Heavy metal biosorption by bacterial cells

Microbial biomass provides available ligand groups on which metal ions bind by different mechanisms. Biosorption of these elements from aqueous solutions represents a remediation technology suitable for the treatment of metal-contaminated effluents. The purpose of the present investigation was the assessment of the capability of Brevibacterium sp. cells to remove bivalent ions, when present alone or in pairs, from aqueous solutions, using immobilized polyacrylamide cells of the microorganism in a flow-through system. The biosorption capacity of Brevibacterium cells was studied for lead, cadmium and copper. The metal cell binding capacity followed the order Cu > Pb > Cd, based on estimated q_max. These values, expressed as mmol metal/g dry weight cells, were 0.54 for Cu, 0.36 for Pb and 0.14 for Cd. Polyacrylamide-gel immobilized cells were effective in Pb, Cu and Cd removal. Lead removal was not affected by the presence of Cd and Cu; lead instead inhibited Cd and Cu removal. The desorption of the metal, by fluxing a chelating solution, restored the metal binding capacity of the cells, thus affording the multiple use of the same biomass in the remediation treatment. Received: 31 July 1997 / Revised: 22 December 1997 / Accepted: 30 December 1997     

Collection and analytical characterisation of the atmospheric particulate in the city of Bari

In this paper an application of new procedures for atmospheric particulate analysis is illustrated. PM10, PAHs (benzo[a]anthracene (BaA), benzo[b]fluoranthene (BbF), benzo[j]fluoranthene (BjF), benzo[k]fluoranthene (BkF), benzo[a]pyrene (BaP), indeno[1, 2, 3-cd]pyrene (Ip), dibenzo[a, h]anthracene (DbA)) and heavy metals (Cu, Ni, Zn, Co, Mn, Cd, Fe and Pb) were investigated. PM10 determination was performed by gravimetric method, PAHs were measured by GC-MS, and heavy metals by HPIC. An air quality monitoring campaign on the territory of Bari municipality has been organised, and its results are shown.     

Marine Sediments and Snow from Ross Sea Region (Antarctica) Dating by 210Pb Method

Abstract

²¹⁰Pb is widely used to determine accumulation rates in order to obtain a time scale in environmental samples. The most accurate method uses the determination of ²¹⁰Pb via its grand-daughter ²¹⁰Po by alpha spectrometry. Unfortunately this method requires a complex wet-chemistry procedure to achieve the separation of ²¹⁰Po from its matrix. In this work a simplified procedure for the chemical separation of ²¹⁰Po is proposed and applied to three marine sediment cores and a 10 m snow core collected in Antarctica. The calculated sedimentation rates for marine sediments range from 0.053 to 0.071 cm y^?1. The mean annual accumulation rate for the snow is 16.6 cm y^?1 w.e. A comparison with literature data in the same region is given.     

Quantitation of a de‐fluorinated analogue of Casopitant Mesylate by normal‐phase liquid chromatography/mass spectrometry

The introduction of Quality by Design (QbD) in Drug Development has resulted in a greater emphasis on chemical process understanding, in particular on the origin and fate of impurities. Therefore, the identification and quantitation of low level impurities in new Active Pharmaceutical Ingredients (APIs) play a crucial role in project progression and this has created a greater need for sensitive and selective analytical methodology. Consequently, scientists are constantly challenged to look for new applications of traditional analytical techniques. In this context a normal‐phase liquid chromatography/electrospray ionization mass spectrometry (LC/ESI‐MS) method was developed to determine the amount of a de‐fluorinated analogue impurity in Casopitant Mesylate, a new API under development in GlaxoSmithKline, Verona. Normal‐phase LC provided the selectivity needed between our target analyte and Casopitant, while a single quadrupole mass spectrometer was used to ensure the sensitivity needed to detect the impurity at <0.05%w/w. Standard solutions and samples were prepared in heptane/ethanol (50:50, v/v) containing 1% of 2 M NH₃ in ethanol; the mobile phase consisted of heptane/ethanol (95:5, v/v) with isocratic elution (flow rate: 1.0 mL/min, total run time: 23 min). To allow the formation of ions in solutions under normal‐phase (apolar) conditions, a post‐column infusion of a solution of 0.1% v/v of formic acid in methanol was applied (flow rate: 200 µL/min). The analysis was carried out in positive ion mode, monitoring the impurity by single ion monitoring (SIM). The method was fully validated and its applicability was demonstrated by the analysis of real‐life samples. This work is an example of the need for selective and accurate methodology during the development of a new chemical entity in order to develop an appropriate control strategy for impurities to ultimately ensure patient safety. Copyright © 2010 John Wiley & Sons, Ltd.     

Photoluminescence-Based Techniques for the Detection of Micro- and Nanoplastics

The growing numbers related to plastic pollution are impressive, with ca. 70 % of produced plastic (>350 tonnes/year) being indiscriminately wasted in the environment. The most dangerous forms of plastic pollution for biota and human health are micro- and nano-plastics (MNPs), which are ubiquitous and more bioavailable. Their elimination is extremely difficult, but the first challenge is their detection since existing protocols are unsatisfactory for microplastics and mostly absent for nanoplastics. After a discussion of the state of the art for MNPs detection, we specifically revise the techniques based on photoluminescence that represent very promising solutions for this problem. In this context, Nile Red staining is the most used strategy and we show here its pros and limitations, but we also discuss other more recent approaches, such as the use of fluorogenic probes based on perylene-bisimide and on fluorogenic hyaluronan nanogels, with the added values of biocompatibility and water solubility.     

Hartogs Phenomena and Antisyzygies for Systems of Differential Equations

We introduce the notion of antisyzygies, which studies the inverse problem of finding a system of PDEs, given compatibility conditions. The system obtained possesses the property of removability of compact singularities. We write explicit computations in the cases of the Cauchy-Fueter system and Maxwell’s system for electromagnetism, and we conclude with a study of systems of non-maximal rank.      

Cores of Simplicial Complexes

We introduce a method to reduce the study of the topology of a simplicial complex to that of a simpler one. Applying this method to complexes arising from graphs, we give topological meaning to classical graph invariants. As a consequence, we answer some questions raised in (Ehrenborg and Hetyei in Eur. J. Comb. 27(6):906–923, 2006) on the independence complex and the dominance complex of a forest and obtain improved algorithms to compute their homotopy types.     

Big rational surfaces

We prove that the Cox ring of a smooth rational surface with big anticanonical class is finitely generated. We classify surfaces of this type that are blow-ups of \mathbbP²{\mathbb{P}^2} at distinct points lying on a (possibly reducible) cubic.