Disseminated Penicillin-Resistant Streptococcus pneumoniae Infection: A Case Report.

An invasive pneumococcal disease involving sternoclavicular joint arthritis, lumbar spondylodiscitis, and muscular abscesses caused by penicillin-resistant Streptococcus pneumoniae has not been reported previously. We successfully treated a 57-year-old man with this condition using surgical drainage and debridement, and laminectomy/fenestration, in combination with the administration of two IV antimicrobial drugs based on blood culture results. Clinical resolution was obtained after decompression of the lumbar spine, with minimal restriction of the left lower limb. This treatment approach should be considered depending on the pathogen, underlying host factors, and the severity of the disease.

An Oxysulfide Photocatalyst Evolving Hydrogen with an Apparent Quantum Efficiency of 30 % under Visible Light.

Photocatalytic water splitting is a simple means of converting solar energy into storable hydrogen energy. Narrow-band gap oxysulfide photocatalysts have attracted much attention in this regard owing to the significant visible-light absorption and relatively high stability of these compounds. However, existing materials suffer from low efficiencies due to difficulties in synthesizing these oxysulfides with suitable degrees of crystallinity and particle sizes, and in constructing effective reaction sites. The present work demonstrates the production of a Gd2 Ti2 O5 S2 (λ<650 nm) photocatalyst capable of efficiently driving photocatalytic reactions. Single-crystalline, plate-like Gd2 Ti2 O5 S2 particles with atomically ordered surfaces were synthesized by flux and chemical etching methods. Ultrafine Pt-IrO2 cocatalyst particles that promoted hydrogen (H2 ) and oxygen (O2 ) evolution reactions were subsequently loaded on the Gd2 Ti2 O5 S2 while ensuring an intimate contact by employing a microwave-heating technique. The optimized Gd2 Ti2 O5 S2 was found to evolve H2 from an aqueous methanol solution with a remarkable apparent quantum efficiency of 30 % at 420 nm. This material was also stable during O2 evolution in the presence of a sacrificial reagent. The results presented herein demonstrates a highly efficient narrow-band gap oxysulfide photocatalyst with potential applications in practical solar hydrogen production.

Three-dimensional CT imaging in extensor tendons using deep learning reconstruction: optimal reconstruction parameters and the influence of dose.

The purpose of this study was to assess the optimal reconstruction parameters and the influence of tube current in extensor tendons three-dimensional computed tomography (3D CT) using deep learning reconstruction, using iterative reconstruction as a reference. In the phantom study, a cylindrical phantom with a 3 mm rod simulated an extensor tendon was used. The phantom images were acquired at tube current of 50, 100, 150, 200, and 250 mA. In the clinical study, CT scans of hand tendons were performed on nine hands from eight patients. All images were reconstructed using advanced intelligent clear-IQ engine (AiCE) parameters (body, body sharp, brain CTA, and brain LCD) and adaptive iterative dose reduction three dimensional (AIDR 3D). The objective image quality for tendon detectability was evaluated by calculating the low-contrast object specific contrast-to-noise ratio (CNRLO) in the phantom study and CNR and coefficient of variation (CV) in the clinical study. In the phantom study, CNRLO (at 200 mA) of AiCE parameters (body, body sharp, brain CTA, and brain LCD) and AIDR 3D were 5.2, 5.3, 5.3, 5.8, and 5.0, respectively. In the clinical study, AiCE brain CTA was higher CNR and lower CV values compared to other reconstruction parameters. AiCE without dose reduction may be an effective strategy for further improving the image quality of extensor tendons 3D CT. Our study suggests that the AiCE brain CTA is more suitable for extensor tendons 3D CT compared to other AiCE parameters.

The origin and evolution of methanogenesis and Archaea are intertwined.

Methanogenesis has been widely accepted as an ancient metabolism, but the precise evolutionary trajectory remains hotly debated. Disparate theories exist regarding its emergence time, ancestral form, and relationship with homologous metabolisms. Here, we report the phylogenies of anabolism-involved proteins responsible for cofactor biosynthesis, providing new evidence for the antiquity of methanogenesis. Revisiting the phylogenies of key catabolism-involved proteins further suggests that the last Archaea common ancestor (LACA) was capable of versatile H2-, CO2-, and methanol-utilizing methanogenesis. Based on phylogenetic analyses of the methyl/alkyl-S-CoM reductase family, we propose that, in contrast to current paradigms, substrate-specific functions emerged through parallel evolution traced back to a nonspecific ancestor, which likely originated from protein-free reactions as predicted from autocatalytic experiments using cofactor F430. After LACA, inheritance/loss/innovation centered around methanogenic lithoautotrophy coincided with ancient lifestyle divergence, which is clearly reflected by genomically predicted physiologies of extant archaea. Thus, methanogenesis is not only a hallmark metabolism of Archaea, but the key to resolve the enigmatic lifestyle that ancestral archaea took and the transition that led to physiologies prominent today.

Nanobdella aerobiophila gen. nov., sp. nov., a thermoacidophilic, obligate ectosymbiotic archaeon, and proposal of Nanobdellaceae fam. nov., Nanobdellales ord. nov. and Nanobdellia class. nov.

A co-culture of a novel thermoacidophilic, obligate symbiotic archaeon, designated as strain MJ1T, with its specific host archaeon Metallosphaera sedula strain MJ1HA was obtained from a terrestrial hot spring in Japan. Strain MJ1T grew in the co-culture under aerobic conditions. Coccoid cells of strain MJ1T were 200-500 nm in diameter, and attached to the MJ1HA cells in the co-culture. The ranges and optima of the growth temperature and pH of strain MJ1T in the co-culture were 60-75 °C (optimum, 65-70 °C) and pH 1.0-4.0 (optimum, pH 2.5), respectively. Core lipids of dialkyl glycerol tetraethers (GDGT)-3 and GDGT-4 were highly abundant in MJ1T cells concentrated from the co-culture. Strain MJ1T has a small genome (0.67 Mbp) lacking genes for biosynthesis of essential biomolecules, such as nucleotides, lipids and ATP. The genomic DNA G+C content was 24.9 mol%. The 16S rRNA gene sequence of strain MJ1T was most closely related to that of the cultivated species, 'Nanopusillus acidilobi' strain N7A (85.8 % similarity). Based on phylogenetic and physiological characteristics, we propose the name Nanobdella aerobiophila gen. nov., sp. nov. to accommodate the strain MJ1T (=JCM 33616T=DSM 111728T). In addition, we propose the names Nanobdellaceae fam. nov., Nanobdellales ord. nov., and Nanobdellia class. nov. to accommodate the novel genus.

Influence of field of view size and reconstruction methods on single-energy metal artifact reduction: a phantom study.

The purpose of this study was to evaluate the effect of single-energy metal artifact reduction (SEMAR) for metal artifacts using CT images reconstructed with adaptive iterative dose reduction three dimensional (AIDR3D) and advanced intelligent clear-IQ engine (AiCE) in calibration-field of view of various sizes. A prosthetic hip joint was arranged at the center of the phantom. The phantom images were scanned by changing calibration-field of view of 320 mm and 500 mm, and were reconstructed using filtered back-projection (FBP), AIDR3D, and AiCE with and without SEMAR, respectively. The metal artifact reduction with SEMAR was evaluated by calculated the relative artifact index value and visual scores in degree of artifact by seven radiology technologists. Relative artifact index of FBP, AIDR3D, and AiCE with 320 mm/500 mm calibration-field of views were 10.2/10.0, 16.3/16.4, and 17.8/17.9 without SEMAR, 3.3/3.1, 2.6/2.5, and 2.3/2.0 with SEMAR, respectively. Visual scores were not significantly different between 320 and 500 mm calibration-field of views in all reconstruction methods. The effect of metal artifact reduction was not affected by calibration-field of view sizes in the SEMAR combined with AIDR3D or AiCE.

Cultivation and biogeochemical analyses reveal insights into methanogenesis in deep subseafloor sediment at a biogenic gas hydrate site.

Gas hydrates deposited in subseafloor sediments are considered to primarily consist of biogenic methane. However, little evidence for the occurrence of living methanogens in subseafloor sediments has been provided. This study investigated viable methanogen diversity, population, physiology and potential activity in hydrate-bearing sediments (1-307 m below the seafloor) from the eastern Nankai Trough. Radiotracer experiments, the quantification of coenzyme F430 and molecular sequencing analysis indicated the occurrence of potential methanogenic activity and living methanogens in the sediments and the predominance of hydrogenotrophic methanogens followed by methylotrophic methanogens. Ten isolates and nine representative culture clones of hydrogenotrophic, methylotrophic and acetoclastic methanogens were obtained from the batch incubation of sediments and accounted for 0.5-76% of the total methanogenic sequences directly recovered from each sediment. The hydrogenotrophic methanogen isolates of Methanocalculus and Methanoculleus that dominated the sediment methanogen communities produced methane at temperatures from 4 to 55 °C, with an abrupt decline in the methane production rate at temperatures above 40 °C, which is consistent with the depth profiles of potential methanogenic activity in the Nankai Trough sediments in this and previous studies. Our results reveal the previously overlooked phylogenetic and metabolic diversity of living methanogens, including methylotrophic methanogenesis.

Unveiling charge dynamics of visible light absorbing oxysulfide for efficient overall water splitting.

Oxysulfide semiconductor, Y2Ti2O5S2, has recently discovered its exciting potential for visible-light-induced overall water splitting, and therefore, imperatively requires the probing of unknown fundamental charge loss pathways to engineer the photoactivity enhancement. Herein, transient diffuse reflectance spectroscopy measurements are coupled with theoretical calculations to unveil the nanosecond to microsecond time range dynamics of the photogenerated charge carriers. In early nanosecond range, the pump-fluence-dependent decay dynamics of the absorption signal is originated from the bimolecular recombination of mobile charge carriers, in contrast, the power-law decay kinetics in late microsecond range is dominated by hole detrapping from exponential tail trap states of valence band. A well-calibrated theoretical model estimates various efficiency limiting material parameters like recombination rate constant, n-type doping density and tail-states parameters. Compared to metal oxides, longer effective carrier lifetime ~6 ns is demonstrated. Different design routes are proposed to realize efficiency beyond 10% for commercial solar-to-hydrogen production from oxysulfide photocatalysts.

Insights into the Methanogenic Population and Potential in Subsurface Marine Sediments Based on Coenzyme F430 as a Function-Specific Biomarker.

Coenzyme F430, the prosthetic group of methyl coenzyme M reductase (MCR), is a key compound in methane metabolism. We applied coenzyme F430 as a function-specific biomarker of methanogenesis to subsurface marine sediments collected below the sulfate reduction zone to investigate the distribution and activity of methanogens. In addition, we examined the kinetics of the epimerization of coenzyme F430, which is the first stage of the degradation process after cell death, at various temperatures (4, 15, 34, 60 °C) and pH (5, 7, 9) conditions, which cover in situ conditions of drilled sediments used in this study. The degradation experiments revealed that the kinetics of the epimerization well follow the thermodynamic laws, and the half-life of coenzyme F430 is decreasing from 304 days to 11 h with increasing the in situ temperature. It indicates that the native F430 detected in the sediments is derived from living methanogens, because the abiotic degradation of F430 is much faster than the sedimentation rate and will not be fossilized. Based on coenzyme F430 analysis and degradation experiments, the native form of F430 detected in subseafloor sediments off the Shimokita Peninsula originates from living methanogen cells, which is protected from degradation in cells but disappears soon after cell death. The biomass of methanogens calculated from in situ F430 concentration and F430 contents in cultivable methanogen species decreases by 2 orders of magnitude up to a sediment depth of 2.5 km, with a maximum value at ∼70 m below the seafloor (mbsf), while the proportion of methanogens to the total prokaryotic cell abundance increases with the depth, which is 1 to 2 orders of magnitude higher than expected previously. Our results indicate the presence of undetectable methanogens using conventional techniques.

Rates and risk factors for amputation in people with diabetes in Japan: a historical cohort study using a nationwide claims database.

BACKGROUND: The prevalence of diabetes is rising, and diabetes develops at a younger age in East Asia. Although lower limb amputation negatively affects quality of life and increases the risk of cardiovascular events, little is known about the rates and predictors of amputation among persons with diabetes from young adults to those in the "young-old" category (50-72 y). METHODS: We analyzed data from a nationwide claims database in Japan accumulated from 2008 to 2016 involving 17,288 people with diabetes aged 18-72 y (mean age 50.2 y, HbA1c 7.2%). Amputation occurrence was determined according to information from the claims database. Cox regression model identified variables related to lower limb amputation. RESULTS: The mean follow-up time was 5.3 years, during which time 16 amputations occurred (0.17/1000 person-years). Multivariate Cox regression analysis showed that age (hazard ratio [HR] 1.09 [95% confidence intervals] 1.02-1.16, p = 0.01) and HbA1c (HR 1.46 [1.17-1.81], p < 0.01) were independently associated with amputations. Compared with those aged < 60 years with HbA1c < 8.0%, the HR for amputation was 27.81 (6.54-118.23) in those aged ≥60 years and HbA1c ≥8.0%. CONCLUSIONS: Age and HbA1c were associated with amputations among diabetic individuals, and the rates of amputation were significantly greater in those ≥60 years old and with HbA1c ≥8.0%.

Temperature limits to deep subseafloor life in the Nankai Trough subduction zone.

Microorganisms in marine subsurface sediments substantially contribute to global biomass. Sediments warmer than 40°C account for roughly half the marine sediment volume, but the processes mediated by microbial populations in these hard-to-access environments are poorly understood. We investigated microbial life in up to 1.2-kilometer-deep and up to 120°C hot sediments in the Nankai Trough subduction zone. Above 45°C, concentrations of vegetative cells drop two orders of magnitude and endospores become more than 6000 times more abundant than vegetative cells. Methane is biologically produced and oxidized until sediments reach 80° to 85°C. In 100° to 120°C sediments, isotopic evidence and increased cell concentrations demonstrate the activity of acetate-degrading hyperthermophiles. Above 45°C, populated zones alternate with zones up to 192 meters thick where microbes were undetectable.

Skipping breakfast, late-night eating and current smoking are associated with medication adherence in Japanese patients with diabetes.

AIMS: Little is known about the relationship between medication adherence for oral hypoglycemic agents (OHAs) and glycemic control after adjusting healthy adherer effect in large scale study. Thus, adjusting for health-related behaviors, we investigated the clinical variables associated with medication adherence and the relationship between medication adherence and glycemic control using a large claims database. METHODS: Analyzed were 8805 patients with diabetes whose medication records for OHA were available for at least 1year. Medication adherence was evaluated by the proportion of days covered (PDC). Multivariate logistic regression model was used to identify clinical variables significantly associated with non-adherence. Multiple regression analysis evaluated the relationship between PDC and HbA1c after adjusting for health-related behaviors. RESULTS: Mean PDC was 80.1% and 32.8% of patients were non-adherence. Logistic analysis indicated that older age and taking concomitant medications were significantly associated with adherence while skipping breakfast (odds ratio 0.66 [95% CI 0.57-0.76]), late-night eating (0.86 [0.75-0.98]), and current smoking (0.89 [0.80-0.99]) were significantly associated with non-adherence. CONCLUSIONS: Skipping breakfast, late-night eating and current smoking were significantly associated with medication adherence, suggesting that clinicians pay attention to those health-related behaviors to achieve good medication adherence.

Application of accelerated long-range corrected exchange functional [LC-DFT(2Gau)] to periodic boundary condition systems: CO adsorption on Cu(111) surface.

Several different types of density functional theory (DFT) exchange correlation functionals were applied to a periodic boundary condition (PBC) system [carbon monoxide (CO) adsorbed on Cu(111): CO/Cu(111)] and the differences in the results calculated using these functionals were compared. The exchange correlation functionals compared were those of Perdew-Burke-Ernzerhof (PBE) and those of long-range corrected density functional theory (LC-DFT), such as LC-ωPBE(2Gau) and LC-BLYP(2Gau). Solid state properties such as the partial density of states were calculated in order to elucidate the detailed adsorption mechanisms and back-bonding peculiar to the CO/Cu(111) system. In addition, our benchmark analysis of the correlations among the orbitals of CO and Cu metal using LC-DFT reasonably was in line with the experimentally observed adsorption site. The computation time was reasonable, and other numerical results were found to agree well with the experimental results and also with the theoretical results of other researchers. This suggests that the long-range Hartree-Fock exchange integral should be included to correctly predict the electronic nature of PBC systems.

Combination of diabetes mellitus and lack of habitual physical activity is a risk factor for functional disability in Japanese.

OBJECTIVE: Declining healthy life expectancy due to functional disability is relevant and urgent because of its association with decreased quality of life and also for its enormous socioeconomic impact. The aim of this study is to examine the impact of diabetes, hypertension, dyslipidemia and physical activity habits on functional disability among community-dwelling Japanese adults. RESEARCH DESIGN AND METHODS: This is a population-based retrospective cohort study including 9673 people aged 39-98 years in Japan (4420, men). Functional disability was defined as a condition meeting Japan's new long-term care insurance certification requirements for the need of assistance in the activities of daily living whether by caregivers or assistive devices. Cox proportional-hazards regression model identified variables related to functional disability. RESULTS: Median follow-up was 3.7 years. During the study period, 165 disabilities occurred in the overall study population. Multivariate analysis showed that diabetes (HR 1.74 (95% CI 1.12 to 2.68)) and no physical activity habit (HR 1.83 (1.27 to 2.65)) presented increased risks for disability. HR for disability increased with the number of risk factors (HR of individuals with four conditions, 3.96 (1.59 to 9.99) vs individuals with none of those conditions as a reference). HR for disability among patients with diabetes with and without a physical activity habit was 1.68 (0.70 to 4.04) and 3.19 (1.79 to 5.70), respectively, compared with individuals without diabetes with a physical activity habit. CONCLUSIONS: The combination of diabetes and lack of habitual physical activity is predictive of functional disability in Japanese. Habitual physical activity attenuates the risk of functional disability in patients with diabetes.

Risk of coronary artery disease according to glucose abnormality status and prior coronary artery disease in Japanese men.

OBJECTIVE: Although glucose abnormality status (GAS), prior coronary artery disease (CAD), and other traditional risk factors affect the incidence of subsequent CAD, their impact in the same cohort has been scantly studied. RESEARCH DESIGN AND METHODS: We analyzed data from a nationwide claims database in Japan that was accumulated during 2008-2016 involving 138,162 men aged 18-72 years. Participants were classified as having normoglycemia, borderline glycemia, or diabetes mellitus (DM) with prior CAD (CAD+) or without prior CAD (CAD-). Cox regression model identified variables related to the incidence of CAD. RESULTS: Among CAD-, management of traditional risks differed from those with and without subsequent CAD events. On the other hand, such differences were weaker in borderline glycemia and DM CAD+, and the influence of traditional risk factors on subsequent CAD was not observed. Cox regression model showed that borderline glycemia and DM confer approximately 1.2- and 2.8-fold excess risks of CAD, respectively, compared with CAD- with normoglycemia. CAD+ confers approximately a 5- to 8-fold increased risk. The impacts of DM and prior CAD additively reached a hazard ratio (HR) of 15.74 (95% confidence interval [CI]: 11.82-21.00). However, the HR in those with borderline glycemia and CAD+ was 7.20 (95% CI: 5.01-10.34), which was not different from those with normoglycemia and CAD+. CONCLUSION: Control status of traditional risk factors and impact on subsequent CAD differ among categories of glycemic status with and without prior CAD. Individualizing treatment strategies is needed in consideration of risk factors, such as GAS and CAD+.

Overt Proteinuria, Moderately Reduced eGFR and Their Combination Are Predictive of Severe Diabetic Retinopathy or Diabetic Macular Edema in Diabetes.

Purpose: Since the combined effects of proteinuria and a moderately decreased eGFR on incident severe eye complications in patients with diabetes are still largely unknown, these associations were determined in a large historical cohort of Japanese patients with diabetes mellitus. Methods: We evaluated the effects of overt proteinuria (OP) (dipstick 1+ and over) and/or moderately reduced estimated glomerular filtration rate (eGFR) (MG) (baseline eGFR 30.0-54.9 mL/min/1.73 m2) on the incidence of treatment-required diabetic eye diseases (TRDED). We divided 7709 patients into four groups according to the presence or absence of OP and MG: no OP without MG (NP[MG-]), OP without MG (OP[MG-]), no OP with MG (NP[MG+]), and OP with MG (OP[MG+]). Multivariate Cox analyses were performed to calculate hazard ratios (HRs) with 95% confidence intervals for combinations of the presence and/or absence of OP and MG on the risk of developing TRDED. Results: During the median follow-up period of 5.6 years, 168 patients developed TRDED. HRs for OP and MG for incident TRDED were 1.91 (95% confidence interval, 1.27-2.87) and 1.90 (1.11-3.23), respectively. HRs for incident TRDED were 1.73 (1.11-2.69) and 5.57 (2.40-12.94) for OP(MG-) and OP(MG+), respectively, in comparison with NP(MG-). Conclusions: In Japanese patients with diabetes, OP and MG were separately as well as additionally associated with higher risks of TRDED. Results indicate the necessity of the simultaneous assessment of proteinuria and eGFR for appropriate evaluation of risks of severe eye complications in patients with diabetes.

Pulse Pressure is a Stronger Predictor Than Systolic Blood Pressure for Severe Eye Diseases in Diabetes Mellitus.

Background Evidence of the role of systolic blood pressure ( SBP ) in development of severe diabetic retinopathy is not strong, although the adverse effect of low diastolic blood pressure has been a partial explanation. We assessed the predictive ability of incident severe diabetic retinopathy between pulse pressure ( PP ) which considers both SBP and diastolic blood pressure, compared with SBP . Methods and Results Eligible patients (12 242, 83% men) aged 19 to 72 years from a nationwide claims database were analyzed for a median observational 4.8-year period. Severe diabetic retinopathy was defined as vision-threatening treatment-required diabetic eye diseases. Multivariate Cox regression analysis revealed that hazard ratios (95% CI ) of treatment-required diabetic eye diseases for 1 increment of standard deviation and the top tertile compared with the bottom tertile were 1.39 (1.21-1.60) and 1.72 (1.17-2.51), respectively, for PP and 1.22 (1.05-1.41) and 1.43 (0.97-2.11), respectively, for SBP adjusted for age, sex, body mass index, hemoglobin A1c, fasting plasma glucose, lipids, and smoking status. In a model with SBP and PP simultaneously as covariates, the hazard ratios of only PP (hazard ratios [95% CI ], 1.57 [1.26-1.96]) but not SBP (0.85 [0.68-1.07]) were statistically significant. Delong test revealed a significant difference in the area under the receiver operating characteristic curve between PP and SBP (area under the receiver operating characteristic curve [95% CI ], 0.58 [0.54-0.63] versus 0.54 [0.50-0.59]; P=0.03). The strongest predictor remained as hemoglobin A1c (area under the receiver operating characteristic curve [95% CI ], 0.80 [0.77-0.84]). Conclusions After excluding the significant impact of glycemic control, PP in comparison with SBP is a better predictor of severe diabetic retinopathy, suggesting a role of diastolic blood pressure and arterial stiffness in pathology.

Relationship Between Number of Multiple Risk Factors and Coronary Artery Disease Risk With and Without Diabetes Mellitus.

PURPOSE: To determine the degree of control of multiple risk factors under real-world conditions for coronary artery disease (CAD) according to the presence or absence of diabetes mellitus (DM) and to determine whether reaching multifactorial targets for blood pressure (BP), low-density lipoprotein-cholesterol (LDL-C), HbA1c, and current smoking is associated with lower risks for CAD. METHODS: We investigated the effects on subsequent CAD of the number of controlled risk factors among BP, LDL-C, HbA1c, and current smoking in a prospective cohort study using a nationwide claims database of 220,894 individuals in Japan. Cox regression examined risks over a 4.8-year follow-up. RESULTS: The largest percentage of participants had two risk factors at target in patients with DM (39.6%) and subjects without DM (36.4%). Compared with those who had two targets achieved, the risks of CAD among those who had any one and no target achieved were two and four times greater, respectively, regardless of the presence of DM. The effect of composite control was sufficient to bring CAD risk in patients with DM below that for subjects without DM with any two targets achieved, whereas the risk of CAD in the DM group with all four risk factors uncontrolled was 9.4 times more than in the non-DM group who had achieved two targets. CONCLUSIONS: These findings show that composite control of modifiable risk factors has a large effect in patients with and without DM. The effect was sufficient to bring CAD risk in patients with DM below that in the non-DM group who had two targets achieved.

A case of normotensive incidentally discovered adrenal pheochromocytoma.

Pheochromocytomas are catecholamine-producing neuroendocrine tumors that arise from the adrenal medulla. The clinical presentation includes headache, palpitation, and hypertension, but pheochromocytomas are sometimes clinically silent. The present case highlights the importance of biochemical testing for pheochromocytoma in patients with adrenal incidentaloma, even if they are completely normotensive and asymptomatic.

Anion-Substitution-Induced Nonrigid Variation of Band Structure in SrNbO3- xN x (0 ≤ x ≤ 1) Epitaxial Thin Films.

Pervoskite oxynitrides exhibit rich functionalities such as colossal magnetoresistance and high photocatalytic activity. The wide tunability of physical properties by the N/O ratio makes perovskite oxynitrides promising as optical and electrical materials. However, composition-dependent variation of the band structure, especially under partially substituted composition, is not yet well understood. In this study, we quantitatively analyzed the composition-dependent variation of band structure of a series of SrNbO3- xN x (0 ≤ x ≤ 1.02) epitaxial thin films. Electrical conductivity decreased along with the increase of N content x as a result of an increase in Nb valence from 4+ to 5+. Optical measurements revealed that the N 2p band is formed at a critical composition between 0.07 < x < 0.38, which induces charge-transfer transition (CTT) in the visible-light region. These variations in the band structure were explained by first-principles calculations. However, the CTT energy slightly increased at higher N contents (i.e., lower carrier density) on contrary to the expectation based on the rigid-band-like shift of the Fermi level, which suggests a complex combination of the following band-shifting effects induced by N-substitution: whereas (1) reduction of the Burstein-Moss effect causes CTT energy reduction, (2) enhancement of hybridization between Nb 4d and N 2p orbitals and/or (3) suppression of many-body effects enlarge the band gap energy at larger N content. The band structure variation in perovskite oxynitride as presently elucidated would be a guidepost for future material design.