Detonation nanodiamonds have found numerous potential applications in a diverse array of fields such as biomedical imaging and drug delivery. Here, we systematically characterized non-functionalized ...and polyglycerol-functionalized detonation nanodiamond particles (DNPs) dispersed in aqueous suspensions at different ionic strengths (∼1.0 × 10
to 1.0 × 10
M) via dynamic light scattering and cryogenic transmission electron microscopy. For these colloidal suspensions, the total potential energies of interactions between a pair of DNPs were theoretically calculated using the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory plus the fitting of the Boltzmann distribution to the interparticle spacing distribution of the colloidal DNPs. These investigations revealed that the non-functionalized DNPs are dispersed in aqueous media through the long-range (>10 nm) and weak (<7
) electrical double-layer repulsive interaction, while the driving force on dispersion of polyglycerol-functionalized DNPs is mostly derived from the short-range (<2 nm) and strong (∼55
) steric repulsive potential barrier generated by the polyglycerol. Moreover, our results show that the truly monodispersed and individually dispersed DNP colloids, forming no aggregates in aqueous suspensions, are available by both functionalizing DNPs by polyglycerol and increasing ionic strength of suspending media to ≳1.0 × 10
M.
Silicon vacancy (SiV) color centers in diamond have attracted widespread attention owing to their stable photoluminescence (PL) with a sharp emission band in the near-infrared region (ZPL 738 nm). ...Especially, SiV center containing single-digit nanometer-sized nanodiamonds (single-digit SiV-NDs) are desirable for various applications such as bioimaging and biosensing because of their extremely small size, comparable to many biomaterials. Therefore, several attempts have been made to fabricate the single-digit SiV-NDs. However, there are no reports on the successful fabrication of such materials in reasonable scale of production. Here, we report the successful synthesis of single-digit SiV-NDs via straightforward detonation process, which is known to have the high productivity in fabrication of single-digit NDs. Triphenylsilanol (TPS), as a silicon source, was mixed with explosives (TPS/TNT/RDX = 1/59/40 wt%) and the detonation process was carried out. The obtained single-digit NDs exhibit PL at approximately 738 nm, indicating that single-digit SiV-NDs were successfully synthesized. Moreover, we conjectured that the physics behind this achievement may be attributed to the aromatic ring of TPS under the consideration of ND formation mechanism newly built up based on the results of time-resolved optical emission measurements for the detonation reaction.
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•SiV centers in diamond are provided for various bioapplications.•SiV center-containing single-digit nanometer NDs were synthesized directly by detonation process.•Detonation with triphenylsilanol as a silicon source allowed to incorporate SiV centers into DNDs.•SiV centers in DNDs showed sharp PL emission peak centered at the ZPL = 738 nm.•Optical measurement of the detonation reaction revealed the physics behind the creation of SiV centers.
Diamond nanoparticles (DNPs) are expected as splendid coating materials to give, e.g. corrosion resistance, anti-bacterial properties, and antireflection function. In this paper, we demonstrate a ...technique of electrostatic layer-by-layer deposition of DNPs onto substrate surfaces using DNP colloidal suspensions with different signs of zeta potentials alternately. The formed DNP layers are investigated in terms of film thickness, surface roughness, and homogeneity. Plus, those morphologies of DNP layers are theoretically correlated with the colloidal properties of DNP suspensions based on the electrostatic interaction potential energy between colloidal DNPs and substrate surfaces. Consequently, it turns out that the demonstrated technique enables formation of DNP thin layers with desired thickness, particle density, and surface roughness on substrate surfaces by controlling the ionic strength of colloidal DNPs.
Nanodiamonds (NDs) containing group IV-vacancy (G4V) centers—silicon-vacancy (SiV), germanium-vacancy (GeV) and tin-vacancy (SnV) centers—have shown promising potential as fluorescent markers for ...bioimaging and -sensing. However, the scale of fabrication has been limited to the laboratory scale. In this study, a detonation process was applied that enables practical scale fabrication of NDs for the direct synthesis of these G4V center-containing NDs (G4V-NDs). This detonation process for the direct synthesis of G4V-NDs employed explosives with the addition of dopant molecules with group IV atoms centered on tetraphenyl compounds. The successful synthesis of negatively charged SiV and GeV center-containing NDs (SiV- and GeV-NDs) was evidenced by photoluminescence (PL) spectra with zero-phonon lines (ZPLs) attributed to such color centers. However, as a result of the same strategy, NDs containing the SnV centers were not obtained in detectable concentrations in PL measurements. When the generated concentrations of SiV- and GeV-NDs synthesized under identical conditions were evaluated based on the number of data points that clear ZPLs were observed on the PL mappings, the SiV-NDs were found to be produced more predominantly than the GeV-NDs. The physics behind such results is explained by the difference in the reaction thermodynamics for each group IV atom.
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•Detonation process (DP) enables practical scale production of nanodiamonds (NDs).•Direct synthesis of NDs containing SiV or GeV centers was achieved by DP.•As Si or Ge sources in DP, atoms centered on tetraphenyl compounds were used.•SnV centers were not detected in NDs obtained via same scheme.•This is due to the difference in the reaction thermodynamics for each heteroatom.
While realizing carbon neutrality is an urgent priority, diamond materials with negative electron affinity (NEA) are considered productive sources of solvated electrons, which can help efficiently ...reduce CO2 in potential green chemistry applications. Recently, CO2 was photocatalytically reduced into CO by solvated electrons using commonly used H-terminated diamond with NEA under deep ultraviolet light irradiation. However, CO2 has never been reduced under visible-light irradiation, would be more practicable in the living environment, because of the wide band gap afforded by diamonds. In this study, electrons excited by visible light in heavily N-doped surface nano-layer of diamond platelets are emitted through the H-terminated surface with NEA toward a CO2-saturated aqueous solution, successfully reducing CO2 into CO. To this end, the B-doped p-type diamond films are grown by chemical vapor deposition on initial seed layers of detonation-synthesized nanodiamonds (DNDs). This approach allows incorporating the abundantly available N atoms in the DNDs into the surface nano-layer on the diamond platelets, resulting in the formation of an electron-excitation nano-layer having ≥1021 N atoms/cm3 and associated defects absorbing visible light. These results pave the way toward a new, energy-efficient technology for CO2 reduction with strong implications for achieving a carbon-negative society.
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•Diamond platelets with N-doped nano-layers are obtained by chemical vapor deposition on detonation-synthesized nanodiamonds.•Electrons are excited by visible light in the N-doped layer due to the defects associated with incorporated N atoms.•Negative electron affinity surfaces enable barrier-free electron emission toward a neighboring aqueous solution.•The electrons emitted into a CO2-saturated KCl aqueous solution reduce CO2 into CO with a Faradaic efficiency of ∼20%.
A simple construction of sol–gel sheaths onto the surface of multi-walled carbon nanotubes (MWCNTs) has been carried out in water by a hydrophobicity-induced covering with the assistance of ...ultrasound. The ultrasound assistance prevents in water an unregulated agglomeration induced by the hydrophobicity of MWCNTs and phenyl-containing sols, leading to a selective construction of sol–gel sheaths on the nanotube surface. The phenyl groups of the resulting sol–gel sheaths were successfully removed by air-oxidation to provide the MWCNTs covered with amorphous SiO
2 sheaths. The effect of the SiO
2 sheaths on the electrical and thermal properties of the SiO
2-MWCNT nanocomposites was evaluated from the electrical resistivities of the nanocomposites with two different SiO
2 concentrations and the thermal conductivities of their phenol-resin composites. The results indicate that the small increase of the SiO
2 concentration remarkably increases the electrical resistivity of the SiO
2-MWCNT nanocomposites. Furthermore, the SiO
2 sheaths have more directly influenced the thermal property of the polymer composites than the inside nanotubes.
The decomposition efficiency of chlorinated hydrocarbons by supercritical water oxidation (SCWO) using sodium nitrate (NaNO
3) and nitrite (NaNO
2) salts as oxidants has been evaluated in the batch ...and flow reactor systems. The oxidation reactions are promoted by the reduction of nitrate and nitrite (i.e., N(+V)
+
5e
−
→
N(0) and N(+III)
+
3e
−
→
N(0)) proceeding via nitrogen monoxide (NO) and dioxide (NO
2) intermediates. The stoichiometric reactions of 4-dichlorobenzene (4-DCBz) with nitrate and nitrite were described on the basis of the component and distribution of the gaseous reaction products. However, {
mCO
+
nH
2} methanations as competing reactions have caused a discrepancy from the chemical equivalent of the stoichiometric reactions. The highest decomposition (net decomposition
>
99.95%) of 4-dichlorobenzene and polychlorinated biphenyls (PCBs) has been achieved at 450
°C and
ρ
w
>
0.25
g/cm
3 for 30
min. Advantageously, the oxidation reactions proceed in parallel with the neutralization of reactor-corrosive hydrogen chloride (HCl) produced by the decomposition of chlorinated hydrocarbons. However, the resulting salts are responsible for the plugging of the flow reactor vessel, because of its low solubility for SCW and high melting point. This work has solved the reactor plugging by introducing removal steps of the precipitated salts into the operation process, whereby a semi-continuous processing of PCBs has been carried out under relatively low pressure condition (
P
=
ca. 39
MPa).
ABSTRACT
Aim
We present the study protocol of a multicenter, retrospective observational study that aims to investigate the efficacy of the actual treatment (the efficacy of conventional and Kampo ...medicines) of patients with mild to moderate or suspected coronavirus disease (COVID‐19).
Methods
This study is designed as a multicenter, retrospective observational study. Outpatients and inpatients will be recruited from Japanese hospitals. The inclusion criteria are as follows: having or suspected to have COVID‐19, mild to moderate COVID‐19, symptomatic, ≥20 years of age, male or female, able to communicate in Japanese, and treated with conventional and Kampo medicine. The exclusion criteria are: unable to provide informed consent due to dementia, psychosis, or psychiatric symptoms, severe COVID‐19, or determined unsuitable for this study. The sample size is set at 1000, as this number of people can be treated at the collaborating medical institutions during the study period.
Results
The main outcome is the number of days without fever, with a body temperature of less than 37°C. The secondary outcome is set at common cold‐like symptoms other than fever (fatigue, cough, shortness of breath, sputum, diarrhea) and severity of illness and hospitalization up to 14 days after the visit.
Trial registration
The trial was registered in the University Hospital Medical Information Network (Reservation No. UMIN000041301) on August 4, 2020.
Conclusion
Our study will explore the contribution of conventional and Kampo medicine in the treatment of patients with mild and moderate COVID‐19.
We studied with quantitative techniques the clinical efficacy of indium-111 antimyosin at a later stage of myocardial infarction in 18 patients at various stages after infarction. Antimyosin ...accumulation was detected irrespective of infarct age and size and quantified as an infarct weight with a tomographic technique. Higher intensities in a planar image were observed in anterior Q wave infarct group (36 +/- 5 g) but not in inferior and non-Q wave anterior infarct groups because of the smaller infarct weights (8 +/- 3 g, 13 +/- 6 g, respectively). Infarct area calculated from thallium-201 tomography significantly correlated with left ventricular ejection fraction in both recent (less than 2 weeks) and older (2-week- to 6-month-old) infarct groups (r = -0.969, P less than 0.001; r = -0.860, P less than 0.001, respectively), whereas there was a significant negative correlation between infarct weight and left ventricular ejection fraction in the recent infarct group (r = -0.731, P less than 0.05) but not in the older infarct group. Thus, antimyosin tomography can detect myocardial necrosis with a high sensitivity regardless of infarct age, size, and location. However, the accumulation might be affected by infarct age and correspond to necrotic mass but not necessarily to infarct volume itself at a later stage probably because of the presence of necrosed and scarred tissues in infarcted myocardium.
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