Zig Zag Research Articles

A C0-type zig–zag theory and finite element for laminated composite and sandwich plates with general configurations

In order to conveniently develop C0 continuous element for the accurate analysis of laminated composite and sandwich plates with general configurations, this paper develops a C0-type zig–zag theory in which the interlaminar continuity of transverse shear stresses is a priori satisfied and the number of unknowns is independent of the number of layers. The present theory is applicable not only to the cross-ply but also to the angle-ply laminated composite and sandwich plates. On the premise of retaining the merit of previous zig–zag theories, the derivatives of transverse displacement have been taken out from the displacement fields. Therefore, based on the proposed zig–zag theory, it is very easy to construct the C0 continuous element. To assess the performance of the proposed model, the classical quadratic six-node triangular element with seven degrees of freedom at each node is presented for the static analysis of laminated composite and sandwich plates. The typical examples are taken into account to assess the performance of finite element based on the proposed zig–zag theory by comparing the present results with the three-dimensional elasticity solutions. Numerical results show that the present model can produce the more accurate deformations and stresses compared with the previous zig–zag theories.

A Comparative Study in the Development of a Number of Basic Skills in Soccer for Cubs in the Age Category of(9-12) years old

The study aimed at expounding the differences in a number of basic skills in soccer for the late childhood period in the age category of (9-12) years old. The researchers hypothesized that significant differences exist in some basic skills among various ages of the late childhood period between (9-12) years old. The researchers used the descriptive method using the survey which is appropriate to the nature and objectives of the study. The population of the study consisted of (200) pupils joining the primary school team players in the center of Hamdanya District for the academic year (2009-2010) while the study sample consists of (132) players representing (6) schools. the data was collected through survey and analyzing of the contexts of scientific literature pertinent to the subject of the study to determine the basic skills in soccer. The analysis showed that the skills were ( shooting , dribbling, bouncing the ball in the air, pass, and shooting for a short distance). The skills were presented to specialists in this field who validated. The researchers used the following tools for (SPSS) package software (Arithmetic mean, standard deviation, Pearson’s simple correlation coefficient, (F-Test) for unidirectional variance analysis, percentage, and (L.S.D). The researchers reached a number of conclusions as follows : o The arithmetic means showed a development in the basic skills of soccer with the progress in age (9-10) (10-11) )(11-12) . o Real and ordered differences were found based on the statistical significance among the three age categories in the skills of (shooting) represented by (shooting towards a goal drawn on the wall) , and the skill of dribbling (represented by the test of zig zag running with ball) , and the control of the ball represented by the control of the ball in the air . o Non ordered differences exists between the age categories in the skills of passing (represented by passing to a target drawn on the ground) , and precision of shooting as no significant differences were shown between the ages of (9-10) (10-11) in those skills. Based on above , the researcher recommended a number of recommendations.

Modelling the role of size, edge structure and terminations on the electronic properties of graphene nano-flakes

The addition of graphene nano-flakes to the suite of materials for graphene-based nanotechnology requires a complete understanding of the relationship between shape, structure, properties and property dispersion. Due to the large number of configurational degrees of freedom, this is a very challenging undertaking, particularly if morphological ensembles contain a reasonable array of sizes, shapes (edges and corners) and edge/corner terminations. We report results of density functional tight-binding simulations of zigzag (ZZ) and armchair (AC) hexagonal graphene nano-flakes, with unterminated, monoyhydride or dihydride terminated edges and corners. We find that hexagonal nano-flakes with AC edges are most likely to be achievable experimentally, providing that sufficient H is present during synthesis (or processing) to facilitate dihydride edge and corner passivation, forming a circumference of sp3 hybridized C atoms. This is significant, since the energy of the Fermi level and electronic density of states in the vicinity of the Fermi level are sensitive to the structural and chemical characteristics of the atoms around the circumference, which can be modified post-synthesis.

Fabrication, characterization and some applications of graded chiral zigzag shaped nano-sculptured silver thin films

Graded chiral zig–zag shaped nano-sculptured silver thin films (GCZSSTF) were produced in two stages using oblique deposition technique together with rotation of substrate about its surface normal while a shadowing block was also fixed at the center of the substrate holder. Chrystallographic and morphological structure of these films were obtained using X-ray diffraction (XRD) and atomic force microscopy (AFM). Spectrophotometry was used to obtain their optical behavior while their application in both hydrophobicity and gas sensing was also investigated. XRD results showed a dominant (1 1 1) orientation growth on the zig arm of the structure while by addition of the second arm (zag) the crystallographical growth orientation changed to (2 2 0). The anisotropic nano-structure of these films was also distinguished through (1 − R) spectra. A common peak at about 350 nm related to the TM mode of plasmon resonances and a broad shoulder at about 420 nm for the s-polarized light and at 620 nm for the p-polarized light corresponding to the LM mode of plasmon resonances are observed. These peaks are directly related to the nano-columns topography. The film system used here proved to act as a physical method for producing layer-by-layer structure for obtaining enhanced hydrophobic surfaces rather than the usual chemical methods reported in the literature. In addition, the GCZSSTF also acted as good as reported results for nano-tubes when applied as cathode in the field ionization gas sensing setup.

3D purely inorganic lead-azide coordination polymer constructed by exclusive end-to-end azido binding

One pot synthesis of a purely inorganic framework of azido-lead(II) complex with molecular formula [Pb 3(N 3) 6] n has been made by using 5-aminotetrazole (5-ATZ) ligand as starting material. X-ray single crystal structure determination revealed the presence of two types of Pb-centers (Pb1 and Pb2). One-dimensional propagation of Pb1 centers with azide segment gives an infinite zig–zag 1D chain along c-axis. 2D sheet is formed along bc- and ac-plane with the 1D chain. It is interesting to identify another infinite 1D chain along a-axis by connecting Pb2 centers via azide linkage. The compound displays an overall 3D structure. All the connectivity of azide in complex 1 show exclusive end-to-end ( i.e., μ-1,3) binding.

Simulated defect and interface engineering for high power Li electrode materials

Correlations between the ionic conductivity and antisite disorder in low cost cathode materials (1D Li+ conducting LiFePO4 and quasi-1D LiFeSO4F) and the origin of the experimentally observed drastic conductivity enhancement in nanoscale heterostructures LixFePO4:Li4P2O7 are explored by molecular dynamics (MD) simulations with a novel bond valence (BV) based force-field. Compared to bulk values, ionic conductivity in surface-modified LixFePO4 is enhanced by up to 3 orders of magnitude. Details of dynamic ion transport pathways are extracted by our BV transport pathway analysis applied to MD simulation trajectories. Besides heterogeneous doping by the redistribution of mobile ions across the interface, ion mobility varies as quantified via the extension of unoccupied accessible pathway regions. A layer-by-layer analysis indicates a maximum mobility close to the interface, but Li+ mobility remains enhanced even at the center of the simulated nanocrystals. Li+ diffusion in LiFeSO4F exhibits a pronounced anisotropy with a “superionic” zig–zag pathway parallel to [111] involving partially occupied Li sites. A notable long range ion diffusion rate can be maintained in macroscopic LiFeSO4F crystals due to the moderate activation energy for migration perpendicular to the channels.

Interaction of Methane with Single-Walled Carbon Nanotubes: Role of Defects, Curvature and Nanotubes Type

We investigate the interaction of single-walled carbon nanotubes (SWCNTs) and methane molecule from the first principles. Adsorption energies are calculated, and methane affinities for the typical semiconducting and metallic nanotubes are compared. We also discuss role of the structural defects and nanotube curvature on the adsorption capability of the SWCNTs. We could observe larger adsorption energies for the metallic CNTs in comparison with the semiconducting CNTs. The obtained results for the zig zag nanotubes with various diameters reveal that the adsorption energy is higher for nanotubes with larger diameters. For defected tubes the adsorption energies are calculated for various configurations such as methane molecule approaching to the defect sites pentagon, hexagon, and heptagon in the tube surface. The results show that the introduce defects have an important contribution to the adsorption mechanism of the methane on SWNTs.

The staggered vertex model and its applications

New solvable vertex models can be easily obtained by staggering the spectral parameter in already known ones. This simple construction reveals some surprises: for appropriate values of the staggering, highly non-trivial continuum limits can be obtained. The simplest case of staggering with period 2 (the case) for the six-vertex model was shown to be related, in one regime of the spectral parameter, to the critical antiferromagnetic Potts model on the square lattice, and has a non-compact continuum limit. Here we study the other regime: in the very anisotropic limit, it can be viewed as a zig–zag spin chain with spin anisotropy. From the Bethe–Ansatz solution, we obtain the central charge c = 2, the conformal spectrum and the continuum partition function, corresponding to one free boson and two Majorana fermions. Finally, moving in more physical territory, we obtain a massive integrable deformation of the model on the lattice. Interestingly, its scattering theory is a massive version of the one for the flow between minimal models. The corresponding field theory is argued to be a complex version of the C(2)2 Toda theory.

First principle conductance calculation of zigzag, armchair and mixed geometries of S–6C–4H–S structures

We investigated ballistic transport properties of armchair (AC), zigzag (ZZ), mixed, rotated-AC and rotated-ZZ geometries of small molecules made of 2S, 6C & 4H atoms which exhibit sp–sp 2 hybridization. Well-tested first principle scattering states formalism implemented in Quantum Espresso package has been employed to perform the calculations. The chains made of 6C-atoms with 1S-atom at each end and 4H-atoms attached to different C-atoms have been relaxed. This resulted in AC, ZZ, mixed geometry structures. Differences in transmission coefficient ( T) curves of AC, ZZ and mixed molecules suggest geometry dependence of conductance and are in accordance with the previously reported results for AC and ZZ nanoribbons. In addition, our computed results for rotated-AC and rotated-ZZ suggest that the angle between electrode surface layers and molecular axis plays dominant role, compared to the role of angle between S–C bond and electrode surface layers, in determining conduction through the structure. The structures with molecular axis perpendicular to electrode surface layers yield higher conductance values.

Micro- to nanoscale surface morphology and friction response of tribological polyimide surfaces

Sintered polyimide surfaces that were worn under macroscale conditions at different temperatures, were further characterised by contact-mode atomic force microscopy for getting insight in the tribophysical and -chemical processes at the micro- to nanoscale. Depending on the temperature, either mechanical interaction (23 °C < T < 100 °C), hydrolysis (120 °C < T < 140 °C), or imidisation (180 °C < T < 260 °C) results in different microscale surface characteristics. At low temperatures, surface brittleness and inter-grain fracture has been observed with an almost homogeneous friction pattern. At intermediate temperatures, the formation of a protecting local film leads to smoother surfaces with local lubricating properties. At high temperatures, different topographical and frictional patterns are observed depending on local imidisation or degradation. From AFM scans at the sub-micronscale, local debris depositions are observed and correspond to surface locations with locally reduced friction. From AFM scans at the nanoscale, polymer chain orientation is observed with formation of zig–zag or stretched molecular conformation: the latter is not induced by purely mechanical surface interactions or hydrolysis, but mainly results from tribochemically induced imidisation at high sliding temperatures. The present investigation describes the influences of local tribological interactions onto the macroscale wear behaviour of a polymer, and therefore aims at contributing to a better understanding of scaling between macro- to nanolevel tribological response.

Orientation dependence of plastic deformation in nickel-based single crystal superalloys: Discrete–continuous model simulations

The anisotropic mechanical response of single-crystal nickel-based superalloys is simulated. At 1123 K, two uniaxial tensile loading cases are simulated: one along [0 0 1] and another along [1 1 1]. Resulting stress–strain curves, stress distributions, interfacial dislocation structures are analysed. In accordance with experiments, the simulations show an anisotropic yield strength. The applied strain is accommodated by dislocations propagating through matrix channels on octahedral slip systems. The net result appears as slip bands along the cubic directions, even though no cubic slip systems are activated. In the [0 0 1] case, the plastic flow is distributed more or less evenly among the three matrix channels, whereas in the [1 1 1] case it is mainly concentrated in one single channel. Typical zig–zag configurations are observed. The elementary mechanisms controlling their formation are explained. Cross-slip does not play any role there. The hardening anisotropy between both loading cases is related to strong differences between the interfacial dislocation microstructures.

Molecular dynamics study of energetics of graphene flakes

Molecular dynamics simulations for graphene flakes of various shapes are performed. The equilibrium structures of graphene flakes are obtained. Round, hexagonal, and rectangular graphene flakes are dealt with, and their sizes are varied from a few angstroms to 200 Å. It is shown that for round and hexagonal graphene flakes of small size, the edge configuration influences their energy in equilibrium. Graphene nanoribbons (GNRs) of various aspect ratios are equilibrated at low temperature. The energies of the equilibrated graphene flakes with zigzag (ZZ) edges are lower than the energies of the equilibrated graphene flakes with armchair (AC) edges. This result corresponds to the scanning tunneling microscopy observations in the literature. The atomic bonds on the edges of graphene flakes with both edge configurations are reconstructed. The bond lengths of such reconstructed edges are smaller than the lengths of the atomic bonds inside them. Therefore, free graphene flakes undergo compressive edge stress and vibrate at finite temperature. Constrained GNRs also vibrate, and the amplitudes of the vibrations of the GNRs with ZZ edges are smaller than those of the GNRs with AC edges. On designing and fabricating GNR devices, GNRs with ZZ edges are more favorable than GNRs with AC edges, and vibrations of GNRs should be taken into account.

Differential expression and processing of transforming growth factor beta induced protein (TGFBIp) in the normal human cornea during postnatal development and aging

Transforming growth factor beta induced protein (TGFBIp, also named keratoepithelin) is an extracellular matrix protein abundant in the cornea. The purpose of this study was to determine the expression and processing of TGFBIp in the normal human cornea during postnatal development and aging. TGFBIp in corneas from individuals ranging from six months to 86 years of age was detected and quantified by immunoblotting. The level of TGFBIp in the cornea increases about 30% between 6 and 14 years of age, and adult corneas contain 0.7–0.8 μg TGFBIp per mg wet tissue. Two-dimentional (2-D) immunoblots of the corneal extracts showed a characteristic “zig–zag” pattern formed by different lower-molecular mass TGFBIp isoforms (30–60 kDa). However, the relative abundance of the different isoforms was different between infant corneas (<1 year) and the child/adult corneas (>6 years). Matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) data of TGFBIp isoforms separated on large 2-D gels show that TGFBIp is proteolytically processed from the N-terminus. This observation was supported by in silico 2-D gel electrophoresis showing that sequential proteolytical trimming events from the N-terminus of mature TGFBIp generate TGFBIp isoforms which form a similar “zig–zag” pattern when separated by 2-D polyacrylamide gel electrophoresis (PAGE). This study shows that in humans TGFBIp is more abundant in mature corneas than in the developing cornea and that the processing of TGFBIp changes during postnatal development of the cornea. In addition, TGFBIp appears to be degraded in a highly orchestrated manner in the normal human cornea with the resulting C-terminal fragments being retained in the cornea. The age-related changes in the expression and processing of corneal TGFBIp suggests that TGFBIp may play a role in the postnatal development and maturation of the cornea. Furthermore, these observations may be relevant to the age at which mutant TGFBIp deposits in the cornea in those dystrophies caused by mutations in the transforming growth factor beta induced gene ( TGFBI) as well as the mechanisms of corneal protein deposition.

New dimeric, trimeric and supramolecular organotin(IV) dithiocarboxylates: Synthesis, structural characterization and biocidal activities

Some new tri-, chlorodi- and diorganotin(IV) dithiocarboxylates ( 1– 10) of 4-benzylpiperidine-1-carbodithioate ligand (L), with general formulae R 3SnL {R = n-C 4H 9 ( 1), C 6H 11 ( 2), CH 3 ( 3) and C 6H 5 ( 4)}, R 2SnClL {R = n-C 4H 9 ( 5), C 2H 5 ( 7), CH 3 ( 9)} and R 2SnL 2 {R = n-C 4H 9 ( 6), C 2H 5 ( 8), CH 3 ( 10)}, have been synthesized by the reaction of organotin(IV) chlorides with the ligand-salt in the appropriate molar ratio. Elemental analysis, Raman, IR, multinuclear NMR ( 1H, 13C and 119Sn) and X-ray crystallographic studies have been undertaken to elucidate the structures of the complexes, both in solution and in solid state. Single-crystal X-ray diffraction study indicate trimeric, dimeric, supramolecular cyclic and supramolecular zig–zag chain structures for complexes 2, 4, 6 and 9, respectively. Square-pyramidal geometry is attributed to complex 9 on the basis of the τ value (0.4). A subsequent antimicrobial study indicates that the compounds are biologically active.

Rho1 has multiple functions in Drosophila wing planar polarity

The frizzled (fz) signaling/signal transduction pathway controls planar cell polarity in both vertebrates and invertebrates. Previous data implicated Rho1 as a component of the fz pathway in Drosophila but it was unclear how it functioned. The existence of a G Protein Binding-Formin Homology 3 (GBD-FH3) domain in Multiple Wing Hairs, a downstream component of the pathway suggested that Rho1 might function by binding to and activating Mwh. We re-examined the role of Rho1 in wing planar polarity and found that it had multiple functions. Aberrant Rho1 activity led to changes in the number of hairs formed, changes in cell shape and F-actin and changes in cellular junctions. Experiments that utilized Rho effector loop mutations argued that these phenotypes were mediated by effects of Rho1 on the cytoskeleton and not by effects on transcription. We found strong positive genetic interactions between Rho1 and mwh, that Rho1 regulated the accumulation of Mwh protein and that these two proteins could be co-immunoprecipitated. The Mwh GBD:FH3 domain was sufficient for co-immunoprecipitation with Rho1, consistent with this domain mediating the interaction. However, further experiments showed that Rho1 function in wing differentiation was not limited to interacting with Mwh. We established by genetic experiments that Rho1 could influence hair morphogenesis in the absence of mwh and that the disruption of Rho1 activity could interfere with the zig zag accumulation pattern of upstream fz pathway proteins. Thus, our results argue that in addition to its interaction with Mwh Rho1 has functions in wing planar polarity that are parallel to and upstream of fz. The upstream function may be an indirect one and associated with the requirement for normal apical basal polarity and adherens junctions for the accumulation of PCP protein complexes.

Effect of the carboxyl groups on the assembly of copper pyridinedicarboxylate complexes

Three new copper(II) complexes [Cu(2,4-pydc)(phen)H 2O][Cu(2,4-pydcH) 2H 2O] ( 1), [Cu 2(2,3-pydc) 2(phen)(H 2O) 2]·4H 2O ( 2), [Cu(3,4-pydc)(phen)]·H 2O ( 3) (2,4-pydcH 2 = 2,4-pyridinedicarboxylic acid, 2,3-pydcH 2 = 2,3-pyridinedicarboxylic acid, 3,4-pydcH 2 = 3,4-pyridinedicarboxylic acid, phen = 1,10-phenanthroline) have been hydrothermally synthesized and characterized by the elemental analyses, IR spectra and the single crystal X-ray diffraction. In all three compounds, the coordination sphere of the Cu metal is square–pyramidal geometry, but the three complexes bear different structures. The complex 1 is a 0D structure composed of two separate Cu units, and the complex 2 has a 1D Zig–Zag chain containing 3D hydrogen bonding net, while the complex 3 exhibits a 2D brickwall-like structure.

A Simple Algorithm To Convert Complex Organic Molecules into Their Straight-Chain Conformations

The main body of the article outlines a simple series of steps to transform virtually any organic molecule that is depicted in 2D into its corresponding straight-chain (or zig–zag) conformation. Further to this, a small extension to this algorithm enables one to transform virtually any organic compound given in 2D into any other conformation in 2D. Extremely useful to students, teachers, and practitioners of organic chemistry, such a method is sure to be embraced owing to its ease of utility and its broad applicability.

A convenient Mn III starting material for the synthesis of homo- and heterometallic manganese carboxylate clusters: Mn 9 and Mn 10−xFe x complexes

The use of a convenient source of Mn III ions, namely the [Mn(OR)(O 2CR′) 2] n (R = H, Me, and R′ = Me, Bu t ) family of 1-D coordination polymers, afforded two new enneanuclear and decanuclear molecular clusters, homometallic [Mn 9O 7(O 2CBu t ) 13(MeCN) 2] ( 3) and heterometallic [Mn 10− x Fe x (OMe) 20(O 2CMe) 10] ( x < 10) ( 4), respectively. Compound 3 was synthesized by a solvent-induced structural transformation, whereas complex 4 resulted from the reaction of [Mn(OH)(O 2CMe) 2] n with an Fe III source. The core of 3 comprises two [Mn 4O 2] 8+ butterfly units and a [Mn 3O] 7+ triangular unit fused together by sharing one Mn atom. Magnetic susceptibility measurements of 3 revealed dominant antiferromagnetic interactions within the molecule, and a ground state of S = 1 with many low-lying excited states. Complex 4 is a mixed Fe III/Mn III single-strand molecular wheel, which forms 3D nanotubular stacks arranged in a zig–zag fashion. The described work suggests that the [Mn(OR)(O 2CR′) 2] n compounds represent excellent starting materials for Mn III carboxylate cluster chemistry.

Molting interferes with web decorating behavior in Argiope keyserlingi (Araneae, Araneidae)

Abstract Various orb weaving spiders decorate their webs with extra silk structures. In the araneid genus Argiope, these web decorations consist of flimsy aciniform silk threads arranged in zig zag shaped bands. The adaptive value of these structures is still unclear and controversy over a suite of possible functional explanations persists: the high variation of web decoration adds further uncertainty. Web decorations can differ in shape, size, and frequency across species and even within species. Physiological processes may influence individual variation in web decorating behavior. Molting events are major physiological transitions combined with fundamental alterations of the metabolic state of the spiders. For gaining new insights into possible proximate mechanisms driving web decorating behavior, we observed subadult Argiope keyserlingi Karsch 1878 females in the laboratory and registered the individual variation of web decorations associated with the maturity molt under laboratory conditions. We found...

Metal-free spin channels in graphitic boron–nitrogen nanostructures

Evidence is given for the existence of metal-free spin channels in an insulating medium. First-principles calculations indicate the presence of an unpaired spin, in a ground state boron–nitrogen nanostructure with a carbon zig–zag chain generated by the inclusion of a disclination with either negative or positive Gaussian curvature. The spin-polarized states are delocalized on the carbon chain suggesting possible spintronics applications.