Substantially Accelerated Response and Recovery in Pd-Decorated WO3 Nanorods Gasochromic Hydrogen Sensor

The development of hydrogen (H2) gas sensors is essential for the safe and efficient adoption of H2 gas as a clean, renewable energy source in the challenges against climate change, given its flammability and associated safety risks. Among various H2 sensors, gasochromic sensors have attracted great interest due to their highly intuitive and low power operation, but slow kinetics, especially slow recovery rate limited its further practical application. This study introduces Pd-decorated amorphous WO3 nanorods (Pd-WO3 NRs) as an innovative gasochromic H2 sensor, demonstrating rapid and highly reversible color changes for H2 detection. In specific, the amorphous nanostructure exhibits notable porosity, enabling rapid detection and recovery by facilitating effective H2 gas interaction and efficient diffusion of hydrogen ions (H+) dissociated from the Pd nanoparticles (Pd NPs). The optimized Pd-WO3 NRs sensor achieves an impressive response time of 14 s and a recovery time of 1 s to 5% H2. The impressively fast recovery time of 1 s is observed under a wide range of H2 concentrations (0.2-5%), making this study a fundamental solution to the challenged slow recovery of gasochromic H2 sensors.

Enhancing Performance of Ultraviolet C Photodetectors Through Single-Domain Epitaxy of Monoclinic β-Ga2 O3 Films and Tailored Anti-Reflection Coating

Implementing high-performance ultraviolet C photodetectors (UVC PDs) based on β-Ga2 O3 films is challenging owing to the anisotropic crystal symmetry between the epitaxial films and substrates. In this study, highly enhanced state-of-the-art photoelectrical performance is achieved using single-domain epitaxy of monoclinic β-Ga2 O3 films on a hexagonal sapphire substrate. Unlike 3D β-Ga2 O3 films with twin domains, 2D β-Ga2 O3 films exhibit a single domain with a smooth surface and low concentration of point defects, which enable efficient charge separation by suppressing boundary-induced recombination. Furthermore, a tailored anti-reflection coating (ARC) is adopted as a light-absorbing medium to improve charge generation. The tailored nanostructure, which features a gradient refractive index, not only substantially reduces the reflection, but also suppresses the surface leakage current as a passivation layer. This study provides fundamental insights into the single-domain epitaxy of β-Ga2 O3 films and the application of ARC for the development of high-performance UVC PDs.

Relationships between Microbiome and Response to Neoadjuvant Chemoradiotherapy in Rectal Cancer

PURPOSE/OBJECTIVE(S)

Gut microbiome is known to be involved in antitumor immunotherapy and chemotherapy responses; however, few research has focused on the role of gut microbiome in the setting of concurrent chemoradiotherapy (CCRT). In this study, we investigated the tumor microbiome dynamics in patients undergoing neoadjuvant CCRT for locally advanced rectal cancer and sought to determine whether the diversity and composition of microbiome affect treatment response.

MATERIALS/METHODS

A total of 103 samples from 26 patients with locally advanced rectal cancer were collected and 16S ribosomal RNA amplicon sequencing was performed. All patients underwent neoadjuvant CCRT followed by surgical resection between 2008 and 2016. Samples were obtained from both tumor and normal rectal tissue at pre- and post-CCRT. According to the American Joint Committee on Cancer tumor regression grading (TRG) system, patients were divided into responders (TRG 0, 1) and non-responders (TRG 2, 3). We performed diversity, taxonomy, and network analyses to compare responders and non-responders. Then, we established the Bayesian network model to predict treatment response in patients with rectal cancer.

RESULTS

Overall, we detected 1260 microbial genera from 287 families, 132 orders, 56 classes, and 32 phyla in the bacteria kingdom. Between tumor and normal rectal tissues, there was no difference in microbial diversity and composition. On the other hand, there was a significant decrease in diversity and compositional alterations when comparing pre- and post-CCRT samples (all p<0.001). Ten patients (38.5%) were classified as responders and 16 patients (61.5%) were classified as non-responders. In both groups, CCRT significantly reduced microbial diversity and altered their composition, but it was more pronounced in non-responders. In taxonomic analysis of pre-CCRT samples, butyrate-producing bacteria were differentially enriched in responders. Meanwhile, in post-CCRT samples, opportunistic pathogen were overrepresented in non-responders. The network analysis revealed that butyrate-producing bacteria had strong interactions in responders, whereas opportunistic pathogen demonstrated strong interactions in non-responders (Pearson's coefficient>0.5). Finally, five microbes were selected as the optimal set for the response prediction model, which yielded an area under the curve value of 82.33%.

CONCLUSION

CCRT significantly changed the diversity and composition of microbiome, especially in non-responders. Several microbes might be related with treatment response. These findings highlight the potential of microbiome to play an important role as a biomarker in patients with rectal cancer. (NCT02533271).

Treatment Outcomes of Stereotactic Body Radiation Therapy for Pulmonary Metastasis from Sarcoma: A Multicenter, Retrospective Study

PURPOSE/OBJECTIVE(S)

The aim of this study was to evaluate the treatment outcomes and potential dose-response relationship of stereotactic body radiation therapy (SBRT) for pulmonary metastasis of sarcoma.

MATERIALS/METHODS

A retrospective review of 39 patients and 71 lesions treated with SBRT from two institutions was performed. The patients had oligometastatic or oligoprogressive disease, or were receiving palliation. Doses of 20-60 Gy were delivered in 1-5 fractions. The local control per tumor (LCpT) was evaluated according to the biologically effective dose with an α/β ratio of 10 (BED10) of the prescribed dose (BED10 ≥ 100 Gy vs. BED10 < 100 Gy). Clinical outcomes per patient, including local control per patient (LCpP), pulmonary progression-free rate (PPFR), any progression-free rate (APFR), and overall survival (OS) were investigated.

RESULTS

The median follow-up period was 27.2 months. The 1-, 2-, and 3-year LCpT rates for the entire cohort were 100.0%, 88.3%, and 73.6%, respectively. There was no observed difference in LCpT between the two BED10 groups (p = 0.180). The 3-year LCpP, PPFR, APFR, and OS rates were 78.1%, 22.7%, 12.9%, and 83.7%, respectively. Five (12.8%) patients with oligometastasis had long-term disease-free intervals, with a median survival period of 40.7 months. Factors that were associated with a worse prognosis were oligoprogression (vs. oligometastasis), multiple pulmonary metastases, and simultaneous extrathoracic metastasis.

CONCLUSION

SBRT for pulmonary metastasis of sarcoma is effective. Some selected patients may achieve durable response. Considerations of SBRT indication and disease extent may be needed as they may influence the prognosis.

Drastic Gas Sensing Selectivity in 2-Dimensional MoS2 Nanoflakes by Noble Metal Decoration

Noble metal nanoparticle decoration is a representative strategy to enhance selectivity for fabricating chemical sensor arrays based on the 2-dimensional (2D) semiconductor material, represented by molybdenum disulfide (MoS₂). However, the mechanism of selectivity tuning by noble metal decoration on 2D materials has not been fully elucidated. Here, we successfully decorated noble metal nanoparticles on MoS₂ flakes by the solution process without using reducing agents. The MoS₂ flakes showed drastic selectivity changes after surface decoration and distinguished ammonia, hydrogen, and ethanol gases clearly, which were not observed in general 3D metal oxide nanostructures. The role of noble metal nanoparticle decoration on the selectivity change is investigated by first-principles density functional theory (DFT) calculations. While the H₂ sensitivity shows a similar tendency with the calculated binding energy, that of NH₃ is strongly related to the binding site deactivation due to preferred noble metal particle decoration at the MoS₂ edge. This finding is a specific phenomenon which originates from the distinguished structure of the 2D material, with highly active edge sites. We believe that our study will provide the fundamental comprehension for the strategy to devise the highly efficient sensor array based on 2D materials.

Nonvolatile Control of Metal-Insulator Transition in VO2 by Ferroelectric Gating

Controlling phase transitions in correlated materials yields emergent functional properties, providing new aspects to future electronics and a fundamental understanding of condensed matter systems. With vanadium dioxide (VO₂ ), a representative correlated material, an approach to control a metal-insulator transition (MIT) behavior is developed by employing a heteroepitaxial structure with a ferroelectric BiFeO₃ (BFO) layer to modulate the interaction of correlated electrons. Owing to the defect-alleviated interfaces, the enhanced coupling between the correlated electrons and ferroelectric polarization is successfully demonstrated by showing a nonvolatile control of MIT of VO₂ at room temperature. The ferroelectrically-tunable MIT can be realized through the Mott transistor (VO₂ /BFO/SrRuO₃ ) with a remanent polarization of 80 µC cm^-2 , leading to a nonvolatile MIT behavior through the reversible electrical conductance with a large on/off ratio (≈10² ), long retention time (≈10⁴ s), and high endurance (≈10³ cycles). Furthermore, the structural phase transition of VO₂ is corroborated by ferroelectric polarization through in situ Raman mapping analysis. This study provides novel design principles for heteroepitaxial correlated materials and innovative insight to modulate multifunctional properties.

Regulating the surface of anion-doped TiO2 nanorods by hydrogen annealing for superior photoelectrochemical water oxidation

Dedications to achieve the highly efficient metal oxide semiconductor for the photoelectrochemical water splitting system have been persisted to utilize the TiO₂ as the promising photoanode material. Herein, we report notable progress for nanostructured TiO₂ photoanodes using facile sequential one-pot hydrothermal synthesis and annealing in hydrogen. A photocurrent density of 3.04 mA·cm^-2 at 1.23 V vs. reversible hydrogen electrode was achieved in TiO₂ nanorod arrays annealed in hydrogen ambient, which is approximately 4.25 times higher than that of pristine TiO₂ annealed in ambient air. 79.2% of incident photon-to-current efficiency at 380 nm wavelength demonstrates the prominence of the material at the near-UV spectral range region and 100 h chronoamperometric test exhibits the stability of the photoanode. Detailed studies regarding crystallinity, bandgap, and elemental analysis provide the importance of the optimized annealing condition for the TiO₂-based photoanodes. Water contact angle measurement displays the effect of hydrogen annealing on the hydrophilicity of the material. This study clearly demonstrates the marked improvement using the optimized hydrogen annealing, providing the promising methodologies for eco-friendly mass production of water splitting photoelectrodes.

Hypervalency in amorphous chalcogenides

The concept of hypervalency emerged as a notion for chemical bonding in molecules to explain the atomic coordination in hypervalent molecules that violates the electron-octet rule. Despite its significance, however, hypervalency in condensed phases, such as amorphous solids, remains largely unexplored. Using ab initio molecular-dynamics simulations, we report here the underlying principles of hypervalency in amorphous chalcogenide materials, in terms of the behaviour of hypervalent structural units, and its implicit relationship with material properties. The origin of a material-dependent tendency towards hypervalency is made evident with the multi-centre hyperbonding model, from which its relationship to abnormally large Born effective charges is also unambiguously revealed. The hyperbonding model is here extended to include interactions with cation s² lone pairs (LPs); such deep-lying LPs can also play a significant role in determining the properties of these chalcogenide materials. The role of hypervalency constitutes an indispensable and important part of chemical interactions in amorphous and crystalline chalcogenide solids.

Visible Light Driven Ultrasensitive and Selective NO2 Detection in Tin Oxide Nanoparticles with Sulfur Doping Assisted by l-Cysteine

In the pandemic era, the development of high-performance indoor air quality monitoring sensors has become more critical than ever. NO₂ is one of the most toxic gases in daily life, which induces severe respiratory diseases. Thus, the real-time monitoring of low concentrations of NO₂ is highly required. Herein, a visible light-driven ultrasensitive and selective chemoresistive NO₂ sensor is presented based on sulfur-doped SnO₂ nanoparticles. Sulfur-doped SnO₂ nanoparticles are synthesized by incorporating l-cysteine as a sulfur doping agent, which also increases the surface area. The cationic and anionic doping of sulfur induces the formation of intermediate states in the band gap, highly contributing to the substantial enhancement of gas sensing performance under visible light illumination. Extraordinary gas sensing performances such as the gas response of 418 to 5 ppm of NO₂ and a detection limit of 0.9 ppt are achieved under blue light illumination. Even under red light illumination, sulfur-doped SnO₂ nanoparticles exhibit stable gas sensing. The endurance to humidity and long-term stability of the sensor are outstanding, which amplify the capability as an indoor air quality monitoring sensor. Overall, this study suggests an innovative strategy for developing the next generation of electronic noses.

Surface-Tailored Medium Entropy Alloys as Radically Low Overpotential Oxygen Evolution Electrocatalysts

Numerous studies have explored new materials for electrocatalysts, but it is difficult to discover materials that surpass the catalytic activity of current commercially available noble metal electrocatalysts. In contrast to conventional transition metal alloys, high-entropy alloys (HEAs) have immense potential to maximize their catalytic properties because of their high stability and compositional diversity as oxygen evolution reactions (OERs). This work presents medium-entropy alloys (MEAs) as OER electrocatalysts to simultaneously satisfy the requirement of high catalytic activity and long-term stability. The surface of MEA electrocatalyst is tailored to suit the OER via anodizing and cyclic voltammetry activation methods. Optimized electrical properties and hydrophilicity of the surface enable an extremely low overpotential of 187 mV for achieving the current density of 10 mA cm^-2 alkaline media. Furthermore, a combined photovoltaic-electrochemical system with MEA electrocatalyst and a perovskite/Si tandem solar cell exhibits a solar-to-hydrogen conversion efficiency of 20.6% for an unassisted hydrogen generation system. These results present a new pathway for designing sustainable high efficiency water splitting cells.

Controlled Band Offsets in Ultrathin Hematite for Enhancing the Photoelectrochemical Water Splitting Performance of Heterostructured Photoanodes

Formation of type II heterojunctions is a promising strategy to enhance the photoelectrochemical performance of water-splitting photoanodes, which has been tremendously studied. However, there have been few studies focusing on the formation of type II heterojunctions depending on the thickness of the overlayer. Here, enhanced photoelectrochemical activities of a Fe₂O₃ film deposited-BiVO₄/WO₃ heterostructure with different thicknesses of the Fe₂O₃ layer have been investigated. The Fe₂O₃ (10 nm)/BiVO₄/WO₃ heterojunction photoanode shows a much higher photocurrent density compared to the Fe₂O₃ (100 nm)/BiVO₄/WO₃ photoanode. The Fe₂O₃ (10 nm)/BiVO₄/WO₃ trilayer heterojunction anodes have sequential type II junctions, while a thick Fe₂O₃ overlayer forms an inverse type II junction between Fe₂O₃ and BiVO₄. Furthermore, the incident-photon-to-current efficiency measured under back-illumination is higher than those measured under front-illumination, demonstrating the importance of the illumination sequence for light absorption and charge transfer and transport. This study shows that the thickness of the oxide overlayer influences the energy band alignment and can be a strategy to improve solar water splitting performance. Based on our findings, we propose a photoanode design strategy for efficient photoelectrochemical water splitting.

α-Gallium Oxide Films on Microcavity-Embedded Sapphire Substrates Grown by Mist Chemical Vapor Deposition for High-Breakdown Voltage Schottky Diodes

α-Gallium oxide, with its large band gap energy, is a promising material for utilization in power devices. Sapphire, which has the same crystal structure as α-Ga₂O₃, has been used as a substrate for α-Ga₂O₃ epitaxial growth. However, lattice and thermal expansion coefficient mismatches generate a high density of threading dislocations (TDs) and cracks in films. Here, we demonstrated the growth of α-Ga₂O₃ films with reduced TD density and residual stress on microcavity-embedded sapphire substrates (MESS). We fabricated the two types of substrates with microcavities: diameters of 1.5 and 2.2 μm, respectively. We confirmed that round conical-shaped cavities with smaller diameters are beneficial for the lateral overgrowth of α-Ga₂O₃ crystals with lower TD densities by mist chemical vapor deposition. We could obtain crack-free high-crystallinity α-Ga₂O₃ films on MESS, while the direct growth on a bare sapphire substrate resulted in an α-Ga₂O₃ film with a number of cracks. TD densities of α-Ga₂O₃ films on MESS with 1.5 and 2.2 μm cavities were measured to be 1.77 and 6.47 × 10⁸ cm^-2, respectively. Furthermore, cavities in MESS were certified to mitigate the residual stress via the redshifted Raman peaks of α-Ga₂O₃ films. Finally, we fabricated Schottky diodes based on α-Ga₂O₃ films grown on MESS with 1.5 and 2.2 μm cavities, which exhibited high breakdown voltages of 679 and 532 V, respectively. This research paves the way to fabricating Schottky diodes with high breakdown voltages based on high-quality α-Ga₂O₃ films.

Increased risk of cardiovascular diseases in patients with chronic rhinosinusitis: a longitudinal follow-up study using a national health screening cohort

BACKGROUND

Chronic rhinosinusitis (CRS) is one of the most common chronic inflammatory diseases and is characterized by sinonasal inflammation that lasts longer than 12 weeks. Whether the effect of chronic inflammation caused by CRS on cardiovascular diseases (CVDs) is similar to its effect on other inflammatory disorders has not been thoroughly evaluated. We aimed to demonstrate whether CRS patients have a higher prevalence of CVDs, including stroke and ischemic heart disease (IHD).

METHODOLOGY

We compared the prevalence of various comorbidities between CRS and control participants through a case-control cohort study from 2002 to 2015 that included 514,866 participants. CRS (n=6,552) and control (n=26,208) participants who were over 40 years old were selected by matching age, sex, income, and area of residence at a 1:4 ratio.

RESULTS

A stratified Cox proportional hazards model was utilized to assess the hazard ratio (HR) of CRS for stroke and IHD. The HRs for stroke and IHD were significantly increased in CRS patients compared to controls after adjusting for obesity, alcohol consumption, smoking, systolic and diastolic blood pressure, fasting blood glucose, total cholesterol, hemoglobin, and Charlson Comorbidity Index (CCI) scores. The HR of stroke was significantly higher in the absence of nasal polyps than in the presence of nasal polyps. The HR of IHD was significantly increased in the CRS group regardless of the presence of nasal polyps.

CONCLUSIONS

This study showed that CRS participants had a significantly higher prevalence of stroke and IHD.

Crystal Facet Engineering of TiO2 Nanostructures for Enhancing Photoelectrochemical Water Splitting with BiVO4 Nanodots

Although bismuth vanadate (BiVO₄) has been promising as photoanode material for photoelectrochemical water splitting, its charge recombination issue by short charge diffusion length has led to various studies about heterostructure photoanodes. As a hole blocking layer of BiVO₄, titanium dioxide (TiO₂) has been considered unsuitable because of its relatively positive valence band edge and low electrical conductivity. Herein, a crystal facet engineering of TiO₂ nanostructures is proposed to control band structures for the hole blocking layer of BiVO₄ nanodots. We design two types of TiO₂ nanostructures, which are nanorods (NRs) and nanoflowers (NFs) with different (001) and (110) crystal facets, respectively, and fabricate BiVO₄/TiO₂ heterostructure photoanodes. The BiVO₄/TiO₂ NFs showed 4.8 times higher photocurrent density than the BiVO₄/TiO₂ NRs. Transient decay time analysis and time-resolved photoluminescence reveal the enhancement is attributed to the reduced charge recombination, which is originated from the formation of type II band alignment between BiVO₄ nanodots and TiO₂ NFs. This work provides not only new insights into the interplay between crystal facets and band structures but also important steps for the design of highly efficient photoelectrodes.

Architecture engineering of nanostructured catalyst via layer-by-layer adornment of multiple nanocatalysts on silica nanorod arrays for hydrogenation of nitroarenes

Direct consideration for both, the catalytically active species and the host materials provides highly efficient strategies for the architecture design of nanostructured catalysts. The conventional wet chemical methods have limitations in achieving such unique layer-by-layer design possessing one body framework with many catalyst parts. Herein, an innovative physical method is presented that allows the well-regulated architecture design for an array of functional nanocatalysts as exemplified by layer-by-layer adornment of Pd nanoparticles (NPs) on the highly arrayed silica nanorods. This spatially confined catalyst exhibits excellent efficiency for the hydrogenation of nitroarenes and widely deployed Suzuki cross-coupling reactions; their facile separation from the reaction mixtures is easily accomplished due to the monolithic structure. The generality of this method for the introduction of other metal source has also been demonstrated with Au NPs. This pioneering effort highlights the feasibility of physically controlled architecture design of nanostructured catalysts which may stimulate further studies in the general domain of the heterogeneous catalytic transformations.

Rationally Designed TiO2 Nanostructures of Continuous Pore Network for Fast-Responding and Highly Sensitive Acetone Sensor

For the last several years, indoor air quality monitoring has been a significant issue due to the increasing time portion of indoor human activities. Especially, the early detection of volatile organic compounds potentially harmful to the human body by the prolonged exposure is the primary concern for public human health, and such technology is imperatively desired. In this study, highly porous and periodic 3D TiO₂ nanostructures are designed and studied for this concern. Specifically, extremely high gas molecule accessibility throughout the whole nanostructures and precisely controlled internecks of 3D TiO₂ nanostructures can achieve an unprecedented gas response of 299 to 50 ppm CH₃ COCH₃ with an extremely fast response time of less than 1s. The systematic approach to utilize the whole inner and outer surfaces of the gas sensing materials and periodically formed internecks to localize the current paths in this study can provide highly promising perspectives to advance the development of chemoresistive gas sensors using metal oxide nanostructures for the Internet of Everything application.

Boosting Unassisted Alkaline Solar Water Splitting Using Silicon Photocathode with TiO2 Nanorods Decorated by Edge-Rich MoS2 Nanoplates

To construct a highly efficient photoelectrochemical tandem device with silicon photocathode operating in alkaline conditions, it is desirable to develop stable and active catalysts which enable the photocathode to reliably perform under an alkaline environment. With nanostructured passivation layer and edge-exposed transition metal disulfides, silicon photocathode provides new opportunities for achieving unbiased alkaline solar water splitting. Here, the TiO₂ nanorod arrays decorated by edge-rich MoS₂ nanoplates are elaborately synthesized and deposited on p-Si. The vertically aligned TiO₂ nanorods fully stabilize the Si surface and improve anti-reflectance. Moreover, MoS₂ nanoplates with exposed edge sites provide catalytically active regions resulting in the kinetically favored hydrogen evolution under an alkaline environment. Interfacial energy band bending between p-Si and catalyst layers facilitates the transport of photogenerated electrons under steady-state illumination. Consequently, the MoS₂ nanoplates/TiO₂ nanorods/p-Si photocathode exhibits significantly improved photoelectrochemical-hydrogen evolution reaction (PEC-HER) performance in alkaline media with a high photocurrent density of 10 mA cm^-2 at 0 V versus RHE and high stability. By integrating rationally designed photocathode with earth-abundant Fe₆₀ (NiCo)₃₀ Cr₁₀ anode and perovskite/Si tandem photovoltaic cell, an unassisted alkaline solar water splitting is accomplished with a current density of 5.4 mA cm^-2 corresponding to 6.6% solar-to-hydrogen efficiency, which is the highest among p-Si photocathodes.

Pre-operative assessment of facial recess width in paediatric cochlear implant recipients: a radiological study

Background

The location of the vertical segment of the facial nerve varies greatly among patients undergoing otological surgery. Its position relative to the incus determines facial recess width, which has implications for ease of cochlear implantation.

Objective

To investigate the variation in facial nerve depth, relative to the incus, on pre-operative computed tomography in patients undergoing cochlear implantation.

Methods

A retrospective cohort study was conducted of paediatric patients undergoing cochlear implantation at a tertiary referral centre. Distance between the incus short process and facial nerve, in the transverse (medial-lateral) dimension, was measured at six imaging slices, ranging from 1.25 to 7.25 mm below the tip of the incus short process.

Results

Facial nerve depth relative to the incus short process demonstrated significant variability. Among all subjects and at all measurements taken inferior to the incus, the mean dimension between the facial nerve and the incus short process was 1.71 mm.

Conclusion

This paper presents a rapid, repeatable technique to assess the depth of the facial nerve vertical segment on pre-operative computed tomography, as measured relative to the tip of the incus short process. This allows the surgeon to anticipate facial recess width and round window access during cochlear implantation.

Microscopic evidence of strong interactions between chemical vapor deposited 2D MoS2 film and SiO2 growth template

Two-dimensional MoS2 film can grow on oxide substrates including Al2O3 and SiO2. However, it cannot grow usually on non-oxide substrates such as a bare Si wafer using chemical vapor deposition. To address this issue, we prepared as-synthesized and transferred MoS2 (AS-MoS2 and TR-MoS2) films on SiO2/Si substrates and studied the effect of the SiO2 layer on the atomic and electronic structure of the MoS2 films using spherical aberration-corrected scanning transition electron microscopy (STEM) and electron energy loss spectroscopy (EELS). The interlayer distance between MoS2 layers film showed a change at the AS-MoS2/SiO2 interface, which is attributed to the formation of S-O chemical bonding at the interface, whereas the TR-MoS2/SiO2 interface showed only van der Waals interactions. Through STEM and EELS studies, we confirmed that there exists a bonding state in addition to the van der Waals force, which is the dominant interaction between MoS2 and SiO2. The formation of S-O bonding at the AS-MoS2/SiO2 interface layer suggests that the sulfur atoms at the termination layer in the MoS2 films are bonded to the oxygen atoms of the SiO2 layer during chemical vapor deposition. Our results indicate that the S-O bonding feature promotes the growth of MoS2 thin films on oxide growth templates.

Risk factors for local recurrence and long term survival after minimally invasive intersphincteric resection for very low rectal cancer: Multivariate analysis in 161 patients

INTRODUCTION

Intersphincteric resection (ISR) is the ultimate anal-sparing technique as an alternative to abdominoperineal resection in selected patients. Oncological safety is still debated. This study analyses long-term oncological results and evaluates risk factors for local recurrence (LR) and overall survival (OS) after minimally-invasive ISR.

MATERIALS AND METHODS

Retrospective single-center data were collected from a prospectively maintained colorectal database. A total of 161 patients underwent ISR between 2008 and 2018. OS and local recurrence-free survival (LRFS) were assessed using Kaplan-Meier analysis (log-rank test). Risk factors for OS and LRFS were assessed with Cox-regression analysis.

RESULTS

Median follow-up was 55 months. LR occurred in 18 patients. OS and LRFS rates at 1, 3, and 5 years were 96%, 91%, and 80% and 96%, 89%, and 87%, respectively. Tumor size (p = 0.035) and clinical T-stage (p = 0.029) were risk factors for LRFS on univariate analysis. On multivariate analysis, tumor size (HR 2.546 (95% CI: 0.976-6.637); p = 0.056) and clinical T-stage (HR 3.296 (95% CI: 0.941-11.549); p = 0.062) were not significant. Preoperative CEA (p < 0.001), pathological T-stage (p = 0.033), pathological N-stage (p = 0.016) and adjuvant treatment (p = 0.008) were prognostic factors for OS on univariate analysis. Preoperative CEA (HR 4.453 (95% CI: 2.015-9.838); p < 0.001) was a prognostic factor on multivariate analysis.

CONCLUSIONS

This study confirms the oncological safety of minimally-invasive ISR for locally advanced low-lying rectal tumors when performed in experienced centers. Despite not a risk factor for LR, tumor size and, locally advanced T-stage with anterior involvement should be carefully evaluated for optimal surgical strategy. Preoperative CEA is a prognostic factor for OS.

Correction: Suppression of metal-to-insulator transition using strong interfacial coupling at cubic and orthorhombic perovskite oxide heterointerfaces

Correction for 'Suppression of metal-to-insulator transition using strong interfacial coupling at cubic and orthorhombic perovskite oxide heterointerfaces' by Woonbae Sohn et al., Nanoscale, 2021, 13, 708-715, DOI: 10.1039/D0NR07545K.

Direct Synthesis of Molybdenum Phosphide Nanorods on Silicon Using Graphene at the Heterointerface for Efficient Photoelectrochemical Water Reduction

MoP nanorod-array catalysts were directly synthesized on graphene passivated silicon photocathodes without secondary phase. Mo-O-C covalent bondings and energy band bending at heterointerfaces facilitate the electron transfer to the reaction sites. Numerous catalytic sites and drastically enhanced anti-reflectance of MoP nanorods contribute to the high solar energy conversion efficiency. Transition metal phosphides (TMPs) and transition metal dichalcogenides (TMDs) have been widely investigated as photoelectrochemical (PEC) catalysts for hydrogen evolution reaction (HER). Using high-temperature processes to get crystallized compounds with large-area uniformity, it is still challenging to directly synthesize these catalysts on silicon photocathodes due to chemical incompatibility at the heterointerface. Here, a graphene interlayer is applied between p-Si and MoP nanorods to enable fully engineered interfaces without forming a metallic secondary compound that absorbs a parasitic light and provides an inefficient electron path for hydrogen evolution. Furthermore, the graphene facilitates the photogenerated electrons to rapidly transfer by creating Mo-O-C covalent bondings and energetically favorable band bending. With a bridging role of graphene, numerous active sites and anti-reflectance of MoP nanorods lead to significantly improved PEC-HER performance with a high photocurrent density of 21.8 mA cm^-2 at 0 V versus RHE and high stability. Besides, low dependence on pH and temperature is observed with MoP nanorods incorporated photocathodes, which is desirable for practical use as a part of PEC cells. These results indicate that the direct synthesis of TMPs and TMDs enabled by graphene interlayer is a new promising way to fabricate Si-based photocathodes with high-quality interfaces and superior HER performance.

Optically Activated 3D Thin-Shell TiO2 for Super-Sensitive Chemoresistive Responses: Toward Visible Light Activation

One of the well-known strategies for achieving high-performance light-activated gas sensors is to design a nanostructure for effective surface responses with its geometric advances. However, no study has gone beyond the benefits of the large surface area and provided fundamental strategies to offer a rational structure for increasing their optical and chemical performances. Here, a new class of UV-activated sensing nanoarchitecture made of highly periodic 3D TiO2, which facilitates 55 times enhanced light absorption by confining the incident light in the nanostructure, is prepared as an active gas channel. The key parameters, such as the total 3D TiO2 film and thin-shell thicknesses, are precisely optimized by finite element analysis. Collectively, this fundamental design leads to ultrahigh chemoresistive response to NO2 with a theoretical detection limit of ≈200 ppt. The demonstration of high responses with visible light illumination proposes a future perspective for light-activated gas sensors based on semiconducting oxides.

Grain Boundaries Boost Oxygen Evolution Reaction in NiFe Electrocatalysts

In a polycrystalline material, the grain boundaries (GBs) can be effective active sites for catalytic reactions by providing an electrodynamically favorable surface. Previous studies have shown that grain boundary density is related to the catalytic activity of the carbon dioxide reduction reaction, but there is still no convincing evidence that the GBs provide surfaces with enhanced activity for oxygen evolution reaction (OER). Combination of various electrochemical measurements and chemical analysis reveals the GB density at surface of NiFe electrocatalysts directly affects the overall OER. In situ electrochemical microscopy vividly shows that the OER occurs mainly at the GB during overall reaction. It is observed that the reaction determining steps are altered by grain boundary densities and the meaningful work function difference between the inside of grain and GBs exists. High-resolution transmission electron microscopy shows that extremely high index planes are exposed at the GBs, enhancing the oxygen evolution activity. The specific nature of GBs and its effects on the OER demonstrated in this study can be applied to the various polycrystalline electrocatalysts.

Suppression of metal-to-insulator transition using strong interfacial coupling at cubic and orthorhombic perovskite oxide heterointerfaces

A quasi-two-dimensional electron gas (2DEG) evolved at the LaAlO3 (LAO)/SrTiO3 (STO) interface has attracted significant attention, because the insertion of perovskite titanates can tune the 2DEG conductivity. However, this depends on the Ti-O-Ti bonding angle and structural symmetry. In this study, we controlled the octahedral tilt of the LAO/CaTiO3 (CTO) interface by heterostructuring it with CTO grown on STO substrates of various thicknesses. The 2DEG was maintained when the thickness of CTO was below the critical thickness of 5 unit cells (uc); however, it was suppressed when the CTO thickness was above the critical thickness. High-angle annular dark-field (HAADF) scanning transmission electron microscopy (STEM) combined with integrated differential phase contrast (iDPC) STEM imaging was used to visualize the TiO6 octahedral tilt propagation and symmetry of the 5 uc and 24 uc CTO films. The symmetry of the 5 uc CTO film resembled that of the STO substrate, whereas the octahedral tilt propagated in the 24 uc CTO film due to the structural relaxation. These results show that the interface engineering of the octahedral tilt can enable or suppress the formation of the 2DEG in perovskite oxides.