Spectral computed tomography (CT) advances conventional CT by enabling material-specific imaging. This technique leverages the energy dependence of X-ray attenuation. However, the polychromatic spectra typical for laboratory and industrial CT limit the sensitivity of spectral CT methods. In this work, band-pass filtering of X-ray energies in a laboratory CT scanner is explored for the purpose of increasing spectral sensitivity. In the Rigaku nano3DX, X-ray generation is tuned to maximize the fraction of characteristic X-rays in the overall energy spectrum. This fraction is further enhanced by strategic filtering and processing of CT datasets to produce semi-monochromatic images centered on characteristic emission lines relevant to the analysis. Reconstructed CT data can then be interpreted as linear attenuation coefficients for the given emission line in the scanned volume, with potential for further spectral and spectroscopic applications in a laboratory setting, particularly for low-Z materials.

Physiological coronary branching at the bifurcation has a constant fractal ratio (FR) of the diameter of the mother vessel to the sum of daughter vessels on quantitative coronary angiography (QCA). We sought to investigate the FR of diseased coronary bifurcations using QCA and intravascular ultrasound (IVUS) and its impact on late lumen loss after percutaneous coronary intervention (PCI). In multicentre prospective studies of the J-REVERSE and 3D OCT Bifurcation Registry, 402 and 109 bifurcations treated with stenting that completed QCAs and IVUS examinations, respectively were analysed. FR was investigated at the reference sites pre-PCI and the minimum lumen diameter (MLD) post-PCI. In the QCA analysis, constant FR was observed in the pre-PCI reference (0.62 ± 0.08) and in the post-PCI MLD site (0.74 ± 0.10), which was greater (p < 0.05). In the IVUS analysis, the constant FR in the post-PCI MLD site (0.67 ± 0.06) was similar to that in the pre-PCI reference (0.66 ± 0.06) and close to the physiological FR value (0.678). The fourth quintile of pre-PCI reference FR in the IVUS analysis showed numerically least late lumen loss in proximal main vessel (MV) (0.16 ± 0.22 mm) and distal MV (0.13 ± 0.32 mm) and significantly less in the side branch compared to higher FR quintile (− 0.14 ± 0.27 mm vs. 0.10 ± 0.19 mm, p = 0.004), while no relationship was found in the QCA analysis. FR in the diseased coronary bifurcation was more accurately assessed on IVUS than on QCA, and the accomplishment of physiological FR might lead to less late lumen loss after bifurcation PCI.

To meet the increasing demand for small-scale NH3 production, catalysts that work under milder conditions than those of the Haber–Bosch process are essential. In this study, Ru clusters and nanoparticles were impregnated on five different CeO2 supports to prepare Ru/CeO2 catalysts for NH3 synthesis at 400 °C and 0.1 MPa. The basicity of the CeO2 support and Ru particle size significantly influenced the catalytic activity. The catalytic activity increased with decreasing Ru particle size, reaching the maximum of 200 mmol gRu−1 h−1 at 1 nm, which is ascribed to a high proportion of unique active sites different from the B5-type sites. Our findings demonstrate that Ru cluster catalysts are advantageous over Ru nanoparticle catalysts for NH3 synthesis.

Gold clusters were deposited in the pores of the zeolite H-ZSM-5 using pulsed laser ablation of an Au target placed in acetone containing the zeolite particles. The Au clusters in the pores of the zeolite were observed using high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). The images revealed that most pores in the zeolite contained Au clusters. Additionally, the position of each Au atom in the clusters was determined by analyzing the HAADF-STEM images. The results revealed that when three Au atoms were visible in a pore, they were planar and aligned mostly parallel to the viewing plane, and when more than three Au atoms were present, a three-dimensional structure was formed because of the steric hindrance of the pore wall. Therefore, the Au clusters were deposited in the zeolite pores. Furthermore, most clusters in the pores were distributed near the surface of the channels of the zeolite particles.

Misalignment of the rotation axis causes severe artifacts in X-ray computed tomography. Calibration of this parameter is often insufficient for sub-micron resolution measurements and needs to be corrected during the post-processing. This correction can be accelerated by various automatic methods. These vary in mechanisms and performance, making them suitable for different use-cases. This work summarizes existing automatic methods for estimating the rotation axis in X-ray computed tomography, with a focus on sub-micron applications. Some of the methods are implemented and compared in the context of a laboratory sub-micron scanner to demonstrate practical considerations of this task.

Laser ablation (LA) in a liquid was used for loading clusters on various supporting materials. An advantage of LA in a liquid is that the cluster generation conditions are almost independent of the material. Gold, silver, and copper clusters were implanted in the pores of zeolite particles using a laser ablation of an Au, Ag, or a Cu plate in water dispersed with zeolite ZSM-5 particles. We found the evidence for Au and Ag clusters trapped in the pores of the zeolite through LA in water that the samples fluoresced between 400 and 500 nm under 350 nm excitation after calcination at 300 °C. However, the sample with Cu did not exhibit photoluminescence because the Cu particles produced by LA in water were oxidized. The Au and Ag clusters were estimated to be composed of ∼6 atoms based on the relationship between the HOMO–LUMO energy gap and the cluster size predicted using the jellium model.

Objectives: Cerebral microbleeds (CMBs), which can be detected by gradient-echo T2*-weighted magnetic resonance imaging (MRI), represent small chronic brain hemorrhages caused by structural abnormalities in cerebral small vessels. CMBs are known to be a potential predictor of future stroke, and are associated with age, various cardiovascular risk factors, cognitive impairment, and the use of antithrombotic drugs. Patients with coronary artery disease (CAD) are at potentially high risk of CMBs due to the presence of coexistent conditions. However, little is known about CMBs in patients with CAD. We aimed to identify the factors associated with the presence of CMBs among patients with CAD. Methods: We evaluated 356 consecutive patients [mean age, 72 10 years; men = 276 (78%)] with angiographically proven CAD who underwent T2*-weighted brain MRI. The brain MRI was assessed by researchers blinded to the patients' clinical details. Results: CMBs were found in 128 (36%) patients. Among 356 patients, 119 (33%) had previously undergone per cutaneous coronary intervention (PCI), and 26 (7%) coronary artery bypass grafting (CABG). There was no significant relationship between CMBs and sex, hypertension, dyslipidemia, diabetes mellitus, anticoagulation therapy, antiplatelet therapy, or prior PCI. CMBs were significantly associated with advanced age, previous CABG, eGFR, non-HDL cholesterol, carotid artery disease, long-term antiplatelet therapy, and long-term dual antiplatelet therapy (DAPT) using univariate logistic regression analysis. The multivariate logistic regression analysis showed that longterm antiplatelet therapy (odds ratio, 1.73; 95% CI, 1.06 2.84; P = 0.03) or longterm DAPT (odds ratio, 2.92; 95% CI, 1.39 6.17; P = 0.004) was significantly associated with CMBs after adjustment for confounding variables. Conclusions: CMBs were frequently observed in patients with CAD and were significantly associated with long-term antiplatelet therapy, especially long-term DAPT.

X-ray microscopes adopting computed tomography enable nondestructive 3D visualization of biological specimens at micron-level resolution without conventional 2D serial sectioning that is a destructive/laborious method and is routinely used for analyzing renal biopsy in clinical diagnosis of kidney diseases. Here we applied a compact commercial system of laboratory-based X-ray microscope to observe a resin-embedded osmium-stained 1-mm strip of a mouse kidney piece as a model of renal biopsy, toward a more efficient diagnosis of kidney diseases. A reconstructed computed tomography image from several hours of data collection using CCD detector allowed us to unambiguously segment a single nephron connected to a renal corpuscle, which was consistent with previous reports using serial sectioning. Histogram analysis on the segmented nephron confirmed that the proximal and distal tubules were distinguishable on the basis of their X-ray opacities. A 3D rendering model of the segmented nephron visualized a convoluted structure of renal tubules neighboring the renal corpuscle and a branched structure of efferent arterioles. Furthermore, another data collection using scientific complementary metal-oxide semiconductor detector with a much shorter data acquisition time of 15 min provided similar results from the same samples. These results suggest a potential application of the compact laboratory-based X-ray microscope to analyze mouse renal biopsy.

Gold clusters trapped on opaque substrate particles were produced using pulsed laser ablation. The ablation laser irradiated the target Au plate in a liquid dispersed with opaque substrate particles. It was found that the rate of thermal diffusion from the smaller particle that absorbed laser energy was greater than that from the larger particle; therefore, it is less likely to increase the temperature. Subsequently, the Au target was ablated more efficiently than the opaque substrate particles dispersed in the liquid. Therefore, the opaque particles were barely miniaturized and remained intact. The interaction mechanism of the deposition of the Au particle produced by laser ablation on the substrate particles was investigated by measuring the zeta potential of the substrate particles. The positively charged Au particles were adsorbed by ion exchange with positively charged Y2O3 substrate particles. In contrast, they interacted via electrostatic interactions with negatively charged α-quartz and ZSM-5 zeolite particles.

We prepared metal alloy nanoparticles by pulsed laser ablation of the boundary between jointed target metal plates of Au and Ag in purified water. When the spot size radius of the focused laser on the target was 2.5 mm, separate Au nanoparticles and Ag nanoparticles were mainly observed with slight alloying. In contrast, when the spot size radius was 0.25 mm, the ejected Au and Ag atoms were found to be more mixed, efficiently forming Au and Ag alloy nanoparticles. The mixing distance of Au and Ag atoms was estimated to be ∼0.5 mm. The dynamics of the plasma plume and the cavitation and their interaction with Au and Ag atoms were quite complex. Hence, we assumed that during plasma plume formation and cavitation formation, Au and Ag atoms diffuse in the plasma plume and cavitation as a uniform medium with a maximum temperature and minimum viscosity. It was suggested that the fast mixing of Au and Ag atoms occurred inside the plasma plume, taking the high temperature, several thousand K of the plasma plume into account. Moreover, the mixing was promoted by the overlapping of plasma plumes, which were generated on Au and Ag plates separately, owing to explosive plasma motions. Then, the alloy nanoparticles were formed in the cavitation bubble where Au and Ag atoms were spatially distributed by plasma plumes. The mixing of the atoms in the cavitation bubble was not likely based on the mixing distance.

We synthesized three-way catalysts consisting of rhodium, platinum, or palladium clusters confined in zeolites produced by pulsed laser ablation (LA) in liquid acetone. A plate of the catalytic metals was irradiated with a pulsed laser in an acetone suspension of zeolite powder. The catalytic properties of the samples were evaluated for the three-way reaction, CO oxidation reaction, and NO–CO reaction. The zeolite-confined clusters generated by LA had higher thermal stability than those supported on α-Quartz (αQ) particles produced by LA. The cluster size matched those of the pores, resulting in a large contact area with the surface of the pores. Therefore, the metal clusters supported by zeolite were efficiently stabilized in the zeolite pores by a larger number of Rh–O–Si bonds than those supported on αQ particles produced by LA. Moreover, the zeolite-confined clusters generated by LA had higher catalytic activity than clusters on zeolite produced by traditional metal-ion exchange followed by reduction.

For three-dimensional observation of unstained bio-specimens using X-ray microscopy with computed tomography (CT), one main problem has been low contrast in X-ray absorption. Here we introduce paraffin-mediated contrast enhancement to visualize biopsy samples of mouse kidney using a laboratory-based X-tray microscope. Unlike conventional heavy-atom staining, paraffin-mediated contrast enhancement uses solid paraffin as a negative contrast medium to replace water in the sample. The medium replacement from water to paraffin effectively lowers the absorption of low-energy X-rays by the medium, which eventually enhances the absorption contrast between the medium and tissue. In this work, paraffin-mediated contrast enhancement with 8 keV laboratory X-rays was used to visualize cylindrical renal biopsies with diameters of about 0.5 mm. As a result, reconstructed CT images from 19.4 h of data collection achieved cellular-level resolutions in all directions, which provided 3D structures of renal corpuscles from a normal mouse and from a disease model mouse. These two structures with and without disease allowed a volumetric analysis showing substantial volume differences in glomerular subregions. Notably, this nondestructive method presents CT opacities reflecting elemental composition and density of unstained tissues, thereby allowing more unbiased interpretation on their biological structures.

In this paper, we propose a novel radiochromic film (RCF)-based computed tomography (CT) dosimetry method, which is different from the method based on CT dose index. RCF dosimetry using Gafchromic QA2 films was performed using two lengths of film-folding phantoms. The phantom was exposed to X-ray CT through a single scan, while the RCF was sandwiched between the phantoms. We analysed the dose profile curve in two directions to investigate the dose distribution. We observed a difference in the dose distribution as the phantom size changed. Our results contradict with the results of previous studies such as Monte Carlo simulation or direct measurement. The ability to visually evaluate 2D dose distributions is an advantage of RCF dosimetry over other methods. This research investigated the ability of 2D X-ray CT dose evaluation using RCF and film-folding phantom.

The application of lithium metal as a negative electrode in all-solid-state batteries shows promise for optimizing battery safety and energy density. However, further development relies on a detailed understanding of the chemo-mechanical issues at the interface between the lithium metal and solid electrolyte (SE). In this study, crack formation inside the sulfide SE (Li3PS4: LPS) layers during battery operation was visualized using in situ Xray computed tomography (X-ray CT). Moreover, the degradation mechanism that causes short-circuiting was proposed based on a combination of the X-ray CT results and scanning electron microscopy images after short-circuiting. The primary cause of short-circuiting was a chemical reaction in which LPS was reduced at the lithium interface. The LPS expanded during decomposition, thereby forming small cracks. Lithium penetrated the small cracks to form new interfaces with fresh LPS on the interior of the LPS layers. This combination of reduction-expansion-cracking of LPS was repeated at these new interfaces. Lithium clusters eventually formed, thereby generating large cracks due to stress concentration. Lithium penetrated these large cracks easily, finally causing short-circuiting. Therefore, preventing the reduction reaction at the interface between the SE and lithium metal is effective in suppressing degradation. In fact, LPS-LiI electrolytes, which are highly stable to reduction, were demonstrated to prevent the repeated degradation mechanism. These findings will promote all-solid-state lithium-metal battery development by providing valuable insight into the design of the interface between SEs and lithium, where the selection of a suitable SE is vital.

In this article, we introduce a new ring artifacts reduction procedure that combines several ideas from existing methods into one complex and robust approach with a goal to overcome their individual weaknesses and limitations. The procedure differentiates two types of ring artifacts according to their cause and character in computed tomography (CT) data. Each type is then addressed separately in the sinogram domain. The novel iterative schemes based on relative total variations (RTV) were integrated to detect the artifacts. The correction process uses the image inpainting, and the intensity deviations smoothing method. The procedure was implemented in scope of lab-based X-ray nano CT with detection systems based on charge-coupled device (CCD) and scientific complementary metal–oxide–semiconductor (sCMOS) technologies. The procedure was then further tested and optimized on the simulated data and the real CT data of selected samples with different compositions. The performance of the procedure was quantitatively evaluated in terms of the artifacts’ detection accuracy, the comparison with existing methods, and the ability to preserve spatial resolution. The results show a high efficiency of ring removal and the preservation of the original sample’s structure.

Manipulation of protein crystals using an external field is a topic of growing interest in several fields, such as X-ray crystallography and crystal processing. The aim of this study was to develop a method for manipulating crystals using a magnetic field by assembling iron oxide nanoparticles inside a lysozyme crystal. Poly(vinylpyrrolidone)-stabilised iron oxide nanoparticles, prepared through pulsed laser ablation in a solution, were preferentially incorporated in the {101} sectors rather than in the {110} sectors of the tetragonal lysozyme crystal, similar to the gold (Au) and platinum (Pt) nanoparticles studied previously. To keep the crystals intact in solutions, the outer surface of the nanoparticle-assembled crystal was coated with a pure lysozyme crystal and the coated crystals were introduced into a solution containing glycerol. The pure lysozyme crystal at the surface of the nanoparticle-assembled crystal is less likely to dissolve compared with the nanoparticle-assembled crystal itself. Additionally, glycerol has a delaying effect on the dissolution of crystals owing to its high viscosity. The authors successfully demonstrated the handling of protein crystals by commercially available needle magnets in solution. This method requires a simple device with a low cost, without any requirement for control conditions and energy, thus facilitating easy and inexpensive handling of the crystal.

Vanadium nanoparticles were produced by laser ablation of a vanadium metal plate in a reductive aqueous solution. Transmission electron microscopy and electron energy-loss spectroscopy revealed that the nanoparticles had an average diameter of 13.2 nm, and consisted of a metallic vanadium core with a slightly oxidised surface. Although vanadium nanoparticles produced in pure water dissolved quickly, mainly as V(V) ions, those produced in a reductive aqueous solution with trisodium citrate and sodium dodecyl sulphate were dispersed for a few hours.

Objectives To evaluate the efficacy and safety of additional drug-coated balloon (DCB) angioplasty after directional coronary atherectomy (DCA) for coronary bifurcation lesions. Background The optimal therapy for bifurcation lesions has not been established, even in the drug-eluting stent era. DCA possibly prevents plaque and carina shift in bifurcation lesions by plaque debulking; however, the efficacy of combined DCA and DCB (DCA/DCB) for bifurcation lesions remains unclear. Methods This multicenter registry retrospectively recruited patients with bifurcation lesions who underwent DCA/DCB and follow-up angiogram at 6-15 months. The primary endpoint was the 12-month target vessel failure (TVF) rate. The secondary endpoints were procedure-related major complications, major cardiovascular events at 12 months, restenosis at 12 months, target lesion revascularization (TLR) at 12 months, and target vessel revascularization (TVR) at 12 months. Results We enrolled 129 patients from 16 Japanese centers. One hundred and four lesions (80.6%) were located around the left main trunk bifurcations. No side branch compromise was found intraoperatively. Restenosis was observed in three patients (2.3%) at 12 months. TLR occurred in four patients (3.1%): 3 (2.3%) in the main vessel and 1 (0.8%) in the ostium of the side branch at 12 months. TVF incidence at 12 months was slightly higher in 14 patients (10.9%), and only two patients (1.6%) had symptomatic TVR. One patient (0.8%) had non-target vessel-related myocardial infarction. Conclusions Our data suggested that DCA/DCB provided good clinical outcomes and minimal side branch damage and could be an optimal non-stent percutaneous coronary intervention strategy for bifurcation lesions.

Background The visualization of internal 3D-structure of tissues at micron resolutions without staining by contrast reagents is desirable in plant researches, and it can be achieved by an X-ray computed tomography (CT) with a phase-retrieval technique. Recently, a laboratory-based X-ray microscope adopting the phase contrast CT was developed as a powerful tool for the observation of weakly absorbing biological samples. Here we report the observation of unstained pansy seeds using the laboratory-based X-ray phase-contrast CT. Results A live pansy seed within 2 mm in size was simply mounted inside a plastic tube and irradiated by in-house X-rays to collect projection images using a laboratory-based X-ray microscope. The phase-retrieval technique was applied to enhance contrasts in the projection images. In addition to a dry seed, wet seeds on germination with the poorer contrasts were tried. The phase-retrieved tomograms from both the dry and the wet seeds revealed a cellular level of spatial resolutions that were enough to resolve cells in the seeds, and provided enough contrasts to delineate the boundary of embryos manually. The manual segmentation allowed a 3D rendering of embryos at three different stages in the germination, which visualized an overall morphological change of the embryo upon germination as well as a spatial arrangement of cells inside the embryo. Conclusions Our results confirmed an availability of the laboratory-based X-ray phase-contrast CT for a 3D-structural study on the development of small seeds. The present method may provide a unique way to observe live plant tissues at micron resolutions without structural perturbations due to the sample preparation.

In cone-beam X-ray computed tomography (CT), distances between the source, object, and detector influence the visual fidelity and voxel size of a reconstructed volume. Calibration using reference objects is an appropriate tool for preventing errors in the estimates of these distances. There is, however, a lack of such objects for high-resolution systems with a small field of view (FoV). In this work, we propose a method to measure the distances mentioned above, improving the determination of voxel size. We use a custom reference object suitable for a FoV of around one millimeter. Many approaches have been developed for this calibration task and discussed in the literature, but none apply to CT scanners with a small FoV and a cone-beam magnification close to one. The proposed method thus aims to provide a calibration procedure for such devices. A Rigaku Nano3DX CT scanner has been calibrated through this method and used for practical validation of the method's accuracy. Results have shown that this approach allows for accurate calibration, which leads to improvements in reconstruction quality and accuracy of voxel size determination.