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.     

Investigations Regarding the Addition of ZnO and Li2O-TiO2 to Phosphate-Tellurite Glasses: Structural,Chemical, and Mechanical Properties

Phosphate and tellurite glasses can be used in optics, optoelectronics, magneto-optics, and nuclear and medical fields. Two series of phosphate-tellurite glasses, (50-x)ZnO-10Al₂O₃-40P₂O₅-xTeO₂ and (40-x)Li₂O-10Al₂O₃-5TiO₂-45P₂O₅-xTeO₂ (x = 5, 10), were synthesized by a non-conventional wet-route, and the mechanical properties as key performance measures for their application in optoelectronics were investigated. X-ray Diffraction (XRD) measurements revealed the vitreous nature of the investigated materials. Instrumented indentation tests allowed the calculation of hardness (H) and Young’s modulus (E) using the Oliver and Pharr model. The influence of increasing the TeO₂ content, as well as the substitution of ZnO by Li₂O-TiO₂, on the variation of hardness, Young’s modulus, penetration depth (PD), and fracture toughness (FT) was evaluated in both series. As a general trend, there is a decrease in the hardness and Young’s modulus with increasing penetration depth. The addition of Li₂O and TiO₂ instead of ZnO leads to improved hardness and elastic modulus values. Regarding the H/E ratio, it was found that the samples with lower TeO₂ content should be significantly more crack-resistant compared to the higher TeO₂ content samples. The H³/E² ratio, being lower than 0.01, revealed a poor resistance of these glasses to plastic deformation. At the same time, a decrease of the fracture toughness with increasing TeO₂ content was noticed for each glass series. Based on dilatometry measurements, the thermal expansion coefficient as well as the characteristic temperatures of the glasses were measured. Field Emission Scanning Electron Microscopy-Energy Dispersive X-ray analysis (FESEM-EDX) revealed a uniform distribution of the elements in the bulk samples. The mechanical properties of these vitreous materials are important in relation to their application as magneto-optical Faraday rotators in laser cavities.     

Preparation,Characterization of Granulated Sulfur Fertilizers and Their Effects on a Sandy Soils

There is a potential for using sulfur waste in agriculture. The main objective of this study was to design a granular fertilizer based on waste elemental sulfur. Humic acids and halloysite were used to improve the properties and their influence on soil properties. This is the first report on the use of proposed materials for fertilizer production. The following granular fertilizers were prepared (the percentage share of component weight is given in brackets): fertilizer A (waste sulfur (95%) + halloysite (5%)), fertilizer B (waste sulfur (81%) + halloysite (5%) + humic acids (14%)), fertilizer C (waste sulfur (50%) + halloysite (50%)) and fertilizer D (waste sulfur (46%) + halloysite (46%) + humic acids (8%)). Basic properties of the obtained granulates were determined. Furthermore, the effect of the addition of the prepared fertilizers on soil pH, electrolytic conductivity, and sulfate content was examined in a 90-day incubation experiment. Enrichment with humic acids and the higher amount of halloysite increased the fertilizer properties (especially the share of larger granules and bulk density). In addition, it stabilized soil pH and increased the sulfur content (extracted with 0.01 mol·L⁻¹ CaCl₂ and Mehlich 3) in the soil.     

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.     

Thermodynamic Origin of the Vitreous Transition

The vitreous transition is characterized by a freezing of atomic degrees of freedom at a temperature T_g depending on the heating and cooling rates. A kinetic origin is generally attributed to this phenomenon instead of a thermodynamic one which we develop here. Completed homogeneous nucleation laws reflecting the energy saving due to Fermi energy equalization of nascent crystals and their melt are used. They are applied to bulk metallic glasses and extended to inorganic glasses and polymers. A transition T*_g among various T_g corresponds to a crystal homogeneous nucleation temperature, leading to a preliminary formation of a cluster distribution during the relaxation time preceding the long steady-state nucleation time of crystals in small samples. The thermally-activated energy barrier ΔG*_2ls/k_BT at T*_g for homogeneous nucleation is nearly the same in all glass-forming melts and determined by similar values of viscosity and a thermally-activated diffusion barrier from melt to cluster. The glass transition T*_g is a material constant and a linear function of the energy saving associated with charge transfers from nascent clusters to the melt. The vitreous transition and the melting temperatures alone are used to predict the free-volume disappearance temperature equal to the Vogel-Fulcher-Tammann temperature of fragile glass-forming melts, in agreement with many viscosity measurements. The reversible thermodynamic vitreous transition is determined by the disappearance temperature T*_g of the fully-relaxed enthalpy H_r that is not time dependent; the observed specific heat jump at T*_g is equal to the proportionality coefficient of H_r with (T*_g − T_a) for T ≤ T*_g as expected from the enthalpy excess stored by a quenched undercooled melt at the annealing temperature T_a and relaxed towards an equilibrium vitreous state. However, the heat flux measurements found in literature over the last 50 years only gave an out-of-equilibrium T_g since the enthalpy is continuous at T*_g without visible heat jump.     

Spectroscopic Properties of Inorganic Glasses Doped with Pr3+: A Comparative Study

The results presented in this communication concern visible and near-IR emission of Pr³⁺ ions in selected inorganic glasses, i.e., borate-based glass with Ga₂O₃ and BaO, lead-phosphate glass with Ga₂O₃, gallo-germanate glass modified by BaO/BaF₂, and multicomponent fluoride glass based on InF₃. Glasses present several emission bands at blue, reddish orange, and near-infrared spectral ranges, which correspond to 4f–4f electronic transitions of Pr³⁺. The profiles of emission bands and their relative intensity ratios depend strongly on glass-host. Visible emission of Pr³⁺ ions is tuned from red/orange for borate-based glass to nearly white light for multicomponent fluoride glass based on InF₃. The positions and spectral linewidths for near-infrared luminescence bands at the optical telecommunication window corresponding to the ¹G₄ → ³H₅, ¹D₂ → ¹G₄, and ³H₄ → ³F₃,³F₄ transitions of Pr³⁺ are dependent on glass-host matrices and excitation wavelengths. Low-phonon fluoride glasses based on InF₃ and gallo-germanate glasses with BaO/BaF₂ are excellent candidates for broadband near-infrared optical amplifiers. Spectroscopic properties of Pr³⁺-doped glasses are compared and discussed in relation to potential optical applications.     

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.     

Universal non-Landau,self-organized,lattice disordering percolative dopant network sub-Tc phase transition in ceramic superconductors

Ceramic superconductors (cuprates, pnictides, etc.) exhibit universal features in both T_c^max and in their planar lattice disordering measured by EXAFS, as reflected by three phase transitions. The two highest temperature transitions are known to be associated with formation of Jahn–Teller pseudogaps and superconductive gaps, with corresponding Landau order parameters, but no new gap is associated with the third transition below T_c, and its origin is mysterious. It is argued that the third subT_c transition is a dopant glass transition, which is remarkably similar to topological transitions previously observed in chalcogenide and oxide alloy network glasses (like window glass).     

Long-term fate of nitrate fertilizer in agricultural soils

Increasing diffuse nitrate loading of surface waters and groundwater has emerged as a major problem in many agricultural areas of the world, resulting in contamination of drinking water resources in aquifers as well as eutrophication of freshwaters and coastal marine ecosystems. Although empirical correlations between application rates of N fertilizers to agricultural soils and nitrate contamination of adjacent hydrological systems have been demonstrated, the transit times of fertilizer N in the pedosphere–hydrosphere system are poorly understood. We investigated the fate of isotopically labeled nitrogen fertilizers in a three–decade-long in situ tracer experiment that quantified not only fertilizer N uptake by plants and retention in soils, but also determined to which extent and over which time periods fertilizer N stored in soil organic matter is rereleased for either uptake in crops or export into the hydrosphere. We found that 61–65% of the applied fertilizers N were taken up by plants, whereas 12–15% of the labeled fertilizer N were still residing in the soil organic matter more than a quarter century after tracer application. Between 8–12% of the applied fertilizer had leaked toward the hydrosphere during the 30-y observation period. We predict that additional exports of ¹⁵N-labeled nitrate from the tracer application in 1982 toward the hydrosphere will continue for at least another five decades. Therefore, attempts to reduce agricultural nitrate contamination of aquatic systems must consider the long-term legacy of past applications of synthetic fertilizers in agricultural systems and the nitrogen retention capacity of agricultural soils.Increasing anthropogenic nitrogen inputs have recently been identified as one of the two major issues potentially compromising a safe operating space for humanity (1). In many regions, the amount of human-activated reactive nitrogen, primarily via application of synthetic fertilizers and cultivation of leguminous crops, exceeds now the amount of natural nitrogen as a result of population growth and the associated need for food production (2, 3). These anthropogenic nitrogen inputs have significantly impacted the nitrogen cycle in terrestrial and aquatic ecosystems (4, 5).Increasing diffuse nitrate loading of surface waters and groundwaters has emerged as a major problem in many agricultural areas of the world resulting in contamination of drinking water resources abstracted from aquifers and eutrophication of freshwaters (6–8) and coastal marine ecosystems (9) despite the implementation of several diffuse pollution control directives (10, 11) and best management practices (12). Empirical correlations relating increased use of synthetic fertilizers, their application rates, land use change, and nitrate leaching suggest that the increased application of synthetic fertilizers is strongly connected with the increase of nitrate concentrations in groundwater and surface waters (13, 14), but quantitative data on transfer rates of fertilizer N into the hydrosphere are elusive. There is also considerable uncertainty regarding the transit time of anthropogenic nitrogen applied to agricultural soils between the topsoil and groundwater due to a poor mechanistic understanding of the timelines governing nitrogen cycling and nitrate transfer through soils (3, 15–17).Previous studies on the fate of synthetic fertilizers and other nitrogen amendments in agricultural soils have been carried out at various long-term agricultural research sites (18–26). In several cases, fertilizer compounds artificially enriched in ¹⁵N have been used to successfully follow the uptake of fertilizer N by crops and retention of fertilizer N in soil organic matter. These tracer studies with labeled ¹⁵N compounds demonstrated that 40–60% of the fertilizer N is rapidly taken up by crops and is removed via harvest, whereas the remainder of the fertilizer N is incorporated into the soil organic matter pool and soil microbial biomass. From this fertilizer-derived soil N pool, nitrate may be formed and leached out of the soil zone especially outside of the growing season (27–29). To our best knowledge, no in situ studies have investigated the long-term fate of this fertilizer-derived N in soil organic matter and quantified to which extent and over which time periods fertilizer N stored in soil organic matter is rereleased for either uptake in crops or is exported toward the hydrosphere.We investigated the long-term fate of isotopically (¹⁵N) labeled fertilizer nitrate in the plant–soil–water system of two intact lysimeters under rotating sugar beet and winter wheat cultivation at a site in France over a period of three decades (1982–2012). The objectives were i) to determine the extent to which fertilizer nitrate was taken up by crops, ii) to assess the mean residence time of fertilizer nitrogen in soil organic matter, and iii) to measure the rates at which fertilizer-derived nitrogen was exported as nitrate to the hydrosphere in the three decades after application of isotopically labeled fertilizer. The goal was to establish a complete 30-y mass balance of the fate of fertilizer N in an agricultural system and to quantify to which extent and over which time periods fertilizer N stored in soil organic matter is rereleased for either uptake in crops or export toward the hydrosphere.Details about the experimental design are provided in the SI Methods. Two large (2 × 2 × 2 m) soil monoliths containing agricultural topsoils underlain by mineral soil were converted into lysimeters. For both lysimeters, the annual crop rotation was sugar beet–winter wheat with annual N fertilization rates of 120 kg N·ha⁻¹·y⁻¹ except in 1982. In the year of the tracer application (1982), Lys S was cropped with sugar beet whereas winter wheat was grown on Lys W. In 1982, both crops received a one-time ¹⁵N-labeled tracer application (635.3 mg ¹⁵N·m⁻² on March 11 for wheat, 633.8 mg ¹⁵N·m⁻² on April 7 for sugar beet) equivalent to a typical fertilizer application rate of 120 and 150 kg N·ha⁻¹·y⁻¹ for wheat and sugar beet, respectively. Nitrogen exports occurred annually by harvesting of wheat and sugar beets and via seepage water outflow in 2-m depth. Soils, harvest products, and seepage waters were sampled repeatedly, and chemical and isotopic analyses were conducted. Mass and isotope balances were conducted to assess the fate of the fertilizer applied in 1982 in the agricultural soils and its export via harvest products and toward the underlying aquifers (see SI Methods for further details).     

Development of a New Sr-O Parameterization to Describe the Influence of SrO on Iron-Phosphate Glass Structural Properties Using Molecular Dynamics Simulations

Iron-phosphate glasses, due to their properties, have many potential applications. One of the most promising seems to be nuclear waste immobilization. Radioactive ⁹⁰Sr isotope is the main short-lived product of fission and, due to its high solubility, it can enter groundwater and pose a threat to the environment. On the other hand, Sr is an important element in hard tissue metabolic processes, and phosphate glasses containing Sr are considered bioactive. This study investigated the effect of SrO addition on a glass structure of nominal 30Fe₂O₃-70P₂O₅ chemical composition using classical molecular dynamics simulations. To describe the interaction between Sr-O ion pairs, new interatomic potential parameters of the Buckingham-type were developed and tested for crystalline compounds. The short-range structure of the simulated glasses is presented and is in agreement with previous experimental and theoretical studies. The simulations showed that an increase in SrO content in the glass led to phosphate network depolymerization. Analysis demonstrated that the non-network oxygen did not take part in the phosphate network depolymerization. Furthermore, strontium aggregation in the glass structure was observed to lead to the non-homogeneity of the glass network. It was demonstrated that Sr ions prefer to locate near to Fe(II), which may induce crystallization of strontium phosphates with divalent iron.     

Effects of cromakalim or pinacidil on pacing- and ischemia-induced ventricular fibrillation in the anesthetized pig

Summary The effects of the potassium channel openers (KCO), cromakalim or pinacidil, were evaluated in an anesthetized porcine model of pacing- and ischemia-induced ventricular fibrillation (VF). Hearts were paced at 180 bpm and the left anterior descending coronary artery was occluded until VF was induced.Reproducible times to VF (in seconds) were obtained allowing at least 20 min recovery following defibrillation. Cromakalim (0.3 mg/kg) or pinacidil (3 mg/kg) produced equivalent drops in mean arterial blood pressure. At these doses, cromakalim reduced monophasic action potential duration measured at 90% repolarization (APD₉₀). Although time to VF in the cromakalim group was significantly greater than the vehicle treated group, it was not significantly different from its predrug value. In contrast, pinacidil reduced APD₉₀, and significantly increased time to VF from 134±5 to 322±62 s (p<0.05). Neither cromakalim nor pinacidil affected whole-cell calcium currents recorded in guinea pig myocytes. During ischemia, cromakalim or pinacidil further reduced APD₉₀; however, pinacidil had a two-fold greater effect than did cromakalim. The Class III antiarrhythmic agent, dofetilide, prolonged APD₉₀, but did not increase time to VF.In conclusion, the increased time to VF observed with pinacidil coincides with its ability to shorten APD, and is consistent with activation of ATP-sensitive K⁺ channels (K⁺ _ATP). It is suggested that indirect reduction of calcium influx through K⁺ _ATP activation and APD shortening is sufficient to increase time to VF in this model. However, the inability of dofetilide to be effective suggests that this model would not be useful to test for Class III antiarrhythmic agents.     

Thiazolidinedione Drugs Promote Onset, Alter Characteristics, and Increase Mortality of Ischemic Ventricular Fibrillation in Pigs

Purpose

Despite favorable metabolic and vascular effects, thiazolidinedione (TZD) drugs have not convincingly reduced cardiovascular mortality in clinical trials, raising the possibility of countervailing, off-target effects. We previously showed that TZDs block cardiac ATP-sensitive potassium (K_ATP) channels in pigs. In this study, we investigated whether TZDs affect onset, spectral characteristics, and mortality of ischemic ventricular fibrillation (VF) and whether such effects are recapitulated by a non-selective K_ATP blocker (glyburide) or a mitochondrial K_ATP blocker (5-hydroxydecanoate).

Methods

A total of 121 anesthetized pigs were pre-treated with TZD (pioglitazone or rosiglitazone, 1?mg/kg IV, resulting in clinically relevant plasma concentrations), glyburide (1?mg/kg IV), 5-hydroxydecanoate (5?mg/kg IV) or inert vehicle. Ischemia was produced by occlusion of the left anterior descending coronary artery. In a subset of pigs treated with rosiglitazone or vehicle, ischemic preconditioning was performed.

Results

VF developed in all but 6 pigs. In non-preconditioned pigs, onset of VF occurred sooner with pioglitazone (11?±?3?min, p?p?=?0.06) than with vehicle (20?±?2?min). Defibrillation of VF was successful in 44?% of pigs treated with vehicle, compared with 0?% with pioglitazone (p?=?0.057) and 33?% with rosiglitazone (NS). After ischemic preconditioning, defibrillation was successful in 62?% of pigs treated with vehicle, compared with 26% treated with rosiglitazone (p?=?0.03). TZDs attenuated slowing of conduction due to ischemia and shifted ECG power spectra during VF toward higher frequencies. All effects of TZDs were recapitulated by glyburide, but not by 5-hydroxydecanoate, supporting an interaction of TZDs with the sarcolemmal K_ATP channel.

Conclusion

In a porcine model, TZDs promote onset and increase mortality of ischemic VF, associated with alterations of conduction and VF spectral characteristics. Similar effects in a clinical setting might adversely impact cardiovascular mortality.     

Enhancement of Gamma-ray Shielding Properties in Cobalt-Doped Heavy Metal Borate Glasses: The Role of Lanthanum Oxide Reinforcement

The direct influence of La³⁺ ions on the gamma-ray shielding properties of cobalt-doped heavy metal borate glasses with the chemical formula 0.3CoO-(80-x)B₂O₃-19.7PbO-xLa₂O₃: x = 0, 0.5, 1, 1.5, and 2 mol% was examined herein. Several significant radiation shielding parameters were evaluated. The glass density was increased from 3.11 to 3.36 g/cm³ with increasing La³⁺ ion content from 0 to 2 mol%. The S5 glass sample, which contained the highest concentration of La³⁺ ions (2 mol%), had the maximum linear (μ) and mass (μ_m) attenuation coefficients for all photon energies entering, while the S1 glass sample free of La³⁺ ions possessed the minimum values of μ and μ_m. Both the half value layer (T_1/2) and tenth value layer (TVL) of all investigated glasses showed a similar trend of (T_1/2, TVL)_S1 > (T_1/2, TVL)_S2 > (T_1/2, TVL)_S3 > (T_1/2, TVL)_S4 > (T_1/2, TVL)_S5. Our results revealed that the S5 sample had the highest effective atomic number (Z_eff) values over the whole range of gamma-ray energy. S5 had the lowest exposure (EBF) and energy absorption (EABF) build-up factor values across the whole photon energy and penetration depth range. Our findings give a strong indication of the S5 sample’s superior gamma-ray shielding characteristics due to the highest contribution of lanthanum oxide.     

Effects of Esophageal Varice Eradication on Portal Hypertensive Gastropathy and Fundal Varices: A Retrospective and Comparative Study

Esophageal varice eradication results in gastric hemodynamic changes. The aim of this study was to detect the influence of variceal eradication on portal hypertensive gastropathy (PHG) and fundal varices and to compare the results of two therapeutic methods (endoscopic variceal ligation and endoscopic sclerotherapy). A total of 114 consecutive patients with cirrhosis and portal hypertension who underwent elective endoscopic variceal ligation (EVL) (85 patients) or endoscopic sclerotherapy (EST) (29 patients) for obliteration of esophageal varices were selected for this study. Both groups were compared for PHG and fundal varice formation before and after eradication. Fifty-eight (68.2%) patients in the EVL and 18 (62.1%) patients in the EST group had PHG before esophageal varice eradication (P > 0.05). PHG grade after eradication of esophageal varices by both EVL and EST was significantly higher compared to pre-eradication. PHG grade and aggregation were similar in both groups. Thirty-seven patients (34 F₁, 3 F₂) in the EVL group and 13 patients (10 F₁, 3 F₂) in the EST group had fundal varices before variceal eradication (P > 0.05). Fundal varices were detected in 46 (35 F₁, 11F₂) and 19 (11F₁, 8F₂) patients in the EVL and EST groups after eradication, respectively. There was a statistically significant increment in occurrence of fundal varices after eradication with EVL and EST groups. There was no significant difference regarding fundal varice development after esophageal variceal eradication in both groups. After varical eradication, PHG was found in 57 (87.7%) and 39 (79.6%) patients with and without fundal varices, respectively (P > 0.05). Esophageal eradication with EVL and EST increases both the incidence and the severity of PHG and fundal varice formation. Both methods have comparable influences on PHG and fundal varices.     

Effect of Yb3+ on the Structural and Visible to Near-Infrared Wavelength Photoluminescence Properties in Sm3+-Yb3+-Codoped Barium Fluorotellurite Glasses

We report on the Sm³⁺ and Sm³⁺:Yb³⁺-doped barium fluorotellurite glasses prepared using the conventional melting and quenching method. The spectroscopic characterisations were investigated with Raman and FTIR to evaluate the glasses’ structural and hydroxyl (-OH) content. The Raman analysis revealed a structural modification in the glass network upon adding and increasing the Yb³⁺ concentration from a TeO₃ trigonal pyramid to a TeO₄ trigonal bi-pyramid polyhedral. At the same time, the FTIR measurements showed the existence of -OH groups in the glass. Thus, under the current experimental conditions and nominal composition, the -OH group contents are too large to enable an effective removal. The near-infrared region of the absorption spectra is employed to determine the nephelauxetic ratio and bonding parameters. The average nephelauxetic ratio decreases, and the bonding parameter increases with the increasing Yb³⁺ content in the glasses. A room temperature visible and near-infrared photoluminescence ranging from 500 to 1500 nm in wavelength and decay properties were investigated for glasses doped with Sm³⁺ and Sm³⁺-Yb³⁺ by exciting them with 450 and 980 nm laser sources. Exciting the Sm³⁺- and Sm³⁺-Yb³⁺-doped glasses by 450 nm excitation reveals a new series of photoluminescence emissions at 1200, 1293, and 1418 nm, corresponding to the ⁶F_11/2 state to the ⁶H_J (J = 7/2, 9/2, 11/2) transitions. Under the 976 nm laser excitation, a broad photoluminescence emission from 980 to 1200 nm was detected. A decay lifetime decreased from ~244 to ~43 μs by increasing the Yb³⁺ content, ascribing to concentration quenching and the OH content.     

Potential phytotoxicity associated with the use of soil urease inhibitors

Recent work in our laboratory showed that the adverse effect of urea fertilizer on seed germination and seedling growth in soil is due to ammonia produced through hydrolysis of urea by soil urease (NH₂CONH₂ + H₂O → 2NH₃ + CO₂) and can be eliminated by amending the fertilizer with a small amount of a urease inhibitor such as N-(n-butyl)thiophosphoric triamide or phenylphosphorodiamidate. Continuation of this work showed that these inhibitors can induce leaf-tip necrosis in plants. Research to account for this phytotoxicity indicated that it resulted from an accumulation of toxic amounts of urea in plants through inhibition of urease activity by N-(n-butyl)thiophosphoric triamide and phenylphosphorodiamidate. Support for this conclusion was provided by experiments showing that these urease inhibitors increased both leaf-tip necrosis and urea concentrations in wheat (Triticum aestivum L.) and sorghum [Sorghum bicolor(L.) Moench] plants grown in soils treated with urea and that the necrotic areas of such plants had a much higher concentration of urea than did the nonnecrotic areas. The potential of urease inhibitors for inducing phytotoxicity should not preclude their use to eliminate the adverse effects of urea fertilizers on seed germination and seedling growth in soil because the ammonia produced through hydrolysis of urea fertilizer by urease is much more detrimental to plant growth than is the urea accumulation induced by urease inhibitors.     

Intracellular Calcium Dynamics,Shortened Action Potential Duration,and Late‐Phase 3 Early Afterdepolarization in Langendorff‐Perfused Rabbit Ventricles

Calcium Dynamics, APD Shortening, and Late‐Phase 3 EAD. Introduction: To elucidate the mechanism of late‐phase 3 early after depolarization (EAD) in ventricular arrhythmogenesis, we hypothesized that intracellular calcium (Ca_i) overloading and action potential duration (APD) shortening may promote late‐phase 3 EAD and triggered activity, leading to development of ventricular fibrillation (VF). Methods and Results: In isolated rabbit hearts, we performed microelectrode recording and simultaneous dual optical mapping of transmembrane potential (V_m) and Ca_i transient on left ventricular endocardium. An I_KATP channel opener, pinacidil, was used to abbreviate APD. Rapid pacing was then performed. Upon abrupt cessation of rapid pacing with cycle lengths of 60–200 milliseconds, there were APD₉₀ prolongation and the corresponding Ca_i overloading in the first postpacing beats. The duration of Ca_i transient recovered to 50% (DCaT₅₀) and 90% (DCaT₉₀) in the first postpacing beats was significantly longer than baseline. Abnormal Ca_i elevation coupled with shortened APD produced late‐phase 3 EAD induced triggered activity and VF. In additional 6 preparations, the heart tissues were treated with BAPTA‐AM, a calcium chelator. BAPTA‐AM significantly reduced the maximal Ca_i amplitude (26.4 ± 3.5% of the control; P < 0.001) and the duration of Ca_i transients in the mapped region, preventing the development of EAD and triggered activity that initiated VF. Conclusions: I _KATP channel activation along with Ca_i overloading are associated with the development of late‐phase 3 EAD and VF. Because acute myocardial ischemia activates the I_KATP channel, late‐phase 3 EADs may be a mechanism for VF initiation during acute myocardial ischemia. (J Cardiovasc Electrophysiol, Vol. 23, pp. 1364‐1371, December 2012)     

Influence of Y2O3 Content on Structural,Optical, Spectroscopic,and Laser Properties of Er3+, Yb3+ Co-Doped Phosphate Glasses

The influence of the addition of Y₂O₃ on the structural, spectroscopic, and laser properties of newly prepared Er, Yb-doped strontium-sodium phosphate glass was investigated. While the addition of Y₂O₃ has a small influence on the absorption spectra and fluorescence lifetime, it has a strong impact on the emission cross-section and on OH⁻ content. The glasses were used as the active medium for diode-pumped laser emitting at 1556 nm. The increase in Y₂O₃ content leads to a significant 35% increase in laser slope efficiency up to 10.4%, but at the expense of the substantial reduction of the wavelength tunability from 82 to 54 nm.     

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.     

Sustainable and Clean Utilization of Yellow Phosphorus Slag (YPS): Activation and Preparation of Granular Rice Fertilizer

Yellow phosphorus slag (YPS) is a typical industrial solid waste, while it contains abundant silicon micronutrient required for the growth of rice. The key scientific problem to use the YPS as rice fertilizer is how to activate the slag efficiently during the phosphorite reduction smelting process. In this work, an alkaline rice fertilizer from the activated YPS was successfully prepared to use the micronutrients. Thermodynamic analyses of SiO₂-CaO, SiO₂-CaO-Al₂O_3, and SiO₂-CaO-Al₂O₃-MgO systems were discussed to optimize the acidity for reduction smelting. Results showed that the reduction smelting followed by the water quenching process can realize the reduction of phosphorite and activation of YPS synchronously. Ternary acidity m(SiO₂)/(m(CaO) + m(MgO)) of 0.92 is suitable for the reduction smelting and activation of the slag. After smelting, the molten YPS can be effectively activated by water quenching, and 78.28% P, 90.03% Ca, and 77.12% Si in the YPS are activated, which can be readily absorbed by the rice roots. Finally, high-strength granular rice fertilizers with a particle size of Φ2–4 mm were successfully prepared from the powdery nitrogen-phosphorus-potassium (NPK) and activated YPS mixture.