Chemical recycling of post-consumer PET: Alkyd resins synthesis

The recycling of post-consumer poly(ethylene terephtalate) (PET) is a worldwide concern due to its environmental impact and the large and increasing volume of these materials produced by society. We use post-consumer PET in alkyd resin synthesis for coatings, replacing a fraction of phthalic anhydride (PA) and ethylene glycol (EG) of conventional synthesis for post-consumer PET.     

Evaluating hardening laws at large tensile strains in sheet specimens

In the finite element modeling of sheet metal formability, the strains in the sheet are calculated from a hardening law which is normally derived from a tensile test. These laws are known to be accurate only up to the maximum uniform strain in tension. However, they are extrapolated during modeling to strains three to five times greater than the uniform strain. In assessing the applicability of these hardening laws at large strains, tensile specimens of 1008 AK steel and commercial purity titanium and zinc were gridded with a fine mesh and slowly pulled to failure. During the test, photographs were taken of the deforming grid in order to develop a complete strain and strain-rate history for each element across the minimum cross section. These data were combined with a hardening law for each material to calculate the total axial load on the specimen. Good agreement between the calculated and measured loads suggests that hardening laws for these materials can be extrapolated to large strains.     

Erratum

Nuclear power plants are presently designed to withstand instantaneous pipe severance in combination with the maximum seismic loads. The hypothetical combination of these two unlikely events leads to system designs which are very expensive and require dynamic event devices such as pipe whip restraints which have the potential for deleterious interaction with the piping system during normal operations. These present pipe rupture criteria are based on the a priori hypothesis that the instantaneous guillotine pipe break is possible, rather than from a consideration of the manner in which cracks might open or extend in a real piping system. The objective of this study is to help establish the basis for understanding how cracks which might exist in the primary piping of a pressurized water reactor (PWR) would open and extend so that improved criteria can be developed based on this information.One of the regions where loss of pressure boundary integrity must be postulated is the terminal end of the cold leg at the reactor vessel inlet nozzle. This region (including the effects of the reactor vessel and the primary pump) is modelled for analysis with the MARC general purpose finite element program. A circumferential crack, one-half circumference long, is considered to suddenly occur around the outside of the elbow when the pipe is at normal operating pressure. The most severe part of the safe shutdown earthquake (SSE) loading transient is applied simultaneously with the initiation of the crack.The plastic dynamic analysis of the crack opening effects in the discharge leg pipe is performed using the MARC program until the maximum opening occurs. The J-integral plastic crack extension criterion is computed for all times during the transient. The results indicate that none of the cracks will extend significantly and that the opening areas are small fractions of the flow area of the pipe.     

Sensitive radioimmunoassay for digoxin in plasma and urine

A reproducible and sensitive radioimmunoassay for digoxin in either serum, plasma or urine is described. Using 0.5 ml of serum or plasma, the assay sensitivity is 0.05 ng of digoxin/ml. The antiserum and tracer solutions employed are available in a kit sold in the United States. All other reagents were prepared in the laboratory. The assay allows measurement of digoxin in plasma or serum for 96 hours after single 0.5 mg doses of digoxin; this is necessary in human bioavailability studies to accurately estimate the total area under the digoxin concentration, time curve from zero to infinite time. In contrast, with the kit assay, employing 0.2 ml of plasma or serum, it has been reported that the 12 hr serum digoxin levels, after single 0.5 mg doses, are, in most subjects, below the sensitivity limit (about 0.5 ng/ml) of the assay.     

Fluorometric measurement of aflatoxins

An accurate, precise and sensitive fluorometric method for quantifying purified aflatoxins in solution is proposed. After purification, aflatoxin samples are read in a fluorometer with a primary filter of 365 nm and a secondary filter of 435 nm for B₁ and B₂ and 465 nm for G₁ and G₂. The method is precise at as little as 0.0002 μg/ml B₁ and G₁ and 0.00006 μg/ml B₂ and G₂, and accurate at concentrations of 0.002 μg/ml B₁ and G₁ and 0.0006 μg/ml B₂ and G₂. University of Georgia College of Agriculture Experiment stations, Journal Series Paper No. 810, College Station, Athens, Georgia 30601.     

Absorption and distribution of radioactivity from suppositories containing 3H-benzocaine in rats

The effects of the suppository vehicle, drug concentration, and nonionic surfactants on in vitro benzocaine dialysis through a cellulose membrane and on rectal absorption in rats of total radioactivity following administration of 3H-benzocaine were investigated. In vitro dialysis correlated quite well with in vivo absorption, and drug release was greater from water-soluble vehicles than from oleaginous vehicles. Inclusion of a nonionic hydrophilic or lipophilic surfactant in cocoa butter resulted in a statistically significant increase for in vitro drug release, while a lipophilic surfactant showed little effect in vivo and a hydrophilic surfactant depressed release in vivo. Both types of surfactant had small effects on release from polyethylene glycol. In vitro release of benzocaine from some commercially available suppositories was compared with experimental preparations. Variation in blood radioactivity following administration of the same concentration of 3H-benzocaine in the same dosage form in male and female rats is reported.     

Strain and strain-rate hardening effects in punch stretching of 5182-0 aluminum at elevated temperatures

The influences of material properties on stretch forming are often studied by testing a wide variety of materials. However, differences in texture, fracture strain, and crystal structure are not taken into account. These material differences are eliminated in the present study by performing tests on a single material (5182-0 aluminum alloy) in which strain hardening, strain-rate hardening, and limit strain vary in a precise manner with temperature and strain-rate. This allows a comparison to be made between experimental results and analytical calculations to separate the contributions of these two types of hardening in distributing strain during elevated temperature forming. Furthermore, the influence of a change in limit strain to overall formability can be assessed since the hardening phenomenon is better understood. The strain distributions developed during forming over a spherical punch are calculated using the finite element method and material properties obtained from tensile tests at 25, 130, and 200°C at varying strain rates. These are compared to experimental strain distributions over the same temperature range. Measurements of limit strains are taken from forming limit diagrams. This research demonstrates that formability is improved at elevated temperatures through increases in both strain-rate hardening and limit strains.     

Automated enzymatic assays in a renewable fashion using the multisyringe flow injection scheme with soluble enzymes

In this paper, a novel flowing stream scheme based upon the multisyringe flow injection (MSFI) technique is presented as a powerful tool to perform automated enzymatic assays. The exploitation of enzymes in homogeneous phase circumvents typical drawbacks associated with the commonly used packed-bead or open tubular permanent columns, namely, malfunctions of the reactor, carryover effects, flow resistance, loss of binding sites, large reagent consumption, and use of harmful organic solvents during immobilization procedures.The proposed MSFI system is able to handle minute volumes of soluble enzymes and accommodate reactions with divergent kinetic and pH demands, as demonstrated via the indirect chemiluminescence determination of trace levels of glucose. The procedure is based on the on-line glucose oxidase-catalyzed oxidation of beta-glucose in homogeneous phase to beta-glucono-delta-lactone and hydrogen peroxide. Subsequently, the generated oxidant merges downstream with an alkaline slug of 3-aminopthalhydrazide and a metal-catalyst zone (viz., Co(II)) at a total flow rate as high as 72 mL/min aiming to warrant maximum light collection from the fast CL reaction. Under optimum conditions for both sequentially occurring reactions, a glucose concentration as low as 90 microg/L may be easily detected at a 1000-fold photomultiplier gain. A second-order polynomial regression equation of light emission versus substrate concentration is found over the range 90 microg/L-2.7 mg/L glucose, although a maximum concentration of 180 mg/L may be determined by suitable gain selection without requiring manifold reconfiguration. An injection throughput of 20 h(-1), a repeatability better than 2.5% at the 1 mg/L level, and a 3sigma detection limit of 72 microg/L are the analytical features of the designed analyzer. The proposed approach was applied to the analysis of ultralow glucose content soft drinks as well as fruit juices suitable for diabetic consumers. The accuracy was assessed using the spectrophotometric batch glucose-Trinder method as an external reference methodology for the determination of the target species in parenteral solutions.     

Itraconazole formation using supercritical carbon dioxide

A new method of preparing Itraconazole (C₃₅H₃₈Cl₂N₈O₄), a synthetic triazole antifungal agent, was developed using supercritical carbon dioxide (SC CO₂) while eliminating the use of toxic solvents. Dissolution amounts of the product were measured in gastric fluid and compared to those of conventional drug formulations. Different operating conditions (five levels of treatment temperature ranging between 110-140°C, four levels of treatment pressure ranging between 30-400 atm, and four different treatment times ranging from 10-60 minutes) were tested in order to produce a desired Itraconazole product, which does not degrade during the product formation and has the highest extent of dissolution in gastric fluid after one hour. Itraconazole dissolution of 100% at one-hour was achieved for the drug produced at the optimum treatment condition: 135°C, 300 atm, and 30 minutes. Extent of dissolution obtained from this solvent and detergent-free process is 10% higher than that of the conventional method involving toxic organic solvents. Itraconazole produced using SC CO₂ should provide minimal side effects in human body.     

Unbridled Development of Urban Space and its Implications for the Preservation of Landmarks: The Morro da Queimada Archaeological Site, Ouro Preto, Brazil

The process of expansion of urban centers in Brazil has been distinguished by the complete absence of planning. As a result, urban environments lead to land uses encroaching on, defacing and destroying landmarks. Attention is given to the Morro da Queimada Archaelogical Site. This represents an important cultural heritage of the 1720 movement of secession during the gold rush. Several ruins of mining equipments such as houses, wells, shafts and galleries have been gradually destroyed. The process of the site's loss of distinct character has been monitored since 1950 using aerial photographs and cartography. Collected data indicate a conservative annual land-use change rate of about 1.5%. This rate points to the complete destruction of the site in 2008. This paper proposes the creation of the Morro da Queimada Historical Park, within the limits of the remaining set of ruins.