A cellulose synthesis inhibitor affects cellulose synthase complex secretion and cortical microtubule dynamics.

P4B (2-phenyl-1-[4-(6-(piperidin-1-yl) pyridazin-3-yl) piperazin-1-yl] butan-1-one) is a novel cellulose biosynthesis inhibitor (CBI) discovered in a screen for molecules to identify inhibitors of Arabidopsis (Arabidopsis thaliana) seedling growth. Growth and cellulose synthesis inhibition by P4B were greatly reduced in a novel mutant for the cellulose synthase catalytic subunit gene CESA3 (cesa3pbr1). Cross-tolerance to P4B was also observed for isoxaben-resistant (ixr) cesa3 mutants ixr1-1 and ixr1-2. P4B has an original mode of action as compared with most other CBIs. Indeed, short-term treatments with P4B did not affect the velocity of cellulose synthase complexes (CSCs) but led to a decrease in CSC density in the plasma membrane without affecting their accumulation in microtubule-associated compartments. This was observed in the wild type but not in a cesa3pbr1 background. This reduced density correlated with a reduced delivery rate of CSCs to the plasma membrane but also with changes in cortical microtubule dynamics and orientation. At longer timescales, however, the responses to P4B treatments resembled those to other CBIs, including the inhibition of CSC motility, reduced growth anisotropy, interference with the assembly of an extensible wall, pectin demethylesterification, and ectopic lignin and callose accumulation. Together, the data suggest that P4B either directly targets CESA3 or affects another cellular function related to CSC plasma membrane delivery and/or microtubule dynamics that is bypassed specifically by mutations in CESA3.

[Association Between Plasma Homocysteine Level and Hyperuricemia in Elderly Patients With Hypertension].

Objective To explore the association between plasma homocysteine (Hcy) level and hyper-uricemia (HUA) in the elderly patients with hypertension.Methods From March to August in 2018,9902 hypertensive patients ≥ 60 years were routinely tested for blood biochemical indicators in Wuyuan county,Jiangxi province.The patients were assigned into a HUA group and a normal uric acid group.Multivariate Logistic regression was adopted to analyze the relationship between Hcy level and the risk of HUA.Results Compared with the normal uric acid group,the HUA group showed increased incidence of hyperhomocysteinemia (99.9% vs.98.7%,P<0.001) and elevated Hcy level[16.8 (13.8-21.5) µmol/L vs.14.4 (12.3-17.7) µmol/L,P<0.001].The multivariate Logistic regression analysis showed that after adjusting for influencing factors,the risk of HUA in the patients with hyperhomocysteinemia was 2.92 times of that in the patients with a normal Hcy level.The threshold effect analysis showed that the Hcy level was positively correlated with the occurrence of HUA in the case of Hcy<20 µmol/L (OR=1.05,95%CI=1.04-1.07,P<0.001).In the case of Hcy ≥ 20 µmol/L,there was no correlation between Hcy level and HUA (OR=1.00,95%CI=0.99-1.00,P=0.055),and the likelihood ratio test showed statistically significant results (P<0.001).Conclusion The elderly with hypertension should pay attention to control the Hcy level,which will be helpful to prevent the occurrence of HUA.

Foliar nutrient allocation patterns in Banksia attenuata and Banksia sessilis differing in growth rate and adaptation to low-phosphorus habitats.

BACKGROUND AND AIMS: Phosphorus (P) and nitrogen (N) are essential nutrients that frequently limit primary productivity in terrestrial ecosystems. Efficient use of these nutrients is important for plants growing in nutrient-poor environments. Plants generally reduce foliar P concentration in response to low soil P availability. We aimed to assess ecophysiological mechanisms and adaptive strategies for efficient use of P in Banksia attenuata (Proteaceae), naturally occurring on deep sand, and B. sessilis, occurring on shallow sand over laterite or limestone, by comparing the allocation of P among foliar P fractions. METHODS: We carried out pot experiments with slow-growing B. attenuata, which resprouts after fire, and faster growing opportunistic B. sessilis, which is killed by fire, on substrates with different P availability using a randomized complete block design. We measured leaf P and N concentrations, photosynthesis, leaf mass per area, relative growth rate and P allocated to major biochemical fractions in B. attenuata and B. sessilis. KEY RESULTS: The two species had similarly low foliar total P concentrations, but distinct patterns of P allocation to P-containing fractions. The foliar total N concentration of B. sessilis was greater than that of B. attenuata on all substrates. The foliar total P and N concentrations in both species decreased with decreasing P availability. The relative growth rate of both species was positively correlated with concentrations of both foliar nucleic acid P and total N, but there was no correlation with other P fractions. Faster growing B. sessilis allocated more P to nucleic acids than B. attenuata did, but other fractions were similar. CONCLUSIONS: The nutrient allocation patterns in faster growing opportunistic B. sessilis and slower growing B. attenuata revealed different strategies in response to soil P availability which matched their contrasting growth strategy.

Fast photothermal poly(NIPAM-co-ß-cyclodextrin) supramolecular hydrogel with self-healing through host-guest interaction for intelligent light-controlled switches.

A graphene oxide/poly(N-isopropylacrylamide-co-ß-cyclodextrin) (GO/poly(NIPAM-co-ß-CD)) hydrogel has been synthesized through host-guest interaction between ß-cyclodextrin (ß-CD) and the isopropyl group of N-isopropylacrylamide (NIPAM). The product exhibits rapid responses to the stimuli of temperature and near-infrared (NIR) irradiation, self-healing properties, and excellent mechanical properties. The host-guest interaction serves as the main physical cross-linker, while a hydrogen bond between the hydroxyl group of ß-CD, GO sheets and amide group of NIPAM acts as a secondary cross-linker. The volume phase transition temperature and NIR response rate of such a hydrogel are controlled by its contents of ß-CD and GO. The obtained hydrogels showing excellent properties might be applied in remote contactless control devices in advanced smart technologies. Based on the excellent characteristics of the hydrogels, remote light-controlled switches have been designed, and more applications will be explored, such as intelligent light-controlled drivers and soft robots.

Model for the role of auxin polar transport in patterning of the leaf adaxial-abaxial axis.

Leaf adaxial-abaxial polarity refers to the two leaf faces, which have different types of cells performing distinct biological functions. In 1951, Ian Sussex reported that when an incipient leaf primordium was surgically isolated by an incision across the vegetative shoot apical meristem (SAM), a radialized structure without an adaxial domain would form. This led to the proposal that a signal, now called the Sussex signal, is transported from the SAM to emerging primordia to direct leaf adaxial-abaxial patterning. It was recently proposed that instead of the Sussex signal, polar transport of the plant hormone auxin is critical in leaf polarity formation. However, how auxin polar transport functions in the process is unknown. Through live imaging, we established a profile of auxin polar transport in and around young leaf primordia. Here we show that auxin polar transport in lateral regions of an incipient primordium forms auxin convergence points. We demonstrated that blocking auxin polar transport in the lateral regions of the incipient primordium by incisions abolished the auxin convergence points and caused abaxialized leaves to form. The lateral incisions also blocked the formation of leaf middle domain and margins and disrupted expression of the middle domain/margin-associated marker gene WUSCHEL-RELATED HOMEOBOX 1 (SlWOX1). Based on these results we propose that the auxin convergence points are required for the formation of leaf middle domain and margins, and the functional middle domain and margins ensure leaf adaxial-abaxial polarity. How middle domain and margins function in the process is discussed.

Manipulating triplet states: tuning energies, absorption, lifetimes, and annihilation rates in anthanthrene derivatives.

The photophysical properties of anthanthrene, four anthanthrene derivatives containing varying phenyl and p-tBu-phenyl substituents, and two anthanthrones with phenyl and p-tBu-phenyl substituents are examined. In general, as the anthanthrenes and anthanthrones become more substituted, red-shifts are observed in the peak maxima of the ground- and excited-state absorption and fluorescence spectra. The anthanthrones have large (>0.8) intersystem crossing (ISC) quantum yields (ΦT) likely caused by nπ* character in the ground or excited states. A bromo-substituted anthanthrene has a unity ISC yield due to an ISC rate constant of 2.5 × 1010 s-1 caused by heavy-atom induced, spin-orbit coupling. This leads to low fluorescence quantum yields (ΦF) in these three derivatives. The parent anthanthrene and remaining derivatives behave much differently. All have ΦF values from 0.58-0.84 with lower ΦT values as radiative decay outcompetes ISC. The anthanthrones have remarkable excited-state absorption with strong, broad transitions across the visible region with weaker transitions extending to nearly two µm. The anthanthrenes have very similar-shaped, broad transitions in the visible which can be shifted ∼60 nm by controlling the substituents. The triplet lifetimes range from 31-1200 µs and increase as the ISC yields decrease; the bromo-substituted anthanthrene is the shortest, followed by the anthanthrones then the other anthanthrenes. The rate of triplet-triplet annihilation is also affected by the presence of substituents; as the amount of steric bulk is increased, the rate of annihilation decreases.

Germostatin resistance locus 1 encodes a PHD finger protein involved in auxin-mediated seed dormancy and germination.

Seed dormancy and germination are important physiological processes during the life cycle of a seed plant. Recently, auxin has been characterized as a positive regulator that functions during seed dormancy and as a negative regulator during germination. Through chemical genetic screenings, we have identified a small molecule, germostatin (GS), which effectively inhibits seed germination in Arabidopsis. GSR1 (germostatin resistance locus 1) encodes a tandem plant homeodomain (PHD) finger protein, identified by screening GS-resistant mutants. Certain PHD fingers of GSR1 are capable of binding unmethylated H3K4, which has been reported as an epigenetic mark of gene transcriptional repression. Biochemical studies show that GSR1 physically interacts with the transcriptional repressor ARF16 and attenuates the intensity of interaction of IAA17/ARF16 by directly interacting with IAA17 to release ARF16. Further results show that axr3-1, arf10 arf16 are hyposensitive to GS, and gsr1 not only resists auxin-mediated inhibition of seed germination but also displays decreased dormancy. We therefore propose that GSR1 may form a co-repressor with ARF16 to regulate seed germination. Besides promoting auxin biosynthesis via upregulating expression of YUCCA1, GS also enhances auxin responses by inducing degradation of DΙΙ-VENUS and upregulating expression of DR5-GFP. In summary, we identified GSR1 as a member of the auxin-mediated seed germination genetic network, and GS, a small non-auxin molecule that specifically acts on auxin-mediated seed germination.

Photodriven Oxygen Removal via Chromophore-Mediated Singlet Oxygen Sensitization and Chemical Capture.

We report a general, photochemical method for the rapid deoxygenation of organic solvents and aqueous solutions via visible light excitation of transition metal chromophores (TMCs) in the presence of singlet oxygen scavenging substrates. Either 2,5-dimethylfuran or an amino acid (histidine or tryptophan methyl ester) was used as the substrate in conjunction with an iridium or ruthenium TMC in toluene, acetonitrile, or water. This behavior is described for solutions with chromophore concentrations that are pertinent for both luminescence and transient absorption spectroscopies. These results consistently produce TMC lifetimes comparable to those measured using traditional inert gas sparging and freeze-pump-thaw techniques. This method has the added benefits of providing long-term stability (days to months); economical preparation due to use of inexpensive, commercially available oxygen scrubbing substrates; and negligible size and weight footprints compared to traditional methods. Furthermore, attainment of dissolved [O2] < 50 µM makes this method relevant to any solution application requiring low dissolved oxygen concentration in solution, provided that the oxygenated substrate does not interfere with the intended chemical process.

Nonlinear optical characterization of multinuclear iridium compounds containing tricycloquinazoline.

Nonlinear optical properties were characterized for a series of multinuclear iridium compounds of the form TCQ[IrIII(ppz)2]n, where n=1, 2, or 3, TCQ is tricycloquinazoline, and ppz is 1-phenylpyrazole. Transient absorption (TA) spectroscopy indicated that the triplet metal-to-ligand charge transfer excited state was formed on a subpicosecond time scale and decayed back to the ground state on a microsecond time scale, consistent with precedents in the literature. TA bands were observed for all three compounds from 475 to 900 nm, implying the potential for reverse-saturable absorption (RSA) at those wavelengths. Z-scan measurements using picosecond and nanosecond pulses were obtained at 532 nm and confirmed the presence of RSA behavior for all three compounds. The triplet excited state cross sections and the RSA figure of merit were found to decrease with increasing n:1>2∼3.

Melatonin and its receptor MT1 are involved in the downstream reaction to luteinizing hormone and participate in the regulation of luteinization in different species.

The functions of melatonin in preovulatory fluid remain elusive. In the current study, we observed that the extremely high level of expression of MT1 in mice granulosa cells was rapidly induced by hCG (equivalent LH) within 2 hours and this was referred as MT1 surge. In cumulus cells, serotonin N-acetyltransferase (SNAT) was also upregulated by hCG and led to elevated melatonin levels in ovarian follicle fluid. Melatonin application before MT1 surge significantly promoted embryo implantation, and this was probably attributed to a rise in progesterone levels in the serum. The mechanistic studies indicated that melatonin/MT1 (MLT/MT1) signaling remarkably improved the expression of corpus luteum marker genes, that is, Akr1c18 and Cyp11a1. High-throughput sequencing results suggested that extracellular matrix (ECM) receptor interaction, focal adhesion, and activation of PI3K/Akt pathway which are involved in granulosa cell luteinization might mediate the actions of MLT/MT1 signal. In addition, this effect on luteinization was compared in different species. It was verified that high melatonin levels exist in serum at estrum of cows and help to improve the first estrus fecundation rate. These results suggested that both melatonin and MT1 are involved in the downstream reaction of hCG (LH) and they play important roles in luteinization. These findings provide the novel information on the physiology of melatonin in animal reproduction.

Effects of seasonal changes on the ovulation rate and embryo quality in superovulated Black Suffolk ewes.

OBJECTIVE: The objective of this study was to investigate the effects of seasonal changes on the superovulation in Black Suffolk ewes, particularly the ovulation rate and embryo quality. DESIGN: Black Suffolk ewes were superovulated either in May (n=22) or in September (n=21), 2013. After estrus synchronization with CIDR, the donor ewes were superovulated with PMSG and seven decreasing doses of FSH (twice daily at 07:00 and 19:00 for four consecutive days. Then, they were subjected to laparoscopic intrauterine artificial insemination. The viable morula and blastocysts were recovered and immediately transferred to recipients. RESULTS: Ewes that were superovulated in May had a much higher ovulation rate than those were superovulated in September (16.8 ± 3.23vs. 10.2 ± 2.94, p<0.01); however, the viability rate of the embryo was lower than that of September (56.0 ± 1.92% vs. 92.5 ± 3.26%, p<0.01). There was no significant difference in the survival rate of the transferred viable embryos (33.9 ± 1.00% vs. 36.7 ± 1.64%, p>0.05) and the number of offspring per donor ewe (3.1 ± 0.54 vs. 2.9 ± 0.72, p>0.05) between May and September. In contrast, the offspring/ova ratio of the donor ewes superovulated in May was lower than that of September (18.5 ± 1.64% vs. 32.8 ± 2.14%, p<0.01). CONCLUSIONS: The superovulation of Black Suffolk ewes may be affected by the seasonal changes. Generallly, The ewe's ovulation rate was higher in May, whereas the viability rate of embryo was higher in September.

Application of the strip clear-cutting system in a running bamboo (Phyllostachys glauca McClure) forest: feasibility and sustainability assessments.

Introduction: As a renewable forest resource, bamboo plays a role in sustainable forest development. However, traditional cutting systems, selection cutting (SeC) and clear-cutting (ClC), result in an unsustainable production of bamboo forests due to labor-consuming or bamboo degradation. Recently, a strip clear-cutting (StC) was theoretically proposed to promote the sustainability of bamboo production, while little is known about its application consequence. Methods: Based on a 6-year experiment, we applied the strip clear-cutting system in a typical running bamboo (Phyllostachys glauca McClure) forest to assess its feasibility and sustainability. Using SeC and ClC as controls, we set three treatments with different strip widths (5 m, 10 m, and 20 m) for strip clear-cutting, simplified as StC-5, StC-10, and StC-20, respectively. Then, we investigated leaf physiological traits, bamboo size and productivity, population features, and economic benefits for all treatments. Results: The stands managed by StC had high eco-physiological activities, such as net photosynthetic rate (P n), photosynthetic nitrogen use efficiency (PNUE), and photosynthetic phosphorus use efficiency (PPUE), and thus grew well, achieved a large diameter at breast height (DBH), and were tall. The stand biomass of StC (8.78 t hm-2 year-1) was 1.19-fold and 1.49-fold greater than that of SeC and ClC, respectively, and StC-10 and StC-20 were significantly higher than SeC or ClC (p< 0.05). The income and profit increased with the increase in stand density and biomass, and StC-20 and StC-10 were significantly higher than SeC or ClC (p< 0.05). Using principal components analysis and subordinate function analysis, we constructed a composite index to indicate the sustainability of bamboo forests. For the sustainability assessment, StC-10 had the highest productive sustainability (0.59 ± 0.06) and the second highest economic sustainability (0.59 ± 0.11) in all cutting treatments. StC-10 had the maximum overall sustainability, with a value of 0.53 ± 0.02, which was significantly higher than that of ClC (p< 0.05). Conclusion: The results verified that StC for Phyllostachys glauca forests is feasible and sustainable as its sustainability index outweighs those of traditional cutting systems (SeC and ClC), and 10 m is the optimum distance for the strip width of StC. Our findings provide a new cutting system for managing other running bamboo forests sustainably.

Cell mechanical responses to subcellular perturbations generated by ultrasound and targeted microbubbles.

The inherently dynamic and anisotropic microenvironment of cells imposes not only global and slow physical stimulations on cells but also acute and local perturbations. However, cell mechanical responses to transient subcellular physical signals remain unclear. In this study, acoustically activated targeted microbubbles were used to exert mechanical perturbations to single cells. The cellular contractile force was sensed by elastic micropillar arrays, while the pillar deformations were imaged using brightfield high-speed video microscopy at a frame rate of 1k frames per second for the first 10s and then confocal fluorescence microscopy. Cell mechanical responses are accompanied by cell membrane integrity changes. Both processes are determined by the perturbation strength generated by microbubble volumetric oscillations. The instantaneous cellular traction force relaxation exhibits two distinct patterns, correlated with two cell fates (survival or permanent damage). The mathematical modeling unveils that force-induced actomyosin disassembly leads to gradual traction force relaxation in the first few seconds. The perturbation may also influence the far end subcellular regions from the microbubbles and may propagate into connected cells with attenuations and delays. This study carefully characterizes the cell mechanical responses to local perturbations induced by ultrasound and microbubbles, advancing our understanding of the fundamentals of cell mechano-sensing, -responsiveness, and -transduction. STATEMENT OF SIGNIFICANCE: Subcellular physical perturbations commonly exist but haven't been fully explored yet. The subcellular perturbation generated by ultrasound and targeted microbubbles covers a wide range of strength, from mild, intermediate to intense, providing a broad biomedical relevance. With µm2 spatial sensing ability and up to 1ms temporal resolution, we present spatiotemporal details of the instantaneous cellular contractile force changes followed by attenuated and delayed global responses. The correlation between the cell mechanical responses and cell fates highlights the important role of the instantaneous mechanical responses in the entire cellular reactive processes. Supported by mathematical modeling, our work provides new insights into the dynamics and mechanisms of cell mechanics.

Oxidation kinetics of nitrogen doped TiO(2-δ) thin films.

The oxidation kinetics of nitrogen doped, oxygen deficient titanium dioxide thin films has been studied in atmospheres of pure oxygen or nitrogen at 500 °C, 550 °C, and 600 °C, respectively, by means of in situ optical spectroscopy. The thin films show high electronic absorbance in the visible and NIR region, accompanied by a red shift of the absorption edge of about 0.4 eV, e.g., from about 2.9 to 2.5 eV at 600 °C. The time dependent decrease of absorbance due to oxidation is found to follow a parabolic rate law. An activation energy of about 1.96 eV can be obtained from the temperature dependence of the parabolic oxidation rate constant. In the framework of a microscopic oxidation model, this energy barrier is attributed to the diffusion of titanium interstitials in the re-oxidized part of the thin films as a rate-determining process. In addition, an attempt is made to evaluate the kinetics of nitrogen release from the time dependent blue shift of the absorption edge during re-oxidation.

Faster calcium recovery and membrane resealing in repeated sonoporation for delivery improvement.

In sonoporation-based macromolecular delivery, repetitive microbubble cavitation in the bloodstream results in repeated sonoporation of cells or sonoporation of non-sonoporated neighboring cells (i.e., adjacent to the sonoporated host cells). The resealing and recovery capabilities of these two types of sonoporated cells affect the efficiency and biosafety of sonoporation-based delivery. Therefore, an improved understanding of the preservation of viability in these sonoporated cells is necessary. Using a customized platform for single-pulse ultrasound exposure (pulse length 13.33 µs, peak negative pressure 0.40 MPa, frequency 1.5 MHz) and real-time recording of membrane perforation and intracellular calcium fluctuations (using propidium iodide and Fluo-4 fluorescent probes, respectively), spatiotemporally controlled sonoporation was performed to administer first and second single-site sonoporations of a single cell or single-site sonoporation of a neighboring cell. Two distinct intracellular calcium changes, reversible and irreversible calcium fluctuations, were identified in cells undergoing repeat reversible sonoporation and in neighboring cells undergoing reversible sonoporation. In addition to an increased proportion of reversible calcium fluctuations that occurred with repeated sonoporation compared with that in the initial sonoporation, repeated sonoporation resulted in significantly shorter calcium fluctuation durations and faster membrane resealing than that produced by initial sonoporation. Similarly, compared with those in sonoporated host cells, the intracellular calcium fluctuation recovery and membrane perforation resealing times were significantly shorter in sonoporated neighboring cells. These results demonstrated that the function recovery and membrane resealing capabilities after a second sonoporation or sonoporation of neighboring cells were potentiated in the short term. This could aid in sustaining the long-term viability of sonoporated cells, therefore improving delivery efficiency and biosafety. This investigation provides new insight into the resealing and recovery capabilities in re-sonoporation of sonoporated cells and sonoporation of neighboring cells and can help develop safe and efficient strategies for sonoporation-based drug delivery.

Spatiotemporal Dynamics and Mechanisms of Actin Cytoskeletal Re-modeling in Cells Perforated by Ultrasound-Driven Microbubbles.

To develop new strategies for improving the efficacy and biosafety of sonoporation-based macromolecule delivery, it is essential to understand the mechanisms underlying plasma membrane re-sealing and function recovery of the cells perforated by ultrasound-driven microbubbles. However, we lack a clear understanding of the spatiotemporal dynamics of the disrupted actin cytoskeleton and its role in the re-sealing of sonoporated cells. Here we used a customized experimental setup for single-pulse ultrasound (133.33-µs duration and 0.70-MPa peak negative pressure) exposure to microbubbles and for real-time recording of single-cell (human umbilical vein endothelial cell) responses by laser confocal microscopic imaging. We found that in reversibly sonoporated cells, the locally disrupted actin cytoskeleton, which was spatially correlated with the perforated plasma membrane, underwent three successive phases (expansion; contraction and re-sealing; and recovery) to re-model and that each phase of the disrupted actin cytoskeleton was approximately synchronized with that of the perforated plasma membrane. Moreover, compared with the closing time of the perforated plasma membrane, the same time was used for the re-sealing of the actin cytoskeleton in mildly sonoporated cells and a longer time was required in moderately sonoporated cells. Further, the generation, directional migration, accumulation and re-polymerization of globular actin polymers during the three phases drove the re-modeling of the actin cytoskeleton. However, in irreversibly sonoporated cells, the actin cytoskeleton, which underwent expansion and no contraction, was progressively de-polymerized and could not be re-sealed. Finally, we found that intracellular calcium transients were essential for the recruitment of globular actin and the re-modeling of the actin cytoskeleton. These results provide new insight into the role of actin cytoskeleton dynamics in the re-sealing of sonoporated cells and serve to guide the design of new strategies for sonoporation-based delivery.

Defect chemistry, redox kinetics, and chemical diffusion of lithium deficient lithium niobate.

High-temperature optical in situ spectroscopy was used to investigate the defect absorption, redox kinetics, and chemical diffusion of a lithium deficient (48.4 mol% Li(2)O) congruent melting lithium niobate single crystal (c-LN). Under reducing atmospheres of various oxygen activities, a(O(2)), UV-Vis-NIR spectra measured at 1000 °C are dominated by an absorption band due to free small polarons centered at about 0.93 eV. The polaron band intensity was found to follow a power law of the form a(O(2))(m) with m = -1/4. A chemical reduction model involving electrons localized on niobium ions on regular lattice sites can explain the observed defect absorption and its dependence on oxygen activity. The kinetics of reduction and oxidation processes upon oxygen activity jumps and the associated chemical diffusion coefficients are found in close agreement over a range from -0.70 to -14.70 in log a(O(2)), indicating a reversible redox process. Assuming coupled fluxes of lithium vacancies and free small polarons for the attainment of stoichiometry, the diffusion coefficients of lithium vacancies as well as of lithium ions in the lithium deficient c-LN have been determined at 1000 °C.

Electrochemical Behavior and Interfacial Delamination of a Polymer-Coated Galvanized Steel System in Acid Media.

The degradation behavior of polymer coatings is essential for their protective performance under various corrosive environments. Herein, electrochemical impedance spectroscopy (EIS) is employed to study the corrosion behavior and interfacial delamination of a polymer-coated metal system exposed to 0.1, 0.5, and 1 mol/L H2SO4 solutions at 50 °C. The electrochemical impedance spectra are analyzed using different equivalent circuits to derive the time dependence of the parameters of the coating, delaminated area, and interfacial processes. The phase angle at 10 Hz (θ10 Hz) is not appropriate in the case of higher delamination area ratio α, while θ10 kHz provides a rapid approach to evaluate the degradation of polymer-coated metal systems. The frequency of the phase angle at -45° (f -45°) leads to a wrong evaluation for higher α and can be no longer viewed as the breakpoint frequency. The frequency f p obtained by the changing rate of phase angle (CRPA) method is proposed to monitor the coating degradation and determine the breakpoint frequency with the consideration of dispersive number n. The frequency f EIS derived from fitting EIS spectra shows a good agreement with f p, which can contribute to clarify the evolution in the process of degradation.

Plasma Membrane Blebbing Dynamics Involved in the Reversibly Perforated Cell by Ultrasound-Driven Microbubbles.

The perforation of plasma membrane by ultrasound-driven microbubbles (i.e., sonoporation) provides a temporary window for transporting macromolecules into the cytoplasm that is promising with respect to drug delivery and gene therapy. To improve the efficacy of delivery while ensuring biosafety, membrane resealing and cell recovery are required to help sonoporated cells defy membrane injury and regain their normal function. Blebs are found to accompany the recovery of sonoporated cells. However, the spatiotemporal characteristics of blebs and the underlying mechanisms remain unclear. With a customized platform for ultrasound exposure and 2-D/3-D live single-cell imaging, localized membrane perforation was induced with ultrasound-driven microbubbles, and the cellular responses were monitored using multiple fluorescent probes. The results indicated that localized blebs undergoing four phases (nucleation, expansion, pausing and retraction) on a time scale of tens of seconds to minutes were specifically involved in the reversibly sonoporated cells. The blebs spatially correlated with the membrane perforation site and temporally lagged (about tens of seconds to minutes) the resealing of perforated membrane. Their diameter (about several microns) and lifetime (about tens of seconds to minutes) positively correlated with the degree of sonoporation. Further studies revealed that intracellular calcium transients might be an upstream signal for triggering blebbing nucleation; exocytotic lysosomes not only contributed to resealing of the perforated membrane, but also to the increasing bleb volume during expansion; and actin components accumulation facilitated bleb retraction. These results provide new insight into the short-term strategies that the sonoporated cell employs to recover on membrane perforation and to remodel membrane structure and a biophysical foundation for sonoporation-based therapy.