Induced smectic phase in binary mixtures of twist-bend nematogens

• Anamarija Knežević,
• Irena Dokli,
• Marin Sapunar,
• Suzana Šegota,
• Ute Baumeister and
• Andreja Lesac

Beilstein J. Nanotechnol. 2018, 9, 1297–1307, doi:10.3762/bjnano.9.122

• % of BB. This corresponds to the ratio of two molecules of BB versus one molecule of CBI in the smectic phase. The entropy changes (ΔS/R) determined from the DSC thermograms (Table S1, Supporting Information File 1) for the NTB to SmCA transition exhibit the maximum around 70 mol % of BB which

Formation and development of nanometer-sized cybotactic clusters in bent-core nematic liquid crystalline compounds

• Yuri P. Panarin,
• Sithara P. Sreenilayam,
• Jagdish K. Vij,
• Anne Lehmann and
• Carsten Tschierske

Beilstein J. Nanotechnol. 2018, 9, 1288–1296, doi:10.3762/bjnano.9.121

• Equation 2 and Equation 3, respectively. In the molecular field approximation (MFA), the orientational entropy of a cluster in the nematic phase is the sum of two contributions: the reorientation of the individual molecules and the fluctuation of the cluster directors with respect to the macroscopic

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

• CNTs in LCs [14][18][38]. The last term F5 is the contribution of the entropy of mixing of an ideal solution of CNTs in the LC matrix. As it is known, the state of thermodynamic equilibrium corresponds to the minimum of the free energy (Equation 1), which is a functional of the two vectors n and m, and

• orientational elastic deformations (F1 = 0), in the entropy contribution to the energy (F5 = min), and in the magnetic energy of CNTs (F3 = min). When the diamagnetism of the LC matrix (F2) begins to predominate, at h ≈ hr+, the next transition from the homeotropic phase to the non-uniform state (the angular

Beyond Moore’s technologies: operation principles of a superconductor alternative

• Igor I. Soloviev,
• Nikolay V. Klenov,
• Sergey V. Bakurskiy,
• Mikhail Yu. Kupriyanov,
• Alexander L. Gudkov and
• Anatoli S. Sidorenko

Beilstein J. Nanotechnol. 2017, 8, 2689–2710, doi:10.3762/bjnano.8.269

• of switching a Josephson junction, EJ ≈ 2 × 10−19 J. While presuming logical irreversibility, this energy can be lowered down to Emin ≈ 4 × 10−23 J (at T = 4.2 K) by using adiabatic switching process. Note that the Landauer limit Emin in this context reflects the entropy change in the computing

Ferrocholesteric–ferronematic transitions induced by shear flow and magnetic field

• Dmitriy V. Makarov,
• Alexander A. Novikov and
• Alexander N. Zakhlevnykh

Beilstein J. Nanotechnol. 2017, 8, 2552–2561, doi:10.3762/bjnano.8.255

• ). F3 is the bulk density of the interaction energy of the magnetic field H with the magnetic moment μ = MSvpn of the particles (the dipole mechanism of the magnetic field effect on an FC). F4 is the contribution of the entropy of mixing of an ideal solution of magnetic particles to the free energy of a

Spin-chemistry concepts for spintronics scientists

• Konstantin L. Ivanov,
• Alexander Wagenpfahl,
• Carsten Deibel and
• Jörg Matysik

Beilstein J. Nanotechnol. 2017, 8, 1427–1445, doi:10.3762/bjnano.8.143

• Introduction In general, chemical reactions are discussed in terms of thermodynamics: reaction enthalpy, reaction entropy and free energy. It is also recognized that steric and charge effects can lead to kinetic control of the reaction dynamics by introduction of activation energies. In some cases, chemical

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

• energy profiles and entropy changes were calculated for step adhesion and dimer formation of these molecules. However, converging these calculations is nontrivial and comes at large computational cost. We illustrate the difficulties as well as the possibilities of applying these methods towards

• understanding dynamic processes of organic molecules on insulating substrates. Keywords: entropy; free energy; molecular dynamics; organic molecules; potential of mean force; thermodynamic integration surface step; Introduction In recent years molecular films and self-assembled monolayers have attracted a lot

• entropy as degrees of freedom within the molecules become constrained. This means that free energies can vary significantly from calculated enthalpy values, which may have a direct impact on our understanding of the balance of interactions that govern self-assembly. Methods to compute the free energy from

Fiber optic sensors based on hybrid phenyl-silica xerogel films to detect n-hexane: determination of the isosteric enthalpy of adsorption

• Jesús C. Echeverría,
• Ignacio Calleja,
• Paula Moriones and
• Julián J. Garrido

Beilstein J. Nanotechnol. 2017, 8, 475–484, doi:10.3762/bjnano.8.51

• , it loses translational entropy. The aim of this study was to assess the effect of temperature on the sensitivity of hybrid phenyl-silica films to n-hexane and to determine the variation of the isosteric enthalpy of adsorption. Materials and Methods Optical fibers and preparation of xerogel films

• temperatures between 288 and 323 K. As we have explained in the Introduction section, when the analyte molecules are adsorbed on the silica xerogel the reflected intensity varies. Adsorption is an exothermic process, in which when a vapor molecules is adsorbed on a surface loses translational entropy because

Three-gradient regular solution model for simple liquids wetting complex surface topologies

• Sabine Akerboom,
• Marleen Kamperman and
• Frans A. M. Leermakers

Beilstein J. Nanotechnol. 2016, 7, 1377–1396, doi:10.3762/bjnano.7.129

• approximation) we can evaluate the mixing interaction energy in the system by Umix = NχφV, where we ignored boundary effects and φV = NV/M is the volume fraction of vacancies. The entropy of mixing can be evaluated when we assume once more that the sites are randomly filled by solvent. The total number of ways

• to arrange the fluid and the vacancies is given by and the mixing entropy is found by Smix = −kB·lnΩ = −kB(N·ln φ + NV·ln φV) with φ = N/M and kB the Boltzmann constant. The free energy of mixing is given by Fmix = Umix – T·Smix. Introducing the dimensionless free energy density f = Fmix/(Mb3kBT

Tunable longitudinal modes in extended silver nanoparticle assemblies

• Serene S. Bayram,
• Klas Lindfors and
• Amy Szuchmacher Blum

Beilstein J. Nanotechnol. 2016, 7, 1219–1228, doi:10.3762/bjnano.7.113

• before reaching a steady-state in less than 60 min. The spontaneity is likely enthalpy-driven due to dipole–dipole binding events that are exothermic. Although the assembly process is entropically not favourable, some entropy is regained through branching (Figure 3). Figure 3 shows the development of

Influence of synthesis conditions on microstructure and phase transformations of annealed Sr₂FeMoO_6−x nanopowders formed by the citrate–gel method

• Marta Yarmolich,
• Nikolai Kalanda,
• Sergey Demyanov,
• Herman Terryn,
• Jon Ustarroz,
• Maksim Silibin and
• Gennadii Gorokh

Beilstein J. Nanotechnol. 2016, 7, 1202–1207, doi:10.3762/bjnano.7.111

• second-order phase transition has been revealed at 188 K for SFMO-6 and SFMO-9 powders and 330 K for all investigated powders (Figure 4). Such extremely small changes of entropy, as well as small temperature intervals of phase transformations (within 20 K), are caused by impurity phases distributed as

Fast diffusion of silver in TiO₂ nanotube arrays

• Wanggang Zhang,
• Yiming Liu,
• Diaoyu Zhou,
• Hui Wang,
• Wei Liang and
• Fuqian Yang

Beilstein J. Nanotechnol. 2016, 7, 1129–1140, doi:10.3762/bjnano.7.105

• ) is the melting temperature of the material in a spherical shape of radius r, Tm(∞) is the melting temperature of the material in bulk shape, R is the gas constant, Svib(∞) is the vibrational melting entropy of the material, h is the atomic radius of the material, and d = 0 for nanoparticles. As shown

Hierarchical coassembly of DNA–triptycene hybrid molecular building blocks and zinc protoporphyrin IX

• Rina Kumari,
• Sumit Singh,
• Mohan Monisha,
• Sourav Bhowmick,
• Anindya Roy,
• Neeladri Das and
• Prolay Das

Beilstein J. Nanotechnol. 2016, 7, 697–707, doi:10.3762/bjnano.7.62

• and Zn PpIX (Figure 6). The increase in Tm indicates the formation of a self-assembled ordered structure where DNA duplexes are closely packed and highly oriented. The increase in Tm is also ascribed to the combination of stacking of Zn PpIX along the DNA duplex, reduced configurational entropy and

Molecular machines operating on the nanoscale: from classical to quantum

• Igor Goychuk

Beilstein J. Nanotechnol. 2016, 7, 328–350, doi:10.3762/bjnano.7.31

• , which in the differential form states that dS ≥ δQ/T (i.e., that the increase of entropy, or loss of information, dI ≡ −dS/kBln2 – a very fundamental equality, or rather tautology of the physical information theory), is equal to or exceeds the heat exchange with the environment in the units of T. For an

• adiabatically isolated system, δQ = 0; hence, dI ≤ 0, i.e., entropy can increase and information can diminish spontaneously, without any heat being produced into the surroundings. This is just the second law of thermodynamics rephrased. As a matter of fact, δQ = |dI|kBTln2 is the maximal (not minimal!) amount

Counterion effects on nano-confined metal–drug–DNA complexes

• Nupur Biswas,
• Sreeja Chakraborty,
• Alokmay Datta,
• Munna Sarkar,
• Mrinmay K. Mukhopadhyay,
• Mrinal K. Bera and
• Hideki Seto

Beilstein J. Nanotechnol. 2016, 7, 62–67, doi:10.3762/bjnano.7.7

• laterally to the film surface, whereas in case of films prepared from buffered solution there is no such layering due to the increased orientational entropy of entangled shorter DNA molecules [8][9]. This indicates that both confinement and presence of charged and neutral species in the environment dictates

Nanostructured surfaces by supramolecular self-assembly of linear oligosilsesquioxanes with biocompatible side groups

• Maria Nowacka,
• Anna Kowalewska and
• Tomasz Makowski

Beilstein J. Nanotechnol. 2015, 6, 2377–2387, doi:10.3762/bjnano.6.244

• entropy–enthalpy compensation [51][52][53]. Thus, the mechanism of adsorption of LPSQ-COOH/X on mica should be discussed with respect to possible intermolecular interactions between polymer chains and their relations with the substrate. Macromolecules consisting of surface-reactive repeating units can

Enhanced fullerene–Au(111) coupling in (2√3 × 2√3)R30° superstructures with intermolecular interactions

• Michael Paßens,
• Rainer Waser and
• Silvia Karthäuser

Beilstein J. Nanotechnol. 2015, 6, 1421–1431, doi:10.3762/bjnano.6.147

• this position is obviously less stable than the hex-vac position. Here, advantageous entropy effects [26] or an adlayer buckling in order to minimize the lattice mismatch to the underlying substrate are given as possible explanations. However, solely entropy effects should result in completely random

• provided first. Furthermore, entropy (S) effects might play a role during the C60 monolayer preparation process at elevated temperatures (T), so that a pure hex-vac C60 domain on Au(111) might not correspond to the minimum free energy (F = U − TS) under these conditions. Nevertheless, 6:6-top C60, which

• relevance. If fullerenes forming a dis-R30° superstructure can be described as an Ising-like system, as mentioned in the previous section, the ratio of bright C60 will be increased at elevated temperatures due to entropy effects. This process counteracts the forming of dim C60 based on the increased

Natural and artificial binders of polyriboadenylic acid and their effect on RNA structure

• Giovanni N. Roviello,
• Domenica Musumeci,
• Valentina Roviello,
• Marina Pirtskhalava,
• Alexander Egoyan and
• Merab Mirtskhulava

Beilstein J. Nanotechnol. 2015, 6, 1338–1347, doi:10.3762/bjnano.6.138

• negative enthalpy and positive entropy variations. The authors also reported the induction of self-assembled structures in poly(rA) due to coralyne, as evidenced by circular dichroism experiments. Remarkable changes in the circular dichroism spectrum of poly(rA) were found with complex formation of 2:1

• interactions which demonstrated that increasing the length of the alkyl chain led to binding which is more entropy-driven, and that chain length influenced the ease of self-structure formation. Recently, Basu et al. [40] found that 9-O-N-aryl/arylalkylaminocarbonylmethyl-substituted analogues of berberine

Multiscale modeling of lithium ion batteries: thermal aspects

• Arnulf Latz and
• Jochen Zausch

Beilstein J. Nanotechnol. 2015, 6, 987–1007, doi:10.3762/bjnano.6.102

• coefficients in order to ensure positive entropy production and may reveal information about the nature of the considered continuum fields, which are essential to make contact to atomistic scale simulations and to experiment or influence the form of the charge distribution in the double layer [27]. Only a

• change of the entropy density Here R is the yet unknown entropy production and μα is the chemical potential of species α. An expression for μα will be derived shortly. By eliminating the heat production from Equation 15 and some reformulations of we obtain Here φH is the specific free energy density

• for the free energy, Equation 16 can be transformed into The requirement, that the entropy production R of Equation 21 has to be strictly positive leads to the relations Here p is the pressure and σ is obtained from Equation 17 and the necessary condition τ + pI = 0 imposed by the positivity of the

Entropy effects in the collective dynamic behavior of alkyl monolayers tethered to Si(111)

• Christian Godet

Beilstein J. Nanotechnol. 2015, 6, 583–594, doi:10.3762/bjnano.6.60

• dependence of the B2 dipolar strength. For both dissipation mechanisms, the observed linear correlation between activation energy and logarithm of pre-exponential factor is consistent with a multi-excitation entropy model, in which the molecular reorientation path is strongly coupled with a large number of

• spectroscopy; dipolar relaxation; entropy; gauche defect; organic monolayer; Introduction Self-assembled monolayers (SAM) and organic molecular layers (OML) have attracted great interest over the past two decades because surface functionalization offers great flexibility for a molecular-level control of

• correlations between “embedded dipoles” in order to describe the asymmetric relaxation peak shapes [45][46]. b) The multi-excitation entropy model proposed by Yelon, Movaghar and Crandall (YMC) [47][48] considers a thermodynamic description of the dipole reorientation path strongly coupled with elementary

Si/Ge intermixing during Ge Stranski–Krastanov growth

• Alain Portavoce,
• Khalid Hoummada,
• Antoine Ronda,
• Dominique Mangelinck and
• Isabelle Berbezier

Beilstein J. Nanotechnol. 2014, 5, 2374–2382, doi:10.3762/bjnano.5.246

• minimization of the surface energy, the strain energy, the alloy mixing energy and the configurational entropy [22]. In the case of a pure Ge dome island (no intermixing with Si), the stress was shown to be compressive in the interior of the island, and tensile at the edges of the island [34]. Thus, in the

Anticancer efficacy of a supramolecular complex of a 2-diethylaminoethyl–dextran–MMA graft copolymer and paclitaxel used as an artificial enzyme

• Yasuhiko Onishi,
• Yuki Eshita,
• Rui-Cheng Ji,
• Masayasu Onishi,
• Takashi Kobayashi,
• Masaaki Mizuno,
• Jun Yoshida and
• Naoji Kubota

Beilstein J. Nanotechnol. 2014, 5, 2293–2307, doi:10.3762/bjnano.5.238

• that of DDMC, the starting material. This means that the association with the hydrogen bond itself is weakened, which then reassembles the supramolecular complexes by a hydrophobic reaction between them. The escape of the crystallization water and the binding of DDMC to PTX decrease the entropy

• compared to the state in which it is not bound (enthalpy–entropy compensation or isokinetic theory) [28]. The enthalpy–entropy decrease is expected to stabilize the complexes against supramolecular stress, by Brownian movement owing to the law of entropy increase (effect of entropy elasticity) [29]. This

• including a guest are now defined as artificial enzymes in which the low-molecular-weight subunit containing the active site is complexed with a high-molecular-weight carrier. These supramolecular assemblies have the characteristic of conformational flexibility (slide-ring elasticity) owing to entropy

Effects of surface functionalization on the adsorption of human serum albumin onto nanoparticles – a fluorescence correlation spectroscopy study

• Pauline Maffre,
• Stefan Brandholt,
• Karin Nienhaus,
• Li Shang,
• Wolfgang J. Parak and
• G. Ulrich Nienhaus

Beilstein J. Nanotechnol. 2014, 5, 2036–2047, doi:10.3762/bjnano.5.212

• of the binding affinities was observed for HSA and apotransferrin binding to Fe–Pt NPs [30]. In contrast with the naive expectation that a temperature increase should enhance the tendency to dissociate the NP–protein complex into its components (due to an increase of the overall translational entropy

On the structure of grain/interphase boundaries and interfaces

• K. Anantha Padmanabhan and
• Herbert Gleiter

Beilstein J. Nanotechnol. 2014, 5, 1603–1615, doi:10.3762/bjnano.5.172

• experimental conditions are responsible for the development of the structural/basic units. The final atomic configurations within these structural/basic units will be decided by the minimization of total free energy and, depending on experimental conditions, maximization of entropy to the extent possible. The

• entropy, EN the energy component that changes with the number of atoms (N) present in the ensemble mainly because of topological reasons and Efv is the energy associated with the free volume (fv) present in the aggregate. (In the traditional form of Equation 1, the energy contributions from N and fv are

• nano-glasses the terms TΔS and SΔT are very significant and thus the formation of nano-glasses is accompanied by high entropy changes. These structures seem to depend on the experimental conditions, the total number of atoms in the ensemble and free volume fraction. To date, generally accepted methods

Self-organization of mesoscopic silver wires by electrochemical deposition

• Sheng Zhong,
• Thomas Koch,
• Stefan Walheim,
• Harald Rösner,
• Eberhard Nold,
• Aaron Kobler,
• Torsten Scherer,
• Di Wang,
• Christian Kübel,
• Mu Wang,
• Horst Hahn and
• Thomas Schimmel

Beilstein J. Nanotechnol. 2014, 5, 1285–1290, doi:10.3762/bjnano.5.142

• the growth rate of the wires is of the order of 10 μm/s in our experiments and that the entropy of interfacial phase transition for silver is small. The faces tend to be roughened [34] and the surfaces of the wires are rounded without obvious faces. This may indicate that the surface is rough on