Slow slumping of a very viscous liquid bridge

A layer of very viscous liquid (e.g. tar, molten glass) spans a chasm between two vertical walls. The slow fall or slump of this initially-rectangular liquid bridge is analysed. A semi-analytical solution is obtained for the initial motion, for arbitrary thickness/width ratios. The formal limits of large and small thickness/width ratios are also investigated. For example, the centre section of a thin bridge of liquid of density and viscosity µ, with width 2w and thickness 2h2w falls under gravity g at an initial velocity gw⁴/(32h²). A finite element technique is then employed to determine the slumping motion at later times, confirming in passing the semi-analytical prediction of the initial slumping velocity.     

Replacement of Fhit in cancer cells suppresses tumorigenicity

The candidate tumor suppressor gene, FHIT, encompasses the common human chromosomal fragile site at 3p14.2, the hereditary renal cancer translocation breakpoint, and cancer cell homozygous deletions. Fhit hydrolyzes dinucleotide 5',5"'-P1,P3-triphosphate in vitro and mutation of a central histidine abolishes hydrolase activity. To study Fhit function, wild-type and mutant FHIT genes were transfected into cancer cell lines that lacked endogenous Fhit. No consistent effect of exogenous Fhit on growth in culture was observed, but Fhit and hydrolase "dead" Fhit mutant proteins suppressed tumorigenicity in nude mice, indicating that 5',5"'-P1, P3-triphosphate hydrolysis is not required for tumor suppression.     

Archival Appraisal and the Digital Record: Applying Past Tradition for Future Practice

The digital revolution has changed the daily work of archivists. As a result, archivists have refined their analog practices and initiated new ones to accommodate the unique information creation and access needs of users. While limitless storage and technological obsolescence may be surmountable challenges, appraisal continues to be a necessary component of this preservation enterprise. Macro-appraisal—a top-down functional assessment of an organization’s high-level decision making that defines the enduring value of specific bodies of documentary evidence of these creative or administrative processes—is used to facilitate the management of diverse bodies of born-digital records in archives and special collections.     

Unperturbed dimensions of polyacrylamide in salt-water-methanol mixtures

The unperturbed dimensions of polyacrylamide are determined by light scattering measurements, in methanol-water solutions and correspond to: R_G?=0.39±0.01 M^0.5. This result is compared to that obtained from viscosity measurements in aqueous solution, through Stockmayer-Fixmann method. A possible explanation based upon the recent blob theory of polymers is proposed for the observed differences.     

Development of a safety awareness group intervention for women with diverse disabilities: A pilot study.

Objective: Describe the development and preliminary evaluation of a safety awareness program for women with disabilities. Design: Baseline and postintervention questionnaires administered to a sample of women who completed a safety awareness program. Participants: Seven women with diverse disabilities. Intervention: Eight interactive sessions designed to increase protective factors. Setting: Community site for persons with disabilities. Main Outcomes: Safety self-efficacy, safety skills, social support/isolation, and safety promoting behaviors. Results: Significant increases from baseline to postintervention were found on measures of self-efficacy and safety skills. Although not statistically significant, improvements were also found in safety promoting behavior. Conclusion: Despite the small sample, findings suggest that participation in a safety awareness program may improve protective factors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An Electronic UWB Continuously Tunable Time-Delay System With Nanosecond Delays

We propose and demonstrate an electronic system achieving continuously tunable time-delays with nanosecond-scale delay excursions for ultra-wideband signals. Our demonstration system yields an adjustable delay of up to 1.6 ns for input signals spanning 3 to 7 GHz. The key component is a dispersive length of microstrip line created by etching a chirped electromagnetic bandgap structure in the conducting strip.     

Development of a Synthetic Skin Simulant Platform for the Investigation of Dermal Blistering Mechanics

Excessive frictional loading to the skin often results in the formation of blisters, due to the transmission of shear loading to the interfaces between dermal cell strata. The consequences of blistering range from mild discomfort to serious infection. In some patients, such as those disposed to epidermolysis bullosa or neuropathic diabetes, blisters can severely degrade life quality. Investigation of environmental and application parameters that affect blister formation has occurred primarily as a qualitative, observational pursuit on human subjects, which has often led to confounding of data and lack of repeatability. The authors have developed a Synthetic Skin Simulant Platform (3SP) that reproduces the mechanical behavior of human skin when exposed to tribological loading. The platform is an assembled construct of bonded elastomeric layers that act as surrogates for the epidermis, basement membrane, dermis, and subdermal structure. Epidermal (top layer) materials are typically silicone or polyurethane films with a friction coefficient akin to human skin, while sublayers display mechanical properties similar to their anatomical analogs. Blistering is evident optically by examining the separation voids formed after applying shear loads to the epidermal layer. The 3SP has been used in a two-axis pin-on-flat tribometer with a stainless steel indenter to study the normal load and friction coefficients encountered at the onset of frictional blistering. The 3SP allows for modulation of friction coefficient, interfacial adhesion strength, and subdermal stiffness for investigation of blistering damage to various anatomical sites. Experimental results have been compared to human test data and have shown that the 3SP provides the potential to make significant advances with respect to skin tribology research.     

Chemorheology of carboxyl terminated polybutadienes with different antioxidants

An investigation of chemorheological properties has been made on two types of carboxyl terminated polybutadienes (CTPB), HC-434, and Butarez CTL. Curing of CTPB has been done with an imine, MAPO. Films have been cast and cured and then cut into strips. Some of these strips have been extracted with acetone and then two types of antioxidants were added, phenyl-beta-naphthylamine (PBN) and methylenebis-(4-methyl-6-tert-butyl)-phenol (BKF). Continuous stress relaxation measurements and intermittent measurements of stress have been made at a temperature of 110°C. The results show that Butarez CTL seems to have better ageing properties than HC-434 even when the same type of antioxidant has been added to the polymers. The most effective antioxidant of the two tested is BKF, which balances scission reactions and crosslinking reactions in a better way than PBN.