Modulating the d-Band Center of RuO2 via Ni Incorporation for Efficient and Durable Li-O2 batteries

Rechargeable Li-O2 batteries (LOBs) are considered as one of the most promising candidates for new-generation energy storage devices. One of major impediments is the poor cycle stability derived from the sluggish reaction kinetics of unreliable cathode catalysts, hindering the commercial application of LOBs. Therefore, the rational design of efficient and durable catalysts is critical for LOBs. Optimizing surface electron structure via the negative shift of the d-band center offers a reasonable descriptor for enhancing the electrocatalytic activity. In this study, the construction of Ni-incorporating RuO2 porous nanospheres is proposed as the cathode catalyst to demonstrate the hypothesis. Density functional theory calculations reveal that the introduction of Ni atoms can effectively modulate the surface electron structure of RuO2 and the adsorption capacities of oxygen-containing intermediates, accelerating charge transfer between them and optimizing the growth pathway of discharge products. Resultantly, the LOBs exhibit a large discharge specific capacity of 19658 mA h g-1 at 200 mA g-1 and extraordinary cycle life of 791 cycles. This study confers the concept of d-band center modulation for efficient and durable cathode catalysts of LOBs.

Interfacial Engineering of MoS2/V2O3@C-rGO Composites with Pseudocapacitance-Enhanced Li/Na-Ion Storage Kinetics

Molybdenum sulfide has been widely investigated as a prospective anode material for Li+/Na+ storage because of its unique layered structure and high theoretical capacity. However, the enormous volume variation and poor conductivity limit the development of molybdenum sulfide. The rational design of a heterogeneous interface is of great importance to improve the structure stability and electrical conductivity of electrode materials. Herein, a high-temperature mixing method is implemented in the hydrothermal process to synthesize the hybrid structure of MoS2/V2O3@carbon-graphene (MoS2/V2O3@C-rGO). The MoS2/V2O3@C-rGO composites exhibit superior Li+/Na+ storage performance due to the construction of the interface between the MoS2 and V2O3 components and the introduction of carbon materials, delivering a prominent reversible capacity of 564 mAh g-1 at 1 A g-1 after 600 cycles for lithium-ion batteries and 376.3 mAh g-1 at 1 A g-1 after 450 cycles for sodium-ion batteries. Theoretical calculations confirm that the construction of the interface between the MoS2 and V2O3 components can accelerate the reaction kinetics and enhance the charge-ionic transport of molybdenum sulfide. The results illustrate that interfacial engineering may be an effective guide to obtain high-performance electrode materials for Li+/Na+ storage.

Piezo-photocatalytic properties of BaTiO3/CeO2 nanoparticles with heterogeneous structure synthesized by a gel-assisted hydrothermal method

BaTiO3/CeO2 nanoparticles with heterogeneous structure were successfully synthesized via a gel-assisted hydrothermal method. The molar ratio of Ti/Ce was set as 1 : 0, 0.925 : 0.075, 0.9 : 0.1; 0.875 : 0.125, and 0.85 : 0.15 in the dried gels. Affected by the values of Ti/Ce, the particle sizes of hydrothermal products decreased obviously, and the surface of nanoparticles became rough and even had small protrusions. XRD, SEM, HRTEM, XPS, DRS, ESR, and PFM were used to characterize the nanoparticle textures. We speculated that the main body and surface of nanoparticles were BaTiO3 and CeO2 protrusions, respectively. The catalytic performance of BaTiO3/CeO2 nanoparticles was characterized by their abilities to degrade RhB in water under different external conditions (light irradiation, ultrasonic oscillation, or both). In all test groups, BaTiO3/CeO2 nanoparticles with a Ti/Ce molar ratio of 0.875 : 0.125 in the initial dried gel exhibited the strongest catalytic ability when light irradiation and ultrasonication were applied simultaneously owing to the appropriate amount of Ce3+ and oxygen vacancies.

Efficient Fe3C-CF Cathode Catalyst Based on the Formation/Decomposition of Li2-xO2 for Li-O2 Batteries

Lithium-oxygen batteries have attracted considerable attention in the past several years due to their ultra-high theoretical energy density. However, there are still many serious issues that must be addressed before considering practical applications, including the sluggish oxygen redox kinetics, the limited capacity far from the theoretical value, and the poor cycle stability. This study proposes a surface modification strategy that can enhance the catalytic activity by loading Fe₃C particles on carbon fibers, and the microstructure of Fe₃C particle-modified carbon fibers is studied by multiple materials characterization methods. Experiments and density functional theory (DFT) calculations show that the discharge products on the Fe₃C carbon fiber (Fe₃C-CF) cathode are mainly Li_2-xO₂. Fe₃C-CF exhibits high catalytic ability based on its promotion of the formation/decomposition processes of Li_2-xO₂. Consequently, the well-designed electrode catalyst exhibits a large specific capacity of 17,653.1 mAh g^-1 and an excellent cyclability of 263 cycles at a current of 200 mA g^-1.

Highly Stable Garnet Fe2 Mo3 O12 Cathode Boosts the Lithium-Air Battery Performance Featuring a Polyhedral Framework and Cationic Vacancy Concentrated Surface

Lithium-air batteries (LABs), owing to their ultrahigh theoretical energy density, are recognized as one of the next-generation energy storage techniques. However, it remains a tricky problem to find highly active cathode catalyst operating within ambient air. In this contribution, a highly active Fe₂ Mo₃ O₁₂ (FeMoO) garnet cathode catalyst for LABs is reported. The experimental and theoretical analysis demonstrate that the highly stable polyhedral framework, composed of FeO octahedrons and MO tetrahedrons, provides a highly effective air catalytic activity and long-term stability, and meanwhile keeps good structural stability. The FeMoO electrode delivers a cycle life of over 1800 h by applying a simple half-sealed condition in ambient air. It is found that surface-rich Fe vacancy can act as an O₂ pump to accelerate the catalytic reaction. Furthermore, the FeMoO catalyst exhibits a superior catalytic capability for the decomposition of Li₂ CO₃ . H₂ O in the air can be regarded as the main contribution to the anode corrosion and the deterioration of LAB cells could be attributed to the formation of LiOH·H₂ O at the end of cycling. The present work provides in-depth insights to understand the catalytic mechanism in air and constitutes a conceptual breakthrough in catalyst design for efficient cell structure in practical LABs.

A228 SAFETY AND EFFICACY OF ENDOSCOPIC RESECTION OF NON-AMPULLARY DUODENAL POLYPS AND RISK OF POLYP RECURRENCE

Background

Non-ampullary duodenal adenomas, which can present sporadically or in the context of a polyposis syndrome, carry a risk of progression to carcinoma in a similar sequence to colorectal adenomas. Complete endoscopic resection is recommended as first line as a less invasive alternative to surgical rsection. Identifying recurrence rates of non-ampullary duodenal polyps after endoscopic resection, and patient and polyp characteristics associated with recurrence is important in determining the best method of resection and guiding endoscopic surveillance.

Purpose

To determine the technical success rate of endoscopic resection of non-ampullary duodenal polyps, complication rates, rate of residual and recurrent polyps, and identify factors associated with polyp recurrence.

Method

All adult patients (≥18 years) that underwent endoscopic resection of non-ampullary duodenal polyps at St. Michael’s Hospital, a Canadian tertiary referral center, from January 2010 to June 2021 were retrospectively identified. Descriptive statistics were calculated for variables of interest and Chi-square, t-test or U-Mann Whitney tests were used to compare variables as appropriate. Bi-variate regression analysis was utilized to determine co-variables associated with recurrence.

Result(s)

A total of 300 patients underwent endoscopic resection of duodenal polyps. Table 1 describes patient demographics, polyp and procedural characteristics and characteristics associated with recurrence. Nearly all cases were technically successful (96%, n=286/299). Clinically significant intraprocedural bleeding occurred in 22% (n=65/300) of patients, and deep mural injury occurred in 3% (n=7/284) of patients. Delayed post-procedural bleeding occurred in 9% of patients (n=26/279). The median time to first surveillance EGD was 4 months. Polyp recurrence occurred in 28% (n=50/180) of patients. Of the patients with polyp recurrence, 82% (n=42/50) were successfully managed endoscopically. On univariate analysis, polyp size (OR 1.03, 95% CI 1.01-1.06), piecemeal resection (OR 1.63, 95% CI 0.17-0.82), intraprocedural bleeding (OR 2.28, 95% CI 1.09-4.74), and high-grade dysplasia (HGD) or intramucosal adenocarcinoma (IMCa) on final histology (OR 3.46, 95% CI 1.64-7.33) were significantly associated with polyp recurrence. On multivariate analysis, only HGD/IMCa on final histology was significant (OR 3.41, 95% CI 1.38-8.47).

Image

Conclusion(s)

Endoscopic resection of duodenal polyps can be safely performed with high technical success, however recurrence is a significant concern. Advanced histology was a significant predictor of polyp recurrence and highlights the importance of accurate pre-resection endoscopic characterization to correctly identify lesions at increased risk that may benefit from alternative resection methods such as ESD or hot rather than cold EMR, and which may require closer follow-up. Future work to develop predictive models of recurrence are needed to better stratify patient risk.

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None

Disclosure of Interest

None Declared

Oxidation of tetracycline hydrochloride with a photoenhanced MIL-101(Fe)/g-C3N4/PMS system: Synergetic effects and radical/nonradical pathways

MIL-101(Fe)-based catalysts have been widely used for degradation of organic pollutants based on peroxymonosulfate (PMS) activation. Hence, a facile calcination and hydrothermal method was used in this study to prepare a MIL-101(Fe)/g-C₃N₄ composite catalyst with high activity and high stability for PMS activation to degrade tetracycline hydrochloride (TC) under visible-light irradiation. We clearly elucidated the mechanism involved in the MIL-101(Fe)/g-C₃N₄ photo Fenton-catalyzed PMS activation process by separating the PMS activation and pollutant oxidation processes. The synergetic effects of MIL-101(Fe) and g-C₃N₄ involved MIL-101(Fe) acting as an electron shuttle mediating electron transfer from the organic substrate to PMS, accompanied by redox cycling of the surface Fe(II)/Fe(III). Multiple experimental results indicated that PMS was bound to the surface of MIL-101(Fe)/g-C₃N₄ during visible irradiation and generation of sulfate radicals (SO₄^•-), hydroxyl radicals (•OH) and superoxide anion free radicals (•O₂^-) for the radical pathway and singlet oxygen (¹O₂) and holes (h⁺) for the nonradical pathway. The major degradation pathways for TC can be described as demethylation, deamination, deamidation and carbonylation. This work provides valuable information and advances the fundamental understanding needed for design and syntheses of metal-free conjugated polymers modified by metal-organic frameworks for heterogeneous photo-Fenton reactions.

Efficient Degradation of Congo Red in Water by UV-Vis Driven CoMoO4/PDS Photo-Fenton System

In order to improve the catalytic activity of cobalt molybdate (CoMoO₄), a PDS-activated and UV-vis assisted system was constructed. CoMoO₄ was prepared by coprecipitation and calcination, and characterized by XRD, FTIR, Raman, SEM, TEM, XPS, TGA Zeta potential, BET, and UV-Vis DRS. The results showed that the morphology of the CoMoO₄ nanolumps consisted of stacked nanosheets. XRD indicated the monoclinic structures with C2/m (C³_2h, #12) space group, which belong to α-CoMoO₄, and both Co²⁺ and Mo⁶⁺ ions occupy distorted octahedral sites. The pH of the isoelectric point (pHIEP) of CMO-8 at pH = 4.88 and the band gap of CoMoO₄ was 1.92 eV. The catalytic activity of CoMoO₄ was evaluated by photo-Fenton degradation of Congo red (CR). The catalytic performance was affected by calcination temperature, catalyst dosage, PDS dosage, and pH. Under the best conditions (0.8 g/L CMO-8, PDS 1 mL), the degradation efficiency of CR was 96.972%. The excellent catalytic activity of CoMoO₄ was attributed to the synergistic effect of photo catalysis and CoMoO₄-activated PDS degradation. The capture experiments and the ESR showed that superoxide radical (·O₂^-), singlet oxygen (¹O₂), hole (h⁺), sulfate (SO₄^-·), and hydroxyl (·OH^-) were the main free radicals leading to the degradation of CR. The results can provide valuable information and support for the design and application of high-efficiency transition metal oxide catalysts.

A169 PRICE: PREVENTING READMISSIONS IN IBD CENTRES OF EXCELLENCE

Background

Hospital readmission rates are high in the inflammatory bowel disease (IBD) population, with 20% of patients readmitted within the same year. Discharge processes are not routinely standardized and deficiencies in transition of care puts patients at an increased risk of recurrent illness and healthcare costs. In addition, hospitalizations for IBD patients are associated with nosocomial complications such as venous thromboembolism.

Aims

We hypothesize that standardized follow-up by an IBD practice nurse and electronic health outcome monitoring reduces the risk of hospital readmission compared to current approaches of hospital discharge alone.

Methods

This pilot study uses a prospective parallel randomized control design and includes patients admitted with an IBD flare who were discharged without surgical intervention. Patients randomized to the control arm were discharged with usual standard of care (i.e. discharge summary and/or follow-up). In addition to standard of care, those in the intervention group received organized telephone or email follow-up by an IBD practice nurse at 1, 7 and 30 days post-discharge. These patients also received bi-weekly corespondence from an electronic survey tool, NoviSurvey, to determine clinical disease severity and medication adherence. Based on patient interactions and survey responses, the IBD nurse may arrange for expedited ambulatory visit or readmission for high-risk patients.

Results

At present, 41 patients have been enrolled into our study, 4 of which were excluded due to surgical management. 19 patients were randomized to the intervention and 17 to the control group. In the intervention group, the 30-day cumulative rate of readmission [0/19 (0%) vs. 4/17 (24%), p = 0.040] as well as the proportion of patients who failed to taper steroids [0/18 (0%) vs. 5/15 (33%), p = 0.013] was significantly lower when compared to the control group. There were no occurrences of deep vein thrombosis within 30 days post-discharge in either group.

Conclusions

These findings in our pilot study indicate that a nurse led post-discharge intervention may translate to benefits including decreased readmission rates and better medication adherence, warranting a large clinical trial to confirm findings.

Patient Demographics and Clinical Outcomes Between Intervention and Control Groups

Funding Agencies

CAG, CCC

MnCo2 S4 -CoS1.097 Heterostructure Nanotubes as High Efficiency Cathode Catalysts for Stable and Long-Life Lithium-Oxygen Batteries Under High Current Conditions

Constructing the heterostructures is considered to be one of the most effective methods to improve the poor electrical conductivity and insufficient electrocatalytic properties of metal sulfide catalysts. In this work, MnCo2 S4 -CoS1.097 nanotubes are successfully prepared via a reflux- hydrothermal process. This novel cathode catalyst delivers high discharge/charge specific capacities of 21 765/21 746 mAh g-1 at 200 mA g-1 and good rate capability. In addition, a favorable cycling stability with a fixed specific capacity of 1000 mAh g-1 at high current density of 1000 mA g-1 (167 cycles) and 2000 mA g-1 (57 cycles) are delivered. It is proposed that fast transmission of ions and electrons accelerated by the built-in electric field, multiple active sites from the heterostructure, and nanotube architecture with large specific surface area are responsible for the superior electrochemical performance. To some extent, the rational design of this heterostructured metal sulfide catalyst provides guidance for the development of the stable and efficient cathode catalysts for Li-O2 batteries that can be employed under high current conditions.

Intrinsic Defects in LiMn2O4: First-Principles Calculations

Spinel LiMn₂O₄ has attracted wide attention due to its advantages of a high-voltage plateau, good capacity, environmental friendliness, and low cost. Due to different experimental synthesis methods and conditions, there are many intrinsic point defects in LiMn₂O₄. By means of first-principles calculations based on a reasonable magnetic configuration, we studied the formation energies, local structures, and charge compensation mechanism of intrinsic point defects in LiMn₂O₄. The formation energies of defects under the assumed O-rich equilibrium conditions were examined. It was found that O, Li, and Mn vacancies, Mn and Li antisites, and Li interstitial could appear in the lattice at some equilibrium conditions, but Mn interstitial is hard to form. The charge was compensated mainly by adjusting the oxidation state of Mn around the defect, except for the defects at the 8a Wyckoff site. The binding energies between point defects were calculated to shed light on the clustering of point defects. Furthermore, the diffusion of Li ions around the defects was discussed. Cation antisites led to a decrease of the Li diffusion barrier but O vacancy caused an increase of the barrier. This study provides theoretical support for understanding point defects in spinel LiMn₂O₄.

First-principles study of Mn antisite defect in Li2MnO3

Lithium-rich layered Li₂MnO₃is regarded as a new generation cathode material for lithium-ion batteries because of its high energy density. Due to the different preparation methods and technological parameters, there are a lot of intrinsic defects in Li₂MnO₃. One frequently observed defect in experiments is Mn antisite defect (Mn_Li). In this work, we study the energetics and electronic properties involving Mn_Liin Li₂MnO₃through first-principles calculations. We find that Mn_Lican reduce the formation energy of Li vacancies around it, but increase that of O vacancies, indicating that Mn_Licould suppress the release of O around it and facilitate capacity retention. Both O and Mn near the Mn_Lican participate in charge compensation in the delithiation process. Furthermore, the effect of Mn_Lion the migration of Li and Mn is investigated. All possible migration paths are considered and it is found that Mn_Limakes the diffusion energy barrier of Li increased, but the diffusion energy barriers of Mn from transition metal layer to Li layer are decreased, especially for the migration of the defect Mn. The insight into the defect properties of Mn_Limakes further contribution to understand the relationship between intrinsic defects and electrochemical properties of Li₂MnO₃.

Insights into Ion Occupancy Manipulation of Fe-Co Oxide Free-Standing Cathodes for Li-O2 Batteries with Enhanced Deep Charge Capability and Long-Term Capability

The merits of Li-O₂ batteries due to the huge energy density are shadowed by the sluggish kinetics of oxygen redox and massive side reactions caused by conductive carbon and a binder. Herein, Fe-Co inverse spinel oxide nanowires grown on Ni foam are fabricated as carbon-free and binder-free cathodes for Li-O₂ batteries. Superior high rate cycle durability and deep charge capability are obtained. For example, 300 cycles with a low overpotential under a fixed capacity of 500 mAh g^-1 are achieved at a high current density of 500 mA g^-1. In the deep discharge/charge mode at 500 mA g^-1, the optimized Fe-Co oxide cathode can stably work for more than 30 cycles with the capacity maintained at about 2100 mAh g^-1. Owing to the appreciable incorporation of Fe³⁺ into the surface of stable inverse spinel oxides, the regulated Fe-Co oxide cathodes possess a more stable and higher ratio of Co³⁺/Co²⁺, which offers improved adsorption ability of reactive oxygen intermediates and thus achieves the enhanced electrocatalytic performance in the higher current density. In addition, the morphology evolution from array to pyramid-like structure of nanowires further provides assurance in the superior cycle capability. By coupling pyramid-shaped nanowires with binary inverse spinel, the obtained Fe-Co oxide becomes a promising material for practical applications in Li-O₂ batteries. This work offers a general strategy to design efficient mixed metal oxide-based electrodes for the critical energy storage fields.

Suppressed polarization by epitaxial growth of SrTiO3 on BaTiO3 nanoparticles for high discharged energy density and efficiency nanocomposites

In order to meet the increasing demand of integration and miniaturization of electronic components, capacitors with high energy density are urgently needed. In this work, a strategy of suppressing interfacial polarization for obtaining enhanced energy density and efficiency polymer based nanocomposites is proposed. This strategy is conducted by epitaxial growth of a SrTiO₃ layer with a moderate dielectric constant on the surface of a BaTiO₃ core to form a kind of novel filler and compositing with the P(VDF-HFP) matrix to prepare dielectric nanocomposites. The SrTiO₃ shell could effectively confine the mobility of charge carriers to enhance the dielectric strength of the composites and improve the energy efficiency by reducing the Maxwell-Wagner-Sillars (MWS) interfacial polarization and space charge polarization between the BaTiO₃@SrTiO₃ fillers and the P(VDF-HFP) matrix due to their similar crystal structure and lattice parameter. The nanocomposite containing 1 vol% BaTiO₃@SrTiO₃ nanoparticles achieved a discharged energy density of 13.89 J cm^-3 and an energy efficiency of 63% at 494.7 kV mm^-1, which are superior to 9.96 J cm^-3 and 50% of BaTiO₃/P(VDF-HFP) nanocomposites with the same loading, respectively, and its discharged energy density is 69% higher than 8.2 J cm^-3 of the neat P(VDF-HFP) at 401.5 kV mm^-1. This work provides an effective way for nanocomposite capacitors with high energy density and efficiency.

Interfacial Superassembly of Grape-Like MnO-Ni@C Frameworks for Superior Lithium Storage

Despite the excellent electrochemical performance of MnO-based electrodes, a large capacity increase cannot be avoided during long-life cycling, which makes it difficult to seek out appropriate cathode materials to match for commercial applications. In this work, a grape-like MnO-Ni@C framework from interfacial superassembly with remarkable electrochemical properties was fabricated as anode materials for lithium-ion batteries. Electrochemical analysis indicates that the introduction of Ni not only contributes to the excellent rate capability and high specific capacity but also prevents further oxidation of MnO to the higher valence states for ultrastable long-life cycling performance. Furthermore, thermodynamic calculation proves that the ultrastable long cycling life of the Ni-Mn-O system originated from a buffer composition region to stabilize the MnO structure. Because of the unique grape-like structure and performance of the Ni-Mn-O system, the MnO-Ni@C electrode displayed an invertible specific capacity of 706 mA h g^-1 after 200 cycles at a current density of 0.1 A g^-1 and excellent cycling stability maintained a capacity of 476.8 mA h g^-1 after 2100 cycles at 1.0 A g^-1 without obvious capacity change. This new nanocomposite material could offer a novel fabrication strategy and insight for MnO-based materials and other metal oxides as anodes for improved electrochemical performance.

A241 PRICE: PREVENTING READMISSIONS IN IBD CENTRES OF EXCELLENCE

Background

Hospital readmission rates are high in the IBD population, with 20% of patients readmitted within the same calendar year. Hospital discharge processes are not routinely standardized and deficiencies in the transition of care after discharge puts patients at increased risk of illness, hospital utilization and healthcare cost. In addition to increased healthcare expenditure, hospitalizations for IBD patients are associated with nosocomial complications such as venous thromboembolism and infection.

Aims

We hypothesize that implementing standardized follow-up by an IBD practice nurse and electronic health outcome monitoring through NoviSurvey can reduce the risk of hospital readmission compared to current approaches of hospital discharge alone.

Methods

This parallel randomized control trial is powered for N=400 and will include patients admitted for an IBD flare without requiring surgical intervention from the gastroenterology service or consulted from general internal medicine. Patients randomized to the control arm are discharged with usual standard of care. Patients in the intervention group will be eligible for usual post-discharge care in addition to organized telephone follow-up by an IBD practice nurse at 1, 7 and 30 days post-discharge. In addition, these patients will receive bi-weekly correspondence from NoviSurvey to complete a short questionnaire on clinical disease severity and medication adherence. Based on telephone interaction and survey scores, the IBD nurse may arrange readmission or expedited ambulatory visit for high-risk patients.

Results

15 patients are currently enrolled into our study, with 7 randomized to the intervention and 8 to the control group. In the control group, 25% of patients were readmitted to hospital within 30 days of discharge and 13% failed to follow their steroid taper. There were no patients in the intervention group who were readmitted to hospital within 30 days and none who failed their steroid taper. In both the control or intervention group, there were no occurrences of deep vein thrombosis within 30 days post-discharge.

Conclusions

The preliminary findings in our small sample study indicate that a nurse led post-discharge intervention may translate to benefits including decreased readmission rates to hospital, better patient satisfaction and better medication adherence.

Funding Agencies

CCC

The preparation of a novel iron/manganese binary oxide for the efficient removal of hexavalent chromium [Cr(vi)] from aqueous solutions

To remove hexavalent chromium Cr(vi) efficiently, a novel Fe–Mn binary oxide adsorbent was prepared via a “two-step method” combined with a co-precipitation method and hydrothermal method. The as-prepared Fe–Mn binary oxide absorbent was characterized via transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectra (FTIR), thermogravimetric analysis (TGA), zeta potential, BET and X-ray photoelectron spectroscopy (XPS). The results indicated that the morphology of the adsorbent was rod-like with length of about 100 nm and width of about 50–60 nm, specific surface area was 63.297 m² g⁻¹, has the composition of α-Fe₂O₃, β-MnO₂ and MnFe₂O₄ and isoelectric point was observed at pH value of 4.81. The removal of Cr(vi) was chosen as a model reaction to evaluate the adsorption capacity of the Fe–Mn binary oxide adsorbent, indicating that the Fe–Mn binary oxide adsorbent showed high adsorption performance (removal rate = 99%) and excellent adsorption stability (removal rate > 90% after six rounds of adsorption). The adsorption behavior of the Fe–Mn binary oxide was better represented by the Freundlich model (adsorption isotherm) and the pseudo-second-order model (adsorption kinetic), suggesting that the adsorption process was multi-molecular layer chemical adsorption. The possible adsorption mechanism of the Fe–Mn binary oxide for the removal of Cr(vi) included the protonation process and the electrostatic attraction interactions.

A novel Fe–Mn binary oxide adsorbent prepared via “co-precipitation and hydrothermal” method, for the efficient and fast removal of Cr(vi).

Two-Dimensional VO2 Mesoporous Microarrays for High-Performance Supercapacitor

Two-dimensional (2D) mesoporous VO₂ microarrays have been prepared using an organic-inorganic liquid interface. The units of microarrays consist of needle-like VO₂ particles with a mesoporous structure, in which crack-like pores with a pore size of about 2 nm and depth of 20-100 nm are distributed on the particle surface. The liquid interface acts as a template for the formation of the 2D microarrays, as identified from the kinetic observation. Due to the mesoporous structure of the units and high conductivity of the microarray, such 2D VO₂ microarrays exhibit a high specific capacitance of 265 F/g at 1 A/g and excellent rate capability (182 F/g at 10 A/g) and cycling stability, suggesting the effect of unique microstructure for improving the electrochemical performance.

Diffusion Tensor Imaging of White Matter in Children Born from Preeclamptic Gestations

BACKGROUND AND PURPOSE

Individuals born from pregnancies complicated by preeclampsia have an elevated risk for cognitive impairment. Deviations in maternal plasma angiokines occur for prolonged intervals before clinical signs of preeclampsia. We hypothesized that fetal brain vascular and nervous tissue development become deviated during maternal progression toward preeclampsia and that such deviations would be detectable by MR imaging.

MATERIALS AND METHODS

In this pilot study, 10 matched (gestational and current ages) pairs (5 boys/5 girls, 7-10 years of age) from preeclampsia or control pregnancies were examined by using diffusion tensor MR imaging. An unbiased voxel-based analysis was conducted on fractional anisotropy and mean diffusivity parametric maps. Six brain ROIs were identified for subsequent analysis by tractography (middle occipital gyrus, caudate nucleus and precuneus, cerebellum, superior longitudinal fasciculus, and cingulate gyrus).

RESULTS

Statistical differences were present between groups for fractional anisotropy in the caudate nucleus (offspring from preeclamptic gestation > controls), volume of the tract for the superior longitudinal fasciculus (offspring from preeclamptic gestation > controls) and the caudate nucleus (offspring from preeclamptic gestation > controls), and for parallel diffusivity of the cingulate gyrus (offspring from preeclamptic gestation > controls).

CONCLUSIONS

These novel preliminary results along with previous results from the same children that identified altered cerebral vessel calibers and increased regional brain volumes justify fully powered MR imaging studies to address the impact of preeclampsia on human fetal brain development.

Characteristics of two-dimensional millimetric microarrays of TiO2 nanowires and their photocatalytic properties

Two-dimensional millimetric microarrays of TiO₂ nanowires were fabricated in this work.

Flexible n-type thermoelectric materials by organic intercalation of layered transition metal dichalcogenide TiS2

Organic semiconductors are attracting increasing interest as flexible thermoelectric materials owing to material abundance, easy processing and low thermal conductivity. Although progress in p-type polymers and composites has been reported, their n-type counterpart has fallen behind owing to difficulties in n-type doping of organic semiconductors. Here, we present an approach to synthesize n-type flexible thermoelectric materials through a facile electrochemical intercalation method, fabricating a hybrid superlattice of alternating inorganic TiS2 monolayers and organic cations. Electrons were externally injected into the inorganic layers and then stabilized by organic cations, providing n-type carriers for current and energy transport. An electrical conductivity of 790 S cm(-1) and a power factor of 0.45 mW m(-1) K(-2) were obtained for a hybrid superlattice of TiS2/[(hexylammonium)x(H2O)y(DMSO)z], with an in-plane lattice thermal conductivity of 0.12 ± 0.03 W m(-1) K(-1), which is two orders of magnitude smaller than the thermal conductivities of the single-layer and bulk TiS2. High power factor and low thermal conductivity contributed to a thermoelectric figure of merit, ZT, of 0.28 at 373 K, which might find application in wearable electronics.

Thermoelectric performance of SrTiO3 enhanced by nanostructuring-self-assembled particulate film of nanocubes

Self-assembled particulate films with a uniform structure over a large area were prepared from La-SrTiO3 nanocubes for thermoelectric applications. UV irradiation was used to assist the formation of particulate film for decomposition of the organic phase in situ to obtain a mechanically robust structure at high temperature. The thermoelectric properties of the particulate film were measured after calcination at 1000 °C under a reductive atmosphere (Ar/H2 = 60/40). A Seebeck coefficient of S = -239 ± 24 μV/K, electrical conductivity of σ = 160 ± 5 S/cm, and thermal conductivity of κ ≈ 1.5 W/mK were obtained for a self-assembled particulate film (La: 5%) corresponding to a ZT value of 0.2 at room temperature, which exceeded that of a La-SrTiO3 single crystal with similar composition.

Synthesis of Li-Mn-O mesocrystals with controlled crystal phases through topotactic transformation of MnCO₃

Mesocrystals of Li-Mn-O compounds, such as LiMn2O4, Li2MnO3, and LiMnO2-Li2MnO3, consisting of oriented nanoscale units were selectively produced under hydrothermal conditions from biomimetically prepared MnCO3 mesocrystals. Topotactic transformation through the intermediate phase of Mn5O8 inheriting a hierarchical structure of the MnCO3 precursor was essential for the formation of the mesocrystal compounds. The crystal phases were successfully controlled by varying the conditions for the hydrothermal reactions. The Li-Mn-O mesocrystals have considerable potential as cathodes of Li-ion batteries.

High-performance nanocomposite based memristor with controlled quantum dots as charge traps

We report a novel approach to improve the resistive switching performance of semiconductor nanorod (NR) arrays, by introducing ceria (CeO2) quantum dots (QDs) as surface charge trappers. The vertically aligned zinc oxide (ZnO) (NR) arrays were grown on transparent conductive glass by electrochemical deposition while CeO2 QDs were prepared by a solvothermal method. Subsequently, the as-prepared CeO2 QDs were embedded into a ZnO NR array by dip coating to obtain a CeO2-ZnO nanocomposite. Interestingly, such a device exhibits excellent resistive switching properties with much higher ON/OFF ratios, better uniformity, and stability over the pure ZnO and CeO2 nanostructures. The origin of resistive switching was studied and the role of heterointerface was discussed.

Fabrication of dielectric nanocubes in ordered structure by capillary force assisted self-assembly method and their piezoresponse properties

Ordered structures of barium titanate (BT) nanocubes, strontium titanate (ST) nanocubes and BT/ST nanocubes mixture were directly fabricated on Si and Pt-coated Si substrates using a capillary force assisted assembly method. The morphology of self-assembled structures was observed using field emission scanning electron microscopy (FE-SEM) and scanning probe microscopy (SPM). It was revealed that nanocubes were arranged with various degrees of ordering to develop multilayer and monolayer regions at the surface of substrates. The elemental mapping of the structure consisting of the nanocubes mixture was also investigated by transmission electron microscopy (TEM) with an energy dispersive X-ray spectroscopy (EDX). It was revealed that BT and ST nanocubes coexisted homogeneously in the structure and had possibility to be arranged in order to each other. The piezoresponse properties obtained by scanning probe microscopy (SPM) indicated that the hetero-interface between BT and ST nanocubes would introduce anomaly in piezoelectric properties.

In situ growth BaTiO3 nanocubes and their superlattice from an aqueous process

Ordered aggregated BaTiO(3) nanocubes with a narrow size distribution were obtained in an aqueous process by using bis(ammonium lactate) titanium dihydroxide (TALH) as Ti source in the presence of oleic acid and tert-butylamine. Kinetics of the formation of BaTiO(3) nanocubes indicated that an in situ growth mechanism was dominant and the superlattice of nanocubes formed in situ through the growth of BaTiO(3) nanoparticles in Ti-based hydrous gel. The size and morphology of nanocubes were controlled by tuning the concentration and molar ratio of surfactants. A novel growth model dependant on the structure of Ti precursor for the formation and morphology control of BaTiO(3) nanocubes and their superlattice was demonstrated.

A new effect of ultrasonication on the formation of BaTiO(3) nanoparticles

A new effect of ultrasonic irradiation on the formation of BaTiO(3) particles was identified. Ultrasonication caused the aggregation of the original 5-10nm BaTiO(3) particles in the same crystal axis and accelerated the formation of BaTiO(3) particles significantly. Furthermore, narrow size distribution was obtained for the aggregated particles under ultrasonic irradiation.

Sonochemical coating of magnetite nanoparticles with silica

Magnetite nanoparticles were coated with silica through the hydrolysis and condensation of tetraethyl orthosilicate (TEOS) under ultrasonic irradiation. The ultrasonic irradiation was used to prevent the agglomeration of the magnetite particles and accelerate the hydrolysis and condensation of TEOS. TEM, DLS, XRF, VSM, TG and sedimentation test were used to characterize the silica-coated magnetite particles. The dispersibility of silica-coated magnetite particles in aqueous solution was improved significantly and the agglomerate particle size was decreased to 110 nm. It was found that the agglomerate particle size of silica-coated magnetite particles was mainly decided by the coating temperature and the pH value in the silica-coating process. The weight ratio of silica in silica-coated magnetite particles was mainly decided by the pH value in the silica-coating process. The dispersibility of silica-coated magnetite particles was mainly decided by the agglomerate particle size of the suspension. The oxidation of magnetite particles in air was limited through the coated silica. The magnetism of silica-coated magnetite particles decreased slightly after silica-coating.

Sonochemical synthesis of monodispersed magnetite nanoparticles by using an ethanol-water mixed solvent

The magnetite nanoparticles were synthesized in an ethanol-water solution under ultrasonic irradiation from a Fe(OH)(2) precipitate. XRD, TEM, TG, IR, VSM and UV/vis absorption spectrum were used to characterize the magnetite nanoparticles. It was found that the formation of magnetite was accelerated in ethanol-water solution in the presence of ultrasonic irradiation, whereas, it was limited in ethanol-water solution under mechanical stirring. The monodispersibility of magnetite particles was improved significantly through the sonochemical synthesis in ethanol-water solution. The magnetic properties were improved for the samples synthesized under ultrasonic irradiation. This would be attributed to high Fe(2+) concentration in the magnetite cubic structure.

Replica multichannel polymer chips with a network of sacrificial channels sealed by adhesive printing method

Replica microchips for capillary array electrophoresis containing 10 separation channels (50 microm width, 50 microm depth and 100 microm pitch) and a network of sacrificial channels (100 microm width and 50 microm depth) were successfully fabricated on a poly(methyl methacrylate) (PMMA) substrate by injection molding. The strategy involved development of moving mask deep X-ray lithography to fabricate an array of channels with inclined channel sidewalls. A slight inclination of channel sidewalls, which can not be fabricated by conventional deep X-ray lithography, is highly required to ensure the release of replicated polymer chips from a mold. Moreover, the sealing of molded PMMA multichannel chips with a PMMA cover film was achieved by a novel bonding technique involving adhesive printing and a network of sacrificial channels. An adhesive printing process enables us to precisely control the thickness of an adhesive layer, and a network of sacrificial channels makes it possible to remove air bubbles and an excess adhesive, which are crucial to achieving perfect sealing of replica PMMA chips with well-defined channel and injection structures. A CCD camera equipped with an image intensifier was used to simultaneously monitor electrophoretic separations in ten micro-channels with laser-induced fluorescence detection. High-speed and high-throughput separations of a 100 bp DNA ladder and phi X174 Hae III DNA restriction fragments have been demonstrated using a 10-channel PMMA chip. The current work establishes the feasibility of mass production of PMMA multichannel chips at a cost-effective basis.