Water pHs Research Articles

Mitigation of Mycotoxins in Food-Is It Possible?

Among microorganisms found in food, fungi stand out because they are adaptable and competitive in a large range of water activities, temperatures, pHs, humidities and substrate types. Besides sporulating, some species are toxigenic and produce toxic metabolites, mycotoxins, under adverse biotic and abiotic variables. Microorganisms are inactivated along the food chain, but mycotoxins have stable structures and remain in ready-to-eat food. The most prevalent mycotoxins in food, which are aflatoxins, fumonisins, ochratoxin A, patulin, tenuazonic acid, trichothecenes and zearalenone, have maximum tolerable limits (MTLs) defined as ppb and ppt by official organizations. The chronic and acute toxicities of mycotoxins and their stability are different in a chemical family. This critical review aims to discuss promising scientific research that successfully mitigated levels of mycotoxins and focus the results of our research group on this issue. It highlights the application of natural antifungal compounds, combinations of management, processing parameters and emergent technologies, and their role in reducing the levels and bioaccessibility. Despite good crop management and processing practices, total decontamination is almost impossible. Experimental evidence has shown that exposure to mycotoxins may be mitigated. However, multidisciplinary efforts need to be made to improve the applicability of successful techniques in the food supply chain to avoid mycotoxins' impact on global food insecurity.

Anaesthetic effect of clove basil (Ocimum gratissimum L.) essential oil on the giant river prawn (Macrobrachium rosenbergii, De Man 1879) exposed to different water pHs

The increasing concern for invertebrate welfare has led to improvements in management procedures and protective legislation; under discussion is the use of anaesthetic agents to improve the welfare of farmed prawns. In parallel, the aquatic environments present changes in their physical and chemical characteristics, like the acidification of waters. With this perspective, our study analysed the effectiveness of Ocimum gratissimum essential oil (EO-OG) as a natural anaesthetic for Macrobrachium rosenbergii at different concentrations and water pHs. Juvenile M. rosenbergii were exposed to five different EO-OG concentrations (0, 100, 200, 300, and 400 μL L−1) and vehicle control (ethanol), at two water pHs (8.08 ± 0.10 and 6.42 ± 0.15). Induction time was EO-OG concentration-dependent regardless of water pH; i.e. the time required for sedation and anaesthesia decreased with the increase of EO-OG concentration. No correlation was found between recovery time and EO-OG concentration. The most effective EO-OG concentration was 400 μL L−1, with prawn sedation in 2.0–2.5 min, anaesthesia in 3.5–4.1 min, and full recovery in 16 min, regardless of water pH. The different tested water pHs influenced sedation time; i.e. sedation time was higher in mild acidic water than in mild alkaline water. Anaesthesia induction and recovery times were similar at both water pHs. Survival rates were 100% in all experimental groups. In summary, EO-OG is effective as a sedative and anaesthetic for juvenile M. rosenbergii in routine procedures, at the recommended concentration of 400 μL L−1, with mild alkaline water.

Phosphorus Fractionation in Sediment and Agricultural Soils Surrounding Lake Toho in the Rainy Season

In recent years, land use related to anthropogenic activities has contributed to high surface water contamination. During the last decade, Lake Toho, in the Republic of Benin, has suffered anthropogenic pollution by the use of fertilizers from farmers around the lake. We assessed the mobility and bioavailability of phosphorus in cultivated soils around the lake to detect the extent of the contamination. The results showed that the cultivated soils around Lake Toho are weakly acidic or even basic with water pHs between 6.25 and 8.3. The humidity of cultivated soils varies from 1% to 38% on different horizons. The content of organic matter is ranged from 40.30% to 49.70%. The total phosphorus concentration ranged from 1049.74 μg.g-1 to 28436.52 μg.g-1 with a high rate of enrichment at the 30 cm horizon. The high contents of total phosphorus recorded at the superficial horizon were due to the use of fertilizers to amend the soil. All forms of phosphorus are represented (P-L, P-Fe, P-Ca, P-Al, and P-OM). The organic fraction predominates on the upper layer of the soil except for sites located outside crop fields. The strong correlation between the Total phosphorus (TP), the (Pr), mobile phosphorus (P-L), and the to organic matter-bound Phosphorus (P-OM) showed that the high phosphorus contents at the upper horizon of the soil were due not only to the anthropogenic contribution but also to the source rock. The remarkable presence of phosphorus in the P-L and P-MO fractions poses a risk of phosphorus transport to the lake. This can lead to eutrophication which can cause the death of fish and harmful toxins development.

Management of Brackish Water for Crop Production in Two Different Textured Soils

| In Pakistan, renewable freshwater resources are decreasing due to unpredictable rainfall changes and farming community is compelled to use underground brackish water. Therefore, a lysimetric study was undertaken to remediate hazardous effects of brackish water on rice-wheat crops through practicable and economical methods in two different textured soils. Treatments were: (A) Types of soils. 1) sandy loam, 2) clay loam, (B) Remedial strategies, 1). canal water, 2) saline-sodic tube well water (continuous), 3) three irrigations of tube well water and two of canal water in a cyclic manner (short cyclic use), 4) tube well water + gypsum @ RSC of water, 5) tube well water+ canal water in 1:1 ratio (conjunctive use). Data showed that the highest biomass and paddy/grain yield were produced by canal water (T1) followed by (T3) where three irrigations of tube well water and two of canal water were used in a short cyclic manner. Whereas, growth and yield of rice and wheat crops were significantly reduced by continuous use of brackish water (T2) and maximum pHs, ECe and SAR were noted in this treatment in both textured soils. Different management practices (use of gypsum and blending) also mitigated the ill effects of saline-sodic water. Therefore, it was concluded that when fresh-water resources are finite and use of saline-sodic water is inevitable, cyclic use of canal and saline-sodic water is a wise and profitable management strategy with marginal effect on crop productivity and proves least detrimental for soil health. Comparison of two different textured soils also revealed that brackish water deteriorated the soil properties of clay loam soil more in comparison to sandy loam soil that highlighted the primary role of soil texture for salinity development and must be recognized while using the brackish water for irrigation purpose.

Właściwości alkalizujące wybranych krzemianowo-wapniowych uszczelniaczy kanałowych. Badanie in vitro

ABSTRACTIntroduction: The aim of this in vitro study was to assess the pH values of selected calcium-silicate root canal sealers in comparison with AH Plus resin-based root canal sealer.Materials and methods: Six root canal sealers were included in this study: BioRoot RCS (Septodont, France), GuttaFlow bioseal (Coltėne/Whaledent, Switzerland), MTA Fillapex (Angelus, Brazil), Total Fill BC Sealer (FKG, Switzerland), Well-Root ST (Vericom, Korea) and AH Plus (Dentsply, DeTrey, Germany). Materials samples (n = 6) were placed in dishes and immersed in 10 mL of distilled water (pH = 6.8). After 1, 3, 24, 48, 72, 168, 336 and 504 hrs, water pH was determined with a pH meter calibrated with a solution of known pH. Data were statistically analyzed using Student-t test (p < 0.05).Results: There were differences in the water pH between the materials tested. The highest water pHs were exhibited by Total Fill BC Sealer, Well-Root ST and BioRoot RCS (pH ~12), followed by GuttaFlow bioseal (pH ~10.5) and MTA Fillapex (pH ~9). The lowest pH was shown by AH Plus (pH ~8).Conclusions: All calcium-silicate root canal sealers studied are able to elevate the pH level, which could have biological and antimicrobial effects. The AH Plus root canal sealer has poor alkalizing properties.

Growth and biochemical variables in Amazon catfish ( Pseudoplatystoma reticulatum ♀ x Leiarius marmoratus ♂) under different water pH.

Although fish may live in different aquatic environments, variations in the water quality parameters, mainly pH, may have a substantial impact in their development and welfare. The objective of this study was to test the effect of different pH levels on the growth performance and biochemical variables in Amazon catfish juveniles (Pseudoplatystoma reticulatum x Leiarius marmoratus). Fish were subjected to four different water pH levels (4.56, 6.0, 7.24, and 8.90) for 40 days. The total ammonia and alkalinity were higher and lower, respectively, in the treatments with water pHs 4.56 and 6.00 than at the other water pH levels. The un-ionized ammonia was higher at water pH 8.90 than at the other water pH levels. Amazon catfish exposed to water pH 4.56 presented specific growth rate and weight gain significantly higher than other water pH values. In general, fish under exposure to water pH 8.90 presented lower growth performance than other water pH values. Biochemical changes were recorded at all water pH. In conclusion, water pH 4.56 is recommended for an Amazon catfish production system, since fish presented higher growth and water quality variables were kept within adequate limits for aquaculture.

English

Some factors on sporulation of Lecanicillium lecanii CA-1-G by one-time-at-a-factor have been studied. These factors include carbon and nitrogen sources, carbon-to-nitrogen ratios, mineral elements and vitamins together with water potentials, temperatures, dark/light cycles and pHs. On the basis of these results, together with “two-step” cultivation and orthogonal method, we optimized the culture conditions for sporulation of this fungus: inoculated with spore suspension on the basal medium ematophagous fungi (sucrose 19.00 gl-1, soy peptone 4.06 gl-1, K2HPO4 1.00 gl-1, KCl 0.50 gl-1, MgSO4 0.50 gl-1, FeSO4 0.01 gl-1and agar 13.00 gl-1) for 4 days, then transferred to sporulation medium (glucose 9.08 gl-1, soy peptone 10.00 gl-1, CuSO4·5H2O 0.01 gl-1, ZnSO4·7H2O 0.05 gl-1, CaCl2 1.00 gl-1, H3BO4 0.005 gl-1, Na2MoO4 0.005 gl-1 and agar 13.00 gl-1) for another 4 days with the environmental conditions of -7.3 MPa/pH 4/light 24 h/temperature 29°C for sporulation and -7.3 MPa/pH 3/light 12h/temperature 23°C for mass production. This research reflects on some physiology on nutrients and environmental characteristics of this fungus, and also gives the essential information for its industrialization.   Key words: Biocontrol, biomass, environment, L. lecani, nutrition, sporulation.

Effect of irrigation water pH and acidifying source on silvery-thread moss (Bryum argenteum Hedw.) establishment

Abstract Many bryophytes are intolerant of osmotic stresses; nevertheless, Bryum argenteum often spreads in golf course greens irrigated with water containing a moderate amount of sodium and/or bicarbonates. The ability of B. argenteum to survive in this stressful environment could be linked to the use of acid injection systems, which are often retrofitted to irrigation systems to combat the negative effects of these harmful salts. The objective of this study was to determine if altering the pH of sodic irrigation water using either sulfuric or hydrochloric acid affects the growth of B. argenteum. Secondarily, if growth of B. argenteum was affected, we sought to understand whether that effect was due to differences in nutrient uptake or availability under the different water pHs and/or acidifying sources. Phosphate buffer solutions (0.01 M, pH = 9) were titrated with each acid to obtain pHs 5, 6, 7 and 8. Irrigation solutions were applied daily to pots containing a sand substrate and nascent B. argenteu...

Modeling Penicillium Expansum Growth Response to Thyme Essential oil at Selected Water Activities and pH Values Using Surface Response Methodology

Our objective was to evaluate, using a full factorial design, the effects of selected water activities (0.990, 0.945, or 0.900), pHs (5, 4, or 3), and thyme essential concentration (TEO, 0, 25, 50, or 100ppm) oil on Penicillium expansum lag time (λ) and radial growth rate (μm) obtained by modeling mold response using Gompertz equation, and corresponding polynomial quadratic models. Potato-dextrose agar formulated with every studied factor combination was inoculated with 103 spores/ml, and incubated at 25°C up to 30 days. Mold colony diameter was periodically measured during incubation and adjusted with Gompertz equation to determine λ and μm. Decreasing aw and pH, and increasing TEO concentration decreased μm and increased λ. At low aw and pH, the increase in TEO concentration had a dramatic effect on P. expansum response since 25ppm of TEO inhibited its growth for 30 days at 25°C. Gompertz parameters exhibited that P. expansum was sensitive to the evaluated combined factors, allowing us to construct a secondary predictive growth model. TEO in combination with aw and pH reduction effectively inhibited P. expansum growth.

EVALUATION OF ROOTSTOCK EFFECT ON TOLERANCE TO IRON CHLOROSIS AND CYTOSPORA CANKER IN PEACHES

The Western Colorado peach growing area is characterized by semi-arid conditions with heavy soils, and high soil and water pHs contributing to severe leaf chlorosis. ‘Redhaven’ peach trees grafted to 17 rootstocks were planted in a randomized block design with 8 replications in 2009 at the Western Colorado Research Center. One of the objectives of this study was to evaluate the performance of the trees under Colorado climatic and edaphic conditions. Tree growth measurements and survival were recorded each year. By the third year after planting, trees showed different levels of foliar chlorosis probably caused by micronutrient deficiency aggravated by high soil pH. These trees were rated for chlorosis based on visual observation (0-10 scale) where 0= no chlorosis to 10 having almost total canopy chlorosis in appearance. Fruit data collected in the third year showed a significant (P=<0.0001 and r2 = 0.59) impact of rootstocks on chlorosis where trees on different rootstocks produced different levels of chlorosis. The highest chlorosis was observed with ‘HBOK 10’, followed by ‘KV010-123’, and ‘KV010-127’; whereas many trees on rootstocks such as ‘Viking’, ‘Atlas’, ‘Guardian®’, ‘Mirobac’ (aka ‘Replantpac’) had lower chlorosis levels and most of the others were intermediate. Tree circumference was significantly affected by the chlorosis (P= 0.004). There was no impact of chlorosis on total fruit yield per tree, total number of fruits per tree, individual fruit weight, or incidence and severity of Cytospora canker among the trees grafted to different rootstocks. Trees on rootstocks such as ‘Atlas’, ‘Fortuna’, and ‘Mirobac’ had 100% disease infection. The majority of rootstocks had at least 12.5% tree death except ‘Viking’, which had 50% mortality. Tree death on ‘Viking’ occurred during the first year after planting; whereas most other trees on different rootstocks died in the second and third year due to Cytospora Canker.

Effect of pH and distance between electrodes on the performance of a sediment microbial fuel cell

The performance of three sediment microbial fuel cells (SMFCs) was evaluated at different feed water pH and electrode spacing for chemical oxygen demand (COD) removal, total nitrogen (TN) removal, and power density; while offering in situ remediation of aquaculture pond water. SMFC-A was operated at the feed water pH of 6.5 and spacing between the electrodes of 100 cm. SMFC-B and SMFC-C were operated at feed water pHs of 8.5 and 6.5, respectively, and distance between electrodes of 50 cm. The anode and cathode were connected with concealed copper wire through an external load of 100 Ω. The average amount of total COD removal rate and TN removal rate, per unit area of cathode, were 1.72 ± 0.06 and 0.021 ± 0.007 g/m(2) d in SMFC-A, 1.03 ± 0.08 and 0.024 ± 0.005 g/m(2) d in SMFC-B, and 1.14 ± 0.01 and 0.017 ± 0.001 g/m(2) d in SMFC-C, respectively. SMFC-A, operated with higher distance between electrodes, demonstrated better removal of organic matter and highest open circuit voltage of 0.903 V. SMFCs with less feed pH (6.5) gave higher COD removal and feed pH of 8.5 gave higher TN removal. SMFCs operated with lesser distance between electrodes gave higher power density.

Characterization and emulsifying properties of different sunflower phosphatidylcholine enriched fractions

AbstractFractions enriched in specific phospholipids are desirable for different industrial purposes because of their characteristic physicochemical and functional properties. We studied the fractionation process of sunflower lecithin using different absolute‐ethanol/water ratios and pHs and then evaluated the emulsifying properties of phosphatidyl‐choline‐(PC‐) enriched fractions in oil/water 30:70 v/v emulsions. We observed a high recovery of PC and a low content of phosphatidyl inositol (PI) in all the PC‐enriched fractions thus obtained along with the highest yields of this phospholipid after extraction with an absolute‐ethanol/water mixture of 96:4 v/v. The use of different pH values for the different solvent extraction media did not markedly modify the yield of the enriched fractions. The extraction coefficients for PC and phosphatidyl ethanolamine (PE) evidenced an increase in both these phospholipids in the PC‐enriched fractions upon extraction with the higher concentration of absolute ethanol. Emulsions containing the PC‐enriched fractions obtained with the absolute‐ethanol/water mixture of 96:4 v/v exhibited the highest stability at pH 7.5 because of the high PC/PE ratio compared to that of the PC‐enriched fractions extracted with the absolute‐ethanol/water mixture of 90:10 v/v. A high emulsifier concentration resulted in a low mean D [4,3] diameter of the particles and a high stability.Practical applications: Sunflower lecithin is a promising alternative to soybean lecithin because it is considered the product of a non‐genetically modified organism (non‐GMO). Experimentation on lecithin modification under industrial conditions with adequate techniques of analysis may be useful for evaluating the potential applications of these sunflower by‐products to the production of new emulsifiers. Thus, an analysis of the influence of different fractionation parameters, such as the pH of the solvent extraction, on the composition and emulsifying properties of the resulting PC‐enriched fractions may provide useful information for the food industry.

Synthesis of kappa-carrageenan-g-poly(acrylamide)/sepiolite nanocomposite hydrogels and adsorption of cationic dye

In this study, nanocomposite hydrogels from grafting of acrylamide onto kappa-carrageenan biopolymer were prepared in the presence of sepiolite clay. Methylenebisacrylamide and ammonium persulfate were used as cross-linker and initiator, respectively. The sepiolite nanoclay was introduced into hydrogel matrix without any chemical treatment. The structure of nanocomposites was investigated by FTIR, SEM, TEM, and TGA techniques. The TEM image showed that sepiolite exists as individual needle’s shape. The swelling of hydrogels were studied in distilled water, salt solutions, and various pHs. The obtained nanocomposites were evaluated to remove of cationic crystal violet (CV) dye from water. The kinetic and isotherm of adsorption of dye onto nanocomposites were studied and analyzed according to kinetic and isotherm models. The results showed that the pseudo-second-order adsorption kinetic was predominated for the adsorption of CV onto nanocomposites. The experimental equilibrated adsorption capacity of nanocomposites was analyzed using Freundlich and Langmuir isotherm models. The results corroborated that the experimental data fit the Langmuir isotherm the best. By varying the pH of initial dye solution, while the clay-free hydrogel showed relatively pH-independent adsorption behavior, the nanocomposites depicted pH-dependent adsorption.

Study of fluorescence quenching of Barley α-amylase

The fluorescence quenching of Barley α-amylase by acrylamide and succinimide has been studied in water using steady-state and time-resolved fluorescence techniques. The steady-state fluorescence quenching technique has been performed in three different pHs (i.e., 6, 7 and 8) of water. Ground state and excited state binding constants (Kg &Ke) have been calculated. From the calculated binding constants (Kg &Ke) the free energy changes for the ground (ΔGg) and excited (ΔGe) states have been calculated and are presented in tables. UV and FTIR spectra have also been recorded to prove the binding of Barley α-amylase with acrylamide and succinimide.

Hydrolysis of the soluble fluorescent molecule carboxyumbelliferyl-beta- d-glucuronide by E. coli beta-glucuronidase as applied in a rugged, in situ optical sensor

Techniques utilizing β-glucuronidase (GUS) activity as an indicator of Escherichia coli ( E. coli) presence use labeled glucuronides to produce optical signals. Carboxyumbelliferyl-β- d-glucuronide (CUGlcU) is a fluorescent labeled glucuronide that is soluble and highly fluorescent at natural water pHs and temperatures and, therefore, may be an ideal reagent for use in an in situ optical sensor. This paper reports for the first time the Michaelis–Menten kinetic parameters for the binding of E. coli GUS with CUGlcU as K m = 910 μM, V max = 41.0 μM min −1, V max/ K m 45.0 μmol L −1 min −1, the optimal pH as 6.5 ± 1.0, optimal temperature as 38 °C, and the Gibb's free energy of activation as 61.40 kJ mol −1. Additionally, it was found CUGlcU hydrolysis is not significantly affected by heavy solvents suggesting proton transfer and solvent addition that occur during hydrolysis are not limiting steps. Comparison studies were made with the more common fluorescent molecule methylumbelliferyl-β- d-glucuronide (MUGlcU). Experiments showed GUS preferentially binds to MUGlcU in comparison to CUGlcU. CUGlcU was also demonstrated in a prototype optical sensor for the detection of E. coli. Initial bench testing of the sensor produced detection of low concentrations of E. coli (1.00 × 10 3 CFU/100 mL) in 230 ± 15.1 min and high concentrations (1.05 × 10 5 CFU/100 mL) in 8.00 ± 1.01 min.

Status of aluminium in environmental compartments contaminated by acidic mine water

Investigations were conducted to characterize aluminium in the affected stream and soils downstream of a mine site discharging acidic mine water. The water-borne Al exhibited a highly non-conservative behaviour at water pH below 3.8 in the 0–3.9 km reach and a much more conservative behaviour in the reaches with higher water pHs downstream of the 3.9 km station. The concentration of water-borne Al was higher at the medium flow event than at the flood event in the 0–9 km reach while the opposite was observed for the 16–56 km reach. Transport of Al associated with suspended materials was only observed during the flood event. The amount of Al carried by per unit weight of suspended particles was smaller in the 0–16 km reach than in the 25–56 km reach. The sediment-borne Al increased downstream with maximum Al accumulation occurred in the 25–29 km reach. The residual Al dominated Al fractions in the streambed sediments. The NH 4Cl-extractable Al in the affected soils decreased with increasing distance from the acidic irrigation water source. In contrast, both the water-extractable and total Al in the soils showed no clear distribution pattern. The NH 4Cl-extractable Al was closely correlated with soil acidity while neither total Al nor water-extractable Al was correlated with soil acidity. The vertical distribution of NH 4Cl-extractable Al was regulated by pH with certain influence from soil clay abundance.

Development and physicochemical evaluation of chondroitin sulfate-poly(ethylene oxide) hydrogel

Novel chondroitin sulfate (CS) — poly(ethylene oxide) (PEO) hydrogel was synthesized and evaluated by a mechanism of self cross-linking of CS derivative with PEO with hexa-thiols (PEO-SH). A derivative of CS was synthesized by the sequential grafting of adipic acid dihydrazide (ADH) and acrylic acid: chemical grafting of ADH to the carboxylic acid in CS (CS-ADH) followed by grafting of the acrylic acid to the free amine groups in the CSADH (CS-ADH-Ac). The synthesis of CS-ADH-Ac molecules was confirmed by observing new acrylate peaks in CS-ADH-Ac by FTIR, ESCA, and NMR. The CS-PEO hydrogel was self cross-linked through a Michael type addition reaction between the acrylate end groups of CS-ADH-Ac and the thiol end groups of the PEO-SH. the gelation behavior of 10% CS-PEO was evaluated by rheological analyses from the changes in the solution properties, such as phase angles and visco-elasticities. Rheological analysis indicated that the gelation process was complete within 2 min after mixing two polymer solutions of CS-ADH-Ac and PEO-SH. The fabricated CS-PEO hydrogel was analyzed by measuring both its swelling under different water pHs and its mechanical strength against compression. The morphological shapes of both its surface and cross sections were also evaluated after the sequential processes of gel swelling to equilibrium followed by dehydration. Both the gelation time and swelling of the fabricated hydrogel were dependent on the pH of the polymer solutions and swelling medium, showing quicker gel formation and better swelling behaviors under basic conditions than under acidic conditions. The equilibrated gel showed different morphologies depending on its location, i.e. its cross sections demonstrated more homogeneous morphologies than the surfaces. While the dehydrated hydrogel demonstrated 8–10 μm pore sizes on its cross sections, the compression strength of the hydrogel ranged from 1.4 to 2.8 Pa depending on its gel concentration. Toluidine blue molecules as a model drug were released from the hydrogel over a period of more than 5 days. These hydrogel properties, such as formation of in situ gel, release behaviors of toluidine blue, and porous structures and mechanical properties of the fabricated gel, highlighted the potential of a hydrogel as a carrier for local drug delivery and a scaffold for tissue engineering.

Facile synthesis of nano-sized metal-organic frameworks, chromium-benzenedicarboxylate, MIL-101

A chromium-benzenedicarboxylate (Cr-BDC) named MIL-101 with huge porosity, one of the most widely studied metal-organic framework (MOF) materials, has been synthesized in wide range of reaction conditions like various water concentrations, pHs and synthesis methods (electric heating and microwave irradiation) to get nano-sized crystals. The crystal size decreases with increasing water concentration and pH. The decrease of size in diluted reactants may be explained with a smaller rate of crystal growth than nucleation rate. The decreased size of MIL-101 in diluted condition is different to the synthesis of zeolites, probably because MOFs are obtained by a simple process of complexation. Moreover, high pH may be beneficial to produce not only benzenedicarboxylate but also chromium trimers, which are needed for the nucleation of MIL-101 structure. In a selected condition, the MIL-101 having the size of about 50nm can be obtained facilely and reproducibly with relatively high yield, which may lead to enlarging the applications of the valuable MOF material.

Aquatic toxicity of sertraline to Pimephales promelas at environmentally relevant surface water pH

Researchers recognize that ionization state may influence the biological activity of weak acids and bases. Dissociation in aqueous solutions is controlled by the pKa of a compound and the pH of the matrix. Because many pharmaceuticals are implicitly designed as ionizable compounds, site-specific variability in pH of receiving waters may introduce uncertainty to ecological risk assessments. The present study employed 48-h and 7-d toxicity tests with Pimephales promelas exposed to the model weak base pharmaceutical sertraline over a gradient of environmentally relevant surface water pHs. The 48-h experiments were completed in triplicate, and the average lethal concentration values were 647, 205, and 72 microL sertraline at pH 6.5, 7.5, and 8.5, respectively. Survivorship, growth, and feeding rate (a nontraditional endpoint linked by other researchers to sertraline's specific mode of action) were monitored during the 7-d experiment. Adverse effects were more pronounced when individuals were exposed to sertraline at pH 8.5 compared to pH 7.5 and 6.5. The pH-dependent toxicological relationships from these studies were related to in-stream pH data for two streams in the Brazos River basin of central Texas, USA. This predictive approach was taken because of the scarcity of environmental analytical data for sertraline. The results of this study emphasized temporal variability associated with in-stream pH linked to seasonal differences within and between these spatially related systems. Relating site-specific pH variability of surface waters to ionization state may allow researchers to reduce uncertainty during ecological risk assessment of pharmaceuticals by improving estimates of biological effects associated with exposure.

Risk Factors for Contamination of Hotel Water Distribution Systems by Legionella Species

The Legionella colonization frequency at 385 Greek hotel hot and cold water distribution systems was 20.8%. Legionella contamination was associated with the presence of an oil heater (odds ratio [OR]=2.04, 95% confidence interval [CI]=1.12 to 3.70), with the sample temperature (OR=0.26, 95% CI=0.1 to 0.5), with seasonal operation (OR=3.23, 95% CI=1.52 to 6.87), and with the presence of an independent disinfection system (OR=0.30, 95% CI=0.15 to 0.62). The same water temperatures, free-chlorine levels, and pHs differently affect the survival of various Legionella spp.