Porous Polypyrrolidines for Highly Efficient Recovery of Precious Metals through Reductive Adsorption Mechanism.

The recycling and utilization of precious metals have emerged as a critical research focus in advancing the development of the circular economy. Among numerous methods for recovering precious metals such as gold, adsorbents with both high adsorption selectivity and capacity have become key technologies. This article incorporated the N-phenylpyrrolidine into a flexible porous polynorbornene backbone to create a class of distinctive porous organic polymers, named BIT-POP-14-BIT-POP-17. Through a reductive capture mechanism, the reductive adsorption sites of N-phenylpyrrolidine coordinate selectively with precious metals, the reduced metal is captured by the hierarchically porous polymers with flexible backbone. This approach leads to remarkable gold recovery efficiency, achieving a record of 2321 mg g-1 at ambient conditions, and 3020 mg g-1 under UV light, surpassing the theoretical limit. The porous polymers are filled in a column for a continuous uptake of gold from waste printed circuit boards (PCBs), showing recovery efficiency toward gold as high as 95% after 84 h. Overall, this work offers a new perspective on designing novel adsorbents for precious metal recovery, providing inspiration for researchers to explore novel adsorption modes and contribute to the advancement of the circular economy.

Bioavailability and ecological risk assessment of metal pollutants in ambient PM2.5 in Beijing.

Metal pollutants in fine particulate matter (PM2.5) are physiologically toxic, threatening ecosystems through atmospheric deposition. Biotoxicity and bioavailability are mainly determined by the active speciation of metal pollutants in PM2.5. As a megacity in China, Beijing has suffered severe particulate pollution over the past two decades, and the health effects of metal pollutants in PM2.5 have received significant attention. However, there is a limited understanding of the active forms of metals in PM2.5 and their ecological risks to plants, soil or water in Beijing. It is essential that the ecological risks of metal pollutants in PM2.5 are accurately evaluated based on their bioavailability, identifying the key pollutants and revealing historic trends to future risks control. A two-year project measured the chemical speciation of pollution elements (As, Cd, Cu, Cr, Ni, Mn, Pb, Sb, Sr, Ti, and Zn) in PM2.5 in Beijing, in particular their bioavailability, assessing ecological risks and identifying key pollutants. The mass concentrations of total and active species of pollution elements were 199.12 ng/m3 and 114.97 ng/m3, respectively. Active fractions accounted for 57.7 % of the total. Cd had the highest active proportion. Based on the risk assessment code (RAC), most pollution elements except Ti had moderate or high ecological risk, with RAC exceeding 30 %. Cd, with an RAC of 70 %, presented the strongest ecological risk. Comparing our data with previous research shows that concentrations of pollution elements in PM2.5 in Beijing have decreased over the past decade. However, although the total concentrations of Cd in PM2.5 have decreased by >50 % over the past decade, based on machine model simulation, its ecological risk has reduced by only 10 %. Our research shows that the ecological risks of pollution elements remain high despite their decreasing concentrations. Controlling the active species of metal pollutants in PM2.5 in Beijing in the future is vital.

Altered Intrinsic Functional Connectivity of the Primary Visual Cortex in Patients with Neovascular Glaucoma: A Resting-State Functional Magnetic Resonance Imaging Study.

PURPOSE: The purpose was to investigate the differences in spontaneous functional connectivity (FC) of the primary visual cortex (V1) between patients with neovascular glaucoma (NVG) and healthy controls (HCs) using resting-state functional magnetic resonance imaging data. METHODS: A total of 18 patients with NVG (nine males and nine females) and 18 HCs with similar age and sex background were enrolled in the study and inspected using resting-state functional magnetic resonance imaging. The differences in FC of the V1 between the two groups were compared using the independent samples t-test. We used the receiver operating characteristic (ROC) curve to compare the average FC values of NVG subjects with those of HCs. RESULTS: FC in the left V1 and right fusiform gyrus, bilateral cuneus, and left precuneus was significantly decreased in the NVG group compared with that reported in the HC group. Meanwhile, patients with NVG presented increased FC between the right V1 and bilateral middle frontal gyrus. However, they also exhibited declining FC between the right V1 and left precuneus, and bilateral cuneus. The ROC curve analysis of each brain region indicated that the accuracy of the area under the ROC curves regarding NVG was excellent. CONCLUSION: NVG involves aberrant FC in the V1 in different brain areas, including the visual-related and cognitive-related regions. These findings may assist in unveiling the underlying neural mechanisms of impaired visual function in NVG.

Strontium Uptake and Effect in Lettuce and Radish Cultivated Under Hydroponic Conditions.

The accumulation of strontium (Sr) in lettuce and radish under 0 (control), 0.5, 1, 2.5, 5, and 10 mM Sr treatments in hydroponic solution at 16, 23 and 30 days and the effects of Sr stress on six nutrient elements in plants were investigated. The results showed that Sr concentrations in plant aerial and underground parts increased in low-Sr treatments (0.5, 1 and 2.5 mM) and fluctuated in high-Sr treatments (5 and 10 mM) throughout the three sampling periods. Sr concentrations were higher in roots than in leaves, reaching 108.8 ± 14.7 and 134.1 ± 1.2 mg/g in lettuce and radish roots, respectively, after 10 mM Sr treatment. Translocation factor (TF) values (ratio of the Sr concentrations in aerial parts to that in roots) were inversely related to the Sr content in the hydroponic solution, and reached 1.45 ± 0.17 to 0.15 ± 0.03 and 1.06 ± 0.20 to 0.12 ± 0.004 for lettuce and radish. The variation in chlorophyll content was consistent with that in plant biomass.

Antioxidative response in leaves and allelochemical changes in root exudates of Ricinus communis under Cu, Zn, and Cd stress.

We have previously reported that Ricinus communis is a good candidate for the phytoremediation of Cd- and Zn-contaminated soil and for fuel production. In this study, changes in the activity of antioxidant enzymes (superoxide dismutase, SOD; catalase, CAT; and guaiacol peroxidase, POD) and the contents of chlorophyll and malondialdehyde (MDA) in R. communis leaves under Cu, Zn, and Cd stress were examined. Compounds from the exudate of R. communis roots were collected and analyzed using GC-MS chromatograms. The results of enzyme activity showed that Cd treatment significantly increased the SOD content of R. communis leaves and slightly elevated the CAT content, whereas the POD content increased markedly at low Cd treatment concentrations and decreased as Cd concentrations increased. Zn treatment distinctly elevated SOD and POD content in R. communis leaves but had no great influence on CAT content. Cu treatment slightly increased CAT activity, while Cu did not evidently change SOD and POD activity. We found 17, 29, 18, 18, and 33 different compounds in the R. communis root exudates from the control group and Cd, Cu, Zn, and Cd+Cu+Zn treatment groups, respectively. The root exudates mainly included ester, alcohol, ether, amide, acid, phenol, alkanes, ketone, aromatic hydrocarbon, and nitrile compounds. However, the root exudates of R. communis grown in uncontaminated soils were dominated by esters, alcohols, and ethers. Single Cu or Zn treatment slightly changed the root exudates, which were dominated by esters, alcohols, and amides. In the Cd and Cd+Cu+Zn treatment groups, the compositions of root exudates apparently increased, with alkanes as the major species (> 88%).

Effects of biochars on the availability of heavy metals to ryegrass in an alkaline contaminated soil.

A pot experiment was conducted to investigate the effects of biochars on the availability of heavy metals (Cd, Cu, Mn, Ni, Pb, and Zn) to ryegrass in an alkaline contaminated soil. Biochars only slightly decreased or even increased the availability of heavy metals assesses by chemical extractant (a mixture of 0.05 mol L-1 ethylenediaminetetraacetic acid disodium, 0.01 mol L-1 CaCl2, and 0.1 mol L-1 triethanolamine). The significantly positive correlation between most chemical-extractable heavy metals and the ash content in biochars indicated the positive role of ash in this extraction. Biochars significantly reduced the plant uptake of heavy metals, excluding Mn. The absence of a positive correlation between the chemical-extractable heavy metals and the plant uptake counterparts (except for Mn) indicates that chemical extractability is probably not a reliable indicator to predict the phytoavailability of most heavy metals in alkaline soils treated with biochars. The obviously negative correlation between the plant uptake of heavy metals (except for Mn) and the (O + N)/C and H/C indicates that biochars with more polar groups, which were produced at lower temperatures, had higher efficiency for reducing the phytoavailability of heavy metals. The significantly negative correlations between the plant uptake of Mn and ryegrass biomass indicated the "dilution effect" caused by the improvement of biomass. These observations will be helpful for designing biochars as soil amendments to reduce the availability of heavy metals to plants in soils, especially in alkaline soils.

[The Concentration Effect of Near-Infrared Quantum Cutting Luminescence of Tm(3+) Ion Sensitized with Bi(3+) Ion in YNbO(4) Phosphor].

Searching for new energy source is one of the most important projects faced by the global, while the most ideal new energy source is solar cell. Near infrared quantum cutting luminescence method can doubly transfer large energy photon which is not sensitive to Si or Ge solar cell to small energy photon which is sensitive to Si or Ge solar cell. It can resolve the spectral mismatch problem and largely enhance solar cell efficiency. Therefore, it is significant. The concentration effect of near-infrared quantum cutting luminescence of Tm3+Bi3+∶YNbO4 phosphor is reported in present manuscript. Through the measurement of excitation and emission spectra, it is found that the Tm0.058Bi0.010Y0.932NbO4 powder phosphor has intense 1 820.0 nm near-infrared quantum cutting luminescence. Further analysis finds they are multi-photon quantum cutting luminescence induced by the cross-energy transfer process. The population of 1G4 energy level may be directly transferred to lower energy level mainly through {1G4­3H4, 3H6­3H5} and {1G4­3H5, 3H6­3H4} cross-energy transfer processes, i. e. one population of the 1G4 energy level may effectively lead to two populations, which are positioned at the 3H4 and 3H5 energy levels, respectively, mainly through {1G4­3H4, 3H6­3H5} and {1G4­3H5, 3H6­3H4} cross-energy transfer processes. This may also effectively lead to three populations of the 3F4 energy level through {3H4­3F4, 3H6­3F4} cross-energy transfer process from the 3H4 level and multi-phonon non-radiative relaxation from the 3H5 level, respectively. This results in the effective three-photon near-infrared quantum cutting of the 3F4­3H6 fluorescence of Tm3+ ion. It's also found that the sensitization action of Bi3+ ion to Tm3+ ion is very strong. The enhancement of the 1 820.0 nm near-infrared quantum cutting luminescence, of Tm0.058Bi0.010Y0.932NbO4 relative to Tm0.005Y0.995NbO4, is about 175.5 times, when excited by the 302.0 nm light. The present results are significant for the exploration of the next-generation multi-photon near-infrared quantum cutting germanium solar cell.

Cadmium transfer and detoxification mechanisms in a soil-mulberry-silkworm system: phytoremediation potential.

Phytoremediation has been proven to be an environmentally sound alternative for the recovery of contaminated soils, and the economic profit that comes along with the process might stimulate its field use. This study investigated cadmium (Cd) transfer and detoxification mechanisms in a soil-mulberry-silkworm system to estimate the suitability of the mulberry and silkworm as an alternative method for the remediation of Cd-polluted soil; it also explored the underlying mechanisms regulating the trophic transfer of Cd. The results show that both the mulberry and silkworm have high Cd tolerance. The transfer factor suggests that the mulberry has high potential for Cd extraction from polluted soil. The subcellular distribution and chemical forms of Cd in mulberry leaves show that cell wall deposition and vacuolar compartmentalization play important role in Cd tolerance. In the presence of increasing Cd concentrations in silkworm food, detoxification mechanisms (excretion and homeostasis) were activated so that excess Cd was excreted in fecal balls, and metallothionein levels in the mid-gut, the posterior of the silk gland, and the fat body of silkworms were enhanced. And, the Cd concentrations in silk are at a low level, ranging from 0.02 to 0.21 mg kg(-1). Therefore, these mechanisms of detoxification can regulate Cd trophic transfer, and mulberry planting and silkworm breeding has high phytoremediation potential for Cd-contaminated soil.

[Near-infrared quantum cutting downconversion luminescence of Yb3+ ion cooperative energy transferred from YVO4 matrix donor].

The present manuscript researches the near infrared quantum cutting luminescence phenomena of Yb3+ ion in YVO4 crystal matrix The luminescence spectra, excitation spectra and fluorescence lifetimes were measured. It was found that the excitation of YVO4 crystal matrix energy band by 322.0 nm light can result in the effective secondary cooperative energy transfer of Yba+ ion from the YVO4 crystal matrix It results in the intense 985.5 nm 2F(5/2)-->2F(7/2) near infrared quantum cutting luminescence of Yb3+ ion. Meanwhile, the 430.O nm luminescence intensity of YVO4 crystal matrix decreases greatly. From the experimental measurements, it was found that the lifetime of 430.0 nm fluorescence of (A) Yb(1.5) : YVO4 crystal is tauA = 3.785 s and that of (B) YVO4 crystal is tauB=22.72 s. It was found also that the theoretical efficiency up limit of quantum cutting of (A) Yb(1.5) : YVO4 crystal is about eta1.5%=183-3%.

Lead in the soil-mulberry (Morus alba L.)-silkworm (Bombyx mori) food chain: translocation and detoxification.

The translocation of lead (Pb) in the soil-mulberry-silkworm food chain and the process of Pb detoxification in the mulberry-silkworm chain were investigated. The amount of Pb in mulberry, silkworm, feces and silk increased in a dose-responsive manner to the Pb contents in the soils. Mulberry roots sequestered most of the Pb, ranging from 230.78 to 1209.25 mg kg(-1). Over 92% of the Pb in the mulberry leaves was deposited in the cell wall, and 95.29-95.57% of the Pb in the mulberry leaves was integrated with oxalic acid, pectates and protein, and it had low bioavailability. The Pb concentrations in the silkworm feces were 4.50-4.64 times higher than those in the leaves. The synthesis of metallothioneins in three tissues of the silkworms was induced to achieve Pb homeostasis under Pb stress. These results indicated the mechanism involved in Pb transfer along the food chain was controlled by the detoxification of Pb in different trophic levels. Planting mulberry and rearing silkworm could be a promising approach for the remediation of Pb-polluted soils due to the Pb tolerance of mulberry and silkworm.

Cadmium adsorption on plant- and manure-derived biochar and biochar-amended sandy soils: impact of bulk and surface properties.

To investigate the role of the bulk and surface composition of both biochar and biochar-amended soils in the adsorption of Cd(2+), as well as the influence of different biochars added to the soils on Cd(2+) adsorption, swine-manure-derived biochars (BSs) and wheat-straw-derived biochars (BWs) were produced at 300, 450, and 600°C. These biochars were added to a sandy soil to investigate the effect of biochars on the adsorption of Cd(2+) by soil. The significantly higher surface C content of the amended soils compared to their bulk C content suggests that the minerals of the biochar-amended soils are most likely covered primarily by biochars. The maximum adsorption capacity (Qmax,total) of the BSs was 10-15 times higher than that of the BWs due to the high polarity and ash content of the BSs. The polarity ((N+O)/C) of the low-temperature biochars greatly affected their Cd(2+) adsorption. The Qmax,total of the BS-amended soils increased with increasing dose, whereas the Qmax,total of the BW-amended soils showed the opposite behavior, which was attributed to the different surface composition characteristics of the two types of soil. The BSs were more effective in immobilizing Cd(2+) upon application to the soil relative to the BWs. This study elucidates the spatial distribution of biochars in biochar-amended soils and highlights the importance of the surface composition of the investigated samples in Cd(2+) adsorption.

Accumulation and localization of cadmium in potato (Solanum tuberosum) under different soil Cd levels.

Phytoavailability and uptake mechanism of Cd in edible plant tissues grown on metal polluted agricultural soils has become a growing concern worldwide. Uptake, transport, accumulation and localization of cadmium in potato organs under different soil Cd levels were investigated using inductively-coupled plasma mass spectrometry and energy dispersive X-ray microanalysis. Results indicated that Cd contents in potato organs increased with increasing soil Cd concentrations, and the order of Cd contents in different organs was leaves > stems/roots > tubers. Root-to-stem Cd translocation coefficients ranged from 0.89 to 1.81. Cd localization in potato tissues suggested that leaves and stems should be the main compartment of Cd storage and uptake. Although low concentrations of Cd migrated from the root to tuber, Cd accumulation in the tuber exceeded the standard for food security. Therefore, the planting of potato plants in farmland containing Cd should be closely evaluated due to its potential to present health risks.

[Spectroscopy parameters of Ho3+ in Ho3+ : FOG and Ho3+ : FOV].

In the present paper, the absorption spectra of Ho3+ (0.5 mol%)-doped oxyfluoride glass (FOG) sample and Ho3+ (0.5 mol%)-doped oxyfluoride vitroceramics (FOV) sample were measured through experiment. The authors calculated the intensity parameters omega 2, 4, 6 of the two materials according to J-O theory, and analyzed the possible reason for the difference between the two materials on the intensity parameters. After that the authors calculated oscillator strength, spontaneous radiative transition rate, branching ratio and integrated emission cross section and some other spectroscopic parameters of several excited states and then made a comparative analysis of the two materials based on these spectroscopic parameters. The authors found that the oscillator strength of trivalent holmium iron in FOV is about the same with the oscillator strength in YAlO3 and is similar to oscillator strength in FOG, while slightly larger than in that LBTAF and much larger than that in LaF3 and ZBLAN. By analyzing the calculated spectroscopic parameters, it can be found that some transitions, especially 5I7 --> 5I8, 5F5 --> 5I8 etc., have a relatively large oscillator strengths(larger than 10(-6)) and large integrated emission cross sections(larger than 10(-18) cm). These transitions have the conditions to form laser passages, so they are worth a lot of attention. At last, application prospects of several strong luminescence transitions were concluded.

Effects of accompanying anions on cesium retention and translocation via droplets on soybean leaves.

Plant foliar uptake and translocation is an important pathway for the migration of radiocesium to the human diet. This study reports the effects of accompanying anions ( [Formula: see text] , [Formula: see text] , [Formula: see text] , and I(-)) on cesium retention and translocation. An experiment to simulate cesium retention and translocation was conducted in a greenhouse by applying droplets of stable cesium solutions to the upper surface of four soybean [Glycine max (L.) Merr.] trifoliate leaves. The average percentages of cesium retention with the accompanying anions [Formula: see text] , [Formula: see text] , [Formula: see text] , and I(-) on the leaves were 7.2, 21.5, 49.3, and 10.2%, respectively. Retention values of the four treatments were stable during the 3-day exposure period, indicating that cesium could be absorbed and penetrate the cuticle quickly once it was dissolved. Scanning electron microscopy coupled with energy dispersive X-ray microanalysis showed that particles containing cesium remained on the leaf surfaces after washing. Also, nano-sized particles containing cesium were observed inside the leaf tissues. Cesium concentrations in the uncontaminated leaves, pods, stems, and roots increased during the study period indicating cesium redistribution from the contaminated leaves.

[Total contents of heavy metals and their chemical fractionation in agricultural soils at different locations of Beijing City].

In this study, 23 groups of suited typical soil-wheat grain samples were collected from different locations of Beijing city (central city, suburban plain and exurban plain), the accumulation, chemical forms and bioavailability of heavy metals in arable soils under different human activity intensity were analyzed, and their source identifications and health risk were discussed. The results showed that (1) Urban soils exhibited Pb contamination with an average concentration (35.59 mg x kg(-1)) above the WHO limit, probably due to the emission of traffic activities and industrial processes. In addition, long-term sewage irrigation and other agricultural activities led to local metal contamination in the suburban agricultural soils. (2) Cu, Zn and Pb were predominantly associated with the residual (35%-75%) and organic (23%-53%) fractions, followed by Fe/Mn oxide (1%-19%), and very small proportion of carbonate (n. d.-5%) and exchangeable (n. d.-2%) fraction. Furthermore, compared with the suburban agricultural soils, Pb, Zn and Cu in the urban agricultural soils showed higher mobility, whereas the exurban agricultural soils presented the lowest mobility. For Cd, the order was contrary. Besides, Cd showed the highest bioavailability among the four metals in suburban and exurban arable soils due to its considerable proportion of exchangeable (13% -31%) and carbonate fractions (11%-27%). (3) Cd and Zn contents in wheat grains were largely dependent on the Fe/Mn ox. fractions in the studied soils (P < 0.05, r were 0.43-0.7). (4) Pb and Zn concentrations in wheat grains in some of the urban and suburban agricultural soils were above the standard limit, which might bring potential risk for the health of the local residents.

Hydrolyzed Al(III) clusters: speciation stability of nano-Al13.

Pure nano-Al13 and aggregates at various concentrations were prepared to examine the particle size effect of coagulation with inorganic polymer flocculant. The property and stability of various species formed were characterized using Infrared, 27Al-NMR, photo correlation spectroscopy (PCS), and Ferron assay. Results showed that concentration and temperature exhibited different roles on the stability of Al13. The quantity of Alb species analyzed by ferron assay in the initial aging period corresponded well with that of Al13, which has been confirmed in a dimension range of 1-2 nm by PCS. Al13 solutions at high concentrations (0.5-2.11 mol/L) were observed to undergo further aggregation with aging. The aggregates with a wide particle size distribution would contribute to the disappeared/decreased Al13 basis on the 27Al-NMR spectrum, whereas a part of Al13 would still remain as Alb. At low concentrations, Al13 solution was quite stable at normal temperature, but lost its stability quickly when heating to 90 degrees C.

[Cooperative downconversion in Tb (0.7 ) Yb (5) : FOV oxyfluoride nanophase vitroceramics].

The present article reports the infrared quantum cutting study of the nanophase oxyfluoride vitroceramics Tb(0.7)Yb (5.0) : FOV. The visible to infrared fluorescence emission spectra, excitation spectra and fluorescence lifetime were measured carefully. The infrared quantum cutting phenomenon {1([5 D4 --> 7 F6](Tb3+), 2([2 F7/2 --> 2 F5/2](Yb3+)} was analyzed based on the above experiments. It was found that the theoretical quantum cutting efficiency is about 121.35% when 5D4 level is excited by 487.0nm light, and about 136.27% when (5D3, 5G6) levels are excited by 378.0 nm light respectively. Meanwhile, it is first time for the present paper to find a cooperative downconversion phenomenon {2([(5D3, 5G6) --> 5D4] (Tb3+), 1([2 F7/2 --> 2 F5/2] (Yb3+)}. That is, the authors found for the first time that the donor Tb3+ ion releases two pieces of energy [(5D3, 5G6) --> 5D4] of small energy photon to produce a middle energy photon [2 F5/2 --> 2 F7/2] of acceptor Yb3+ ion.

[Improvement of anti-stokes energy transfer between rare earth ions--2. Numerical calculation and analysis].

The dynamics of all levels were calculated numerically in the present article for Er(0.5)Yb(3):FOV oxyfluoride nanophase vitroceramics. The population dynamical processes were analyzed carefully. It was found for the first time that traditional phonon-assisted energy transfer theory of rare earth ion energy transfer can not well explain the observed experimental calibrated results, as it does not take into account the difference between Stokes and anti-Stokes process. A coefficient, the improved factor of the intensity ratio of Stokes to anti-Stokes process in quantum Raman theory compared to classical Raman theory, was introduced for the first time to successfully describe the anti-Stokes energy transfer. The theoretical improvement results are coincident with experiments very well. This improvement is very significant and indispensable when the photonics of nanomaterials is probed.

Al(III) speciation distribution and transformation in high concentration PACl solutions.

Effects of Al(III) concentration and pH on the speciation of Al(III) in polyaluminum chloride (PACl) solutions especially on the Al13 fraction were investigated. A series of PACl samples were prepared over the range of Al(III) concentration from 0.01 to 2.0 mol/L with the B (OH/Al ratio) value from 1.0 to 2.5 by forced hydrolysis of AlCl3. The samples were characterized by ferron assay, pH and 27Al NMR. It was shown that the Al(lIII) concentration had a dramatic effect on the hydrolysis processes and the species distribution of PACl was in relate to the decrease of pH. The fraction of Al species, Alb, (or A113) decreased and Al, increased with increase of total Al(III) concentration. Under the condition of AI(llI) 2.0 mol/L, B = 2.5, the pH value was 2.73 and no Al13 could be detected. During diluting and aging, the species distribution evolved. The Al13 could then be detected again and the amounts increased with time. If the diluted samples were concentrated by freeze dry at -35 degrees C or heating at 80 degrees C, the pH value and Al13 content would decrease with the increased concentration. It demonstrated that the key factor for formation of Al13 in concentrated PACl was pH value.