Kinetic Modeling of the Anodic Degradation of Ni-EDTA Complexes: Insights into the Reaction Mechanism and Products

In this study, an electrochemical advanced oxidation process (EAOP) was employed to effectively degrade complexes of nickel and ethylenediaminetetraacetic acid (EDTA) present in electroless nickel plating wastewaters. Our results show that Ni-EDTA complexes can be effectively degraded by an EAOP with degradation of the complexes occurring at/near the anode surface via interaction with hydroxyl radicals generated on water splitting. Our results further show that the rate of Ni-EDTA degradation is not a function of the rate of any particular chemical reaction but, rather, is controlled by the rate of transport of Ni-EDTA to the anode surface. The oxidation of EDTA to smaller noncomplexing entities releases Ni2+, which is subsequently deposited onto the cathode as Ni0. While complete Ni-EDTA removal and Ni recovery are achieved within 2 h, the overall TOC removal by EAOP is limited, with only 50% TOC removal achieved after 2 h of treatment. The low affinity of small molecular weight EDTA degradation products (such as formic acid, glycine, oxamic acid, and acetic acid) for the anode surface limits oxidation of these compounds and overall TOC removal by the anodic oxidation process. We have developed a mathematical kinetic model that satisfactorily describes Ni-EDTA removal, Ni recovery, and TOC removal over a range of Ni and EDTA concentrations and provides a good description of the oxidation of various EDTA degradation intermediates. The mathematical model developed here, when coupled with the hydrodynamics of the electrochemical cell using a computational fluid dynamics tool, can assist in both cell design and the selection of operating parameters such that the performance of the EAOP process for Ni-EDTA degradation and TOC removal is optimized

Decreasing Nitrogen Fertilizer Input Had Little Effect on Microbial Communities in Three Types of Soils

<div><p>In this study, we examined the influence of different nitrogen (N) application rates (0, 168, 240, 270 and 312 kg N ha^-1) on soil properties, maize (<i>Zea mays</i> L.) yields and microbial communities of three types of soils (clay, alluvial and sandy soils). Phospholipid fatty acid analysis was used to characterize soil microbial communities. Results indicated that N fertilization significantly decreased microbial biomass in both clay and sandy soils regardless of application rate. These decreases were more likely a result of soil pH decreases induced by N fertilization, especially in the sandy soils. This is supported by structural equation modeling and redundancy analysis results. Nitrogen fertilization also led to significant changes in soil microbial community composition. However, the change differences were gradually dismissed with increase in N application rate. We also observed that N fertilization increased maize yields to the same level regardless of application rate. This suggests that farmers could apply N fertilizers at a lower rate (i.e. 168 kg N ha^-1), which could achieve high maize yield on one hand while maintain soil microbial functions on the other hand.</p></div

Helminth antigens downregulated surface maturation markers on BMDMs.

<p>BMDMs were pulsed with medium alone, PL at 25/ml, LPS at 10 ng/ml, or PL at 25 ug/ml twenty min prior to the addition of LPS to a final concentration of 10 ng/ml in the medium (PL+LPS) and cultured for a total of 20–24 h period. BMDMs were harvested and FACS analysis was performed to measure surface expression of MHC-II, CD80, and CD86. Dotted line in the histogram shows control staining with isotype/fluorochrome control Ab, and filled line shows signal with specific Ab.</p

Helminth antigens impairment of TRPC1-STIM1 channel assembly.

<p>Co-immunoprecipitation of TRPC1 and STIM1 from BMDMs in resting, LPS-, and Tg-stimulations. A) Cells were pulsed with medium alone, PL at 25 ug/ml, LPS at 10 ng/ml, or PL before the addition of LPS to the medium. B) Cells were pulsed with medium alone, PL at 25 ug/ml, Tg at 2 µM, or PL before the addition of Tg to the medium. Immunoprecipitation of TRPC1-STIM1 complex from cell was prepared by using Anti-STIM1 Ab. Anti-TRPC1 was used for western blot detection in both Fig. 8 A and B. The average pixel intensity of the respective bands from three independent experiments was measured. This was done using the imaging software Quality One-4.6.7 (Bio-Rad).</p

Infiltrating myeloid cells display reduced expression of surface maturation markers during murine NCC.

<p><i>In-situ</i> IF staining was performed on frozen sections of HBSS infected (mock) and parasite infected brains of mice at 1 wk and 2 wk p.i. Brain cryosections were analyzed for expression of maturation markers MHC II, CD80, and CD86 using fluorochrome conjugated antibodies (red-PE) and macrophages specific marker CD11b (green-Alexa 488). Nuclear staining DAPI is depicted in blue. Staining for these maturation markers MHC-II (A1), CD80 (B1), and CD86 (C1) was undetected/barely detected in mock infected mice. Parasite infected mice brains displayed large number of infiltrating myeloid cells stained positive for CD11b (A2–A3, B2–B3, and C2–C3). MHC-II was undetected in many of the CD11b+ accumulated cells in the CNS of NCC mice at both 1 wk (A2) and 2 wk p.i. (A3) (arrow). CD80 (B2–B3) and Cd86 (C2–C3) were undetected/barely detected in the CD11b+ myeloid cells around the parasite (P) in the CNS of NCC mice both at 1 wk and 2 wk p.i. Results are from one representative experiment of atleast three independent experiments (n = 4 per each time point).</p

Helminth antigens inhibit Tg induced Ca²⁺ release and Ca²⁺ entry.

<p>Fura 2 fluorescence measurements in J774 cells. Cells were pulsed with medium alone, Tg at 1/ml for 20 mins before the addition of LPS to the medium. Analog plots of the fluorescence ratio (340/380) from an average of 0- 50 cells are shown in (A) and (B). (C) The bar graph indicates the average data on calcium release (first peak) and calcium entry (second peak) under these conditions. ** indicate significance (p = <0.01). (D) Inward currents were induced upon store depletion at −80 mV in control and PL treated cells Respectively IV curves under these conditions are shown in (E). Average (8–10 recordings current intensity at −80 mV are shown in (F). * indicate significance (p = <0.05).</p

Helminth antigens inhibit LPS induced Ca²⁺ release and Ca²⁺ entry.

<p>Fura 2 fluorescence measurements in J774 cells. Cells were pulsed with medium alone, LPS at 10/ml, or pretreat PL at 25 ug/ml for 20 min before the addition of LPS to the medium. Analog plots of the fluorescence ratio (340/380) from an average of 0–50 cells are shown in (A) and (B). (C) The bar graph indicates the average data on calcium release (first peak) and calcium entry (second peak) under these conditions. ** indicate significance (p = <0.01). (D) Application LPS in bath solution induced inward currents at −80 mVin control and PL treated cells. Respectively IV curves under these conditions are shown in (E). Average (8–10 recordings current intensity at −80 mV are shown in (F). * indicate significance (p = <0.05).</p

Effect of PL on cytokine production by BMDMs.

<p>BMDMs were pulsed with medium alone, PL at 25/ml, or various TLR ligands; LPS (10 ng/ml) (<b>A</b>), Pam3 Cys4 (Pam3) at 10 ng/ml (<b>B</b>), dsRNA (10 ng/ml) (<b>C</b>), ssRNA (10 ng/ml) (<b>D</b>), CpG DNA (1 µM) (<b>E</b>), or PL before the addition of respective TLR agonists in the medium. Cells were cultured for a total of 24 h period. The cytokine contents of IL-6 and TNF-α in culture supernatants were assayed by using specific sandwich enzyme-linked immunosorbent assays as recommended by the manufacturer (BD biosciences or R&D Systems). Cytokines detected below the assay detection limit for each stimulation are presented as UD (undetected). The mean ± SE concentration of cytokines in five independent experiments was determined. (F) BMDMs were pulsed with medium alone, PL at various concentrations; 5 ug/ml (PL5), 15 ug/ml (PL15) or 30 ug/ml (PL30), before the addition of LPS (10 ng/ml) in the medium. The cytokine contents of IL-6 in culture supernatants were assayed at 24 h as described above. Significant differences were measured by Student's <i>t</i> test and are denoted by asterisks (*, P<0.05, **, P<0.01 and ***, P<0.001).</p

PL inhibits LPS-induced mRNA expression of IL-6 and TNF-α.

<p>BMDMs were pulsed with medium alone or PL, LPS, PL+LPS for 30 min, 2 h, 6 h, or 24 h. RNA was isolated and reversed transcribed to cDNA by using random primers. Levels of IL-6, TNF-α and housekeeping gene 18 S in these samples were measured by Real Time PCR analysis as described using SYBR green as the detection dye. IL-6 and TNF-α mRNA levels were normalized to the mRNA level of the housekeeping gene 18 S in the same sample. Fold change in mRNA expression of IL-6 (A) and TNF- α (B) after 6 h and 24 h stimulation over their respective baseline control level in unstimulated samples were expressed in arbitrary units. Data shown are representative of three independent experiments. Significant differences were measured by Student's <i>t</i> test and are denoted by asterisks (**, P<0.01 and ***, P<0.001).</p

Soil microbial community composition and environmental constraints.

<p>A) Principal component analysis (PCA) of the phospholipid fatty acid (PLFA) data. Error bars indicate standard errors. The symbol size is positively correlated with N application rate. B) Redundancy analysis (RDA) of the PLFA data as explained by environmental variables. The explanatory variables followed by asterisks indicate significant influences on the PLFA data (*, <i>P</i> < 0.05; **, <i>P</i> < 0.01; ***, <i>P</i> < 0.001).</p