Orientational Dynamics of Magnetic Iron Oxide Nanoparticles in a Hydrogel: Observation by Magnetic Linear Dichroism under Oscillating Field.

For the success of biomedical applications of magnetic iron oxide nanoparticles (MION), such as magnetic hyperthermia and magnetic particle imaging, it is essential to understand the orientational dynamics of MION in a complex fluid under an alternating field. Here, using the magnetic linear dichroism (MLD) measurement, we directly observed the orientational behavior of MION in a hydrogel under a damped oscillating magnetic field (DOMF) of 33 kHz in frequency. Hydrophobically modified ethoxylated urethane (HEUR) is examined as the network polymer because the mesh size of the network is controllable with its concentration. We used two MIONs: a bare MION (MION1) and a MION coated with an amphiphilic polymer (MION2). Where the mesh size of the gel network is larger than the particle's hydrodynamic diameter, MION1 in the hydrogel rotates in the same manner in a simple solution, although the macroscopic rheological property of the medium is quite different. Meanwhile, the orientational behavior of MION2 is dramatically changed by the addition of HEUR molecules even below the minimum gelation concentration, indicating that MION2 is associated with the flower micelles of HEUR. By analyzing the MLD waveform, the orientational behavior of MION1 in the HEUR gel under a DOMF can be explained with single-mode relaxation, whereas that of MION2 is complicated; a rapid partial rotation near the particle and a whole slow rotation of the particle-flower micelle associate are superimposed. It is hard to distinguish this difference in orientational behaviors from the dynamic magnetization curve because the dominant magnetization reversal process is Néel rotation, the rotation of the magnetic moment in the particle. The MLD measurement is a potential tool for optimizing biomedical techniques utilizing MIONs and for nanorheology or colloid science in a complex matrix such as a hydrogel or cytoplasmic matrix.

Utility of CT texture analysis to differentiate olfactory neuroblastoma from sinonasal squamous cell carcinoma.

The purpose of this study was to examine differences in texture features between olfactory neuroblastoma (ONB) and sinonasal squamous cell carcinoma (SCC) on contrast-enhanced CT (CECT) images, and to evaluate the predictive accuracy of texture analysis compared to radiologists' interpretations. Forty-three patients with pathologically-diagnosed primary nasal and paranasal tumor (17 ONB and 26 SCC) were included. We extracted 42 texture features from tumor regions on CECT images obtained before treatment. In univariate analysis, each texture features were compared, with adjustment for multiple comparisons. In multivariate analysis, the elastic net was used to select useful texture features and to construct a texture-based prediction model with leave-one-out cross-validation. The prediction accuracy was compared with two radiologists' visual interpretations. In univariate analysis, significant differences were observed for 28 of 42 texture features between ONB and SCC, with areas under the receiver operating characteristic curve between 0.68 and 0.91 (median: 0.80). In multivariate analysis, the elastic net model selected 18 texture features that contributed to differentiation. It tended to show slightly higher predictive accuracy than radiologists' interpretations (86% and 74%, respectively; P = 0.096). In conclusion, several texture features contributed to differentiation of ONB from SCC, and the texture-based prediction model was considered useful.

Triaxial system in stent-graft placement for traumatic renal artery dissection: A case report.

Stent-graft placement is an important treatment for traumatic renal artery dissection, but it may occasionally be technically difficult to advance a catheter through the lesion of the dissection due to severe stenosis of the true rumen. A triple-coaxial (triaxial) system, which consists of a small microcatheter, a large microcatheter, and a 4-Fr. catheter, has recently become available, and it contributes to super-selective catheterization. We thought this system may be useful for passing catheters through the dissection. We herein report a 30-year-old male patient with traumatic renal artery dissection, who was successfully treated by stent-graft placement using the triaxial system.

Use of 0.014-in. pushable bare platinum coils in super-selective embolization through the 1.6-Fr. microcatheter of the triaxial system.

BACKGROUND: A triple-coaxial (triaxial) system, which consists of a small microcatheter, a large microcatheter, and a 4-Fr. catheter, has been reported to allow super-selective catheterization. A 1.6-Fr. microcatheter has recently become available as the small microcatheter for the triaxial system, in addition to 0.014-in. pushable bare platinum coils that may be introduced into the 1.6-Fr. microcatheter. PURPOSE: The purpose of the present study was to evaluate the feasibility of 0.014-in. pushable bare platinum coils in embolization through the 1.6-Fr. microcatheter of the triaxial system. MATERIAL AND METHODS: Between November 2015 and October 2019, 19 embolizations were performed on 18 patients, 9 males and 9 females with a median age of 77 years (range, 41-88 years), using 0.014-in. pushable bare platinum coils through the 1.6-Fr. microcatheter of the triaxial system. The technical success rate, clinical success rate, and complications associated with the procedure were assessed. Technical success was defined as the successful delivery and placement of 0.014-in. pushable bare platinum coils, and clinical success as the immediate postembolic complete cessation of blood flow confirmed by digital subtraction angiography. RESULTS: Eighty-four 0.014-in. pushable bare platinum coils were delivered and 19 arteries were successfully embolized. The median number of 0.014-in. pushable bare platinum coils was 4 (range, 1-12). The technical success rate was 100% (84/84) and the clinical success rate was also 100% (19/19). There were no complications associated with the procedures. CONCLUSION: The use of 0.014-in. pushable bare platinum coils in super-selective embolization through the 1.6-Fr. microcatheter of the triaxial system appears to be feasible and safe.

Anchoring Energy Measurements at the Aqueous Phase/Liquid Crystal Interface with Cationic Surfactants Using Magnetic Fréedericksz Transition.

We constructed the apparatus to observe the Fréedericksz transition of liquid crystal in contact with water. The Fréedericksz transition is a distortion of nematic liquid crystals (LCs) induced by external fields. In the present system, sweeping homogeneous magnetic field was applied to the sample, and the distortion of the LC was visualized with a polarized light microscope with the crossed Nichols configuration. The anchoring energy (WAQ/LC) at the aqueous phase/LC interface was measured in the presence of surfactant from the threshold magnetic field of the Fréedericksz transition. We studied two cationic surfactants: dodecyltrimethylammonium bromide and tetradecyltrimethylammonium bromide. A nematic LC, 4-cyano-4'-pentylbiphenyl (5CB), was examined, which was confined in a copper grid on an octadecyltrichlorosilane-treated microscope glass plate. Measured WAQ/LC were reproducible and showed consistence with the reported region for the water/LC interface. Interfacial excess of surfactants was also measured by the pendant drop method, and the relationship between the obtained WAQ/LC and the interfacial excess was investigated. Experiments showed that an increase in the anchoring energy depends on the surfactant and its interfacial excess. The region of the interfacial coverage, at which WAQ/LC increases, varied with the chain length of the surfactant. The measurement of the anchoring energy will provide new fundamental information on aqueous phase/LC interface.

Development of Plasmonic Cu2O/Cu Composite Arrays as Visible- and Near-Infrared-Light-Driven Plasmonic Photocatalysts.

We describe efficient visible- and near-infrared (vis/NIR) light-driven photocatalytic properties of hybrids of Cu2O and plasmonic Cu arrays. The Cu2O/Cu arrays were prepared simply by allowing a Cu half-shell array to stand in an oxygen atmosphere for 3 h, which was prepared by depositing Cu on two-dimensional colloidal crystals with a diameter of 543 or 224 nm. The localized surface plasmon resonances (LSPRs) of the arrays were strongly excited at 866 and 626 nm, respectively, at which the imaginary part of the dielectric function of Cu is small. The rate of photodegradation of methyl orange was 27 and 84 times faster, respectively, than that with a Cu2O/nonplasmonic Cu plate. The photocatalytic activity was demonstrated to be dominated by Cu LSPR excitation. These results showed that the inexpensive Cu2O/Cu arrays can be excellent vis/NIR-light-driven photocatalysts based on the efficient excitation of Cu LSPR.

Zero-velocity magnetophoretic method for the determination of particle magnetic susceptibility.

A simple zero-velocity method to determine the particle magnetic susceptibility by measuring the magnetophoretic velocity was proposed. The principle is that the magnetophoretic velocity of a particle in a liquid medium must be zero when the magnetic susceptibilities of the medium and the particle are equal, or the gravity force and the magnetophoretic force are balanced. By changing the medium magnetic susceptibility and measuring the magnetophoretic velocity of a particle, the particle magnetic susceptibility was determined from the medium magnetic susceptibility under the zero-velocity condition. The feasibility of the method was demonstrated for polystyrene particles using a Dy(III) solution in the horizontal migration mode and different organic solvents in the vertical migration mode.

Fermentative production of nervonic acid by Mortierella capitata RD000969.

A high-nervonic acid (cis-15-tetracosenoic acid, C24:1, n-9)-producing filamentous fungus of the Mortierella species was discovered among soil filamentous fungi. The filamentous fungal strain -RD000969- was isolated from soil collected in Kanagawa Prefecture (Japan) and was found to accumulate nervonic acid at a rate of 6.94% of the total cellular fatty acids. The base sequences of 28S rDNA D1/D2 and ITS 5.8S rDNA showed 100% homology with Mortierella capitata CBS 293.96. In addition to nervonic acid, strain RD000969 produced a large amount of long-chain monounsaturated fatty acids (C20:1, 12.22%; C22:1, 4.07%; C26:1, 5.91%) and a small amount of ultra-long-chain fatty acids (C28:1, 0.44%; C30:1, 0.06%; C32:1, trace). In the fungal cells, 98.87% of nervonic acid was localized at the sn-1,3 position of triacylglycerol. Nervonic acid production was maximum (186.3 mg·L(-1)) when the fungus was cultured in potato dextrose (PD) medium containing yeast extract, CaCl2, and MgSO4·7H2O.

Faraday rotation dispersion microscopy imaging of diamagnetic and chiral liquids with pulsed magnetic field.

We have constructed an experimental setup for Faraday rotation dispersion imaging and demonstrated the performance of a novel imaging principle. By using a pulsed magnetic field and a polarized light synchronized to the magnetic field, quantitative Faraday rotation images of diamagnetic organic liquids in glass capillaries were observed. Nonaromatic hydrocarbons, benzene derivatives, and naphthalene derivatives were clearly distinguished by the Faraday rotation images due to the difference in Verdet constants. From the wavelength dispersion of the Faraday rotation images in the visible region, it was found that the resonance wavelength in the UV region, which was estimated based on the Faraday B-term, could be used as characteristic parameters for the imaging of the liquids. Furthermore, simultaneous acquisition of Faraday rotation image and natural optical rotation image was demonstrated for chiral organic liquids.

Surface tension determination through measurements of resonance oscillation of a small surface using dielectric force by a localized alternating current electric field.

The present study proposed a novel microscope method for the determination of the surface tension of liquids through measurements of the forced oscillation of the small surface, which was induced with a rod electrode by applying an alternating current (ac) voltage. The electrode bottom was placed 200 µm above the surface, and a stronger electric field was generated under it. Liquids of a larger dielectric constant than air gathered under the electrode by a dielectric force, and thus the surface was oscillated. The oscillation was successfully analyzed with the forced oscillation model and the oscillation mode of two-dimensional circular membranes. A resonance oscillation was observed, the frequency of which was well related to the ratio of surface tension to density of the liquids. Therefore, the proposed novel method can be used for the determination of surface tensions of small surfaces with known densities.

Single-molecule lactonization of octadecylrhodamine B at a liquid-liquid interface.

The total internal reflection laser fluorescence microscope method was used to observe the lateral diffusion of a single octadecylrhodamine B (C(18)RB) molecule at the toluene-water interface. The interfacial diffusion constant of single fluorescent cation C(18)RB(+) was obtained from the maximum residence time in a small observation area with pH <2. For pH >3, the maximum residence time was remarkably shortened, indicating that single fluorescent zwitterion C(18)RB(±) rapidly converted to the nonfluorescent lactone at the interface. The lactonization rate was completed within 0.13 ms at the toluene-water interface but slowed to 67 ms at an interface saturated with dimyristoylphosphatidylcholine.

Microscope measurements for the transient formation of W/O emulsions of sodium bis(2-ethylhexyl) sulfosuccinate in the dodecane/water interfacial region.

The present study investigated the transient formation of water-in-oil (W/O) emulsions of sodium bis(2-ethylhexyl) sulfosuccinate (aerosol OT, AOT) in a dodecane/water interfacial region and the anomalous uptake of water in the dodecane phase by in situ bright-field optical microscopy and water concentration measurements in detail. The hydrodynamic radius of the individual W/O emulsions in the dodecane phase was determined to be 0.1-1.2 µm from the analysis of their diffusion behavior; they are much larger than common W/O microemulsions (a few nanometers in radius). At first, they were formed spontaneously in the dodecane/water interfacial region without shaking, and they diffused away into the dodecane phase. Then, almost all of them vanished at the interface by fusion. Their number and the water concentration in the dodecane phase increased first and then decreased gradually. The formation mechanism was discussed with estimated concentration profiles of AOT and water molecules, which suggests that larger W/O emulsions of 0.01-0.44 µm in radius can be formed in the dodecane phase near the interface (within 2 µm) because the concentration of AOT becomes lower than that of water there.

Chemiluminescence from an oxidation reaction of rhodamine B with cerium(IV) in a reversed micellar medium of cetyltrimethylammonium chloride in 1-hexanol-cyclohexane/water.

The chemiluminescence (CL) emission, observed when rhodamine B (RB) in 1-hexanol-cyclohexane was mixed with cerium(IV) sulfate in sulfuric acid dispersed in a reversed micellar medium of cetyltrimethylammonium chloride (CTAC) in 1-hexanol-cyclohexane/water, was investigated using a flow-injection system. The CL emission from the oxidation reaction of RB with Ce(IV) was found to be stronger in the CTAC reversed micellar solution compared with an aqueous solution. Bearing on the enhancement effect of the CTAC reverse micelles on the RB-Ce(IV) CL, several studies including stopped-flow, fluorescence and electron spin resonance (ESR) spectrometries were performed. Rapid spectral changes of an intermediate in the RB-Ce(IV) reaction in the aqueous and reversed micellar solutions were successfully observed using a stopped-flow method. The effect of the experimental variables, i.e., oxidant concentration, sulfuric acid concentration, the mole fraction of 1-hexanol, water-to-surfactant molar concentration ratio, flow rate, upon the CL intensity was evaluated. Under the experimental conditions optimized for a flow-injection determination of RB based on the new reversed micellar-mediated CL reaction with Ce(IV), a detection limit of 0.08 µmol dm(-3) RB was achieved, and a linear calibration graph was obtained with a dynamic range from 0.5 to 20 µmol dm(-3). The relative standard deviation (n = 6) obtained at an RB concentration of 3 µmol dm(-3) was 3%.

Acid-base behavior of rhodamine B in a reversed micellar medium of cetyltrimethylammonium chloride in 1-hexanol-cyclohexane/water.

The acid-base behavior of rhodamine B (RB) in reversed micellar solutions of cetyltrimethylammonium chloride (CTAC) in 1-hexanol-cyclohexane/water was investigated through absorption and fluorescence measurements under varying the hydrogen-ion concentration in a water pool, the mole fraction of 1-hexanol in a bulk solvent and the water to surfactant molar concentration ratio. RB exhibited equilibria between the cationic, zwitterion and lactone forms of the dye as a cause of the spectral changes, indicating a change in the RB distribution among the reversed micellar water pool, interface and bulk solvent. Furthermore, RB was used as a probe to develop a method for determining the critical micelle concentration (CMC) in CTAC solutions. Abrupt variations in the intensities and wavelengths of the absorption and emission maxima of RB were observed at the CMC. The standard free energy of micellization was also evaluated from the CMC data.

Direct determination of bromine in plastics by electrothermal vaporization/inductively coupled plasma mass spectrometry using a tungsten boat furnace vaporizer and an exchangeable sample cuvette system.

A tungsten boat furnace vaporization inductively coupled plasma mass spectrometry (TBF/ICP-MS) method has been applied to the direct determination of bromine in plastic samples. In the pretreatment, the plastic sample is spread over a small sample cuvette made of tungsten by treating it with a strongly basic organic solution, e.g., octanol or diisobutyl ketone in the presence of potassium hydroxide. The cuvette is placed on a tungsten boat furnace, with which the electrothermal vaporizer is equipped. At the vaporization step, a widely spread thin layer of the sample facilitates its efficient evaporation and introduction into an ICP mass spectrometer. The most remarkable feature is that all the bromine species in plastic samples are decomposed to form a thermally stable inorganic salt during the pretreatment procedure. Therefore, the bromine content in plastic samples can be measured by a calibration curve method constructed with an aqueous standard solution of potassium bromate(V). The detection limit (3sigma) was estimated to be 0.77 pg of bromine, which corresponds to a concentration of 0.31 ng g(-1) of bromine in plastic samples when a sample amount taken of 2.5 mg is studied. The relative standard deviation was calculated to be 2.2%. Analytical results of some plastic samples, which contained both inorganic bromide salts and also organic bromine species, are given.

In situ measurements of emission transition dipole moment of individual ordered microdomain of diprotonated tetraphenylporphine aggregate formed at dodecane/aqueous H2SO4 interface.

Rhombic-ordered microdomains of diprotonated 5,10,15,20-tetraphenylporphine aggregate, whose sizes were 10-200 microm, were formed at dodecane/aqueous H(2)SO(4) interfaces. The light excitation of their two absorption bands (410 and 473 nm for H- and J-bands, respectively) led to one fluorescence band at longer wavelength (723 nm). The direction of the emission transition dipole moment (mu(e)) of individual rhombic microdomains, determined with an in situ optical microscope and a linear polarizer, was almost parallel to the major axis, which was also almost parallel to the direction of the absorption transition dipole moment of their J-bands. Their absorption and emission transition scheme was proposed.

Adsorption behavior of the cetyltrimethylammonium chloride reverse micelles on porous silica gels.

The adsorption behavior of reverse micelles of cetyltrimethylammonium chloride (CTAC) onto porous silica gels of various pore sizes has been investigated. A decrease in the amount of CTAC in the reversed micellar bulk solution in chloroform/water added to the silica gel in a column was observed, indicating the CTAC adsorption onto the silica surface. The adsorption profile obtained showed a maximum of the adsorbed surfactant amount, where the point of surface saturation may be reached, beyond which the adsorption amount remained unchanged. The adsorption of CTAC was also dependent on the specific surface area of the silica gel used. These results suggest that a CTAC monolayer may be formed and completed on the silica surface. The adsorbed CTAC amount slightly decreased with increasing the water to surfactant molar ratio, R, in the reversed micellar bulk solution, although at R < 2 the CTAC adsorption remained constant with silica gels having larger pore diameters. Even in the presence of traces of water moisture in the bulk solution used for the CTAC adsorption, the adsorption of water on silica gel was also observed and the molar ratios, R(Gamma), of the water to surfactant adsorbed on different silica gels were almost unity, implying that the silica gel may tend to hold some of water molecules originally adsorbed on its surface. The adsorption of CTAC molecules appears to occur through the adsorbed water molecules, probably polarized at the silica surface, and a CTAC-water-silica nanointerface seems to be formed. The adsorbed water amount or R(Gamma) also increased with an increase in R and on silica gels with larger pore diameters and a plateau was observed in the R range of 3 - 4, beyond which an increase in R(Gamma) occurred again. The water molecules present in the vicinity of the adsorbed CTAC and the silica surface may possess different properties at different R and R(Gamma) values.

In situ fluorescence microscopic investigation into the dependence of conformation and electrophoretic velocity of single DNA molecules on acid or spermidine concentration.

A measurement cell for DNA migration was fabricated by agarose gel on a glass plate for the purpose of in situ fluorescence microscopic measurements of the electrophoretic behaviors of single giant DNA (T4GT7DNA, 165600 base pairs) molecules. The cell was connected to an original circuit that can supply a constant electric field strength to a DNA-migration-space of the cell. Conformation and electrophoretic velocity of single DNA molecules were measured at the same time as a function of acid or spermidinium concentration. As a result, the conformational change from the random-coiled to globular states and reduced electrophoretic velocities were induced by an addition of acid or spermidinium. The change of the electrophoretic velocity was quantitatively attributable to the partial neutralization of anionic phosphate groups of DNA molecules by H(+) or tricationic spermidinium. The acid-dissociation constant of the conjugate acid of phosphate group of the DNA molecules (pK(a)) and the association constant of the phosphate groups of DNA molecule with tricationic spermidinium (K(ass)) were determined to be 2.0 and 5.5 x 10(3) dm(3) mol(-1), respectively.