Dynamic behavior of nematic liquid crystal mixtures with quantum dots in electric fields

• Emil Petrescu,
• Cristina Cirtoaje and
• Octavian Danila

Beilstein J. Nanotechnol. 2018, 9, 399–406, doi:10.3762/bjnano.9.39

• nanoparticles [6], quantum dots (QDs) [7][8][9][10][11][12] or other nanomaterials [13][14][15][16][17] that can be effectively used in electro-optical devices. When added to liquid crystals, quantum dots may seriously influence their behavior under an electric field due to the anchoring forces acting on the

• liquid crystal is acting like a continuous fluid and the interaction forces between its molecules are elastic. Taking into account a strong anchoring on the glass support, the free energy density of such a system with added quantum dots is: where fN is the liquid crystal free energy density, fE is a term

• and the configuration given in Figure 3, as well as homeotropic anchoring of liquid crystal molecules on the QD surface [12], the interaction energy for a particle can be obtained using a similar procedure as presented by Burylov [22]: where w is the anchoring energy on the surface of the nanoparticle

Periodic structures on liquid-phase smectic A, nematic and isotropic free surfaces

• Anna N. Bagdinova,
• Evgeny I. Demikhov,
• Nataliya G. Borisenko,
• Sergei M. Tolokonnikov,
• Gennadii V. Mishakov and
• Andrei V. Sharkov

Beilstein J. Nanotechnol. 2018, 9, 342–352, doi:10.3762/bjnano.9.34

• ; liquid crystals; microscopy; smectic A phase; Introduction The considerable interest in studies of liquid crystalline free boundaries that has recently arisen is due to their intrinsic free surface properties which are not influenced by the substrate anchoring [1][2]. This is very important for many

• amplitudes by the program MetroPro. A piece of LC display was used as a substrate (Figure 12), which provides two main advantages. First, it has a large anchoring energy for theliquid crystal director field, and second, helps to better focus at the bottom edge of the liquid crystal layer. During the

Wafer-scale bioactive substrate patterning by chemical lift-off lithography

• Chong-You Chen,
• Chang-Ming Wang,
• Hsiang-Hua Li,
• Hong-Hseng Chan and
• Wei-Ssu Liao

Beilstein J. Nanotechnol. 2018, 9, 311–320, doi:10.3762/bjnano.9.31

• biological species recognition with minimum nonspecific attachment. Herein, a straightforward approach utilizing chemical lift-off lithography to create a diluted self-assembled monolayer matrix for anchoring diverse biological probes is introduced. The strategy encompasses convenient operation, well-tunable

• -arrangement of silane or thiol molecules on silica or Au surfaces, which has been proven as a convenient route for the fabrication of functional surfaces toward versatile targets [12][13][14][15][16]. In addition to direct surface modification, the versatility of anchoring molecule tail groups provides

• steps, and biomolecule anchoring. It should be noted that the conformal contact reaction requires no external pressure, and the lift-off operation is performed under ambient conditions. As shown in the AFM images of Figure 1, the SAM-modified Au surface reveals a depressed square pattern after CLL

Anchoring of a dye precursor on NiO(001) studied by non-contact atomic force microscopy

• Sara Freund,
• Antoine Hinaut,
• Nathalie Marinakis,
• Edwin C. Constable,
• Ernst Meyer,
• Catherine E. Housecroft and
• Thilo Glatzel

Beilstein J. Nanotechnol. 2018, 9, 242–249, doi:10.3762/bjnano.9.26

• ligand to complete the active dye [43][44][45]. We present in this paper, high-resolution structural and electrical measurements obtained by nc-AFM of a typical anchoring ligand (DCPDMbpy), based on a 6,6′-dimethyl-2,2′-bipyridine metal-binding domain with two 4-carboxyphenyl anchoring groups (see Figure

• (001) surface, we investigated the adsorption properties of the anchoring ligand DCPDMbpy, at various coverages. Depending on the deposition conditions and post-deposition treatments of the sample, DCPDMbpy molecules remain separated or form molecular clusters or islands on the surface of NiO(001) at

• between the NiO surface and the dye precursor molecule DCPDMbpy. Conclusion We have presented high-resolution topographic measurements using bimodal nc-AFM at room temperature of the anchoring part of a larger dye molecule (DCPDMbpy) adsorbed on a NiO(001) crystal surface. The surface structure of NiO(001

Dynamic behavior of a nematic liquid crystal with added carbon nanotubes in an electric field

• Emil Petrescu and
• Cristina Cirtoaje

Beilstein J. Nanotechnol. 2018, 9, 233–241, doi:10.3762/bjnano.9.25

• models have to be developed for their characterization [5][6][9][10][11]. When nanoparticles are inserted in liquid crystals, nematic molecules are attached to the particle surface due to anchoring forces. Experimental studies revealed that carbon nanotubes have a strong interaction with liquid crystal

• we consider the interaction free energy between nanoparticles and nematic liquid crystal molecules given by the model proposed by Burylov and Zakhlevnykh [17], we get: where f is the volumetric fraction of nanotubes, R is the nanotubes radius, w is the average anchoring energy density at the nematic

• Dierking and co-workers [13][14] proved an alignment of CNTs parallel to the liquid crystal molecules, so we may assume that the anchoring angle α is neglectable. Thus, Equation 11 becomes: When exposed to an external electric field higher than the critical Fréedericksz transition threshold the molecules

Nematic topological defects positionally controlled by geometry and external fields

• Pavlo Kurioz,
• Marko Kralj,
• Bryce S. Murray,
• Charles Rosenblatt and
• Samo Kralj

Beilstein J. Nanotechnol. 2018, 9, 109–118, doi:10.3762/bjnano.9.13

• interaction strength, is the surface normal of the local confinement, and describes preferred nematic ordering of the surface. The surface term given by Equation 8 enforces for w > 0 (w < 0) degenerate tangential (homeotropic) anchoring. On the other hand, the contribution in Equation 9 is minimized for

• the Cartesian (x,y,z) or cylindrical geometry (r,φ,z), as illustrated in Figure 1. Accordingly, we use two different boundary conditions, to which we refer as “boundary anchoring condition” (BAC) [18] and “surface anchoring condition” (SAC), respectively. We use BAC in the “Cartesian” cells. We assume

• Equation 10, in which we set m = 1. At the bottom plate we enforce homeotropic anchoring conditions using the ansatz in Equation 8. At the lateral boundaries we assume free boundary conditions. These conditions impose a boojum topological defect at the top plate [19][20]. Note that in our simulations we

Nematic liquid crystal alignment on subwavelength metal gratings

• Irina V. Kasyanova,
• Artur R. Geivandov,
• Vladimir V. Artemov,
• Maxim V. Gorkunov and
• Serguei P. Palto

Beilstein J. Nanotechnol. 2018, 9, 42–47, doi:10.3762/bjnano.9.6

• have also obtained a 90° twisted LC director distribution, implying sufficiently strong azimuthal LC anchoring at the grating surface. Keywords: alignment; Fourier analysis; nematic liquid crystal; subwavelength metal grating; Introduction In the age of nanotechnology, various nanostructured

• twisted distribution of the LC director takes place in the layer. The appearance of the twist demonstrates that the subwavelength aluminum gratings are capable of aligning liquid crystals along their slits with rather small pretilt angles and that the anchoring energy is high enough to balance the elastic

• torque at the surface, which is provided by the twisted deformation across the LC layer. The azimuthal anchoring strength can be estimated from the fact that the angular deviation from the 90o twist is not higher than our experimental accuracy (δφ ≈ 3°). Our analysis shows that in the case of such small

Magnetic field induced orientational transitions in liquid crystals doped with carbon nanotubes

• Danil A. Petrov,
• Pavel K. Skokov and
• Alexander N. Zakhlevnykh

Beilstein J. Nanotechnol. 2017, 8, 2807–2817, doi:10.3762/bjnano.8.280

• absolutely rigid anchoring of NLC molecules with the boundaries. We set the origin of the coordinate system at the middle of the layer (see Figure 1). We use the unit vectors n and m, the so-called directors, to describe the preferential orientation of the LC molecules and CNTs, respectively. We assume soft

Inelastic electron tunneling spectroscopy of difurylethene-based photochromic single-molecule junctions

• Youngsang Kim,
• Safa G. Bahoosh,
• Dmytro Sysoiev,
• Thomas Huhn,
• Fabian Pauly and
• Elke Scheer

Beilstein J. Nanotechnol. 2017, 8, 2606–2614, doi:10.3762/bjnano.8.261

• HOMO energy is closer to the Fermi energy than the LUMO level, as typical for sulfur anchoring groups [37]. In Figure 2c, we show the wavefunctions of the dominant eigenchannel at EF for the closed and open forms for electrons that enter from the left side. The electric transport mainly proceeds

Nanoprofilometry study of focal conic domain structures in a liquid crystalline free surface

• Anna N. Bagdinova,
• Evgeny I. Demikhov,
• Nataliya G. Borisenko and
• Sergei M. Tolokonnikov

Beilstein J. Nanotechnol. 2017, 8, 2544–2551, doi:10.3762/bjnano.8.254

• substrate anchoring [1][2]. This understanding is important for display-quality technology and production enhancement. The study of the free liquid crystalline boundary is interesting for applications such as liquid crystalline colors and coatings as well as cosmetics. To study liquid crystalline free

• liquid crystal display was used (Figure 7). For this, we have broken a commercial Samsung PC display, cleaned and dried it. The LC PC display substrate brings two main advantages. First, it has a large anchoring energy for the liquid crystal director field and it makes for better conditions for FCD

Dynamic behavior of a nematic liquid crystal mixed with CoFe₂O₄ ferromagnetic nanoparticles in a magnetic field

• Emil Petrescu,
• Cristina Cirtoaje and
• Cristina Stan

Beilstein J. Nanotechnol. 2017, 8, 2467–2473, doi:10.3762/bjnano.8.246

• variations of transition thresholds [27][28] or response time [29]. Ferromagnetic nanoparticles are good candidates for LC improvement due to their significant positive magnetic anisotropy and strong anchoring energy [30][31] on a large surface provided by chain clustering. All these effects help the

• nanoparticles are agglomerating in long chains on which LC molecules are attached like leaves on a tree branch. Previous results [32] and microscopy images indicate that CoFe2O4 nanoparticles are gathering in long chains which align themselves parallel to the rubbing directions indicating a strong anchoring to

• interaction of the liquid crystal with the applied field, the interaction of the ferromagnetic nanoparticles with the magnetic field and the LC molecules anchoring on the surface of the added particles. The deviation angle θ between the glass plates is given by: where z is the Oz coordinate of the LC

Adsorbate-driven cooling of carbene-based molecular junctions

• Giuseppe Foti and
• Héctor Vázquez

Beilstein J. Nanotechnol. 2017, 8, 2060–2068, doi:10.3762/bjnano.8.206

• adsorbate is fundamentally different from that of anchoring groups in molecular junctions (R–NH2): here NH2 acts as an acceptor, while as anchoring group, amines are electron donors [42]. In Supporting Information File 1, we show a comparison of the plane-averaged electron density difference upon adsorption

• of NH2 for reference, and its saturated counterpart NH3 (which is similar to the role as anchoring group R–NH2). Similar shifts of molecular levels are expected for other adsorbates, whose donor or acceptor character could be used to gate NHC conducting orbitals. We now turn to the spectral features

Application of visible-light photosensitization to form alkyl-radical-derived thin films on gold

• Rashanique D. Quarels,
• Xianglin Zhai,
• Neepa Kuruppu,
• Jenny K. Hedlund,
• Ashley A. Ellsworth,
• Amy V. Walker,
• Jayne C. Garno and
• Justin R. Ragains

Beilstein J. Nanotechnol. 2017, 8, 1863–1877, doi:10.3762/bjnano.8.187

• demonstrated with radical initiators [44]. Therefore, crosslinking is a possible underlying reason for robustness (see proposed mechanism, Scheme 3). In addition, formation of Au–C and CO2–Au bonds at the surface is evidenced by TOF-SIMS but not by XPS, suggesting that limited anchoring of the film may be

Methionine-mediated synthesis of magnetic nanoparticles and functionalization with gold quantum dots for theranostic applications

• Arūnas Jagminas,
• Agnė Mikalauskaitė,
• Vitalijus Karabanovas and
• Jūrate Vaičiūnienė

Beilstein J. Nanotechnol. 2017, 8, 1734–1741, doi:10.3762/bjnano.8.174

• stabilization of cobalt ferrite NPs as the capping ligand and reducing agent of gold ions. The interest in NPs capped with methionine was based on the current understanding that methionine can reduce chloroauric acid from alkaline solutions anchoring Au0 at the surface of the NPs [18]. As-synthesized NPs were

Two-dimensional carbon-based nanocomposites for photocatalytic energy generation and environmental remediation applications

• Suneel Kumar,
• Ashish Kumar,
• Ashish Bahuguna,
• Vipul Sharma and
• Venkata Krishnan

Beilstein J. Nanotechnol. 2017, 8, 1571–1600, doi:10.3762/bjnano.8.159

• reactions, mainly controlled hydrolysis and condensation, to form the desired photocatalyst. The major advantage of using the sol–gel method is the in situ growth of nanostructures so that the various functional groups on the surface of GO sheets are available to provide reactive and anchoring sites for the

• properties with unsaturated N-atoms for anchoring active sites [69]. Furthermore, the stacked 2D layered structure of g-C3N4 consists of single-layer nitrogen heteroatom-substituted graphite nanosheets, formed through sp2 hybridization of C and N atoms, and various layers are bound together by van der Waals

Nano-engineered skin mesenchymal stem cells: potential vehicles for tumour-targeted quantum-dot delivery

• Liga Saulite,
• Dominyka Dapkute,
• Karlis Pleiko,
• Ineta Popena,
• Simona Steponkiene,
• Ricardas Rotomskis and
• Una Riekstina

Beilstein J. Nanotechnol. 2017, 8, 1218–1230, doi:10.3762/bjnano.8.123

• through the anchoring of the clathrin and adaptor protein 2 (AP2) complex to endosomes, thereby preventing the assembly of coated pits at the inner plasma membrane [42]. In serum-free medium, QD uptake was decreased by CPZ and nystatin (Figure 7b,d). nystatin is an inhibitor of caveolin/lipid raft

Stable Au–C bonds to the substrate for fullerene-based nanostructures

• Taras Chutora,
• Jesús Redondo,
• Bruno de la Torre,
• Martin Švec,
• Pavel Jelínek and
• Héctor Vázquez

Beilstein J. Nanotechnol. 2017, 8, 1073–1079, doi:10.3762/bjnano.8.109

• as well as anchoring groups [9][10][11][12]. They have featured in spin transport studies, where spin currents can be achieved by encapsulating magnetic atoms or impurities inside the fullerene cage [13][14][15][16][17][18]. The adsorption of C60 on the metal surface determines the strength and

CVD transfer-free graphene for sensing applications

• Chiara Schiattarella,
• Sten Vollebregt,
• Tiziana Polichetti,
• Brigida Alfano,
• Ettore Massera,
• Maria Lucia Miglietta,
• Girolamo Di Francia and
• Pasqualina Maria Sarro

Beilstein J. Nanotechnol. 2017, 8, 1015–1022, doi:10.3762/bjnano.8.102

• temperature at 1000 °C, the pressure at 25 mbar and using Ar/H2/CH4 as feedstock. At the end of the CVD growth, the Mo has been selectively etched away underneath graphene employing phosphoric acid. Due to anchoring at the sides of the patterned catalyst, the graphene layer sticks directly to the underlaying

Triptycene-terminated thiolate and selenolate monolayers on Au(111)

• Jinxuan Liu,
• Martin Kind,
• Björn Schüpbach,
• Daniel Käfer,
• Stefanie Winkler,
• Wenhua Zhang,
• Andreas Terfort and
• Christof Wöll

Beilstein J. Nanotechnol. 2017, 8, 892–905, doi:10.3762/bjnano.8.91

• larger domains and lower defect densities than their sulfur-based analogues. The most prominent example likely is anthraceneselenolate [5] vs anthracenethiolate [26] on Au(111). The selenolate anchoring group is believed to experience a smaller corrugation of the Au(111) interaction potential, enabling

Calculating free energies of organic molecules on insulating substrates

• Julian Gaberle,
• David Z. Gao and
• Alexander L. Shluger

Beilstein J. Nanotechnol. 2017, 8, 667–674, doi:10.3762/bjnano.8.71

• molecular dynamics. Both molecules contain the same anchoring groups and benzene ring structures, yet differ in their flexibility. Therefore, the entropic contributions to their free energy differ, which affects surface processes. Using potential of mean force and thermodynamic integration techniques, free

α-((4-Cyanobenzoyl)oxy)-ω-methyl poly(ethylene glycol): a new stabilizer for silver nanoparticles

• Jana Lutze,
• Miguel A. Bañares,
• Marcos Pita,
• Andrea Haase,
• Andreas Luch and
• Andreas Taubert

Beilstein J. Nanotechnol. 2017, 8, 627–635, doi:10.3762/bjnano.8.67

• oligomeric or polymeric stabilizer is attached to the particle surface without a specific anchor group [26][27][28][29][30]. The current gold standard for anchoring an organic moiety on the NP surface is the thiol or thiolate group [3][24][31][32][33]. There are, however, cases where the thiol group may not

• be desirable (such as situations, where thiols may form thiyl radicals leading to protein degradation and cause diseases such as cancer) [34][35]. Hence, there is an interest in alternative anchoring groups with a similar or better anchoring efficiency. Among the possible candidates are the amine and

Performance of natural-dye-sensitized solar cells by ZnO nanorod and nanowall enhanced photoelectrodes

• Saif Saadaoui,
• Mohamed Aziz Ben Youssef,
• Moufida Ben Karoui,
• Rached Gharbi,
• Emanuele Smecca,
• Vincenzina Strano,
• Salvo Mirabella,
• Alessandra Alberti and
• Rosaria A. Puglisi

Beilstein J. Nanotechnol. 2017, 8, 287–295, doi:10.3762/bjnano.8.31

• cells (DSSCs). Fourier transform infrared (FTIR) spectra of the extract revealed the presence of anchoring groups and coloring constituents. Two different structures were prepared by chemical bath deposition (CBD) using zinc oxide (ZnO) layers to obtain ZnO nanowall (NW) or nanorod (NR) layers employed

• semiconductor in DSSCs [2][3][4][5]. Besides, the TiO2 offers high electronic mobility for photogenerated electron collection, a suitable band gap, which adapts to the injection of the electrons of most studied dyes, and high surface area to enhance the dye loading by anchoring the dye [6][7]. Zinc oxide (ZnO

• and mallow plants in different concentrations and at various immersion times. Furthermore, we analyzed the properties of the different used dyes and we reported the most anchoring-dominant molecules. By studying different gases used in the annealing process, we noted that the FG gave the most

Performance of colloidal CdS sensitized solar cells with ZnO nanorods/nanoparticles

• Anurag Roy,
• Partha Pratim Das,
• Mukta Tathavadekar,
• Sumita Das and
• Parukuttyamma Sujatha Devi

Beilstein J. Nanotechnol. 2017, 8, 210–221, doi:10.3762/bjnano.8.23

• ; ZnO; Introduction Dye-sensitized solar cells (DSSCs) using inorganic semiconductors are being investigated as a cost-effective and alternative energy source. In DSSCs, a porous electrode made of a wide band gap semiconductor is required for anchoring dye molecules and transporting photo-injected

• nanoparticle aggregation. Various disulfide bonds, thiol residues and other hydroxyl moieties that exist on BSA can serve as effective surface functionalized groups on CdS surfaces [27]. This may further lead to better anchoring with the metal oxide-based photoanode. Among the alternative single oxide

• ]. The surface-functionalized CdS acts as an anchoring moiety, which promotes CdS towards effective sensitization with ZnO. The Raman spectrum was performed as shown in Figure 2b. The peaks located at 294 and 589 cm−1 correspond to the fundamental band (1LO) and corresponding overtone (2LO) of

Solvent-mediated conductance increase of dodecanethiol-stabilized gold nanoparticle monolayers

• Patrick A. Reissner,
• Jean-Nicolas Tisserant,
• Antoni Sánchez-Ferrer,
• Raffaele Mezzenga and
• Andreas Stemmer

Beilstein J. Nanotechnol. 2016, 7, 2057–2064, doi:10.3762/bjnano.7.196

• networks; Self-assembly; Introduction Ordered gold nanoparticle monolayers are increasingly applied as templates for molecular resistor networks [1][2][3][4][5][6][7][8]. Gold nanoparticles serve as conducting nodes and different molecules can bind to the gold nanoparticle using anchoring groups such as

In situ formation of reduced graphene oxide structures in ceria by combined sol–gel and solvothermal processing

• Jingxia Yang,
• Johannes Ofner,
• Bernhard Lendl and
• Ulrich Schubert

Beilstein J. Nanotechnol. 2016, 7, 1815–1821, doi:10.3762/bjnano.7.174

• the intensity ratio I(D)/I(G). I(D)/I(G) values for all rGO–CeO2 composites were larger than that of GO, indicating that the number of defects in the graphene layer increased during the reduction of GO [29][30]. Anchoring of CeO2 on rGO also caused an intensity decrease and up-shifting of the G-band