Incidence and estimation of chitinase activity associated with marine fish and other estuarine samples

A procedure for the determination of chitinase activity was adapted for the seawater environment. Preliminary data indicate that the controlled bacterial environment within the digestive tracts of marine fishes and possibly other marine animals plays a significant role in the decomposition and recycling of chitin. It is estimated in the stomachs of a single population of Enophrys bison (buffalo sculpin) of 1×10⁵ fish that ca. 16 metric tons of chitin could be decomposed annually.Published as Technical Paper No. 4434, Oregon Agricultural Experiment Station. This research was supported by NIH training grant 5TO1 GM-00704 and NSF grant DES73-06611 AO2.     

Detection of a carcinogen, 2-amino-1-methyl-6-phenylimidazo [4,5-b]pyridine, in airborne particles and diesel-exhaust particles

A carcinogen, 2-amino-1-methyl-6-phenylimidazo [4,5-b]-pyridine (PhIP), has been measured in airborne particles, diesel-exhaust particles, and incineration ash from garbage-burning plants. PhIP was found in all kinds of samples. In the light of the present results, together with the previous findings that PhIP was present in cooked foods and cigarette smoke, PhIP is likely to be an ubiquitous environmental pollutant. These observations also suggest that PhIP may be formed through the combustion process.     

Salinity and nutrient effects on the induction of the galactose permease system in a psychrophilic marine vibrio

An Antarctic psychrophilic marine Vibrio species was isolated having the inducible ability to accumulate nonmetabolizable thiomethyl-14C--galactopyranoside (14C-TMG) through a galactose permease system. Induction of 14C-TMG uptake was found to have a salinity requirement which was higher than that required for uptake. At the optimum salinity, galactose and fucose were the primary inducers. Lactose produced a comparable induction but only at higher concentrations, whereas glucose did not cause induction. The initial rate of 14C-TMG uptake exhibited saturation kinetics with an apparent Km value of 4.8 x 10^–6M. An amino acid, in addition to the inducer, was required for induction which could not be replaced by glycerol or galactose. Evidence is presented which indicates that the uptake of 14C-TMG is energy-dependent and that nutrient availability is more important than salinity for induction and uptake under conditions which would normally be found in the oceanic environment.Technical Paper No. 4911, Oregon Agricultural Experiment Station.     

Genetic differences in the production of male neonates in Daphnia magna exposed to juvenile hormone analogs

We studied the susceptibility of three genetically different strains of the cyclical parthenogen Daphnia magna (Cladocera, Crustacea) in producing male neonates following exposure to juvenile hormone analogs. In experiment 1, NIES, Clone A, and Belgium A strains were exposed to the insect growth regulators (IGRs) fenoxycarb or epofenonane in a 21-day reproduction experiment. Fenoxycarb exposure decreased the total number of neonates and increased production of male neonates in a concentration-dependent manner in the NIES strain. The decrease in the total number of neonates was so great in Clone A following fenoxycarb exposure that male neonates were not observed, even at the highest concentration, where the total number of neonates was only 2% of the control. In the Belgium A strain, male neonates were observed at a rate of about 20% following exposure to the highest fenoxycarb concentration, but the total number observed was small. Epofenonane did not decrease reproduction in the NIES and Belgium A strains as dramatically as did fenoxycarb, but the neonatal sex ratio changed in a concentration-dependent manner. Although the ratio of males was as low as about 10%, induction of male neonates was also observed in Clone A following epofenonane exposure. In experiment 2, gravid females were exposed to high concentrations (5 or 10 microg/l) of fenoxycarb or pyriproxyfen for 12h. These treatments induced the production of male neonates in all strains, with a small decrease in the total number of neonates. Although induction of male neonates by juvenile hormones and their analogs was universal among genetically different strains, care is needed in interpreting the results of the 21-day reproduction tests, because decreased numbers of neonates at higher concentrations could obscure the presence of male neonates.     

Production of male neonates in Daphnia magna (Cladocera, Crustacea) exposed to juvenile hormones and their analogs

We exposed the water flea Daphnia magna (Cladocera, Crustacea) to either juvenile hormone I (JH I), juvenile hormone II (JH II), or the juvenile hormone-mimicking insecticides kinoprene, hydroprene, epofenonane, or fenoxycarb. By 21-day reproduction tests, we investigated the effects on the number of neonates born per female and the offspring sex ratio. All six chemicals induced D. magna to produce male neonates; the male sex ratio of the offspring increased as the chemical concentration increased. EC50 values for production of male neonates were estimated as 400 (JH I), 410 (JH II), 190 (kinoprene), 2.9 (hydroprene), 64 (epofenonane), and 0.92 (fenoxycarb) microg/l. The number of neonates produced was reduced with all chemicals at the concentrations investigated. At the EC50 for male production, five of the six chemicals reduced the reproductive rate to less than 50%; the exception was epofenonane, which caused only a slight reduction in reproductive rate. These results were similar to those obtained for five juvenoids studied previously, one of which was studied here again. There are now 10 chemical substances--all juvenile hormones or their analogs-that are known to induce D. magna to produce male neonates. This suggests that juvenile hormone is involved in initiating male production followed by sexual reproduction in D. magna, and probably in most cladocerans that exhibit cyclic parthenogenesis.     

Alkaline hydrolysis of photovoltaic backsheet containing PET and PVDF for the recycling of PVDF

Recovering fluorine from end-of-life products is crucial for the sustainable production and consumption of fluorine-containing compounds because fluorspar, an important natural resource for fluorine, is currently at a supply risk. In this study, we investigated the feasibility of chemically recycling a fluorine-containing photovoltaic (PV) backsheet for fluoropolymer recycling. Herein, a PV backsheet consisting of laminated polyethylene terephthalate (PET) and polyvinylidene fluoride (PVDF) was treated with different concentrations of sodium hydroxide (NaOH) to hydrolyze the PET layer to water-soluble sodium terephthalate (Na₂TP) and to separate pure PVDF layer as a solid material. Optimized alkaline conditions (up to 10 M NaOH at 100 °C for 2 h) were determined, under which 87% of the PET layer could be decomposed without any significant deterioration of the PVDF layer. The hydrolysis kinetics of PET layer in NaOH could be explained by the modified shrinking-core model. Considering that the mass of end-of-life PV panels in Japan is estimated to increase to approximately 280,000 tons per year by 2036, PV backsheets are attractive candidates for fluoropolymer recycling, which can be effectively achieved using chemical recycling approach demonstrated in this study.

     

Mechanical properties of steel slag replaced mineral aggregate for road base/sub-base application based Vietnam and Japan standard

Steelmaking slag is one of the most massive industrial by-products generated during steelmaking processes. This paper presents the current steelmaking slag production status and its potential to use as mineral aggregates in base/sub-base layer of road pavement. The mechanical properties of steelmaking slag were confirmed by the test method specified in Vietnam specification. The volume stability test of the slag was conducted based on JIS A 5015-2018 (Japanese Industrial Standard: Iron and steel slag for road construction). From the results, it was confirmed that steelmaking slag can satisfy all the mechanical requirements specified in Vietnam specification and the requirements regarding stability specified in JIS A 5015-2018. In addition, it was found that the elastic modulus of steelmaking slag applied as a base or sub-base layer in pavement was higher than that of the conventional graded aggregate made from mineral aggregate. Therefore, the thickness of pavement can be reduced by using steelmaking slag, and the construction cost can be lower.