Cell Volume

We report the structural and magnetic properties of the La1−xTbxMn1/2Sc1/2O3 series. LaMn1/2Sc1/2O3 shows a long range ferromagnetic ordering in agreement with a fully polarized Mn-sublattice. The substitution of La with Tb produces structural changes which affect the magnetic properties. This substitution leads to a contraction in the unit cell volume that mainly reduces the M–O–M bond angle (M = Mn,

In the southern spring–summer season of 2001–2002 six cultivars (Orfeo, Arroz Tuscola, Barbucho, Coscorrón, Pinto and Tórtola) of common beans (Phaseolus vulgaris L.) were grown under two frequencies of irrigation in the central zone of Chile. Control plants were irrigated every 7 days and water stress plants were irrigated every 21 days. Leaf water potential (ΨW), leaf relative water content (RWC), turgid weight to dry weight ratio (TW/DW), osmotic potential at full turgor (ψS100), osmotic adjustment (OA), elasticity module of the cell wall (ɛ) and cell size of the palisade and spongy tissue were evaluated at 74–76 days after sowing (DAS) in completely developed leaves. Water stressed plants showed lower ΨW than in control plants in all the varieties with values that averaged −1.4 and −0.9 MPa, respectively. According to the Drought Resistance Index (DRI) calculated from field measurements, among the cultivars studied, Orfeo was the most resistant to water stress and Arroz Tuscola, the most susceptible. A close negative relationship between leaf TW/DW and DRI under water stress conditions was observed (r2 = 0.63). Leaf TW/DW decreased considerably with water stress in cultivar Orfeo (15%) but the decrease was higher in Tórtola (22%), and there was also a decrease (although smaller) in Pinto (11%). Arroz Tuscola under stress did not present an important change in TW/DW, but presented one of the highest values of TW/DW. There was a strong negative correlation between DRI and palisade cell size under water stress conditions (r2 = 0.85) and a strong positive one between palisade cell size and TW/DW (r2 = 0.86) thus higher DRI was associated with small palisade cell size and small TW/DW. The most resistant cultivar Orfeo did not show a decrease in ψS100 calculated from the pressure–RWC relationships and its resistance was not associated with maintenance of leaf TW/DW under water stress. ψS100 calculated from the pressure–RWC relationships decreased only in the cultivar Coscorrón. Cultivar Orfeo showed a strong decrease (35%) of ɛ, in association to a higher cell wall elasticity (CWE) and as consequence maintained better its cell turgescence but this was also the case of Tórtola (56%) and Pinto (34%) and to a lesser extent of Barbucho (18%). This was not the case for Arroz Tuscola where ɛ and CWE were not changed. These results suggest that CWE and to a lesser extent leaf TW/DW can be important components of the water stress adaptation mechanism in this specie that could contribute to the higher resistance to water stress of Orfeo compared to Arroz Tuscola.

The high-temperature cell parameters of lime (CaO), periclase (MgO), corundum (Al2O3), and spinel (MgAl2O4) have been determined from 300 up to 3000 K through X-ray diffraction experiments with synchrotron radiation. The good agreement found with dilatometric results suggests that vacancy-type defects do not make a large contribution to thermal expansion for these oxides, even near the melting point, justifying the use of X-ray diffraction for determining volume properties up to very high temperatures. Thermal expansion coefficients were determined from the measured cell volumes with equations of the form α=α0 + α1T + α2/T 2. Along with available isobaric heat capacity and compressibility data, these derived coefficients clearly show that anharmonic effects contribute little to the isochoric heat capacities (C v ) of CaO, MgO, and Al2O3, which do not depart appreciably from the 3nR Dulong and Petit limit.

Double perovskite structure with composition of Sr2Mg1-xMnxMoO6 (SMMMO) and Sr2Mg1-xFexMoO6 (SMFMO) for anode materials in solid oxide fuel cell have been synthesized by means of solid state reaction and sol gel method, respectively. Crystal structure of those materials were characterized by X-ray diffraction technique and refined using Rietveld method implemented in the Rietica program and their conductivity were determined by DC conductivity measurement technique. The higher Mn concentration the lower the cell volume of SMMO, whilst for SMFO the higher Fe content the larger the cell. For SMMO the ionic conductivity tends to increase with increased Mn, whilst for SMFMO conductivity decreases as Fe concentration increases.

The dielectric properties of human erythrocytes (red blood cells) suspended in whole blood and in isotonic media at various volume fractions (haematocrits) have been studied in the frequency range 0.2–10 MHz, in which the so-calledβ-dispersion due to the Maxwell-Wagner effect is known to occur. The capacitance and conductance at 25 °C were measured by an instrument interfaced to a computer. The rectangular sample cavity (1 ml volume) contained four pure gold electrode pins, and the sample could be circulated by a roller pump. The frequency-dependence of the permittivity and conductivity were fitted by non-linear least squares regression. Corrections were applied for non-linearity in the dielectric increment at high haematocrit, and for electrode polarisation when diluting the blood in saline. Data were interpreted in terms of a simple equivalent resistor-capacitor circuit. From the measured haematological values the specific membrane capacitance (Cm) and the conductivities internal and external to the cells (σ′i and σ′o respectively) were estimated. The conductivities behaved in a predictable manner with a mean of 0.458 S · m−1 (s.d. ± 0.044) for σ′i, whereas the value of Cm (and indeed the actual capacitance of the suspension) was dependent on the amount of plasma present. Hence, in stationary normal (anticoagulated) whole blood samples, Cm was as high as 2.98 μF · cm−2 (s.d. ± 0.40), in contrast to about 0.9 μF · cm−2 in blood diluted more than two-fold (to less than 20% hct) in isotonic media. The high value remained when the diluent was plasma. The Cm value returned to a high value when washed erythrocytes were reconstituted with plasma, provided that this was present at above a critical or threshold concentration of about 30 vol % in the medium, irrespective of the haematocrit in the range studied (15–44%). The Cm remained low in serum. When added to washed cells in saline, purified fibrinogen had no effect. However, high Cm values were obtained by fibrinogen supplementation to serum and diluted plasma. Applying moderate flow to whole blood approximately halved its high Cm value in an exponential manner with flow rate, whilst the Cm of washed cells (31–67% hct) slightly increased, and converged to the value for whole blood under flow. We interpret the highapparent Cm value in stationary samples to be a result of rapid cell aggregation in the presence of plasma, where rouleaux formation takes place before visible sedimentation sets in.

An in-depth understanding of the mechanisms underlying regulatory volume behavior in corneal epithelial cells has been in part hampered by the lack of adequate methodology for characterizing this phenomenon. Accordingly, we developed a novel approach to characterize time-dependent changes in relative cell volume induced by anisosmotic challenges in calcein-loaded SV40-immortalized human corneal epithelial (HCE) cells with a fluorescence microplate analyzer. During a hypertonic challenge, cells shrank rapidly, followed by a temperature-dependent regulatory volume increase (RVI), τc = 19 min. In contrast, a hypotonic challenge induced a rapid (τc = 2.5 min) regulatory volume decrease (RVD). Temperature decline from 37 to 24°C reduced RVI by 59%, but did not affect RVD. Bumetanide (50 μM), ouabain (1 mM), DIDS (1 mM), EIPA (100 μM), or Na+-free solution reduced the RVI by 60, 61, 39, 32, and 69%, respectively. K+, Cl− channel and K+-Cl− cotransporter (KCC) inhibition obtained with either 4-AP (1 mM), DIDS (1 mM), DIOA (100 μM), high K+ (20 mM) or Cl−-free solution, suppressed RVD by 42, 47, 34, 52 and 58%, respectively. KCC activity also affects steady-state cell volume, since its inhibition or stimulation induced relative volume alterations under isotonic conditions. Taken together, K+ and Cl− channels in parallel with KCC activity are important mediators of RVD, whereas RVI is temperature-dependent and is essentially mediated by the Na+-K+-2Cl− cotransporter (Na+-K+-2Cl−) and the Na+-K+ pump. Inhibition of K+ and Cl− channels and KCC but not Na+-K+-2Cl− affect steady-state cell volume under isotonic conditions. This is the first report that KCC activity is required for HCE cell volume regulation and maintenance of steady-state cell volume.

Iron is essential for phytoplankton growth, as it is in- volved in many metabolic processes. It controls photosyn- thesis as well as many enzymatic processes. As such, iron affects the cell's energy supply and contributes to the assim- ilation of carbon and nitrogen. To determine whether iron limitation would result in energy stress or induced nitrogen deficiency, an Antarctic Phaeocystis

A new structure for ceramic pigments was synthesized by a conventional solid state reaction process. It is based on Ni-doped hibonite, CaAl12O19, which assumes a turquoise-like blue colour similar to that of V-doped zircon. Hibonite is associated with anorthite, CaAl2Si2O8, acting like a fluxing agent in order to lower the synthesis temperature, and with cassiterite, SnO2, acting as a tin buffer to promote coupled Ni2++Sn4+→Al3++Al3+ substitutions, in order to ensure the electric neutrality of the hibonite lattice. Since relatively low chromophore contents are required, this new system constitutes an interesting alternative to the common blue ceramic pigments based on cobalt aluminate spinel or vanadium-doped zircon, implying lower cost and environmental advantages. The pigments characterization was performed by X-ray powder diffraction, diffuse reflectance spectroscopy, CIELAB colorimetric analysis, and testing in ceramic glazes and bodies. The substitution of Al3+ by bigger ions, like Ni2+ and Sn4+, increases the cell volume compared to undoped hibonite and is responsible for the turquoise blue colour, as verified by UV–vis analysis. The chromatic mechanism is due to incorporation of Ni2+ in tetrahedral coordination, likely occurring at the site M3 of the hibonite lattice, where it partially substitutes the Al3+ ion. While this product shows a strong hue as a pigment, it is not stable after severe testing in glazes and attempts to improve its colouring performance are now under development.

Three novel orange, ultramicrobacterial isolates, UMB10, UMB14, and UMB34T were isolated from enrichment cultures inoculated with a melted 3,043 m deep Greenland ice core sample. Phylogenetic analysis of the 16S rRNA gene sequences indicated that the isolates belonged to a single species within the genus Chryseobacterium. They were most closely related to Chryseobacterium aquaticum (99.3%), Chryseobacterium soli (97.1%), and Chryseobacterium soldanellicola (96.9%). Genomic hybridization showed low levels of relatedness between UMB34T and C. aquaticum and C. soldanellicola (19–30%) and C. soli and Chryseobacterium jejuense (45–56%). Comparative genomic fingerprinting analysis using the enterobacterial repetitive intergenic consensus (ERIC) sequence showed nearly identical banding patterns for the three isolates and these patterns were distinct from those of C. aquaticum, C. soldanellicola, C. soli, and C. jejuense. The cells were short rods, lacked flagella, had cell volumes of 3, formed buds and smaller protrusions (blebs), produced copious extracellular material and a flexirubin type pigment. UMB34T produced acids from carbohydrates and utilized glucose and maltose although it did not assimilate mannose. The DNA G + C was 39.6–41.6 mol%. Based on the differences from validly named Chryseobacterium species, it was concluded that these isolates represent a new species for which the name, Chryseobacterium greenlandense is proposed. The type strain is UMB34T (=CIP 110007T = NRRL B-59357).

The ability of neutrophils to sense and move to sites of infection is essential for our defense against pathogens. For motility, lamellipodium extension and stabilization are prerequisites, but how cells form such membrane protrusions is still obscure. Using contrast-enhanced video microscopy and Transwell assays, we show that water-selective aquaporin channels regulate lamellipodium formation and neutrophil motility. Addition of anti-aquaporin-9 antibodies, HgCl(2), or tetraethyl ammonium inhibited the function(s) of the channels and blocked motility-related shape changes. On human neutrophils, aquaporin-9 preferentially localized to the cell edges, where N-formyl peptide receptors also accumulated, as assessed with fluorescence microscopy. To directly visualize water fluxes at cell edges, cells were loaded with high dilution-sensitive, self-quenching concentrations of fluorophore. In these cells, motile regions always displayed increased fluorescence compared with perinuclear regi...

Strontium hexaferrite nanoparticles with nominal composition SrZrxCdxFe12−2xO19 (for x=0.0–0.6) with step increment of 0.2 have been synthesized by the chemical co-precipitation technique. XRD, hysteresis loops measurements and LCR meter were employed to evaluate the structure, magnetic and dielectric properties of SrZrxCdxFe12−2xO19 nanomaterials. The XRD analysis confirms the single phase and various parameters such as lattice constants (a and c), cell