Polyolefin Recyclates for Rigid Packaging Applications: The Influence of Input Stream Composition on Recyclate Quality.

In order to shift to a circular plastics economy, high quality recyclates are required to effectively substitute virgin materials. Current approaches to empirically quantify the substitutability for recyclates are mainly limited by the abundance of virgin material grades along with a lack of adequate application-specific property profiles. In contrast, this work aims for a holistic analysis of the substitution potential of polyolefin recyclates intended for rigid packaging applications. This approach is fundamentally based on the classification of virgin polyolefins into different application-specific sub-groups with defined property windows derived from supplier data sheets, which allows for a generalization within one polymer type without neglecting the various available material grades. Moreover, the findings should provide valuable information for improvements of quality-defining process steps along the value chain of mechanical recycling. Therefore, it is of great importance to correlate the input stream composition of the investigated recyclates with the obtained qualities. The investigation of the substitution potential for selected recyclates clearly highlights the necessity of functional recycling for enhanced quality levels, which especially affects the sorting step in the recycling value chain. This work illustrates that a homogeneous waste stream directly correlates with a high substitution potential. Thus, the development of economically viable sorting strategies which take the functionality of plastic waste products into account must be targeted in future research. Furthermore, the development of detailed application-specific property windows in a joint effort with manufacturers should be pursued, as it allows for a meaningful empirical quantification of the substitutability for recyclates obtained from mechanical recycling.

From Bottle Caps to Frisbee-A Case Study on Mechanical Recycling of Plastic Waste towards a Circular Economy.

This study demonstrates an open-loop recycling process of a specific post-consumer plastic waste stream. The targeted input waste material was defined as high-density polyethylene beverage bottle caps. Two methods of waste collection, informal and formal, were employed. Thereafter, materials were hand-sorted, shredded, regranulated, and then injection-molded into a flying disc (i.e., frisbee) as a pilot product. To observe the potential changes in the material throughout the entire recycling process, eight different test methods including melt mass-flow rate (MFR), differential scanning calorimetry (DSC), and mechanical tests were carried out on the various material states. The study showed that the informal collection led to a relatively higher purity in the input stream, which also appeared to have a 23% lower MFR value compared to that of the formally collected materials. The DSC measurements revealed a cross-contamination by polypropylene, which clearly affected the properties of all investigated materials. The cross-contamination led to a slightly higher tensile modulus in the recyclate, while the Charpy notched impact strength declined after processing by approximately 15% and 8% compared to those of the informal and formal input materials, respectively. All materials and the processing data were documented and stored online as a practical implementation of a digital product passport as a potential digital traceability tool. Furthermore, the suitability of the resulting recyclate to be used in transport packaging applications was also investigated. It was found that a direct replacement of virgin materials for this specific application is not possible without proper material modification.

Simultaneous Modification of Properties Relevant to the Processing and Application of Virgin and Post-Consumer Polypropylene.

Post-consumer recyclates often have a property profile that results from mixing a variety of products, which are made from different materials, produced by different processing methods, and coming from applications with different lifetimes. This usually leads to a mixture of all these material properties in the recycling process. In contrast, virgin materials are specifically designed for applications and thus offer all the necessary properties for the intended products. In order to be able to use recycled materials for specific and demanding applications, not only the viscosity, which is important for processing and often varies greatly with recyclates, but also the mechanical properties, particularly the tensile modulus and impact strength, must be adjusted. For this purpose, various virgin materials of polypropylene homopolymers, random copolymers, and block copolymers with different flowabilities were mixed in different proportions and their properties were determined. The flowability of homopolymers and random copolymers in the blend behaved very similarly, while block copolymers exhibited a different behavior in some cases. By incorporating homopolymers into blends, the stiffness of the resulting material blend can be very well adjusted. The addition of random copolymers can increase strain at break, and the addition of block copolymers results in a significant increase in impact strength. In numbers, the maximum adjustment range for tensile modulus, yield stress, strain at break, and impact strength are 880 MPa, 14 MPa, 185%, and 6.9 kJ/m2, respectively. While a good and reliable prediction of property profile is possible for polymer blends with different virgin materials, the resulting material properties for polymer blends of virgin and recycled materials are also influenced by impurities. In this work, however, a good prediction was also achieved for recyclate blends.

Polypropylene Post-Consumer Recyclate Compounds for Thermoforming Packaging Applications.

Polypropylene (PP) plastic packaging waste consists of a variety of different plastic packaging products with a great span in rheological and mechanical behavior. Therefore, the resulting post-consumer recyclates usually show melt mass-flow rates (MFR) in the region of injection molding grades and intermediate mechanical properties. High-quality packaging applications demand a distinct property profile that is met by tailor-made PP grades and cannot be met by recyclates with intermediate performance. One such application with high market volume is high-stiffness thermoforming trays. The aim of this research was to blend intermediate-performance recyclates with a virgin PP grade to obtain compounds that fulfill the rheological and mechanical demands of this application. Three commercially available PP post-consumer recyclates were acquired and compounded with different blending ratios with a high stiffness, low MFR virgin PP grade. As the pure recyclates show different rheological properties, the blending ratios had to be adapted for each of them to fit into the MFR range of 2-4 g/10 min which is desirable for thermoforming applications. The resulting PP recyclate compounds show a distinct correlation of recyclate content with rheological and mechanical performance. However, the resulting property profile was directly dependent on the performance of the originally used recyclate. The best-performing recyclate could be used in a blending ratio of 65 m% recyclate content while adhering to both property limits, the MFR of 2-4 g/10 min and the lower bound tensile stiffness of 1500 MPa.

Polypropylene Pipe Compounds with Varying Post-Consumer Packaging Recyclate Content.

The high recycling targets set by the European Commission will create an increased availability of polypropylene (PP) post-consumer recyclates (PCRs). However, no regulations mandate the use of recycled PP (rPP), so the industry is challenged to explore possibilities to utilize such materials. One option, as suggested by the European Commission, is the introduction of rPP in pipe applications. According to existing standards, the use of recyclate is not allowed in pressurized gas and drinking water systems. However, many other pipe and underground applications, such as stormwater systems, open the increased use of PCRs. Additionally, even for less-demanding applications, such as non-pressure sewage systems, highly durable solutions are needed to cover the requested lifetime and request an ambitious property profile to fulfill the application needs that cannot be met by PP packaging materials and even less by PCRs thereof. Hence, this work explores the possible use of commercially available PCRs out of polypropylene from packaging applications in compounds together with virgin PP pipe grades to meet the demands for less-demanding applications. Two different commercially available rPPs and one commercially available recycled polyolefin (rPO) from mixed polyethylene and PP waste were acquired and, together with two predefined virgin PP pipe grades, were blended to compounds in the range of 10 m%, 20 m%, and 30 m% recyclate content. The compounds and three virgin PP pipe grades, acting as benchmarks, were tested in terms of short- and long-term mechanical performance as well as for many other physical properties. All of the compounds showed good results regarding fatigue crack (FCG) resistance with virgin polymer as the reference. The factors influencing FCG resistance, such as melt flow rate and polyolefin cross-contamination, were thoroughly investigated as the used virgin grades and recyclates cover a broad range of these properties.

Sampling Scheme Conception for Pretreated Polyolefin Waste Based on a Review of the Available Standard Procedures.

Given the rapid development of plastics recycling in recent years, the need for guidelines for sampling and material characterization is steadily emerging. However, there still exists a considerable scarcity of methods that enable proper material data acquisition. This paper consists of two parts. The first part provides a critical review of the available sampling techniques that can be utilized in the field of plastics recycling. Several sampling studies were covered in the review alongside the prominent standardization institutions. It was found that neither the literature nor the standards provide a comprehensive practice that considers the distinctive characteristics of plastic waste and applies it to different situations along the value chain. In the second part, a proposal of a sampling plan for pretreated rigid plastic waste is conceptualized based on selected information from the reviewed methods. Two variants of the proposed plan were evaluated based on the flake size distribution and the apparent density of four different pretreated polyolefin (PO) waste materials. The results of the study showed that combining stratified random sampling with composite sampling yields a good sampling technique for rigid PO waste. Moreover, the analysis of a composite sample adequately conveys the true material properties of a sublot or lot.

Application of Mixing Rules for Adjusting the Flowability of Virgin and Post-Consumer Polypropylene as an Approach for Design from Recycling.

To enable the use of recyclates in thermoformed polypropylene products with acceptable optical appearance and good mechanical stability, a multilayer structure of virgin and recycled material can be used. When producing multilayer films with more than two layers, the used materials should have similar melt flow properties to prevent processing instabilities. In the case of a three-layer film, post-consumer recyclates are often hidden in the core layer. Due to the inconsistent melt flow properties of post-consumer recyclates, the adjustment of the melt flow properties of the core layer to those of the outer layers has to be realized by blending with virgin materials. In order to understand the effect of mixing with a virgin material with a certain pre-defined melt flow rate (MFR), material mixtures with different mixing partners from various sources were realized in this study. Hence, the pre-defined virgin material was mixed with (i) virgin materials, (ii) artificial recyclates out of a mixture of different virgin materials, and (iii) commercially available recyclates. These blends with mixing partner contents ranging from 0-100% in 10% increments were prepared by compounding and the MFR of each mixture was determined. For a mathematical description of the mixing behavior and furthermore for a proper MFR prediction of the material mix, existing mixing rules were tested on the three pre-defined sample groups. Therefore, this paper shows the applicability of different mixing rules for the prediction of the MFR of material blends. Furthermore, a new mixing rule was developed using symbolic regression based on genetic programming, which proved to be the most accurate predictive model.

Determination of the Influence of Multiple Closed Recycling Loops on the Property Profile of Different Polyolefins.

In a circular economy, polymeric materials are used in multiple loops to manufacture products. Therefore, closed-loops are also envisaged for the mechanical recycling of plastics, in which plastic is used for products that are in turn collected and reprocessed again and again to make further products. However, this reprocessing involves degradation processes within the plastics, which become apparent through changes in the property profile of the material. In the present paper, the influence of multiple recycling loops on the material properties of four different polyolefins was analyzed. Two different closed-loop cycles with industrially sized processing machines were defined, and each polyolefin was processed and reprocessed within the predefined cycles. For the investigation of the effect of the respective loops, samples were taken after each loop. The samples were characterized by high-pressure liquid chromatography coupled to a quadru-pole time-of-flight MS, high-temperature gel permeation chromatography, melt flow rate measurements, infrared spectroscopy, differential thermal analysis, and tensile tests. With increasing number of processing loops, the tested polyolefins showed continuous material degradation, which resulted in significant changes in the property profiles.

Short- and Long-Term Performance of Pipe Compounds Containing Polyethylene Post-Consumer Recyclates from Packaging Waste.

The polymer industry is pushed to present solutions that lead to a circular plastics economy. High plastic packaging waste recycling targets will eventually lead to a high availability of packaging material recyclates. Although the use of polyethylene terephthalate (PET) recyclates is prescribed by regulations to be used in new PET bottles, no such regulation prescribes the use of polyethylene recyclate (rPE) in new products. One possibility of using rPE, which is considered by the European Union, is the use within pipe materials. Pipe applications demand a certain property profile, most prominently a high slow crack growth (SCG) resistance, which is not met by most packaging materials or recyclates made from it. Hence, this work investigates the use of commercially available post-consumer recyclates out of high-density polyethylene from packaging applications in compounds together with high SCG-resistant virgin PE pipe material with a PE100-RC specification. Two rPEs were acquired from German producers and blended to compounds consisting of 25 m%, 50 m% and 75 m% recyclate. These compounds, together with the pure recyclates and several virgin pipe materials acting as benchmarks were tested in terms of short- and long-term mechanical performance and with other basic characterization methods. Several compounds exceeded the performance of one tested virgin PE pipe material, an injection molding PE80 grade, in several categories. The content of recyclate needed to outperform this benchmark grade was mostly dependent on the resulting melt flow rate (MFR) of the compound and thus also of the MFR of the pure recyclate. Furthermore, different levels of polypropylene contaminations within the recyclates resulted in differently contaminated compounds. This is proved to influence the SCG resistance too, as compounds of similar MFRs but with different SCG resistances were found.

Lateral Resolution of a Commercial Optical Coherence Tomography Instrument.

Purpose: The lateral resolution of an optical coherence tomography (OCT) instrument was considered to be equal to the illumination spot size on the retina. To evaluate the potential lateral resolution of the Spectralis OCT, an instrument calculated to have a 14 µm resolution. Methods: The lateral point spread function (PSF) was evaluated using diamond abrasive powder 0 to 1 µm in diameter in silicone elastomer and a validated target with 800 nm FeO particles in urethane. The amplitude transfer function was calculated from human OCT images. Finally, resolution was measured using the 1951 USAF target. Results: Measurement of the lateral PSF from 1215 diamond particle images yielded a full-width half maximum (FWHM) to be 5.11 µm and for 732 FeO particles, 4.9 µm. From the amplitude transfer function, the FWHM of the diffraction limited PSF was calculated to be 5.0 µm. The USAF target imaging showed a lateral resolution of 4.6 µm. Conclusions: Although a calculation of the spot size of the illumination beam was reported in the past as the lateral resolution of the OCT instrument, the actual lateral resolution is better by a factor of at least 2.5 times. The clinically used A-scan spacing was derived from the calculated, and not the true resolution, and results in under sampling. This set of findings likely apply to all commercial clinical instruments. Translational Relevance: The scan density parameters of past and present commercial OCT instruments were based on earlier translational concepts, which now appear to have been incorrect.

Assessment of Commercially Available Polyethylene Recyclates for Blow Molding Applications by a Novel Environmental Stress Cracking Method.

The transition to a circular economy has a major impact on waste management and the reuse of materials. New mandatory recycling targets for plastics will lead to a high availability of recyclates. For these recyclates, useful applications need to be found. One potential application for recyclates is blow molding bottles as packaging for non-food contents. This study investigates commercially available post-consumer high-density polyethylene recyclates together with virgin blow molding grades in terms of their short-term mechanical properties and environmental stress cracking resistance. While the short-term mechanical properties showed only slightly lower performance than the tested virgin grades, the overall environmental stress cracking failure times of the recyclates were much lower compared to virgin materials, even though the crack-growth kinetics could be similar. Although neither the tensile nor the notched impact strength results of the two polyethylene recyclates revealed large differences, the stress intensity-factor-dependent crack-growth rates of both materials were significantly different.

Characterization of Composition and Structure-Property Relationships of Commercial Post-Consumer Polyethylene and Polypropylene Recyclates.

The current efforts in moving closer towards a circular plastics economy puts massive pressure on recycled plastics, especially recycled polyethylene (rPE) and recycled polypropylene (rPP) to enter new markets. Their market penetration remained low so far, despite PE and PP constituting the largest share of plastic wastes. However, with the current imperative of more circularity comes a new focus on performance of recyclates. Hence, a detailed understanding of composition and structure-property relationships of post-consumer recyclates has to be developed. Five recycling companies from the Austrian and German markets were asked to supply their purest high-quality rPE and rPP grades. These were characterized by differential scanning calorimetry (DSC), thermo-gravimetric analysis (TGA), and Fourier-transform infrared (FTIR) spectroscopy, and micro-imaging. Technological characterization included density measurements, determination of the melt flow rate (MFR), and Charpy impact testing. All recyclates contained diverse contaminants and inclusions ranging from legacy fillers like calcium carbonate to polymeric contaminants like polyamides or polyolefin cross-contamination. The overall amount, size, and distribution of contaminants varied significantly among suppliers. Furthermore, first structure-property relationships for polyolefin recyclates that link inorganic content and polymeric purity with density and impact performance could be derived.

Development of probiotic orodispersible tablets using mucoadhesive polymers for buccal mucoadhesion.

OBJECTIVE: Probiotic bacteria, such as different lactobacilli strains, have successfully been used to treat gingivitis and periodontitis or caries. By formulating probiotics as orodispersible tablet (ODT), the benefits of this dosage form could be utilized. Without any further measures, the probiotic bacteria will be eliminated too fast from the intended site of action, the oral mucosa. The use of mucoadhesive granules, composed of mucoadhesive polymer and probiotics, is a promising strategy to prolong the contact time between lactobacilli and oral mucosa without delaying disintegration. METHODS: Three common mucoadhesive polymers, anionic Carbopol 971P NF, nonionic Metolose 65SH50 and cationic chitosan were included into tablets either by direct compression (DC) or after granulation with the probiotics. Disintegration, mucoadhesion of the tablets, and storage stability of the probiotics were characterized. RESULTS: By incorporating a sufficient amount of polymer superior probiotic mucoadhesion could be achieved. All formulations based on granulated probiotics and mucoadhesive polymer fulfilled the Food and Drug Administration (FDA) acceptance level for disintegration of orodispersible tablets. These formulations exhibited excellent storage stability under refrigerated conditions over 30 months. Interestingly, ODTs including Carbopol 971P NF still proved superior mucoadhesion after long-term storage, whereas the mucoadhesive effect of Metolose 65SH50 and chitosan declined markedly. CONCLUSIONS: The results of this study suggest that Carbopol 971P NF was the most appropriate polymer for a probiotic mucoadhesive ODT.

Global and Local Aging in Differently Stabilized Polypropylenes Exposed to Hot Chlorinated Water with and without Superimposed Mechanical-Environmental Loads.

The influence of chlorinated water on the global and local aging behavior of polypropylene (PP) was investigated for three differently stabilized PP grades consisting of the same PP base polymer. While one of the PP grades contained only a processing stabilizer (PP-S0), the other two were modified with a primary phenolic antioxidant (PP-S1) and a combination of a primary phenolic antioxidant and a hindered amine stabilizer (PP-S3). To study global aging effects, micro-sized specimens were pre-exposed to chlorinated water (5 mg/L free chlorine) at 60 °C for up to 750 h. Over the entire exposure period, significant material aging was detected by monitoring a continuous decrease in stabilizer content, oxidation induction temperature, mean molar mass, and mechanical strain at break. In terms of aging resistance and ultimate mechanical performance, PP-S1 was found to outperform the other two material formulations under these test conditions. Moreover, superimposed mechanical-environmental fatigue tests with cracked round bar specimens were carried out with the three PP grades in non-chlorinated (0 mg/L free chlorine) and chlorinated (5 mg/L free chlorine) water at 80 °C and 95 °C to study local crack tip aging effects. While the fatigue crack growth resistance substantially deteriorated for all three materials in chlorinated water, a significantly stronger effect was found for the higher temperature, with crack growth rates at a given stress intensity factor range in chlorinated water being ca. 30 to 50 times faster than in non-chlorinated water, depending on the material. Molar mass measurements of material samples taken from various positions of the tested CRB specimens provided clear evidence of enhanced local crack tip aging due to the chlorinated water environment.

Chlorinated Water Induced Aging of Pipe Grade Polypropylene Random Copolymers.

Polypropylene random copolymers (PP-R) are common materials for pressurized hot water pipes. In many pipe systems, potable water is disinfected by chlorine to prevent waterborne diseases. This paper deals with hot chlorinated water induced aging of two PP-R grades with varying morphology. One material had a conventional monoclinic α crystal form (PP-Rα), whereas the other was explicitly beta-nucleated resulting in a trigonal ß crystal form with a fine spherulite structure (PP-Rß). Micro-sized specimens with a thickness of 100 µm were used for aging experiments at 60 °C in chlorinated water with 5 mg/L free chlorine, and aging indicators were monitored for exposure times of up to 2000 h. On the other hand, superimposed mechanical-environmental tests were carried out by using cracked round bar specimens with a diameter of 14 mm to determine the fatigue crack growth (FCG) resistance of both PP-R grades at 60 °C in non-chlorinated and chlorinated water. PP-Rß was found to outperform PP-Rα with an about 30% higher time-to-embrittlement value of 2000 h. Furthermore, PP-Rß exhibited an enhanced FCG resistance in both non-chlorinated and chlorinated water. The effect of chlorine content on the deterioration of the FCG resistances was significantly more pronounced for PP-Rα.

Ex vivo anti-inflammatory effects of probiotics for periodontal health.

Background: Probiotic bacteria with anti-inflammatory properties have the potential to be of therapeutic benefit in gingivitis. Objective: To evaluate the effects of potential probiotic strains on inflammatory mediators involved in early gingivitis using an ex vivo inflammation model. Methods: Strains were screened in viable and attenuated forms for effects on bacterial lipopolysaccharide (LPS)-stimulated release of interleukins (IL)-1ß, -6 and -8, tumor necrosis factor-α, prostaglandin E2 and 8-isoprostane from human primary monocytes, and then, if anti-inflammatory effects were shown, on IL-1ß-stimulated release of inflammatory mediators from primary gingival fibroblasts. Lead strains were evaluated for optimal dosing, batch-to-batch variation and functional consistency in toothpaste. Results: Twenty-one of 73 strains showed anti-inflammatory effects in monocytes; of which, seven showed effects in both viable and attenuated forms. Seven of 14 strains showed effects in fibroblasts. Strains Lactobacillus paracasei LPc-G110(SYBIO-15) and Lactobacillus plantarum GOS42(SYBIO-41) induced statistically significant dose-dependent reductions in the release of multiple inflammatory mediators from monocytes, which were consistent across batches. Viable L. paracasei LPc-G110 tooth paste significantly reduced IL-6, IL-8 and prostaglandin E2 release from monocytes versus placebo. Conclusion: Strains L. paracasei LPc-G110 and L. plantarum GOS42 have potential for use as probiotics in oral care products to reduce gingival inflammation.

Influence of Hot Chlorinated Water and Stabilizer Package on the Fatigue Crack Growth Resistance of Glass Fiber Reinforced Polyamide.

To assess the potential use of polyamide (PA) for solar-thermal systems applications, the effect of water with varying chlorine content on the fatigue crack growth (FCG) resistance of two PA formulations differing in their stabilizer packages was investigated at 80 °C. A commercial PA containing 30 wt % glass fibers and a standard stabilization package (PA-0) was used as the reference material. For the other formulation, the reference material PA-0 was compounded with two additional stabilizers (PA-S1). Keeping the specimen geometry and initial loading conditions the same, the total number of cycles to ultimate specimen failure was found to be reduced with an increase in chlorine content for both materials. As to the effect of the chlorine content on crack growth kinetics, the most pronounced effect in enhancing the crack growth rates or decreasing the FCG resistance was determined between 0 ppm and 1 ppm chlorine content. When comparing the relative change of FCG resistance in chlorinated water (10 ppm) to the FCG resistance in non-chlorinated water (0 ppm), the additional stabilization in the material PA-S1 appears beneficial over the stabilization in the reference material PA-0.

Characterization of Irradiation Crosslinked Polyamides for Solar Thermal Applications-Basic Thermo-Analytical and Mechanical Properties.

Polyamide 66 (PA 66) and short glass fiber reinforced versions of PA 66 are widely used for solar-thermal applications, in which thermal and environmental loading of components is from high importance. In this study, the influence of crosslinking via electronic beam irradiation on the morphology and mechanical behavior of unreinforced PA 66 and two types of short glass fiber reinforced PA 66 (30 wt % glass fiber content, 35 wt % glass fiber content) was investigated. In total, five different electronic beam irradiation doses in the range of 0 and 200 kGy were applied. Besides experiments with unconditioned specimens, also preconditioned specimens saturated with water at 80 °C for seven days were investigated. It was found that irradiation causes a shift to lower melting temperatures and lower melting enthalpies, while simultaneously leading to higher glass transition temperatures (TG), increasing small strain modulus values and higher tensile strengths. Also, as expected, preconditioning samples in water at 80 °C to water uptake saturation leads to a shift to lower TG values ('plasticization' effect). In terms of tensile behavior at room temperature, water saturated specimens (being above TG at room temperature) exhibited lower modulus and tensile strength values compared to quasi-dry specimens (being below TG at room temperature).

Mapping of sheep sensory cortex with a novel microelectrocorticography grid.

Microelectrocorticography (µECoG) provides insights into the cortical organization with high temporal and spatial resolution desirable for better understanding of neural information processing. Here we evaluated the use of µECoG for detailed cortical recording of somatosensory evoked potentials (SEPs) in an ovine model. The approach to the cortex was planned using an MRI-based 3D model of the sheep's brain. We describe a minimally extended surgical procedure allowing placement of two different µECoG grids on the somatosensory cortex. With this small craniotomy, the frontal sinus was kept intact, thus keeping the surgical site sterile and making this approach suitable for chronic implantations. We evaluated the procedure for chronic implantation of an encapsulated µECoG recording system. During acute and chronic recordings, significant SEP responses in the triangle between the ansate, diagonal, and coronal sulcus were identified in all animals. Stimulation of the nose, upper lip, lower lip, and chin caused a somatotopic lateral-to-medial, ipsilateral response pattern. With repetitive recordings of SEPs, this somatotopic pattern was reliably recorded for up to 16 weeks. The findings of this study confirm the previously postulated ipsilateral, somatotopic organization of the sheep's sensory cortex. High gamma band activity was spatially most specific in the comparison of different frequency components of the somatosensory evoked response. This study provides a basis for further acute and chronic investigations of the sheep's sensory cortex by characterizing its exact position, its functional properties, and the surgical approach with respect to macroanatomical landmarks.

Cosmetic permanent fillers for soft tissue augmentation: a new contraindication for interferon therapies.

BACKGROUND: Most of the new fillers used for soft tissue augmentation in aesthetic dermatology are considered well tolerated, but very little data are available on their long-term tolerability, especially in patients receiving immunomodulatory therapy. OBSERVATIONS: A 48-year-old woman presented with disfiguring facial edema 10 weeks after she began antiviral therapy with peginterferon alfa-2a and ribavirin for chronic hepatitis C infection. The major affected sites had been treated 10 years before with Artecoll, a permanent filler containing polymethylmethacrylate. A treatment attempt with allopurinol was initiated while antiviral therapy was continued and was successfully completed after 6 months. Despite significant improvement, extended plastic surgery was necessary for facial reconstruction. CONCLUSIONS: The normal host response to a cosmetic filler is a weak granulomatous reaction. Interferon and other immunostimulatory medications can lead to an exacerbation of this preexisting low-grade chronic inflammation that is quite similar to interferon-triggered sarcoidosis. This potential long-term risk has medicolegal implications for informed consent and for the potential use of both permanent fillers and interferon.