The temperature dependence of luminescence from a long-lasting phosphor exposed to ionizing radiation

The temperature dependence of luminescence from a long-lasting phosphor (LLP), SrAl₂O₄ : Eu²⁺,Dy³⁺, exposed to ionizing radiation has been measured to understand the LLP luminescence mechanism. Evaluation of the decay constants of the LLP exposed to -, β- or γ-rays at temperatures from 200 to 390 K showed that the decay constant is divided into four components ranging from 10⁻⁴ to 10⁻¹ s⁻¹ with activation energies of 0.02–0.35 eV.

Total luminous intensity from the LLP with changing irradiation temperature has its maximum value around the room temperature. Irradiation at elevated temperature (390 K) has the total luminescence pattern with monotonous decrease as temperature rises. As a result of evaluating the temperature dependence of luminescence, the luminescence mechanism is considered as follows:

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Fiber-optic devices for local area network application

Recent developments on fiber-optic devices are reviewed from the local area network (LAN) application viewpoint. Future technical trends are also discussed, along with current research activities. In local area network systems, low device cost and easy maintenance or maintenance-free devices are especially required. Light sources and photodetectors suitable for the systems are described. InGaAsP/InP light emitting diodes can cover a broad application field, up to a gigabits per second super high-speed network region. Optical passive devices, which include branching couplers, switches and connectors, are mentioned as essential components. Compact transmitter/receiver module technology is a key factor in realizing optical-fiber local area network systems. An example of 200-Mbit/s transmitter/receiver module is reported.     

Effect of Forming Pressure on the Internal Structure of Alumina Green Bodies Examined with Immersion Liquid Technique

Green bodies prepared by compaction of alumina granules were made transparent by an immersion liquid technique, and the internal structure was characterized with an optical microscope to study the effect of forming pressure on the internal structure. Clear images obtained by the technique provide more detailed information than other existing methods for structures ranging from one to tens of micrometers. Intergranular pores were present between unfractured granules. Their sizes and concentration tended to decrease with increasing forming pressure. However, pores were clearly present even in the green body prepared at 600 MPa. A rod- and needlelike feature was also found and was concluded to correspond to a high-density region. The significance of large pores and high-density regions on processing as well as the details of the technique is discussed.     

Protein modification by a Maillard reaction intermediate methylglyoxal. Immunochemical detection of fluorescent 5-methylimidazolone derivatives in vivo

Methylglyoxal (MG), an endogenous metabolite that increases in diabetes, is a common intermediate in nonenzymatic glycation (Maillard reaction) in vivo. Here we describe the immunochemical approach to the detection of MG adducts in proteins in vitro and in atherosclerotic lesions of human aorta in vivo. The reaction of protein (bovine serum albumin) with MG led to selective loss of arginine and lysine residues, accompanied by the formation of 5-methylimidazolone (N delta-(5-methylimidazolon-2-yl)ornithine) and imidazolysine (1,3-di-lysino-4-methylimidazole) derivatives, respectively. The anti-5-methylimidazolone antibody was prepared by immunizing rabbits with a MG-keyhole limpet hemocyanin conjugate and purifying the serum on an affinity gel prepared by covalent attachment of the 5-methylimidazolone derivative. The antibody cross-reacted with the proteins treated with not only MG but trioses, such as hydroxyacetone, dihydroxyacetone, and glyceraldehyde. The immunohistochemical analysis revealed that atherosclerotic lesions of human aorta contained 5-methylimidazolone derivatives whose distributions were identical to those of advanced glycation end products (AGEs) detected by the anti-AGE antibody.     

Effects of Digital Doping of Mn on Giant Magneto-Optical Properties of Zn1−x Mn x Se Quantum Wells

We have studied effects of the digital-doping profile of MnSe layers on the giant magneto-optical properties in Zn_1?x Mn _x Se-based quantum wells. The giant Zeeman shift energy increases monotonically with increasing spatial overlap of the exciton wavefunction with the 0.5 monatomic-thick effective Mn layers at the interfaces between the digitally doped MnSe layers and nonmagnetic ZnSe layers. Also, a field-induced enhancement factor of the excitonic photoluminescence intensity, because of the suppression of the exciton energy transfer into the d-d transition of Mn-ions, increases linearly with increasing such overlap of the exciton wavefunction with the effective Mn layer. In addition, the formation energy as large as 18.6 meV and the formation time of the magnetic polaron are determined, which are also affected by the digital-doping profile.     

Combined pars plana vitrectomy, lens removal and intraocular lens implantation for complications of diabetic retinopathy. Surgical results in 120 cases

We performed combined vitrectomy, lens removal and posterior chamber intraocular lens implantation for proliferative diabetic retinopathy in 120 eyes of 101 patients. Follow-up periods ranged from 3 to 63 months, with a mean of 17 months. Three lens removal methods were used: extracapsular cataract extraction (14 eyes), phacoemulsification and aspiration (49 eyes), and pars plana phacoemulsification (57 eyes). Preoperative rubeosis iridis or neovascular glaucoma was found in 21 eyes. Gas or temporary silicone oil tamponade was employed in 32 eyes. Surgical results were good, and the postoperative vision was finger counts or below only in 13 eyes. Thus the combined surgery proved to have no serious problems. Our results indicate two important points. (1) It is best to chose either of the following two methods for the lens surgery: phacoemulsification with continuous circular capsulorhexis, self sealing sclerocorneal incision, and in-the-bag fixation of the posterior chamber lens, or pars plana phacoemulsification leaving the anterior capsule, rub off and aspirating the lens epithelial cells, continuous circular capsulorhexis, and posterior chamber lens implantation in front of the anterior capsule from a self-sealing sclerocorneal wound. (2) It is mandatory to do complete vitrectomy and cut out the vitreous gels incarcerated in the sclerotomy site.