Nonmagnetic framboid and associated iron nanoparticles with a space-weathered feature from asteroid Ryugu.

Extraterrestrial minerals on the surface of airless Solar System bodies undergo gradual alteration processes known as space weathering over long periods of time. The signatures of space weathering help us understand the phenomena occurring in the Solar System. However, meteorites rarely retain the signatures, making it impossible to study the space weathering processes precisely. Here, we examine samples retrieved from the asteroid Ryugu by the Hayabusa2 spacecraft and discover the presence of nonmagnetic framboids through electron holography measurements that can visualize magnetic flux. Magnetite particles, which normally provide a record of the nebular magnetic field, have lost their magnetic properties by reduction via a high-velocity (>5 km s-1) impact of a micrometeoroid with a diameter ranging from 2 to 20 µm after destruction of the parent body of Ryugu. Around these particles, thousands of metallic-iron nanoparticles with a vortex magnetic domain structure, which could have recorded a magnetic field in the impact event, are found. Through measuring the remanent magnetization of the iron nanoparticles, future studies are expected to elucidate the nature of the nebular/interplanetary magnetic fields after the termination of aqueous alteration in an asteroid.

Optimal plastic recycling system and technology development could accelerate decarbonization: A case study from Japan.

This study provided a geographic and technical matching approach supporting low-carbon style recycling systems, demonstrated using polyvinyl chloride waste (PVCW) generated in 2018 in Mie Prefecture, Japan. From a carbon dioxide (CO2) emission basis, mechanical/material recycling (MR) and energy recovery facilities were all allocated full capacity; however, parts of chemical recycling facilities were excluded in the optimal solutions. From the spatial distribution of the allocated result, we confirmed a trend that to achieve the minimum total emissions, the matchings from pretreatment to recycling facilities were done based on a nearby priority rule. From an emission reduction basis, MR accounted for the major proportion of total reductions which was similar to that accessed from an emission basis. Thus, the promotion of MR should be prioritized at the current technical level when optimizing emissions of the whole lifecycle. The number of facilities allocated were substantially reduced; meanwhile, the averaged emission reductions per ton of PVCW disposed were increased from the current level (2.93) to the near-future level (4.99 t-CO2 t-1). Thus, we concluded that this optimization under a higher technical level was effective to make the current recycling system with more emission reductions (low-carbon environmental effect) and require fewer disposal facilities (cost-saving economic effect). Meanwhile, certain long-distance routes found in solutions implied that technical parameters were more important than geolocation parameters to achieve maximum emission reductions.

A dehydrated space-weathered skin cloaking the hydrated interior of Ryugu.

Without a protective atmosphere, space-exposed surfaces of airless Solar System bodies gradually experience an alteration in composition, structure and optical properties through a collective process called space weathering. The return of samples from near-Earth asteroid (162173) Ryugu by Hayabusa2 provides the first opportunity for laboratory study of space-weathering signatures on the most abundant type of inner solar system body: a C-type asteroid, composed of materials largely unchanged since the formation of the Solar System. Weathered Ryugu grains show areas of surface amorphization and partial melting of phyllosilicates, in which reduction from Fe3+ to Fe2+ and dehydration developed. Space weathering probably contributed to dehydration by dehydroxylation of Ryugu surface phyllosilicates that had already lost interlayer water molecules and to weakening of the 2.7 µm hydroxyl (-OH) band in reflectance spectra. For C-type asteroids in general, this indicates that a weak 2.7 µm band can signify space-weathering-induced surface dehydration, rather than bulk volatile loss.

Oxygen isotopes of anhydrous primary minerals show kinship between asteroid Ryugu and comet 81P/Wild2.

The extraterrestrial materials returned from asteroid (162173) Ryugu consist predominantly of low-temperature aqueously formed secondary minerals and are chemically and mineralogically similar to CI (Ivuna-type) carbonaceous chondrites. Here, we show that high-temperature anhydrous primary minerals in Ryugu and CI chondrites exhibit a bimodal distribution of oxygen isotopic compositions: 16O-rich (associated with refractory inclusions) and 16O-poor (associated with chondrules). Both the 16O-rich and 16O-poor minerals probably formed in the inner solar protoplanetary disk and were subsequently transported outward. The abundance ratios of the 16O-rich to 16O-poor minerals in Ryugu and CI chondrites are higher than in other carbonaceous chondrite groups but are similar to that of comet 81P/Wild2, suggesting that Ryugu and CI chondrites accreted in the outer Solar System closer to the accretion region of comets.

A comprehensive review of domestic-open waste burning: recent trends, methodology comparison, and factors assessment.

Open burning is a waste management practice performed by many people worldwide, especially in developing countries. Lack of detailed data of open burning practices may lead to a misinterpretation during data analysis, especially when estimating global/local emissions and assessing risks. This study presents a comprehensive review of current research trends, methodological assessments, and factors behind open waste burning practices from published literature. This review used systematic methods such as PRISMA 2020 methodology, a bibliometric approach, and qualitative content analysis to determine and assess 84 articles related to open burning. The results show that environmental risks and emission factors related to open burning incidents at the landfill or residential level are preferable topics that will be rising in the years to come. Coupling methods such as a transect-based approach with a questionnaire survey and mobile-static plume sampling to determine the activities and incidents as baseline data for risk assessment will help researchers gain a robust dataset of open burning emission inventory. In addition, it was found that environmental knowledge and awareness levels influence open burning practices, thereby opening up opportunities for future research. Supplementary Information: The online version contains supplementary material available at 10.1007/s10163-022-01430-9.

Activity and emission inventory of open waste burning at the household level in developing countries: a case study of Semarang City.

In this study, total burned household waste and the potential emissions released from waste burning in Semarang City, Indonesia, were estimated. Waste piles were monitored using the transect walk survey method in 16 sub-districts of Semarang City. Carbon monoxide (CO), carbon dioxide (CO2), hydrocarbon (HC), nitrous oxide (NOx), and total particulate matter (TPM) were directly analyzed through a simulation of waste combustion. The potential emissions from other pollutants were predicted by multiplying the weight of the burned waste by the emission factors available in the literature. The estimated waste burned in Semarang City in 2020-2021 was 58.8 Gg/year, or approximately 9.70% of the total waste generated in Semarang City. This estimation exceeds local government estimates of 2020 by two-fold. Peri-urban areas (both inner and outer) were identified as the most significant contributors to waste burning. Further, garden waste was the most burned waste (73.61%), followed by plastic waste (17.45%). Other wastes, including paper, leather, textile, rubber, and food, were also burned. Overall, a decrease in the activity of waste burning is an important step for reducing the potential of air pollution and climate change. Supplementary Information: The online version contains supplementary material available at 10.1007/s10163-022-01371-3.

Retraction notice to "Gelatin scaffold combined with bone morphogenetic protein-4 induces odontoblast-like cell differentiation involving integrin profile changes, autophagy-related gene 10, and Wnt5 sequentially in human induced pluripotent stem cells" [Differentiation 93 (2017) 1-14].

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the authors, with the approval of the Editor-in-Chief. The journal was initially contacted by the corresponding author to report the unavailability of the raw data of the results presented by the article, as well as the similarity between the Western blots from Figure 11A (MMP-3) and Figure 11C (MMP-3). Also, a significant amount of text has been reused from the articles that the authors have previously published in the Experimental Cell Research 341 (2016) 92-104 https://doi.org/10.1016/j.yexcr.2016.01.010 and the Journal of Biological Chemistry 289 (2014) 14380-14391 https://doi.org/10.1074/jbc.M113.526772. All of the authors except Nobuaki Ozeki and Taiki Hiyama have reportedly agreed to retract the article. N. Ozeki left Aichi Gakuin University in March 2018 and does not respond to co-authors inquiries, while T. Hiyama left Aichi Gakuin University and could not be reached. The authors deeply regret this error and any inconvenience it may have caused.

Iron whiskers on asteroid Itokawa indicate sulfide destruction by space weathering.

Extraterrestrial iron sulfide is a major mineral reservoir of the cosmochemically and astrobiologically important elements iron and sulfur. Sulfur depletion on asteroids is a long-standing, yet unresolved phenomenon that is of fundamental importance for asteroid evolution and sulfur delivery to the Earth. Understanding the chemistry of such environments requires insight into the behavior of iron sulfides exposed to space. Here we show that troilite (FeS) grains recovered from the regolith of asteroid 25143 Itokawa have lost sulfur during long-term space exposure. We report the wide-spread occurrence of metallic iron whiskers as a decomposition product formed through irradiation of the sulfide by energetic ions of the solar wind. Whisker growth by ion irradiation is a novel and unexpected aspect of space weathering. It implies that sulfur loss occurs rapidly and, furthermore, that ion irradiation plays an important role in the redistribution of sulfur between solids and gas of the interstellar medium.

Generation of realistic virtual nodules based on three-dimensional spatial resolution in lung computed tomography: A pilot phantom study.

PURPOSE: The aim of this feasibility study using phantoms was to propose a novel method for obtaining computer-generated realistic virtual nodules in lung computed tomography (CT). METHODS: In the proposed methodology, pulmonary nodule images obtained with a CT scanner are deconvolved with the point spread function (PSF) in the scan plane and slice sensitivity profile (SSP) measured for the scanner; the resultant images are referred to as nodule-like object functions. Next, by convolving the nodule-like object function with the PSF and SSP of another (target) scanner, the virtual nodule can be generated so that it has the characteristics of the spatial resolution of the target scanner. To validate the methodology, the authors applied physical nodules of 5-, 7- and 10-mm-diameter (uniform spheres) included in a commercial CT test phantom. The nodule-like object functions were calculated from the sphere images obtained with two scanners (Scanner A and Scanner B); these functions were referred to as nodule-like object functions A and B, respectively. From these, virtual nodules were generated based on the spatial resolution of another scanner (Scanner C). By investigating the agreement of the virtual nodules generated from the nodule-like object functions A and B, the equivalence of the nodule-like object functions obtained from different scanners could be assessed. In addition, these virtual nodules were compared with the real (true) sphere images obtained with Scanner C. As a practical validation, five types of laboratory-made physical nodules with various complicated shapes and heterogeneous densities, similar to real lesions, were used. The nodule-like object functions were calculated from the images of these laboratory-made nodules obtained with Scanner A. From them, virtual nodules were generated based on the spatial resolution of Scanner C and compared with the real images of laboratory-made nodules obtained with Scanner C. RESULTS: Good agreement of the virtual nodules generated from the nodule-like object functions A and B of the phantom spheres was found, suggesting the validity of the nodule-like object functions. The virtual nodules generated from the nodule-like object function A of the phantom spheres were similar to the real images obtained with Scanner C; the root mean square errors (RMSEs) between them were 10.8, 11.1, and 12.5 Hounsfield units (HU) for 5-, 7-, and 10-mm-diameter spheres, respectively. The equivalent results (RMSEs) using the nodule-like object function B were 15.9, 16.8, and 16.5 HU, respectively. These RMSEs were small considering the high contrast between the sphere density and background density (approximately 674 HU). The virtual nodules generated from the nodule-like object functions of the five laboratory-made nodules were similar to the real images obtained with Scanner C; the RMSEs between them ranged from 6.2 to 8.6 HU in five cases. CONCLUSIONS: The nodule-like object functions calculated from real nodule images would be effective to generate realistic virtual nodules. The proposed method would be feasible for generating virtual nodules that have the characteristics of the spatial resolution of the CT system used in each institution, allowing for site-specific nodule generation.

A method for evaluating the performance of computer-aided detection of pulmonary nodules in lung cancer CT screening: detection limit for nodule size and density.

OBJECTIVE: We propose the application of virtual nodules to evaluate the performance of computer-aided detection (CAD) of lung nodules in cancer screening using low-dose CT. METHODS: The virtual nodules were generated based on the spatial resolution measured for a CT system used in an institution providing cancer screening and were fused into clinical lung images obtained at that institution, allowing site specificity. First, we validated virtual nodules as an alternative to artificial nodules inserted into a phantom. In addition, we compared the results of CAD analysis between the real nodules (n = 6) and the corresponding virtual nodules. Subsequently, virtual nodules of various sizes and contrasts between nodule density and background density (ΔCT) were inserted into clinical images (n = 10) and submitted for CAD analysis. RESULTS: In the validation study, 46 of 48 virtual nodules had the same CAD results as artificial nodules (kappa coefficient = 0.913). Real nodules and the corresponding virtual nodules showed the same CAD results. The detection limits of the tested CAD system were determined in terms of size and density of peripheral lung nodules; we demonstrated that a nodule with a 5-mm diameter was detected when the nodule had a ΔCT > 220 HU. CONCLUSION: Virtual nodules are effective in evaluating CAD performance using site-specific scan/reconstruction conditions. Advances in knowledge: Virtual nodules can be an effective means of evaluating site-specific CAD performance. The methodology for guiding the detection limit for nodule size/density might be a useful evaluation strategy.

Gelatin scaffold combined with bone morphogenetic protein-4 induces odontoblast-like cell differentiation involving integrin profile changes, autophagy-related gene 10, and Wnt5 sequentially in human induced pluripotent stem cells.

While human induced pluripotent stem (hiPS) cells have potential use in regenerative medicine, there are no reports on odontoblastic differentiation of hiPS cells. In the current study, to examine integrin profiles and explore the early signaling cascade of odontoblastic differentiation in hiPS cells, we investigated the regulation of autophagy-related gene (Atg) and wingless/int1 (Wnt) signaling in gelatin scaffold (GS) combined with bone morphogenetic protein (BMP)-4 (GS/BMP-4)-mediated odontoblastic differentiation. Following GS/BMP-4 treatment, there was a dramatic loss of α3 and α6 integrins, and reciprocal strong induction of α1 integrin expression in the differentiated cells. GS/BMP-4 increased the mRNA and protein levels of Atg10, Lrp5/Fzd9 (an Atg10 receptor), and Wnt5 together with the amount of autophagosomes and autophagic fluxes. Treatment with siRNAs against Atg10 and Wnt5a individually suppressed the GS/BMP-4-induced increase in odontoblastic differentiation. The odontoblastic phenotype was inhibited by chloroquine, but increased after treatment with rapamycin (an autophagy enhancer). Taken together with our previous findings, we have replicated our results from the rodent system in a novel human system. We have revealed a unique sequential cascade involving Atg10, Wnt5a, α1 integrin, and matrix metalloproteinase-3 in GS/BMP-4-induced differentiation of hiPS cells into odontoblast-like cells at a relatively early stage.

Bone morphogenetic protein-induced cell differentiation involves Atg7 and Wnt16 sequentially in human stem cell-derived osteoblastic cells.

We established a differentiation method for homogeneous α7 integrin-positive human skeletal muscle stem cell (α7(+)hSMSC)-derived osteoblast-like cells with bone morphogenetic protein (BMP)-2. To explore the early signaling cascade for osteoblastic differentiation, we examined the upregulation of autophagy-related gene (Atg) and wingless/int1 (Wnt) signaling during BMP-2-mediated human osteoblastic differentiation. In a screening experiment, BMP-2 increased the mRNA and protein levels of Atg7, Wnt16, and Lrp5/Fzd2 (a Wnt receptor), but not microtubule-associated protein 1 light chain (LC3; a mammalian homolog of yeast Atg8), TFE3, Beclin1, Atg5, Atg12, Wnt3a, or Wnt5, together with the amounts of autophagosomes and autophagy fluxes. Treatment with siRNAs against Atg7 and Wnt16 individually suppressed the BMP-2-induced increase in osteoblastic differentiation. The osteoblastic phenotype, involving osteocalcin (BGLAP), osteopontin (SPP1), and osterix (SP7) expression, decreased when autophagy was inhibited by chloroquine (an autophagy inhibitor), but increased after treatment with rapamycin (an autophagy enhancer). Taken together with our previous findings, we have revealed a unique sequential cascade of BMP-2→Atg7→Wnt16→Lrp5/Fzd2→matrix metalloproteinase-13→osteoblastic differentiation. This cascade results in a potent increase in osteoblastic cell differentiation, indicating the unique involvement of Atg7, autophagy, and Wnt16 signaling in BMP-2-induced differentiation of α7(+)hSMSCs into osteoblast-like cells at a relatively early stage.

Technical Note: Image filtering to make computer-aided detection robust to image reconstruction kernel choice in lung cancer CT screening.

PURPOSE: In lung cancer computed tomography (CT) screening, the performance of a computer-aided detection (CAD) system depends on the selection of the image reconstruction kernel. To reduce this dependence on reconstruction kernels, the authors propose a novel application of an image filtering method previously proposed by their group. METHODS: The proposed filtering process uses the ratio of modulation transfer functions (MTFs) of two reconstruction kernels as a filtering function in the spatial-frequency domain. This method is referred to as MTFratio filtering. Test image data were obtained from CT screening scans of 67 subjects who each had one nodule. Images were reconstructed using two kernels: fSTD (for standard lung imaging) and fSHARP (for sharp edge-enhancement lung imaging). The MTFratio filtering was implemented using the MTFs measured for those kernels and was applied to the reconstructed fSHARP images to obtain images that were similar to the fSTD images. A mean filter and a median filter were applied (separately) for comparison. All reconstructed and filtered images were processed using their prototype CAD system. RESULTS: The MTFratio filtered images showed excellent agreement with the fSTD images. The standard deviation for the difference between these images was very small, ∼6.0 Hounsfield units (HU). However, the mean and median filtered images showed larger differences of ∼48.1 and ∼57.9 HU from the fSTD images, respectively. The free-response receiver operating characteristic (FROC) curve for the fSHARP images indicated poorer performance compared with the FROC curve for the fSTD images. The FROC curve for the MTFratio filtered images was equivalent to the curve for the fSTD images. However, this similarity was not achieved by using the mean filter or median filter. CONCLUSIONS: The accuracy of MTFratio image filtering was verified and the method was demonstrated to be effective for reducing the kernel dependence of CAD performance.

Autophagy-related gene 5 and Wnt5 signaling pathway requires differentiation of embryonic stem cells into odontoblast-like cells.

We previously confirmed a unique and unanticipated role for an α2 integrin, extracellular matrix metalloproteinase inducer (Emmprin), and matrix metalloproteinase (MMP)-3-mediated signaling cascade, in driving the odontoblast-like differentiation of mouse embryonic stem (ES) cells in a collagen type-I scaffold (CS) combined with bone morphogenetic protein (BMP)-4 (CS/BMP-4). To explore the early signaling cascade for odontoblastic differentiation, we examined the upregulation of autophagy-related gene (Atg) and Wnt signaling by CS/BMP-4 mediated odontoblast differentiation. In a screening experiment, CS/BMP-4 increased the mRNA and protein levels of Atg5, Lrp5/Fzd9 (an Atg5 receptor), and Wnt5, but not microtubule-associated protein 1 light chain (LC3; a mammalian homolog of yeast Atg8), TFE3, Beclin1, and Atg12, together with the amount of autophagosomes and autophagy fluxes. Treatment with siRNAs against Atg5 and Wnt5 individually suppressed the CS/BMP-4-induced increase in odontoblast differentiation. The odontoblastic phenotype, involving dentin matrix protein-1 and dentin sialophosphoprotein expression, decreased when autophagy was inhibited by chloroquine, but increased after treatment with rapamycin (an autophagy enhancer). Taken together with our previous findings, we have revealed a unique sequential cascade involving Atg5, Wnt5a, α2 integrin, Emmprin, and MMP-3. This cascade results in a potent increase in odontoblastic cell differentiation, indicating the unique involvement of Atg5, autophagy and Wnt5 signaling in CS/BMP-4-induced differentiation of ES cells into odontoblast-like cells, at a relatively early stage.

Interleukin-1ß-induced autophagy-related gene 5 regulates proliferation of embryonic stem cell-derived odontoblastic cells.

We previously established a method for the differentiation of induced pluripotent stem cells and embryonic stem cells into α2 integrin-positive odontoblast-like cells. We also reported that Wnt5 in response to interleukin (IL)-1ß induces matrix metalloproteinase (MMP)-3-regulated cell proliferation in these cells. Our findings suggest that MMP-3 plays a potentially unique physiological role in the generation of odontoblast-like cells under an inflammatory state. Here, we examined whether up-regulation of autophagy-related gene (Atg) 5 by IL-1ß was mediated by Wnt5 signaling, thus leading to increased proliferation of odontoblast-like cells. IL-1ß increased the mRNA and protein levels of Atg5, microtubule-associated protein 1 light chain (LC3, a mammalian homolog of yeast Atg8) and Atg12. Treatment with siRNAs against Atg5, but not LC3 and Atg12, suppressed the IL-1ß-induced increase in MMP-3 expression and cell proliferation. Our siRNA analyses combined with western blot analysis revealed a unique sequential cascade involving Atg5, Wnt5a and MMP-3, which resulted in the potent increase in odontoblastic cell proliferation. These results demonstrate the unique involvement of Atg5 in IL-1ß-induced proliferation of embryonic stem cell-derived odontoblast-like cells.