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The formation and the chemical characterization of single atoms of dubnium (Db, element 105), in the form of its volatile oxychloride, was investigated using the on‐line gas phase chromatography technique, in the temperature range 350–600 °C. Under the exactly same chemical conditions, comparative studies with the lighter homologues of Group 5 in the Periodic Table clearly indicate the volatility sequence being NbOCl3 > TaOCl3 ≥ DbOCl3. From the obtained experimental results, thermochemical data for DbOCl3 were derived. The present study delivers reliable experimental information for theoretical calculations on chemical properties of transactinides., Dubnium obeys Mendeleev's periodicity. Fifty years after the discovery of this element, its chemical behavior was experimentally revisited. From the gas chromatographic investigation of the volatile oxychloride compound, a trend of decreasing volatility along Group 5 elements was deduced, in agreement with the expectations by the laws established in the Periodic Table.

All superheavy elements (SHEs), with atomic numbers (Z) ≥104, have been artificially synthesized one atom at a time and their chemical properties are largely unknown. Because these heavy nuclei have short lifetimes as well as extremely low production rates, chemical experiments need to be carried out on single atoms and have mostly been limited to adsorption and extraction. We have now investigated the precipitation properties of the SHE Rf (Z = 104). A co-precipitation method with samarium hydroxide had previously established that the co-precipitation behaviour of a range of elements reflected these elements’ tendency to form hydroxide precipitates and/or ammine complex ions. Here we investigated co-precipitation of Rf in basic solutions containing NH3 or NaOH. Comparisons between the behaviour of Rf with that of Zr and Hf (lighter homologues of Rf) and actinide Th (a pseudo-homologue of Rf) showed that Rf does not coordinate strongly with NH3, but forms a hydroxide (co)precipitate that is expected to be Rf(OH)4. It is difficult to investigate the chemical properties of superheavy elements, which are only available an atom at a time and rapidly decay. A co-precipitation method with samarium has now been developed that suggests rutherfordium would form hydroxide precipitates—but not ammine ones—if it were possible to perform these experiments on macroscopic quantities.

Deep-learning algorithms enable precise image recognition based on high-dimensional hierarchical image features. Here, we report the development and implementation of a deep-learning-based image segmentation algorithm in an autonomous robotic system to search for two-dimensional (2D) materials. We trained the neural network based on Mask-RCNN on annotated optical microscope images of 2D materials (graphene, hBN, MoS2, and WTe2). The inference algorithm is run on a 1024 × 1024 px2 optical microscope images for 200 ms, enabling the real-time detection of 2D materials. The detection process is robust against changes in the microscopy conditions, such as illumination and color balance, which obviates the parameter-tuning process required for conventional rule-based detection algorithms. Integrating the algorithm with a motorized optical microscope enables the automated searching and cataloging of 2D materials. This development will allow researchers to utilize a large number of 2D materials simply by exfoliating and running the automated searching process. To facilitate research, we make the training codes, dataset, and model weights publicly available.

Chemical studies of transactinide elements (atomic number Z ≥ 104) are of great importance to understand the relativistic effects; however, the experimental methodology is limited owing to the sing...

For new chemical studies on heavy elements, we previously investigated the coprecipitation behaviors with samarium hydroxide for various elements. Herein, we report the coprecipitation experiment using multitracer produced by neutron-induced fission of

For new chemical studies on heavy elements, we previously investigated the coprecipitation behaviors with samarium hydroxide for various elements. Herein, we report the coprecipitation experiment using multitracer produced by neutron-induced fission of 235U. The coprecipitation behaviors of 10 elements were investigated: new data were obtained for Sr, Ru, I, Pm, and Np. The present results support the previously obtained conclusion that the hydroxide precipitation properties of various elements can be qualitatively investigated through their coprecipitation behaviors.

The first nuclear-excited state of $^{229}\mathrm{Th}, ^{229\mathrm{m}}\mathrm{Th}$, is known to have extremely low excitation energy at 8.28 \ifmmode\pm\else\textpm\fi{} 0.17 eV, and the nuclear decay mode and half-life of $^{229\mathrm{m}}\mathrm{Th}$ are considered to depend on its chemical environment. Recently, internal-conversion (IC) electrons from $^{229\mathrm{m}}\mathrm{Th}$ produced from a $^{233}\mathrm{U}$ source were detected for the first time, and the half-life of $^{229\mathrm{m}}\mathrm{Th}$ on the nickel-alloy surface of a microchannel plate detector was determined. In this study, to determine the half-lives for other chemical environments, we produced $^{229\mathrm{m}}\mathrm{Th}$ through the \ensuremath{\beta} decay of $^{229}\mathrm{Ac}$ and measured low-energy IC electrons from $^{229\mathrm{m}}\mathrm{Th}$ using the coincidence measurement technique between high-energy electrons (mainly \ensuremath{\beta} particles and high-energy IC electrons) and all electrons (including IC electrons from $^{229\mathrm{m}}\mathrm{Th}$) emitted from an $^{229}\mathrm{Ac}$ electrodeposited source. The $^{229}\mathrm{Ac}$ nuclide was produced by the $^{232}\mathrm{Th}(p,\ensuremath{\alpha})^{229}\mathrm{Ac}$ reaction and then was separated from a large amount of the reaction byproducts utilizing chemical separation techniques. Electron signals, which correspond to the IC electrons from $^{229\mathrm{m}}\mathrm{Th}$, were detected using the coincidence measurement technique. The half-life of $^{229\mathrm{m}}\mathrm{Th}$ in the Ac electrodeposited source was determined to be 10(8) \ensuremath{\mu}s, which is close to the previous experimental value. The method established in this study lays the foundations to study the IC-decay property of $^{229\mathrm{m}}\mathrm{Th}$ as a function of the chemical environment.

We describe a technique for making one-dimensional ohmic contacts to individual graphene layers encapsulated in hexagonal boron nitride (h-BN) using CF4 and O2 plasmas. The high etch selectivity of h-BN against graphene (>1000) is achieved by increasing the plasma pressure, which enables etching of h-BN, while graphene acts as an etch stop to protect underlying h-BN. A low-pressure O2 plasma anisotropically etches graphene in the vertical direction, which exposes graphene edges at h-BN sidewalls. Despite the O2 plasma bombardment, the lower h-BN layer functions as an insulating layer. Thus, this method allows us to pattern metal electrodes on h-BN over a second graphene layer. Subsequent electron-beam lithography and evaporation fabricate metal contacts at the graphene edges that are active down to cryogenic temperatures. This fabrication method is demonstrated by the preparation of a graphene Hall bar with a graphite back-gate and double bilayer-graphene Hall bar devices. The high flexibility of the device geometries enabled by this method creates access to a variety of experiments on electrostatically coupled graphene layers., 4 figures, accepted for publication in Applied Physics Letters

The nuclear half-life of 235m U (the first metastable nuclear excited state of 235U) varies depending on chemical environments because the nucleus interacts only with outer-shell electrons in the nuclear internal conversion (IC) process due to its extremely low excitation energy at 76.737 ± 0.018 eV. Elucidating the mechanism of the half-life variation of this unique isomer would largely contribute to understanding interactions between nuclei and shell electrons. For elucidating the mechanism, we aim at measuring both half-lives and IC electron energy spectra of 235m U in various chemical environments. In this study, we developed a retarding-field type magnetic bottle spectrometer for measuring the half-lives and energy spectra with high signal to noise ratio ( S ∕ N ) and high energy resolution. As an evaluation of the fabricated apparatus, the collection efficiency of electrons emitted from a 235m U sample to a channeltron electron detector was measured as a function of the strong and weak magnetic fields and the collection voltage applied to a mesh placed on the entrance of the channeltron detector. Electron collection efficiencies of almost 100% were confirmed under several conditions. Due to this high efficiency together with the low dark noise of the channeltron detector, high S ∕ N measurements have been achieved successfully. An IC-electron energy spectrum of 235m U recorded under the most efficient condition showed an energy resolution ( Δ E ∕ E ) of ∼ 2%, which is sufficiently high to observe small peak shifts and splittings in the IC-electron energy spectra of 235m U compounds. This developed apparatus allows high precision measurements of half-lives and IC-electron energy spectra of 235m U in various chemical environments even with small amount of 235m U and low emission rate of IC electrons.

The following reaction systems, with and without proton ambiguity, were set up for direct measurements of the rate constants of borate and boronate ions: boric acid [B(OH)3] and 4,5-dihydroxy-1,3-benzenedisulfonic acid disodium salt (Tiron); 3-nitrophenylboronic acid [3-NO2PhB(OH)2] and Tiron; phenylboronic acid [PhB(OH)2] and 4-nitrocatechol; boric acid and 4-nitrocatechol. Each rate constant for boric or boronic acid is larger than that for the conjugate borate or boronate ion for the reaction systems without proton ambiguity. These results explicitly indicate that the widespread belief that the rate constants of boronate ions are several orders of magnitude larger than those of the conjugate boronic acids is erroneous. The relative kinetic reactivities of RB(OH)2 and RB(OH)3– were investigated in relation to the linear free energy relationships between the rate constants and acidities of the boronic acids and diols.

The pKas of 3-pyridylboronic acid and its derivatives were determined spectrophotometrically. Most of them had two pKas assignable to the boron center and pyridine moiety. The pKa assignment performed by 11B nuclear magnetic resonance spectroscopy revealed that both boron centers in 3-pyridylboronic acid [3-PyB(OH)2] and the N-methylated derivative [3-(N-Me)Py+B(OH)2] have strong acidities (pKa = 4.4 for both). It was found that introduction of a substituent to pyridine-C atom in 3-pyridylboronic acid drastically increased the acidity of the pyridinium moiety, but decreased the acidity of the boron center, whereas the introduction to pyridine-N atom had no influence on the acidity of the boron center. Kinetic studies on the complexation reactions of 3-pyridinium boronic acid [3-HPy+B(OH)2] with 4-isopropyltropolone (Hipt) carried out in strongly acidic aqueous solution indicated that the positive charge on the boronic acid influenced little on its reactivity; 3-HPy+B(OH)2 reacts with Hipt and protonated H2ipt+, and its reactivity was in line with those of a series of boronic acids. Kinetics in weakly acidic aqueous solution revealed that 3-HPy+B(OH)2 reacts with Hipt faster than its conjugate boronate [3-HPy+B(OH)3–], which is consistent with our recent results. The reactivity of 3-(N-Me)Py+B(OH)2 towards Hipt was also examined kinetically; the reactivities of 3-(N-Me)Py+B(OH)2 and 3-(N-Me)Py+B(OH)3– are almost the same as those of their original 3-HPy+B(OH)2 and 3-HPy+B(OH)3–, respectively. Copyright © 2012 John Wiley & Sons, Ltd.

We developed microsatellite loci to examine the occurrence of multiple paternity in the praying mantid Tenodera aridifolia Stoll, as inferred from the genotypes of the progeny within field-collected oothecae (egg cases). The microsatellite locus MTA, developed from field-caught mantids, was found to have three alleles (A, B, and C) among >600 hatchlings from 18 oothecae from two locations in Japan. Of the 18 oothecae, two show clear evidence of multiple sires, two show equivocal evidence of multiple sires, and the remaining 14 do not show evidence of multiple sires. Thirteen of the latter 14 oothecae are exclusively homozygous, with all progeny being of the same genotype (BB). Although the exclusively homozygous oothecae suggest a high incidence of monogamy in these field populations, we caution that we probably underestimated the incidence of multiple paternity, given our use of one locus with three alleles. This study is the first genetic investigation of field-collected progeny of a sexually cannibalistic species, as well as the first demonstration of multiple paternity in nature for a sexually cannibalistic species.

Kinetic studies were performed on the reactions of phenylboronic acid with L -lactic acid and mandelic acid in acidic aqueous and alkaline solutions in order to specify reactive species in these reactions. It was confirmed that the diprotonated ligand (H 2 L: L -lactic acid or mandelic acid) is less reactive than the monoprotonated ligand (HL − : L -lactate ion or mandelate ion), which made possible direct determination of the rate constants of phenylboronic acid (PhB(OH) 2 ) and its conjugate base, phenylboronate ion (PhB(OH) 3 − ). It was found that PhB(OH) 2 is more reactive than PhB(OH) 3 − . On the basis of kinetic results, it was concluded that the most reactive species are PhB(OH) 2 and HL − at physiological pH 7.4, so the reaction in the boronic acid-based sensor for L -lactate mainly would occur between these species.

Nitrogen-doped ZnO films have been grown by metalorganic vapor-phase epitaxy using diisopropylzinc, tertiary-butanol in the growth temperature range of 300–450 °C. Tertiary-butylamine was used as a nitrogen-dopant source. The nitrogen incorporation and N–H vibrational mode were observed by Raman spectroscopy. The electric properties of the as-grown samples showed n-type with carrier concentration of the order of 1018 cm−3. The N–H vibrational mode was eliminated and high electron concentration was decreased to the order of 1015 cm−3 by post-annealing at 500 °C.

Reaction systems of boronic acid (RB(OH2), R = phenyl or 3-fluorophenyl) with diols and no proton ambiguity were elaborately set up, and kinetic measurements were conducted to elucidate the relative reactivities of RB(OH)2 and RB(OH)3(-). In the reactions of phenylboronic and 3-fluorophenylboronic acids with propylene glycol, the reactivity order was: RB(OH)2RB(OH)3(-), whereas in the reactions of 3-pyridylboronic acid with Tiron and 2,2'-biphenol, the reactivity of RB(OH)2 was comparable to that of RB(OH)3(-). These results are in contrast to those that have been previously reported, and widely accepted for over thirty years, that concluded that the reactivity of RB(OH)3(-) is several orders of magnitude higher than that of RB(OH)2. The reactivity of Tiron with 3-pyridylboronic acid is affected by the protonation of one of its sulfonate groups.

To evaluate the sympathetic nervous activity in chronic hypoxic states, the plasma concentrations of norepinephrine (NE), cyclic adenosine 3', 5'-monophosphate (cyclic AMP), cyclic guanosine 3', 5'-monophosphate (cyclic GMP) and dopamine-beta-hydroxylase (DBH) enzyme activity were measured in 32 patients with pulmonary tuberculosis and 30 normal volunteers. Moreover, the peripheral arterial-venous difference of concentration of these substance, arterial blood gas levels and spirometric data were studied in these patients. The results of this study demonstrated that the plasma NE and cyclic AMP concentrations were directly related to the degree of hypoxemia and some of the spirometric parameters in these patients. It is concluded that sympathetic nervous activity was augmented in chronic hypoxic states, especially with chronic respiratory failure.

Plasma norepinephrine (NE) concentration was measured in blood samples from the pulmonary artery (PA), the superior vena cava (SVC), the inferior vena cava (IVC) and the femoral artery (FA) in 34 patients undergoing diagnostic cardiac catheterization. In patients with pulmonary hypertension, the mean plasma NE concentrations in PA, SVC and FA were significantly higher than that of IVC, but no such difference was found in patients without such hypertension. Except in IVC, the plasma NE concentration in patients with pulmonary hypertension was significantly higher than in others. Furthermore, the plasma NE concentration was positively correlated with the mean pulmonary arterial pressure and inversely related to pulmonary arterial oxygen saturation in patients without a shunt. These results suggest the possibility that vasoconstriction by the sympathetic nervous system may contribute to the development of pulmonary hypertension in patients without the shunt.

Twenty-three patients with chronic respiratory failure and 30 normal subjects were studied to assess the sympathetic nervous activity in chronic hypoxic states, especially in chronic cor pulmonale. Of the 23 patients, 13 had a right ventricular hypertrophy (RVH) pattern on the electrocardiogram. Plasma norepinephrine (NE), dopamine-beta-hydroxylase (DBH), cyclic adenosine 3',5'-monophosphate (cyclic AMP) and cyclic guanosine 3',5'-monophosphate (cyclic GMP) concentrations were measured before and after oxygen inhalation. Plasma NE concentrations were 0.57 +/- 0.07 ng/ml in patients with chronic respiratory failure and 0.22 +/- 0.02 ng/ml in controls (p less than 0.001). Moreover, plasma NE concentrations were higher in patients with RVH than without (p less than 0.05), and these concentrations decreased significantly (p less than 0.05) in the former patients after oxygen inhalation. Plasma cyclic AMP concentrations were 31.2 +/- 2.6 pmol/ml in cases of chronic respiratory failure and 17.4 +/- 0.7 pmol/ml in controls (p less than 0.001) with no difference in plasma cyclic GMP and DBH concentrations. These results suggest that a significant proportion of patients with chronic respiratory failure, especially with cor pulmonale, were in hyper-adrenergic states partially due to hypoxia.

The plasma concentrations of norepinephrine (NE), adenosine cyclic 3', 5'-monophosphate (cyclic AMP), and guanosine cyclic 3', 5'-monophosphate (cyclic GMP) were measured serially for 2 weeks after the onset of symptoms in 17 patients with acute myocardial infarction (AMI). The mean concentrations of NE in patients without complications were significantly elevated during the first 2 days following AMI. There was a significant correlation between the maximum concentration of plasma NE and of plasma CK. The mean concentrations of plasma cyclic AMP and cyclic GMP in patients without complications were significantly elevated on the first day and for 8 days respectively following AMI. The concentration of plasma cyclic AMP on admission in patients with complications was significantly higher than that in those without complications. There were significant correlations between the maximum concentration of plasma cyclic AMP and those of plasma CK, GOT, and LDH. Significant but weak correlations between the concentration of plasma NE and those of cyclic AMP and cyclic GMP were found. The results of the present study suggest an enhanced sympathetic nervous system activity at an early stage of AMI, a prolonged enhancement of parasympathetic nervous system activity in the course of AMI, and the potential value of plasma cyclic AMP concentrations as a useful index to estimate the seriousness and size of AMI.