Recycling WEEE: Polymer characterization and pyrolysis study for waste of crystalline silicon photovoltaic modules

Photovoltaic (PV) modules contain both valuable and hazardous materials, which makes its recycling meaningful economically and environmentally. In general, the recycling of PV modules starts with the removal of the polymeric ethylene-vinyl acetate (EVA) resin using pyrolysis, which assists in the recovery of materials such as silicon, copper and silver. The pyrolysis implementation, however, needs improvement given its importance. In this study, the polymers in the PV modules were characterized by Fourier transform infrared spectroscopy (FTIR) and the removal of the EVA resin using pyrolysis has been studied and optimized. The results revealed that 30min pyrolysis at 500°C removes >99% of the polymers present in photovoltaic modules. Moreover, the behavior of different particle size milled modules during the pyrolysis process was evaluated. It is shown that polymeric materials tend to remain at a larger particle size and thus, this fraction has the greatest mass loss during pyrolysis. A thermo gravimetric analysis (TGA) performed in all polymeric matter revealed the optimum pyrolysis temperature is around 500°C. Temperatures above 500°C continue to degrade matter, but mass loss rate is 6.25 times smaller. This study demonstrates the use of pyrolysis can remove >99% of the polymeric matter from PV modules, which assists the recycling of this hazardous waste and avoids its disposal.

Recycling WEEE: Extraction and concentration of silver from waste crystalline silicon photovoltaic modules

Photovoltaic modules (or panels) are important power generators with limited lifespans. The modules contain known pollutants and valuable materials such as silicon, silver, copper, aluminum and glass. Thus, recycling such waste is of great importance. To date, there have been few published studies on recycling silver from silicon photovoltaic panels, even though silicon technology represents the majority of the photovoltaic market. In this study, the extraction of silver from waste modules is justified and evaluated. It is shown that the silver content in crystalline silicon photovoltaic modules reaches 600g/t. Moreover, two methods to concentrate silver from waste modules were studied, and the use of pyrolysis was evaluated. In the first method, the modules were milled, sieved and leached in 64% nitric acid solution with 99% sodium chloride; the silver concentration yield was 94%. In the second method, photovoltaic modules were milled, sieved, subjected to pyrolysis at 500°C and leached in 64% nitric acid solution with 99% sodium chloride; the silver concentration yield was 92%. The first method is preferred as it consumes less energy and presents a higher yield of silver. This study shows that the use of pyrolysis does not assist in the extraction of silver, as the yield was similar for both methods with and without pyrolysis.

Brown seaweed- (Tasco) treated conserved forage enhances antioxidant status and immune function in heat-stressed wether lambs

Twenty-seven wether lambs were utilized to evaluate select innate immunity and oxidative stress in response to diet and heat stress. Dietary treatments were: (i) control (tall fescue) hay = no Tasco (tradename for the extract of the brown seaweed, Ascophyllum nodosum, Acadian Sealants Ltd, Nova Scotia, Canada); (ii) pre-harvest Tasco-Forage-treated hay and (iii) control hay + post-harvest Tasco-EX. Tasco-Forage and Tasco-EX are two forms of the Tasco extract that are either applied to foliage or used for direct feeding, respectively. All lambs were supplemented with soyabean meal and trace mineralized salt. Heat stress was applied for 10 days with measurements obtained at days 0, 4 and 10. A heat x treatment interaction indicated hay with Tasco enhanced monocyte oxidative burst through short duration (p < 0.05) and long duration (p < 0.10) heat stress. Phagocytic activity was influenced by days of heat stress (p < 0.001) and treatment (p = 0.02) with post-harvest Tasco lambs exhibiting the greatest immune enhancement (p < 0.05). Red and white blood cell glutathione peroxidase increased by heat stress day 10 in Tasco lambs. Superoxide dismutase activity was increased and lipid hydroperoxide metabolites minimized (p < 0.01) through long duration heat stress in the pre-harvest Tasco group. Tasco treatment of tall fescue hay prior to harvest appears to provide residual effects on animal antioxidant availability in short-duration heat stress. Tasco supplementation to post-harvest fescue hay enhances immune function and protects against prolonged heat-induced oxidative stress.

Dietary boron supplementation enhances the effects of estrogen on bone mineral balance in ovariectomized rats

The present study investigated whether boron would enhance the action of 17beta-estradiol (E2) or parathyroid hormone (PTH) on bone mineral balance in ovariectomized (OVX) rats. Forty-three days after OVX, the rats were treated for 5 wk with vehicle, boron (5 ppm as boric acid), E2 (30 microg/kg/d, sc), PTH (60 microg/kg/d, sc), or a combination of boron and E2 or PTH. Bone mineral balance was assessed by measuring apparent absorption, excretion, and retention of calcium (Ca), phosphorus (P), and magnesium (Mg). Serum Ca, P, Mg, and osteocalcin were also measured in this experiment. Boron alone had no effects on food consumption, weight gain, bone mineral balance, and serum levels of Ca, P, Mg, and osteocalcin. E2 alone increased serum P and Mg and decreased serum osteocalcin, but it had no effect on bone mineral balance. The combination of boron and E2 markedly improved apparent absorption of Ca, P, and Mg. In addition, the combination treatment increased the apparent retention of Ca and Mg (but not P) and also increased serum Ca and Mg but not serum P. On the other hand, boron cotreatment did not prevent the E2-induced reduction in serum osteocalcin in OVX rats. PTH alone significantly increased serum Ca, P, Mg, and osteocalcin concentrations, although it had no effect on bone mineral balance. Contrary to the boron-E2 combination treatment, the combination of boron and PTH did not enhance bone mineral balance. However, inasmuch as boron-PTH cotreatment did not enhance the stimulatory action of PTH on serum Ca, P, and osteocalcin, boron completely abolished the stimulatory effect of PTH on serum Mg. In conclusion, we have demonstrated for the first time that although boron by itself has no effect on bone mineral homeostasis, it appears to have synergistic enhancing effects on the action of E2 on Ca and Mg homeostasis in OVX rats.

Dietary boron supplementation enhanced the action of estrogen, but not that of parathyroid hormone, to improve trabecular bone quality in ovariectomized rats

This study investigated whether boron would enhance the ability of 17beta-estradiol (E2) or parathyroid hormone (PTH) to improve bone quality in ovariectomized OVX rats. Adult OVX rats were treated for 5 wk with vehicle, boron (5 ppm as boric acid), E2 (30 microg/kg/d, sc), PTH (60 microg/kg/d, sc), or a combination of boron and E2 or PTH, respectively. The E2 treatment corrected many adverse effects of OVX on bone quality, increased bone Ca, P, and Mg contents, and decreased trabecular plate separation. Dietary boron supplementation had no effects on these bone parameters in OVX rats. When OVX rats were treated with boron and E2 together, trabecular bone volume (Tb.BS/TV) and plate density were increased significantly more than that caused by E2 alone. The boron and E2 combination also increased trabecular bone surface (Tb.BV/TV) and decreased trabecular plate separation in OVX rats. In contrast, whereas daily PTH injection also increased bone Ca, Mg, and P contents, Tb.BV/TV, Tb.BS/TV, trabecular plate density and thickness, and decreased trabecular plate separation in OVX rats, the combination of boron and PTH had no additional improvement in bone quality over that achieved by PTH alone. In summary, this study shows for the first time that boron enhanced the action of E2, but not that of PTH, to improve trabecular bone quality in OVX rats.

Reaction of the avian respiratory system to intratracheally administered avirulent Salmonella typhimurium

Chickens were inoculated intratracheally (IT) with the SR-11 Salmonella typhimurium deletion mutant x4062 strain. Data collected for 8 days postinoculation (PI) were: signs of respiratory and gastrointestinal disease; histological lesions; the influx, phagocytic proportion, and phagocytic capacity of avian respiratory phagocytes (ARPs); and the proportion of granulocytes vs. macrophages in the lung tissues and lavage fluids of the lungs and air sacs. S. typhimurium-inoculated chickens had no clinical signs of gastrointestinal or respiratory disease but had various degrees of inflammatory changes in the lungs. At 5 hr PI, S. typhimurium-inoculated chickens had approximately 53-fold more ARPs than mock-inoculated controls. Between 26 hr and 8 days PI, the number of ARPs from S. typhimurium-inoculated birds was not significantly higher than the number from the mock-inoculated controls. Flow cytometric analysis of ARPs demonstrated that the proportion of phagocytic ARPs and the phagocytic capacity of ARPs from S. typhimurium-inoculated chickens were significantly higher between 5 and 26 hr PI than those of the ARPs from mock-inoculated chickens. Kinetic changes over 8 days in the granulocyte/macrophage ratios in the lavage fluids, as compared with kinetic changes in the lung tissues, suggested that the granulocytes generally represent a much higher proportion of the ARPs, and egress earlier and in much larger numbers from the tissues to the lumen of lungs and air sacs than do macrophages.

Characterization of a non-hemolytic mutant of Actinobacillus pleuropneumoniae serotype 5: role of the 110 kilodalton hemolysin in virulence and immunoprotection

To determine the role of hemolysin(s) in virulence and immunoprotection, non-hemolytic mutants of Actinobacillus pleuropneumoniae serotype 5, strain J45, were isolated following chemical mutagenesis. One mutant was selected for extensive characterization. Differences in capsule content, or in lipopolysaccharide or membrane protein electrophoretic profiles of the parent and mutant were not detected. A predominant, calcium-inducible protein of 110 kDa was present in culture supernatant of the parent, but absent from the mutant. Two-dimensional (2-D) gel electrophoresis confirmed that the 110 kDa protein was absent in culture supernatant of the mutant, but few, if any, minor differences could be detected in whole-cell proteins between the parent and mutant. The mutant totally lacked extracellular hemolytic and cytotoxic activity. Lysates of whole cells of the mutant contained weak hemolytic activity, and the 110 kDa protein could be detected by immunoblotting. Neutralization titers were negative in pigs immunized with the mutant or purified, denatured hemolysin, although enzyme-immunoassay titers were detected. Four additional independently isolated non-hemolytic mutants were avirulent in pigs and mice at doses greater than 10 times the lethal dose of the parent. Neither pigs nor mice were protected against lethal infection following immunization with the non-hemolytic mutant. We conclude that the 110 kDa hemolysin plays an important role in bacterial virulence and the pathogenesis of pleuropneumonia, and that sufficiently high levels of neutralizing antibodies to the 110 kDa hemolysin may be required for protection of pigs against disease.

Cellular defense of the avian respiratory system: protection against Escherichia coli airsacculitis by Pasteurella multocida-activated respiratory phagocytes

The concept of nonspecific cellular defense of the respiratory system of poultry against respiratory pathogens by "preventive activation" of avian respiratory phagocytes (ARPs) was tested in an in vivo protection trial. Chickens were stimulated intratracheally by Pasteurella multocida Choloral vaccine strain. Seven hours later, these and mock-inoculated control chickens were challenged with pathogenic Escherichia coli via the air-sac route. Stimulated chickens had a 25-fold-elevated number of ARPs compared with mock-inoculated control chickens. The proportion of active phagocytes and the phagocytic capacity of these cells was higher in the ARP populations of stimulated chickens than in the ARP populations of control chickens. In vivo protection against E. coli air-sac infection was demonstrated by reduction of morbidity and mortality rates, diminished weight loss, and lower scores of gross and histopathological lesions of P. multocida-stimulated chickens compared with mock-inoculated controls.

Cellular defense of the avian respiratory system. Influx of phagocytes: elicitation versus activation

We studied various means of inducing avian phagocytes to migrate to the respiratory tract. No significant and consistent increases in the number of avian respiratory phagocytes (ARP) were elicited by intravenous inoculation with Escherichia coli lipopolysaccharide (LPS), Saccharomyces cerevisiae glucan (G), and Freund's incomplete adjuvant (FIA) in a water-in-oil-in-water emulsion; subcutaneous inoculation with the LPS-G-FIA homogenate; or aerosolized exposure to LPS-G-FIA, thioglycolate, and proteose-peptone. Intravenous inoculation with heat-killed Corynebacterium parvum resulted in a significant increase in the number of ARP by day 6 after inoculation; intratracheal inoculation of C. parvum effected a more rapid and higher level of phagocyte migration to the respiratory tract. Intratracheally administered E. coli induced significant migration of phagocytes to the respiratory system so that by 24 hours postinoculation, the group average number of ARP was about 50-100 times as high as the number in unstimulated control birds. None of the birds yielding high numbers of phagocytes from their respiratory tract had signs of respiratory disease.

Trisomy 9p resulting from de novo 9/15 translocation and a 9p isochromosome

Trisomy 9p with de novo 9/15 translocation and 9p isochromosome was observed in a mentally defective boy with typical clinical features for this syndrome. This chromosomal aberration is probably caused by the pericentric inversion of chromosome 9 of the patient's father.