Heavy metal distribution in a sediment phytoremediation system at pilot scale

The continuous stream of polluted sediments, dredged from harbors and water bodies in order to maintain the navigation, is a common practice, but the fate of these sediments is an issue recognized worldwide. This pilot case study evaluated the application of phytoremediation as sustainable management strategy for the decontamination of polluted dredged marine sediments. The synergic action of different plant species (Paspalum vaginatum; P. vaginatum + Spartium junceum and P. vaginatum + Tamarix gallica) and organic matter (compost) in removing both heavy metals (Cd, Ni, Zn, Pb and Cu) and total petroleum hydrocarbons, and in recovering the nutritive and biological sediment properties were evaluated. In addition to the detection of total metal removal efficiency, the chemical distribution of metals in the sediment phases (exchangeable, manganese and iron oxides, organic matter and residual minerals) was also measured in order to make a more realistic estimation of the phytoremediation efficiency for the sediment decontamination. Finally, a complete picture of the metal flux was obtained by investigating the metal mass-balance in the treated sediments. The results of metal content in the sediment phases showed that metal distribution was not uniform and each metal predominated in different fractions; the solubility of metals in the sediment in the decreasing order was: Cd>Zn>Cu>Pb>Ni. The higher proportion of Ni and Pb in the residual phase can be the reason of the lower translocation of these metals in the plant tissues. On the other hand, Cd, Zn and Cu were the metals most easily translocated in plant tissues, both aboveground and roots, confirming their higher availability for the plants. The results of mass balance indicated that, at the end of the experimentation, a high content of metals were still found in the sediment. The greatest contribution in metal removal was attributed to a phytostabilization process at rhizosphere level followed by gravel and sand absorption. The capacity of rhizophere to precipitate heavy metals, could be considered as an alternative option for reducing the metal availability and, consequently, the toxicity in contaminated sediments

Kinetic theory of age-structured stochastic birth-death processes

Classical age-structured mass-action models such as the McKendrick-von Foerster equation have been extensively studied but are unable to describe stochastic fluctuations or population-size-dependent birth and death rates. Stochastic theories that treat semi-Markov age-dependent processes using, e.g., the Bellman-Harris equation do not resolve a population's age structure and are unable to quantify population-size dependencies. Conversely, current theories that include size-dependent population dynamics (e.g., mathematical models that include carrying capacity such as the logistic equation) cannot be easily extended to take into account age-dependent birth and death rates. In this paper, we present a systematic derivation of a new, fully stochastic kinetic theory for interacting age-structured populations. By defining multiparticle probability density functions, we derive a hierarchy of kinetic equations for the stochastic evolution of an aging population undergoing birth and death. We show that the fully stochastic age-dependent birth-death process precludes factorization of the corresponding probability densities, which then must be solved by using a Bogoliubov-–Born–-Green–-Kirkwood-–Yvon-like hierarchy. Explicit solutions are derived in three limits: no birth, no death, and steady state. These are then compared with their corresponding mean-field results. Our results generalize both deterministic models and existing master equation approaches by providing an intuitive and efficient way to simultaneously model age- and population-dependent stochastic dynamics applicable to the study of demography, stem cell dynamics, and disease evolution

Muscoloskeletal disorders and occupational stress of violinists

Although musculoskeletal disorders are the most frequent cause of occupational diseases in musicians, very few studies have focused attention on a single category of instruments, in particular on the violin. This involves, in its practice, almost all the areas of the body, besides being in the category of strings which is the most numerous in an orchestra. A specific protocol, investigating postural and clinical profiles of the muskoloskeletal apparatus as well as job stress, was utilized in a conservatory on graduates in the tenth year of violin study, who regularly participated in activities of orchestras or string quartets. The investigation revealed “target segments” of osteoarticular apparatus (jaw, vertebral spine, shoulders, elbows, hands and fingers, lower limbs) electively subjected to overuse, as well as muscle contracture of trapezoids and hyperkeratosis of fingers and clavicle. Although the work environment was comfortable, most violinists claimed to undergo intense rhythms and competitiveness. This study, highlighting sublinical occupational diseases in young musicians (violinists) suggests adequate prevention measures

Polyacetylenes Bearing Chiral-Substituted Fluorene and Terfluorene Pendant Groups: Synthesis and Properties

The synthesis of the first polyacetylenes bearing chiral fluorene-based pendant groups is described. Poly{9,9-bis[(S)-3,7-dimethyloctyl]fluoren-2-ylacetylene} (PFA1), poly{9,9-bis[(S)-2-methylbutyl]- fluoren-2-ylacetylene} (PFA2), and poly{9,9,9′,9′,9′′,9′′-hexakis[(S)-2-methylbutyl]-7,2′;7′,2′′-terfluoren- 2-ylacetylene} (PFA3) have been obtained by Rh(I)-catalyzed polymerization of the corresponding terminal acetylene monomers 2-ethynyl-9,9-bis[(S)-3,7-dimethyloctyl]fluorene (2a), 2-ethynyl-9,9-bis[(S)-2-methylbutyl]fluorene (2b), and 2-ethynyl-9,9,9′,9′,9′′,9′′-hexakis[(S)-2-methylbutyl]-7,2′;7′,2′′-terfluorene (10). The effect of the alkyl chain length at the C-9 position of fluorene on the structural and conformational aspects of the polymers PFA1 and PFA2 as well as on their chiroptical properties was studied by XRD, DSC, TGA, GPC, UV-vis, and CD. A more planar conformation of the polyenic backbone of PFA1 with respect to PFA2 can be inferred by a red shift of the ð-ð* transition in the UV-vis spectra. Their photoluminescence properties are those typical of fluorene systems. CD measurements evidenced Cotton effects of opposite signs in correspondence of the backbone absorption region, ascribable to an excess of a screw sense of the helical conformations assumed by the two polymers. PFA3 revealed an amorphous structure and exhibited peculiar thermal stability features (as indicated by TGA and DSC). Its emission spectra interest the violet-blue region and do not show any substantial red shift passing from solution to solid state, thus pointing out an aggregation prevention of terfluorene groups by means of the polyacetylene backbone

Treatment of a rapidly expanding thoracoabdominal aortic aneurysm after endovascular repair of descending thoracic aortic aneurysm in an old patient.

Background: Aortic pathology progression and/or procedure related complications following endovascular repair should always be considered mostly in older patients. We herein describe a hybrid procedure for treatment of rapidly expanding thoracoabdominal aneurysm following endovascular treatment of a descending thoracic aortic aneurysm in an older patient. Case presentation: A 82-year-old man at 18 months after endovascular surgery for a contained rupture of descending thoracic aortic aneurysm revealed a type IV thoracoabdominal aneurysm with significant increase of the aortic diameters at superior mesenteric and renal artery levels. A hybrid approach consisting of preventive visceral vessel revascularization and endovascular repair of entire abdominal aorta was performed. Under general anaesthesia and by xyphopubic laparotomy, the infrarenal aneurysmatic aorta and common iliac arteries were replaced by a bifurcated woven prosthetic graf. From each of the prosthetic branches two reverse 14x7 mm bifurcated PTFE prosthetic grafts were anastomized to both renal arteries and to the celiac axis and superior mesenteric artery, respectively. Vessel ischemia was restricted to the time required for anastomosis. Three 10 cm Gore endovascular stent-grafts for a total length of 15 cm, were used. The overlapping of the stent-grafts was carried out from the bottom upwards, starting from the aorto-iliac prosthetic body up to the healthy segment of thoracic aorta, 40 mm from the previous stent-grafts. The patient was discharged on the 9th postoperative day. Conclusion: This technique offers the advantage of a less invasive treatment, reducing the risk of paraplegia, visceral ischaemia and pulmonary complications, mostly in older patients

Status of coronary disease and results from early endovascular aneurysm repair after preventive percutaneous coronary revascularization

Background: The incidence of coronary artery disease (CAD) is high in patients with an aortic aneurysm but preoperative routine coronary angiography and preventive coronary revascularization are not recommended to reduce cardiac events in patients with severe CAD. Aim: This study evaluated the safeness and efficacy of preventive percutaneous coronary intervention (PCI) in patients with severe CAD scheduled for endovascular aneurysm repair (EVAR). Methods: All patients with descending thoracic aneurysm (DTA) or abdominal aortic aneurysm (AAA) scheduled for EVAR underwent preliminary coronary angiography. Based on coronary angiography results, 917 patients (40.7%) had significant CAD and were treated by percutaneous coronary intervention (PCI; CAD group) and 1337 patients (59.3%) were without or with mild/moderate CAD and were considered as controls (no‐CAD group). To evaluate the safeness and efficacy of preventive PCI in patients with severe CAD undergoing EVAR, groups were compared for hospital and 12‐month cardiac adverse events. Results: CAD was present in 1210 patients (53.6%): significant in 917 patients (38%) and mild to moderate in 293 patients (5.3%). Hospital and 12‐month cardiac events occurred in 15 (1.6%) and 13 (1.4%) CAD group patients and in 9 (0.7%) and 8 (0.4%) no‐CAD group patients (p = .05 and p = .08), respectively. Hospital and 12‐month cardiac deaths occurred in 3 (0.3%) and 2 (0.2%) CAD group patients and in 3 (0.2%) and 2 (0.2%) no‐CAD group patients (p = .9 and p = .9), respectively. Conclusion: The strategy to treat severe CAD preoperatively by PCI and early subsequent EVAR brings a similar outcome to that in patients without or with mild/ moderate CAD

Low cost laboratories using ICT

En este trabajo se presentan los resultados de una propuesta educativa orientada a promover el desarrollo de un pensamiento crítico y un mayor interés por las ciencias experimentales. Con este fin desarrollamos propuestas de proyectos educativos susceptibles de ser destinadas a las aulas y laboratorios de las escuelas secundarias y primeros años de la universidad, que resaltan los aspectos metodológicos de las ciencias. Aquí, realizamos una compilación de varios proyectos, que ilustran formas de incorporar las tecnologías de la información y la comunicación (TIC) en diversos experimentos de ciencias, muchos de ellos publicados individualmente anteriormente, y que en conjunto se pueden utilizar para implementar un aula-laboratorio de bajo costo. Con TIC hacemos referencia a la convergencia de computadoras, sistemas audiovisuales, Internet, telefonía, y diversos equipos que se integran con algunos de ellos. Los proyectos intentan integrar áreas como física, matemática, química, informática, arte, etc. y apuntan a que los estudiantes puedan responder a las preguntas: ¿Cómo sabemos esto?, ¿Por qué creemos en aquello? Preguntas que ilustran la naturaleza del pensamiento científico. Nuestra contribución más significativa es haber desarrollado «aulas-laboratorios» de muy bajo costo, usando TIC. Con el advenimiento de programas como «Una Laptop por Niño» que se están implementando en varios países de Latinoamérica, resulta oportuno utilizar este recurso como base para generar laboratorios de bajo costo, que creemos pueden ser una herramienta útil para mejorar el aprendizaje de las ciencias, incentivar vocaciones y contribuir a desarrollar un pensamiento crítico, a la par de desarrollar habilidades con el uso de las TIC que pueden ser de utilidad en diversos ámbitos académicos y laborales.The results of an educational project aimed at promoting the development of critical thinking and promote interest in experimental sciences in High Schools and College students is presented. In this paper, we made a compilation of several activities, which ways of integrating information technology and communication (ICT) in various experiments of science, which together can be used to implement a low cost “classroom-laboratory”. With ICT we refer to the convergence of computers, software, audiovisual systems, Internet, telephone, and other equipment that integrates with some of these devices. To this end, several projects were developed, that can be transferred to high schools and colleges settings, with limited financial resources, as is frequent in Latin America. The projects highlight the methodological aspects of science and seek to integrate areas such as physics, mathematics, chemistry, computer science, art, etc. They aim to answer the questions: how do we know this?, why do we believe in that? These questions illustrate the nature of scientific thought. With the advent of programs such as “One Laptop per Child” that are being implemented in several Latin American countries, it is appropriate to use these resources as a basis to generate low cost laboratories. This contribution may be a useful tool to improve the quality of science learning and to encourage vocations in science and engineering. Furthermore, the development of a critical thinking, along with acquisition of skills in the use of ICT, can be essential in many academic and professional fields

Experimental evidence of stochastic resonance without tuning due to non Gaussian noises

In order to test theoretical predictions, we have studied the phenomenon of stochastic resonance in an electronic experimental system driven by white non Gaussian noise. In agreement with the theoretical predictions our main findings are: an enhancement of the sensibility of the system together with a remarkable widening of the response (robustness). This implies that even a single resonant unit can reach a marked reduction in the need of noise tuning.Comment: 4 pages, 3 figure