Temporal dynamics of public transportation ridership in Seoul before, during, and after COVID-19 from urban resilience perspective.

We delve into the temporal dynamics of public transportation (PT) ridership in Seoul, South Korea, navigating the periods before, during, and after the COVID-19 pandemic through a spatial difference-in-difference model (SDID). Rooted in urban resilience theory, the study employs micro-level public transportation card data spanning January 2019 to December 2023. Major findings indicate a substantial ridership decline during the severe COVID impact phase, followed by a period in the stable and post-COVID phases. Specifically, compared to the pre-COVID phase, PT ridership experienced a 32.1% decrease in Severe, followed by a reduced magnitude of 21.8% in Stable and 13.5% in post-COVID phase. Interestingly, the observed decrease implies a certain level of adaptability, preventing a complete collapse. Also, contrasting with findings in previous literature, our study reveals a less severe impact, with reductions ranging from 27.0 to 34.9%. Moreover, while the ridership in the post-COVID phase exhibits recovery, the ratio (Post/Pre) staying below 1.0 suggests that the system has not fully returned to its pre-pandemic state. This study contributes to the urban resilience discourse, illustrating how PT system adjusts to COVID, offering insights for transportation planning.

Recent Progress of Advanced Functional Separators in Lithium Metal Batteries.

As a representative in the post-lithium-ion batteries (LIBs) landscape, lithium metal batteries (LMBs) exhibit high-energy densities but suffer from low coulombic efficiencies and short cycling lifetimes due to dendrite formation and complex side reactions. Separator modification holds the most promise in overcoming these challenges because it utilizes the original elements of LMBs. In this review, separators designed to address critical issues in LMBs that are fatal to their destiny according to the target electrodes are focused on. On the lithium anode side, functional separators reduce dendrite propagation with a conductive lithiophilic layer and a uniform Li-ion channel or form a stable solid electrolyte interphase layer through the continuous release of active agents. The classification of functional separators solving the degradation stemming from the cathodes, which has often been overlooked, is summarized. Structural deterioration and the resulting leakage from cathode materials are suppressed by acidic impurity scavenging, transition metal ion capture, and polysulfide shuttle effect inhibition from functional separators. Furthermore, flame-retardant separators for preventing LMB safety issues and multifunctional separators are discussed. Further expansion of functional separators can be effectively utilized in other types of batteries, indicating that intensive and extensive research on functional separators is expected to continue in LIBs.

Iron-containing nanominerals for sustainable phosphate management: A comprehensive review and future perspectives.

Adsorption, which is a quick and effective method for phosphate management, can effectively address the crisis of phosphorus mineral resources and control eutrophication. Phosphate management systems typically use iron-containing nanominerals (ICNs) with large surface areas and high activity, as well as modified ICNs (mICNs). This paper comprehensively reviews phosphate management by ICNs and mICNs in different water environments. mICNs have a higher affinity for phosphates than ICNs. Phosphate adsorption on ICNs and mICNs occurs through mechanisms such as surface complexation, surface precipitation, electrostatic ligand exchange, and electrostatic attraction. Ionic strength influences phosphate adsorption by changing the surface potential and isoelectric point of ICNs and mICNs. Anions exhibit inhibitory effects on ICNs and mICNs in phosphate adsorption, while cations display a promoting effect. More importantly, high concentrations and molecular weights of natural organic matter can inhibit phosphate adsorption by ICNs and mICNs. Sodium hydroxide has high regeneration capability for ICNs and mICNs. Compared to ICNs with high crystallinity, those with low crystallinity are less likely to desorb. ICNs and mICNs can effectively manage municipal wastewater, eutrophic seawater, and eutrophic lakes. Adsorption of ICNs and mICNs saturated with phosphate can be used as fertilizers in agricultural production. Notably, mICNs and ICNs have positive and negative effects on microorganisms and aquatic organisms in soil. Finally, this study introduces the following: trends and prospects of machine learning-guided mICN design, novel methods for modified ICNs, mICN regeneration, development of mICNs with high adsorption capacity and selectivity for phosphate, investigation of competing ions in different water environments by mICNs, and trends and prospects of in-depth research on the adsorption mechanism of phosphate by weakly crystalline ferrihydrite. This comprehensive review can provide novel insights into the research on high-performance mICNs for phosphate management in the future.

On-Demand Transient Paper Substrate for Selective Disposability of Thin-Film Electronic Devices.

This study demonstrates a novel approach to creating a thin-film electronic device that offers selective or complete disposability only in on-demand conditions while maintaining stable operation reliability during everyday use. The approach involves a transient paper substrate, combined with phase change encapsulation and highly bendable planarization materials, achieved through a simple solution process. The substrate used in this study offers a smooth surface morphology that enables the creation of stable multilayers for thin-film electronic devices. It also exhibits superior waterproof properties, which allows the proof-of-concept organic light-emitting device to function even when submerged in water. Additionally, the substrate provides controlled surface roughness under repeated bending, demonstrating reliable folding stability for 1000 cycles at 10 mm of curvature. Furthermore, a specific component of the electronic device can be selectively made to malfunction through predetermined voltage input, and the entire device can be fully disposed of via Joule-heating-induced combustion.

Fiber support prevents colloid-facilitated contamination induced by dissolution-precipitation of a calcium phosphate adsorbent.

During the adsorptive removal of hazardous metal contaminants, dissolution-precipitation of sparingly soluble adsorbents may result in the formation of toxic colloidal suspensions, triggering secondary pollution. Therefore, we studied the prevention of colloid-facilitated contamination in a model adsorption system of dicalcium phosphate dihydrate (DCPD, CaHPO4·2H2O) and Cd2+ as an adsorbent and adsorbate. Upon adding pure DCPD powder into a 500 mg L-1 Cd2+ solution of pH â‰Œ 7.0, aggregates of spheroidal Cd-bearing primary particles, within 0.040-0.95 µm size range, were generated via dissolution-precipitation. The accumulated volume of these submicron particles (10.8%) was greater than that of the submicron particles from the exposure of DCPD to deionized water (4.48%). While the Cd-carrying submicron particles, which are responsible for colloidal recontamination, appeared to form via homogeneous nucleation, their formation was suppressed using polyacrylonitrile fibers (PANFs) as supporting substrates. Thus, heterogeneous nucleation on PANFs formed hexagonal columnar microparticles of a new phase, pentacadmium dihydrogen tetrakis (phosphate) tetrahydrate (Cd5H2(PO4)4·4H2O). Together with dissolution-precipitation on the native DCPD, nucleation and growth on the PANFs accelerated the depletion of the dissolved species, reducing the degree of supersaturation along the DCPD-water interface. Although the PANFs decreased the Cd adsorption capacity to 56.7% of that of DCPD, they prevented the formation of small aggregates of Cd-bearing particles. Other sparingly soluble adsorbents can be compounded with PANF to prevent the generation of toxic colloids.

Leaching of structural Ca2+ ions from a chalcogenide adsorbent by H+ lifts Cs(I) uptake.

Acidic wastewater containing radioactive 137Cs is difficult to treat by selective adsorption. Abundant H+ under acidic conditions damages the structure of adsorbents and competes with Cs+ for adsorption sites. Herein, we designed a novel layered calcium thiostannate (KCaSnS) that contains Ca2+ as a dopant. The dopant Ca2+ ion is metastable and larger than the ions attempted before. The pristine KCaSnS demonstrated a high Cs+ adsorption capacity of 620 mg/g at 8250 mg/L Cs+ solution and pH 2, which is 68% higher than that at pH 5.5 (370 mg/g), a trend opposite to all previous studies. The neutral condition allowed the release of Ca2+ present only in the interlayer (∼20%); whereas the high acidity facilitated the leaching of Ca2+ from the backbone structure (∼80%). The complete structural Ca2+ leaching was made possible only by a synergistic interaction of highly concentrated H+ and Cs+. Doping a large enough ion, such as Ca2+, to accommodate Cs+ into the Sn-S matrix upon its liberation opens a new way of designing high-performance adsorbents.

Dittmarite-type magnesium phosphates for highly efficient capture of Cs.

The presence of cesium ions (Cs+) in radioactive wastewater has attracted considerable attention owing to their extreme toxic effects. Thus, there is an urgent need to develop adsorbents for Cs+ with high adsorption capacities (q). While phosphate-based adsorbents have advantages for their disposal, previous adsorbents have shown limited q because of their limited capacity for ion exchange, despite showing high theoretical q values. In this study, two dittmarite-type magnesium phosphates, KMgPO4·H2O (KMP) and NH4MgPO4·H2O (NMP), were synthesized because of their ability to contain readily exchangeable cations in their interlayers. KMP and NMP demonstrated remarkable adsorption capacities for Cs+ (qeKMP = 630 mg g-1 and qeNMP = 711 mg g-1), which were the highest among all reported adsorbents and are ∼84 % of their theoretical values. Their distribution coefficients in waters with high divalent ion concentrations were low, which limits their use for the adsorption of Cs+ from such environments. After adsorption, KMP and NMP were structurally transformed into struvite-type CsMgPO4·6H2O (CsMP), which has two different stacking structures, either cubic or hexagonal, depending on the pH of the solution. The high q values of KMP and NMP enable them to reduce the volume of radioactive waste for disposal.

Designing a Bimodal BaTiO3 Artificial Layer to Boost the Dielectric Effect toward Highly Reversible Dendrite-Free Zn Metal Anodes.

With the growing interest in suppressing greenhouse gas emissions from fossil fuel combustion, the implementation of electrical energy storage devices for efficiently utilizing renewable energy is expanding worldwide. Zn-ion batteries are attractive for energy storage because of their safety, eco-friendliness, high energy density, and low cost. However, their commercialization is hindered by the poor rechargeability of the zinc anode because of Zn dendrite growth and hydrogen evolution. Herein, we present the application of an artificial layer composed of bimodal BaTiO3 particles on Zn metal to boost the dielectric properties and thus enhance the reversibility of Zn anodes during long-term cycling. The BaTiO3 layer induces electric polarization under external electric fields, causing the Zn ions to move sequentially toward the Zn anode. Moreover, its mechanical characteristics alleviate the volume changes between the BaTiO3 layer and Zn metal. Consequently, Zn dendrite growth is effectively inhibited, and the electrochemical performance is significantly improved in Zn|Zn symmetric cells, resulting in a low overvoltage (39 mV) and stable cycling (800 h) at 1 mA cm-2. Moreover, the Zn-ion full cell using an α-MnO2 cathode exhibits consistent capacity retention up to 380 cycles. This study demonstrates a new strategy to economically and readily suppress dendrite formation by using bimodal dielectric particles as artificial layers to stabilize metal-based batteries.

Highly selective cesium removal under acidic and alkaline conditions using a novel potassium aluminum thiostannate.

The pH values of nuclear wastewater are extremely low or high, which make the efficient removal of 137Cs a major concern among the issues for safety management and environmental remediation. Existing metal sulfides for Cs+ adsorption have shown poor performance at acidic and alkaline conditions, and the reason has not been revealed yet. Herein, a novel potassium aluminum thiostannate (KAlSnS-3) adsorbent was designed and its Cs+ adsorption mechanism over a wide pH range was investigated. We hypothesized that Al3+ dopant on Sn4+ sites would allow stable adsorption for Cs+ upon its partial release at acidic and alkaline conditions. As a result, KAlSnS-3 demonstrated excellent adsorption performance across a broad pH range (1-13), and high selectivity toward Cs+, even under high salinity conditions (in tap water Kd = 3.12 × 104 mL/g; and in artificial seawater Kd = 3.42 × 103 mL/g). KAlSnS-3 also exhibited rapid adsorption kinetics (R = 97.6% in the first minute), a remarkable adsorption capacity (259.31 mg/g), and a high distribution coefficient (2.09 × 105 mL/g) toward Cs+. In addition, the high reusability of KAlSnS-3 was observed, suggesting its potential for real-world applications. The mechanism for enhancing performance at low and high pH values was discussed with the evidence of crystallinity, elemental concentrations, and binding energy of electrons based on the concept of electrostatic interactions and chemical affinity. In summary, this work provides insights into the mechanism of Cs+ removal under a wide pH range, and the impressive Cs+ adsorption performance indicates the application potential of KAlSnS-3 in wastewater treatment.

P-Doped SiOx /Si/SiOx Sandwich Anode for Li-Ion Batteries to Achieve High Initial Coulombic Efficiency and Low Capacity Decay.

Initial reversibility and excellent capacity retention are the key requirements for the success of high-capacity electrode materials in high-performance Li-ion batteries and pose a number of challenges to development. Silicon has been regarded as a promising anode material because of its outstanding theoretical capacity. However, it suffers from colossal volume change and continuous formation of unstable solid electrolyte interphases during lithiation/delithiation processes, which eventually result in low initial Coulombic efficiency (ICE) and severe capacity decay. To circumvent these challenges, a new sandwich Si anode (SiOx /Si/SiOx ) free from prelithiation is designed and fabricated using a combination of P-doping and SiOx layers. This new anode exhibits high conductivity and specific capacity compared to other Si thin-film electrodes. Cells with SiOx /Si/SiOx anodes deliver the highest presently known ICE value among Si thin-film anodes of 90.4% with a charge capacity of 3534 mA h g-1 . In addition, the SiOx layer has sufficient mechanical stability to accommodate the large volume change of the intervening Si layer during charge-discharge cycling, exhibiting high potential for practical applications of Si thin-film anodes.

Posterior scoliosis correction with thoracoplasty: effect on pulmonary function with a mean follow-up of 4.8 years.

PURPOSE: To perform a study to investigate the influence of posterior scoliosis surgery and thoracoplasty on pulmonary function. METHODS: This was a retrospective observational study of 37 patients with AIS who underwent posterior instrumented surgical correction with thoracoplasty. There was a minimum of 2 years follow-up. Clinical outcomes were measured using the SRS-22 questionnaires. Radiological outcomes were evaluated using standing posteroanterior and lateral radiographs. All patients had pulmonary function tests to evaluate pulmonary volume and flow (forced expiratory volume in the first second (FEV1) and forced vital capacity (FVC)) both before surgery and at the final follow-up. RESULTS: There were three males and 34 females. The mean age of patients was 14.6 years (range 11-21 years). The mean length of follow was 58 months (range 24-124 months). The average main thoracic Cobb angle in the coronal plane was corrected from 50.0° ± 12.4° preoperatively to 16.6° ± 6.3° postoperatively. The average thoracolumbar Cobb angle in the coronal plane was corrected from 28.2° ± 10.6° preoperatively to 10.1° ± 7.2°. The average thoracic kyphosis angle was corrected from 17.4° ± 11.0° preoperatively to 21.8° ± 10.5°. In terms of the Quality of life Outcomes (QoL), there was a significant increase (p < 0.001) in the mean SRS 22 scores from 3.8 preoperatively to 4.3 postoperatively. A statistically significant increase in the absolute forced expiratory volume in one second (FEV1) from pre-operative values with a p value < 0.001 was seen. There was a statistically significant increase in percentage predicted forced expiratory volume in one second from preoperative values with a p value of 0.008. There was also a statistically significant increase in the absolute forced vital capacity (FVC) from preoperative values with a p value < 0.001. The average percentage predicted forced vital capacity did increase on final follow-up from before surgery, but the increase was not statistically significant. CONCLUSIONS: We have demonstrated that pulmonary function post-thoracoplasty not only reaches pre-operative levels, but significantly surpasses it with regards to the majority of the pulmonary parameters measured in this study. We also demonstrated satisfactory radiological correction and clinical outcomes.

Efficient adsorptive removal of Cobalt(II) ions from water by dicalcium phosphate dihydrate.

Although the radionuclide 60Co is widely used, its presence in various effluents demands its removal to preclude environmental pollution and detrimental effects on human health. This study investigated the batch adsorption performance of a potential cobalt adsorbent, dicalcium phosphate dihydrate (DCPD), in immobilizing Co2+ from water. The influences of solution pH, contact time, initial concentration, and competing cations were examined and discussed. Stable cobalt uptake was observed at pH 4-8. The sorption kinetics showed a multi-stage uptake profile, implying that several mechanisms are involved in the adsorption process. Microscopy and structural analysis revealed that DCPD decomposes to its anhydrous form during adsorption, which explains the multistep curve over the entire adsorption period. However, the non-apatitic transformation is not exclusive to cobalt uptake. Intraparticle diffusion also contributed to the overall removal kinetics of Co2+ from water. Considering the Sips isotherm model, the maximum Co2+ adsorption capacity of DCPD was 441 mg g-1. Cobalt uptake selectivity dropped in the presence of Ca2+ ions, from 1.21 × 104 to 207 mL g-1, indicating DCPD would be more applicable in treating soft 60Co-contaminated waters. Structural analysis, elemental mapping, and qualitative analysis of solid residues confirmed that ion exchange is involved in the removal of cobalt from aqueous solutions.

Caesium adsorption on a zeolitic imidazolate framework (ZIF-8) functionalized by ferrocyanide.

137Cs is one of the most hazardous radionuclides in nuclear waste owing to its toxicity. Developing an adsorbent for Cs+ with a high capacity and selectivity is a challenging task. A metal-organic framework (MOF) is a material with a high surface area that has been widely applied in wastewater treatment. Exploiting the affinity between ferrocyanide (FC) and Cs+, zeolitic imidazolate framework-8 (ZIF-8) was chemically functionalized with FC, ZIF-8-FC to selectively capture Cs+. After functionalization, ZIF-8-FC has a hollow morphology and small FC related crystals, which might result in better migration of Cs+ inside ZIF-8-FC. This synergistic effect was proven by the Qmax of ZIF-8-FC, 422.42 mg g-1, which is 15.9 times higher than that of ZIF-8. Additionally, ZIF-8-FC retained its good adsorption performance within a pH range of 3-11 and an excellent Cs+ selectivity even in artificial seawater conditions. The structure of ZIF-8-FC after adsorption proves its stability. Furthermore, the thermodynamic adsorption implied that higher temperatures are more favorable for Cs+ uptake. This work demonstrates the remarkable adsorption and selectivity of ZIF-8-FC, which make it a promising candidate for remediation of radioactive Cs+.

Rapid and selective removal of Cs+ from water by layered potassium antimony thiostannate.

137Cs is radioactive and highly hazardous to human health and the environment and its efficient removal from water is still challenging. In this study, potassium antimony tin sulfide (KATS-2) was synthesized using a hydrothermal method and utilized for the first time for cesium removal from water. KATS-2 showed a high maximum ion exchange capacity (358 mg g-1) and distribution coefficient (1.59 × 105 mL g-1) toward Cs+. In particular, KATS-2 showed rapid ion exchange kinetics and reached the adsorption equilibrium within 5 min with 99% removal efficiency. The adsorption was good at a wide active pH range (1-12) even in extreme alkaline conditions (Kd = 3.26 × 104 mL g-1 at pH 12). The effect of coexisting ions was also investigated, and a high selectivity toward Cs+ was maintained even in artificial seawater (Kd = 3.28 × 103 mL g-1). Powder X-ray diffraction and thermogravimetric analysis demonstrated that KATS-2 was chemically and thermally stable. The results showed that owing to its excellent adsorption performance as well as chemical and thermal stability, KATS-2 is a promising adsorbent for Cs+ removal from contaminated water.

Brushite-infused polyacrylonitrile nanofiber adsorbent for strontium removal from water.

The Fukushima Daiichi nuclear disaster and the decommissioning of over a hundred nuclear reactors worldwide led to the increase in the demand for efficient water treatment technologies to remove radionuclides, such as 90Sr. Brushite or dicalcium phosphate dihydrate (DCPD) is a potential adsorbent to remove strontium from water. In this study, composite poly(acrylonitrile) (PAN) nanofiber (NF) adsorbents with DCPD (PAN/DCPD) were prepared, characterized, and investigated for strontium adsorption in water. Material characterization revealed mechanically suitable, hydrophilic, and macroporous composite NF adsorbents with average fiber diameters of <500 nm. As-prepared DCPD powder exhibited a superior strontium uptake capacity of 81.7 mg g-1 at pH â‰… 10 of aqueous Sr2+ solution over its biogenic and synthetic predecessor, hydroxyapatite. Increased DCPD loading resulted in higher adsorption. Maximum Sr2+ uptake of PAN/DCPD NF with 70 wt% DCPD loading (PAN/70DCPD NF) was 146 mg g-1 considering the Sips isotherm model. Kinetic studies revealed that Sr2+ removal by PAN/DCPD NF was a chemisorption process which involved ion exchange and surface complexation. PAN/70DCPD NF as a dead-end membrane filter exhibited superior removal efficiency over pure PAN NF. The overall results of this study revealed the potential application of PAN/DCPD NF adsorbent for 90Sr removal from water.

Delamination-Free Multifunctional Separator for Long-Term Stability of Lithium-Ion Batteries.

Next-generation lithium-ion batteries (LIBs) that satisfy the requirements for an electric vehicle energy source should demonstrate high reliability and safety for long-term high-energy-density operation. This inevitably calls for a novel approach to advance major components such as the separator. Herein, a separator is designed and fabricated via application of multilayer functional coating on both sides of a polyethylene separator. The multilayer-coated separator (MCS) has a porous structure that does not interfere with lithium ion diffusion and exhibits superior heat resistance, high electrolyte uptake, and persistent adhesion with the electrode. More importantly, it enables high capacity retention and reduced impedance build up during cycling when used in a coin or pouch cell. These imply its promising application in energy sources requiring long-term stability. Fabrication of the MCS without the use of organic solvents is not only environmentally beneficial but also effective at cost reduction. This approach paves the way for the separator, which has long been considered an inactive major component of LIBs, to become an active contributor to the energy density toward achieving longer cycle stability.

Removal of Sr2+ using high-surface-area hydroxyapatite synthesized by non-additive in-situ precipitation.

Owing to their high-risk factor, many attempts have been made to remove radionuclides from water. Sr2+ ions are the target of removal by synthesized hydroxyapatite in this research. A facile method for synthesizing high-surface-area hydroxyapatite by in-situ precipitation using excess diammonium phosphate solution and without any additive was developed. The highest surface area achieved using this method was 177.00 m2/g, and the synthesized hydroxyapatite was also mesoporous. The effects of different pH, temperatures, and ion concentrations during synthesis on the properties of the hydroxyapatite were assessed, and it was found that a low temperature and high pH were optimal for synthesizing high-surface-area hydroxyapatite. The maximum strontium removal capacity of 28.51 mg/g was achieved when the pH-7.5 solution was used. This performance is competitive in comparison with previously developed synthesized materials. Synthesized hydroxyapatite could effectively remove radioactive strontium from an aqueous solution for nuclear waste management.

Effect of nanopatterning on mechanical properties of Lithium anode.

One of the challenges in developing Lithium anodes for Lithium ion batteries (LIB) is controlling the formation of Li dendrites during cycling of the battery. Nanostructuring and nanopatterning of electrodes shows a promising way to suppress the growth of Li dendrites. However, in order to control this behavior, a fundamental understanding of the effect of nanopatterning on the electro-mechanical properties of Li metal is necessary. In this paper, we have investigated the mechanical and wear properties of Li metal using Atomic Force Microscopy (AFM) in an airtight cell. By using different load regimes, we determined the mechanical properties of Li metal. We show that as a result of nanopatterning, Li metal surface underwent work hardening due to residual compressive stress. The presence of such stresses can help to improve cycle lifetime of LIBs with Li anodes and obtain very high energy densities.

Anammox biomass carrying efficiency of polyethylene non-woven sheets as a carrier material.

To access the effects of the surface modification and fabric structure of polyethylene (PE) non-woven fabric sheets on retaining the attachment efficiency of anammox biomass, three different non-woven sheets were prepared and inserted in an anammox reactor. The hydrophobic surface modification with 10% KMnO4 and gelatin did not improve the attachment efficiency of the anammox biomass on the surface of the PE non-woven fibers. Densely packed PE-755 having the highest specific surface area to volume ratio (SA/V) (755) retained 221.4 mg biomass per unit sheet, whereas PE-181 having the lowest SA/V (181) retained only 66.4 mg biomass per unit. Accordingly, the volumetric anammox activity of non-woven sheet PE-755 was the highest among the three PE non-woven sheets because of the strong positive relationship between the specific anammox activity and biomass amount (R = 0.835, P < .01). The specific surface area to volume ratio (cm2 cm-3) as well as the bulk density should be considered as important parameters for the selection of non-woven biocarriers for anammox biomass.

Direct Anterior Approach Using Navigation Improves Accuracy of Cup Position Compared to Conventional Posterior Approach.

The accuracy of cup position in total hip arthroplasty is essential for a satisfactory result as malpositioning increases the risk of complications including dislocation, high wear rate, loosening, squeaking, edge loading, impingement and ultimately failure. We studied 166 patients in a single-surgeon-series of matched cohorts of patients who underwent total hip arthroplasties. Four separate groups were identified comprising of the posterior approach +/- navigation and the direct anterior approach +/- navigation. We found a significant difference between the direct anterior navigated group and the posterior non-navigated group for both anteversions (P < 0.05, confidence interval (CI) -3.86 to -1.73) and inclination (P < 0.05, CI -3.08 to -1.08). Almost, 72% of anterior navigated patients fell within 5o of the navigation software set target cup position of 45o inclination and 20o anteversion and 100% were within 10o. Only 30% of posterior non-navigated were within 5o of both anteversion and inclination and 73% were within 10o. There was also a significant difference between the direct anterior navigated and non-navigated group with respect to anteversion only (p < 0.05, CI 1.50 to 1.30). There were no other significant differences between approaches +/- navigation. The direct anterior approach allows ease of access to both anterior-superior iliac spines for navigation and a supine patient allows anteversion and inclination to be measured in the frontal plane. We conclude that the direct anterior approach with navigation improves the accuracy of cup position compared to the conventional posterior approach without navigation.