Decrease In Cell Volume Research Articles

Essential oil and monensin affect ruminal fermentation and the protozoal population in continuous culture

The interaction of monensin and essential oil was hypothesized to suppress protozoa and methane production while maintaining normal rumen function. The objective of this study was to determine the effects of feeding monensin (MON) and CinnaGar (CIN, a commercial blend of cinnamaldehyde and garlic oil; Provimi North America, Brookville, OH) on ruminal fermentation characteristics. Continuous culture fermentors (n = 4) were maintained in 4 experimental periods in a 4 × 4 Latin square design. Four dietary treatments were arranged in a 2 × 2 factorial: (1) control diet, 37 g/d of dry matter (40 g/d at ∼92.5% dry matter) of a 50:50 forage:concentrate diet containing no additive; (2) MON at 11 g/909 kg of dry matter; (3) CIN at 0.0043% of dry matter; and (4) a combination of MON and CIN at the levels in (2) and (3). Treatment had no effects on protozoal populations, concentration of NH3N, total N flow of effluent, production of total volatile fatty acids, or flows of conjugated linoleic acid and total C18 fatty acids. The MON decreased acetate:propionate ratio and biohydrogenation of both total C18 and 18:1 cis-9 but increased protozoal generation time, concentration of peptide, and flow of 18:1 trans-11. The MON tended to decrease protozoal counts in effluent and flow of 18:0 but tended to increase propionate production. The CIN decreased true organic matter digestibility and protozoal N flow of effluent but increased nonammonia, nonmicrobial N flow. The CIN tended to decrease protozoal counts, microbial N flow, and neutral detergent fiber digestibility but tended to increase biohydrogenation of total C18, 18:2, and 18:3. The CIN tended to increase isovalerate production. The MON and CIN tended to interact for increased methane production and bacterial N flow. A second experiment was conducted to determine the effects of MON and CIN on protozoal nitrogen and cell volume in vitro. Four treatments included (1) control (feed only), (2) feed + 0.0043% dry matter CIN, (3) feed + 2.82 μM MON, and (4) feed + CIN + MON at the same levels as in (2) and (3). With no interactions, MON addition decreased percentage of protozoa that were motile and tended to decrease cell volume at 6 h. The CIN did not affect cell count or other indicators of motility or volume at either 3 or 6 h. Under the conditions of our study, we did not detect an additive response for MON and CIN to decrease protozoal counts or methane production. A 3-dimensional method is suggested to better estimate protozoal cell volume.

Cellular mechanism for herbal medicine Junchoto to facilitate intestinal Cl\u2212/water secretion that involves cAMP-dependent activation of CFTR

Constipation is a common symptom frequently compromising the quality of daily life. Several mechanistically different drugs have been used to mitigate constipation, including Japanese herbal (Kampo) medicines. However, the mechanisms of their actions are often not well understood. Here we aimed to investigate the molecular mechanisms underlying the effects of Junchoto (JCT), a Kampo medicine empirically prescribed for chronic constipation. Cl− channel activity was measured by the patch-clamp method in human cystic fibrosis transmembrane conductance regulator (CFTR)-expressing HEK293T cells and human intestinal Caco-2 cells. cAMP was measured by a luciferase-based assay. Cell volume change was measured by a particle-sizing and particle-counting analyzer and video-microscopic measurement. In both CFTR-expressing HEK293T and Caco-2 cells, JCT dose-dependently induced whole-cell currents showing typical biophysical and pharmacological features of CFTR. Robust expression of CFTR was confirmed by RT-PCR and Western blotting in Caco-2 cells. Luciferase-based measurement revealed that JCT increases intracellular cAMP levels. Administration of the adenylate cyclase inhibitor SQ22536 or CFTR inhibitor-172, or treatment with small interfering RNAs (siRNA) targeting CFTR, abolished JCT-induced whole-cell currents, suggesting that elevated intracellular cAMP by JCT causes activation of CFTR in Caco-2 cells. Finally, blockade of CFTR activity by CFTR inhibitor-172 or siRNA-knockdown of CFTR or application of SQ22536 markedly reduced the degree of cell volume decrease induced by JCT. JCT can induce a Cl− efflux through the CFTR channel to promote water secretion, and this effect is likely mediated by increased cAMP production.

Properties of La–Sr Manganites with Combined Substitution of Different Valence Ions for Strontium and Manganese

Experimental data on structural, magnetic, and electrical features of manganites of the system La0.65Sr0.35–cCecMn1 – xZn x O3 + γ (c = 0, 0.05; x = 0, 0.05, 0.10), synthesized by ceramic processing, are reported. Part of the samples were annealed under conditions that yield stoichiometric oxygen content. The samples obtained are of rhombohedral structure, but contain the impurity of the CeO2 phase. The introduction of cerium and zinc leads to a decrease in the unit cell volume of the rhombohedral phase. Cerium does not substantially affect the magnetization and Curie point of the initial samples. The width of the “ferromagnetic–paramagnetic” transition temperature interval rises after annealing, especially in manganite with high zinc content. Initial and annealed samples of composition with c = 0.05, x = 0.10 exhibit the phase transition “metal–semiconductor” at temperatures of about 219 K and 200 K, respectively. All other manganites possess a metallic character of conductivity in the range of 100–300 K. The maximum absolute value of magnetoresistance reaches 52%. The approaches to the interpretation of experimental results are discussed.

Hypoxia inhibits the regulatory volume decrease in red blood cells of common frog (Rana temporaria)

Red blood cells of vertebrates can restore their cellular volume after hyposmotic swelling. The process strictly depends on oxygen availability in the environment. However, the role of hemoglobin in regulation of cell volume recovery is not clear yet. Little is known about the osmotic reactions and regulatory volume decrease of amphibian red blood cells. We investigated volume recovery process in oxygenated (oxyhemoglobin concentration 97 ± 3% of total hemoglobin) deoxygenated (96 ± 2% of deoxyhemolobin) and oxidized (47 ± 2% of methemoglobin, 41 ± 3% of deoxyhemoglobin) red blood cells of common frog (Rana temporaria) after hyposmotic swelling. Using the low-angle light scattering method we demonstrated the regulatory volume decrease in oxygenated cells and showed that the process was eliminated in hypoxic conditions. Reoxygenation of hypoxic cells restored the regulatory volume decrease. Oxidation of cellular hemoglobin to methemoglobin inhibited the volume recovery response in hyposmotically swollen oxygenated and reoxygenated hypoxic cells.

Magnetostructural transformation and magnetocaloric effect in Ni42Mn47.5Sn10.5 and Ni41.5Mn47.5Sn10.5Zn0.5 ferromagnetic shape memory alloys

A comparative investigation on magnetostructural transformation and coupled magnetocaloric properties of Ni42Mn47.5Sn10.5 and Ni41.5Mn47.5Sn10.5Zn0.5 ferromagnetic shape memory alloys prepared by arc-melting method is carried out through structural and magnetic measurements. As Zn is doped in NiMnSn alloy, the cell volume decreases and the martensitic transformation temperature increases by 21 K. Obvious metamagnetic behavior and magnetic hysteresis is observed in isothermal magnetization curves, indicating the magnetic field induced magnetostructural transformation. Magnetic field induced phase transition is also confirmed under applied field of 2 T and martensitic transformation temperature is decreased by 4.1 and 5.29 K for Ni42Mn47.5Sn10.5 and Ni41.5Mn47.5Sn10.5Zn0.5 alloys, respectively. The entropy change in Ni41.5Mn47.5Sn10.5Zn0.5 alloy with change in magnetic field from 0 to 2 T is 12.3 J · kg−1 · K−1, which is larger than that in Ni42Mn47.5Sn10.5 alloy. The achieved low field entropy change in Zn doped alloy suggests its potential application as magnetic cooling refrigerant.

Controlling Cellular Volume via Mechanical and Physical Properties of Substrate

The mechanical and physical properties of substrate play a crucial role in regulating many cell functions and behaviors. However, how these properties affect cell volume is still unclear. Here, we show that an increase in substrate stiffness, available spread area, or effective adhesion energy density results in a remarkable cell volume decrease (up to 50%), and the dynamic cell spreading process is also accompanied by dramatic cell volume decrease. Further, studies of ion channel inhibition and osmotic shock suggest that these volume decreases are due to the efflux of water and ions. We also show that disrupting cortex contractility leads to bigger cell volume. Collectively, these results reveal the “mechanism of adhesion-induced compression of cells,” i.e., stronger interaction between cell and substrate leads to higher actomyosin contractility, expels water and ions, and thus decreases cell volume.

Leaves, not roots or floral tissue, are the main site of rapid, external pressure-induced ABA biosynthesis in angiosperms.

Rapid biosynthesis of abscisic acid (ABA) in the leaf, triggered by a decrease in cell volume, is essential for a functional stomatal response. However, it is not known whether rapid biosynthesis of ABA is also triggered in other plant tissues. Through the application of external pressure to flower, root, and leaf tissues, we test whether a reduction in cell volume can trigger rapid increases in ABA levels across the plant body in two species, Solanum lycopersicum and Passiflora tarminiana. Our results show that, in contrast to rapid ABA synthesis in the leaf, flower and root tissue did not show a significant, increase in ABA level in response to a drop in cell volume over a short time frame, suggesting that rapid ABA biosynthesis occurs only in leaf, not in flower or root tissues. A gene encoding the key, rate-limiting carotenoid cleavage enzyme (9-cis-epoxycarotenoid dioxygenase, NCED) in the ABA biosynthetic pathway in S. lycopersicum, NCED1, was upregulated to a lesser degree in flowers and roots compared with leaves in response to applied pressure. In both species, floral tissues contained substantially lower levels of the NCED substrate 9’-cis-neoxanthin than leaves, and this ABA precursor could not be detected in roots. Slow and minimal ABA biosynthesis was detected after 2 h in petals, indicating that floral tissue is capable of synthesizing ABA in response to sustained water deficit. Our results indicate that rapid ABA biosynthesis predominantly occurs in the leaves, and not in other tissues.

Valence state of cations in manganites Pr1-xCaxMnO3 (0.3 ≤ x ≤ 0.5) from X-ray diffraction and X-ray photoelectron spectroscopy

Polycrystalline Pr1-xCaxMnO3 (х = 0.3, 0.35, 04, 0.45, and 0.5) samples are synthesized by solid-state reaction method. Crystal structure of the samples is studied by X-ray diffraction method with Rietveld refinement. Diffraction patterns from all the samples are well indexed within the Pnma space group. It is shown that lattice parameters and unit cell volume decrease monotonically and O−Mn−O angles become closer to the ideal 180⁰ value upon the growth of x. Mn2p, Mn3s, Ca2p, Pr3d, Pr4d, and O1s X-ray photoelectron spectra are measured. Pr3d and Pr4d spectra are calculated in isolated ion approximation with approximate accounting for the charge transfer effect. Elemental compositions of samples are measured by the XPS method; they differ noticeably from the nominal ones. Charge compensation upon heterovalent Pr3+ → Ca2+ substitution is shown to realize via two mechanisms: creation of oxygen vacancies and formation of Mn4+ ions coexisting with Mn3+. Relative Mn4+/Mn3+ abundances are determined via decomposition of Mn2p and Mn3s XPS into contributions from the spectra of tri- and quadrivalent Mn ions. The amount of Mn4+ ions is shown to increase with Ca content x.

Inhibition of Collagen Related Peptide Induced Platelet Activation and Apoptosis by Ceritinib

Background/Aims: The anaplastic lymphoma (tyrosine) kinase (ALK) inhibitor ceritinib triggers apoptosis of tumor cells and eryptosis of erythrocytes. Blood platelets may similarly enter a state resembling apoptosis, which could be triggered by activation with collagen related peptide (CRP). CRP-induced platelet apoptosis is characterized by cell membrane scrambling with phosphatidylserine exposure to the platelet surface and cell shrinkage, preceded by externalization of Ca²⁺ channel Orai1, increase of cytosolic Ca²⁺-activity ([Ca²⁺]_i), formation of reactive oxygen species (ROS), and caspase activation. The present study explored whether ceritinib triggers platelet apoptosis and/or modifies the CRP induced apoptosis. Methods: Platelets isolated from wild-type mice were exposed for 30 minutes to ceritinib (1.5 µg/ml) without or with 2.5 – 15 min pretreatment with CRP (2 µg/ml or 5 µg/ml). Flow cytometry was employed to estimate cytosolic Ca²⁺-activity ([Ca²⁺]_i) from Fluo-3 fluorescence, ROS abundance from 2’,7’-dichlorodihydrofluorescein diacetate fluorescence, platelet degranulation from P-selectin abundance, integrin activation from α_IIbβ₃ integrin abundance, caspase activity utilizing an Active Caspase-3 Staining kit, phosphatidylserine abundance from annexin-V-binding, platelet volume from forward scatter and aggregation utilizing staining with CD9-APC and CD9-PE. Results: In the absence of CRP, ceritinib slightly, but significantly decreased [Ca²⁺]_i without significantly modifying the other measured parameters. CRP significantly increased [Ca²⁺]_i, ROS abundance, P-selectin abundance, activated α_IIbβ₃ integrin, annexin-V-binding, caspase activity as well as aggregation and decreased cell volume, all effects significantly blunted in the presence of ceritinib. Conclusions: The present observations uncover a novel, unexpected effect of ceritinib, i.e. inhibition of CRP-induced platelet activation and apoptosis.

Electrochemically Reduced Water: Modification of the Incubation Medium and Oxidative Activity

It has been shown that Dulbecco’s incubation medium prepared with electrochemically reduced water compensates for oxidative stress induced by hydrogen peroxide addition (H2O2, 0.2 mM) to the incubation medium. The incubation medium modified in this way does not affect the H2O2 induced apoptosis in an early mouse embryo. The embryonic cell in the experimental model of apoptosis shows the presence of characteristic morphological changes and decreased cell volume. These apoptosis-related changes were detected using laser-scanning microtomography.

Simultaneous Operando Characterization of Crystallographic and Electrochemical Properties of Ni-Ce0.9Gd0.1O2-δ Solid Oxide Fuel Cell Anode

A novel dual chamber (DC) measurement cell has been implemented for simultaneous monitoring of crystallographic and electrochemical (EC) properties of Ni-Ce0.9Gd0.1O2−δ (Ni-GDC) solid oxide fuel cell (SOFC) anode at different fuel cell polarizations. The influence of system parameters (temperature, oxygen partial pressure in anode compartment and oxide ion flux through the electrolyte membrane from the cathode to the anode) on the crystallographic structure of GDC and redox performance of Ni has been studied. The oxide ion flux through the membrane from cathode to anode leads to increase of oxygen partial pressure in anode layers close to electrolyte. Increase of oxygen partial pressure leads to decrease of unit cell volume of the GDC lattice. The observed average change of GDC lattice parameter was 0.0147 Å V−1 at 800°C. The oxidation of Ni caused by oxide ion flux at high fuel cell loads has been detected electrochemically but not from XRD results.

AMPK-dependent nitric oxide release provides contractile support during hyperosmotic stress

In different pathological situations, cardiac cells undergo hyperosmotic stress (HS) and cell shrinkage. This change in cellular volume has been associated with contractile dysfunction and cell death. Given that nitric oxide (NO) is a well-recognized modulator of cardiac contractility and cell survival, we evaluated whether HS increases NO production and its impact on the negative inotropic effect observed during this type of stress. Superfusing cardiac myocytes with a hypertonic solution (HS: 440mOsm) decreased cell volume and increased NO-sensitive DAF-FM fluorescence compared with myocytes superfused with an isotonic solution (IS: 309mOsm). When cells were exposed to HS in addition to different inhibitors: L-NAME (NO synthase inhibitor), nitroguanidine (nNOS inhibitor), and Wortmannin (eNOS inhibitor) cell shrinkage occurred in the absence of NO release, suggesting that HS activates nNOS and eNOS. Consistently, western blot analysis demonstrated that maintaining cardiac myocytes in HS promotes phosphorylation and thus, activation of nNOS and eNOS compared to myocytes maintained in IS. HS-induced nNOS and eNOS activation and NO production were also prevented by AMPK inhibition with Dorsomorphin (DORSO). In addition, the HS-induced negative inotropic effect was exacerbated in the presence of either L-NAME, DORSO, ODQ (guanylate cyclase inhibitor), or KT5823 (PKG inhibitor), suggesting that NO provides contractile support via a cGMP/PKG-dependent mechanism. Our findings suggest a novel mechanism of AMPK-dependent NO release in cardiac myocytes with putative pathophysiological relevance determined, at least in part, by its capability to reduce the extent of contractile dysfunction associated with hyperosmotic stress.

Changes in the fluid volume balance between intra- and extracellular water in a sample of Japanese adults aged 15-88 yr old: a cross-sectional study.

The fluid volume balance between intracellular water (ICW) and extracellular water (ECW) gradually changes with age and various medical conditions. Comprehension of these physiological changes would aid in clinical decision-making related to body fluid assessments. A total of 1,992 individuals (753 men and 1,239 women) aged ≥15 yr included in this study had their body composition measurements performed at training gyms in 2014. We developed a regression formula to assess the association of age with the ratio of ECW to ICW in these subjects. The mean ages of male and female subjects were 51.2 ± 15.2 and 57.4 ± 15.2 yr, and their mean body mass indexes were 23.4 ± 3.3 and 21.1 ± 2.8 kg/m2, respectively. The total fluid volumes of male and female subjects were 39.6 ± 4.9 and 27.7 ± 3.0 liters, whereas the percent body fat mass per kilogram of body weight were 19 and 26%, respectively. The ECW-to-ICW ratio increased with age because of the steeper decrease in the ICW content than in the ECW content, especially after the age of 70 yr. The regression formulas used for calculating the age-adjusted ECW/ICW ratio were as follows: 0.5857 + 7.4334 × 10-6 × (age)2 in men and 0.6062 + 5.5775 × 10-6 × (age)2 in women. In conclusion, the fluid imbalance between ICW and ECW contents is driven by decreased cell volume associated with aging and muscle attenuation. Therefore, our proposed formula may serve as a useful assessment tool for the calculation of body fluid composition.

Structural, dielectric and impedance study of Bi and Li co-substituted Ba0.50Sr0.50TiO3 ceramics for tunable microwave devices applications

In this article, the structural, dielectric and electrical properties of Bi and Li co-substituted (Ba, Sr) site in Ba0.50Sr0.50TiO3 ceramics are presented. Four different compositions of Ba0.50Sr0.50TiO3, (Ba0.50Sr0.50)0.98(Bi, Li)0.02TiO3, (Ba0.50Sr0.50)0.96(Bi, Li)0.04TiO3, and (Ba0.50Sr0.50)0.92(Bi, Li)0.08TiO3 were synthesized using solid-state reaction with microwave heating of starting materials. Phase detection for all samples has been examined by XRD along with Rietveld refinement analyses, and the results show the formation of single phase without observation of any secondary phase. However, a decrease in crystallite size, lattice parameters, and unit cell volume has been observed with the increase of Bi and Li concentration. A Dense microstructure with different grains sizes and shapes has been obtained by scanning electron microscopy. Impedance spectroscopy in the temperature range of 30–300 °C and frequency range of 60 Hz–1 MHz has been used to study the dielectric properties. The result shows that the Bi and Li co-substituted Ba0.5Sr0.5TiO3 ceramics exhibit very interesting features, such as enhanced dielectric constant with low loss which make it suitable for microwave tunable devices applications. An electric impedance analysis was carried out at different temperatures namely (400, 450, 500, and 550 °C). A single semicircular arc with single relaxation process has been observed in all studied samples which suggest that the grains contribute to the total resistance in these materials. The activation energy was obtained from the impedance analysis using Arrhenius plot of grain conductivity.

Computational Design of Perovskite BaxSr1–xSnO3 Alloys as Transparent Conductors and Photocatalysts

Using a first-principles-based multiscale computational approach involving density functional theory and the cluster expansion method, we produced the structural evolution for the perovskite BaxSr1–xSnO3 system in relation to its Ba:Sr composition from the formation energies of different alloy configurations and demonstrated their use as tunable alloy transparent conductors and photocatalysts via structural, electronic, and optical studies. The predicted phase diagram revealed the transformation of the structure of BaxSr1–xSnO3 from orthorhombic to tetragonal and finally to cubic with increasing x, forming disordered solid solutions for 0 < x < 1 that is entropically stabilized against phase segregation. This trend is similarly observed in the published experiments. A special quasirandom structure approach is used to model the disordered solid solutions of the BaxSr1–xSnO3 alloys. Structural analyses have indicated that the decrease in Ba:Sr ratio is associated with the decrease in unit cell volume, and a...

Between Scylla and Charybdis: Balancing Among Structural Stability and Energy Density of Layered NCM Cathode Materials for Advanced Lithium-Ion Batteries

Two major strategies are currently pursued to improve the energy density of lithium-ion batteries using LiNixCoyMnzO2 (NCM) cathode materials. One is to increase the fraction of redox active Ni (≥80%), which allows larger amounts of Li to be extracted at a given cutoff voltage (Umax). The other is to increase Umax, in particular for medium-Ni content NCM materials. However, the accompanying lattice changes ultimately lead to capacity fading in both cases. Here the structural changes occurring in Li1.02NixCoyMnzO2 (with x = 1/3, 0.5, 0.6, 0.7, 0.8 and 0.85) during cycling operation in the voltage range between 3.0 and 4.6 V vs Li are quantified by means of operando X-ray diffraction combined with detailed Rietveld analysis. All samples show a large decrease in unit cell volume upon charging, ranging from 2.4% for NCM111 (33% Ni) to 8.0% for NCM851005 (85% Ni). To make a fair comparison of the structural stability of the different NCM materials, energy densities as a function of Umax are estimated and corre...

Charge-Transfer-Induced Lattice Collapse in Ni-Rich NCM Cathode Materials during Delithiation

Ni-rich LiNixCoyMnzO2 (NCM) cathode materials have great potential for application in next-generation lithium-ion batteries owing to their high specific capacity. However, they are subjected to severe structural changes upon (de)lithiation, which adversely affects the cycling stability. Herein, we investigate changes in crystal and electronic structure of NCM811 (80% Ni) at high states of charge by a combination of operando X-ray diffraction (XRD), operando hard X-ray absorption spectroscopy (hXAS), ex situ soft X-ray absorption spectroscopy (sXAS), and density functional theory (DFT) calculations and correlate the results with data from galvanostatic cycling in coin cells. XRD reveals a large decrease in unit cell volume from 101.38(1) to 94.26(2) A3 due to collapse of the interlayer spacing when x(Li) < 0.5 (decrease in c-axis from 14.469(1) A at x(Li) = 0.6 to 13.732(2) A at x(Li) = 0.25). hXAS shows that the shrinkage of the transition metal–oxygen layer mainly originates from nickel oxidation. sXAS, ...

Laser induced adjustment of the conductivity of rare earth doped Mn-Zn nanoferrite

AbstractTwo series of Mn-Zn nanoferrites (namely Mn1-xZnxFe2O4and Mn1-xZnxFe2-yRyO4) were synthesized using standard ceramic technique. X-ray diffraction and FT-IR were employed in the chacterization of the nanopowder. The X-ray density for each sample increased after laser irradiation which was correlated with the decrease in the unit cell volume. The study involved the thermal and frequency variation of the dielectric constant and AC conductivity of the investigated samples before and after laser irradiation. The later altered the conductivity by decreasing its value for the rare earth doped samples except for the Sm3+doped one. The results suggested the exploitation of Mn-Zn doped rare earth nanoferrites in many technological applications demanding high resistivity.

On the role of disorder produced by manganese vacancy at the B site on the structural and magnetic properties of [formula omitted] nanocrystalline

Single-phase perovskite-type manganese oxides La0.67Ba0.33Mn1−xO3 with x = 0.00–0.08 have been prepared by the modified sol–gel method (Pechini) and the influence of the vacancy concentration in the B-site on their structures and magnetic properties has systematically been investigated. The structural elucidation of the synthesized materials was carried out by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy. Rietveld analysis of fitted and observed X-ray diffraction patterns exhibited the single-phase nature of all the studied materials, which crystallize in R3¯c space group. The average crystallite size was found to be around 56 nm. FTIR spectra present the prominent absorption peak of the in-phase stretching mode (B2g mode) rising from the vibration of MnO bond length. Raman spectra at room temperature reveal a gradual change in phonon modes with increasing B-site vacancy concentration. All the samples undergo a ferro-to paramagnetic transition, at temperatures that vary from 335 to 216 K as the manganese vacancy increases. As follows from the results of structural and magnetic analyses, creating a vacancy at the Mn site (increase of chemical disorder) induces the formation of Mn4+ ions, which results in the decrease of unit cell volume and leads to a shortage of 3d electrons of the transition metal.

Structural phase transitions, phase separation and physical properties for the 122-system iron-based superconductors

The discovery of iron-based superconductors stimulated the second research upsurge for high-temperature superconductors, which have been considered as one of the significant research field from both academic and technological points of view. It is noted that the studies of iron-based superconductors have brought a great development of a large number of experimental technologies and theoretical researches in superconductivity physics. The remarkable correlations between structural transitions and multiple ordered states have been observed in the typical iron-based superconductors. According to the microstructure analyses and in-situ transmission electron microscopy (TEM) investigations, AFe2As2 (A=Ba, Sr and Ca) iron-based superconducting materials often show up a structural transition from tetragonal phase to orthorhombic phase from room temperature down to 20 K, resulting in visible twinning domains in the orthorhombic phase. The tetragonal SrFe2As2 samples, consistent with X-ray and neutron-diffraction data, undergo the tetragonal- orthorhombic phase transition at about 205 K and show clear twin domains in the orthorhombic phase. On the other hand, TEM observations of CaFe2As2 reveal the presence of a pseudoperiodic structural modulation with a periodicity of around 40 nm at room temperature. This quasi-periodicity structural modulation is likely related to the local structural distortions within the Ca layers. In situ cooling TEM observations of CaFe2As2 reveal the presence of complex domain structures in the low-temperature orthorhombic phase. Phase separation and structural inhomogeneity as critical structural issues have been extensively investigated in a variety of strongly correlated systems. The phase separations associated with structural domains result visibly structural alterations in K y Fe2− x Se2 system. Structural investigations by means of TEM on K0.8Fe x Se2 and KFe x Se2, with 1.5≤ x ≤1.8, have revealed a rich variety of microstructure phenomena. Materials with 1.5≤ x ≤1.6 often show a superstructure modulation along the [310] zone-axis direction, and this modulation can be well interpreted by the Fe-vacancy order, which likely yields a superstructure phase of K2Fe4Se5. The superconducting K0.8Fe x Se2 and KFe x Se2 (1.7≤ x ≤1.8) materials contain clear phase separation, in particular, along the c-axis direction, recognizable as visible parallel lamellae in the crystals; this fact suggests that the superconducting phase could have the Fe-vacancy disordered state. The main changes of physical properties in the AFe2As2 materials have also been discussed. The substitution of A-element in AFe2As2 have a significant effect on the structural properties and spin density wave (SDW), then leads to the appearance and change of superconductivities. Polycrystalline samples of Ba1− x Sr x Fe2As2 (0≤ x ≤1) and Ba1− x Sr x Fe1.8Co0.2As2 (0≤ x ≤1) were synthesized by a solid state reaction method. Structural analysis by means of X-ray diffraction shows that the lattice parameters and unit cell volume decrease monotonically with the increase of x for Ba1– x Sr x Fe2As2. The measurements of transport properties demonstrate that the average size of the Ba(Sr)-site cations could evidently influence the SDW behavior in Ba1− x Sr x Fe2As2 and superconductivity in Ba1− x Sr x Fe1.8Co0.2As2 as well. The critical temperature for SDW ( T SDW) increases with the Sr substitution for Ba in Ba1− x Sr x Fe2As2 and, on the other hand, the superconducting T c decreases with the increase of Sr content in Ba1− x Sr x Fe1.8Co0.2As2. The inhomogeneous distributions of Ba/Sr ions and structural distortions in Ba0.5Sr0.5Fe2As2 have been investigated by TEM observations.