Introduction Of Ca2 Research Articles

Mechanistic Insights into Synaptotagmin-1 Mediated Membrane Fusion and Interactions.

We present two innovative approaches to investigate the dynamics of membrane fusion and the strength of protein-membrane interactions. The first approach employs pore-spanning membranes (PSMs), which allow for the observation of protein-assisted fusion processes. The second approach utilizes colloidal probe microscopy with membrane-coated probes with reconstituted proteins. PSMs enable one to obtain detailed information about the fusion process with particular emphasis on fusion intermediates and fusion pore formation. We demonstrate the potential of the PSM system using SNARE-mediated fusion. Accompanied by colloidal probe microscopy, molecular information can be gathered on how full-length synaptotagmin-1 (syt-1) contributes to the fusion process. We propose that syt-1 engages with anionic bilayers, significantly modifying the adhesion between membranes. The introduction of Ca2+ transforms these interactions, shifting from a state of minimal interaction force between bilayers to one of pronounced strength. This syt-1 interaction facilitates fusion in the presence of Ca2+ with a significant reduction in the occurrence of stalled intermediate fusion states. Moreover, the presence of Ca2+ significantly accelerates the fusion process, an effect that is further amplified by the addition of multivalent anions such as ATP.

Pro-inflammatory S100A8 Protein Exhibits a Detergent-like Effect on Anionic Lipid Bilayers, as Imaged by High-Speed AFM.

Neuronal cell death induced by cell membrane damage is one of the major hallmarks of neurodegenerative diseases. Neuroinflammation precedes the loss of neurons; however, whether and how inflammation-related proteins contribute to the loss of membrane integrity remains unknown. We employed a range of biophysical tools, including high-speed atomic force microscopy, fluorescence spectroscopy, and electrochemical impedance spectroscopy, to ascertain whether the pro-inflammatory protein S100A8 induces alterations in biomimetic lipid membranes upon interaction. Our findings underscore the crucial roles played by divalent cations and membrane charge. We found that apo-S100A8 selectively interacts with anionic lipid membranes composed of phosphatidylserine (PS), causing membrane disruption through a detergent-like mechanism, primarily affecting regions where phospholipids are less tightly packed. Interestingly, the introduction of Ca2+ ions inhibited S100A8-induced membrane disruption, suggesting that the disruptive effects of S100A8 are most pronounced under conditions mimicking intracellular compartments, where calcium levels are low, and PS concentrations in the inner leaflet of the membrane are high. Overall, our results present a mechanistic basis for understanding the molecular interactions between S100A8 and the plasma membrane, emphasizing S100A8 as a potential contributor to the onset of neurodegenerative diseases.

Surface and morphology modulated adsorption-activation of trace concentration hydrogen peroxide with multiple electron transfer pathways and sustained Fenton reactions

To promote mass transfer and activation of hydrogen peroxide (H2O2) in Fenton-like reactions, a novel MOFs-derived Fe2O3 was tailor-designed through surface sulfur modification and morphology tuning for degrading a group of persistent micropollutants, i.e., sulfamethoxazole, enrofloxacin, and ofloxacin. The introduction of Ca2+ and Mg2+ modulated the growth of crystal clusters to prevent aggregation of Fe2O3 nanoparticles and provide more reaction sites. Likewise, the abundant acid sites (–SO3H) promote the chemisorption of even trace-concentration H2O2 (S–O bonding), whereas the S–Fe bonding accelerates electron transfer to promote the Fe3+/Fe2+ cycle and thus the H2O2 utilization. More interestingly, surface-adsorbed H2O is found to be activated to form •OH, due to electron-poor Fe sites formed after detachment of –SO3H, demonstrating a sustained radical yield for the micropollutant degradation. This study opens new perspectives in catalyst design to ultimately realize the utilization of trace-concentration H2O2 and even H2O in Fenton-like systems.

Enhanced H2S removal efficiency using CuO/Al2O3 catalyst impregnated with Ca(NO3)2: Influence of calcination temperature and mechanistic insights

A series of Ca(NO3)2-CuxO/Al2O3 catalysts with different calcination temperatures were designed to remove H2S effectively. Experimental and characterization results indicate that the calcination temperature can influence the catalyst's specific surface area, basic sites, and oxygen vacancies (VOs) concentration, thereby promoting its desulfurization performance. The Ca(NO3)2-CuxO/Al2O3 catalyst, calcined at 230 °C, exhibits an optimal surface structure. It demonstrates optimal H2S desulfurization performance at a temperature of 60 °C and relative humidity of 60 %, achieving a removal capacity of 486.67 mg/g. The VOs in CuxO (CuO and Cu2O) induce a unique catalytic of H2O, which generates hydroxy radicals (·OH) to oxidize the H2S anion to S. The introduction of Ca2+ provides basic sites to buffer pH, and NO3- with H+ removes H2S through cyclic oxidation, significantly enhancing the desulfurization performance of the Cu-based catalyst. The CaO-CuxO/Al2O3 catalyst, calcined at 700 °C, suffers from a deteriorated catalyst structure, leading to the rapid formation of desulfurization by-products due to the presence of CaO covering the catalyst surface. This diminishes the effectiveness of Cu, significantly impairing the catalyst's desulfurization performance (150.47 mg/g). Consequently, desulfurization mechanisms of Ca(NO3)2-CuxO/Al2O3 and CaO-CuxO/Al2O3 are proposed, offering effective strategies for the design and optimization of subsequent high-efficiency catalysts.

CaCl2 doping effect on optical and structural properties of halide perovskites under ligand assisted reprecipitation synthesis

The high potential of metal halide perovskite (MHP) nanocrystals with the general formula CsPbX3 (X = Cl, Br, and I) has led to the development of easy and cost-effective methods on a daily basis. The room temperature (RT) and open atmosphere ligand-assisted reprecipitation (LARP) methods were utilized to synthesize CsPbBr3 and CsPbBr2I nanocrystals (NCs). CaCl2 was used as a dopant in four different concentrations (0.25, 0.5, 0.75, and 1 % molar) to optimize the optical and electrical properties and to enhance the stability of NCs. The most optimal results were observed with 0.25 % doping for CsPbBr2I and 0.75 % doping for CsPbBr3. XRD and FE-SEM analyses revealed a cubic crystal structure for the synthesized nanocrystals. Dynamic light scattering (DLS) analysis indicated an average size of was 35–70 nm. The introduction of Ca2+ impurity, resulted in increased sizes for 0.75 % doped CsPbBr3 NCs; and increased intensity for 0.25 % doped CsPbBr2I NCs. Optical studies, including UV–vis, Fourier Transform Infrared (FTIR), and photoluminescence spectroscopies were conducted. The bandgap of CsPbBr2I and CsPbBr3 was estimated at 2.60 and 2.75 eV, respectively. The FTIR spectra suggested the effective involvement of the ligand agents oleic acid (OA) and oleylamine (OLA) in synthesis of metal halide perovskite nanocrystals. Photoluminescence spectroscopy demonstrated that the photoluminescence intensity of CsPbBr2I and CsPbBr3 varied with impurity doping, indicating an enhancement of semiconductor electronic properties under Ca2+ doping.

Acrylic acid incorporated nanocellulose/acrylamide ion-conductive hydrogels for wearable sensors

In this paper, CNC/PAM/PAA interpenetrating network composite hydrogels were prepared from acrylamide (AM), cellulose nanocrystals (CNC), and acrylic acid (AA) by in situ free radical polymerization. CNC/PAM/PAA-Ca2+ hydrogels were successfully prepared by adding CaCl2 to the mixed solution to introduce ions. The composite hydrogels were characterized using scanning electron microscopy and Fourier transform infrared spectroscopy and tested for their mechanical, electrical, and sensing properties. The experimental results showed that the copolymerization reaction of AM and AA resulted in hydrogels with excellent mechanical properties, with a maximum tensile strength of 98.7 kPa and an elongation at break of 643.6%. In addition, the introduction of Ca2+ ions significantly improved the conductivity and sensitivity of the hydrogel. The developed multifunctional poly (AM-AA) hydrogels were able to stably detect the relative changes in electrical resistance during cyclic tensile, compressive, and bending motions of a human finger, which is expected to be widely used in flexible sensor devices.

Simultaneous modification of Na-rich and Ca2+/Ni2+ dual-substitution boosting superior electrochemical performance of Na3V2(PO4)3

The lower intrinsic electronic conductivity of Na3V2(PO4)3(NVP) has seriously limited its further development. Herein, Ca2+/Ni2+ co-doped and carbon nanotubes (CNTs)-coated Na3+x+0.04V1.96-xCa0.04Nix(PO4)3/C@CNTs (CaNi0.07@CNTs) system is presented. Both Ca2+ and Ni2+ are substituted for V3+, triggering charge compensation and producing p-type doping effect, generating abundant hole carriers to improve electronic conductivity. Furthermore, the ionic radius of Ca2+ is significantly larger than that of V3+, so introduction of Ca2+ can support NVP crystal structure and improve the stability. Furthermore, the introduction of Ca2+ can increase the lattice spacing, thus expanding the transport channels for sodium ions. The introduction of Ni2+ reduces the resistance suffered during charge transport and optimizes the chemical properties. Meanwhile, due to low valence of Ca2+ and Ni2+, more Na+ are designed to be introduced to the NVP system for charge balance. The Na-rich strategy induces excess active Na+ participating in the de-intercalation process to supply more reversible capacities. Furthermore, the CNTs wrapped around the active grains serves to buffer deformation of the crystal and to establish a conductive network connecting the particles. The after-cycling XRD/SEM/XPS further confirms the improved crystal stability of CaNi0.07@CNTs. Comprehensively, CaNi0.07@CNTs possess superior sodium storage in half and full cells.

Hydrated Calcium Vanadate Nanoribbons with a Stable Structure and Fast Ion Diffusion as a Cathode for Quasi-Solid-State Zinc-Ion Batteries.

We demonstrated the use of hydrated calcium vanadate (CaV6O16·3H2O, denoted as CaVO-2) as a cathode for aqueous zinc-ion batteries (AZIBs). Nanoribbons of hydrated calcium vanadate facilitated shortening of the Zn2+ transport distance and accelerated zinc-ion insertion. The introduction of interlayer structure water increased the interlayer spacing of calcium vanadate and as a "lubricant". Ca2+ insertion also expanded the interlayer spacing and further stabilized the interlayer structure of vanadium-based oxide. The density functional theory results showed that the introduction of Ca2+ and structured water could effectively improve the diffusion kinetics, resulting in the rapid transport of zinc ions. As a result, AZIBs based on the CaVO-2 cathode offered high specific capacity (329.6 mAh g-1 at 200 mA g-1) and fast charge/discharge capability (147 mAh g-1 at 10 A g-1). Impressively, quasi-solid-state zinc-ion batteries based on the CaVO-2 cathode and polyacrylamide-cellulose nanofiber hydrogel electrolytes maintained an outstanding specific capacity and long cycle life (162 mAh g-1 over 10 000 cycles at 5 A g-1). This study provided a reliable strategy for metal-ion insertion and the structural water introduction of oxides to produce a high-quality cathode for ZIBs. Meanwhile, it provides ideas for the combination of vanadium-based materials and gel electrolytes to construct solid-state zinc-ion batteries.

Calcium-facilitated adsorption and precipitation of bacteria on the graphene oxide surface

Efficient removal of bacteria from aqueous environments is a hot research topic. Graphene oxide (GO) has been widely used due to its antimicrobial properties and high surface activity. However, GO alone could not remove bacteria from the aqueous environment through aggregation and precipitation. In this study, CaCl2 (Ca2+) was introduced into the process of bacterial removal by GO due to the negative charge on the surface of the removed bacteria (Sporosarcina pasteurii). The introduction of Ca2+ leads to the re-accumulation of GO layers, and the proportion of oxygen-containing functional groups in GO increases significantly. AFM and zeta potential results indicate a reduction in the negative charge on the GO surface in the presence of Ca2+, which reduces the electrostatic repulsion to bacteria. This leads to a gradual increase in the attractiveness of the GO surface and the adsorption of more bacteria. Ca2+ acts as a bridge, facilitating the sedimentation of GO and bacteria, resulting in the removal of bacteria from the water environment. The removal efficiency of GO against bacteria increased as the concentration of Ca2+ increased.

Double physical network hydrogels with rapid self-recovery and multistimuli-responsive shape memory effects based on low-methoxyl pectin and host-guest interactions

Double physical network (DPN) hydrogels exhibit superior performance compared with other hydrogel types due to their unique crosslinking structure. However, certain mechanical properties, such as self-recovery and fatigue resistance, still need improvement, and stimuli-responsiveness can be expanded for a wider range of applications. In this study, we presented a facile strategy for designing multifunctional DPN hydrogels based on a poly-cyclodextrin (PCD) and adamantane (Ad) host-guest supramolecular crosslinked polyacrylamide (PAAm) network and a low-methoxyl pectin (LMP) network established through Ca2+ or H+. ‘Egg box’ junction zones between Ca2+ and COO− on the LMP chains, as well as hydrogen bonding and hydrophobic association junction zones, could be formed during this process. The synergistic effect of the flexible supramolecular network and the stiff LMP network imparted remarkable stress tolerance, fatigue resistance, ductility, and anti-piercing capacities to the DPN hydrogels. The thermal reversible DPN structure also endowed the hydrogel with thermal-accelerated rapid self-recovery, as the hydrogel can virtually recover to its original state within 40 min at 80 °C. Multistimuli-responsive including chemical- and thermal-induced shape memory behavior was achieved based on the versatile LMP network. The temporary shape of the LMP hydrogel could be fixed with the introduction of Ca2+ or H+, while spontaneous shape recovery was observed under near infrared (NIR) radiation or immersion in K2CO3 or NaOH solutions, respectively. Additionally, the DPN hydrogels exhibited notable self-healing behavior when the cut surfaces were contacted and stored at 80 °C. More importantly, green natural resources derived raw materials of cyclodextrin (CD) and LMP also offered a sustainable strategy to prepare functional hydrogels. The combination of the above features of the LMP DPN hydrogel provided a new method for designing smart materials with ideal functions for soft actuators and biomedical applications.

Genesis and supergene weathering of tetrahedrite-(Hg) in meta-carbonate rocks: Bearing on differential mobility of priority pollutant metals

The Cu-Sb-Hg mineralization of San Giuliano Terme (Monti Pisani, Tuscany, Italy) is characterized by the widespread occurrence of deeply altered tetrahedrite-(Hg) hosted within joints and faults in the Liassic “Calcari ceroidi” Formation. Through a multi-technique approach (optical and scanning electron microscopy, electron microprobe analysis, single-crystal and powder X-ray diffraction, micro-Raman spectroscopy, X-ray fluorescence, fluid inclusion analysis), tetrahedrite-(Hg) and its alteration products have been characterized and data about its genesis and successive supergene weathering have been collected. Tetrahedrite-(Hg) from San Giuliano Terme has the empirical formula Cu9.92Ag0.02(Hg1.64Fe0.30Zn0.04)Σ1.98(Sb3.53As0.56)Σ4.09S12.95, and is found with scarce gangue minerals represented by calcite, baryte, and very rare fluorite. The mineralization formed from hydrothermal fluids with moderately high salinity (∼17.5 wt% NaClequiv.) of dominantly metamorphic origin at T ∼ 285 °C. Tetrahedrite-(Hg) is usually fully replaced by a mixture of cinnabar, roméite-group minerals, malachite, and rarely azurite. Based on the modal abundance of the mineralogical constituents and their micro-textures, four stages of supergene weathering of tetrahedrite-(Hg) have been recognized. The alteration stages reflect the progressive ingression of meteoric water into the system, with consequent oxidation of tetrahedrite-(Hg) and the introduction of Ca2+, HCO3– and H2O, as well as the progressive removal of S, Sb, and Cu. The relative proportions of the supergene minerals in the four alteration stages can be taken as a proxy for the mobility of the main chemical constituents of tetrahedrite-(Hg), three of which (Hg, Sb, and Cu) are priority pollutant metals. Mercury was found to be the least mobile element in the reconstructed geochemical process. In fact, the widespread precipitation of cinnabar in the space formerly occupied by tetrahedrite-(Hg) hinders the dispersion of Hg in the environment, sequestering it in a solid matrix.

Effect of calcium ions on the surface properties of heterogenite and conducive to sulfidization flotation: Insight from oxygen vacancy

It is challenging to obtain a satisfactory sulfidization effect via direct sulfidization of heterogenite, and the introduction of Ca2+ to modify the surface property of heterogenite could improve its sulfidization. Tests using ICP-OES and SEM-EDS showed that Ca2+ modified the surface morphology of heterogenite, facilitating sulfur ion adsorption. FT-IR and Raman spectrometer analysis revealed that the pre-treatment of Ca2+ was beneficial to form more Co-S bonds on the surface of heterogenite. XPS analysis indicated that Ca2+ modified heterogenite surface properties by creating more oxygen vacancies, which was further supported by EPR test results. DFT calculations further show that oxygen vacancies could increase the adsorption capacity of Co sites on the heterogenite surface. Furthermore, micro-flotation tests showed that the surface modification of Ca2+ could significantly improve the sulfidization flotation recovery of heterogenite. This study found calcium ions enhance the sulfidization of heterogenite by inducing surface oxygen vacancies, which provides a new perspective for understanding and enhancing the sulfidization process of heterogenite and contributes to the efficient recovery of cobalt oxide ore.

Ca2+ enhanced far-red emission performance and efficiency of SrGd2Al2O7:Mn4+ phosphor for the potential application in plant growth lighting.

Mn-based phosphors with the wavelength of 700-750nm are an important category of far-red phosphors that have promising potential in the application of plant lighting, and the higher ability of the far-red light emitting of the phosphors is beneficial to plant growth. Herein, a series of Mn4+- and Mn4+/Ca2+-doped double perovskite SrGd2Al2O7 red-emitting phosphors with wavelengths centered at about 709nm were successfully synthesized by means of a traditional high-temperature solid-state method. First-principles calculations were conducted to explore the intrinsic electronic structure of SrGd2Al2O7 for a better understanding of the luminescence behavior in this material. Extensive analysis demonstrates that the introduction of Ca2+ ions into the SrGd2Al2O7:Mn4+ phosphor has significantly boosted the emission intensity, internal quantum efficiency, and thermal stability by 170%, 173.4%, and 113.7%, respectively, which are superior to those of most other Mn4+-based far-red phosphors. The mechanism of the concentration quench effect and the positive effect of co-doping Ca2+ ions in the phosphor were extensively explored. All studies suggest that the SrGd2Al2O7:0.1%Mn4+, 11%Ca2+ phosphor is a novel phosphor that can be used to effectively promote the growth of plants and regulate the flowering cycle. Therefore, promising applications can be anticipated from this new phosphor.

Structure characterization and calcium ions induced emulsion gel properties of pectic polysaccharide from Fructus aurantii

A novel pectic polysaccharide was extracted from Fructus aurantii using ammonium oxalate extraction, whose primary structure and emulsification properties were investigated for the first time. Fructus aurantii ammonium oxalate-extracted pectin (FAOP) was a highly methyl-esterified pectin with a 60.36% methyl-esterification degree and a relative weight-average molecular weight (Mw) of 1.30 × 106 Da. The backbone of FAOP was composed of a 2:3 molar ratio of →4)-α-GalpA-(1→ and →4)-α-GalpA-6-O-methyl-(1→ linkage, which contained an ∼57.04% linear homogalacturonan (HG) structural domain. In addition, neutral sugar side chains, such as arabinan and galactan belonging to the rhamnogalacturonan I (RG-I) region, were identified. Subsequently, the effects of Ca2+ on the properties of oil-in-water emulsions were investigated by droplet size, zeta potential, rheological properties and emulsion stability. Results indicated that FAOP formed a solid-like gel emulsion and exhibited excellent emulsion stability when the Ca2+ concentration was 5 mM. At this concentration, the droplet size was the smallest, the backscatter signal (BS) was almost unchanged; the Turbiscan stability index (TSI) value was the lowest, and tanδ (G"/G′) was less than 1. These findings indicated that the improved emulsion stability of FAOP by the introduction of Ca2+ was related to the emulsion gel network structure. These results indicated the potential application of Fructus aurantii pectin as a food stabiliser and thickener.

Dual Site-Selective Substitution Strategy Achieving Anionic Redox Activity and Solid-Solution Reaction in P2-Type Cathode Materials

P2-type Na0.67Ni0.33Mn0.67O2 has been considered as the potential cathode for sodium-ion batteries. However, its practical application is plagued by Na+/vacancy ordering, harmful phase transition, and lattice oxygen loss. Herein, we develop a dual site-selective substitution strategy to fabricate a P2-type Na0.63Ca0.05(Ni0.26Li0.07Mn0.67)O2 cathode. The substitution of Li+ for Ni2+ introduces lone pair oxygen via forming a Li–O–Li configuration and make O 2p close to its Fermi level due to the weakened TM–O (TM: transition metal) bond, which triggers the anionic redox for charge compensation, while the introduction of Ca2+ in a Na layer enhances the electrostatic cohesion of neighboring TM layers by forming a strengthened O–Ca–O configuration, which suppresses the glide of adjacent TM layers and reduces the excessive lattice oxygen loss. Therefore, with a dual site-selective substitution strategy, the P2-type Na0.63Ca0.05(Ni0.26Li0.07Mn0.67)O2 cathode can suppress the Na+/vacancy ordering, P2–O2 phase transition, and lattice oxygen loss even at a potential of 4.35 V, achieving a reversible anionic redox and solid-solution reaction. The P2-type Na0.63Ca0.05(Ni0.26Li0.07Mn0.67)O2 cathode exhibits high discharge capacity (142.7 mA h g–1 at 20 mA g–1), excellent rate capability (57.1 mA h g–1 at 2 A g–1), and cyclic stability (a capacity retention of 83.2% after 700 cycles).

Effervescent cannabidiol solid dispersion-doped dissolving microneedles for boosted melanoma therapy via the “TRPV1-NFATc1-ATF3” pathway and tumor microenvironment engineering

BackgroundConventional dissolving microneedles (DMNs) face significant challenges in anti-melanoma therapy due to the lack of active thrust to achieve efficient transdermal drug delivery and intra-tumoral penetration.MethodsIn this study, the effervescent cannabidiol solid dispersion-doped dissolving microneedles (Ef/CBD-SD@DMNs) composed of the combined effervescent components (CaCO3 & NaHCO3) and CBD-based solid dispersion (CBD-SD) were facilely fabricated by the “one-step micro-molding” method for boosted transdermal and tumoral delivery of cannabidiol (CBD).ResultsUpon pressing into the skin, Ef/CBD-SD@DMNs rapidly produce CO2 bubbles through proton elimination, significantly enhancing the skin permeation and tumoral penetration of CBD. Once reaching the tumors, Ef/CBD-SD@DMNs can activate transient receptor potential vanilloid 1 (TRPV1) to increase Ca2+ influx and inhibit the downstream NFATc1-ATF3 signal to induce cell apoptosis. Additionally, Ef/CBD-SD@DMNs raise intra-tumoral pH environment to trigger the engineering of the tumor microenvironment (TME), including the M1 polarization of tumor-associated macrophages (TAMs) and increase of T cells infiltration. The introduction of Ca2+ can not only amplify the effervescent effect but also provide sufficient Ca2+ with CBD to potentiate the anti-melanoma efficacy. Such a “one stone, two birds” strategy combines the advantages of effervescent effects on transdermal delivery and TME regulation, creating favorable therapeutic conditions for CBD to obtain stronger inhibition of melanoma growth in vitro and in vivo.ConclusionsThis study holds promising potential in the transdermal delivery of CBD for melanoma therapy and offers a facile tool for transdermal therapies of skin tumors.

Effects of Ca-Compounds on the Gases Formation Behavior during Molten Salts Thermal Treatment of Bio-Waste

Bio-waste utilization is essential, and pyrolysis is a prominent way for its effective utilization. However, the gradual accumulation of ash compounds in the intermediate products probably affects the thermal conversion characteristics of bio-waste. In the present study, beech wood and disposable chopsticks were selected as bio-waste samples. The effects of typical ash components (Ca-compounds) on volatile formation behavior were investigated during the molten salts thermal treatment of bio-waste. Results demonstrated that about 80% mass of initial bio-waste was gasified into the volatiles at 300 °C. The introduction of Ca-compounds in the molten salts slightly decreased the total yield of gaseous products. More specifically, Ca2+ could improve the generation of CO2 and suppress the generation of other gases (CO, H2, and CH4), and this is accompanied by a reduction in the low heating value (LHV) of the gases. The possible reason is that Ca2+ might act on the -OH bonds, phenyl C-C bond, methoxy bond and carboxylic acid -COOH bonds of the bio-waste to promote CO2 release. In contrast, the introduction of CO32− and OH- tended to relieve the inhibition effect of Ca2+ on the generation of H-containing gases. Meanwhile, the introduction of Ca2+ can promote the conversion of bio-waste into liquid products as well as increase the saturation level of liquid products. Moreover, as a vital form of carbon storage, CO2 was found to be abundant in the pyrolysis gases from molten salts thermal treatment of bio-waste, and the concentration of CO2 was much higher than that of direct-combustion or co-combustion with coal. It’s a promising way for bio-waste energy conversion as well as synchronized CO2 capture by using molten salts thermal treatment, while the introduction of small amounts of Ca-compounds was found to have no significant effect on the change of CO2 concentration.

Time-dependent analysis of polysaccharide fouling by Hermia models: Reveal the structure of fouling layer

The Hermia fouling models are often applied in interpreting filtration data to reveal the fouling mechanisms. However, the application of these models is arbitrary and lacks in-depth analysis. In this study, time-dependent Hermia models with forward and reverse processing were employed for the first time to analyze the membrane fouling mechanism and fouling layer structure determined by polysaccharide in dead-end and cross-flow filtration. The applicability of Hermia classic and mass-transfer models was also investigated. Results showed that in cross-flow filtration, the Hermia classic model is more suitable for processing the filtration data with Ca2+ and the Hermia mass-transfer model is more appropriate for fitting the experiment result caused by Mg2+ owning to the differences in affinity of Ca2+ and Mg2+ to polysaccharide. Fitting results further manifested that the differences in concentration could obviously affect structure of polysaccharide fouling layer, and the introduction of Ca2+ and/or Mg2+ changed the spatial conformation and compactness of fouling layer. These results suggested that Hermia fouling models can provide insightful analysis of the fouling layer structure from micro-level to interpret the fouling mechanisms. The influence of cation concentration and type on membrane fouling can be revealed by the processing of Hermia models. In short, time-dependent forward and reverse processing of Hermia classic and mass-transfer models could preliminarily explain the membrane fouling behavior and structure of fouling layer. This work suggests that the Hermia fouling models are more useful than we thought and the time-dependent application of them could provide deep insights into fouling development.

Fabrication of calcium/cupric crosslinked alginate electrospun nanofibers for enhancing fluoroquinolones adsorption

Fluoroquinolones (FQs) in the environment have posed a threat to the ecosystem and human health. The development of efficient and economical materials for the removal of FQs provides an alternative answer to the issue. Herein, calcium and cupric crosslinked alginate nanofibers (SA-Ca/Cu) were prepared by fabrication of electrospun SA nanofibers, followed by crosslinking with CaCl2 and CuCl2. The introduction of Ca2+ and Cu2+ to crosslink the SA nanofibers not only endows the SA-Ca/Cu nanofibers with water resistance but also provides abundant binding sites to interact with FQs. The SA-Ca/Cu nanofibers are a mesoporous material with the Brunauer-Emmett-Teller surface area of 23.7 m2 g−1, and a pore diameter of 25.5 nm. The adsorption isotherms data of SA-Ca/Cu toward FQs were well fitted to the Langmuir model and the kinetics were well described by the general-order model. The maximum adsorption capacities of SA-Ca/Cu toward sparfloxacin, ciprofloxacin, and enrofloxacin were calculated to be 285.0, 338.1, and 375.0 mg g−1, respectively. In addition, the adsorption thermodynamics was investigated to help understand the adsorption process. Furthermore, the excellent removal efficiency of the SA-based nanofibers toward FQs from mineral and river water samples, as well as the simulated effluents demonstrates that the natural biomaterial-based mesoporous materials are effective, economical, and potential adsorbents for treating real effluents containing FQs.

A study of the impact of oxygen vacancies on the VUV efficiency of rare-earth doped YBO3 via Ca2+ co-doping

Vacuum ultraviolet excitation and reflectance spectroscopy were used to study doped yttrium borate phosphors with composition Y1-x-yBO3:REy, Cax up to x = 0.10 and up to y = 0.06 (Eu3+ or Tb3+). These data were used to estimate host-to-activator energy transfer efficiencies. The introduction of Ca2+ leads to the formation of oxygen vacancies, VO●●, that act as energy traps. We find that the introduction of these defects lowers the transfer efficiency to both dopants, with Eu3+ being impacted more than Tb3+. The results are discussed in terms of the energies of dopant states relative to band states, and the difference in trapping mechanisms between the two rare earth ions.