Mechanical and Gamma Ray Absorption Behavior of PbO-WO3-Na2O-MgO-B2O3 Glasses in the Low Energy Range

The Makishima and Mackenzie model has been used to determine the mechanical properties of the PbO-WO₃-Na₂O-MgO-B₂O₃ glass system. The number of bonds per unit volume of the glasses (n_b) increases from 9.40 × 10²² to 10.09 × 10²² cm⁻³ as the PbO content increases from 30 to 50 mol%. The Poisson’s ratio (σ) for the examined glasses falls between 0.174 and 0.210. The value of the fractal bond connectivity (d) for the present glasses ranges from 3.08 to 3.59. Gamma photon and fast neutron shielding parameters were evaluated via Phy-X/PSD, while that of electrons were calculated via the ESTAR platform. Analysis of the parameters showed that both photon and electron attenuation ability improve with the PbO content. The fast neutron removal cross section of the glasses varies from 0.094–0.102 cm⁻¹ as PbO molar content reduced from 50–30 mol%. Further analysis of shielding parameters of the investigated glass system showed that they possess good potential to function in radiation protection applications.     

Thermal Evolutions to Glass-Ceramics Bearing Calcium Tungstate Crystals in Borate Glasses Doped with Photoluminescent Eu3+ Ions

Thermal evolutions of calcium-tungstate-borate glasses were investigated for the development of luminescent glass-ceramics by using Eu³⁺ dopant in a borate glass matrix with calcium tungstate, which was expected to have a combined character of glass and ceramics. This study revealed that single-phase precipitation of CaWO₄ crystals in borate glass matrix was possible by heat-treatment at a temperature higher than glass transition temperature T_g for (100−x) (33CaO-67B₂O₃)−xCa₃WO₆ (x = 8−15 mol%). Additionally, the crystallization of CaWO₄ was found by Raman spectroscopy due to the formation of W=O double bondings of WO₄ tetrahedra in the pristine glass despite starting with the higher calcium content of Ca₃WO₆. Eu³⁺ ions were excluded from the CaWO₄ crystals and positioned in the borate glass phase as a stable site for them, which provided local environments in higher symmetry around Eu³⁺ ions.     

Investigation of Er3+ Ions Reinforced Zinc-Phosphate Glasses for Ionizing Radiation Shielding Applications

Melt quenching technique is used for preparing glasses with chemical formula (70P₂O₅)–(16 − x)CdO–(14ZnO)–(xEr₂O₃), (x = 1–6 mol%). These glasses were named Er1, Er2, Er3, Er4, Er5, and Er6, respectively. Photon buildup factors, fast neutron absorption, and electron stopping of the prepared glasses were examined. Glasses’ density was varied from 3.390 ± 0.003 for the Er1 glass sample to 3.412 ± 0.003 for the Er6 glass sample. The Buildup factor (BUF) spectra have relatively higher values in the Compton Scattering (CS) dominated areas compared to both Photoelectric effect (PE), and Pair Production (PP) dominated energy regions. The highest BUF appeared at the Er atom K-absorption edge, whose intensity increases as the molar concentration of Er₂O₃ in the glasses increases. The photon absorption efficiency (PAE) of the glasses increases according to the trend (PAE)_Er1 < (PAE)_Er2 < (PAE)_Er3 < (PAE)_Er4 < (PAE)_Er5 < (PAE)_Er6. Fast neutron removal cross-section, FNRC (ΣR) values of the glasses obtained via calculation varied from 0.1045–0.1039 cm⁻¹ for Er1–Er6. Furthermore, the continuous slowing down approximation mode (CSDA) range enhances the kinetic energy of electrons for all glasses. Generally, results revealed that the investigated glasses could be applied for radiation shielding and dosimetric media.     

Near-IR Luminescence of Rare-Earth Ions (Er3+, Pr3+, Ho3+, Tm3+) in Titanate–Germanate Glasses under Excitation of Yb3+

Inorganic glasses co-doped with rare-earth ions have a key potential application value in the field of optical communications. In this paper, we have fabricated and then characterized multicomponent TiO₂-modified germanate glasses co-doped with Yb³⁺/Ln³⁺ (Ln = Pr, Er, Tm, Ho) with excellent spectroscopic properties. Glass systems were directly excited at 980 nm (the ²F_7/2 → ²F_5/2 transition of Yb³⁺). We demonstrated that the introduction of TiO₂ is a promising option to significantly enhance the main near-infrared luminescence bands located at the optical telecommunication window at 1.3 μm (Pr³⁺: ¹G₄ → ³H₅), 1.5 μm (Er³⁺: ⁴I_13/2 → ⁴I_15/2), 1.8 μm (Tm³⁺: ³F₄ → ³H₆) and 2.0 μm (Ho³⁺: ⁵I₇ → ⁷I₈). Based on the lifetime values, the energy transfer efficiencies (η_ET) were estimated. The values of η_ET are changed from 31% for Yb³⁺/Ho³⁺ glass to nearly 53% for Yb³⁺/Pr³⁺ glass. The investigations show that obtained titanate–germanate glass is an interesting type of special glasses integrating luminescence properties and spectroscopic parameters, which may be a promising candidate for application in laser sources emitting radiation and broadband tunable amplifiers operating in the near-infrared range.     

γ-Actin is required for cytoskeletal maintenance but not development

β_cyto-Actin and γ_cyto-actin are ubiquitous proteins thought to be essential building blocks of the cytoskeleton in all non-muscle cells. Despite this widely held supposition, we show that γ_cyto-actin null mice (Actg1^−/−) are viable. However, they suffer increased mortality and show progressive hearing loss during adulthood despite compensatory up-regulation of β_cyto-actin. The surprising viability and normal hearing of young Actg1^−/− mice means that β_cyto-actin can likely build all essential non-muscle actin-based cytoskeletal structures including mechanosensory stereocilia of hair cells that are necessary for hearing. Although γ_cyto-actin–deficient stereocilia form normally, we found that they cannot maintain the integrity of the stereocilia actin core. In the wild-type, γ_cyto-actin localizes along the length of stereocilia but re-distributes to sites of F-actin core disruptions resulting from animal exposure to damaging noise. In Actg1^−/− stereocilia similar disruptions are observed even without noise exposure. We conclude that γ_cyto-actin is required for reinforcement and long-term stability of F-actin–based structures but is not an essential building block of the developing cytoskeleton.     

Enhancing Thermoelectric Properties of (Cu2Te)1−x-(BiCuTeO)x Composites by Optimizing Carrier Concentration

Because of the high carrier concentration, copper telluride (Cu₂Te) has a relatively low Seebeck coefficient and high thermal conductivity, which are not good for its thermoelectric performance. To simultaneously optimize carrier concentration, lower thermal conductivity and improve the stability, BiCuTeO, an oxygen containing compound with lower carrier concentration, is in situ formed in Cu₂Te by a method of combining self-propagating high-temperature synthesis (SHS) with spark plasma sintering (SPS). With the incorporation of BiCuTeO, the carrier concentration decreased from 8.1 × 10²⁰ to 3.8 × 10²⁰ cm⁻³, bringing the increase of power factor from ~1.91 to ~2.97 μW cm⁻¹ K⁻² at normal temperature. At the same time, thermal conductivity reduced from 2.61 to 1.48 W m⁻¹ K⁻¹ at 623 K. Consequently, (Cu₂Te)_0.95-(BiCuTeO)_0.05 composite sample reached a relatively high ZT value of 0.13 at 723 K, which is 41% higher than that of Cu₂Te.     

Influence of ZnF2 and WO3 on Radiation Attenuation Features of Oxyfluoride Tellurite WO3-ZnF2-TeO2 Glasses Using Phy-X/PSD Software

The radiation shielding features of the ternary oxyfluoride tellurite glasses were studied by calculating different shielding factors. The effect of the TeO₂, WO_3, and ZnF₂ on the tested glass system’s attenuating performance was predicted from the examination. The mass attenuation coefficient (µ/ρ) values for the oxyfluoride tellurite glasses depend highly on the concentration of WO_3, as well as ZnF₂. All the present ZnFWTe1-ZnFWTe5 samples have higher µ/ρ values than that of the pure TeO₂ glass at all energies. For the samples with a fixed content of WO₃, the replacement of TeO₂ by ZnF₂ increases the µ/ρ, while for the glasses with a fixed content of TeO₂, the replacement of WO₃ by ZnF₂ results in a decline in the µ/ρ values. The results revealed that ZnFWTe4 has the lowest linear attenuation coefficient (µ) among the oxyfluoride tellurite glasses, whereby it has a slightly higher value than pure TeO₂ glass. The maximum effective atomic number (Z_eff) is found at 0.284 MeV and varied between 31.75 and 34.30 for the tested glasses; it equaled to 30.29 for the pure TeO₂ glass. The half-value layer (HVL) of the glasses showed a gradual decline with increasing density. The pure TeO₂ was revealed to have thicker HVL than the selected oxyfluoride tellurite glasses. A 1.901-cm thickness of the sample, ZnFWTe1, is required to decrease the intensity of a photon with an energy of 0.284 MeV to one-tenth of its original, whereas 1.936, 1.956, 2.212, and 2.079 cm are required for glasses ZnFWTe2, ZnFWTe3, ZnFWTe4, and ZnFWTe5, respectively.     

Detailed Inspection of γ-ray,Fast and Thermal Neutrons Shielding Competence of Calcium Oxide or Strontium Oxide Comprising Bismuth Borate Glasses

For both the B₂O₃-Bi₂O₃-CaO and B₂O₃-Bi₂O₃-SrO glass systems, γ-ray and neutron attenuation qualities were evaluated. Utilizing the Phy-X/PSD program, within the 0.015–15 MeV energy range, linear attenuation coefficients (µ) and mass attenuation coefficients (μ/ρ) were calculated, and the attained μ/ρ quantities match well with respective simulation results computed by MCNPX, Geant4, and Penelope codes. Instead of B₂O₃/CaO or B₂O₃/SrO, the Bi₂O₃ addition causes improved γ-ray shielding competence, i.e., rise in effective atomic number (Z_eff) and a fall in half-value layer (HVL), tenth-value layer (TVL), and mean free path (MFP). Exposure buildup factors (EBFs) and energy absorption buildup factors (EABFs) were derived using a geometric progression (G–P) fitting approach at 1–40 mfp penetration depths (PDs), within the 0.015–15 MeV range. Computed radiation protection efficiency (RPE) values confirm their excellent capacity for lower energy photons shielding. Comparably greater density (7.59 g/cm³), larger μ, μ/ρ, Z_eff, equivalent atomic number (Z_eq), and RPE, with the lowest HVL, TVL, MFP, EBFs, and EABFs derived for 30B₂O₃-60Bi₂O₃-10SrO (mol%) glass suggest it as an excellent γ-ray attenuator. Additionally, 30B₂O₃-60Bi₂O₃-10SrO (mol%) glass holds a commensurably bigger macroscopic removal cross-section for fast neutrons (Σ_R) (=0.1199 cm⁻¹), obtained by applying Phy-X/PSD for fast neutrons shielding, owing to the presence of larger wt% of ‘Bi’ (80.6813 wt%) and moderate ‘B’ (2.0869 wt%) elements in it. 70B₂O₃-5Bi₂O₃-25CaO (mol%) sample (B: 17.5887 wt%, Bi: 24.2855 wt%, Ca: 11.6436 wt%, and O: 46.4821 wt%) shows high potentiality for thermal or slow neutrons and intermediate energy neutrons capture or absorption due to comprised high wt% of ‘B’ element in it.     

Effects of Vanadium on the Structural and Optical Properties of Borate Glasses Containing Er3+ and Silver Nanoparticles

The erbium-vanadium co-doped borate glasses, embedded with silver nanoparticles (Ag NPs), were prepared to improve their optical properties for potential optical fiber and glass laser application. The borate glasses with composition (59.5–x) B₂O₃–20Na₂O–20CaO–xV₂O₅–Er₂O₃–0.5AgCl (x = 0–2.5 mol%) were successfully prepared by conventional melt-quenching method. The structural properties of glass samples were investigated by XRD, TEM and by Fourier transform infrared (FTIR) spectroscopy while optical properties were carried out by UV–Vis spectroscopy by measuring optical absorption and the emission properties were investigated by photoluminescence spectroscopy. The XRD patterns confirmed the amorphous nature of the prepared glass samples whilst the FTIR confirmed the presence of VO₄, VO₅, BO₃ and BO₄ vibrations. UV–Vis–NIR absorption spectra reveal eight bands which were located at 450, 490, 519, 540, 660, 780, 980, and 1550 nm corresponding to transition of ⁴F_5/2, ⁴F_7/2, ²H_11/2, ⁴S_3/2, ⁴F_9/2, ⁴I_9/2, ⁴I_11/2, and ⁴I_13/2, respectively. The optical band gap (E_opt), Urbach energy and refractive index were observed to decrease, increase and increase, respectively, to the addition of vanadium. Under 800 nm excitation, three emission bands were observed at 516, 580 and 673 nm, which are represented by ²H_11/2–⁴I_15/2, ⁴S_3/2–⁴I_15/2 and ⁴F_15/2–⁴I_15/2, respectively. The excellent features of achieved results suggest that our findings may provide useful information toward the development of functional glasses.     

Interferon-gamma and interleukin-4 reciprocally regulate CD8 expression in CD8+ T cells

The CD8 co-receptor can modulate CD8⁺ T cell function through its contributions to T cell receptor (TCR) binding and signaling. Here we show that IFN-γ and IL-4 exert opposing effects on the expression of CD8α mRNA and surface CD8 protein during CD8⁺ T cell activation. IL-4 caused down-regulation of surface CD8 on ovalbumin (OVA)_257–264-specific TCR-transgenic OT-I CD8⁺ T cells activated with OVA_257–264-coated antigen presenting cells or polyclonal stimuli, and on wild type CD8⁺ T cells activated with polyclonal stimuli. This effect was enhanced in each case when the cells lacked a functional IFN-γ or IFN-γR gene. When WT or IFN-γ-deficient OT-I CD8⁺ T cells were analyzed 9 days after co-injection with control or IL-4-expressing OVA⁺ tumor cells into RAG-2^−/−γc^−/− mice, CD8 levels were highest on WT donor cells from mice that received the control tumor and lowest on IFN-γ-deficient donor cells from mice that received the IL-4-expressing tumor. The latter CD8^low cells displayed markedly impaired binding of OVA_257–264/MHC tetramers and peptide/MHC-dependent degranulation. The data reveal an unexpected role for IFN-γ in tuning the CD8 co-receptor during primary CD8⁺ T cell activation both in vitro and in vivo.     

Investigation of the TeO2/GeO2 Ratio on the Spectroscopic Properties of Eu3+-Doped Oxide Glasses for Optical Fiber Application

This study presented an analysis of the TeO₂/GeO₂ molar ratio in an oxide glass system. A family of melt-quenched glasses with the range of 0–35 mol% of GeO₂ has been characterized by using DSC, Raman, MIR, refractive index, PLE, PL spectra, and time-resolved spectral measurements. The increase in the content of germanium oxide caused an increase in the transition temperature but a decrease in the refractive index. The photoluminescence spectra of europium ions were examined under the excitation of 465 nm, corresponding to ⁷F₀ → ⁵D₂ transition. The PSB (phonon sidebands) analysis was carried out to determine the phonon energy of the glass hosts. It was reported that the red (⁵D₀ → ⁷F₂) to orange (⁵D₀ → ⁷F₁) fluorescence intensity ratio for Eu³⁺ ions decreased from 4.49 (Te0Ge) to 3.33 (Te15Ge) and showed a constant increase from 4.58 (Te20Ge) to 4.88 (Te35Ge). These optical features were explained in structural studies, especially changes in the coordination of ^[4]Ge to ^[6]Ge. The most extended lifetime was reported for the Eu³⁺ doped glass with the highest content of GeO₂. This glass was successfully used for the drawing of optical fiber.     

Dendritic Iron(III) Carbazole Complexes: Structural,Optical, and Magnetic Characteristics

This paper focuses on the synthesis, structural characterization, and study of the optical, magnetic, and thermal properties of novel architectures combining metal ions as magnetoactive centers and photoactive blocks formed by carbazole units. For this purpose, a series of azomethine complexes of the composition [Fe(L)₂]X (L = 3,6-bis[(3′,6′-di-tert-butyl-9-carbazol)-9-carbazol]benzoyloxy-4-salicylidene-N′-ethyl-N-ethylenediamine, X = NO₃⁻, Cl⁻, PF₆⁻) were synthesized by the reaction of metal salts with Schiff bases in a mixture of solvents. The UV–Vis absorption properties were studied in dichloromethane and rationalized via time-dependent density functional theory (DFT) calculations. Upon excitation at 350 nm, the compounds exhibited an intense dual fluorescence with two emission bands centered at ~445 and ~485 nm, which were assigned to π_carb–π* intraligand and π_carb–d_Fe ligand-to-metal charge-transfer excited states. EPR spectroscopy and SQUID magnetometry revealed solid-state partial spin crossover in some compounds, and antiferromagnetic interactions between the neighboring Fe(III) ions.     

Synbiotics Easing Renal Failure by Improving Gut Microbiology (SYNERGY): A Randomized Trial

Background and objectives

The generation of key uremic nephrovascular toxins, indoxyl sulfate (IS), and p-cresyl sulfate (PCS), is attributed to the dysbiotic gut microbiota in CKD. The aim of our study was to evaluate whether synbiotic (pre- and probiotic) therapy alters the gut microbiota and reduces serum concentrations of microbiome–generated uremic toxins, IS and PCS, in patients with CKD.

Design, setting, participants, & measurements

Predialysis adult participants with CKD (eGFR=10–30 ml/min per 1.73 m²) were recruited between January 5, 2013 and November 12, 2013 to a randomized, double–blind, placebo–controlled, crossover trial of synbiotic therapy over 6 weeks (4-week washout). The primary outcome was serum IS. Secondary outcomes included serum PCS, stool microbiota profile, eGFR, proteinuria-albuminuria, urinary kidney injury molecule-1, serum inflammatory biomarkers (IL-1β, IL-6, IL-10, and TNF-α), serum oxidative stress biomarkers (F₂-isoprostanes and glutathione peroxidase), serum LPS, patient-reported health, Gastrointestinal Symptom Score, and dietary intake. A prespecified subgroup analysis explored the effect of antibiotic use on treatment effect.

Results

Of 37 individuals randomized (age =69±10 years old; 57% men; eGFR=24±8 ml/min per 1.73 m²), 31 completed the study. Synbiotic therapy did not significantly reduce serum IS (−2 μmol/L; 95% confidence interval [95% CI], −5 to 1 μmol/L) but did significantly reduce serum PCS (−14 μmol/L; 95% CI, −27 to −2 μmol/L). Decreases in both PCS and IS concentrations were more pronounced in patients who did not receive antibiotics during the study (n=21; serum PCS, −25 μmol/L; 95% CI, −38 to −12 μmol/L; serum IS, −5 μmol/L; 95% CI, −8 to −1 μmol/L). Synbiotics also altered the stool microbiome, particularly with enrichment of Bifidobacterium and depletion of Ruminococcaceae. Except for an increase in albuminuria of 38 mg/24 h (P=0.03) in the synbiotic arm, no changes were observed in the other secondary outcomes.

Conclusion

In patients with CKD, synbiotics did not significantly reduce serum IS but did decrease serum PCS and favorably modified the stool microbiome. Large–scale clinical trials are justified.     

The Effect of ZnO,MgO, TiO2, and Na2O Modifiers on the Physical,Optical, and Radiation Shielding Properties of a TeTaNb Glass System

Novel glass samples with the composition 75TeO₂–5Ta₂O₅–15Nb₂O₅–5x (where x = ZnO, MgO, TiO₂, or Na₂O) in mole percent were prepared. The physical, optical, and gamma radiation shielding properties of the glass samples were studied over a wide energy spectrum ranging between 0.015 and 20 MeV. The glasses’ UV–vis spectra were utilized to evaluate the optical energy gap and refractive index. Glass samples had a refractive index ranging from 2.2005 to 2.0967. The results showed that the sample doped with zinc oxide (ZnO) recorded the highest density (ρ_glass), molar polarizability (α_m), molar refraction (Rm), refractive index (n), and third-order nonlinear optical susceptibility (χ³) and the lowest optical energy gap (E_opt) among the samples under investigation. When comparing the current glass system with various standard glass shielding materials, the prepared glass system showed superior shielding performance at energies ranging between 40 and 85 keV. These findings indicate that the prepared glass systems can be used in diagnostic X-rays, especially in dental applications.     

Spectroscopic identification and stability of the intermediate in the OH + HONO2 reaction

The reaction of nitric acid with the hydroxyl radical influences the residence time of HONO₂ in the lower atmosphere. Prior studies [Brown SS, Burkholder JB, Talukdar RK, Ravishankara AR (2001) J Phys Chem A 105:1605–1614] have revealed unusual kinetic behavior for this reaction, including a negative temperature dependence, a complex pressure dependence, and an overall reaction rate strongly affected by isotopic substitution. This behavior suggested that the reaction occurs through an intermediate, theoretically predicted to be a hydrogen-bonded OH–HONO₂ complex in a six-membered ring-like configuration. In this study, the intermediate is generated directly by the association of photolytically generated OH radicals with HONO₂ and stabilized in a pulsed supersonic expansion. Infrared action spectroscopy is used to identify the intermediate by the OH radical stretch (ν₁) and OH stretch of nitric acid (ν₂) in the OH–HONO₂ complex. Two vibrational features are attributed to OH–HONO₂: a rotationally structured ν₁ band at 3516.8 cm⁻¹ and an extensively broadened ν₂ feature at 3260 cm⁻¹, both shifted from their respective monomers. These same transitions are identified for OD–DONO₂. Assignments of the features are based on their vibrational frequencies, analysis of rotational band structure, and comparison with complementary high level ab initio calculations. In addition, the OH (v = 0) product state distributions resulting from ν₁ and ν₂ excitation are used to determine the binding energy of OH–HONO₂, D₀ ≤ 5.3 kcal·mol⁻¹, which is in good accord with ab initio predictions.     

Linking the Electrical Conductivity and Non-Stoichiometry of Thin Film Ce1−xZrxO2−δ by a Resonant Nanobalance Approach

Bulk ceria-zirconia solid solutions (Ce_1−xZr_xO_2−δ, CZO) are highly suited for application as oxygen storage materials in automotive three-way catalytic converters (TWC) due to the high levels of achievable oxygen non-stoichiometry δ. In thin film CZO, the oxygen storage properties are expected to be further enhanced. The present study addresses this aspect. CZO thin films with 0 ≤ x ≤ 1 were investigated. A unique nano-thermogravimetric method for thin films that is based on the resonant nanobalance approach for high-temperature characterization of oxygen non-stoichiometry in CZO was implemented. The high-temperature electrical conductivity and the non-stoichiometry δ of CZO were measured under oxygen partial pressures pO₂ in the range of 10⁻²⁴–0.2 bar. Markedly enhanced reducibility and electronic conductivity of CeO₂-ZrO₂ as compared to CeO_2−δ and ZrO₂ were observed. A comparison of temperature- and pO₂-dependences of the non-stoichiometry of thin films with literature data for bulk Ce_1−xZr_xO_2−δ shows enhanced reducibility in the former. The maximum conductivity was found for Ce_0.8Zr_0.2O_2−δ, whereas Ce_0.5Zr_0.5O_2-δ showed the highest non-stoichiometry, yielding δ = 0.16 at 900 °C and pO₂ of 10⁻¹⁴ bar. The defect interactions in Ce_1−xZr_xO_2−δ are analyzed in the framework of defect models for ceria and zirconia.     

Optical Spectra Tuning of All-Glass Photonic Bandgap Fiber Infiltrated with Silver Fast-Ion-Conducting Glasses

Silver iodide metaphosphate glasses of the xAgI + (1−x)AgPO₃ family are embedded inside the air capillaries of a commercial silica photonic crystal fiber (PCF) by means of vacuum-assisted infiltration technique. In this paper, we report on tuning the photonic bandgap (PBG) guidance characteristics of the fabricated all-glass photonic bandgap fibers, by varying the composition of the fast-ion-conducting phosphate glass infiltration medium. Doping AgPO₃ metaphosphate glass with AgI significantly alters the PBG guidance patterns in the examined range between 350 and 1750 nm, as it leads to the introduction of numerous additional transmission stop-bands, while affecting scattering dependant losses. The effect of phosphate glass cooling method during sample fabrication on the transmission behavior of the xAgI + (1−x)AgPO₃/PCFs is also considered.     

Influence of Bi2O3 on Mechanical Properties and Radiation-Shielding Performance of Lithium Zinc Bismuth Silicate Glass System Using Phys-X Software

We analyzed the mechanical properties and radiation-shielding performance of a lithium zinc bismuth silicate glass system. The composition of these glasses is 20ZnO-30Li₂O-(50-x)SiO₂-xBi₂O₃ (x varies between 10 and 40 mol%). The mechanical properties of the investigated glass system, such as Young’s modulus (E), bulk modulus (K), shear modulus (S), and longitudinal modulus (L), were determined using the Makishima–Mackenzie model. The elastic moduli gradually decreased with the addition of Bi₂O₃. E decreased from 46 to 31 GPa, K decreased from 27 to 14 GPa, S decreased from 19 to 14 GPa, and L decreased from 52 to 32 GPa as Bi₂O₃ was substituted for SiO₂. The mass attenuation coefficient (MAC) was investigated at energies between 0.284 and 1.33 MeV to understand the radiation-shielding performance of the glasses. The MAC value increased when SiO₂ was replaced by Bi₂O₃. We found that the effect of Bi₂O₃ on MAC values was noticeably stronger at energies of 0.284 and 0.347 MeV, while the effect of Bi₂O₃ on MAC values became weaker as energy increased. The linear attenuation coefficient (LAC) results demonstrated that if the samples were exposed to low-energy photons, the glass could prevent the penetration of photons, and thus, the glass samples were effective in radiation protection. The LAC values for the lowest- and highest-density samples changed from 0.998 to 1.976 cm⁻¹ (at 0.284 MeV) and from 0.286 to 0.424 cm⁻¹ (at 0.826 MeV). According to the radiation-shielding results, the thick, high-density glass sample has special and distinctive shielding properties.     

Phosphatidylinositol 4,5-bisphosphate (PIP2) stimulates the electrogenic Na/HCO3 cotransporter NBCe1-A expressed in Xenopus oocytes

Bicarbonate transporters are regulated by signaling molecules/ions such as protein kinases, ATP, and Ca²⁺. While phospholipids such as PIP₂ can stimulate Na-H exchanger activity, little is known about phospholipid regulation of bicarbonate transporters. We used the patch-clamp technique to study the function and regulation of heterologously expressed rat NBCe1-A in excised macropatches from Xenopus laevis oocytes. Exposing the cytosolic side of inside-out macropatches to a 5% CO₂/33 mM HCO₃⁻ solution elicited a mean inward current of 14 pA in 74% of macropatches attached to pipettes (−V_p = −60 mV) containing a low-Na⁺, nominally HCO₃⁻-free solution. The current was 80–90% smaller in the absence of Na⁺, approximately 75% smaller in the presence of 200 μM DIDS, and absent in macropatches from H₂O-injected oocytes. NBCe1-A currents exhibited time-dependent rundown that was inhibited by removing Mg²⁺ in the presence or absence of vanadate and F⁻ to reduce general phosphatase activity. Applying 5 or 10 μM PIP₂ (diC8) in the presence of HCO₃⁻ induced an inward current in 54% of macropatches from NBC-expressing, but not H₂O-injected oocytes. PIP₂-induced currents were HCO₃⁻-dependent and somewhat larger following more NBCe1-A rundown, 62% smaller in the absence of Na⁺, and 90% smaller in the presence of 200 μM DIDS. The polycation neomycin (250–500 μM) reduced the PIP₂-induced inward current by 69%; spermine (100 μM) reduced the current by 97%. Spermine, poly-D-lysine, and neomycin all reduced the baseline HCO₃⁻-induced inward currents by as much as 85%. In summary, PIP₂ stimulates NBCe1-A activity, and phosphoinositides are regulators of bicarbonate transporters.     

Triple Perovskite Nd1.5Ba1.5CoFeMnO9−δ-Sm0.2Ce0.8O1.9 Composite as Cathodes for the Intermediate Temperature Solid Oxide Fuel Cells

Triple perovskite has been recently developed for the intermediate temperature solid oxide fuel cell (IT-SOFC). The performance of Nd_1.5Ba_1.5CoFeMnO_9−δ (NBCFM) cathodes for IT-SOFC is investigated in this work. The interfacial polarization resistance (R_P) of NBCFM is 1.1273 Ω cm²~0.1587 Ω cm² in the range of 700–800 °C, showing good electrochemical performance. The linear thermal expansion coefficient of NBCFM is 17.40 × 10⁻⁶ K⁻¹ at 40–800 °C, which is significantly higher than that of the electrolyte. In order to further improve the electrochemical performance and reduce the thermal expansion coefficient (TEC) of NBCFM, Ce_0.8Sm_0.2O_2−δ (SDC) is mixed with NBCFM to prepare an NBCFM-xSDC composite cathode (x = 0, 10, 20, 30, 40 wt.%). The thermal expansion coefficient decreases monotonically from 17.40 × 10⁻⁶ K⁻¹ to 15.25 × 10⁻⁶ K⁻¹. The surface oxygen exchange coefficient of NBCFM-xSDC at a given temperature increases from 10⁻⁴ to 10⁻³ cm s⁻¹ over the po2 range from 0.01 to 0.09 atm, exhibiting fast surface exchange kinetics. The area specific resistance (ASR) of NBCFM-30%SDC is 0.06575 Ω cm² at 800 °C, which is only 41% of the ASR value of NBCFM (0.15872 Ω cm²). The outstanding performance indicates the feasibility of NBCFM-30% SDC as an IT-SOFC cathode material. This study provides a promising strategy for designing high-performance composite cathodes for SOFCs based on triple perovskite structures.