Centrifuge Testing to Evaluate and Mitigate Liquefaction-Induced Building Settlement Mechanisms

The effective application of liquefaction mitigation techniques requires an improved understanding of the development and consequences of liquefaction. Centrifuge experiments were performed to study the dominant mechanisms of seismically induced settlement of buildings with rigid mat foundations on thin deposits of liquefiable sand. The relative importance of key settlement mechanisms was evaluated by using mitigation techniques to minimize some of their respective contributions. The relative importance of settlement mechanisms was shown to depend on the characteristics of the earthquake motion, liquefiable soil, and building. The initiation, rate, and amount of liquefaction-induced building settlement depended greatly on the rate of ground shaking. Engineering design procedures should incorporate this important feature of earthquake shaking, which may be represented by the time rate of Arias intensity (i.e., the shaking intensity rate). In these experiments, installation of an independent, in-ground, perimetrical, stiff structural wall minimized deviatoric soil deformations under the building and reduced total building settlements by approximately 50%. Use of a flexible impermeable barrier that inhibited horizontal water flow without preventing shear deformation also reduced permanent building settlements but less significantly.     

Comparison between the effects of ultrasonic and thermal stimulation on release of internal hydrophobic dyes from Pluronic micelles

In this study, we propose a novel chemical reaction process using Pluronic micelles as reactant carriers in order to reduce complicated piping. A Pluronic micelle containing the hydrophobic dye NKX-1595 was prepared by a dialysis method, and the release of the internal dye from the micelle by external stimulation was investigated. In particular, we investigated the effects of the combination of ultrasonic frequency and type of Pluronic on degree of dye release (DDR). A low ultrasonic frequency is effective for the release of the internal dye from the micelle and ultrasonic physical effects are an important factor. Furthermore, under a weak ultrasonic physical effect at 490 kHz, the inhibition effect when the internal substance moves to the corona from the micelle core is also important for estimating the retention of the internal substance by the micelle. In addition, we investigated the effects of thermal stimulation on DDR at several environmental temperatures. The internal dye was gradually released from the micelle when the environmental temperature was greater than 303 K. Thus, appropriate design of external stimulation enables controlling not only the amount of effluence but also the release rate of the internal dye from the micelle.     

Binding properties of peptidic affinity ligands for plasmid DNA capture and detection

Peptides constructed from α‐helical subunits of the Lac repressor protein (LacI) were designed then tailored to achieve particular binding kinetics and dissociation constants for plasmid DNA purification and detection. Surface plasmon resonance was employed for quantification and characterization of the binding of double stranded Escherichia coli plasmid DNA (pUC19) via the lac operon (lacO) to “biomimics” of the DNA binding domain of LacI. Equilibrium dissociation constants (K_D), association (k_a), and dissociation rates (k_d) for the interaction between a suite of peptide sequences and pUC19 were determined. K_D values measured for the binding of pUC19 to the 47mer, 27mer, 16mer, and 14mer peptides were 8.8 ± 1.3 × 10^?10 M, 7.2 ± 0.6 × 10^?10 M, 4.5 ± 0.5 × 10^?8 M, and 6.2 ± 0.9 × 10^?6 M, respectively. These findings show that affinity peptides, composed of subunits from a naturally occurring operon–repressor interaction, can be designed to achieve binding characteristics suitable for affinity chromatography and biosensor devices. © 2008 American Institute of Chemical Engineers AIChE J, 2009     

Development of Numerical Methods for Simulation of Rapid Multi-Phase Interactions

Techniques commonly used in the calculations of multi-phase flow, such as local parameter averaging and continuity phase assumptions, may result in large calculational inaccuracies for phenomena with rapid phase change. For example, with vapor explosions, a large degree of pseudo-diffusion (i.e. numerical diffusion) of components in dispersed states or with discontinuous fronts may occur, and local information, useful for modeling and evaluation of the phenomena, may be lost. Pseudo-diffusion of the components which act as high-temperature heat sources affects component distributions throughout the entire system. Numerical divergence is also often caused by fluctuation of these high-temperature components. In this paper, two treatment methods are proposed to avoid these problems. One method is a dispersed component method, which was developed for dispersed components. This method includes special modeling for some local parameters and some treatments to suppress pseudo-diffusion and numerical divergence. The other is a multi-region scheme, where a calculation domain is divided into an expanding, multi-phase mixture region and the surrounding, single-phase continuum region. The front of the mixture region is tracked using an adaptable grid to accurately follow the interface. By this method, numerical diffusion at the interface can be avoided. The effectiveness of these treatments is demonstrated by numerical simulations.     

On the Predominant Electron-Donicity of Polar Solid Surfaces

The reasons for the predominant electron-donicity of almost all solid polar surfaces and its implications are discussed in this paper. By contact angle or interfacial tension measurements, the electron-accepting as well as the electron-donating properties of polar liquids can be ascertained, through the interplay between their energies of adhesion and cohesion. For the solid-liquid interface, direct interfacial tension measurements are not possible, but indirectly, solid/liquid interfacial tensions of polar systems can be obtained by contact angle measurement. However, as the energy of cohesion of a solid does not influence the contact angle formed by a liquid drop placed upon its surface, one can only measure the solid surface'ks residual polar property, manifested by the energy of adhesion between solid and liquid. This residual polar property is of necessity the dominant component; in most cases this turns out to be its electron donicity. When, by means of contact angle measurements with polar liquids, both electron-accepting and electron-donating potentials are found on a polar solid, it is most likely still partly covered with a polar liquid: usually water. The amount of residual water of hydration of a polar solid follows from its polar (Lewis acid-base) surface tension component (γ^AB). The degree of orientation of the residual water of hydration on a polar solid can be expressed by the ratio of the electron-donating to electron-accepting potentials (γ^?/γ^⊕), measured on the hydrated surface.     

Organic Sulfur Compounds from Dictyopteris spp. Deter Feeding by an Herbivorous Amphipod (Ampithoe longimana) but Not by an Herbivorous Sea Urchin (Arbacia punctulata)

Brown seaweeds in the genus Dictyopteris produce several C₁₁ sulfur metabolites that appear biosynthetically related to the C₁₁ compounds known to attract sperm to female gametes of many brown algae. All four of the C₁₁ sulfur compounds that we tested strongly deterred feeding by the amphipod Ampithoe longimana but had no effect on feeding by the sea urchin Arbacia punctulata, even when tested at concentrations that were two to eight times greater than those that deterred amphipods. In numerous previous investigations, a variety of seaweed compounds have been shown to deter feeding by large mobile herbivores such as fishes and urchins but to be relatively ineffective against mesograzers, such as the amphipod of our study. Our results for the C₁₁ sulfur compounds from Dictyopteris thus contrast sharply with patterns from previous studies and suggest that these metabolites may be defenses specifically targeted against small mesograzers such as amphipods. The occurrence of C₁₁ metabolites in brown algal eggs could allow these defenses to be especially important in defending gametes, zygotes, or young sporelings from herbivorous mesograzers.     

Essential Amino Acid Composition of Fleshy Fruits Versus Maintenance Requirements of Passerine Birds

Nutritional analyses were performed on 27 fruit species that are eaten by frugivorous birds in east Mediterranean habitats in Israel. The essential amino acid (EAA) profile [compared by principal component analysis (PCA)] of these fruits indicated two distinct groups of fruits. The main group consisted of 23 species that were similar in their relatively low total EAA quantities and unbalanced EAA profiles. On average, the EAAs phenylalanine and tyrosine were most concentrated and histidine least (tryptophan was not measured). Comparing the relative amounts of EAAs in fruits with required amounts for maintenance of granivorous passerine birds revealed that these fruits are deficient in all or most EAAs. The sulfur-containing amino acids (methionine and cystine) were most limiting relative to the required amount (41–61% below requirement), while four others (arginine, lysine, isoleucine, and leucine) were severely deficient (30–37% below requirement). These results complement reports suggesting that frugivorous birds have lower total protein demands than granivores. The second group of four fruit species had relatively high total EAA contents. Each of these fruits appeared to contain especially large quantities of some EAAs, but it was uncertain whether some high concentrations could have resulted from interactions in the pulp during preparation and chemical analysis.     

X-ray Photoelectron Study of Chemical Interactions at Ti/Polymer Interfaces

We have used X-ray photoelectron spectroscopy to study the chemical interactions at the interface formed during in situ deposition of Ti atoms on epoxy, triazine, and polystyrene surfaces. We find that for deposition on thick polymer films (1-2 mm) the primary component at the interface is TiO₂ with small amounts of titanium nitride and titanium carbide. The source of the oxygen in the TiO₂ is water or molecular oxygen dissolved in the polymer films. We also find that the Ti/triazine interface is more stable to heat treatment than the Ti/epoxy interface. This result is attributed to the higher glass transition temperature of triazine. For thin triazine films (～ 100Å) we observe that titanium carbide is the dominant product, with smaller amounts of oxide and nitride. Aging in air causes the carbide and nitride to convert to the more thermodynamically-stable oxide. Titanium carbide is also the primary initial species at the Ti/polystyrene interface.     

Antimicrobial peptides and induced membrane curvature: Geometry,coordination chemistry,and molecular engineering

Short cationic, amphipathic antimicrobial peptides are multi-functional molecules that have roles in host defense as direct microbicides and modulators of the immune response. While a general mechanism of microbicidal activity involves the selective disruption and permeabilization of cell membranes, the relationships between peptide sequence and membrane activity are still under investigation. Here, we review the diverse functions that AMPs collectively have in host defense, and show that these functions can be multiplexed with a membrane mechanism of activity derived from the generation of negative Gaussian membrane curvature. As AMPs preferentially generate this curvature in model bacterial cell membranes, the selective generation of negative Gaussian curvature provides AMPs with a broad mechanism to target microbial membranes. The amino acid constraints placed on AMPs by the geometric requirement to induce negative Gaussian curvature are consistent with known AMP sequences. This ‘saddle-splay curvature selection rule’ is not strongly restrictive so AMPs have significant compositional freedom to multiplex membrane activity with other useful functions. The observation that certain proteins involved in cellular processes which require negative Gaussian curvature contain domains with similar motifs as AMPs, suggests this rule may be applicable to other curvature-generating proteins. Since our saddle-splay curvature design rule is based upon both a mechanism of activity and the existing motifs of natural AMPs, we believe it will assist the development of synthetic antimicrobials.     

THERMODYNAMIC ANALYSIS OF DRYING FOODS

Thermodynamic functions computed for food systems showing hysteresis indicate considerable differences. There appears to exist no qualitative agreement between the values obtained. Large differences in values between the adsorption an desorp-tion branches of isotherms make the absolute magnitude of the entropy and enthalpy changes uncertain. The desorption iso-steric heat was found to decrease with temperature while the adsorption branch of the isotherm for a few foods were found to exhibit temperature reversal effect giving higher values at low temperatures. Such trend may indicate either transition in the form of binding energy or the effect of temperature on structural alterations. In designing drying equipment, the isosteric heat of desorption will provide “a worst case” analysis as the true isosteric heat will lie somewhere between the adsorption and desorption isosteric heat. Any overcalculation in designing equipment by using the desorption branch of hysteresis data can only be in favor of increased throughput capability. The use of isosteric heat in freeze drying and in air drying calculations were undertaken and found to rise at a faster rate than the energy expended in moisture removal.