Sorption and mobility of polyethylene glycol (PEG 4000) in tropical soils

Millions of tons of polyethylene glycols (PEGs) are manufactured worldwide and most of them will reach conventional sewage disposal systems after industrial utilization. This raises environmental concerns, but not much is known about the environmental fate of these polymers. The main goals of this research were to evaluate sorption and mobility of PEG in sandier soils of Brazil. PEG 4000 was applied to the soils either freely in solution or as a simulated bioassay residue. The bioassay was prepared to simulate PEG as it is present in the animal feces. It allowed us to compare PEG mobility for both forms of environment disposal. PEG showed very low sorption (<22% of the applied PEG) and high mobility potential (>43% of the applied amount in the free-PEG and >24% of the applied amount in the bioassay-PEG experiment) in the studied soils. When PEG was applied, simulating its supply to animal diets, about 30% of its applied amount was retained into the bioassay residues and its leaching potential was reduced, whereas the remaining amount (about 70%) was readily available in solution and could be directly released into the environment.     

Morphological and chemical characteristics of atmospheric particles in the Metropolitan Zone of Toluca Valley (Mexico)

Scanning electron microscopy with energy-dispersive spectroscopy has been used for both morphological and elemental chemistry analyses of atmospheric particles. This technique allows the in situ observation of individual aerosol particles in the sample chamber. Aerotransported particles were analysed from seven monitoring stations located in the Metropolitan Zone of Toluca Valley (MZTV). Several different morphologies were identified: aggregates, porous spheres, rough and smooth compact material. The elemental composition included C, Na, Mg, Al, Si, S, Cl, K, Mn, Ca, Ti, V, Cr, Fe, Ni, Cu, Zn and Ce. These are semiquantitative analyses considering the bulk sample or individual particles. It was possible to correlate or confirm some chemical associations such as C–S, Ca–S–O and Si–Al–O, probably due to the presence of compounds derived from incomplete combustion, building tailing materials and aluminosilicates of cortical origin. Bioaerosols such as pollen, spores, brochosomes and diatoms were identified in the zone; all these types of particles have a natural origin too. Several types of suspended particles were identified in the MZTV, they were from different sources (natural and anthropogenic) to which the population can be potentially exposed, and may cause harm in the short- and long-term, according to their chemical element composition and size.     

Successful intrauterine shunting of a sacrococcygeal teratoma (SCT) causing fetal bladder obstruction

We report a case of a sacrococcygeal teratoma (SCT) diagnosed at 22 weeks with a substantial intrapelvic cystic extension leading to bladder outlet obstruction and hydronephrosis at 27 weeks. Prenatal percutaneous shunting of the cystic teratoma was performed at 28 weeks to avoid prolonged fetal pelvic compression by the tumour that could have adverse effects by stretching the pelvic plexus and sacral nerves. Urinary dilatation resolved completely after shunting and a 3880 g baby girl was delivered at 39 weeks. The potential benefits of in utero shunting to avoid urological complications of SCTs with intrapelvic extension are discussed. Copyright © 2001 John Wiley & Sons, Ltd.     

Mesomelic campomelia,polydactyly and Dandy–Walker cyst in siblings

The present report describes two fetuses, one female and one male, with thus far undescribed skeletal malformations. The mother was a gravida 2, para 0. Both pregnancies were terminated in the second trimester because of multiple congenital anomalies diagnosed ultrasonographically resembling a short rib-polydactyly syndrome. Both fetuses were found to have postaxial hexadactyly of the hands and feet, marked bilateral campomelia of the forearm and shank bones, and a Dandy–Walker cyst. In addition, the fourth ventricle was dilated in the first sibling and the second sibling had an inverse intestinal malrotation. A literature search failed to reveal similar observations. Copyright © 2001 John Wiley & Sons, Ltd.     

Klippel–Trenaunay–Weber (KTW) syndrome: the use of in utero magnetic resonance imaging (MRI) in a prospective diagnosis

The diagnosis of the Klippel–Trenaunay–Weber (KTW) syndrome is rarely made antenatally. We report the use of both ultrasound and in utero magnetic resonance imaging (MRI) in the prenatal diagnosis of this syndrome. This is the first report of the use of prenatal MRI in the diagnosis of this condition. There was concordance in the findings of both modalities, with limb hypertrophy, and multiple haemangiomata – both subcutaneous and internally – demonstrated with ultrasound and MRI. The patient elected to terminate the pregnancy because of associated oligohydramnios and a small fetal chest noted at 20 weeks. The postmortem examination confirmed the antenatal diagnosis. Copyright © 2001 John Wiley & Sons, Ltd.     

Pregnancy after preimplantation genetic diagnosis for Sanjad–Sakati syndrome

Sanjad–Sakati syndrome (SSS) is an autosomal recessive disorder characterized by congenital hypoparathyroidism, growth and mental retardation. In Saudi Arabia, the disease is caused by a deletion of 12 bp (155-166nt) in the tubulin-specific chaperone E gene. In a family with two affected siblings with SSS, preimplantation genetic diagnosis (PGD) was performed. Fluorescent PCR (F-PCR) was utilized to check the heterozygosity and the homozygosity status of the parents and the affected children, respectively. F-PCR was then optimized for single-cell analysis by using peripheral blood lymphocytes. The patient underwent a cycle with intra-cytoplasmic sperm injection. A total of 11 embryos were obtained and biopsied. There were five heterozygous, three homozygous affected and three normal embryos. One heterozygous and one normal embryo were transferred because of their very good quality (morula). A singleton pregnancy was obtained, and amniosynthesis confirmed the presence of the heterozygous fetus. These results show for the first time, the feasibility of PGD for SSS. Copyright © 2004 John Wiley & Sons, Ltd.     

Problems and issues in laser beam welding of aluminum–lithium alloys

Aluminum–lithium (Al–Li) alloys are very attractive for potential aerospace applications due to their lower density, higher specific strength and rigidity, better corrosion and fatigue crack growth resistance properties, compared to conventional aluminum alloys. Laser beam welding (LBW), being an advanced joining method, has already been approved for applications involving aluminum alloys. However, there are still a number of problems and issues to be answered and solved in LBW of Al–Li alloys. In this review, the properties of Al–Li alloys and the characteristics of LBW are introduced, the formation and prevention of the main weld defects such as porosity and hot cracking are discussed, and then the weld microstructure and the joint mechanical properties are described in highlight. At the end, an outlook on future trends is presented.     

Hot extrusion process modeling using a coupled upper bound-finite element method

A thermo-mechanical model has been developed for modeling of hot extrusion processes. Accordingly, an admissible velocity field was first proposed by means of stream function method and then, extrusion pressure as well as temperature variations within the metal and the die were predicted employing a combined upper bound and Petrov–Galerkin finite element analysis. In order to evaluate the model predictions, hot extrusion of AA6061-10%SiC_p was considered under both isothermal and non-isothermal conditions and the predicted force–displacement diagrams under various extrusion conditions were compared with the experimental ones and reasonable consistency was found between the two sets of results.     

An imprecise Fault Tree Analysis for the estimation of the Rate of OCcurrence Of Failure (ROCOF)

The paper proposes an imprecise Fault Tree Analysis in order to characterize systems affected by the lack of reliability data. Differently from other research works, the paper introduces a classification of basic events into two categories, namely Initiators and Enablers. Actually, in real industrial systems some events refer to component failures or process parameter deviations from normal operating conditions (Initiators), whereas others refer to the functioning of safety barriers to be activated on demand (Enablers). As a consequence, the output parameter of interest is not the classical probability of occurrence of the top event, but its Rate of OCcurrence (ROCOF) over a stated period of time. In order to characterize the basic events, interval-valued information supplied by experts are properly aggregated and propagated to the top. To this purpose, the Dempster–Shafer Theory of evidence is proposed as a more appropriate mathematical framework than the classical probabilistic one. The proposed methodology, applied to a real industrial scenario, can be considered a helpful tool to support risk managers working in industrial plants.     

Experimental investigation of fast flame propagation in stratified hydrogen–air mixtures in semi-confined flat layers

This paper presents results of an experimental investigation on fast flame propagation and the deflagration-to-detonation transition (DDT) and following detonation propagation in a semi-confined flat layer filled with stratified hydrogen–air mixtures. The experiments were performed in a transparent, rectangular channel open from below. The combustion channel has a width of 0.3 m and a length of 2.5 m. The effective layer thickness in the channel was varied by using different linear hydrogen concentration gradients. The method to create quasi-linear hydrogen concentration gradients that differ in the range and slope is also presented. The ignited mixtures were accelerated quickly to sonic flame speed in the first obstructed part of the channel. The interaction of the fast flame propagation with different obstacle set-ups was studied in the second part of the channel. The experimental results show an initiation of DDT by one additional metal grid in the obstructed semi-confined flat layer. Detonation propagation and failed detonation propagation were observed in obstructed and unobstructed parts of the channel.