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

Possible Recycling of End-of-Life Dolomite Refractories by the Production of Geopolymer-Based Composites: Experimental Investigation

Production and characterization of geopolymers prepared by mixing metakaolin, end-of-life dolomite refractories, sodium silicate solution, and sodium hydroxide solution have been performed. The as-received refractory was crumbled in order to obtain products having, respectively, 250\ua0\u3bcm, 1 mm, and 2.5\ua0mm maximum particles size. Each batch of powder was added in different proportions to a blank geopolymeric matrix. It has been observed that the addition of waste refractory reduces workability of the reference refractory-free slurry. After hardening, only the set of samples prepared with powders with maximum size of 250\ua0\u3bcm maintain integrity while the others resulted affected by the presence of fractures caused by volumetric instabilities; samples with composition R100 showed the highest compressive strength, whereas higher refractory addition lowers strength. Specific surface area appears independent by materials composition; conversely pore volume slightly increases with the addition of dolomite refractory powder. During the thermodilatometric tests all compositions display a shrinkage of about 0.1% between 170 and 400\ua0\ub0C; however, sintering starts at higher temperature (above 600\ua0\ub0C) and samples melt in the range between 650 and 750\ua0\ub0C as a function of their composition, thus showing that the resulting materials loose refractoriness with respect to both the reference geopolymer and the dolomite refractory. Graphical Abstract: [Figure not available: see fulltext.

Analysis of Particle Transport in a Magnetophoretic Microsystem

An analytical analysis is presented of the transport and capture of magnetic micro/nano-particles in a magnetophoretic microsystem that consists of an array of integrated soft-magnetic elements embedded beneath a microfluidic channel. The elements, which are polarized by a bias field, produce a nonuniform field distribution that gives rise to a force on magnetic particles within the microchannel. The equations governing particle motion are derived using analytical expressions for the dominant magnetic and fluidic forces. The magnetic force is obtained using an analytical expression for the field distribution in the microchannel combined with a linear magnetization model for the magnetic response of particles. The theory takes into account particle size and material properties, the bias field, the dimensions of the microchannel, the fluid properties, and the flow velocity. The equations of motion are solved to study particle transport and capture. The analysis indicates that the particles exhibit an oscillatory motion as they traverse the microsystem, and that a high capture efficiency can be obtained in practice

Integrated Geomechanical and Digital Photogrammetric Survey in the Study of Slope Instability Processes of a Flysch Sea Cliff (Debeli Rtič Promontory, Slovenia)

This work presents an integrated study approach that combines the results of a geomechanical survey with data obtained using digital photogrammetry (DP), to assess slope instability processes affecting a sea cliff at the Debeli Rtič promontory (Slovenia). The investigated cliff is 4–18 m-high and is made up of an alternation of sandstones and marlstones belonging to the Flysch Formation of Trieste, which is Eocene in age. The studied cliff was subjected to localized slope failures that occurred in the past and is currently subject to frequent rock collapses, thus resulting in its partial and episodic retreat. Field evidence acquired through a traditional survey was integrated with outputs of the DP technique based on 1399 images that were collected using both a commercial unmanned aerial vehicle (UAV) and a mobile phone (MP). UAV-derived images were useful for performing rock mass structure analysis in the upper part of the investigated cliff, where the traditional survey was not possible due to hazardous operating conditions. In addition, the use of a MP was observed to be a useful tool for the rapid collection of images at the toe of unsafe marine cliff environments. This study highlights that UAV-DP and MP-DP techniques can only be effective if the outcomes obtained from the 3D model reconstruction are validated by direct measurements acquired by means of the traditional field survey, thus avoiding improper or even erroneous results while enlarging the amount of data and the area of investigation. The study approach presented herein allowed for the assessment of slope instabilities affecting the Flysch Sea cliff, whose retreat is caused by the combined action of marine erosion and slope gravitational processes

Integrated Geomechanical and Digital Photogrammetric Survey in the Study of Slope Instability Processes of a Flysch Sea Cliff (Debeli Rtic Promontory, Slovenia)

This work presents an integrated study approach that combines the results of a geomechanical survey with data obtained using digital photogrammetry (DP), to assess slope instability processes affecting a sea cliff at the Debeli Rtic promontory (Slovenia). The investigated cliff is 4-18 m-high and is made up of an alternation of sandstones and marlstones belonging to the Flysch Formation of Trieste, which is Eocene in age. The studied cliff was subjected to localized slope failures that occurred in the past and is currently subject to frequent rock collapses, thus resulting in its partial and episodic retreat. Field evidence acquired through a traditional survey was integrated with outputs of the DP technique based on 1399 images that were collected using both a commercial unmanned aerial vehicle (UAV) and a mobile phone (MP). UAV-derived images were useful for performing rock mass structure analysis in the upper part of the investigated cliff, where the traditional survey was not possible due to hazardous operating conditions. In addition, the use of a MP was observed to be a useful tool for the rapid collection of images at the toe of unsafe marine cliff environments. This study highlights that UAV-DP and MP-DP techniques can only be effective if the outcomes obtained from the 3D model reconstruction are validated by direct measurements acquired by means of the traditional field survey, thus avoiding improper or even erroneous results while enlarging the amount of data and the area of investigation. The study approach presented herein allowed for the assessment of slope instabilities affecting the Flysch Sea cliff, whose retreat is caused by the combined action of marine erosion and slope gravitational processes

Automação de balanças comerciais como lisímetros em ambiente protegido.

bitstream/CNPDIA-2009-09/11843/1/CT80_2006.pd

Resposta diferencial de genótipos de sorgo para tolerância ao alumínio em solução nutritiva.

Neste trabalho utilizou-se de uma tecnica de solucao nutritiva para identificar, dentre 391 linhagens de sorgo (BAG-Sorgo; 181), CNPMS: 71, SEPON/ICRISAT: 17 e Sacarino: 122, os genotipos que apresentam tolerancia ao aluminio. A avaliacao do comportamento diferencial dessas linhagens baseou-se no crescimento da raiz seminal primaria de plantas jovens de sorgo, em solucao nutritiva contendo niveis variados de Al (0,0, 2,25 e 4,5 mg de Al/1 para sorgo granifero e 0,0, 2,25 e 5,0 mg de Al/1 para sorgo sacarino). A caracteristica usada para a comparacao entre genotipos foi o Comprimento Relativo da Raiz Seminal (CRSS = CRS + AL/CRS - Al, onde CRS = comprimento da Raiz Seminal). Baseando-se na distribuicao percentual dos valores de CRRS obtidos para as diferentes linhagens e nos valores de CRRS encontrados para os materiais controles SC 298 (sensivel ao Al) e SC 283 (tolerante ao Al) tres classes de resposta ao aluminio foram definidas: Sensivel (CRRS 0,70). Dentre os materiais avaliados as seguintes linhagens apresentaram tolerancia aos niveis de 4,5 ou 5,0 mg de Al/1: IS 3625, IS 7173 C (SC 283), IS 12666, 5DX61/6/2, 3DX57/1/1910, 156-P-5-Serere-1, 9DX9/11, Brandes, MN 4004 e MN 1204

The Effect of the P/Si Ratio on the Preparation and Properties of Phosphoric Acid-Metakaolin Geopolymers

The present research deals with the production and characterization of geopolymers prepared by mixing metakaolin, different amounts of phosphoric acid solution and water. Hardening was performed by aging the geopolymeric pastes in a climatic chamber. The workability of the pastes has been improved while the H2O/total solid content has been kept constant and the P/Si ratio increased. However, such a benefit implies considerable heat output, which must be controlled in order to limit the formation of extended fractures. The compressive strength of the hardened materials increases with increasing P/Si ratio at a constant H2O/total solid content, whereas their strength decreases with increasing H2O/ total solid content at a constant P/Si ratio. The open macroporosity, which is directly dependent on the total amount of water added to the geopolymeric pastes, may explain the above results better than the nano/microporosity and/or chemical bonds that contribute to building up the materials\u2019 textural features