[A New Preoperative Simulation Using Magnetic Resonance Imaging Bone-Like Imaging with Zero-Echo-Time Sequence].

This study aimed to evaluate the clinical usefulness of zero-echo time(ZTE)-based magnetic resonance imaging(MRI)in planning an optimal surgical approach and applying ZTE for anatomical guidance during transcranial surgery. P atients who underwent transcranial surgery and carotid endarterectomy and for whom ZTE-based MRI and magnetic resonance angiography(MRA)data were obtained, were analyzed by creating ZTE/MRA fusion images and 3D-ZTE-based MRI models. We examined whether these images and models could be substituted for computed tomography imaging during neurosurgical procedures. Furthermore, the clinical usability of the 3D-ZTE-based MRI model was evaluated by comparing it with actual surgical views. ZTE/MRA fusion images and 3D-ZTE-based MRI models clearly illustrated the cranial and intracranial morphology without radiation exposure or the use of an iodinated contrast medium. The models allowed the determination of the optimum surgical approach for cerebral aneurysms, brain tumors near the brain surface, and cervical internal carotid artery stenosis by visualizing the relationship between the lesions and adjacent bone structures. However, ZTE-based MRI did not provide useful information for surgery for skull base lesions, such as vestibular schwannoma, because bone structures of the skull base often include air components, which cause signal disturbances in MRI. ZTE sequences on MRI allowed distinct visualization of not only the bone but also the vital structures around the lesion. This technology is minimally invasive and useful for preoperative planning and guidance of the optimum approach during surgery in a subset of neurosurgical diseases.

Role of amide proton transfer imaging in maximizing tumor resection in malignant glioma: a possibility to take the place of 11C-methionine positron emission tomography.

BACKGROUND: Amide proton transfer (APT) imaging has been proposed as a technique to assess tumor metabolism. However, the relationship between APT imaging and other quantitative modalities including positron emission tomography (PET) has not been investigated in detail. This study aimed to evaluate the clinical usefulness of APT imaging in determining the metabolic status of malignant glioma and to compare findings with those from 11C-methionine (Met)-PET. METHODS: This research analyzed APT imaging data from 20 consecutive patients with malignant glioma treated between January 2022 and July 2023. Patients underwent tumor resection and correlations between tumor activity and intensity of APT signal were investigated. We also compared 11C-Met-PET and APT imaging for the same regions of the perifocal tumor invasion area. RESULTS: Clear, diagnostic APT images were obtained from all 20 cases. Mean APT intensity (APTmean) was significantly higher in the glioblastoma (GBM), IDH wild type group (27.2 ± 12.8%) than in other gliomas (6.0 ± 4.7%; p < 0.001). The cut-off APTmean to optimally distinguish between GBM and other malignant gliomas was 12.8%, offering 100% sensitivity and 83.3% specificity. These values for APTmean broadly matched the tumor-to-contralateral normal brain tissue ratio from 11C-Met-PET analysis (r = 0.66). The APT signal was also observed in the gadolinium non-contrast region on T1-weighted imaging, appearing to reflect the surrounding tumor-infiltrated area. CONCLUSIONS: APT imaging can be used to evaluate the area of tumor invasion, similar to 11C-Met-PET. APT imaging revealed low invasiveness in patients and was useful in preoperative planning for tumor resection, facilitating maximum tumor resection including the tumor invasive area.

Photocatalytic Dinitrogen Fixation with Water on High-Phosphorus-Doped Carbon Nitride with Surface Nitrogen Vacancies.

Sunlight-driven photocatalytic dinitrogen (N2) fixation with water at ambient conditions is of vital importance for a sustainable energy society. The efficiency of this reaction, however, is still low because of the difficulty in promoting both water oxidation and N2 reduction reactions. Herein, we report that a high-phosphorus-doped carbon nitride with surface nitrogen vacancies (PCN(V)) synthesized by thermal condensation under a hydrogen (H2) atmosphere using phosphorus oxide (P2O5) as a phosphorus source efficiently promotes N2 fixation. The large numbers of the doped P atoms on the PCN(V)-P2O5 catalysts enhance the oxidation of water, while the N vacancies reduce N2, facilitating efficient ammonia (NH3) generation with an apparent quantum yield at 420 nm of 3.4%. Simulated sunlight illumination of the catalyst in water under N2 bubbling produces NH3 with a solar-to-chemical conversion efficiency of 0.16%, which is the highest efficiency among the previously reported powder photocatalysts.

Polythiophene-Doped Resorcinol-Formaldehyde Resin Photocatalysts for Solar-to-Hydrogen Peroxide Energy Conversion.

The generation of hydrogen peroxide (H2O2) from water and dioxygen by sunlight-driven heterogeneous photocatalysis is a promising method for the artificial photosynthesis of a liquid solar fuel. We previously found that resorcinol-formaldehyde (RF) resin powders prepared by high-temperature hydrothermal synthesis act as highly active semiconductor photocatalysts for H2O2 generation. Herein, we report that RF resin powders doped with poly(3-hexylthiophene-2,5-diyl) (RF/P3HT) exhibit enhanced photocatalytic activities. The highly dispersed P3HT within the resin particles created charge transfer complexes with the conduction band of the resin via electron donation, facilitating efficient transfer of the photogenerated conduction band electrons through P3HT. This enhanced charge separation promoted efficient water oxidation and O2 reduction. The solar-to-chemical conversion efficiency for H2O2 generation on the RF/P3HT resin in water under simulated sunlight irradiation with atmospheric pressure of O2 was ∼1.0%, which is the highest efficiency reported for powder catalysts in artificial photosynthesis.

Enhanced Masses on Contrast-Enhanced Breast: Differentiation Using a Combination of Dynamic Contrast-Enhanced MRI and Quantitative Evaluation with Synthetic MRI.

BACKGROUND: The addition of synthetic MRI might improve the diagnostic performance of dynamic contrast-enhanced MRI (DCE-MRI) in patients with breast cancer. PURPOSE: To evaluate the diagnostic value of a combination of DCE-MRI and quantitative evaluation using synthetic MRI for differentiation between benign and malignant breast masses. STUDY TYPE: Retrospective, observational. POPULATION: In all, 121 patients with 131 breast masses who underwent DCE-MRI with additional synthetic MRI were enrolled. FIELD STRENGTH/SEQUENCE: 3.0 Tesla, T1 -weighted DCE-MRI and synthetic MRI acquired by a multiple-dynamic, multiple-echo sequence. ASSESSMENT: All lesions were differentiated as benign or malignant using the following three diagnostic methods: DCE-MRI type based on the Breast Imaging-Reporting and Data System; synthetic MRI type using quantitative evaluation values calculated by synthetic MRI; and a combination of the DCE-MRI + Synthetic MRI types. The diagnostic performance of the three methods were compared. STATISTICAL TESTS: Univariate (Mann-Whitney U-test) and multivariate (binomial logistic regression) analyses were performed, followed by receiver-operating characteristic curve (AUC) analysis. RESULTS: Univariate and multivariate analyses showed that the mean T1 relaxation time in a breast mass obtained by synthetic MRI prior to injection of contrast agent (pre-T1 ) was the only significant quantitative value acquired by synthetic MRI that could independently differentiate between malignant and benign breast masses. The AUC for all enrolled breast masses assessed by DCE-MRI + Synthetic MRI type (0.83) was significantly greater than that for the DCE-MRI type (0.70, P < 0.05) or synthetic MRI type (0.73, P < 0.05). The AUC for category 4 masses assessed by the DCE-MRI + Synthetic MRI type was significantly greater than that for those assessed by the DCE-MRI type (0.74 vs. 0.50, P < 0.05). DATA CONCLUSION: A combination of synthetic MRI and DCE-MRI improves the accuracy of diagnosis of benign and malignant breast masses, especially category 4 masses. Level of Evidence 4 Technical Efficacy Stage 2 J. MAGN. RESON. IMAGING 2021;53:381-391.

Photocatalytic Dinitrogen Fixation with Water on Bismuth Oxychloride in Chloride Solutions for Solar-to-Chemical Energy Conversion.

Ammonia is an indispensable chemical. Photocatalytic NH3 production via dinitrogen fixation using water by sunlight illumination under ambient conditions is a promising strategy, although previously reported catalysts show insufficient activity. Herein, we showed that ultraviolet light irradiation of a semiconductor, bismuth oxychloride with surface oxygen vacancies (BiOCl-OVs), in water containing chloride anions (Cl-) under N2 flow efficiently produces NH3. The surface OVs behave as the N2 reduction sites by the photoformed conduction band electrons. The valence band holes are consumed by self-oxidation of interlayer Cl- on the catalyst. The hypochloric acid (HClO) formed absorbs ultraviolet light and undergoes photodecomposition into O2 and Cl-. These consecutive photoreactions produce NH3 with water as the electron donor. The Cl- in solution compensates for the removed interlayer Cl- and inhibits catalyst deactivation. Simulated sunlight illumination of the catalyst in seawater stably generates NH3 with 0.05% solar-to-chemical conversion efficiency, thus exhibiting significant potential of the seawater system for artificial photosynthesis.

Resorcinol-formaldehyde resins as metal-free semiconductor photocatalysts for solar-to-hydrogen peroxide energy conversion.

Artificial photosynthesis is a critical challenge in moving towards a sustainable energy future. Photocatalytic generation of hydrogen peroxide from water and dioxygen (H2O + [Formula: see text]O2 → H2O2, ΔG° = 117 kJ mol-1) by sunlight is a promising strategy for artificial photosynthesis because H2O2 is a storable and transportable fuel that can be used directly for electricity generation. All previously reported powder photocatalysts, however, have suffered from low efficiency in H2O2 generation. Here we report that resorcinol-formaldehyde resins, widely used inexpensive polymers, act as efficient semiconductor photocatalysts to provide a new basis for H2O2 generation. Simple high-temperature hydrothermal synthesis (~523 K) produces low-bandgap resorcinol-formaldehyde resins comprising π-conjugated and π-stacked benzenoid-quinoid donor-acceptor resorcinol couples. The resins absorb broad-wavelength light up to 700 nm and catalyse water oxidation and O2 reduction by the photogenerated charges. Simulated sunlight irradiation of the resins stably generates H2O2 with more than 0.5% solar-to-chemical conversion efficiency. Therefore, this metal-free system shows significant potential as a new artificial photosynthesis system.

Photocatalytic Dinitrogen Reduction with Water on Boron-Doped Carbon Nitride Loaded with Nickel Phosphide Particles.

Photocatalytic N2 reduction with water by sunlight irradiation is a challenging issue toward sustainable energy society, but previously reported photocatalysts had suffered from low stability and low activity. We prepared a boron-doped carbon nitride (BCN) semiconductor powder loaded with nickel phosphide particles (Ni2P) as cocatalysts. The Ni2P/BCN catalyst, when photoirradiated in pure water by simulated sunlight under N2 flow, successfully produces NH3 at room temperature. The B doping leads to a positive shift of the valence band level and enhances water oxidation by the photoformed holes. The Ni2P particles efficiently receive the conduction band electrons of BCN, leading to enhanced charge separation of the photoformed hole and electron pairs, and behave as N2 reduction sites. Simulated sunlight irradiation of the catalyst in water stably generates NH3 with 0.010% solar-to-chemical conversion efficiency. This noble-metal-free system therefore shows a significant potential for N2 photofixation.

Doping of Nb5+ Species at the Au-TiO2 Interface for Plasmonic Photocatalysis Enhancement.

Au nanoparticles loaded on semiconductor TiO2 absorb visible light due to their surface plasmon resonance (SPR) and inject the photogenerated hot electrons (ehot-) into the conduction band of TiO2. The separated charges promote oxidation and reduction reactions. The step that determines the rate of the plasmonic photocatalysis on the Au/TiO2 system is the ehot- injection through the Schottky barrier created at the Au-TiO2 interface. In the present work, niobium (Nb5+) oxide species were doped at the Au-TiO2 interface by loading Nb5+ onto the TiO2 surface followed by deposition of Au particles (2 wt % of TiO2). Visible light irradiation of the Au/Nb5+/TiO2 catalysts promotes aerobic oxidation of alcohols with much higher efficiency than that of undoped Au/TiO2. Lewis acidity of the Nb5+ species located at the interface cancels the negative charges of Au and creates a barrier with a narrower depletion layer, promoting tunneling ehot- injection. Efficiency of the ehot- injection depends on the amount of Nb5+ doped. Loading small amounts of Nb5+ (∼0.1 wt % of TiO2) creates mononuclear NbO4 species and shows large activity enhancement. In contrast, loading larger amounts of Nb5+ creates aggregated polynuclear Nb2O5 species. They decrease the electron density of Au particles and weaken their SPR absorption. This suppresses the ehot- generation on the Au particles and decreases the activity of plasmonic photocatalysis.

Photocatalytic Conversion of Nitrogen to Ammonia with Water on Surface Oxygen Vacancies of Titanium Dioxide.

Ammonia (NH3) is an essential chemical in modern society. It is currently manufactured by the Haber-Bosch process using H2 and N2 under extremely high-pressure (>200 bar) and high-temperature (>673 K) conditions. Photocatalytic NH3 production from water and N2 at atmospheric pressure and room temperature is ideal. Several semiconductor photocatalysts have been proposed, but all suffer from low efficiency. Here we report that a commercially available TiO2 with a large number of surface oxygen vacancies, when photoirradiated by UV light in pure water with N2, successfully produces NH3. The active sites for N2 reduction are the Ti3+ species on the oxygen vacancies. These species act as adsorption sites for N2 and trapping sites for the photoformed conduction band electrons. These properties therefore promote efficient reduction of N2 to NH3. The solar-to-chemical energy conversion efficiency is 0.02%, which is the highest efficiency among the early reported photocatalytic systems. This noble-metal-free TiO2 system therefore shows a potential as a new artificial photosynthesis for green NH3 production.

Synthesis of Au Nanoparticles with Benzoic Acid as Reductant and Surface Stabilizer Promoted Solely by UV Light.

Photoreductive synthesis of colloidal gold nanoparticles (AuNPs) from Au3+ is one important process for nanoprocessing. Several methods have been proposed; however, there is no report of a method capable of producing AuNPs with inexpensive reagents acting as both reductant and surface stabilizer, promoted solely under photoirradiation. We found that UV irradiation of water with Au3+ and benzoic acid successfully produces monodispersed AuNPs, where thermal reduction does not occur in the dark condition even at elevated temperatures. Photoexcitation of a benzoate-Au3+ complex reduces Au3+ while oxidizing benzoic acid. The benzoic acid molecules are adsorbed on the AuNPs and act as surface stabilizers. Change in light intensity and benzoic acid amount successfully creates AuNPs with controllable sizes. The obtained AuNPs can easily be redispersed in an organic solvent or loaded onto a solid support by simple treatments.

Carbon Nitride-Aromatic Diimide-Graphene Nanohybrids: Metal-Free Photocatalysts for Solar-to-Hydrogen Peroxide Energy Conversion with 0.2% Efficiency.

Solar-to-chemical energy conversion is a challenging subject for renewable energy storage. In the past 40 years, overall water splitting into H2 and O2 by semiconductor photocatalysis has been studied extensively; however, they need noble metals and extreme care to avoid explosion of the mixed gases. Here we report that generating hydrogen peroxide (H2O2) from water and O2 by organic semiconductor photocatalysts could provide a new basis for clean energy storage without metal and explosion risk. We found that carbon nitride-aromatic diimide-graphene nanohybrids prepared by simple hydrothermal-calcination procedure produce H2O2 from pure water and O2 under visible light (λ > 420 nm). Photoexcitation of the semiconducting carbon nitride-aromatic diimide moiety transfers their conduction band electrons to graphene and enhances charge separation. The valence band holes on the semiconducting moiety oxidize water, while the electrons on the graphene moiety promote selective two-electron reduction of O2. This metal-free system produces H2O2 with solar-to-chemical energy conversion efficiency 0.20%, comparable to the highest levels achieved by powdered water-splitting photocatalysts.

Coumarin-Spiropyran Dyad with a Hydrogenated Pyran Moiety for Rapid, Selective, and Sensitive Fluorometric Detection of Cyanide Anion.

We synthesized a coumarin-spiropyran dyad with a hydrogenated pyran moiety (2), behaving as an off-on type fluorescent receptor for rapid, selective, and sensitive detection of cyanide anion (CN(-)) in aqueous media. The receptor itself shows almost no fluorescence with a quantum yield < 0.01, due to the delocalization of π-electrons over the molecule. Selective nucleophilic addition of CN(-) to the spirocarbon of the molecule rapidly promotes spirocycle opening within only 3 min. This leads to localization of π-electrons on the coumarin moiety and exhibits strong light-blue fluorescence at 459 nm with very high quantum yield (0.52). As a result of this, the receptor facilitates rapid, selective, and sensitive fluorometric detection of CN(-) as low as 1.0 µM.

Hot-Electron-Induced Highly Efficient O2 Activation by Pt Nanoparticles Supported on Ta2O5 Driven by Visible Light.

Aerobic oxidation on a heterogeneous catalyst driven by visible light (λ >400 nm) at ambient temperature is a very important reaction for green organic synthesis. A metal particles/semiconductor system, driven by charge separation via an injection of "hot electrons (e(hot)(-))" from photoactivated metal particles to semiconductor, is one of the promising systems. These systems, however, suffer from low quantum yields for the reaction (<5% at 550 nm) because the Schottky barrier created at the metal/semiconductor interface suppresses the e(hot)(-) injection. Some metal particle systems promote aerobic oxidation via a non-e(hot)(-)-injection mechanism, but require high reaction temperatures (>373 K). Here we report that Pt nanoparticles (∼5 nm diameter), when supported on semiconductor Ta2O5, promote the reaction without e(hot)(-) injection at room temperature with significantly high quantum yields (∼25%). Strong Pt-Ta2O5 interaction increases the electron density of the Pt particles and enhances interband transition of Pt electrons by absorbing visible light. A large number of photogenerated e(hot)(-) directly activate O2 on the Pt surface and produce active oxygen species, thus promoting highly efficient aerobic oxidation at room temperature.

Effects of substituents on fluorometric detection of cyanide anions by indolium-coumarin dyads.

We synthesized an indolium­coumarin dyad (1) and its derivatives with ­Cl (2), ­N(CH3)2 (3), or ­NO2 (4) substituent, and used them for fluorometric detection of cyanide anions (CN(-)) in aqueous media. All of the dyads exhibit fluorescence enhancement by CN(-) via a nucleophilic interaction of CN(-) with the indolium carbon atoms. Their fluorescence response and selectivity to CN(-), however, depend strongly on the substituents. Ab initio calculation and kinetic analysis were performed to verify the behaviors. Substitution of electron-withdrawing groups (2 and 4) increases the electrophilicity of the indolium carbon. This decreases the activation enthalpy for the nucleophilic interaction with CN(-) and facilitates rapid CN(-) sensing. Compound 4 with very high electrophilicity, however, also promotes nucleophilic interaction with OH(-) in the solution, resulting in decreased CN(-) selectivity. As a result of this, the ­Cl-substituted compound 2 containing the indolium carbon with appropriate electrophilicity facilitates rapid (within 1 min) and selective CN(-) detection.

Spiropyran as a reusable chemosensor for selective colorimetric detection of aromatic thiols.

Design of optical molecular probes for selective detection of aromatic thiols has attracted much attention. Although several types of probes have been proposed, all of them exhibit colorimetric or fluorometric response via irreversible reaction with aromatic thiols and cannot be reused. Here we report that a spiropyran dye is the first example of a reusable chemosensor for aromatic thiols. A colorless spiropyran dye () dissolved in aqueous media containing aromatic thiols is selectively isomerized to the colored merocyanine form in the dark. In contrast, visible light irradiation of the merocyanine form promotes successful reversion to the colorless spirocyclic form. Kinetic absorption analysis and ab initio calculations of the transition states revealed that this colorimetric response in the dark is ascribed to the decrease in activation energy for isomerization via the nucleophilic interaction between the aromatic thiol and the olefinic carbon of the dye.

Sunlight-driven hydrogen peroxide production from water and molecular oxygen by metal-free photocatalysts.

Design of green, safe, and sustainable process for the synthesis of hydrogen peroxide (H2 O2 ) is a very important subject. Early reported processes, however, require hydrogen (H2 ) and palladium-based catalysts. Herein we propose a photocatalytic process for H2 O2 synthesis driven by metal-free catalysts with earth-abundant water and molecular oxygen (O2 ) as resources under sunlight irradiation (λ>400 nm). We use graphitic carbon nitride (g-C3 N4 ) containing electron-deficient aromatic diimide units as catalysts. Incorporating the diimide units positively shifts the valence-band potential of the catalysts, while maintaining sufficient conduction-band potential for O2 reduction. Visible light irradiation of the catalysts in pure water with O2 successfully produces H2 O2 by oxidation of water by the photoformed valence-band holes and selective two-electron reduction of O2 by the conduction band electrons.

Sunlight-Driven Nitrate-to-Ammonia Reduction with Water by Iron Oxyhydroxide Photocatalysts.

The photocatalytic reduction of harmful nitrates (NO3-) in strongly acidic wastewater to ammonia (NH3) under sunlight is crucial for the recycling of limited nitrogen resources. This study reports that a naturally occurring Cl--containing iron oxyhydroxide (akaganeite) powder with surface oxygen vacancies (ß-FeOOH(Cl)-OVs) facilitates this transformation. Ultraviolet light irradiation of the catalyst suspended in a Cl--containing solution promoted quantitative NO3--to-NH3 reduction with water under ambient conditions. The photogenerated conduction band electrons promoted the reduction of NO3--to-NH3 over the OVs. The valence band holes promoted self-oxidation of Cl- as the direct electron donor and eliminated Cl- was compensated from the solution. Photodecomposition of the generated hypochlorous acid (HClO) produced O2, facilitating catalytic reduction of NO3--to-NH3 with water as the electron donor in the entire system. Simulated sunlight irradiation of the catalyst in a strongly acidic nitric acid (HNO3) solution (pH ∼ 1) containing Cl- stably generated NH3 with a solar-to-chemical conversion efficiency of ∼0.025%. This strategy paves the way for sustainable NH3 production from wastewater.

Mechanism for different fluorescence response of a coumarin-amide-dipicolylamine linkage to Zn(II) and Cd(II) in water.

A coumarin-amide-dipicolylamine linkage (L) was synthesized and used as a fluorescent receptor for metal cations in water. The receptor dissolved in water with neutral pH shows almost no fluorescence due to the photoinduced electron transfer (PET) from the amide and amine nitrogens to the excited state coumarin moiety. Coordination of Zn(2+) or Cd(2+) with L creates strong fluorescence at 437 or 386 nm, respectively, due to the suppression of PET. In contrast, other metal cations scarcely show fluorescence enhancement. IR, NMR, and potentiometric analysis revealed that both Zn(2+) and Cd(2+) are coordinated with two pyridine N, amine N, and amide O; however, the Zn(2+) center is also coordinated with a hydroxide anion (OH(-)). The structure difference for Zn and Cd complexes results in longer- and shorter-wavelength fluorescence. Ab initio calculations revealed that π electrons on the excited state Cd complex are delocalized over the molecules and the Cd complex shows shorter-wavelength emission. In contrast, π electrons of OH(-)-coordinated Zn complex are localized on the coumarin moiety. This increases the electron density of coumarin moiety and shows longer-wavelength fluorescence.