; Vorlageform des Erscheinungsvermerks: Amstelodami, Apud Janssonio Waesbergios, Anno 1683.
    Database Former special subject collection: coastal and deep sea fishing

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  9. Book: Johannis Ottonis Helbigii, Thuringi, Philosophi & Medicinae Doctoris Introitus In veram atque Inauditam Physicam

    Hellwig, Johannes Otto von

    Epistola Ex India Orientali in Europam ad Celeberrimam Sacri Romani Imperii Academiam Naturae Curiosorum transmissa, apertus

    1680  

    Title variant Johannis Ottonis Helbigii, Thuringi, Philosophi & Medicinae Doctoris Introitus In Veram atque Inauditam Physicam Magis elucidatus, Et Duabus Epistolis augmentatus ; Introitus In Veram atque Inauditam Physicam Magis elucidatus, Et Duabus Epistolis augmentatus
    Institution Sacri Romani Imperii Academia Caesareo-Leopoldina Naturae Curiosorum
    Language Latin
    Size 87 S., 12°
    Publisher Rüdiger
    Publishing place Heidelberg ; Heidelbergae
    Document type Book
    Note Ähnliche Ausg. mit Abweichung auf Titelbl. (dort: Otton) und Vortitelbl. (dort: augmuntatur) s. VD17 14:628748M ; Vorlageform des Erscheinungsvermerks: HEIDELBERGÆ, Apud JOH. MICHAEL. RÜDIGER, 1680. ; Enth. außerdem: (S. [49]) Vis Aliena Tessae. sive Epistolium responsorium Hermetice Commentans & explicans Eadem In Scripto Helbigiano, Introitus in veram & inauditam physicam intitulato ... contenta Verba : Aliquot abhinc mensibus Baruthi, nunc Heidelbergae Excusum a Samuele Ammonio, Anno M DC LXXX. - (S. [67]) J. O. Helbigii Epistola Ad praecedentis libelli, qui intitulatus est, Vis Aliena Tessae, Autorem, Dn. W. F. I. Con. B. - (S. [81]) J. O. Helbigii Epistola Intimorum iussu Amicorum ad Fraternitatem Roseae Crucis Exarata
    Database Former special subject collection: coastal and deep sea fishing

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  10. Book: Joh. Ottonis Helbigii, Dr. Chur-Fürstl. Durchl. zu PfaltzRahts/ Leib-Medici, und bey der Heydelberg. Universität P. P. Gründliche Antwort/ Auff folgende Drey Fragen: I. Was eigentlich der Lapis Philosophorum sey? II. Worinnen seine Materia bestehe/ und wie sie müsse bereitet werden? III. Und endlich was man von denen Laboranten und Goldsuchern/ insgemein Alchemisten/ an Herren-Höfen/ halten solle?

    Hellwig, Johannes Otto von / S., C. T

    An seinen geliebten Freund/ C. T. S. Dr

    1681  

    Title variant auf drei sei Materie Alchimisten
    Language Latin
    Size 24 S., 12°
    Publisher Ammon ; Rüdiger
    Publishing place Heidelberg
    Document type Book
    Note Erscheinungsjahr nach Datierung am Ende: Nürnberg den 26. Martii 1681.
    Database Former special subject collection: coastal and deep sea fishing

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