Kohei Yoshimoto

Thermal and optical properties of La 2 O 3 -Nb 2 O 5 high refractive index glasses

(100−x)La2O3-xNb2O5 glasses with high refractive indices (>2.1) and low wavelength dispersion were prepared by containerless processing. All the glasses were colorless and transparent in the visible region. The glass forming region was divided into two regions: a high-La2O3-content (39 ≤ x ≤ 42) region and a high-Nb2O5-content (60 ≤ x ≤ 75) region. The dependence of the physical properties on the composition for these two types of glasses was different, implying that the high-La2O3-content glasses (La glasses) and high-Nb2O5-content glasses (Nb glasses) were intrinsically different. A large difference in the molar volumes of the two types of glasses indicated that the Nb glasses were more densely packed than the La glasses. Furthermore, the oxygen polarizabilities estimated from the molar volumes and refractive indices were greater than 2.43 A3 for the La glasses, while those for the Nb glasses decreased from 2.43 A3 with decreasing x. The large oxygen polarizabilities, as compared to those of conventional optical glasses, indicate a particularly high degree of ionic character for the component elements in the glasses. These results suggest that both the La and Nb glasses are desirable materials for high-valued optics, such as lenses with high power and high resolution as well as wide viewing angles used for a digital camera in a smartphone.

Bandgap control using strained beam structures for Si photonic devices

We have demonstrated that bandgap energy of Si can be controlled by micro-mechanically structured Si beams (250 nm thick, 3 μm wide, and 15 μm long) elastically deformed by an external force. Microscopic photoluminescence spectroscopy reveals that downward bending of the beam by 3 μm reveals a red shift in the peak from ~1100 nm up to ~1300 nm. It is found from calculations based on deformation potentials and finite element method that tensile strain as large as ~1.5% is generated in the top surface of the deformed beam and responsible for the red shift of the peak. The presented result should be a proof of concept to cancel wavelength fluctuation unavoidably occurring on uncooled LSIs in terms of stress application, and thereby an enabler of wavelength division multiplexing implementation on a chip. The applications of other beam materials such as Ge and GaAs are discussed.

Low phonon energies and wideband optical windows of La 2 O 3 -Ga 2 O 3 glasses prepared using an aerodynamic levitation technique

xLa2O3-(100 − x)Ga2O3 binary glasses were synthesized by an aerodynamic levitation technique. The glass-forming region was found to be 20 ≤ x ≤ 57. The refractive indices were greater than 1.92 and increased linearly with increasing x. The polarizabilities of oxide ions were estimated to be 2.16–2.41 Å3, indicating that the glasses were highly ionic. The glasses were transparent over a very wide range from the ultraviolet to the mid-infrared region. The widest transparent window among the oxide glasses was from 270 nm to 10 μm at x = 55. From the Raman scattering spectra, a decrease in bridging oxide ions and an increase in non-bridging oxide ions were confirmed to occur with increasing La2O3 content. The maximum phonon energy was found to be approximately 650 cm−1, being one of the lowest among oxide glasses. These results show that La2O3-Ga2O3 binary glasses should be promising host materials for optical applications such as lenses, windows, and filters over a very wide wavelength range.

Kinetic Estimated Glomerular Filtration Rate as a Predictor of Successful Continuous Renal Replacement Therapy Discontinuation: Kinetic eGFR as a Predictor of Successful CRRT Discontinuation

No standardized criteria for continuous renal replacement therapy (CRRT) discontinuation have been established. Kinetic estimated glomerular filtration rate (eGFR) is a newly developed estimation method based on dynamic changes of serum creatinine expected to reflect the true GFR. This study aimed to evaluate the predictive role of kinetic eGFR for CRRT discontinuation.

Findings from two large randomized controlled trials on renal replacement therapy in acute kidney injury

Many issues regarding the management of renal replacement therapy (RRT) in acute kidney injury (AKI) including timing of initiation, selection of RRT modality, and optimal dosing remain to be resolved. Two major randomized controlled trials, the Veterans Affairs/National Institutes of Health (VA/NIH) Acute Renal Failure Trial Network (ATN) and the Randomized Evaluation of Normal versus Augmented Level (RENAL) studies, which were elaborately designed to evaluate the benefit for delivering RRT of higher intensity in critically ill patients, were characterized by their sophisticated design, large sample sizes, and comprehensive data collection. Although no beneficial effect of higher intensity RRT was demonstrated by these studies, many ancillary studies conducted subanalyses which provided additional findings on other important clinical questions that remained unsolved. This review aims to overview the useful information obtained by the VA/NIH ATN and the RENAL studies to gain useful insights for optimal RRT in AKI.

Emission-wavelength control using a mechanically stressed micro-beam structure: GaAs on Si-on-insulator beam

Mechanically stressed micro-beam structures are proposed to control the emission wavelength for III-V compounds on Si-on-insulator wafers. Based on the calculations for GaAs, the tuning of emission wavelength and the locking from temperature fluctuations are demonstrated by controlling the applied stress.