Reduction In Cell Volume Research Articles

Integration of Cell Growth and Asymmetric Division during Lateral Root Initiation in Arabidopsis thaliana

Lateral root formation determines to a large extent the ability of plants to forage their environment and thus their growth. In Arabidopsis thaliana and other angiosperms, lateral root initiation requires radial cell expansion and several rounds of anticlinal cell divisions that give rise to a central core of small cells, which express different markers than the larger surrounding cells. These small central cells then switch their plane of divisions to periclinal and give rise to seemingly morphologically similar daughter cells that have different identities and establish the different cell types of the new root. Although the execution of these anticlinal and periclinal divisions is tightly regulated and essential for the correct development of the lateral root, we know little about their geometrical features. Here, we generate a four-dimensional reconstruction of the first stages of lateral root formation and analyze the geometric features of the anticlinal and periclinal divisions. We identify that the periclinal divisions of the small central cells are morphologically dissimilar and asymmetric. We show that mother cell volume is different when looking at anticlinal vs. periclinal divisions and the repeated anticlinal divisions do not lead to reduction in cell volume, although cells are shorter. Finally, we show that cells undergoing a periclinal division are characterized by a strong cell expansion. Our results indicate that cells integrate growth and division to precisely partition their volume upon division during the first two stages of lateral root formation.

Endosperm cell size reduction caused by osmotic adjustment during nighttime warming in rice

High night temperature (HNT) often reduces yield in field crops. In rice, HNT during the ripening stage diminishes endosperm cell size, resulting in a considerable reduction in final kernel weight; however, little is known about the underlying mechanisms at cell level. In this study, we performed picolitre pressure-probe-electrospray-ionization mass spectrometry to directly determine metabolites in growing inner endosperm cells of intact seeds produced under HNT conditions, combining with 13C feeding and water status measurements including in situ turgor assay. Microscopic observation in the inner zone suggested that approximately 24.2% of decrease in cell expansion rate occurred under HNT at early ripening stage, leading to a reduction in cell volume. It has been shown that HNT-treated plants were subjected to mild shoot water deficit at night and endosperm cell turgor was sustained by a decline in osmotic potential. Cell metabolomics also suggests that active solute accumulation was caused by a partial inhibition of wall and starch biosynthesis under HNT conditions. Because metabolites were detected in the single cells, it is concluded that a partial arrest of cell expansion observed in the inner endosperms was caused by osmotic adjustment at mild water deficit during HNT conditions.

Antimalarial Activity of Nigella sativa L. Seed Extracts and Selection of Resistance in Plasmodium berghei ANKA in a Mouse Model.

Background Chemotherapy plays a crucial role in malaria control. However, the main obstacle to treatment has been the rise of parasite resistance to most antimalarial drugs. Artemisinin-based combination therapies (ACTs) remain the most effective antimalarial medicines available today. However, malaria parasite tolerance to ACTs is now increasingly prevalent especially in Southeast Asia presenting the danger of the spread of ACTs resistance to other parts of the world. Consequently, this creates the need for alternative effective antimalarials. Therefore, this study sought out to determine antimalarial potential, safety, and resistance development of the extracts in a mouse model. Method Methanolic and ethyl acetate extracts were obtained by solvent extraction. The extracts were assayed for acute toxicity in vivo. Additionally, the two extracts were evaluated for antimalarial activity in vivo against Plasmodium berghei ANKA strain by the 4-day suppressive test at 500, 250, and 125 mg/kg/day. Packed cell volume was evaluated to determine anemia manifestation. Finally, continuous drug pressure experiment at 500 mg/kg and DNA amplification via PCR were conducted. The amplicons underwent through Sanger sequencing. Results There was no toxicity realized in the animals at 2000 mg/kg. Importantly, high parasitemia suppression of 75.52% and 75.30% using a dose of 500 mg/kg of methanolic and ethyl acetate extracts, respectively, was noted. The extracts were able to reverse packed cell volume reduction. Nigella sativa-resistant phenotype was selected as delayed parasite clearance. However, there was no change in the nucleotide sequences of PbMDR1 and PbCRT genes. Conclusion The results provide room for future exploitation of the plant as an antimalarial.

Hydrostatic Pressure Regulates the Volume, Aggregation and Chondrogenic Differentiation of Bone Marrow Derived Stromal Cells.

The limited ability of articular cartilage to self-repair has motivated the development of tissue engineering strategies that aim to harness the regenerative potential of mesenchymal stem/marrow stromal cells (MSCs). Understanding how environmental factors regulate the phenotype of MSCs will be central to unlocking their regenerative potential. The biophysical environment is known to regulate the phenotype of stem cells, with factors such as substrate stiffness and externally applied mechanical loads known to regulate chondrogenesis of MSCs. In particular, hydrostatic pressure (HP) has been shown to play a key role in the development and maintenance of articular cartilage. Using a collagen-alginate interpenetrating network (IPN) hydrogel as a model system to tune matrix stiffness, this study sought to investigate how HP and substrate stiffness interact to regulate chondrogenesis of MSCs. If applied during early chondrogenesis in soft IPN hydrogels, HP was found to downregulate the expression of ACAN, COL2, CDH2 and COLX, but to increase the expression of the osteogenic factors RUNX2 and COL1. This correlated with a reduction in SMAD 2/3, HDAC4 nuclear localization and the expression of NCAD. It was also associated with a reduction in cell volume, an increase in the average distance between MSCs in the hydrogels and a decrease in their tendency to form aggregates. In contrast, the delayed application of HP to MSCs grown in soft hydrogels was associated with increased cellular volume and aggregation and the maintenance of a chondrogenic phenotype. Together these findings demonstrate how tailoring the stiffness and the timing of HP exposure can be leveraged to regulate chondrogenesis of MSCs and opens alternative avenues for developmentally inspired strategies for cartilage tissue regeneration.

Evaluation of Hemato-Biochemical Parameters, Body and Organ Weight and Reproductive Profile Changes in Response to Receiving Different Levels of Indomie Noodles in Albino Rats

The Indomie noodles are an instant noodle sold dried in packets or cups. The noodles are quick and easy to make and can be eaten as a snack or part of the main meal. This study was designed to examine the possible effect of different levels of Indomie noodles on the hematological biochemical profile, organosomatic index and male fertility indices in healthy adult albino rats. In an experimental study, twenty male rats of average weight 115 g (divided into four groups) and twenty female rats of average weight 100 g (divided into four groups). Each group consists of five rats. Group A is the control group and was fed with standard rat feed. In contrast, groups B, C and D were supplied with 25 %, 50 % and 75 % Indomie instant noodles cooked and spiced with the seasoning. The administration was carried out for 8 w. The result showed that the body weight, expressed as growth rate, showed that rats exposed to the 75 % Indomie noodle formulated diets had significantly minimum growth rates than controls and other two different groups. There was a significant increase (p<0.05) in the organosomatic index (kidney, liver, brain and testes) of rats fed on a diet containing 75 % Indomie noodles. There was a significant (p<0.05) increase in lymphocytes percentage, with a decrease in monocytes and granulocyte percentages compared to the control group. Red blood cell indices examination showed a reduction in mean cell volume, mean cell hemoglobin and mean cell hemoglobin concentration value. A diet containing 75 % Indomie noodles appeared to the highest significant decrease in total serum protein and serum uric acid with a significant increase of alkaline phosphatase and blood urea at 25 %, 50 % and 75 % in comparison to the control group. However, aspartate aminotransferase results show a significant difference at 75 % compared to 0 %. On the other, evaluation of various sperm parameters showed there was a significant reduction in sperm concentration, motility and viability between treated groups in comparison to the untreated group in response to an increase in the percent of Indomie noodles in the diet and their plasma testosterone levels of the treated groups decreased insignificantly than those of the control group.

Antimalarial Activity of Seed Extracts of Schinus molle Against Plasmodium berghei in Mice.

Background.Malaria is a major public health problem in developing countries. In Ethiopian, the seeds of Schinus molle are used for the management of malaria. Therefore, the current study aimed to evaluate in vivo antimalarial activity of hydro-alcoholic crude extract and solvent fractions of Schinus molle seeds in Plasmodium berghei infected mice.Methods.An 80 percent of methanolic crude extract and solvent fractions of Schinus molle seeds were tested for antimalarial activity at 100, 200 and 400 mg/kg doses. The parasitemia level, packed cell volume, body weight, survival of date and rectal temperature were used to evaluate the anti-malarial activity of the extracts. One-way ANOVA followed by post hoc Tukey’s HSD multiple comparison test was employed and the result was expressed in mean ± SEM (standard error of the mean).Results.The curative activity of the highest dose of crude extract and aqueous fraction of Schinus molle seeds was 69.86% and 73.82% (p < 0.001), respectively. In the prophylactic test, aqueous fraction had 72.39% (p < 0.001) suppression antimalarial activity. Among solvent fractions, only chloroform fraction was significantly attenuated packed cell volume reduction. The mice treated with crude extract and aqueous fraction had longer survival date than vehicle-treated mice (p < 0.001).Conclusion.The experiment finding showed that the crude extract and solvent fractions of Schinus molle seeds had significant curative and prophylaxis anti-plasmodial activity. This result revealed that the Schinus molle seeds extract has promising antimalarial activity against Plasmodium berghei. However, further confirmatory studies, isolation and characterization of the active constituents are recommended.

Metabolic rejuvenation upgrades circulatory functions of red blood cells stored under blood bank conditions.

Red blood cells (RBC) change upon hypothermic conservation, and storage for 6 weeks is associated with the short-term clearance of 15% to 20% of transfused RBCs. Metabolic rejuvenation applied to RBCs before transfusion replenishes energetic sources and reverses most storage-related alterations, but how it impacts RBC circulatory functions has not been fully elucidated. Six RBC units stored under blood bank conditions were analyzed weekly for 6 weeks and rejuvenated on Day 42 with an adenine-inosine-rich solution. Impact of storage and rejuvenation on adenosine triphosphate (ATP) levels, morphology, accumulation of storage-induced microerythrocytes (SMEs), elongation under an osmotic gradient (by LORRCA), hemolysis, and phosphatidylserine (PS) exposure was evaluated. The impact of rejuvenation on filterability and adhesive properties of stored RBCs was also assessed. Rejuvenation of RBCs restored intracellular ATP to almost normal levels and decreased the PS exposure from 2.78% to 0.41%. Upon rejuvenation, the proportion of SME dropped from 28.2% to 9.5%, while the proportion of normal-shaped RBCs (discocytes and echinocytes 1) increased from 47.7% to 67.1%. In LORCCA experiments, rejuvenation did not modify the capacity of RBCs to elongate and induced a reduction in cell volume. In functional tests, rejuvenation increased RBC filterability in a biomimetic splenic filter (+16%) and prevented their adhesion to endothelial cells (-87%). Rejuvenation reduces the proportion of morphologically altered and adhesive RBCs that accumulate during storage. Along with the improvement in their filterability, these data show that rejuvenation improves RBC properties related to their capacity to persist in circulation after transfusion.

A single Na+-Pi cotransporter in Toxoplasma plays key roles in phosphate import and control of parasite osmoregulation.

Inorganic ions such as phosphate, are essential nutrients required for a broad spectrum of cellular functions and regulation. During infection, pathogens must obtain inorganic phosphate (Pi) from the host. Despite the essentiality of phosphate for all forms of life, how the intracellular parasite Toxoplasma gondii acquires Pi from the host cell is still unknown. In this study, we demonstrated that Toxoplasma actively internalizes exogenous Pi by exploiting a gradient of Na+ ions to drive Pi uptake across the plasma membrane. The Na+-dependent phosphate transport mechanism is electrogenic and functionally coupled to a cipargarmin sensitive Na+-H+-ATPase. Toxoplasma expresses one transmembrane Pi transporter harboring PHO4 binding domains that typify the PiT Family. This transporter named TgPiT, localizes to the plasma membrane, the inward buds of the endosomal organelles termed VAC, and many cytoplasmic vesicles. Upon Pi limitation in the medium, TgPiT is more abundant at the plasma membrane. We genetically ablated the PiT gene, and ΔTgPiT parasites are impaired in importing Pi and synthesizing polyphosphates. Interestingly, ΔTgPiT parasites accumulate 4-times more acidocalcisomes, storage organelles for phosphate molecules, as compared to parental parasites. In addition, these mutants have a reduced cell volume, enlarged VAC organelles, defects in calcium storage and a slightly alkaline pH. Overall, these mutants exhibit severe growth defects and have reduced acute virulence in mice. In survival mode, ΔTgPiT parasites upregulate several genes, including those encoding enzymes that cleave or transfer phosphate groups from phosphometabolites, transporters and ions exchangers localized to VAC or acidocalcisomes. Taken together, these findings point to a critical role of TgPiT for Pi supply for Toxoplasma and also for protection against osmotic stresses.

Deeper and Deeper on the Role of BK and Kir4.1 Channels in Glioblastoma Invasiveness: A Novel Summative Mechanism?

In the last decades, increasing evidence has revealed that a large number of channel protein and ion pumps exhibit impaired expression in cancers. This dysregulation is responsible for high proliferative rates as well as migration and invasiveness, reflected in the recently coined term oncochannelopathies. In glioblastoma (GBM), the most invasive and aggressive primary brain tumor, GBM cells modify their ionic equilibrium in order to change their volume as a necessary step prior to migration. This mechanism involves increased expression of BK channels and downregulation of the normally widespread Kir4.1 channels, as noted in GBM biopsies from patients. Despite a large body of work implicating BK channels in migration in response to an artificial intracellular calcium rise, little is known about how this channel acts in GBM cells at resting membrane potential (RMP), as compared to other channels that are constitutively open, such as Kir4.1. In this review we propose that a residual fraction of functionally active Kir4.1 channels mediates a small, but continuous, efflux of potassium at the more depolarized RMP of GBM cells. In addition, coinciding with transient membrane deformation and the intracellular rise in calcium concentration, brief activity of BK channels can induce massive and rapid cytosolic water loss that reduces cell volume (cell shrinkage), a necessary step for migration within the brain parenchyma.

Effect of scandium and zirconium alloying on microstructure and gaseous hydrogen storage properties of YFe3

RM3 compounds (R = rare earth metals, M = transition metals) have rarely been studied for gaseous hydrogen storage applications because of unfavorable thermodynamics. In this work, the hydrogen storage properties of a single-phase YFe3 alloy were improved by non-stoichiometric composition and alloying with Sc and Zr. Only the Y1.1–yScyFe3 (y = 0.22, 0.33) alloys consist of a single rhombohedral phase. The Sc substitution for Y leads to the reduction in the unit cell volume of the YFe3 phase, and thus significantly increases the dehydriding equilibrium pressure and decreases the dehydrogenation temperature. The alloy Y0.77Sc0.33Fe3 delivers a decomposition enthalpy change of 33.54 kJ/mol and a lowest dehydrogenation temperature of 135 °C, in comparison with 38.99 kJ/mol and 165 °C for the alloy Y1.1Fe3. The Zr substitution causes a similar thermodynamic destabilization effect, but the composition and microstructure of Y–Zr–Fe alloys need to be further optimized.

E-cigarette constituents propylene glycol and vegetable glycerin decrease glucose uptake and its metabolism in airway epithelial cells in vitro.

Electronic nicotine delivery systems, or e-cigarettes, utilize a liquid solution that normally contains propylene glycol (PG) and vegetable glycerin (VG) to generate vapor and act as a carrier for nicotine and flavorings. Evidence indicated these “carriers” reduced growth and survival of epithelial cells including those of the airway. We hypothesized that 3% PG or PG mixed with VG (3% PG/VG, 55:45) inhibited glucose uptake in human airway epithelial cells as a first step to reducing airway cell survival. Exposure of H441 or human bronchiolar epithelial cells (HBECs) to PG and PG/VG (30–60 min) inhibited glucose uptake and mitochondrial ATP synthesis. PG/VG inhibited glycolysis. PG/VG and mannitol reduced cell volume and height of air-liquid interface cultures. Mannitol, but not PG/VG, increased phosphorylation of p38 MAPK. PG/VG reduced transepithelial electrical resistance, which was associated with increased transepithelial solute permeability. PG/VG decreased fluorescence recovery after photobleaching of green fluorescent protein-linked glucose transporters GLUT1 and GLUT10, indicating that glucose transport function was compromised. Puffing PG/VG vapor onto the apical surface of primary HBECs for 10 min to mimic the effect of e-cigarette smoking also reduced glucose transport. In conclusion, short-term exposure to PG/VG, key components of e-cigarettes, decreased glucose transport and metabolism in airway cells. We propose that this was a result of PG/VG reduced cell volume and membrane fluidity, with further consequences on epithelial barrier function. Taking these results together, we suggest these factors contribute to reduced defensive properties of the epithelium. We propose that repeated/chronic exposure to these agents are likely to contribute to airway damage in e-cigarette users.

Reactivation of fatty acid oxidation by medium chain fatty acid prevents myocyte hypertrophy in H9c2 cell line.

Metabolic shift is an important contributory factor for progression of hypertension-induced left ventricular hypertrophy into cardiac failure. Under hypertrophic conditions, heart switches its substrate preference from fatty acid to glucose. Prolonged dependence on glucose for energy production has adverse cardiovascular consequences. It was reported earlier that reactivation of fatty acid metabolism with medium chain triglycerides ameliorated cardiac hypertrophy, oxidative stress and energy level in spontaneously hypertensive rat. However, the molecular mechanism mediating the beneficial effect of medium chain triglycerides remained elusive. It was hypothesized that reduction of cardiomyocyte hypertrophy by medium chain fatty acid (MCFA) is mediated by modulation of signaling pathways over expressed in cardiac hypertrophy. The protective effect of medium chain fatty acid (MCFA) was evaluated in cellular model of myocyte hypertrophy. H9c2 cells were stimulated with Arginine vasopressin (AVP) for the induction of hypertrophy. Cell volume and secretion of brain natriuretic peptide (BNP) were used for assessment of cardiomyocyte hypertrophy. Cells were pretreated with MCFA (Caprylic acid) and metabolic modulation was assessed from the expression of medium-chain acyl-CoA dehydrogenase (MCAD), cluster of differentiation-36 (CD36) and peroxisome proliferator-activated receptor (PPAR)-α mRNA. The signaling molecules modified by MCFA was evaluated from protein expression of mitogen activated protein kinases (MAPK: ERK1/2, p38 and JNK) and Calcineurin A. Pretreatment with MCFA stimulated fatty acid metabolism in hypertrophic H9c2, with concomitant reduction of cell volume and BNP secretion. MCFA reduced activated ERK1/2, JNK and calicineurin A expression mediated by AVP. In conclusion, the beneficial effect of MCFA is possibly mediated by stimulation of fatty acid metabolism and modulation of MAPK and Calcineurin A.

Evaluation of structural, optical, dielectric, electrical, and magnetic properties of Ce3+ doped Cu0.5Cd0.25Co0.25Fe2-xO4 spinel nano-ferrites

Rare earth cerium (Ce3+) doped Cu0.5Cd0.25Co0.25CexFe2-x O4 (x = 0, 0.0125, 0.025, 0.0375, 0.05) spinel ferrites nanoparticles were synthesized via co-precipitation technique. XRD, FT-IR, UV-VIS, VSM, LCR and current-voltage measurement techniques were utilized to investigate the structural parameters, metal stretching vibrations, indirect energy band gap, magnetic parameters and electrical behavior of synthesized ferrite powders respectively. The XRD patterns confirmed the remarkable reduction in crystallites size, cell volume and lattice constant while both densities (ρx,ρbulk) tends to increase with rise in Ce3+contents(x). The indirect energy band gaps (Eg) and the DC electrical resistivities were found in decreasing order from 3.48 to 2.50 eV and 9.902×107 to 0.142×107(ohm-cm) respectively at room temperature (303 K) with Ce3+ doping concentration. LCR meter inveterate that the dielectric constant had declining, and ac conductivity had growing trend at fix value of cerium concentration with rise of frequency from 8 Hz to 8 MHz. The soft magnetic properties can be significantly improved by the small amount of Ce3+ ion doping (x = 0.0375) with an increase of the saturation magnetization (Ms), and retentivity (Mr).

Unit cell volume reduction of Gd5(Si,Ge)4 nanoparticles controlled by bulk compressibility

The production of Gd5(Si,Ge)4 compounds in reduced dimensionality, through pulsed laser deposition (PLD), have shown their potential for practical applications. Here, we present nanoparticles ranging from 10 to 27 nm of average particle size of Gd5(SixGe1−x)4, with x = 0, 0.45 and 0.60, obtained using an Nd:Yag (1064 nm) and an Excimer KrF laser (248 nm). Synchrotron X-ray Diffraction measurements revealed a reduced unit cell volume in comparison to their bulk counterpart. The x = 0 sample presented a ∼1.99% reduction while x = 0.45 composition, a shrinkage of ∼1.81% on the unit cell volume that are a result of a structural change to a Gd5Si4-type structure [O(I)]. In contrast, x = 0.60 nanoparticles conserve the bulk crystal structure with ∼ 0.95% of volume shrinkage. As a consequence, there is a change on the magnetic transition order from a first to a second one for all nanostructures followed by a magnetocaloric response reduction. These observations unveil a direct correlation between the bulk compressibility values and the unit cell shrinkage, suggesting that the rise of a surface stress plays a major role on the particle and unit cell dimensions.

Calcium dynamically alters erythrocyte mechanical response to shear

Red blood cells (RBC) are constantly exposed to varying mechanical forces while traversing the cardiovascular system. Upon exposure to mechanical stimuli (e.g., shear stress), calcium enters the cell and prompts potassium-efflux. Efflux of potassium is accompanied by a loss of intracellular fluid; thus, the volume of RBC decreases proportionately (i.e., ‘Gárdos effect’). The mechanical properties of the cell are subsequently impacted due to complex interactions between cytosolic viscosity (dependent on cell hydration), the surface-area-to-volume ratio, and other molecular processes. The dynamic effects of calcium on RBC mechanics are yet to be elucidated, although accumulating evidence suggests a vital role. The present study thus examined the effects of calcium on contemporary biomechanical properties of RBC in conjunction with high-precision geometrical analyses with exposure to shear. Mechanical stimulation of RBC was performed using a co-axial Couette shearing system to deform the cell membrane; intracellular signaling events were observed via fluorescent imaging. Calcium was introduced into RBC using ionophore A23187. Increased intracellular calcium significantly impaired RBC deformability; these impairments were mediated by a calcium-induced reduction of cell volume through the Gárdos channel. Extracellular calcium in the absence of the ionophore only had an effect under shear, not at stasis. Under low shear, the presence of extracellular calcium induced progressive lysis of a sub-population of RBC; all remaining RBC exhibited exceptional capacity to deform, implying preferential removal of potentially aged cells. Collectively, we provide evidence of the mechanism by which calcium acutely regulates RBC mechanical properties.

Systematic quantitative analysis of ribosome inventory during nutrient stress.

SUMMARYMammalian cells reorganize their proteomes in response to nutrient stress via translational suppression and degradative mechanisms using the proteasome and autophagy systems1,2. Ribosomes are central targets of this response, as they are responsible for translation and subject to lysosomal turnover upon nutrient stress3–5. Ribosomal (r)-protein abundance (~6% of the proteome, ~107 copies/cell)6,7 and their enrichment in arginine (Arg) and lysine (Lys) residues has led to the hypothesis that they are selectively used as a source of basic AAs during nutrient stress via autophagy4. However, the relative contributions of translational and degradative mechanisms to the control of r-protein abundance during acute stress responses is poorly understood, as is the extent to which r-proteins are employed to generate AAs when specific building blocks are limited7. Here, we integrate quantitative global translatome and degradome proteomics8 with genetically encoded Ribo-Keima5 and Ribo-Halo reporters to interrogate r-protein homeostasis with and without active autophagy. Upon acute nutrient stress, cells strongly suppress r-protein translation, but, remarkably, r-protein degradation occurs largely through non-autophagic pathways. Simultaneously, loss of r-protein abundance is compensated for by reduced dilution of pre-existing ribosomes and reduced cell volume, thereby maintaining ribosome density within single cells. Withdrawal of basic or hydrophobic AAs induces translational repression without differential induction of ribophagy, indicating that ribophagy is not used to selectively produce basic amino acids during acute nutrient stress. We present a quantitative framework describing the contributions of biosynthetic and degradative mechanisms to r-protein abundance and proteome remodeling during nutrient stress.

Effect of strontium doping on the structural and dielectric properties of YCrO3

Study of multiferroic Y1−xSrxCrO3 (x = 0.0, 0.1) chromite obtained through solid-state reaction technique is presented. The Rietveld refinement of the XRD profile shows the orthorhombic Pbnm crystal symmetry of the system. The bandgaps of YCrO3 and Y0.9Sr0.1CrO3 samples are found as ~ 2.31 and ~ 2.23 eV, respectively. The FTIR spectra peaks show a red shift in the case of Sr2+ ion doping in YCrO3 indicating the reduction in cell volume. Two dielectric relaxation peaks are observed in the YCrO3 , whereas Y0.9Sr0.1CrO3 shows only one broad peak that is found to be extremely frequency dependent. The dielectric peak maxima shifts to higher temperatures with an increase in frequency in both the samples. This kind of dielectric variation is indicating a relaxor type of dielectric material. It is noted that the observed conductive process is closely associated with thermally stimulated oxygen vacancies. The P–E loops of both the samples have completely round shape with maximum polarization (Pmax) being observed at zero electric field. For YCrO3, the mechanism of leakage current conduction is in good agreement with the Ohmic conduction mechanism, whereas Y0.9Sr0.1CrO3 agrees well with space charge-limited conduction mechanism. The decreased bandgap and leakage current makes the Sr2+ ion doping beneficial for various electronic applications.

Densification-Induced Structure Changes in Basolite MOFs: Effect on Low-Pressure CH4 Adsorption.

Metal-organic frameworks’ (MOFs) adsorption potential is significantly reduced by turning the original powder into pellets or granules, a mandatory step for their use at industrial scale. Pelletization is commonly performed by mechanical compression, which often induces the amorphization or pressure-induced phase transformations. The objective of this work is the rigorous study of the impact of mechanical pressure (55.9, 111.8 and 186.3 MPa) onto three commercial materials (Basolite C300, F300 and A100). Phase transformations were determined by powder X-ray diffraction analysis, whereas morphological changes were followed by nitrogen physisorption. Methane adsorption was studied in an atmospheric fixed bed. Significant crystallinity losses were observed, even at low applied pressures (up to 69.9% for Basolite C300), whereas a structural change occurred to Basolite A100 from orthorhombic to monoclinic phases, with a high cell volume reduction (13.7%). Consequently, adsorption capacities for both methane and nitrogen were largely reduced (up to 53.6% for Basolite C300), being related to morphological changes (surface area losses). Likewise, the high concentration of metallic active centers (Basolite C300), the structural breathing (Basolite A100) and the mesopore-induced formation (Basolite F300) smooth the dramatic loss of capacity of these materials.

Alkylimidazolium Ionic Liquids as Antifungal Alternatives: Antibiofilm Activity Against Candida albicans and Underlying Mechanism of Action.

Candida albicans is an opportunistic pathogen causes fungal infections that range from common skin infections to persistent infections through biofilm formation on tissues, implants and life threatening systemic infections. New antifungal agents or therapeutic methods are desired due to high incidence of infections and emergence of drug-resistant strains. The present study aimed to evaluate (i) the antifungal and antibiofilm activity of 1-alklyl-3-methyl imidazolium ionic liquids ([CnMIM]+[X]–, n = 4, 12 and 16) against Candida albicans ATCC 10231 and two clinical C. albicans strains and (ii) the mechanism of action of promising antifungal ionic liquid on C. albicans. Two of the tested compounds were identified as more effective in preventing growth and biofilm formation. These ionic liquid compounds with –dodecyl and –hexadecyl alkyl groups effectively prevented biofilm formation by fluconazole resistant C. albicans 10231 and two other clinical C. albicans strains. Although both the compounds caused viability loss in mature C. albicans biofilms, an ionic liquid with –hexadecyl group ([C16MIM]+[Cl]–) was more effective in dispersing mature biofilms. This promising ionic liquid compound ([C16MIM]+[Cl]–) was chosen for determining the underlying mode of action on C. albicans cells. Light microscopy showed that ionic liquid treatment led to a significant reduction in cell volume and length. Increased cell membrane permeability in the ionic liquid treated C. albicans cells was evident in propidium iodide staining. Leakage of intracellular material was evident in terms of increased absorbance of supernatant and release of potassium and calcium ions into extracellular medium. A decrease in ergosterol content was evident when C. albicans cells were cultured in the presence of antifungal ionic liquid. 2′,7′-Dichlorodihydrofluorescein acetate assay revealed reactive oxygen species generation and accumulation in C. albicans cells upon treatment with antifungal ionic liquid. The effect of antifungal ionic liquid on mitochondria was evident by decreased membrane potential (measured by Rhodamine 123 assay) and loss of metabolic activity (measured by MTT assay). This study demonstrated that imidazolium ionic liquid compound exert antifungal and antibiofilm activity by affecting various cellular processes. Thus, imidazolium ionic liquids represent a promising antifungal treatment strategy in lieu of resistance development to common antifungal drugs.

Impact of aluminum substitution on the structural and dielectric properties of Ni–Cu spinel ferrite nanoparticles synthesized via sol–gel route

Aluminum substituted nickel copper Ni0.5Cu0.5AlxFe2 − xO4 (x = 0.0, 0.2, 0.4 and 0.6) spinel ferrite nanoparticles were prepared via sol–gel auto combustion method. All the samples were annealed at 600 °C for three hours in muffle furnace. The prepared samples were characterized using X-ray diffraction, scanning electron microscopy, Fourier transform infra-red spectroscopy and Impedance Spectroscopy to investigate their structure, morphology and electrical properties. The cubic structure (FCC) with preferred orientation along (311) plane was found with crystallite size of 17–21 nm. Few diffraction peaks corresponding to the secondary phase appear due to insufficient reaction between Al3+ and Fe3+ ions. Lattice constant, unit cell volume, dislocation density, stacking fault, lattice strain and micro-strain have been studied as a function of substitution effect. The appropriate substitution is evident from reduction in lattice strain and unit cell volume resulted from significant change in lattice parameters. The real and imaginary parts of dielectric constant, complex modulus, impedance and tangent loss of prepared nanoparticles have been investigated in the frequency range from 100 Hz to 20 MHz. The hopping of charge carriers at higher frequencies would result in improved conduction mechanism for these nanomaterials. Small crystallite size and low dielectric loss of aluminum substituted nickel copper spinel ferrite nanoparticles would make them potential candidate for high storage memory devices, cancer treatment and microwave applications, respectively.