Effects of pH and organic co-solvents on the oxidation of naphthalene with peroxosulfate catalyzed by iron(III) tetrakis(p-sulfonatophenyl)porphyrin

2003 ◽  
Vol 07 (09) ◽  
pp. 645-650 ◽  
Author(s):  
Mikio Kawasaki ◽  
Anabel Kuriss ◽  
Masami Fukushima ◽  
Akira Sawada ◽  
Kenji Tatsumi
Keyword(s):  
Catalytic System ◽  
Acidic Ph ◽  
Efficient Conversion ◽  
Effects Of Ph

The oxidation of naphthalene was investigated in a biomimetic catalytic system using KHSO 5 and iron(III) tetrakis(p-sulfonatophenyl)porphyrin ( FeTPPS ) in order to elucidate the influence of solution forms, such as buffer pH and co-solvent types, on the reaction. 1,4-naphthoquinone was the main byproduct and the efficiency of oxidation, particularly 1,4-naphthoquinone formation, was influenced by pH and the type of co-solvent used. The most efficient conversion of 1,4-naphthoquinone was observed at an acidic pH (= 3). At higher pH , the formation of μ-oxo species ( OFe 2( TPPS )2) leads to a decrease of the percentage of naphthalene oxidized. In addition, the organic co-solvents (methanol, ethanol, 2-propanol and acetonitrile) influenced the amounts of naphthalene conversion. The amounts of 1,4-naphthoquinone formed were related to the electron donating character of the organic co-solvents.

Troponin I isoforms and differential effects of acidic pH on soleus and cardiac myofilaments

1995 ◽  
Vol 268 (2) ◽  
pp. C323-C330 ◽  
Author(s):  
J. Wattanapermpool ◽  
P. J. Reiser ◽  
R. J. Solaro
Keyword(s):  
Troponin I ◽  
Troponin C ◽  
Binary Complex ◽  
Acidic Ph ◽  
Differential Effects ◽  
Adult Rat ◽  
Effects Of Ph ◽  
Isoform Switching ◽  
Acidic Conditions ◽  
Tension Generation

Differences in pH sensitivity of tension generation between developing and adult cardiac myofilaments, which contain the same isoform of troponin C (TnC), have been proposed to be due to troponin I (TnI) isoform switching from the slow skeletal (ss) to cardiac (c) TnI isoforms (21). We investigated the effects of acidic pH on Ca(2+)-activation of force in chemically skinned preparations of adult rat trabeculae and single soleus fibers that also share the same TnC isoform. Compared with the soleus fibers, trabeculae demonstrated a greater suppression of tension and a rightward shift in pCa50 (-log half-maximally activating molar Ca2+ concentration) when pH was decreased from 7.0 to 6.2. The pH-induced shift in pCa50 in soleus fibers did not change with sarcomere length. Troponin subunit interactions were also investigated, using cardiac troponin C (cTnCIA) labeled with a fluorescent probe, 2-(4'-iodoacetamidoanilino)-naphthalene-6-sulfonic acid. Under acidic conditions, cTnCIA demonstrated a decrease in Ca(2+)-affinity. This decrease was amplified both in the binary complex cTnCIA-cTnI and in the complex cTnCIA-cTnI-cTnT-tropomyosin to the same extent. In contrast, substitution of ssTnI for cTnI in these complexes produced the same decrease in Ca2+ affinity in response to acidic pH as cTnCIA alone. These results support our hypothesis that differential effects of pH on tension generation and Ca2+ sensitivity between soleus fibers and trabeculae are due to the presence of different isoforms of TnI.

Performance of denitrifying microbial fuel cell subjected to variation in pH, COD concentration and external resistance

2013 ◽  
Vol 68 (1) ◽  
pp. 250-256 ◽  
Author(s):  
Jin-Tao Li ◽  
Shao-Hui Zhang ◽  
Yu-Mei Hua
Keyword(s):  
Fuel Cell ◽  
Chemical Oxygen Demand ◽  
Microbial Fuel Cell ◽  
Electricity Generation ◽  
Oxygen Demand ◽  
Pollutant Removal ◽  
Acidic Ph ◽  
External Resistance ◽  
Weakly Alkaline ◽  
Effects Of Ph

The effects of pH, chemical oxygen demand (COD) concentration and external resistance on denitrifying microbial fuel cell were evaluated in terms of electricity generation characteristics and pollutant removal performance. The results showed that anodic influent with weakly alkaline or neutral pH and cathodic influent with weakly acidic pH favored pollutant removal and electricity generation. The suitable influent pH of the anode and cathode were found to be 7.5–8.0 and 6.0–6.5, respectively. In the presence of sufficient nitrate in the cathode, higher influent COD concentration led to more electricity generation and greater pollutant removal rates. With an anodic influent pH of 8.0 and a cathodic influent pH of 6.0, an influent COD concentration of 400 mg/L was deemed to be appropriate. Low external resistance favored nitrate and COD removal. The results suggest that operation of denitrifying microbial fuel cell at a lower external resistance would be desirable for pollutant removal but not electricity generation.

Synergetic combination of a mesoporous polymeric acid and a base enables highly efficient heterogeneous catalytic one-pot conversion of crude Jatropha oil into biodiesel

2020 ◽  
Vol 22 (5) ◽  
pp. 1698-1709 ◽  
Author(s):  
Hu Pan ◽  
Yanan Liu ◽  
Qineng Xia ◽  
Heng Zhang ◽  
Li Guo ◽  
...  
Keyword(s):  
Catalytic System ◽  
Jatropha Oil ◽  
One Pot ◽  
Heterogeneous Catalytic ◽  
Mild Conditions ◽  
Efficient Conversion ◽  
Highly Efficient ◽  
Polymeric Acid

Highly efficient conversion of crude Jatropha oil to biodiesel was realized under mild conditions via a synergistic catalytic system consisting of acid (MICPHPW) and base (MICPOH) catalysts using a ‘one-pot, two-step’ strategy.

Development of a novel bi-enzymatic silver dendritic hierarchical nanostructure cascade catalytic system for efficient conversion of starch into gluconic acid

2019 ◽  
Vol 356 ◽  
pp. 423-435 ◽  
Author(s):  
Saghar Rezaei ◽  
Amir Landarani–Isfahani ◽  
Majid Moghadam ◽  
Shahram Tangestaninejad ◽  
Valiollah Mirkhani ◽  
...  
Keyword(s):  
Catalytic System ◽  
Gluconic Acid ◽  
Hierarchical Nanostructure ◽  
Efficient Conversion

scholarly journals The Effects of pH and Temperature on Cysteine Protease (Cathepsin B) Activity in Miracidia and Eggs of Fasciola hepatica

2020 ◽  
Author(s):  
Leila KIANIFARD ◽  
Mohammad YAKHCHALI ◽  
Mehdi IMANI
Keyword(s):  
Cysteine Protease ◽  
Cathepsin B ◽  
Fasciola Hepatica ◽  
Distilled Water ◽  
Acidic Ph ◽  
Optimum Temperature ◽  
Egg Hatching ◽  
Ph Values ◽  
Zoonotic Parasite ◽  
Effects Of Ph

Abstract Background: Fascioliasis is a worldwide zoonotic disease caused by the trematodes Fasciola hepatica in humans and animals. Proteases are essential for the survival of parasites and have important activities such as penetration, tissue migration, and egg hatching. This study was conducted to analyze cysteine protease of the miracidia and eggs of F. hepatica, and to assess the effects of pH and temperature on the proteases activity and stability. Methods: Adults F. hepatica were isolated from infected livers and were morphologically identified in 2018. Eggs collected from the adults and incubated in distilled water at 28 °C for 16 d to produce miracidia. The extract was collected from miracidia and eggs. A substrate for cathepsin B (Z-Arg-Arg-Pna) was used to assess the enzyme activity at different (2-12) pH levels. After homogenization, protein level was measured with Bradford method. Estimation of optimum temperature and pH was performed in the temperature range of 10-90 ° C and pH values from 2-12. Results: The highest activity of the miracidia and eggs enzyme extracts for Z-ArgArg-pNA was at pH 4. The miracidia extract was most stable at neutral pH and the eggs extract was most stable in acidic pH. The optimum temperature activity for both stages was 40 °C. These proteases were stable up to 40 °C. Conclusion: Upon the importance of pH and temperature in the life cycle of F. hepatica, the current findings can be used for induction of some modifications in pH and preventing the activity of the enzymes for decrement of the efficacy of miracidia penetration into the intermediate snails and egg hatching of this zoonotic parasite.

scholarly journals Effects of pH on Helicobacter pylori binding to human gastric mucins: identification of binding to non-MUC5AC mucins

2004 ◽  
Vol 384 (2) ◽  
pp. 263-270 ◽  
Author(s):  
Sara LINDÉN ◽  
Jafar MAHDAVI ◽  
Jan HEDENBRO ◽  
Thomas BORÉN ◽  
Ingemar CARLSTEDT
Keyword(s):  
Helicobacter Pylori ◽  
Chondroitin Sulphate ◽  
Acidic Ph ◽  
Gastric Mucus ◽  
Ulcer Disease ◽  
Effects Of Ph ◽  
Membrane Bound ◽  
H Pylori ◽  
Host Blood

Helicobacter pylori causes gastritis, peptic ulcer disease and gastric cancer. The microbe is found in the gastric mucus layer where a pH gradient ranging from acidic in the lumen to neutral at the cell surface is maintained. The aim of the present study was to investigate the effects of pH on H. pylori binding to gastric mucins from healthy individuals. At pH 3, all strains bound to the most charged MUC5AC glycoform and to a putative mucin of higher charge and larger size than subunits of MUC5AC and MUC6, irrespective of host blood-group. In contrast, at pH 7.4 only Leb-binding BabA-positive strains bound to Leb-positive MUC5AC and to smaller mucin-like molecules, including MUC1. H. pylori binding to the latter component(s) seems to occur via the H-type-1 structure. All strains bound to a proteoglycan containing chondroitin sulphate/dermatan sulphate side chains at acidic pH, whereas binding to secreted MUC5AC and putative membrane-bound strains occurred both at neutral and acidic pH. The binding properties at acidic pH are thus common to all H. pylori strains, whereas mucin binding at neutral pH occurs via the bacterial BabA adhesin and the Leb antigen/related structures on the glycoprotein. Our work shows that microbe binding to membrane-bound mucins must be considered in H. pylori colonization, and the potential of these glycoproteins to participate in signalling events implies that microbe binding to such structures may initiate signal transduction over the epithelial layer. Competition between microbe binding to membrane-bound and secreted mucins is therefore an important aspect of host–microbe interaction.

scholarly journals Glutathione-Induced Conversion of Pentavalent Antimony to Trivalent Antimony in Meglumine Antimoniate

2001 ◽  
Vol 45 (3) ◽  
pp. 913-916 ◽  
Author(s):  
Frédéric Frézard ◽  
Cynthia Demicheli ◽  
Claúdio S. Ferreira ◽  
Michelle A. P. Costa
Keyword(s):  
Standard Treatment ◽  
Reduced Glutathione ◽  
Reduced Form ◽  
Molar Ratio ◽  
Dependent Manner ◽  
Acidic Ph ◽  
Meglumine Antimoniate ◽  
Pentavalent Antimony ◽  
Effects Of Ph ◽  
Dose Dependent

ABSTRACT The standard treatment of human leishmaniases involves the use of pentavalent antimony [Sb(V)] compounds, including meglumine antimoniate. The mode of action of these compounds has not been fully elucidated. The possibility that Sb(III) is involved has been suggested; however, the biomolecule that may induce the conversion of Sb(V) to Sb(III) has not yet been identified. In the present study, we investigated both the ability of reduced glutathione (GSH) to promote the reduction of Sb(V) into Sb(III) in meglumine antimoniate and the effects of pH and temperature on this transformation. GSH did promote the reduction of Sb(V) into Sb(III) in a dose-dependent manner. When GSH and meglumine antimoniate were incubated together at a GSH/Sb molar ratio superior or equal to 5:1, all antimony was encountered in the reduced form, indicating a stoichiometry of 5:1 between GSH and Sb(V) in the reaction. The reaction between Sb(V) and GSH was favored at an acidic pH (pH 5) and an elevated temperature (37°C), conditions found within the phagolysosome, in which Leishmania resides. For instance, about 30% of the Sb(V) (concentration, 2mM) was converted to Sb(III) following incubation for 3 days with 10 mM GSH at pH 5 and 37°C. Our data support the hypothesis that Sb(V) would be converted by GSH, or a related thiol compound, to more toxic Sb(III) in the phagolysosome of macrophages.

scholarly journals Mechanisms of Heat-induced Antigen Retrieval: Does pH or Ionic Strength of the Solution Play a Role for Refolding Antigens?

2005 ◽  
Vol 53 (11) ◽  
pp. 1311-1321 ◽  
Author(s):  
Katsura Emoto ◽  
Shuji Yamashita ◽  
Yasunori Okada
Keyword(s):  
Ionic Strength ◽  
The Other ◽  
Antigen Retrieval ◽  
Antigenic Determinants ◽  
Acidic Ph ◽  
Cooling Process ◽  
Ph Values ◽  
Ph Dependency ◽  
Nacl Concentration ◽  
Effects Of Ph

We investigated the effects of pH and ionic strength of solutions used for antigen retrieval to elucidate the mechanism of heat-induced antigen retrieval (HIAR) in immunohistochemistry. The immunostaining intensity of nuclear, cytoplasmic, cell membrane, and extracellular matrix antigens with 17 different antibodies was evaluated in formaldehyde-fixed and paraffin-embedded mouse and human tissues. Deparaffinized sections were autoclaved for 10 min in buffers with different pH values ranging from 3.0 to 10.5. To test the influence of ionic strength on immunoreactions, the sections were autoclaved for 10 min in 20 mM Tris-HCl buffers (TB) at pH 9.0 and 10.5 with or without 25, 50, and 100 mM NaCl. There were two immunostaining patterns for pH dependency of HIAR. First, the majority of antibodies recovered their antigenicity when heated in the buffers with both acidic pH (pH 3.0) and basic pH (pH 9.0 and 10.5). Second, some antibodies showed strong immunostaining only at basic pH values (pH 9.0 and 10.5). When the sections were autoclaved in TB at pH 9.0, immunostaining of all eight antibodies examined decreased as the NaCl concentration increased. On the other hand, when the sections were treated with TB at pH 10.5, all antibodies yielded stronger reactions in the buffer containing NaCl than in the buffer without NaCl; five antibodies exhibited the strongest immunoreaction at concentrations from 25 to 50 mM. These results suggest that the extended polypeptides by heating are charged negatively or positively at basic or acidic pH, and that an electrostatic repulsion force acts to prevent random entangling of polypeptides caused by hydrophobic attractive force and to expose antigenic determinants, during cooling process of HIAR solution.

scholarly journals Effects of pH on Nanofibrillation of TEMPO-Oxidized Paper Mulberry Bast Fibers

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 414 ◽  
Author(s):  
Jung Park ◽  
Chan-Woo Park ◽  
Song-Yi Han ◽  
Gu-Joong Kwon ◽  
Nam-Hun Kim ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Cellulose Nanofibrils ◽  
Crystallinity Index ◽  
Electrostatic Repulsion ◽  
Acidic Ph ◽  
Tempo Oxidation ◽  
Bast Fibers ◽  
Ph Values ◽  
Ph Dependency ◽  
Effects Of Ph

TEMPO oxidation was conducted as a pretreatment to achieve efficient nanofibrillation of long paper mulberry bast fibers (PMBFs). The pH dependency of nanofibrillation efficiency and the characteristics of the resulting cellulose nanofibrils (CNFs) were investigated. As the pH increased, the negative value of the zeta potential of TEMPO-oxidized fibers increased. The increase in electrostatic repulsion at pH values of greater than 9 prevented the entanglement of long PMBFs, which was a drawback for defibrillation at acidic pH. With increasing pH, the CNF production yield was increased. The crystallinity index of TEMPO-oxidized CNFs from PMBFs was 83.5%, which was higher than that of TEMPO-oxidized CNFs from softwood fibers in the same conditions. The tensile strength of nanopaper from TEMPO-oxidized PMBF CNFs was 110.18 MPa, which was approximately 30% higher than that (84.19 MPa) of the TEMPO-oxidized CNFs from softwood fibers.

scholarly journals Distribution, Sorption and Desorption of Tylosin, Chlortetracycline and their Metabolites in Pig Manure

2016 ◽  
Vol 4 (4) ◽  
pp. 65 ◽  
Author(s):  
Ashok K Singh
Keyword(s):  
Detection Limit ◽  
Pig Manure ◽  
Quantitative Detection ◽  
Acidic Ph ◽  
Accurate Assessment ◽  
Antibiotic Residues ◽  
Degree Of Contamination ◽  
Pig Farms ◽  
Effects Of Ph ◽  
Desorption Hysteresis

Effects of pH on sorption, desorption and hysteresis of chlortetracycline (CTCs), tylosin (TYL) and their metabolites have been studied in pig manure samples collected from different pig farms. Approximately 36% of the samples analyzed tested positive (concentration > quantitative detection limit) for the antibiotics and metabolite residues. The degree of contamination depended upon the manure’s pH. The acidic TYL-positive manure samples contained TYL-A and TYL-B, while the basic TYL-positive samples contained TYL-A, TYL-ALD and TYL-D.  The CTC-positive manure samples contained mostly CTC, ECTC and ACTC at acidic pH, but mostly CTC, ICTC, EICTC and EACTC at basic pH. For acidic and neutral manure samples, the logKDdes values were greater than the KDs values for TYL-B, TYL-A, TYL-ALD, CTC, ACTC, ECTC and EACTC, indicating sorption-desorption hysteresis. TYL-D, ICTC and EICTC did not exhibit sorption-desorption hysteresis. At acidic and neutral pH, the residues remained solid-bound, but an increase in pH decreased hysteresis, resulting in greater leaching and contamination of the environment. Thus, environmental pH may determine the antibiotics and metabolite leaching in freshwater at or away from the site of production. In addition, analysis of the parent antibiotic residues may not provide an accurate assessment of the environmental health.    

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