Introduction Aquatic ecosystems have been fertile ground for understanding the extent to which animals can alter nutrient cycling. Although animals have been included in ecosystem models for years (for example, Teal, 1962), it is only more recently that investigators have looked at animals, either as individuals, single species, or assemblages, as agents regulating nutrient cycling (Kitchell et...

in vascular plants, the soil solution is transported from the roots to the leaves through smalldiameter vessels found in the xylem; this transport not only allows the nutrient uptake but also the accumulation of heavy metals in their shoots. by analogy to this phenomenon, the present study aimed at the evaluation of heavy metals transport (pb, cr, as, cd, zn, ni and al) in ph 4 and ph 8 solutio...

in vascular plants, the soil solution is transported from the roots to the leaves through smalldiameter vessels found in the xylem; this transport not only allows the nutrient uptake but also the accumulation of heavy metals in their shoots. by analogy to this phenomenon, the present study aimed at the evaluation of heavy metals transport (pb, cr, as, cd, zn, ni and al) in ph 4 and ph 8 solutio...

the potential sources of cr (vi) are various effluents from metallurgy, electroplating, leather tanning, textile dyeing, paint, ink, and aluminum manufacturing industries. these industrial effluents can contain cr (vi), in the concentration range of 10 to 100 mg/l (nakano et al 2000), which is much higher than the standard limit; 0.5 mg/l in industrial wastewater (epa). in aqueous systems, chro...

This letter is regarding the article by Daoudi et al. entitled "Study of bacterial contamination of mobile phones and stethoscopes in Neonatal Intensive Care Unit" published in International Journal of Pediatrics DOI: 10.22038/IJP.2017.25504.2170 (1). The authors have evaluated the microbial contamination of mobile phones and stethoscopes used by medical and paramedical staff. They reported tha...

Human activities can cause large alterations in biogeochemical cycles of key nutrients such as carbon (C), nitrogen (N), and phosphorus (P). However, relatively little is known about how these changes alter the proportional fluxes of these elements across ecosystem boundaries from rivers to lakes. Here, we examined environmental factors influencing spatial and temporal variation in particulate ...

Tolerancing has great impact on the cost and quality of a product. Dimensional and geometric tolerancing are designed to ensure that products meet both designed functionality and minimum cost. The task of dimensioning and tolerancing in process planning stage is to determine the working dimensions and tolerances of the machined parts by given blueprint (B/P) specifications. A lot of research wo...

The prevalence of obesity in adolescents has increased over the past three decades. Recent evidence has shown that in developed countries, about one in five teens is obese (Abdelghaffar et al., 2020). In Iran, the prevalence of overweight and obesity is 23% (Moghimi-Dehkordi et al., 2020). Improper eating behaviors and obesity are major concerns in adolescence that can be associated with the ri...