710 research outputs found
Continuous Magnetophoretic Separation of Blood Cells from Plasma at the Microscale
We present a method for the direct and continuous separation of red and white
blood cells from plasma at the microscale. The method is implemented in a
microfluidic system with magnetic functionality. The fluidic structure within
the microsystem consists of an inlet and a single microfluidic channel with
multiple outlets. The magnetic functionality is provided by an array of
integrated soft-magnetic elements that are embedded transverse and adjacent to
the microchannel. The elements are magnetized using an external field, and once
magnetized they produce a magnetic force on blood cells as they flow through
the microchannel. In whole blood, white blood cells (WBCs) behave as
diamagnetic microparticles, while red blood cells (RBCs) exhibit diamagnetic or
paramagnetic behavior depending on the oxygenation of their hemoglobin. We
study the motion of blood cells through the microchannel using a mathematical
model that takes into account the magnetic, fluidic and gravitational forces on
the cells. We use the model to study blood cell separation, and our analysis
indicates that the microsystem is capable of separating WBC-rich plasma,
deoxygenated RBC-rich plasma and cell-depleted plasma into respective outlets.Comment: Submitted to Journal of Applied Physic
N-isopropyl chitosan. A pH- and thermo-responsive polysaccharide for gel formation
The present contribution deals with the synthesis and characterization of N-isopropyl chitosan in which the introduction of hydrophobic groups leads to an increased flexibility of the polysaccharide backbone. The isopropyl groups extend the solubility of the modified-chitosan samples and render the modified chitosan a pH- and thermo-sensitive system for hydrogel formation. Indeed, upon varying the pH of the system and/or its temperature within a range compatible with biological applications, a non-reversible sol-gel transition occurs, as determined through extended rheological analyses. The modified chitosan samples show a very good biocompatibility as determined through preliminary viability and cell growth experiments
Synthesis, crystallographic characterization, and mechanical behavior of alumina chromia alloys
Powder mixtures of Alumina and Chromia, blended in different proportions (1, 3, 5 and 10%wt) by attrition milling, were fired either by pressureless sintering in air and hot pressing under vacuum. The resulting materials, characterized by X-ray diffraction, Raman spectroscopy, SEM, hardness and fracture toughness showed that all the compositions form complete solid solution which maintain the same crystal structures of corundum; chromia addition retards materials' densification of pressureless fired samples but not that of hot-pressed samples. Data from Raman spectroscopy and SEM/EDXS showed the appearance of Ti- and Mn-based impurities near the indentation print, in particular on fractured grains. The addition of chromia improves hardness, but does not affect toughness which is, on the other hand, greatly influenced by materials\u2019 residual porosity
Temporary/Permanent Dual Cross-Link Gels Formed of a Bioactive Lactose-Modified Chitosan
Mounting evidences have recognized that dual cross-link and double-network gels can promisingly recapitulate the complex living tissue architecture and overcome mechanical limitations of conventional scaffolds used hitherto in regenerative medicine. Here, dual cross-link gels formed of a bioactive lactose-modified chitosan reticulated via both temporary (boric acid-based) and permanent (genipin-based) cross-linkers are reported. While boric acid rapidly binds to lactitol flanking diols increasing the overall viscosity, a slow temperature-driven genipin binding process takes place allowing for network strengthening. Combination of frequency and stress sweep experiments in the linear stress\u2013strain region shows that ultimate gel strength, toughness, and viscoelasticity depend on polymer-to-genipin molar ratio. Notably, herewith it is demonstrated that linear stretching correlates with strain energy dissipation through boric acid binding/unbinding dynamics. Strain-hardening effect in the nonlinear regime, along with good biocompatibility in vitro, points at an interesting role of present system as biological extracellular matrix substitute
Ocorrência de adultos de Drosophila suzukii (Matsumura, 1931) (Diptera: Drosophilidae) em pontos comerciais na área urbana de Vacaria-RS.
Este estudo teve como objetivos avaliar a ocorrência de exemplares adultos de D. suzukii nas proximidades de mercados de comercialização de frutas em área urbana
Prehistoric stone disks from entrances and cemeteries of north-eastern Adriatic hillforts|Prazgodovinski kamniti diski z vhodov in grobi[; na gradi[;ih na severovzhodnem Jadranu
The paper presents a group of four, approximately 0.5m large, stone disks from entrances or cemeteries of two protohistoric hillforts of north-eastern Adriatic. The disks, having a sparse chronology with the exception of one dated to the Middle Bronze Age, show flat and plain surfaces or covered with sub-circular depressions. One disk shows two larger cup-marks at the centre of both faces. They are interpreted as ritual artefacts based on the association with sacred settlement locations and comparisons with similar coeval stones found mainly close to citadel entrances, burials and thresholds in the Aegean area and Anatolia
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