1,280 research outputs found
Development of advanced analytical methods for the determination of emerging pollutants in environmental waters
This thesis work was focused on the analytical determination of emerging
pollutants in environmental water matrix, concerning preparative step and
analysis using Gas Chromatography coupled with Mass Spectrometry (GCMS).
The emerging pollutants are so defined because they have been
recognized only recently as pollutants and regulatory and monitoring plans
are not yet implemented at Italian and European level. Pharmaceuticals
and Personal Care Products (PPCPs) are considered emerging
contaminants, they describe a large class of chemical contaminants that
can originate from human usage and excretions and veterinary
applications. There are a large number of different substances used as
medicines, during and after treatment, humans and animals excrete a
combination of intact and metabolised pharmaceuticals, many of which are
generally soluble in water and have been discharged to the aquatic
environment with little evaluation of possible risks or consequences to
humans and environment. In addition, the chemicals that are components
of personal care products (PCPs) number in the thousands, the world’s
people consume enormous quantities of skin care products, dental care
products, soaps, sunscreen agents, and hair styling products. PCPs
continuously enter the wastewater after their regular use during showering
or bathing. Recent studies indicate the potential widespread occurrence on
low-level concentrations (ng-ÎĽg/L) of PPCPs in the aquatic environment.
Therefore, there’s critical need for efficient and reliable analytical methods
to address the occurrence concentrations, and fate of the PPCPs in
environment. GC-MS has been the basic tool for environmental analyses of
various organic pollutants and it has been the approach of this study choice
because of its superior separation and identification capabilities.
The activity has been concentrated on the development of sample
preparation procedures that could be fast, cost-effective and environmentfriendly
for the analysis of PPCPs. It’s known that sample pre-treatment
causes an analysis bottleneck that typically accounts for over 60% of the total analysis time. The work was focused on evaluation and optimization of
different extraction techniques for treatment of water matrix.
There are fundamentally two kinds of approach for parameters
optimization. One Factor At Time (OFAT) method involves the testing of
factors, or causes, one at a time instead of all factors are changed at once.
Even more people, prominent text books and academic papers currently
favour design of experiments (DOE) approach; it’s a statistically
multivariate method for screening and/or optimization of different factors at
the same time (multiple factors are changed at once). It shows several
relevant advantages over OFAT approach: it requires less runs for the
same (sometimes more) precision in effect estimation, it can estimate
interactions and it provides a knowledge (and optimal settings of factors) in
the whole experimental domain, where OFAT can miss them. For these
reasons this approach was chosen for several published works, using in
particular Central Composite Design (CCD) or Box-Behnken Design (BBD).
Two different extraction procedure have been studied: Solid Phase
Extraction (SPE) and Solid Phase Micro Extraction (SPME). The first
technique was evaluated in order to optimize extraction step of 25 PCPs,
including fragrances, PAHs, antioxidants, UV-filters, plasticizers, and
pesticides, from water, using OFAT approach. The optimized parameters
were different: SPE sorbent, type and volume of eluent, elution rate, and
evaporation procedure. The better recovery yield considering the totality of
PCPs were found extracting with a Strata-X SPE cartridge, using a volume
of 15 mL of Ethyl Acetate as solvent, operating with slow flow rate, and
evaporating at 40°C of temperature. Under these con ditions the procedure
achieves a recovery higher than 70% for most PCPs investigated (with
LOD ranged from 5 to 10 pg injected on GC), this result makes the
developed method suitable for comprehensive chemical profiling of PCPs in
various aqueous matrices. It is clear that higher recovery values can be
achieved only for selected PCPs using specific target-compound methods.
That it was done for method optimization for determination of two synthetic
phenolic antioxidants and their five main metabolites in water. This is the first published method dedicated solely to the determination of this
chemical class in water samples. The methodology was developed using
SPE approach with derivatization before GC-MS analysis. Extraction on 10
mg Oasis HLB cartridges provides a satisfactory enrichment factor for
environmental samples avoiding the need of solvent evaporation and
reducing SPE costs and organic solvent wastes. After extraction, polar
metabolites are derivatized with MTBSTFA to produce stable, less polar
analytes that are determined by GC-MS at low levels. The usage of two
surrogate internal standards results in a method providing good accuracy,
with relative recoveries between 80 and 110%, and limits of detection (2-44
ng/L). The application of the method to wastewater and river samples
showed BHT and BHT-Q as the compounds in higher concentrations in
wastewater (up to 800 ng/L) and the metabolites BHT-CHO and BHTCOOH
as the most resistant to water treatment, being at the 10-100 ng/L in
sewage and river samples. In this work the optimization was done with an
experimental design approach, using a Box-Behnken design (BBD). This
work was developed in collaboration with University of Santiago de
Compostela (E).
SPME technique was investigated in order to extract a mixture of several
PCPs, evaluating extraction time and temperature and desorption time and
temperature. A simple SPME method has been developed for the
simultaneous GC-MS determination of 23 PCPs (i.e. antioxidants, PAHs,
UV-filters, pesticides, fragrances, plasticizers, that display log Kow values >
3.2) at trace levels in water. An Inscribed Central Composite (CCI) design
approach was employed for investigate extraction temperature and time,
and desorption temperature and time. A direct immersion mode was used
for extraction from a fixed sample volume. The optimum SPME operating
conditions have been defined as: extraction time of 90 min at a temperature
of 80°C, desorption time of 11 min at 260°C. Under these conditions the
procedure provides low detection limits (<= ppb) and satisfactory
reproducibility (RSD%<=1%) for most of the PCPs investigated.
The analysis was then extended to more polar compounds, for a total of 21
PPCPs that display a range of log Kow between 1.2 and 6.4 (i.e. antiseptic,
antinflammatory drugs, estrogens, UV-filters) with the necessity of
derivatize the compounds before GC analysis. A on-fiber after extraction
approach was chosen for SPME derivatization, using silylation agent. The
derivatization can be performed in only 30.5 minutes with a very small
consumption of silylation reagent and without need of high temperature.
Under the optimized conditions of extraction, derivatization and desorption,
the procedure provides low detection limits (<= 1 ppb for the non polar
analytes and <=35 ppb for the derivatized ones) and satisfactory
reproducibility (RSD% <=10% or 20%) for most of the PPCPs investigated.
The PhD project, in his totality, was a logic progressive work, expanding the
study in term of kind of analytes studied, extraction techniques and
optimization approach. A preliminary and careful study was carried out in
order to properly understand the current situation and the possible research
developments of interest. The study was initially focused on less polar
analytes (PCPs), then extending to more polar ones (PPCPs). It was firstly
took in consideration the SPE technique, going to more innovative and
preferable on several points of view SPME. The expanded range (in
particular polarity range) of analytes makes necessary a derivatization step
before GC-MS analysis, for these reason the subsequent step was the
optimization of a method that includes SPME-derivatization. Also
considering the optimization approach, the work started using OFAT
optimization, this approach was left after the first work for the more
accurate and precise DOE.
These works led to development of multiresidual analytical method suitable
for the comprehensive analysis of this kind of pollutants in water matrix.
These methodologies may be the basis of water monitoring for temporal
and spatial changes
Geant4 Maintainability Assessed with Respect to Software Engineering References
We report a methodology developed to quantitatively assess the
maintainability of Geant4 with respect to software engineering references. The
level of maintainability is determined by combining a set of metrics values
whose references are documented in literature.Comment: 5 pages, 2 figures, 4 tables, IEEE NSS/MIC 201
Poly(hydroxyalkanoate) production by Cupriavidus necator from fatty waste can be enhanced by phaZ1 inactivation
PHA production from waste oils or fats requires microorganisms that should be both excellent PHA producers and equipped with enzymatic activities allowing hydrolysation of triglycerides. Unfortunately, microbes with the combination of substrate-utilization and PHA production are not currently available, and the strategies to be adopted are the use of costly commercial enzymes, or genetic modification of microorganisms exhibiting high PHA product yields. In the present work, after a general investigation on the ability of Cupriavidus necator to grow on a number of fatty substrates, the possibility to enhance PHA production by limiting intracellular depolymerisation, was investigated. By knocking out the related phaZ1 gene, the construction of C. necator recombinant strains impaired in depolymerase (PhaZ1) activity was achieved. The polymer yield of the recombinant strain was finally compared to that of the parental C. necator DSM 545
Publication patterns in HEP computing
An overview of the evolution of computing-oriented publications in high
energy physics following the start of operation of LHC. Quantitative analyses
are illustrated, which document the production of scholarly papers on
computing-related topics by high energy physics experiments and core tools
projects, and the citations they receive. Several scientometric indicators are
analyzed to characterize the role of computing in high energy physics
literature. Distinctive features of software-oriented and hardware-oriented
scholarly publications are highlighted. Current patterns and trends are
compared to the situation in previous generations' experiments.Comment: To be published in the Proc. of CHEP (Computing in High Energy
Physics) 201
Scholarly literature and the press: scientific impact and social perception of physics computing
The broad coverage of the search for the Higgs boson in the mainstream media
is a relative novelty for high energy physics (HEP) research, whose
achievements have traditionally been limited to scholarly literature. This
paper illustrates the results of a scientometric analysis of HEP computing in
scientific literature, institutional media and the press, and a comparative
overview of similar metrics concerning representative particle physics
measurements. The picture emerging from these scientometric data documents the
scientific impact and social perception of HEP computing. The results of this
analysis suggest that improved communication of the scientific and social role
of HEP computing would be beneficial to the high energy physics community.Comment: To be published in the Proceedings of CHEP 2013 (Computing in High
Energy Physics
On the Direct Strength Design of Continuous Cold-formed Steel Beams
The work reported in this paper concerns an ongoing investigation aimed at developing an efficient methodology to design continuous cold-formed steel beams failing in modes that combine local, distortional and global features. At this stage, it is intended to assess how accurately can the load-carrying capacity of lipped channel continuous (two and three-span) beams subjected to non-uniform bending be predicted by means of the current Direct Strength Method (DSM) design curves. “Exact” ultimate strength values yielded by geometrically and materially non-linear shell finite element analyses are compared with estimates provided by the DSM equations and, on the basis of this comparison, it is possible to identify some features that must be included in a DSM approach applicable to continuous cold-formed steel beams
Using Generalized Beam Theory (GBT) to Assess the Buckling Behavior of Cold-formed Steel Structural Systems
This paper deals with the application of beam finite element models based on Generalized Beam Theory (GBT) to analyze the buckling behavior of three cold-formed steel structural systems, namely (i) beams belonging to storage rack systems, (ii) portal frames built from rectangular hollow section (RHS) profiles and (iii) roof-supporting trusses, exhibiting different support conditions and subjected to various loadings. In particular, taking advantage of the GBT unique and structurally clarifying modal features, it is possible to assess how different geometries and/or bracing arrangements affect (improve) the local, distortional and/or global buckling behavior of the above structural systems. The accuracy of the GBT-based buckling results is assessed through the comparison with values yielded by rigorous shell finite element analyses carried out in the code ANSYS. In spite of the disparity between the numbers of degrees of freedom involved, which are orders of magnitude apart, there is a virtual coincidence between the critical buckling loads and mode shapes provided by the GBT (beam) and ANSYS (shell) finite element analyses
Production of bioethanol from multiple waste streams of rice milling
This work describes the feasibility of using rice milling by-products as feedstock for bioethanol. Starch-rich residues (rice bran, broken, unripe and discolored rice) were individually fermented (20% w/v) through Consolidated Bioprocessing by two industrial engineered yeast secreting fungal amylases. Rice husk (20% w/v), mainly composed by lignocellulose, was pre-treated at 55 degrees C with alkaline peroxide, saccharified through optimized dosages of commercial enzymes (Cellic (R) CTec2) and fermented by the recombinant strains.
Finally, a blend of all the rice by-products, formulated as a mixture (20% w/v) according to their proportions at milling plants, were co-processed to ethanol by optimized pre-treatment, saccharification and fermentation by amylolytic strains.
Fermenting efficiency for each by-product was high (above 88% of the theoretical) and further confirmed on the blend of residues (nearly 52 g/L ethanol). These results demonstrated for the first time that the co-conversion of multiple waste streams is a promising option for second generation ethanol production
The role of training in decreasing anxiety among experienced computer users
The purpose of our paper is twofold: on one hand we draw on the team climate literature to
understand how IT knowledge integration capability can be promoted within team-based structures;
on the other hand we rely on resource-based view framework for understanding how IT knowledge
integration capability affects teams performance, in terms of effectiveness, and efficiency. We tested
our research model on a sample of 410 members and leaders of 69 organizational work teams. Results
show the critical role played by team climate for favouring IT knowledge integration capability, which
in turn affects team outcomes.
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