Critical adsorption on curved objects

A systematic fieldtheoretic description of critical adsorption on curved objects such as spherical or rodlike colloidal particles immersed in a fluid near criticality is presented. The temperature dependence of the corresponding order parameter profiles and of the excess adsorption are calculated explicitly. Critical adsorption on elongated rods is substantially more pronounced than on spherical particles. It turns out that, within the context of critical phenomena in confined geometries, critical adsorption on a microscopically thin `needle' represents a distinct universality class of its own. Under favorable conditions the results are relevant for the flocculation of colloidal particles.Comment: 52 pages, 10 figure

Proteoglycan Breakdown of Meniscal Explants Following Dynamic Compression Using a Novel Bioreactor

Motivated by our interest in examining meniscal mechanotransduction processes, we report on the validation of a new tissue engineering bioreactor. This paper describes the design and performance capabilities of a tissue engineering bioreactor for cyclic compression of meniscal explants. We showed that the system maintains a tissue culture environment equivalent to that provided by conventional incubators and that its strain output was uniform and reproducible. The system incorporates a linear actuator and load cell aligned together in a frame that is contained within an incubator and allows for large loads and small displacements. A plunger with six Teflon-filled Delrin compression rods is attached to the actuator compressing up to six tissue explants simultaneously and with even pressure. The bioreactor system was used to study proteoglycan (PG) breakdown in porcine meniscal explants following various input loading tests (0–20% strain, 0–0.1 MPa). The greatest PG breakdown was measured following 20% compressive strain. These strain and stress levels have been shown to correspond to partial meniscectomy. Thus, these data suggest that removing 30–60% of meniscal tissue will result in the breakdown of meniscal tissue proteoglycans

Basal-plane Incommensurate Phases in HCP Structures

An Ising model with competing interaction is used to study the appearance of incommensurate phases in the basal plane of an hexagonal closed-packed structure. The calculated mean-field phase diagram reveals various 1q-incommensurate and lock-in phases. The results are applied to explain the basal-plane incommensurate phase in some compounds of the A'A"BX_4 family, like K_2MoO_4, K_2WO_4, Rb_2WO4 and to describe the sequence of high-temperature phase transitions in other compounds of this family.Comment: 8 pages, RevTeX + 4 ps figure

The specific heat of thin films near the lambda-transition: A Monte Carlo study of an improved three-dimensional lattice model

We study the finite size scaling behaviour of the specific heat of thin films in the neighbourhood of the lambda-transition. To this end we have simulated the improved two-component phi^4 model on the simple cubic lattice. We employ free boundary conditions in the short direction to mimic the vanishing order parameter at the boundaries of a 4He film. Most of our simulations are performed for the thicknesses L_0=8,16 and 32 of the film. It turns out that one has to take into account corrections proportional 1/L_0 to obtain a good collapse of the finite size scaling functions obtained from different L_0. Our results are compared with those obtained from experiments on thin films of 4He near the lambda-transition, from field theory and from previous Monte Carlo simulations.Comment: 46 pages, 15 figure

Molecular dosimetry of DNA and hemoglobin adducts in mice and rats exposed to ethylene oxide.

Experiments involving ethylene oxide (ETO) have been used to support the concept of using adducts in hemoglobin as a surrogate for DNA adducts in target tissues. The relationship between repeated exposures to ETO and the formation of N-(2-hydroxyethyl)valine (HEtVal) in hemoglobin and 7-(2-hydroxyethyl)guanine (7-HEG) in DNA was investigated in male rats and mice exposed by inhalation to 0, 3, 10, 33, or 100 ppm ETO for 6 hr/day for 4 weeks, or exposed to 100 ppm (mice) or 300 ppm (rats) for 1, 3, 5, 10, or 20 days (5 days/week). HEtVal was determined by Edman degradation, and 7-HEG was quantitated by HPLC separation and fluorescence detection. HEtVal formation was linear between 3 and 33 ppm ETO and increased in slope above 33 ppm. The dose-response curves for 7-HEG in rat tissues were linear between 10 and 100 ppm ETO and increased in slope above 100 ppm. In contrast, only exposures to 100 ppm ETO resulted in significant accumulation of 7-HEG in mice. Hemoglobin adducts were lost at a greater rate than predicted by normal erythrocyte life span. The loss of 7-HEG from DNA was both species and tissue dependent, with the adduct half-lives ranging from 2.9 to 5.8 days in rat tissues (brain, kidney, liver, lung, spleen, testis) and 1.0 to 2.3 days in all mouse tissues except kidney (t1/2 = 6.9 days). The concentrations of HEtVal were similar in concurrently exposed rats and mice, whereas DNA from rats had at least 2-fold greater concentrations of 7-HEG than DNA from mice.(ABSTRACT TRUNCATED AT 250 WORDS

Subunit Vaccine Targeting Phosphate ABC Transporter ATP-Binding Protein, PstB, Provides Cross-Protection against Streptococcus suis Serotype 2, 7, and 9 in Mice.

Streptococcus suis is a significant pathogen in pigs and a newly emerging zoonotic agent in humans. The presence of multiple serotypes and strains with diversified sequence types in pig herds highlights the need for the identification of broadly cross-reactive universal vaccine antigen targets, capable of providing cross-protection against S. suis infection. Subunit vaccines based on the conserved proteins shared between different S. suis serotypes are potential candidates for such a universally protective vaccine. In the present study, phosphate ABC transporter ATP-binding protein PstB (PstB), an immunogenic protein of the S. suis bacterium, was expressed and purified, and then subjected to cross-protection evaluation in mice. The PstB protein showed nearly 100% amino acid similarity across a panel of 31 S. suis isolates representing different serotypes, which were collected from different countries. A recombinant PstB (rPstB) protein (S. suis serotype 2) was recognized by rabbit sera specific to this serotype, and induced high levels of IFN-γ and IL-4 in mice immunized with the recombinant protein. These cytokines are considered important for protection against S. suis infection. Immunization of mice with rPstB resulted in an 87.5% protection against challenge with S. suis serotype 2 and 9 strains, suggesting a high level of cross-protection for S. suis serotypes 2 and 9. A lower protection rate (62.5%) was observed in mice challenged with the S. suis serotype 7 strain. These data demonstrate that PstB is a promising target antigen for development as a component of a universal subunit vaccine against multiple S. suis serotypes