Microelectrochemical Sensor Reveals Tunneling Nanotube-Mediated Intercellular Communication of Endothelial Mechanotransduction.

The intercellular communication of mechanotransduction has a significant impact on various cellular processes. Tunneling nanotubes (TNTs) have been documented to possess the capability of transmitting mechanical stimulation between cells, thereby triggering an influx of Ca2+ ions. However, the related kinetic information on the TNT-mediated intercellular mechanotransduction communication is still poorly explored. Herein, we developed a classic and sensitive Pt-functionalized carbon fiber microelectrochemical sensor (Pt/CF) to study the intercellular communication of endothelial mechanotransduction through TNTs. The experimental findings demonstrate that the transmission of mechanical stimulation from stimulated human umbilical vein endothelial cells (HUVECs) to recipient HUVECs connected by TNTs occurred quickly (<100 ms) and effectively promoted nitric oxide (NO) production in the recipient HUVECs. The kinetic profile of NO release exhibited remarkable similarity in stimulated and recipient HUVECs. But the production of NO in the recipient cell is significantly attenuated (16.3%) compared to that in the stimulated cell, indicating a transfer efficiency of approximately 16.3% for TNTs. This study unveils insights into the TNT-mediated intercellular communication of mechanotransduction.

Examining dynamic developmental trends: the interrelationship between age-friendly environments and healthy aging in the Chinese population-evidence from China Health and Retirement Longitudinal Study, 2011-2018.

BACKGROUND: The objective of this research is to investigate the dynamic developmental trends between Age-Friendly Environments (AFE) and healthy aging in the Chinese population. METHODS: This study focused on a sample of 11,770 participants from the CHARLS and utilized the ATHLOS Healthy Aging Index to assess the level of healthy aging among the Chinese population. Linear mixed model (LMM) was used to explore the relationship between AFE and healthy aging. Furthermore, a cross-lagged panel model (CLPM) and a random-intercept cross-lagged panel model (RI-CLPM) were used to examine the dynamic developmental trends of healthy aging, taking into account both Between-Person effects and Within-Person effects. RESULTS: The results from LMM showed a positive correlation between AFE and healthy aging (ß = 0.087, p < 0.001). There was a positive interaction between the geographic distribution and AFE (central region * AFE: ß = 0.031, p = 0.038; eastern region * AFE: ß = 0.048, p = 0.003). In CLPM and RI-CLPM, the positive effect of healthy aging on AFE is a type of Between-Person effects (ß ranges from 0.147 to 0.159, p < 0.001), while the positive effect of AFE on healthy aging is Within-Person effects (ß ranges from 0.021 to 0.024, p = 0.004). CONCLUSION: Firstly, individuals with high levels of healthy aging are more inclined to actively participate in the development of appropriate AFE compared to those with low levels of healthy aging. Furthermore, by encouraging and guiding individuals to engage in activities that contribute to building appropriate AFE, can elevate their AFE levels beyond the previous average level, thereby improving their future healthy aging levels. Lastly, addressing vulnerable groups by reducing disparities and meeting their health needs effectively is crucial for fostering healthy aging in these populations.

Uptake, subcellular distribution, and fate of tetracycline in two wetland plants supplemented with microbial agents: Effect and mechanism.

The use of wetland plants in the context of phytoremediation is effective in the removal of antibiotics from contaminated water. However, the effectiveness and efficiency of many of these plants in the removal of antibiotics remain undetermined. In this study, the effectiveness of two plants-Phragmites australis and Iris pseudacorus-in the removal of tetracycline (TC) in hydroponic systems was investigated. The uptake of TC at the roots of I. pseudacorus and P. australis occurred at concentrations of 588.78 and 106.70 µg/g, respectively, after 7-day exposure. The higher uptake of TC in the root of I. pseudacorus may be attributed to its higher secretion of root exudates, which facilitate conditions conducive to the reproduction of microorganisms. These rhizosphere-linked microorganisms then drove the TC uptake, which was higher than that in the roots of P. australis. By elucidating the mechanisms underlying these uptake-linked outcomes, we found that the uptake of TC for both plants was significantly suppressed by metabolic and aquaporin inhibition, suggesting uptake and transport of TC were active (energy-dependent) and passive (aquaporin-dominated) processes, respectively. The subcellular distribution patterns of I. pseudacorus and P. australis in the roots were different, as expressed by differences in organelles, cell wall concentration levels, and transport-related dynamics. Additionally, the microbe-driven enhancement of the remediation capacities of the plants was studied comprehensively via a combined microbial-phytoremediation hydroponic system. We confirmed that the microbial agents increased the secretion of root exudates, promoting the variation of TC chemical speciation and thus enhancing the active transport of TC. These results contribute toward the improved application of wetland plants in the context of antibiotic phytoremediation.

LIMD2 promotes tumor proliferation, invasion, and epithelial-mesenchymal transition in clear cell renal cell carcinoma.

LIMD2 was found upregulated in various tumors and metastatic samples and associated with a poor prognosis. But the role of LIMD2 in clear cell renal cell carcinoma (ccRCC) remains elusive. The expression of LIMD2 in ccRCC was analyzed using cohort data downloaded from TCGA and ICGC databases. In vitro and in vivo experiments were then conducted to study the biological role of LIMD2 in ccRCC and explore the possible mechanism. The results indicated that LIMD2 was overexpressed and correlated with a poor outcome in ccRCC. LIMD2 promoted the malignancy of ccRCC both in vitro and in vivo. LIMD2 induced epithelial-mesenchymal transition (EMT) via activating the ILK/Akt pathway in ccRCC. In conclusion, LIMD2 is overexpressed and promotes proliferation, invasion, and EMT in ccRCC, which may serve as a potential novel therapeutic target for ccRCC.

[Effect of Pien Tze Huang against EV71].

This study aims to investigate the inhibitory effect of Pien Tze Huang(PZH) on enterovirus 71(EV71). To be speci-fic, chemiluminescence method was adopted to evaluate the toxicity of PZH to African green monkey kidney(Vero) cells and human rhabdomyosarcoma(RD) cells, and cytopathic effect(CPE) method to assess the inhibition on EV71-GFP reporter virus and EV71 C4 wild-type virus. The results showed that PZH had low cytotoxicity to Vero cells and RD cells, with the half-maximal cytotoxic concentration(CC_(50)) of about 0.691 3-0.879 2 mg·mL~(-1) for the two. In addition, PZH can effectively inhibit the replication of EV71 within the non-cytotoxic concentration range, and dose-dependently alleviate the cytopathic changes caused by virus infection, with the half-maximal effective concentration(EC_(50)) of 0.009 2-0.106 3 mg·mL~(-1). On the basis of the above results, the green fluorescent protein(GFP), indirect immunofluorescence assay(IFA), and median tissue culture infective dose(TCID_(50)) were employed to assess and verify the anti-EV71-GFP and anti-EV71 C4 activity of PZH. The results demonstrated that PZH can dose-dependently lower the expression of GFP by EV71-GFP and structural protein VP-1 by EV71 C4 and decrease the production of progeny infectious viruses. The EC_(50) of PZH for EV71-GFP and EV71 C4 was about 0.006 0-0.006 2 mg·mL~(-1) and 0.006 6-0.025 6 mg·mL~(-1), respectively. This study suggested that PZH may exert antiviral activity by acting on EV71 and interfering with the expression of VP-1. At the moment, there is still a lack of specific anti-EV71 drugs. This study proposed a new idea for the symptomatic treatment of EV71 infections such as hand-foot-mouth disease and verified an effective drug for the treatment of EV71 infections.

Ultrasound-assisted catalytic reduction of Cr(VI) by an acid mine drainage based nZVI coupling with FeS2 system from aqueous solutions: Performance and mechanism.

Nowadays, nanoscale zero valent iron (nZVI) has been extensively applied for the decontamination of various pollutants, but passivation of nZVI severely affects its reactivity in use. In this study, ultrasound (US)-assisted catalytic reduction of Cr(VI) by an acid mine drainage based nZVI (AMD-nZVI) coupling with FeS2 system was systematically examined. Results show that the presence of FeS2 and US induced a synergistic enhancement of Cr(VI) removal by AMD-nZVI. Nearly 98% of Cr(VI) removal was achieved by AMD-nZVI/FeS2/US process within 60 min under optimal reaction conditions. Several coexisting substances with lower concentration including Pb(II), Ni(II), bisphenol A (BPA) and 2,4-diclorophenol (2,4-DCP) could be effectively removed in simultaneous manner with Cr(VI) removal. The inhibitory order of water matrix species on Cr(VI) removal was NO3- > PO43- > HCO3- > Ca2+ > Mg2+ > Cl-, and a serious suppression effect was induced by humic acid (HA). Addition of ethylene diamine tetra-acetic acid (EDTA) and citric acid (CA) could enhance Cr(VI) removal rate. An enhanced reaction mechanism was proposed, which involved the regeneration of more Fe2+ and H+ by AMD-nZVI/FeS2/US process, leading to the reduction of Cr(VI) by AMD-nZVI and FeS2 into Cr(III) species inculding Cr2O3 and Cr(OH)3. This study well demonstrates that AMD-nZVI/FeS2/US process is considered as a potential candidate for the remediation of Cr(VI) in real wasterwater.

Multifunctional Cellular Beacons with in Situ Synthesized Quantum Dots Make Pathogen Detectable with the Naked Eye.

The rapid and sensitive detection of pathogens is extremely crucial for timely clinical diagnosis and diseases control. Here, by employing cellular beacons with in situ synthesized QDs created from Staphylococcus aureus ( S. aureus), we efficiently fabricated an antibody (Ab) and acetylcholinesterase (AChE)-functionalized nanobioprobe, i.e., multifunctional cellular beacons (MCBs), avoiding complicated modification. Coupled with magnetic separation, a novel method for pathogen detection with the naked eye is established. With this method, enterovirus 71 (EV71) can be detected by the naked eye through the aggregation of gold nanoparticles that is triggered by the product of AChE catalyzed acetylthiocholine, with a detection limit of 0.5 ng/mL. Moreover, due to the MCBs have high luminance with perfect uniformity, the detection can also be realized by counting the number of MCBs, with a detection limit of 1 ng/mL. The method is validated with human throat swabs, resulting in a complete consistence with reverse transcription-polymerase chain reaction results. This study reports the first cellular beacons-based method for pathogen detection by the naked eye and broadens the applicability of cell self-synthesized nanoparticles-based immunoassays. Moreover, the MCBs-based method will provide a powerful tool for clinical detection.

LB-100 sensitizes hepatocellular carcinoma cells to the effects of sorafenib during hypoxia by activation of Smad3 phosphorylation.

Hepatocellular carcinoma (HCC) is a common cancer with poor prognosis. The multikinase inhibitor sorafenib is the only clinically proved systematic treatment for HCC. However, few patients respond to sorafenib. Hypoxic microenvironments contribute to sorafenib resistance. LB-100, a serine/threonine protein phosphatase 2A (PP2A) inhibitor was previously found to be a chemosensitizer in HCC. Here, we tested whether LB-100 could sensitize HCC to the effects of sorafenib. Intriguingly, LB-100 enhanced the effects of sorafenib in HCC cells only during hypoxic environments. LB-100 dramatically increased intracellular p-Smad3 level, which was responsible for the effect of LB-100 as a sensitizer. LB-100 downregulated Bcl-2 expression and enhanced sorafenib-induced apoptosis in HCC cells. We further proved that PP2A mediated LB-100-induced p-Smad3 overexpression. In addition, p38 mitogen-activated protein kinase pathway was activated in hypoxic conditions, and enhanced p-Smad3-dependent Bcl-2 inhibition and consequent apoptosis. In conclusion, LB-100 sensitized HCC cells to sorafenib in hypoxic environments. This effect was mediated by inactivation of PP2A, resulting in enhanced level of p-Smad3. Increased p-Smad3 downregulated Bcl-2, causing increased apoptosis of HCC cells.

[Application of zebrafish in drug screens for active ingredients].

Zebrafish has unique advantages over other animal models in the aspect of drug screens for active ingredients and gains more and more attentions in drug research and development recently. Thus, this article reviews the recent advance of zebrafish-based drug screens in Chinese traditional medicine (TCM) effective part research, monomer drug screening, activity evaluation of natural products, discovery of new uses for old drugs, and toxicity assessment in early-phase drug discovery.

Simultaneous detection of multiple influenza virus subtypes based on microbead-encoded microfluidic chip.

Influenza virus, existing many subtypes, causes a huge risk of people health and life. Different subtypes bring a huge challenge for detection and treatment, thus simultaneous detection of multiple influenza virus subtypes plays a key role in fight against this disease. In this work, three kinds of influenza virus subtypes are one-step detection based on microbead-encoded microfluidic chip. HIN1, H3N2 and H7N3 were simultaneously captured only by microbeads of different magnetism and sizes, and they were further treated by magnetic separation and enriched through the magnetism and size-dependent microfluidic structure. Different subtypes of influenza virus could be linearly encoded in different detection zones of microfluidic chip according to microbeads of magnetism and size differences. With the high-brightness quantum dots (QDs) as label, the enriched fluorescence detection signals were further read online from linearly encoded strips, obtaining high sensitivity with detection limit of HIN1, H3N2, H7N3 about 2.2 ng/mL, 3.4 ng/mL and 2.9 ng/mL. Moreover, a visual operation interface, microcontroller unit and two-way syringe pump were consisted of a miniaturized detection device, improving the detection process automation. And this assay showed strong specificity. This method improves a new way of multiple pathogens detection using microbead-encoded technologies in the microfluidic chip.

Purification of quantum dot-based bioprobes with a salting out strategy.

A salting out strategy is reported for purification of IgG-conjugated QD (IgG-QD) bioprobes. Adding NaCl can precipitate free IgG selectively, while the IgG-QD maintains good colloidal stability. The dynamic light scattering technique reveals that this is due to the relatively positive zeta potential of free IgG than that of the IgG-QD.

[Effect of Modified Chitosan Loaded with Silica on Arsenic Uptake and Transport in Rice].

Chitosan loaded with silica foliar spraying material (NCSI) was prepared using natural biomass chitosan and organic silicon and was applied to Lindao 16, Nanjing 2728, Zhenghan 10, and Nongken 58 at the rice filling stage to study the effects on arsenic (As) absorption in rice. The results showed that under a 100 µmol·L-1 pentavalent arsenic[As(Ⅴ)] hydroponic environment, foliar spraying of 30 mL NCSI on leaves promoted the accumulation of As in leaves and reduced the accumulation of As in roots and grains. Among them, the As contents of Nanjing 2728, Zhenghan 10, and Nongken 58 grains were decreased by 14.44%, 21.66%, and 10.85%, respectively, compared with those of the blank group on the 3rd day after spraying NCSI. Meanwhile, foliar spraying of NCSI improved the activities of CAT and SOD in rice leaves and increased the GSH content, indicating that the spraying of NCSI alleviated the stress of As on rice, improved the tolerance of rice to As, and reduced the toxicity of As to rice. The main mechanism of foliar application of NCSI to reduce As accumulation in rice grains may have been that NCSI induced GSH production in leaves, reducing more As(Ⅴ) to trivalent arsenic[As(Ⅲ)], thereby promoting As chelating in leaves and inhibiting As migration to grains. Therefore, foliar spraying of NCSI can be used as a foliar control technology to solve the problem of excessive As in rice and provide a scientific basis for the safe production of rice in China.

[Pharmacokinetics, tissue distribution and magnetic resonance's response characterstics of folic acid-O-carboxymethyl chitosan ultrasmall superparamagnetic iron oxide nanoparticles in mice and rats].

Folic acid-O-carboxymethyl chitosan ultrasmall superparamagnetic iron oxide nanoparticles (FA-OCMCS-USPIO-NPs) are a novel molecular targeting MR contrast agent. This paper reperts the pharmacokinetics and magnetic resonance response characteristics of FA-OCMCS-USPIO-NPs in normal rats and mice, and discussed its distributing regularity in animals, providing basis for tumor targeting imaging. O-phenanthroline method was used to determine iron content in rats' plasma and mice's organs following high and low doses of nanoparticles injected through tail vein, and the blood concentration-time curve was drawn, the calculated t1/2 of two groups were greater than 7 h. The results of tissue distribution showed that only a small part of nanoparticles were swallowed by the liver and spleen, while none in the heart, lung and kidney. At the same times, the phagocytosis of nanoparticles did not change with the dose. The results of MRI showed that renal excretion occurred 4 hours after injection, and signal to noise ratio (SNR) of liver and kidney returned to normal levels 24 hours after injection. There were no nanoparticles in the lungs. So a part of nanoparticles escaped from phagocytosis of liver and spleen, and it owned lower toxicity and longer half-life. indicated its use for tumor-targeting imaging. All of these indicated its use for tumor-targeting imaging.

A new insight on enhanced Pb(II) removal by sludge biochar catalyst coupling with ultrasound irradiation and its synergism with phenol removal.

The applicability of sludge biochar catalyst (SBC) coupling with ultrasound (US) irradiation for the simultaneous removal of Pb(II) and phenol was firstly investigated in this study. Results indicate that Pb(II) removal of SBC/US process was superior to that of SBC without US. The inhibitory order of the coexisting anions on Pb(II) removal was PO43- > HCO3- > NO3- > F- > SO42- > Cl-. Also, several coexisting metals ions inculding Cr(VI), Ni(II) and Cu(II) could be removed in a simultaneous manner with Pb(II). A high removal performance of Pb(II) by SBC/US process and its synergism with phenol oxidation had been successfully achieved. The simultaneous removal efficiencies of Pb(II) and phenol were high up to 95% within 60 min at optimum reaction conditions. Four kinds of Pb species inculding Pb0, PbCO3, PbO and Pb(OH)2 were formed during the reaction, whereas five kinds of transformation compounds of phenol such as 1,4-benzoquinone, acetic acid, formic acid, maleic acid and propionic acid were detected. Both HO and O2- contributed to the oxidation of phenol by SBC/US process, but HO was dominant radical. A reaction mechanism for the synergistic removal of Pb(II) and phenol by SBC/US process involving in four stages-namely adsorption, precipitation, reduction and Fenton-like oxidation processes was proposed. This study demonstrates that SBC/US process could be considered as a potential candidate for the remediation of real wastewaters containing Pb(II) and phenol.

Inhibition of polychlorinated dibenzo-p-dioxins and dibenzofurans by phosphorus-containing compounds in model fly ash.

Waste incineration is a preferred method in China to dispose the municipal solid waste, but controlling the production of highly toxic polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans effectively during incineration is both challenging and imperative. In this study, the suppression of PCDD/Fs by various phosphorus-containing compounds was explored, and the mechanisms responsible for the inhibition were studied in detail. The experiments took place in a lab-scale vertical tubular reactor at 350 °C under a simulated flue gas (12 vol% O2 in N2 flow), and both the off-gases and residues were collected for PCDD/Fs analysis. The scanning electron microscopy and energy-dispersive X-ray spectroscopy were used to characterize the reaction residues. The experimental results revealed that NH4H2PO4 and (NH4)2·HPO4 showed the highest inhibitory effect (57.2% and 57.3%, respectively) on the PCDD/Fs formation, followed by CaHPO4 with inhibition efficiency of 39.1%. In contrast, KH2PO4 and K2HPO4 barely inhibited the generation of the PCDD/Fs. The inhibitory effect of NH4H2PO4 and (NH4)2·HPO4 was similar to that of nitrogen-based inhibitors. At the same time, it was proven that the inhibitory activity of CaHPO4 might be due to the reaction of it with Cu2+ forming stable compounds.

Chlorophyll-Based Near-Infrared Fluorescent Nanocomposites: Preparation and Optical Properties.

Near-infrared (NIR) fluorescence has attracted much attention in biomedical fields because it offers deep tissue penetration and high spatial resolution. Herein, a method is developed for the preparation of NIR fluorescent nanocomposites (NCs) by encapsulating natural chlorophyll (Chl) into the micelles of octylamine-modified poly(acrylic acid) (OPA). Both femtosecond transient absorption spectra and isothermal titration calorimetry thermogram reveal that the micelles of OPA provide a hydrophobic environment for the improved fluorescence efficiency. Hence the resulted Chl NCs possess unique properties such as ultrasmall size, outstanding photostability, good biocompatibility, and superbright NIR fluorescence emission. In vivo imaging of sentinel lymph node is achieved in nude mice, demonstrating the potential of Chl NCs in biomedical applications. This work provides a new strategy for the preparation of highly biocompatible NIR fluorescence labeling nanocomposites.

Synergistic oxidation of Bisphenol A in a heterogeneous ultrasound-enhanced sludge biochar catalyst/persulfate process: Reactivity and mechanism.

Recently, clean-up of resistant organic compounds has attracted growing attention. In this study, a novel heterogeneous ultrasound-enhanced sludge biochar catalyst/persulfate (BC/PS/US) process was firstly developed for the degradation of bisphenol A (BPA) in water. The results revealed that BC/PS/US process could successfully achieve a positively synergistic effect between sonochemistry and catalytic chemistry on the degradation of BPA compared to its corresponding comparative process. Nearly 98% of BPA could be degraded within 80 min at optimum reaction conditions. The coexisting substances including Cl-, SO42- and NO3- had no obvious inhibition on the BPA degradation, whereas HCO3- and humic acid (HA) had significant inhibition effects on that. PS decomposition of BC/PS/US process was superior to that of BC/PS or US/PS process. Both SO4- and HO participated in the degradation of BPA, but SO4- was predominant radical in the BC/PS/US process. A possible pathway of BPA degradation was proposed, and the BPA molecule was attacked by SO4- and degraded into five kinds of intermediate products through hydroxylation and demethylation processes. This study helps to comprehend the application of sludge biochar catalyst as a persulfate activator for the degradation of organic compounds under ultrasound irradiation, and provides a new strategy in wastewater treatment.

Complete duodenal obstruction induced by groove pancreatitis: A case report.

BACKGROUND: Groove pancreatitis (GP) is a type of chronic pancreatitis occurring in an anatomic area between the duodenum, head of the pancreas, and common bile duct. Duodenal obstruction is always caused by malignant pancreatic diseases, such as pancreatic head carcinoma, while is rarely induced by benign pancreatic diseases, such as pancreatitis. CASE SUMMARY: A 39-year-old man presented with a 1-mo history of upper abdominal discomfort. His concomitant symptoms were abdominal distension, postprandial nausea, and vomiting. Contrast-enhanced computed tomography of the abdomen showed thickening of the intestinal wall with enhancement of the descending segment of the duodenum, which could not be clearly differentiated from the head of the pancreas. Upper gastrointestinal radiographs and gastrointestinal endoscopy showed a complete obstruction of the descending duodenum. An operation found that a 3-cm mass was located in the "groove part" of the pancreas and oppressing the descending duodenum. Pancreaticoduodenectomy was performed to relieve the obstruction and thoroughly remove the pancreatic lesions. The pathologic diagnosis was pancreatitis. The patient had an uneventful recovery with no complications. CONCLUSION: Because of the special location and the contracture induced by long-term chronic inflammation, our case reminds surgeons that some benign pancreatic diseases, such as GP, can also present with symptoms similar to those of pancreatic cancer. This knowledge can help to avoid an unnecessary radical operation.

[Effect of Iron on the Release of Arsenic in Flooded Paddy Soils].

Amorphous iron oxides in paddy soil are critical adsorbents of arsenic. The flooding period during rice cultivation contributes to the reductive dissolution of these amorphous iron oxides, which releases sorbed arsenic into the paddy soil solution. However, more detailed work should be conducted to evaluate quantitatively arsenic immobilization, release, and transformation regulated by metastable amorphous iron oxides. In previous studies, arsenic in the soil solution phase and solid phase were classified into F1 (exchangeable arsenic), F2 (specifically sorbed arsenic), F3 (amorphous iron oxide bound arsenic), and F4 (crystalline iron oxide bound arsenic), according to a sequential extraction procedure using reagents of increasing dissolution strength. In this study, soil samples were collected from the vicinity of a silver smelting plant in Chenzhou, Hunan Province, and the contribution of different arsenic speciation (F1, F2, F3, and F4) to arsenic release during anaerobic enrichment incubation of paddy soil was investigated. Sample analysis was conducted at the end of the first phase (day 15) and the second phase (day 30). The effects of amorphous iron oxides in paddy soil on migration and transformation of arsenic were discussed. Results showed significant elevation of dissolved Fe(Ⅱ) and arsenic concentration (P<0.05) in enrichment solutions in the second phase compared with that in the first phase. Arsenic released in the soil solution in both phases originated from exchangeable arsenic and specifically sorbed arsenic, as indicated by its significantly positive correlation with F1 and F2 (r=0.73, P<0.05; r=0.657, P<0.05). However, an insignificant positive correlation was found between the arsenic released and F3. Moreover, HCl-extractable Fe(Ⅱ) was significantly and positively correlated with arsenic (r=0.577, P<0.05; r=0.613, P<0.05), while amorphous iron oxides were significantly and negatively correlated with arsenic (r=-0.428, P=0.126; r=-0.564, P<0.05). In conclusion, arsenic in the F1 and F2 fractions acted as the major source of released arsenic. Despite elevated levels of HCl-extractable Fe(Ⅱ) that might result from the slight reductive dissolution of amorphous iron oxide, the significant negative correlation between dissolved arsenic and amorphous iron oxides indicated that metastable amorphous iron oxides in anaerobic paddy soil can generally sorb dissolved arsenic effectively, resulting in lower mobility of arsenic. Increasing the level of amorphous iron oxides in paddy soil is conducive to inactivation of arsenic.

[Effect of Calcium Silicate-biological Humus Fertilizer Composite on Uptake of Cd by Shallots from Contaminated Agricultural Soil].

The safety of vegetable production is a key link in reducing cadmium consumption through the food chains. Field experiments were conducted to investigate the effects of composite materials (calcium silicate-biological humus fertilizer) on the growth of shallots and the uptake of Cd by shallots from contaminated agricultural soil. Four treatments (T1: 0.5% calcium silicate+0.5% biological humus fertilizer; T2: 0.5% calcium silicate+1.0% biological humus fertilizer; T3: 1.0% calcium silicate+0.5% biological humus fertilizer; and T4: 1.0% calcium silicate+1.0% biological humus fertilizer) and a control group (CK) were adopted. The changes in soil pH, DTPA-extractable Cd, biomass of shallots, and cadmium concentrations in shallots over time under different treatments were analyzed. The results show that the application of composite amendments decreased the concentrations of DTPA-extractable Cd in the soil. In particular, after T3 treatment, the concentrations of soil DTPA-extractable Cd decreased by 60.71%, 49.54%, 44.63%, and 58.94% after 14, 28, 42, and 56 d, respectively. The biomass of the shallots aboveground increased significantly by 107.99% and 107.19% after T3 and T4 treatment, respectively. The composite amendments exhibited different effects on the uptake of Cd by the shallots from the soil, and the T4 treatment was the most effective in immobilizing Cd and inhibiting translocation of Cd into the shallots. The cadmium concentration in the shallots decreased by 43.80% after 56 d with the T4 treatment. In conclusion, T4 is the optimum treatment for soil cadmium immobilization.