Unit Volume Of Cells Research Articles

Room temperature properties of microstructure and resistivity of alkaline earth – doped on lanthanide manganite

Microstructure of material has a strong relation with resistivity property. Here we report our interesting sample of La0.7(Sr1-xBax)0.3MnO3 (x = 0, 0.3, 0.6, and 0.9) material that has been synthesized by using sol-gel method successfully. All pattern of X-ray diffractometer (XRD) on the successful samples show that all samples are single phase confirmed without significant crystal disorder. The XRD pattern refinement yield that all samples formed R-3c space group with a rhombohedral structure. Although the substitution of Ba2+ to Sr2+ ions have significant difference in atomic radius; it does not change the crystal structure. However, the alkaline earth – doped on lanthanide manganite causes a change in lattice parameters which is followed by shifted of average crystal size, bond length, cell unit volume and bond angle at Mn-O-Mn. The microstructure results by means of scanning electron microscope (SEM) characterization shows that substitution of Ba2+ ions decrease the grain size and yield agglomeration. The relation on the microscopic result resistively confirmed by cryogenic magnetometer characterization in the concentration x = 0 has minimum resistivity of 1.28.10-3 Ωm and the maximum resistivity in the concentration x = 0.9 is 1.85.10-1 Ωm. The Ba2+ doped into Sr2+ in lanthanum manganite may cause a wider resistivity range.

BMAL1 and CLOCK control polarization and lumen formation during mammary alveologenesis in 3D culture

Circadian clock disruption decreased mammary development and impaired lactation in late gestation cows and mice. Transcriptional targets of the circadian clock genes BMAL1 and CLOCK include the cell-cell and cell-ECM proteins e-cadherin (CDH1) and zonula occludens-1 (ZO-1). The polarization and lumen formation of milk-producing acini is dependent on these junctional proteins. We hypothesized that if BMAL1 and CLOCK were disrupted, mammary epithelial cells (HC11) will have a reduced ability to form acini. Our objective was to measure the effect of BMAL1 gene deletion (BMAL1-KO) and CLOCK protein reduction (shCLOCK) in HC11 cells on the formation of acini and expression of CDH1 and ZO-1 in three-dimensional (3D) cultures. Cells were plated on Matrigel, embedded, and cultured to create 3D structures. ImageJ software was used to quantify the acini and found that the BMAL1-KO and shCLOCK lines formed fewer and smaller acini (p < 0.05). Confocal microscopy revealed that CDH1 was located along lateral membranes and ZO-1 was apically located in all three lines. Levels of CDH1 and ZO-1 were greater (p < 0.05) per unit volume of cell in the shCLOCK cell line. Live/dead staining of cells found little to no cell death across three lines. Transmission electron microscopy (TEM) of acini indicated less polarization of cells within BMAL1-KO and shCLOCK acini. Polarization of cells is required for formation of 3D structures and requires coordination of temporal-spatial cues. Disruption of circadian clocks results disturbs temporal organization of cellular processes and causes a reduced ability of cells to polarize and form acini.

Structural and thermal properties of InSb:Mn with MnSb clusters

III-V family compounds doped with transition metals are promising materials for spintronic applications. Synthesis of an In0.9Mn0.1Sb ingot was thus carried out by direct fusion of the stoichiometric mixture of the constituent elements, followed by controlled cooling. The ingot obtained showed p-type conductivity. Scanning Electron Microscopy (SEM) images show MnSb clusters in an InSb matrix doped with Mn, a result like that found when the compound is obtained using other techniques. Energy-dispersive X-ray spectroscopy (EDS) shows that the atomic ratio of the clusters is Mn/Sb = 0.896 ± 0.025, while the atomic ratio of the matrix is In/Sb = 1.013 ± 0.005. The indexation of the powder X-ray diffraction pattern at room temperature yielded a majority cubic phase of InSb doped with Mn, with a lattice parameter a = 6.474173 Å and cell unit volume V = 271.36Å3 , while non-indexed reflections are associated with the presence of MnSb rich in Sb. The phase transition temperatures were obtained from differential thermal analysis (DTA) measurements on powder samples in evacuated quartz capsules. It can be observed that fusion of the InSb matrix doped with Mn occurs between 485 °C and 528 °C, unlike the congruent fusion of the InSb at 527.7 °C; while the fusion of the Sb-rich MnSb clusters occurs between 494 °C and 509 °C. These temperatures are lower than those reported for the Sb-rich side of the phase diagram of the Mn-Sb binary system, which shows a decrease in the thermal stability of the compounds. The estimated fusion enthalpies for InSb:Mn and antimony-rich MnSb are, respectively, 4.8 Kcal/mol and 117.4 Kcal/mol.

Radiation shielding properties of bi-ferroic ceramics added with CNTs

This study reports the structural and radiation shielding properties of bi-ferroic ceramics added with carbon nanotubes (CNTs). Three samples labeled C1, C2, and C3 were synthesized by the sol-gel process followed by the sintering step at high temperatures. The structural analysis showed a tetragonal structure for C1 ceramic sample and a cubic structure for C2, and C3 samples. The inclusion of the CNTs phase into the bi-ferroic ceramic phases induces a variation in the lattice constant and causes a shrinkage in the cell unit volume V. For the C1, C2, and C3 ceramics, the linear attenuation coefficient (LAC) was experimentally measured at nine energies in the range of 8.1 × 10−2 - 1.41 MeV. At 8.1 × 10−2 MeV, the LAC is 14.244, 15.763 and 16.837 cm−1 for C1–C3 ceramics. The LAC results demonstrated the importance of utilizing these ceramics for low-energy radiation shielding applications. From the half-value layer (HVL) results, we found that a layer with a small thickness can be used to reduce the intensity of the low-energy photons. At higher energy, a thicker layer is needed to reduce the number of photons that can penetrate the ceramics.

Analysis Microstructure of La<sub>0.7</sub>(Sr<sub>1-x</sub>Ca<sub>x</sub>)<sub>0.3</sub>MnO<sub>3</sub> Prepared by Sol-Gel Method

Perovskite-based on manganite La0.7(Sr1-xCax)0.3MnO3 (x = 0, 0.3, 0.5, 0.7) has been successfully synthesized using by sol-gel method. All sample was characterized by using XRD (X-Ray Diffraction) obtain a single phase without impurities peak. The transition of crystal structure transition, lattice parameters, cell unit volume, crystal size, bond length (Mn-O), and <Mn-O-Mn> bond angles caused by Ca2+ ion substitution. Dopant concentration x = 0 - 0.5 shows that the sample has a rhombohedral crystal structure with space group R-3c and orthorhombic crystal structure with space group P n m a at dopant concentration x = 0.7. The results of SEM (Scanning Electron Microscope) characterization show a difference in grain size with the addition of Ca2+ ion substitution.

Analysis crystal structure of magnetic materials Co1-xZnxFe2O4

Modification of zinc substitution cobalt ferrite material is expected to be one of the microwave absorbing material candidates because it has single phase permittivity and permeability. Permitivity and permeability are engineered from the inter-substitution of atoms in the crystal lattice as a function of composition. Substitution of zinc into cobalt ferrite (Co1- xZnxFe2O4) for Zn2+ (x = 0 – 1) has been synthesized using the solid reaction method through mechanical deformation techniques. The results of refinement of X-ray diffraction patterns indicates that a single phase is obtained for all x compositions. Cubic structure formation with Fd3m space group, where the lattice parameter, lattice strain, cell unit volume, and atomic density change as a composition function. Morphological observations of particles using a scanning electron microscope showed that the particle size distribution was evenly distributed for all compositions with particle sizes ranging from 100-500 nm, whereas in each particle the average size of crystallite also changed as a function of composition. It was concluded that the effect of Zn substitution on Co1-xZnxFe2O4 resulted in changes in the crystal structure parameters as a function of composition with a uniform particle size distribution in all compositions.

A NOVEL CELL Design of Alkaline-Based ZINC -Iodide FLOW Battery for Enhancing Energy and POWER Performance

An alkaline-based Zinc-Iodide Flow Battery (ZIFB) is considered one of the promising electrochemical energy storage devices with a prospective application in the transport systems due to their high specific energy. To improve the battery performances of this zinc-iodide system, numerous researches have been conducted by considering new materials, electrode structures, various system design and operating conditions. However, there is a very useful prospect to adopt alternative cell geometries that can produce higher power per cell unit volume and/or reduce the overall system cost to commercialize the product. In this work, a novel cell structure is designed for ZIFB, which includes embedded serpentine flow channels in a non-porous and non-brittle case. This new design eliminates end plates and gaskets to improve safety, extend life, and promote ease of assembly with fewer components than traditional ZIFB cells. In particular, a key challenge of conventional graphite flow field plates in which solution penetration can occur due to an easily broken and porous structure is solved by using rigid impermeable polyvinyl chloride (PVC) sheets with flow channels embedded in the sheets. Various tests, such as cycling and polarization measurements of a wide range of current and flow rates, and Electrochemical Impedance Spectroscopy (EIS) for internal resistance analysis, are performed to compare new and traditional designs. The results show that the new design keeps cycling performance stable, with better stability and energy efficiency, than conventional ZIFB cells do. High power performance is also observed for the same external cell size. In addition, an abrupt potential drop caused by high contact resistance between the current collector and a porous electrode is solved by introducing a layer of the patterned graphite sheet to improve contact and electronic conductivity and, also, to function as a flow channel.

Unveiling the Synergic Roles of Mg/Zr Co-Doping on Rate Capability and Cycling Stability of Li4Ti5O12

Li4Ti5O12 (LTO) has attracted great interest as an anode material due to the “zero strain” during Li+ insertion and extraction. But the intrinsic ionic diffusion coefficient and electronic conductivity are very poor. Herein, a strategy of Mg2+ and Zr4+ co-doping has been proposed to modulate the crystal structure and improve the electrochemical performances. More importantly, the synergic roles of Mg/Zr co-doping has been unveiled based on the analysis of X-ray diffraction, Neutron powder diffraction, X-ray photoelectron spectroscopy, and electrochemical measurements. Firstly, Mg-Zr co-doping expands the lattice parameter, cell unit volume and even Li-O bond length, which reduces Li+ migration barrier and benefits to Li+ insertion/extraction. Secondly, Ti-O shrinkage induced by Mg-Zr co-doping enhances the structure stability and subsequently the cycle performance. Thirdly, Mg-Zr co-doping promotes more Ti4+/Ti3+ which facilitates electron conductivity. Moreover, Mg-Zr co-doping also decreases the polarization and charge transfer impedance. Li3.8Mg0.2Ti4.9Zr0.1O12 delivers a discharge capacity of 180.5, 150.7, 110.4 and 78.9 mAh/g at 0.2C, 1C, 5C and 10C, respectively. Moreover, the capacity retention is greatly increased from 57.9% of LTO to 98.59% at 10C after 500 cycles.

Efficacious realization of Ba0.5Sr0.5TixM1−xO3 (M = Mn2+, Co2+) perovskite nanostructures through oxalate precursor strategy

Nowadays, barium strontium titanate (BST; Ba0.5Sr0.5TiO3) as a versatile material is a prospect candidate in different electronic and magnetic applications. In this study, cubic BST nanoparticles have been prosperity fabricated based on the oxalate precursor method. Afterwards, the formed precursor powders are further annealed at temperature 1000 °C for time 2 h. Meanwhile, the insertion of Mn2+ or Co2+ ions as an acceptor substitution to BST crystal was described at different concentrations from 0.1 to 0.3 molar ratios. Accordingly, the crystallite size and cell unit volume were found to enhance due to the introduction of acceptor ions. The Mn2+ or Co2+ ions replacements have the magnificent impact on the morphology, optical as well as dielectric and magnetic properties compared to the pure one. For instance, the optical transparency of BST material was found to increase with increasing Mn2+ or Co2+ ion content. Typically, the band gap energy and the refractive index were increased with acceptor doped ions. The dielectric performance in terms of different substitutions was decreased with Co2+ ions and increased with Mn2+ ions compared with pure BST sample. Eventually, the magnetic peculiarities were improved by addition of Mn2+ or Co2+ ions at different molar ratios.

Isolated effects of microwave radiation on the solid-liquid interface reactions between hydroxyapatite nanocrystals and silver ions

The main objective of this work was to evaluate the effect of microwave radiation on the surface reactions and doping of as-synthesized hydroxyapatite (HA) nanocrystals with Ag+ ions. Our assays were based on wavelength-dispersive X-ray fluorescence, Rietveld refinement of X-ray diffraction data and Fourier transform infrared spectroscopy. The results demonstrated that the elemental and phase compositions of the as-synthesized HA nanocrystals were not affected by the microwaves. Conversely, the occupation of the PO43- and OH- sites of the HA nanocrystals by HPO42- and CO32- groups was strongly affected by the microwaves, as well as by the insertion of Ag+ ions into the structure. Consequently, the lattice parameters, crystallite size and aspect ratio of the as-synthesized HA nanocrystals were also affected. Furthermore, the microwaves were able to accelerate the reactions between the Ag+ ions and the HA surface as well as the rate of variation in HA cell unit volume. These findings indicate that microwaves are capable of significantly modifying not only the crystallographic features of HA nanocrystals but also the rate of Ag+ doping.

A quantitative ultrastructural study of Chromatium minus in the bacterial layer of Lake Cis� (Spain)

A quantitative ultrastructural study was performed with samples taken throughout a layer of the purple sulfur bacterium Chromatium minus in Lake Ciso (Spain). Ultrathin sections of cells were analyzed by transmission electron microscopy, in order to study the size, number and volume of intracytoplasmic membranes (ICM), sulfur globules and poly-β-hydroxybutyrate (PHB) granules per unit volume of cell. Important differences were seen between cells from the top (receiving 60 μE · m−2 · s−1 at noon) on the one hand, and cells from the peak and bottom parts of the bacterial layer (receiving less than 1 μE · m−2 · s−1) on the other hand. The amount of ICM per cell increased as a function of depth being about three times higher in bottom cells than in top cells. Neither statistically significant differences in cell size, nor in numbers of sulfur globules were found, but the ultrastructure changed with depth. Finally, the most important changes throughout depth were detected in PHB granules. Top cells had 0.5% of their volume occupied by PHB granules, whereas in the bottom cells the corresponding value was 12.2%. These changes were due to the number of PHB granules per unit volume of cell since globule size was constant.

Progesterone production in vitro by small and large ovine luteal cells.

Corpora lutea from cyclic ewes were dissociated by collagenase digestion and trypsin/EGTA treatment. Enriched fractions of endothelial cells, small luteal cells and large luteal cells were prepared on a stepped gradient of Ficoll 400. Progesterone was measured by radioimmunoassay and the results corrected so that progesterone production by each cell type could be determined. Endothelial cells did not produce significant amounts of progesterone, with or without LH stimulation, and endothelial cell contamination of small and large luteal cell fractions did not influence progesterone production by these fractions. Mean +/- s.e.m. basal progesterone production (n = 10) by large luteal cells was greater (P less than 0.001) on a per cell basis than that by small luteal cells (1.16 +/- 0.16 compared with 0.25 +/- 0.06 pg/h/cell). However LH, which stimulated a maximal 3-4-fold increase in progesterone production by small luteal cells (LH ED50 = 0.14 ng/ml), had no significant effect on production by large luteal cells, when contamination by small luteal cells was taken into account. The response of small luteal cells was specific to LH, other hormones having had no significant effect. Basal progesterone production by small luteal cells (0.12 +/- 0.03 fg/h/micron3) calculated per unit volume of cell was not significantly different from that of large luteal cells (0.17 +/- 0.02 fg/h/micron3). After LH stimulation, small luteal cells produced more progesterone than did large luteal cells (0.40 +/- 0.09 compared with 0.18 +/- 0.03 fg/h/micron3) (P less than 0.05). When the amounts of progesterone produced per cell were multiplied by the absolute numbers of large luteal (1 X 10(7] and small luteal (5 X 10(7] cells in the intact corpus luteum, basal progesterone production by large luteal cells (11.6 +/- 1.6 micrograms/h) was similar to that by small luteal cells (12.3 +/- 3.0 micrograms/h). However, under LH stimulation, progesterone production by the small luteal cell type (39.9 +/- 9.5 micrograms/h) was approximately 3 times greater than that by the large luteal cell type (12.3 +/- 1.6 micrograms/h) (P less than 0.05). We therefore conclude that small luteal cells may be the principal source of luteal progesterone production in the sheep.

Potassium fluxes in the rat reticulocyte Ouabain sensitivity and changes during maturation

K + turnover is markedly enhanced in the rat reticulocyte, both influx and efflux rates being increased by factors of approximately 3 over the corresponding rates in adult cells. These accelerated fluxes are observed despite the absence of any appreciable change in intracellular K + concentration during the course of maturation. Qualitative characteristics of the active transport process for K + influx appear to be identical in reticulocytes and mature erythrocytes with regard both to K + sensitivity, and to ouabain sensitivity as a function of external K + concentration. The number of ouabain binding sites per unit volume of cells, however, is increased by a factor of approximately three in the reticulocyte and thus correlates well with the observed degree of enhancement of active K + influx in these cells. Half-maximal rates of ouabain-sensitive K + influx are observed at external K + concentrations well below 1 mM for both reticulocytes and mature erythrocytes. It is concluded that the enhanced rate of K + accumulation in the reticulocyte can be quantitatively attributed to an increased number of pump units which are qualitatively identical to those in the mature cell, and which function at a near-maximal rate at the ambient K + concentration present in normal rat plasma.

Increased erythrocyte cation permeability in thalassemia and conditions of marrow stress.

Calcium and sodium permeability of erythrocytes from patients with untransfused alpha- or beta- thalassemia major has been studied and compared to mature erythrocytes or control cells with comparable reticulocytosis. Isotopic Na(+) influx was increased a mean fourfold greater than normals and threefold greater than reticulocyte rich control. Passive net leak of Na(+) into thalassemic cells incubated with ouabain was also increased corresponding to their greater (22)Na(+) influx. Erythrocyte Na(+) and K(+) concentrations and cell water content per unit volume of cells were normal. Quantitation of active cation pumps in the cell membrane by the technique of [(3)H]ouabain binding showed a 2.6- to 9.9-fold increase above normal. Inward Ca(2+) movement was studied in cells with absent Ca(2+) pumping produced by depletion of either ATP or Mg(2+)-ions. Calcium uptake by ATP depleted thalassemic cells was increased 12-fold above normals and 3.6-fold above reticulocyte-rich controls. The Ca(2+) uptake by Mg(2+)-depleted thalassemic cells was also increased above normal confirming that erythrocyte Ca(2+) permeability is increased in this disease. Osmotic fragility measurements show that the surface area to volume ratio of thalassemic erythrocytes was increased by 15 to 25% above mature erythrocytes. The increased passive cation permeability of thalassemic erythrocytes cannot be explained by either reticulocytosis or an increased surface area to volume ratio of these cells. Moreover, erythrocyte Na(+) and Ca(2+) influxes in congenital dyserythropoietic anemia (CDA type 2) were increased 2- and 14-fold, respectively, above normal. The increased cation fluxes and cation pump numbers in thalassemic and congenital dyserythropoietic anemia erythrocytes are consistent with the hypothesis of membrane immaturity arising from rapid marrow transit times, a concept previously advanced to explain the persistence of i-antigen on these cells.

A biochemical study of erythrocytes in Swedish families with beta-thalassaemia minor.

In three ‘aboriginal’ Swedish families with β‐thalassaemia minor the contents of Ery‐Hb A2 and Ery‐Hb F seem not to vary with time (age). The results were entirely the same in both young and adult β‐thalassaemic individuals. The erythrocyte contents of hexokinase, phosphofructokinase, pyruvate kinase, aldolase, lactate dehydrogenase, glucose‐6‐phosphate dehydrogenase and glutathione reductase expressed per unit volume of cells were increased in accordance with findings in β‐thalassaemia minor from the Mediterranean area.The erythrocyte concentrations of ATP and ADP, also calculated as per cent volume of cells, were decreased, the concentrations of G6P + F6P and DPG increased. These findings are not specific for the disease, as they have also been registered in iron deficiency anaemia. There are indications, however, that the glycolytic system of β‐thalassaemic erythrocytes can increase the oxygen releasing capacity of the haemoglobin mass to the same extent as in other types of anaemia.

ERYTHROCYTE LIPIDS: A COMPARISON OF NORMAL YOUNG AND NORMAL OLD POPULATIONS.

Abstract Lipid fractions of normal young and normal old red cells have been measured and the concentrations related to the individual cell, to surface area of the cell, and to a unit volume of cells. The older cells contain a decreased concentration of total lipid as compared with younger cells, regardless of the mode of expression of results; statistically significant differences occurred in the cholesterol concentrations as referred to the individual cell, to the cell surface area, and in the total phospholipid concentrations as related to the single cell. The results suggest that cellular factors may contribute to the maintenance of erythrocytic cholesterol concentrations and that the evaluation of lipid concentrations in normal and abnormal cells would be most satisfactorily obtained if similarly aged populations of normal and abnormal cells were compared.

Limnology of Canyon Ferry Reservoir

In general, one µg chlorophyll was equivalent to 0.5 mm3 cell volume and 0.12 mg ash‐free dry weight. The average seston content consisted of 34.5% phytoplankton, 9.8% zooplankton, and 55.7% detritus. Optimal photosynthesis per unit chlorophyll and cell volume averaged 0.39 µ mole O2/µg chl/hr and 0.86 µ mole O2/mm3/hr, respectively. The average euphotic zone photosynthetic rate was 52% of the optimal rate. Chlorophyll content per unit volume of cells and photosynthesis per unit chlorophyll or cell volume decreased with increase in population size. Evidence was found of an interacting effect of temperature, light intensity, and phosphates on photosynthesis. An empirical method was described for estimating photosynthesis on the basis of chlorophyll content, optimal ra.te of photosynthesis per unit chlorophyll, extinction coefficient, and the ratio of euphotic zone photosynthesis to optimal photosynthesis. Determinations of phytoplankton respiration were made, and net euphotic zone photosynthesis was computed for various sizes of chlorophyll standing crop. It was concluded that the most frequently occurring values of chlorophyll standing crop were most likely to produce a maximum net production and to be at a steady state level.

RELATION BETWEEN QUANTITY OF CHLOROPHYLL AND CAPACITY FOR PHOTOSYNTHESIS

Seeking evidence as to the number of chlorophyll molecules concerned in the reduction of one molecule of carbon dioxide, Emerson and Arnold (3) measured the maximum amount of carbon dioxide which could be reduced by a measured quantity of cells, under conditions designed to make photosynthesis dependent only on the amount of chlorophyll present, and independent of other factors, both internal and external. The limiting effect of chemical processes in the cell under saturating external conditions was avoided by illuminating with extremely short flashes of light (about 10~5 seconds) and allowing sufficient dark time (about one-tenth of a second) between flashes so that the chemical processes or Blackman reaction could run to completion between light flashes. The intensity of the flashes was so great that higher intensities resulted in no increase in carbon dioxide assimilation. With light flashes as short as 10~5 sec, it was believed impossible for a significant number of individual chlorophyll molecules to act more than once per flash in the reduction of carbon dioxide. Under these conditions it was anticipated that chlorophyll would be the only factor limiting the amount of carbon dioxide reduced per flash. The number of chlorophyll molecules should limit the energy available for carbon dioxide reduction after each flash. The ratio (p) of number of chlorophyll molecules present to number of carbon dioxide molecules reduced per flash was found to remain approximately constant, even when the chlorophyll content per unit volume of cells was varied several fold. Unexpectedly high values were obtained for p, showing that the cells contained two or three thousand times as much chlorophyll as the maximum amount of carbon dioxide which they could reduce per flash of light. Calculations made by Gaffron and Wohl (7) show that essentially the same relationship prevails in continuous light. They compared the maximum rate of carbon dioxide reduction with the chlorophyll content for a variety of material, including leaves as well as suspensions of algal cells. Taking the average time required for the completion of the Blackman reaction in Chlorella from the results of Emerson and Arnold, they found that assimilating cells in general contain over two thousand times as much chlorophyll as seems necessary to account for the highest observed rates of photosynthesis.

The Chlorophyll Factor in Photosynthesis

Photosynthesis is a process taking place in visible light and involving a reaction between two colorless substances, carbon dioxide and water, which gives rise to carbohydrates. The process is made possible in visible light by the presence of chlorophyll, the chief coloring matter of green plants. The function of chlorophyll can be revealed only by a study of the process when different amounts of chlorophyll are present. This condition is made possible by applying appropriate culture methods to the unicellular green alga Chlorella. Chlorella cells may be produced which show all degrees of greenness but which are normal in other respects. A study of their capacity for photosynthesis at different concentrations of chlorophyll per unit volume of cells, using different light intensities and temperatures, indicates that chlorophyll plays the part of a chemical reactant in photosynthesis as well as being the absorber of energy in the form of visible light, which furnishes the driving force for the process.