Tracking biological cells in time-lapse microscopy: an adaptive technique combining motion and topological features

This paper presents a vision-based method for automatic tracking of biological cells in time-lapse microscopy by combining the motion features with the topological features of the cells. The automation of tracking frequently faces problems of segmentation error and of finding correct cell correspondence in consecutive frames, since the cells are of varying size and shape, and may have uneven movement; these problems become more acute when the cell population is very high. To reduce the segmentation error, we introduce a cell-detection method based on h-maxima transformation, followed by the fitting of an ellipse for the nucleus shape. To find the correct correspondence between the detected cells, the topological features, namely, color compatibility, area overlap and deformation are combined with the motion features of skewness and displacement. This reduces the ambiguity of matching and constructs accurately the trajectories of the cell proliferation. Finally, a template-matching-based backward tracking procedure is employed to recover any break in a cell trajectory that may occur due to the segmentation errors or the presence of a mitosis. The tracking procedure is tested using a number of different cell sequences with nonuniform illumination, or uneven cell motion, and is shown to provide high accuracy both in the detection and the tracking of the cells.     

Miscibility studies of sodium carboxymethylcellulose/poly(vinyl alcohol) blend membranes for pervaporation dehydration of isopropyl alcohol

Miscibility studies of sodium carboxymethylcellulose/poly(vinyl alcohol) (NaCMC/PVA) blends of different compositions (100/0, 80 : 20, 60 : 40, 50 : 50, 40 : 60, 20 : 80, and 0 : 100) were investigated using viscometric method. NaCMC, PVA, and their blend membranes were prepared by solution‐casting technique and were then crosslinked with glutaraldehyde (GA). The effect of blend composition on mechanical, swelling, and pervaporation results (flux and selectivity) was also investigated in this study. Attenuated total reflectance–Fourier transform infrared spectroscopy (ATR–FTIR) results showed that the blends are miscible over the entire studied composition range and further confirmed the crosslinking reaction with GA. FTIR studies reveal that the blends containing 50 : 50 (NaCMC/PVA) are an optimum miscible blend. Thermogravimetric analysis confirms that the thermal stability increased with increase in NaCMC content in NaCMC/PVA blend membrane. XRD and DSC showed a corresponding decrease in crystallinity and increase in melting point with increase in NACMC content, respectively. NaCMC/PVA blends of all the composition under study were used for dehydration of isopropyl alcohol at different compositions of IPA/water mixture (90 : 10, 87.5 : 12.5, 85 : 15, and 82.5 : 17.5) at 35°C. Swelling studies and PV results reveal that increase in NaCMC content in the blend leads to an increase in flux of water, whereas selectivity decreases. The optimum flux and selectivity were observed for the blend containing 50 : 50 NaCMC/PVA content at a feed ratio of 87.5 : 12.5 IPA/water. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation and characterization of 4A zeolite‐filled mixed matrix membranes for pervaporation dehydration of isopropyl alcohol

Sodium carboxymethylcellulose/poly (vinyl alcohol) mixed matrix membranes filled with different amounts 4A zeolite (0, 5, 10, 15, and 20 wt %) were prepared by solution casting method. Prepared membranes were crosslinked with GA and used for pervaporation dehydration of isopropyl alcohol of different feed mixtures at 35°C. On increment in zeolite content in the membrane it was found the improvement in the performance of the membrane, due to its hydrophilic nature and molecular sieving effect in addition to its favorable interaction with hydrophilic sodium carboxymethylcellulose and polyvinyl alcohol. The structure and chemical constituents of the MMM's were investigated by attenuated total reflectance Fourier transform infrared spectroscopy. Thermal stability of the membranes was assessed by DSC and TGA techniques. Crystallinity of the membranes was assessed using X‐ray diffraction, and the morphological properties were assessed by scanning electron microscopy. Mechanical properties were also carried out to determine the tensile strength and % of elongation at break using universal testing machine. It was found that the mechanical strength increases with increase in the zeolite content upto 15 wt % of zeolite with an optimum tensile strength of 113.31 N/mm². Pervaporation was carried out to asses the membrane performance, the highest flux and selectivity obtained is 0.584 kg/m²/h and 6945 for NaCMCA20 and NaCMCA15, respectively, for a feed composition containing 17.5 and 10 wt % of water in the feed and further swelling studies also supporting the pervaporation results. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

The analysis and design of two-dimensional nearly-orthogonal symmetric wavelet filter banks

The design and analysis of two-channel two-dimensional (2D) nonseparable nearly-orthogonal symmetric wavelet filter banks with quincunx decimation is studied. The basic idea is to impose multiple zeros at the aliasing frequency to a symmetric filter and minimize the deviation of the filter satisfying the orthogonal condition to obtain a nearly-orthogonal FIR filter bank. Since multiple zeros are imposed, a scaling function may be generated from the minimized filter. With this filter, a semi-orthogonal filter bank is constructed. Methods for analyzing the correlation of the semi-orthogonal filter banks are proposed. The integer translates of the wavelet and scaling function are nearly-orthogonal. The integer translates of the wavelet at different scale are completely orthogonal. The semi-orthogonal filter bank can be efficiently implemented using the corresponding nearly-orthogonal FIR filter bank.     

Evolutionary design of 2-dimensional recursive filters via the computer language GENETICA

In this paper, we present a new design method for a class of two-dimensional (2-D) recursive digital filters using an evolutionary computational system. The design of the 2-D filter is reduced to a constrained minimization problem the solution of which is achieved by the convergence of an appropriate evolutionary algorithm. In our approach, the genotypes of potential solutions have a uniform probability within the region of the search space specified by the constraints and zero probability outside this region. This approach is particularly effective as the evolutionary search considers only those potential solutions that respect the constraints. We use the computer language GENETICA, which provides the expressive power necessary to get an accurate problem formulation and supports an adjustable evolutionary computational system. Results of this procedure are illustrated by a numerical example, and compared with those of some previous designs.     

Dielectric constant variation of polystyrene-graphite composite material with temperature

Temperature variation is investigated for the dielectric constant of polystyrene-graphite composite, and variation of normalized capacitance with temperature is studied. Experimental and theoretical results, obtained through modelling, appear to match quite closely.     

Bamboo and wood fibre cement composites for sustainable infrastructure regeneration

This paper describes the development of eco-friendly bamboo and wood fibre cement composites from agriculture wastes for applications in the housing and building industries, and for sustainable infrastructure regeneration. Bamboo flakes and fibres from oil palm tree fronds were produced and tested for their sugar content and effect on the setting and strength development of the portland cement matrix. To counteract the adverse effects on cement hydration, chemical accelerators, cement replacement materials or a combination of both were used in the manufacture of the composite boards. With the bamboo, the composition of the particleboard was optimized in terms of bamboo–cement ratio and the type and amount of chemical admixture to produce a composite with satisfactory strength and dimensional stability. For the production of wood fibre cement composites, cement replacement materials such as fly ash, rice husk ash and latex were used in conjunction with chemical admixtures to counteract the adverse effect on the hydration characteristics of the cement matrix. Tests were then carried out to optimize the amount and type of cement replacement material and chemical admixtures to produce boards with adequate strength and dimensional stability. All the strength and dimensional stability tests reported in the paper were carried out according to Malaysian Standard MS 934. The paper emphasizes the need for holistic design combining chemical admixtures, cement replacement materials and modern production technology to produce a wide range of cement-bonded composite boards, which will satisfy international standards and can be widely used for infrastructure regeneration.     

On the on-line computation of DCT-IV and DST-IV transforms

Various options available for the on-line computation of discrete cosine transform-IV (DCT-IV) and discrete sine transform-IV (DST-IV) in hardware are considered and compared. A novel architecture for the simultaneous, real-time computation of both the transforms, based on the decomposition of the odd-time, odd-frequency discrete Fourier transform (O² DFT), is also proposed     

Studies on the oxidation behaviour of intermetallic compounds

The oxidation behaviour of the AB₅ type intermetallic compounds CaNi₅ and LaNi₅ has been studied at different temperatures ranging from 100 to 800° C. The kinetic results indicate that the element A (Ca, La) is first oxidized rapidly followed by slower oxidation of nickel. X-ray diffractograms of the oxidized LaNi₅ show the formation of ternary phases like LaNiO₃ and La₂NiO₄ at temperature as low as 400° C. A comparison between the oxidation behaviour of the two compounds reveals that CaNi₅ is more resistant to oxidation and decomposition than the LaNi₅ system.     

Analysis, design, and optimization of a secondary-side resonantconverter operating in the discontinuous capacitor voltage mode

A high-frequency link parallel resonant DC/DC power converter (PRC) operating in the lagging power factor mode with the resonating capacitor on the secondary side of the high-frequency (HF) transformer is analyzed for operation in the discontinuous capacitor voltage mode (DCVM) using a state-space approach. Converter equations are solved for operation under steady-state condition. Based on the analysis, design curves are obtained for DCVM operation. A method of obtaining the optimum operating point under certain constraints for DCVM operation is developed and is used to develop a simple design procedure. Experimental results obtained with a MOSFET-based 1 kW PRC are presented to support the theory