Mathematical modelling of tongue deformation during swallow in patients with head and neck cancer

ABSTRACT

Cancer localized to the tongue is often characterized by increased stiffness in the affected region. This stiffness affects swallow in a manner that is difficult to quantify in patients. A biomechanical model was developed to simulate the spatio-temporal deformation of the tongue during the pharyngeal phase of swallow in patients with cancer of the tongue base. The model involves finite element analysis (FEA) of a three-dimensional (3D) model of the tongue reconstructed from magnetic resonance images (MRI). The tongue tissue is assumed to be hyper-elastic. In order to examine the effects of tissue change (increased stiffness) due to the presence of cancer localized to the tongue base, various sections of the 3D geometry are modified to exhibit different elastic properties. Three cases are considered, representing the normal tongue, a tongue with early-stage cancer, and tongue with late-stage cancer. Early- and late-stage cancers are differentiated by the degree of stiffness within the base of tongue tissue. Analysis of the model suggests that healthy tongue has a maximum deformation of 9.38 mm, whereas tongues having mild cancer and severe cancer have a maximum deformation of 8.65 and 6.17 mm, respectively. Biomechanical modelling is a useful tool to explain and estimate swallowing abnormalities associated with tongue cancer and post-treatment characteristics.     

What Do Middle and High School Students Know About the Particulate Nature of Matter After Instruction? Implications for Practice

This study explores middle and high school students' understanding of the particulate nature of matter after they were taught the concept. A total of 87 students (41 high school and 46 middle school) participated in the study. Findings suggest that students held misconceptions about the law of conservation of matter, chemical composition of matter in different phases of matter, the process of condensation, and behaviors of molecules at a microscopic level. The discussion focuses on the implications of these findings for enhancing science teachers' pedagogical content knowledge.     

Synergistic effects in hydrogen-helium bubbles

The detrimental effects of hydrogen and helium on structural materials undergoing irradiation are well documented, if not well understood. There is experimental evidence to suggest that a synergistic effect between the two elements exists, which results in increased damage when both are present. This situation is expected in the next generation of fusion and fission reactors, so a fundamental understanding of these synergistic interactions is needed to predict materials performance. We perform atomistic simulations of hydrogen and helium bubbles in body-centered cubic iron to determine the mechanism behind this effect. We first develop an interatomic potential suitable for describing the interactions between hydrogen and helium. Through analysis of the energetics and structure of these bubbles, we explain the observed synergy as a consequence of bubble growth through helium induced loop punching, aided by the presence of hydrogen, instead of as a direct interaction between hydrogen and helium. The hydrogen benefits from an increased area of free surface on which to bind.     

Pressure-induced transformations in crystalline and vitreous PbGeO3

Structural transitions in crystalline and vitreous PbGeO₃ were studied at pressures up to 20 GPa. Crystalline PbGeO₃ was observed to undergo a pressure-induced amorphization between 12–18 GPa. Vitreous PbGeO₃ was found to exhibit an amorphous-to-amorphous transition in a similar pressure range. The structural and thermal properties of the pressure-cycled PbGeO₃ materials were further studied with high-energy x-ray diffraction and differential scanning calorimetry. The properties were then compared to those of thermally quenched glass and ball-milled PbGeO₃ samples. The structure of pressure-amorphized PbGeO₃ was found to closely resemble that of ball-milled PbGeO₃. However, the thermal properties probed by differential scanning calorimetry exhibited significant differences to those of thermally quenched PbGeO₃ glass.     

Carboxylate Platform: The MixAlco Process Part 2: Process Economics

The MixAlco process employs a mixed culture of acid-forming microorganisms to convert biomass to carboxylate salts, which are concentrated via vapor-compression evaporation and subsequently chemically converted to other chemical and fuel products. To make alcohols, hydrogen is required, which can be supplied from a number of processes, including gasifying biomass, separation from fermentor gases, methane reforming, or electrolysis. Using zeolite catalysts, the alcohols can be oligomerized into hydrocarbons, such as gasoline. A 40-tonne/h plant processing municipal solid waste ($45/tonne tipping fee) and using hydrogen from a pipeline or refinery ($2.00/kg H₂) can sell alcohols for $1.13/gal or gasoline for $1.75/gal with a 15% return on investment ($0.61/gal of alcohol or $0.99/gal of gasoline for cash costs only). The capital cost is $1.95/annual gallon of mixed alcohols. An 800-tonne/h plant processing high-yield biomass ($60/tonne) and gasifying fermentation residues and waste biomass to hydrogen ($1.42/kg H₂) can sell alcohols for $1.33/gal or gasoline for $2.04/gal with a 15% return on investment ($1.08/gal of alcohol or $1.68/gal of gasoline for cash costs only). The capital cost for the alcohol and gasification plants at 800 tonnes/h is $1.45/annual gallon of mixed alcohols.     

Ion imaging studies of ClONO2 photodissociation: Primary branching ratios and secondary dissociation

The photodissociation dynamics of ClONO₂ at 235 nm has been reinvestigated using velocity map ion imaging. We report branching ratios for the Cl + NO₃ and ClO + NO₂ channels to be 0.49:0.51 with anisotropy parameters of β = 0.5 ± 0.1 and β = −0.1 ± 0.3 for the Cl and ClO production channels, respectively. Photodissociation at 248 nm and 262 nm results in similar branching ratios and dynamics as observed at 235 nm. Measured O(³P₂) images arising from ClONO₂ dissociation at 226 nm suggest that oxygen atoms result from the spontaneous dissociation of metastable NO₃. The quantum yield of O atoms arising from the spontaneous dissociation of NO₃ varies from 0.09 at 262 to 0.38 at 235 nm based on the derived internal energy distributions of the NO₃ fragments. We also describe a Monte-Carlo forward-convolution fitting of imaging data which permits detailed analysis of both spontaneous secondary dissociation and secondary photodissociation.     

Formyl Derivatives of Amino-Substituted Polyfluorotriphenyl-4,5-dihydro-1H-pyrazoles: Synthesis and Use as Donor Blocks of Nonlinear Optical Chromophores

Russian Journal of Organic Chemistry - A series of new formyl derivatives of polyfluorinated triphenyl-4,5-dihydro-1H-pyrazoles containing various amine residues in the fluorinated benzene ring...     

Symmetric Pairs of Unbounded Operators in Hilbert Space,and Their Applications in Mathematical Physics

In a previous paper, the authors introduced the idea of a symmetric pair of operators as a way to compute self-adjoint extensions of symmetric operators. In brief, a symmetric pair consists of two densely defined linear operators A and B, with \(A \subseteq B^{\star }\) and \(B \subseteq A^{\star }\). In this paper, we will show by example that symmetric pairs may be used to deduce closability of operators and sometimes even compute adjoints. In particular, we prove that the Malliavin derivative and Skorokhod integral of stochastic calculus are closable, and the closures are mutually adjoint. We also prove that the basic involutions of Tomita-Takesaki theory are closable and that their closures are mutually adjoint. Applications to functions of finite energy on infinite graphs are also discussed, wherein the Laplace operator and inclusion operator form a symmetric pair.     

Surfactant effects on the particle size of iron (III) oxides formed by sol-gel synthesis

In this work, we probed the effects of a common surfactant, sodium dodecylbenzene sulfonate (NaDDBS), on the particle size of iron (III) oxides formed via a modified sol-gel synthesis. The goal was to create tunable nanosized particles via a method that combines the efficiency and advantages of the sol-gel process, but inhibits the formation of a gel. Two different metal salt precursors were used, ferric nitrate nonahydrate, Fe(NO₃)₃ · 9H₂O, and ferric chlorate hexahydrate, FeCl₃ · 6H₂O. The particle size of the dried gel was 4.5 nm for Fe(NO₃)₃ · 9H₂O and 3.6 nm for FeCl₃ · 6H₂O. In the presence of the surfactant FeCl₃ · 6H₂O formed a gel and Fe(NO₃)₃ · 9H₂O was unable to gel, but the new particle sizes were 4.9 nm and 3.2 nm, respectively. The addition of the surfactant in the later stages of the process afforded the stabilization of independent nanoparticles of the same size as those obtained in the systems that gelled.