|
| ||
|
|
||
Cell Diameter (cell + diameter)
Selected AbstractsChloroplast rotation and morphological plasticity of the unicellular alga Rhodosorus (Rhodophyta, Stylonematales)PHYCOLOGICAL RESEARCH, Issue 3 2002Sarah Wilson SUMMARY Time-lapse videomicroscopy was used to film chloroplast rotation in the 13 isolates of Rhodosorus marinus Geitler and one isolate of Rhodosorus magnei Fresnel & Billard maintained in culture. Cell diameter, rates of chloroplast rotation and the number of chloroplast lobes were measured in all isolates. Chloroplast rotation is a definitive characteristic of the genus Rhodosorus and should be included in its taxonomic description. Isolates of the type species, R. marinus, measure 4,7 ,m in diameter in low light (2,4 ,mol photons m,2 s,1) and 4.5,11.5 ,m in diameter in bright light (15,20 ,mol photons m,2 s,1), and have two to seven chloroplast lobes. Rhodosorus magnei is 9 ,m in diameter and has seven to nine chloroplast lobes in bright light. However, these cells are much smaller (approx. 4 ,m diam.) and have only two to three chloroplast lobes when maintained in low light. The species R. magnei was created based on its larger cell size and numerous chloroplast lobes compared with R. marinus, but since these characteristics were found to be quite variable and dependant on culture conditions, they cannot be used to differentiate these two species. [source] Continuous extrusion of microcellular polycarbonate,POLYMER ENGINEERING & SCIENCE, Issue 7 2003Richard Gendron Extruded microcellular foams have been obtained from mixtures of polycarbonate (PC) and n-pentane. Cell diameters were in the range of 2 to 5 ,m and the foam densities varied between 400 and 700 kg/m3. Although two types of PC have been investigated, one linear and one branched, the presence of side branchings did not modify the extruded foam characteristics. Use of carbon dioxide as the blowing agent was also attempted, and cell sizes below 10 ,m have been successfully obtained. One prerequisite for microcellular foaming was believed to consist in a concentration of the blowing agent close to its limit of solubility as that defined under the actual processing conditions of pressure and temperature. This hypothesis was validated from the observation of extrusion of regular PC foams (intermediate to low densities and cell sizes ranging between 100 ,m and 1 mm) using moderate concentrations of blowing agents, and from solubility and viscosity measurements on similar polymer/blowing agent systems. [source] Quantitation of cytological parameters of malignant lymphocytes using computerized image analysisINTERNATIONAL JOURNAL OF LABORATORY HEMATOLOGY, Issue 4 2008S. A. HAMID JAHANMEHR Summary Computerized image analysis may add to morphological evaluation by turning qualitative data into quantitative values. In this study, image analysis program was used to quantitate cytological parameters of lymphocytes in B-cell lymphoproliferative disorders. Chronic lymphocytic leukemia (CLL), mantle cell lymphoma (MCL) and B-cell prolymphocytic leukemia (B-PLL) were selected to represent typically small, medium, and large-sized lymphocytes, respectively. Image analysis was performed to determine the morphological parameters. A set of measurements was generated for quantitation of total cell area, cell diameter, cytoplasm area, nuclear area, nuclear/cell ratio, and nuclear density. The quantitated parameters substantiated morphological characteristics of the tumor cells. Comparative assessments demonstrated that CLL, MCL, and PLL can be differentiated by the quantitative descriptors. The results from image analysis may assist in defining morphological criteria and in developing quantitative cell morphology. [source] A stationary-wave model of enzyme catalysisJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 2 2010Carlo Canepa Abstract An expression for the external force driving a system of two coupled oscillators in the condensed phase was derived in the frame of the Debye theory of solids. The time dependence and amplitude of the force is determined by the size of the cell embedding the coupled oscillators and its Debye temperature (,D). The dynamics of the driven system of oscillators were followed in the two regimes of (a) low ,D and cell diameter, as a model of liquid water, and (b) large ,D and cell diameter, as a model of the core of a protein. The response in potential energy of the reference oscillator was computed for all possible values of the internal parameters of the system under investigation. For protein cores, the region in the parameter space of high maximum potential energy of the reference oscillator is considerably extended with respect to the corresponding simulation for water. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010 [source] Influence of Sulfonation on the Properties of Expanded Extrudates Containing 32% Whey ProteinJOURNAL OF FOOD SCIENCE, Issue 2 2006David P. Taylor ABSTRACT Whey protein concentrate (WPC) was treated with sodium sulfite to achieve 4 levels of disulfide bond sulfonation (0%, 31%, 54%, and 71% mole/mole). The WPCs were blended with cornstarch to a 32% (weigh/weight) protein content and extruded into an expanded product. Extrudates were collected at 160 °C and 170 °C and analyzed for physical (air cell diameter, expansion ratio, breaking strength, and density) and chemical (water adsorption index [WAI], water solubility index, moisture content, soluble protein, and carbohydrates) properties. The control and 54% sulfonated samples had larger expansion ratios and air cell diameters and smaller densities and breaking strengths than the 31% and 71% samples. Expansion increased at 170 °C in the sulfonated samples. The WAI was influenced by both sulfonation and temperature, whereas the other chemical properties (except moisture content) were influenced only by sulfonation level. Soluble protein and carbohydrate were highest in the control and 54% samples. The anomalous behavior of the 54% sample may have been the result of significant structural and functional changes of ,-lactalbumin that are predicted to occur at approximately 50% sulfonation. Many functional properties of the WPCs were measured and were significantly correlated to the extrudate properties, particularly those related to protein unfolding and flexibility The increased ability for the proteins to become unfolded during extrusion may have promoted protein-starch interactions, which led to decreases in expansion and overall quality Disulfide bond content did influence the chemical and physical properties of an extruded-expanded whey protein products. [source] MECHANICAL,ACOUSTIC AND SENSORY EVALUATIONS OF CORNSTARCH,WHEY PROTEIN ISOLATE EXTRUDATESJOURNAL OF TEXTURE STUDIES, Issue 4 2007E.M. CHENG ABSTRACT The mechanism relating sensory perception of brittle food foams to their mechanical and acoustic properties during crushing was investigated. Cornstarch was extruded with four levels of whey protein isolate (0, 6, 12 and 18%) and two levels of in-barrel moisture (23 and 27%). Hardness, fracturability and roughness of mass were three main sensory attributes that varied substantially between products. High correlations (r = 0.841,0.998) were observed between sensory attributes and instrumentally determined mechanical properties, including crushing force (11.2,57.9 N) and crispness work (4.6,75.8 N·mm). Based on acoustic data obtained during instrumental crushing, time-domain signal processing and a novel voice recognition technique utilizing frequency spectrograms were successfully employed for understanding the differences in the sensory properties of various products. Microstructure features, including average cell diameter (1.00,2.94 mm), average wall thickness (0.04,0.27 mm) and cell number density (7,193 cell/cm3), were characterized noninvasively using X-ray microtomography, and proved to be critical in relating sensory perception of the cellular extrudates to their mechanical,acoustic signatures. PRACTICAL APPLICATIONS The sensory perception of crispy and crunchy food products is primarily a function of their mechanical response and emission of sounds during fracture. The current study was focused on understanding these relationships in the context of brittle extruded foods. The mechanical,acoustic techniques outlined in this study have the potential of reducing the time, costs and subjectivity involved in evaluation of new foods by human panels, and can be a useful tool in the overall product development cycle. These techniques need not be limited only to food systems, as properties of any rigid, fracturable material can be characterized based on its mechanical,acoustic signature. [source] In vivo corneal confocal microscopy in keratoconusOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 3 2005Joanna G. Hollingsworth Abstract Purpose:, To evaluate the corneas of keratoconic subjects using in vivo confocal microscopy. Methods:, Slit scanning confocal microscopy was used to evaluate the central cornea of one eye of each of 29 keratoconic subjects (mean age 31 ± 10 years; range 16,49 years). Quantitative aspects of corneal morphology were compared against data from control subjects. Results:, Compared with normal control corneas, epithelial wing cell nuclei were larger (p < 0.0001) and epithelial basal cell diameter was larger (p < 0.05) in the keratoconic cornea. Many of the keratoconic corneas investigated showed increased levels of stromal haze and reflectivity, which appeared to be related to the presence of apical scarring on slit lamp examination. A grading scale was devised to quantify the levels of haze. This scale was shown to provide a measure of the level of scarring present. The anterior keratocyte density (AKD) and posterior keratocyte density were 19% lower (p < 0.0001) and 10% lower (p = 0.004) than in controls, respectively. The reduction in AKD was significantly associated with three factors: a history of atopy, eye rubbing and the presence of corneal staining. The mean endothelial cell density in keratoconus was 6% greater than that of normal controls (p = 0.05). The level of endothelial polymegethism was shown not to be different between keratoconic subjects and matched controls (paired t -test: t = 1.82, p = 0.08). Conclusions:, Confocal microscopy demonstrates significant quantitative alterations of corneal morphology in keratoconus. [source] Polystyrene microcellular plastic generation by quick-heating process at high temperaturePOLYMER ENGINEERING & SCIENCE, Issue 7 2000Sumarno Generation of microcellular plastic in the polystyrene-nitrogen system was studied in a batch process. In this study, a quick-heating method was applied to study the effects of saturation temperature, decompression rate and heating time on the microcellular structure for sheet samples with a thickness of 1.3 mm. The saturation pressure in each process was kept constant at 25 MPa. At saturation temperatures above 393 K, we found that, although the solubility of nitrogen increased with increasing saturation temperature, cell density decreased, and the average cell diameter and volume expansion ratio increased. The samples that were saturated at 433 K shattered after microcellular processing. The change in decompression rate affected the supersaturation degree of the dissolved gas in the polymer, and affected the cell structure. Variation of heating time for difference saturation/heating temperature could be used to obtain the optimum relation between cell density, average cell diameter, and volume expansion ratio. [source] Vesicle traffic through intercellular bridges in DU 145 human prostate cancer cellsJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 3 2004Cristina Vidulescu Abstract We detected cell-to-cell communication via intercellular bridges in DU 145 human prostate cancer cells by fluorescence microscopy. Since DU 145 cells have deficient gap junctions, intercellular bridges may have a prominent role in the transfer of chemical signals between these cells. In culture, DU 145 cells are contiguous over several cell diameters through filopodial extensions, and directly communicate with adjacent cells across intercellular bridges. These structures range from 100 nm to 5 ,m in diameter, and from a few microns to at least 50,100 ,m in length. Time-lapse imagery revealed that (1) filopodia rapidly move at a rate of microns per minute to contact neighboring cells and (2) intercellular bridges are conduits for transport of membrane vesicles (1,3 ,m in diameter) between adjacent cells. Immunofluorescence detected alpha-tubulin in intercellular bridges and filopodia, indicative of microtubule bundles, greater than a micron in diameter. The functional meaning, interrelationship of these membrane extensions are discussed, along with the significance of these findings for other culture systems such as stem cells. Potential applications of this work include the development of anticancer therapies that target intercellular communication and controlling formation of cancer spheroids for drug testing. [source] Influence of Sulfonation on the Properties of Expanded Extrudates Containing 32% Whey ProteinJOURNAL OF FOOD SCIENCE, Issue 2 2006David P. Taylor ABSTRACT Whey protein concentrate (WPC) was treated with sodium sulfite to achieve 4 levels of disulfide bond sulfonation (0%, 31%, 54%, and 71% mole/mole). The WPCs were blended with cornstarch to a 32% (weigh/weight) protein content and extruded into an expanded product. Extrudates were collected at 160 °C and 170 °C and analyzed for physical (air cell diameter, expansion ratio, breaking strength, and density) and chemical (water adsorption index [WAI], water solubility index, moisture content, soluble protein, and carbohydrates) properties. The control and 54% sulfonated samples had larger expansion ratios and air cell diameters and smaller densities and breaking strengths than the 31% and 71% samples. Expansion increased at 170 °C in the sulfonated samples. The WAI was influenced by both sulfonation and temperature, whereas the other chemical properties (except moisture content) were influenced only by sulfonation level. Soluble protein and carbohydrate were highest in the control and 54% samples. The anomalous behavior of the 54% sample may have been the result of significant structural and functional changes of ,-lactalbumin that are predicted to occur at approximately 50% sulfonation. Many functional properties of the WPCs were measured and were significantly correlated to the extrudate properties, particularly those related to protein unfolding and flexibility The increased ability for the proteins to become unfolded during extrusion may have promoted protein-starch interactions, which led to decreases in expansion and overall quality Disulfide bond content did influence the chemical and physical properties of an extruded-expanded whey protein products. [source] Size Distribution of Dispersed Luteal Cells During Oestrous Cycle in Angora GoatsREPRODUCTION IN DOMESTIC ANIMALS, Issue 5 2007H Kalender Contents The present study examines the size distribution of the goat steroidogenic luteal cells throughout the oestrous cycle. Corpora lutea (CL) were collected after laparatomy on days 5, 10 and 16 of the oestrous cycle. Luteal cells were isolated from CL by collagenase digestion. Steriodogenic luteal cells were identified by staining of the cells for 3, -hydroxysteroid dehydrogenase activity, a marker for steroidogenic cells. Luteal cells having steroidogenic capacity covered a wide spectrum of sizes, ranging from 5 to 37.5 ,m in diameter. There was a significant increase in mean cell diameters (p < 0.01) as CL aged. The mean cell diameter on day 5 was 11.55 ± 0.12 ,m, which was significantly increased and reached up to 19.18 ± 0.24 ,m by day 16 of the oestrous cycle. The ratio of large to small luteal cells was 0.06:1.0 on day 5 of the oestrous cycle. This ratio increased to 0.78:1.0 by day 16 of the oestrous cycle. Luteal cell size on days 5, 10 and 16 of the oestrous cycle reached its maximum at 7.5, 10 and 35 ,m in diameter, respectively. Development of CL is associated with an increase in luteal cell size in goats. It is likely that small luteal cells could develop into large luteal cells as CL becomes older during oestrous cycle in goats. [source] | |||||||||||||