Odd-even Effect Research Articles

The effect of position of (-)-menthyl on the mesomorphic and photoisomerization behavior in azobenzene chiral liquid crystals

As the mesomorphic type of liquid crystals could be largely altered by the molecular chirality, we herein explored the effect of position of chiral (-)-menthyl on the mesomorphic and photoisomerization behavior in azobenzene liquid crystals. By modifying the position of chiral (-)-menthyl in the menthol based liquid crystal compounds through gradually increasing the alkyl chain length of the dicarboxylic spacer, seven new chiral liquid crystal compounds 4-(4-menthyloxy-n-oxoalkanoyloxy)-4′-(4-ethoxybenzoyloxy) azobenzene MnAZO2B (n = 2–8) were prepared. A combination of analysis methods was conducted to systematically investigate their structures, mesophase behaviors and optical properties. The length and parity of the flexible spacers has a dramatic influence on the mesomorphic behaviors, and an odd-even effect is observed for these chiral liquid crystal compounds.

Chain-Length Induced Structural Polymorphism for two-dimension self-assembly

Structural polymorphism obtained through the 2D self-assembly which was made use of the chain-ength induced, has has aroused wide concern. On the one hand, owing to its significance meaning in crystal engineering, on the other hand, it has a broad application prospect in nano science and technolog.The assembly of symmetric 2, 7-bis (n-alkoxy) -9-fluorenone(F-OCn) with varying lengths of peripheral alkyl chains dissolved in homologous acids was investigated. The size and shape of molecules and the structure and position of substituents were critical factors that regulate the equilibrium of the interaction and formation of self-assembled patterns. Useing altered the symmetry and chain-length of the molecular structure, the self-assembly morphology and cellular properties can be predicted. The self-assembled strcture displayed the assembly of F-OCn (11-14). “S” shaped and alternating phases are the thermodynamic stable states. The competition between van der Waals forces from the interdigital alkyl chains and van der Waals forces between molecule-substrate takes effect. The vdW forces between the molecule-substrate was predominant when n varies from 15 to 18. The observation of the chain-length effects and odd-even effects showed that: F-OCeven developed from a loose-and close-packed patterns to a dislocated zigzag patterns.Self-assembled morphology of F-OCodd evolved from a well-distributed trimer monolayer to the dislocated zigzag pattern.These researches offers insight into the structural diversity by regulating the alkyl side chain-length and odd-even effects on two-dimension self-assembly and the construct a new molecular materials.

Interference Measurements of Non-Abelian e/4 & Abelian e/2 Quasiparticle Braiding

The quantum Hall states at filling factors $\nu=5/2$ and $7/2$ are expected to have Abelian charge $e/2$ quasiparticles and non-Abelian charge $e/4$ quasiparticles. The non-Abelian statistics of the latter has been predicted to display a striking interferometric signature, the even-odd effect. By measuring resistance oscillations as a function of magnetic field in Fabry-P\'erot interferometers using new high purity heterostructures, we for the first time report experimental evidence for the non-Abelian nature of excitations at $\nu=7/2$. At both $\nu=5/2$ and $7/2$ we also examine, for the first time, the fermion parity, a topological quantum number of an even number of non-Abelian quasiparticles. The phase of observed $e/4$ oscillations is reproducible and stable over long times (hours) near both filling factors, indicating stability of the fermion parity. At both fractions, when phase fluctuations are observed, they are predominantly $\pi$ phase flips, consistent with either fermion parity change or change in the number of the enclosed $e/4$ quasiparticles. We also examine lower-frequency oscillations attributable to Abelian interference processes in both states. Taken together, these results constitute new evidence for the non-Abelian nature of $e/4$ quasiparticles; the observed life-time of their combined fermion parity further strengthens the case for their utility for topological quantum computation.

Stacking Order, Perfect Spin Polarization, and Giant Magnetoresistance in Zigzag Graphene/ h - BN Heterobilayer Nanoribbons

In a van der Waals heterostructure of two-dimensional materials, electronic properties are tunable by means of stacking orders. Here, we study the spin-dependent quantum transport in the bilayer of ferromagnetic zigzag-edged graphene/hexagonal-$\mathrm{BN}$ nanoribbons (ZGr-BNNRs) using density-functional theory combined with the Keldysh nonequilibrium Green's-function method. We reveal a strong odd-even effect of transport across the ZGr-BNNRs and a giant magnetoresistance value observed only in even-width ZGr-BNNRs. More interestingly, this value can be optimized by engineering stacking orders, yielding the perfect spin polarization efficiency of 100% and the magnetoresistance value of over ${10}^{4}$ in even-width ZGr-BNNRs. Our results provide a route to design and fabricate high-performance spin filters and magnetic storage devices.

Generation of mono-mesophase in allylidene-based homologues with a longer molecular axis

In this article, we have synthesized twenty-eight nematogenic homologous derivatives of allylidene base with cinnamates and benzoates linkages. All nematogenic homologous derivatives were characterized by ultraviolet spectroscopy, Infrared and proton magnetic resonance with study of their mesophase properties by the polarized optical microscope (POM) where they were found to be enantiotropically nematogenic. The thermograms of mesophase transition enthalpies and entropies were recorded by differential scanning calorimetry (DSC). The geometries of all molecules were optimized by DFT/B3LYP method using a basis set def2-SVP, the result of these calculated molecule's geometries for all molecules showed to have an electron-rich longer molecular axis, which enables the molecule to form a stronger pi interaction with adjacent molecules and induces the nematogenic mesophase behavior. The effect of an additional diene system on mesophase behavior of a stepped type of molecules was also studied. The role of the number of rings on mesophase behavior as an odd-even effect on mesophase transition temperature as well as the role of the substitution on the terminal ring for the same was considered.

Layer-Dependent Magnetic Structure and Anomalous Hall Effect in the Magnetic Topological Insulator MnBi4Te7.

The intrinsic antiferromagnetic topological insulator (TI) MnBi4Te7 provides a capacious playground for the realization of topological quantum phenomena, such as the axion insulator states and quantum anomalous Hall (QAH) effect. In addition to nontrivial band topology, magnetism is another necessary ingredient for realizing these quantum phenomena. Here, we investigate signatures of thickness-dependent magnetism in exfoliated MnBi4Te7 thin flakes. We observe an obvious odd-even layer-number effect in few-layer MnBi4Te7. Noticeably, we show that in monolayer MnBi4Te7 the anomalous Hall effect exhibits a sign reversal. Compared with the case of MnBi2Te4, interlayer antiferromagnetic exchange coupling, which is essential for the realization of the QAH effect, is greatly suppressed in MnBi4Te7. The demonstration of thickness-dependent magnetic properties is helpful to further explore the topological quantum phenomena in MnBi4Te7.

Thermoresponse of Odd-Even Effect in n-Alkanethiolate Self-Assembled Monolayers on Gold Substrates.

This study examines thermoresponse of odd-even effect in self-assembled monolayers (SAMs) of n-alkanethiolates (SCn , n=3-18) formed on template-stripped gold (AuTS ) using macro- and microscopic analytical techniques, contact angle goniometry (CAG) and vibrational sum frequency generation (VSFG) spectroscopy, respectively. Both CAG and VSFG analyses showed that the odd-even effect in liquid-like SAMs (n=3-9) disappeared upon heating at 50-70 °C, indicating that the heating led to increased structural disorder regardless of odd and even carbon numbers. In contrast, the opposite thermoresponse was observed for odd and even SCn molecules in wax- and solid-like SAMs (n=10-18). Namely, temperature-dependent orientational change of terminal CH3 relative to the surface normal was opposite for the odd and even molecules, thereby leading to mitigated odd-even effect. Our work offers important insights into thermoresponse of supramolecular structure in condensed organic matter.

Simple deep-learning approach for α -decay half-life studies

To exploit the potential of deep learning (DL) in $\ensuremath{\alpha}$-decay studies, we refocus on the essence of DL, which is a nonlinear input-output mapping with a hierarchical learning process. Here, instead of using the residual between experimental data and the calculation, the idea of training DL directly by experimental $\ensuremath{\alpha}$-decay half-life is used. The Levenberg-Marquardt backpropagation algorithm is utilized for fixing free parameters of the mapping. A $\mathcal{K}$-fold cross-validation method is introduced to avoid overfitting and improve the generalization performance of DL, as well as to determine hyperparameters effectively. We find that DL results with both three-dimensional ${Z,A,{Q}_{\ensuremath{\alpha}}}$ and four-dimensional ${Z,A,{Q}_{\ensuremath{\alpha}},l}$ input vectors achieve an impressive accuracy that matches or even exceeds the traditional models. Especially, DL realizes an efficient extraction of the pertinent shell and odd-even staggering effects of half-life solely from the characteristics of ${Q}_{\ensuremath{\alpha}}$ values. On the other hand, the universal decay law (UDL) describes the classical relationship between ${Z,A,{Q}_{\ensuremath{\alpha}}}$ and a-decay half-life, which is homologous with DL. Heuristically, we add the contributions of the angular momentum and blocking effect of unpaired nucleons in the UDL and develop an improved UDL formula.

Tuning the odd-even effect on two-dimensional assemblies of curcumin derivatives by alkyl chain substitution: a scanning tunnelling microscopy study.

Well-ordered molecular arrangement on surfaces is fundamental for fabrication of functional molecular devices which are of particular interest in nanotechnology. In addition to nano-manufacturing, the production of useful materials from natural resources has recently attracted increasing attention. Herein, we focused on the two-dimensional (2D) self-assemblies of curcumin derivatives. The effects of the number, length, and substitution of the alkyl chains on the 2D structures of curcumin derivatives were studied by scanning tunnelling microscopy at the highly oriented pyrolytic graphite/1,2,4-trichlorobenzene interface. Curcumin derivatives containing both methoxy and alkoxy chain groups and those possessing four alkoxy chains exhibit linear structures with and without interdigitation of alkoxy chains, respectively. These 2D structure formations are independent of the alkyl chain length. However, the bisdemethoxycurcumin derivatives periodically form stair-like and linear structures depending on the alkyl chain length, which indicates the existence of the odd-even effect. These results suggest that the 2D structural modulation of curcumin derivatives caused by the odd-even effect can be tuned by the number of alkyl chain substituents. The appearance and disappearance of the odd-even effect in curcumin derivatives are discussed in terms of the balance between intermolecular and molecule-substrate interactions.

The odd–even effect in n-carboxyalkylammonium-containing organic–inorganic hybrids of Mn(ii) halides: structural and magnetic characterisation

The combination of n-carboxyalkylamines with MnCl2 in HCl yields 0D compounds of the formula (NH3(CH2)nCOOH)2[MnCl4(H2O)2] when n = 2 or 4, and 2D halide perovskites of the formula (NH3(CH2)nCOOH)2[MnCl4] when n = 3 or 5.

Determining the probable isotopic existence of superheavy nuclei

Superheavy nuclei, due to a higher neutron to proton ratio, its formation is highly complicated and predicting the feasible isotope which can be synthesised is an important task in the research on superheavy nuclei. Here we propose a method for predicting the isotopic feasibility by determining the coexistence of odd-even effect in the context of calculating Eα, T1/2(α) using the binding energy by FRDM model. The prominent decay mode of Superheavy nuclei, α-decay, is been evaluated for Z=101-130 with A= 220-360 by considering both preformed α-cluster and 2n+2p instant decay. The intersection points in the graphs corresponding to the minimum difference between odd and even neutron contribution yield the most probable isotope to be formed and is compared with α-decay half-life calculations by Brown formula. Comparison of the results with known synthesised nuclei yield a close agreement with each other.

Experimental study of high-energy fission and quasi-fission dynamics with fusion-induced fission reactions at VAMOS++

During the last decade, the use of inverse kinematics in the experimental study of fission is bringing a wealth of new observables obtained in single measurements, allowing their analysis and their correlations. An ongoing application of this technique is the basis of a series of experiments performed with the variable-mode, large-acceptance VAMOS++ spectrometer at GANIL. A recent experiment has been focused on the survival of the nuclear structure effects at high excitation energy in fission and quasi-fission. The full isotopic identification of fragments, the fission dynamics and the ratio between the production of fragments with even and odd atomic numbers, the so-called proton even-odd effect, are shown. The latter shows a different mechanism for fission and quasi-fission that could be used to separate fission from quasi-fission.

CSR dan Nilai Perusahaan: Peran Odd-Even Effect Dewan Direksi, Umur dan Ukuran Perusahaan

Firm value is one indicator in investing. The study aims to examine the effect of Corporate Social Responsibility (CSR) on firm value by using firm age, board of directors odd-even effect and company size as moderating variables for companies listed on the Sri Kehati Index from 2013-2019. The research sample consisted of 84 observations and data were analyzed using multiple linear regression models and Moderated Regression Analysis (MRA). The results of the study show that CSR has a positive and significant effect on firm value. The results also show that firm age, board of directors odd-even effect and firm size moderate the relationship between CSR and firm value.
 Keywords: Board Meeting Efficiency; Company Value; Corporate Social Responsibility; Company Size; Company Age

17.9 MeV’lik Enerjide (p,α) Tesir Kesiti Verileri üzerine Sistematik Bir İnceleme

Nuclear cross section data are needed in various applications such as radiation therapy, astrophysics, radioisotope production, fusion and fission. The systematics play a very important role in determining cross sections on neutron- and proton-induced reactions at incoming energies of which there are no experimental values. So, empirical systematics have been extensively used at present in the studies on cross section calculations. In this paper, we proposed empirical cross section formulas considering Q–value dependence on (p,α) reactions at proton energy of 17.9 MeV. The present formulas including Coulomb and odd-even effects are based on the statistical theory. In addition, these formulas are a modification to the Levkovskii’s original asymmetry parameter formulas for neutron induced reactions and the Tel et al.’s empirical formulas for proton reactions. Fitting parameters of formulas were determined by least-squares fitting to experimental excitation function data. It is seen that new empirical formulas give good fits with (p,α) experimental cross section values in the literature at 17.9 MeV.

Molecular Arrangement and Thermal Properties of Bisamide Organogelators in the Solid State.

The crystal structure and phase behavior of bisamide gelators are investigated using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy, X-ray diffraction (XRD), and molecular modeling, aiming at a better understanding of bisamide gel systems. A homologous series of bisamide model compounds (nBAs) was prepared with the (CH2)n spacer between the two amide groups, where n varies from 5 to 10, and with two symmetric C17 alkyl tails. With increasing spacer length, the thermal properties show a clear odd-even effect, which was characterized using our newly developed analytical model DSCN(T). Using XRD, all studied nBA compounds turn out to have a layer-like structure. The XRD patterns of the odd BA series are very similar but show marked differences compared to the XRD patterns of the even series, which in turn are very similar. The odd-membered 5BA molecules are nearly perpendicular to the stacked layers, as described by a pseudo-orthorhombic unit cell, whereas the even-membered 6BA molecules are tilted at an angle with respect to the layer normal, as described by a triclinic unit cell. In both the odd and even series, the inter-layer interaction is the van der Waals interaction. The 6BA hydrogen bonding scheme is very similar to that of Nylon 6,10 α, unlike the 5BA H bonding scheme. The packing of the C17 alkyl tails in the 5BA layers is similar to polyethylene, and unlike 6BA. The slightly higher crystalline density of 6BA (1.038 g cm-3) as compared to 5BA (1.018 g cm-3) explains the higher melting point, higher enthalpy of fusion, and the observed shift of N-H stretch bands to higher wave numbers. The structural differences observed between the odd and even BA series reflect the different structure-directing effect of parallel versus antiparallel amide hydrogen bonding motifs. These differences underlie the observed odd-even effect in the thermal properties of nBA compounds.

Facile Synthesis of Liquid Crystal Dimers Bridged with a Phosphonic Group.

Liquid crystal (LC) dimers with well-defined composition and structure arouse broad attentions for their exhibiting LC properties beyond conventional low molar mass mesogens and serving as fascinating model compounds for LC polymers. Here in this work, a series of LC dimers bridged with a phosphonic group have been synthesized through a facile free radical mediated addition reaction between hypophosphorous acid and vinyl terminated cyanobiphenyl mesogens with variant length alkyl spacers. In addition, two esterified derivatives and a group of mono-addition homologues with a terminal phosphonic acid group have also been prepared for comparison study. All the newly synthesized compounds exhibit monotropic nematic (N) phase with typical schlieren textures except for the LC dimer with the longest eleven-methylene spacer, which surprisingly shows twist-bend nematic (NTB ) phase directly from the isotropic state upon cooling. Moreover, the thermal transition properties such as the nematic-isotropic transition temperatures and associated entropy changes of the series LC dimers display a modest odd-even effect. Furthermore, both the LC dimers and the mono-addition homologues in N phase are quite easy to achieve homeotropic alignment upon annealing thanks to the supramolecular interactions between the introduced phosphonic acid group and the hydroxylated glass surface. This work thus provides a novel synthesis strategy for a class of LC materials bridged with a phosphonic acid group prone to further functionalization, which may serve as promising vertical alignment agents and pave the way for developing a new kind of functionalized LC materials of NTB phase.

Crystallization-induced emission enhancement of alkyl chain-dependent pyrene-based luminogens: Visual detection of nitro-explosives

In view of the widespread applications and urgent need for efficient blue emitting materials, the synthesis of such materials has seen renewed interest. In the present work, three alkyl chain-dependent blue emitting pyrene-based luminogens were synthesized and characterized. The experimental results show that these luminogens exhibited high photoluminescence efficiency both in solution (>86%) and in the solid state (>35%). Interestingly, 1,3,6,8-tetrakis (pentylphenyl)pyrene (TPPy), as a photoelectric functional material, was endowed with higher quantum yield (72%) and competitiveness due to a remarkable crystallization-induced emission enhancement (CIEE) property. More importantly, TPPy exhibits high sensitivity and selectivity for ortho-nitroaniline (o-NA) with low limit of detection (9.99 × 10−8 M), which is mainly due to the distinctive odd-even effects of the terminal alkyl chain. The results demonstrate that this type of luminogen can potentially be utilized for practical applications in the field of contaminant or explosive detection as a sensitive and portable fluorimeter.

Dimer-parity-dependent odd-even effects in photoinduced transitions to cholesteric and twist grain boundary smectic-C^{*} mesophases: Experiments and simulations.

We describe investigations on the influence of the flexible spacer parity and length of the guest photoactive liquid-crystalline dimers in guest-host mixtures exhibiting photoinduced transitions involving isotropic (I), cholesteric (N^{*}), and twist grain boundary smectic-C^{*} (TGBC^{*}) phases. Despite a small concentration (3 wt. %) of the guest molecules, the transition temperatures and their photodriven shift (δT) show a strong odd-even parity (of the dimer) dependent effect, with the even-parity systems having a larger value than their odd-parity counterparts; δT is larger for the N^{*}-TGBC^{*} transition than for the I-N^{*} one. The photocalorimetric measurements corroborate these features in addition to showing that, in comparison with the absence-of-ultraviolet (UV) case, the transition enthalpy (ΔH) of the I-N^{*} transition in the UV-on case is diminished by 33 and 12% for the mixtures with even- and odd-parity dimers, respectively. The duration for relaxation from the isothermal photodriven transition also exhibits general features of an odd-even influence. Molecular dynamics simulations demonstrate the presence of significant conformational heterogeneity and associated shift in the conformational space on photostimulation of the guest molecules. The change in the effective shape and nematic order parameter is more pronounced in the even-parity system.

Non-linear disulphide-centred S-shaped oligomers with inner and outer spacers connected by aromatic azo moieties

ABSTRACT The synthesis and characterisation of a series of non-linear S-shaped oligomers [bis-n-(2-(6-(4-{4-acetylphenylazo}phenoxy)hexyloxy)phenoxy)alkyl]disulphide are reported. The length of the two outer spacers for this series are retained at n 1 = 6 while the length of the inner spacer, n 2, is varied from four to nine methylene units. All oligomers exhibit monotropic nematic phase except compound with butyl spacer which is non-mesogenic. The odd-even effect can be verified at the I-N transition temperature wherein the oligomers with odd-numbered inner spacers display higher transition temperature in comparison to its even-membered analogous compounds. The molecules in this series exhibit prominent photoisomerisation behaviour that can be validated by the rate of conversion from trans to cis (1620 s) and vice versa (3120 min).

Interactions of nitric oxide molecules with pure and oxidized silver clusters Agn ±/AgnO± (n=11-13): A computational study.

In this work, we have studied, within density functional theory, the interaction of NO with pure and oxidized silver clusters, both anionic and cationic, composed from 11 to 13 Ag atoms. In that size interval, shell closing effects are not expected, and structural and electronic odd-even effects will determine the strength of interaction. First, we obtained that species Agn ± and AgnO± with odd number of electrons (n = 12) adsorb NO with higher energy than their neighbors (n = 11 and 13). This result is in agreement with the facts observed in recent mass spectroscopy measurements, which were performed, however, at finite temperature. The adsorption energy is about twice for oxidized clusters compared to pure ones and higher for anions than for cations. Second, the adsorption of another NO molecule on AgnNO± forms Agn(NO)2 ±, with the dimer (NO)2 in cis configuration, and binding the two N atoms with two neighbor Ag atoms. The n = 12 species show the higher adsorption energy again. Third, in the absence of reaction barriers, all complexes Agn(NO)2 ± dissociate spontaneously into AgnO± and N2O, except the n = 12 anion. The maximum high barrier along the dissociation path of Ag13(NO)2 - is about 0.7eV. Further analysis of projected density of states for Ag11-13(NO)x ± (x = 0, 1, 2) molecules shows that bonding between NO and Ag clusters mainly occurs in the energy range between -3.0 and 3.0eV. The overlap between 4d of Ag and 2p of N and O is larger for Ag12(NO)2 ± than for neighbor sizes. For n = 12, the d bands are close to the (NO)22π orbital, leading to extra back-donation charge from the 4d of Ag to the closer 2π orbital of (NO)2.