Variety Of pH Research Articles

Floating Microsponge: An Emerging Drug Delivery System

Floating microsponges are a method to extend gastric residence time, there with the aid of using concentrated on site-responsive medicament liberate withinside the top GIT for locally or systemic effect. Gastro retentive dosage forms (GRDFs) are getting utilized from a totally long term to enhance treatment with numerous main medications. Floating microsponge significantly enhances the therapy of stomach with the aid of using liberating the medication locally and for that reason used for medication selecting at specific organ. This may be sustained over an extended period of time. Floating drug delivery allow extended and non-stop release of the drug to the top a part of Gastro intestinal tract and this expressively amplify the period of drug release and enhance pharmacokinetic of medication which have slim healing window, with the aid of using this method dosing frequency and affected person compliance is increased. A microsponge’s drug delivery system is a particularly cross-linkage, spongy, polymeric microsphere, polymeric device consisting permeable microspheres. Microsponges are prepared with the aid of using numerous techniques consisting of liquid-liquid suspension polymerization and quasi emulsion solvent diffusion method. Microsponge,s preparations are strong over variety of pH 1 to 11; microsponge,s preparations are strong on the temperature as much as 1300C well suited with maximum vehicles and ingredients. The present assessment introduces microsponge,s technology at the side of its techniques of preparation, characterization, advantages, evaluation and release mechanism of microsponge,s drug delivery system, advertised product and up to date studies regarding microsponge.
 Keywords: Floating microsponge, Oral administration, Controlled release, Quasi emulsion, Target release.

Adsorptive Behavior of Tartaric Acid Treated Holarrhena antidysenterica and Citrullus colocynthis Biowastes for Decolourization of Congo Red Dye from Aqueous Solutions

The aim of the present work is to eradicate Congo red (CR) dye from aqueous solutions since the dye compounds are harmful to human life and the environment leading to detrimental results. For this purpose, Holarrhena antidysenterica (HA) and Citrullus colocynthis (CC) adsorbents were used for the adsorptive removal of Congo red dye from wastewaters. The unmodified adsorbents (U-HA and U-CC) were chemically modified using tartaric acid (TA). Morphological structures were examined by FTIR and SEM. Batch adsorption studies were tested at a variety of pH, time exposure, temperatures, and adsorbent dosages. Thermodynamic parameters such as Gibbs free energy ( ∆ G ° ), enthalpy ( ∆ H ° ), entropy changes ( ∆ S ° ), and energy of activation ( E a ) were also calculated. The results revealed that tartaric acid-Citrullus colocynthis (TA-CC) gave optimum conditions of time of contact (35 min), temperature conditions (40°C), pH (3), and dosage of adsorbent (1.6 g) for maximum dye removal. Tartaric acid-Holarrhena antidysenterica (TA-HA) gave equilibrium time of contact (30 min), temperature (40°C), and pH optimum (2) along with a 1.6 g dosage of adsorbent. Mechanistic understanding of adsorption isotherm provided that the Langmuir model was followed by raw and modified adsorbents. Maximum adsorption capacities Q max attained were 60.61 (mg g-1), 128.21 (mg g-1), 87.71 (mg g-1), and 131.57 (mg g-1), respectively, for U-HA, TA-HA, U-CC, and TA-CC. The results of kinetic modeling displayed a high value of R 2 (0.99) along with minimal error (RMSE) for dye removal showing that the pseudo-second-order kinetic model has acceptable accuracy. Fourier transform infrared proposed the electrostatic, pi-pi interactions, and hydrogen bonding as dominant adsorption mechanisms at acidic pH, respectively. Rate-determining steps comprise both surface and intraparticle diffusions. Thermodynamics indicated that the dye adsorption of CR is spontaneous, exothermic, and favorable in nature. These agricultural wastes due to specific points such as low cost, availability, and high removal rates of adsorption are highly competent for the expulsion of anionic dye like CR from wastewaters.

Characterization and Application of Biopolymer Producing Bacteria for Enhanced Oil Recovery

The objective of this research is to isolate and identify hydrocarbon-degrading bacteria for biopolymer synthesis and application in the augmentation of Nigerian heavy crude oil recovery. MEOR refers to the process of injecting either indigenous or non-indigenous microbes into hydrocarbon reserves. Injecting microorganisms with nutritional broth facilitate the formation of essential metabolites such as biosurfactants, biopolymers, and gases, resulting in decreased interfacial tension, viscosity modification, and mobility control. It is environmentally friendly, less expensive to implement, and requires minimal or no changes to the existing infrastructure. A soil sample from a hydrocarbon-contaminated site in Ogoniland was collected and sent to a laboratory for physicochemical and microbiological investigation. Bacillus sp, Pseudomonas sp, and Klebsiella sp were biochemically identified after screening three isolates for biopolymer production using Sudan black solution. To assess the ideal growth and biopolymer synthesis capability under reservoir conditions, a variety of pH, temperature, salinity, carbon, and nitrogen nutrition sources were applied to selected microorganisms. Peptone is the optimal nitrogen source for Bacillus sp, glucose is the optimal carbon source for Bacillus sp, and glycerol is the optimal carbon source for Pseudomonas sp and Klebsiella sp, as indicated by the results. In addition, the following are the ideal parameter ranges for the three microorganisms: pH 7–8, a temperature range between 25 and 350 degrees Celsius, and a salinity range between 0.5 and 5% are all desirable conditions for a body of water. After inoculation with microorganisms and the optimum nutrient source, an additional recovery range of 18.33% to 29.09% of the pore capacity was achieved. The post-recovery analysis uncovered a remarkable transformation of heavy crude to light hydrocarbon components by an average of 20.33 percent with glucose and 97.27 percent with peptone.

Arsenic(V) Removal from Water by Resin Impregnated with Cyclodextrin Ligand

More rigorous environmental rules on hazardous metals release require the implementation of diverse methods to remove them from contaminated streams. The adsorption process is the most attractive method for removal of toxic metal ions from different aqueous solutions. In the present study, batch and fixed bed column experiments were carried out to investigate the performance of permethylated β-cyclodextrin impregnated resin for the removal of As(V) ions from aqueous solutions. Sorption of As(V) ions was performed in groups under a variety of pH and metal concentrations. It was noted that removal efficiency was the highest (98%) at pH 6.0, and at an initial As(V) concentration equal to 0.1 mg/L. Sorption model use for experimental data indicates that the removal mechanism of As(V) by the permethylated β-cyclodextrin impregnated resin was the physical sorption. The adsorption capacity of the cyclodextrin ligand immobilized onto Amberlite XAD-4 resin was 19 mg/g. In addition, the impregnated resin was regenerable, thus was able to be used over and over.

Blossom end rot disease tracking and prevention: a smart approach

Agriculture is the foundation of any nation. It is required for the comprehensive financial turn of events. The paper centers on Blossom End Rot infection which influences the tomato plant because of pH variety in the soil. This paper presents an investigation of different strategies to sift through disease, plant infection distinguishing proof utilizing layout coordinating picture order just as deep learning based Convolutional neural systems picture arrangement and proposes a framework to forestall the event of this ailment. Deep learning based disease identification has higher exactness than conventional strategies. In traditional methods, we just pH value of the soil is measured and remedial measure is taken, but here model is proposed that combines that disease detection at the early stage itself by using Deep Learning and IoT. The general goal is to improve rural profitability and homestead salary.

Hydrogen peroxide formation in water during the VUV/UV irradiation process: Impacts and mechanisms of selected anions

Understanding the formation and transformation of radicals generated by a low pressure mercury lamp emitting both 254 nm ultraviolet (UV254) and 185 nm vacuum UV (VUV185) is currently challenging due to the complexity of concurrent redox reactions occurring in this complex system. Because hydrogen peroxide (H2O2) is a common product of both oxidizing and reducing radicals generated during the VUV irradiation process, monitoring the variations in H2O2 levels can help us better understand the presence and relative dominance of different radicals. In this study, we systematically evaluated the effects of several selected anions on the formation of H2O2 under a variety of pH and dissolved oxygen (DO) conditions. Results show that although addition of these anions inhibited the formation of H2O2, their H2O2-inhibition mechanisms are markedly different. At low concentrations (≤1.0 mg/L), chloride reduced the generation of H2O2 primarily by consuming hydroxyl radicals (•OH); however, in high concentrations (11.0 mg/L), its light-screening effect was dominant. In comparison, the presence of bromide (≤1.0 mg/L) inhibited H2O2 formation mainly by reacting rapidly with both •OH and H2O2. Carbonate and phosphorous species exerted influence mainly by consuming •OH. Along with irradiation, increasing pH significantly decreased H2O2 levels, confirming that H2O2 was formed mainly by •OH. In contrast, raising DO did not raise H2O2 maximum yields, confirming that reducing radicals like aqueous electrons (e-aq) and hydrogen atoms (•H) are not the key precursors of H2O2 in this process. Mathematically, the evolutions of H2O2 can be reliably modeled (R2 ≥ 0.80) using a kinetics model incorporating H2O2 formation and decomposition kinetics. The results of this study may contribute to better understanding the use of VUV technology in water/wastewater treatment.

Mechanistic understanding of the adsorption and thermodynamic aspects of cationic methylene blue dye onto cellulosic olive stones biomass from wastewater

In the current study, the mechanistic understanding of the adsorption isotherm and thermodynamic aspects of cationic methylene blue (MB) dye adsorption onto cellulosic olive stones biomass from wastewater were investigated. The batch adsorption of MB onto the olive stones (black and green olive stones) was tested at a variety of pH, dye concentrations, temperatures, and biomass particle sizes. The adsorption thermodynamics such as Gibbs free energy, enthalpy, and entropy changes were also calculated. Moreover, the desorption studies of MB from the spent olive stones were studied to explore the re-usability of the biomasses. The results revealed that under the optimum pH of 10, the maximum MB uptake was achieved i.e. 80.2% for the green olive stones and 70.9% for the black olive stones. The green olive stones were found to be more efficient in remediating higher MB concentrations from water than the black olive stones. The highest MB removal of the green olive stones was achieved at 600 ppm of MB, while the highest MB removal of the black olive stones was observed at 50 ppm of MB. Furthermore, for almost all the concentrations studied (50–1000 ppm), the MB adsorption was the highest at the temperature of 45 °C (P value < 0.05). It was shown by the Fourier transform infrared that the electrostatic interaction and hydrogen bonding were proposed as dominant adsorption mechanisms at basic and acidic pH, respectively. While the hydrophobic-hydrophobic interaction was a dominant mechanism at neutral pH. The thermodynamic studies revealed that the adsorption process was endothermic, spontaneous, and favorable. Moreover, the real wastewater experiment and the desorption studies showed that the green and black olive stones were a cost-effective and promising adsorbents for MB remediation from wastewater on account of their high adsorption and desorption removal capacities.

Food Spoilage by Bacilli: Combined Effects of pH, aw and Storage Temperature on Spore Germination and Growth in Cultural Broth Added with Solutes and Organic Acids

Aims: The control of Bacillus spores plays an important role in quality assurance and safety of processed foods. Their growth can be avoided by either sterilization or pasteurization in combination with a lowering of pH (≤ 4.6) or water activity (aw &lt; 0.90) or with the combined action of both parameters (spore germination inhibition). In some food products, the reduction of pH to values ​​lower than 4.6 or a thermal treatment of sterilization can lead to nutritional and organoleptic changes, that are not always satisfactory for the consumer. The aim of this work was to produce data for a range of spoilage bacilli at a variety of pH and aw values and to monitor the potential outgrowth of these spores when stored at different temperatures. This study focused on the influence of the type of acid or solute used. &#x0D; Place and Duration of Study: Quality, Safety and Pre-Industrialization Area, Stazione Sperimentale per l’Industria delle Conserve Alimentari-SSICA, Parma, Italy between March 2018 and November 2019.&#x0D; Methodology: B. sublitilis, B. licheniformis, B. cereus spore’s growth was studied in broth under the following conditions: aw (0.90 to 0.93), temperature (6, 12 and 30°C) and pH (4.9 to 5.5). Selected water activities were reached by the addition of appropriate amount of sodium chloride, sucrose or glycerol; pH was adjusted to various values with lactic acid, acetic acid or citric acid.&#x0D; Results: A combination of aw 0.92, with glycerol or sodium chloride and pH 5.1 inhibits the germination of all strains spores. B. subtilis was the species able to grow in the less favorable conditions. Acetic acid proved the strongest antimicrobial action; sodium chloride resulted more effective in inhibiting growth when used in combination with acids tested.&#x0D; Conclusion: The results achieved can be useful for the food industry, identifying the conditions that could preserve the product by means of a less drastic heat treatment preserving as much as possible the natural organoleptic characteristics.

The effect of pH-temperature on plastic allowance for Low-Density Polyethylene (LDPE) by Thiobacillus sp. and Clostridium sp.

LDPE are plastic polymers, widely used because they are affordable, waterproof, and flexible, hence difficult to degrade naturally. This study aim therefore is to degrade LDPE plastic using a biotechnology approach with a mixture of Thiobacillus sp. and Clostridium sp. at a variety of pH and temperatures. Mixed bacterial cultures were grown on Stone Mineral Salt Solution (SMSs) with a batch system, thereafter, gravimetric method was used to determine the difference in weight and Fourier Transformer Infrared Spectroscopy (FTIR) was used to determine changes in functional groups. To obtain the optimum condition that produces the highest degradation, researchers conducted the experiment at temperature varied from 25, 30, 35o C and pH 5, 7, 9. The highest removal of LDPE occurred at 30oC with pH 7. Gravimetrically, mixed cultures of Thiobacillus sp. and Clostridium sp. was capable of degrading LDPE plastic with an allowance of 2-7% for 30 days. Considering that this research produces a relatively small allowance, further research is needed to exploit the potential of using both bacteria in degrading LDPE plastic.

Novel triphenylamine polyazomethines bearing carbazole and trifluoromethyl substituents: Preparation and electrochromic behavior

A series of novel polyazomethines (PAMs) were successfully synthesised as reported herein. In particular, a new electroactive diamine 3″-trifluoromethyl-4, 4′-diamino-4″-N-carbazolyl triphenylamine (IV) underwent direct polycondensation reactions with various dialdehydes, such as terephthalaldehyde (Va), 1, 3-isophthalaldehyde (Vb), o-phthalaldehyde (Vc) and 4, 4′-diformyltriphenylamine (Vd) to yield a sequence of novel PAMs: VIa-VId. These polymers were tested via differential scanning calorimetry (DSC) to have very high glass transition temperatures (Tgs, 237–271 °C). Meanwhile, thermogravimetric analysis (TGA) indicated that all of the PAMs in these series were stable with a 5% weight loss in nitrogen atmosphere (444–483 °C). These PAMs films were tested via cyclic voltammetry (CV) and calculated to have HOMO levels between −5.09 and −5.29 eV, LUMO levels between −2.47 and −3.18 eV (relative to vacuum levels). The color of the PAMs films can be changed from yellow in the initial neutral state to red via electrooxidation during the period of 0.0–1.3 V, and then becomes purple as the voltage rises to 1.5 V. A variety of pH- and chemical doping-responsive color changes were also observed. Taking into account the sensitive properties of PAMs, this PAMs will have broad application prospects, such as chemical sensors, OLEDs and solar cells.

A novel serine protease from pseuderanthemum latifolium B. Hansen: Characterization and fibrino(geno)lytic activities

Protease (PPL) was isolated from Pseuderanthemum latifolium B. Hansen and had a molecular mass of 70 kDa. The N-terminal sequence of PPL showed 70-80% similarity with of subtilisin-like serine proteases from plants, but it did not show any sequence homology with known plant proteases. Serine protease inhibitors (PMSF, DFP) effectively blocked about 90% of PPL activity. PPL was highly activity at the pH range from 6 to 9 and temperatures from 50 °C to 80 °C, with an optimum at pH 7.0 and temperatures 70 °C. PPL had stability in a variety of pH, temperature, surfactant and oxidizing agents. PPL with concentration of 2.5 µg completely hydrolyzed the Aα-chain of fibrinogen within 5 min and hydrolyzed the Bβ and the γ-chain after 10 h. Fibrin also was strong hydrolyzed by PPL with concentration of 0.3 µg. Thus, PPL is a unique serine protease, which it had strong fibrino(geno)lytic activities.

THE ADSORPTION OF HEAVY METALS FROM INDUSTRIAL WASTEWATER USING SARGASSUM CRASSIFOLIUM

Sargassum crassifolium is the origin strains of macroalgae from Indonesia which was the most effectively adsorb heavy metals from liquid solution and it was investigated the adsorptive capability of heavy metals in industrial wastewater. The macroalgae were collected at Kotok Besar Island, Seribu Island, North Jakarta, Indonesia and were treated with the variety of pH 2, 3, 4, 5 and 9 for 60 minutes oscillation, in duplicate assessment. The macroalgae were selectively effective for removal of Cd, Hg, and Pb compared with other heavy metals, achieving 75-99.05% adsorption efficiency, mostly in acidic condition for 60 minutes oscillation, except Hg. The selectivity order for other metal ion uptake by S. crassifolium was Cu>Fe>Co>Ni>Cr with percentage removal below 56%. Due to the low cost, availability and significantly high adsorption capability, the brown macroalgae S. crassifolium is able to be used for selective removal of heavy metals from industrial wastewater effectively in acidic pH range

Use of Monascus sp. NP1 for bioethanol production from Cladophora glomerata

The fungus Monascus sp. was able to produce ethanol instead of red pigment under glucose derepression with greater and more tolerance to ethanol than yeast. Algae are known as a polysaccharide resource for bioethanol production. This work was focused on the optimization of cellulase production through solid-state fermentation of straw and rice bran using Trichoderma viride TISTR 3161 for saccharification by the alga, Cladophora glomerata. The best conditions for alga enzymatic hydrolysis were proposed after varying crude enzyme and temperature, comparing the enzyme method to the physical method of saccharification from the alga, characterizing bioethanol production from the fungi at the laboratory scale, and scaling up to a 10-L fermenter, and fermentation of the algal extract at a variety of pH at the laboratory scale. Cellulase production from Sangyod Phatthalung rice using 21.19-mg crude enzyme at 35 °C provided the best conditions of all five varieties of Thai rice tested in terms of producing reducing sugar via algal hydrolysis. This method obtained nearly the same amount of reducing sugar as the physical method (acid and high temperature). At the laboratory scale, 20% glucose in liquid medium was the best condition for ethanol production (1384 μM) of all glucose concentrations tested (2, 10, 20, 30, and 50%) at room temperature on a rotary shaker (110 rpm) for 120 h. The time of production could be reduced to 72 h to produce the same amount of ethanol in a fermenter. The pH of 6 was the proper condition for bioethanol production in algal extract media. The promise of this technique for bioethanol production was shown.

Combined experimental and quantum chemical study on the adsorption mechanism of phosphorous anions on the hydrotalcite surfaces

In the present work, the hydrotalcite-like compound [Mg6Al2(OH)[Formula: see text]]CO[Formula: see text] [Formula: see text]H2O (shorted as MgAl–CO[Formula: see text] is synthesized and the adsorption of phosphorous anions, their adsorption performance on the surface of hydrotalcites, and its mechanism are analyzed. To theoretically clarify the adsorption mechanism and adsorption structures, we perform quantum chemistry calculations of reactants, locally stable states, transition states, and products among phosphorous anion, water, and hydrotalcite in a variety of pH ranges. The experimental result shows that the efficiency of phosphate removal does not depend on pH of the solution, with which the numerical results are consistent. In particular, we identify the factors of influencing the adsorption ratio in different pH ranges from the quantum chemistry calculations: the stability of locally stable states, and the energies and locations of potential barriers along the reaction pathway relative to those of the locally stable states. The results suggest that hydrotalcites synthesized in this work are suitable as sorbent materials for the adsorption and removal of phosphorous anions from aqueous solutions.

Characterization of the Secondary Structure of CP30, a Highly Repetitive Ampholytic Protein in Beetle Elytral Cuticle

SummaryCP30 is a major component protein in the rigid cuticle of the beetle elytron which we recently identified. It has a highly unusual amino acid sequence comprised largely of alternating blocks of 3–5 anionic and cationic amino acid residues (three charged residues, glutamic acid, arginine and histidine, make up 76% of the sequence) which suggest an unusual stuctural role. The secondary structure of CP30 was evaluated at a variety of pH, ionic strength and temperature conditions. Circular dichroism (CD), fluorescence spectroscopy and static and dynamic light scattering showed that the protein had an extended α‐helical structure at pH 3, 5 and 7 which unfolded around 60°C and reformed upon cooling back to 10°C. The protein aggregated or adhered to the dialysis membrane at pH 5, low salt, which is close to the protein's isoelectric point (5.82), preventing analysis at that condition. Further studies aimed at solubilizing the protein near that condition may uncover evidence of assembly. While the structural function of CP30 is currently unknown, the sequence of CP30 may offer new design motifs for the development of novel polymer or gel biomaterials.

In Vivo Predictive Dissolution: Transport Analysis of the CO2, Bicarbonate In Vivo Buffer System

Development of an oral in vivo predictive dissolution medium for acid drugs with a pKa in the physiological range (e.g., Biopharmaceutics Classification System Class IIa) requires transport analysis of the complex in vivo CO2 /bicarbonate buffering system. In this report, we analyze this buffer system using hydrodynamically defined rotating disk dissolution. Transport analysis of drug flux was predicted using the film model approach of Mooney et al based on equilibrium assumptions as well as accounting for the slow hydration reaction, CO2 + H2 O → H2 CO3 . The accuracy of the models was compared with experimentally determined results using the rotating disk dissolution of ibuprofen, indomethacin, and ketoprofen. The equilibrium and slow hydration reaction rate models predict significantly different dissolution rates. The experimental results are more accurately predicted by accounting for the slow hydration reaction under a variety of pH and hydrodynamic conditions. Although the complex bicarbonate buffering system requires further consideration given its dynamic nature in vivo, a simplifying irreversible reaction (IRR) transport analysis accurately predicts in vitro rotating disk dissolution rates of several carboxylic acid drugs. This IRR transport model provides further insight into bicarbonate buffer and can be useful in developing more physiologically relevant buffer systems for dissolution testing.

Synthesis, screening and pharmacokinetic evaluation of potential prodrugs of bupropion. Part one: in vitro development.

In general, prodrugs are developed to circumvent deficiencies associated with the absorption, distribution, metabolism, excretion or toxicological (ADMET) profile associated with the active drug. In our study, we select bupropion, a drug with broad pharmacology incorporating dopaminergic, noradrenergic, nicotinic and cytokine modulation properties, but which is rapidly metabolized in vivo. We exploited its carbonyl and secondary amine functionality to facilitate the synthesis of bioprecursor prodrug forms with the sole objective of identifying analogues with enhanced properties over bupropion. A range of analogues were synthesized, ranging from N-methyl, N-benzyl, oximes, enol acetate and ether forms to examples where both functional groups were utilized to form oxadiazine, oxadiazinone, oxazolone and acetylated derivatives. We then developed an in vitro metabolic screen to simulate the human oral delivery route for these analogues. The selection of media in the screens contained a variety of pH, enzymatic and co-factor systems which mimic metabolic in vivo environments that drugs encounter when delivered orally. By coupling our in vitro screening tool to a selective hyphenated technique such as LC-MS, we were able to quickly select potential prodrugs for further in vitro and in vivo development. From the data generated, the N-alkylated bupropion analogues were shown to have the highest potential to act as bioprecursor prodrugs of bupropion.

Effects of Ocean Acidification on Toxicity of Heavy Metals in the Bivalve Mytilus edulis L

The anthropogenic release of carbon dioxide into the atmosphere leads to an increase in the CO2 partial pressure in the ocean, which may reach 950 μatm by the end of the 21st century. An experiment was performed to test the effects of increased sea water concentrations of CO2 combined with heavy metals on mortality rates, metallothionein, immune funtion, and uptake kinetics of the bivalve Mytilus edulis L. As a result, the mortality rates of Mytilus edulis L fluctuated with pH variety in all heavy metals (Cd, Pb, Cu) test seawater treatments compared to control group. It was demonstrated that in vivo Cd-, Pb-, or Cu pretreatment under acidifications can alleviate metallothionein by in vitro Cd, Pb, and Cu in soft tissues and suggested that acidification can aggravate heavy metals pollution and toxicity for marine organisms. Moreover, the fraction of eosinophilic cells increased over the 21 days period for Cd exposure, then decreased with 28 and 35 days incubation, the fraction of eosinophilic cells increased similar with Cd exposure and pH 8.2. The fraction of eosinophilic cells significantly increased from 32% to 53% of the hemocyte population over the 35-day period for Pb exposure and pH8.2, the fraction of eosinophilic cells increased from 35% to 58% of the hemocyte population over the 35-day period for Pb exposure and pH 6.2. Phagocytosis levels declined with increasing exposure time for Cd alone and phagocytosis levels declined with decreasing pH (from 8.2 to 6.2) with Cd exposure on 35 days. Mytilus edulis L in Pb with reduced pH (6.2) treatments also decreased their phagocytosis levels on 35 days. Further, phagocytosis decreased bigger than that of Pb with pH 8.2. At steady state equilibrium, CF of 109Cd was significantly higher at pH 6.2 and pH 7.7 than at pH 8.2, the accumulation of 203Pb was significantly higher at the lowest pH 6.2 level than at the two exposure levels (pH 7.7 and pH 8.2). Similarly, the lower the seawater pH 6.2, the more 63Cu was accumulated in the hemolymph of Mytilus edulis L. The results indicate that future reductions in pH caused by increased CO2 concentrations in the sea may have an impact on Mytilus edulis L combined with heavy metals pollution.

(H2O)(terpy)Mn(mu-O)2Mn(terpy)(OH2)](NO3)3 (terpy = 2,2':6,2''-terpyridine) and its relevance to the oxygen-evolving complex of photosystem II examined through pH dependent cyclic voltammetry.

Photosynthetic water oxidation occurs naturally at a tetranuclear manganese center in the photosystem II protein complex. Synthetically mimicking this tetramanganese center, known as the oxygen-evolving complex (OEC), has been an ongoing challenge of bioinorganic chemistry. Most past efforts have centered on water-oxidation catalysis using chemical oxidants. However, solar energy applications have drawn attention to electrochemical methods. In this paper, we examine the electrochemical behavior of the biomimetic water-oxidation catalyst [(H(2)O)(terpy)Mn(mu-O)(2)Mn(terpy)(H(2)O)](NO(3))(3) [terpy = 2,2':6',2''-terpyridine] (1) in water under a variety of pH and buffered conditions and in the presence of acetate that binds to 1 in place of one of the terminal water ligands. These experiments show that 1 not only exhibits proton-coupled electron-transfer reactivity analogous to the OEC, but also may be capable of electrochemical oxidation of water to oxygen.

Inner-sphere oxidation of ternary nitrilotriacetatocobalt(II) complexes involving oxalate and phthalate by periodate

The oxidation of [CoII(nta)(ox)(H2O)2]3− and [CoII(nta)(ph)(H2O)2]3− (nta = nitrilotriacetate, ox = oxalic acid and ph = phthalic acid) by periodate have been studied kinetically in aqueous solution over 20–40 °C and a variety of pH ranges. The rate of oxidation of [CoII(nta)(ox)(H2O)2]3− by periodate, obeys the following equation: d[CoIII]/dt = [CoII(nta)(ox)(H2O)23−][H5IO6] {k4K5 + (k5K6K2/[H+]} while the reaction of [CoII(nta)(ph)(H2O)2]3− with periodate in aqueous acidic medium obeys the following rate law: d[CoIII]/dt = k6K8[CoII]T [IVII]T/{1 + [H+]/K7 + K8[IVII]T}. Initial cobalt(III) products were formed and slowly converted to final products, fitting an inner-sphere mechanism. Thermodynamic activation parameters have been calculated. A common mechanism for the oxidation of ternary nitrilotriacetatocobalt(II) complexes by periodate is proposed and supported by an excellent isokinetic relationship between ΔH* and ΔS* values for these reactions.