Latex Barrier Research Articles

Microfibrillated Cellulose Based Barrier Coatings for Abrasive Paper Products

Paper-based abrasive products are multilayer structures in which the first layer on the paper substrate is usually a latex barrier coating to prevent the migration of adhesive glue into the substrate. The high coat weight (10 g/m2) of latex barrier layers is a cause of environmental concerns. Hence, alternative materials that can provide the barrier function at lower coat weights are desired. In this work, microfibrillated cellulose (MFC) combined with poly(vinyl) alcohol (PVA) were explored as suitable alternatives to the current latex coatings. Barrier coating formulations containing PVA, MFC, and silica (SiO2) were developed and applied to a paper substrate using a rod coating method on a pilot scale. Coating quality and barrier performance were characterized using scanning electron microscope images, air permeance, surface roughness, water contact angle, KIT test, and oil Cobb measurements. The barrier coatings were also studied for adhesion to the subsequent coating layer. An optimal barrier function was achieved with the developed coatings at a low coat weight of ca. 3 g/m2. The adhesion of pure PVA and PVA-MFC barrier coatings to the subsequent coating layer was inadequate; however, silica addition was found to improve the adhesion.

Effects of drainage control on densification as a liquefaction mitigation technique

Ground densification is among the most popular techniques for liquefaction mitigation employed in practice. Yet, the effects of densification, especially in combination with strategies that enhance or inhibit drainage to or from the densified area, on the performance of the soil-foundation-structure system are not well understood. This paper describes dynamic centrifuge experiments to evaluate these effects, considering 3- and 9-story, moment-resisting frame structures with different embedment depths, founded on layered liquefiable soil deposits. The experiments compared structures mitigated with densification alone, and mitigated with a combination of densification and either prefabricated vertical drains (enhancing drainage) or a flexible impermeable latex barrier (inhibiting drainage) around the densified area. Ground densification tended to reduce the foundation settlement, although not to acceptable levels (based on limiting values typically considered in design and performance assessment), but amplified the drift and acceleration demands on the superstructure. The addition of a flexible impermeable barrier around the densified area did not have a notable influence on foundation settlement. However, it increased the excess pore pressures under the edges of the 3-story structure by inhibiting outward flow, amplifying its foundation rotation compared to the case with densification alone. In the case of the heavier and deeper, 9-story structure, adding a barrier around the densified zone restricted the locally inward flow from the adjacent loose soil. This helped reduce net pore pressures under the edges of the structure after strong shaking, foundation rotation, and seismic demand on the superstructure. Enhancing drainage around the densified zone, on the other hand, notably reduced permanent foundation settlement and rotation during all motions nearly to acceptable limits, but amplified accelerations, imposing additional seismic demands on the structure, which could lead to damage if not considered in design. These results demonstrate the importance of considering the structure's dynamic properties and force-deformation behavior, foundation and ground motion properties, and soil-structure interaction when planning the geometry of ground densification and drainage.

A Multichamber, Pressure-Based Test Method to Determine Wind Loads on Air-Permeable, Multilayer Cladding Systems

Current standardized testing on air-permeable multi-layer cladding is inaccurate as one of the primary parameters for setting the peak net wind loads across the cladding is the external pressure gradient which is removed from all standardized testing. After implementing a latex barrier system, and examining the control strategy for the Pressure Loading Actuators, a multi-chamber airbox system for testing air-permeable multi-layer cladding is developed and compared to a benchmark study performed by the Insurance Research Lab for Better Homes. The results indicate that using multi-chamber, pressure-based, testing to obtain wind loads for air-permeable, multi-layer wall systems with flexible cladding is sufficiently accurate. This method also shows that eliminating temporal variations from the external pressures for easier standardized testing would provide fairly accurate results.

Construction and Validation of a Self-Efficacy Scale for Latex Barrier Use.

Some studies have concluded there is a relationship between perceived self-efficacy and behaviors that prevent HIV transmission. This paper presents the construction and validation of the latex barrier use self-efficacy scale (LBSS), which 480 participants filled out. Exploratory factor analysis yielded two components: positive expectations of self-efficacy (ES-POS) and negative expectations of self-efficacy (ES-NEG), which together accounted for 65.59% of total variance. That structure was later verified through confirmatory factor analysis. Internal consistency was .80 for the total scale, and .78 for each of the two factors. Moreover, the instrument had adequate convergent validity and was positively related with condom use self-efficacy, attitudes toward condom and latex barrier use, and ability to refuse sex if the partner refuses to use preventive methods. In conclusion, this instrument is a useful measure of self-efficacy in latex barrier use.

Reluctant Objects

Pre-exposure prophylaxis (PrEP) has so far emerged as a reluctant object in much gay community discourse, primarily because of its association with the supposed excesses of unbridled sex. Its approval in the United States sparked bitter debate and a new round of sexual health moralism issuing mainly from gay community-based commentators, with initial uptake much slower than expected. This article considers early gay community responses to PrEP and connects them to the failure of existing HIV scientific practices to produce inhabitable sexual pedagogies. The controversy surrounding PrEP speaks to how condoms have been a way to manage communal fears about sexual excess in the era of AIDS, providing not only a latex barrier but also symbolic reassurance that gay sex might in some way be made “safe.” Another mode of attending to what is risky and exciting about sexual and scientific encounters might be possible in conceiving them as events.

Latex barrier thin film formation on porous substrates.

Here we present the formation of thin layers of barrier polymers onto mesoporous and macroporous substrates via dip coating of latex solutions. We investigated four commercially available latex solutions: polytetrafluoroethylene (PTFE), perfluoroalkoxy fluorothermoplastic (PFA), polyvinylidene chloride (PVDC), and polyolefin-based latex (Hypod). We examined the latex film formation on porous polymeric and ceramic substrates with a broad range of pore sizes from 10 to 200 nm. Our results show that both characteristics of the latex solution [glass transition temperature (Tg), particle size, and crystallinity] and the characteristics of the porous substrate (pore size and hydrophobicity) impact the film formation. We confirmed the defect-free, barrier nature of our latex thin films through scanning electron microscopy (SEM), atomic force microscopy (AFM), and hydraulically driven water permeation tests. Additionally, we found that latex concentration (not dipping time) is the most important parameter determining ultimate latex film thickness. We obtained defect-free films from PVDC and Hypod, which are "soft" polymers (Tg < room temperature), on mesoporous substrates under the conditions of slow evaporation rate of the solvent from these latex solutions. PTFE and PFA, which are "hard" polymers (Tg > room temperature), did not form continuous films on porous substrates.

Gedeon streaming suppression in a small scale thermoacoustic-Stirling engine-generator

Thermoacoustic-Stirling engines, or traveling wave engines, have been shown to convert heat to acoustic power very efficiently (over 30% first-law) in the laboratory. The laboratory prototypes are generally heated from the inside by an embedded electric heater, have a long, bulky resonator, and deliver their work to an acoustic load rather than as electricity, leaving significant challenges required for commercialization unaddressed. The authors are part of a team developing a compact acoustic Stirling engine that is externally heated and is coupled to a pair of linear alternators, dubbed the Thermoacoustic-Stirling Engine-Generator (TaSEG). An important part of this work has been developing a commercially viable means of suppressing Gedeon streaming, a steady flow that circulates in an acoustic engine's toroidal geometry. In the laboratory, this streaming is typically suppressed by either a latex barrier or a “jet pump,'' a special flow element with asymmetric flow resistance, adjusted from the outside of the engine via a rod that passes through the pressure vessel. This work describes the design and testing of a simple, compact, and inexpensive element with multiple jet-pump orifices (the “jet plate''), which can replace the laboratory versions in a commercial engine.

If the condom doesn't fit, you must resize it

When used properly, condoms provide excellent protection against sexually transmitted infections (STIs) and unintended pregnancies [ [1] Albert A.E. Warner D.L. Hatcher R.A. Trussell J. Bennett C. Condom use among female commercial sex workers in Nevada's legal brothels. Am J Public Health. 1995; 85: 1514-1520 Google Scholar ]. Non-use of condoms is the major risk factor for transmission of STIs, far overwhelming condom failure (slippage or breakage) or transmission of infectious agents through the latex barrier [ [2] Steiner M.J. Cates W.J.R. Warner L. The real problem with male condoms is nonuse. Sex Trans Dis. 1999; 26: 459-462 Google Scholar ]. To increase acceptance and usage, condoms are manufactured and marketed in a variety of shapes, textures, colors and flavors. However, there are significant limitations imposed upon the sizes of condoms made available, and several recent studies highlight public health problems with current condom sizes and the need to expand the range of sizes [ 3 Crosby R.A. Yarber W.L. Graham C.A. Sanders S.A. Does it fit okay? Problems with condom use as a function of self-reported poor fit. Sex Transm Infect. 2010; 86: 36-38 Google Scholar , 4 Reece M. Herbenick D. Dodge B. Penile dimensions and men���s perceptions of condom fit and feel. Sex Transm Infect. 2009; 85: 127-131 Google Scholar , 5 Reece M. Herbenick D. Sanders S.A. Monahan P. Temkit M. Yarber W.L. Breakage, slippage and acceptability outcomes of a condom fitted to penile dimensions. Sex Transm Infect. 2008; 84: 143-149 Google Scholar ].

Chemical Warfare

Chemical Warfare

Management of Latex Reactions in the Occupational Setting

1. The increased use of natural rubber latex barrier protection to prevent exposure to bloodborne pathogens has led to an increase in latex related health reactions, particularly associated with glove use. 2. The three types of reactions to latex in order of frequency include irritant contact dermatitis, allergic contact dermatitis, and immediate systemic/anaphylaxis reactions. 3. The management goal for all reactions is to avoid unnecessary restriction from the appropriate use of latex (gloves) which provides the best barrier protection, while protecting individual workers from exposure that results in sensitization or causes sensitized individuals to have serious reactions. 4. Choose non-latex gloves when barrier protection from bloodborne pathogens is not an issue. When selecting a latex glove, choose a glove that is low in proteins and powder free to control airborne latex exposure.

Transcending the Latex barrier: The therapeutics of comfort touch in patients with acquired immunodeficiency syndrome

Comfort touch has a positive impact on patient outcomes. When using Latex gloves, nurses often overlook the importance of skin-to-skin contact in effective comfort touch. Comfort touch is especially essential in vulnerable populations that are already experiencing several physical and emotional losses. Nurses' attitudes and fears may be a contributing factor to comfort touch not always being provided in caring for patients with acquired immunodeficiency syndrome (AIDS). The article discusses the therapeutics of comfort touch and explores the issues surrounding the absence of comfort touch in nursing interactions in patients with AIDS. Suggestions are made for nursing practice, education, and research.

Rapid inactivation of infectious pathogens by chlorhexidine-coated gloves.

Gloves containing chlorhexidine gluconate in an instant-release matrix on their inner surface (CHG gloves) were tested to determine their ability to rapidly inactivate infectious pathogens that may permeate or leak through the latex surface. CHG gloves were exposed for 1 to 10 minutes to blood or media containing infectious pathogens (e.g., bacteria, fungi, parasites, and viruses) as well as to lymphocytes and macrophages that are known to be the primary carriers of human immunodeficiency virus (HIV). Inactivation of pathogens was determined either by in vitro assay or in vivo infectivity. Stressed control and CHG glove fingers were submerged in a viral pool (retrovirus or bacteriophage) and after a set time, the glove interiors were checked for presence of permeated virions. CHG gloves rapidly inactivate all the pathogens tested including retrovirus and hepatitis B virus (90% to 100%). In the stressed glove fingers, live virus was detected in 26% of the control group but not in any of the CHG group. The use of CHG gloves may reduce the risk of exposure to infectious fluid-borne pathogens should the integrity of the latex barrier be compromised by overt failure or by permeation of viruses. Rapid destruction of lymphocytes and macrophages may facilitate inactivation of HIV associated with these cells. Tests have shown that CHG coating does not alter physical properties of the glove, and, furthermore, CHG gloves do not show potential for dermal irritation or sensitization.

Post-milking teat dip use in dairy herds with high or low somatic cell counts

Summary Milk samples for bacteriologic culture were submitted from 71 dairy herds, 24 with low somatic cell count (scc) and 47 with high scc and high prevalence of subclinical mastitis. At the time of sample submission to the Mastitis Diagnostic Laboratory of Pennsylvania State University, information regarding the herd mastitis control practices was collected. A combined program of post-milking teat dipping (pmtd) and antibiotic treatment of all cows at the start of the nonlactating period was practiced more frequently for herds with low scc, (P &lt; 0.001) than for herds with high scc. Among all herds for which pmtd was practiced, a higher proportion (P &lt; 0.001) of those for which chlorhexidine-based products were used had low scc than high scc. Conversely, a higher proportion of herds for which a dip with an acrylic latex barrier was used had high scc rather than low scc (P = 0.002). For herds with high prevalence of sub- clinical mastitis, and despite a program of pmtd and treatment of all cows at the start of the nonlactating period, a change to a different germicidal teat dip product may be indicated to help reduce prevalence of infection.

Use of Latex Teat Dip with Germicide During the Prepartum Period

The efficacy of an acrylic latex barrier teat dip with germicide on new infections at parturition was tested on 113 cows and heifers during the prepartum period. A split udder design was used in which right quarters were undipped controls and left quarters were dipped with latex dip once daily for approximately 14 d prior to parturition. Distal streak canal swabs were taken from all quarters prior to the beginning of dipping, and all cows were quarter sampled in duplicate at drying off, parturition, and the first 5 consecutive wk of lactation. All quarters received antibiotic therapy at drying off. Excluding infections detected by distal streak canal swabs, the number of new infections at parturition in control and dipped quarters was 32 and 36. New infections at parturition in control and dipped quarters were Staphylococcus aureus, 2 and 2; coagulase-negative staphylococci, 8 and 9; stretptococci, 10 and 12; coliforms, 8 and 8; and others, 4 and 5. Differences were not significant. These results suggest no benefit to use of prepartum latex teat dip with germicide on new infections at parturition.

Bioavailability in rabbits of formaldehyde from durable-press textiles.

Carbon-14-labeled formaldehyde was used per se, or was used in the synthesis of dimethyloldihydroxyethyleneurea (DMDHEU), which was incorporated into cotton or cotton/polyester blend fabric. Patches of the fabric containing known quantities of radioactive DMDHEU were applied to the backs of New Zealand White rabbits for periods up to 48 h. The rabbits were placed in specially constructed metabolism chambers designed to prevent either inhalation of volatile material emanating from the fabric or interference of any volatile material from the fabric with trapping of expired carbon dioxide. The results of the studies indicate that aqueous formaldehyde covered with a latex barrier is absorbed and retained in the layers of skin in direct contact with the formaldehyde. Approximately 65% of a dose of [14C] formaldehyde was recovered in skin 4 h after application. Skin samples from the backs of rabbits to which durable-press fabric prepared from radiolabeled DMDHEU had been applied were found to have 0.09-2.61% of the total 14C contained in the cloth patches. The levels of radioactivity recovered from the skin varied with degree of occlusion of the cloth, presence or absence of perspiration, type of synthesis used for the preparation of DMDHEU, and whether cotton or cotton/polyester blend fabric was used. Other tissues and organs had only low levels of radioactivity. Injected [14C] formaldehyde was rapidly expired as 14CO2 (28.6% of the dose within 4 h; 37.0% within 48 h). Metabolism and distribution of formaldehyde was found to be dependent on route of administration: i.e., topical application resulted in high skin levels, whereas intravenous injection led to rapid pulmonary and renal excretion and retention of radioactivity in liver, kidney, and blood.