Nondestructive in-line sub-picomolar detection of magnetic nanoparticles in flowing complex fluids

Over the last decades, the use of magnetic nanoparticles in research and commercial applications has increased dramatically. However, direct detection of trace quantities remains a challenge in terms of equipment cost, operating conditions and data acquisition times, especially in flowing conditions within complex media. Here we present the in-line, non-destructive detection of magnetic nanoparticles using high performance atomic magnetometers at ambient conditions in flowing media. We achieve sub-picomolar sensitivities measuring $\sim$30 nm ferromagnetic iron and cobalt nanoparticles that are suitable for biomedical and industrial applications, under flowing conditions in water and whole blood. Additionally, we demonstrate real-time surveillance of the magnetic separation of nanoparticles from water and whole blood. Overall our system has the merit of inline direct measurement of trace quantities of ferromagnetic nanoparticles with so far unreached sensitivities and could be applied in the biomedical field (diagnostics and therapeutics) but also in the industrial sector

A Study of the Physical-Chemical Mechanisms and Variables Which Affect the Transport of Inorganic and Organic Heterogeneous Systems

In order to model transport of dissolved ions in subsurface environments, one should understand how these ions interact with solid phase adsorbents. Our primary goal has been investigating the reaction mechanisms which affect microcontaminant partitioning between aqueous solutions and solid phase adsorbents, using goethite ({alpha}-FeOOH) as a model adsorbent. Cylindrical internal reflection -- Fourier transform infrared (CIR-FTIR) spectroscopy has been developed as the primary technique for this study. Wet chemical adsorption studies, acoustophoresis and electrophoretic mobility have been used to obtain supporting information as needed. Phenol and o-nitrophenol did not adsorb to goethite. Benzoate, phthalate and p-hydroxybenzoate all adsorbed via a bidentate mechanism to two adjacent iron atoms, while salicylate and 2,4-dihydroxybenzoate formed a chelate complex to single iron atoms. Phosphate adsorption was predominately bidentate

Ordered ceramic membranes

Ceramic membranes have been formed from colloidal sols coated on porous clay supports. These supported membranes have been characterized in terms of their permeabilities and permselectivities to various aqueous test solutions. The thermal stabilities and pore structures of these membranes have been characterized by preparing unsupported membranes of the correpsonding material and performing N{sub 2} adsorption-desorption and X-ray diffraction studies on these membranes. To date, membranes have been prepared from a variety of oxides, including TiO{sub 2}, SiO{sub 2}, ZrO{sub 2}, and Al{sub 2}O{sub 3}, as well as Zr-, Fe-, and Nb-doped TiO{sub 2}. In many of these membranes pore diameters are less than 2 nm, while in others the pore diameters are between 3 and 5 nm. Procedures for fabricating porous clay supports with reproducible permeabilities for pure water are also discussed. 30 refs., 59 figs., 22 tabs

G-protein beta(3) subunit gene (GNB3) 825T allele is associated with enhanced renal perfusion in early hypertension

The C825T polymorphism of the gene encoding the G-protein beta(3) subunit (GNB3) is associated with increased intracellular signal transduction and arterial hypertension. The aim of the study was to investigate the impact of this polymorphism on early adaptive processes of the left ventricle and renal hemodynamic changes in young normotensive to mildly hypertensive subjects. Ninety-five white male students with normal or mildly elevated blood pressure were genotyped for the GNB3 C825T polymorphism. In each participant, 24-hour ambulatory blood pressure, left ventricular structure and function (2D-guided M-mode echocardiography), renal plasma flow (para-aminohippurate clearance), glomerular filtration rate (inulin clearance), and 24-hour urinary sodium excretion were determined. The GNB3 825T allele was not associated with casual or ambulatory blood pressure, parameters of left ventricular structure or function, glomerular filtration, or 24-hour urinary sodium excretion. However, in T:-allele carriers (CT+TT), renal plasma flow was higher than in CC subjects (CT/TT: 659+/-96 versus CC: 614+/-91 mL/min, P:=0.019). ANOVA disclosed that renal plasma flow was independently influenced by both genotype and blood pressure, with hypertensives having a higher renal plasma flow than normotensive subjects. This was the fact irrespective of the criteria used for the definition of hypertension (World Health Organization or 24-hour ambulatory blood pressure criteria). The GNB3 825T variant is associated with increased renal perfusion in this study. Because early renal hemodynamic changes play a pivotal role in the pathogenesis of essential hypertension, our data suggest a relevance of increased G-protein activation in the pathogenesis of hypertension

Base-free Knoevenagel condensation catalyzed by copper metal surfaces

ISSN:1359-7345ISSN:1364-548

A sensor for monitoring the volume of nutrient in a solid substrate-based growth media by using electrochemical admittance spectroscopy

A sensor was fashioned to monitor the volume of nutrient in a solid substrate-based growth media by using electrochemical admittance spectroscopy. Several experimental parameters were investigated (i.e. The use of two- or three-electrode cells, the superficial area of the electrode, the amount of nutrient solution added to the growth media, and the influence of varying the dc and ac potential) to assess how these variables affect the admittance of the system. A linear correlation was observed between the maximum of the imaginary admittance and the volume of nutrient present. The response factor was 2.8 x 10(-5) S cm(-2) ml(-1) and the limit of detection (LOD) was 0.54 ml. The humidity of the growth media does not change the response of the nutrient toward the monitoring measurements. These results demonstrate that the volume of nutrient in this solid substrate-based growth media can be assessed using a ceramic sensor to measure the imaginary admittance. (C) 2002 Elsevier B.V. B.V. All rights reserved