High pH Medium Research Articles

Effect of electrolyte composition on electrocatalytic transformation of perfluorooctanoic acid (PFOA) in high pH medium

Recent regulatory actions aim to limit per- and polyfluoroalkyl substances (PFAS) concentrations in drinking water and wastewaters. Regenerable anion exchange resin (AER) is an effective separation process to remove PFAS from water but will require PFAS post-treatment of the regeneration wastestream. Electrocatalytic (EC) processes using chemically boron-doped diamond electrodes, stable in a wide range of chemical compositions show potential to defluorinate PFOA in drinking water and wastewater treatments. Chemical composition and concentration of mineral salts in supporting electrolytes affect AER regeneration efficiency, and play a crucial role in the EC processes. Their impact on PFAS degradation remains understudied. This study investigates the impact of 17 brine electrolytes with different compositions on perfluorooctanoic acid (PFOA) degradation in an alkaline medium and explores the correlation between the rate of PFOA degradation and the solution's conductivity. Results show that higher electrolyte concentrations and conductivity lead to faster PFOA degradation rates. The presence of chloride anions have negligible impact on the degradation rate. However, the presence of nitrate salts reduce PFOA degradation efficiency. Additionally, the use of mixed electrolytes may be a promising approach for reducing the cost of EC operations. PFOA degradation was not influenced by the pH of the bulk solution.

PH-Sensitive Fluorescence Emission of Boron/Nitrogen Co-Doped Carbon Quantum Dots

Carbon quantum dots (CQDs) with their strong photoluminescence (PL) activity, high biocompatibility, robust stability, low cytotoxicity, and flexible surface structures have been employed in many fields including chemical sensing, biosensing, photocatalyst, energy storage, and biomedical applications. Of note, CQDs present an intrinsic pH-sensitive PL nature indicating their intense potential for pH-mediated sensing and imaging. Despite the numerous studies performed in the last two decades, the pH-sensitive PL mechanism of CQDs is still under debate and must be clarified to overcome the limitations in practical applications. Therefore, in this report, we performed a systematical study to determine the pH-sensitive PL nature of boron/nitrogen co-doped CQDs (B/N CQDs). In the first part, B/N CQDs with a strong blue emission were fabricated via a hydrothermal synthesis procedure. B/N-CQDs showed a strong blue PL emission with high quantum yield and excitation-dependent nature. Under the low pH conditions (pH 3), B/N-CQDs exhibited a robust green fluorescence emission with a significant red-shift (48 nm) and the loss of the excitation-dependent nature. The change in PL nature originated from the protonation of surface groups, a decrease in negative surface charge (from −20.6 to −1.23 eV), and finally, aggregation of the nanostructure (the size of CQDs from 4.8 to 7.5 nm). However, in the case of alkaline conditions, the deprotonation surface groups significantly enhanced the surface charge and led to the emergence of a negative ‘protective shell’ with a zeta potential of −71.3 eV. In a high pH medium (pH 13), PL spectra showed the loss of excitation-dependent features and a red-shift (35 nm) in emission peak maxima with lower intensity. This report provides significant progress in the clarification of the pH-sensitive PL mechanism of CQDs. We envision that the proposed CQDs would provide unique opportunities in the fabrication of novel pH sensor systems and fluorescence imaging where a wide range of pH sensitivity is required.

Characterization of polyanilines synthesized at different pH for electrochemical sensing and supercapacitor applications

Here we synthesized different polyanilines from the aqueous HCl solutions of different pH through chemical oxidative polymerization of aniline using potassium persulphate as oxidant at 10 ± 2 °C. The polymers were characterized using UV–Visible spectra, FT-IR and SEM. The dependence of pH of the acid medium used for the synthesis on the electrochemical characteristics - specific capacitance and current sensing of the synthesized polyanilines were studied by cyclic voltammetric and chronopotentiometric techniques. Polyaniline experiences a sharp drop in its performance as a supercapacitor when it is synthesized from a higher pH medium. The highest specific capacitance was obtained for polyaniline synthesized from pH = 0 medium. We have also verified that the electrochemical reactions of all the synthesized polyanilines can sense their electrical working energetic conditions. The sensing capabilities (here the current sensing) of polyanilines synthesized at different pH showed a linear relationship between the consumed electrical energy and the applied current. The current sensitivity of polyaniline slightly decreases as the pH of reaction media increases from 0 to 2 and markedly decreases for polyaniline from solutions of pH above 2.

Comparison Study Between Encapsulation of Acalypha indica Linn Extracts with Chitosan-PCL and Chitosan-OA

Drug delivery is one of the major applications in the biodegradable polymer science. Chitosan is a non-toxic and naturally biodegradable polymer. It is soluble in acidic aqueous media and insoluble in higher pH media. Chitosan has been modified to improve its properties such as stability and the modified derivatives have been widely used in many applications especially for drug delivery. There are several kinds of chitosan modification. This study investigated the modification of chitosan with polyester-types of polymer and the fatty acidbased polymer. The aim of this study is to compare the formation encapsulation of chitosan-oleic acid conjugate (Ch-OA) and chitosan- polycaprolactone(PCL) copolymer for the encapsulation of Acalypha indica active compounds for drug delivery by using emulsion-solvent evaporation technique. The crude extracts have been extracted and the phytochemicals inside the crude extracts are less stable in nature. These active compounds need to be encapsulated to stabilize them and delivered well into the body system. As for conclusion, chitosan:PCL is able to form better encapsulation using this method.

The Effect of Backbone Structure on Functional Properties in Anion Exchange Membranes; Comparison of Poly(fluorene) with Poly(biphenylene) and Poly(terphenylene)s

The irreversible environmental impacts caused by energy generation from fossil fuels calls for a paradigm shift in the energy conversion and storage. Among many alternative energy technologies hydrogen based electrochemical devices gain significance because of its high efficiency and environmentally benign byproduct formation. Ion exchange polymers play a key role in electrochemical devices as solid-state electrolytes conducting ions between the electrodes while acting as a physical barrier to reactants and electrons. Electrochemical reactions carried out under high pH medium in fuel cells and electrolyzers using anion exchange membranes (AEMs) have gained significant traction recently, due to the prospect of using non-platinum group metal electrocatalyst for the redox reactions. While AEMs remain a crucial part of electrochemical devices such as alkaline exchange membrane fuel cells and alkaline electrolyzers, the absence of a suitable membrane is an impediment for the widespread usage of these technologies. Recently our group synthesized several anion exchange polymers via super acid catalyzed Friedel-Crafts polycondensation. These AEMs, BPN1-100, m-TPN1-100 and p-TPN1-100 showed excellent stability in alkaline medium due to the absence of labile aryl-ether bonds in the polymer backbone. Additionally, they also exhibit good ionic conductivities and mechanical properties. In order to further understand the effects of polymer backbone morphology in AEM properties another polymer FMN1-100 was synthesized. In this study, properties of the AEMs BPN1-100, m-TPN1-100, p-TPN1-100, and FMN1-100 (Figure 1) were evaluated and compared for the purpose of anion exchange polymer electrolytes. Furthermore, FMN2-60 and FMN2-50 containing dication side chains were synthesized and compared against FMN1-100 containing a monocation side chain. The effect of the backbone architecture and side chain cations on the AEM properties such as, ionic conductivity, water uptake ratio, mechanical properties, morphology, and alkaline stability were investigated to broaden the knowledge of polymer design for AEMs. Figure 1

Influence of phosphorus on the electrocatalytic activity of palladium nickel nanoalloy supported on N-doped reduced graphene oxide for ethanol oxidation reaction

For successful commercialization of the direct ethanol fuel cell (DEFC), cheaper long-lasting lower noble metal contained anode catalyst is highly needed. For this, nitrogen-doped reduced graphene oxide (N-rGO) supported palladium-nickel alloy nano catalysts with tuned Pd:Ni ratio was synthesized using chemical co-reduction method. Aiming to have better catalytic efficacy and further reduction of cost, nonmetal phosphorus is incorporated to the most active Pd3Ni/N-rGO catalyst to prepare lower Pd contained Pd3NiP/N-rGO ternary catalyst. X-ray diffraction confirms the fcc alloy structure and microscopic study reveals precisely that spherical particles of nano dimension are well distributed on the N-rGO support. XPS analysis confirms the presence of nitrogen and phosphorus along with Pd and Ni in the catalyst matrix. Electrochemical evaluation by cyclic voltametry, chronoamperometry and electrochemical impedance spectroscopy showed that among the bimetallic catalysts studied, Pd3Ni/N-rGO catalyst exhibits synergistic and optimum electro-catalytic performance and poisoning tolerance towards ethanol oxidation reaction (EOR) in the high pH medium. But, phosphorus containing Pd3NiP/N-rGO catalyst shows even more enhanced catalytic performance (2223 mA mg−1Pd current density) than its bimetallic counterpart (1416 mA mg−1Pd current density) signifying that nonmetal phosphorus can effectively promote ethanol oxidation. Moreover, N-doped reduced graphene oxide enhances the catalyst dispersion by creating new active sites, which improves the proper utilization of noble metal Pd. Additionally, the synergistic effect between Pd, Ni and P particles and the support caused by N doping helps to enhance electrocatalytic activity and long-term stability of the catalyst.

Impact of pH on succession of sourdough lactic acid bacteria communities and their fermentation properties.

Sourdough, a traditional fermented dough, is made via natural fermentation by lactic acid bacteria (LAB). Its pH changes from near neutral to acid during the subculture process. However, the product quality of subcultured sourdough depends on the unpredictable succession of LAB communities, the influential factors of which are still unclear. To elucidate one end of the LAB community succession mechanism, we evaluated the effect of pH by designing four subculture experiments using a model medium adjusted to pH 6.7, 5.5, and 4.5, as well as a natural sourdough subculture. All experiments began by inoculating a sourdough LAB mixture, and both bacterial successions and fermentative properties were monitored until ten subculture steps. In media subcultures, lactic acid production was higher in higher pH media. Three LAB genera, Weissella, Pediococcus, and Lactobacillus, each represented by one operational taxonomic unit (OTU), were successively detected in all subcultures. In later steps with lower pH media, an OTU closely related to Lactobacillus brevis dominated, replacing an OTU closely related to the Weissella cibaria-confusa group that was more dominant than the L. brevis OTU in the near-neutral pH medium. In the sourdough subculture, the three genera were also detected, while Lactobacillus was dominant in earlier steps due to the emergence of an OTU closely related to Lactobacillus sanfranciscensis. These results suggest that a lower pH is favorable for the sequence of sourdough bacterial community evolution finalizing with Lactobacillus domination. Further research is needed to elucidate additional factors other than pH that influence the pattern of LAB community shift.

Alkaline extracellular conditions promote the proliferation and mineralization of a human cementoblast cell line.

To investigate the proliferation and mineralization of a human cementoblast cell line under alkaline conditions. A human cementoblast cell line was cultured in alkaline media with several pHs (pH 7.6, 8.0 and 8.4) without CO2 . Cell numbers, phospho-p44/42 expression, alkaline phosphatase (ALP) activity and mineralization were evaluated. The significance of differences between groups was assessed using two-way analysis of variance 15 (ANOVA) followed by Bonferroni's multiple comparison test (α=0.01). Cell numbers increased in a time-dependent manner in the high pH medium groups. Western blot analysis revealed the upregulated expression of phospho-p44/42 under alkaline conditions. ALP activity was also increased at pH 8.0 and 8.4. Alizarin red staining revealed increased mineralization in the high pH medium groups. The incorporation of the transient receptor potential ankyrin subfamily member 1 (TRPA1) antagonist HC030031 markedly negated the effect on proliferation and mineralization. Extracellular alkaline conditions promoted the proliferation and mineralization of human cementoblasts invitro via TRPA1.

Removal of Barite-Scale and Barite-Weighted Water- or Oil-Based-Drilling-Fluid Residue in a Single Stage

Summary Barite is one of the most common weighting materials used in drilling fluids for deep oil and gas wells. Consequently, the main source of solids forming the filter cake is “barite particles,” the weighting material used in drilling fluids. Barite is insoluble in water and acids such as hydrochloric acid (HCl) and formic, citric, and acetic acids, and barite is moderately soluble in chelating agents such as ethylenediaminetetraacetic acid (EDTA). The present study introduces a new formulation to dissolve barite scale and barite filter cake using converters and catalysts. Barite can be converted to barium carbonate (BaCO3) in a high-pH medium (pH = 12) using a combination of potassium hydroxide (KOH) and potassium carbonate (K2CO3) solutions. Subsequently, HCl or low-pH chelating agents can be used to dissolve the BaCO3. Another solution is to use the EDTA chelating agent at pH of 12 and K2CO3 or KOH as a catalyst/converter in a single step. The removal formulation also contains a polymer breaker (oxidizers or enzymes). The three components of the new formulation are compatible with each other and stable up to 300°F. Solubility experiments were conducted using industrial-grade barite (particle size of 30 to 60 µm). The solubility experiments were conducted at 300°F for 24 hours. Varying concentrations of the catalyst were added to determine the optimal concentration. The developed formulation was tested for the removal of filter cake formed by barite drilling fluid using a high-pressure/high-temperature (HP/HT) cell. Filter-cake removal was conducted for filter cakes formed by both water- and oil-based drilling fluids. The results of this study show that the barite-removal efficiency of the new formulation is 87% for water-based mud (WBM) and 83% for oil-based mud (OBM). The test results show that the solubility of barite particles in 0.6 M EDTA is 62 wt% in 24 hours at 300°F. Adding K2CO3 or KOH catalyst to the 0.6-M-EDTA solution increases the solubility of barite to 90 wt% in 24 hours at 300°F. Thus, barite scale can be removed efficiently using high-pH formulations (pH = 12) to avoid the safety issues associated with HCl. Because the EDTA chelating agent is compatible with the polymer breaker (oxidizer), the filter cake can be removed in a single stage. The concentration of the components of the formulations used in this study is as follows: 10 wt% oxidizer, 10 wt% K2CO3 or KOH concentration (catalyst/converter), and 0.6 M EDTA. The developed formulations achieved more than 80% filter-cake removal in both oil-based and water-based drilling fluids. For OBM, a water-wetting surfactant, a mutual solvent, and an emulsifier were added to the formulation to remove the oil and to make the surface of the filter cake water-wet. In this study, two solutions are proposed to remove the barite filter cake and barite scale from oil and gas wells at different conditions. The first one is using HCl after converting the barium sulfate (BaSO4) to BaCO3 by use of a high-pH medium such as KOH and K2CO3. Although HCl can easily remove the resulting BaCO3, the generated barium chloride (BaCl2) is a safety and health concern. The second method is to create a high-pH medium (pH = 12) using the removal fluid itself, which uses the EDTA chelating agent in addition to using K2CO3 or KOH as converters.

Preparation and characterization of silicagel from silicate solution obtained by autoclave treatment of copper slag

The formation of silicagel from sodium silicate solution obtained by alkaline autoclave treatment of copper slag was investigated. The influence of the parameters of the gelation process (type of acid used, the pH of the medium, and drying conditions) on the structure and properties of the resulting silicagel, were studied. Silicagels obtained under different conditions were characterized by XRD, low-temperature nitrogen adsorption, FTIR, SEM, and TEM analyses. All silicagels are amorphous with a different degree of crosslinking. The physicochemical characterizations show that the type of acid, the mode of drying and pH influence the dispersity and the morphology of the silicagels prepared. Silicagels obtained at low-pH medium have a higher specific surface area and porosity than silicagels obtained at high-pH medium. Silicagels obtained at low-pH medium have no micropores and their porosity is only expressed by a narrow mesopore distribution. Freeze-drying improves the porosity of the silicagels obtained at high-pH medium. It is confirmed that the dilution of the sodium silicate solution affects the initial pH and the time of gelation.The moisture absorption capacity of the prepared silicagels increases in the following order: silicagel obtained at high-pH medium, dried in air < silicagel obtained at high-pH medium, freeze-dried < silicagel obtained at low-pH medium, dried in air.

Synthesis and properties of 1D manganese-doped hematite particles

The properties of Mn-doped hematites and their Mn-doped precursors were investigated using the 57Fe Mössbauer spectroscopy, XRD, FT-IR, UV/Vis/NIR and FE SEM. Mn-doped goethite precursors were synthesized in a high alkaline pH medium starting with iron choline citrate. The XRD analysis of all Mn-doped goethites and Mn-doped hematites showed only the presence of a goethite or hematite crystal structure. The RT Mössbauer spectrum of reference goethite showed typical features of precipitated goethite. With increased Mn-doping the spectral lines of the goethite precursor were broadening, the hyperfine magnetic field decreased and the relative intensity of central quadrupole doublets increased. The RT Mössbauer spectra of Mn-doped hematite showed features of the hematite phase and increased relative intensity of a central quadrupole doublet which disappeared in the spectra recorded at liquid N2 temperature. The presence of this superparamagnetic component in the RT Mössbauer spectra is a direct consequence of Mn-doping. In the FT-IR spectra the characteristic IR bands sensitive to Mn-doping were identified. The UV/Vis/NIR spectra showed shifts of optical absorption bands and a strong absorption increase in the visible part of the spectrum. FE SEM images of Mn-doped goethite precursor showed a change in shape from rod to star-like particles. Upon heating at 300 °C for 4 h in air, the obtained Mn-doped hematite particles preserved the original morphologies of Mn-doped goethite precursors. Taking into account the superparamagnetic spectra (RT and liquid N2 temperature), XRD and the corresponding FE SEM images of Mn-doped hematite particles it can be concluded that these particles contained substructure. In this substructure of Mn-doped hematites the fraction of superparamagnetic crystallites (domains) is given by calculated value for the superparamagnetic doublet present.

Bimetallic Co/Zn-ZIF as an Efficient Photocatalyst for Degradation of Indigo Carmine

Cobalt-incorporated zeolitic imidazolate framework ZIF-8 was synthesized by a simple one-pot synthesis method at room temperature. Powder X-ray diffraction patterns and energy dispersive X-ray spectrum confirmed the formation of the bimetallic Co/Zn-ZIF structure. UV-Vis diffuse reflectance spectra revealed that the bimetallic ZIF had a lower HOMO-LUMO gap compared with ZIF-8 due to the charge transfer process from organic ligands to cobalt centers. A hydrolytic stability test showed that Co/Zn-ZIF is very robust in aqueous solution - the most important criterion for any material to be applied in photodegradation. The photocatalytic efficiency of the synthesized samples was investigated over the Indigo Carmine (IC) dye degradation under solar simulated irradiation. Cobalt incorporated ZIF-8 exhibited high efficiency over a wide range of pH and initial concentration. The degradation followed through three distinct stages: a slow initial stage, followed by an accelerated stage and completed with a decelerated stage. Moreover, the photocatalytic performance of the synthesized samples was highly improved in alkaline environment rather than in acidic or neutral environments, which may have been because in high pH medium, the increased concentration of hydroxyl ion facilitated the formation of hydroxyl radicals, a reactive species responsible for the breaking of the Indigo Carmine structure. Thus, Co/Zn-ZIF is a promising and green material for solving the environmental pollution caused by textile industries.

The role of H+/OH− channels in saline pathology of Chara australis: brief history

The pH banding pattern, observed in Chara and Nitella early last century, suggests that there are H+ or OH− conducting channels in the alkaline bands of the characean plasma membrane. If the cells are exposed to high pH medium, pHo, these channels become the dominant membrane conductance: High pH state. Goldman-Hodgkin-Katz (GHK) equation can model the current-voltage (I/V) characteristics of this state with either H+ or OH− as permeant ion. However, H+ requires unrealistically large increases in channel conductance/number parameter as pHo increases. Recently we discovered a typical spiky noise in the membrane potential difference (PD) of salt sensitive Chara australis, appearing immediately upon exposure to saline. The H+/OH− channels are thought to open transiently in small patches all over the cell, while negative membrane PD does not support their open state/s. As the membrane PD depolarizes due to inhibition of the proton pump by salinity, the H+/OH− channels remain open to dominate the I/V characteristics, which can also be modeled by GHK equation. The addition of 1 mM ZnCl2, the main known blocker of animal H+ channels, abolishes both the PD noise and the H+/OH− I/V characteristics in high pH state and in salt stressed cells. Confocal microscopy and fluorescein isothiocyanate (FITC)-dextran illuminate the pH changes around cells and reveal transient bright spots early in saline exposure, becoming more numerous and fixed in space with time in saline APW.

Xanthine sensor development based on ZnO–CNT, ZnO–CB, ZnO–GO and ZnO nanoparticles: an electrochemical approach

The wet-chemical method was used to prepare the various ZnO–CNT, ZnO–CB, ZnO–GO nanocomposites, and ZnO nanoparticles in higher pH medium, which were finally utilized with 5% nafion to produce a thin film of NCs/Nafion/GCE sensor that has a faster response towards selected xanthine with higher sensitivity, lower detection limit, and large linear dynamic range by electrochemical approach.

Comparative Carbon Dioxide Capture from Air between Chlorella vulgaris and Chlorella sorokiniana

Background/Objectives: In this research, the potential of a commercial microalgae species namely, Chlorella vulgaris and a native microalgae species isolated from a palm oil mill effluent, Chlorella sorokiniana to capture carbon dioxide from the air was investigated. Methods/Statistical Analysis: Both of the species were cultured in Bold Basal Medium (BBM) at three different concentrations denoted as 1.0 BBM, 2.0 BBM and 3.0 BBM. Among the parameters that were analyzed included pH value, optical density, specific growth rate, dry biomass and the rate of carbon dioxide gas captured by the microalgae. Findings: Different medium concentrations caused a different growth rate of C. vulgaris and C. sorokiniana . C. vulgaris favored an environment with a lower pH value ranging from pH 6.0-6.5 while the native isolated microalgae species, C. sorokiniana prefers a higher pH medium which has a range of 7.0-8.0. In addition, C. sorokiniana has a higher specific growth rate, 0.0452 h -1 in 3.0 BBM compared to C. vulgaris that only has a specific growth rate of 0.0013 h -1 in 1.0 BBM. C. vulgaris had the highest dry biomass value of 0.016 g/L in 1.0 BBM in comparison to C. sorokiniana with 2.438 g/L for the dry biomass in 3.0 BBM. It is also observed that the C. sorokiniana microalgae in 3.0 BBM has the highest potential of capturing carbon dioxide gas from air at a rate of 4.584 g/L in comparison with C. vulgaris microalgae in 2.0 BBM that only captured 0.030 g/L of carbon dioxide from air. Application/Improvements: The locally isolated microalgae have shown a vast potential as an alternative for carbon dioxide capture.

Effect of medium variations (zinc supplementation during oocyte maturation, perifertilization pH, and embryo culture protein source) on equine embryo development after intracytoplasmic sperm injection

Prospective studies were conducted to help define procedural factors affecting in vitro embryo production via intracytoplasmic sperm injection (ICSI) of equine oocytes. In experiment 1, use of 10% fetal bovine serum as a protein source in embryo culture medium resulted in a higher blastocyst rate than did use of a combination of 3% fetal bovine serum, 3% equine preovulatory follicular fluid, and 4% human serum substitute (37% vs. 15%, respectively, P < 0.05). In experiment 2, the effect of zinc supplementation (0, 0.5, 1, or 1.5 μg/mL) during IVM was examined. There were no significant differences in rates of cleavage or blastocyst development (20%–31%). However, the proportion of blastocysts that developed on Day 7 for the added-zinc treatments was significantly higher than that for the control treatment (45% vs. 8%). In experiment 3, we tested whether use of high-pH medium (pH 8.0–8.4) during ICSI procedures would improve blastocyst rate when sperm with low cleavage rates after ICSI was used. When high-pH conditions were used for sperm preparation and also for the first 2 hours of incubation of injected oocytes after ICSI, the cleavage rate was unaffected but no blastocysts developed (0% vs. 24% for control). When high-pH conditions were used for sperm preparation only, the blastocyst rate was 37%. This was repeated using sperm from a second stallion; there was no significant difference in cleavage or blastocyst rates between sperm preparation in high pH vs. control medium. These findings add to our knowledge of factors affecting in vitro production of equine embryos.

Response of Citrus rootstocks to iron deficiency under high pH conditions

Turkey is one of the major citrus producing countries in the Mediterranean Basin. Approximately 90% of the total citrus production in Turkey is carried out in the Mediterranean Region. Soil of the Mediterranean region is calcareous and because sour orange is tolerant to high pH, the rootstocks is widely used in this region. Sour orange rootstock, which is well adapted to calcareous soils, has positive effects on yield and quality, but is extremely sensitive to Citrus Tristeza Virus disease. Because sour orange is very sensitive to tristeza, there is a need to find an alternative rootstock that is well adapted to calcareous soils and has good fruit yield and quality. For this purpose, 16 citrus rootstock and genotypes could be used as a rootstock, were tested against high-pH conditions for iron chlorosis in growth chamber. At the end of this experiment, Tuzcu 891 sour orange, Gou Tou sour orange and Antalya Cleopatra mandarin were the most tolerant; Duncan grapefruit, Tuzcu 31-31 sour orange, Sunki mandarin, Nasnaran mandarin, Cleopatra mandarin x Swingle citrumelo hybrid, Carrizo citrange, C-35 citrange and Marumi kumquat were moderate tolerant; Volkameriana, Swingle citrumelo, Pomeroy trifoliate and Sarawak bintangor were sensitive; and a local trifoliate was found to be the most sensitive to iron chlorosis in a high pH medium.

The Vacuolar Manganese Transporter MTP8 Determines Tolerance to Iron Deficiency-Induced Chlorosis in Arabidopsis.

Iron (Fe) deficiency is a widespread nutritional disorder on calcareous soils. To identify genes involved in the Fe deficiency response, Arabidopsis (Arabidopsis thaliana) transfer DNA insertion lines were screened on a high-pH medium with low Fe availability. This approach identified METAL TOLERANCE PROTEIN8 (MTP8), a member of the Cation Diffusion Facilitator family, as a critical determinant for the tolerance to Fe deficiency-induced chlorosis, also on soil substrate. Subcellular localization to the tonoplast, complementation of a manganese (Mn)-sensitive Saccharomyces cerevisiae yeast strain, and Mn sensitivity of mtp8 knockout mutants characterized the protein as a vacuolar Mn transporter suitable to prevent plant cells from Mn toxicity. MTP8 expression was strongly induced on low-Fe as well as high-Mn medium, which were both strictly dependent on the transcription factor FIT, indicating that high-Mn stress induces Fe deficiency. mtp8 mutants were only hypersensitive to Fe deficiency when Mn was present in the medium, which further suggested an Mn-specific role of MTP8 during Fe limitation. Under those conditions, mtp8 mutants not only translocated more Mn to the shoot than did wild-type plants but suffered in particular from critically low Fe concentrations and, hence, Fe chlorosis, although the transcriptional Fe deficiency response was up-regulated more strongly in mtp8. The diminished uptake of Fe from Mn-containing low-Fe medium by mtp8 mutants was caused by an impaired ability to boost the ferric chelate reductase activity, which is an essential process in Fe acquisition. These findings provide a mechanistic explanation for the long-known interference of Mn in Fe nutrition and define the molecular processes by which plants alleviate this antagonism.

Water absorption and moisture permeation properties of chitosan/poly(acrylamide-co-itaconic acid) IPC films

In this work, aqueous solutions of chitosan (Ch) and [poly(acrylamide(AAm)-co-itaconicacid(IA)] have been mixed to yield Ch/poly(AAm-co-IA) Inter-polyelectrolyte complex (IPC) films. The films were characterized by FTIR, X-ray diffraction (XRD) and thermo gravimetric analysis (TGA). There was remarkable increase in the crystalline nature of IPC films. The films were investigated for their water absorption capacity in the physiological fluid (PF) of pH 7.4 at 37°C. The amount of IA present in the film forming solutions affected the water absorption behavior of the resulting films. The dynamic water uptake data were interpreted by various kinetic models. The effect of pH on the swelling ratio (SR) indicated that the films showed highest swelling in lower as well as higher pH media. The water vapor transmission rates (WVTR) were obtained in the range of 6000–6645g/m2/day.

Fabrication of highly sensitive ethanol sensor based on doped nanostructure materials using tiny chips

Doped CuO–Fe2O3 nanocubes (NCs) are prepared via a facile wet-chemical process using active reactant precursors with reducing agents in high pH medium (pH &gt; 10).