169,866 research outputs found
Review article: the histological assessment of disease activity in ulcerative colitis
No full textBackgound In patients with ulcerative colitis (UC), mucosal healing has emerged as a major therapeutic goal, and is usually assessed endoscopically. Histological healing does not correlate very well with endoscopic mucosal healing in UC and persistent histological inflammation might be a better predictor of future clinical relapse than the endoscopic appearance alone. Aim To define how histological assessment of disease activity should be best done in UC. Methods Electronic (PubMed/Embase) and manual search. Results At least 18 histological indices to assess disease activity in UC have been described, though none are fully validated. However, histological assessment is increasingly used as a secondary endpoint in clinical trials in UC. After reviewing and discussing existing histological scoring systems for UC activity, we describe features of histological response and define three grades of activity: (i) histological healing - complete resolution of abnormalities (ii) quiescent disease, - lack of mucosal neutrophils but chronic inflammation may remain (iii) active disease - presence of neutrophils plus possible epithelial damage. It is recommended that two biopsies are taken from each colonic segment which should include always biopsy of the rectum and the most affected segments. There is to date no agreed preferable scoring system but the Geboes Index is the best validated (kappa for interobserver variation 0.59-0.70). Conclusion Histological assessment of disease activity in UC is increasingly used, but needs to be carefully defined
Development and validation of the Nancy histological index for UC
No full textObjective We developed a validated index for assessing histological disease activity in UC and established its responsiveness. Methods Two hundred biopsies were scored. The outcome was the Global Visual Evaluation (GVE). Eight histological features were tested. The Nancy index was developed by multiple linear regression and bootstrap process to create an index that best matched the GVE. Goodness of fit was assessed by the adjusted R squared (adjusted R-2). The second step was the validation of the index: 100 biopsies were scored for the Nancy index by three pathologists from different centres. Inter-reader reliability was evaluated for each reader. The relationship between the change of the Nancy index and the Geboes index was assessed to assess the responsiveness. Results After backward selection with bootstrap validation, 3/8 items were selected: ulceration (adjusted R-2=0.55), acute inflammatory infiltrate (adjusted R-2=0.88) and chronic inflammatory infiltrate (adjusted R-2=0.79). The Nancy index is defined by a 5-level classification ranging from grade 0 (absence of significant histological disease activity) to grade 4 (severely active disease). The intraclass correlation coefficient (ICC) for the intrareader reliability was 0.88 (95% CI 0.82 to 0.92) and the index had good interreader reliability (ICC=0.86 (0.81 to 0.99)). The correlation between the Nancy index and the Geboes score or the GVE was very good. The index had a good responsiveness with a high correlation between changes in the Geboes score and changes in the Nancy index (0.910 (0.813 to 0.955)). Conclusions A three descriptor histological index has been validated for use in clinical practice and clinical trials
MONITORING THE PERFORMANCES IN REAL WORKING CONDITIONS OF C&D WASTE MATERIALS IN ROAD CONSTRUCTION USING EMBEDDED INSTRUMENTS
No full textThis paper reports the results obtained so far, of the research conducted to verify the
compatibility of construction and demolition waste (C&D) as alternative materials for
road constructions. Annually highway and construction industries consume a huge
amount of aggregates deriving from quarries, causing considerable energy and
environmental losses. Understand how this new type of materials behave on the
physical and mechanical point of view is important to encourage and develop their
use. Pavement material behaviour is affected by many factors (i.e., load magnitude,
material properties and environmental conditions), therefore not only laboratory tests
are important but especially evaluate mechanical performances in real working
conditions (Rombi at al., 2010). For this purpose an experimental road, 30 m long and
4 m wide, was built. At three different depths a total of n°12 instruments were
installed: 3 pressure cells to measure stresses and 9 Linear Variable Differential
Transformers (LVDTs) to measure deformations. In situ tests were conducted for each
layer during construction. At the end of the construction and after a year tests were
repeated to verify the mechanical behaviour in the long term. The data were collected
from the pressure cells and LVDTs under different load and speed magnitude. At this
point of the research data are being analysed and compared, and the results reported
on this paper. In the near future all the data collected will be used to calibrate a
mathematical model in order to predict C&D performances in real working
conditions. To be able to understand how pavement materials, no matter what type of
material you are using C&D or natural aggregates, respond to traffic and
environmental loading is fundamental when designing pavements and evaluating their
performance
EXPERIMENTAL INVESTIGATION ON THE USE OF C&DW MATERIALS AS AGGREGATES FOR ROAD SUB-BASE
No full textMore than 95% of road infrastructures materials consist of aggregates. Highway and
construction industries consume annually a huge amount of aggregates, causing
considerable energy and environmental losses (Hüseyin et al, 2007). Many country
are substituting quarry aggregates with construction and demolition waste (C&DW)
materials. However in Italy there is the need to overcome the distrust for the use of
C&D materials. Thus, the aim of this research is to evaluate the suitability of
construction and demolition waste (C&DW) materials, produced in Sardinia (Italy),
from the physical and mechanical point of view. Laboratory tests were conducted to
evaluate physical characteristics and also an experimental road has been built to
evaluate mechanical performances in situ. The research has been divided in two main
phases: in the first phase laboratory tests were carried out such as Sieve analysis,
Limits of Atterberg, CBR test, L.A. abrasion test. In the second phase in situ tests
were carried out consisting of: dry density of soil by sand replacement method and
both static and dynamic plate tests. Other tests were carried out to study the behaviour
of the material during its use (short term behaviour and in the long term), in order to
evaluate environmental compatibility of the material in place under working
conditions, as well as the mechanical performance in situ or in a real scale test. The
first results are encouraging, the material is non-plastic, the Los Angeles abrasion test
shows the tendency to fragmentation of the aggregates, but within the limits, therefore
allowing their use in road sub-grade layer also the material shows good bearing
capacity. The introduction in the market for the construction of roads of solid waste
materials helps to limit the exploitation of renewable natural resources
Sub-Micrometric MCM-41 Particles as Support to Design Efficient and Regenerable Maghemite-Based Sorbent for H2S Removal
Get PDFIn this work, highly dispersed maghemite (gamma-Fe2O3) in form of ultrasmall nanoparticles (about 2 nm) was embedded into a mesostructured silica MCM-41 (about 600 nm) featuring regular sub-micrometric hexagonal shaped particles via the two-solvent incipient wetness impregnation strategy. The obtained nanocomposite was then tested as H2S sorbent in the mid-temperature range. When compared with a commercial sorbent (Katalko(JM) 32-5), it showed superior performances after the first sulfidation which remained steady over three repeated sulfidation cycles, highlighting the regenerability properties of the composite. In order to evaluate the effect of the length of the pore channels on the accessibility of H2S to the active phase, an analogous micrometric gamma-Fe2O3 @MCM-41, featuring micrometric channels and particles of irregular shape was used as reference
Gold-assisted E ' centres formation on the silica surface of Au/SBA-15 catalysts for low temperature CO oxidation
No full textSH-functionalized SBA-15 was synthesized and gold nanoclusters were grafted inside its channels. Different portions of such gold-containing material were subjected to a variety of thermal treatments, including calcination in the 300-560 degrees C temperature range and further treatments under a hydrogen atmosphere at diverse temperatures (up to 600 degrees C). The resulting materials were thoroughly characterized by CHS elemental analysis, X-ray diffraction, transmission electron microscopy, N-2 physisorption and H-2 chemisorption, as well as by Raman, NMR, FTIR and EPR spectroscopies, in order to investigate the influence of the temperature and atmosphere of the pretreatment on the gold particle size and oxidation state, the formation of defective E' centres on the silica support and their ability to induce the formation of reactive O-2(-) surface species. Catalytic testing for the CO oxidation reaction was carried out in the 40 150 degrees C temperature range. Significant differences in catalytic behaviour were observed among the catalysts, which are discussed in the light of the characterization results. A mechanism for the "activation" of the non-reducible ("inert") SBA-15 support involving Au-0 -> Au+ transformation is proposed, where gold metal plays an essential twofold role: it induces the formation of atomic hydrogen by dissociatively adsorbing H-2 and triggers the formation of E' centres by transferring an electron to positively charged silicon species
Highly effective MnCeOx catalysts for biodiesel production by transesterification of vegetable oils with methanol
No full textThis paper reports the results obtained using a novel MnCeOx system in the transesterification reaction
of refined sunflower oil with methanol. The performance of such catalysts has been compared with that
of common acid supported catalysts. Results obtained revealed that MnCeOx system possesses a superior
activity especially by operating at low temperatures (≤120 ◦C). Independently of Mn loading, the redox precipitation
method for the preparation of Mn-based systems allowed to obtain always high dispersed
catalysts and, as a consequence, a linear relationship between reaction rate and Mn loading was obtained.
NH3-TPD and CO2-TPD measurements indicate that MnCeOx systems are characterized by a prevalent
nature of basic sites. However, the catalyst performance is the result of a synergic role played by both
the surface acid/base character and textural porosit
“Experimental Investigation on the Use of Recycled Aggregates”
No full textMore than 95% of road infrastructures materials consist of aggregates. Highway and construction industries consume annually a huge amount of aggregates, causing considerable energy and environmental losses. The aim of this research is to evaluate the suitability of construction and demolition waste (C&DW) materials, produced in Sardinia (Italy), from the physical and mechanical point of view. Laboratory tests were conducted to evaluate physical characteristics and also an experimental road has been built to evaluate mechanical performances in situ. The research has been divided in two main phases: in the first phase laboratory tests were carried out such as Sieve analysis, Limits of Atterberg, CBR test, L.A. abrasion test. In the second phase in situ tests were carried out consisting of: dry density of soil by sand replacement method and both static and dynamic plate tests. Other tests were carried out to study the behaviour of the material during its use (short term behaviour and in the long term), in order to evaluate environmental compatibility of the material in place under working conditions, as well as the mechanical performance in situ or in a real scale test. The first results are encouraging, the material is non-plastic, the Los Angeles abrasion test shows the tendency to fragmentation of the aggregates, but within the limits, therefore allowing their use in road sub-grade layer also the material shows good bearing capacity. The introduction in the market for the construction of roads of solid waste materials helps to limit the exploitation of renewable natural resources
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