Thermodynamics of the first transition in writhe of a small circular DNA by Monte Carlo simulation

Monte Carlo simulations are employed to investigate the thermodynamics of the first transition in writhe of a circular model filament corresponding to a 468 base-pair DNA. Parameters employed in these simulations are the torsional rigidity, C = 2.0 × 10⁻¹⁹ dyne cm², and persistence length, P = 500 Å. Intersubunit interactions are modeled by a screened Coulomb potential. For a straight line of subunits this accurately approximates the nonlinear Poisson-Boltzmann potential of a cylinder with the linear charge density of DNA. Curves of relative free energy vs writhe at fixed linking difference (Δ1) exhibit two minima, one corresponding to slightly writhed circles and one to slightly underwrithed figure-8's, whenever Δ1 lies in the transition region. The free energies of the two minima are equal when Δ1_c = 1.35, which defines the midpoint of the transition. At this midpoint, the free energy barrier between the two minima is found to be ΔG_bar = (0.20) k_BT at 298 K. Curves of mean potential energy vs writhe at fixed linking difference similarly exhibit two minima for Δ1 values in the transition region, and the two minimum mean potential energies are equal when Δ1 = 1.50. At the midpoint writhe, Δ1_c = 1.35, the difference in mean potential energy between the minimum free energy figure-8 and circle states is (1.3) k_BT, and the difference in their entropies is 1.3 k_B. Thus, the entropy of the minimum free energy figure-8 state significantly exceeds that of the circle at the midpoint of the transition. The first transition in writhe is found to occur over a rather broad range of Δ1 values from 0.85 to 1.85. The twist energy parameter (E_T), which governs the overall free energy of supercoiling, undergoes a sigmoidal decrease, while the translational diffusion coefficient undergoes a sigmoidal increase, over this same range. The static structure factor exhibits an increase, which reflects a decrease in radius of gyration associated with the circle to figure-8 transition. © 1996 John Wiley & Sons, Inc.     

Partitioning net ecosystem carbon exchange and the carbon isotopic disequilibrium in a subalpine forest

We investigate the utility of an improved isotopic method to partition the net ecosystem exchange of CO₂ (F) into net photosynthesis (F_A) and nonfoliar respiration (F_R). Measurements of F and the carbon isotopic content in air at a high‐elevation coniferous forest (the Niwot Ridge AmeriFlux site) were used to partition F into F_A and F_R. Isotopically partitioned fluxes were then compared with an independent flux partitioning method that estimated gross photosynthesis (GEE) and total ecosystem respiration (TER) based on statistical regressions of night‐time F and air temperature. We compared the estimates of F_A and F_R with expected canopy physiological relationships with light (photosynthetically active radiation) and air temperature. Estimates of F_A and GEE were dependent on light as expected, and TER, but not F_R, exhibited the expected dependence on temperature. Estimates of the isotopic disequilibrium D , or the difference between the isotopic signatures of net photosynthesis (δ_A, mean value ?24.6‰) and ecosystem respiration (δ_R, mean value ?25.1‰) were generally positive (δ_A>δ_R). The sign of D observed here is inconsistent with many other studies. The key parameters of the improved isotopic flux partitioning method presented here are ecosystem scale mesophyll conductance (g_m) and maximal vegetative stomatal conductance (g_cmax). The sensitivity analyses of F_A, F_R, and D to g_cmax indicated a critical value of g_cmax (0.15 mol m^?2 s^?1) above which estimates of F_A and F_R became larger in magnitude relative to GEE and TER. The value of D decreased with increasing values of g_m and g_cmax, but was still positive across all values of g_m and g_cmax. We conclude that the characterization of canopy‐scale mesophyll and stomatal conductances are important for further progress with the isotope partitioning method, and to confirm our anomalous isotopic disequilibrium findings.     

Assessment of annual carbon exchange in a water-stressed Pinus radiata plantation: an analysis based on eddy covariance measurements and an integrated biophysical model

We used a combination of eddy flux, chamber and environmental measurements with an integrated suite of models to analyse the seasonality of net ecosystem carbon uptake (F_CO2) in an 8-year-old, closed canopy Pinus radiata D.Don plantation in New Zealand (42°52′ S, 172°45′ E). The analyses utilized a biochemically based, big-leaf model of tree canopy photosynthesis (A_c), coupled to multiplicative environmental-constraint functions of canopy stomatal conductance (G_c) via environmental measurements, a temperature-dependent model of ecosystem respiration (R_eco), and a soil water balance model. Available root zone water storage capacity at the measurement site is limited to about 50 mm for the very stony soil, and annual precipitation is only 660 mm, distributed evenly throughout the year. Accordingly the site is prone to soil moisture deficit throughout the summer. G _c and A_c obtained maximum rates early in the growing season when plentiful soil water supply was associated with sufficient quantum irradiance (Q_abs), and moderate air saturation deficit (D) and temperature (T). From late spring onwards, soil water deficit and D confined G_c and A_c congruously, which together with the solely temperature dependency of R_eco resulted in the pronounced seasonality in F_CO2. Reflecting a light-limitation of A_c in the closed canopy, modelled annual carbon (C) uptake was most sensitive to changes in Q_abs. However, Q_abs did not vary significantly between years, and changes in annual F_CO2 were mostly due to variability in summer rainfall and D. Annual C-uptake of the forest was 717 g C m^–2 in a near-average rainfall year, exceeding by one third the net uptake in a year with 20% less than average rainfall (515 g C m^–2).     

Some aspects of cooperativity in human hemoglobin

The cooperativity in hemoglobin can be described by the Hill parameter n, the free energy of interaction ΔF₁ and the allosteric free energy ΔF_A. By this latter is meant here the free energy change associated with the transition from the deoxy to the oxy conformation in hemoglobin. In this paper some general relations between n, ΔF₁ and ΔF_A are given. A method is presented by which ΔF_A can be calculated from oxygenation data.     

Solution properties of synthetic polypeptides. XII. Enthalpy changes accompanying helix-coil transition of polypeptide

For helix-coil transitions of polypeptide in binary mixtures consisting of helix-forming solvent and coil solvent, the transition enthalpy ΔH(T,x) has been found to depend significantly on temperature (T) and solvent composition (x). For such systems, calorimetric measurements may yield some averages of ΔH(T,x) which are no longer amenable to direct comparison with ΔH itself. Theoretical equations relating calorimetric data to ΔH(T,x) are derived and tested favorably with experimental data. It is demonstrated that the transition enthaply from heat capacity measurements is approximately equal to ΔH_cfm, while those from heat of dilution and heat of solution measurements are equal to ΔH_c. Here ΔH_c denotes the value of ΔH at the transition point and f_m represents the maximum helical content attained in a thermally induced transition. The discrepancies among calorimetric data are also discussed.     

Comments on a novel approach to the role of chirality in the origin of life

We review a recent paper²⁰ in which a specific enhancement factor (i.e., a phase transition into a condensed Bose mode) is proposed to account for the observed amplification of the ground state energies of the L - and D -amino acid enantiomers; the difference between these energies is assumed to be due to the neutral parity-violating electroweak interaction. This physical effect initially shifts the enantiomer energies by about 3 × 10^?19 eV. The proposed phase transition is characterized by a critical temperature T_c, which may be studied theoretically by enlarging the standard electroweak theory to include either the top quark or supersymmetry²¹. Possible experimental means of finding T_c are discussed.     

Distribution and diffusion of alamethicin in a lecithin/water model membrane system

Summary Attenuated total reflection infrared spectroscopy has been used to determine the equilibrium distribution of the peptide antibiotic alamethicinR _F30 between dipalmitoyl phosphatidylcholine bilayers and the aqueous environment. The distribution coefficientK=c _eq ^W /c _eq ^M turned out to be concentration dependent, pointing to alamethicin association in the membrane with increasing concentration in the aqueous phase (c _eq ^W ). This concentration was varied within 28 and 310nm, i.e., in a range typical for black film experiments. Furthermore, diffusion coefficients of alamethicin in the hydrophobic phase of the membrane (D _M) and across the membrane/water interface (D _I) have been estimated from the time course of the equilibration process. It was found that the diffusion rate of the uncharged analogueR _F50 is about 10 times higher than that of theR _F30 component, exhibiting one negative charge at theC-terminus. The time constants for transmembrane diffusion of alamethicinR _F30 varied between 2.2 hr at low concentration and 3.2 hr at higher concentration. The corresponding low concentration value of theR _F50 component was found to be 0.25 hr.     

TheRT1.G locus in the rat encodes a Qa/TL-like antigen

A new antigenic system in the rat homologous to theQa/TL antigen system in the mouse has been characterized. It was detected by antibodies raised in donor-recipient combinations that were matched for theRT1. A, B, D, E loci in the major histocompatibility complex (MHC): (R11×BN)F₁ anti-BN.1L(LEW), (R18×BN)F₁ anti-BN.1L, and BN.1LV1(F344) anti-BN.1L. Absorption analyses using these antisera and a variety of inbred, congenic and recombinant strains identified three alleles,RT1.G ^a ,G ^b ,G ^c , of whichG ^c is a null allele. The strain distribution of these alleles was determined, using 37 strains of rats representative of all of the prototypic haplotypes and a number of congenic and recombinant strains. The use of the congenic and recombinant strains showed that theRT1.G locus was linked to the MHC and that the most probable gene order wasA-E-G. Testcross analysis showed that the map distance betweenA andG was 1.4 cM(4/285 recombinants). The RT1.G antigen has a heavy chain ofM _r 46 000 and is present on both T and B cells.     

Canopy scale measurements of CO2 and water vapor exchange along a precipitation gradient in southern Africa

Short‐term measurements of carbon dioxide, water, and energy fluxes were collected at four locations along a mean annual precipitation gradient in southern Africa during the wet (growing) season with the purpose of determining how the observed vegetation–atmosphere exchange properties are functionally related to the long‐term climatic conditions. This research was conducted along the Kalahari Transect (KT), one in the global set of International Geosphere‐Biosphere Program transects, which covers a north–south aridity gradient, all on a homogenous sand formation. Eddy covariance instruments were deployed on a permanent tower in Mongu, Zambia (879 mm of rainfall per year), as well as on a portable tower in Maun (460 mm yr^?1), Okwa River Crossing (407 mm yr^?1), and Tshane (365 mm yr^?1), Botswana for several days at each site. The relationships between CO₂ flux, F_c, and photosynthetically active radiation were described well by a hyperbolic fit to the data at all locations except for Mongu, the wettest site. Here, there appeared to be an air temperature effect on F_c. While daytime values of F_c routinely approached or exceeded ?20 μmol m^?2 s^?1 at Mongu, the magnitude of F_c remained less than ?10 μmol m^?2 s^?1 when the air temperature was above 27°C. Canopy resistances to water vapor transfer, r_c, displayed an overall decline from the wetter sites to the more arid sites, but the differences in r_c could be almost exclusively accounted for by the decrease in leaf area index (LAI) from north to south along the KT. Ecosystem water use efficiency (WUE), defined as the ratio of net carbon flux to evapotranspiration, showed a general decrease with increasing vapor pressure deficit, D, for all of the sites. The magnitudes of WUE at a given D, however, were dissimilar for the individual sites and were found to be stratified according to the position of the sites along the long‐term aridity gradient. For example, Mongu, which has the wettest climate, has a much lower WUE for like levels of D than Tshane, which historically has the most arid climate. Given the similar inferred stomatal resistances between the sites, the disparate carbon uptake behavior for the grass vs. woody vegetation is the likely cause for the observed differences in WUE along the aridity gradient. The short‐term flux measurements provide a framework for evaluating the vegetation's functional adaptation to the long‐term climate and provide information that may be useful for predicting the dynamic response of the vegetation to future climate change.     

The Amplitude Distribution of Release Events through a Fusion Pore

Neurotransmitters, hormones, or dyes may be released from vesicles via a fusion pore, rather than by full fusion of the vesicle with the plasma membrane. If the lifetime of the fusion pore is comparable to the time required for the substance to exit the vesicle, only a fraction of the total vesicle content may be released during a single pore opening. Assuming 1), fusion pore lifetimes are exponentially distributed (τ_P), as expected for simple single channel openings, and 2), vesicle contents are lost through the fusion pore with an exponential time course (τ_D), we derive an analytical expression for the probability density function of the fraction of vesicle content released (F): dP/dF = A (1 − F)^(A-1), where A = τ_D/τ_P. If A > 1, the maximum of the distribution is at F = 0; if A < 1, the maximum is at F = 1; if A = 1, the distribution is perfectly flat. Thus, the distribution never has a peak in the middle (0 < F < 1). This should be considered when interpreting the distribution of miniature synaptic currents, or the fraction of FM dye molecules lost during a single fusion pore opening event.     

Near-infrared in vitro measurements of photosystem I cofactors and electron-transfer partners with a recently developed spectrophotometer

A kinetic-LED-array-spectrophotometer (Klas) was recently developed for measuring in vivo redox changes of P700, plastocyanin (PCy), and ferredoxin (Fd) in the near-infrared (NIR). This spectrophotometer is used in the present work for in vitro light-induced measurements with various combinations of photosystem I (PSI) from tobacco and two different cyanobacteria, spinach plastocyanin, cyanobacterial cytochrome c₆ (cyt. c₆), and Fd. It is shown that cyt. c₆ oxidation contributes to the NIR absorption changes. The reduction of (F_AF_B), the terminal electron acceptor of PSI, was also observed and the shape of the (F_AF_B) NIR difference spectrum is similar to that of Fd. The NIR difference spectra of the electron-transfer cofactors were compared between different organisms and to those previously measured in vivo, whereas the relative absorption coefficients of all cofactors were determined by using single PSI turnover conditions. Thus, the (840 nm minus 965 nm) extinction coefficients of the light-induced species (oxidized minus reduced for PC and cyt. c₆, reduced minus oxidized for (F_AF_B), and Fd) were determined with values of 0.207?±?0.004, –?0.033?±?0.006, –?0.036?±?0.008, and –?0.021?±?0.005 for PCy, cyt. c₆, (F_AF_B) (single reduction), and Fd, respectively, by taking a reference value of +?1 for P700⁺. The fact that the NIR P700 coefficient is larger than that of PCy and much larger than that of other contributing species, combined with the observed variability in the NIR P700 spectral shape, emphasizes that deconvolution of NIR signals into different components requires a very precise determination of the P700 spectrum.

     

ATP Synthases With Novel Rotor Subunits: New Insights into Structure,Function and Evolution of ATPases

ATPases with unusual membrane-embedded rotor subunits were found in both F₁F₀ and A₁A₀ ATP synthases. The rotor subunit c of A₁A₀ ATPases is, in most cases, similar to subunit c from F₀. Surprisingly, multiplied c subunits with four, six, or even 26 transmembrane spans have been found in some archaea and these multiplication events were sometimes accompanied by loss of the ion-translocating group. Nevertheless, these enzymes are still active as ATP synthases. A duplicated c subunit with only one ion-translocating group was found along with “normal” F₀ c subunits in the Na⁺ F₁F₀ ATP synthase of the bacterium Acetobacterium woodii. These extraordinary features and exceptional structural and functional variability in the rotor of ATP synthases may have arisen as an adaptation to different cellular needs and the extreme physicochemical conditions in the early history of life.     

Improving green emission of Tb3+ ions in BaO‐B2O3‐P2O5 glasses by means of Al3+ ions

BaO‐B₂O₃‐P₂O₅ glasses doped with a fixed concentration of Tb³⁺ ions and varying concentrations of Al₂O₃ were synthesized, and the influence of the Al³⁺ ion concentration on the luminescence efficiency of the green emission of Tb³⁺ ions was investigated. The optical absorption, excitation, luminescence spectra and fluorescence decay curves of these glasses were recorded at ambient temperature. The emission spectra of terbium ions when excited at 393 nm exhibited two main groups of bands, corresponding to ⁵D₃ → ⁷F_j (blue region) and ⁵D₄ → 7F_j (green region). From these spectra, the radiative parameters, viz., spontaneous emission probability A, total emission probability A_T, radiative lifetime τ and fluorescent branching ratio β, of different transitions originating from the ⁵D₄ level of Tb³⁺ ions were evaluated based on the Judd‐Ofelt theory. A clear increase in the quantum efficiency and luminescence of the green emission of Tb³⁺ ions corresponding to ⁵D₄ → ⁷F₅ transition is observed with increases in the concentration of Al₂O₃ up to 3.0 mol%. The improvement in emission is attributed to the de‐clustering of terbium ions by Al³⁺ ions and also to the possible admixing of wave functions of opposite parities. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis and luminescence properties of Ca3Ga2Si3O12:RE3+ (RE = Eu/Tb) powder phosphors

Rare earth ions (Eu³⁺ or Tb³⁺)‐activated Ca₃ Ga₂ Si₃O₁₂ (CaGaSi) phosphors were synthesized by using a sol–gel method. Photoluminescence spectra of Eu³⁺:CaGaSi phosphors exhibited five emission bands at 578, 592, 612, 652 and 701 nm, which were assigned to the transitions (⁵D₀ → ⁷F₀, ⁷F_1, ⁷F₂, ⁷F₃ and ⁷F₄), respectively, with an excitation wavelength of λ_exci = 392 nm. Among these, the transition ⁵D₀ → ⁷F₂ (612 nm) displayed bright red emission. In the case of Tb³⁺:CaGaSi phosphors, four emission bands were observed at 488 (⁵D₄ → ⁷F₆), 543 (⁵D₄ → ⁷F₅), 584 (⁵D₄ → ⁷F₄) and 614 nm (⁵D₄ → ⁷F₃) from the measurement of PL spectra with λ_exci = 376 nm. Among these, the transition ⁵D₄ → ⁷F₅ at 543 nm displayed bright green emission. The structure and morphology of the phosphors were studied from the measurements of X‐ray diffraction (XRD), scanning electron microscopy (SEM) and energy‐dispersive X‐ray analysis (EDAX) results. Copyright © 2011 John Wiley & Sons, Ltd.     

Effect of hydration upon the thermal stability of tropocollagen and its dependence on the presence of neutral salts

The endotherm enthalpy changes ΔH_D and temperatures T_D of thermal denaturation of tropocollagen fibers were measured by DSC calorimetry as functions of water content. The denaturation temperatures decrease with increasing water content. The enthalpy change values increase sharply in the range 0–28% of water content, where a maximum of 14.3 cal g^?1 is reached. The effect of water uptake on the enthalpy term is explained by water bridge formation within the collagen triple helix. Evidence is given for the existence of approximately three intercatenary water bridges per triplet at the enthalpy maximum, their H-bond energy amounting to approximately 4000 kcal/mol of protein. In the 30–60% range of water content, ΔH_D decreases by 2 cal^?1 probably due to interactions between secondary water structures and the stabilizing intrahelical water bonds. The influence of two neutral potassium salts, with a structure-stabilizing and a structure-breaking anion (F^? and I^?), on the hydration dependence of ΔH_D and T_D was also studied. It was shown that the primary hydration is not influenced by these ions, but that T_D and ΔH_D are altered in an ion specific way in the presence of interface and bulk water. Hydrophobic interactions do not explain the experimental results. A reaction mechanism of the effects of ions upon the structural stability of collagen is proposed and discussed in terms of interactions of the medium water molecules with the intrahelical water bonds, and in terms of proton-donor/proton-acceptor equilibria between peptide groups, hydrated ions, and intrahelical water molecules.     

Intercalation of cationic dyes in the DNA double helix: introductory theory

The effect of salt on the intercalation of acridine dyes and DNA is rather well explained by the Gouy-Chapman double-layer theory as applied to a cylinder model of the DNA–dye complex. The free energy of transfer of a dye ion from the bulk solution to the complex is divided into several parts, one of which, ΔF₀, accounts for the short-range, nonelectrostatic interactions. The assumption that ΔF₀ should not depend on the amount of dye in the complex leads to an internal dielectric constant of the cylinder of about D_i = 7. The scatter in ΔF₀ values, as calculated from individual experimental points, is of order 0.5 kT per dye ion. This scatter is large enough to mask possible effects of heterogeneity in DNA sequences. The calculations are made for a long cylinder with radius 10 Å, with the DNA phosphate charges smeared uniformly at the surface, a uniform spacing of dye charges at the cylinder axis, and a length of b = 3.37 Å per base pair. Each intercalated dye ion also adds a length b to the total length of the cylinder. The salt-dependent part of the electric free energy of intercalation, ΔF₁, is tabulated for complexes with r = 0–0.24 dye ions per DNA phosphate in 0.002–0.2M monovalent salt and dye solutions.     

Effect of circulatory congestion on the components of pulmonary diffusing capacity in morbid obesity

Objective: Obese patients without clinically apparent heart disease may have a high output state and elevated total and central blood volumes. Central circulatory congestion should result in elevated pulmonary diffusing capacity (D_LCO) and capillary blood volume (V_c) reflecting pulmonary capillary recruitment; however, the effect on membrane diffusion (D_m) is uncertain. We examined D_LCO and its partition into V_c and D_m in 13 severely obese subjects (BMI = 51 ± 14 kg/m²) without manifest cardiopulmonary disease before and after surgically induced weight loss. Research Methods and Procedures: D_LCO and its partition into V_c and D_m [referenced to alveolar volume (V_A)] as described by Roughton and Forster, total body water by tritiated water, and fat distribution by waist‐to‐hip ratio were performed. Results: Despite normal D_LCO (mean 98 ± 16% predicted), V_c/V_A was increased (mean 118 ± 30% predicted), and D_m/V_A was reduced (mean 77 ± 34% predicted). Nine of 13 subjects were restudied after weight loss (mean 52 ± 43 kg); V_c/V_A decreased to 89 ± 18% predicted (p = 0.01), and D_m/V_A increased to 139 ± 30% predicted (p < 0.01). Increasing total body water was associated with both increasing V_c (r = 0.74, p = 0.01) and increasing waist‐to‐hip ratio (r = 0.65, p = 0.02), indicating that circulatory congestion increases with increasing central obesity. Discussion: Severely obese subjects without manifest cardiopulmonary disease may have increased V_c indicating central circulatory congestion and reduced D_m suggesting associated alveolar capillary leak, despite normal D_LCO. Reversibility with weight loss is in accord with reversibility of the hemodynamic abnormalities of obesity.     

A chlorophyll fluorescence analysis of photosynthetic efficiency, quantum yield and photon energy dissipation in PSII antennae of Lactuca sativa L. leaves exposed to cinnamic acid

This study investigated the effects of cinnamic acid (CA) on growth, biochemical and physiological responses of Lactuca sativa L. CA (0.1, 0.5, 1.0 and 1.5 mM) treatments decreased plant height, root length, leaf and root fresh weight, but it did not affect the leaf water status. CA treatment (1.5 mM) significantly reduced F_v, F_m, photochemical efficiency of PSII (F_v/F_m) and quantum yield of PSII (ΦPSII) photochemistry in L. sativa. The photochemical fluorescence quenching (qP) and non-photochemical quenching (NPQ) were reduced after treatment with 1.5 mM CA. Fraction of photon energy absorbed by PS II antennae trapped by “open” PS II reaction centers (P) was reduced by CA (1.5 mM) while, portion of absorbed photon energy thermally dissipated (D) and photon energy absorbed by PSII antennae and trapped by “closed” PSII reaction centers (E) was increased. Carbon isotope composition ratios (δ¹³C) was less negative (−27.10) in CA (1.5 mM) treated plants as compared to control (−27.61). Carbon isotope discrimination (Δ¹³C) and ratio of intercellular CO₂ concentration (ci/ca) from leaf to air were also less in CA treated plants. CA (1.5 mM) also decreased the leaf protein contents of L. sativa as compared to control.     

Optical,emission, and excitation dynamics of Eu3+-doped bismuth-based phosphate glass for visible display laser applications

Eu³⁺-doped-bismuth-based phosphate glasses with chemical equation (60 − x)P₂O₅–20Bi₂O₃−10Na₂CO₃–10SrF₂–xEu₂O₃ (PBNSEu), (where x = 0, 0.1, 0.5, 1.0, 1.5 and 2 mol%) were fabricated using the melt-quenching method. Obtain X-ray diffraction (XRD), energy-dispersive X-ray (EDAX), and Fourier transform infrared (FTIR) spectra were used to characterize the structure of the prepared PBNSEu glass. The J–O (Judd–Ofelt) intensity parameters (Ω₂, Ω₄) were estimated using photoluminescence emission spectra. When excited with a xenon lamp at λ_exc = 394 nm, the most intense red-emission transition occurred at ~612 nm (⁵D₀→⁷F₂). J–O intensity parameters were used to calculate radiative properties, whereas the radiative branching ratio (β_R), radiative transition probability (A_R), radiative lifetime (τ_R), and total radiative transition rate (A_τ) were calculated for the transitions ⁵D₀→⁷F_J (where J = 0–4) and were obtained in the emission spectra for europium ion-doped in the current glass. Using the CIE1931 chromaticity coordinates axes, the colours of various concentrations of Eu³⁺ ion-doped PBNS glass were evaluated using the emission spectra. Temperature-dependent luminescence spectra were recorded for the optimized PBNSEu20 glass to calculate the activation energy. These results strongly suggested red components in w-LEDs and visible display laser applications.