Search

Underwater acoustic positioning system (UAPS) is used to know the positions of underwater robots and underwater structures. In ultra-short baseline (USBL) acoustic positioning systems, the three-dimensional position is determined by measuring the time difference of arrival (TDOA). In this paper, we investigate the acoustic positioning system targeting multiple sound sources and propose a simultaneous multi-point measurement method using time division and code division multiplexing (TD-CDM). TD-CDM provides higher position accuracy than code division multiplexing (CDM) and has a much shorter positioning time than time division and multiplexing (TDM). The effectiveness of TD-CDM has been proven by the results of the water tank experiment and simulation.

The carboxylate adducts of OsO4 ([OsO4(X)]−, X− = AcO− and BzO−) were isolated and their structures, physicochemical properties and reactivity were explored. The C(sp3)−H oxygenation mechanism by the carboxylate adducts was discussed based on their kinetics and DFT studies.

A tin(II) complex coordinated by a sterically demanding o-phenylenediamido ligand is synthesized. The ligand is redox-active to reach a tin(II) complex with the diiminobenzosemiquinone radial anion in the oxidation by AgPF6. The tin(II) complex reacts with a series of nosylazides (x-NO2C6H4-SO2-N3; x = o, m, or p) at -30 °C to yield the corresponding nitrene radical bound tin(II) complexes. The nitrene radical complexes exhibit C(sp3)-H activation and amination reactivity.

We herein report a 73-year-old Japanese woman with possible multiple system atrophy-cerebellar form (MSA-C) who suffered from urinary retention (sacral autonomic disorder) for 12 years before exhibiting cerebellar ataxia. A peculiar combination of findings on urodynamics and sphincter electromyography (EMG), e.g. detrusor hyperactivity with impaired contraction (DHIC), detrusor-sphincter dyssynergia (DSD) and neurogenic sphincter EMG (upper and lower neuron-type autonomic dysfunction), seems to have been predictive of future development of MSA.

The redox state of the metallomonooxygenases is finely tuned by imposing specific coordination environments on the metal center to reduce the activation energy for the generation of active-oxygen species and subsequent substrate oxygenation reactions. In this study, copper(II) complexes supported by a series of linear tetradentate ligands consisting of a rigid 6-, 7-, or 8-membered cyclic diamine with two pyridylmethyl (-CH2Py) side arms (L6Pym2, L7Pym2, and L8Pym2) are employed to examine the effects of the coordination environment on the reactivity of their acylperoxide adduct complexes. The UV-vis and electron paramagnetic resonance spectroscopic data indicate that the ligand-field splitting between the dx2-y2 and dz2 orbitals of the starting copper(II) complexes increase with an increase of the ring size of the diamine moiety (L6Pym2 → L7Pym2 → L8Pym2). In the reaction of these copper(II) complexes with m-chloroperbenzoic acid (m-CPBA), the L6Pym2 complex gives a stable m-CPBA adduct complex, whereas the L7Pym2 and L8Pym2 complexes are immediately converted to the corresponding m-chlorobenzoic acid (m-CBA) adducts, indicating that the reactivity of the copper(II) acylperoxide complexes largely depends on the coordination environment induced by the supporting ligands. Density functional theory (DFT) calculations on the m-CPBA adduct complexes show that the ligand-field-splitting energy increases with an increase of the ring size of the diamine moiety, as in the case of the starting copper(II) complexes, which enhances the reactivity of the m-CPBA adduct complexes. The reasons for such different reactivities of the m-CPBA adduct complexes are evaluated by using DFT calculations.

A cyclometalated osmium(III) complex, [OsIIICl(phpy)(tpy)]+ (OsIII(phpy); phpy = 2-C6H4-2′-C5H4N-κC,N) is synthesized from OsIIICl3(tpy) (tpy = 2,2′;6′,2″-terpyridine) and 2-phenylpyridine (H-phpy)...

Hydroxylation of cyclohexane with m-chloroperbenzoic acid was examined in the presence of an iron(III) complex supported by a trianionic planar tetradentate ligand. The present reaction system shows a high turnover number of 2750 with a high product selectivity of alcohol (93%). The turnover frequency was 0.51 s-1, and the second-order rate constant (k) for the C-H bond activation of cyclohexane was 1.08 M-1 s-1, which is one of the highest values among the iron complexes in the oxidation of cyclohexane so far reported. The present catalytic system can be adapted to the hydroxylation of substrates having only primary C-H bonds such as 2,2,3,3-tetramethylbutane as well as gaseous alkanes such as butane, propane, and ethane. The involvement of an iron(III) acyl peroxido complex as the reactive species was suggested by spectroscopic measurements of the reaction solution.

C(sp2)–H iodination of m-xylene promoted by a rhodium(III) complex supported by a redox-active ligand, (nBu4N)[RhIIIL3−(MeCN)Cl] (1Cl), is reported. The iodination reaction involves an electrophili...

The rhodium (III) complexes supported by a di-deprotonated o-phenylenediamido ligand, ([Cp*RhIII(C6H4N2tBu2Ph22−)] ([Cp*RhIII(L2−)], 1), and one-electron and two-electron oxidized ligands, [Cp*RhII...

The reaction of osmium tetroxide (OsO

A tin(II) complex coordinated by a sterically demanding

Mechanistic studies are performed on the alkane hydroxylation with m -CPBA ( m -chloroperbenzoic acid) catalyzed by nickel(II) complexes, Ni II (L). In the oxidation of cycloalkanes, Ni II (TPA) acts as an efficient catalyst with a high yield and a high alcohol selectivity. In the oxidation of adamantane, the tertiary carbon is predominantly oxidized. The reaction rate shows first-order dependence on [substrate] and [Ni II (L)] but is independent on [ m CPBA]; v obs = k 2 [substrate][ Ni II (L)]. The reaction exhibited a relatively large kinetic deuterium isotope effect ( KIE ) of 6.7, demonstrating that the hydrogen atom abstraction is involved in the rate-limiting step of the catalytic cycle. Furthermore, Ni II (L) supported by related tetradentate ligands exhibit apparently different catalytic activity, suggesting contribution of the Ni II (L) in the catalytic cycle. Based on the kinetic analysis and the significant effects of O 2 and CCl 4 on the product distribution pattern, possible contributions of (L)Ni II -O• and the acyloxyl radical as the reactive oxidants are discussed.

A tetrahedral CuII alkylperoxido complex [CuII (TMG3 tach)(OOCm)]+ (1OOCm ) (TMG3 tach={2,2',2''-[(1s,3s,5s)-cyclohexane-1,3,5-triyl]tris-(1,1,3,3-tetramethyl guanidine)}, OOCm=cumyl peroxide) is prepared and characterized by UV/Vis, cold-spray ionization mass spectroscopy (CSI-MS), resonance Raman, and EPR spectroscopic methods. Product analysis of the self-decomposition reaction of 1OOCm in acetonitrile (MeCN) indicates that the reaction involves O-O bond homolytic cleavage of the peroxide moiety with concomitant C-H bond activation of the solvent molecule. When an external substrate such as 1,4-cyclohexadiene (CHD) is added, the O-O bond homolysis leads to C-H activation of the substrate. Furthermore, the reaction of 1OOCm with 2,6-di-tert-butylphenol derivatives produces the corresponding phenoxyl radical species (ArO. ) together with a CuI complex through a concerted proton-electron transfer (CPET) mechanism. Details of the reaction mechanisms are explored by DFT calculations.

Much recent attention has been focused on the structure and reactivity of transition-metal superoxide complexes, among which mononuclear copper(II)-superoxide complexes are recognized as key reactive intermediates in many biological and abiological dioxygen-activation processes. So far, several types of copper(II)-superoxide complexes have been developed and their electrophilic reactivity has been explored in C–H and O–H bond activation reactions. Here we demonstrate that a mononuclear copper(II)-(end-on)superoxide complex supported by a N-[(2-pyridyl)methyl]-1,5-diazacyclooctane tridentate ligand can induce catalytic C–C bond formation reaction between carbonyl compounds (substrate) and the solvent molecule (acetone), giving β-hydroxy-ketones (aldol). Kinetic and spectroscopic studies at low temperature as well as DFT calculation studies support a nucleophilic reactivity of the superoxide species toward the carbonyl compounds, providing new insights into the reactivity of transition-metal superoxide species not only in biological oxidation reactions but also in synthetic organic chemistry. Copper(II)-superoxide complexes are known to behave as electrophiles but there are few examples of nucleophilic reactivity by such species. Here a mononuclear copper(II)-superoxide species is shown to promote simple aldol reactions, and this reactivity is found to be sensitive to minor changes to the ligand structure.

Oxido-alcoholato- and oxido-thiolato-molybdenum(VI) complexes bearing two ene-1,2-dithiolate ligands (cyclohexene-1,2-dithiolate) are prepared as synthetic models of molybdenum(VI) reaction centers of dimethyl sulfoxide reductase family of molybdenum enzymes. These complexes are prepared by oxygen atom transfer from tertiary amine N-oxide (trimethylamine N-oxide and N,N-dimethylaniline N-oxide) to the five-coordinate alcoholato- and thiolato-molybdenum(IV) complexes, and are characterized by UV–vis, cold-spray-ionization mass, resonance Raman, and 1H NMR spectroscopies. The oxygen atom transfer reactions are studied kinetically at a low temperature (−40 °C) to demonstrate that the reactivity of the thiolato-molybdenum(IV) complex is higher than that of alcoholato-molybdenum(IV) complex by about 7 times, and that the oxygen atom transfer reactivity increases with increasing the electron withdrawing ability of the p-substituent of N,N-dimethylaniline N-oxide derivatives. Mechanistic details are discussed based on the reactivity studies.

The aim of this study is to prepare transparent foldable poly(methyl methacrylate) (PMMA) based materials by using poly(vinyl butyral) (PVB) with polymerizable group. The influences of PVB content, modification of OH group in PVB, concentration of polymerizable groups, and molecular weight of PVB on the foldability and physical properties such as transparency, mechanical properties, surface hardness of the resulting PVB/PMMA graft copolymers were investigated. The increase of PVB content contributed to the improvement of the folding property but surface hardness was decreased. The introduction of the polymerizable group to the OH group of PVB and the increase of the concentration improved the surface hardness and suppressed the whitening of bent surface. Furthermore, by using PVB having a polymerizable groups, PVB and PMMA were dispersed so finely that the interface cannot be confirmed clearly, and samples containing 10 wt% or more of PVB with a polymerizable groups were foldable and maintained similar mechanical properties and transparency as PMMA. The use of high molecular weight PVB with polymerizable groups promoted the formation of fine phase separated structures, enabled bending at a lower PVB content.

Hydroxylation of cyclohexane with

The author is working on the practical application of the investigation of the underwater offshores structure using ROV equipped with an acoustic camera. The image obtained by mosaic processing of the acoustic camera image is distorted due to the influence of sway during capturing. In this research, we have developed a technology for image correction using position and navigation data from GNSS and INS. The position of the stone embedded in the concrete plate was determined by using the mosaic image created from the image of the acoustic camera with sway suppression by using the rail mechanism and the mosaic image created from the image of the acoustic camera installed in the ROV with sway generated. As a result of verifying the accuracy by the size of the stone, the position error with sway generated was close to the one with sway suppression, and the stone size error was almost close to the actual value.

The aim of this study was to prepare transparent acryl/glass cloth composite materials with low light dispersion and high mechanical properties (modulus and strength) by using E-glass cloth and photo-curable acrylate monomers. The influences of the refractive index of the matrix, and the addition of comonomers and silica nanoparticles treated with silane coupling agent on the transparency, wavelength dependence of transmittance, and tensile properties of the composite materials were investigated. The acryl/glass cloth composite material prepared with E-glass cloth and 2,2-bis[4-(acryloxy diethoxy) phenyl] propane (ABPE4) indicated high transmittance at 600 nm, while the transmittance at 400 nm was reduced due to the scattering at the interface of the matrix and the glass fibers because the refractive index difference was large at shorter wavelengths. The usage of a comonomer with a lower refractive index than ABPE4 was an effective way to decrease the refractive index mismatch between the matrix and the glass fibers, and the transparency of the resulting composite material was improved. Moreover, the mechanical performance of the acryl/glass cloth composite material was increased by adding comonomer with a high affinity for glass cloth to matrix. The addition of silica nano particles treated with a silane coupling agent to the matrix was also a useful method for not only improving the transparency, but also improving the mechanical performance, because the nano particles on the fiber surface reduced the refractive index difference and increased the surface area and bonding strength at the interface of the matrix and the fibers.

This mini-review article summarizes the O2-reactivity of copper(I) complexes supported by a series of 2-(2-pyridyl)ethylamine (Pye) based ligands, which was developed by Karlin and his coworkers for biomimetic copper-oxygen chemistry. Oxygenation reaction of the copper(I) complexes supported by simple bis[2-(2-pyridyl)ethyl]amine tridentate ligands (R′Pye2R) mainly provided (μ-η2:η2-peroxido)dicopper(II) complex 5, but the reaction rates were significantly altered by the ligand substituents R and R′. The peroxide complex 5 induced aliphatic hydroxylation at the benzylic position of the ligand sidearm, when R = –CH2CH2Ph. Mechanistic studies on the aliphatic ligand hydroxylation revealed that the real reactive intermediate was a bis(μ-oxido)dicopper(III) speceis 6 generated in situ by the O–O bond homolysis of 5. On the other hand, peroxide complex 5 induced direct hydroxylation of phenolate derivatives to the corresponding catechols via electrophilic aromatic substitution mechanism, which can be regarded as a model reaction of tyrosinase. When the reaction of copper(I) complexes and O2 was conducted by using 2-(2-pyridyl)ethylamine didentate ligands (R″Pye1R,R′), not only the (μ-η2:η2-peroxido)dicopper(II) complex 5, but also the bis(μ-oxido)dicopper(III) speceis 6 and a mixed-valent bis(μ3-oxido)tricopper(II,II,III) complex 7 were generated, the product type of which was also controlled by the ligand substituents (R, R′, and R″). Reactivities of the generated complexes supported by the didentate ligands R″Pye1R,R′ were also explored. Notably, a tridentate ligand consisting with 2-(2-pyridyl)ethylamine (Pye1) and 8-membered cyclic diamine (RL8Pye) gave a mononuclear copper(II) endo-on superoxide complex 1, when the supported copper(I) complex and O2 was reacted at a low temperature. Such a unique ligand effect of the RL8Pye system were examined using a series of related tridentate ligands. Furthermore, asymmetric (μ-η1:η2-peroxido)dicopper(II) complex 8 was successfully obtained by using a newly designed penta-pyridine ligand (Pye2PyPye2).

Six-coordinate rhodium(III) complexes coordinated by a planar trianionic ligand (L3-) are synthesized. One of the axial positions is occupied by chloride (Cl-), bromide (Br-), or iodide (I-), and another axial position is coordinated by a solvent molecule such as acetonitrile (AN), water (H2O), tetrahydrofuran (THF), or pyridine (PY) to complete an octahedral rhodium(III) center; [RhIII(L3-)(X)(Y)]- (1X/Y; X = Cl-, Br-, or I-, Y = AN, H2O, THF, or PY). Coordination of the AN, H2O, and THF ligands to the metal center is rather weak, so that these solvent molecules are easily replaced by PY to give [RhIII(L3-)(Cl)(PY)]-. In the electrochemical measurements, all complexes have two reversible redox couples based on the ligand-centered oxidation L3- to L•2- and to L-, as reflected by the very similar redox potentials regardless of the different axial ligands. The rhodium(III) complexes catalyze C-H bond amination of xanthene with tosyl azide (TsN3). Because the yields of the aminated product are nearly the same among the complexes, replacement of the axial solvent ligands with TsN3 readily occurs to give a nitrene-radical-bound rhodium(III) complex, [RhIII(L•2-)(N•Ts)(X)]-, as an active oxidant, which is generated by one-electron transfer from the trianionic L3- to the nitrene nitrogen atom. Generation of such a diradical intermediate was substantiated by the direct reaction of 1Cl/AN with TsN3 in the absence of the substrate (xanthene). In this case, a rhodium(III) iminosemiquinone complex, 2, was generated by the intramolecular reaction between the nitrene-radical moiety and the radical moiety of the ligand L•2-.

Copper(II) complexes supported by N 3 -tridentate ligands, consisting of a rigid cyclic diamine (8-membered cyclic-diamine; L8 or 7-membered cyclic-diamine; L7 ) and a 2-(2-pyridyl)ethyl (-CH 2 CH 2 Py) group, were synthesized and structurally characterized. Reaction of the copper(II) complexes and cumene hydroperoxide (CmOOH) in the presence of triethylamine in CH 3 CN gave the corresponding cumylperoxide complexes L8 Cu II OOCm and L7 Cu II OOCm. The UV–vis and EPR spectra suggested that L8 Cu II OOCm takes a tetrahedrally distorted structure, whereas L7 Cu II OOCm has a planar geometry in solution. Resonance Raman spectra of these alkylperoxide complexes indicated that the O-O stretching vibration energy of L8 Cu II OOCm ( ν O–O = 878 cm − 1 ) is somewhat lower than that of L7 Cu II OOCm ( ν O–O = 881 cm − 1 ). Such a difference in O-O bond strength is reflected to the reactivity difference of these two alkylperoxide complexes. Namely, the reactivity L8 Cu II OOCm toward CHD (1,4-cyclohexadiene) as well as solvent molecule (CH 3 CN) is higher than that of L7 Cu II OOCm due to the weaker O-O bond of the former complex as compared to that of the latter complex. Geometric effects on the reactivity induced by the supporting ligands are discussed.

A new tridentate N3 ligand (TMG3tach) consisting of cis,cis-1,3,5-triaminocyclohexane (tach) and three N,N,N′,N′-tetramethylguanidino (TMG) groups has been developed to prepare copper complexes with a tetrahedral geometry and a labile coordination site. Treatment of the ligand with CuIIX2 (X = Cl and Br) gave copper(II)-halide complexes, [CuII(TMG3tach)Cl]+ (2Cl) and [CuII(TMG3tach)Br]+ (2Br), the structures of which have been determined by X-ray crystallographic analysis. The complexes exhibit a four-coordinate structure with C3v symmetry, where the labile halide ligand (X) occupies a position on the trigonal axis. 2Br was converted to a methoxido-copper(II) complex [CuII(TMG3tach)(OMe)](OTf) (2OMe), also having a similar four-coordinate geometry, by treating it with an equimolar amount of tetrabutylammonium hydroxide in methanol. The methoxido-complex 2OMe was further converted to the corresponding phenolato-copper(II) (2OAr) and thiophenolato-copper(II) (2SAr) complexes by ligand exchange reactions wit...

Cross-linked poly(ethyl acrylate-co-methyl methacrylate) (P(EA-MMA)) nanoparticles were prepared by soap-free emulsion polymerization. Size of the isolated nanoparticles in various organic solvents was largely swollen when the solubility parameter of the solvent was similar to that for P(EA-MMA). Well-ordered colloidal crystal assembly film of the P(EA-MMA) nanoparticle was prepared by drying the as-prepared aqueous suspension. The transparent and colorless film exhibited structural color when it was swollen in the organic solvent. Wavelength of the structural color revealed linear relationship with the size of the isolated nanoparticle in the same solvent. This solvent-responsive color-changing behavior explained that the solvent swelling of the nanoparticle increased the repeating distance of the colloidal crystal and the wavelength of the reflected light from the ordered structure. These results suggest that the structural color of the swollen film can be tuned by the solvent quality for P(EA-MMA).

Thermally stable TM1459 cupin superfamily protein from Thermotoga maritima was repurposed as an osmium (Os) peroxygenase by metal-substitution strategy employing the metal-binding promiscuity. This novel artificial metalloenzyme bears a datively bound Os ion supported by the 4-histidine motif. The well-defined Os center is responsible for not only the catalytic activity but also the thermodynamic stability of the protein folding, leading to the robust biocatalyst (Tm ≈ 120 °C). The spectroscopic analysis and atomic resolution X-ray crystal structures of Os-bound TM1459 revealed two types of donor sets to Os center with octahedral coordination geometry. One includes trans-dioxide, OH, and mer-three histidine imidazoles (O3N3 donor set), whereas another one has four histidine imidazoles plus OH and water molecule in a cis position (O2N4 donor set). The Os-bound TM1459 having the latter donor set (O2N4 donor set) was evaluated as a peroxygenase, which was able to catalyze cis-dihydroxylation of several alken...

Key Clinical Message An acute ileus and/or urinary retention are recognized as emergent complications requiring appropriate depressurizing treatments. Meningitis should be suspected as a cause of these autonomic disturbances.

Werner type six-coordinate rhodium(iii) complexes coordinated by a planar trianionic ligand and two axial aniline ligands are synthesised. The trianionic ligand behaves as a redox-active ligand to form a ligand radical species upon one-electron oxidation of the complex. The rhodium(iii) complexes catalyse C-H amination of external substrates such as xanthene with tosylazide as the nitrene source. DFT-calculation and kinetic deuterium isotope effects indicate that a di-radical rhodium(iii) complex formed by one-electron transfer from the redox-active ligand to the nitrene group works as a reactive intermediate to induce aliphatic C-H activation.

Background There has been no report about outcome of pitavastatin versus atorvastatin therapy in high-risk patients with hypercholesterolemia. Methods Hypercholesterolemic patients with one or more risk factors for atherosclerotic diseases (n = 664, age = 65, male = 54%, diabetes = 76%, primary prevention = 74%) were randomized to receive pitavastatin 2 mg/day (n = 332) or atorvastatin 10 mg/day (n = 332). Follow-up period was 240 weeks. The primary end point was a composite of cardiovascular death, sudden death of unknown origin, nonfatal myocardial infarction, nonfatal stroke, transient ischemic attack, or heart failure requiring hospitalization. The secondary end point was a composite of the primary end point plus clinically indicated coronary revascularization for stable angina. Results The mean low-density lipoprotein cholesterol (LDL-C) level at baseline was 149 mg/dL. The mean LDL-C levels at 1 year were 95 mg/dL in the pitavastatin group and 94 mg/dL in the atorvastatin group. There were no differences in LDL-C levels between both groups, however, pitavastatin significantly reduced the risk of the primary end point, compared to atorvastatin (pitavastatin = 2.9% and atorvastatin = 8.1%, HR, 0.366; 95% CI 0.170–0.787; P = 0.01 by multivariate Cox regression) as well as the risk of the secondary end point (pitavastatin = 4.5% and atorvastatin = 12.9%, HR = 0.350; 95%CI = 0.189–0.645, P = 0.001). The results for the primary and secondary end points were consistent across several prespecified subgroups. There were no differences in incidence of adverse events between the statins. Conclusion Pitavastatin therapy compared with atorvastatin more may prevent cardiovascular events in hypercholesterolemic patients with one or more risk factors for atherosclerotic diseases despite similar effects on LDL-C levels.

During recent years, the number of jellyfish in the waters surrounding Japan has been increasing tremendously. Not only does this have a negative impact on the environment, but it is causing serious damage to the fisheries and coastal facilities. Jellyfish chips, i.e., desalted, dried, and shredded jellyfish, can act not only as an effective organic fertilizer, but also as a bioherbicide in paddy fields. However, we observed that following the application of jellyfish chips, the rice yield decreased by approximately 10% compared with that of conventional rice cultivation, and that weed control was insufficient and unstable. To overcome these limitations, we applied rice bran together with jellyfish chips, and compared the rice yield with that achieved by the conventional cultivation practice. The combined application of jellyfish chips and rice bran successfully controlled the weeds in the paddy fields providing a grain yield similar to that of conventional rice cultivation. The improvement in yield might be due to the difference in organic fertilizer composition and the onset time of fertilizer effect. Furthermore, the improvement in herbicidal effect can be attributed to the synergistic effect of different growth suppressing substances in the two organic fertilizers. Overall, the combined use of jellyfish chips and rice bran might be an innovative organic practice in paddy cultivation.

Stereoselective oxidative cyclization of 1,5-dienes with hydrogen peroxide catalyzed by [Os(III)(OH)(H2O)(L-N4Me2)](PF6)2 (1: L-N4Me2 = N,N'-dimethyl-2,11-diaza-[3,3](2,6)pyridinophane) is explored. 1,5-Dienes involving geraniol derivatives are converted to the corresponding tetrahydrofurans in modest to high yields. The products exclusively have the cis-conformation with respect to the substituents at the 2- and 5-positions of the tetrahydrofuran ring. The products also have a syn-conformation with respect to the furan oxygen atom and the hydroxyl groups. Mechanistic studies including a direct reaction of the oxo-hydroxo-osmium(V) complex, 2, with a dihydroxylated geraniol derivative are performed.