Competition and Neutralization: Thermally Induced Crystallization and Phase Evolution of Amorphous Calcium Phosphate with Cosubstitution of Larger and Smaller Divalent Cations.

The presented study evaluated the effect of cosubstitution of larger and smaller divalent cations on the thermally induced crystallization of amorphous calcium phosphate (ACP). The predesigned combinations of larger (Sr2+ and Ba2+) and smaller (Mg2+, Cu2+, and Co2+) divalent cations were carried out and their effects on the thermodynamic equilibrium between α/ß-tricalcium phosphate (TCP) were outlined. The coexistence of larger and smaller divalent cations shielded the formation of α-TCP and shifted the thermodynamic equilibrium toward the ß-TCP, which implied that the smaller cations dominated the crystalline phase. However, the retarded crystallization induced by the larger cations still remained and allowed ACP to maintain its amorphous nature partly or completely until a higher temperature.

Quantifying the contribution of ecological water replenishment on aquifer recovery using a refined groundwater model.

Due to its independent control and directly easy operation, ecological water replenishment (EWR) has been an important measure for restoring river ecosystems. However, the positive and negative contribution of the EWR activities to aquifer system are not fully understood under the combined influences of climate change and human activities across time scales. A refined groundwater flow model integrating an open channel flow at daily time scales is developed in a part of Northern China Plain to reproduce the dynamic process of groundwater level changes. After model calibration with groundwater level and runoff data, the changes of simulated groundwater level and river runoff have the Nash-Sutcliffe efficiency coefficient of 0.98 and 0.60, respectively. Results clearly demonstrate that the impulse response of aquifer recovery to runoff in three centralized EWRs. By using with and without EWR method, the simulated maximum contribution of EWR near river to aquifer recovery may be over 70 %. Scenario analysis method considering different precipitation, groundwater exploitation reduction and EWR activities are applied to evaluate the total quantities of aquifer recovery. The prediction of nine-year EWR activities under multiple scenarios shows that the increased groundwater level generally varies from 4.08 to 8.57 m, and the contribution of EWR accounts for 7.88 %-36.59 %. It is also noticed that 14 out of the 18 informal landfill sites will face potential groundwater pollution risks, indicating the negative influences of long-term EWR activities. This study can provide a method for quantifying the influences and contribution of EWR on aquifer recovery and can be referred to as a guideline for EWR evaluation with similar hydrogeological conditions.

Upconverted persistent luminescent Zn3Ga2SnO8: Cr3+, Yb3+, Er3+ phosphor for composite anti-counterfeiting ink.

Herein, a novel colorless anti-counterfeiting luminous ink composite material, to the best of our knowledge, was prepared by incorporating upconverted persistent luminescent Zn3Ga2SnO8:1%Cr3+, 5%Yb3+, 0.5%Er3+ (ZGSO: Cr,Yb,Er) phosphors into a resin solution, followed by stirring. Owing to its small particle size and uniform distribution, ZGSO: Cr, Yb, Er exhibits long-lasting, persistent near-infrared emission at 696 nm following the stoppage of excitation by a 274 nm ultraviolet light and a 980 nm excitation. ZGSO: Cr, Yb, Er composites were prepared and exhibited characteristic peaks corresponding to upconversion and an afterglow curve following excitation at 980 nm. With various special luminescent modes, sharp emission peaks, and emission intensity varying over time, the emission light of composite ink is easy to detect and not easily confused. Furthermore, the prepared composite ink can be calligraphic, visualized, and observable, and has good light-emitting performance following UV excitation. Our work provides a meaningful way to fabricate multifunctional anti-counterfeiting luminous ink composites with an intense persistent luminescence for use in anti-counterfeiting signs, inspection imaging, and other complex industrial applications.

Auditory Discrimination Elicited by Nonspeech and Speech Stimuli in Children With Congenital Hearing Loss.

PURPOSE: Congenital deafness not only delays auditory development but also hampers the ability to perceive nonspeech and speech signals. This study aimed to use auditory event-related potentials to explore the mismatch negativity (MMN), P3a, negative wave (Nc), and late discriminative negativity (LDN) components in children with and without hearing loss. METHOD: Nineteen children with normal hearing (CNH) and 17 children with hearing loss (CHL) participated in this study. Two sets of pure tones (1 kHz vs. 1.1 kHz) and lexical tones (/ba2/ vs. /ba4/) were used to examine the auditory discrimination process. RESULTS: MMN could be elicited by the pure tone and the lexical tone in both groups. The MMN latency elicited by nonspeech and speech was later in CHL than in CNH. Additionally, the MMN latency induced by speech occurred later in the left than in the right hemisphere in CNH, and the MMN amplitude elicited by speech in CHL produced a discriminative deficiency compared with that in CNH. Although the P3a latency and amplitude elicited by nonspeech in CHL and CNH were not significantly different, the Nc amplitude elicited by speech performed much lower in CHL than in CNH. Furthermore, the LDN latency elicited by nonspeech was later in CHL than in CNH, and the LDN amplitude induced by speech showed higher dominance in the right hemisphere in both CNH and CHL. CONCLUSION: By incorporating nonspeech and speech auditory conditions, we propose using MMN, Nc, and LDN as potential indices to investigate auditory perception, memory, and discrimination.

Blue LED-pumped intense short-wave infrared luminescence based on Cr3+-Yb3+-co-doped phosphors.

The growing demand for spectroscopy applications in the areas of agriculture, retail and healthcare has led to extensive research on infrared light sources. The ability of phosphors to absorb blue light from commercial LED and convert the excitation energy into long-wavelength infrared luminescence is crucial for the design of cost-effective and high-performance phosphor-converted infrared LEDs. However, the lack of ideal blue-pumped short-wave infrared (SWIR) phosphors with an emission peak longer than 900 nm greatly limits the development of SWIR LEDs using light converter technology. Here we have developed a series of SWIR-emitting materials with high luminescence efficiency and excellent thermal stability by co-doping Cr3+-Yb3+ ion pairs into Lu0.2Sc0.8BO3 host materials. Benefitting from strong light absorption of Cr3+ in the blue waveband and very efficient Cr3+→Yb3+ energy transfer, the as-synthesized Lu0.2Sc0.8BO3:Cr3+,Yb3+ phosphor emits intense SWIR light in the 900-1200 nm from Yb3+ under excitation with blue light at ~460 nm. The optimized phosphor presents an internal quantum yield of 73.6% and the SWIR luminescence intensity at 100 °C can still keep 88.4% of the starting value at 25 °C. SWIR LED prototype device based on Lu0.2Sc0.8BO3:Cr3+,Yb3+ phosphor exhibits exceptional luminescence performance, delivering SWIR radiant power of 18.4 mW with 9.3% of blue-to-SWIR power conversion efficiency and 5.0% of electricity-to-SWIR light energy conversion efficiency at 120 mA driving current. Moreover, under the illumination of high-power SWIR LED, covert information identification and night vision lighting have been realized, demonstrating a very bright prospect for practical applications.

Enhancing the understanding of hydrological responses induced by ecological water replenishment using improved machine learning models: A case study in Yongding River.

The ecological water replenishment (EWR) of Yongding River has been an important project implemented in response to the Development of an Ecological Civilization policy in China since 2016. A reasonable amount of EWR requires a systematic understanding of the relationship among the surface water, groundwater, ecology and economy. However, studying surface water-groundwater interactions still remains an important issue. Thus, a coupled model integrating a Muskingum method-based open channel flow model and machine learning-based groundwater model is developed to describe the dynamic changes in streamflow and groundwater level in response to the EWR of Yongding River. The model is calibrated using observed streamflow data as well as groundwater level data on a daily scale for the spring EWR in 2020. The simulated results match well with the observed data and suggest that significant groundwater level increases occur only around the main channel of Yongding River. Fifteen scenarios under different EWR schemes are set to obtain reasonable streamflow during EWR, and then the responses of streamflow and groundwater level changes are simulated. Reasonable streamflow at the Guanting Reservoir need to be above 65 m3/s to ensure the streamflow can pass through Beijing and significant groundwater level recoveries of 170 million m3 through EWR. The developed models can improve the understanding of the interaction between surface water and groundwater and provide a quick assessment of the factors influencing the different EWR schemes and thus aid in effective EWR project management.

Color modification of ZnGa2O4:Yb3+,Er3+,Tm3+ upconversion phosphors with the doping of Sn4+ and Ge4+ ions.

Upconversion phosphors Zn3Ga2SnxGe1-xO8:Yb3+,Er3+,Tm3+ were prepared by solid-state reaction with a subsequent thermal treatment at 1300°C. Under the excitation of a 980 nm laser, all phosphors produced blue emission at 477 nm, green emissions at 526 nm and 549 nm, and red emissions at 659 nm and 694 nm. The doping of Sn4+ ions and Ge4+ ions had no effect on the positions of upconversion emission peaks. However, the emission intensity changed in different degrees with different doping ions in the matrix. According to the basic theory of color-light, it is known that the color-light can be obtained by mixing a definite ratio of red, green, and blue emissions. Specifically, in the 980 nm light excitation, ZGO:Yb,Er,Tm phosphors show purplish pink luminescence, while ZGSO:Yb,Er,Tm show greenish blue luminescence, ZGGO:Yb,Er,Tm show purplish blue luminescence, and ZGGSO:Yb,Er,Tm show blue luminescence. In other words, doping Sn4+ ions can move upconversion luminescence toward the green region, while doping Ge4+ ions bend it toward the blue region. Adjusting the doping of Sn4+ ions and Ge4+ ions can obviously change the upconversion luminescent color. Besides, the upconversion luminescence of all as-prepared phosphors is visible to the naked eye without additional optical instruments.

Up-conversion Persistent Luminescence of a 980 nm Laser Activated Zn3Ga2(GexSn1-x)O8:Yb,Er,Cr Phosphors.

Zn3Ga2(GexSn1-x)O8:Yb,Er,Cr phosphors with different doping ratio of Ge/Sn were prepared by high temperature solid-state method. After excited at 270 nm with a xenon lamp for 15 min, the persistent luminescence (PL) of Zn3Ga2(GexSn1-x)O8:Yb,Er,Cr phosphor can last more than 60 min. Under the excitation at 980 nm, Zn3Ga2(GexSn1-x)O8:Yb,Er,Cr phosphors can generate effective up-conversion emissions from Er3+ ions at 410 nm, 525 nm, 550 nm, 660 nm and Cr3+ ions around 700 nm. Besides, after ceasing irradiation, Zn3Ga2(GexSn1-x)O8:Yb,Er,Cr phosphors show up-conversion persistent luminescence (UCPL) from Cr3+ ions around 700 nm. Moreover, Zn3Ga1.995(Ge0.3Sn0.7) O8:Yb3+,Er3+,Cr3+ phosphor is optimal with the best persistent luminescent and up-conversion persistent luminescent properties. In short, owing to the long afterglow time, strong up-conversion emissions and novel up-conversion persistent luminescence, the as-prepared Zn3Ga2(GexSn1-x)O8:Yb,Er,Cr phosphors can be potentially applied in a wide range of fields, such as security materials, coating materials, infrared detection, fluorescent label, tracer and testing.

A Nonenzymatic Glucose Sensor Platform Based on Specific Recognition and Conductive Polymer-Decorated CuCo2O4 Carbon Nanofibers.

CuCo2O4 decoration carbon nanofibers (CNFs) as an enzyme-free glucose sensor were fabricated via electrospinning technology and carbonization treatment. The CNFs with advantages of abundant nitrogen amounts, porosity, large surface area, and superior electrical conductivity were used as an ideal matrix for CuCo2O4 decoration. The resultant CuCo2O4-CNF hybrids possessed favorable properties of unique three-dimensional architecture and good crystallinity, accompanied by the CuCo2O4 nanoparticles uniformly growing on the CNF skeleton. To further enhance the selective molecular recognition capacity of the developed sensor, a conductive film was synthesized through the electropolymerization of thiophene and thiophene-3-boronic acid (TBA). Based on the synergistic effects of the performances of CNFs, CuCo2O4 nanoparticles, and boronic acid-decorated polythiophene layer, the obtained poly(thiophene-3-boronic acid) (PTBA)/CuCo2O4-CNF-modified electrodes (PTBA/CuCo2O4-CNFs/glassy carbon electrode (GCE)) displayed prominent electrocatalytic activity toward electro-oxidation of glucose. The fabricated sensor presented an outstanding performance in the two linear ranges of 0.01-0.5 mM and 0.5-1.5 mM, with high selectivity of 2932 and 708 µA·mM-1·cm-2, respectively. The composite nanofibers also possessed good stability, repeatability, and excellent anti-interference selectivity toward the common interferences. All these results demonstrate that the proposed composite nanofibers hold great potential in the application of constructing an enzyme-free glucose sensing platform.

Properties of reduced graphene/carbon nanotubes reinforced calcium phosphate bone cement in a microwave environment.

In this work, the setting process of reduced graphene (RGO)/carbon nanotubes (CNTs) reinforced calcium phosphate cement (CPC) were conducted in a microwave environment. The introduction of microwave can increase the reaction temperature, speed up the vibration of water molecules and eliminate bubbles from the interface between RGO, CNTs and the substrate. Comparing with CPC without microwave treatment, the final setting time of composites after microwave treatment are almost a half, the flexural strength and the compressive strength are increased by 19.86% and 21.68% respectively, which are 17.38 MPa and 104.52 MPa. Meanwhile, the CPC composites remain the excellent bioactivity.

Enhanced Up-Conversion Emission in Al3+ Co-Doped ZnGa2O4:Yb3+,Tm3+ Powder Phosphors.

Yb3+-Tm3+ co-doped up-conversion powder phosphors using Zn(AlxGa1-x)2O4 (ZAGO) as the host materials were synthesized via solid-state reaction successfully. In addition, the morphology, structural characterization and up-conversion luminescent properties were all investigated by scanning electron microscope (SEM), x-ray diffraction (XRD) and fluorescence spectrophotometer (F-7000), respectively. Under the excitation of a 980 nm laser, all as-prepared powders can carry out blue emission at about 477 nm (corresponding to 1G4 â†’ 3H6 transition of Tm3+ ions), and red emission at about 691 nm (attributed to 3F3 â†’ 3H6 transition of Tm3+ ions). Also, the influence of doping Al3+ ions were investigated. In brief, the doping of Al3+ ions has no effect on the position of emission peak. Howbeit the up-conversion efficiency and intensity of ZAGO:Yb,Tm phosphors are stronger than ZGO:Yb,Tm and ZAO:Yb,Tm phosphors, while the crystallinity is the opposite. More particularly, all as-prepared powder phosphors emit strong luminescence, which is observable by the naked eye, demonstrating the potential applications in luminous paint, luminescent dye, etc.

Sol-gel Synthesis and Upconversion Luminescent Properties of Yb3+,Er3+,Eu3+ Triply-Doped in YVO4 Phosphors.

Yb3+,Er3+,Eu3+ triply-doped in YVO4 with varying molar ratio of Er/Eu were synthesized in a sol-gel method with a subsequent heat treatment for the first time. The optimal molar ratio of Er/Eu for the maximum energy transfer efficiency was 1/39. After molar ratio, the influences of different heat treatment temperatures were also researched and the maximal heat temperature was 1300 °C. Besides, the properties of YVO4:Yb3+,Er3+,Eu3+ upconversion phosphors were investigated by X-ray diffraction, scanning electron microscopy and photo luminescent spectra, respectively. In sum, XRD results indicate the crystal structure of as-prepared samples, which is the tetragonal phase of YVO4 with no other diffraction peaks. SEM images show the morphology of as-prepared samples, which are granular-like nanoparticles. PL spectra demonstrate the upconversion luminescence of as-prepared samples, which emit strong green lights (at 525 nm, 550 nm) and slight red lights (at 590 nm, 615 nm, 695 nm) under the NIR irradiation at 980 nm. Two strong green emissions are attributed to the 2H11/2→4I15/2 and 4S3/2→4I15/2 transitions of Er3+ ions. Meanwhile, three slight red emissions are attributed to the 5D0→7F1, 5D0→7F2 and 5D0→7F4 transitions of Eu3+ ions. All in all, the colorful emissions endow YVO4:Yb3+,Er3+,Eu3+ phosphors great potential for some applications, such as display devices, bio-labeling and infrared detection.

Upconversion photoluminescence of core-shell structured SiO2@YVO4:Yb3+, Er3+, Eu3+ nanospheres.

Core-shell structured SiO2@YVO4:Yb3+, Er3+, Eu3+ nanospheres were prepared by a simple solgel method followed by a subsequent heat treatment. The as-prepared composites were characterized by a scanning electron microscope, high-resolution transmission electron microscope, x-ray diffraction, and photoluminescence spectra. The influences of different coating numbers were also studied. To sum up, the composites are spherical shaped with an average diameter of 200 nm, and the YVO4:Yb3+, Er3+, Eu3+ luminescent particles are successfully coated on the surface of SiO2 nanospheres. Under the near-infrared irradiation at 980 nm, the composites can emit strong green lights (at 525 nm, 550 nm) attributed to the H11/22→I15/24, S3/24→I15/24 transitions of Er3+ ions, and slight red lights (at 590 nm, 620 nm) attributed to the D05→F17, D05→F27 transitions of Eu3+ ions. Given the above, due to the regular core-shell structure, the uniform distribution of nanoparticles, and the colorful emissions, the SiO2@YVO4:Yb3+, Er3+, Eu3+ nanospheres may have great potential for some biological applications, such as biological tracers, bio-labeling, and so on.

Red/near-infrared/short-wave infrared multi-band persistent luminescence in Pr3+-doped persistent phosphors.

Red/near-infrared/short-wave infrared multi-band persistent phosphors are developed by doping Pr3+ into MgGeO3 and CdSiO3 hosts, which emit intense, very-long-lasting (>120 h) persistent luminescence at around 625 nm, 900 nm and 1085 nm after ultraviolet light excitation. The penetration power of these three wavelengths in chicken breast follows the order of 1085 nm > 900 nm > 625 nm.

Long persistent luminescence in the ultraviolet in Pb(2+)-doped Sr2MgGe2O7 persistent phosphor.

We extend the persistent luminescence into the ultraviolet spectral region by developing a new ultraviolet persistent phosphor Sr2MgGe2O7:Pb(2+). The Sr2MgGe2O7:Pb(2+) phosphor exhibits strong persistent luminescence peaking at 370 nm and a long persistence time of >12 h after excitation. The phosphor also exhibits a photo-stimulated persistent luminescence capability.

New function of the Yb3+ ion as an efficient emitter of persistent luminescence in the short-wave infrared.

The trivalent ytterbium (Yb3+) ion has been extensively used as an emitter in short-wave infrared (SWIR) lasers, a sensitizer to activate other lanthanide ions for up-conversion luminescence, and a spectral converter in Ln3+-Yb3+ doubly doped quantum cutting phosphors. Here we report a new function of the Yb3+ ion-as an efficient emitting center for SWIR persistent luminescence. We have developed the first real SWIR persistent phosphor, MgGeO3:Yb3+, which exhibits very-long persistent luminescence at around 1000 nm for longer than 100 h. The MgGeO3:Yb3+ phosphor is spectrally transparent to visible/near-infrared light (~400-900 nm) and is a promising ultraviolet-to-SWIR spectral convertor. The MgGeO3:Yb3+ phosphor also exhibits a photostimulated persistent luminescence capability, where the SWIR persistent emission in an ultraviolet-light pre-irradiated sample can be rejuvenated by low-energy light (white or red light) stimulation. The MgGeO3:Yb3+ phosphor is expected to have promising applications in biomedical imaging, night-vision surveillance and photovoltaics.

Design and construction of polymerized-chitosan coated Fe3O4 magnetic nanoparticles and its application for hydrophobic drug delivery.

In this study, a novel hydrogel, chitosan (CS) crosslinked carboxymethyl-ß-cyclodextrin (CM-ß-CD) polymer modified Fe3O4 magnetic nanoparticles was synthesized for delivering hydrophobic anticancer drug 5-fluorouracil (CS-CDpoly-MNPs). Carboxymethyl-ß-cyclodextrin being grafted on the Fe3O4 nanoparticles (CDpoly-MNPs) contributed to an enhancement of adsorption capacities because of the inclusion abilities of its hydrophobic cavity with insoluble anticancer drugs through host-guest interactions. Experimental results indicated that the amounts of crosslinking agent and bonding times played a crucial role in determining morphology features of the hybrid nanocarriers. The nanocarriers exhibited a high loading efficiency (44.7±1.8%) with a high saturation magnetization of 43.8emu/g. UV-Vis spectroscopy results showed that anticancer drug 5-fluorouracil (5-Fu) could be successfully included into the cavities of the covalently linked CDpoly-MNPs. Moreover, the free carboxymethyl groups could enhance the bonding interactions between the covalently linked CDpoly-MNPs and anticancer drugs. In vitro release studies revealed that the release behaviors of CS-CDpoly-MNPs carriers were pH dependent and demonstrated a swelling and diffusion controlled release. A lower pH value led to swelling effect and electrostatic repulsion contributing to the protonation amine impact of NH3(+), and thus resulted in a higher release rate of 5-Fu. The mechanism of 5-Fu encapsulated into the magnetic chitosan nanoparticles was tentatively proposed.

In vitro and in vivo evaluation of chitosan/ß-glycerol phosphate composite membrane for guided bone regeneration.

Chitosan and ß-glycerol phosphate (CS/ß-GP) composite, with a thermosensitive sol-gel transition behavior, has been tested as one of the viable materials for barrier membrane fabrication. These studies have provided us with a new concept for a guided bone regeneration (GBR) membrane design. The composition, porous structure of the membrane, and the neutral mild preparation procedures make the CS/ß-GP membrane a potentially active guide for bone regeneration. In this study, the CS/ß-GP composite membrane, with different concentrations of ß-GP, was studied to assess their potential utility in GBR application. The initial attachment of the ST2 stromal cell line to the CS/ß-GP composite membrane was better than their attachment to the pure CS membrane. The proliferation and osteoblastic differentiation of the cells were much higher on the CS/ß-GP composite membrane as compared to the pure CS membrane (p < 0.05). A mild inflammatory response was observed around the implanted CS/ß-GP composite membrane without any foreign body reaction that continued up to 4 weeks of postsurgery. This primary study indicated that the in vitro and in vivo bioactivities of the CS/ß-GP composite membrane fulfilled the requirements for GBR technique.