Hypervascular hepatocellular carcinoma in the cirrhotic liver: diffusion-weighted imaging versus superparamagnetic iron oxide-enhanced MRI

Purpose

The purpose of the study was to validate diffusion-weighted imaging (DWI) in the assessment of hypervascular hepatocellular carcinoma (HCC) compared with superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance imaging (MRI) in the cirrhotic liver.

Material and Methods

Forty-six consecutive patients with 106 hypervascular focal lesions in the cirrhotic liver who underwent DWI using three b factors and gadopentetate dimeglumine-enhanced dynamic MRI followed by SPIO-enhanced MRI were enrolled. Two independent radiologists evaluated two separated image sets (SPIO set, dynamic MRI and SPIO-enhanced T2*-weighted images; DWI set, DWI and dynamic MRI) and assigned confidence levels for diagnosis of HCC using a five-point scale for each lesion. Area under the receiver operating characteristic curve (A_z) was calculated for each image set.

Results

The A_z value of the DWI set was larger than the SPIO set by both readers (reader 1, 0.936 vs. 0.900, P=.050; reader 2, 0.938 vs. 0.905, P=.110). For the sensitivity (reader 1, 93.1% vs. 86.2%, P=.146; reader 2, 95.4% vs. 88.5%, P=.070) and specificity (reader 1, 89.5% vs. 73.7%, P=.250; reader 2, 79.0% vs. 73.7%, P=1.000) of HCC diagnosis, DWI sets were superior to SPIO sets without statistically significant differences.

Conclusion

For assessment of hypervascular HCC, DWI in combination with dynamic MRI provides comparable or slightly better information compared with the combination of dynamic and SPIO-enhanced MRI.     

Tunable Properties of Nature-Inspired N,N′-Alkylated Riboflavin Semiconductors

A series of novel soluble nature-inspired flavin derivatives substituted with short butyl and bulky ethyl-adamantyl alkyl groups was prepared via simple and straightforward synthetic approach with moderate to good yields. The comprehensive characterization of the materials, to assess their application potential, has demonstrated that the modification of the conjugated flavin core enables delicate tuning of the absorption and emission properties, optical bandgap, frontier molecular orbital energies, melting points, and thermal stability. Moreover, the thin films prepared thereof exhibit smooth and homogeneous morphology with generally high stability over time.     

Surface ripple changes during Cr film ablation with a double ultrashort laser pulse

Surface modification is investigated experimentally by varying the time separation of double femtosecond laser radiation and surface ripples by varying the time separation and polarization direction of double pulses train. Nanometer-sized particles are formed during resolidification of the molten region when the second pulse arrives within 10 ps and the molten material is ejected much after 10 ps. The ripple in the outer region remains oblique to the sum of the vector direction of the two pulses when the time delay is zero. With time delay ranging from 0.5 to 10 ps and different polarization directions of the laser radiation, the ripple generally aligned perpendicular to the polarization direction of the electric field with multiple pulses in the vicinity of ablation threshold is effectively eliminated without fragments at the edge. Furthermore, remnant ripples on irradiated area at higher energies with the same polarization direction are removed by irradiation at a lower energy with each different polarization direction of double pulse. Based on morphological observations for different time delays, possible mechanisms of ripple formations and eliminations are suggested.     

In situ observation of photo-bleaching in human single living cell excited by a NIR femtosecond laser

The photo-bleaching of single living cells excited by femtosecond laser irradiation was observed in situ to study the nonlinear interaction between ultrafast laser pulses and living human breast MDA-MB-231 cells. We conducted a systematic study of the energy dependence of plasma-mediated photo-disruption of fluorescently labeled subcellular structures in the nucleus of living cells using near-infrared (NIR) femtosecond laser pulses through a numerical aperture objective lens (0.75 NA). The behavior of photo-bleached living cells with fluorescently labeled nuclei was observed for 18 h after femtosecond laser irradiation under a fluorescence microscope. The photo-bleaching of single living cells without cell disruption occurred at between 470 and 630 nJ. To study the photo-disruption of subcellular organelles in single living cells using the nonlinear absorption excited by a NIR femtosecond laser pulse, the process of photo-bleaching without photo-disruption provides key information for clarifying the nonlinear interaction between NIR ultrashort, high-intensity laser light and transparent fluorescently labeled living cells.     

Effects of linking groups in fluorinated aromatic polyamides

Based on dynamic thermogravimetric analysis (TGA) of fluorinated aromatic polyamides, we found that substituting terephthaloyl units for isophthaloyl units usually increased the thermal stability of the polymers. In contrast, the first steps of thermal degradation of poly(5,5′-sulfonyl-2,2′-difluoro-diphenyl terephthalamide) (2,2′-DIF-PSDPT) and poly(5,5′-sulfonyl-2,2′-difluorodphenyl isophthalamide)(2,2′-DIF-PSDPI) followed almost the same curve. This was attributed to the relative flexibility of the ? SO₂? group, and also to the activating effect on the dehydrofluorination reaction, which was believed to be the first step of the degradation of the ortho-fluorinated aromatic polyamides, , resulting in the formation of benzoxazole groups, , on the polymer backbone. With fluorinated aromatic polyamides having ortho fluorine to the amide nitrogen, the electron releasing ? CH₂? group deactivated the nucleophilic substitution of the dehydrofluorination reaction and the electron withdrawing group ? SO₂? activated the reaction, so that the onset degradation temperatures of the fluorinated aromatic units R in followed the order:      

Realization of a large magnetic moment in the ferromagnetic CoPt bulk phase

Changes in the magnetic moment and other physical properties of a CoPt alloy induced by a new type of ion-beam mixing in an external magnetic field were investigated. This process induces the formation of a metastable phase through extremely rapid quenching from well above the ordering temperature. The measured magnetic moment per Co atom was 2.63 mu(B), larger by 55% and 35% than that of the bulk Co and stable CoPt film, respectively, which is one of the highest values ever observed in the ferromagnetic bulk phase.     

Nonlinear features and response mechanisms of a PtO2 mask layer for optical data storage with a superresolution near-field structure

Optical features of a PtO2 mask layer in a superresolution near-field structure are investigated in detail by use of the Z-scan technique. The high photothermal stability of the PtO2 mask is revealed, and a phenomenon in which laser-irradiated PtO2 decomposes to yield Pt particles is confirmed. We also find a physical change in the mask layer that accompanies the chemical decomposition. Microscopic observations and atomic force microscope studies support the theory that the physical deformation is induced by the decomposition of PtO2. It is clear that the optical nonlinear responses of the PtO2 mask layer result from two mechanisms.     

New spectroscopic data, spin-orbit functions, and global analysis of data on the A 1Sigmau+ and b 3Piu states of Na2

The lowest electronically excited states of Na2 are of interest as intermediaries in the excitation of higher states and in the development of methods for producing cold molecules. We have compiled previously obtained spectroscopic data on the A 1Sigmau+ and b 3Piu states of Na2 from about 20 sources, both published and unpublished, together with new sub-Doppler linewidth measurements of about 15,000 A<--X transitions using polarization spectroscopy. We also present new ab initio results for the diagonal and off-diagonal spin-orbit functions. The discrete variable representation is used in conjunction with Hund's case a potentials plus spin-orbit effects to model data extending from v=0 to very close to the 3 2S+3 2P12 limit. Empirical estimates of the spin-orbit functions agree well with the ab initio functions for the accessible values of R. The potential function for the A state includes an exchange potential for S+P atoms, with a fitted coefficient somewhat larger than the predicted value. Observed and calculated term values are presented in an auxiliary (EPAPS) file as a database for future studies on Na2.     

Microwave-assisted derivatization and single-drop microextraction for gas chromatographic determination of chromium(III) in water

A rapid and efficient sample preparation method combining microwave-assisted derivatization (MAD) and single-drop microextraction (SDME) for the gas chromatographic (GC) determination of trace Cr(III) in water was developed. Aqueous Cr(III) was first converted to the volatile chromium trifluoroacetylacetonate (Cr(tfa)3) by reaction with 1,1,1-trifluoroacetylacetone (Htfa) under the irradiation of microwave. Derivatization of Cr(III) at ng ml(-1) level could be completed in less than 1 min. The formed Cr(tfa)3 was then extracted into a small droplet (2 microl) of toluene suspended at the tip of a microsyringe needle. The optimal extraction time was 30 min. The solvent drop was directly injected into a GC equipped with a flame photometric detector (FPD) for analysis. The two Cr(tfa)3 isomers extracted could be efficiently separated in 2 min. Linearity (r>0.99) over the concentration range 2-300 ng ml(-1) Cr was obtained and the limit of detection was 0.5 ng ml(-1) Cr. The relative standard deviation was 7.8% at 20 ng ml(-1) Cr (n=5). Applicability of this method to water analysis was examined by analyzing the chromium content in a reference standard water sample and an industrial effluent.     

Kinetics and mechanism of the aminolysis of aryl phenyl chlorothiophosphates with anilines

Kinetic studies of the reactions of aryl phenyl chlorothiophosphates (1) and aryl 4-chlorophenyl chlorothiophosphates (2) with substituted anilines in acetonitrile at 55.0 degrees C are reported. The negative values of the cross-interaction constant rhoXY (rhoXY = -0.22 and -0.50 for 1 and 2, respectively) between substituents in the nucleophile (X) and substrate (Y) indicate that the reactions proceed by concerted SN2 mechanism. The primary kinetic isotope effects (kH/kD = 1.11-1.13 and 1.10-1.46 for 1 and 2, respectively) involving deuterated aniline nucleophiles are obtained. Front- and back-side nucleophilic attack on the substrates is proposed mainly on the basis of the primary kinetic isotope effects. A hydrogen-bonded, four-center-type transition state is suggested for a front-side attack, while the trigonal bipyramidal pentacoordinate transition state is suggested for a back-side attack. The MO theoretical calculations of the model reactions of dimethyl chlorothiophosphate (1') and dimethyl chlorophosphate (3') with ammonia are carried out. Considering the specific solvation effect, the front-side nucleophilic attack can occur competitively with the back-side attack in the reaction of 1'.