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An ultrasonic particle concentrator based on a standing-wave hemispherical resonator is combined with confocal laser-scanning fluorescence detection. The goal is to perform ultrasensitive biomedical analysis by concentration of biologically active microspheres. The standing-wave resonator consists of a 4 MHz focusing ultrasonic transducer combined with the optically transparent plastic bottom of a disposable 96-well microplate platform. The ultrasonic particle concentrator collects suspended microspheres into dense, single-layer aggregates at well-defined positions in the sample vessel of the microplate, and the fluorescence from the aggregates is detected by the confocal laser-scanning system. The biochemical properties of the system are investigated using a microsphere-based human thyroid stimulating hormone assay. [ABSTRACT FROM AUTHOR]

A longitudinal hemispherical standing-wave ultrasonic trap for size-selective separation of microspheres in small-diameter capillaries is described. The trap utilizes the competition between acoustic radiation forces and viscous drag forces on spheres suspended in a liquid inside 20-75-μm-diam fused silica capillaries. Experiments performed on 3.0- and 4.7-μm-diam latex spheres demonstrate the principles of trapping and verify the theoretically calculated size-dependent forces on the spheres. The spheres are detected by the use of laser-induced fluorescence. The goal is to use the trap for separation and ultrahigh-sensitivity detection of trace amounts of proteins and other macromolecules containing two antigenic sites, by binding the target molecule with high specificity to antibody-coated latex spheres. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We combine ultrasonic trapping and capillary electrophoresis (CE) with the goal to detect ultra-low concentrations of proteins via size-selective separation and enrichment of antibody-coated latex spheres. An 8.5 MHz standing ultrasonic wave is longitudinally coupled into the sub-100-μm diam capillary of the CE system. Competition between acoustic and viscous forces result in in-flow separation of μm-diam spheres according to their size. Experiments separating 2.8- and 2.1-μm-diam fluorescent latex particles, which model a protein-specific immunocomplex/free particle mixture, indicate a potential improvement of the concentration limit of detection of 104 compared to current CE systems. Theoretical calculations show room for further improvement. [Copyright &y& Elsevier]

Practitioners designing for mobile learning (mLearning) and scholars exploring the same are faced with the challenge of planning for and understanding a variety of ways and places of learning. This study focuses on one crucial distinction concerning this; that of formal and informal learning. Through the analysis of contemporary research literature, we found that informal learning is represented as more enriching than formal learning. We also identified that some representations of informal learning, such as subconscious and tacit, actually gainsay the idea of designing the learning process. Based on these results we propose a number of implications to enhance pedagogical sustainability in mLearning design. We argue that in order to fuse informal and formal learning, mLearning designers need to offer more clear definitions of the concepts "formal" and "informal"; they need to omit some design aspects to the learners themselves, or to offer a design in form of a learning path that students themselves can customise according to their learning habits, routines, and preferences. [ABSTRACT FROM AUTHOR]

Objective To study symptom panorama in students, to identify undiagnosed iron deficiency, and to evaluate any changes in symptoms and laboratory test results after treatment with iron supplementation. Design Descriptive and prospective, interventional study. Setting Healthcare in upper secondary school. Intervention Treatment with iron supplementation for a period of 3 months. Subjects Students in the first grade of one upper secondary school. Main outcome measures Frequency of iron deficiency related to symptoms measured by a questionnaire (30 questions) on symptoms related to quality of life and 9 questions about diet and exercise. Results Iron deficiency was diagnosed in 12% of the students (two or more abnormal laboratory tests) and in 61% of the students one or more laboratory tests were abnormal. Symptoms of vertigo/dizziness were significantly more common in students with iron deficiency. After iron supplementation there was a significant increase in s-ferritin levels and a decrease in s-transferrin levels, with an accompanying significant reduction of the symptom scores of vertigo/dizziness, irritability, depressive symptoms, and indisposition. Conclusions Symptoms of vertigo/dizziness were significantly more common in students with iron deficiency. Iron supplementation reduced the symptoms of vertigo/dizziness, irritability, depressive symptoms, and indisposition. [ABSTRACT FROM AUTHOR]

Understanding the complex 3D tumor microenvironment is important in cancer research. This microenvironment can be modelled in vitro by culturing multicellular tumor spheroids (MCTS). Key challenges when using MCTS in applications such as high-throughput drug screening are overcoming imaging and analytical issues encountered during functional and structural investigations. To address these challenges, we use an ultrasonic standing wave (USW) based MCTS culture platform for parallel formation, staining and imaging of 100 whole MCTS. A protein repellent amphiphilic polymer coating enables flexible production of high quality and unanchored MCTS. This enables high-content multimode analysis based on flow cytometry and in situ optical microscopy. We use HepG2 hepatocellular carcinoma, A498 and ACHN renal carcinoma, and LUTC-2 thyroid carcinoma cell lines to demonstrate (i) the importance of the ultrasound–coating combination, (ii) bright field image based automatic characterization of MTCS, (iii) detailed deep tissue confocal imaging of whole MCTS mounted in a refractive index matching solution, and (iv) single cell functional analysis through flow cytometry of single cell suspensions of disintegrated MTCS. The USW MCTS culture platform is customizable and holds great potential for detailed multimode MCTS analysis in a high-content manner. [ABSTRACT FROM AUTHOR]

We present a tunable-angle wedge ultrasound transducer for improved control of microparticle acoustophoresis in a microfluidic chip. The transducer is investigated by analyzing the pattern of aligned particles and induced acoustic energy density while varying the transducer geometry, transducer coupling angle, and transducer actuation method (single-frequency actuation or frequency-modulation actuation). The energy-density analysis is based on measuring the transmitted light intensity through a microfluidic channel filled with a suspension of 5 µm diameter beads and the results with the tunable-angle transducer are compared with the results from actuation by a standard planar transducer in order to decouple the influence from change in coupling angle and change in transducer geometry. We find in this work that the transducer coupling angle is the more important parameter compared to the concomitant change in geometry and that the coupling angle may be used as an additional tuning parameter for improved acoustophoretic control with single-frequency actuation. Further, we find that frequency-modulation actuation is suitable for diminishing such tuning effects and that it is a robust method to produce uniform particle patterns with average acoustic energy densities comparable to those obtained using single-frequency actuation. [ABSTRACT FROM AUTHOR]

Objectives: To design and validate a scoring system for tomosynthesis (digital tomography) in pulmonary cystic fibrosis.Methods: A scoring system dedicated to tomosynthesis in pulmonary cystic fibrosis was designed. Three radiologists independently scored 88 pairs of radiographs and tomosynthesis examinations of the chest in 60 patients with cystic fibrosis and 7 oncology patients. Radiographs were scored according to the Brasfield scoring system and tomosynthesis examinations were scored using the new scoring system.Results: Observer agreements for the tomosynthesis score were almost perfect for the total score with square-weighted kappa >0.90, and generally substantial to almost perfect for subscores. Correlation between the tomosynthesis score and the Brasfield score was good for the three observers (Kendall's rank correlation tau 0.68, 0.77 and 0.78). Tomosynthesis was generally scored higher as a percentage of the maximum score. Observer agreements for the total score for Brasfield score were almost perfect (square-weighted kappa 0.80, 0.81 and 0.85).Conclusions: The tomosynthesis scoring system seems robust and correlates well with the Brasfield score. Compared with radiography, tomosynthesis is more sensitive to cystic fibrosis changes, especially bronchiectasis and mucus plugging, and the new tomosynthesis scoring system offers the possibility of more detailed and accurate scoring of disease severity.Key Points: Tomosynthesis is more sensitive than conventional radiography for pulmonary cystic fibrosis changes. The radiation dose from chest tomosynthesis is low compared with computed tomography. Tomosynthesis may become useful in the regular follow-up of patients with cystic fibrosis. [ABSTRACT FROM AUTHOR]

Surface acoustic wave (SAW) excitation of an acoustic field in a trapezoidal glass microfluidic channel for particle manipulation in continuous flow has been demonstrated. A unidirectional interdigital transducer (IDT) on a Y-cut Z-propagation lithium niobate (LiNbO3) substrate was used to excite a surface acoustic wave at approximately 35 MHz. An SU8 layer was used for adhesive bonding of the superstrate glass layer and the substrate piezoelectric layer. This work extends the use of SAWs for acoustic manipulation to also include glass channels in addition to prior work with mainly poly-di-methyl-siloxane channels. Efficient alignment of 1.9 µm polystyrene particles to narrow nodal regions was successfully demonstrated. In addition, particle alignment with only one IDT active was realized. A finite element method simulation was used to visualize the acoustic field generated in the channel and the possibility of 2D alignment into small nodal regions was demonstrated [ABSTRACT FROM AUTHOR]

We demonstrate flow-free transport of cells and particles by the use of frequency-modulated ultrasonic actuation of a microfluidic chip. Two different modulation schemes are combined: A rapid (1 kHz) linear frequency sweep around ∼6.9 MHz is used for two-dimensional spatial stabilization of the force field over a 5 mm long inlet channel of constant cross section, and a slow (0.2–0.7 Hz) linear frequency sweep around ∼2.6 MHz is used for flow-free ultrasonic transport and positioning of cells or particles. The method is used for controlling the motion and position of cells monitored with high-resolution optical microscopy, but can also be used more generally for improving the robustness and performance of ultrasonic manipulation micro-devices. [ABSTRACT FROM AUTHOR]

Abstract: Ultrasonic-standing-wave (USW) technology has potential to become a standard method for gentle and contactless cell handling in microfluidic chips. We investigate the viability of adherent cells exposed to USWs by studying the proliferation rate of recultured cells following ultrasonic trapping and aggregation of low cell numbers in a microfluidic chip. The cells form 2-D aggregates inside the chip and the aggregates are held against a continuous flow of cell culture medium perpendicular to the propagation direction of the standing wave. No deviations in the doubling time from expected values (24 to 48 h) were observed for COS-7 cells held in the trap at acoustic pressure amplitudes up to 0.85 MPa and for times ranging between 30 and 75 min. Thus, the results demonstrate the potential of ultrasonic standing waves as a tool for gentle manipulation of low cell numbers in microfluidic systems. (E-mail: jessica.hultstrom@biox.kth.se) [Copyright &y& Elsevier]