On the theory of solitons of fluid pressure and solute density in geologic porous media, with applications to shale, clay and sandstone

In this paper we propose the application of a new model of transients of pore pressure p and solute density \r{ho} in geologic porous media. This model is rooted in the non-linear waves theory, the focus of which is advection and effect of large pressure jumps on strain (due to large p in a non-linear version of the Hooke law). It strictly relates p and \r{ho} evolving under the effect of a strong external stress. As a result, the presence of quick and sharp transients in low permeability rocks is unveiled, i.e. the non-linear Burgers solitons. We therefore propose that the actual transport process in porous rocks for large signals is not the linear diffusion, but could be governed by solitons. A test of an eventual presence of solitons in a rock is here proposed, and then applied to Pierre Shale, Bearpaw Shale, Boom Clay and Oznam-Mugu silt and clay. A quick analysis showing the presence of solitons for nuclear waste disposal and salty water intrusions is also analyzed. Finally, in a kind of "theoretical experiment" we show that solitons could also be present in Jordan and St. Peter sandstones, thus suggesting the occurrence of osmosis in these rocks

Effective reference and current integration for large displacement interface

The most common interface formulations proposed in literature are generally based on the restrictive hypothesis of small strains and small displacements and, even though their application to geometrically nonlinear problems is of paramount interest, only few contributions are available in literature. Motivations are probably due to the difficulties encountered on such formulation, as already mentioned by several authors. A pioneering formulation is the finite displacement three-dimensional interface developed by Ortiz and Pandolfi in [1], where normal and tangential traction components are evaluated with respect to the middle surface in the current configuration, producing a non-symmetric geometric stiffness matrix. More recently, an interface element formulation for geometrical non-linearity and material nonlinearity, which is developed in the reference configuration, has been proposed by Reinoso and Paggi in [2]. The constitutive model is formulated on the local reference, defined by normal axis and tangential axis with respect to the middle surface in the current configuration. The interface formulation generates a non symmetric geometric stiffness matrix, which is simplified by neglecting the non symmetric contribution, in order to reduces computational cost by the use of symmetric solver. The state of the art of cohesive models for the material separation is presented by Mosler and Scheider in [3], focusing the attention on the thermodynamics and variational consistency. In [3] the authors state that many proposed models do not verify fundamental requirements such as thermodynamic principles, frame invariance, equilibrium conditions. Such problems are magnified for anisotropic models in geometrically nonlinear context. Attention is also focused on the unphysical dissipation produced in elastic paths due to unsymmetrical stiffness matrix. Some existing cohesive-zone models are analyzed under conditions of large displacement and large strain by Ottosen et al in [4], and CZMs are also evaluated with respect to thermodynamic consistency and the fundamental laws such as balance of angular momentum and frame invariance. It is shown that in elastic regime only isotropic models, with traction vector aligned to separation displacement vector, fulfill the physical principles, as already shown in [5]. In [6] some cohesive-zone models are compared at finite strain condition, by a wedge test and by a peel test. The paper [6] shows that some models available in literature, or implemented in commercial finite element codes, which integrate the weak form equilibrium condition over the current configuration, produce significant error in terms of fracture energy. On the contrary, models integrated over the reference configuration produce negligible numerical error. The present paper investigates reasons of the different results between current and reference integration schemes. It is shown that interface formulations integrated over current configuration violate energy conservation principle, due to the elastic energy generated by the finite interface elongation with constant elastic stiffness parameters. Moreover, an original mechanical interpretation of the elastic stiffness parameters, defined as a density of elastic springs between the two interface edges, can be considered an effective solution for interface integrated over the current configuration. In fact, the interface elongation modify the density of springs, as well as volume change modifies the mass density, and integration over current configuration and integration over the reference one produce two identical solutions. In the present paper the interface formulation is rigorously developed under large displacement conditions, assuming as local reference for the constitutive model, normal and tangential axes to the middle surface, as already proposed in [1]. The geometric operators in the current configuration, such as the normal and tangential axes to the middle surface and elongation of the middle surface, are defined as functions of nodal displacements, and first order and second order derivatives, with respect to nodal displacements, are developed. Finally, nodal force vector and consistent stiffness matrix are developed for a two-dimensional interface element, showing the symmetry condition of the geometric stiffness matrix, if the second order derivative are not neglected. The proposed interface formulation is implemented in the FEAP finite element code [7] and the cohesive formulation proposed in [8] is considered as constitutive model. Results of numerical some simulations are proposed with times of convergence obtained with a symmetric solver

Robustness of solutions to the capacitated facility location problem with uncertain demand

We investigate the properties of robust solutions of the Capacitated Facility Location Problem with uncertain demand. We show that the monotonic behavior of the price of robustness is not guaranteed, and therefore that one cannot discriminate among alternative robust solutions by simply relying on the trade-off price-vs-robustness. Furthermore, we report a computational study on benchmark instances from the literature and on instances derived from a real-world application, which demonstrates the validity in practice of our findings

MicroRNA-551b expression profile in low and high-grade cervical intraepithelial neoplasia

OBJECTIVE: To evaluate the expression of microRNA (miR)-551b in patients with low and high grade cervical intraepithelial neoplasia (CIN) and to find an association with high-risk Human Papillomavirus (HR-HPV) infection-related prognostic biomarkers. PATIENTS AND METHODS: The expression level of miR-551b was determined in 50 paraffin-embedded cervical specimens (10 normal squamous epithelium, 18 condylomas, 8 CIN1, and 14 CIN2-3) using quantitative Real-time polymerase chain reaction (qRT-PCR). χ2-test compared miR-551b expression in different diagnosis groups. An Ordered Logistic Regression and a Probit correlation were made to correlate miR-551b expression levels with the cervical tissue histological findings. The immunohistochemical distribution of p16 and Ki-67 according to histopathological findings was also assessed. RESULTS: The distribution of the miR-551b expression profile was significantly lower in CIN1-3 samples compared to other histological diagnosis groups (condyloma and negative). The expression levels were inversely correlated to the cervical pathological grade, from negative to CIN2-3. A 1% increase in miR-551b expression level produced an increase of 19% to the probability of a minor histological grade diagnosis in a range from negative to CIN2-3 and an increase of 13% to the probability of a negative histological grade diagnosis. Among the cases with miR-551b expression < 0.02 (considered as cut-off value) a significant statistical correlation was found between p16 and Ki-67 expression and the diagnosis of CIN2-3. CONCLUSIONS: O ur d ata s howed a s ignificant inverse correlation between miR-551b expression and the histological grading of the lesions, suggesting a tumor suppressive function in the different stages of cervical dysplasia

Microfluidic mixing of low viscosity Boger fluids

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.This study is focused on the development of low viscosity Boger fluids and on the investigation of their elasticity on emulsion formation. Non-Newtonian continuous phases (Boger fluids) made of two different molecular weight Polyacrylamide in water plus glycerol solutions were used. While, as Newtonian continuous phase, a water plus glycerol solution showing the same viscosity as the non-Newtonian one was prepared and as dispersed phase silicon oil was used. Visualization of these emulsions flowing through a micromixer was useful in order to extract quantitative informations of their behavior, such as the velocity profile and droplets’ size distribution. Then the formation of vortex upstream of a divergent-convergent configuration has been shown as the wall migration effect, which drives droplets away from the walls and toward the center of the microcapillary investigated

Prolonged antimicrobial activity of PMMA bone cement with embedded gentamicin-releasing silica nanocarriers

Antibiotic laden bone cements are regularly employed to prevent infections after joint replacement surgeries. We have developed silica nanocarriers loaded with gentamicin as a drug delivery system to be dispersed in poly methyl-methacrylate (PMMA) bone cement for controlling and extending the release of the antibiotic from bone cements, thus proving a prolonged antimicrobial activity. Layer-by-layer self-assembly was used to deposit gentamicin between alginate layers and two different poly β-amino esters on the silica nanoparticles. The release of gentamicin from PMMA bone cement containing silica nanocarriers continued for about 30 days compared to 6 days when the same amount of antibiotic was added as a pure powder (as in commercial formulations); moreover, the medium containing the released antimicrobial drug was capable of preventing the growth of numerous bacteria species responsible for prosthetic joint infections (both catalogue strains and clinical isolates) for longer periods of time than in the case of commercial formulations, thus confirming the extended antimicrobial properties of the drug once released from the carrier. No detrimental effects toward human osteoblasts were also observed; moreover, bone cement material characteristics such as curing time, water uptake, and mechanical properties were unaffected when the silica nanocarriers were added

Microfluidic interactions between red blood cells and drug carriers by image analysis techniques

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.Blood is a complex biological fluid composed of deformable cells and platelets suspended in plasma, a protein-rich liquid. The peculiar nature of blood needs to be considered when designing a drug delivery strategy based on systemically administered carriers. Here, we report on an in vitro fluid dynamic investigation of the influence of the microcapillary flow of red blood cells (RBCs) on micron sized carriers by high speed imaging methods. The experiments were carried out in a 50μm diameter glass capillary that mimicked the hydrodynamic conditions of human microcirculation. Spherical μ particles (μ-Ps), with sizes ranging between 0.5 and 3μm, were tested. Images of the flowing RBCs and μ-Ps were acquired by a highspeed/ high-magnification microscopy. The transport and distribution of rigid particles in a suspension of RBCs under shear flow were followed for: i) the migration of RBCs towards the vessel centerline due to their deformability; ii) the cross-flow migration of μ-Ps towards the vessel wall due to their hydrodynamic interactions with RBCs; iii) the radial distribution of μ-Ps in the presence of RBCs. This study suggests that the therapeutic efficacy of μ-Ps could be ultimately affected by their interactions with the flowing RBCs in the vasculature

Preterm birth after loop electrosurgical excision procedure (LEEP). how cone features and microbiota could influence the pregnancy outcome

OBJECTIVE: In the last years, the mean age of women who underwent cervical treatment for high-grade cervical intraepithelial neoplasia (CIN 2-3) is similar to the age of women having their first pregnancy. The aim of this study was to evaluate the risk of preterm birth in subsequent pregnancies after loop electrosurgical excision procedure (LEEP). PATIENTS AND METHODS: From January 2013 to January 2016 the study identified a total of 1435 women, nulliparous, who underwent LEEP for CIN 2-3, and who wished to have their first pregnancy. Before surgery, the lengths of the cervix were calculated by transvaginal sonography. After the treatment, the dimension of the removed tissue was evaluated. During the pregnancy, all women carried out periodic transvaginal sonography and vaginal-cervical swabs. RESULTS: The average age of patients was 31.96±5.24 years; the interval between the surgical procedure and pregnancy was 12.04±4.67 months; the gestational age at births was 37.53±2.91 weeks. The first vaginal and cervical swab performed during pregnancy was negative in 81.8% of patients. The most prevalent infections were related to C. Albicans, G. Vaginalis, and Group B Streptococcus (GBS). The rate of preterm delivery was significantly higher in women with a minor cervical length. CONCLUSIONS: The length and the volume of cervical tissue excised have been shown to be directly related to the risk for preterm birth. Furthermore, vaginal infections and their persistence during pregnancy in women with a history of LEEP may be associated with an increased risk for preterm birth, compared with women with no history of LEEP

Exposure to Endocrine Disruptors and Nuclear Receptors Gene Expression in Infertile and Fertile Men from Italian Areas with Different Environmental Features

Internal levels of selected endocrine disruptors (EDs) (i.e., perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), di-2-ethylhexyl-phthalate (DEHP), mono-(2-ethylhexyl)-phthalate (MEHP), and bisphenol A (BPA)) were analyzed in blood/serum of infertile and fertile men from metropolitan, urban and rural Italian areas. PFOS and PFOA levels were also evaluated in seminal plasma. In peripheral blood mononuclear cells (PBMCs) of same subjects, gene expression levels of a panel of nuclear receptors (NRs), namely estrogen receptor α (ERα) estrogen receptor β (ERβ), androgen receptor (AR), aryl hydrocarbon receptor (AhR), peroxisome proliferator-activated receptor γ (PPARγ) and pregnane X receptor (PXR) were also assessed. Infertile men from the metropolitan area had significantly higher levels of BPA and gene expression of all NRs, except PPARγ, compared to subjects from other areas. Subjects from urban areas had significantly higher levels of MEHP, whereas subjects from rural area had higher levels of PFOA in both blood and seminal plasma. Interestingly, ERα, ERβ, AR, PXR and AhR expression is directly correlated with BPA and inversely correlated with PFOA serum levels. Our study indicates the relevance of the living environment when investigating the exposure to specific EDs. Moreover, the NRs panel in PBMCs demonstrated to be a potential biomarker of effect to assess the EDs impact on reproductive health