- Salt-induced silk gel-derived N and trace Fe co-doped 3D porous carbon as an oxygen reduction catalyst in microbial fuel cells. [Journal Article]
- NNanoscale 2019 Jul 08
- Inexpensive and high-efficiency oxygen reduction reaction (ORR) catalysts play a significant role in achieving practical applications of microbial fuel cells (MFCs). Hence, herein, novel nitrogen (N)…
Inexpensive and high-efficiency oxygen reduction reaction (ORR) catalysts play a significant role in achieving practical applications of microbial fuel cells (MFCs). Hence, herein, novel nitrogen (N) and trace iron (Fe) co-doped three-dimensional (3D) porous carbon (NFex-C) was synthesized as an excellent ORR catalyst from an interesting salt-induced silk gel, which was beneficial to the spontaneously formation of porosity and boosted the ORR activity. Among the series of NFex-C, NFe0.5-C (1.20% N-ORR/C, 0.07 at% Fe) possessed a higher specific surface area (538.94 m2 g-1) and pore volume (2.158 cm3 g-1). Note that NFe0.5-C exhibited a significantly higher positive initial potential (0.274 V vs. Ag/AgCl) and half-wave potential (0.095 V vs. Ag/AgCl) than other catalysts and commercial Pt/C (20 wt%); this implied that it possessed prominent ORR catalytic activity. In the MFC tests, the output-voltage and maximum power density of NFe0.5-C were enhanced to 517.37 ± 7.87 mV and 605.35 ± 15.39 mW m-2, respectively. Moreover, NFe0.5-C (0.15 $ g-1) exhibits excellent anti-poisoning ability and is thousands of times cheaper than commercial Pt/C (20 wt%, 220.04 $ g-1); therefore, NFe0.5-C should be a prospective catalyst to substitute precious commercial Pt/C in MFCs and even for application in other types of fuel cells.
- Enhancing oxygen reduction reaction activity and CO2 tolerance of cathode for low temperature solid oxide fuel cells by in-situ formation of carbonates. [Journal Article]
- AAACS Appl Mater Interfaces 2019 Jul 03
- Development of low-cost and cobalt-free efficient cathode materials for oxygen reduction reaction (ORR) remains one of the paramount motivations for material researchers at low temperature (< 650 ᵒC)…
Development of low-cost and cobalt-free efficient cathode materials for oxygen reduction reaction (ORR) remains one of the paramount motivations for material researchers at low temperature (< 650 ᵒC). In particular, iron-based perovskite oxides show promise as electrocatalysts for ORR because Fe metal is cheaper and naturally abundant, exhibit matched thermal expansion with contacting components such as electrolyte and show high tolerance in CO2 containing atmosphere. Herein, we demonstrated a new mechanism, the in-situ formation of alkali metal carbonates at cathode surface. This new mechanism leads to an efficient and robust cobalt-free electrocatalyst (Sr0.95A0.05Fe0.8Nb0.1Ta0.1O3-, SAFNT5, A= Li, Na, K) for the application of low temperature solid oxide fuel cell (LT-SOFC). Our results revealed that the formation of Li\K carbonates boost the ORR activity with an area specific resistance (ASR) as low as 0.12 and 0.18 Ω cm2 at 600 ᵒC, respectively, which are the highest performance of cobalt-free single-phase cathode that have been ever reported by far. We also find that the chemical stability and tolerance of tested cathodes towards CO2 poisoning significantly improved with alkali carbonates, as compared to the pristine SrFe0.8Nb0.1Ta0.1O3- (SFNT) at 600 ᵒC. This work demonstrates the conclusive role of alkali carbonates to develop highly efficient and stable cobalt-free cathodes for LT-SOFCs and CO2 neutralization.
- Stereoselective Alkyne Hydrogenation by a Simple Iron Catalyst. [Journal Article]
- CChemSusChem 2019 Jul 02
- The stereoselective hydrogenation of alkynes constitutes one of the key approaches to the construction of stereo-defined alkenes. The majority of conventional methods utilize noble and toxic metal ca…
The stereoselective hydrogenation of alkynes constitutes one of the key approaches to the construction of stereo-defined alkenes. The majority of conventional methods utilize noble and toxic metal catalysts. Here, we report a simple catalyst comprised of the commercial chemicals Fe(acac)2 and diisobutylaluminiumhydride (DIBAL-H) that enables the Z-selective semi-hydrogenation of alkynes under near ambient conditions (1-3 bar H2, 30 °C, 5 mol% [Fe]). Neither elaborate catalyst preparation nor addition of ligands is required. Mechanistic studies (kinetic poisoning, XAS, TEM) strongly indicate the operation of small iron cluster and particle catalysts.
- Possible involvement of transcriptional activation of nuclear factor erythroid 2-related factor 2 (Nrf2) in the protective effect of caffeic acid on paraquat-induced oxidative damage in Drosophila melanogaster. [Journal Article]
- PBPestic Biochem Physiol 2019; 157:161-168
- Paraquat (PQ) is a widely used herbicide with no antidote which is implicated in the pathogenesis of the Parkinson's disease. The present study then investigated the potential of caffeic acid (CA), a…
Paraquat (PQ) is a widely used herbicide with no antidote which is implicated in the pathogenesis of the Parkinson's disease. The present study then investigated the potential of caffeic acid (CA), a known antioxidant, cardioprotective and neuroprotective molecule to counteract oxidative stress mediated by PQ. In addition, molecular docking was performed to understand the mechanism underlying the inhibitory effect of CA against PQ poisoning. The fruit fly, Drosophila melanogaster, was exposed to PQ (0.44 mg/g of diet) in the absence or presence of CA (0.25, 0.5, 1 and 2 mg/g of died) for 7 days. Data showed that PQ-fed flies had higher incidence of mortality which was associated with mitochondrial dysfunction, increased free Fe(II) content and lipid peroxidation when compared to the control. Co-exposure with CA reduced mortality and markedly attenuated biochemical changes induced by PQ. The mechanism investigated using molecular docking revealed a strong interaction (-6.2 Kcal/mol) of CA with D. melanogaster transcriptional activation of nuclear factor erythroid 2-related factor 2 (Nrf2). This was characterized by the binding of CA to keap-1 domain of Nrf2. Taking together these results indicate the protective effect of CA against PQ-induced oxidative damage in D. melanogaster was likely through its coordination which hinders Nrf2-keap-1 binding leading to an increase of the antioxidant defense system.
- Determination of Iron Chelating Agents by Analytical Methods: A Review. [Journal Article]
- CRCrit Rev Anal Chem 2019 May 29; :1-11
- Acute iron poisoning and chronic iron overload consequences in significant morbidity and mortality worldwide. Treatment of acute iron poisoning and chronic iron overload can be challenging and care p…
Acute iron poisoning and chronic iron overload consequences in significant morbidity and mortality worldwide. Treatment of acute iron poisoning and chronic iron overload can be challenging and care providers are often tackled with management dilemmas. Iron chelating agents are commonly prescribed for patients with iron deficiency anemia. In this review article, different analytical techniques are reported used for qualitative and quantitative analysis of iron chelating agents like, deferiprone, deferoxamine, and deferasirox. Efforts are taken to collect all related articles published till October 2018. This review discusses all analytical methods, its advantages and disadvantages as well as its applications. This article will help you to know about basic analytical techniques as well as advanced hyphenated techniques practiced for determination of iron chelating agents in different matrices. The techniques discussed in this review follow the ICH guidelines for method validation.
- Heavy metal toxicity: An update of chelating therapeutic strategies. [Review]
- JTJ Trace Elem Med Biol 2019; 54:226-231
- CONCLUSIONS: Heavy metals are necessary for various biological processes, but they become harmful in excess. Specifically, they induce oxidative stress by generating free radicals and reducing antioxidant levels. Heavy metals also alter the confirmation of protein and DNA and inhibit their function. Chelation therapy is commonly used to treat metals toxicity. Chelation is a chemical process that occurs when interaction between a central metal atom/ion and ligand leads to formation of a complex ring-like structure. The ligand has a donor ion/molecule, which has a lone pair of electrons and may be monodentate to polydentate. Each metal has a different reactivity with a ligand, so a specific chelation agent is required for each metal. Combination therapy with a chelating agent and an antioxidant led to improved outcome.Heavy metal poisoning is a common health problem because of mining, smelting, industrial, agricultural and sewage waste. Heavy metals can be efficiently excreted from the body following treatment with proper chelation agents.
- Endoplasmic reticulum rather than mitochondria plays a major role in the neuronal apoptosis induced by polybrominated diphenyl ether-153. [Journal Article]
- TLToxicol Lett 2019 Sep 01; 311:37-48
- Polybrominated diphenyl ether-153 (BDE-153) has been demonstrated to induce neuronal apoptosis in rat cerebral cortex and primary neurons, however, the roles of mitochondria and endoplasmic reticulum…
Polybrominated diphenyl ether-153 (BDE-153) has been demonstrated to induce neuronal apoptosis in rat cerebral cortex and primary neurons, however, the roles of mitochondria and endoplasmic reticulum (ER) remain unclear in the BDE-153-induced neuronal apoptosis. To this purpose, we observed the mitochondria and ER ultrastructure changes in the neuronal apoptosis in rats following BDE-153 treatment, detected the mitochondrial membrane potential (MMP), Ca2+-Mg2+-ATP enzyme activity, and the changes of mitochondria and ER apoptosis related molecules in rat cerebral cortex and in primary neurons following BDE-153 treatment. Results showed that compared to the control group, neuronal apoptosis was significantly increased in a dose-dependent manner in rat cerebral cortex and in primary neurons following BDE-153 treatment. In comparison with control, BDE-153 treatment induced remarkable ultrastructural changes in ER rather than in mitochondria, and the severity of ER damage was worse with the increasing BDE-153 dose. Meanwhile, ER apoptosis related molecules including caspase-12 (at mRNA level), cleaved caspase-12 (at protein level), and Tmem132a (at mRNA and protein levels) were significantly increased in the cerebral cortex in rats following BDE-153 treatment, while procaspase-12 protein was significantly decreased, comparing with control. In contrast, mitochondria apoptosis related molecules (MMP, Ca2+-Mg2+-ATP enzyme activity, cyt-C protein, caspase-3, 8, 9 mRNA, caspase-8, 9 enzyme activities) did not significantly changed in the cerebral cortex of rats or in primary neurons following BDE-153 treatment, except for the elevated caspase-3 mRNA and enzyme activity. Therefore, we conclude that BDE-153 induced neuronal apoptosis was dependent on p53, and mediated more by ER than mitochondria in the cerebral cortex of rats and in primary neurons. The findings suggest that ER is a potential sensitive target of BDE-153 neurotoxicity, providing a scientific evidence for the mechanism and intervention study on PBDE's neurotoxicity.
- Comparing erosion and organ accumulation rates of lead and alternative lead-free ammunition fed to captive domestic ducks. [Journal Article]
- AAmbio 2019 Apr 16
- Lead poisoning of birds of prey from ingestion of ammunition lead has been well documented. Alternative, lead-free ammunition is widely available, but the toxicokinetics of other metals in birds are …
Lead poisoning of birds of prey from ingestion of ammunition lead has been well documented. Alternative, lead-free ammunition is widely available, but the toxicokinetics of other metals in birds are poorly understood. We tested the erosion of lead, copper, zinc, iron and brass by feeding domestic Pekin ducks (Anas platyrhynchos forma domestica) defined numbers of small metal pellets. The accumulation of these metals was analysed in the breast muscle, brain, pancreas, liver and kidney. Four weeks after application, the ducks were euthanized and necropsied, internal organs tested for metal accumulation and gizzard pellets collected and weighed to record loss by erosion. Degree of erosion was highest in zinc pellets (81% mass loss), followed by iron (46%) and lead (45%) and was only marginal in copper and brass. Only lead showed highly elevated levels of accumulation in organs compared to controls.
- [Interaction of Salmonella with Macrophages-Critical Roles of Salmonella SEp22, a Pathogenicity-related Protein, and Macrophage Reactive-Oxygen Intermediate Species (ROIs) on the Infection and Survival of Salmonella]. [Review]
- YZYakugaku Zasshi 2019; 139(4):617-627
- Salmonella is a Gram-negative [Gram(-)] bacteria, distributed widely in such natural environments as soil, dust, or river water, causing food poisoning as well as oral infections such as Typhi or Par…
Salmonella is a Gram-negative [Gram(-)] bacteria, distributed widely in such natural environments as soil, dust, or river water, causing food poisoning as well as oral infections such as Typhi or Paratyphi. Salmonella is highly tissue invasive, easily spreading throughout the whole body after initial growth in the phagocytic vesicles of macrophages as an intra-cellular parasite. Because there remain many unknown elements in the Salmonella-macrophage interaction, I started my study by focusing on the molecules and mechanisms underlying the interaction; for example, how Salmonella escapes natural biodefense systems armed by macrophages, and how macrophages surround and inactivate Salmonella. In addition, I developed insight into Salmonella survival in the face of both environmental stresses and immunological stresses, including attacks from macrophages, based on the idea that "pathogenicity" is not limited simply to an attack, but to both the attack and defense against hazards. In this study, I found a novel pathogenicity-related protein of Salmonella, SEp22, an iron-chelating protein of MW 18.7 kDa, to cope with reactive-oxygen intermediates (ROIs) generated by activated macrophages pre-treated with lipopolysaccharides (LPS), one of the major components of Salmonella outer membrane. We also showed that Salmonella attacks macrophages by a novel mechanism through the induction of apoptosis with large amounts of LPS and protein synthesis inhibition, in addition to the well-known mechanisms of type-three secretion system (TTSS)-induced cell damage, including InvA, an attacking, virulent factor of Salmonella. We showed that macrophages could escape from this type of cell death by LPS-induced macrophage activation and LPS-tolerance.
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- Antidotal Effects of the Phenothiazine Chromophore Methylene Blue Following Cyanide Intoxication. [Journal Article]
- TSToxicol Sci 2019 Jul 01; 170(1):82-94
- Our study was aimed at (1) determining the efficacy of the dye methylene blue (MB), following a rapidly lethal cyanide (CN) intoxication in un-sedated rats; (2) clarifying some of the mechanisms resp…
Our study was aimed at (1) determining the efficacy of the dye methylene blue (MB), following a rapidly lethal cyanide (CN) intoxication in un-sedated rats; (2) clarifying some of the mechanisms responsible for the antidotal properties produced by this potent cyclic redox dye. Sixty-nine awake rats acutely intoxicated by CN (IP, KCN 7 mg/kg) received saline, MB (20 mg/kg) or hydroxocobalamin (HyCo, 150 mg/kg) when in deep coma. Survival in this model was very low, reaching 9% at 60 min without any treatment. Methylene blue significantly increased survival (59%, p < .001) at 60 min, versus 37% with HyCo (p < .01). In addition, 8 urethane-anesthetized rats were exposed to a sublethal CN intoxication (KCN, 0.75 mg/kg/min IV for 4 min); they received MB (20 mg/kg, IV) or saline, 5 min after the end of CN exposure. All MB-treated rats displayed a significant reduction in hyperlactacidemia, a restoration of pyruvate/lactate ratio-a marker of NAD/NADH ratio-and an increase in CO2 production, a marker of the activity of the TCA cycle. These changes were also associated with a 2-fold increase in the pool of CN in red cells. Based on series of in vitro experiments, looking at the effects of MB on NADH, as well as the redox effects of MB on hemoglobin and cytochrome c, we hypothesize that the antidotal properties of MB can in large part be accounted for by its ability to readily restore NAD/NADH ratio and to cyclically re-oxidize then reduce the iron in hemoglobin and the electron chain complexes. All of these effects can account for the rapid antidotal properties of this dye following CN poisoning.