Interphase‐layer effect on deformation of silicone rubber filled with nanosilica particles

The viscoelastic and statically tensile deformation properties of silicone rubber composites filled with nanosilica (300 nm in diameter) and microsilica particles (1.5 μm in diameter) were investigated on the basis of experimental results to clarify the interphase‐layer effect on these properties. The interphase layers formed around the nanoparticles without chemical coating were found to be glassy, even though the composites were in the rubbery state. The interphase layer thickness was determined to be approximately 20 nm using Guth and Gold's mixture law with the viscoelastic properties of the nanoparticle‐filled rubber in the rubbery state. The determined thickness of the interphase layer was confirmed by comparing the maximum strains at fracture for the nanoparticle‐filled rubber, which decreased for higher volume fraction of the nanoparticles. Therefore, the deformation properties were clarified to depend on the volume fraction of the apparent particles composed of the nanoparticles and interphase layers. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45880.     

Microdialysis assessment of 5-fluorouracil release from thermosensitive magnetoliposomes induced by an electromagnetic field in tumor-bearing mice

The current study was designed to evaluate the properties of thermosensitive magnetoliposomes (TMs), a new drug carrier proposed by the authors, in an electromagnetic field pertaining to their selective heating and drug release under an in vivo condition. TMs containing 5-fluorouracil (5-FU) were prepared by reverse-phase evaporation, injected into the tumor mass of B 16-BL6 melanoma in mice, and selectively heated by a 500-kHz electromagnetic field. The release profile of 5-FU from TMs was examined by using a microdialysis technique. The temperature of TMs in the tumor was effectively elevated to 42 degrees C and maintained at this temperature, overcoming the "cooling effect" of blood flow and surrounding tissues. The release kinetics of 5-FU from TMs was successfully analyzed by physiological modeling, which allows the prediction of intratumor drug concentrations during electromagnetic field exposure under various conditions. In conclusion, this study first demonstrated an in vivo evidence for the electromagnetic field-induced thermosensitive release of a drug from TMs in a tumor with the use of microdialysis.     

Purification and properties of a novel sulfatase from Pseudomonas testosteroni that hydrolyzed 3 beta-hydroxy-5-cholenoic acid 3-sulfate

OBJECTIVE: This study aimed to examine ocular rupture force in pig eyes after "minimally invasive radial keratotomy" (MRK) and standard radial keratotomy (SRK). DESIGN: Experimental study. MATERIALS: A total of 71 pairs of pig eyes (51 control eyes) were examined. INTERVENTION: An axial-torsional Materials Testing System (MTS, Eden Prairie, MN) was used to apply blunt force to the corneal surface. A force transducer measured the rupture forces in control eyes and in eyes with MRK or SRK. Five groups of paired eyes were compared: 2.0-mm MRK versus control (N = 12), 3.5-mm MRK versus control (N = 21), 6.5-mm SRK versus control (N = 18), SRK versus 3.5-mm MRK versus 2.0-mm MRK (N = 10). MAIN OUTCOME MEASURE: Ocular rupture force (newtons) was measured. RESULTS: The mean rupture force in newtons was 746.3 for control eyes, 514.2 for 2.0-mm MRK, 353.1 for 3.5-mm MRK, and 246.2 for SRK. Analysis of variance showed a statistically significant difference (P < or = 0.04) between paired comparisons. CONCLUSION: The MRK and SRK significantly weakened ocular integrity compared with control eyes not operated on. MRK required significantly more force to rupture than SRK. MRK eyes, however, ruptured at 50% to 70% of the force required to rupture eyes not operated on. Any patient considering radial keratotomy should be counseled about the risk of greater ocular damage in trauma.     

New high-pressure Sr-Ca-Cu-O compounds and their superconducting properties

It is shown for (Sr, Ca)_1–y CuO_2.00+z (nominal composition) superconductors fabricated under a high pressure of 5 GPa and at 930°C that, as z increases, the Meissner fraction increases from a few percent to 20% and then starts to decrease. In the X-ray powder diffraction pattern for the sample with the maximum Meissner fraction, it is obvious that the infinite-layer structure has been decomposed and a new structure becomes the major phase. It appears that the new structure is the 0223 structure which consists of rock-salt and the infinite-layer type blocks. This material is likely to be a new superconducting cuprate.     

Exciton–Exciton Annihilation in Thermally Activated Delayed Fluorescence Emitter

Recent studies have demonstrated that in thermally activated delayed fluorescence (TADF) materials, efficient reverse intersystem crossing occurs from nonradiative triplet exited states to radiative singlet excited states due to a small singlet–triplet energy gap. This reverse intersystem crossing significantly influences exciton annihilation processes and external quantum efficiency roll‐off in TADF based organic light‐emitting diodes (OLEDs). In this work, a comprehensive exciton quenching model is developed for a TADF system to determine singlet–singlet, singlet–triplet, and triplet–triplet annihilation rate constants. A well‐known TADF molecule, 3‐(9,9‐dimethylacridin‐10(9H)‐yl)‐9H‐xanthen‐9‐one (ACRXTN), is studied under intensity‐dependent optical and electrical pulse excitation. The model shows singlet–singlet annihilation dominates under optically excited decays, whereas singlet–triplet annihilation and triplet–triplet annihilation have strong contribution in electroluminescence decays under electrical pulse excitation. Furthermore, the efficiency roll‐off characteristics of ACRXTN OLEDs at steady state is investigated through simulation. Finally, singlet and triplet diffusion length are calculated from annihilation rate constants.     

An Organic Laser Dye having a Small Singlet‐Triplet Energy Gap Makes the Selection of a Host Material Easier

Quenching of singlets by long‐lived triplets is a serious issue for lasing from organic laser dyes, especially under long pulse excitation. As a strategy to scavenge or manage unnecessary triplets, an organic laser dye is dispersed into a host material having high singlet and low triplet energy levels [a large singlet‐triplet energy gap (ΔE_ST)]. However, finding such a host material having a triplet scavenging capability is limited. In this study, an organic laser dye, 2,6‐dicyano‐1,1‐diphenyl‐λ⁵σ⁴‐phosphinine (DCNP), having a small ΔE_ST of ≈0.44 eV is synthesized, and thus 4‐4′‐bis[(N‐carbazole)styryl] biphenyl (BSBCz) can be employed as a triplet scavenging host, i.e., the triplets formed on DCNP are easily transferred to BSBCz. A 1 wt%‐DCNP‐doped BSBCz film is formed on a mixed‐order distributed feedback grating, showing lasing with a low threshold value of ≈0.86 µJ cm^?2 and a full‐width‐at‐half‐maximum value of ≈0.5 nm. Because of the suppressed singlet‐triplet annihilation, DCNP‐based laser devices operating under a continuous‐wave regime, with a low threshold of 72 W cm^?2 and a long laser half‐lifetime of ≈3 min, are demonstrated. These results indicate a possibility of the wider selection of host materials, easing a material design strategy of fabricating high‐performance laser devices in future.     

Simulating dual-arm robot motions to avoid collision by rigid body dynamics for laboratory bench work

Artificial Life and Robotics - To develop a method by which a dual-arm robot can simulate collision avoidance while replicating motions of a laboratory biologist. Using a kinematic robot model with...     

Sputtering preparation of ferroelectric PLZT thin films and their optical applications

Preparation of epitaxial PLZT thin films on sapphire has been investigated, and excellent ferroelectric properties such as piezoelectricity and electrooptic effect with high transparency were obtained in thin films. Moreover, a preparation process was developed involving the multitarget sputtering method, and strict control of film composition and epitaxial growth with the buffer layer of graded composition were performed. Using these PLZT thin films, some optical applications, including an acoustooptic deflector and an electrooptic guided-light switch, are shown.     

Measurement of electron probe beam diameter by digital image processing

The present report illustrates a computerized method for precise measurement of the diameter of an electron beam. The value of this measurement extends beyond simply providing an accurate estimate of resolution. Other salient areas which will benefit include quantitative X-ray microanalysis, energy loss spectroscopy, diffraction studies, and electron beam lithography. The biological sciences as well as the material sciences will gain enormously from improved accuracy in measurement (control) of beam diameter. It is anticipated that most or all of the mathematical manipulations outlined in this paper will be incorporated into digital electronic packages which will perform the functions automatically for setting the electron beam diameter to the scientist's choice. The purpose of the present report is to indicate some of the principles involved so that as electron microscopy becomes more computerized and automated, the user will have some understanding of what the electronics are doing rather than simply depressing a button or two and ignoring the power of what resides within the walls of the instrument. The performance of a scanning electron microscope (SEM) and a scanning transmission electron microscope (STEM) is roughly determined by the incident electron probe beam size (diameter) involving a sufficient electron current. In the present paper, the diameter of an ultrafine electron beam is measured indirectly from the information given by the blurring of an edge in a STEM or a SEM image of a crystalline specimen with fine, sharp edges. The obtained data were processed by digital image processing methods which give an accurate value of the beam diameter. For confirming the validity of this method, a suitable simulation based on the convolution theorem was performed. By using this measurement, we could measure the diameter of an ultrafine electron beam down to 2 nm, which could not be measured easily by previous techniques.