Performance evaluation of a low-cost loess-based filler for bioretention cells.

The sand and gravel fillers used in traditional bioretention cells are expensive and becoming increasingly scarce, and their performance is unstable. It is important to find a stable, reliable, and low-cost alternative filler for bioretention facilities. Using cement as a modified loess filler for bioretention cells is a low-cost and easily obtainable alternative. The loss rate and anti-scouring index of the cement-modified loess (CM) were analyzed under different curing times, cement addition amount, and compactness control conditions. This study found that the stability and strength of the cement-modified loess in water with a density of not less than 1.3 g/cm3, a curing time, of not less than 28 d and a cement addition amount not less than 10% meets the use requirements of the bioretention cell filler. X-ray diffraction and Fourier transform infrared spectroscopy of cement-modified materials with a 10% cement addition and a curing time of 28 days (CM28) and 56 days (CM56). Cement-modified materials with 2% straw and a curing time of 56 days (CS56) showed that the three kinds of modified loess all contain calcium carbonate and that the surface contains hydroxyl and amino functional groups that can effectively remove phosphorus. The specific surface areas of the CM56, CM28, and CS56 samples were 12.53 m2/g, 24.731 m2/g, and 26.252 m2/g, respectively, which are significantly higher than that of sand (0.791 m2/g). At the same time, the adsorption capacity of the ammonia nitrogen and the phosphate that was present in the three modified materials is better than that of sand. CM56, like sand, has rich microbial communities, which can entirely remove nitrate nitrogen in water under anaerobic conditions, indicating that CM56 can be used as an alternative filler for bioretention cells. The production of cement-modified loess is simple and cost-effective, and using modified loess as a filler can reduce the use of stone resources or other on-site materials. Current methods for improving the filler of bioretention cells are mainly based on sand. This experiment used loess to improve the filler. The performance of loess is better than sand, and can completely replace sand as the filler in bioretention cells.

Establishment and Optimization of Soil Cd Risk Threshold in Typical Karst Area with Potato Production, China.

The threshold is key to risk assessment of soil cadmium (Cd) pollution. However, there is limited research on the soil Cd risk threshold of potatoes. Soil and potato samples (n = 256) were used to establish and optimize the Cd risk threshold by using relative cumulative frequency, bioconcentration factor, and regression model. The results showed that suggested risk screening values (SRSVs) for soil Cd were divided into 2.465 (pH ≤ 5.5), 2.564 (5.5 < pH ≤ 6.5), 2.778 (6.5 < pH ≤ 7.5), and 4.348 mg kg-1 (pH > 7.5). SRSVs were applied to classify soil Cd risk assessment by collecting soil samples (n = 100). Low-risk areas only comprised 0.98% of the total area using risk screening values (RSVs) (GB15618-2018), and risk areas comprised as much as 99.02%. Low-risk area and risk area comprised 97.75% and 2.25% of the total area based on SRSVs. SRSVs are appropriate for potato production in typical karst areas.

Effects of freeze-thaw cycles on nutrient removal from bioretention cells.

There have been numerous summaries of the runoff purification characteristics of bioretention cells in warm climates. However, little has been done on the effects of freeze-thaw cycles (FTCs) that frequently occur in cold regions on bioretention cell performance. Three experimental columns were constructed to simulate the operation of the bioretention cell under the FTCs. The effects of FTCs on the nutrient removal efficiency of different filling bioretention cells were analyzed. The results showed that the ammonia nitrogen (NH4+-N) concentration in the effluent of the wood chip bioretention cell under the T3 conditions (WBCF) (2.35 mg/L) was significantly higher than that of the wood chip bioretention cell operating at room temperature (WBCR) (0.62 mg/L). The effluent NH4+-N concentration of aluminum sludge bioretention cell (ABCF) (0.096 mg/L) under the FTCs was lower than that of WBCF (0.91 mg/L). Under the T3 condition, the effluent nitrate nitrogen (NO3--N) and total nitrogen (TN) concentrations of WBCF (5.33 mg/L and 8.86 mg/L) were higher than those of WBCR (5 mg/L and 6.11 mg/L) at room temperature. Under FTCs conditions, both WBCF and ABCF had high NO3--N removal efficiency (up to 85.87% and 24.75%) at the initial stage of thawing of the filler, and the efficiency gradually decreased with the thawing of the filler. With the increase of FTCs, the NO3--N removal efficiency of WBCF gradually decreased (always higher than 13.6%), while the removal efficiency of ABCF fluctuated wildly (the removal efficiency was primarily negative). The total phosphorus (TP) concentration in the effluent of WBCF (0.11 mg/L) under the T3 conditions was lower than that of WBCR (0.02 mg/L) at room temperature, and the TP concentration of ABCF (0.021 mg/L) in the effluent under the FTCs was slightly lower than that of WBCF (0.031 mg/L). The FTCs have a more significant impact on removing nitrogen pollutants in runoff, but have little effect on phosphorus. Compared with aluminum sludge, wood chips are more suitable for efficient removal of nitrogen pollutants in runoff under the FTCs. The experimental conclusions can provide a reference for the construction of bioretention cells in cold regions.

Controllable synthesis of dual-MOFs nanostructures for pH-responsive artemisinin delivery, magnetic resonance and optical dual-model imaging-guided chemo/photothermal combinational cancer therapy.

Theranostic nanoagents which integrate diagnostic and therapeutic moieties into a single platform have attracted broad attention in cancer therapy, however the development of more effective and less toxic diagnostic and therapeutic interventions is still of great urgency. Herein, novel core-shell PB@MIL-100(Fe) dual metal-organic-frameworks (d-MOFs) nanoparticles are fabricated and their combined theranostic effects in vitro and in vivo are investigated. The d-MOFs nanoparticles can serve as a T1-T2 dual-modal magnetic resonance imaging (MRI) contrast and fluorescence optical imaging (FOI) agent due to the existence of inner PB MOFs and outer MIL-100(Fe) MOFs. The artemisinin (a traditional Chinese anticancer medicine) with a high loading content of 848.4 mg/g is released from the d-MOFs upon tumor cellular endocytosis due to the pH-responsive degradation of outer MOFs in low pH lysosomes of tumor cells. Furthermore, the inner PB MOFs can be utilized for photothermal therapy due to its strong absorbance in NIR region. Under the guidance by such dual-modal imaging, in vivo photothermal and chemotherapy is finally carried out, achieving effective tumor ablation in an animal tumor model. Furthermore, histological analysis revealed that the drug delivery system had no obvious effect on the major organs of mice due to the low toxicity of both d-MOFs and artemisinin. The distinctive multimodal imaging capability, excellent synergistic therapy effect through the combined chemo-photothermal therapy together with the low toxicity of both d-MOFs and artemisinin endow the theranostic nanoagent a promising next generation of nanomedicine for efficient and safe cancer therapy.

Aqueous phase preparation of ultrasmall MoSe2 nanodots for efficient photothermal therapy of cancer cells.

Photothermal therapy (PTT) is a promising cancer treatment with both high effectiveness and fewer side effects. However, an ideal PTT agent not only needs strong absorption of near-infrared (NIR) light and high photothermal conversion efficiency, but also needs good biocompatibility, stability, and small size, which makes the design and preparation of a novel PTT agent a great challenge. In this work, we developed an ultrasonication-assisted liquid exfoliation method for the direct preparation of ultrasmall (2-3 nm) MoSe2 nanodots (NDs) in aqueous solution and demonstrated their superior properties as a PTT agent. The as-prepared MoSe2 NDs have strong absorption of NIR light and high photothermal conversion efficiency of about 46.5%. In vitro cellular experiments demonstrate that MoSe2 NDs have negligible cytotoxicity and can efficiently kill HeLa cells (human cervical cell line) under NIR laser (785 nm) irradiation.

Novel Mn3 [Co(CN)6]2@SiO2@Ag Core-Shell Nanocube: Enhanced Two-Photon Fluorescence and Magnetic Resonance Dual-Modal Imaging-Guided Photothermal and Chemo-therapy.

The versatile Mn3[Co(CN)6]2@SiO2@Ag core-shell NCs are prepared by a simple coprecipitation method. Ag nanoparticles with an average diameter of 12 nm deposited on the surface of Mn3[Co(CN)6]2@SiO2 through S-Ag bonding are fabricated in ethanol solution by reducing silver nitrate (AgNO3 ) with NaBH4 . The NCs possess T1 -T2 dual-modal magnetic resonance imaging ability. The inner Prussian blue analogs (PBAs) Mn3[Co(CN)6]2 exhibit bright two-photon fluorescence (TPF) imaging when excited at 730 nm. Moreover, the TPF imaging intensity displays 1.85-fold enhancement after loading of Ag nanoparticles. Besides, the sample also has multicolor fluorescence imaging ability under 403, 488, and 543 nm single photon excitation. The as-synthesized Mn3[Co(CN)6]2@SiO2@Ag NCs show a DOX loading capacity of 600 mg g(-1) and exhibit an excellent ability of near-infrared (NIR)-responsive drug release and photothermal therapy (PTT) which is induced from the relative high absorbance in NIR region. The combined chemotherapy and PTT against cancer cells in vitro test shows high therapeutic efficiency. The multimodal treatment and imaging could lead to this material a potential multifunctional system for biomedical diagnosis and therapy.

Intense infrared emission of Er(3+) in Ca(8)Mg(SiO(4))(4)Cl(2) phosphor from energy transfer of Eu(2+) by broadband down-conversion.

We report on conversion of near-ultraviolet and visible radiation ranging from 250 to 500 nm into near-infrared emission by a Ca(8)Mg(SiO(4))(4)Cl(2): Eu(2+), Er(3+) phosphor. Efficient 1530-1560 nm Er(3+) emission ((4)I(13/2)-->(4)I(15/2)) was detected under the excitation of Eu(2+) (4f?5d) absorption band as a result of energy transfer from Eu(2+) to Er(3+), which is confirmed by both steady state and time-resolved emission spectra. The laser power dependent emission intensity changes were investigated to analysis the energy transfer mechanism. Energy transfer from Eu(2+) to Er(3+) followed by a multi-photon quantum cutting of Er(3+) is proposed. The result indicates that the phosphor has potential application in enhancement of conversion efficient of germanium solar cells because the energy difference of Er(3+): (4)I(13/2)-->(4)I(15/2) transition matches well with the bandgap of Ge (Eg~0.785 eV).