Hard Plastic Research Articles

Embarking On A New Course: Environmental Health Coverage

Embarking On A New Course: Environmental Health Coverage

Phthalates in Toys Available in Indian Market

Twenty four children's toys and child care articles available in the local market of India were analyzed for eight phthalates as children toys are plasticized with phthalates. All toy samples showed the presence of one or more phthalates including di-(2-ethylhexyl) phthalate (96% of the samples), di-iso-nonyl phthalate and di-iso-decyl phthalate (42% of the samples) at a concentration ranging from 0.1% to 16.2%. Soft toys contain higher levels of phthalates as compared to hard toys as primary function of phthalates is softening of hard plastic materiel.

Vibration of a single microcapsule with a hard plastic shell in an acoustic standing wave field

Observation techniques for measuring the small vibration of a single microcapsule of tens of nanometers in an acoustic standing wave field are discussed. First, simultaneous optical observation of a microbubble vibration by two methods is investigated, using a high-speed video camera, which permits two-dimensional observation of the bubble vibration, and a laser Doppler vibrometer (LDV), which can observe small bubble vibration amplitudes at high frequency. Bubbles of tens of micrometers size were trapped at the antinode of an acoustic standing wave generated in an observational cell. Bubble vibration at 27 kHz could be observed and the experimental results for the two methods showed good agreement. The radial vibration of microcapsules with a hard plastic shell was observed using the LDV and the measurement of the capsule vibration with radial oscillation amplitude of tens of nanometers was successful. The acoustic radiation force acting on microcapsules in the acoustic standing wave was measured from the trapped position of the standing wave and the radial oscillation amplitude of the capsules was estimated from the theoretical equation of the acoustic radiation force, giving results in good agreement with the LDV measurements. The radial oscillation amplitude of a capsule was found to be proportional to the amplitude of the driving sound pressure. A larger expansion ratio was observed for capsules closer to the resonance condition under the same driving sound pressure and frequency.

My memories of Jack Vallentyne

My memories of Jack Vallentyne

Prototyping of microfluidic systems using a commercial thermoplastic elastomer

This article describes the fabrication of microfluidic networks (μFNs) from a commercially available (styrene)–(ethylene/butylene)–(styrene) (SEBS) block copolymer (BCP). The unique combination of hard and elastomeric properties provided by this material promotes high-throughput replication of fluidic structures using thermoforming technologies, while retaining the advantage of quick and easy assembly via conformal contact, as commonly achieved for devices fabricated from poly(dimethylsiloxane (PDMS). We employ Versaflex CL30, which is optically transparent, available at low cost (e.g., $2.50/Lbs), and likely to be compatible with a broad range of biological species. We demonstrate excellent fidelity in replication of fluidic structures using hot embossing lithography in conjunction with a photolithographically prepared Si/SU-8 master mold. Moreover, we introduce rapid prototyping of high-quality structures using an approach that we call soft thermoplastic lithography (STPL). Thanks to the rheological characteristics of the SEBS copolymer, STPL enables thermoforming on a heated master at temperatures around 170°C. Using this approach, replication can be completed within a very short period of time (e.g., less than 3 min) without the need of resorting to pressure- or vacuum-assisted instrumentation. Serving as a proof-of-concept, we devise a μFN that is suitable for the formation of miniaturized arrays comprising fluorescently labeled oligonucleotides and proteins on hard plastic substrates. Resultant spots are characterized by high fluorescent contrast, excellent edge definition, and uniform distribution of probes within the modified areas.

Evaluation of a metofluthrin fan vaporizer device against phlebotomine sand flies (Diptera: Psychodidae) in a cutaneous leishmaniasis focus in the Judean Desert, Israel

The OFF! Clip-On fan vaporizer device releasing metofluthrin was evaluated against phletobomine sand flies in the Judean Desert, Israel, in October, 2009. A total of 76,400 sand flies was collected, with male flies representing 98.3%Phlebotomus sergenti and 1.7%P. papatasi. Females comprised 43.0% of the total catch and included 6.7% blood-fed females. Similar proportions of flies were collected in both suction and sticky traps. In trials with unbaited suction traps, similar numbers of sand flies were collected in traps with a metofluthrin device, blank device, or no device (i.e., suction only). In suction traps baited with CO(2) , higher numbers of P. sergenti males and blood-fed females were collected in traps with a blank device compared to traps with a metofluthrin device. In sticky traps baited with CO(2) , there were no significant differences between catches in traps with a metofluthrin device, blank device, or no device. The results suggest metofluthrin from the device is not repellent against sand flies in a field environment despite showing insecticidal activity against flies collected in suction traps.

A direct tying loop of silk sutures on the electrode

Editor, we experienced a case of lead migration in spinal cord stimulation (SCS), which was successfully corrected and fixed by tying the loops of silk sutures directly around the lead. A-42-year-old man visited our pain clinic with a complaint of burning pain, causalgia, and paresthesia in both legs. Despite continuous conservative therapy, severe pain persisted in the lower back, both buttocks, and knee and ankle areas; therefore, we decided to try spinal cord stimulation. After confirmation of induced paresthesia at the painful site, the lead and extension cables were connected, and a cylindrically shaped hard plastic was used for anchoring. Suture tying on the middle part of the cylindrically shaped hard plastic was performed with black silk. On the second day during the lead trial, paresthesia of the left leg disappeared; however, paresthesia developed in the lower abdomen. Although we changed the programming, paresthesia never developed at the painful site again. We suspected migration of the lead and checked the position of the lead through a T-L spine X-ray. On the left side, migration of the lead occurred in the cephalad direction, and the lead was positioned at the middle of the T7 level. To correct the position of the lead, we pulled the lead to the middle of the ninth vertebral body. Anchoring was performed again, and suture tying on the middle part of the cylindrically shaped hard plastic was performed with black silk. In addition, we made direct tying loops of silk sutures around the lead at the proximal site of the anchoring to prevent lead migration in the longitudinal direction again (Fig. 1). After revision of the lead, the patient could feel the paresthesia again on the painful side and the lead's position was maintained without any migration. Fig. 1 This picture shows the tying loops of the silk suture directly around the lead. Lead migration results in a loss of proper paresthesia coverage and a subsequent reduction in pain relief. Andersen [1], reporting on the use of SCS for angina, found that the most frequent complication requiring repeated surgery was lead migration (23%). Introduction of multichannel leads has greatly reduced the need for repeated revision as the result of lead migration. North et al. [2] found that programmable multichannel systems have a significantly greater clinical reliability than single-channel systems. Our patient also used multipolar leads; however, despite repeated trials of reprogramming, we failed in re-generation of paresthesia. When we checked the position of the lead, the lead had moved almost two vertebral levels, which is too far for generation of paresthesia to the painful site. In this case, to prevent lead migration, we made direct tying loops of silk sutures around the lead at the proximal site of the anchoring, and the result was successful. Oh et al. [3] presented an alternate anchoring technique, which involves tying loops of silk sutures directly around the lead without the use of silicone or hard plastic anchors. In our case, we used the cylindrically shaped anchor; in addition, we tied loops of silk sutures directly around the lead. Because the silk suture is tied directly on the lead, there is a possibility of lead damage. Kreis et al. [4] studied SCS lead integrity when direct silk sutures were made with supramaximal tension on the lead. They concluded that 28 SCS leads with 56 knot ties revealed no significant damage to polyurethane insulation by high power microscopy or change in conductor impedance. Because implanted silk sutures show a gradual loss of tensile strength over time, the risk of further wear and tear due to silk suture tension is minimal [4]. Our method has a limitation of being the routine for use in prevention of lead migration; however, it would be an alternative until a more successful and safe method can be developed.

Inadvertent Venous Air Embolism from Pressure Infuser Bag Confirmed by Transesophageal Echocardiography

Most reports on the topic of venous air embolism (VAE) deal primarily with surgical procedures where the operative site is above the level of the heart. Accidental administration of air while using a pressure infuser bag is rare. We report a case of cardiovascular collapse while applying pressure over a hard plastic bottle for rapid fluid infusion. Massive air bubbles in the right side of the heart were confirmed by intraoperative transesophageal echocardiography (TEE). This case demonstrates that TEE plays an important role in prompt diagnosis and management of VAE in anesthetized patients. The patient gave written permission to the authors to publish this report.

No Association Found Between Urinary BPA and Type 2 Diabetes

Bisphenol A (BPA), a chemical component of hard plastic containers and linings of metal cans since the 1960s, has been detected in the urine of more than 90% of children and adults in CDC studies. In …

EXPERIMENTAL STUDY ON EVALUATION OF GRAIN DIAMETER USING CONTACT TIME WHEN GRAVEL COLLIDES WITH ELASTIC PLATE

The sieve test is a method of measuring grain diameter for erosion control studies using a sieve made from a wire mesh. However, it is expensive to transport gravel from the field to the laboratory. Therefore, we looked for an easy, economical method of measuring grain diameter. We proposed a simple method for measuring the grain diameter in the field. Our method uses the contact time between the gravel and an elastic body. We determined the contact time between glass balls, gravel, and a hard plastic polyacetal board and found that the grain diameter was proportional to the contact time. Experimentally, there was a good correlation between the contact time and grain diameter. In addition, the count of the number of pieces of gravel was accurate. The contact time was measured and converted to the grain diameter. The resulting grain size histogram of the gravel determined in the experiments matched the material studied. Application of this method in the field is possible.

354 放射音を用いたCFRP積層板の実験的衝撃荷重同定

This paper proposes a method to identify the location and force history of an impact force acting on CFRP laminated plates using the radiated sound. Sound pressure measured with microphones is used to identify the impact force. The impact location is identified using arrival times of the sound wave at the sensors. Experimental transfer matrices, which relate the impact force and the measured sound pressures, are used to identify the force history. In order to verify the validity of the proposed method, impact force identification of a CFRP laminated plate is performed experimentally, and the identification results are compared with the measured ones. In addition, the effect of the stiffness of the impactor on the accuracy of identification results is examined by conducting experiments using two impulse hammer tips, one made of rubber and the other made of hard plastic. Moreover, the effect of noise on the accuracy is also examined. The experimental results reveal that the location and force history identified using the proposed method show good agreement with the measured ones. In order to identify the force history accurately, experimental transfer matrices should be constructed with an impulse hammer tip which can excite a wide frequency range.

Efficacy of an insecticide paint against insecticide-susceptible and resistant mosquitoes - Part 1: Laboratory evaluation

BackgroundThe main malaria vector Anopheles gambiae and the urban pest nuisance Culex quinquefasciatus are increasingly resistant to pyrethroids in many African countries. There is a need for new products and strategies. Insecticide paint Inesfly 5A IGR™, containing two organophosphates (OPs), chlorpyrifos and diazinon, and insect growth regulator (IGR), pyriproxyfen, was tested under laboratory conditions for 12 months following WHOPES Phase I procedures.MethodsMosquitoes used were laboratory strains of Cx. quinquefasciatus susceptible and resistant to OPs. The paint was applied at two different doses (1 kg/6 m2 and 1 kg/12 m2) on different commonly used surfaces: porous (cement and stucco) and non-porous (softwood and hard plastic). Insecticide efficacy was studied in terms of delayed mortality using 30-minute WHO bioassay cones. IGR efficacy on fecundity, fertility and larval development was studied on OP-resistant females exposed for 30 minutes to cement treated and control surfaces.ResultsAfter treatment, delayed mortality was high (87-100%) even against OP-resistant females on all surfaces except cement treated at 1 kg/12 m2. Remarkably, one year after treatment delayed mortality was 93-100% against OP-resistant females on non-porous surfaces at both doses. On cement, death rates were low 12 months after treatment regardless of the dose and the resistance status. Fecundity, fertility and adult emergence were reduced after treatment even at the lower dose (p < 10-3). A reduction in fecundity was still observed nine months after treatment at both doses (p < 10-3) and adult emergence was reduced at the higher dose (p < 10-3).ConclusionsHigh mortality rates were observed against laboratory strains of the pest mosquito Cx. quinquefasciatus susceptible and resistant to insecticides. Long-term killing remained equally important on non-porous surfaces regardless the resistance status for over 12 months. The paint's effect on fecundity, fertility and adult emergence may continue to provide an additional angle of attack in reducing overall population densities when the lethal effect of OPs diminishes over time. Some options on how to deal with porous materials are given. Implications in vector control are discussed.

The danger of stoicism

The danger of stoicism

Effect of Increasing the Hard Segment Percentage on the Mechanical Response of Selected Polyurethane Films

This paper describes a study which investigated aspects of the mechanical responses of selected polyurethane films (PUs) when the hard segment percentage was varied. The range of structures achieved included the chain extender ethylene glycol (EG), the macrodiol polytetrahydrofuran (PTHF) (molar mass 2000), and two di-isocyanates: 4,4′-methylene bis(phenyl isocyanate) (MDI) and 4,4′-dibenzyl diisocyanate (DBDI) generating dibenzyl-based hard segments of conformational mobility. The influence of increasing the hard segment percentage from 20 to 80%, on the mechanical properties was followed. The study of the PUs stress—strain response included tensile tests, and load—unload cycles at constant rate of extension, with measurement of hysteresis and strain recovery. As shown, the mechanical properties of such materials were greatly enhanced by hard-phase crystallinity, through its effect on the flow stress. Increasing the hard segment percentage led systematically to increases in the input strain energy elongation. With increasing hard segment percentage the polymers based on DBDI hard segments, displayed higher stiffness and strength than the conventional MDI-based PUs. Both features of the response were attributed to differences in hard phase plastic flow stress, resulting from crystallinity in the DBDI phase. With increasing hard segment percentage, lower strain recovery and strain energy recovery on cycling were observed in the case of PUs derived from dibenzyl structures.

A hard microflow cytometer using groove-generated sheath flow for multiplexed bead and cell assays

With a view toward developing a rugged microflow cytometer, a sheath flow system was micromachined in hard plastic (polymethylmethacrylate) for analysis of particles and cells using optical detection. Six optical fibers were incorporated into the interrogation region of the chip, in which hydrodynamic focusing narrowed the core stream to ~35 μm × 40 μm. The use of a relatively large channel at the inlet as well as in the interrogation region (375 μm × 125 μm) successfully minimized the risk of clogging. The device could withstand pressures greater than 100 psi without leaking. Assays using both coded microparticles and cells were demonstrated using the microflow cytometer. Multiplexed immunoassays detected nine different bacteria and toxins using a single mixture of coded microspheres. A549 cancer cells processed with locked nucleic acid probes were evaluated using fluorescence in situ hybridization.

CARDIOVASCULAR HEALTH: Exploring a Potential Link between BPA and Heart Disease

Most people in the United States are exposed to the plastic monomer bisphenol A (BPA), whether in plastic linings in food cans, containers made of hard plastic, or other plastics and foods containing BPA. Exposure to this suspected endocrine disruptor is illustrated by urine samples collected for NHANES (the National Health and Nutrition Examination Survey), for which the Centers for Disease Control and Prevention surveys thousands of adults and children. A new analysis of NHANES data published 13 January 2010 in PLoS ONE adds more evidence for an association between heart disease and higher exposures to BPA, even at the relatively low levels seen in the general population. David Melzer, an epidemiologist at the University of Exeter, United Kingdom, and his colleagues first looked at NHANES data collected from 2003 and 2004; their results, published in the 17 September 2008 issue of JAMA, were the first to show an association between higher levels of BPA metabolites in urine and adverse adult health outcomes, including heart disease. The current analysis considered NHANES data from 2005 and 2006. Although the BPA levels in urine samples from this new group of people were lower by almost a third, the association remained between coronary heart disease and higher urinary BPA. While this study may help inform future research, such cross-sectional studies “should not be used to demonstrate that a particular chemical can cause a particular effect,” said Steven G. Hentges of the Polycarbonate/BPA Global Group of the American Chemistry Council in a 13 January 2010 press release. And indeed, Melzer and his colleagues emphasize that because this study is cross-sectional—a snapshot in time instead of a long-term observational investigation—they cannot say whether BPA contributes to heart disease or if heart disease changes the exposure to or metabolism of BPA in adults. “What would really help is if industry and regulators could support independent studies [to examine] whether high BPA levels are present before any disease started,” Melzer says. “Chasing human [data] is the way forward,” says Richard Sharpe, an endocrinologist from The Queen’s Medical Research Institute in Edinburgh who did not participate in the research. NHANES provides a robust data set, he says, and the repeatability of the association with a second survey group is positive. However, that replication is somewhat incomplete because not all of the associations found with BPA in the first study were found in the second. “The more logical interpretation of the results as they stand at the moment is that they are looking at two variables that are associated with something else,” Sharpe says. Diet, for instance, is a major contributor to heart disease in the United States and also a major source of BPA exposure. “We should remember that heart disease develops over a long period of time,” Sharpe says, “so if BPA is involved causally, a cross-sectional study such as this [PLoS ONE report] cannot show this.” Scott Belcher, a scientist at the University of Cincinnati, says the association in humans is “not super surprising in light of our animal studies and because we already know estrogens are related to various cardiovascular end points.” Belcher’s team reported at the June 2009 Endocrine Society annual meeting that BPA exposure in vitro in muscle cells and in whole hearts from female rodents leads to arrhythmias, and they recently received American Recovery and Reinvestment Act funds from the NIEHS to conduct further research on BPA in mice. Meanwhile, pending the release of an updated toxicology review for BPA, the Food and Drug Administration announced in January 2010 it is “taking reasonable steps to reduce human exposure to BPA in the food supply.”

A packaged optical slot-waveguide ring resonator sensor array for multiplex label-free assays in labs-on-chips

We present the design, fabrication, and characterisation of an array of optical slot-waveguide ring resonator sensors, integrated with microfluidic sample handling in a compact cartridge, for multiplexed real-time label-free biosensing. Multiplexing not only enables high throughput, but also provides reference channels for drift compensation and control experiments. Our use of alignment tolerant surface gratings to couple light into the optical chip enables quick replacement of cartridges in the read-out instrument. Furthermore, our novel use of a dual surface-energy adhesive film to bond a hard plastic shell directly to the PDMS microfluidic network allows for fast and leak-tight assembly of compact cartridges with tightly spaced fluidic interconnects. The high sensitivity of the slot-waveguide resonators, combined with on-chip referencing and physical modelling, yields a volume refractive index detection limit of 5 x 10(-6) refractive index units (RIUs) and a surface mass density detection limit of 0.9 pg mm(-2), to our knowledge the best reported values for integrated planar ring resonators.

피스톤크라운의 열간단조공정 최적화를 위한 유한요소해석

Piston crown to the hot forge a unified nature of the product has a shape with multi-level step forging process, so if you are not a mechanical professional, this process could lead to a significant loss to the material. Therefore, material technology in minor terms; continue to improve the collection rate that undamaged the product material. The piston crown and the manufacturing products such as marine diesel engines are being forged to reduce costs and to improve mechanical properties. Piston crown molding is a hot forging process that works in large volume forging products. Because of the size of the hard plastic material flow process for improving the design and actual field experience through advanced plastic technology, it is important to interpret the results. Also for many experimental plastic procedures, the accumulation of results is very important.

Hard Segment Inelastic Effects on the Stress–Strain Response of Polyurethane Elastomers Based on Hard Segments of Variable Geometry

A study was made of a family of thermoplastic polyurethane copolymers, in which the nature and number of the hard segment components (crystallizing or not) were varied. Materials were synthesized with ethylene glycol (EG) as chain extender. Changes induced by varying the type and the number of isocyanates and the order of their introduction were followed and the mechanical responses were measured in cyclic tensile tests and stress relaxation in interrupted tests. Polymers based on DBDI hard segments showed lower strain recovery and strain energy recovery on cycling than did the conventional materials with MDI and the materials based on mixtures of isocyanates MDI/DBDI. Such features of the response were attributed to differences in hard phase plastic flow stress; hard domain hydrogen bonding exerted strong influences on the inelasticity of polyurethane elastomers. Stress-strain cycles reflected the resistance to plastic deformation occurring in the hard domains. This was enhanced by more pronounced hydrogen bonding achieved in the more mobile DBDI than in MDI.

Eye Protection in Orthopaedic Surgery

Conjunctival contamination from splashed debris during orthopaedic surgical procedures places surgeons at risk for communicable diseases such as human immunodeficiency virus (HIV) and hepatitis B and C. The purpose of this study was to compare the effectiveness of various types of protective eyewear in preventing conjunctival contamination. A simulation model was constructed with use of a mannequin head in a typical position of a surgeon's head during an operation. The head was placed at an appropriate distance from the surgical field, and a femoral osteotomy was performed on a cadaver thigh. Six experimental groups were tested to determine the ability of various types of eye protection to prevent contamination of the conjunctiva: (1) modern prescription glasses, (2) standard surgical telescopic loupes, (3) hard plastic contoured glasses, (4) disposable plastic glasses, (5) a combination facemask and eye shield, and (6) no protection (control). Thirty femoral osteotomies were performed, and contamination of both the protective devices and the simulated conjunctival surfaces were recorded. None of the tested devices were completely effective. The modern prescription glasses and the controls both were associated with conjunctival contamination rates of 83%. The other eye protective devices were associated with significantly lower rates of overall contamination, with a rate of 50% for the loupes, 30% for the facemask and eye shield, 17% for the hard plastic glasses, and 3% for the disposable plastic glasses. Modern prescription glasses provided no benefit over the control in our experimental model; therefore, we do not recommend that they be used as the sole eye protection, especially during surgical procedures in which there is a high rate of debris expulsion from the wound. Readily available and disposable plastic glasses were associated with the lowest rate of conjunctival contamination (3%) and are an effective means with which to protect the orthopaedic surgeon from communicable diseases by conjunctival contamination.