Search

Purpose: Autoimmune Thyroiditis (AIT) is the most common thyroid disease; however, there were no measures to prevent the progression of the disease. The present study attempts to identify that Notch signaling regulates the differentiation of T helper 17 (Th17) cells by activating downstream Phosphatidylinositol-3 kinase/protein kinase/mechanistic target of rapamycin complex 1 (PI3K/AKT/mTORC1) pathway participating in the thyroid injury of the experimental autoimmune thyroiditis (EAT). Methods: In vivo experiments, mice were randomly divided into 4 groups: a control group, an EAT group, and two groups with LY294002 treatment (pTg plus 25 mg/kg or 50 mg/kg LY294002, respectively). The degrees of thyroiditis were evaluated, and the percentage of Th17 cells, expression of interleukin-17A (IL-17A), and the main components of the Notch–PI3K signaling pathway were detected in different groups. In vitro experiments, two different dosages of LY294002 (25 and 50 μM) were used to intervene splenic mononuclear cells (SMCs) from EAT mice to further evaluate the regulatory effect of Notch–PI3K pathway on Th17 cells. Results: Our data demonstrate that the infiltration of Th17 cells and the expressions of IL-17A, Notch, hairy and split 1 (Hes1), p‑AKT (Ser473), p‑AKT (Thr308), p‑mTOR (Ser2448), S6K1, and S6K2 increased remarkably in EAT mice. After PI3K pathway was blocked, the degrees of thyroiditis were significantly alleviated, and the proportion of Th17 cells, the expression of IL-17A, and the above Notch–PI3K pathway-related molecules decreased in a dose-dependent manner. Additionally, the proportion of Th17 cells was positively correlated with the concentration of serum thyroglobulin antibody (TgAb), IL-17A, and Notch–PI3K pathway-related molecules mRNA levels. Conclusions: Notch signal promotes the secretion of IL-17A from Th17 cells by regulating the downstream PI3K/AKT/mTORC1 pathway through Hes-Phosphatase and tensin homolog (PTEN) and participates in thyroid autoimmune damage, and the PI3K pathway inhibitor may play important effects on AIT by affecting Th17 cells differentiation. more...

Electromagnetic ion cyclotron waves in the Earth's outer radiation belt drive rapid electron losses through wave‐particle interactions. The precipitating electron flux can be high in the hundreds of keV energy range, well below the typical minimum resonance energy. One of the proposed explanations relies on nonresonant scattering, which causes pitch‐angle diffusion away from the fundamental cyclotron resonance. Here we propose the fractional sub‐cyclotron resonance, a second‐order nonlinear effect that scatters particles at resonance order n= 1/2, as an alternate explanation. Using test‐particle simulations, we evaluate the precipitation ratios of sub‐MeV electrons for wave packets with various shapes, amplitudes, and wave normal angles. We show that the nonlinear sub‐cyclotron scattering produces larger ratios than the nonresonant scattering when the wave amplitude reaches sufficiently large values. The ELFIN CubeSats detected several events with precipitation ratio patterns matching our simulation, demonstrating the importance of sub‐cyclotron resonances during intense precipitation events. High‐energy electrons in the Earth's radiation belt are constantly being scattered by the ubiquitous electromagnetic plasma waves. A portion of these scattered electrons is lost to the atmosphere, where the particles deposit their energy and cause a chain of chemical reactions, possibly contributing to ozone destruction. The energy and flux of the precipitating electrons depend on the nature of the wave‐particle interactions in the radiation belt. The electromagnetic ion cyclotron wave (EMIC), known to be responsible for scattering relativistic electrons, has been observed to cause precipitation at energies much lower than expected by the standard theory. We numerically investigate two types of interactions, the nonresonant scattering and the nonlinear sub‐cyclotron scattering, and show how both influence the relative precipitating fluxes. We demonstrate that sub‐cyclotron interactions driven by intense EMIC waves can cause stronger precipitation than nonresonant scattering at sub‐MeV energies. The dual ELFIN CubeSats detected precipitation profiles that match our numerical results, confirming the importance of nonlinear sub‐cyclotron scattering in the analysis of intense precipitation events. Electrons resonate with intense quasiparallel electromagnetic ion cyclotron wave waves at fractions of the minimum resonance energyFractional resonant scattering causes significant precipitation when the wave amplitude reaches above 1% of the ambient fieldPrecipitating electron flux spectrum observed by the ELFIN CubeSats supports the estimated influence of fractional resonances Electrons resonate with intense quasiparallel electromagnetic ion cyclotron wave waves at fractions of the minimum resonance energy Fractional resonant scattering causes significant precipitation when the wave amplitude reaches above 1% of the ambient field Precipitating electron flux spectrum observed by the ELFIN CubeSats supports the estimated influence of fractional resonances more...

We report unusual Electromagnetic Ion Cyclotron (EMIC) waves with a very narrow frequency bandwidth, closely following and approaching the proton gyrofrequency. One interesting case analysis shows that magnetosonic waves, anisotropic suprathermal proton distributions, and high frequency EMIC waves are closely related. Magnetosonic waves potentially cause the resonant heating of suprathermal protons and the temperature anisotropy of suprathermal protons (10–100 eV) likely provides free energy for the excitation of high frequency EMIC waves. The statistical analysis shows that this type of EMIC waves has a typical wave amplitude of ~100 pT, left‐handed polarization, and small wave normal angles. Moreover, these low frequency EMIC waves typically occur near the equator in the low‐density regions from dawn to dusk. These newly observed high frequency EMIC waves provide new insights into understanding the generation of EMIC waves and the energy transfer between magnetosonic waves and EMIC waves. Electromagnetic Ion Cyclotron (EMIC) waves are commonly observed in the Earth's magnetosphere and play an important role in causing the loss of ring current ions and relativistic electrons due to pitch angle scattering. In this study, we report unusual high frequency EMIC waves with frequency very close to the proton gyrofrequency. An interesting case study clearly shows the correlation between magnetosonic waves, the enhancement of suprathermal protons, and high frequency EMIC waves. The protons at suprathermal energies could be heated by magnetosonic waves and the anisotropic distribution of suprathermal protons is likely responsible for the excitation of high frequency EMIC waves. The statistical analysis shows that this type of EMIC waves has a typical wave amplitude of ~100 pT, left‐handed polarization, and small wave normal angles. These newly observed high frequency EMIC waves provide new insights into understanding the generation of EMIC waves and the energy transfer between magnetosonic waves and EMIC waves. Unusually high frequency EMIC waves are observed near the proton gyrofrequency with a very narrow bandwidthTemperature anisotropy of suprathermal protons in association with magnetosonic waves likely excites high frequency EMIC wavesStatistical results show that high frequency EMIC waves typically occur near the equator in the low‐density regions from dawn to dusk more...

Elastic electron–proton scattering (e–p) and the spectroscopy of hydrogen atoms are the two methods traditionally used to determine the proton charge radius, rp. In 2010, a new method using muonic hydrogen atoms1found a substantial discrepancy compared with previous results2, which became known as the ‘proton radius puzzle’. Despite experimental and theoretical efforts, the puzzle remains unresolved. In fact, there is a discrepancy between the two most recent spectroscopic measurements conducted on ordinary hydrogen3,4. Here we report on the proton charge radius experiment at Jefferson Laboratory (PRad), a high-precision e–p experiment that was established after the discrepancy was identified. We used a magnetic-spectrometer-free method along with a windowless hydrogen gas target, which overcame several limitations of previous e–p experiments and enabled measurements at very small forward-scattering angles. Our result, rp= 0.831 ± 0.007stat± 0.012systfemtometres, is smaller than the most recent high-precision e–p measurement5and 2.7 standard deviations smaller than the average of all e–p experimental results6. The smaller rpwe have now measured supports the value found by two previous muonic hydrogen experiments1,7. In addition, our finding agrees with the revised value (announced in 2019) for the Rydberg constant8—one of the most accurately evaluated fundamental constants in physics. more...

Extracellular matrix protein 1 (ECM1) is related to strong invasiveness and poor prognosis in major malignancies, but the underlying mechanism remains unknown. Here we aimed to elucidate the function of ECM1 on cell metastasis and glucose metabolism in gastric cancer (GC). The level of ECM1 in sera and tissues of patient with GC were positively correlated with tumor invasion and recurrence. Genetic manipulation of ECM1 expression affected cell metastasis and glucose metabolism in GC cell lines. Enhanced ECM1 expression facilitated gene expression levels associated with epithelial–mesenchymal transition (EMT) and glucose metabolism. Interestingly, our results indicated that ECM1 directly interacted with integrin β4 (ITGB4) and activated ITGB4/focal adhesion kinase (FAK)/glycogen synthase kinase 3β signaling pathway, which further induced the expression of transcription factor SOX2. Aberrant expression of SOX2 altered gene expression of EMT factors and glucose metabolism enzymes. Furthermore, SOX2 enhanced hypoxia-inducible factor α (HIF-1α) promoter activity to regulate glucose metabolism. The micro-positron emission tomography/computed tomography imaging of xenograft model showed that ECM1 substantially increased 18F-fluorodeoxyglucose uptake in xenograft tumors. Using in vivo mouse tail vein injection experiments, ECM1 was also found to increase in lung surface metastasis. These findings provide evidence that ECM1 regulates GC cell metastasis and glucose metabolism by inducing ITGB4/FAK/SOX2/HIF-1α signal pathway and have important implications for the development of therapeutic target to prevent tumor metastasis and recurrence. more...

Aims:The objective of this study is to characterize the relationship between forkhead box C2 protein (Foxc2) and leptin under adipose inflammatory response.Methods:Lipopolysaccharide (LPS)-induced inflammatory model was conducted. Data from wild-type and ob/ob mice were used to compare the alternative role of leptin on Foxc2-mediated inflammation and browning. Transcriptional regulation and protein-protein interaction were analyzed by bioinformatics and proved by chromatin immunoprecipitation and co-immunoprecipitation experiment.Results:Foxc2 and leptin correlated with inflammation and browning of white adipose tissue (WAT) in LPS-treated mice. Moreover, Foxc2-mediated inhibition of inflammation involved downstream activation of leptin signal and promoted WAT browning. We then determined CREB, the potential transcriptional factor of leptin, was required for Foxc2-mediated inflammation in the regulation of WAT browning. Foxc2 alleviated adipocyte inflammation by reducing leptin-mediated Janus-activated kinase 2/signal transducer and activator of transcription 3 (STAT3) pathway. Importantly, STAT3 physically interacted with PRDM16 and formed a complex to promote WAT browning. Exogenous Foxc2 overexpression also ameliorated inflammation and promoted adipose browning in high fat diet (HFD)-induced obese mice.Conclusions:Our results indicated that Foxc2 inhibited inflammation and promoted browning of WAT through positive regulation of leptin signal and the STAT3-PRDM16 complex. These findings identify a new potential means to prevent and treat obese caused metabolic syndrome of mammals. more...

Core IdeasPaddy soil shrinkage behaviors and cracking patterns were significantly influenced by wetting and drying cycles.Wetting and drying (WD) intensity had a greater impact on soil shrinkage than WD frequency and sequence.The crack area can be better predicted by shrinkage curve when considering wetting and drying cycles.The geometry factor is linked to soil shrinkage and cracking.Linking soil shrinkage and cracking Soil cracks develop in paddy soils during wetting and drying (WD) cycles. Although changes in soil structure related to cracking have often been described as soil shrinkage, the relationship between soil shrinkage and cracking remains unclear. The objectives of this study were to investigate how WD cycles affect soil shrinkage and cracking and to establish a link between soil shrinkage in the laboratory and cracking in the field. Two paddy fields (one young paddy field and one old paddy field) were subjected to multiple WD cycles during rice growth. Soil cracks were photographed in the field, and the area density (Dc), compactness of cracks (CP), and equivalent width (EW) of the cracks were analyzed. The shrinkage curves of soil cores that were sampled in the two paddy fields were determined after they were subjected to various laboratory‐based simulated WD cycles (including variations in intensity, frequency, and sequence). To estimate soil cracking, three parameterizations based on the shrinkage curves of the soil cores treated with non‐predrying (Parameterization A), slight drying (Parameterization B), and intense drying (Parameterization C) were established. The YPF soil presented greater Dcand CP than the OPF soil (P < 0.05), whereas the OPF soil exhibited greater EW and coefficient of linear extensibility (P < 0.05). Area density was not only affected by the current soil water content or by the previous drying history. As the number of WD cycles increased, equivalent width generally increased, whereas CP decreased. The intensity of the WD cycles affected shrinkage more than the frequency or sequence. The fitted geometry factor, rs, decreased from Parameterization A to Parameterization C for both soils. The Dcvalues were more accurately estimated by using soil shrinkage curves that included the intensity of the WD cycles. Our results demonstrate that the soil shrinkage curve associated with rscan better predict cracking when the effects of WD cycles are considered. more...

Deregulation of the MYConcogene produces Myc protein that regulates multiple aspects of cancer cell metabolism, contributing to the acquisition of building blocks essential for cancer cell growth and proliferation. Therefore, disabling Myc function represents an attractive therapeutic option for cancer treatment. However, pharmacological strategies capable of directly targeting Myc remain elusive. Here, we identified that 3-bromopyruvate (3-BrPA), a drug candidate that primarily inhibits glycolysis, preferentially induced massive cell death in human cancer cells overexpressing the MYConcogene, in vitroand in vivo, without appreciable effects on those exhibiting low MYClevels. Importantly, pharmacological inhibition of glutamine metabolism synergistically potentiated the synthetic lethal targeting of MYCby 3-BrPA due in part to the metabolic disturbance caused by this combination. Mechanistically, we identified that the proton-coupled monocarboxylate transporter 1 (MCT1) and MCT2, which enable efficient 3-BrPA uptake by cancer cells, were selectively activated by Myc. Two regulatory mechanisms were involved: first, Myc directly activated MCT1and MCT2transcription by binding to specific recognition sites of both genes; second, Myc transcriptionally repressed miR29a and miR29c, resulting in enhanced expression of their target protein MCT1. Of note, expressions of MCT1and MCT2were each significantly elevated in MYCN-amplified neuroblastomas and C-MYC-overexpressing lymphomas than in tumors without MYCoverexpression, correlating with poor prognosis and unfavorable patient survival. These results identify a novel mechanism by which Myc sensitizes cells to metabolic inhibitors and validate 3-BrPA as potential Myc-selective cancer therapeutics. more...

ISLET1 is a homeodomain transcription factor necessary for development of the pituitary, retina, motor neurons, heart, and pancreas. Isl1-deficient mice (Isl1−/−) die early during embryogenesis at embryonic day 10.5 due to heart defects, and at that time, they have an undersized pituitary primordium. ISL1 is expressed in differentiating pituitary cells in early embryogenesis. Here, we report the cell-specific expression of ISL1 and assessment of its role in gonadotropes and thyrotropes. Isl1expression is elevated in pituitaries of Cga−/−mice, a model of hypothyroidism with thyrotrope hypertrophy and hyperplasia. Thyrotrope-specific disruption of Isl1with Tshb-creis permissive for normal serum TSH, but T4levels are decreased, suggesting decreased thyrotrope function. Inducing hypothyroidism in normal mice causes a reduction in T4levels and dramatically elevated TSH response, but mice with thyrotrope-specific disruption of Isl1have a blunted TSH response. In contrast, deletion of Isl1in gonadotropes with an Lhb-cretransgene has no obvious effect on gonadotrope function or fertility. These results show that ISL1 is necessary for maximal thyrotrope response to hypothyroidism, in addition to its role in development of Rathke's pouch. more...

Background:Tumor treatment fields (TTFields) are an approved adjuvant therapy for glioblastoma. The magnitude of applied electrical field is related to the anti-tumoral response. However, peritumoral edema (ptE) may result in shunting of electrical current around the tumor, thereby reducing the intra-tumoral electric field. In this study, we address this issue with computational simulations. Methods:Finite element models were created with varying amounts of ptE surrounding a virtual tumor. The electric field distribution was simulated using the standard TTFields electrode montage. Electric field magnitude was extracted from the tumor and related to edema thickness. Two patient specific models were created to confirm these results. Results:The inclusion of ptE decreased the magnitude of the electric field within the tumor. In the model considering a frontal tumor and an anterior-posterior electrode configuration, ≥ 6 mm of ptE decreased the electric field by 52%. In the patient specific models, ptE decreased the electric field within the tumor by an average of 26%. The effect of ptE on the electric field distribution was spatially heterogenous. Conclusions:Given the importance of electric field magnitude for the anti-tumoral effects of TTFields, the presence of edema should be considered both in future modelling studies and as a predictor of non-response. more...

The Brillouin shift and width for poly(acrylic acid) hydrogels have been obtained as a function of gel network volume fraction using a five-pass Fabry-Pérot interferometer. A conspicuous peak has been observed in the Brillouin shift at high volume fraction. The results are discussed in the light of a theory for the Brillouin light-scattering from gels proposed by Marqusee and Deutch. more...

Transparent bicontinuous nanostructured polymeric materials have been synthesized via the polymerization of bicontinuous microemulsions of appropriate formulations. The use of polymerizable zwitterionic betaine surfactant of (acryloyloxy)undecyldimethylammonio acetate (AUDMAA) and cationic surfactant (acryloyloxy)undecyltrimethylammonium bromide (AUTMAB) is the key factor to the success of the stable polymerization. The nanostructures (pores) of polymeric materials were characterized by SEM, thermoporometry, and membrane-filtration of poly(ethylene glycol) having different molecular weights. The pore size or the width of the polymerized bicontinuous microemulsions (transparent solid polymers) increased substantially from about 20 to 100 nm with the increase of the water content (20−60 wt %) or NaCl concentration (0−2 wt %) in precursor microemulsions. In contrast, the incorporation of 12 wt % HEMA in the precursor microemulsion reduced the pore size drastically to about 2 nm. This total polymerization (except water) approach enables one to synthesize various bicontinuous nanostructures (2−150 nm) of transparent polymeric materials by simply adjusting the concentrations of water, HEMA, polymerizable surfactant, and electrolyte in precursor bicontinuous microemulsions. more...

A variety of esters from the reactions of monoalcohols with palm olein were prepared, epoxidized byin situperoxyacid techniques, and some of their physical properties were compared. The thermal oxidative stabilities of these esters andbis(2-ethylhexyl) phthalate were studied. The esters were placed in an oven maintained at 120°C, and the loss of mass and acid, iodine, percent oxirane, hydroxyl, and peroxide values were monitored periodically. The epoxidized esters had higher densities and lower volatilities, and were more resistant toward oxidation than their unepoxidized counterparts. The stability of the oxirane was related to the initial acid value of the sample. Higher initial acid value resulted in a greater decrease in the oxirane content, indicating acid-catalyzed cleavage of the oxirane ring. more...

The particle sizes and their size distributions of latexes from the dispersion polymerization of styrene using a small amount of ο-methoxy poly(ethylene oxide)n undecyl-α-methacrylate macromonomer (PEO-R-MA-40) as a polymerizable stabilizer in ethanol—water media have been studied. Monodisperse or/and nearly monodisperse latex particles from 0.1 to 1 μm in diameter were readily obtained. The diameter of latex particles follows the relationship Dvad ∝ θ^0.33 $[PEO-R-MA-40]^{-0.60}_{\rm o}$ $[styrene]^{1.02}_{\rm o}$ $[AIBN]^{-0.09}_{\rm o}$, where θ is the fractional conversion of styrene. Except for the styrene concentration dependency, this relationship is in excellent agreement with the model developed by Paine¹¹ and modified by Kawaguchi et al.¹³ When the surface composition of the grafted PEO macromonomer on the latex particles exceeded 16% as analyzed by X-ray photoelectron spectroscopy (XPS), the particles were nearly monodisperse. In terms of polymerization, this occurred around 18% conversion of styrene. Beyond this critical state of polymerization, the latex particles grew bigger with more PEO macromonomer-styrene copolymers situated on the particle surface. The effect of various factors on the particle size distribution is also discussed. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3575–3583, 1997 more...

The polymerization of styrene in ternary microemulsions stabilized by the cationic surfactant tetradecyltrimethylammonium bromide was studied as a function of concentrations of water-soluble (potassium persulfate, KPS) and oil-soluble (AIBN) initiators. At a particular molar ratio of the initiators, similar maximum rates of polymerization can be achieved from using both types of the initiators. In addition, both initiated systems produced microlatexes with similar hydrodynamic radius, number of polymer particles, molecular weight of polystyrene and number of polymer chain per latex particle. But the dependencies of these latex parameters on concentrations of KPS and AIBN may not be the same. The polymerization mechanism appears to be similar, irrespective of using KPS or AIBN. It is discussed in terms of “effective radicals” produced for the polymerization. While the different dependencies of some latex parameters on concentrations of the initiators are attributed to the different efficiencies of the initiators in producing “effective radicals”. more...

Abstract: A variety of esters from the reactions of monoalcohols with palm olein were prepared, epoxidized byin situ peroxyacid techniques, and some of their physical properties were compared. The thermal oxidative stabilities of these esters andbis(2-ethylhexyl) phthalate were studied. The esters were placed in an oven maintained at 120C, and the loss of mass and acid, iodine, percent oxirane, hydroxyl, and peroxide values were monitored periodically. The epoxidized esters had higher densities and lower volatilities, and were more resistant toward oxidation than their unepoxidized counterparts. The stability of the oxirane was related to the initial acid value of the sample. Higher initial acid value resulted in a greater decrease in the oxirane content, indicating acid-catalyzed cleavage of the oxirane ring. more...

Transparent nanostructured polymeric materials have been produced from the direct polymerization of bicontinuous microemulsions using the macromonomer ω-methoxy−poly(ethylene oxide)40−undecyl−α-methacrylate (C1−PEO−C11−MA-40) as a polymerizable nonionic surfactant. Besides the PEO macromonomer, the system also consisted of methyl methacrylate (MMA), 2-hydroxyethyl methacrylate (HEMA), water, and the cross-linker ethylene glycol dimethacrylate (EGDMA). Most of the bicontinuous microemulsions investigated could be gelled within 10 min at 30 °C using a redox initiator. The transparent microemulsions were eventually transformed to transparent solid polymers. These polymeric materials were characterized by thermoporometry, SEM observation, and the pore size evaluation for the polymer films by PEG filtration. The pore size of these transparent polymeric materials ranges from about 1 to 10 nm in diameter. It was larger for the systems containing higher ratios of water to HEMA or water to C1−PEO−C11−MA-40 and smaller for higher ratios of HEMA to C1−PEO−C11−MA-40. The results from PEG filtration provide the direct evidence that bicontinuous nanostructured polymeric materials can readily be prepared via the polymerization of these nonionic bicontinuous microemulsions. more...

Synthesis of monodisperse polystyrene microlatexes by emulsion polymerization using a polymerizable surfactant, ω-methoxypoly(ethylene oxide)40undecyl α-methacrylate macromonomer (PEO-R-MA-40), has been investigated. PEO-R-MA-40 copolymerized readily with styrene. The locus of the copolymerization is believed to occur near the surface of styrene-swollen micelles/particles where the polymerizable end groups (methacrylate) of PEO-R-MA-40 were concentrated due to its hydrophilicity. The latexes became stabilized when only about 6 wt % styrene and 10.5 wt % PEO-R-MA-40 were copolymerized. From the XPS results, it shows that only about 22% of the latex surface occupied by the copolymerized PEO-R-MA-40 was sufficient to stabilize the latex particles. Toward the completion of the copolymerization, about 80% of the latex surface was enriched by the copolymerized PEO-R-MA-40. Nearly monodisperse latex particles with diameters ranging from about 30 to 90 nm were obtained by lowering the feed weight-ratio of PEO-R-MA-40 to styrene from 1/2 to 1/8. But the particle size did not seem to be affected by the increase of KPS concentration from 0.5 to 3.0 mM at the feed ratio of 1/8. A polymerization scheme is presented to account for the results. more...

A novel method has been successfully used for the preparation of ultrafiltration (UF) membranes by direct polymerization of bicontinuous microemulsions. One of these microemulsions consisted of a polymerizable cationic surfactant of ((acryloyloxy)undecyl)trimethylammonium bromide (AUTMAB), methyl methacrylate (MMA), 2-hydroxyethyl methacrylate (HEMA), and water. The other was a zwitterionic microemulsion composed of a polymerizable surfactant of ((acryloyloxy)undecyl)dimethylammonio acetate (AUDMAA), MMA, HEMA, and water. In addition, a small amount of the cross-linker ethylene glycol dimethacrylate (EGDMA) was also included in each microemulsion polymerization for improving its UF membrane strength. The uniqueness of the microemulsion system is that all organic components can readily be copolymerized at room temperature using a redox initiator. The transparent membranes thus formed showed excellent strength and performance on the separation of different molecular weights of poly(ethylene glycol) (PEG). The pore sizes of the membranes were calculated to be within the range 1−5 nm in diameter, and they could be regulated by varying microemulsion compositions. more...

In this study, using Van Allen Probes observations we identify 81 events of electron flux bursts with butterfly pitch angle distributions for tens of keV electrons with close correlations with chorus wave bursts in the Earth's magnetosphere. We use the high‐rate electron flux data from Magnetic Electron Ion Spectrometer available during 2013–2019 and the simultaneous whistler‐mode wave measurements from Electric and Magnetic Field Instrument Suite and Integrated Science to identify the correlated events. The events are categorized into 67 upper‐band chorus (0.5–0.8 fce) dominated events and 14 other events where lower‐band chorus (0.05–0.5 fce) has modest or strong amplitudes (fcerepresents electron cyclotron frequency). Each electron flux burst correlated with chorus has a short timescale of ∼1 min or less, suggesting potential nonlinear effects. The statistical distribution of selected electron burst events tends to occur in the post‐midnight sector at L> 5 under disturbed geomagnetic conditions, and is associated with chorus waves with relatively strong magnetic wave amplitude and small wave normal angle. The frequency dependence of the electron flux peaks agrees with the cyclotron resonant condition, indicating the effects of chorus‐induced electron acceleration. Our study provides new insights into understanding the rapid nonlinear interactions between chorus and energetic electrons. Whistler‐mode chorus waves can efficiently cause electron pitch angle scattering and acceleration in the Earth's radiation belts. Electron butterfly distribution, which has two flux peaks at off‐90° pitch angles, could be caused by the electron acceleration at intermediate pitch angles. Nonlinear wave‐particle interaction is potentially important for electron acceleration during a short timescale to form bursty electron flux enhancements. Using Van Allen Probes observations, we evaluate the occurrence and characteristics of events with a strong correlation between chorus wave bursts and electron butterfly distributions. We use the electron flux measurements at 34 and 54 keV with high time and pitch angle resolutions to identify the events. Our multi‐event analysis shows that the electron flux bursts correlated with chorus tend to occur at high Lshells on the nightside under disturbed geomagnetic conditions. Most of the identified events are associated with chorus waves with strong magnetic wave amplitudes and small wave normal angles. The pitch angles of electron flux peaks agree with the interaction regime of chorus, suggesting the critical role of chorus in forming the butterfly shaped pitch angle distributions in the Earth's radiation belts. We identified multiple chorus bursts correlated with electron flux bursts peaking at intermediate pitch angles using Van Allen Probes dataElectron flux bursts at 34–54 keV correlated with chorus are observed over 21‐05 MLT and L∼4.5–6.5 with peak flux at 76° pitch angleThe pitch angles of electron flux peaks show frequency and Ldependences, suggesting the cyclotron resonant interaction effects by chorus We identified multiple chorus bursts correlated with electron flux bursts peaking at intermediate pitch angles using Van Allen Probes data Electron flux bursts at 34–54 keV correlated with chorus are observed over 21‐05 MLT and L∼4.5–6.5 with peak flux at 76° pitch angle The pitch angles of electron flux peaks show frequency and Ldependences, suggesting the cyclotron resonant interaction effects by chorus more...

A simple model was established to calculate and predict the effects of network modifiers on the viscosity of molten blast furnace slag by relating the effects to the ionic bond force parameter. It was found that the model performs very well in calculating the viscosity of blast furnace slags containing FeO, MnO, BaO, Na2O, K2O and CaF2, with relative error ? of 0·219 (±0·196) and overall absolute error (root mean square error) of 0·402 Pa s. The viscosity decreasing abilities are in the order of K2O<(Na2O, BaO)<(CaO, MnO, FeO) more...

The electron resonant interaction with whistler‐mode waves is characterized by transport in pitch angle–energy space. We calculate electron diffusion and advection coefficients (a simplified characterization of transport) for a large range of electron pitch angle and energy using test particle simulations. Nonlinear effects are analyzed by comparing the diffusion coefficients using test particle simulations and quasilinear theory, and by evaluating the advection rates. Dependence of nonlinear effects on the wave amplitude and bandwidth of whistler‐mode waves is evaluated by running test particle simulations with a broad range of wave amplitude and bandwidth. The maximum amplitudes where the quasilinear approach is valid are found to increase with increasing bandwidth, from 50 pT for narrowband waves to 300 pT for broadband waves at L‐shell of 6. Moreover, interactions between intense whistler‐mode waves and small pitch angle electrons lead to large positive advection, which limits the applicability of diffusion‐based models. This study demonstrates the parameter range of the applicability of quasilinear theory and diffusion model for different wave amplitudes and frequency bandwidths of whistler‐mode waves, which is critical for evaluating the effects of whistler‐mode waves on energetic electrons in the Earth’s magnetosphere. The maximum wave amplitude threshold for the applicability of quasilinear theory increases with increasing bandwidthElectron diffusion acceleration due to intense broadband whistler‐mode waves is limited by phase trapping trajectory along the field lineInteractions between intense whistler‐mode waves and small pitch angle electrons limit the applicability of diffusion models The maximum wave amplitude threshold for the applicability of quasilinear theory increases with increasing bandwidth Electron diffusion acceleration due to intense broadband whistler‐mode waves is limited by phase trapping trajectory along the field line Interactions between intense whistler‐mode waves and small pitch angle electrons limit the applicability of diffusion models more...

Nano-titania ceramics is a potential biomaterial for orthopaedic application. In our previous studies, a bioactive nano-titania ceramics was prepared by using alkali-heat treatment. In this paper, hydroxyapatite was used as a grain growth inhibitor additive to get nano-titania ceramics with different grain size, and the effect of grain size on the bioactivity was studied in vitro. more...

After the Tantalum metal was subjected to the anodic oxidation at suitable voltage in 2M H2SO4 solution, tantalum oxide with rhombic or amorphous structure formed on the metal surface. The Oxide showed apatite formation ability in simulative body fluid at 6d. It meant the anodic oxidation treatment ia an effective method to accelerate the bioactivity of tantalum metal. more...

Homopolymers of azobenzene methacrylates (azo) and their diblock copolymers with 2-(dimethylamino)ethyl metharylate (DMAEMA) were synthesized via atom transfer radical polymerization (ATRP). Polymers of cyano- and butoxy-substituted azobenzenes exhibited liquid crystalline textures. Water-soluble diblock copolymers could be obtained with a long DMAEMA block and a short azo block. These diblock copolymers self-assembled into polymeric micelles with core−shell structure in aqueous solutions. The rates of trans−cis photoisomerization were almost the same for the DMAEMA copolymers of 6-[4-phenylazo]phenoxy]hexyl methacrylate (PPHM), p(DMAEMA172-b-PPHM9), and 6-[4-(4-cyanophenylazo)phenoxy]hexyl methacrylate (CPHM), p(DMAEMA172-b-CPHM7), whereas slightly slower rates were observed for the copolymer of 6-[4-(4-butoxyphenylazo)phenoxy]hexyl methacrylate (BPHM), p(DMAEMA172-b-BPHM7), most likely due to steric hindrance presented by the bulky butoxy group. The rates in aqueous micellar solutions were only marginally faster than those in films for all the three diblock copolymers. In contrast, marked rate differences for the thermal cis−trans isomerization of p(DMAEMA172-b-CPHM7) were observed in film and in solution due to the donor−acceptor effect of CPHM. The observation of a sizable rate difference in different environment for p(DMAEMA172-b-CPHM7) suggests that a rotational mechanism might be operative for these water-soluble amphiphilic diblock copolymers. more...

Four lignans, sacidumlignans A−D (1−4), and two degraded lignan derivatives, sacidumols A (5) and B (6), along with four known compounds, (+)-pinoresinol, 9α-hydroxypinoresinol, perforatic acid, and peucenine-7-O-methyl ether, were isolated from the ethanolic extract of the whole plant of Sarcostemma acidum. The structures and relative configuration of these new compounds were elucidated on the basis of spectroscopic and chemical data, especially 2D NMR techniques. Sacidumlignan D (4) was assigned as a rearranged tetrahydrofuran lignan with an unprecedented skeleton. Sacidumlignan A (1) showed moderate antimicrobial activities against two Gram-positive bacteria in vitro. more...

Poly(lactic acid)s (PLA) were grafted to both ends of Pluronic F127 (PEO−PPO−PEO) to produce novel amphiphilic PLA−F127−PLA block copolymers. The hydrolytic degradation of PLA−F-127−PLA block copolymers in phosphate buffered saline (PBS) (pH 7.4) solution at 37 °C was studied using a combination of physical techniques, such as dynamic light scattering (DLS), transmission electron microscopy (TEM), nuclear magnetic resonance (NMR), and gel permeation chromatography (GPC). It was found that the morphologies and particle size of PLAF127-23 nanoparticles changed dramatically because of the initial rapid degradation of PLA blocks. The morphology of the microstructure transformed from the regular onionlike vesicles to large compound vesicles. With increasing time, the degradation rate of LA−LA linkage was reduced, and the degradation mainly occurred at the interface of F127 and PLA blocks. The morphologies of PLAF127-23 nanoparticles changed from the regular larger compound vesicles to irregular compound vesicles, and to regular large compound vesicles as degradation progresses. Accordingly the particle size of PLAF127-23 nanoparticles decreased initially and remained constant for a certain time period, and it then increased again. more...

The atom transfer radical polymerization technique was used to synthesize the poly(methyl methacrylate-block-methacrylic acid) (P(MAA-b-MMA)) copolymer in order to study the aggregation behavior in aqueous solution over the course of neutralization. Combinations of static and dynamic light scattering (SLS, DLS) and potentiometric titration techniques were used to investigate the size and shape of the micelle at various degrees of neutralization (α). By comparing the effect of different polymer chain length with similar MMA/MAA ratio on the aggregation behavior during neutralization, we found relatively strong entanglement of long MMA polymer chains. The comparison between the different MMA/MAA ratios showed that longer MMA chains produced more entanglements. Conductometric titration was used to determine the counterion condensation phenomenon during the course of neutralization. At a critical micellar charge density observed at α ~ 0.4, Na⁺ ions are condensed on the polymer chains. The amount of condensed Na⁺ was evaluated by the conductivity change, yielding the condensation ratio when the polymer was completely neutralized. more...

Di- and triblock copolymers of ethylene oxide (EO) and ethyl acrylate (EA) were synthesized by the atom transfer radical polymerization technique. The chemical compositions of the di- and triblock copolymers as determined by NMR and gel permeation chromatography are represented by [EO114EA10] and [EA10EO445EA10], respectively. The aggregation behaviors of these polymers in aqueous solutions were studied using a combination of static light scattering (SLS), dynamic light scattering, steady fluorescence, time-resolved fluorescence quenching (TRFQ), and surface tension techniques. The hydrodynamic radii (Rh) of PEO-b-PEA and PEA-b-PEO-b-PEA, where PEO is poly(ethylene oxide) and PEA, poly(ethylene acrylate), in an aqueous solution possess values of 15.3 and 25.5 nm, respectively, and they are independent of the polymer concentrations, which suggest that these micelles are formed via the closed association model. The critical micelle concentration (cmc) for the di- and triblock copolymers as determined from the surface tension are 0.002 and 0.007 wt %, while the aggregation numbers (Nagg) determined from the SLS and TRFQ are 18 and 26, respectively. When the di- and triblock copolymers are mixed in various proportions, unique intermediate cmc values are obtained. The Rh of the mixtures cannot be described by the simple or inverse mixing rule, which confirms that mixed micelles are produced. more...

PtRu nanoparticles supported on Vulcan XC-72 carbon and carbon nanotubes were prepared by a microwave-assisted polyol process. The catalysts were characterized by transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy (XPS). The PtRu nanoparticles, which were uniformly dispersed on carbon, were 2−6 nm in diameter. All PtRu/C catalysts prepared as such displayed the characteristic diffraction peaks of a Pt face-centered cubic structure, excepting that the 2θ values were shifted to slightly higher values. XPS analysis revealed that the catalysts contained mostly Pt(0) and Ru(0), with traces of Pt(II), Pt(IV), and Ru(IV). The electro-oxidation of methanol was studied by cyclic voltammetry, linear sweep voltammetry, and chronoamperometry. It was found that both PtRu/C catalysts had high and more durable electrocatalytic activities for methanol oxidation than a comparative Pt/C catalyst. Preliminary data from a direct methanol fuel cell single stack test cell using the Vulcan-carbon-supported PtRu alloy as the anode catalyst showed high power density. more...

Poly(lactic acid) (PLA) were grafted to both ends of Pluronic F127 (PEO−PPO−PEO) to produce novel amphiphilic PLA-F127−PLA block copolymers. The aggregation behaviors of three different modified polymers were examined by laser light scattering and transmission electron microscopic techniques. The structure of aggregates produced from moderate to long PLA segments (PLAF127−29 (230 units of PLA) and PLAF127−48 (500 units of PLA) systems, respectively) was found to be normal bi-layer vesicles. Polymer with the shortest PLA segment (PLAF127−23 (142 units of PLA)) produces aggregates with complicated onion-like vesicles containing three layers. These vesicles possess microstructure similar to many biological systems, and they exhibit desirable properties for potential applications as drug delivery vehicles. more...

A fumed hydrophilic nano-silica-filled polypropylene (PP) composite was blended with a liquid-crystalline polymer (LCP; Rodrun LC5000). The preblended polymer blend was extruded through a capillary die; this was followed by a series of rheological and morphological characterizations. The viscosity of the PP matrix increased with the addition of the hydrophilic nano-silica. At shear rates between 50 and 200 s⁻¹, the composite displays marked shear-thinning characteristics. However, the incorporation of LC5000 in the PP composite eliminated the shear-thinning characteristic, which suggests that LC5000 destroyed the agglomerated nano-silica network in the PP matrix. Although the viscosity ratio of LCP/PP was reduced after the addition of nano-silica fillers, the LCP phases existed as droplets and ellipsoids. The nano-silicas were concentrated in the LC5000 phase, which hindered the formation of LCP fibers when processed at high shear deformation. We carried out surface modification of the hydrophilic nano-silica to investigate the effect of modified nano-silica (M-silica) on the morphology of the PP/LC5000 blend system. Ethanol was successfully grafted onto the nano-silica surface with a controlled grafting ratio. The viscosity was reduced for PP filled with ethanol-M-silica when compared to the system filled with untreated hydrophilic nano-silica. The LC5000 in the (PP/M-silica)/LC5000 blend existed mainly in the form of fibrils. At high shear rates (e.g., 3000 s⁻¹), the LC5000 fibril network was formed at the skin region of the extrudates. The exclusion of nano-silica in the LC5000 phase and the increased viscosity of the matrix were responsible for the morphological changes of the LCP phase. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1484–1492, 2003 more...