An adapted Coffey model for studying susceptibility losses in interacting magnetic nanoparticles

• Mihaela Osaci and
• Matteo Cacciola

Beilstein J. Nanotechnol. 2015, 6, 2173–2182, doi:10.3762/bjnano.6.223

• orientations model of the magnetic moments [12][15]. In this model, we may assume that the magnetic moments μi are constrained to stable orientations along the local minimum of free energy, when the energy barriers are large in comparison with kBT. Due to thermal fluctuations, the time behaviour of μi is

• determining energy barriers in the systems with interactions is quite complex. Generally, in 3D space, the normalized (over kBT) free energy of the i-th spherical nanoparticle, subject to a local magnetic field [13], is: where ξi = (μ0 Ms Vi Hi)/(kBT), σi = (Ki,effVi)/(kBT), and Ki,eff is the effective

• nanoparticle. Without losing the generality of the problem, it is possible to consider a magnetic field acting onto the x–z plane. Considering Equation 14, the normalized free energy of an i-th nanoparticle subject to a local magnetic field Hi applied with an angle ψi to the easy axis is given by: The polar

Light-powered, artificial molecular pumps: a minimalistic approach

• Giulio Ragazzon,
• Massimo Baroncini,
• Serena Silvi,
• Margherita Venturi and
• Alberto Credi

Beilstein J. Nanotechnol. 2015, 6, 2096–2104, doi:10.3762/bjnano.6.214

• information about the relative position of the ring and axle components (i.e., whether they are associated or not) contributes to the gating. From the analysis of the free energy change of the system, it can be estimated that the maximum amount of work that could be performed by the pump in a cycle under the

Distribution of Pd clusters on ultrathin, epitaxial TiO_x films on Pt₃Ti(111)

• Christian Breinlich,
• Maria Buchholz,
• Marco Moors,
• Tobias Pertram,
• Conrad Becker and
• Klaus Wandelt

Beilstein J. Nanotechnol. 2015, 6, 2007–2014, doi:10.3762/bjnano.6.204

• Pd metal on the oxide is smaller than twice the surface free energy of the vacuum–metal interface of the liquid metal [19]. In the case of late transition metals on oxides, this criterion is usually met, and thus 3D growth is observed in most cases [14]. From a kinetic point of view, the growth

Metal hydrides: an innovative and challenging conversion reaction anode for lithium-ion batteries

• Luc Aymard,
• Yassine Oumellal and
• Jean-Pierre Bonnet

Beilstein J. Nanotechnol. 2015, 6, 1821–1839, doi:10.3762/bjnano.6.186

• hydride and lithium is given in Equation 3, where MHx is the hydride, M the metal or the intermetallic phase, and x the number of hydrogen atoms. Under standard conditions (p = 1 atm and T = 298 K), the Gibbs free energy of the reaction in Equation 3, ΔrG in kJ·mol−1, can be calculated from the values of

• Gibbs free energy of formation of MHx and LiH (ΔfG°298(LiH) and ΔfG°298(MHx). It corresponds to the sum of reactions (Equation 1 + Equation 2) given as: The Gibbs free energy of the reaction in Equation 3 is: According to the thermodynamics rules, the reaction is feasible for ΔrG°298 ≤ 0 and

• spontaneous for ΔrG°298 < 0. Given the fact that the formation of LiH independent from the type of hydride MHx (common reaction product), another simple criterion to predict the possibility of the conversion process is the Gibbs free energy of formation of the hydride MHx divided by x. This value must be

Two-phase equilibrium states in individual Cu–Ni nanoparticles: size, depletion and hysteresis effects

• Aram S. Shirinyan

Beilstein J. Nanotechnol. 2015, 6, 1811–1820, doi:10.3762/bjnano.6.185

• .6.185 Abstract In isolated bimetallic nanoscale systems the limit amount of matter and surface-induced size effects can change the thermodynamics of first-order phase transformation. In this paper we present theoretical modification of Gibbs free energy concept describing first-order phase

• one has to plot the Gibbs free energy densities as functions of composition and then find the conditions for minimal energy of a given system by using the rule of common tangent [22]. Corresponding modification and theoretical descriptions for nanosystems may be done taking into account the additional

• energy condition. As result the stable phase in bulk material (say, phase 1) is one which has the lowest bulk Gibbs free energy density g (energy per number of atoms in a system): g1 < g2. Subindexes 1 and 2 are referred to the phase 1 or phase 2, respectively. In a multicomponent system it also depends

Influence of surface chemical properties on the toxicity of engineered zinc oxide nanoparticles to embryonic zebrafish

• Zitao Zhou,
• Jino Son,
• Bryan Harper,
• Zheng Zhou and
• Stacey Harper

Beilstein J. Nanotechnol. 2015, 6, 1568–1579, doi:10.3762/bjnano.6.160

• estimate the protein-ligand binding free energy [35], and molar refractivity (RF) represents the energy required to polarize one mole of the substance and is associated with receptor binding affinity [36]. Dreiding energy (DE) will be used to predict the binding affinity of organic molecules with Zn and

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

• 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

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

• mechanics in order to obtain the Gibbs free energy of bulk and interfaces at finite temperatures. Especially for the calculation of differences of Gibbs free energies, which are relevant for the determination of stable equilibrium configurations, the accuracy is higher than might be expected from the

• ], which provide an approximate continuous description of the dynamics of interfaces [27]. They need as input the interface free energies between the phases. This interface free energy is accessible to DFT simulations [28][29]. On the basis of this information the intercalation properties of phase

• 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

Observing the morphology of single-layered embedded silicon nanocrystals by using temperature-stable TEM membranes

• Sebastian Gutsch,
• Daniel Hiller,
• Jan Laube,
• Margit Zacharias and
• Christian Kübel

Beilstein J. Nanotechnol. 2015, 6, 964–970, doi:10.3762/bjnano.6.99

• TEM (see insets of Figure 3b and Figure 3c) and electron diffraction, we found that both samples feature a high degree of crystallinity as is corrobated by detailed Raman studies [20][42]. However, the Si NC shape is not spherical at all. Due to the minimization of Gibbs free energy, a spherical shape

Capillary and van der Waals interactions on CaF₂ crystals from amplitude modulation AFM force reconstruction profiles under ambient conditions

• Annalisa Calò,
• Oriol Vidal Robles,
• Sergio Santos and
• Albert Verdaguer

Beilstein J. Nanotechnol. 2015, 6, 809–819, doi:10.3762/bjnano.6.84

• obtained experimentally by leaving the ambient humidity spontaneously increase from 10% to the ambient value of 40% after sample preparation (see Experimental section). This increase of RH should reduce the free energy barrier for water nucleation, thus increasing the water condensation rate [3]. It is

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

• , in the most stable all-trans conformation of the (CH2)n molecular backbone [17][22]. However, increasing temperature has a strong influence on the tethered polymethylene OML structure because new chain configurations can be reached from this free energy minimum by a trans–gauche isomerization

• vibrations) are so strongly coupled as to be indistinguishable, the excitation must be treated by using the transition state theory and the Eyring equation, with a free energy for the transition, ΔG = ΔE − TΔS that includes the large entropy associated with this fluctuation. Hence, the resulting frequency

Electrical properties of single CdTe nanowires

• Elena Matei,
• Camelia Florica,
• Andreea Costas,
• María Eugenia Toimil-Molares and
• Ionut Enculescu

Beilstein J. Nanotechnol. 2015, 6, 444–450, doi:10.3762/bjnano.6.45

• electrodeposited semiconductor. The mechanism leading to the formation of the stoichiometric compound was thermodynamically explained based on the free energy corresponding to the compound formation reaction. In the case of this particular compound, this free energy opens up the possibility to obtain the

Exploiting the hierarchical morphology of single-walled and multi-walled carbon nanotube films for highly hydrophobic coatings

• Francesco De Nicola,
• Paola Castrucci,
• Manuela Scarselli,
• Francesca Nanni,
• Ilaria Cacciotti and
• Maurizio De Crescenzi

Beilstein J. Nanotechnol. 2015, 6, 353–360, doi:10.3762/bjnano.6.34

• ][15][16], where the free energy surface presents one absolute minimum and one or more local minima separated from the former by large free energy barriers, as compared to the thermal energy. Metastability can also have a technological importance, as in practice, it represents a way of extending the

• stable because lower in surface free energy. Moreover we fitted our data in Figure 4b with Wenzel’s equation [1] where r is the roughness factor (i.e, the ratio between the actual wet surface area and its projection on the plane). Interestingly, the fit returned r = 1.08 ± 0.01, which means that

The fate of a designed protein corona on nanoparticles in vitro and in vivo

• Denise Bargheer,
• Julius Nielsen,
• Gabriella Gébel,
• Markus Heine,
• Sunhild C. Salmen,
• Roland Stauber,
• Horst Weller,
• Joerg Heeren and
• Peter Nielsen

Beilstein J. Nanotechnol. 2015, 6, 36–46, doi:10.3762/bjnano.6.5

• nm) is much smaller than the adsorbent. If the nanoparticle and protein are in the same size, the Langmuir adsorption formalism seems not to be valid. This was discussed by Liu et al. using small CeO2-particles and bovine serum albumin with similar size of 7 nm [36]. The smaller surface free energy

SERS and DFT study of copper surfaces coated with corrosion inhibitor

• Maurizio Muniz-Miranda,
• Francesco Muniz-Miranda and
• Stefano Caporali

Beilstein J. Nanotechnol. 2014, 5, 2489–2497, doi:10.3762/bjnano.5.258

• the 1H tautomer is more stable than the 4H having an energy of −242.320444 Hartree and −242.309585 Hartree, respectively, as discussed in the literature [18]. In addition, the calculated free energy difference indicates that the 1H tautomer is more stable than 4H, resulting in ΔG = 6.22 kcal/mol, the

Nanoparticle interactions with live cells: Quantitative fluorescence microscopy of nanoparticle size effects

• Li Shang,
• Karin Nienhaus,
• Xiue Jiang,
• Linxiao Yang,
• Katharina Landfester,
• Volker Mailänder,
• Thomas Simmet and
• G. Ulrich Nienhaus

Beilstein J. Nanotechnol. 2014, 5, 2388–2397, doi:10.3762/bjnano.5.248

• ligand densities and the receptor-ligand binding energy. It competes with the energy cost required to bend the membrane, which depends on the membrane tension and the NP curvature and, therefore, on the NP size. If the overall energy balance is equivalent to a localized decrease in the Gibbs free energy

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

• deposition [34]. Ge islands exhibiting a Ge-rich core were shown to be related to growth conditions promoting far-from-equilibrium states, controlled by kinetic processes, which is more typical for the case of MBE growth [34]. Equilibrium is reached through free energy minimization, taking into account the

Inorganic Janus particles for biomedical applications

• Isabel Schick,
• Steffen Lorenz,
• Dominik Gehrig,
• Stefan Tenzer,
• Wiebke Storck,
• Karl Fischer,
• Dennis Strand,
• Frédéric Laquai and
• Wolfgang Tremel

Beilstein J. Nanotechnol. 2014, 5, 2346–2362, doi:10.3762/bjnano.5.244

• theory of heterogeneous nucleation, this can be achieved by decreasing the concentration of the precursor below supersaturation, at which the homogeneous nucleation would be favourable [61]. Furthermore, the additional term of Gibbs free energy for the adhesive energy at the interface between the seeds

Liquid-phase exfoliated graphene: functionalization, characterization, and applications

• Mildred Quintana,
• Jesús Iván Tapia and
• Maurizio Prato

Beilstein J. Nanotechnol. 2014, 5, 2328–2338, doi:10.3762/bjnano.5.242

• cycloaddition of benzynes were found to be energetically as strong as the attachment of hydrogen atoms, while for the 1,3-dipolar cycloaddition, the free energy of the reaction is slightly smaller [36]. Additionally, carbon atoms which localize at graphene edges are considered to be more reactive than carbon

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

• . Therefore, in order for an enzyme–substrate reaction to advance spontaneously, it needs to be set to free energy change: ΔG = ΔH − TΔS < 0, and enthalpy (ΔH) must also decrease greatly with the entropy (enthalpy–entropy compensation or isokinetic theory) [28]. In fact, the change of enthalpy, ΔH‡, will

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

• structural fluctuations of the proteins and/or the polymer shell around the NPs at higher temperatures, which could cause major structural changes forming a free energy-optimized binding interface. In our earlier work, we used NPs with a chemically well-defined, carboxylic acid-functionalized surface to

• denature. In general, a protein molecule interacting with a NP may change and even completely denature if the interaction free energy is comparable or larger than the internal energy needed to stabilize its structure. Notably, proteins consist of typically a few thousand atoms but are stabilized by an

Electronic and electrochemical doping of graphene by surface adsorbates

• Hugo Pinto and
• Alexander Markevich

Beilstein J. Nanotechnol. 2014, 5, 1842–1848, doi:10.3762/bjnano.5.195

• doping of graphene occurs when certain surface adsorbates participate in electrochemical redox reactions in which graphene plays the role of an electrode. Such reactions occur spontaneously if the total Gibbs free energy is negative and the diffusion and reaction barriers are sufficiently low for the

• reaction proceed at room temperature. The total Gibbs free energy change is given by ΔG + W for p-doping and ΔG − W for n-doping, where ΔG is the free energy for the molecular reaction and W is the work function of graphene. The work function of graphene is expected to be similar to that of graphite, about

• involving H2O/O2 and graphene as in The value of ΔG of this reaction can be calculated from the tables of free energies to be −4.82 eV [19]. Under the assumption that electrons for the above reaction are taken from graphene the total Gibbs free energy change is −4.82 + W or −0.3 eV. Thus, the reaction will

Real-time monitoring of calcium carbonate and cationic peptide deposition on carboxylate-SAM using a microfluidic SAW biosensor

• Anna Pohl and
• Ingrid M. Weiss

Beilstein J. Nanotechnol. 2014, 5, 1823–1835, doi:10.3762/bjnano.5.193

• the sensor to an electrical signal by the direct piezoelectric effect. The ability to easily calibrate the system with high performance [35] is essential to ensure the observed changes in the acoustic wave are indicative of changes in the system free energy which changes as a function of mass transfer

Non-covalent and reversible functionalization of carbon nanotubes

• Antonello Di Crescenzo,
• Valeria Ettorre and
• Antonella Fontana

Beilstein J. Nanotechnol. 2014, 5, 1675–1690, doi:10.3762/bjnano.5.178

• as phenylethyl alcohol [38] or N-methylpyrrolidone (NMP) [39]. Indeed NMP has been demonstrated to enter the bundles during sonication and remain strongly bound to the nanotube surface. This leads to an enthalpy of mixing that is approximately zero conferring to the corresponding free energy of

• demonstrated [69] to wrap the nanotube exposing their polar domains towards the aqueous environments while favoring the contact of their hydrophobic domains with the nanotube surface. The wrapping of the SWCNTs by water-soluble polymers is a thermodynamically driven phenomenon because the free energy cost of

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

• structural/basic units that constitute a grain/interphase boundary/interface could be a collection of different ensembles of atoms whose number, size and shape are governed by the well-known free energy equation where U is the internal energy, P the pressure, V the volume, T the absolute temperature, S the

• more than one species is present in a material, i.e., short-range order always exists. This is due to the presence of interatomic (including electronic) attractive and repulsive forces and the drive to decrease the free energy of the system. Equation 1 applies to a cluster of atoms. When it gets