Polarization Gradient Research Articles

Flexoelectric nanostructure design using explicit topology optimization

Flexoelectricity is the coupling between polarization and strain gradient. As the large strain gradient leads to a strong flexoelectric effect, the design of flexoelectric nano-structure via topology optimization has seen growing attentions. In the present work, an explicit topology optimization framework is proposed for flexoelectric structures design. To achieve this purpose, the Moving Morphable Void (MMV)-based approach is employed in the context of Isogeometric Analysis (IGA) combined with the Trimming Surface Analysis (TSA). Energy conversion factor and effective electric polarizability are respectively optimized to improve the flexoelectric performance of the nanostructure. Performing design under the explicit framework coupled with IGA can bring several advantages. Due to the use of NURBS basis functions of IGA, the required continuity in the approximation of the PDEs of flexoelectricity can be satisfied straightforwardly. Furthermore, with the use of the TSA technique, the occurrence of weak/gray material, which may cause numerical instability in flexoelectricity design, can be avoided. Also due to the explicit geometry description in MMV, the optimized result can be imported to the CAD system directly, which is significant for nanoscale structure from manufacturing perspective. Several representative numerical examples for topology optimization of flexoelectric structures are presented to demonstrate the effectiveness and advantages of the proposed approach.

Robust polarization gradient cooling of trapped ions

We implement three-dimensional polarization gradient cooling (PGC) of trapped ions. Counter-propagating laser beams near 393 nm impinge in lin ⊥ lin configuration, at a frequency below the S1/2 to P3/2 resonance in 40Ca+. Our measurements demonstrate that cooling with laser beams detuned to lower frequencies from the resonance is robust against an elevated phonon occupation number and works continuously in the crossover from regular Doppler cooling to detunings of tens of linewidths. It is thus robust against heating events and also works well for an initial ion motion far out of the Lamb–Dicke regime. We show that PGC performance strongly depends on residual micromotion (MM) and find PGC working for a MM modulation index β ⩽ 0.1. Still, we find that the spectral impurity of the laser field affects both, cooling rates and cooling limits. Thus, a Fabry–Pérot cavity filter is employed to efficiently suppress amplified spontaneous emission of the diode laser. We demonstrate mean phonon numbers for a single ion of 5.4(4) at a trap frequency of 2π × 285 kHz and 3.3(4) at 2π × 480 kHz, in the axial and radial directions, respectively.

Polarity affects the antioxidant and antimicrobial activities of jellyfish (Acromitus hardenbergi) extracts

Jellyfish is an emerging aquaculture species, farmed for Oriental cuisines and nutraceutical ingredients. This study aimed to examine antioxidative and antimicrobial potentials of various fractions of the jellyfish, Acromitus hardenbergi. The bell and oral arms of the jellyfish were sequentially extracted with petroleum ether (PE), dichloromethane (DCM), chloroform (CHCl3), methanol (MeOH), and water (H2O) to extract its bioactive in an increasing polarity gradient. Test fractions were assayed for antiradical activities using electron spin resonance spectrometry, β-carotene-linoleate model and Folin-Ciocalteu assay; and antimicrobial activity against 2 Gram-negative bacteria, 4 Gram-positive bacteria and 2 fungal species using the disc diffusion assay. All fractions were also subjected to Fourier Transform Infrared (FTIR) analysis to identify types of functional groups present. It was found that the hydrophilic extracts (H2O fractions) possessed the most effective radical scavenging activity (p < 0.05) while the lipophilic extracts (PE fractions) the most active antimicrobial activity, especially against Gram-positive bacteria (p < 0.05). Total oxidation substrates content was found to be highest in the PE fractions of jellyfish bell and oral arms (p < 0.05). FTIR data showed that the H2O and MeOH fractions contains similar functional groups including -OH, -C=O, -N-H and -S=O groups, while the PE, DCM, and CHCl3 fractions, the -CH3, -COOH groups. This study showed that A. hardenbergi contains antioxidants and antimicrobials, thereby supporting the traditional claim of the jellyfish as an anti-aging and health-promoting functional food. Bioassay-guided fractionation approach serves as a critical milestone for the strategic screening, purification, and elucidation of therapeutically significant actives from jellyfish.

Broadband cross-circular polarization carpet cloaking based on a phase change material metasurface in the mid-infrared region

In view of the fact that most invisibility devices focus on linear polarization cloaking and that the characteristics of mid-infrared cloaking are rarely studied, we propose a cross-circularly polarized invisibility carpet cloaking device in the mid-infrared band. Based on the Pancharatnam-Berry phase principle, the unit cells with the cross-circular polarization gradient phase were carefully designed and constructed into a metasurface. In order to achieve tunable cross-circular polarization carpet cloaks, a phase change material is introduced into the design of the unit structure. When the phase change material is in amorphous and crystalline states, the proposed metasurface unit cells can achieve high-efficiency cross-polarization conversion, and reflection intensity can be tuned. According to the phase compensation principle of carpet cloaking, we construct a metasurface cloaking device with a phase gradient using the designed unit structure. From the near- and far-field distributions, the cross-circular polarization cloaking property is confirmed in the broadband wavelength range of 9.3–11.4 µm. The proposed cloaking device can effectively resist detection of cross-circular polarization.

Tuning Ferroelectric Response of Electroactive Materials by Controlling Multilayered Structures to Achieve Excellent Energy Storage Performance

Flexible ferroelectric polymers are key candidates for flexible capacitive electronic devices. However, there is a lack of functional and accessible methods to control the ferroelectric response of polymers. Herein, a novel and effective approach is adopted to tune the ferroelectric response of polymers, over the conventional methods (graft or block copolymerization). Specifically, a central ferroelectric poly(vinylidene fluoride‐co‐trifluoroethylene) (P(VDF‐TrFE)) layer is sandwiched between shielding layers (polymethacrylate (PMMA)). The differently distributed electric fields were generated in inner and outer layers owing to a larger polarization gradient between PMMA and P(VDF‐TrFE), building a competition in the local ferroelectric layer. Controlling the polarization and thickness of the shielding layer may result in the electric field in it being lesser than the electric field in the ferroelectric layer during reverse poling, leading to a part of the dipoles reverting to the initial direction in the ferroelectric layer. Then dipoles along antiparallel directions coexist in P(VDF‐TrFE), leading to antiferroelectric‐like behavior. With the low remnant polarization, antiferroelectric‐like films possess an excellent discharge energy density (11.72 J cm−3 at 3300 kV cm−1). Given the practicability and simplicity of tuning the ferroelectric response, it is firmly believed that this method will cut a conspicuous figure in a supercapacitor with ultrahigh energy density and discharged efficiency.

Flexoelectricity and electronic properties of monolayer GaSe under shear strain gradient

The flexoelectric effect is a linear coupling phenomenon between electric polarization and mechanical strain gradient. Due to the size dependence, the influence of flexoelectricity on the physical properties of two-dimensional (2D) materials will be very significant. In this paper, we found that inhomogeneous deformation can lead to significant flexoelectric effects in monolayer GaSe. The strain gradient introduced by the deformation along the film thickness leads to out-of-plane ferroelectric polarization and shows an obvious size effect. The shear flexoelectric coefficient of monolayer GaSe is 0.048e, which is one order of magnitude larger than TMDs monolayers. In addition, the strain gradient can modulate the band gap of 2D materials in a wide range, indicating that out-of-plane deformation can dramatically regulate the electronic conductivity and optical properties of GaSe monolayer. Our work reveals that the flexoelectric effect of monolayer GaSe has great application potential in nano-strain engineering and flexible electronics.

The Chinese medicine babaodan suppresses LPS-induced sepsis by inhibiting NLRP3-mediated inflammasome activation

Ethnopharmacological relevanceBBD is a well-known traditional Chinese medicine widely used in clinic to treat viral hepatitis, cholecystitis, angiocholitis and urinary tract infection. According to traditional medicinal theory, BBD exerts the effects of “clearing and humid heat, activating blood and removing toxicity, curing jaundice and relieving pain”, the signs of which are recognized as common symptoms of inflammation during infectious diseases in modern medicine. Aim of the studyTo determine the therapeutic effect of BBD on bacterial endotoxin lipopolysaccharide (LPS) induced sepsis and to investigate the relevant pharmacological and molecular mechanisms of action whereby BBD mitigates inflammation. Materials and methodsIn vivo, a mouse sepsis model was induced by intraperitoneally injection of LPS; the BBD were formulated as drug suspension for intragastric administration. The survival rate, secretion of pro-inflammatory cytokines of IL-1β and TNF-α, and multiple organ injury of lung, liver and spleen were examined. In vitro, peritoneal macrophages (PMs) were stimulated with LPS plus ATP for NLRP3 inflammasome activation; polar gradient extractions of BBD from ultrapure water (sample 1) followed by 70% ethanol (sample 2) were added as interventions. In addition to detect the secretion of IL-1β and TNF-α, the activation of NF-κB, ASC-speck formation and ASC oligomerization were examined by western blotting and immunofluorescent stainning. Eventually, the extractions of BBD were applied for UPLC-QTOF-MS analyses; refer to the identified chemicals, the bioactive compounds in BBD with anti-NLRP3 inflammasome activities were discussed. ResultsBBD improved the survival of sepsis mice accomplished with diminished inflammatory cytokines production and multiple organ injury. Mechanistically, BBD inhibited both the NF-κB pathway and the assembly of NLRP3 complex in PMs. There were 29 chemical compounds identified from sample 1 and 20 from sample 2. Both samples contained bile acids and saponins and sample 2 contained 2 extra chemicals in the category of bile acids. ConclusionsBBD presents therapeutic role of endotoxin induced sepsis by inhibiting NLRP3-medaited inflammasome activation, which supports its traditional use for the treatment of infectious diseases. The bile acids and saponins are most likely related to the anti-NLRP3 inflammasome activation effect of BBD.

A Comparison of Multiphase Magnetic Field Tracers in a High Galactic Latitude Region of the Filamentary Interstellar Medium

Abstract Understanding how the Galactic magnetic field threads the multiphase interstellar medium (ISM) remains a considerable challenge, as different magnetic field tracers probe dissimilar phases and field components. We search for evidence of a common magnetic field shared between the ionized and neutral ISM by comparing 1.4 GHz radio continuum polarization and H i line emission from the Galactic Arecibo L-Band Feed Array Continuum Transit Survey (GALFACTS) and Galactic Arecibo L-Band Feed Array H i (GALFA-H i) survey, respectively. We compute the polarization gradient of the continuum emission and search for associations with diffuse/translucent H i structures. The polarization gradient is sensitive to changes in the integrated product of the thermal electron density and line-of-sight field strength (B ∥) in warm ionized gas, while narrow H i structures highlight the plane-of-sky field orientation in cold neutral gas. We identified one region in the high Galactic latitude Arecibo sky, G216+26 centered on (ℓ, b) ∼ (216°, +26°), containing filaments in the polarization gradient that are aligned with narrow H i structures roughly parallel to the Galactic plane. We present a comparison of multiphase observations and magnetic field tracers of this region, demonstrating that the warm ionized and cold neutral media are connected likely via a common magnetic field. We quantify the physical properties of a polarization gradient filament associated with Hα emission, measuring a line-of-sight field strength B ∥ = 6 ± 4 μG and a plasma beta β = 2.1 − 2.1 + 3.1 . We discuss the lack of widespread multiphase magnetic field alignments and consider whether this region is associated with a short-timescale or physically rare phenomenon. This work highlights the utility of multitracer analyses for understanding the magnetized ISM.

Flexoelectricity in hexagonal boron nitride monolayers

Two-dimensional (2D) materials are highly bendable due to their atomic thickness and, thus, can readily attain a large strain gradient hard to achieve in bulk materials. This attribute provides a unique platform to explore the coupling between strain gradient and electric polarization, referred to as flexoelectric effect. Here, we perform an intensive first-principles study of the flexoelectric effect in hexagonal boron nitride (h-BN) monolayer for its potential applications in harsh environments. Despite being an isoelectronic isomorph of graphene, h-BN exhibits a distinctly higher flexoelectric coefficient than graphene does, along with a stronger nonlinearity. The enhanced flexoelectricity is ascribed to bending-induced structural buckling that separates B and N atoms into two coaxially curved surfaces, whose effect is well quantified by a model analysis. This behavior also helps rationalize why the three-atom-thick MoS2 has the largest flexoelectric coefficient among these 2D materials. We also find that the flexoelectricity results in a staggered band gap in all double-walled BN nanotubes that can favor charge separation in photovoltaics, in contrast to the size- and chirality-dependent band alignment in double-walled carbon nanotubes.

Polarization Gradient Effect of Negative Capacitance LTFET.

In this paper, an L-shaped tunneling field effect transistor (LTFET) with ferroelectric gate oxide layer (Si: HfO2) is proposed. The electric characteristic of NC-LTFET is analyzed using Synopsys Sentaurus TCAD. Compared with the conventional LTFET, a steeper subthreshold swing (SS = 18.4 mV/dec) of NC-LTFET is obtained by the mechanism of line tunneling at low gate voltage instead of diagonal tunneling, which is caused by the non-uniform voltage across the gate oxide layer. In addition, we report the polarization gradient effect in a negative capacitance TFET for the first time. It is noted that the polarization gradient effect should not be ignored in TFET. When the polarization gradient parameter g grows larger, the dominant tunneling mechanism that affects the SS is the diagonal tunneling. The on-state current (Ion) and SS of NC-LTFET become worse.

Phase-field simulation on the interaction of oxygen vacancies with charged and neutral domain walls in hexagonal YMnO3

A three-dimensional model of the interaction between the charged or neutral domain walls and oxygen vacancies in the hexagonal manganite YMnO3 was proposed, and simulated using Landau–Ginzburg–Devonshire (LGD) theory, dynamic diffusion equation and Maxwell’s equation. The calculation proves that stiffness anisotropic factors can adjust the domain wall state and ultimately affect the distribution of oxygen vacancies. The head-to-head domain wall corresponds to low oxygen vacancy density, and the tail-to-tail domain wall corresponds to high oxygen vacancy density. The electrostatic field generated by the bound charge is the key factor leading to the change of oxygen vacancy distribution. Finally, e-index law N d = ae b*dP/dz can fit the relationship between the oxygen vacancy concentration and the polarization gradient along z direction. Our theory provides a new way to modulate the distribution of oxygen vacancies through domain wall morphology in hexagonal YMnO3.

Abnormal Electromechanical Property of Nonlinearly Graded Lead‐Free Ferroelectric Thin Films (Adv. Theory Simul. 2/2022)

Large piezoelectric effect in nonlinearly graded lead-free ferroelectric thin films In article number 2100370, using extended phase field simulations, Le Van Lich and co-workers demonstrate that a large piezoelectric effect can be obtained in nonlinearly graded lead-free ferroelectric thin film. The enhancement of piezoelectric property originates from the large gradient of electrical polarization, which makes the polarization field more susceptible to external excitation.

Enhanced Upconversion Photoluminescence Assisted by Flexoelectric Field in Oxide Nanomembranes

AbstractFlexoelectricity refers to the linear coupling between electric polarization and strain gradients, and exhibits in all materials with arbitrary crystal symmetries. Recent breakthroughs on synthesizing high‐quality freestanding perovskite oxides have provided new opportunities to couple this universal effect to various functionalities. In particular, the interplay between flexoelectricity and upconversion emission in lanthanide doped freestanding perovskite oxide SrTiO3:Er3+ nanomembranes is experimentally demonstrated. The tunable flexoelectricity leads to an over fourfold enhancement in upconversion photoluminescence (PL) through strain gradient engineering. The observed significant PL enhancement can be ascribed to the strain gradient induced polarization, or more fundamentally, inversion symmetry breaking. Furthermore, this behavior is reversible and exhibits excellent antifatigue characteristics even after 104 bending cycles. The showcased strong coupling between flexoelectricity and photoluminescence in nonpolar materials offers dramatically greater design freedom for various strain‐tunable optoelectronic devices, regardless of the lattice symmetry of the constituent materials.

A free-piston batch reverse osmosis (RO) system for brackish water desalination: Experimental study and model validation

Batch RO is designed to achieve high energy efficiency and high recovery in desalination. However, so far relatively few experiments on batch RO have been reported. Here we present an extensive experimental study of a single-acting, free-piston batch RO system using an 8-inch spiral wound membrane. The system was tested in the laboratory with brackish feed water containing up to 5 g/L NaCl. The objective was to quantify system performance in terms of Specific Energy Consumption (SEC), recovery, rejection, and output. Sensitivity to permeate flux and recirculation flow rate was also investigated. Performance was compared against the predictions of a theoretical model that accounts for salt retention, concentration polarization, and longitudinal concentration gradient in the RO module. For the first time, osmotic backflow was measured and incorporated into the model. For feed concentrations ranging from 1 to 5 g/L and recovery of 0.8, hydraulic SEC was measured in the range 0.22–0.48 kWh/m3 and electrical SEC in the range 0.48–0.83 kWh/m3. With improvements to the membrane permeability from 4.4 to 8 LMH/bar, selection of more efficient pumps, and reduction of valve friction losses, the model predicts that hydraulic SEC will be lowered to 0.14–0.39 kWh/m3.

Mechanism for switchability in electron-doped ferroelectric interfaces

With the recent experimental verification that ferroelectric lattice distortions survive in the metallic phase of some materials, there is a desire to create devices that are both switchable and take advantage of the novel functionalities afforded by polar interfaces. In this work, we explore a simple model for such an interface and demonstrate a mechanism by which a metallic ferroelectric substrate may be switched by a bias voltage. This finding is in contrast to the reasonable expectation that hysteresis is prevented by screening of external fields in ferroelectric metals. Instead, the electron gas binds to polarization gradients to form a compensated state. Uncompensated electrons, which may screen external fields, are generated either when the electron density exceeds the ferroelectric polarization or when the bias voltage exceeds a "spillover" threshold. We propose that switchable thin films may be optimized by choosing an electron density that is slightly less than the lattice polarization. In addition to the high-polarization states, we find that thin metallic films also have a low-polarization state with average polarization near zero. Unlike in insulating films, where the polarization is small everywhere in this state, the low-polarization state in the metallic films consists of two head-to-head domains of opposite polarization. This domain formation is enabled by the screening of depolarizing fields by the electron gas.

Identification of the main phenolic compounds responsible for the antioxidant activity of Litsea glaucescens Kunth

Litsea glaucescens is a native plant from Mexico and Central America known as laurel, and they leaves are commonly used as food seasoning and traditional medicine, however, there is not enough information about its biological activities, as antioxidant and the compounds responsible of this activity. The antioxidant activity and the total phenolic content of a methanolic extract of L. glaucescens leaves (LGE) and a series of twelve chromatographic fractions (I-XII) obtained through a polarity gradient elution are reported in this work. In all the cases a concentration-response was observed since the DPPH inhibition increases (p≤0.05) as a function of the concentration. Nevertheless, the most polar fractions XI and XII were the most effective of the series (100 µg/mL=93 and 91%, 50 µg/mL= 93 and 91%, 25 µg/mL =92 and 87% and 12.5 µg/mL=85 and 53% of radical inhibition, respectively). The results of the FRAP assay confirmed that XI and XII have the highest antioxidant activity (7994.06 and 5011.03 µmol Fe(II)/g, respectively) and the total phenolic content, evaluated by the Folin-Ciocalteu method, was also the highest in both fractions (462.9 and 347.5 mg GAE/g of dry weight, respectively). In addition, epicatechin, was isolated from XI, whereas quercitrin and kaempferol were obtained from XII by flash chromatography and their structures were elucidated through HPLC-ESI-MS and NMR spectroscopy. Then, it is possible to infer that these phenolic compounds are the main responsible for the antioxidant activity of L. glaucescens. Our study provides information that may be useful for the use of this natural product in food and pharmaceutical formulations.

Regulating Interfacial Li-Ion Transport via an Integrated Corrugated 3D Skeleton in Solid Composite Electrolyte for All-Solid-State Lithium Metal Batteries.

Although solid composite electrolytes show tremendous potential for the practical solid‐state lithium metal batteries, searching for a straightforward tactic to promote the ion conduction at electrolyte/electrode interface, especially settling lithium dendrites formation caused by the concentration gradient polarization, are still long‐standing problems. Here, the authors report a corrugated 3D nanowires‐bulk ceramic‐nanowires (NCN) skeleton reinforced composite electrolyte with regulated interfacial Li‐ion transport behavior. The special and integrated NCN skeleton endows the electrolyte with fast Li‐ion transfer and solves the Li+ concentration polarization at electrode/electrolyte interface, thereby eliminating the energy barrier originated from the redistribution of charge carriers and offering homogeneous interfacial Li‐ion flux on lithium anode. As a “double insurance”, the bulk ceramic sheet in 3D framework enables the electrolyte to block the mobility of anions. The rational designed NCN composite electrolyte exhibits excellent ionic conductivity and the assembled all‐solid‐state battery possesses 90.2% capacity retention after 500 cycles. The proposed strategy affords a special insight in designing high‐performance solid composite electrolytes.

Hole mobility behavior in Al-gradient polarization-induced p-type AlGaN grown on GaN template

A series of samples with their AlGaN layers of decreasing Al contents along the c-axis are grown on GaN templates with molecular beam epitaxy for producing polarization-induced p-type behaviors. By fixing the Al-gradient rate at 0.15%/nm and AlGaN layer thickness at 100 nm while changing the central Al content in those samples, we study the dependence of hole mobility on the central Al content. As the central Al content increases, hole mobility decreases monotonically with two different decreasing slopes in the two Al-content ranges divided at ∼40%. Tensile strain relaxation is observed when the Al content is higher than ∼40%, resulting in the increase in overall polarization gradient and, hence, hole concentration. Although the variation of the alloy scattering strength of hole in AlGaN can support the smaller decreasing slope of hole mobility in the Al-content range of >40%, other factors, such as piezoelectric scattering and bound charge distribution, may need to be considered for a complete interpretation. Compared with Mg-doped p-type AlGaN of 25% in an Al content, the polarization-induced p-type AlGaN can provide us with a higher hole mobility level at about the same hole concentration.

Correcting B0 inhomogeneity-induced distortions in whole-body diffusion MRI of bone

Diffusion-weighted magnetic resonance imaging (DWI) of the musculoskeletal system has various applications, including visualization of bone tumors. However, DWI acquired with echo-planar imaging is susceptible to distortions due to static magnetic field inhomogeneities. This study aimed to estimate spatial displacements of bone and to examine whether distortion corrected DWI images more accurately reflect underlying anatomy. Whole-body MRI data from 127 prostate cancer patients were analyzed. The reverse polarity gradient (RPG) technique was applied to DWI data to estimate voxel-level distortions and to produce a distortion corrected DWI dataset. First, an anatomic landmark analysis was conducted, in which corresponding vertebral landmarks on DWI and anatomic T2-weighted images were annotated. Changes in distance between DWI- and T2-defined landmarks (i.e., changes in error) after distortion correction were calculated. In secondary analyses, distortion estimates from RPG were used to assess spatial displacements of bone metastases. Lastly, changes in mutual information between DWI and T2-weighted images of bone metastases after distortion correction were calculated. Distortion correction reduced anatomic error of vertebral DWI up to 29 mm. Error reductions were consistent across subjects (Wilcoxon signed-rank p < 10–20). On average (± SD), participants’ largest error reduction was 11.8 mm (± 3.6). Mean (95% CI) displacement of bone lesions was 6.0 mm (95% CI 5.0–7.2); maximum displacement was 17.1 mm. Corrected diffusion images were more similar to structural MRI, as evidenced by consistent increases in mutual information (Wilcoxon signed-rank p < 10–12). These findings support the use of distortion correction techniques to improve localization of bone on DWI.

Brain diffusion MRI with multiplexed sensitivity encoding for reduced distortion in a pediatric patient population

BackgroundDiffusion-weighted imaging (DWI) is a valuable tool for routine imaging of the pediatric brain. However, the commonly used single-shot (ss) echo-planar imaging (EPI) DWI sequence is prone to geometric distortions and T2*-blurring. This study aimed to investigate in a pediatric population the benefits of using multiplexed sensitivity-encoding (MUSE) without and with reversed polarity gradients (RPG) instead. MethodsThis retrospective study compared image quality, geometric distortions, and diffusion values between three different approaches for DWI (ssEPI, MUSE, and RPG-MUSE) in 14 patients (median age = 4 (0.6–15) years, 11 males). Distortion levels were quantified and compared in two brain regions, i.e., the brain stem and the temporal lobes, using the Dice Coefficient and the Hausdorff Distance, with T2-weighted images as reference. Expected geometrical distortion was further evaluated by comparing the effective echo spacing between the DWI sequences. Apparent diffusion coefficient (ADC) values were determined in the genu of the corpus callosum and the optic nerves. Two raters graded overall image quality and image distortions on a Likert scale. ResultsDistortion levels assessed with Dice coefficient and Hausdorff distance were significantly lower for MUSE (p < 0.05) and RPG-MUSE (p < 0.01) compared to ssEPI. No significant difference in ADC values was observed between methods. The RPG-MUSE method was graded by one rater as significantly higher in overall image quality than ssEPI (p < 0.05) and by both raters as significantly lower in levels of image distortions than both MUSE (p < 0.05) and ssEPI (p < 0.05). These results were in agreement with the reduced effective echo spacing was that was attained with MUSE and RPG-MUSE. ConclusionFor imaging of the pediatric brain, MUSE and even more so RPG-MUSE offers both improved geometric fidelity and image quality compared to ssEPI.