Cover Strip Research Articles

Resistance of Commercial Bed Covers against Faecal Pellets of House Dust Mites: Behaviour of Seams and Zippers

This study evaluated the allergen impermeability against airborne allergens of dust mite droppings through all parts of commercial bed covers, including surface seams and zippers. Specimens were taken from places with and without seams and zipper. A novel penetration cell was developed to expose the specimens to an inoculum of purified mite droppings that was assessed for its allergen content Der p1 prior to the penetration tests. Using covers of different construction and material, the penetration level increased significantly in the presence of seams and zippers and could reach up to 6% depending on the seam’s/zipper’s characteristics and quality. Therefore, zippers and seams have to be considered as access points for the penetration of mite droppings. As for the penetration of airborne mite particles through the zipper, the penetration level was greatly attenuated by the presence of a cover strip. Depending on the respective quality and the construction type, the mite allergen Der p1 penetrated most likely through the zipper and seams of the specimens, already after a single laundry cycle. Hence, laundry may compromise the barrier performance and proves to be an important quality feature. In all samples, the textile surface showed sufficient allergen impermeability. Our conclusions provide recommendations to both manufacturers and users.

Resistance of Type 5 chemical protective clothing against nanometric airborne particles: Behavior of seams and zipper

ABSTRACTIn the field of dermal protection, the use of chemical protective clothing (CPC) (including coveralls) are considered as the last barrier against airborne engineered nanomaterials (ENM). In the majority of cases, Type 5 CPC, used against solid particles (ISO 13982-1), perform well against ENM. But in a recent study, a penetration level (PL) of up to 8.5% of polydisperse sodium chloride airborne nanoparticles has been measured. Moreover, in all the previous studies, tests were performed on a sample of protective clothing material without seams or zippers. Thus, the potential for permeation through a zipper or seams has not yet been determined, even though these areas would be privileged entry points for airborne ENM.This work was designed to evaluate the PL of airborne ENM through coveralls and specifically the PL through the seams on different parts of the CPC and the zipper.Eight current models of CPC (Type 5) were selected. The samples were taken from places with and without seams and with a zipper. In some cases, a cover strip can be added to the zipper to enhance its sealing. Polydisperse nanoparticles were generated by nebulization of a sodium chloride solution. A penetration cell was developed to expose the sample to airborne nanometric particles. The NaCl particle concentration in number was measured with an ultrafine particle counter and the PL was defined as the downstream concentration divided by the upstream concentration.The results obtained show that the PL increased significantly in the presence of seams and could reach up to 90% depending on the seam's design. Moreover, this study classifies the different types of seams by their resistance against airborne ENM. As for the penetration of airborne NaCl particles through the zipper, the PL was greatly attenuated by the presence of a cover strip, but only for certain models of coveralls. Finally, the values of the pressure drop were directly linked to the type of seam. All of these conclusions provide recommendations to both manufacturers and users.

Evaluation of add-on methods for bis-acryl composite resin interim restorations

Statement of problemInterim restoration materials should allow easy add-on for repair and modification; however, bis-acryl composite resins are reported to have unfavorable performance in this regard. PurposeThe purpose of this study was to find a suitably effective add-on method for bis-acryl interim composite resins. Material and methodsA control group with a new type of bis-acryl material added to the same bis-acryl disks (n=10) was compared to 9 experimental groups (n=20) divided on the basis of their surface conditions: oxygen-inhibited unpolymerized layer preserved; ground; ground and treated with a light-polymerizing bonding agent, with or without a synthetic polyester film (Mylar) cover strip to control oxygen-inhibited unpolymerized layer; with bis-acryl, bis-GMA flowable composite, or poly-methyl methacrylate (PMMA) resins as add-on materials. PMMA specimens added with PMMA resin served as a parallel control group (n=20). Half of the experimental and PMMA control specimens were thermocycled 2000 times at 5 ±2°C and 55 ±2°C. Shear bond strength (SBS) results were then compared using 2-way and 1-way ANOVA and a Tukey honest significant difference (HSD) test (α=.05). ResultsNo significant differences were found between SBS of PMMA and those of bis-acryl controls (21.74 and 17.47 MPa, respectively), with all of the experimental groups exhibiting values comparable to the controls and unaffected by thermocycling. The highest SBS (35.58 MPa) was obtained with the bis-GMA-added group, in which the surface was ground and treated with a bonding agent (P<.05). With the bis-acryl resin and bonding agent group, additional light polymerizing significantly increased the SBS from 15.58 to 23.80 MPa (P<.05). ConclusionsBis-acryl-based interim material has favorable add-on properties, which are improved by additional surface treatment and use of a flowable composite resin.

Structural Behavior of FRP Tunnel Lining

This paper represented the numerical analysis of the tunnel lining which was used for maintaining the old tunnel. The tunnel lining was made from FRP corrugated sheet that supported the lining concrete in the tunnel and flowed the water or / and the moisture swept on the tunnel surface. The FRP sheet was supported by the anchor bolts. In numerical analysis, the finite element degenerate shell was adopted to represent the FRP behavior. Firstly, the proposed FRP sheet was adopted and the distribute load equivalent to the concrete peeled from the tunnel lining was applied and the stresses of the FRP sheet, the tensile force of bolts and the deflection of FRP sheet were investigated. Then, secondary, the FRP corrugated sheet with longitudinal cover strip was investigated. From the numerical analysis, the effectiveness of the FRP corrugated sheet was confirmed.

First quantification of alpha‐Gal epitope in current glutaraldehyde‐fixed heart valve bioprostheses

Glutaraldehyde fixation does not guarantee complete tissue biocompatibility in current clinical bioprosthetic heart valves (BHVs). Particularly, circulating anti-αGal human antibodies increase significantly from just 10 days after a BHV implantation. The inactivation of such epitope should be mandatory to meet the requirements for a perspectively safe clinical application; nevertheless, its quantitative assessment in commercially available BHVs has never been carried out. In this investigation, seven different models of BHVs were tested. The number of epitopes was determined with reference to a standard αGal source by an ELISA test. The presence of xenoantigen was subsequently confirmed by immunofluorescence analysis. Porcine tissue, knockout for the αGal epitopes, was used as negative control. Epic™ valve was the only model among those tested, in which the αGal antigen appeared to be completely shielded. Composite Trifecta™ valve exhibited conflicting results: cusps of bovine pericardial tissue were devoid of reactive αGal epitopes, while the stent cover strip of porcine pericardium still maintained 30% of active antigens originally present in native tissue. All other tested BHVs express an αGal amount not significantly different from that exhibited by porcine Mosaic(®) valve (5.2 ± 0.6 × 10(10) each 10 mg of tissue). For the first time, the quantitative evaluation of the αGal epitope in heart valve bioprostheses, already in clinical practice for about 40 yrs, was finally determined. Such quantification might provide indications of biocompatibility relevant for the selection of bioprosthetic devices and an increase in the confidence of the patient. It might become a major quality control tool in the production and redirection of future investigation in the quest for αGal-free long-lasting substitutes.

Time of Interseeding of Lana Vetch and Winter Rye Cover Strips Determines Competitive Impact on Pumpkins Grown Using Organic Practices

Growing a main vegetable crop for harvest and a cover crop for residue return to soil in the same growing season is a promising strategy to sustain soil quality in vegetable rotations. Our research evaluated cover crop strips interseeded between pumpkins (Cucurbita pepo L.) as a way to implement such a strategy. Cover crop types were lana vetch (Vicia villosa ssp. dasycarpa Ten.) and a lana vetch–winter rye (Secale cereale L.) mix, interseeded before, at the same time, or after pumpkins. The competitive impact of different cover crop strips was assessed using pumpkin yield, cover strip biomass, crop nitrogen status, soil nitrate status, and soil water potential. Cover strips were also assessed for competitiveness with native weeds. Seeding date affected the competitiveness of cover strips with pumpkins, while cover type did not. Cover crops seeded before pumpkins or at the same time reduced pumpkin yield in proportion to biomass produced by the cover strips early in pumpkin growth. Cover strips seeded after pumpkins did not reduce yield. Tilling in a before-seeded cover strip at 30 days after pumpkin seeding gave higher pumpkin yield than before-seeded cover strips that were not tilled. At three of four sites, after-seeded cover strips had the lowest percent weed biomass in strips, and at two sites with moderate weed pressure vetch–rye strips were more effective than vetch alone in suppressing weeds. Cover strips seeded before or at the same time as pumpkins reduced pumpkin yield by taking up resources that were otherwise available to pumpkins. At a high-rainfall site, competition for soil nitrate by cover crop strips was the dominant factor in reducing pumpkin yield. At a low-rainfall site, the dominant factor was competition for water. Because of effective weed suppression and lack of pumpkin yield reduction, interseeding vetch–rye strips after pumpkins was a promising practice, as was tilling in preexistent cover strips at an interval &lt;30 days after pumpkin seeding. Good previous weed management and rye–vetch mixes at high seeding rates are necessary to allow interseeded cover strips to outcompete weeds.

Impact of habitat management on grey partridge populations: assessing wildlife cover using a multisite BACI experiment

Summary The grey partridge is a species of conservation concern, in common with many farmland birds. Its widespread decline in western Europe has been attributed to agricultural intensification. Attempts to restore populations have concentrated upon habitat management. In France, a mosaic of strips planted with maize‐ or kale‐based mixtures is widely used to benefit the grey partridge on intensively cultivated farmlands. The rationale for planting these summer‐to‐winter cover strips is to increase the overwinter survival rate and hence breeding density. Although this policy is costly to apply, there is little information on its effectiveness. We tested effectiveness of this management scheme as a practical way of improving or restoring partridge populations. We present data from a 6‐year before–after control–impact (BACI) experiment replicated across four study sites. We monitored partridge populations to estimate breeding density, reproductive success and overwinter mortality. During the course of the study, no partridge population increase occurred on managed areas compared with control areas. Wildlife cover strips did not improve reproductive success but were associated with higher overwinter ‘apparent mortality’ rates. Some field data suggested that there was a predation risk at cover strip–field edges. Cover strips may concentrate a number of species within small isolated areas and may act, under some circumstances, as an ecological trap for prey species such as the grey partridge. Due to these complex and unforeseen interactions, this habitat management measure proved unsuitable for partridge restoration. Synthesis and applications. This study has demonstrated the necessity of field experiments at a farm‐scale to test the effectiveness of habitat management schemes. A priori assumptions based on smaller scale studies, even if they are supported by some field evidence, can be misleading because they fail to capture the emergent properties of larger scale systems. This study is a specific illustration of how the BACI approach is a powerful tool for addressing wildlife management problems at large spatial scales.

Comparison of Filament-Core Spun Yarns Produced by New and Conventional Methods

In recent years, we have been reporting our research on composite yarns of mostly cotton content produced on a modified ring spinning system. Recently, we reported an improved method of producing an all staple-core spun yarn, and we have applied the same method to filament-core spinning, obtaining a yarn of greatly improved quality. The new filament-core yarn has almost total core coverage, does not strip, and is about 10% stronger (probably due to its improved yarn structure) than a conventional filament-core yarn. This paper briefly describes the new and conventional core spinning methods and evaluates nylon filament-core/cotton-wrap yarns produced with them. There is also a comparison of the cover factor, strip resistance, and microscopic cross sections of a few other core yarns (with Kevlar, fiberglass, and polyester cores). A significant improvement in the cover factor of the new yarn suggests that it may be very useful for sewing threads; ropes; twines; cables; special military, industrial, and surgical fabrics; and other textiles in which the high strength, durability, and a 100% cotton surface (for ease of finishing or coating) are important.