Preparation of a low‐phosphorous terpolymer as a scale,corrosion inhibitor,and dispersant for ferric oxide

A novel low‐phosphorus terpolymer, used as scale, corrosion inhibitor, and dispersant for iron oxide, was prepared through free‐radical polymerization reaction of acrylic acid (AA), oxalic acid‐allypolyethoxy carboxylate (APEM), and phosphorous acid (H₃PO₃) in water with redox system of hypophosphorous and ammonium persulfate as initiator. Structure of the synthesized AA‐APEM‐H₃PO₃ terpolymer was characterized by Fourier transform infrared spectrometer and ¹H‐NMR. The polymer possesses excellent scale inhibition performance for CaCO₃, outstanding ability to disperse ferric oxide, and good corrosion inhibition properties. The study showed that AA‐APEM‐H₃PO₃ exhibited excellent ability to control calcium carbonate scale, with approximately 90.16% CaCO₃ inhibition at a level of 8 mg/L AA‐APEM‐H₃PO₃. The data of the light transmittance showed that, compared to hydrolyzed polymaleic acid and polyepoxysuccinic acid, AA‐APEM‐H₃PO₃ had superior ability to control iron ions scaling. The light transmittance of the solution was about 24.1% in the presence of the terpolymer when the dosage was 8 mg/L. Moreover, the corrosion inhibition efficiency could reach up to 79.77% at a dosage of 30 mg/L, with ethylene diamine tetra methylene phosphonic acid just 39.62%. Scanning electronic microscopy, transmission electron microscope, and X‐ray powder diffraction analysis were used to investigate the effect of AA‐APEM‐H₃PO₃ on morphology of calcium carbonate scale. The low‐phosphorous terpolymer has also been proven to be effective inhibitor of calcium carbonate even at increasing solution temperature, pH, and Ca²⁺ concentration. The proposed inhibition mechanism suggests the surface complexation and chelation between the functional groups ? P(O) (OH)₂, ? COOH and Ca²⁺, with polyethylene glycol segments increasing its solubility in water. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41447.     

Synthesis and evaluation of an environment-friendly terpolymer CaCO3 scale inhibitor for oilfield produced water with better salt and temperature resistance

The CaCO₃ deposits exist widely in the petroleum industry, causing severe damage to the equipment and production. In this article, a novel environment-friendly terpolymer scale inhibitor Poly (maleic anhydride - acrylic acid -2- acrylamide -2- methyl propanesulfonic acid) (P(MA-AA-AMPS))-containing carboxylic acid group, sulfonic acid group, and amide group was synthesized. The structure and molecular weight were characterized by FTIR, ¹H-NMR, and GPC. The static scale inhibition experiment was conducted to study the influence of factors such as the dosage, monomer ratio, temperature, pH, Ca²⁺ concentration, and concentration on the scale inhibition performance of CaCO₃. The results show that when the monomer ratio is 2.0:1.0:0.5 and the dosage is 20 mg L⁻¹, the maximum scale inhibition efficiency is 95.52%. Even when Ca²⁺ concentration exceeds 1200 mg L⁻¹ and temperature reaches 90 °C, the scale inhibition efficiency is still larger than 80%. The results of SEM and XRD show that P(MA-AA-AMPS) interferes with the growth of CaCO₃ crystal by adsorption, dispersion, and chelation. The effect leads to changes in the morphology of CaCO₃ crystals, the size of which drops from 20–30 μm to 2–5 μm. The P(MA-AA-AMPS) can transform CaCO₃ from stable calcite crystals to unstable aragonite and vaterite. Finally, the formation of CaCO₃ scale is well inhibited. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48460.     

Infusion of Ag‐Ion from Aqueous Solution into Solid Calcium Phosphate of Hydroxyapatite (HA) Crystal Structure

In contrast to extensive literature concerning Ag incorporation in hydroxyapatite, HA, while the phosphate approximated to stoichiometry of Ca₁₀(PO₄)₆(OH)₂, with added Ag has been precipitating from an aqueous solution, the paper presents Ag incorporation through Ag ion infusion from AgNO₃ solution into solid HA pressed in pellet and ignited at 800°C. After Ag ions infused into the HA‐solid (crossed the interfacial solution‐solid boundary), they diffused across the crystal structure to a depth of time‐dependent several mm. The path of Ag diffusion in the solid HA was recorded using SEM‐EDS point analyses of Ag, Ca, P, EDS‐linear analyses of those elements, and elemental mapping. Time‐dependent concentrations of Ag⁺, Ca²⁺, and PO₄^3? in AgNO₃ solutions were also analyzed. The appearance of Ag in the crystalline HA with simultaneous local depletion in Ca and phosphate recorded as P, observed by EDS with simultaneous appearance of Ca²⁺ and PO₄^3? ions and a decrease in Ag⁺ concentration in AgNO₃ solution led the authors to a conclusion that Ag⁺ for Ca²⁺ substitution supported by PO₄^3? charge balancing in the crystalline HA was in process. The HA particles in the section of the pellet without Ag had a uniform shape and size approximated to 300–400 nm. SEM image of the HA solid section, where Ag ions appeared was characterized by irregular aggregates of smaller crystals with sporadically present large, shaped in prism blocks identified by the XRD as Ag₃PO₄.     

Hyperbranched polyesters with carboxylic acid functional groups for the inhibition of the calcium carbonate scale

Scale deposits exist widely in industrial water‐cooling systems and oil‐production systems, causing severe damage to the equipment. The most effective way to prevent the formation of scale has been to use an inhibitor. The use of a hyperbranched polymer as an inhibitor, however, has rarely been reported. In this study, we prepared a hydroxyl‐terminated hyperbranched polyester (HBPE–OH) with trimethyloypropane as the core and 2,2‐bis(hydroxymethyl)propionic acid as an AB₂ monomer. The HBPE–OH was then modified with succinic anhydride to obtain the carboxyl‐terminated hyperbranched polyester (HBPE–COOH). The effects of the dosage, Ca²⁺ concentration, pH value, and temperature of the system on the inhibition efficiency were investigated when HBPE–COOH was used as an inhibitor of calcium carbonate (CaCO₃) scale. HBPE–COOH acted as a good antiscaling inhibitor for CaCO₃; when the polyester concentration was 200 mg/L, the scale inhibition rate exceeded 70%. Scanning electron microscopy and X‐ray powder diffraction demonstrated that the mechanism of inhibition was the disturbance of the growth of the crystals and modification of the crystal morphology by the hyperbranched polyester. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46292.     

The Properties of Sintered Calcium Phosphate with [Ca]/[P] = 1.50

In order to obtain the properties of the sintered as-dried calcium phosphate with [Ca]/[P] = 1.50, the characteristics of sintered pellets have been investigated using X-ray diffraction (XRD), inductively coupled plasma-mass spectrometry (ICP-MS), Fourier-transform infrared (FT-IR) spectra, Vickers hardness indentation and scanning electron microscopy (SEM). When the pellet samples were sintered between 700 °C and 1200 °C for 4 h, the hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂, HA) still maintained the major phase, accompanied with the rhenanite (NaCaPO₄) as the secondary phase and β-tricalcium phosphate (β-Ca₃(PO₄)₂, β-TCP) as the minor phases. In addition, the HA partially transformed to α-tricalcium phosphate (α-Ca₃(PO₄)₂, α-TCP) and tetracalcium phosphate (Ca₄(PO4)₂O, TTCP), when the pellet samples were sintered at 1300 °C and 1400 °C, respectively, for 4 h. The maximum density and Vickers Hardness (HV) of sintered pellet samples were 2.85 g/cm³ (90.18% theoretical density (T.D.)) and 407, which appeared at 1200 °C and 900 °C, respectively.     

Synthesis and application of a cyclopolymer bearing a propylphosphonic acid and a propylcarboxylic acid pendants in the same repeating unit

Diallyl[3-(diethoxyphosphoryl)propyl](3-ethoxycarbonylpropyl)ammonium chloride [ (CH₂CH=CH₂)₂N⁺{(CH₂)₃PO₃Et₂} {(CH₂)₃CO₂Et} Cl^?], a new diallyl quaternary ammonium salt, has been cyclopolymerized to its cationic polyelectrolyte having pyrrolidine rings embedded in the polymer backbone. The polymer represents the first example of a cyclopolymer in which each repeating unit contains a propylphosphonate as well as a propylcarboxylate pendant. The hydrolysis of one, two or all the three-ester groups in the polymer afforded a series of pH-responsive macromolecules having identical degree of polymerization, which permitted a meaningful comparison of their solution behaviors. Apparent pK _as of the triprotic repeating unit have been determined to be 2.52, 5.32 for 9.02 for the functionalities –PO₃H₂, ?CO₂H, and –PO₃H^?, respectively. The completely hydrolyzed polymer containing PO₃H₂ and CO₂H groups demonstrated remarkable antiscalant behavior; at a concentration of 10 ppm, it inhibited the scaling of CaSO₄ from its supersaturated solution with an inhibition efficiency of 100 % for over 500 min. The polymer may thus be exploited as an antiscalant in reverse osmosis plants.     

Linalool Activates Oxidative and Calcium Burst and CAM3-ACA8 Participates in Calcium Recovery in Arabidopsis Leaves

Plants produce linalool to respond to biotic stress, but the linalool-induced early signal remains unclear. In wild-type Arabidopsis, plant resistance to diamondback moth (Plutella xylostella) increased more strongly in a linalool-treated group than in an untreated control group. H₂O₂ and Ca²⁺, two important early signals that participated in biotic stress, burst after being treated with linalool in Arabidopsis mesophyll cells. Linalool treatment increased H₂O₂ and intracellular calcium concentrations in mesophyll cells, observed using a confocal microscope with laser scanning, and H₂O₂ signaling functions upstream of Ca²⁺ signaling by using inhibitors and mutants. Ca²⁺ efflux was detected using non-invasive micro-test technology (NMT), and Ca²⁺ efflux was also inhibited by NADPH oxidase inhibitor DPI (diphenyleneiodonium chloride) and in cells of the NADPH oxidase mutant rbohd. To restore intracellular calcium levels, Ca²⁺-ATPase was activated, and calmodulin 3 (CAM3) participated in Ca²⁺-ATPase activation. This result is consistent with the interaction between CAM7 and Ca²⁺-ATPase isoform 8 (ACA8). In addition, a yeast two-hybrid assay, firefly luciferase complementation imaging assay, and an in vitro pulldown assay showed that CAM3 interacts with the N-terminus of ACA8, and qRT-PCR showed that some JA-related genes and defense genes expressions were enhanced when treated with linalool in Arabidopsis leaves. This study reveals that linalool enhances H₂O₂ and intracellular calcium concentrations in Arabidopsis mesophyll cells; CAM3-ACA8 reduces intracellular calcium concentrations, allowing cells to resume their resting state. Additionally, JA-related genes and defense genes’ expression may enhance plants’ defense when treated with linalool.     

Preparation of carboxy sulfonic acid-containing copolymer scale inhibitors and their scale inhibition effect on CaCO3

Free radical polymerization was selected to obtain a promising copolymer scale inhibitor IA-AM-SAS with good water solubility and temperature and salt resistance, which is suitable for the treatment of surface pipeline water in oil fields, using itaconic acid (IA), acrylamide (AM), and sodium acrylsulfonate (SAS) as the monomers. The structure of the synthesized copolymer was verified by Fourier transform infrared spectroscopy and nuclear magnetic resonance hydrogen spectroscopy. Thermogravimetric results showed that the copolymer does not undergo significant thermal degradation at temperatures below 356°C, indicating that the copolymer has good thermal stability. The molecular weights of the polymers at different monomer ratios were measured using gel permeation chromatography and the relationship between the molecular weights and scale inhibition performance was discussed. The results showed that the scale inhibition effect was best when the monomer molar ratio n(IA): n(AM): n(SAS) was 0.5:2:1.5 and the number of average molecular weight of the prepared copolymer was 7712 g/mol, and the inhibition efficiency of CaCO₃ was 84.02% when IA-AM-SAS was at a concentration of 30 mg L⁻¹, and the inhibition rate was measured by the standard of static scale inhibition test in the oilfield measured. The range of conditions (PH, Ca²⁺ concentration, water temperature, and time) of the static scale inhibition test was then expanded using a one-way controlled variable experiment to explore the performance of IA-AM-SAS scale inhibitors under different water quality conditions. The scale inhibition mechanism was explored by scanning electron microscopy, x-ray diffraction, and x-ray photoelectron spectroscopy. Briefly, the combination of multiple functional groups enables IA-AM-SAS to be applied in complex and challenging environments.     

Study on Calcium Scales Inhibition Performance in the Presence of Double-Hydrophilic Copolymer

Novel double-hydrophilic block copolymers, acrylic acid (AA)-2-acrylamido-2-methyl-propane sulfonate (AMPS)-oxalic acid-allypolyethoxy carboxylate (APEM) was specially designed and synthesized from allyloxy polyethoxy ether (APEG) to inhibit the precipitation of CaCO₃ and CaSO₄. The structure of the copolymer was characterized by FT-IR and H¹-NMR. Using the static experiment method, the scale inhibition efficiencies for CaCO₃ and CaSO₄ scale were investigated. It was shown that AA-AMPS-APEM exhibited excellent ability to control inorganic minerals scales, with approximately 97.1% CaSO₄ inhibition and displayed significant ability to prevent the formation of CaCO₃ scales. The synthesized AA-AMPS-APEM was also compared with that of current commercial inhibitors. The effect of the copolymer addition on the crystals of CaCO₃ and CaSO₄ scales morphology and structures were examined through scanning electron microscope (SEM), transmission electron microscope (TEM), and X-ray diffraction studies (XRD). It proved that great changes in the size and morphology of the calcium scales took place under the influence of AA-AMPS-APEM. The proposed inhibition mechanism suggests the formation of complexes between the side-chain carboxyl groups of AA-AMPS-APEM and calcium ions on the surface of inorganic minerals, and the excellent solubility of complexes resulted from a number of hydrophilic polyethylene glycol (PEG) and sulfonic group (-SO₃H) group.     

Adsorption and inhibitive action of hexadecylpyridinium bromide on steel in phosphoric acid produced by dihydrate wet method process

The adsorption and inhibitive action of hexadecylpyridinium bromide (HDPB) on the corrosion of cold rolled steel (CRS) in phosphoric acid produced by dihydrate wet method process (7.0 M H₃PO₄) was studied by weight loss, open circuit potential (OCP), potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM), and atomic force microscopy (AFM) methods. The results show that HDPB is a good inhibitor in 7.0 M H₃PO₄, and its maximum inhibition efficiency (IE) is higher than 90% at little concentrations. The adsorption of HDPB obeys Langmuir adsorption isotherm equation. Thermodynamic parameters (adsorption enthalpy ∆H ⁰, adsorption free energy ∆G ⁰, and adsorption entropy ∆S ⁰) were calculated and discussed. Polarization curves show that HDPB acts as a mixed-type inhibitor in phosphoric acid. EIS shows that charge-transfer resistance increases with the inhibitor concentration, confirming adsorption process mechanism. The inhibition action of HDPB could also be evidenced by SEM and AFM images. A probable inhibitive mechanism is proposed from the viewpoint of adsorption theory.     

Defluoridation performance and mechanism of nano‐scale aluminum oxide hydroxide in aqueous solution

BACKGROUND: The present study has concentrated on investigating the fluoride removal potential of nano‐scale aluminum oxide hydroxide (nano‐AlOOH). A series of batch adsorption experiments were carried out to assess parameters that influence the adsorption process. The different parameters investigated include the effect of contact time, initial fluoride concentration, adsorbent dose, pH of the solution and co‐existing anions. RESULTS: Most of the adsorption took place during the first 30 min and kinetic and equilibrium adsorption data show that the process obeys a pseudo‐second‐order kinetic equation and the Langmuir adsorption model. The fluoride removal efficiency is greater than 90% between pH 6 and 8 and decreases as pH values increase to 11. The presence of SO₄^2? or PO₄^3? in aqueous solution was found to reduce the fluoride uptake. Desorption studies showed that the fluoride can easily be desorbed at pH 13. CONCLUSION: Nano‐AlOOH possesses a maximum fluoride capacity of 3259 mg F^? kg^?1, which is comparable with that of activated alumina. Maximum adsorption occurred at around pH 7, which makes nano‐AlOOH a potential adsorbent for drinking water treatment. Copyright © 2009 Society of Chemical Industry     

Exploration of As(III)/As(V) Uptake from Aqueous Solution by Synthesized Calcium Sulfate Whisker

Although common calcium-containing minerals such as calcite and gypsum may fix arsenic, the interaction between modified calcic minerals and arsenic has seldom been reported. The uptake behavior of As(III)/As(V) from aqueous solutions by calcium sulfate whisker (CSW, dihydrate or anhydrite) synthesized through a cooling recrystallization method was explored. A series of batch experiments were conducted to examine the effect of pH, reaction time, whisker dosage, and initial As concentration. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the samples prepared. The results showed that pH of the aqueous solution was an important parameter for As(III)/As(V) uptake, and an excellent removal efficiency could be achieved under strongly alkaline condition. The data from batch experiments for reaction of As(V) with calcium sulfate dihydrate whisker (CSDW) and calcium sulfate anhydrous whisker (CSAW) were well described with extended Langmuir EXT1 model, from which theoretic maximum adsorption capacity of 46.57 mg As(V)·(g CSDW)^− 1 and 39.18 mg As(V)·(g CSAW)^− 1 were obtained. Some calcium arsenate solids products, such as CaAsO₃(OH) (weilite, syn), Ca₃(AsO₄)₂ (calcium arsenate), CaO–As₂O₅, Ca–As–O, Ca₅(AsO₄)₃OH·xH₂O (calcium arsenate hydroxide hydrate), and CaH(AsO₄)·2H₂O (hydrogen calcium arsenic oxide hydrate), were detected at pH = 12.5 through XRD analysis. This indicates that the interaction mechanism between As(V) and CSW is a complex adsorption process combined with surface dissolution and chemical precipitation.     

Warm white-light generation in Ca9MgNa(PO4)7:Sr2+, Mn2+, Ln (Ln=Eu2+, Yb3+, Er3+, Ho3+, and Tm3+) under near-ultraviolet and near-infrared excitation

To obtain warm white-light emission, a series of Ca₉MgNa(PO₄)₇:Sr²⁺, Mn²⁺, Ln (Ln=Eu²⁺, Yb³⁺, Er³⁺, Ho³⁺, and Tm³⁺) phosphors were designed and their photoluminescence properties under near-ultraviolet and near-infrared excitation were studied. For near-ultraviolet excitation, blue-white emission is produced initially in the Eu²⁺ single-doped Ca₉MgNa(PO₄)₇, whose excitation band can well match with the near ultraviolet LED chip. By introducing Sr²⁺ ions into Ca₉MgNa(PO₄)₇:Eu²⁺, the Eu²⁺ emission band beyond 500 nm is enhanced obviously. Correspondingly, the emitting light color is tuned to nearly white. To generate warm white light further, Mn²⁺ is doped into the Ca_8.055MgNa(PO₄)₇:0.045Eu²⁺, 0.9Sr²⁺ and the correlated color temperature is decreased largely. For near-infrared excitation, the green, red, and blue emissions have been obtained in the Yb³⁺-Er³⁺, Yb³⁺-Er³⁺, and Yb³⁺-Er³⁺ co-doped Ca₉MgNa(PO₄)₇ phosphors, respectively. And warm white light is also produced in the Ca₉MgNa(PO₄)₇:Yb³⁺, Er³⁺, Ho³⁺, Tm³⁺ under 980 nm excitation.     

IFCC recommendation on sampling,transport and storage for the determination of the concentration of ionized calcium in whole blood,plasma and serum

The substance concentration of ionized calcium (c _Ca²⁺) in blood, plasma or serum preanalytically may be affected by pH changes of the sample, calcium binding by heparin, and dilution by the anticoagulant solution.pH changes in whole blood can be minimized by anaerobic sampling to avoid loss of Co₂, by measuring as soon as possible, or by storing the sample in iced water to avoid lactic acid formation. c_Ca ²⁺ and pH should be determined simultaneously.Plasma or serum: If centrifuged in a closed tube, and measured immediately, the pH of the sample will be close to the original value. If a delay has occurred between centrifugation and the measurement, causing substantial loss of Co₂, equilibration of the sample with a gas mixture corresponding to pCO2= 5.3 kPa prior to the measurement is recommended. Conversion of the measured values to c_Ca ²⁺ (7.4) is only valid if the pH is in the range 7.2-7.6.Ca²⁺ binding by heparin can be minimized by using either of the following:(1) A final concentration of sodium or lithium heparinate of 15 IU/ml blood or less(2) Calcium titrated heparin with a final concentration of less than 50 IU/ml blood.Dilution effect can be avoided by use of dry heparin in capillaries or syringes. When heparin solutions are used, errors due to dilution or calcium binding can be reduced by using syringes with a heparin solution containing free calcium ions corresponding to the mean concentration of ionized calcium in normal plasma.Conditions for blood collection, storage, and transport to avoid preanalytical errors are described in this paper.     

A novel dazzling Eu3+‐doped whitlockite‐type phosphate red‐emitting phosphor for white light‐emitting diodes

A series of novel red‐emitting Ca₈ZnLa_1?xEu_x(PO₄)₇ phosphors were successfully synthesized using the high‐temperature solid‐state reaction method. The crystal structure, photoluminescence spectra, thermal stability, and quantum efficiency of the phosphors were investigated as a function of Eu³⁺ concentration. Detailed analysis of their structural properties revealed that all the phosphors could be assigned as whitlockite‐type β‐Ca₃(PO₄)₂ structures. Both the PL emission spectra and decay curves suggest that emission intensity is largely dependent on Eu³⁺ concentration, with no quenching as the Eu³⁺ concentration approaches 100%. A dominant red emission band centered at 611 nm indicates that Eu³⁺ occupies a low symmetry sites within the Ca₈ZnLa(PO₄)₇ host lattice, which was confirm by Judd‐Ofelt theory. Ca₈ZnLa_1?xEu_x(PO₄)₇ phosphors exhibited good color coordinates (0.6516, 0.3480), high color purity (~96.3%), and high quantum efficiency (~78%). Temperature‐dependent emission spectra showed that the phosphors possessed good thermal stability. A white light‐emitting diode (LED) device were fabricated by integrating a mixture of obtained phosphors, commercial green‐emitting and blue‐emitting phosphors into a near‐ultraviolet LED chip. The fabricated white LED device emits glaring white light with high color rendering index (83.9) and proper correlated color temperature (5570 K). These results demonstrate that the Ca₈ZnLa_1?xEu_x(PO₄)₇ phosphors are a promising candidate for solid‐state lighting.     

Regression model,artificial intelligence,and cost estimation for phosphate adsorption using encapsulated nanoscale zero-valent iron

This study investigated the adsorption of PO₄^3? onto encapsulated nanoscale zero-valent iron (nZVI). At initial PO₄^3–: 10 mg · L^?1, the optimum condition was initial pH: 6.5, nZVI dosage: 20 g · L^?1, stirring-rate: 100 rpm, and time: 30 min, achieving PO₄^3? removal of 42%. The effect of pH and time on the PO₄^3? removal efficiency was quadratic-linear concave up, whereas the curve of nZVI dosage was quadratic-convex. Artificial neural network with a structure of 5?7?1 adequately predicted PO₄^3? removal (R²: 97.6%), and the sensitivity analysis demonstrated that pH was the most influential input. The cost of the adsorption unit was 3.15 $USD · m^?3.     

Synthesis and luminescence properties of single‐component Ca5(PO4)3F:Dy3+, Eu3+ white‐emitting phosphors

A series of Ca₅(PO₄)₃F:Dy³⁺, Eu³⁺ phosphors was synthesized by a solid‐state reaction method. The XRD results show that all as‐prepared Ca₅(PO₄)₃F:Dy³⁺, Eu³⁺ samples match well with the standard Ca₅(PO₄)₃F structure and the doped Dy³⁺ and Eu³⁺ ions have no effect on the crystal structure. Under near‐ultraviolet excitation, Dy³⁺ doped Ca₅(PO₄)₃F phosphor shows blue (486 nm) and yellow (579 nm) emissions, which correspond to ⁴F_9/2→⁶H_15/2 and ⁴F_9/2→⁶H_13/2 transitions respectively. Eu³⁺ co‐doped Ca₅(PO₄)₃F:Dy³⁺ phosphor shows the additional red emission of Eu³⁺ at 631 nm, and an improved color rendering index. The chromaticity coordinates of Ca₅(PO₄)₃F:Dy³⁺, Eu³⁺ phosphors also indicate the excellent warm white emission characteristics and low correlated color temperature. Overall, these results suggest that the Ca₅(PO₄)₃F:Dy³⁺, Eu³⁺ phosphors have potential applications in warm white light‐emitting diodes as single‐component phosphor.     

Calcium activation of peanut lipoxygenase

Peanut lipoxygenase isozyme 1 (pH optimum, 8.3) was strongly activated by 0.5–1.0 mM Ca⁺⁺, and the rate of activation was maximum when the ratio of substrate to Ca⁺⁺ was ca. 2∶1. Peanut lipoxygenase isozymes 2 and 3 (pH optima, 6.2) were activated by calcium but did not have an optimum level of activity. Calcium differentially activated peanut lipoxygenase causing the rate of pentane production to increase much more rapidly than the rate of oxygen consumed by the enzyme reaction. At pH 6.2, in the absence of calcium, the percentages of the hydroperoxide isomers produced by peanut lipoxygenase were 74.9% 13-hydroperoxycis-9,trans-11-octadecadienoic acid (13 LOOHcis-trans), 2.6% 13-hydroperoxytrans-9,trans-11-octadecadienoic acid (13 LOOHtrans-trans) and 22.5% 9-hydroperoxy 10, 12-octadecadienoic acid (9 LOOH). The presence of 1 mM Ca⁺⁺ at pH 6.2 did not significantly affect the percentage distribution of the hydroperoxides produced. However, at pH 8.3, the percentage distribution of hydroperoxides produced was 45.2% 13 LOOHcis-trans, 10.9% 13 LOOHtrans-trans and 43.9% 9 LOOH in the absence of Ca⁺⁺ and 57.0% 13 LOOHcis-trans, 8.0% 13 LOOHtrans-trans and 35.0% 9 LOOH in the presence of 1 mM Ca⁺⁺. Paper No. 5110 of the Journal of the North Carolina Agricultural Experiment Station, Raleight, NC 27607.     

The Role of Calcium Signaling in Melanoma

Calcium signaling plays important roles in physiological and pathological conditions, including cutaneous melanoma, the most lethal type of skin cancer. Intracellular calcium concentration ([Ca²⁺]i), cell membrane calcium channels, calcium related proteins (S100 family, E-cadherin, and calpain), and Wnt/Ca²⁺ pathways are related to melanogenesis and melanoma tumorigenesis and progression. Calcium signaling influences the melanoma microenvironment, including immune cells, extracellular matrix (ECM), the vascular network, and chemical and physical surroundings. Other ionic channels, such as sodium and potassium channels, are engaged in calcium-mediated pathways in melanoma. Calcium signaling serves as a promising pharmacological target in melanoma treatment, and its dysregulation might serve as a marker for melanoma prediction. We documented calcium-dependent endoplasmic reticulum (ER) stress and mitochondria dysfunction, by targeting calcium channels and influencing [Ca²⁺]i and calcium homeostasis, and attenuated drug resistance in melanoma management.     

Effect of A+ (A = Li,Na and K) co-doping on enhancing the luminescence of Ca5(PO4)2SiO4:Eu3+ red-emitting phosphors as charge compensator

A series of Ca_5-x(PO₄)₂SiO₄:xEu³⁺ red-emitting phosphors were synthesized through solid-state reaction, and alkali metal ions A⁺ (A = Li, Na and K) were co-doped in Ca₅(PO₄)₂SiO₄:Eu³⁺ to improve its luminescence property. The impacts of synthesis temperature, luminescence center Eu³⁺ concentration and charge compensator A⁺ on the structure and luminescence property of samples were studied in detail. X-ray diffraction results indicated that prepared Ca₅(PO₄)₂SiO₄:Eu³⁺, A⁺ had a standard Ca₅(PO₄)₂SiO₄ structure with space group P6₃/m. Under the excitation of 392 nm, Ca₅(PO₄)₂SiO₄:Eu³⁺ phosphors showed a red emission consisting of several emission peaks at 593 nm, 616 nm and 656 nm, relevant to ⁵D₀→⁷F₁, ⁵D₀→⁷F₂ and ⁵D₀→⁷F₄ electron transitions of Eu³⁺ ions, respectively. Luminescence intensity and lifetime of Ca₅(PO₄)₂SiO₄:Eu³⁺ can be significantly enhanced through co-doping alkali metal ion A⁺, which play an important role as charge compensator. The results suggest that Ca₅(PO₄)₂SiO₄:Eu³⁺, A⁺ red phosphors with excellent luminescence property are expectantly served as red component for white light-emitting diodes excited by near-ultraviolet.