Regeneration of used sand with sodium silicate binder by wet method and their core manufacturing

Journal of Material Cycles and Waste Management - Organic binders that are used in sand casting emit high amounts of hazardous pollutants and volatile organic compounds during the casting process....     

Exposure assessment of particulate matter and blood chromium levels in people living near a cement plant

This study evaluates the effect of air pollution caused by cement plants on nearby residential areas and performs an exposure assessment of particulate matter (PM) and total Cr, Cr⁶⁺, Pb, and Al. Further, the blood Cr levels of residents exposed to PM released by cement plants are also assessed. Nine buildings (eight residential and one elementary school building) close to cement plants were selected for this study, which were located in Pyeongtaek port, in west of Gyeonggi Province, South Korea. A total of 51 suspended particulate samples were collected at a flow rate of 2.0 L/min. Total Cr was more widely detected in residents’ houses and elementary schools. PM levels were higher at distances of 4.1 and 4.8 km than those at closer distances of 2.7 km. This was due to the influence of wind direction. The estimated mean blood level of Cr for the study participants was 3.80 μg/L, which is higher than levels estimated by other studies on Cr blood levels. Therefore, cement plants could cause an increase in total Cr and blood Cr levels in residential areas, and more continuous monitoring is necessary to better understand their impacts.     

Functional values of stabilimenta in a wasp spider, Argiope bruennichi: support for the prey-attraction hypothesis

Many orb-weaving spiders decorate their webs with conspicuous ultraviolet (UV)-reflective stabilimenta. The prey-attraction hypothesis suggests that stabilimenta are visually attractive to prey and thus may increase the spiders’ foraging success. However, previous studies on the function of stabilimenta have produced conflicting results in Argiope species. Using a combination of field and laboratory studies, we examined whether the linear stabilimentum of Argiope bruennichi contributes to prey interception. We recorded prey interceptions in 53 webs with stabilimenta and 37 equally-sized webs without stabilimenta, classifying captured prey according to their taxonomical group and size. On average, 6.2?±?4.7 prey items were intercepted in webs with stabilimenta, while 3.2?±?2.9 items were intercepted in webs without stabilimenta. The effects of stabilimenta on foraging success appear to be due to increased interception of UV-sensitive insect pollinators, including 20 families of Diptera, Hymenoptera, Coleoptera, and Lepidoptera. The mean number of UV-sensitive prey was 4.4?±?3.6 in webs with stabilimenta compared with 1.8?±?2.1 in webs without stabilimenta. Webs with and without stabilimenta did not differ in the mean number of UV-nonsensitive prey captured. The linear stabilimentum showed strong positive effects on the interception of large prey: webs with stabilimenta captured more than twice as many large prey (≥5?mm) than webs without stabilimenta, whereas there was only a slight difference in the interception rates for small prey (<5?mm). Comparisons among different Argiope species suggest that the stabilimentum may have different adaptive functions in different species or ecological contexts.     

Comparative study of torrefaction of empty fruit bunches and palm kernel shell

Journal of Material Cycles and Waste Management - This paper describes the effect of torrefaction on the characteristics of empty fruit bunches (EFB) and palm kernel shell (PKS). The torrefaction...     

Impact of natural and calcined starfish (<Emphasis Type="Italic">Asterina pectinifera</Emphasis>) on the stabilization of Pb,Zn and As in contaminated agricultural soil

Metal stabilization using soil amendments is an extensively applied, economically viable and environmentally friendly remediation technique. The stabilization of Pb, Zn and As in contaminated soils was evaluated using natural starfish (NSF) and calcined starfish (CSF) wastes at different application rates (0, 2.5, 5.0 and 10.0 wt%). An incubation study was conducted over 14 months, and the efficiency of stabilization for Pb, Zn and As in soil was evaluated by the toxicity characteristic leaching procedure (TCLP) test. The TCLP-extractable Pb was reduced by 76.3–100 and 91.2–100 % in soil treated with NSF and CSF, respectively. The TCLP-extractable Zn was also reduced by 89.8–100 and 93.2–100 % in soil treated with NSF and CSF, respectively. These reductions could be associated with the increased metal adsorption and the formation of insoluble metal precipitates due to increased soil pH following application of the amendments. However, the TCLP-extractable As was increased in the soil treated with NSF, possibly due to the competitive adsorption of phosphorous. In contrast, the TCLP-extractable As in the 10 % CSF treatment was not detectable because insoluble Ca–As compounds might be formed at high pH values. Thermodynamic modeling by visual MINTEQ predicted the formation of ettringite (Ca₆Al₂(SO₄)₃(OH)₁₂·26H₂O) and portlandite (Ca(OH)₂) in the 10 % CSF-treated soil, while SEM–EDS analysis confirmed the needle-like structure of ettringite in which Pb was incorporated and stabilized in the 10 % CSF treatment.     

Enhanced anaerobic biodegradability and inactivation of fecal coliforms and Salmonella spp. in wastewater sludge by using microwaves.

During continuous operation of three mesophilic-anaerobic digesters, the effect of microwave irradiation, as sludge thermal pretreatment (60 to 65 degrees C), was studied. The fecal coliforms log inactivation for microwaved/digested sludge was 4.2 +/- 0.4, whereas for conventionally heated/digested sludge and control were 2.9 +/- 0.5 and 1.5 +/- 0.5, respectively. In the case of Salmonella spp., no colonies were detected in 85% of the microwaved/digested samples. Considering the detection limit, the log inactivation of these samples was greater than 2.0 +/- 0.3. The conventionally heated/digested sludge and control showed log inactivations of 1.9 +/- 0.2 and 1.1 +/- 0.3, respectively. At the 95% confidence level, microwaved/digested sludge increased the biogas production by 16.4 +/- 5.6% and 6.3 +/- 2.4%, as compared to control and conventionally heated/digested sludge, respectively. When thermally treated sludge was analyzed for soluble chemical oxygen demand, microwaved waste-activated sludge showed considerable solubilization between 37 and 60 degrees C. Microwaved/digested sludge showed a reduction of capillary suction times by 11.1 +/- 5.9% and 10.7 +/- 5.6%, as compared to control and conventionally heated/digested sludge, respectively.     

Sexual selection and mating system in Zorotypus gurneyi Choe (Insecta: Zoraptera)

Body size is clearly an important factor influencing the outcome of agonistic contests, but is often weakly correlated with dominance ranks in Zorotypus gurneyi Choe (Insecta: Zoraptera). The study of the development and dynamics of dominance relations using artificially constructed colonies show that age, or tenure within the colony, is the prime determinant of dominance among males. Dominance hierarchies become relatively stable within 2 or 3 days and males that emerge later normally begin at the bottom of the hierarchy regardless of size. Males interact much more frequently when they are simultaneously introduced to each other than when they are allowed to emerge at different times. In the latter case, males that emerge late appear to recognize relative dominance of older males and avoid direct contests. Considering the high correlation between dominance rank and mating success, there is a strong selective advantage to males that emerge earlier and such pressure of sexual selection may be responsible for the difference in life history strategies between Z. gurneyi and its sympatric congener, Z. barberi Gurney, in central Panama.     

Investigation of heavy metal accumulation in Polygonum thunbergii for phytoextraction

In this study, cadmium (II), lead (II), copper (II) and zinc (II) were determined in Polygonum thunbergii and soil from the Mankyung River watershed, Korea. Soil samples contained detectable lead (<17.5 g g(-1)), copper (<8.4 g g(-1)) and zinc (<24.5 g g(-1)), whereas cadmium was undetectable. Whole plants of P. thunbergii contained detectable lead (<320.8 g g(-1)), copper (<863.2 g g(-1)) and zinc (<2427.3 g g(-1)), whereas cadmium was detectable only in the stem (<7.4 g g(-1)) and root (<10.1 g g(-1)). Whole plant concentrations were very different for each metal, particularly in the case of zinc. The mean content of heavy metal in the whole plants increased in the order of cadmium (8.5 g g(-1))相似文献   

Sexual selection and mating system in Zorotypus gurneyi Choe (Insecta : Zoraptera)

Summary Social behavior of a species in the little-known insect order Zoraptera is described for the first time. Zorotypus gurneyi Choe (Insecta: Zoraptera) is a wing-dimorphic species that lives colonially under the bark of rotting logs in central Panama. Males are larger than females in total body size and fight each other to gain access to females. Highly linear and stable dominance hierarchies exist among males. Higher-ranking males show such agonistic behavior as jerking, chasing, head-butting, hindleg-kicking, and grappling, whereas subordinates often try to avoid contacts. Higher-ranking males, the dominant males in particular, are well recognized by others and relatively free of injuries. Although the dominant males are often the largest, the correlation between body size and dominance rank is not always significant. The mating system of Z. gurneyi is an example of female defense polygyny in which the dominant males obtain the majority of matings (75% on average). Mating success among Z. gurneyi males is much more variable than that of some lekking species.     

Cooperative prey capture by young subsocial spiders

Matriphagous young of a subsocial spider Amaurobius ferox exhibit collective predation during their post-maternal social period. In this paper, we examine functional mechanisms of collective predation by sibling groups. Predation efficiency increased with increasing number of individuals within each group. Solitary or paired individuals were generally unable to capture a 20 mg cricket. In larger groups, more individuals participated and captured the prey more quickly. Some siblings did not take part in paralyzing prey, but later consumed it. The proportion of these profiteers within a group increased with the group size. Presented with prey of different sizes (1, 5, or 40 mg), siblings were most aggressive towards each other when predating on 5 mg prey. Prey of this size could be captured by a single individual and yet were sufficiently large for more than one individual to eat. Siblings were much less aggressive towards one another during the capture of 40 mg prey, which require the assistance of other individuals to capture. By providing the same mass of prey in different numbers of individuals (a single cricket of 40 or 40 mg of first-instar crickets), we tested the influence of cooperation on the post-maternal social period. We found no difference in the development of young during the social period nor the timing of dispersal and the body mass of dispersing individuals. We conclude that the young of this subsocial animal increased predation efficiency by cooperative hunting after the mother's death.