S. Pfeiffer

University of Michigan–Ann Arbor

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G. Heppke

Technische Universität Berlin

R. Shashidhar

JSS Academy of Higher Education and Research

R. Shashidhar

Visvesvaraya Technological University

S. Krishna Prasad

Centre for Nano and Soft Matter Sciences

Charlie J. Childs

University of Wyoming

Darrell N. Kotton

Boston University

D. S. Shankar Rao

Centre for Nano and Soft Matter Sciences

Orren Shachaf

The University of Texas at Austin

S. Quentel

Technische Universität Berlin

Tristan Frum

University of Michigan–Ann Arbor

Cooperative Institutions

University of Michigan–Ann Arbor

United States Naval Research Laboratory

Raman Research Institute

Centre National de la Recherche Scientifique

Naval Research Laboratory Center for Bio/Molecular Science and Engineering

University of Florida

Bangalore University

Kent State University

Boston University

Boston Medical Center

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Fast switching ferroelectric side-chain liquid-crystalline polymer and copolymer

Liquid Crystals (1991)

Jawad Naciri S. Pfeiffer R. Shashidhar

Abstract New ferroelectric side-chain liquid-crystalline polymers, a copolymer and a homopolymer, with siloxane backbone and a triaromatic mesogen as the side group have been synthesized. The materials exhibit a chiral smectic C phase over a large temperature range extending to room temperature. They possess high values of spontaneous polarization: 105 nC cm−2 for the homopolymer and 180 nC cm−2 for the copolymer. The electro-optic switching time in the chiral smectic C phase is extremely fast (150 μs). In the smectic A phase, an electroclinic effect with switching times less than 100 μs and with field induced tilt angles of 18° is observed.

Mesogen

Side chain

Siloxane

10.1080/02678299108036446

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Citations (60)

Dielectric Studies on Two Isomeric Cyano Ester Homologous Series

Molecular Crystals and Liquid Crystals Incorporating Nonlinear Optics (1989)

G. Heppke S. Pfeiffer C. Nagabhushan R. Shashidhar

Abstract We have studied the static dielectric permittivities of two homologous series of compounds, viz., 4-cyanophenyl 4′-n-alkoxybenzoates (CPnOB) and 4-n-alkoxyphenyl 4′-cyanobenzoates (nOPCB). These are biaromatic compounds with a terminal cyano group, but the ester linkages in the two series are oppositely disposed. For both series of compounds, the mean permittivity shows a jump at the nematic-isotropic transition that increases with increasing chain length. The pretransitional effects in the isotropic phases of the compounds CPnOB, wherein the longitudinal component of the dipole moment of the ester linkage is additive with regard to the cyano end-group, are found to be nearly one order of magnitude larger than those seen in the case of the nOPCB compounds.

Homologous series

Linkage (software)

10.1080/00268948908047750

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Citations (6)

Experimental Observation of a Transition between Two Uniaxial Nematic Liquid-Crystal Phases

Physical Review Letters (1994)

George Nounesis Satyendra Kumar S. Pfeiffer R. Shashidhar C. W. Garland

The experimental observation of a phase transition between two uniaxial nematic liquid-crystalline phases is reported. High-resolution x-ray scattering and ac calorimetric studies on binary mixtures of octyl- and decyloxyphenyl-nitrobenzoyloxy benzoates show evidence of a first-order transition between two nematic phases with different types of short-range smectic order. This transition is observed in the vicinity of the termination of the smectic-${A}_{d}$-smectic-${A}_{1}$ phase boundary, in accordance with theoretical predictions.

Biaxial nematic

Benzoates

10.1103/physrevlett.73.565

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Citations (26)

Nascent matrix deposition supports alveolar organoid formation from aggregates in synthetic hydrogels

bioRxiv (Cold Spring Harbor Laboratory) (2024)

Madeline K. Eiken Charlie J. Childs Lindy K. Brastrom Tristan Frum Eleanor M. Plaster

Human induced pluripotent stem cell (iPSC) derived alveolar organoids have emerged as a system to model the alveolar epithelium in homeostasis and disease. However, alveolar organoids are typically grown in Matrigel, a mouse-sarcoma derived basement membrane matrix that offers poor control over matrix properties, prompting the development of synthetic hydrogels as a Matrigel alternative. Here, we develop a two-step culture method that involves pre-aggregation of organoids in hydrogel-based microwells followed by embedding in a synthetic hydrogel that supports alveolar organoid growth, while also offering considerable control over organoid and hydrogel properties. We find that the aggregated organoids secrete their own nascent extracellular matrix (ECM) both in the microwells and upon embedding in the synthetic hydrogels. Thus, the synthetic gels described here allow us to de-couple exogenous and nascent ECM in order to interrogate the role of ECM in organoid formation.

Organoid

Matrigel

Matrix (chemical analysis)

10.1101/2024.03.19.585720

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Citations (1)

Continuous thermodynamic path between three smectic-Aphases of the same symmetry

Physical Review A (1992)

S. Pfeiffer G. Heppke D. S. Shankar Rao R. Shashidhar

Observation of a continuous thermodynamic path between smectic-${\mathit{A}}_{1}$ and smectic-${\mathit{A}}_{2}$ phases is reported. This path follows a continuous evolution from smectic-${\mathit{A}}_{1}$ to smectic-${\mathit{A}}_{\mathit{d}}$ in the vicinity of a closed-loop nematic domain and then from smectic-${\mathit{A}}_{\mathit{d}}$ to smectic-${\mathit{A}}_{2}$ in the neighborhood of a smectic-${\mathit{A}}_{\mathit{d}}$--smectic-${\mathit{A}}_{2}$ critical point.

10.1103/physreva.46.r6166

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Citations (5)

X-Ray Studies Near the Ad-A2 Criticai Point in a Binary System of Successive Homologues

Molecular Crystals and Liquid Crystals Letters (2013)

S. Quentel G. Heppke S. Krishna Prasad S. Pfeiffer R. Shashidhar

AbstractWe have observed on the basis of X-ray studies a Ad-A2 critical point in a binary mixture of homologues belonging to the 4-n-alkyloxyphenyl 4′-(4′-cyanobenzyloxy)—benzoate series (nOPCBOB). The critical point exists between the 10th and 11th member for a molar fraction of Xc = 0. 44 of the latter. Below Xc the layer spacing shows a distinct jump at the Ad-A2 transition whereas a smooth evolution is seen for X > Xc in the supercritical region.

Critical point (mathematics)

Transition point

10.1080/01406566.1990.10767058

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Langmuir-Blodgett Films of Triazolehemiporphyrazines: Evidence for Molecular Organization

Langmuir (1995)

S. Pfeiffer Christophe Mingotaud Chantal Garrigou–Lagrange P. Delhaès Ángela Sastre‐Santos

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTLangmuir-Blodgett Films of Triazolehemiporphyrazines: Evidence for Molecular OrganizationS. Pfeiffer, C. Mingotaud, C. Garrigou-Lagrange, P. Delhaes, A. Sastre, and T. TorresCite this: Langmuir 1995, 11, 7, 2705–2712Publication Date (Print):July 1, 1995Publication History Published online1 May 2002Published inissue 1 July 1995https://pubs.acs.org/doi/10.1021/la00007a060https://doi.org/10.1021/la00007a060research-articleACS PublicationsRequest reuse permissionsArticle Views81Altmetric-Citations30LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

10.1021/la00007a060

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Citations (31)

Ferroelectricity in a Langmuir–Blodgett multilayer film of a liquid crystalline side-chain polymer

Applied Physics Letters (1993)

S. Pfeiffer R. Shashidhar Thomas L. Fare Jawad Naciri Jörg Adams

The observation of ferroelectric behavior in a Langmuir–Blodgett (LB) film of a liquid crystalline polymer is reported. It is established that a 30-layer film exhibits spontaneous polarization and electro-optic switching. The magnitude of the polarization of the LB film is found to be similar to that of the bulk material. The polarization current in the LB film follows the applied triangular wave field to higher frequencies as compared to the same material in a surface stabilized (sandwich) cell.

Side chain

Ferroelectric Polymers

10.1063/1.109759

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Citations (13)

Dielectric studies on two compounds exhibiting first and second order smectic Ad-nematic transitions

Molecular crystals and liquid crystals. Letters section (2013)

G. Heppke S. Pfeiffer R. Shashidar

ABSTRACTThe influence of the order of the smectic A to nematic transition (A-N) on the behaviour of the static dielectric permittivity was investigated by studying 4-cyano-phenyl 4′-n-decyloxybenzoate (CP10OB) and 4-cyanophenyl 4′-n-undecyloxybenzoate (CP11OB). In the case of the former which exhibits a second order A-N transition, ϵ∥, ϵ⊥ well as Δϵ are seen to show a change of slope at the transition while in case of the latter compound which has a first order A-N transition a small jump is seen. These studies show that the change in the order of the A-N transition manifests in the dielectric properties of the materials.

Transition temperature

Source

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Scanning tunnelling microscopic study of the interfacial order in a ferroelectric liquid crystal

Liquid Crystals (1993)

Susan L. Brandow Judith A. Harrison D. P. DiLella Richard J. Colton S. Pfeiffer

Abstract We present scanning tunnelling microscopy images of a ferroelectric liquid crystal in its chiral smectic C phase. These images show evidence of pronounced interaction between the adjacent lateral dipoles located near the chiral centres of neighbouring molecules. The two dimensional structure at the graphite—liquid crystal interface is found to be highly ordered. Features of this crystal-like order are the pronounced dimer arrangement within a layer and a kinked conformation in which the aromatic core is tilted with respect to the chains. The core axis is tilted at 30° with respect to the layer normal in the plane of the interface. This tilt is very similar to the tilt angle of the bulk material.

Antiferroelectricity

Crystal (programming language)

10.1080/02678299308029062

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Citations (6)