On Generalization to Develop Model of Details of the Leaf Margin using the B-Spline Offset Research on the Leaf Shape Modeling

The aim of this research is to develop a new model of details for the leaf serration before wrapping it onto the overall leaf margin. For this purpose, we used the offset of the original leaf shape outline. The model of the leaf consists of several leaf parts are represented with B-spline curves which also represent the offset. We propose a new algorithm to represent the pattern of the details. The details are applied as an offset to the underlying curve. An algorithm how the pattern combines to the margin was also explained. The results of the drawings are divided into three categories: satisfactory, acceptable, and unsatisfactory. Expert botanist was referred to assess the drawing result to ensure the result is parallel with a botanical point of view. The findings show that the geometry of the details was satisfactory, except for some minor distortion. As the implication, this research allows novice botanists and amateurs to readily see a picture which they might find it hard to visualize before.

MODIFICATION OF SCORING SCHEMES USING DECOMPOSITION PROCEDURES ON STATISTICAL DATA

This paper presents a method of modifying original scores to obtain independent random variables. It includes an analysis of the consequences of using such a method. The paper also describes the mathematical background of the method in detail and discusses the possible use of the method in identifying student or participant assessments that are over- or underrated. The method distinguishes performances of students and assesses their written solutions using a scoring scheme. In this study, it is used to analyze the competence of participants in the Physics Olympiad competition. Scoring schemes that are appropriately set by an author for a physics problem present the participant scores as independent random variables. The assessment solutions are analyzed using analytical tools (such as covariant matrix) for the dependence of random variables. The evaluators of the participants’ solutions were highly qualified professionals. Nevertheless, the study found statistical evidence of minor distortion in the evaluations, though this was found to only marginally affected the ranking of participants

A non-solvated form of [(Z)-O-methyl-N-(2-methylphenyl)thiocarbamato-κS](triphenylphosphane-κP)gold(I): crystal structure and Hirshfeld surface analysis

The title compound, [Au(C9H10NOS)(C18H15P)], features a near linear P—Au—S arrangement defined by phosphane P and thiolate S atoms with the minor distortion from the ideal [P—Au—S is 177.61 (2)°] being traced in part to the close intramolecular approach of an O atom [Au...O = 3.040 (2) Å]. The packing features supramolecular layers lying parallel to (011) sustained by a combination of C—H...π and π–π [inter-centroid distance = 3.8033 (17) Å] interactions. The molecular structure and packing are compared with those determined for a previously reported hemi-methanol solvate [Kuanet al.(2008).CrystEngComm,10, 548–564]. Relatively minor differences are noted in the conformations of the rings in the Au-containing molecules. A Hirshfeld surface analysis confirms the similarity in the packing with the most notable differences relating to the formation of C—H...S contacts between the constituents of the solvate.

Structural Studies of Iron(III) Complexes with N4O2 Coordination Sphere

The Spin-Crossover (SCO) phenomenon implicates a switchable between a low-spin (LS) diamagnetic state, which is stable at low temperatures and a paramagnetic high-spin state (HS), which is stable at higher temperatures. This transition is generated by an external perturbation such as temperature, pressure or light. In general, the switching process in solid-state systems is controlled by cooperative intermolecular interactions. The correlation of structure with physical properties is crucial to the identification of these interactions and ultimately the understanding of the complex processes that control the SCO phenomenon[1]. With the aim of developing new SCO materials, we carried out the syntheses and crystal structure analysis of seven iron(III) complexes, mixing 5-bromo-salicylaldehyde or 5-chloro-salicylaldehyde and ethylendiamine with iron(III) chloride and/or ammonium hexafluorophosphate solutions by slow diffusion or reflux in methanol or 2-propanol (figure 1). The crystal structures show the iron(III) centre is hexacoordinated (FeN4O2) and the coordination polyhedron can be described as a distorted octahedron formed by the 4 N atoms of the ethylenediamine fragment and 2 hydroxyl O atoms from the salicylaldehyde fragment, this distortion was evaluated at 120 and 298 K, the major distortion were observed in complexes [2]+ PF6–· MeOH, [2]+ PF6–·iPrOH and [1]+ PF6–·MeOH, which is characteristic in HS states, while the complexes [2]+ Cl–·iPrOH, [1]+ PF6–·iPrOH [2]+ and [2]+ClO4–, shows a minor distortion according to LS states. On the other hand, [1]+ClO4– is a SCO complex with a typical geometry for both spin states at 120 K (LS) and 298 K (HS). Finally, we studied the intermolecular interactions using Crystal Explorer Software[2] between the iron complexes, the counterion and/or the solvate molecule, for instance, in the [2]+PF6–·MeOH complex, the most remarkable feature observed are Br···Br intermolecular interactions (figure 2). ACKNOWLEDGMENTS: FONDECYT N01130640, FONDEQUIP EQM120095 and Beca CONICYT folio 21130944

Modeling of Early Stages of Formation of Poly-CO

ABSTRACTWe studied the early stages of polymerization of CO under pressure. We performed DFT simulations of 128 and 432 atom models. Structures of random networks found at zero temperature were used for equilibration at 100 K by employing first principles MD. We found that the polymerization begins at 7 - 8 GPa and slightly depends on the size of the model. It turned out that there are several metastable phases of the extended CO solid, corresponding to different compression pressures from 7 - 8 GPa to 15-18 GPa with different numbers of CO fragments, not connected to the random network. We also found that the transition to the phases is irreversible which results in hysteresis loops. Random network structures obtained, say, under 18 GPa could exist at 3 GPa, whereas compression to 3 GPa results in the delta phase of CO crystal, with intact CO fragments and minor distortion of the cubic phase. To analyze the random structure fragments we calculated normal modes and IR intensities using the dipole approximation. Contributions from the main motifs of the random network are identified and compared with experimental IR measurements.

Making mountains

It has been a quiet 20 million years for the pebble: an interlude, at somewhere around 3–4 kilometres under the sea floor. The rock has still been crystallizing, but only very slowly. The water has by now mostly been squeezed out, so little fluid has flowed through that rock. At this depth it is hot, well above 1008°C. The pebble-form is sterile, lifeless. The time is now a little under 400 million years ago. We are in the Devonian Period. Above, at the Earth’s surface, changes have been taking place, but as far as they affected the pebble they could be on another planet. In the sea, the graptolites have been going through an evolutionary rollercoaster, with explosions of diversity separated by bad times, when they only just survive. Soon, one of those bad times will be terminal, and they will disappear from the open seas, never to return. By contrast, the fish are beginning to thrive both in the sea and in rivers and lakes. The land is greening, almost explosively, as plants evolve furiously. None of this affects the future pebble. But something soon will. The sea above has been gradually shallowing, filled in with sediment from the encroaching land. Eventually, it changed, some few million years ago, into a vast coastal plain, traversed by rivers. We are about at the time, now, when that lowland is about to rear up to form a range of mountains that—although much reduced from their early glory—can still be climbed today. What took them so long? For the Iapetus Ocean to the north, which, 50 million years ago, was more than 1000 kilometres across, had effectively disappeared 20 million years ago, the ocean plate sliding beneath the northern continent of Scotland and north America. But on Avalonia, the effect was as if these continents had just slid neatly into place, with only minor distortion of the Avalonian crust (and, in truth, these landmasses did approach each other partly from the side, rather than headon). Did the mountain-building force still come from the north, perhaps as some mysteriously delayed intensification of the vice-like grip that held these landmasses together?

The crystal and molecular structure of perylene

Crystals of perylene, C 20 H 12 , are monoclinic with four molecules in a unit cell of dimensions a = 11.27 7 , b = 10.82 6 , c = 10.26 3 Å, B = 100.55°, space group P 2 1 /a The intensities of 1135 reflexions were measured with a scintillation counter and Mo K a radiation, and the 436 strongest reflexions were used in the structure refinement. The gross features of the structure previously determined from two projections, have been confirmed by the new threedimensional data, the positional and thermal parameters of the carbon atoms have been refined by least-squares and differential syntheses, and the hydrogen atoms have been approximately located. There are small, but significant deviations from a completely planar arrangement ; this minor distortion of the molecule is the result of slight intermolecular steric effects, and does not appear to be associated with any possible overcrowding in the 1, 12 and 6, 7 positions. The mean bond distances agree fairly closely with the values predicted by valence-bond and molecular-orbital calculations; the peri -bond lengths are 1.471 + 0.006 Å. All the intermolecular separations correspond to normal van der Waals interactions; the perpendicular distance between mean molecular planes is 3.46 Å.