Highly luminescent carbon dots (C-dots) were synthesized by the one-pot simple hydrothermal method directly from lemon juice using different temperatures, time, aging of precursors, and diluted ...solvents to control the luminescence of C‐dots. The obtained C-dots were characterized by high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectrophotometry, dynamic light scattering, ultraviolet-visible spectrophotometry, and photoluminescent spectrophotometry. The results show that C‐dots had strong green light emission with quantum yield in the range of 14.86 to 24.89% as a function of hydrothermal temperatures. Furthermore, light emission that is dependent on hydrothermal time, aging of precursor, and diluted solvent was observed. These results suggest that the C‐dots have potential application in optoelectronics and bioimaging.
In this work, low-temperature hydrothermal synthesis of a series of
x
Mo-1%Er-10%Yb (
x
:mol%) doped hydroxyapatite (HA) phosphors was studied. The single phase of hexagonal structure HA nanorods ...obtained with high crystallinity was verified using characterization techniques such as XRD and HRTEM + SAED. It was found that the presence of the orientation associated with near to the {210} planes of the HA phase was favored with the increase of the Mo
6+
doping content and different hydrothermal reaction times. The Mo
6+
doped HA:Er-Yb phosphor showed an energetic green UC emission band (520/550 nm) and weak red UC emission band (655 nm) attributed to (
2
H
11/2
,
4
S
3/2
)-
4
I
15/2
,
4
F
9/2
-
4
I
15/2
transition of the Er
3+
ion, respectively, under 975 nm laser excitation. Notably, the green emission intensity of the Mo
6+
doped phosphor is 70 times higher than that of the samples without doped Mo
6+
content. The high efficiency of the green UC can be attributed to the novel energy transfer process from the |
2
F
7/2
,
3
T
2
〉 state of the Yb
3+
-MoO
4
2−
dimer to the
4
F
7/2
of the Er
3+
ions. The results from fitting the theoretical model to the experimental luminescence decay curves of the undoped and doped samples showed that the decay time of green emission of the sample doped with Mo
6+
ions (329 μs) is longer than that of the undoped sample (299 μs), which confirms the presence of the Yb
3+
-MoO
4
2−
dimer in the system. Moreover, the grain orientations due to the effect of Mo
6+
ions doped in the HA phosphor could favor the enhancement of the UC emission intensity. The UC mechanism of Mo
6+
doped HA:Er-Yb was determined to be three (green band) and two photon (red band) absorption processes. The results suggest that the HA:Er-Yb-Mo phosphor could have potential in solar cell and biomedical applications.
In this work, low-temperature hydrothermal synthesis of a series of
x
Mo-1%Er-10%Yb (
x
:mol%) doped hydroxyapatite (HA) phosphors was studied.
•Dual-mode intense green emission of HA/β-TCP: Er-Yb-Mo composite synthesized by hydrothermal method.•Mo6+ doped system enhances strongly both UC and DC green emissions.•Dual-mode mechanism of ...HA/β-TCP:Er-Yb-Mo phosphor has explained.•Good temperature sensing property was obtained.
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This work presents a novel multifunctional material synthesized by hydroxyapatite/ β-tricalcium phosphate (HA/β-TCP) doped with Er-Yb-Mo ions (using hydrothermal method) and its characterization, showing a peculiar property of green dual-mode emissions (up and down-conversions). It was found that the obtained material exhibits an intense green emission (510–560 nm) both via up-conversion (excited by 975 nm) and down-conversion (excited by 379 nm), which depend on the Mo6+ contents. Particularly, compared with the free-Mo6+ sample, the green emission intensities of the samples doped with 5% Mo6+ mol are 50 and 35 times higher for UC and DC emissions, respectively. Furthermore, the temperature sensing property of the HA/β-TCP: Er-Yb-Mo composite is investigated by fluorescence intensity ratio (FIR) technique, showing a high and competitive sensitivity with a maximum value of 0.0064 K−1 at 403 K. The results indicated that the HA/β-TCP: Er-Yb-Mo phosphor can be useful for high-temperature-sensing applications.
Freshwater ecosystem services are negatively affected by factors such as climate change (e.g. changes in temperature, precipitation, and sea level rise) and human interventions (e.g. agriculture ...practices, impoundment of dams, and land use/land cover change). Moreover, the potential synergic impacts of these factors on ecosystems are unevenly distributed, depending on geographical, climatic and socio-economic conditions. The paper aims to review the complex effects of climatic and non-climatic drivers on the supply and demand of freshwater ecosystem services. Based on the literature, we proposed a conceptual framework and a set of indicators for assessing the above-mentioned impacts due to global change, i.e. climate change and human activities. Then, we checked their applicability to the provisioning services of two well-known case studies, namely the Po River basin (Italy) and the Red River basin (Vietnam).
To define the framework and the indicators, we selected the most relevant papers and reports; identified the major drivers and the most relevant services; and finally summarized the fundamental effects of these drivers on those services. We concluded that the proposed framework was applicable to the analyzed case studies, but it was not straightforward to consider all the indicators since ecosystem services were not explicitly considered as key assessment endpoints in these areas. Additionally, the supply of ecosystem services was found to draw much more attention than their demand. Finally, we highlighted the importance of defining a common and consistent terminology and classification of drivers, services, and effects to reduce mismatches among ecosystem services when conducting a risk assessment.
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•We assessed the impacts of climate change and human activities on freshwater services.•Indicators and a conceptual framework of climatic/non-climatic effects are analyzed.•The literature focuses more on the provisioning and regulating services.•Consistent terminologies and classifications are needed for future risk assessments.
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•Bayesian Network is applied to analyze ecosystem services under different scenarios.•Precipitation resulted as the main driver of changes in the water yield.•Nutrient retention is ...mainly driven by land use variation.•“Win-win” water management strategies are required to maintain ecosystem services.•The approach represents an operational tool for integrated water management.
Freshwater ecosystems are negatively affected by climate change and human interventions modifying together supply and demand of ecosystem services (ES). Research on ES focused on assessing risks arising from the interaction among both stressors, integrating empirical data with expert knowledge. This work aims at incorporating Bayesian Networks (BN) approaches into ES appraisal, identifying key factors driving changes and trade-offs among ES potential under different scenarios. Applying the designed BN to the Taro River basin (TRB) in Italy, the outcomes showed a limited space to improve ES potential, as well as trade-offs between water yield and nutrient retention services due to changes in precipitation and land use patterns. Moreover, the analysis of key input variables highlighted that precipitation is the main driver affecting provisioning services while land use for the regulating ones. The results imply a low capacity to provide services in the medium term for the TRB where water was exploited for multiple competing objectives. Therefore, “win-win” spatial planning and water management strategies are needed to improve freshwater ES potential. The designed BN model represents a valuable decision support tool to quickly perform ES assessment and to identify the most suitable management plan to maintain benefits from freshwater ecosystems.
Polymer-derived ceramic environmental barrier coatings (EBCs) in combination with active fillers are highly attractive due to their facile processing and applicability at elevated temperatures. In ...this study, several kinds of active and passive fillers were added to polymer-derived ceramics and then coated onto carbon steel, using cheap and simple lacquer methods (such as dip or spray coating). The resultant coating, investigated by Thermal Gravimetric Analysis (TGA), Scanning Electron Microscopy with X-ray microanalysis (SEM/EDS), X-ray Diffraction (XRD), adhesion tests and oxidation tests, showed that it acted as an excellent film to withstand thermal cycling, and prevented carbon steel from being oxidized at elevated temperatures. The low-cost and effective coating method described in this paper can be used widely to protect carbon steel used at high temperatures (e.g. steel boiler tubes in waste-to-energy plants).
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•Microporous Ti surface with aligned pores was synthesized successfully by electrochemical method.•Microporous Ti with aligned pore structure was controlled by electrochemical ...currents.•Microporous Ti promoted cell attachment and preferential growth on the aligned pores.
This paper reports the synthesis of microporous Ti surfaces with aligned pores by applying a different current during electrochemical process for application in cell-surface interaction study and biomedical implants. As the microporous Ti surfaces were synthesized by current from (0.5–4)A, the microstructure of the Ti surfaces was shifted from a relative smooth to microporous one that was observed to have an aligned pore surface. Optical images showed that the micropore sizes in ∼(85.4–224.4)µm. The roughness of the microporous Ti was significantly higher than that of the Ti by a factor of approximately 5 to 7. Confocal laser scanning microscope showed excellent cell attachment and preferential growth on the microporous Ti with aligned channels after 72 h of culturing which could be important for cell-surface interactions study and biomedical implants.
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•Integrated risk assessment of climate and land use changes on ecosystem services.•Comparing to land use change, climate change has a greater effect on water yield.•Nutrient ...retentions are more sensitive to land use change than climate change.•Useful insights for water resources management and climate adaptation are provided.
Climate and land-use changes are posing increasing threats to freshwater-related ecosystem services, acting both on the supply and the demand side. A better understanding of the dynamics of these potential services, driven by the interactions between the factors mentioned above, could bring benefits to water resources management, the environment, and human well-being. In this work, we developed an integrated modeling approach to assess the conjoined impacts of land-use and climate changes on the potential ecosystem services (i.e. water yield and nutrients retention) until 2050. This approach was applied to the Taro River basin in Italy.
Firstly, the results showed a 20% reduction in water yield was driven mainly by the increases in evapotranspiration demand and changes in rainfall patterns. Furthermore, a mean decrease of approximately 3% of the total nitrogen retention and a mean increase of 3% for the total phosphorus retention could be mainly attributed to land-use changes. Secondly, the rate of change would be different over time with the most pronounced differences between 2020 and 2030 and slower variations afterward. Finally, the obtained results could be a valuable support to identify and prioritize the best management practices for sustainable water use, balancing the tradeoffs among services.
In this paper, a novel material based on Er-Yb-Mo tri-doped HA/β-TCP phosphor for intense green up-conversion (UC) emission was successfully synthesized by solid-state reaction method. X-ray ...diffraction (XRD) measurements verified that the materials including a trace amount of HA phase has a hexagonal structure and main β-TCP phase has a rhombohedral structure, which is controlled by the doped ions. Under excitation wavelength of 976 nm laser diode, the HA/β-TCP:Er-Yb-Mo phosphor showed strong green UC emission band at 520/556 nm and weak red emission band at 656 nm which are attributed to (2H11/2, 4S3/2) - 4I15/2, 4F9/2 - 4I15/2 transition of the Er3+ ion, respectively. Remarkably, compared with the sample without Mo6+, the green emission intensities increased ∼650 times was achieved by using Er3+-Yb3+-Mo6+ doped phosphor. The high efficiency of the UC can be attributed to novel energy transfer process from |2F7/2, 3T2> state of Yb3+ - MoO42− dimer to the 4F7/2 of Er3+ ions. Moreover, the grain orientations due to the effect of Mo6+ ions doped in β-TCP phosphor could play an important role in the enhancement of UC emission intensity. These results indicate that the HA/β-TCP: Er-Yb-Mo phosphor has potential application in biological imaging and medicine.
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•Novel upconversion material (Er-Yb-Mo tri-doped HA/β-TCP phosphor) was facilely synthesized by solid-state reaction method.•The crystalline single – phase of β-TCP was achieved by doping with Mo6+ ions.•The green emission intensity of the sample doped with Mo was 650 times higher compared with the sample without Mo.•The selective green upconversion emission can be controlled by controlling the doping Mo6+ concentration in HA/β-TCP: Er3+-Yb3+.
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