Cryogenic changes in seminal protein of cattle and buffalo

The effect of subzero temperatures on the electrophoretic pattern of seminal plasma protein of cattle and buffalo was studied. The profiles of the seminal proteins of these two closely related species differed considerably. Cattle had 11 proteins in the anodic system (pH 8.6) and none in the cathodic system (pH 4.3), while buffalo have 19 in the anodic system (pH 8.6) and 2 proteins in the cathodic system (pH 4.3). Freezing of semen at -5 degrees C for 24 h caused aggregation of seminal proteins in both species. A higher aggregation and loss of proteins were observed when freezing was done in liquid nitrogen at -196 degrees C. The effect was more pronounced in buffalo than in cattle. Loss of more seminal plasma proteins due to cryoinjury in buffalo semen may account for its poorer freezability than that of cattle semen.     

“Unblocking” Serum Activity <Emphasis Type="Italic">in vitro</Emphasis> in the Polyoma System may Correlate with Antitumour Effects of Antiserum <Emphasis Type="Italic">in vivo</Emphasis>

In a variety of tumour systems, individuals carrying progressively growing neoplasms have lymphoid cells with a specific cytotoxic effect on cultured tumour cells from the same individual^1–4. Since the sera of tumour-bearing individuals have been shown to prevent tumour cell destruction by immune lymphocytes in vitro^2,5–8 and since this serum blocking activity appears early in primary and transplant tumour development^5,7, it has been suggested that the appearance of this serum blocking activity might be responsible for the progressive growth of tumours in individuals having cytotoxic lymphocytes. Counteraction of this blocking activity would thus be of primary importance in facilitating the function of an already existing or bolstered cell-mediated immunity. The serum blocking activity might be inhibited in various ways, by preventing the formation of blocking antibody or by interfering with its action (“unblocking”), as demonstrated in Moloney sarcoma regressor sera⁹. This type of serum also has a therapeutic effect on Moloney sarcomas in vivo^10,11, which has been tentatively attributed to its unblocking activity^8,9 or, possibly, to a complement-dependent cytotoxicity¹⁰. Tumour growth in the Moloney sarcoma system, however, might be due in part to continuous recruitment of neoplastic cells by virus-induced transformation and so the therapeutic effect could be due to a virus-neutralizing serum activity^9,10.     

Thermoluminescence studies of zinc borate (ZnB2O4) phosphor doped with rare earths for dosimetric aspects

A series of ZnB₂O₄ phosphors doped with different concentrations of Eu and Dy (0.05 0.1, 0.2, 0.5, 1.0 mol%) and co-doped with Ce (1, 2, 5, 7, 10 mol%) respectively was prepared via the solid-state reaction technique and the thermoluminescence (TL) behaviour of gamma ray-irradiated samples was studied. The synthesized samples were irradiated with γ-rays for the dose range 0.03–1.20 kGy. The TL intensity variations with dose, dopant concentration, and the effect of co-doping were studied. The TL response curves for ZnB₂O₄:Eu³⁺ and ZnB₂O₄:Dy³⁺, ZnB₂O₄:Eu³,Ce³⁺ and ZnB₂O₄:Dy³⁺,Ce³⁺ phosphor were observed. It was revealed that ZnB₂O₄:Eu³⁺ showed a linear TL behaviour for the dose 0.03–1.20 kGy and ZnB₂O₄:Dy³⁺ showed linearity for the gamma dose range 0.03–0.10 kGy. Furthermore, fading for all the samples was observed to be less than 10% for a storage period of 30 days. In addition to this, the trapping parameters, especially activation energies were evaluated using the Ilich method and the initial rise method. The activation energy values obtained from both methods were in complete agreement with each other.     

On the mechanism of ATP-induced shape changes in the human erythrocyte membranes: the role of ATP

In the preceding paper (Sheetz, M. and S.J. Singer. 1977. J Cell Biol. 73:638-646) it was shown that erythrocyte ghosts undergo pronounced shape changes in the presence of mg-ATP. The biochemical effects of the action of ATP are herein examined. The biochemical effects of the action of ATP are herein examined. Phosphorylation by ATP of spectrin component 2 of the erythrocyte membrane is known to occur. We have shown that it is only membrane protein that is significantly phosphorylated under the conditions where the shape changes are produced. The extent of this phosphorylation rises with increasing ATP concentration, reaching nearly 1 mol phosphoryle group per mole of component 2 at 8mM ATP. Most of this phosphorylation appears to occur at a single site on the protein molecule, according to cyanogen bromide peptide cleavage experiments. The degree of phosphorylation of component 2 is apparently also regulated by a membrane-bound protein phosphatase. This activity can be demonstrated in erythrocyte ghosts prepared from intact cells prelabeled with [(32)P]phosphate. In addition to the phosphorylation of component 2, some phosphorylation of lipids, mainly of phosphatidylinositol, is also known to occur. The ghost shape changes are, however, shown to be correlated with the degree of phosphorylation of component 2. In such experiment, the incorporation of exogenous phosphatases into ghosts reversed the shape changes produced by ATP, or by the membrane-intercalating drug chlorpromazine. The results obtained in this and the preceding paper are consistent with the proposal that the erythrocyte membrane possesses kinase and phosphates activities which produce phosphorylation and dephosphorylation of a specific site on spectrin component 2 molecules; the steady-state level of this phosphorylation regulates the structural state of the spectrin complex on the cytoplasmic surface of the membrane, which in turn exerts an important control on the shape of the cell.     

Selective inhibition of prostaglandin biosynthesis by gold salts and phenylbutazone

Gold salts and phenylbutazone selectively inhibit the synthesis of PGF_2α and PGE₂ respectively. Lowered production of one prostaglandin species is accompanied by an increased production of the other. Selective inhibition by these drugs was observed in the presence of adrenaline, reduced glutathione and copper sulphate under conditions when most anti-inflammatory compounds inhibited PGE₂ and PGF_2α syntheses equally. It is postulated that selective inhibitors may have a different mode of action and beneficial effects may be related to the endogenous ratio of PGE to PGF required for normal function.     

Photoluminescence of Alq3‐ and Tb‐activated aluminium–tris(8‐hydroxyquinoline) complex for blue chip‐excited OLEDs

The tris(8‐hydroxyquinoline)–aluminium complex is the most important and widely studied as electron transporting and green light emitting material. Alq₃ and Tb_xAl_(1‐x)q₃ have been synthesized (where x = 0.1, 0.3, 0.5, 0.7 and 0.9) and blended films of Alq₃ and Tb_xAl_(1‐x)q₃ with PMMA and PS at different percentage weight (wt%) concentrations (e.g., 0.1, 1, 5, 10, 25 and 50 wt%) have been prepared. The synthesized materials and their blended thin films have been characterized by a photoluminescence (PL) technique; the synthesis and PL characterization are reported in this paper. The synthesized metal complex shows bright emission of green light with blue light excitation (440 nm) and the prepared Tb_xAl_(1‐x)q₃ phosphor may be applicable in blue chip‐excited OLEDs for the newly developed wallpaper lighting technology. Copyright © 2012 John Wiley & Sons, Ltd.     

Energy transfer between Ce3+ → Gd3+ or Tb3+ in KNaSO4 microphosphor

KNaSO₄ microphosphor doped with Ce,Gd and Ce,Tb and prepared by a wet chemical method was studied using X‐ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence (PL) characterization. KNaSO₄ has a 5‐µm particle size detected by SEM. KNaSO₄:Ce³⁺,Tb³⁺ showed blue and green emission (at 494 nm, 557 nm, 590 nm) of Tb³⁺ due to ⁵D₄ → ⁷F_J (J = 4, 5, 6) transitions. KNaSO₄:Ce³⁺,Gd³⁺ showed luminescence in the ultraviolet (UV) light region at 314 nm for an excitation at 271 nm wavelength. It was observed that efficient energy transfer took place from Ce³⁺ → Gd³⁺ and Ce³⁺ → Tb³⁺ sublattices indicating that Ce³⁺ could effectively sensitize Gd³⁺ or Tb³⁺ (green emission). Ce³⁺ emission weakened and Gd³⁺ or Tb³⁺ enhanced the emission significantly in KNaSO₄. This paper discusses the development and understanding of photoluminescence and the effect of Tb³⁺ and Gd³⁺ on KNaSO₄:Ce³⁺. Copyright © 2015 John Wiley & Sons, Ltd.     

Luminescence in Ba2Sr2Al2O7:RE (RE = Tb3+,Eu3+ and Dy3+) novel aluminate phosphors

The luminescence of novel rare earth ( Tb ^{3 +} , Eu ^{3 +} and Dy ^{3 +} )‐activated Ba ₂ Sr ₂ Al ₂ O ₇ phosphors for solid‐state lighting is presented. The aluminate phosphors were synthesized using a one‐step combustion method. X‐Ray diffraction, scanning electron microscopy and photoluminescence characterizations were performed to understand the mechanism of excitation and the corresponding emission in the as‐prepared phosphor, as characterized the phase purity and microstructure. Improvements in the luminescence properties of the phosphors with rare earth concentration were observed. The phosphor hue could be tuned from blue, green and red by proper selection of rare earth ions in typical concentrations. Effective absorption in the near‐ultraviolet region was observed, which makes the phosphor a potential candidate for ultraviolet light‐emitting diodes. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis and photoluminescence characteristics of (Y,Gd)BO3:RE (RE = Eu3+, Ce3+, Dy3+ and Tb3+) phosphors for blue chip and near‐UV white LEDs

A series of Eu³⁺‐, Ce³⁺‐, Dy³⁺‐ and Tb³⁺‐doped (Y,Gd)BO₃ phosphors was synthesized by a solid‐state diffusion method. X‐Ray diffraction confirmed their hexagonal structure and the scanning electron microscopy results showed crystalline particles. The excitation spectra revealed that (Y,Gd)BO₃ phosphors doped with Eu³⁺, Ce³⁺ , Dy³⁺ and Tb³⁺ are effectively excited with near UV‐light of 395 nm/blue light, 364, 351 and 314 nm, respectively. Photoluminescence spectra of Eu³⁺‐, Ce³⁺‐ and Tb³⁺/Dy³⁺‐doped phosphor showed intense emission of reddish orange, blue and white light, respectively. The phosphor Y_0.60Gd_0.38BO₃:Ce_0.02 showed CIE 1931 color coordinates of (0.158, 0.031) and better color purity compared with commercially available blue BAM:Eu²⁺ phosphor. The phosphor (Y,Gd)BO₃ doped with Eu³⁺, Dy³⁺ and Tb³⁺ showed CIE 1931 color coordinates of (0.667, 0.332), (0.251, 0.299) and (0.333, 0.391) respectively. Significant photoluminescence characteristics of the prepared phosphors indicate that they might serve as potential candidates for blue chip and near‐UV white light‐emitting diode applications. Copyright © 2015 John Wiley & Sons, Ltd.     

Versatility of thermoluminescence materials and radiation dosimetry – A review

Thermoluminescence (TL) materials exhibit a wide range of applications in different areas such as personal dosimetry, environmental dosimetry, medical research etc. Doping of different rare earth impurities in different hosts is responsible for changing the properties of materials useful for various applications in different fields. These materials can be irradiated by different types of beams such as γ‐rays, X‐rays, electrons, neutrons etc. Various radiation regimes, as well as their dose–response range, play an important role in thermoluminescence dosimetry. Several TL materials, such as glass, microcrystalline, nanostructured inorganic materials and recently developed materials, are reviewed and described in this article.