An extended technicolour model for grand unification

An extended technicolour grand unification model based on the gauge groupE ₆×SU(7) extended technicolour is presented. The symmetry-breaking based on extended technicolour theory is discussed. It is shown that the existing phenomenology is well explained by the model. The strangeness changing neutral currents may not be a problem with this model.     

Heat of adsorption and density distribution in slit pores with defective walls: GCMC simulation studies and comparison with experimental data

The adsorption behavior (capacity, density distribution and packing density) and the isosteric heat versus loading in a slit pore whose walls contain defective graphene layers are investigated in this paper. The defective wall is characterized by the extent and size of the defect. Simulation results obtained with the Grand Canonical Monte Carlo method reveal complex patterns of isosteric heat, and this complex behavior is a result of the interplay between three factors: (i) the surface heterogeneity (solid-fluid interaction, sites with varying degree of affinity), (ii) fluid-fluid interaction and (iii) the overlapping of potentials exerted by the two defective walls. We illustrate this with argon adsorption in pores of various sizes, and results obtained from the simulation agree qualitatively with the experimental data at 77 K on Saran microporous S600H and micro-mesoporous S84 charcoals of Beebe et al. [R.A. Beebe, B. Millard, J. Cynarski, J. Am. Chem. Soc. 75 (1953) 839]. The S600H was found to contain pores predominantly in the neighborhood of 7 Å with 30% of defect and a defective size of 2.84 Å. This is consistent with the argument made by Beebe et al. that this sample is a microporous solid and most pores can accommodate only one layer. The other sample, S84, has larger pores than S600H, and it is found that it has a wider pore size distribution and the pore width is centered at about 12 Å.     

Vibration of strings with nonlinear supports

The dynamic string motion, which displacement is unilaterally constrained by the rigid termination condition of an arbitrary geometry has been simulated and analyzed. The treble strings of a grand piano usually terminate at a capo bar, which is situated above the strings. The apex of a V-shaped section of the capo bar defines the end of the speaking length of the strings. A numerical calculation based on the traveling wave solution is proposed for modeling the nonlinearity inducing interactions between the vibrating string and the contact condition at the point of string termination. It was shown that the lossless string vibrates in two distinct vibration regimes. In the beginning the string starts to interact in a nonlinear fashion with the rigid terminator, and the resulting string motion is aperiodic. Consequently, the spectrum of the string motion depends on the amplitude of string vibrations, and its spectral structure changes continuously with the passage of time. The duration of that vibration regime depends on the geometry of the terminator. After some time of aperiodic vibration, the string vibrations settle in a periodic regime where the resulting spectrum remains constant.     

On the limitation of the van der Waals-Platteeuw-based thermodynamic models for hydrates with multiple occupancy of cavities

Thermodynamic models based on the van der Waals–Platteeuw statistical theory (Adv. Chem. Phys. 2, 1 (1959)) can be very accurate in describing hydrate equilibrium conditions, even for some occasions when multiple cavity occupancy occurs. These are cases outside the range of assumptions used for the development of the original statistical theory. However, during multiple cavity occupancy such models can perform poorly when calculating the cavity occupancies. This paper reports novel Grand Canonical Monte Carlo molecular simulations for the case of pure structure II N₂ hydrate and compares the calculated cavity occupancies with experimental data and observe reasonable agreement. Also examined are the van der Waals–Platteeuw-based modifications that retained the single-occupancy assumption of the original theory and how they perform when predicting cavity occupancies and hydrate equilibrium pressures.     

On grand Lebesgue spaces on sets of infinite measure

We consider grand Lebesgue spaces on sets of infinite measure and study the dependence of these spaces on the choice of the so‐called. We also consider Mikhlin and Marcinkiewicz theorems on Fourier multipliers in the setting of grand spaces.     

单壁碳纳米管上毒性苯气体净化的分子模拟(英文)

采用巨正则系综蒙特卡罗(GCMC)方法研究了空气中微量苯组分在单臂碳纳米管(SWNTs)上的吸附净化.模拟表明,具有较大孔径的(20,20)纳米管比较适合吸附纯苯蒸汽,而对于移除空气中的毒性苯物质,苯的吸附选择性分别在(12,12)纳米管及4.0 MPa时和(18,18)纳米管及0.1 MPa时出现最小值和最大值.为了解释这一异常行为,我们进一步分析了N2-O2-C6H6混合物的局部密度分布、吸附分子构型和概率密度分布,发现(18,18)纳米管内外完全被苯分子占据,而对于(12,12)纳米管,由于存在更强的吸附质-吸附剂相互作用,空气分子更倾向于吸附在管与管之间的间隙.此外,吸附分子的空间有序参数表明大多数苯分子采取"平躺"在纳米管表面的定位,而线性的N2和O2分子则多数平行于孔轴方向.最后研究了温度和苯分子主体相浓度对分离效果的影响.我们发现较大孔中的选择性随着温度的增加比小孔下降更加明显.与此对比,主体相苯浓度对小孔中的选择性起到更加重要的作用.     

Atomistic simulation of sorption in model pores with reduced spatial periodicity

Grand Canonical Monte Carlo (GCMC) was used to study the sorption thermodynamics of carbon dioxide in model graphite slit-like pores and nanotubes by means of the Ewald technique, suitably adapted for the computation of long range (electrostatic) interactions of sorbates confined in pore systems exhibiting reduced periodicity in space. The computed thereby micropore size distributions extracted via mathematical elaboration of the simulation results with respect to real graphitic materials, reproduced successfully the experimentally measured isotherms of carbon dioxide in these materials at various temperatures. In the case of nanotubes, a direct Coulomb summation over a large number of periodic images proved to be a sufficient approximation leading to excellent agreement between the simulated and measured isotherms.     

Heterogeneity of activated carbons in adsorption of phenols from aqueous solutions—Comparison of experimental isotherm data and simulation predictions

Surface heterogeneity of activated carbons is usually characterized by adsorption energy distribution (AED) functions which can be estimated from the experimental adsorption isotherms by inverting integral equation. The experimental data of phenol adsorption from aqueous solution on activated carbons prepared from polyacrylonitrile (PAN) and polyethylene terephthalate (PET) have been taken from literature. AED functions for phenol adsorption, generated by application of regularization method have been verified. The Grand Canonical Monte Carlo (GCMC) simulation technique has been used as verification tool. The definitive stage of verification was comparison of experimental adsorption data and those obtained by utilization GCMC simulations. Necessary information for performing of simulations has been provided by parameters of AED functions calculated by regularization method.     

Food Web Implications of δ13C and δ15N Variability over 370 km of the Regulated Colorado River USA

Abstract

Dual stable isotope analysis in the regulated Colorado River through Grand Canyon National Park, USA, revealed a food web that varied spatially through this arid biome. Down-river enrichment of δ¹³C data was detected across three trophic levels resulting in shifted food webs. Humpack chub δ¹³C and δ¹⁵N values from muscle plugs and fin clips did not differ significantly. Humpback chub and rainbow trout trophic position is positively correlated with standard length indicating an increase in piscivory by larger fishes. Recovery of the aquatic community from impoundment by Glen Canyon Dam and collecting refinements for stable isotope analysis within large rivers are discussed.     

A note on dimension-5 operators in GUTs and their impact

Quantum gravity or string compactification can lead to effective dimension-5 operators in Grand Unified Theories which modify the gauge kinetic terms. We exhaustively discuss the group-theoretic nature of such operators for the popular SU(5), SO(10), and E(6) models. In particular, for SU(5) only a Higgs in the 200 representation can help bring the couplings to unification below the Planck scale and in consistency with proton decay limits while for a supersymmetric version 24, 75, or 200 representations are all acceptable. The results also have a direct application in non-universality of gaugino masses in a class of supersymmetric models where identical group-theoretic features obtain.