1,721,075 research outputs found
Hyper-concentrated flows: experimental investigation of effect of inflow parameters and sediment concentration on propagation process
No full textDebris-flows runout estimations are of crucial importance to delineate the potentially hazardous areas and to make reliable assessment of the level of risk of urban areas. Especially in recent years, several researches have been conducted in order to define predicitive models. But, existing runout estimation methods need input parameters that can be difficult to estimate. Recent experimental researches have also allowed the assessment of the physics of the debris flows. But, the major part of the experimental studies analyze the basic kinematic conditions which determine the phenomenon evolution. Experimental program has been recently conducted at the Hydraulic laboratory of the Department of Civil, Environmental, Aerospatial and of Materials (DICAM) – University of Palermo (Italy). The experiments, carried out in a laboratory flume appositely constructed, were planned in order to evaluate both the effect of sediment concentration and the influence of the geometrical parameters (such as the slope and the geometrical characteristics of the confluences to the main channel) on the propagation phenomenon of the debris flow and its deposition. The laboratory flume reproduces the protection channel which is under construction in Giampilieri (Messina – Italy). The experimental apparatus includes a high-precision camera allowing the estimation of hyperconcentrated flow velocity by applying the VIA technique. Attention is particularly focused on flowing of sediment-water mixture for different geometrical characteristics (slope, angle,..) of the inflow channels and/or by introducing roughness elements on the bed. The propagation phenomenon is analyzed and discussed for different concentrations of sediment
Flow-induced vegetation uprooting in a meandering bend : experimental investigation
No full textVegetation uprooting is a complex process which depends on many interrelated factors. In this paper, attention is focused on the flow-induced uprooting in river bends, where the flow characteristics vary as effected by the channel's curvature and its continuous changing in the downstream direction. Results are presented by an experimental work done in a high-amplitude meandering flume with mature herbaceous vegetation on the bed. In the first part of the paper, the variation along the bend of the geometrical (length, thickness, and radical architecture) and the mechanical (resistance force) characteristics of the roots are analyzed. In the second part of the paper, the transition from the condition of vegetation distributed on the bed to the condition of vegetation uprooted by the flow is experimentally examined. The results show that the flow-induced uprooting varies along the bend depending on the roots' geometrical and mechanical characteristics which are, in turn, influenced by the variation of the water surface elevation along the bend itself. It has been found that lower values of the resistance force occur at the apex section where the roots are characterized by higher values of length and lower values of thickness and have radical apparatuses characterized by limited encumbrance, a high number of roots, and low bushyness. The flow-induced uprooting especially develops close to the outer bank along the channel reach between the bend entrance and the apex section, where the root resistance force and the water surface slope tend to decrease in value
PROPAGATION OF HYPERCONCENTRATED FLOWS IN PROTECTION CHANNELS AROUND URBAN AREAS: EXPERIMENTAL INVESTIGATION
Full text linkMonitoring of surface velocity of hyper-concentrated flow in a laboratory flume by means of fully-digital PIV
No full textThis paper investigates the utility and the efficiency of the digital image-technique for remote monitoring of surface velocity in hyper-concentrated flow by the aid of data collected
during experiments conducted in the laboratory flume. In particular the present paper attention is focused on the estimation procedure of the velocity vectors and on their sensitivity with parameters (number of images, spatial resolution of interrogation area, ) of the images processing procedure
Variazione delle caratteristiche delle radici di una vegetazione flessibile e matura in un canale meandriforme: risultati preliminari
Full text linkASPETTI CHIAVE
• Interazione corrente-vegetazione in un canale meandriforme
• Variazione delle caratteristiche geometriche delle radici di una vegetazione matura lungo la curva
• Variazione delle caratteristiche meccaniche delle radici di una vegetazione matura lungo la curv
Investigating CRISPR-CAS13b as a tool for the RNA editing of CFTR mRNA with premature stop codon
Full text linkBackground and Rationale
Some CF patients are compound heterozygous or homozygous for
nonsense mutations in the CFTR gene. Mutant CFTR gene coding for
transcripts with premature termination codons (PTCs) is responsible
for truncated CFTR protein and for a severe form of the disease. In a
precision medicine framework the “REPAIRv2” (RNA Editing for
Programmable A to I Replacement v2) tool, developed in the laboratory
of Dr. Feng Zhang (USA), seems a good alternative to restore
the full-length CFTR protein by editing its mRNA containing PTCs.
This new approach is based on the possibility of targeting a deaminase
enzyme (huADAR2) to a specific Adenosine, to be edited to Inosine
(G analogue), on the mutant RNA by a specific guide RNA
(gRNA), complementary to the target regions, and a Cas protein.
Hypothesis and objectives
We applied the new CRISPR/dCas13b based molecular tool of RNA
editing (REPAIRv2) to correct the premature stop codon UGA, changing
to UGG, in the H2bGFPopal and CFTRW1282X mRNAs with the
purpose of recovering the full-length proteins.Essential Methods
We designed and cloned the gRNAs needed to target the REPAIRv2
system to the Adenine to be modified. By site-directed mutagenesis
we introduced a premature stop codon, W1282X, in the CFTR cDNA.
Human HeLa cells expressing the H2BGFPopal mRNA, FRT cells expressing
CFTRW1282X and IB3.1 airway epithelial human cells
(CFTRΔ508/W12382X) were co-transfected with the plasmids coding
for the recombinant protein dCAS13b/ADAR2DD, and for the gRNAs.
Fluorescence microscopy was used to analyse the editing results.
Results
Direct fluorescence microscopy and immunofluorescence analyses
detecting the corrected proteins (H2BGFP and CFTR, respectively)
suggest that the REPAIRv2 system was able, in different cell lines, to
edit the H2BGFPopal and the CFTRW1282X mRNA. However, the rate
of editing does not seem high. Indeed, when RNA was purified from
transfected cell, retro-transcribed and amplified base correction was
not detectable by standard DNA sequencing and western blot.
Conclusions
Collectively, our results indicate that the REPAIRv2 tool is able to edit
the UGA premature stop codon present in the HeLa-H2BGFPopal
cells and in engineered FRTW1282X cells harbouring the UGA PTC in
the CFTR mRNA. Furthermore, the REPAIRv2 tool worked in the IB3.1
cells suggesting its ability to edit endogenous UGA premature stop
codon. Anyway, enhance the delivery of the plasmids as well increase/
stabilize the target mRNA to be edited, seem necessary to improve
the efficiency of REPAIRv2.
References
1. Cox DBT, Gootenberg JS, Abudayyeh OO, Franklin B, Kellner MJ, Joung J,
Zhang F.- RNA editing with CRISPR-Cas13. Science. 2017 Nov 24; 358
(6366):1019-1027)
2. Lentini L, Melfi R, Di Leonardo A, Spinello A, Barone G, Pace A, Palumbo
Piccionello A, Pibiri I. Toward a rationale for the PTC124 (Ataluren)
promoted readthrough of premature stop codons: a computational
approach and GFP-reporter cell-based assay. Mol Pharm. 2014 Mar
3;11(3):653-64.
Acknowledgment FFC#5/2018 funded by FFC and supported by Delegazione
FFC di Palerm
P14ARF: The absence that makes the difference
Full text linkP14ARF is a tumor suppressor encoded by the CDKN2a locus that is frequently inactivated in human tumors. P14ARF protein quenches oncogene stimuli by inhibiting cell cycle progression and inducing apoptosis. P14ARF functions can be played through interactions with several proteins. However, the majority of its activities are notoriously mediated by the p53 protein. Interestingly, recent studies suggest a new role of p14ARF in the maintenance of chromosome stability. Here, we deepened this new facet of p14ARF which we believe is relevant to its tumor suppressive role in the cell. To this aim, we generated a monoclonal HCT116 cell line expressing the p14ARF cDNA cloned in the piggyback vector and then induced aneuploidy by treating HCT116 cells with the CENP‐E inhibitor GSK923295. P14ARF ectopic re‐expression restored the near‐diploid phenotype of HCT116 cells, confirming that p14ARF counteracts aneuploid cell generation/proliferation
Turbulence structure and implications in exchange processes in high-amplitude vegetated meanders: Experimental investigation
No full textAquatic plants in rivers interact with flow and exert an important role in maintaining suitable habitat and ecological equilibrium. Understanding turbulence structure in the presence of vegetation is important with respect to environmental processes, such as sediment transport and mixing of transported quantities. Literature indicates that mass and momentum exchanges in the presence of vegetation are strongly influenced by the sequence of coherent structures which form between vegetated and non-vegetated zones. In the present paper we investigate turbulence structure and coherent motion in high-curvature channels with submerged vegetation. The analysis is performed with the aid of detailed experimental data collected in a meandering flume of large amplitude. Results essentially highlight that the contribution of turbulence to lateral diffusion and to streamwise and vertical transport may be significantly influenced by the relative submergence h/kv. The dominant mechanism of exchange obtained for h/kv2. Quadrant analysis has been also applied to investigate the occurrence of turbulent events and the associated exchange mechanism. In particular, at the apex section, it has been found that ejection events dominate in the outer bank region and, as literature indicates, this could cause the suspension of sediment in the flow that is transported downstream. In the central region the motion is especially characterized by high-speed fluid directed towards the bed, influencing the transport process significantly
Efficiency of a digital particle image velocimetry (DPIV) method for monitoring the surface velocity of hyper-concentrated flows
Full text linkDigital particle image velocimetry records high resolution images and allows the identification of the position of points in different time instants. This paper explores the efficiency of the digital image-technique for remote monitoring of surface velocity and discharge measurement in hyper-concentrated flow by the way of laboratory experiment. One of the challenges in the application of the image-technique is the evaluation of the error in estimating surface velocity. The error quantification is complex because it depends on many factors characterizing either the experimental conditions or/and the processing algorithm. In the present work, attention is devoted to the estimation error due either to the acquisition time or to the size of the sub-images (interrogation areas) to be correlated. The analysis is conducted with the aid of data collected in a scale laboratory flume constructed at the Hydraulic laboratory of the Department of Civil, Environmental, Aerospace and of Materials Engineering (DICAM)—University of Palermo (Italy) and the image processing is carried out by the help of the PivLab algorithm in Matlab. The obtained results confirm that the number of frames used in processing procedure strongly affects the values of surface velocity; the estimation error decreases as the number of frames increases. The size of the interrogation area also exerts an important role in the flow velocity estimation. For the examined case, a reduction of the size of the interrogation area of one half compared to its original size has allowed us to obtain low values of the velocity estimation error. Results also demonstrate the ability of the digital image-technique to estimate the discharge at given cross-sections. The values of the discharge estimated by applying the digital image-technique downstream of the inflow sections by using the aforementioned size of the interrogation area compares well with those measured
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