Polar Gap Research Articles

A theoretical evaluation for new fused remote N‐heterocyclic silylenes (RNHSis) using density functional theory

AbstractIn this research, we compare and contrast the stability, polarity, polarizability, band gap, and global reactivity of singlet (s) and triplet (t) fused benzene N‐heterocyclic silylene (1‐s and 1‐t) along with five numbered congeners (2x‐s, and 2x‐t, x = CH2, SiH2, GeH2, NH, PH, AsH, O, S, and Se) at DFT (density functional theory). All singlet and triplet remote N‐heterocyclic silylenes (RNHSis) appear as minima showing positive force constant. Every singlet RNHSi emerges as ground state and exhibits more stability than its corresponding triplet RNHSi. In going from 1‐s to 2x‐s species, the thermodynamic and kinetic stability is increased, so that higher ΔEs‐t (= Et − Es) and higher band gap or ΔEHOMO–LUMO (=ELUMO − EHOMO) is considered for 2CH2‐s, 2NH‐s, and 2O‐s structures. In going from second row to forth row of every group in the periodic table, electronegativity of heteroatoms have pronounced effect on the stability, polarity, polarizability, and band gap of 2x‐s species. These silylenes show more stability than the synthesized silylene by Kira. Every 2x‐t silylene shows higher nucleophilicity (about 1.6 times) than its corresponding 2x‐s analogous. Every singlet RNHSi reveals lower nucleophilicity (N), higher electrophilicity (ω), chemical potential (μ), and global hardness (η) than its triplet congener. Furthermore, 2x‐s silylenes benefit from stabilization effect of two heteroatoms synchronously in the fused five‐membered ring via mesomeric effect and π donation from the lone pairs of heteroatom to the formally vacant 3p orbital of the silylenic center. Hence, we predict higher stability as well as lower global reactivity of RNHSis than Kira's silylene will make them creditable for the synthetic research.

Optical properties of polar and nonpolar GaN/AlN multiquantum well systems—DFT study

Ab initio simulations were applied for nonpolar GaN/AlN superlattices of various widths for the first time giving band diagrams and optical transition oscillator strengths. The results confirmed the absence of electric fields in m-plane GaN/AlN multiquantum well (MQW) systems leading to drastically different properties of polar and nonpolar systems, narrow polar and nonpolar GaN/AlN well properties, such as bandgap or oscillator strength. Wider wells show drastic differences related to the presence of electric fields in polar systems. Wide nonpolar wells have bandgaps following parabolic dependence resulting from localization energy. Polar wide well gaps are determined by spontaneous and piezoelectric fields that reduce bandgap for wider wells and barriers. Oscillator strength shows a more dramatic difference between polar and nonpolar wells. Drastic reduction in the oscillator strength is observed for wide polar MQWs. The decrease in the oscillator strength by several orders of magnitude is observed for the increase in the width of wells and barriers. The wide polar wells should have extremely ineffective radiative emission from both direct and across the barrier overlap of electron–hole wavefunctions.

Bridging the polarization gap: Maximizing diffusion among dissimilar communities

Polarized networks, composed of weakly connected and self-reinforcing groups, can limit the diffusion of ideas, behaviors, and innovations. Here, we use a complex contagion model, in which diffusion depends on both the connectivity and the similarity of individuals, to ask how to optimally build bridges and enhance diffusion in networks characterized by fragmentation and homophily. First, we show that the problem is NP-hard. Then, we explore the space of solutions using heuristics, finding that connecting high degree nodes, or hubs, is an ineffective strategy to accelerate diffusion in fragmented and homophilous networks. We show that in these networks, diffusion is more effectively accelerated by connecting similar but low degree nodes. These results tell us that, in the presence of homophily and polarization, connecting communities through their most central actors may impede rather than facilitate diffusion. Instead, strategies to accelerate the diffusion of innovation, behaviors, and ideas should focus on creating links among the most similar members of different communities. These findings shed light on the diffusion of ideas and innovations in polarized networks. CCS Concepts: • Mathematics of computing → Network optimization; • Information systems → Social networks

Information avoidance in a polarized society

This well-powered, pre-registered study explores how the behavior of dictators is affected by allowing them, in a give-or-take dictator game, to choose whether they want to know the recipient's position on a polarizing matter. Specifically, we study whether the option to avoid polarizing information reduces the polarization gap, i.e., the difference between the amounts given to recipients’ holding aligned and conflicting positions. We find that over 30% of dictators choose to avoid potentially polarizing information, and that this choice substantially decreases the polarization gap. We also find that those who choose to remain uninformed expect the polarization gap to be smaller than those who choose to be informed.

Towards an ultra-long lifespan Li-CO2: electron structure and charge transfer pathway regulation on hierarchical architecture

Lithium-CO2 batteries are recognized as an essential strategy for efficient carbon sequestration and energy storage to achieve carbon neutrality. Their cycle-ability and polarization voltage, however, are hindered by high decomposition voltage (≈4.3–4.5 V) of insulating Li2CO3. Herein, we report a significant advance toward the rational design of self-supporting and ultra-long cycle lifetime cathode for Li-CO2 batteries, dependence on a favorable hierarchical architecture and rich charge transfer constructed by homogeneously distributed MnO2 nanoplates rooted in the MXene surface supported by carbon paper. Detailedly, it exhibits impressive ultra-long-term stability of 1087 cycles (4348 h) with a low polarization gap (≈ 0.47 V) at a high current of 200 μA cm−2, which is outperformed by all the liquid electrolyte-based Li-CO2 batteries reported previously. Electronic structure analysis reveals that facile charge transfer occurs between catalytic surface and Li2CO3, springing from the –OH functional group (in MXene) to MnO2 by –OH⋯O hydrogen bonds, which acts as charge transfer channels, improving the metallicity of Li2CO3 and facilitating its decomposition and extending battery cyclability. This work paves an effective trajectory for the future development of highly efficient cathodes for durable metal-CO2 batteries.

Combining advanced photoelectron spectroscopy approaches to analyse deeply buried GaP(As)/Si(1 0 0) interfaces: Interfacial chemical states and complete band energy diagrams

The epitaxial growth of the polar GaP(100) on the nonpolar Si(100) substrate suffers from inevitable defects at the antiphase domain boundaries (APDs), resulting from mono-atomic steps on the Si(100) surface. Stabilization of Si(100) substrate surfaces with As is a promising technological step enabling the preparation of Si substrates with double atomic steps and reduced density of the APDs. In this paper, 4–50-nm-thick GaP epitaxial films were grown on As-terminated Si(100) substrates with different types of doping, miscuts, and As-surface termination by metalorganic vapor phase epitaxy (MOVPE). The GaP(As)/Si(100) heterostructures were investigated by X-ray photoelectron spectroscopy (XPS) combined with gas cluster ion beam (GCIB) sputtering and by hard X-ray photoelectron spectroscopy (HAXPES). We found residuals of As atoms in the GaP lattice (∼0.2–0.3 at.%) and a localization of As atoms at the GaP(As)/Si(100) interface (∼1 at.%). Deconvolution of core level peaks revealed interface core level shifts. In As core levels, chemical shifts between 0.5 and 0.8 eV were measured and identified by angle-resolved XPS measurements. Similar valence band offset (VBO) values of 0.6 eV were obtained, regardless of the doping type of Si substrate, Si substrate miscut or type of As-terminated Si substrate surface. The band alignment diagram of the GaP(As)/Si(1 0 0) heterostructure was deduced.

Radio Emission of Pulsars. I. Slow Tearing of a Quantizing Magnetic Field

The pulsed radio emission of rotating neutron stars is connected to slow tearing instabilities feeding off an inhomogeneous twist profile within the open circuit. This paper considers the stability of a weakly sheared, quantizing magnetic field in which the current is supported by a relativistic particle flow. The electromagnetic field is almost perfectly force free, and particles are confined to the lowest Landau state, experiencing no appreciable curvature drift. In a charge-neutral plasma, we find multiple branches of slowly growing tearing modes, relativistic analogs of the double-tearing mode, with peak growth rate . Here, B z is the strong (nearly potential) guide magnetic field, J z the field-aligned current density, and is the mode wavenumber normalized by the current gradient scale. These modes are overstable when the plasma carries a net charge, with the real frequency proportional to the imbalance in the densities of positive and negative charges. An isolated current sheet thinner than the skin depth supports localized tearing modes with growth rate scaling as (sheet thickness/skin depth)−1/2. In a pulsar, the peak growth rate is comparable to the angular frequency of rotation, , slow compared with the longitudinal oscillations of particles and fields in a polar gap. The tearing modes experience azimuthal drift reminiscent of subpulse drift and are a promising driver of pulse-to-pulse flux variations. A companion paper demonstrates a Cerenkov-like instability of current-carrying Alfvén waves in thin current sheets with relativistic particle flow and proposes coherent curvature emission by these waves as a source of pulsar radio emission.

Affective polarization and political engagement in the United States: what factors matter?

ABSTRACT This article examines the factors that predict affective polarization and political engagement in the United States. Using an original survey dataset (N = 1,100) of a fairly representative national sample, this study explored some factors (e.g., age, gender, political ideology, and partisan news media and social media) to see how they predict affective polarization and political engagement. The results could be helpful to further study widening affective polarization, which is reportedly affecting democracy itself, in this current political and public opinion atmosphere “Trumpfied” in the last couple of years. The insights found in this research could also help devise political and social campaign strategies that minimize polarization gaps. The results might enable corporate entities to better classify their consumers based on relevant issues associated with polarization and political engagement. Future research is encouraged to combine survey data and social media data for a more refined outcome.

Origin of low dielectric permittivity in crosslinked cellulose/ Kevlar fiber composites as revealed via molecular dynamics simulation

The mismatch of the dielectric constant of oil-paper insulation mainly affects the unreasonable field strength distribution of oil-paper insulation under alternating current conditions. Reducing the dielectric constant of insulation paper by using low dielectric constant Kevlar is an effective way to modify natural fibers. However, the bonding capability of Kevlar and natural fibers is poor. Based on the molecular simulation method, the influence mechanism of different butanetetracarboxylic acid (BTCA) contents on the dielectric constant of cellulose-Kevlar composite structures is analyzed from the perspective of free volume, bond length and angle distribution, and glass transition temperature. The bonding performance of Kevlar and cellulose molecular chains is strengthened when BTCA content is increased and the fractional free volume of the composite structure is reduced. Such a reduction restricts the movement of polar groups and decreases the dielectric constant of the composite structure. Further increasing the BTCA content will raise the number of polar groups and gaps in the system, which is conducive to the establishment of the turning polarization, leading to an increase in the dielectric constant. Within the range of BTCA content selected in the paper, the dielectric constant of the composite structure first decreases, then rises with an increase in BTCA content, and finally reaches the minimum value (3.53) when the BTCA content is 3%. The crosslinking modification method achieves the purpose of improving the dielectric properties of the composite structure and provides a certain theoretical basis for the study of low dielectric constant insulating paper.

Template-assisted synthesis of single-atom catalysts supported on highly crystalline vanadium pentoxide for stable oxygen evolution

Single-atom catalysts (SACs) have drawn considerable attention due to their maximum atomic catalyst utilization, unique electronic properties, and high cost efficiency, but they tend to aggregate during synthesis, and corrosive carbonaceous supports gradually degrade their original performance. Herein, we develop a template-assisted synthesis of Co SACs anchored on highly crystalline V2O5·nH2O nanobelts (CoVO NBs) for achieving highly stable oxygen evolution reaction (OER). The Co sites on oxide supports weaken the binding energy of reaction intermediates and work as active reaction sites. Even though the partial leaching of V4+ ions was observed during electrocatalysis, the remaining Co moieties helped to maintain high OER activity and exceptional durability, with initial overpotentials of 428 and 374 mV observed at 10 mA cm−2 in 0.1 and 1 M KOH, respectively. Furthermore, zinc (Zn)–air cells with CoVO30 NBs displayed a small initial charge-discharge polarization gap (0.78 V) and high cycling performance up to 450 h.

Externally driven plasma models as candidates for pulsar radio emission

ABSTRACT Coherent radio emission from pulsars originates from excited plasma waves in an ultra-relativistic and strongly magnetized electron–positron pair plasma streaming along the open magnetic field lines of the pulsar. Traditional coherent radio emission models have relied on instabilities in this pair plasma. Recently, alternative models have been suggested. These models appeal to direct coupling of the external electromagnetic field to the superluminal O-mode (lt2 mode) during the time-dependent pair cascade process at the polar gap. The objective of this work is to provide generic constraints on plasma models based on lt2 mode using realistic pulsar parameters. We find that the very short time-scale associated with pair cascades does not allow lt2 mode to be excited at radio frequencies and the impulsive energy transfer can only increase the kinetic spread (‘temperature’) of the pair plasma particles. Moreover, under homogeneous plasma conditions, plasma waves on both branches of O mode (i.e. superluminal lt2 and subluminal lt1) cannot escape the plasma. In the strongly magnetized pair plasma, only the extraordinary mode (t mode) can escape freely. We show that any generic fictitious mechanisms do not result in the wave electric field of t mode to have predominant orientation either parallel or perpendicular to the magnetic field plane as observed. Such fictitious mechanisms will inevitably lead to depolarization of signals and cannot account for the highly polarized single pulses observed in pulsars. We suggest coherent curvature radiation as a promising candidate for pulsar radio emission mechanism.

Combining Advanced Photoelectron Spectroscopy Approaches to Analyse Deeply Buried Gap(As)/Si(100) Interfaces: Interfacial Chemical States and Complete Band Energy Diagrams

The epitaxial growth of the polar GaP(100) on the nonpolar Si(100) substrate suffers from inevitable defects at the antiphase domain boundaries, resulting from mono-atomic steps on the Si(100) surface. Stabilization of Si(100) substrate surfaces with arsenic is a promising technological step enabling the preparation of Si substrates with double atomic steps and reduced density of the APDs. In this paper, 4-50 nm thick GaP epitaxial films were grown on As-terminated Si(100) substrates with different types of doping, miscuts, and As-surface termination by metalorganic vapor phase epitaxy. The GaP(As)/Si(100) heterostructures were investigated by X-ray photoelectron spectroscopy (XPS) combined with gas cluster ion beam (GCIB) sputtering and by hard X-ray photoelectron spectroscopy (HAXPES). We found residuals of arsenic atoms in the GaP lattice (0.2-0.3 at.%) and a localization of As atoms at the GaP(As)/Si(100) interface (1 at.%). Deconvolution of core level peaks revealed interface core level shifts. In As core levels, chemical shifts between 0.5-0.8 eV were measured and identified by angle-resolved XPS measurements. Similar valence band offset (VBO) values of 0.6 eV were obtained, regardless of the doping type of Si substrate, Si substrate miscut or type of As-terminated Si substrate surface. The band alignment diagram of the heterostructure was deduced.

Influence of acetabular cup thickness on seating and primary stability intotal hip arthroplasty.

Insufficient primary stability of acetabular hip cups is a complication resulting in early cup loosening. Available cup designs vary in terms of wall thickness, potentially affecting implant fixation. This study investigated the influence of different wall thicknesses on the implantation process and the resulting primary stability using excised human acetabula. Implantations were performed using a powered impaction device providing consistent energy with each stroke. Two different wall thicknesses were compared in terms of seating progress, polar gap remaining after implantation, bone-to-implant contact area, cup deflection, and lever out moment. Thin-walled cups showed higher lever out resistance (p < 0.001) and smaller polar gaps (p < 0.001) with larger bone contact towardthe dome of the cup (p < 0.001) compared to thick-walled cups. Small seating steps at the end of the impaction process were observed if a high number of strokes were needed to seat the cup (p = 0.045). A high number of strokes led to a strain release of the cup during the final strokes (p = 0.003). This strain release is indicative for over-impaction of the cup associated with bone damage and reduced primary stability. Adequate cup seating can be achieved with thin-walled cups with lower energy input in comparison to thicker ones. Thin-walled cups showed improved primary stability and enable implantation with lower energy input, reducing the risk of over-impaction and bone damage. Additional strokes should be avoided as soon as no further seating progress has been observed.

A Controllable Dual Interface Engineering Concept for Rational Design of Efficient Bifunctional Electrocatalyst for Zinc-Air Batteries.

Searching for bifunctional noble-free electrocatalysts with high activity and stability are urgently demanded for the commercial application of zinc-air batteries (ZABs). Herein, the authors propose a controllable dual interface engineering concept to design a noble-metal-free bifunctional catalyst with two well-designed interfaces (Ni3 FeN|MnO and MnO|CNTs) via a simple etching and wet chemical route. The heterointerface between MnO and Ni3 FeN facilitates the charge transfer rate during surface reaction, and heterointerface between MnO and carbon nanotubes (CNTs) support provides effective electron transfer path, while the CNTs matrix builds free diffusion channels for gas and electrolyte. Benefiting from the advantages of dual interfaces, Ni3 FeN/MnO-CNTs show superior oxygen reduction reaction and oxygen evolution reaction catalytic activity with an ultralow polarization gap (∆E) of 0.73V, as well as preferable durability and rapid reaction kinetics. As proof of concept, the practical ZAB with Ni3 FeN/MnO-CNT exhibits high power density of 197mWcm-2 and rate performance up to 40mAcm-2 , as well as superior cycling stability over 600 cycles, outperforming the benchmark mixture of Pt/C and RuO2 . This work proposes a controllable dual interface engineering concept toward regulating the charge, electron, and gas transfer to achieve efficient bifunctional catalysts for ZABs.

Tunability of Structure, Polarization, and Band Gap of High TC Organic–Inorganic Ferroelectrics by Hydrostatic Pressure: First-Principles Study

The effect of hydrostatic pressure in the range of 0–10 GPa on the structural, electric, and electronic properties of hybrid organic–inorganic ferroelectric perovskites TMCM–MnCl3 and TMCM–CdCl3 (TMCM = trimethyl chloromethyl ammonium) is predicted from first-principles density functional theory calculations. These materials differentiate themselves in the family of organic–inorganic ferroelectrics by their unusually high Curie temperature and piezoelectric constants and therefore are of both scientific and technological significance. Computations predict (i) the (co)existence of multiple competing phases with different polarizations and band gaps tunable by the pressure; (ii) the presence of two regions of structural response to pressure and their atomistic origin; (iii) increase of spontaneous polarization of up to 18% (19%) for TMCM–CdCl3 (TMCM–MnCl3) driven by the significant volume decrease under pressure; and (iv) 36% decrease in the band gap of TMCM–MnCl3 and 10% increase in the band gap of TMCM–CdCl3 under 10 GPa.

Determinants of the primary stability of cementless acetabular cup implants: A 3D finite element study

Primary stability of cementless implants is crucial for the surgical success and long–term stability. However, primary stability is difficult to quantify in vivo and the biomechanical phenomena occurring during the press–fit insertion of an acetabular cup (AC) implant are still poorly understood. The aim of this study is to investigate the influence of the cortical and trabecular bone Young's moduli Ec and Et, the interference fit IF and the sliding friction coefficient of the bone–implant interface μ on the primary stability of an AC implant. For each parameter combination, the insertion of the AC implant into the hip cavity and consequent pull–out are simulated with a 3D finite element model of a human hemi–pelvis. The primary stability is assessed by determining the polar gap and the maximum pull–out force. The polar gap increases along with all considered parameters. The pull–out force shows a continuous increase with Ec and Et and a non-linear variation as a function of μ and IF is obtained. For μ > 0.6 and IF > 1.4 mm the primary stability decreases, and a combination of smaller μ and IF lead to a better fixation. Based on the patient's bone stiffness, optimal combinations of μ and IF can be identified. The results are in good qualitative agreement with previous studies and provide a better understanding of the determinants of the AC implant primary stability. They suggest a guideline for the optimal choice of implant surface roughness and IF based on the patient's bone quality.

The Fate of Zone 2 Radiolucencies in Contemporary Highly Porous Acetabular Components: Not All Designs Perform Equally.

BackgroundThe enhanced frictional resistance of modern ultraporous acetabular components can impede complete seating; however, surgeons expect the enhanced ingrowth surface to resolve polar (zone 2) gaps over time via osseointegration. This study characterized zone 2 radiographic osseointegration in 3 acetabular component designs: 2 highly porous ingrowth and one traditional ongrowth.MethodsA consecutive cohort of primary total hip arthroplasties was reviewed which utilized 3 different acetabular cup designs: ongrowth titanium with hydroxyapatite (HA), highly porous titanium with machined radial grooves (MRG), and dual-porous titanium substrate with micropore (MP). Radiographic analysis was performed using accepted measurement criteria with particular attention to radiolucent lines.ResultsSeven hundred ninety cases were available for analysis. Initial 1-month radiographs revealed 43.2% of HA, 78.2% of MRG, and 81.0% of MP cups exhibited zone 2 radiolucencies, consistent with incomplete seating. At 1 year, all HA radiolucencies resolved, whereas 46.2% and 34.7% of radiolucencies remained in MRG and MP cups, respectively (P ≤ .005). At minimum 2 years, a significant proportion of zone 2 radiolucencies remained in 46.0% of MRG compared with 23.9% of MP cups and 3.0% of HA cups (P ≤ .007).ConclusionThe resolution of zone 2 radiolucencies at 1-year and minimum 2-year follow-up signified osseointegration for nearly all HA and most MP cups. Highly porous titanium cups with machined radial grooves demonstrated persistent zone 2 radiolucencies at 1 year and beyond. Given reports of early loosening with this particular acetabular implant, further follow-up is warranted as this study highlights that not all contemporary highly porous metal acetabular components perform equally.Level of EvidenceIII.

Antioxidant Behavior Affected by Polarity in the Olive Oil: Experimental and Molecular Simulation Investigations.

Natural antioxidants are essential potential sources for protecting the oxidation of food oils. However, until now, the mechanisms are still not very clear, especially from the quantitatively theoretical level to analyze the antioxidant behavior. In this work, the micromechanisms of the antioxidant behavior affected by polarity in the olive oil were systematically investigated by experimental and computational methods. The results showed that the polarity of antioxidants decreased with the growth of the alkyl chains, which had multiple impacts on the effectiveness of antioxidants. The excessive polarity gap between the antioxidant and oil molecules would cause the antioxidant to be dispersed at the oil–air interface, which could enhance their antioxidant ability. Meanwhile, the antioxidants with longer alkyl chains had lower polarity and better dispersibility but decreased mobility. Hence, compared with other antioxidants, medium polarity antioxidants presented both good dispersion and relatively suitable migration, indicating that they would have an optimal antioxidant effect.

Enhancing the performance of lithium oxygen batteries through combining redox mediating salts with a lithium protecting salt

Li–O2 batteries have recently emerged to meet nowadays elevated electric energy demands. Redox mediators (RMs) for solution-inducing decomposition of discharge products are one approach to increase energy efficiency and reduce high overpotentials in these batteries. However, multiple obstacles hinder their usage such as redox shuttling, capacity fading, electrolyte degradation, etc. Herein, we present a new chemistry based on a combination of LiNO3, TEGDME and an ionic liquid that enables LiI (1 M) to lower the charge potential (3.5V) with a long cycle life of 270 cycles. 0.1 M LiI increases the cyclability up to 500 with a slightly increased charge potential (~4V) for a fixed capacity of 1000 mAh/g. Up to 100 cycles, this battery system retained ~95% Li2O2 capacity with a ~0.8 V charge-discharge polarization gap. The addition of LiNO3 to the electrolyte provides a protective solid electrolyte interface (SEI) on anode that works in synergy with the LiI RM. Moreover, we found that this electrolyte blend results in domain formation of ionic and neutral species enhancing the discharge and charge processes. Finally, DFT calculations provide a better understanding of the role of the anode SEI layer and the Li2O2 decomposition promoted by the LiI during charge on the cathode.

Analysis of limitations on recovery of gravity field based on satellite gravity gradient data

Although satellite gravity gradient data plays a great role in determining short-wavelength part of static gravity field model, accuracy of the long-wavelength part of gravity field model recovered by them are poor, which leads to only a few applications in time-variable gravity investigation. The reason is that some factors limit the accuracy of the gravity field recovered using gradient data, including accuracy of the gravity gradient observations, measurement bandwidth (MBW) of gradiometer, satellite inclination, etc. This paper aims at analyzing the influence of these limitations on gravity field recovery and discusses the possibility of time-variable gravity field detection by using gravity gradient observations. Firstly, for arbitrary satellite orbit inclination, we give the frequency distributions of all the components of gravity gradients (i.e. Txx,Tyy,Tzz,Txy,TxzandTyz, ). The results show that the maximum frequency of each component of the gravity gradients is the same, i.e. l/Ts (l is degree of the gravity field model, Ts is the orbital periods), and it is not influenced by the inclination of the satellite orbits. Secondly, the paper gives a theory proof to explain why only the low orders of the coefficients are influenced by polar gaps. Big polar gaps are experimented by a numerical test with inclination of 45°. Finally, considering that the measurement bandwidth can be expanded and accuracy of gradient observations can be improved by superconducting gravity gradiometer (SGG) compared to gradiometer used in Gravity field and steady-state Ocean Circulation Explorer (GOCE), the possibility of detecting time-variable gravity using gravity gradient observations is discussed. The results show that the SGG creates errors in MBW with magnitude of 0.014 mE, which is smaller than the magnitude of the time-variable gravity gradient signals (i.e., 0.02 mE) derived from Gravity Recovery and Climate Experiment (GRACE) gravity field models. This indicates the potential of SGG in time-variable gravity detection.