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Interventional radiology is one of the most widely used treatment options for abdominal abnormality. Due to new dose limitations, radiation is a hazard that needs to be considered when choosing the international treatment technique. The aim of this study was to measure the effective/equivalent doses and to investigate the associated factors correlating with the doses during Transarterial Chemoembolization (TACE) and Percutaneous Transhepatic Biliary Drainage (PTBD) for radiologists, technologists and nurses involved with the treatment. This prospective study reports occupational dose per procedure of 57 cases (TACE = 42, PTBD = 15) in a Thailand hospital spanning one year. All staff included in this study wore 30 nanoDot Optically Stimulated Luminescence Dosimeter for measuring doses at 7 bodily locations. The average dose area product and cumulative doses was 151.3 Gy·cm2, 1,185.1 mGy during TACE and 21.3 Gy·cm2, 212.2 mGy during PTBD. The radiation exposure of the radiologists was significantly higher than technologists and nurses (p-value < 0.05). The lead protection equipment was a dose-reducing factor which decreased the dose up to 93%. The present study also contributes to the establishment of an individual dose location report and identifies significant correlations between associated factors and dose values. The left hand (1.2 mSv) and the left eye (1.1 mSv) showed maximum doses during the PTBD procedure. The exceeded dose over the limitation was observed in the left eye. We concluded that the dose feedback was able to increase awareness of the occupation staff. So, dose monitoring, updating education and regular training could be applied simply and effectively to improve skills, while reducing the occupational dose. [ABSTRACT FROM AUTHOR]

Graphene is a good support for immobilizing catalysts, due to its large theoretical specific surface area and high electric conductivity. Solid chemical converted graphene, in a form with multiple layers, decreases the practical specific surface area. Building pores in graphene can increase specific surface area and provide anchor sites for catalysts. In this study, we have prepared porous graphene (PG) via the process of equilibrium precipitation followed by carbothermal reduction of ZnO. During the equilibrium precipitation process, hydrolyzed N,N-dimethylformamide sluggishly generates hydroxyl groups which transform Zn2+ into amorphous ZnO nanodots anchored on reduced graphene oxide. After carbothermal reduction of zinc oxide, micropores are formed in PG. When the Zn2+ feeding amount is 0.12 mmol, the average size of the Pt nanoparticles on PG in the catalyst is 7.25 nm. The resulting Pt/PG exhibited the highest turnover frequency of 511.6 min−1 for ammonia borane hydrolysis, which is 2.43 times that for Pt on graphene without the addition of Zn2+. Therefore, PG treated via equilibrium precipitation and subsequent carbothermal reduction can serve as an effective support for the catalytic hydrolysis of ammonia borane. [ABSTRACT FROM AUTHOR]

Boron nitride (BN) is a wide-bandgap material for various applications in modern nanotechnologies. In the technology of material science, computational calculations are prerequisites for experimental works, enabling precise property prediction and guidance. First-principles methods such as density functional theory (DFT) are capable of capturing the accurate physical properties of materials. However, they are limited to very small nanoparticle sizes (<2 nm in diameter) due to their computational costs. In this study, we present, for the first time, an important computational approach to DFT calculations for BN materials deposited on different substrates. In particular, we predict the total energy and cohesive energy of a variety of face-centered cubic (FCC) and hexagonal close-packed (HCP) boron nitrides on different substrates (Ni, MoS2, and Al2O3). Hexagonal boron nitride (h-BN) is the most stable phase according to our DFT calculation of cohesive energy. Moreover, an experimental validation equipped with a molecular beam epitaxy system for the epitaxial growth of h-BN nanodots on Ni and MoS2 substrates is proposed to confirm the results of the DFT calculations in this report. [ABSTRACT FROM AUTHOR]

Graphene is a good support for immobilizing catalysts, due to its large theoretical specific surface area and high electric conductivity. Solid chemical converted graphene, in a form with multiple layers, decreases the practical specific surface area. Building pores in graphene can increase specific surface area and provide anchor sites for catalysts. In this study, we have prepared porous graphene (PG) via the process of equilibrium precipitation followed by carbothermal reduction of ZnO. During the equilibrium precipitation process, hydrolyzed N,N-dimethylformamide sluggishly generates hydroxyl groups which transform Zn2+ into amorphous ZnO nanodots anchored on reduced graphene oxide. After carbothermal reduction of zinc oxide, micropores are formed in PG. When the Zn2+ feeding amount is 0.12 mmol, the average size of the Pt nanoparticles on PG in the catalyst is 7.25 nm. The resulting Pt/PG exhibited the highest turnover frequency of 511.6 min−1 for ammonia borane hydrolysis, which is 2.43 times that for Pt on graphene without the addition of Zn2+. Therefore, PG treated via equilibrium precipitation and subsequent carbothermal reduction can serve as an effective support for the catalytic hydrolysis of ammonia borane.

Boron nitride (BN) is a wide-bandgap material for various applications in modern nanotechnologies. In the technology of material science, computational calculations are prerequisites for experimental works, enabling precise property prediction and guidance. First-principles methods such as density functional theory (DFT) are capable of capturing the accurate physical properties of materials. However, they are limited to very small nanoparticle sizes (2, and Al2O3). Hexagonal boron nitride (h-BN) is the most stable phase according to our DFT calculation of cohesive energy. Moreover, an experimental validation equipped with a molecular beam epitaxy system for the epitaxial growth of h-BN nanodots on Ni and MoS2 substrates is proposed to confirm the results of the DFT calculations in this report.

Antimony (Sb) is a potential candidate anode for potassium-ion batteries (PIBs) owing to its high theoretical capacity. However; in the process of potassium alloying reaction; the huge volume expansion (about 407%) leads to pulverization of active substance as well as loss of electrical contact resulting in rapidly declining capacity. Herein; uniformly dispersed Sb-Nanodot in carbon frameworks (Sb-ND@C) were constructed by in situ confined polymerization of ionic liquids. Attributed to the uniformly dispersed Sb-ND and confinement effect of carbon frameworks; as anode for PIBs; Sb-ND@C delivered a superior rate capability (320.1 mA h g−1 at 5 A g−1) and an outstanding cycling stability (486 mA h g−1 after 1000 cycles; achieving 89.8% capacity retention). This work offers a facile route to prepare highly dispersed metal-Nanodot via the in situ polymerization of ionic liquid for high-performance metal-ion batteries [ABSTRACT FROM AUTHOR]

We fabricated superconducting and ferromagnetic nanostructures, which are intended for applications in transmission electron microscopy (TEM), in a commercial sample holder that can be cooled using liquid helium. Nanoscale superconducting quantum-interference devices (nanoSQUIDs) with sub-100 nm nanobridge Josephson junctions (nJJs) were prepared at a distance of ~300 nm from the edges of a 2 mm × 2 mm × 0.05 mm substrate. Thin-film TiN-NbN-TiN heterostructures were used to optimize the superconducting parameters and enhance the oxidation and corrosion resistance of nJJs and nanoSQUIDs. Non-hysteretic I(V) characteristics of nJJs, as well as peak-to-peak quantum oscillations in the V(B) characteristics of the nanoSQUIDs with an amplitude of up to ~20 µV, were obtained at a temperature ~5 K, which is suitable for operation in TEM. Electron-beam lithography, high-selectivity reactive ion etching with pure SF6 gas, and a naturally created undercut in the Si substrate were used to prepare nanoSQUIDs on a SiN membrane within ~500 nm from the edge of the substrate. Permalloy nanodots with diameters down to ~100 nm were prepared on SiN membranes using three nanofabrication methods. High-resolution TEM revealed that permalloy films on a SiN buffer have a polycrystalline structure with an average grain dimension of approximately 5 nm and a lattice constant of ~0.36 nm. The M(H) dependences of the permalloy films were measured and revealed coercive fields of 2 and 10 G at 300 and 5 K, respectively. These technologies are promising for the fabrication of superconducting electronics based on nJJs and ferromagnetic nanostructures for operation in TEM. [ABSTRACT FROM AUTHOR]

From the Principle of Radiation Protection for workers, radiation shielding is a way to reduce radiation exposure. This study aimed to assess the efficacy of shielding device in reducing effective doses experienced by radiological technologists working in a PET/CT examination room by measuring the equivalent dose with and without shielding device in phantoms using 18F 518 MBq at the National Cyclotron and PET Centre, Chulabhorn Hospital, Thailand. The phantoms were placed at the radiological technologists’ working position and nanoDotTM OSL dosimeters were attached at eyes, thyroid, and chest positions for 30 minutes. The experimental results showed that the effective dose measured with and without the radiation shields were 0.249 ± 0.030 mSv and 0.250 ± 0.020 mSv, respectively. Furthermore, data analysis revealed no statistically significant difference (p >0.05) between the two conditions. Hence, it was concluded that the use of radiation shields could not reduce the effective dose.

We investigate the ferromagnetic properties of the conducting filament (CF) nanodots formed on epitaxial BiFeO3 (BFO) thin film, which exhibit resistive switching behavior. 50-nm thick epitaxial BFO thin film was grown on Nb-doped SrTiO3 single crystal substrates through pulsed laser deposition. The ferroelectric microcapacitor fabricated using the epitaxial BFO thin film shows excellent ferroelectric properties with a remanent polarization of approximately 32 μC/cm2 and unipolar resistive switching behavior. CF nanodots with a diameter of approximately 16 nm are formed in the local region of the BFO thin film through conductive atomic force microscopy. Generally, ferromagnetic materials exhibit superparamagnetism, on a scale of tens of nanometers, as a result of the thermal energy of the magnetic moments. In this study, magnetic force microscopy demonstrates that the CF nanodot possesses ferromagnetism. It is suggested that exchange coupling between the CF nanodot and surrounding BFO causes the ferromagnetism of the nanodot. Our study provides new insight on the design of multistate memory cells with resistive switching and magnetic spin ordering, for application in high-density information storage media.

Fabrication and development of effective visible-light-responsive photocatalysts are required to tackle critical environmental issues. The aim of this study was to develop a nanocomposite material with improved photocatalytic activity for the degradation of industrial dyes such as Reactive Orange-16 (RO-16), Reactive Blue (RB-222), Reactive Yellow-145 (RY-145), and Disperse Red-1 (DR-1) without the need for a post-separation process after use. Here we report the hydrothermal synthesis of nanodots of Co1-xZnxFe2O4 (x = 0.3, 0.5 and 0.7), coated with polyaniline, by in situ polymerization. The Co1-xZnxFe2O4 nanodots, coated with polyaniline (PANI) nanograins, facilitated optical properties by easily capturing visible light. X-ray Diffraction (XRD) patterns and Scanning Electron Microscopy (SEM) images have confirmed the single-phase spinel structure of Co1-xZnxFe2O4 nanodot and nano-pore size of the Co1-xZnxFe2O4/PANI nanophotocatalyst. The specific surface area of the Brunauer–Emmett–Teller (BET) of the Co1-xZnxFe2O4/PANI photocatalyst was determined to be 24.50 m2/g by multipoint analysis. The final Co1-xZnxFe2O4/PANI (x = 0.5) nanophotocatalyst showed high efficiency in the catalytic degradation of toxic dyes (∼98% within 5 min), with good mechanical stability and recyclability under visible light irradiation. The nanophotocatalyst was re-used and its efficiency was largely maintained, even after seven cycles (∼82%) of degradation. The effects of various parameters, such as initial dye concentration, nanophotocatalyst concentration, initial pH of dye solution, and reaction kinetics were studied. According to the Pseudo-first-order kinetic model, photodegradation data followed the first-order reaction rate (R2 > 0.95) of degradation of dyes. In conclusion, a simple and low-cost synthesis process, speedy degradation and excellent stability of polyaniline-coated Co1-xZnxFe2O4 nanophotocatalyst could be used as a promising photocatalyst for dye-wastewater treatment.

Although radiotherapy has become indispensable for tumor treatment in recent years, the inevitable side effects of high-dose radiation on the normal tissue and deficiency of appropriate radiosensitizers without long-term body retention that do not cause potential toxicity limit further clinical applications to a certain extent. Herein, we rationally synthesized BiOI nanodots coated with M1 macrophage membrane (BiOI@M) by utilizing their coordination interaction. With two high-atomic-number elements and ultrasmall size, the prepared BiOI nanodots not only enhanced radiosensitivity by reactive oxygen species under X-ray irradiation in vitro, but also could be excreted quickly by kidneys. Meanwhile, the M1 macrophage membrane functioned as a highly desirable carrier with long-circulating and tumor-targeting capability. As a result, treatment with as-prepared BiOI@M could improve the therapeutic outcome of radiotherapy in a xenograft mouse model and reduce the potential toxicity of nanoparticles. Simultaneously, BiOI nanodots exhibited excellent CT imaging ability as contrast agents to visualize biodistribution in vivo and to monitor tumor growth. Therefore, our work demonstrated the preparation of a tumor targeting and renal clearable radiosensitizer and offered a potential approach to enhance the radiotherapy efficacy of hepatocellular carcinoma.

CoOOH nanodots decorated hematite (CoOOH/Fe 2 O 3) photoanode was successfully fabricated. The CoOOH/Fe 2 O 3 exhibits a high photocurrent density of 1.92 mA cm−2 at 1.23 V vs. RHE, which is ca. 2.6 times to that of bare Fe 2 O 3 , and a ca. 110 mV cathodic shift of the onset potential. CoOOH plays important roles that suppress the surface recombination and improve the charge transfer. [Display omitted] • CoOOH nanodot was rationally designed and in-situ decorated on Fe 2 O 3 photoanode. • CoOOH/Fe 2 O 3 exhibited superior photoelectrochemical activity for water oxidation. • CoOOH could suppress charge recombination by passivating the surface states of Fe 2 O 3. • CoOOH provided active sites and facilitated the charge transfer for water oxidation. Photoelectrochemical (PEC) water splitting has been considered as an alternative process to produce green hydrogen. However, the energy conversion efficiency of PEC systems was still limited by the inefficient photoanode. Cocatalysts decoration is regarded as an efficient strategy for improving PEC performance of photoanode. In this work, nanodot-like cobalt (oxy)hydroxides was rationally decorated on hematite to fabricate CoOOH/Fe 2 O 3 photoanode. The resulted CoOOH/Fe 2 O 3 exhibits a high photocurrent density of 1.92 mA cm−2 at 1.23 V vs. RHE, which is 2.6 times than that of bare Fe 2 O 3. In addition, the onset potential displays a cathodic shift of ca. 110 mV, indicating that CoOOH can efficiently accelerate water oxidation kinetics over Fe 2 O 3. The comprehensive PEC and electrochemical characterizations reveal that CoOOH could not only provide abundant accessible Co active sites for water oxidation, but also could passivate the surface states of Fe 2 O 3 , thus increase the carrier density and decrease the interfacial resistance. As a result, the PEC water oxidation performance over Fe 2 O 3 was significantly boosted. This work supports that the roles of CoOOH cocatalyst is generic and such CoOOH could be used for other semiconductor-based photoanodes for outstanding PEC water splitting performance. [ABSTRACT FROM AUTHOR]

A plasmonic refractive index sensor focused on a square ring resonator (SRR) and a circular ring resonator (CRR), coupled to a metal-insulator-metal (MIM) bus waveguide and a rectangular stub is proposed. The structure is numerically investigated using the Finite Element Method (FEM) by positioning nanodots (NDs) at highly confined E-filed region. The evident effect of refractive index (RI) on resonant wavelength is employed to sense the materials. A maximum sensitivity of 2850 nm/RIU was obtained by the optimized design, and associate figure of merit (FOM) and quality factor (Q-factor) recorded are 105.95 and 71.71, respectively. The structure's high tolerance for possible manufacturing flaws makes it easy-to-manufacture. With compact size, superior performance, and narrow resonance dip, the proposed sensor is expected to be an excellent candidate for biosensing, gas sensing and lab-on-chip applications. [ABSTRACT FROM AUTHOR]

The development of new microbicidal compounds has become a top priority due to the emergence and spread of drug-resistant pathogenic microbes. In this study, blue-emitting and positively charged carbon dots (CDs), called Du-CDs, were fabricated for the first time utilizing the natural product extract of endophyte Diaporthe unshiuensis YSP3 as raw material through a one-step solvothermal method, which possessed varied functional groups including amino, carboxyl, hydroxyl, and sulfite groups. Interestingly, Du-CDs exhibited notably enhanced antimicrobial activities toward both bacteria and fungi as compared to the natural product extract of YSP3, with low minimum inhibitory concentrations. Moreover, Du-CDs significantly inhibited the formation of biofilms. Du-CDs bound with the microbial cell surface via electronic interaction or hydrophobic interaction entered the microbial cells and were distributed fully inside the cells. Du-CDs caused cell membrane damage and/or cell division cycle interruption, resulting in microbial cell death. Moreover, Du-CDs exhibited an improved antimicrobial effect and accelerated wound healing ability with good biocompatibility in the mouse model. Overall, we demonstrate that the formation of CDs from fungal natural products presents a promising and potential means to develop novel antimicrobial agents with great fluorescence, improved microbiocidal effect and wound healing capacity, and good biosafety for combating microbial infections.

Antimony (Sb) is a potential candidate anode for potassium-ion batteries (PIBs) owing to its high theoretical capacity. However; in the process of potassium alloying reaction; the huge volume expansion (about 407%) leads to pulverization of active substance as well as loss of electrical contact resulting in rapidly declining capacity. Herein; uniformly dispersed Sb-Nanodot in carbon frameworks (Sb-ND@C) were constructed by in situ confined polymerization of ionic liquids. Attributed to the uniformly dispersed Sb-ND and confinement effect of carbon frameworks; as anode for PIBs; Sb-ND@C delivered a superior rate capability (320.1 mA h g−1 at 5 A g−1) and an outstanding cycling stability (486 mA h g−1 after 1000 cycles; achieving 89.8% capacity retention). This work offers a facile route to prepare highly dispersed metal-Nanodot via the in situ polymerization of ionic liquid for high-performance metal-ion batteries

Si1– x Sn x and Si1– x –y Ge x Sn y polycrystalline thin layers were grown using Sn nanodots as crystal nuclei. Si1– x Sn x crystallization occurred around Sn nanodots, and the substitutional Sn content was estimated as high as 1.5%. In the case of the poly-Si1– x –y Ge x Sn y, Ge and Si were deposited simultaneously on the Sn nanodots, however, Ge was preferentially incorporated into the Sn nanodots, resulting in the formation of the poly-Si1– x –y Ge x Sn y with amorphous Si residue. It was found that the poly-Si1– x Sn x formed by the Sn nanodots mediated formation can be used as the new virtual substrate to be alloyed with Ge, namely the 2-step formation process consisting of poly-Si1– x Sn x crystallization and Ge alloying with the poly-Si1– x Sn x is the effective process for the poly-Si1– x –y Ge x Sn y formation. This non-equilibrium process with achieving crystallization resulted in the substitutional Si and Sn content in the as-grown poly-Si1– x –y Ge x Sn y as high as 10.8% and 3.5%, respectively. [ABSTRACT FROM AUTHOR]

Laser-induced near-field effect, which confines the laser energy in a nano scale region to be enhanced, allows the laser fabrication with a resolution much smaller than the wavelength. Owing to such a high fabrication resolution, the laser-induced near-field fabrication has been attracting much attention as a tool for the surface nanostructuring. In this report, we introduce a novel method based on the laser-induced near-field reduction using a femtosecond laser by which gold nanocluster arrays are formed on substrates with the assistance of self-assembled silica microspheres. In the laser near-field reduction, the incident laser is focused in the vicinity of the backside of the silica microspheres to initiate synthesis of gold nanoparticles, followed by creation of gold nanoclusters by continuous growth of the gold nanoparticles along the silica microsphere surfaces. In addition, laser-treated MoS2 quantum dots are mixed in the gold precursor to increase the reduction efficiency for the formation of spherical gold nanoclusters. The gold nanocluster arrays provide potential applications for plasmonic devices.

Clusters have an atomically precise structure and possess functions significantly different from those of atoms, nanocrystals, and bulk solids. Here, we report a strategy of fabricating cluster nanodots and nanodot supracrystals based on the self-assembly principle of lipids. Firstly, we synthesized a pyramid Janus heterocluster consisting of two types of clusters [polyoxometalate (POM) and polyhedral oligomeric silsesquioxane (POSS)] covalently linked by a dendritic linker. Subsequently, the heterocluster self-assembled into core-corona nanodots in which individual POSS clusters distribute on the surface of a POM core in the POSS-preferred solvent. The nanodots further self-assembled into nanodot supracrystals as the solvent gradually evaporated. Reconstruction of the structural characteristics of the supracrystals by coarse-grained molecular simulations confirmed this two-step self-assembly process. Mathematical analysis indicated that solvation promotes the discontinuous distribution of individual POSS clusters on the surface of the POM cores. The results of this work will open up prospects for the preparation of artificial virus-like nanodots and highly ordered cluster-assembled nanomaterials for advanced applications. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the feasibility of using optically stimulated luminescence dosimeters (OSLDs), nanoDots, for the determination of an average glandular dose (AGD) with a specific digital breast tomosynthesis (DBT) system, whereas the X‐ray tube was fixed (2D mode) and moved (3D mode). The entrance surface air kerma (ESAK) was measured by placing the nanoDots on the surface of a polymethyl methacrylate (PMMA) phantom with 25, 28, and 34 kV W/Rh techniques. The experimental setup of the ESAK measurement was simulated using a Monte Carlo simulation code to determine the ESAK and the backscatter factor (BSF). The AGD was calculated by dividing the ESAK values over the corresponding BSF factors for each PMMA phantom thickness and multiplying the AGD conversion factors. The AGD determination by the nanoDots variated within ±5% for both 2D and 3D modes, compared to those determined using an ionization chamber. The results were similarly observed for the simulation, except for the 25 kV on the 3D mode. Regarding the International Atomic Energy Agency technical reports series number 457, the nanoDots can be used for the AGD determination with realistic 2D and 3D image acquisitions based on ±10% uncertainty. [ABSTRACT FROM AUTHOR]

According to International Commission of Radiological Protection, the equivalent dose limit for the eye lens for occupational exposure is recommended to be 20 mSv yr -1 , averaged over 5 years, with no single year above 50 mSv. Some studies reported the measurement of assistant's lens exposure in diagnostic computed tomography (CT) examinations, but further investigation is still required in the association between the lens dose for assistants and various dose parameters. Therefore, we measured the assistant's lens exposure using small optically stimulated luminescence dosimeters. The type of occupation, type of assistance, total scan time, total mAs, total scan length, and dose-length product (DLP) were recorded and analyzed in association with air kerma at the lens position. The assistance was classified into four types: 'assisted ventilation,' 'head holding,' 'body holding,' and 'raising patient's arm.' The air kerma of lens position was not significantly different for each assistance type ( p < 0.05, Kruskal-Wallis test). Further, the lens doses for assistants correlated with DLP, but with various strengths of correlation with the assistance type and were influenced by the distance from the CT gantry. In conclusion, lens dose during assistance and DLP demonstrated the strongest correlation. 'Raising patient's arm' and 'head holding' exhibited stronger correlations, which required less table movement during the CT scan than 'assisted ventilation' and 'body holding'., (© 2024 Society for Radiological Protection. Published on behalf of SRP by IOP Publishing Limited. All rights reserved.)

[Display omitted] • Heterostructure of ultrafine FeOOH nanodots on CoAl-LDH nanosheets was developed. • FeOOH@CoAl-LDH showed a superior and stable OER activity. • The heterostructure could optimize the adsorption free energy of OER intermediates. The supported and dispersed ultrafine active species for electrocatalytic water oxidation are quite promising for the high intrinsic activity. A novel heterostructure of ultrafine FeOOH nanodots with an average size of 2.3 nm supported on CoAl-LDH nanosheets, is constructed by a facile method under ambient conditions. The as-prepared FeOOH@CoAl-LDH shows a strong interfacial interaction upon the formation of heterostructure, and is demonstrated as a highly efficient and stable electrocatalyst that demands 272 mV to attain 50 mA cm−2 and exhibits a Tafel slope of 40 mV dec−1. Moreover, density functional theory calculations manifest the coupling of FeOOH with CoAl-LDH can effectively decrease the energy barrier during the water oxidation process by optimizing the adsorption free energy of intermediates in the reaction pathway. The successful development of FeOOH@CoAl-LDH can shed light on the design of novel electrocatalysts that can fully take advantages of small size, heterostructure and synergistic effect. [ABSTRACT FROM AUTHOR]

Nanodots composed of multiferroic cobalt-substituted BiFeO 3 , a ferroelectric ferromagnet at room temperature, are fabricated by pulsed laser deposition using anodized porous alumina as masks. The obtained nanodots are approximately 60 nm in diameter, more than 10 nm in thickness, and approximately 70 Gbit/in. 2 in density. Piezoresponse and magnetic force microscopies show both ferroelectricity and ferromagnetism with a single-domain nature. It is also found that the dot with 190 nm diameter had multidomain vortex ferroelectric and magnetic structures indicating the strong magnetoelectric coupling. The single-domain cobalt-substituted BiFeO 3 nanodots are suitable for verifying magnetization reversal by the electric field, which is the first step in the development of low-power-consumption nonvolatile magnetic memory devices.

We summarize our experimental findings in the arrays of Ni80Fe20 circular nanodots with diameter 300 nm and thickness 20 nm ≤ L ≤ 100 nm, probed by broadband ferromagnetic resonance spectroscopy in the absence of external magnetic field. Spin excitation modes related to the vortex core gyrotropic dynamics were observed in the gigahertz frequency range. Micromagnetic simulations revealed that they are flexure oscillations of the vortex core string with n = 0, 1, 2 nodes along the dot thickness. It was found that for L > 70 nm the intensity of more complicated n = 1 vortex gyrotropic mode is unexpectedly higher than the one of the lowest n = 0 gyrotropic mode. This behavior was clarified on the basis of the inhomogeneous vortex mode phase profiles extracted from micromagnetic simulations and calculated analytically. Precise measurements of the dependence of resonance frequency of the vortex n = 0 mode on the dot thickness demonstrated a clear maximum around L = 70 nm, that was theoretically explained by introducing a vortex mass, which is a result of the vortex distortion due to interaction with spin waves having azimuthal indices m = ±1. Finally, several azimuthal spin-wave modes having curled structure at the dot top and bottom faces were found in the spectrum of the dots with thicknesses L ≥ 40 nm. [ABSTRACT FROM AUTHOR]

Purpose: Optically stimulated luminescence dosimeter (OSLDs) are often used to make in vivo dose measurements. Most users calibrate the OSLDs using the software provided by the vendor which typically is intended for doses up to about 300 cGy with an uncertainty of ±5.5%. OSLDs that reach that dose are then discarded, and new ones are purchased and calibrated. A method has been developed for reusing OSLDs and predicting dose sensitivity up to at least 7000 cGy. Materials and methods: The nanoDot OSLDs used in this study were routinely used to do in vivo measurements for TBI patients. Instead of using the calibration program provided by the vendor, each nanoDot was bleached to about 100 counts (~0.1 cGy), then calibrated with 50 cGy to produce a sensitivity specific to each nanoDot prior to the patient measurement. NanoDots were read in the hardware mode and the sensitivity factor was applied manually to subsequent patient in‐vivo TBI measurements. This was followed by bleaching prior to the next use. The changes of nanoDot sensitivity relative to accumulated dose were analyzed among nine nanoDots. In addition, a method to predict a nanoDot's sensitivity was investigated which aims to reduce the number of sensitivity calibrations while retaining dosimetric accuracy. Results: Individual per‐use nanodot calibrations were performed up to 7000 cGy for 37 clinical TBI patients. Among the nine nanoDots analyzed in this paper, the sensitivity vs accumulated dose decreased linearly up to about 3000 cGy, with linear fitting curve R2 values above 0.93. After 3000 cGy of accumulated dose, the sensitivity started to plateau and tended to increase by 6000 cGy, with 2nd order polynomial curve R2 values above 0.94. With this finding, an efficient and accurate method to predict nanoDots' sensitivities was developed. With the method applied to the nine OSLDs, a total of 127 sensitivities were predicted and retrospectively compared with measured sensitivities. The predicted sensitivities agreed with measured sensitivities within ±4.0% with an average of −0.8%. Conclusions: This study is the first to demonstrate the reuse of nanoDot OSLDs on numerous patients with accumulated dose up to 7000 cGy. Our nanoDot re‐usage methodology is accurate, cost‐saving and feasible. A time‐saving method is also provided that allows a user to reuse a nanoDot with sensitivities predicted with better accuracy than the 5.5% value provided by the conventional batch calibration method. [ABSTRACT FROM AUTHOR]

The efficient incoupling of light into particular fibers at large angles is essential for a multitude of applications; however, this is difficult to achieve with commonly used fibers due to low numerical aperture. Here, we demonstrate that commonly used optical fibers functionalized with arrays of metallic nanodots show substantially improved large-angle light-collection performances at multiple wavelengths. In particular, we show that at visible wavelengths, higher diffraction orders contribute significantly to the light-coupling efficiency, independent of the incident polarization, with a dominant excitation of the fundamental mode. The experimental observation is confirmed by an analytical model, which directly suggests further improvement in incoupling efficiency through the use of powerful nanostructures such as metasurface or dielectric gratings. Therefore, our concept paves the way for high-performance fiber-based optical devices and is particularly relevant within the context of endoscopic-type applications in life science and light collection within quantum technology.

Mass production of manganese-doped silica nanowires (Mn-SiONWs) have been achieved by a simple method of thermal evaporation of SiO and Mn powders. Tunneling electron microscope studies reveal manganese silicide nanodots with an average diameter of 3.52 nm embedded in the SiONWs. Based on the characterizations of the novel microstructures, a plausible growth mechanism for the Mn-SiONWs was proposed by considering the catalytic role of SiO and Ostwald Ripening process during the growth. Quantitative simulation was then performed to understand the narrow size distribution of the nanodots, and the critical radius about 1 nm for the nanodot formation was obtained. Finally, the photoluminescence properties and their relationship with the microstructures were studied. • Mass production of Mn-doped nanodot embedded SiONWs (Mn-SiONWs) were achieved by a simple method of thermal evaporation. • A plausible growth mechanism was proposed by considering the catalytic role of SiO and Ostwald Ripening process during the growth. • Quantitative simulation was then performed to understand the narrow size distribution of the Mn-rich nanodots. [ABSTRACT FROM AUTHOR]

Noble metal nanodots have been applied to plasmonic devices, catalysts, and highly sensitive detection in bioinstruments. We have been studying the fabrications of them through a laser-induced dot transfer (LIDT) technique, a type of laser-induced forward transfer (LIFT), in which nanodots several hundred nm in diameter are produced via a solid–liquid–solid (SLS) mechanism. In the previous study, an interference laser processing technique was applied to LIDT, and aligned Au nanodots were successfully deposited onto an acceptor substrate in a single shot of femtosecond laser irradiation. In the present experiment, Pt thin film was applied to this technique, and the deposited nanodots were measured by scanning electron microscopy (SEM) and compared with the Au nanodots. A typical nanodot had a roundness fr=0.98 and circularity fcirc=0.90. Compared to the previous experiment using Au thin film, the size distribution was more diffuse, and it was difficult to see the periodic alignment of the nanodots in the parameter range of this experiment. This method is promising as a method for producing large quantities of Pt particles with diameters of several hundred nm.

Accurate methods that can continuously detect low concentrations of hydrogen peroxide (H2O2) have a huge application potential in biological, pharmaceutical, clinical and environmental analysis. Luminescent probes and nanomaterials are used for fabrication of sensors for H2O2 that can be applied for these purposes. In contrast to previous reviews focusing on the chemical design of molecular probes for H2O2, this mini-review highlights the latest luminescent nanoparticular materials and new luminescent optical sensors for H2O2 in terms of the nanomaterial composition and luminescent receptor used in the sensors. The nanomaterial section is subdivided into schemes based on gold nanoparticles, polymeric nanoparticles with embedded enzymes, probes showing aggregation-induced emission enhancement, quantum dots, lanthanide-based nanoparticles and carbon based nanomaterials, respectively. Moreover, the sensors are ordered according to the type of luminescent receptor used within the sensor membranes. Among them are lanthanide complexes, metal-ligand complexes, oxidic nanoparticles and organic dyes. Further, the optical sensors are confined to those that are capable to monitor the concentration of H2O2 in a sample over time or are reusable. Optical sensors responding to gaseous H2O2 are not covered. All nanomaterials and sensors are characterized with respect to the analytical reaction towards H2O2, limit of detection (LOD), analytical range, electrolyte, pH and response time/incubation time. Applications to real samples are given. Finally, we assess the suitability of the nanomaterials to be used in membrane-based sensors and discuss future trends and perspectives of these sensors in biomedical research.

We report the ubiquitous radiographic characteristics of optically stimulated luminescence dosimeters (OSLD) so called nanoDot OSLDs (Landauer Inc., Glendwood, IL). The X-ray irradiations were performed in free air ambiance to inspect the repeatability, the reproducibility, the signal depletion, the element correction factors (ECFs), the dose response and the energy dependence. Repeatability of multiple readouts after single irradiation to 10 mGy revealed a coefficient of variation below 3%, while the reproducibility in repeated irradiation-readout-annealing cycles was above 2%. The OSL signal depletion for three nanoDots with simultaneous irradiation to 20 mGy and sequential readouts of 25 times displayed a consistent signal reduction ≈0.5% per readout with R 2 values over 0.98. ECFs for individual OSLDs were varied from 0.97 to 1.03. In the entire dose range under 80 kV, a good linearity with an R 2 exceeding 0.99 was achieved. Besides, the percentage difference between OSLD and ion-chamber dose was less than 5%, which was superior to TLD. The X-ray photon irradiated energy response factors (between 0.76 and 1.12) in the range of 40–150 kV (26.1–61.2 keV) exhibited significant energy dependence. Indeed, the nanoDot OSLDs disclosed good repeatability, reproducibility and linearity. The OSLDs measured doses were closer to ion-chamber doses than that of TLD. It can be further improved up to ≈3% by applying the individual dosimeter ECF. On top, the energy dependent uncertainties can be minimized using the energy correction factors. It is established that the studied nanoDot OSLDs are prospective for measuring entrance dose in general radiographic practices. [ABSTRACT FROM AUTHOR]

Modulation of reactive oxygen and nitrogen species in a tumor could be exploited for nanotherapeutic benefits. We investigate the antitumor effect in Walker-256 carcinosarcoma of magnetic nanodots composed of doxorubicin-loaded Fe 3 O 4 nanoparticles combined with electromagnetic fields. Treatment using the magnetic nanodot with the largest hysteresis loop area (3402 erg/g) had the greatest antitumor effect with the minimum growth factor 0.49 ± 0.02 day –1 (compared to 0.58 ± 0.02 day –1 for conventional doxorubicin). Electron spin resonance spectra of Walker-256 carcinosarcoma treated with the nanodots, indicate an increase of 2.7 times of free iron (that promotes the formation of highly reactive oxygen species), using the nanodot with the largest hysteresis loop area, compared to conventional doxorubicin treatment as well as increases in ubisemiquinone, lactoferrin, NO-FeS-proteins. Hence, we provide evidence that the designed magnetic nanodots can modulate the tumor redox state. We discuss the implications of these results for cancer nanotherapy. [ABSTRACT FROM AUTHOR]

A novel two-step nano-patterning method is proposed to fabricate epitaxial ferroelectric BiFeO 3 (BFO) nanoring array, which maintains well-epitaxial structure and possesses strong ferroelectricity demonstrated by X-ray diffraction (XRD) and piezoresponse force microscopy (PFM). The ferroelectric polarizations were examined by PFM, revealing the reversible switching behavior under an electric field. This novel method could also be extended to other oxide material systems. The fabrication of high quality ferroelectric nanoring structure provides the possibility to explore novel functionalities (e.g., ferroelectric vortices) and offers application potentials for the high-density non-volatile memory devices. [ABSTRACT FROM AUTHOR]