Mechanical and Thermal Properties of Bamboo Microfibril Reinforced Polyhydroxybutyrate Biocomposites

In the present investigation, microfibrils were extracted from raw bamboo and characterized using scanning electron microscope. Composites based on polyhydroxybutyrate (PHB) and bamboo microfibril were prepared with various microfibril loading. The mechanical and thermal properties of the resulting composites were measured. Tensile strength and impact strength of the composites were found to be increasing with increase in the loading of bamboo microfibrils, reached an optimum and thereafter decreased with further increase in microfibril loading. Percentage crystallinity was found to be increasing with increase in fibril loading. Thermal stability of the composite was higher than that of pure PHB. The composite could be developed further for various structural applications.     

Heavy metals, polycyclic aromatic hydrocarbons and polychlorinated biphenyls in surface sediments of the Naples harbour (southern Italy)

The Naples's harbour is one of the largest and most important commercial and tourist port of the Mediterranean basin. It is located on the southeast coast of Italy and receives industrial and municipal wastewaters from the city of Naples. Due to its social and economic impact, a comprehensive assessment of levels and sources of contamination of bottom sediments in this area of the Mediterranean basin is essential to identify potential danger due to mobilization of contaminants produced by managing of the same sediments. In this study, superficial sediments collected from 189 sampling sites were analyzed for grain size, heavy metals (Cr, Cu, Ni, Pb, V, Zn, Co, Sn, Cd, Hg, As, Al and Fe), 16 priority polycyclic aromatic hydrocarbons (PAHs) and perylene and 38 individual polychlorinated biphenyl (PCB) congeners. Compared to the estimated local background, Cu, Zn, Pb, Cd, Sn and Hg show enrichment factors >3 and only Hg evidences a median value higher than the NOAA (effects range - median) guidelines. Principal component analysis allowed us to clearly discriminate two areas mainly affected by heavy metals contamination and influenced by different sources related to industrial, commercial and/or urban activities. Priority PAHs are predominantly represented by three-five-ring compounds with concentrations ranging between 9 and 31774 ng g(-1) and frequently higher than the NOAA ER-M index. A prevalent pyrolitic origin of PAH was assessed on the basis of the relative abundance of the different congeners and selected isomer ratios. The concentrations of PCBs, as sum of the 38 congeners, ranged from 1 to 899 ng g(-1), with a predominance of highly chlorinated (tetra- and penta-chlorobiphenyls) congeners. WHO-TEQ values, calculated for the PCDD-like PCB congeners, suggest a relatively high level of toxicity. Generally, the concentration of PAHs and PCBs were higher near the sites of intense industrial, shipping and/or commercial activities suggesting a direct influence of these sources on the pollutant distribution patterns.     

Diffusion of US army chemical weapons disposal technologies: public perception of technology attributes

This study was conducted to identify factors that influence individuals' acceptance of environmental management technologies for cleaning up hazardous materials. The study sample consisted of approximately 2600 residents living within emergency response zones surrounding eight US Army's Chemical Weapons Stockpile sites. The findings suggest that residents perceive clear differences between the desirable characteristics of the two technologies: incineration and neutralization. In a relative comparison, the majority of positive technological attributes were associated with incineration. Positive perceptions toward incineration were associated with individuals who trust the Army, who perceive that the media have made them more trusting of weapons disposal activities, who are ready to participate, and who are male. Unlike incineration, there was insufficient evidence that individual factors influence variations in perceptions toward neutralization. No community factor was related to perceptions toward either incineration or neutralization.     

Effects of the parasiticide ivermectin on the cladoceran Daphnia magna and the green alga Pseudokirchneriella subcapitata

Although widely used for the treatment of endo- and ectoparasites in livestock and pets, very few data on chronic effects on aquatic organisms are available for the parasiticide ivermectin. In the present study, toxicity of ivermectin to two freshwater organisms, the cladoceran Daphnia magna and the green alga Pseudokirchneriella subcapitata was investigated. For D. magna, a mean LC(50) 48 h of 5.7 ngl(-1) was derived from 10 acute tests. Chronic toxicity of ivermectin to D. magna was extremely high: with 0.001 and 0.0003 ngl(-1), respectively, nominal LOEC and NOEC based on growth and reproduction were far below the analytical limit of detection for this compound. P. subcapitata was considerably less sensitive to ivermectin than D. magna. For both growth rate and yield, EC(50) was >4,000 microgl(-1), LOEC was 1,250 microgl(-1) and NOEC 391microgl(-1). In view of the high toxicity to D. magna, the use of ivermectin might pose a risk to local aquatic ecosystems. Further studies should be carried out to investigate the effects of ivermectin and its degradation products on pelagic and benthic freshwater invertebrates.     

Cadmium sorption by sodium and thiourea-modified zeolite-rich tuffs

In the present investigation, two zeolite-rich tuffs from Guaymas and El Cajon(State of Sonora), which were conditioned with a sodium chloride solution and subsequently modified with a thiourea solution, were chosen to evaluate the removal of Cd from aqueous systems. The zeolitic materials were characterized by scanning electron microscopy and X-ray diffraction. The surface area was also determined. The experiments were performed in a batch system, and the influences of p H, contact time between phases, and the concentration of Cd in the solution on the adsorption by sodium or thiourea-modified zeolite-rich tuff were investigated. It was found that the efficiency of Cd ion removal from aqueous solutions is influenced by the p H of the aqueous systems. The Cd adsorption kinetic data were well fitted to a pseudo-second-order model in all cases. The Langmuir and Langmuir–Freundlich isotherms adequately described the Cd sorption behavior by the zeolite from El Cajon pretreated with Na Cl and the zeolite from Guaymas modified with thiourea, respectively.     

Stable oligonucleotide-functionalized gold nanosensors for environmental biocontaminant monitoring

The global propagation of environmental biocontaminants such as antibiotic resistant pathogens and their antibiotic resistance genes(ARGs) is a public health concern that highlights the need for improved monitoring strategies. Here, we demonstrate the environmental stability and applicability of an oligonucleotide-functionalized gold nanosensor. The mec A ARG was targeted as model biocontaminant due to its presence in clinically-relevant pathogens and to its emergence as an environmental contaminant.mec A-specific nanosensors were tested for antibiotic resistance gene(ARG) detection in ARG-spiked effluent from four wastewater treatment plants(WWTPs). The mec A-specific nanosensors showed stability in environmental conditions and in high ionic strength([MgCl_2] 50 m M), and high selectivity against mismatched targets. Spectrophotometric detection was reproducible with an LOD of 70 pM(≈ 4 × 10~7 genes/μL), even in the presence of interferences associated with non-target genomic DNA and complex WWTP effluent. This contribution supports the environmental applicability of a new line of cost-effective, field-deployable tools needed for wide-scale biocontaminant monitoring.     

Was endothermy in amniotes induced by an early stop in growth during ontogeny?

Endothermy and its evolution are still an unresolved issue. Here, we present a model which transforms an ectothermic amniote (ancestor) into a derived amniote (descendant) showing many characteristics seen in extant endothermic birds and mammals. Consistent with the fossil record within the ancestral lineages of birds and mammals, the model assumes that mutations in genes which get active during ontogeny and affect body growth resulted in a reduced asymptotic body size and an early growth stop of the descendant. We show that such a postulated early growth stop in the descendant simultaneously increases the growth rate and metabolic rate, and also changes six life history traits (offspring mass, annual clutch/litter mass, number of offspring per year, age and mass at which sexual maturity is reached, age at which the individual is fully grown) of the descendant compared to a similar-sized ancestor. All these changes coincide with known differences between recent ectothermic and endothermic amniotes. We also elaborate many other differences and similarities in biological characteristics supporting the early growth stop. An early stop in growth during ontogeny thus could have played a key role in the evolution of endothermy within the reptilia and therapsids. It generated variability in characteristics of ancestral ectotherms, which was subject to natural selection in the past and resulted in many adaptations linked to endothermy in today’s birds and mammals.