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Elucidating the role of pyrogenic carbon (C pyr) as a global pool for CO 2 sequestration in temperate ecosystems requires information on the contribution of C pyr to soil organic carbon (SOC) across different climatic regions. We investigated the effect of climate and basic soil properties on the accumulation of C pyr in surface soils across the native North American prairies. Topsoil samples (0-10 cm) of 18 native grassland sites along temperature and precipitation transects from central Saskatoon, Canada, to south Texas, USA, were analyzed for benzenecarboxylic acids as molecular markers for C pyr after nitric acid oxidation in the bulk soil (<2 mm), clay-(<2 mm) and silt-sized (2-20 mm) separates. C pyr contributed between 4 and 18% to SOC, the major proportions of C pyr being mostly found in the clay and silt fractions. C pyr in soil did not correlate with basic inorganic soil properties such as pH or clay content, but it increased significantly as SOC contents increased (r 2 = 0.78; P < 0.001). Obviously, C pyr co-accumulated with dead biomass. Since this accumulation depends on climate, also C pyr contents in soil depend on climate and may be predicted by the logarithm of the ratio of mean annual temperature (MAT) to mean annual precipitation (MAP) (P < 0.05). We conclude that the natural potential of soils to sequester C pyr reflects both, (1) higher C pyr production at sites with high plant biomass in moist climates, and (2) lower C pyr residence time at soils acting as a CO 2 source in warm climates.

Copper, as a heavy metal, is toxic for many biological systems. Thus, the determination of trace amounts of copper in environmental samples is of great importance. In the present work, a new method was developed for the determination of trace amounts of copper in water samples. The method is based on the formation of ternary Cu(II)-CAS-CTAB ion-pair and adsorption of it into a mini-column packed with cotton prior applying inductively coupled plasma optical emission spectrometry (ICP-OES). The experimental parameters that affected the extraction efficiency of the method such as pH, flow rate and volume of the sample solution, concentration of chromazurol S (CAS) and cethyltrimethylammonium bromide (CTAB) as well as type and concentration of eluent were investigated and optimized. The ion-pair (Cu(II)-CAS-CTAB) was quantitatively retained on the cotton under the optimum conditions, then eluted completely using a solution of 25% (v/v) 1-propanol in 0.5 mol L −1 HNO 3 and directly introduced into the nebulizer of the ICP-OES. The detection limit (DL) of the method for copper was 40 ng L −1 (V sample = 100 mL) and the relative standard deviation (R.S.D.) for the determination of copper at 10 g L −1 level was found to be 1.3%. The method was successfully applied to determine the trace amounts of copper in tap water, deep well water, seawater and two different mineral waters, and suitable recoveries were obtained (92-106%).

In this study, the behaviour of Lactobacillus fermentum CRL 722 and CRL 251 were evaluated under different pH conditions (pH 6.0, 5.5, 5.0, 4.5) and without pH control. Growth was similar under all conditions assayed except at pH 4.5. These microorganisms were able to eliminate raffinose, a nondigestible α-oligosaccharide (NDO) found in soy products, showing a consumption rate of 0.25 g l −1 h −1 (pH 6.0-5.0). The removal of raffinose was due to the high α-galactosidase (α-gal) activities of these lactic acid bacteria, which was highest at pH 5.5 (5.0 U/ml). The yield of organic acids produced during raffinose consumption was also highest at this pH. The results of this study will allow selection of the optimum growth conditions of L. fermentum with elevated levels of α-gal to be used in the reduction of NDO in soy products when used as starter cultures.

Green fluorescent protein (GFP) is an excellent biosensor as a result of its ability to be easily monitored in a wide variety of applications. Enzymes and proteins have been used as biological indicators to evaluate the immediate efficacy of industrial procedures, such as blanching, pasteurization, and disinfection treatments, as well as to monitor the satisfactory preservation of a product subjected to disinfection or sterilization. The purpose of this work was to study GFP stability in chlorinated water for injection (WFI) and chlorinated buffered solutions at various pH ranges, with and without agitation, to evaluate the exposure time required for chlorine to decrease 90% of its fluorescence intensity (decimal reduction time, D-value, min, 25°C). Fluorescence intensity (Ex/Em max) 394/509 nm) was measured immediately after the addition of GFP (8.0-9.0 µg/mL) into buffered or unbuffered chlorine solutions with or without constant stirring. With solutions constantly stirred, GFP fluorescence decreased abruptly on contact with chlorine in concentrations greater than 150 ppm, with D-values between 1.3 min (147 ppm chlorine) and 1.7 min (183 ppm chlorine). In phosphate buffered chlorine solutions (pH) 7.15 (0.08), GFP retained its structure between 52 and 94 ppm, but protein stability decreased 10-fold when exposed to 110 ppm chlorine. The recovery of GFP fluorescence intensity due to renaturation was observed between 30 and 100 ppm chlorine in WFI (final pH) 11.01 (0.23) without stirring. Stirring enhanced the contact between GFP and chlorine throughout the assay and provided a more accurate D-value evaluation. GFP performed as a suitable fluorescent marker for monitoring disinfection effectiveness.

1] The global oceans serve as the largest sustained natural sink for increasing atmospheric carbon dioxide (CO 2 ) concentrations. As this CO 2 is absorbed by seawater, it not only reacts causing a reduction in seawater pH (or acidification) but also decreases the carbonate mineral saturation state (W), which plays an important role in calcification for many marine organisms. Ocean acidification could affect some of the most fundamental biological and geochemical processes of the sea in coming decades. Observations obtained in situ from Volunteer Observing Ships and multiple geochemical surveys have been extended using satellite remote sensing and modeled environmental parameters to derive estimates of sea-surface alkalinity (A T ) and carbon dioxide partial pressure (pCO 2,sw ). Pairing estimates of A T and pCO 2,sw have permitted characterization of the changes in sea-surface W, which have transpired over the past decade throughout the Greater Caribbean Region as a consequence of ocean acidification. The results reveal considerable spatial and temporal variability throughout the region. Despite this variability, we observed a strong secular decrease in aragonite saturation state (W arg ) at a rate of approximately À0.012 ± 0.001 W arg yr À1 (r 2 = 0.97, P < 0.001).

The investigation of adsorption of nitrate onto chitosan beads modified by cross-linking with epichlorohydrin (ECH) and surface conditioning with sodium bisulfate was performed. The results indicated that both cross-linking and conditioning increased adsorption capacity compared to normal chitosan beads. The maximum adsorption capacity was found at a cross-linking ratio of 0.4 and conditioning concentration of 0.1 mM NaHSO 4 . The maximum adsorption capacity was 104.0 mg g −1 for the conditioned cross-linked chitosan beads at pH 5, while it was 90.7 mg g −1 for normal chitosan beads. The Langmuir isotherm model fit the equilibrium data better than the Freundlich model. The mean adsorption energies obtained from the Dubinin-Radushkevich isotherm model for all adsorption systems were in the range of 9.55-9.71 kJ mol −1 , indicating that physical electrostatic force was potentially involved in the adsorption process.

Clean water is a basic human need that is used for daily activities. However, as the population increases, the need for water also increases. One method of conserving water resources is Rainwater Storage. Conventional rainwater storage cannot be appropriately monitored, maintain water quality, and only works like a container, which, if left to continue, can result in the collected rainwater becoming a source of disease and dangerous for users. This research aims to create an automatic rainwater collection system and water quality monitoring that can control the flow of water that will enter the reservoir to keep the water entering the reservoir of good quality. In the manufacture of this system, three sensors are used, including a pH sensor, a water turbidity sensor, and a TDS (Total Dissolved Solids) sensor. In determining water quality, the k-Nearest Neighbor (k-NN) method is used to classify whether the water is feasible, less feasible, or not suitable for consumption. Data trans...

The capability of 14 zeolites synthesized from different fly ashes (ZFAs) to sequestrate Cr(III) from aqueous solutions was investigated in a batch mode. The influence of pH on the sorption of Cr(III) was examined. ZFAs had a much greater ability than fly ash to remove Cr(III), due to the high cation exchange capacity (CEC) and the high acid neutralizing capacity (ANC) of ZFAs. The mechanism of Cr(III) removal by ZFAs involved ion exchange and precipitation. A high-calcium content in both the fly ashes and ZFAs resulted in a high ANC value and, as a result, a high immobilization capacity for Cr(III). The pH strongly influenced Cr(III) removal by ZFAs. Inside the solubility range, removal of chromium increased with increasing pH. Hydroxysodalite made from a high-calcium fly ash had a higher sorptive capacity for Cr(III) than the NaP1 zeolite from medium-and low-calcium fly ashes. On the other hand, at pH values above the solubility range, the efficiency of chromium removal by the ZFAs approached 100% due to the precipitation of Cr(OH) 3 on the sorbent surfaces. It is concluded that ZFAs and high-calcium fly ashes may be promising materials for the purification of Cr(III) from water/wastewater.

The rheological and morphological properties and in vitro theophylline release of tertiary aminebased microgels were evaluated. The testing of such a formulation through in vitro diffusion experiments revealed that the release of theophylline from the microgels was pH-dependent and differs significantly with respect to a nonresponsive gel like scleroglucan (Scl). The microgels were obtained from 2-(diethyl amino) ethylmethacrylate (DEA) in the presence of a bifunctional crosslinker at pH 8-9. As the resulting microgels are pH-responsive and an increase in viscosity from high to low pH range is exhibited, the in vitro release of theophylline as model drug was studied at different pHs of both the matrix and the receptor medium. The release behaviors of PDEA-based microgels were compared to nonresponsive natural gel Scl, studied previously. For microgels, diverse release patterns were found at different acidity conditions. This observation seems to be related to complex diffusion phenomena and the different gel structure obtained for samples prepared at dissimilar pH.

The electrosynthesis, overoxidation and characterization of l-aspartic acid (l-Asp) imprinted polypyrrole (PPy) films have been performed by using electrochemical quartz crystal microbalance (EQCM). Following the determination of the optimal electrosynthesis parameters for the formation of a smooth and uniform PPy/l-Asp films, the overoxidized polypyrrole (oPPy) matrix templated with either l-or d-aspartic acid (l-, d-Asp) was evaluated as a potential enantioselective recognition element. Under potentiodynamic conditions and in strongly acidic media a significantly higher sensitivity of the l-Asp acid imprinted overoxidized polypyrrole film (oPPy/l-Asp) for l-Asp than d-Asp was observed. The results suggest the feasibility of preparing molecularly imprinted films by electropolymerization for the enantioselective recognition of amino acids and the suitability of EQCM for both monitoring the selective recognition as well as to electrochemically modulate the binding process.

Stevia as a natural sweetener with zero calories, and proven non-toxic effects on human health, recently found widespread use in the food and baking industry. Steviol glycosides that are concentrated in the plant leaves are: even 300 times sweeter than sucrose, heat-stable and well tolerate low pH-values. Th ese are all characteristics that popularize this plant in its application as a natural sweetener in consummation and everyday use. This review provides an insight into: the possibilities of applying stevia as a sweetener for commercial purposes; biochemical and nutritional content of the stevia leaves; the basic techniques of its cultivation, and use of stevia leaves as a basic raw material for the various stevia products.

Different pH control agents (NaOH/H 2 SO 4 -SodSulp, NaOH/CH 3 COOH-SodAcet, NH 4 OH/CH 3 CO-OH-AmmoAcet and NH 4 OH/H 2 SO 4 -AmmoSulp) were used to investigate their effects on growth, enzyme production (alkaline protease and amylase), and entomotoxicity of Bacillus thuringiensis var. kurstaki HD-1 (Btk) against eastern spruce budworm larvae (Choristoneura fumiferana) using starch industry wastewater (SIW) as a raw material in a 15-l fermentor. AmmoSulp and SodSulp were found to be the best pH control agents for alkaline protease and amylase production, respectively; whereas, the fermented broth obtained by using SodAcet as pH control agents recorded the highest delta-endotoxin production of 1043.0 mg/l and entomotoxicity value 18.4 9 10 9 SBU/l. Entomotoxicity of re-suspended centrifuged pellet in onetenth of original volume in case of SodAcet as pH control agents was 26.7 9 10 9 SBU/l and was the highest value compared to three other pH control agents.

In this work, a brewer’s yeast strain was used to remove heavy metals from a synthetic effluent. The solid–liquid separation process was carried out using the flocculation ability of the strain. The yeast strain was able to sediment in the presence of Cu2+, Ni2+, Zn2+, Cd2+ and Cr3+, which evidences that the flocculation can be used as a cheap and natural separation process for an enlarged range of industrial effluents. For a biomass concentration higher than 0.5 g/l, more than 95% of the cells were settled after 5 min; this fact shows that the auto-aggregation of yeast biomass is a rapid and efficient separation process. Cells inactivated at 45 °C maintain the sedimentation characteristics, while cells inactivated at 80 °C lose partially (40%) the flocculation.The passage of metal-loaded effluent through a series of sequential batches allowed, after the second batch, the reduction of the Ni2+concentration in solution for values below the legal limit of discharge of wastewater in natural waters (2 mg/l); this procedure corresponds to a removal of 91%. A subsequent batch had a marginal effect on Ni2+ removal (96%).Together, the results obtained suggest that the use of brewing flocculent biomass looks a promising alternative in the bioremediation of metal-loaded industrial effluents since the removal of the heavy metals and cell separation are simultaneously achieved.

Nickel ion-imprinted membrane was synthesized using PVDF microfiltration membrane as support. In the current study, thermodynamic and kinetic of Ni(II) and Co(II) ions adsorption onto the membrane was investigated. Classical adsorption isotherms including Langmuir, Freundlich, Redlich-Peterson and Langmuir-Freundlich (Sips) were employed to describe the adsorption equilibria. The Sips equilibrium model could superiorly represent the equilibrium adsorption of the ions. Calculation of principle thermodynamic parameters such as free energy, enthalpy and entropy change revealed exothermic and spontaneous adsorption on the basis of the negative H • and G • values, respectively. Meanwhile, adsorption of Co(II) ions on the imprinted membrane was less favorable than that of Ni(II) ions. Moreover, negative values of S • demonstrated randomness reduction at the solid-liquid interface. Pseudo-firstorder, pseudo-second-order and intra-particle diffusion models were utilized to describe the adsorption kinetic. Ion diffusivity through the membrane was also examined versus time and initial concentration. The kinetic results indicated superior adsorption-permeation rate of Ni(II) compared with Co(II) ions. In addition, a novel mathematical model was developed for prediction of the ions adsorption-transport behavior. Well fitted to the experimental data, the model provided a new insight into the phenomena involved in ion adsorption on imprinted membranes.

A comprehensive study of the chemical composition of rainwater was carried out from June 1999 to September 2001 at Lucknow, India. The rainwater was found to be alkaline with a mean pH of 6.7 in winter season and 6.5 in monsoons. It was observed during the study that Ca was the most abundant ion and along with Mg and NH 4 it forms equilibrium reactions with acids. Analysis of Variation (ANOVA) indicates that concentration of major ions was higher during cold climatic conditions probably due to dry season in winter leading to low dilution phenomena. The data was subjected to factor analysis based on Principal Component Analysis using the SPSS software (Version 7.5). The rotated factor matrix was employed to group variables into four factors. The first factor included Ca, Mg, SO 4 , NO 3 and NH 4 attributed to soil derivatives and biogenic activities. Factor 2 loaded with Na, K, and Cl, may be linked to emissions from traditional combustion activities. Factor 3 and 4 include Cu, Zn, Fe and Ni, which may be attributed to industrial activities and scavenging process cycles. D

A three variables-five levels central composite design was used to study the effects of pH (3.5, 4.0, 4.5, 5.0 and 5.5), cinnamaldehyde (0, 40, 80, 120 and 160 ppm) and heating temperature (80, 84, 88, 92 and 96°C) on the spores of Alicyclobacillus acidoterrestris in malt extract broth (MEB). The heat shock resulted in a slight decrease of spore number from 3.2 to 2.5 log CFU mL )1 and occurred at 80-85°C depending on the pH of the medium. Otherwise, cinnamaldehyde acted as an additional hurdle within the storage time; the critical amounts to be used were included in the range 41.35-44.42 ppm of cinnamaldehyde and were related positively to the pH, i.e. the critical amount of active compound decreased with the decreasing of the pH.

The retention properties of a SBA-15 mesoporous silica functionalized with -(CH 2 ) 3 COOH groups, synthesized by a co-condensation route, were investigated for the ion chromatography of different cationic species. A systematic study on the effect of different eluent compositions containing non-complexing (methanesulfonic acid) or complexing (oxalic or pyridine-2,6-dicarboxylic acids) eluents, in the presence of organic modifiers (CH 3 CN, CH 3 OH, CH 3 NH 2 ) on the retention of cations (Li + , Na + , K + , Ca 2+ , Mg 2+ , Sr 2+ , Ba 2+ , NH 4 + , Cu 2+ , Ni 2+ , Zn 2+ , Cd 2+ , Co 2+ , Pb 2+ , Fe 3+ ) chosen as model analytes and for their environmental importance, allowed us to elucidate the mechanisms (cation-exchange or complexation) involved in the retention on the SBA-15 phase. For the first time separations of cations on SBA-15 based stationary phases are investigated, providing the basis for further development of mesoporous silica chemistry for in-flow ion-exchange applications.

The application of a DC electric field down gradient to the contaminated zone in the subsurface can create an electrokinetic barrier. The electrical potential gradient causes the movement of ions which in turn imposes a viscous drag on the pore water. In clayey soils, this viscous drag can generate a high enough pore water pressure capable of counteracting the ground water gradient. This phenomenon can be used effectively as a barrier to prevent contaminant migration. A finite element model was developed to simulate the contaminant migration in soil under coupled hydraulic, electrical and chemical gradients. The model is also capable of predicting the associated changes in the soil like the pore water pressure, pH and voltage gradient as a function of time and distance from the electrode. This model was validated using the w experimental data presented by Yeung Yeung, A.T., 1990. Electro-kinetic barrier to contaminant x transport through compacted clay. PhD Thesis, University of California, Berkeley, 260 pp. . The results indicate very good agreement between the experimental and simulated results. The model predications show that when the anode is placed down gradient of the cathode, the cation migration could be completely arrested. However, the anions were found to move faster in the direction of the ground water flow and reduce the effectiveness of the barrier. This could be avoided by carefully designing the placement of the electrodes. If the contaminant of interest is either a cation or an anion, a simple double row of anode and cathode electrode arrangement could serve as an effective barrier. On the other hand, if the contaminant includes both anions and cations, then a triple-row configuration of electrodes need to be implemented. The model ) Corresponding author. 0169-7722r00r$ -see front matter q 2000 Elsevier Science B.V. All rights reserved.

Cancer surgery prognosis currently relies heavily on expensive diagnostics devices that have limited availability to patients. Minute-to-minute cancer recurrence monitoring device is needed. This paper investigates a novel design and simulation of Implantable micro-scale, minute-to-minute sensors of low manufacture cost. In Cadence simulation software, electrochemical sensor array circuit in 0.35 micron complementary metal oxide semiconductor (CMOS) process was designed. The simulated circuit supported both pH ISFET sensor and soluble oxygen level O2-FET sensor. The simulation result showed that the circuit's output voltage has optimal sensitivity when ISFET V gate was biased at range of 2.29-2.49 volts. The output voltage in this biasing scheme varies linearly with the input voltage V gate making it ideal region for monitoring of cancer. The appropriate biasing of ISFET V gate voltage found by simulation is within 2.29-2.49 volts. In the case of pH measurements, the sensitivity can be up to 0.02 pH in a minute-to-minute pH probing device for cancer prognosis tracking. Other chemical probes such as O2-FET and Oct4 sensors are also supported by the device architecture.

Determination of chromium in groundwater samples containing iron may pose analytical problems due to sorption and fixation of chromium species onto Fe(III) hydroxides. Parks et al. (Water Res. 2004, 38, 2827) hypothesized that chromium species trapped inside Fe(III) hydroxides i.e. "fixed chromium" may not be soluble by HNO 3 digestion (APHA method 3030 B). In such cases, hydroxylamine digestion is required to release "fixed chromium". To verify the hypothesis, we carried out this study on groundwater samples containing chromium and iron, using different methods of APHA and EPA. The results showed the presence of "fixed chromium", ranged between 0.1 and 19.2 μg L − 1 , contributing 0.2 to 14.1% towards true total chromium. Digestion of samples with HNO 3 released Cr(III) bound to organic complexes, but not the "fixed chromium". The hydroxylamine digestion released "fixed chromium", but not the Cr(III) bound to organic complexes. Microwave digestion of samples with HNO 3 + HCl was effective for the release of both "fixed" and "Cr(III)-organic complexes". Cr(III) was only adsorbed onto suspended matter, whereas Cr(VI), and Cr (III)-organic complexes were not adsorbed onto suspended matter due to their solubility. Sample pH, buffering capacity, and matrix have a significant influence on the adsorption and fixation of chromium species onto Fe(III) hydroxides.

The International Cooperative Programme on Assessment and Monitoring of Acidification of Rivers and Lakes (ICP-Water) started in 1987. The main aim of the programme is to establish degree and geographical extent of acidification of surface waters and evaluate dose/response relationships to aquatic biota attributable to acidic deposition. The sample frequency in each locality is from a few-to a large number every year. Samples of invertebrates are taken from 108 localities. One time samples as well as regularly seasonal samples over years exist in the database. The acidity score (Raddum index) is determined for the different sites and regions, and compared with the corresponding chemical data. The analysis show a strong relationship between water quality and fauna. Sensitive species/taxa are associated with high ANC and pH, while tolerant species/taxa are associated with low pH and ANC. The diversity of the fauna in less acidified areas varies from region to region depending on the native water quality and the adaptions of the fauna. In areas with strongly oligotrophic water, low in ionic strength, the sensitive fauna tolerate lower ANC and pH than in areas with originally high ionic strength and high pH. The critical load of ANC, 20/~eq/l, developed for the oligotrophic water in Norway, should therefore be increased in watersheds with high ionic strength. In Central Europe the data indicate a critical level of ANC-50/zeq/1.

Processes governing the mobilization of A1 and Cd in podzols and cambisols of S. Sweden having different tree layer vegetation (Picea abies, Fagus sylvatica, or Betula pendula) were investigated. Speciation of A1 and Cd in soil solutions were performed by a column cation exchange procedure (cf. Driscoll, 1984) in combination with thermodynamic calculations. Podzols in spruce and beech stands were characterized by a high release of organic compounds from the O/Ah horizons, resulting in a high organic complexation of A1 (c. 93%) in the soil solution from the E horizon (15 cm lysimeters). Organic complexes were mainly adsorbed/precipitated in the upper Bh horizon and the overall transport of A1 at 50 cm depth was governed by a pH dependent dissolution of a solid-phase A1 pool. In the cambisols, inorganic A1 forms were predominant at both 15 and 50 cm depth, and A1 solubility was closely related to solution pH. Secondary minerals like synthetic gibbsite, jurbanite, kaolinite or imogolite could generally not explain measured solution AP + activities. Results instead indicated that the relatively large organically bound solid-phase A1 pools present in both soil types could do so. The column fractionation procedure could be used only qualitatively for Cd, but results strongly indicated that Cd-organo complexes contributed significantly to the overall mobilization of Cd in the podzol E horizons. In all other soil solutions, Cd 2+ was the predominant species. Both solid-phase and solution chemistry suggests that ion exchange processes controlled the Cd 2+ activities in these solutions. All reactive solidphase Cd was extractable by NH4C1 and Cd 2+ activities could in most cases effectively be modeled by the use of ion exchange equations. Solubilized AP + efficiently competed for exchange sites and played an important role for the Cd mobilization in these soils.

AbstractÐAlthough the presence of hepatotoxins in surface and drinking water is regarded as an ecotoxicological and human health problem, limited knowledge exists on the fate of these compounds. Therefore the n-octanol/water distribution ratio (D ow ) of the hepatotoxin microcystin-LR (MC-LR) was determined in order to enable the prediction of the fate of this compound in the aquatic environment. The presence of two free ionizable carboxyl groups and one free ionizable amino group in MC-LR suggest that its speciation and partitioning between octanol and water is pH dependent. This was experimentally studied and con®rmed in the present study. The log D ow of MC-LR decreased from 2.18 at pH = 1 to À1.76 at pH = 10. From the low log D ow values, especially at the basic pH region at which the toxin producing cyanobacteria¯ourish, a low tendency to bioconcentrate from water in biota can be expected. #

The estimation of chemical concentrations in wildlife foods, such as plant foliage, is often performed for risk assessments at contaminated sites. Regression models and uptake factors for use in estimating the uptake of inorganic elements from soil by above-ground plant tissues were derived in this study. These included models for arsenic, cadmium, copper, lead, mercury, nickel, selenium, and zinc. Models were developed using published data from soil contaminated in the field and were validated using measured concentrations from two contaminated sites. Single-variable regression models of log-transformed concentrations in plants versus log-transformed concentrations in soil are generally recommended over simple uptake factors for use in estimating plant uptake of inorganic contaminants in ecological risk assessments. Multiple regression models with soil concentration and pH as the variables are also recommended for estimating the uptake of four chemicals (cadmium, mercury, selenium, and zinc) by plants. Models for use in screening risk assessments, i.e., the upper 95% prediction limits on the regressions, are recommended to provide conservative estimates of uptake of inorganic chemicals by plants.

Palm oil mill effluent (POME) a b s t r a c t A hydrogen producer was successfully isolated from anaerobic digested palm oil mill effluent (POME) sludge. The strain, designated as Clostridium butyricum EB6, efficiently produced hydrogen concurrently with cell growth. A controlled study was done on a synthetic medium at an initial pH value of 6.0 with 10 g/L glucose with the maximum hydrogen production at 948 mL H 2 /L-medium and the volumetric hydrogen production rate at 172 mL H 2 /L-medium/h. The supplementation of yeast extract was shown to have a significant effect with a maximum hydrogen production of 992 mL H 2 /L-medium at 4 g/L of yeast extract added. The effect of pH on hydrogen production from POME was investigated. Experimental results showed that the optimum hydrogen production ability occurred at pH 5.5. The maximum hydrogen production and maximum volumetric hydrogen production rate were at 3195 mL H 2 /L-medium and 1034 mL H 2 /L-medium/h, respectively. The hydrogen content in the biogas produced was in the range of 60-70%. ª

This paper presents a micromagnetoelastic sensor array for simultaneously monitoring multiple biological agents. Magnetoelastic sensors, made of low-cost amorphous ferromagnetic ribbons, are analogous and complementary to piezoelectric acoustic wave sensors, which track parameters of interest via changes in resonance behavior. Magnetoelastic sensors are excited with magnetic ac fields, and, in turn, they generate magnetic fluxes that can be detected with a sensing coil from a distance. As a result, these sensors are highly attractive, not only due to their small size and low cost, but also because of their passive and wireless nature. Magnetoelastic sensors have been applied for monitoring pressure, temperature, liquid density, and viscosity, fluid flow velocity and direction, and with chemical/biological responsive coatings that change mass or elasticity, various biological and chemical agents. In this paper, we report the fabrication and application of a six-sensor array for simultaneous measurement of Escherichia coli O157:H7, staphylococcal enterotoxin B, and ricin. In addition, the sensor array also monitors temperature and pH so the measurements are independent from these two parameters.

Metabolic acidosis is associated with various clinical situations including diabetes mellitus and renal diseases. The aim of this study was to investigate the effects of acidosis on the resting as well as precontracted human left internal mammary artery. The vessels were obtained from the patients undergoing coronary artery bypass grafting surgery at The Aga Khan University Hospital, Karachi. Left internal mammary artery was cut into rings and isometric tension recording experiments were performed. Decrease in pH of the bathing solution from 7.4 to 6.8 had no effect on the resting tension of left internal mammary artery, whereas, acidic pH markedly relaxed the contractions to 24.8 mM KCl and 300 nM phenylephrine. Interestingly, when the KCl-or phenylephrine-contracted rings were treated with 3 AM glibenclamide; an inhibitor of ATP-sensitive potassium (K ATP ) channels, the relaxant effect of acidosis was abolished. Similarly, acidosis failed to cause relaxation of 100 nM endothelin-1-induced contraction in Ca 2+ -free bathing solution or in the presence of a voltage-dependent Ca 2+ channel inhibitor, verapamil (10 AM), whereas, endothelin-1-induced contraction was attenuated by acidosis in Ca 2+ -containing normal solution. From all these data, it is concluded that under the acidic pH conditions, opening of K ATP channels occurs; resulting in the hyperpolarization, decrease in Ca 2+ influx via voltage-dependent Ca 2+ channels and subsequent relaxation of human left internal mammary artery. D

The effect of shear on dewatering behaviour and particle interactions of Na-exchanged smectite and kaolinite clay dispersions has been investigated at pH 7.5, using hydrolysable Ca(II) and Mn(II) ions as coagulants and high molecular weight anionic and non-ionic polyacrylamide (PAM A and PAM N, respectively) and polyethylene oxide (PEO) flocculants. Metal ion addition enhanced the flocculation performance by dramatically reducing the magnitude of the particle zeta potential and, in the case of smectite pulp, suppressing osmotic swelling. Under optimum orthokinetic flocculation conditions of controlled agitation rate and duration, PAM A and PEO-based flocs settled faster than those of PAM N whilst kaolinite pulps produced higher sedimentation rates than smectite pulps. The settling rates are nearly an order of magnitude greater than those observed under standard flocculant -pulp mixing/flocculation methods of inversion and plunging. The difference in the flocculant behaviour is attributed to the more expanded conformation of PAM A and PEO polymer chains in contrast to PAM N, whilst the lower yield stresses, reflecting inter-particle bridging and floc network structure strength that are conducive to faster clarification, were displayed by kaolinite pulps. Following shear, similar consolidation enhancement of å 5 -7 wt.% solid for both pulps was achieved at an optimum agitation range of 100 -200 rpm. This was accompanied by decreased yield stress in the case of PAM A-based pulps, indicating non-reversible disruption of polymer mediated particle and floc network structure. In contrast, the yield stresses of PAM N and PEO flocculated dispersions indicated similar and stronger particle interactions, respectively, upon consolidation following shear. The findings show clear links between effect of shear, interfacial chemistry and polymer structure on pulp particle interactions and dewaterability. D

The complexation properties of humic substances, the stability of the dissolved humic-metal complex, and the interaction of complex with other soil constituents determine the solubility and mobility of heavy metals. This study investigated the influence of humic and fulvic acid on the release of zinc of soils from Fethiye (Mediterranean Region); Samsun (Black Sea Region); and Izmir (Aegean Region). The time-dependent release of zinc from the soil was evaluated using plots of logarithm of q t /q s versus time. The kinetics of zinc release by humic acid was characterised by two pseudo-first-order reactions. The observed rate coefficients in our model were k 1 =4.2×10 − 3 h − 1 and k 2 =5×10 − 5 h − 1 , which indicated to an initial fast reaction followed by a slower reaction. The release of zinc increased with increasing humic acid concentration representing an approach to plateau formation at the higher humic concentrations. The highest releases of 334.5, 350.8 and 369.4 μmol kg − 1 for Fethiye, Samsun and Izmir soils, respectively, were obtained for a humic acid concentration of 1000 mg L − 1. A different situation was observed in treatments with 150 mg L − 1 humic acid solutions, where the precipitative removal of humic acid-zinc complexes occurred at about pH 7. The interactive behaviour of humic acid-zinc complexes represented a similar reduction in the zinc concentrations in aqueous solution. A rise in the zinc load caused only a slight increase in release, which indicated that zinc load had little effect on release. Changes in soil suspension pH reflected higher zinc releases. An increase in the suspension pH to approximately 10.5 resulted in an increase from 209.4 μmol kg − 1 to 280.2 μmol kg − 1 (300 mg L − 1 humic acid), which was attributed to the involvement of other functional groups like phenolic groups in the process. On the other hand, decreasing the suspension pH to about 5 revealed to an increase from 89 μmol kg − 1 to 602.7 μmol kg − 1 (100 mg L − 1 humic acid), which was determined to be mainly the contribution of acidity. The influence of humic acid sorption on zinc release was investigated by evaluating sorption behaviour with respect to pH, salt, clay, oxide and organic matter contents of soils. Sorption of humic acid on soils presented a linear behaviour, and as the partition and distribution coefficients imply, was highest for Fethiye Soil, followed by Samsun and Izmir soils. Since this order reflected the reverse order of zinc release from soils, the degree of zinc release from soils was related to the degree of humic acid sorption. Thus, the greatest release of zinc from Izmir Soil was explained by the low humic acid sorption. The release of zinc from soil was lower for fulvic acid solutions, despite its higher acidic functional group content. For fulvic acid concentration of 300 mg L − 1 , a zinc release of 46.7, 85.7 and 148.5 μmol kg − 1 was obtained for Fethiye, Samsun and Izmir soils, respectively. This was linked to the strength of bonds involved in the process, as shown by the stability constants of zinc humic or fulvic acid complexes.

NiS-P zeolite was prepared by ion exchange and precipitation procedures and it was characterized by FT-IR, SEM and thermal methods. The prepared composite was used as a catalyst in the photodecolorization process of Eriochrome Black T (E.B.T.) dye in aqueous solution under UV irradiation. The effect of key operating parameters such as catalyst dosage, temperature, initial concentration of the dye and initial pH of the solutions were studied on the decolorization process of dye. The primary objective was to determine the optimal conditions for each of the parameters. UV-vis spectrophotometric measurements were performed for the determination of decolorization and mineralization extents. The optimal operation parameters were found as follows: pH 9.1, 0.8 g L −1 of catalyst loading and 40 ppm of dye concentration. The NiS particles out of zeolite framework did not show significant decolorization efficiency. The decolorization process obeyed first-order kinetics.

Gliclazide is practically insoluble in water. In order to improve the drug dissolution rate, cogrinding method was used as an approach to prepare gliclazide coground/solid dispersions (SDs) in the carriers such as povidone (PVP-K30), crospovidone and microcrystalline cellulose (Avicel PH 101) with different drug to carrier ratios. The dissolution rate of gliclazide from the SDs was measured at two physiological pH values of 1.2 and 7.2 simulating gastric and intestinal fluids using USP dissolution apparatus II. The concentration of the dissolved drug in the medium was determined by direct or first-derivative UV spectroscopy. The dissolution rates of the formulations were dependent on the nature and ratio of drug to carriers in SDs and the corresponding physical mixtures as well as the pH of the medium. At a higher pH the drug has a faster dissolution than at a lower pH. The fastest dissolution rates were observed from coground formulations with the drug to carrier ratio of 1:5. The amount of drug dissolved in 15 min from these SDs was varied from 96% in the case of Avicel SD to 100% for SD of PVP. Whereas the amount of drug released in the same time from unground drug powder (UD), ground drug powder (GD) and all physical mixtures was between 60 and 80%. These results indicate that the dissolution rate is highly enhanced from the SDs. DSC as well as X-ray diffraction showed reduced drug crystallinity in SDs. Scanning electron microscopy and particle size analysis revealed significant decreased particle size of the drug in SDs. FT-IR spectroscopy demonstrated no detectable interactions between the drug and carriers. In addition to latter evidence, increased wettability and hydrophilicity of drug particles and deaggregation brought about by the carriers are the reasons for enhanced drug dissolution from the SDs. One of the possible advantages of formulating an insoluble drug such as gliclazide is that if it is used in preparation of capsules or tablets of the drug, its dose might be reduced which is economically beneficial.

Cone Pond, New Hampshire, is an acidic (pH = 4.5) clearwater lake that is currently fishless. Historical records indicate declining fish populations between 1951 and 1966, but paleolimnological work using diatoms failed to find evidence for further recent acidification of this naturally acid site. We initiated new paleolimnological studies using mallomonadacean chrysophytes to further our understanding of Cone Pond&#39;s recent past. Our stratigraphic analyses indicate recent striking changes in the chrysophyte flora of this lake, with Mallomonas hindonii, a species only common in recently acidified lakes, replacing M. crassisquama, a cosmopolitan species that dominated the flora over the preceding 8000 yr; this recent change parallels the declines in fish populations. Because chrysophytes often bloom in early spring and are known, in other lakes, to experience changes in community composition before those expressed by the diatom community, a possibility is that chrysophytes track t...

Xylanase is an enzyme in high demand for various industrial applications, such as those in the biofuel and pulp and paper Welds. In this study, xylanase-producing microbes were isolated from the gut of the wood-feeding termite at 50°C. The isolated microbe produced thermostable xylanase that was active over a broad range of temperatures (40-90°C) and pH (3.5-9.5), with optimum activity (4,170 § 23.5 U mg ¡1 ) at 60°C and pH 4.5. The enzyme was puriWed using a strong cation exchanger and gel Wltration chromatography, revealing that the protein has a molecular mass of 205 kDa and calculated pI of 5.38. The half-life of xylanase was 6 h at 60°C and 2 h at 90°C. The isolated thermostable xylanase diVered from other xylanases reported to date in terms of size, structure, and mode of action. The novelty of this enzyme lies in its high speciWc activity and stability at broad ranges of temperature and pH. These properties suggest that this enzyme could be utilized in bioethanol production as well as in the paper and pulp industry.

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Mineral after in vitro digestion, using special gastric conditions prevailing in preterm and newborn infants. Mineral after in vitro digestion, using special gastric conditions prevailing in preterm and newborn infants. Mineral dialyzability was studied using pH 2.0, 3.5, and 4.5 for gastric digestion. The effect of gastric pH was more important dialyzability was studied using pH 2.0, 3.5, and 4.5 for gastric digestion. The effect of gastric pH was more important dialyzability was studied using pH 2.0, 3.5, and 4.5 for gastric digestion. The effect of gastric pH was more important dialyzability was studied using pH 2.0, 3.5, and 4.5 for gastric digestion. The effect of gastric pH was more important dialyzability was studied using pH 2.0, 3.5, and 4.5 for gastric digestion. The effect of gastric pH was more important on iron dialyzability (FeD) and zinc dialyzability (ZnD) than on calcium dialyzability (CaD). The effect on iron on iron dialyzability (FeD) and zinc dialyzability (ZnD) than on calcium dialyzability (CaD). The effect on iron on iron dialyzability (FeD) and zinc dialyzability (ZnD) than on calcium dialyzability (CaD). The effect on iron on iron dialyzability (FeD) and zinc dialyzability (ZnD) than on calcium dialyzability (CaD). The effect on iron on iron dialyzability (FeD) and zinc dialyzability (ZnD) than on calcium dialyzability (CaD). The effect on iron dialyzability was remarkable in fluid formulations with high digestibility: FeD was 18% to 20% when gastric diges-dialyzability was remarkable in fluid formulations with high digestibility: FeD was 18% to 20% when gastric diges-dialyzability was remarkable in fluid formulations with high digestibility: FeD was 18% to 20% when gastric diges-dialyzability was remarkable in fluid formulations with high digestibility: FeD was 18% to 20% when gastric digesdialyzability was remarkable in fluid formulations with high digestibility: FeD was 18% to 20% when gastric digestion was made at pH 2, decreasing to 3% when made at pH 4.5. In most powder infant formulas with the lowest tion was made at pH 2, decreasing to 3% when made at pH 4.5. In most powder infant formulas with the lowest tion was made at pH 2, decreasing to 3% when made at pH 4.5. In most powder infant formulas with the lowest tion was made at pH 2, decreasing to 3% when made at pH 4.5. In most powder infant formulas with the lowest tion was made at pH 2, decreasing to 3% when made at pH 4.5. In most powder infant formulas with the lowest digestibility digestibility digestibility digestibility digestibility, F , F , F , F , FeD r eD r eD r eD r eD remained close to 10% despite v emained close to 10% despite v emained close to 10% despite v emained close to 10% despite v emained close to 10% despite var ar ar ar ariations in gastr iations in gastr iations in gastr iations in gastr iations in gastric digestion pH. P ic digestion pH. P ic digestion pH. P ic digestion pH. P ic digestion pH. Per er er er ercent zinc dialyzability cent zinc dialyzability cent zinc dialyzability cent zinc dialyzability cent zinc dialyzability (ZnD%) steadily decreased when gastric digestion pH increased. At each pH, percent iron dialyzability (FeD%) and (ZnD%) steadily decreased when gastric digestion pH increased. At each pH, percent iron dialyzability (FeD%) and (ZnD%) steadily decreased when gastric digestion pH increased. At each pH, percent iron dialyzability (FeD%) and (ZnD%) steadily decreased when gastric digestion pH increased. At each pH, percent iron dialyzability (FeD%) and (ZnD%) steadily decreased when gastric digestion pH increased. At each pH, percent iron dialyzability (FeD%) and ZnD% from human milk were higher than those from infant formulas. Evaluation of mineral dialyzability from ZnD% from human milk were higher than those from infant formulas. Evaluation of mineral dialyzability from ZnD% from human milk were higher than those from infant formulas. Evaluation of mineral dialyzability from ZnD% from human milk were higher than those from infant formulas. Evaluation of mineral dialyzability from ZnD% from human milk were higher than those from infant formulas. 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The underlying mechanisms governing nonenzymatic pectin and pectate degradation during thermal treatment have not yet been fully elucidated. This study determined the extent of nonenzymatic degradation due to -elimination, acid hydrolysis, and demethylation during prolonged heating of citrus pectins and its influence on physicochemical properties. Solutions of citrus pectins, buffered from pH 4.0 to 8.5, were heated at 75, 85, 95, and 110°C for 0-300 min. Evolution of methanol and formation of reducing groups and unsaturated uronides were monitored during heating. Molecular weight and viscosity changes were determined through size exclusion chromatography and capillary viscometry, respectively. Results showed that at pH 4.5, the activation energies of acid hydrolysis, -elimination, and demethylation are 95, 136, and 98 kJ/mol, respectively. This means that at this pH, acid hydrolysis occurs more rapidly than -elimination. Furthermore, the rate of acid hydrolysis is diminished by higher levels of methyl esterification. Also, citrus pectin (93% esterified) degrades primarily via -elimination even under acidic conditions. Acid hydrolysis and -elimination caused significant reduction in relative viscosity and molecular weight.

Removal of Cr(VI) ions from aqueous solution was investigated using modified palm shell activated carbon. Low Molecular Weight Polyethyleneimine (LMW PEI) was used for impregnation purpose. The maximum amount of LMW PEI adsorbed on activated carbon was determined to be approximately 228.2 mg/ g carbon. The adsorption experiments were carried out in a batch system using potassium dichromate K 2 Cr 2 O 7 as the source of Cr(VI) in the synthetic waste water and modified palm shell activated carbon as the adsorbent. The effects of pH, concentration of Cr(VI) and PEI loaded on activated carbon were studied. The adsorption data were found to fit well with the Freundlich isotherm model. This modified Palm shell activated carbon showed high adsorption capacity for chromium ions.

Expression in transgenic plants is potentially one of the most economical systems for large-scale production of valuable peptide and protein products. However, the downstream processing of recombinant proteins produced in plants has not been extensively studied. In this work, we studied the extraction and purification of recombinant aprotinin, a protease inhibitor used as a therapeutic compound, produced in transgenic corn seed. Conditions for extraction from transgenic corn meal that maximize aprotinin concentration and its fraction of the total soluble protein in the extract were found: pH 3.0 and 200 mM NaCl. Aprotinin, together with a native corn trypsin inhibitor (CTI), was captured using a tryspin-agarose column. These two inhibitors were separated using an agarose-IDA-Cu 2+ column that proved to efficiently absorb the CTI while the recombinant aprotinin was collected in the flowthrough with purity of at least 79%. The high purity of the recombinant aprotinin was verified by SDS-PAGE and N-terminal sequencing. The overall recombinant aprotinin recovery yield and purification factor were 49% and 280, respectively. Because CTI was also purified, the recovery and purification process studied has the advantage of possible CTI co-production. Finally, the work presented here introduces additional information on the recovery and purification of recombinant proteins produced in plants and corroborates with past research on the potential use of plants as biorreactors.

pH is one of the key parameters that determines heavy metal mobility in soils, sediments and waste materials. In many respects leaching behaviour as reflected by the pH stat leaching tests provide a better means of assessing environmental impact than analysis of total elemental composition. This paper discusses the use of pH stat leaching tests as a tool to assess the potential mobilisation of trace metals from soils, sediments and waste materials. The possibilities of pH stat leaching tests are illustrated by means of different examples.

This study reports the preparation of starch-based tableted microspheres that are crosslinked with epichlorohydrin (EPI) using a modified water-in-oil (w/o) emulsification technique. Ampicillin (AMP), a broad spectrum antibiotic was encapsulated up to the extent of 70% into the microspheres. The microspheres were characterized by Fourier transform infrared spectroscopy (FT-IR) to confirm the crosslinking reaction and chemical stability of AMP. Differential scanning calorimetry (DSC) was studied on the placebo and drugloaded microspheres to confirm the polymorphism of AMP. Results of this study indicated a molecular level dispersion of AMP in the developed microspheres. Scanning electron microscopy (SEM) confirmed the spherical nature and smooth surfaces of the microspheres produced. Mean particle size of the microspheres as measured by laser light scattering ranged between 96 and 158 lm. Diffusion coefficients (D) of water transport through the microspheres were determined using an empirical equation. Values of D decrease with increasing crosslinking as well as increasing content of starch in the microspheres. In-vitro release studies were performed in 1.2 and 7.4 pH media to simulate the gastric and intestinal conditions. The results indicated a dependence on the amount of polymer and extent of crosslinking. Release data were fitted to an empirical relation to estimate transport parameters and to understand the transport mechanism. Statistical analyses of release data was performed using analysis of variance (ANOVA) method. Suitable microspheres were selected and compressed into tablets using the directly compressible excipients. SEM photographs of the fractured part of the tablet revealed the presence of discrete microspheres in the tablets, suggesting that the system chosen is ideal for tableting. Tablets significantly lowered the initial burst effect when compared to microsphere formulations. The tablets were effective in releasing the AMP over an extended period of about 24 h.

External environments affect prenyl alcohol production by squalene synthetase-deficient mutant Saccharomyces cerevisiae ATCC 64031. Cultivation of the yeast in medium with an initial pH ranging from 7.0 to 8.0 increased the amount of secreted farnesol (FOH). In contrast, acidic medium with a pH below 4.0 increased the intracellular FOH and its isomer nerolidol. These effects of alkaline pH were also observed on constant pH cultivation in a jar fermenter. On cultivation for 133 h, the FOH production reached 102.8 mg/l.

Leaching was performed to recover zinc from a zinc leach residue which contained 9.87% Zn and 4.93% Fe. During sulfuric acid leaching, Fe was dissolved as well as Zn which can reduce the Zn extraction efficiency. Leaching the residue in the presence of an oxidizing reagent such as hydrogen peroxide or manganese dioxide significantly reduced the iron content of the leach liquor. Effect of pH, temperature, solid/liquid ratio, reaction time and hydrogen peroxide or manganese dioxide concentration on the recovery of zinc and iron in non-oxidative and oxidative leaching conditions were investigated. By using the optimum oxidative leaching conditions, iron recovery reduced from 70% in non-oxidative leaching to 0.4 and 5% in the presence of MnO2 and H2O2, respectively, with acceptable Zn recovery. This reduction in the iron content was due to the different iron compounds formed at different conditions.

A differential pH technique for lactose and lactulose determination in milk samples (UHT, pasteurised, sterilised and fresh milk) is presented. With enzymatic reactions, causing a pH variation directly proportional to the lactose and lactulose contents in samples, in less than two and four minutes, respectively, the lactose and lactulose can be analysed without sample preparation procedures. The automatic methods are very simple, precise and accurate, with an excellent linearity for lactose (R 2 = 0.9999) and lactulose (R 2 = 0.9997) throughout the whole range of concentrations and good repeatability (the coefficient of variation was lower than 0.5%). With the optimised experimental conditions, a sensitivity of 0.1 mmol·L -1 lactulose was obtained.

Se estima que las actividades humanas han causado un calentamiento global de aproximadamente 1,0°C con respecto a los niveles preindustriales. También es probable que el calentamiento global llegue a 1,5°C entre 2030 y 2050 si continúa aumentando al ritmo actual. Los modelos climáticos prevén aumento de la temperatura media, de los episodios de calor extremo y de las precipitaciones intensas, además prevén la probabilidad de sequía y de déficits de precipitación. Para mitigar el cambio climático es necesario reducir las emisiones de GEI e implementar medidas de adaptación. En ese sentido, existen estrategias relacionadas con la conservación del patrimonio, que pueden contribuir con los objetivos propuestos en el Acuerdo de París y en la Agenda 2030. En este artículo se presentan los resultados de las evaluaciones de riesgo de quince ciudades. Para este estudio se consideran los riesgos de origen natural y antrópico, además de los riesgos asociados al cambio climático, que podrían af...