Terminal Planes Research Articles

Mass production of micro/nanostructured porous ZnO plates and their strong structurally enhanced and selective adsorption performance for environmental remediation

A facile route was presented for mass fabrication of porous ZnO nanoplates, with a yield of >94%, based on a solvothermal method, using ethylene glycol as the morphology director, and subsequent annealing process. The as-prepared ZnO nanoplates are composed of two terminal non-polar planes with several microns in the planar dimensions and 10–15 nm in thickness. The nanoplates are porous with a pore diameter of 5–20 nm and a high specific surface area (147 m2 g−1). Importantly, such ZnO nanoplates show strong and selective adsorption to cationic contaminants. Especially, they can very efficiently adsorb heavy metal cations in aqueous solution, and have an unsaturated adsorption capacity of more than 1600 mg g−1 for Cu(II) ions, exhibiting a strong, structurally enhanced adsorption performance. The adsorption isotherm is subject to the Freundlich equation, in contrast to that of the commercial ZnO nanopowders, which follows a Langmuir isotherm model. This work not only demonstrates the possibility and validity of the porous ZnO nanoplates as promising adsorbents for contaminant-removal and environmental remediation, but also gives insight into understanding the adsorptive behavior of porous ZnO plates.

Boundary Immittance Operators for the SchrÖdinger–Maxwell Problem of Carrier Dynamics in Nanodevices

We have recently introduced a novel algorithm in which Maxwell equations, discretized by the transmission line matrix method, are coupled to the Schrodinger equation and simultaneously solved. The goal of this study is to develop a method that accounts for deterministic electromagnetic field dynamics together with the quantum coherent transport in the nanoscale environment. We present exact boundary conditions for the Schrodinger equation that rigorously model absorption and injection of charge at the terminal planes. As a nontrivial application of the above concept, we show the dynamics of a charge wavepacket from source to drain electrodes in a carbon nanotube transistor environment. We then compare computed characteristics with experimental ones reported in the literature.

N,N′-Bis(2-hydroxybenzylidene)pentane-1,5-diamine

In the title potential O,N,N',O'-tetradentate Schiff base ligand {systematic name: 2,2'-[pentane-1,5-diylbis(nitrilomethylidyne)]diphenol}, C(19)H(22)N(2)O(2), the mutual orientation of the three planar fragments determines the conformation of the molecule. The dihedral angles between the planes of the two salicylidene groups and the plane of the central extended pentane chain are 78.4 (2) and 62.0 (3) degrees, and the angle between the terminal ring planes is 55.4 (1) degrees. Strong intramolecular O-H...N hydrogen bonds close almost-planar six-membered rings, and the O-H bonds are elongated as a result of hydrogen-bond formation.

(Z)-2-Phenyl-3-(2,2′:5′,2′′-terthiophen-3′-yl)acrylonitrile

In the crystal structure of the title compound, C21H13NS3, one of the terminal thio­phene rings is disordered in approximately a 3:1 ratio of components, and the disorder is of the flip type. The terthio­phene units are far from coplanarity, in contrast to terthio­phene itself. The conformation might be described, for the unit of greater occupancy, as quasi-cis [the S—C—C—S torsion angle is 41.1 (5)°] quasi-trans [the S—C—C—S torsion angle is −140.1 (4)°], and for the less-occupied part as quasi-cis–quasi-cis [35.7 (6)°]. The dihedral angle between the terminal ring planes is as high as 71.7 (2)°. The central C—C=C—C group is almost planar [maximum deviation of 0.027 (3) A] and it is approximately equally twisted with respect to both the central thio­phene and the phenyl ring planes [26.5 (4) and 23.5 (7)°, respectively]. The crystal packing is determined by van der Waals inter­actions, and some weak C—H⋯N and C—H⋯π relatively short directional contacts.

A Bandwidth Enhancement Technique for Mobile Handset Antennas Using Wavetraps

A novel technique for enhancing the impedance bandwidth of wireless terminal antennas is presented. By introducing resonant short circuit transmission lines to the long sides of the chassis edges, an effective electrical shortening of the terminal ground plane is achieved. This effect has been used to realize terminal ground planes with resonant lengths at high frequencies, such as GSM 1800/1900 MHz or UMTS 2 GHz, thereby extending the impedance bandwidth. The proposed technique has been validated by simulations and measurements. Three typical applications are presented where the introduction of wavetraps improves the bandwidth and/or in-band performance

The electrodynamic theory of metal probe-scatterer for measurement of amplitude-phase field distribution in a multimode waveguide

The paper is devoted to a new electrodynamic theory of metal probe-scatterer based on the diffraction pattern of formation of the perturbed (secondary) field. The work discloses peculiar features of measurement of amplitude-phase distribution of the field in the opening (in the terminal planes of analysis) of the multimode guide structure. An algorithm is presented for compensation of multiplicative distortion inherent in the passive sounding method. Experimental results of practical implementation of the method are included.

Exact TLM Boundary Conditions for Closed Homogeneous Waveguide

Abstract In this contribution we introduce a rigorous and efficient method producing exact TLM boundary conditions for closed homogeneous waveguides. This approach uses the modal expansion of the EM field and the modal transfer functions between different planes. The absorbing condition is imposed by sampling the modal coefficients on arbitrary planes inside the TLM-domain and translating them to the terminal planes. Accuracy and efficiency of the method are demonstrated for the H-plane junction and for thick inductive irises in rectangular waveguide, providing excellent wide-band match of the fundamental mode as well as of higher order modes excited by the discontinuity.

Prevalence of normal occlusion traits in deciduous dentition

The aim of this research was to study the normal occlusal patterns of deciduous dentition in Brazilian preschool children. The sample consisted of 356 preschool children, of both genders, aged 3-5 1/2 years from the urban zone of Salvador, Bahia. The occlusion exam was carried out by two examiners, in the classroom, utilizing a wooden spatula. The data were analyzed by the statistical program EPI-INFO 6.02 using the Chi-squared test. The frequency of the type I arch was 43.3% for the upper and 46.3% for the lower arch. The frequency of the type II arch was 56.7% for the upper and 53.75 for the lower arch, however, no difference between genders was noticed. The distribution of primate spaces was: 89.9% for the upper and 67.1% for the lower arch. This prevalence decreased significantly as age increased (p < 0.01). Normal canine relationship was found in almost 60% of the children for the right and left sides. Out of 712 evaluated terminal planes, 55.9% presented mesial terminal step for the primary second molars, 37.9% straight terminal plane and 6.2% distal step. The results permitted to conclude that the presence of generalized spacing between incisors, commonly described by other authors, was not the most prevailing condition for both arches in this sample. On the other hand, primate spaces were the most common ones. The most frequent normal occlusal patterns for canine and molar relationships were found to be the Class I patterns.

NMR-Based model of a telomerase-inhibiting compound bound to G-quadruplex DNA.

The single-stranded (TTAGGG)n tail of human telomeric DNA is known to form stable G-quadruplex structures. Optimal telomerase activity requires the nonfolded single-stranded form of the primer, and stabilization of the G-quadruplex form is known to interfere with telomerase binding. We have identified 3,4,9, 10-perylenetetracarboxylic diimide-based ligands as potent inhibitors of human telomerase by using a primer extension assay that does not use PCR-based amplification of the telomerase primer extension products. A set of NMR titrations of the ligand into solutions of G-quadruplexes using various oligonucleotides related to human telomeric DNA showed strong and specific binding of the ligand to the G-quadruplex. The exchange rate between bound and free DNA forms is slow on the NMR time scale and allows the unequivocal determination of the binding site and mode of binding. In the case of the 5'-TTAGGG sequence, the ligand-DNA complex consists of two quadruplexes oriented in a tail-to-tail manner with the ligand sandwiched between terminal G4 planes. Longer telomeric sequences, such as TTAGGGTT, TTAGGGTTA, and TAGGGTTA, form 1:1 ligand-quadruplex complexes with the ligand bound at the GT step by a threading intercalation mode. On the basis of 2D NOESY data, a model of the latter complex has been derived that is consistent with the available experimental data. The determination of the solution structure of this telomerase inhibitor bound to telomeric quadruplex DNA should help in the design of new anticancer agents with a unique and novel mechanism of action.

Synthesis and Characterization of a Series of Edge-Sharing Octahedral-Tetrahedral-Octahedral Linear Trinuclear Complexes [M(3)(L1O)(4)](2+), Where M = Mn(2+), Co(2+), Ni(2+), Cu(2+), and Zn(2+) and L1OH Is the "Heteroscorpionate" Ligand (2-Hydroxyphenyl)bis(pyrazolyl)methane.

The mixed functionality pyrazole/phenol ligand (2-hydroxyphenyl)bis(pyrazolyl)methane, L1OH, has been used to prepare a series of linear trimetallic systems with the general structural motif [M(3)(L1O)(4)](2+), where M = Mn(2+), Co(2+), Ni(2+), Cu(2+), and Zn(2+). Each of these complexes has been structurally characterized by X-ray crystallography giving the following structural parameters: [Zn(3)(L1O)(4)][BF(4)](2).H(2)O, C(52)H(44)N(16)B(2)F(8)O(5)Zn(3), monoclinic, a = 18.572(4) Å, b = 22.400(5) Å, c = 15.921(3), beta = 112.439(8) degrees, space group C2/c, Z = 4; [Cu(3)(L1O)(4)] [BF(4)](2).2MeCN, C(56)H(44)N(18)B(2)Cu(3)F(8)O(4), monoclinic, a = 40.574(2) Å, b = 16.701(1) Å, c = 19.841(2) Å, beta = 111.388(5) degrees, space group C2/c, Z = 8; [Ni(3)(L1O)(4)][ClO(4)](2).MeCN.0.5H(2)O, C(54)H(44)N(17)Cl(2)Ni(3)O(12.5), monoclinic, a = 12.324(4) Å, b = 26.537(2) Å, c = 18.829(3) Å, beta = 102.78(1) degrees, space group C2/c, Z = 4; [Co(3)(L1O)(4)][BF(4)](2).MeCN, C(54)H(44)N(17)B(2)Co(3)F(8)O(4), monoclinic, a = 12.395(2) Å, b = 26.483(3) Å, c = 18.703(4) Å, beta = 103.22(2) degrees, space group C2/c, Z = 4; [Mn(3)(L1O)(4)(MeCN)][ClO(4)](2).1.4MeCN, C(56.68)H(44)N(18.34)Cl(2)Mn(3)O(12), orthorhombic, a = 15.471(2) Å, b = 17.364(2) Å, c = 24.216(2) Å, space group Pbcn, Z = 4. For Zn(2+), Cu(2+), Ni(2+), and Co(2+) the central metal atom of the linear trimetallic [M(3)(L1O)(4)](2+) unit is four coordinate and has a pseudotetrahedral geometry with a dihedral angle, omega, between the two M(central)O(2)M(terminal) planes of 79.9 degrees (Zn), 61.2 degrees (Co), 60.4 degrees (Ni), and 46.8 degrees (Cu). The central Mn(2+) atom of [Mn(3)(L1O)(4)(MeCN)][ClO(4)](2).1.4MeCN is five-coordinate, with a trigonal bipyramidal stereochemistry, the result of an equatorially coordinated MeCN solvent molecule. Variable-temperature magnetic data indicate that the Ni, Cu, and Mn complexes display modest antiferromagnetic coupling between the metal centers, while the Co derivative is strongly ferromagnetically coupled.

Occlusal relationships and spacing or crowding of teeth in the dentitions of 3-4-year-old Nigerian children.

A study of 525 3-4-year-old children in nursery schools and day-care centres was carried out to assess occlusal relationships and the presence of spacing or crowding of teeth. No significant differences in occlusal relationships were found between boys and girls (P > 0.05). Bilateral straight terminal planes of molars and class 1 canine relationship were the most prevalent features (74.5% and 73.3% respectively). Most of the children had 'normal' vertical and transverse occlusal relationships. The most common sites of spacing were mesial to maxillary canines and distal to mandibular canines. 32% of the children were found to have generalized anterior segment spacing, 4% showed exclusively anthropoid spaces, and 18% had either contact between all the teeth or crowding in the anterior region.

Nature of multilayer steps on the {100} cleavage planes of MgO single crystals

The results of an AFM study of the nature of multilayer steps on the {100} cleavage faces of MgO crystals is described and discussed. The results show that (i) multilayer cleavage steps of a width between 55 and 590 nm and of a slope between about 1 and 8° are stable, (ii) the terminal planes of multilayer steps are composed of high-index vicinal faces with indices (7 0 1), (42 0 1) and (77 0 1) for the 〈010〉 steps with respect to the (100) cleavage, which do not correspond to the low-index planes of the equilibrium form of MgO crystals, and (iii) that the curved parts of the profile of a multilayer cleavage step in its upper and lower regions extend to a distance equal to the width of the step.

Prevalence of malocclusion in 6-year-old Icelandic children: A study using plaster models and orthopantomograms

The prevalence of different malocclusion features was investigated in 396 6-year-old Icelandic children, using the epidemiologic registration method described by Bjork et al. in 1964. Girls were ahead of boys with regard to dental stage (P<0.01). One or more permanent teeth were congenitally missing in 5% of the children. Postnormal occlusion was found in 27% of the boys and in 31% of the girls, and prenormal occlusion was found in 6% and 5%, respectively. Straight terminal plane at the second deciduous molars was found in individuals with either normal or postnormal occlusion. Thus, it can be misleading to use the relation of the terminal planes as a measurement of the sagittal relation between the jaws. The prevalence of hypodontia was much lower than has been reported previously for Icelandic children.

An improved de-embedding technique for the measurement of the complex constitutive parameters of materials using a stripline field applicator

A method for measuring the electromagnetic constitutive parameters of materials using a strip-transmission-line field applicator is presented. A technique is developed to measure the scattering parameters of the imperfect transition regions between the applicator coaxial terminal ports and the front and back terminal planes of the material sample in stripline, S-parameters of the sample region are subsequently deembedded from the coaxial-terminal model. The complex permittivity and permeability of the sample are easily related to the sample's S-parameters through well-known analytic relations. Measured constitutive parameters are presented for several representative materials. >

Coupling between two abruptly terminated single-mode optical fibers

The coupling between two single-mode optical fibers that are abruptly terminated and are facing each other is investigated analytically by means of a coupled system of integral equations. The electromagnetic fields are described by using mixed-spectrum eigenwave representations inside the waveguides, and Fourier integrals are utilized to describe the field between the two guides. Weak guidance conditions on the fiber guides are assumed to facilitate the formulation of the corresponding boundary-value problem. Numerical results are presented for several coupling geometries, and misalignment and reflection-loss phenomena are also investigated for cases when the two fiber terminal planes are parallel to each other.

Coupling Between an Abruptly Terminated Optical Fiber and a Dielectric Planar Waveguide

The coupling between an optical fiber and a dielectric planar waveguide is analyzed when both guides are terminated abruptly and are facing each other. Mixed spectrum eigenwave representations of fields are employed inside the waveguides while Fourier integrals are utilized to describe the field in the space between the two guides. A coupled system of integral equations is derived by satisfying the boundary conditions on the terminal planes of both waveguides. A weak guidance approximation is assumed to facilitate the analysis. Numerical results are presented for several coupling geometries. Misalignment losses and coupling optimization phenomena are investigated.

Prediction of first molar occlusion

A longitudinal study of the deciduous terminal plane relationship and occlusion of the first permanent molars was carried out in fifty-four boys and sixty-four girls 4 1 2 to 14 years of age. Distributions of the deciduous terminal planes, initial occlusion of the first permanent molars, the degree of association between the two, and subsequent changes in the occlusion of the first permanent molars are described. A method of predicting the occlusion of the first molars is presented.

Coupling through a Small Aperture in a Waveguide

The problem of the waveguide coupled to an external load through a small aperture is expressed in terms of an integral equation. Solution of the latter yields an equivalent circuit for the load as seen from the waveguide. Holes in terminal planes and sidewall are considered separately. Some attention is also given to multiple-hole coupling.

The enzymatic degradation of cellulose from Valonia ventricosa

The degradation of microfibrils from Valonia ventricosa by cellulase has been studied. As a result of enzymatic attack the elementary fibrils making up the microfibrils tended to separate and the ends of the microfibrils became oblique or pointed. The terminal planes made angles of 60 ... 66°, 33°, or 20 ... 25° with the microfibril axis. These planes are assumed to correspond to the 41\(\bar 4\), 43\(\bar 4\) and 45\(\bar 4\) planes of the cellulose lattice and it is suggested that they are planes along which it is progressively more difficult for hydrolysis to proceed. On the basis of these considerations a suggestion has been proposed to explain the form of erosion cavities formed by soft-rot fungi described by previous workers in wood fibres and tracheids.

Reactive Optical Information Processing I: Theory of Information Recovery and Resonator Mode Structure

A method of processing optical information is described in which the use of absorptive spatial filters is replaced by suitable mirrors with spatially varying reflectances. When these mirrors are made the terminal planes of a laser resonator, the light which is lost in conventional spatial filtering systems, is stored in the laser cavity. It is shown that shallowly modulated phase objects may be imaged outside the resonator without any appreciable effect on the modes of the resonator.