Polymeric Plug Research Articles

Field longevity of methyl eugenol and cue-lure plugs and associated insecticidal strips: captures of Bactrocera dorsalis and Zeugodacus cucurbitae (Diptera: Tephritidae) in Hawaii.

Certain species of true fruit flies (Diptera: Tephritidae) cause tremendous damage to commercially important fruits and vegetables, and many countries operate continuous trapping programs which rely on male-specific lures such as trimedlure (TML), methyl eugenol (ME), and cue-lure (CL). Traditionally, these attractants have been applied as liquids to cotton wicks inside traps, although this results in high evaporative loss of the lure. Slow-release, polymeric plugs have been widely adopted for TML, but such devices are not widely used for ME or CL. Recent data, however, suggest that ME and CL plugs may be attractive for as long as 12 wk in the field. The present study investigates whether ME and CL plugs weathered for 18 or 24 wk are effective in capturing males of Bactrocera dorsalis (Hendel) and Zeugodacus cucurbitae (Coquillett), respectively. For B. dorsalis, 6 g ME plugs were as effective as the control treatment (fresh liquid on a wick) after 12 wk of weathering but not after 18 or 24 wk. For Z. cucurbitae, 3 g CL plugs were as effective as the control treatment (fresh CL plugs) after 12 and 18 wk of weathering but not after 24 wk. The residual content and release rate of the 2 lures were also measured over time, but, with the exception of the residual content of ME, we did not find a direct correlation between these parameters and numbers of flies captured.

Relationship between Field Captures of Mediterranean Fruit Flies (Diptera: Tephritidae) and the Residual Amount and Release Rate of Trimedlure from Polymeric Plugs

Relationship between Field Captures of Mediterranean Fruit Flies (Diptera: Tephritidae) and the Residual Amount and Release Rate of Trimedlure from Polymeric Plugs

Field Longevity and Attractiveness of Trimedlure Plugs to MaleCeratitis capitatain Florida and Hawaii

Detection of the Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), relies heavily on traps baited with trimedlure, a male-specific attractant. Originally used as a liquid, trimedlure is now dispensed from solid polymeric plugs that reduce volatilization and increase the effective field longevity of the lure. Many of the previous bioassays that measured trimedlure longevity were conducted in Hawaii and adopted a simple “50% rule” for trimedlure plug replacement, i.e., trimedlure plugs should be changed out when their attractiveness (trap captures of male medflies) drops below 50% that observed for fresh trimedlure liquid. The goal of the present study was to assess the field effectiveness of trimedlure plugs in Florida and apply standard statistical analyses to the trapping data. Sterile marked male medflies were released in a citrus orchard with traps containing 3 trimedlure treatments: 2 mL fresh liquid, 2 g fresh plugs, or 2 g plugs aged for intervals of 1, 2, 4, 6, 8, 10, or 12 wk. A single release of approximately 40,000 males was performed for each of the weathering intervals. Weathered trimedlure plugs were as effective as fresh lures when aged 6 wk or less, but catch was significantly reduced for plugs weathered 8 or more wk. At 8 to 12 wk, remaining trimedlure content per plug was ≤ 0.4 g. Ancillary field trials in Hawaii compared male medfly captures in traps baited with fresh 2 or 3 g trimedlure plugs, or 2 or 3 g plugs weathered for 6, 8, or 10 wk. Two and 3 g plugs weathered for 6 wk were as attractive as fresh lures, but 3 g plugs were more effective than 2 g plugs at the longer weathering intervals. Results are compared with prior studies, and implications for medfly management strategies are discussed.

An Environmentally-friendly Method for Removing Polymer Plugging in Well Boreholes

With the progresses of industrial scale of high concentration and high molecular weight polymer flooding in Daqing oilfield, there are severe polymer plug problems, which occur in the perforated zone and the interstices of the formation adjacent the perforated zone. In attempts to remove or at lease reduce these polymeric build-up plugs, the strong oxidants are widely used in oilfields. The use of oxidants is undesirable because of the high price and short efficient period. What is more, it cannot meet standards of safety and environmental protection. This article presents lab and field test results of this removing polymeric plug method based on microbial degrading polymer. Lab experiments results show that polymers with different molecular weights were efficiently degraded by screened bacteria under different reservoir temperatures. It can be seen in visualization model that polymer plugs in pore were removed obviously. The polymer injection pressure was decreased 25%. The pilot tests in Daqing oilfield showed that by applying the method, average injection pressure of each well was decreased 435 psia, the average effective period reached to 520 days, and more than 7,000 barrels (bbl) of oil were increased in the test field.

Preventing stone retropulsion during intracorporeal lithotripsy

Several studies of ureteroscopic treatment for ureteral stones have reported that most stone clearance failures can be attributed to stone fragment retropulsion. Stone retropulsion can result in increased operative time and cost-resulting from the need to change from the semi-rigid ureteroscope to a flexible instrument to chase migrated calculi-and additional procedures to treat residual migrated fragments are often required. The degree of migration depends mainly on the energy source used for lithotripsy; pneumatic and electrohydraulic lithotripters are associated with a greater degree of retropulsion than lasers. Different stone-trapping strategies and devices have been developed to minimize stone migration. Novel devices include the Lithovac(®) suction device, the Passport(™) balloon, the Stone Cone(™), the PercSys Accordion(®), the NTrap(®), and stone baskets such as the LithoCatch(™), the Parachute(™), and the Escape(®). Some authors have also reported on the use of lubricating jelly and BackStop(®) gel (a reverse thermosensitive polymeric plug); these devices are instilled proximal to the stone prior to the application of kinetic energy in order to prevent retrograde stone migration.

Development and evaluation of pulsatile drug delivery system using novel polymer

The aim of the present investigation was to develop a pulsatile drug delivery system based on an insoluble capsule body filled with theophylline microspheres and sealed with a swellable novel polymer plug isolated from the endosperm of seeds of higher plant Delonix regia family-Fabaceae. Theophylline microspheres were prepared by solvent evaporation method using Eudragit S 100. The swellable plugs of varying thickness and hardness were prepared by direct compression, which were then placed in the capsule opening. The drug delivery system was designed to deliver the drug at such a time when it was needed most to offer convenience to the chronic patients of asthma. Formulated dosage forms were evaluated for an in vitro drug release study, which showed that the release might be consistent with a release time expected to deliver the drug to the colon depending on the thickness and hardness of the hydrogel plug. Thus, thickness and hardness of the novel polymeric plug plays an important role in controlling the drug release from the formulated drug delivery system.

A New Long-Life Trimedlure Dispenser for Mediterranean Fruit Fly

New agricultural techniques are attempting to reduce the application of synthesized pesticides and replace them with new environmentally friendly methods such as mass trapping, mating disruption, or chemosterilization techniques. All these methods are based on the release of a lure for insect attraction or confusion. The success of the chosen method depends on the quality of the attractant emission from the dispenser. Currently, used dispensers with a polymeric matrix and new dispensers with mesoporous inorganic materials were evaluated to obtain more efficient emission kinetics. In this study, the selected pest was the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) and the lure used was trimedlure (TML). The dispensers were validated by means of a field study comparing insect catches with attractant release values. As a result, we have demonstrated that mesoporous dispensers have a clearly longer lifetime than the polymeric plug. Furthermore, the attractant release rate is less dependent on temperature in mesoporous than in polymeric dispensers.

Improved Controlled-Release Formulations for a New Trap Design for Male Mediterranean Fruit Flies: The C&C Trap

The Mediterranean fruit fly, Ceratitis capitata, is a major pest of fruits and vegetables in the world. With the help of an extensive trapping program, the continental United States has remained free of established medfly populations. In an effort to increase trapping efficiency, controlled-release polymeric panels with trimedlure and ceralure were developed in conjunction with the development of a new trap, the C&C trap. This study contrasts the effectiveness of different panel formulations with the standard trimedlure polymeric plug and describes the use of the panels in the C&C trap. Field tests in Hawaii using released sterile flies showed consistently higher male medfly catches with panels in C&C traps than with the standard trimedlure polymeric plug in Jackson traps.

Controlled Release of Trimedlure Isomer C from a Compressed Disk and the Evaluation of Its Attractiveness to the Mediterranean Fruit Fly (Diptera: Tephritidae)

Isomer C, the isomer of trimedlure most attractive to Mediterranean fruit flies, Ceratitis capitata (Wiedemann), was obtained in nearly pure form as crystals from aged or refrigerated commercial trimedlure. Crystalline trimedlure-C was compressed into disks with a pellet mold, and the release rate of isomer C from the disks was determined in the laboratory using a volatile collection system. Field-trapping tests comparing pure isomer C in compressed disks, the commercial trimedlure mixture in cotton wicks, and commercial trimedlure in polymeric plugs showed that the isomer C disks were competitive in attractiveness with the two currently used formulations for 8 wk. Trap catches with these three baits did not indicate that the other isomers in the trimedlure mixture added to or reduced the attractiveness of trimedlure-C to male Mediterranean fruit flies. Compressed disks of isomer C provide a method of testing the most attractive trimedlure isomer at precisely controlled release rates and isometric purity, in either laboratory or field tests.

Design, Effectiveness, and Performance Criteria of Dispenser Formulations of Trimedlure, an Attractant of the Mediterranean Fruit Fly (Diptera: Tephritidae)

Controlled-release dispensers of trimedlure (TML), a synthetic attractant of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), were evaluated in seven aging tests in natural and released populations. Insect captures and laboratory-measured release rates and residual contents showed that the cotton wick dispensers, which were formerly used for 2 g liquid TML (density = 1.0 g/ml), were generally ineffective after 2-4 wk of field exposure; a 4-g dose of TML increased the longevity, but not the initial biological activity of the cotton wick. Two controlled-release formulations, a polymeric plug (70% by weight TML) and a plastic laminate, extended the effective lifetime of 2 g TML to about 8 wk. A polymeric plug with 4 g TML further extended the duration of effectiveness to 12 wk or longer. Laboratory and field data suggested definitive values for relative insect capture, release rate, and residual trimedlure content, which have been used as performance criteria in the purchase of trimedlure dispensers.

Intramedullary plugs in cemented hip arthroplasty

The use of intramedullary plugs in cemented total joint arthroplasty is currently considered standard practice by most surgeons. In this in vitro study, the authors evaluated the holding power, migration, and leakage of four commonly used plug types—bone, acrylic bone cement, and two polymeric plugs from different manufacturers. Only acrylic bone cement plugs prevented distal leakage of cement and did not migrate under the influences of pressurized cement injection.