Hydrothermal synthesized kaolin group lamellar/spongy aluminosilicates for enhanced lead vapor capture.

Developing high-temperature-resistant adsorbents with superior porous properties is crucial for safely disposing of heavy metal-containing solid waste via pyrolysis. We synthesized aluminosilicates hydrothermally and observed that acidic conditions, especially HCl (pH=2.6), favored sponge-like mineral (NC2.6) formation with a specific surface area of 500.31 m²/g and pore volume of 0.986 cm³ /g, while alkaline conditions (pH=12.0) promoted spherical particle growth. NC2.6 exhibited higher adsorption capacity compared to kaolinite and halloysite in the PbCl2 vapor adsorption, reaching a maximum of 137.68 mg/g at 700 â„ƒ (75.91 % stable). We examined the effect of CO2 and H2O on adsorption efficiency and explored the mechanisms using DFT and GCMC simulations. From GCMC results, CO2 negatively impacted PbCl2 adsorption due to competitive adsorption, while H2O increased adsorption content (144.24 mg/g at 700 â„ƒ) by converting PbCl2 into oxides. DFT revealed the presence of CO2 enhanced the adsorption stability of PbCl2 via the formation of covalent bonds between O in CO2 and Pb, and active O on the aluminosilicate surface. H2O increased PbCl2 adsorption energy, as O in H2O occupied an active Al that originally formed a covalent bond with Cl, while the H formed a weak hydrogen bond with this Cl.

Improved adsorption capacity and applicable temperature of gaseous PbCl2 capture by modified montmorillonite with combined thermal treatment and acid activation.

The emission of semi-volatile heavy metals during the thermal utilization of various fuels has been a huge threat to the environment. In this study, the montmorillonite modified by thermal treatment and hydrochloric acid activation was evaluated for the PbCl2 adsorption performance. The optimum adsorption temperature of sorbents increased with the thermal treatment temperature (<500 °C) for the increased amount of reactive sites caused by the removal of interlayer water and hydroxyl, while a higher treatment temperature will collapse the lamellar structure of montmorillonite and greatly inhibit the PbCl2 adsorption. Besides, the hydrochloric acid activation can help inhibit the melting of sorbents during the adsorption process by removing the impurities and promote the PbCl2 vapor to contact with more reactive sites at higher temperatures. By comparing different sorbents, montmorillonite was found to exhibit better adsorption performance at 600-700 °C, while the sorbent thermal-treated at 500 °C and then acid-activated got the highest adsorption efficiency at 900 °C, which was 17.83% higher than that of montmorillonite. This study provided an environmental-friendly modification method to capture more heavy metals at high-temperature conditions, which can be partly realized by the recycling of montmorillonite used for the removal of normal gas pollutants in lower temperatures conditions or acid wastewater treatment.

A Comparison of the Effect of Lead (Pb) on the Slow Vacuolar (SV) and Fast Vacuolar (FV) Channels in Red Beet (Beta vulgaris L.) Taproot Vacuoles.

Little is known about the effect of lead on the activity of the vacuolar K+ channels. Here, the patch-clamp technique was used to compare the impact of lead (PbCl2) on the slow-activating (SV) and fast-activating (FV) vacuolar channels. It was revealed that, under symmetrical 100-mM K+, the macroscopic currents of the SV channels exhibited a typical slow activation and a strong outward rectification of the steady-state currents, while the macroscopic currents of the FV channels displayed instantaneous currents, which, at the positive potentials, were about three-fold greater compared to the one at the negative potentials. When PbCl2 was added to the bath solution at a final concentration of 100 µM, it decreased the macroscopic outward currents of both channels but did not change the inward currents. The single-channel recordings demonstrated that cytosolic lead causes this macroscopic effect by a decrease of the single-channel conductance and decreases the channel open probability. We propose that cytosolic lead reduces the current flowing through the SV and FV channels, which causes a decrease of the K+ fluxes from the cytosol to the vacuole. This finding may, at least in part, explain the mechanism by which cytosolic Pb2+ reduces the growth of plant cells.

Crystal Structure of Colloidally Prepared Metastable Ag2Se Nanocrystals.

Structural polymorphism is known for many bulk materials; however, on the nanoscale metastable polymorphs tend to form more readily than in the bulk, and with more structural variety. One such metastable polymorph observed for colloidal Ag2Se nanocrystals has traditionally been referred to as the "tetragonal" phase. While there are reports on the chemistry and properties of this metastable polymorph, its crystal structure, and therefore electronic structure, has yet to be determined. We report that an anti-PbCl2-like structure type (space group P21/n) more accurately describes the powder X-ray diffraction and X-ray total scattering patterns of colloidal Ag2Se nanocrystals prepared by several different methods. Density functional theory (DFT) calculations indicate that this anti-PbCl2-like Ag2Se polymorph is a dynamically stable, narrow-band-gap semiconductor. The anti-PbCl2-like structure of Ag2Se is a low-lying metastable polymorph at 5-25 meV/atom above the ground state, depending on the exchange-correlation functional used.

Green production of a novel sorbent from kaolin for capturing gaseous PbCl2 in a furnace.

The pollution of semi-volatile heavy metals is one of the key environmental risks for municipal solid waste incineration, and in-situ adsorption of metals within the furnace by mineral sorbents such as kaolin has been demonstrated as a promising emission control method. To lessen the consumption of sorbent, a novel material of amorphous silicate was produced from kaolin through pressurised hydrothermal treatment. Its performance of gaseous PbCl2 capture was tested in a fixed bed furnace and compared with unmodified kaolin and metakaolin. With increasing temperature, the adsorption rates for all sorbents declined due to higher saturated vapour pressure, while the partitions of residual form lead increased which indicated higher stability of heavy metals in the sorbent because of melting effect. The new sorbent with a larger surface area and reformed structure presented 26% more adsorption efficiency than raw kaolin at 900 °C, and increasing the modification pressure improved these properties. Additionally, the production of this high-temperature sorbent was relatively inexpensive, required little thermal energy and no chemicals to produce and no waste effluent was generated, thus being much cleaner than other modification methods.

Treatment with Lead Chloride During Pregnancy and the Postnatal Period Alters Cell Proliferation and Immune Function in Swiss Albino Mice.

In the current study, we investigated the effect of lead chloride (PbCl2) administration (50 and 100 ppm) on organ and body weight as well as its bioaccumulation during pregnancy and the postnatal period in mice. We showed that lead has no effect on the body weight of mice. However, spleen weight is affected by the two doses of PbCl2 while liver and kidney weights are altered only by the 100-ppm dose. Inductively coupled plasma atomic emission spectrometry (ICP-AES) analysis showed that lead accumulates in the blood, spleen, and thymus. Both doses of PbCl2 significantly reduced splenocyte and thymocyte cell counts after stimulation with lipopolysaccharide (LPS) and phytohemagglutinin A (PHA), respectively. On the other hand, we showed that the levels of Th1 cytokines (interleukin-2 (IL-2), interferon gamma (IFN-γ)), and tumor necrosis factor alpha (TNF-α) were reduced in the serum of mice treated with PbCl2 in a dose-dependent manner, as measured by ELISA. The levels of interleukin-4 (IL-4) and interleukin-10 (IL-10) were very low in untreated mice and were also reduced by treatment with PbCl2. The levels of IL-2, IFN-γ, IL-4, IL-10, and TNF-α secretion differentially decreased in LPS-stimulated splenocytes in lead-treated mice. Using PHA-stimulated thymocytes, we observed a reduction in the levels of IL-2, IL-4, IL-10, and TNF-α in the PbCl2-treated groups. However, IFN-γ concentration in the supernatant of these cells was not decreased when mice were treated with 50 ppm of lead.

Autophagy plays a protective role in cell death of osteoblasts exposure to lead chloride.

Lead (Pb) is a toxic heavy metal widespreadly used in industrial field. Prior studies showed that Pb exposure had detrimental effects on osteoblasts. The mechanisms underlying Pb-induced damage are complex. Autophagy can protect cells from various cytotoxic stimuli. In the present study, the aim of our research was to investigate whether Pb could activate autophagy to play a protective role against osteoblasts apoptosis. Our results indicated that PbCl2 induced autophagy and autophagic flux in MC3T3-E1 murine osteoblastic cell by RT-PCR, western blot, as well as fluorescence microscopy analysis of GFP-LC3, AO and MDC staining. Pb increased the apoptosis of osteoblasts, evidenced by western blot and Hoechst 33258 staining assessment. In addition, inhibiting autophagy by 3-MA further increased the osteoblasts apoptosis after Pb exposure, showed by flow cytometry and Hoechst 33258 staining. Furthermore, phosphorylation of mTOR and p70S6K was inhibited by Pb exposure, indicating that Pb might induce autophagy in osteoblasts via inhibiting mTOR pathway. Altogether, these evidence suggested that Pb exporsure promoted autophagy flux in osteoblasts. The activation of autophagy by Pb played a protective role in osteoblasts apoptosis, which might be mediated through the mTOR pathway.

Effects of PbCl2 on selective catalytic reduction of NO with NH3 over vanadia-based catalysts.

The effects of PbCl2 on the selective catalytic reduction of NO with NH3 over vanadia-based catalysts were studied with BET, XRD, SEM, XPS, NH3-TPD, NH3 chemisorption, FT-IR and catalytic activity measurements. The results showed that PbCl2 deactivated the catalysts to a very high extent. The doping of PbCl2 could decrease the surface acidity, especially that of Brønsted acid sites. XPS characterization reveals that the presence of PbCl2 resulted in the transformation of V(5+) into V(4+), which decreased the reducibility of vanadia species. Based on the analysis of physical and chemical properties of the catalysts, the PbCl2-poisoning mechanism model of the vanadia-based SCR catalysts was proposed.

S1 kills MCF-7/ADR cells more than MCF-7 cells: A protective mechanism of endoplasmic reticulum stress.

Drug resistance in chemotherapy for breast cancer is associated with high levels of P-glycoprotein (P-gp) as well as endoplasmic reticulum (ER) stress. In this paper, we aimed to evaluate the efficacy of a pan-BH3 mimetic S1 on drug-resistant MCF-7/ADR cells, and the roles of S1-induced ER stress in cell death. S1 exhibited greater and faster mitochondrial apoptosis in MCF-7/ADR cells than in MCF-7 cells. We demonstrated by Bax/Bak activation and cyrochrome c release that the p-glycprotein had little influence on S1 entering cells and hitting its targets in MCF-7/ADR cells. An IRE1-mediated ER stress response followed by c-Jun N-terminal kinase (JNK) and extracellular signal-regulated protein kinase (ERK) activation was specifically induced by S1 in MCF-7 cells, but not in MCF-7/ADR cells. Coimmunoprecipitation and western blotting analysis determined that ER stress played a protective role in S1-induced apoptosis by triggering Bcl-2 phosphorylation, which grabbed more pro-apoptotic proteins. The synergism effect of ERK inhibitor PD98059 with S1 confirmed the protective role of ER stress. Defective ER stress in MCF-7/ADR cells confers the more sensitivity toward S1.

EVALUATION OF ANTIOXIDANT DEFENSE RESPONSES TO LEAD STRESS IN HAPALOSIPHON FONTINALIS-339(1).

Lead (Pb) is a heavy metal and a potentially hazardous environmental pollutant. In this study, the potential of lead to induce oxidative stress in biological systems was assessed using the cyanobacterium Hapalosiphon fontinalis-339 as model test organism. The impact of lead toxicity on the cellular antioxidant system and the biochemical modulations that result in generation of antioxidant defense responses were also studied. To determine the effect of Pb toxicity, the test organism was grown in the presence of various concentrations (0.05, 0.10, 0.20, 0.40, 0.80, 1.0, 1.20, and 1.25 mg · L(-1) ) of exogenous lead chloride (PbCl2 ), and its effects on growth were observed in terms of the change in chl content. There was a significant increase in metal uptake by the alga with a concomitant decrease in growth. Lead stress appeared to significantly up-regulate the levels of stress-related antioxidant enzymes-such as superoxide dismutase (SOD), ascorbate peroxidase (APX), and glutathione reductase (GR)-while a decrease in catalase (CAT) levels was observed. In addition, the levels of nonenzymatic antioxidants, oxidized and total glutathione, were changed. Our results suggest the existence of a potent antioxidant defense machinery in H. fontinalis-339 and this organism can be employed to monitor lead toxicity in the environment.