Abstract
We perform a full nuclear-network numerical calculation of the
r
-process nuclei in binary neutron-star mergers (NSMs), with the aim of estimating gamma-ray emissions from the remnants of ...Galactic NSMs up to 10
6
yr old. The nucleosynthesis calculation of 4070 nuclei is adopted to provide the elemental composition ratios of nuclei with an electron fraction
Y
e
between 0.10 and 0.45. The decay processes of 3237 unstable nuclei are simulated to extract the gamma-ray spectra. As a result, the NSMs have different spectral colors in the gamma-ray band from various other astronomical objects at less than 10
5
yr old. In addition, we propose a new line diagnostic method for
Y
e
that uses the line ratios of either
137m
Ba/
85
K or
243
Am/
60m
Co, which become larger than unity for young and old
r
-process sites, respectively, with a low
-Y
e
environment. From an estimation of the distance limit for gamma-ray observations as a function of age, the high sensitivity in the sub-megaelectronvolt band, at approximately 10
−9
photons s
−1
cm
−2
or 10
−15
erg s
−1
cm
−2
, is required to cover all the NSM remnants in our Galaxy, if we assume that the population of NSMs by Wu et al. A gamma-ray survey with sensitivities of 10
−8
–10
−7
photons s
−1
cm
−2
or 10
−14
–10
−13
erg s
−1
cm
−2
in the 70–4000 keV band is expected to find emissions from at least one NSM remnant under the assumption of an NSM rate of 30 Myr
−1
. The feasibility of gamma-ray missions observing Galactic NSMs is also studied.
HEX-P is a probe-class mission concept that will combine high spatial resolution X-ray imaging (
<
1
0
″
full width at half maximum) and broad spectral coverage (0.2–80 keV) with an effective area ...far superior to current facilities (including
XMM
-Newton and
NuSTAR
) to enable revolutionary new insights into a variety of important astrophysical problems. HEX-P is ideally suited to address important problems in the physics and astrophysics of supernova remnants (SNRs) and pulsar wind nebulae (PWNe). For shell SNRs, HEX-P can greatly improve our understanding via more accurate spectral characterization and localization of non-thermal X-ray emission from both non-thermal-dominated SNRs and those containing both thermal and non-thermal components, and can discover previously unknown non-thermal components in SNRs. Multi-epoch HEX-P observations of several young SNRs (e.g., Cas A and Tycho) are expected to detect year-scale variabilities of X-ray filaments and knots, thus enabling us to determine fundamental parameters related to diffusive shock acceleration, such as local magnetic field strengths and maximum electron energies. For PWNe, HEX-P will provide spatially-resolved, broadband X-ray spectral data separately from their pulsar emission, allowing us to study how particle acceleration, cooling, and propagation operate in different evolution stages of PWNe. HEX-P is also poised to make unique and significant contributions to nuclear astrophysics of Galactic radioactive sources by improving detections of, or limits on,
44
Ti in the youngest SNRs and by potentially discovering rare nuclear lines as evidence of double neutron star mergers. Throughout the paper, we present simulations of each class of objects, demonstrating the power of both the imaging and spectral capabilities of HEX-P to advance our knowledge of SNRs, PWNe, and nuclear astrophysics.
HEX-P is a probe-class mission concept that will combine high spatial resolution X-ray imaging (<10"FWHM) and broad spectral coverage (0.2--80 keV) with an effective area far superior to current ...facilities (including XMM-Newton and NuSTAR) to enable revolutionary new insights into a variety of important astrophysical problems. With the recent discoveries of over 40 ultra-high-energy gamma-ray sources (detected above 100 TeV) and neutrino emission in the Galactic Plane, we have entered a new era of multi-messenger astrophysics facing the exciting reality of Galactic PeVatrons. In the next decade, as more Galactic PeVatrons and TeV gamma-ray sources are expected to be discovered, the identification of their acceleration and emission mechanisms will be the most pressing issue in both particle and high-energy astrophysics. In this paper, along with its companion papers (Reynolds et al. 2023, Mori et al. 2023), we will present that HEX-P is uniquely suited to address important problems in various cosmic-ray accelerators, including Galactic PeVatrons, through investigating synchrotron X-ray emission of TeV--PeV electrons produced by both leptonic and hadronic processes. For Galactic PeVatron candidates and other TeV gamma-ray sources, HEX-P can fill in a large gap in the spectral-energy distributions (SEDs) of many objects observed in radio, soft X-rays, and gamma rays, constraining the maximum energies to which electrons can be accelerated, with implications for the nature of the Galactic PeVatrons and their contributions to the spectrum of Galactic cosmic rays beyond the knee at $\sim3$ PeV. In particular, X-ray observation with HEX-P and TeV observation with CTA will provide the most powerful multi-messenger diagnostics to identify Galactic PeVatrons and explore a variety of astrophysical shock mechanisms. We present simulations of each class of Galactic TeV--PeV sources, demonstrating the power of both the imaging and spectral capabilities of HEX-P to advance our knowledge of Galactic cosmic-ray accelerators. In addition, we discuss HEX-P’s unique and complementary roles to upcoming gamma-ray and neutrino observatories in the 2030s.
We perform a full nuclear-network numerical calculation of the \(r\)-process nuclei in binary neutron-star mergers (NSMs), with the aim of estimating \(\gamma\)-ray emissions from the remnants of ...Galactic NSMs up to \(10^6\) years old. The nucleosynthesis calculation of 4,070 nuclei is adopted to provide the elemental composition ratios of nuclei with an electron fraction \(Y_{\rm e}\) between 0.10 and 0.45 . The decay processes of 3,237 unstable nuclei are simulated to extract the \(\gamma\)-ray spectra. As a result, the NSMs have different spectral color in \(\gamma\)-ray band from various other astronomical objects at less than \(10^5\) years old. In addition, we propose a new line-diagnostic method for \(Y_{\rm e}\) that uses the line ratios of either \(^{137{\rm m}}\)Ba/\(^{85}\)K or \(^{243}\)Am/\(^{60{\rm m}}\)Co, which become larger than unity for young and old \(r\)-process sites, respectively, with a low \(Y_{\rm e}\) environment. From an estimation of the distance limit for \(\gamma\)-ray observations as a function of the age, the high sensitivity in the sub-MeV band, at approximately \(10^{-9}\) photons s\(^{-1}\) cm\(^{-2}\) or \(10^{-15}\) erg s\(^{-1}\) cm\(^{-2}\), is required to cover all the NSM remnants in our Galaxy if we assume that the population of NSMs by \citet{2019ApJ...880...23W}. A \(\gamma\)-ray survey with sensitivities of \(10^{-8}\)--\(10^{-7}\) photons s\(^{-1}\) cm\(^{-2}\) or \(10^{-14}\)--\(10^{-13}\) erg s\(^{-1}\) cm\(^{-2}\) in the 70--4000 keV band is expected to find emissions from at least one NSM remnant under the assumption of NSM rate of 30 Myr\(^{-1}\). The feasibility of \(\gamma\)-ray missions to observe Galactic NSMs are also studied.
HEX-P is a probe-class mission concept that will combine high spatial resolution X-ray imaging (<10" FWHM) and broad spectral coverage (0.2-80 keV) with an effective area far superior to current ...facilities (including XMM-Newton and NuSTAR) to enable revolutionary new insights into a variety of important astrophysical problems. With the recent discoveries of over 40 ultra-high-energy gamma-ray sources (detected above 100 TeV) and neutrino emission in the Galactic Plane, we have entered a new era of multi-messenger astrophysics facing the exciting reality of Galactic PeVatrons. In the next decade, as more Galactic PeVatrons and TeV gamma-ray sources are expected to be discovered, the identification of their acceleration and emission mechanisms will be the most pressing issue in both particle and high-energy astrophysics. In this paper, along with its companion papers (Reynolds et al. 2023, Mori et al. 2023), we will present that HEX-P is uniquely suited to address important problems in various cosmic-ray accelerators, including Galactic PeVatrons, through investigating synchrotron X-ray emission of TeV-PeV electrons produced by both leptonic and hadronic processes.
HEX-P is a probe-class mission concept that will combine high spatial resolution X-ray imaging (\(<10"\) full width at half maximum) and broad spectral coverage (0.2--80 keV) with an effective area ...far superior to current facilities (including XMM-Newton and NuSTAR) to enable revolutionary new insights into a variety of important astrophysical problems. HEX-P is ideally suited to address important problems in the physics and astrophysics of supernova remnants (SNRs) and pulsar-wind nebulae (PWNe). For shell SNRs, HEX-P can greatly improve our understanding via more accurate spectral characterization and localization of non-thermal X-ray emission from both non-thermal-dominated SNRs and those containing both thermal and non-thermal components, and can discover previously unknown non-thermal components in SNRs. Multi-epoch HEX-P observations of several young SNRs (e.g., Cas A and Tycho) are expected to detect year-scale variabilities of X-ray filaments and knots, thus enabling us to determine fundamental parameters related to diffusive shock acceleration, such as local magnetic field strengths and maximum electron energies. For PWNe, HEX-P will provide spatially-resolved, broadband X-ray spectral data separately from their pulsar emission, allowing us to study how particle acceleration, cooling, and propagation operate in different evolution stages of PWNe. HEX-P is also poised to make unique and significant contributions to nuclear astrophysics of Galactic radioactive sources by improving detections of, or limits on, \(^{44}\)Ti in the youngest SNRs and by potentially discovering rare nuclear lines as evidence of double neutron star mergers. Throughout the paper, we present simulations of each class of objects, demonstrating the power of both the imaging and spectral capabilities of HEX-P to advance our knowledge of SNRs, PWNe, and nuclear astrophysics.
Objectives
This study is aimed at evaluating the effect of a new glass ionomer cement (GIC) containing fluoro-zinc-silicate fillers on biofilm formation and ion incorporation.
Materials and methods
...Streptococcus mutans
biofilms were developed on two GIC materials: Caredyne Restore (CD) and Fuji VII (FJ); and hydroxyapatite (HA) for 24 h at 37 °C using a flow cell system. The morphological structure and bacterial viability were analyzed using a confocal laser scanning microscopy. Bacterial adhesion during the initial 2 h was also assessed by viable cell counting. To study the ion incorporation, restored cavities prepared on the root surfaces of human incisors were subjected to the elemental mapping of the zinc and fluoride ions in the GIC-dentin interface using a wavelength-dispersive X-ray spectroscopy electron probe microanalyzer.
Results
Morphological observations revealed that biofilm formation in the CD group was remarkably inhibited compared with the HA and FJ groups, exhibiting sparse, thinner biofilm clusters. The microorganisms adhering to the CD group were significantly inhibited, revealing 2.9 ± 0.4 for CD, 4.9 ± 0.2 for FJ, and 5.4 ± 0.4 log colony-forming units (CFU) for HA. The CD zinc ion incorporation depth was 72.2 ± 8.0 μm. The fluoride penetration of CD was three times deeper than that of FJ; this difference was statistically significant (
p
< 0.05).
Conclusions
Enhanced by the incorporation of zinc and fluoride ions, the new GIC inhibited biofilm formation by interfering with bacterial adhesion.
Clinical relevance
A novel GIC comprised of fluoro-zinc-silicate fillers may improve clinical outcomes, such as root caries and minimally invasive dentistry.
Chemical disinfection of oral biofilms often leaves biofilm structures intact. This study aimed to examine whether the residual structure promotes secondary bacterial adhesion. Streptococcus mutans ...biofilms generated on resin-composite disks in a rotating disc reactor were disinfected completely with 70% isopropyl alcohol, and were again cultured in the same reactor after resupplying with the same bacterial solution. Specimens were subjected to fluorescence confocal laser scanning microscopy, viable cell counts and PCR-Invader assay in order to observe and quantify secondarily adhered cells. Fluorescence microscopic analysis, particularly after longitudinal cryosectioning, demonstrated stratified patterns of viable cells on the disinfected biofilm structure. Viable cell counts of test specimens were significantly higher than those of controls, and increased according to the amount of residual structure and culture period. Linear regression analysis exhibited a high correlation between viable and total cell counts. It was concluded that disinfected biofilm structures favored secondary bacterial adhesion.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
This study aimed to develop a technique to create sequential slices, allowing the fluorescent visualization of bacterial viability in all parts of an infected dentin.
Cylindrical dentin blocks were ...prepared from freshly extracted human teeth with a single-rooted canal. Each block was immersed in 5% sodium hypochlorite (NaOCl) and 17% EDTA for 5 minutes before being infected with Enterococcus faecalis. The bacteria were allowed to develop inside dentin specimens for 28 days under anaerobic conditions. The specimens were exposed in 2% NaOCl for either 2 minutes or 20 minutes at 20°C, 37°C, and 45°C, respectively. After staining with calcein AM (Thermo Fisher Scientific, Waltham, MA) and propidium iodide, the samples were cryoembedded, mounted on an adhesive film, and sectioned at a thickness of 10 μm along the running of the dentinal tubules. Stacks of fluorescent images were collected in the z dimension using confocal laser scanning microscopy, and the maximum affected distance from a root canal was measured from the 3-dimensional reconstructed image. The reliability of this technique was verified by comparison with a dye bleaching test.
Horizontal sequential sections preserving 3-dimensional bacterial distribution and their viabilities could be made without decalcification. The treatment time contributed to the penetration of NaOCl into dentinal tubules, whereas temperature did not significantly affect the penetration. The judgment by confocal laser scanning microscopic analysis was consistent with that of a dye bleaching test.
The horizontal sectioning method has the advantage of creating sequential sections, allowing information to be imaged at every portion.
•A slicing technique for visualizing bacterial viability in dentin was developed.•The predemineralization and/or fracturing are not need for sample preparation.•This technique may be useful as an approach for elucidating clinical failure.
An ideal antibiofilm strategy is to control both in the quality and quantity of biofilm while maintaining the benefits derived from resident microflora. Vizantin, a recently developed ...immunostimulating compound, has also been found to have antibiofilm property. This study evaluated the influence on biofilm formation of Streptococcus mutans in the presence of sulfated vizantin and biofilm development following bacterial adhesion on a hydroxyapatite disc coated with sulfated vizantin. Supplementation with sulfated vizantin up to 50 μM did not affect either bacterial growth or biofilm formation, whereas 50 μM sulfated vizantin caused the biofilm to readily detach from the surface. Sulfated vizantin at the concentration of 50 μM upregulated the expression of the gtfB and gtfC genes, but downregulated the expression of the gtfD gene, suggesting altered architecture in the biofilm. Biofilm development on the surface coated with sulfated vizantin was inhibited depending on the concentration, suggesting prevention from bacterial adhesion. Among eight genes related to bacterial adherence in S. mutans, expression of gtfB and gtfC was significantly upregulated, whereas the expression of gtfD, GbpA and GbpC was downregulated according to the concentration of vizantin, especially with 50 μM vizantin by 0.8-, 0.4-, and 0.4-fold, respectively. These findings suggest that sulfated vizantin may cause structural degradation as a result of changing gene regulation related to bacterial adhesion and glucan production of S. mutans.
•Vizantin has immunostimulating and antimetastatic properties.•Vizantin showed antibiofilm activity against S. mutans without affecting bacterial growth.•Streptococcus mutans biofilm was detached by altering its internal architecture.•Gene expressions related to bacterial adhesion were changed.
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