Nondestructive separation/enrichment and rolling circle amplification-powered sensitive SERS enumeration of circulating tumor cells via aptamer recognition.

Nondestructive separation/enrichment and reliable detection of extremely rare circulating tumor cells (CTCs) in peripheral blood are of considerable importance in tumor precision diagnosis and treatment, yet this remains a big challenge. Herein, a novel strategy for nondestructive separation/enrichment and ultra-sensitive surface-enhanced Raman scattering (SERS)-based enumeration of CTCs is proposed via aptamer recognition and rolling circle amplification (RCA). In this work the magnetic beads modified with "Aptamer (Apt)-Primer" (AP) probes were utilized to specifically capture CTCs, and then after magnetic separation/enrichment, the RCA-powered SERS counting and benzonase nuclease cleavage-assisted nondestructive release of CTCs were realized, respectively. The AP was assembled by hybridizing the EpCAM-specific aptamer with a primer, and the optimal AP contains 4 mismatched bases. The RCA enhanced SERS signal nearly 4.5-fold, and the SERS strategy has good specificity, uniformity and reproducibility. The proposed SERS detection possesses a good linear relationship with the concentration of MCF-7 cells spiked in PBS with the limit of detection (LOD) of 2 cells/mL, which shows good potential practicality for detecting CTCs in blood with recoveries ranging from 100.56% to 116.78%. Besides, the released CTCs remained good cellular activity with the normal proliferation after re-culture for 48 h and normal growth for at least three generations. The proposed strategy of nondestructive separation/enrichment and SERS-based sensitive enumeration is promising for reliable analysis of EpCAM-positive CTCs in blood, which is expected to provide a powerful tool for analysis of extremely rare circulating tumor cells in complex peripheral blood for liquid biopsy.

Double-Tetrahedral DNA Probe Functionalized Ag Nanorod Biointerface for Effective Capture, Highly Sensitive Detection, and Nondestructive Release of Circulating Tumor Cells.

Circulating tumor cells (CTCs) are indicative of tumorigenesis, metastasis, and recurrence; however, it is still a great challenge to efficiently analyze the extremely rare CTCs in peripheral blood. Herein, a novel nanobiointerface integrating high affinities of arrayed silver nanorods (Ag NRs) and double-tetrahedral DNA (DTDN) probes by a clever strategy is proposed for the efficient capture, highly sensitive detection, and nondestructive release of CTCs. Under the optimal conditions, the DTDN-probe-functionalized Ag NRs nanobiointerface can capture 90.2% of SGC-7901 cells in PBS, and the capture efficiency is 2.8 times and 50 times those of a DTDN-probe-functionalized Ag film and unfunctionalized Ag NRs, respectively, benefiting from the nanorough interface of the Ag NRs array and multivalent recognition of the DTDN probe. In addition, 93.4% of cells was released via Zn2+-assisted DNAzyme cleavage, and the viability of the postreleased CTCs is about 98.0%. The potential practicality of the nanobiointerface for testing CTCs in blood was further characterized by spiking SGC-7901 cells in leukocytes collected from human blood, and the results show that 83.8% capture efficiency, 91.2% release efficiency, and single-cell detection limit were achieved, which indicates that the nanobiointerface has great potential in clinical applications for reliable CTC analyses.

DNA walker-powered ratiometric SERS cytosensor of circulating tumor cells with single-cell sensitivity.

Identification and detection of extreme rare circulating tumor cells (CTCs) in peripheral blood can precisely monitor cancer recurrence and metastasis, however, how to ultra-sensitively and reliably detect CTCs is a big challenge. In this work, a ratiometric surface-enhanced Raman spectroscopy (SERS)-based strategy for ultra-sensitively and nondestructively detecting CTCs was proposed via CTCs-triggered DNA walker-assisted assembly of plasmonic nanostructure networks consisting of Walker probes and SERS tags. The Walker probes were prepared by modifying Fe3O4@SiO2@Au nanoparticles (GMNPs) with ROX-labeled EpCAM aptamer-blocked Zn2+-specific DNAzyme and hairpin-structured single-stranded DNAs H1, and the SERS tags were constructed by co-labelling hairpin-structured single-stranded DNAs H2 and Raman molecules (DTNB) on Au NPs. The aptamers can recognize EpCAM-positive CTCs via the specific binding to EpCAM, so that the activity of DNAzymes is activated with the assistance of Zn2+ to launch the DNA walker to move around for the cleavage of H1 on GMNPs. The residual fragments of H1 on GMNPs can hybridize with H2 on SERS tags and result in the formation of Walker probe-SERS tag network nanostructures (Nw NSs) with rich SERS hot spots. The reliable SERS detection of CTCs is achieved by the stable ratiometric SERS signals of DTNB and ROX generated from the Nw NSs, and a good linear relation between ratiometric SERS signal and MCF-7 cells concentration was obtained with the detection limit low to 1 cell/mL. The recovery rate of MCF-7 cells in peripheral blood is in the range of 94.0%-104.5%, which indicates a good application prospect of the novel ratiometric SERS cytosensor in the clinic detection of EpCAM-positive CTCs.

PD-1 Inhibitor-Induced Thyrotoxicosis Associated with Coronary Artery Spasm and Ventricular Tachycardia.

Programmed cell death protein 1 (PD-1) inhibitors open a new era of cancer immunotherapy, but they are associated with immune-related adverse events (irAEs) involving multiple endocrine organs of which thyroid dysfunction is the most common An uncommon condition of coronary artery spasm and ventricular tachycardia associated with thyrotoxicosis, induced by a PD-1 inhibitor, is discussed in this case. A 60-year-old male patient with a 1-week history of chest tightness and palpitation at rest was referred to us in July 2021. No obvious abnormalities were noted on physical examination and electrocardiography. He was being treated with a PD-1 inhibitor (camrelizumab, 200 mg) for lung metastasis of liver cancer; treatment stopped because he was found to have hyperthyroidism. Holter recorded intermittent STsegment arch back raised 0.5-14 mm upward lasting for 1-5 min, accompanied by ventricular tachycardia. He was treated with antivasospasm drugs (isosorbide mononitrate and diltiazem). Thyroid function was reexamined and revealed elevated FT3 and FT4 levels, decreased TSH levels, and negative thyroid-associated antibodies. After antivasospasm treatment and iodine taboo diet, his symptoms were relieved, and ST-segment elevation and ventricular tachycardia were disappeared. This case adds to our knowledge of the association between coronary artery spasms and thyrotoxicosis, which is an irAE induced by a PD-1 inhibitor. Patients treated with PD-1 inhibitors need regular follow-ups for cardiac complications, especially those with a history of heart disease.

Microalgal Activity and Nutrient Uptake from Wastewater Enhanced by Nanoscale Zerovalent Iron: Performance and Molecular Mechanism.

Microalgae-based bioremediation presents an alternative to traditional biological wastewater treatment. However, its efficiency is still challenging due to low microalgal activities and growth rate in wastewater. Iron plays an important role in microbial metabolism and is effective to stimulate microbial growth. In this study, a novel approach was proposed to simultaneously promote microalgal activity and nutrient uptake from wastewater using nanoscale zerovalent iron (nZVI), and the underlying molecular mechanism was explored. Compared to the control, 0.05 mg/L of nZVI significantly enhanced biomass production by 113.3% as well as NH4+-N and PO43--P uptake rates by 32.2% and 75.0%, respectively. These observations were attributed to the enhanced metabolic pathways and intracellular regulations. Specifically, nZVI alleviated the cellular oxidative stress via decreased peroxisome biogenesis as indicated by reduced reactive oxygen species, enzymes, and genes involved. nZVI promoted ammonium assimilation, phosphate metabolism, carbon fixation, and energy generation. Moreover, nZVI regulated the biosynthesis and conversions of intracellular biocomposition, leading to increased carotenoid, carbohydrate, and lipid productions and decreased protein and fatty acid yields. The above metabolisms were supported by the regulations of differentially expressed genes involved. This study provided an nZVI-based approach and molecular mechanism for enhancing microalgal activities and nutrient uptake from wastewater.

Architectural Genesis of Metal(loid)s with Iron Nanoparticle in Water.

Reactions of core-shell iron nanoparticles with metal(loid)s in water can form an array of nanostructures such as Ag-seed/dendrite, As-subshell, U-yolk, Co-hollowshell, and Cs-spot. Nonetheless, there is a lack of profound understanding in the genesis of these amazing geometries. Herein, we propose a concept to unravel the interdiffusion between the core-shell iron nanoparticle and metal(loid)s, where several key interactions including the Kirkendall effect, metal(loid) character effect, and reaction condition effect are involved in determining the structure of the final solid reaction products. Particularly, the architectural growths of metal(loid)s with iron nanoparticles in water can be manipulated mutually or singly by the following factors: standard redox potential difference, magnetic property, electrical charge and conductivity, as well as the iron (hydr)oxide shell structure under different solution chemistry and operation conditions. This contribution provides a theoretical basis to rationalize the architectural genesis of various metal(loid)s with iron nanoparticles, which will benefit the real practice for synthesizing functional iron-based nanoparticles and recovering the rare/precious metal(loid)s by iron nanoparticles from water.

Sulfidation of zerovalent iron for improving the selectivity toward Cr(VI) in oxic water: Involvements of FeSx.

Recognition of the general roles of FeSx in selectivity of zerovalent iron (ZVI) toward target contaminants is of great significance but challenging, especially in oxic water system. Herein, the ZVI amended with Na2S2O3 (i.e., S-ZVINa2S2O3) and Na2S2O4 (i.e., S-ZVINa2S2O4) were applied for the sequestration of Cr(VI) and corresponding FeSx involvements were explored. Results revealed that the largest effect for S-ZVINa2S2O3 and S-ZVINa2S2O4 observed at S/Fe molar ratio of 0.05 were 7.9- and 11.6- folds increase in removal rate (kobs) of Cr(VI), respectively. respectively. Correspondingly, the electron efficiency (EE) of S-ZVI for reducing Cr(VI) were mainly from 2.1- to 2.4- folds greater than that that of the ZVIH2O. Further, this work suggested that the improved selectivity of ZVI toward Cr(VI) by sulfidation should be mainly ascribed to the involvements of FeSx, which could tune the reactive sites and corrosion products of ZVI for synergistically improving the mass transfer of Cr(VI) and subsequent electron transfer from iron core to Cr(VI). Overall, this work offers a new platform for improving ZVI selectivity for water decontamination.

Weak magnetic field enables high selectivity of zerovalent iron toward metalloid oxyanions under aerobic conditions.

For water treatment/remediation by zerovalent iron (ZVI), of particular concern is its selectivity toward contaminants over natural non-targets (e.g., O2 and H2O/H+). Hence, the effects of weak magnetic field (WMF) on the selectivity of ZVI toward metalloid oxyanions (i.e., As(III), As(V), Sb(III), Sb(V), Se(IV) and Se(VI)) were in-depth investigated under aerobic conditions. This study unraveled that, despite the electron utilization (EU) of ZVI with and without WMF were almost identical at reaction equilibrium, the application of a WMF could enhance the specific removal capacity (SRC) of ZVI toward metalloid oxyanions from 1.8-19.0 mg/g Fe to 12.6-85.3 mg/g Fe. Particularly, the electron efficiency (EE) of ZVI with WMF for reduction of Se(IV)/Se(VI) were 3.7- to 14.1-fold greater than that without WMF. Since the WMF-induced magnetic gradient force (FΔB) can derive the movement of both Fe2+ and metalloid oxyanions, the subsequent incorporation of metalloid oxyanions with in-situ generated iron oxides can also been mediated synchronously and thus leading to an enhanced SRC of ZVI (also EE for Se(IV) and Se(VI) reduction by ZVI). In general, our findings prove that WMF should be a promising method to promote the selectivity of ZVI for water decontamination under aerobic conditions.

Kidney-secreted erythropoietin lowers lipidemia via activating JAK2-STAT5 signaling in adipose tissue.

BACKGROUND: Dyslipidemia is commonly observed in various kidney diseases, renal specific secreted erythropoietin (EPO) may participate in this process. However, how this process is regulated remains elusive. METHOD: Dyslipidemia was evaluated in chronic kidney disease and ischemia kidney injury animal model. Primary cultured adipocytes were harvested to investigate the lipid metabolic effect of EPO. Lipidemia was evaluated in EPO treated animals. Blood samples from cardiac surgery-induced kidney injury patient were collected to assess correlationship between EPO and lipidemia. FINDINGS: We found a decrease in secreted EPO and hypertriglyceridemia in chronic kidney disease (CKD) mice. In contrast, in renal ischemia animal model, increased EPO triggered by hypoxia signaling activation, was accompanied by decreased triglyceride (TG) in serum. Mechanistically, circulating EPO modulated JAK2-STAT5 signaling, which in turn enhanced lipid catabolism in peripheral adipose tissue and contributed to dysregulated lipidemia. Delivering of recombinant EPO into both wild type and CKD mice suppressed TG in serum by accelerating lipid catabolism in adipose tissue. In a cohort of patients diagnosed with acute kidney injury after cardiopulmonary bypass surgery, the decreased TG and cholesterol negatively correlated with increased EPO in serum. INTERPRETATION: This study depicted a new mechanism by which renal secreted EPO controlled lipidemia in kidney diseases including chronic kidney disease. Circulating EPO stimulated lipid catabolism by targeting JAK2-STATA5 signaling in peripheral adipose tissue, providing new therapeutic target for dyslipidemia treatment. FUNDING: This work was supported by grants from the National Natural Science Foundation of China (Nos. 81700640 and 81970608).

[Observation of electroacupuncture intervention on cell apoptosis and Bax and Bcl-2 expression in cerebral and myocardial tissues in cerebral ischemia rats based on "heart-brain correlation" theory].

OBJECTIVE: To compare the effect of electroacupuncture (EA) of "Neiguan" (PC6) of the Pericardium Meridian, "Shenmen" (HT7) of the Heart Meridian，"Shuigou" (GV26) of the Governor Vessel and "Zhaohai" (KI6) of the Kidney Meridian on myocardial and cerebral cell apoptosis in cerebral ischemia (CI) rats, so as to explore its mechanism underlying improvement of CI based on the theory of "Heart-brain Correlation". METHODS: Forty-eight SD rats (half male and half female) were randomly divided into normal control, model, PC6, HT7, GV26 and KI6 groups (n＝8 in each one). The CI model was established by occlusion of the middle cerebral artery (MCAO). EA (4 Hz/20 Hz, 1.5 mA) was applied to the right PC6, HT7, GV26 or KI6 respectively for 30 min, once every 12 h for 5 times. The cell apoptosis of the ischemic myocardial and cerebral tissues was detected by TUNEL method, and the expression of cerebral and myocardial Bax and Bcl-2 was determined by using immunohistochemistry. RESULTS: Following modeling, the cell apoptosis percentages and Bax-positive cells of both myocardial and cerebral tissues were significantly increased in the model group in comparison with the control group (P<0.01). After EA intervention, the cerebral apoptotic percentage and cerebral Bax-positive cells in the cerebral tissue of the PC6, HT7 and GV26 groups, and the myocardial apoptosis percentage in the PC6 and HT7 groups, as well as the myocardial Bax-positive cells in the PC6 group were obviously decreased (P<0.05, P<0.01), while the cerebral Bcl-2 positive cells in the PC6, HT7 and GV26 groups, and the myocardial Bcl-2 positive cells in the PC6 and HT7 groups were significantly increased relevant to the model group (P<0.01, P<0.05). No significant changes were found in the KI 6 group in the cell apoptosis index and percentages and Bax- and Bcl-2-positive cells of both myocardium and cerebral cortex tissues compared with the model group (P>0.05)．. CONCLUSION: EA stimulation of PC6 and HT7 can inhibit CI injury induced cell apoptosis of cerebral and myocardial tissues in CI rats, which is possibly associated with its effects in down-regulating Bax expression and up-regulating Bcl-2 expression of both myocardial and cerebral tissues.

Isolation and phylogenetic analysis of an emerging Senecavirus A in China, 2017.

Senecavirus A (SVA), which is associated with porcine vesicular disease and high mortality in neonatal piglets, is a small non-enveloped RNA virus and a member of Picornaviridae family. An emerging SVA strain, named SVA CH/FuJ/2017, was isolated from vesicular liquid and vesicular lesion tissue from piglets with vesicular disease in Fujian province, China. In our study, the complete genome sequence of SVA CH/FuJ/2017 strain has been determined. The viral genome was 7285 nt in length. The homology analysis indicated that the gene sequences of polyprotein and VP1 in SVA CH/FuJ/2017 shared highest nucleotide identities with American SVA isolates; and polyprotein showed the highest similarity with American SVA isolates. The phylogenetic analysis based on polyprotein and VP1 nucleotide sequences indicated that SVA CH/FuJ/2017 was closely related to American SVA isolates. The results revealed that the novel SVA strain was closely related to those SVA strains that were isolated in America. Hence, the retrospective study is important for tracing the probable origin of China SVA strains.

Characterization methods of zerovalent iron for water treatment and remediation.

Appropriately selecting methods for characterizing the reaction system of zerovalent iron (ZVI) favors its application for water treatment and remediation. Hence, a survey of the available ZVI characterization techniques used in laboratory and field studies are presented in this review for clarifying the characteristic properties, (in-situ) corrosion processes, and corrosion products of ZVI system. The methods are generally classified into four broad categories: morphology characterization techniques, (sub-)surface and bulk analysis mainly via the spectral protocols, along with the (physio)electrochemical alternatives. Moreover, this paper provides a critical review on the scopes and applications of ZVI characterization methodologies from several perspectives including their suitable occasions, availability, (semi-)quantitative/qualitative evaluations, in/ex-situ reaction information, advantages, limitations and challenges, as well as economic and technical remarks. In particular, the characteristic spectroscopic peak locations of typical iron (oxyhydr)oxides are also systematically summarized. In view of the complexity and variety of ZVI system, this review further addresses that different characterization methods should be employed together for better assessing the performance and mechanisms of ZVI-involved systems and thereby facilitating the deployment of ZVI-based installations in real practice.

LncRNA NEAT1 promotes colorectal cancer cell proliferation and migration via regulating glial cell-derived neurotrophic factor by sponging miR-196a-5p.

Colorectal cancer (CRC) is the one of the most common malignant tumors worldwide. Recent years, widespread long non-coding RNAs (lncRNAs) have been discovered and are known to regulate gene expression in cancers. However, the roles and underlying mechanisms of lncRNA in CRC remain largely unclear. Here, we firstly revealed that repression of lncRNA nuclear paraspeckle assembly transcript 1 (NEAT1) inhibited cell proliferation and migration in HCT116 cells and overexpression of NEAT1 promoted cell proliferation and migration in SW480 cells using CCK8 assay and transwell assay. Then, we found that suppression of NEAT1 increased the miR-196a-5p expression in HCT116 cells, while elevation of NEAT1 decreased the miR-196a-5p expression in SW480 cells using qPCR assay. Furthermore, miR-196a-5p could bind to the predicted binding site of NEAT1. We then found that miR-196a-5p was involved in the role of NEAT1 in CRCs. In addition, we demonstrated that miR-196a-5p mimics inhibited the glial cell-derived neurotrophic factor (GDNF) expression in HCT116 cells and meanwhile, miR-196a-5p inhibitor promoted GDNF expression in SW480 cells using qPCR and western blot analysis. Then, we proved that miR-196a-5p exerted its function via regulating GDNF expression in CRCs. Ultimately, our study demonstrated that NEAT1 exerted its role via miR-196a-5p/GDNF axis in CRCs. In summary, this work provided the first evidence of a NEAT1/miR-196a-5p/GDNF regulatory pathway in CRC.

Enhanced Reactivity and Electron Selectivity of Sulfidated Zerovalent Iron toward Chromate under Aerobic Conditions.

When zerovalent iron (ZVI) is used in reductive removal of contaminants from industrial wastewater, where dissolved oxygen (DO) competes with target contaminant for the electrons donated by ZVI, both the reactivity and the electron selectivity (ES) of ZVI toward target contaminant are critical. Thus, the reactivity and ES of two sulfidated ZVI (S-ZVI) samples, synthesized by ball-milling with elemental sulfur (S-ZVIbm) and reacting with Na2S (S-ZVINa2S), toward Cr(VI) under aerobic conditions were investigated. Sulfidation appreciably increased the reactivity of ZVI and the ratio of the rate constants for Cr(VI) removal by S-ZVIbm or S-ZVINa2S to their counterparts without sulfur fell in the range of 1.4-29.9. ES of S-ZVIbm and S-ZVINa2S toward Cr(VI) were determined to be 14.6% and 13.3%, which were 10.7- and 7.5-fold greater than that without sulfidation, respectively. This was mainly ascribed to the greater improving effect of sulfidation on the reduction rate of Cr(VI) than that of DO by ZVI. The improving effects of sulfidation on the performance of ZVI were mainly due to the following mechanisms: sulfidation increased the specific surface area of ZVI, the FeS x layer facilitated the enrichment of Cr(VI) anions on S-ZVI surface because of its anions selective property and favored the electron transfer from Fe0 core to Cr(VI) at the surface because of its role as efficient electron conductor.

Advances in Sulfidation of Zerovalent Iron for Water Decontamination.

Sulfidation has gained increasing interest in recent years for improving the sequestration of contaminants by zerovalent iron (ZVI). In view of the bright prospects of the sulfidated ZVI (S-ZVI), this review comprehensively summarized the latest developments in sulfidation of ZVI, particularly that of nanoscale ZVI (S-nZVI). The milestones in development of S-ZVI technology including its background, enlightenment, synthesis, characterization, water remediation and treatment, etc., are summarized. Under most circumstances, sulfidation can enhance the sequestration of various organic compounds and metal(loid)s by ZVI to various extents. In particular, the reactivity of S-ZVI toward contaminants is strongly dependent on S/Fe molar ratio, sulfidation method, and solution chemistry. Additionally, sulfidation can improve the selectivity of ZVI toward targeted contaminant over water under anaerobic conditions. The mechanisms of sulfidation-induced improvement in contaminants sequestration by ZVI are also summarized. Finally, this review identifies the current knowledge gaps and future research needs of S-ZVI for environmental application.

Photothermal therapy of single cancer cells mediated by naturally created gold nanorod clusters.

Gold nanorods (GNRs) are generally considered to be nontoxic to normal and cancer cells. They are usually accumulated at lysosomes after entering into cells, forming GNR clusters in which strong plasmonic coupling between GNRs is expected. We investigated the photothermal therapy of single cancer cells by exploiting the significantly enhanced two-photon-induced absorption of GNR clusters naturally created in the lysosomes of cancer cells. It was revealed numerically that the plasmonic coupling between GNRs in GNR clusters can effectively enhance the photothermal conversion efficiency. As a result, the thermal damage of single cancer cells can be induced by using pulse energy as low as ~70 pJ. In experiments, the locations of GNR clusters can be accurately determined through the detection of the two-photon-induced luminescence, which is also significantly enhanced, by using a confocal laser scanning microscope. The photothermal therapy was conducted by focusing femtosecond laser light on the targeted GNR clusters, generating bubbles and deforming cell membranes. The photothermal therapy proposed in this work can lead to the rapid and acute injury of single cancer cells. The dependence of the apoptosis time on the pulse energy of femtosecond laser light was also examined. Our findings suggest a novel strategy for the photothermal therapy of single cancer cells with ultralow energy.

Development of Palliative Care in China: A Tale of Three Cities.

BACKGROUND: China is the most populous country in the world, but access to palliative care is extremely limited. A better understanding of the development of palliative care programs in China and how they overcome the barriers to provide services would inform how we can further integrate palliative care into oncology practices in China. Here, we describe the program development and infrastructure of the palliative care programs at three Chinese institutions, using these as examples to discuss strategies to accelerate palliative care access for cancer patients in China. METHODS: Case study of three palliative care programs in Chengdu, Kunming, and Beijing. RESULTS: The three examples of palliative care delivery in China ranged from a comprehensive program that includes all major branches of palliative care in Chengdu, a program that is predominantly inpatient-based in Kunming, and a smaller program at an earlier stage of development in Beijing. Despite the numerous challenges related to the limited training opportunities, stigma on death and dying, and lack of resources and policies to support clinical practice, these programs were able to overcome many barriers to offer palliative care services to patients with advanced diseases and to advance this discipline in China through visionary leadership, collaboration with other countries to acquire palliative care expertise, committed staff members, and persistence. CONCLUSION: Palliative care is limited in China, although a few comprehensive programs exist. Our findings may inform palliative care program development in other Chinese hospitals. IMPLICATIONS FOR PRACTICE: With a population of 1.3 billion, China is the most populous country in the world, and cancer is the leading cause of death. However, only 0.7% of hospitals offer palliative care services, which significantly limits palliative care access for Chinese cancer patients. Here, we describe the program development and infrastructure of three palliative care programs in China, using these as examples to discuss how they were able to overcome various barriers to implement palliative care. Lessons from these programs may help to accelerate the progress of palliative cancer care in China.

Coupled Effect of Ferrous Ion and Oxygen on the Electron Selectivity of Zerovalent Iron for Selenate Sequestration.

Although the electron selectivity (ES) of zerovalent iron (ZVI) for target contaminant and its utilization ratio (UR) decide the removal capacity of ZVI, little effort has been made to improve them. Taking selenate [Se(VI)] as a target contaminant, this study investigated the coupled influence of aeration gas and Fe(II) on the ES and UR of ZVI. Oxygen was necessary for effective removal of Se(VI) by ZVI without Fe(II) addition. Due to the application of 1.0 mM Fe(II), the ES of ZVI was increased from 3.2-3.6% to 6.2-6.8% and the UR of ZVI was improved by 5.0-19.4% under aerobic conditions, which resulted in a 100-180% increase in the Se(VI) removal capacity by ZVI. Se(VI) reduction by Fe0 was a heterogeneous redox reaction, and the enrichment of Se(VI) on ZVI surface was the first step of electron transfer from Fe0 core to Se(VI). Oxygen promoted the generation of iron (hydr)oxides, which facilitated the enrichment of Se(VI) on the ZVI particle surface. Therefore, the high oxygen fraction (25-50%) in the purging gas resulted in only a slight decrease in the ES of ZVI. Fe(II) addition resulted in a pH drop and promoted the generation of lepidocrocite and magnetite, which benefited Se(VI) adsorption and the following electron transfer from underlying Fe0 to surface-located Se(VI).

Combined Effect of Weak Magnetic Fields and Anions on Arsenite Sequestration by Zerovalent Iron: Kinetics and Mechanisms.

In this study, the effects of major anions (e.g., ClO4-, NO3-, Cl-, and SO42-) in water on the reactivity of zerovalent iron (ZVI) toward As(III) sequestration were evaluated with and without a weak magnetic field (WMF). Without WMF, ClO4- and NO3- had negligible influence on As(III) removal by ZVI, but Cl- and SO42- could improve As(III) sequestration by ZVI. Moreover, the WMF-enhancing effect on As(III) removal by ZVI was minor in ultrapure water. A synergetic effect of WMF and individual anion on improving As(III) removal by ZVI was observed for each of the investigated anion, which became more pronounced as the concentration of anion increased. Based on the extent of enhancing effects, these anions were ranked in the order of SO42- > Cl- > NO3- ≈ ClO4- (from most- to least-enhanced). Furthermore, the inhibitory effect of HSiO3-, HCO3-, and H2PO4- on ZVI corrosion could be alleviated taking advantage of the combined effect of WMF and SO42-. The coupled influence of anions and WMF was associated with the simultaneous movement of anions with paramagnetic Fe2+ to keep local electroneutrality in solution. Our findings suggest that the presence of anions is quite essential to maintaining or stimulating the WMF effect.

Aging of Zerovalent Iron in Synthetic Groundwater: X-ray Photoelectron Spectroscopy Depth Profiling Characterization and Depassivation with Uniform Magnetic Field.

Scanning electron microscopy (SEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) depth profiling were employed to characterize the aged zerovalent iron (AZVI) samples incubated in synthetic groundwater. The AZVI samples prepared under different conditions exhibited the passive layers of different morphologies, amounts, and constituents. Owing to the accumulation of iron oxides on their surface, all the prepared AZVI samples were much less reactive than the pristine ZVI for Se(IV) removal. However, the reactivity of all AZVI samples toward Se(IV) sequestration could be significantly enhanced by applying a uniform magnetic field (UMF). Moreover, the flux intensity of UMF necessary to depassivate an AZVI sample was strongly dependent on the properties of its passive layer. The UMF of 1 mT was strong enough to restore the reactivity of the AZVI samples with Fe3O4 as the major constituent of the passive film or with a thin layer of α-Fe2O3 and γ-FeOOH in the external passive film. The flux intensity of UMF necessary to depassivate the AZVI samples would increase to 2 mT or even 5 mT if the AZVI samples were covered with passive films being thicker, denser, and contained more γ-FeOOH and α-Fe2O3. Furthermore, increasing the flux intensity of UMF facilitated the reduction of Se(IV) to Se(0) by AZVI samples.