pH In Presence Research Articles

Incorporating Kinetic Modeling in the Development Stages of Hard Rock Mine Projects

Weathering cell test, designed specifically to overcome material-limited constraints, yields prompt and efficient experimental assessment during the development stages of mining projects. However, it has barely benefited from geochemical modeling tools despite their ease of use. Accordingly, this paper aims to strengthen the upstream geochemical assessment via parametric analysis that simulates the effect of various mineral assemblages on leachate quality recovered from weathering cells. The main objective is to simulate the pH in presence of silicate neutralizing minerals and Mn release from carbonates based upon minimal characterization data. The public domain code PHREEQC was used for geochemical kinetic modeling of four weathering cells. The kinetic model utilized a water film concept to simulate diffusion of chemical elements from mineral surfaces to the pore water. The obtained results suggest that the presence of the silicate neutralizing minerals slightly affects the Mn release from carbonates. Furthermore, plagioclases could supply a significant neutralization potential when they predominate the mineral assemblage. Finally, coupling weathering cell test and parametric analyses illuminate the pH evolution for various mineral proportion scenarios.

Buffer Influence on the Amino Acid Silica Interaction.

Protein‐surface interactions are exploited in various processes in life sciences and biotechnology. Many of such processes are performed in presence of a buffer system, which is generally believed to have an influence on the protein‐surface interaction but is rarely investigated systematically. Combining experimental and theoretical methodologies, we herein demonstrate the strong influence of the buffer type on protein‐surface interactions. Using state of the art chromatographic experiments, we measure the interaction between individual amino acids and silica, as a reference to understand protein‐surface interactions. Among all the 20 proteinogenic amino acids studied, we found that arginine (R) and lysine (K) bind most strongly to silica, a finding validated by free energy calculations. We further measured the binding of R and K at different pH in presence of two different buffers, MOPS (3‐(N‐morpholino)propanesulfonic acid) and TRIS (tris(hydroxymethyl)aminomethane), and find dramatically different behavior. In presence of TRIS, the binding affinity of R/K increases with pH, whereas we observe an opposite trend for MOPS. These results can be understood using a multiscale modelling framework combining molecular dynamics simulation and Langmuir adsorption model. The modelling approach helps to optimize buffer conditions in various fields like biosensors, drug delivery or bio separation engineering prior to the experiment.

Harvest of the Oleaginous Microalgae Scenedesmus obtusiusculus by Flocculation From Culture Based on Natural Water Sources.

Harvest and dewatering poses a significant economical burden for industrial algae biomass production. To mitigate these effects, energy efficient techniques for these process steps have to be developed. Flocculation of the microalgae Scenedesmus obtusiusculus in salt based medium was induced by pH-shift and alternatively by addition of two biological flocculants, chitosan, and the commercial tannin CFL-PT. This is the first time that CFL-PT is used as an algae flocculant particularly focusing on harvesting of halophilic strains. The method was characterized and subsequently optimized. In comparison to biological flocculants, induction by pH shift is far cheaper, but due to buffering effects of the brackish cultivation medium infeasible amounts of base are required to raise the pH-value. tannin appears to be superior compared to chitosan not only in the absence of algae organic matter (AOM), but tannin-based harvest is also more robust regarding culture pH in presence of AOM. A higher flocculant-demand for modified tannin compared to chitosan is offset by the lower price. Given the employed strain and cultivation conditions, cultivation time had no pronounced effect on flocculation efficiencies (FE) while algae zeta-potential and bacterial communities also remained stable.

Photo-electro-Fenton process applied to the degradation of valsartan: Effect of parameters, identification of degradation routes and mineralization in combination with a biological system

In this work, the oxidation of the antihypertensive drug valsartan by the Electro-Fenton (EF) and photo-electro-Fenton (PEF) processes was studied using a Ti/IrO2 doped with SnO2 as anode, and a carbon felt air diffusion electrode as cathode. Initially, the influence of variables such as supporting electrolyte type, current density, and pH on EF and/or PEF processes was evaluated. The processes were carried out in batch mode, in an open and undivided cell of 200 cm3. The efficiency of the systems was evaluated in terms of the removal of the initial contaminant and rate of mineralization. When NaCl was used as a supporting electrolyte at pH 3.0 and current density 3.46 mA/cm2 adding 3.6 × 10−5 mol/L of Fe2+, total valsartan (20 mg/L) degradation was observed after 45 min. After 120 min, even if total removal of valsartan was reached, only 25% of mineralization was obtained. Thus, valsartan degradation tests at near neutral pH in presence of oxalic acid (4.6 × 10−5 mol/L) lead to comparable results with those obtained at pH 3.0. Primary aromatic intermediates were identified by high resolution mass spectrometry (HRMS) using hybrid quadrupole- time-of-flight (QTOF) MS, from which an initial degradation pathway was proposed. At the end of the PEF system, several aliphatic acids were accumulated and observed, which were effectively removed in a subsequent aerobic biological system. The results demonstrate the feasibility of PEF and biological coupling process to completely mineralize emerging pharmaceutical pollutants, such as valsartan, at natural pH.

Sustainable extraction and dyeing of microwave-treated silk fabric using arjun bark colorant

ABSTRACTDue to an increase in awareness of harmful aspects of synthetic dyes among the global community, the demand of natural dyes in textile sector has been dramatically increased. The current study has been conducted to explore new eco-friendly source of natural brown colorant from arjun bark for textile. Both bark powder and silk fabrics were microwave irradiated for 1–6 min. Dyeing was performed at different variables onto irradiated and un-irradiated silk using extracts obtained from irradiated and un-irradiated powder. To make the dyeing process more sustainable, two chemical and bio-mordants were employed at optimal conditions. The results show that acidified methanolic extract from irradiated powder (RP, 8g) has given high color strength if irradiated silk (RSi) is dyed for 65 min. at 65°C using dye bath of 1 pH in presence of 7% of Na2SO4 as exhausting agent. Good shades and improved fastness characteristics have been obtained by employing 1% of Fe (iron sulfate) and Al (aluminum sulfate) as Chemical and 1% of turmeric and pomegranate extracts as bio-mordants. Hence, microwave radiation has not only explored the coloring efficacy of arjun bark as potential source of natural brown dye but also made its applicability under sustainable conditions.

TiO2-carbon quantum dots (CQD) nanohybrid: enhanced photocatalytic activity

In situ synthesized carbon quantum dot (CQD)-titanium dioxide (TiO2) nanostructures were found to exhibit excellent photocatalytic dye degradation properties. CQDs were synthesized by solvothermal decomposition of PEG in basic pH in presence of NaOH and their morphology and photophysical properties were studied. Nanostructures were produced by synthesizing CQDs in the presence of (a) commercial TiO2 [CQD/TiO2-P25] and (b) TiO2 precursor [CQD/TiO2] to obtain co-synthesized nanostructures. The photocatalytic properties of the hetero-structures, was also studied and compared with those of commercial TiO2-P25 and synthesized TiO2. The photocatalytic degradation rates of methylene blue were found to rise in the order of TiO2-P25 (2.00 × 10−3 min−1), synthesized TiO2 (6.7 × 10−3 min−1), CQD/TiO2-P25 (1.31 × 10−2 min−1) and CQD/TiO2 (3.6 × 10−2 min−1) respectively. The highest degradation rate for CQD/TiO2 among the samples is attributed to the superior interface between the CQDs and the TiO2, leading to higher interfacial charge transfer. The observed 18-fold increase in degradation rate for CQD/TiO2 over commercial TiO2-P25 photocatalyst and the over two-fold increase over CQD/TiO2-P25 photocatalyst, has significant techno-commercial implications, making CQD/TiO2 a promising photocatalyst.

Self-assembly of water soluble perylene tetracarboxylic acid with metal cations: Selective fluorescence sensing of Cu2+ and Pb2+ ions in paper strips, zebrafish and yeast

Self-assembly of water soluble highly fluorescent perylene tetracarboxylic (PTCA, Φf = 0.67) dye via metal coordination has been leads to the selective fluorescence sensing of Cu2+ and Pb2+ ions at neutral pH and Ag+ ions sensing via nanoparticles formation at basic medium. High-resolution transmission electron microscopic (HR-TEM) analysis revealed the conversion 1-D nanostructures of PTCA to spherical aggregates with Cu2+ and hexagonal prisms with Pb2+ ions. However, Ag+ ions were reduced to silver nanoparticles (AgNPs) at higher pH. The concentration dependent studies showed detection of both metal ions up to µM concentration level. Interference studies suggested good selectivity for both Cu2+ and Pb2+ ions at neutral pH in presence of other metal cations. Importantly, application potential of PTCA for selective fluorescence sensing of Cu2+ and Pb2+ ions have been demonstrated in filter paper as well as biological environment such as zebrafish and yeast.

Target-directed Dynamic Combinatorial Chemistry: A Study on Potentials and Pitfalls as Exemplified on a Bacterial Target.

Target-directed dynamic combinatorial chemistry (DCC) is an emerging technique for the efficient identification of inhibitors of pharmacologically relevant targets. In this contribution, we present an application for a bacterial target, the lectin FimH, a crucial virulence factor of uropathogenic E. coli being the main cause of urinary tract infections. A small dynamic library of acylhydrazones was formed from aldehydes and hydrazides and equilibrated at neutral pH in presence of aniline as nucleophilic catalyst. The major success factors turned out to be an accordingly adjusted ratio of scaffolds and fragments, an adequate sample preparation prior to HPLC analysis, and the data processing. Only then did the ranking of the dynamic library constituents correlate well with affinity data. Furthermore, as a support of DCC applications especially to larger libraries, a new protocol for improved hit identification was established.

Magnesium and molecular crowding of the cosolutes stabilize the i-motif structure at physiological pH.

Most of the important genomic regions, especially the G,C rich gene promoters, consist of sequences with potential to form G,C-tetraplexes on both the DNA strands. In this study, we used three C-rich oligonucleotides (11Py, 21Py, and HTPy), of which 11Py and 21Py are located at various transcriptional regulatory elements of the human genome while HTPy sequence is a C-rich strand of human telomere sequence. These C-rich oligonucleotides formed i-motif structures, verified by Circular Dichroism (CD), UV absorption melting experiments, and native gel electrophoresis. The CD spectra revealed that 11Py and 21Py form i-motif structures at acidic pH values of 4.5 and 5.7 in the presence of 100 mM NaCl but remain unstructured at pH 7.0. However, 21Py can form stable i-motif structure even at neutral pH in presence of 1 mM MgCl2 . UV-thermal melting studies showed stabilization of 21Py i-motif at pH 5.7 in the presence of Na+ or K+ with increasing concentration of MgCl2 or CaCl2 from 1 to 10 mM. Significant shift in the CD peak of HTPy sequence was observed as the positive peak from 286 nm shifted to 276 nm while the negative peak from 265 to 254 nm. Further, inevitable necessity of 1 mM Mg2+ to form i-motif structure at neutral pH was observed. Under similar ionic conditions and neutral pH, all the three C-rich sequences were able to form stable i-motif structures (11Py, 21Py) or altered i-motif/homoduplex structures (HTPy) in the presence of MgCl2 and cell mimicking molecular crowding conditions of 40 wt% PEG 200. It is concluded that presence of Mg2+ ions and molecular crowding agents induce and stabilize i-motif structures at physiological solution environment.

Customized tuning of aggregation-induced emission of a napthalimide dye by surfactants and cyclodextrin

The aggregation-induced emission behaviour of an environment sensitive 2,3-substituted napthalimide dye has been investigated at neutral pH in presence of three different surfactants i.e., cationic, anionic, and neutral. The changes observed in the excitation spectrum of the dye compared to its absorption spectra in water in presence of the surfactants above their micellar concentration reveals the transformation of the H-aggregates of the dye to the monomeric form. The alteration of the dye aggregates to its monomeric form and its consequence on emission properties has been utilized to estimate the surfactant concentration parameter for pre-micellar to micellar transformation. The aggregation of the dye molecules has been made reversible by removal of the surfactant molecules from the system upon host-guest complexation with α-cyclodextrin. This switchable aggregation-deaggregation phenomenon of DMN-Bu by employing surfactants and α-cyclodextrin at neutral pH in water is utilized for determining their critical micellar concentration.

Acidotoxicity via ASIC1a Mediates Cell Death during Oxygen Glucose Deprivation and Abolishes Excitotoxicity.

Ischemic reperfusion (I/R) injury is associated with a complex and multifactorial cascade of events involving excitotoxicity, acidotoxicity, and ionic imbalance. While it is known that acidosis occurs concomitantly with glutamate-mediated excitotoxicity during brain ischemia, it remains elusive how acidosis-mediated acidotoxicity interacts with glutamate-mediated excitotoxicity. Here, we investigated the effect of acidosis on glutamate-mediated excitotoxicity in acute hippocampal slices. We tested the hypothesis that mild acidosis protects against I/R injury via modulation of NMDAR, but produces injury via activation of acid sensing ion channels (ASIC1a). Using a novel microperfusion approach, we monitored time course of injury in acutely prepared, adult hippocampal slices. We varied the duration of insult to delay the return to preinsult conditions to determine if injury was caused by the primary insult or by the modeled reperfusion phase. We also manipulated pH in presence and absence of oxygen glucose deprivation (OGD). The role of ASIC1a and NMDAR was deciphered by treating the slices with and without an ASIC or NMDAR antagonist. Our results show that injury due to OGD or low pH occurs during the insult rather than the modeled reperfusion phase. Injury mediated by low pH or low pH OGD requires ASIC1a and is independent of NMDAR activation. These findings point to ASIC1a as a mediator of ischemic cell death caused by stroke and cardiac arrest.

Hyperthermostable binding molecules on phage: Assay components for point-of-care diagnostics for active tuberculosis infection

Tuberculosis is the leading cause of death from infectious disease worldwide. The low sensitivity, extended processing time, and high expense of current diagnostics are major challenges to the detection and treatment of tuberculosis. Mycobacterium tuberculosis ornithine transcarbamylase (Mtb OTC, Rv1656) has been identified in the urine of patients with active TB infection and is a promising target for point-of-care diagnostics. Specific binding proteins with low nanomolar affinities for Mtb OTC were selected from a phage display library built upon a hyperthermostable Sso7d scaffold. Phage particles displaying Sso7d variants were utilized to generate a sandwich ELISA-based assay for Mtb OTC. The assay response is linear between 2 ng/mL and 125 ng/mL recombinant Mtb OTC and has a limit of detection of 400 pg/mL recombinant Mtb OTC. The assay employing a phage-based detection reagent is comparable to commercially-available antibody-based biosensors. Importantly, the assay maintains functionality at both neutral and basic pH in presence of salt and urea over the range of concentrations typical for human urine. Phage-based diagnostic systems may feature improved physical stability and cost of production relative to traditional antibody-based reagents, without sacrificing specificity and sensitivity.

An investigation of microscopic precipitation and micellization of sodium deoxycholate in presence of Tween 40

Abstract In this work the behavior of NaDC as a function of solution pH in presence of Tween 40 has been studied. The pH results were modelled in terms of carboxylate soap solution theory by Lucassen and its generalized form by Kralchevsky et al. The results reveal that the composition of the NaDC solution in terms of various soaps changes as a function of Tween 40 concentration. In general, Tween 40 has almost no effect on the alkanoic acid HZ formation, but hinders the formation of acid soap (HZ)2(MZ)1 depending upon Tween 40 concentration. However, neutral soap MZ formation is favoured at very high concentrations of Tween 40. The influence of Tween 40 on the composition of NaDC solution has been attributed to the ability of the former to show enhanced hydrogen bonding. The presence of different precipitates is well correlated with the surface tension variation and micelles are formed prior to HZ precipitation. The study is expected to provide useful insights to understand the correlation between precipitation and micellization of bile salts and is expected to help in devising methods to enhance their biological functioning in presence of neutral amphiphiles like Tween 40 commonly encountered in delivery systems or food stuffs etc.

Detection of creatinine using surface-driven ordering transitions of liquid crystals

ABSTRACTDetermining creatinine levels in blood is of great importance in the detection of high risk for renal failure. Here, we report a simple methodology for real-time monitoring of creatinine employing surface-driven ordering transitions in liquid crystals (LCs) by changing pH in presence of creatinine deiminase enzyme. It is found that when 5CB (4-Cyano-4ʹ-pentylbiphenyl) LC doped with 4ʹ-hexyl-biphenyl-4-carboxylic acid, a bright optical appearance was observed (at aqueous–LC interface) which is not disturbed in presence of creatinine, consistent with a planar/tilted orientation of the LC molecules at those interface. Interestingly, in presence of creatinine deiminase, an ordering transition was observed resulting from enzymatic reactions (giving rise to NH4+ ions) that can change the local pH values and lead to dark optical appearance of the LC. Presence of different amounts of creatinine would lead varied ordering transition that can be monitored in real time in presence of creatinine deiminase. Our approach could detect the creatinine levels as low as that of the healthy adult (~50 µM) and can be successfully applied to measure higher concentration of creatinine in real time using dynamic optical response of the LC.

Characterization of smart auto-degradative hydrogel matrix containing alginate lyase to enhance levofloxacin delivery against bacterial biofilms

The aim of the present work is the characterization of smart auto-degradable microspheres composed of calcium alginate/high methoxylated pectin containing an alginate lyase (AL) from Sphingobacterium multivorum and levofloxacin. Microspheres were prepared by ionotropic gelation containing AL in its inactive form at pH 4.0. Incubation of microspheres in Tris–HCl and PBS buffers at pH 7.40 allowed to establish the effect of ion-chelating phosphate on matrix erodability and suggested an intrinsically activation of AL by turning the pH close to neutrality. Scanning electron and optical microscopies revealed the presence of holes and surface changes in AL containing microspheres. Furthermore, texturometric parameters, DSC profiles and swelling properties were showing strong changes in microspheres properties. Encapsulation of levofloxacin into microspheres containing AL showed 70% efficiency and 35% enhancement of antimicrobial activity against Pseudomonas aeruginosa biofilm. Levofloxacin release from microspheres was not changed at acidic pH, but was modified at neutral pH in presence of AL. Advantageously, only gel matrix debris were detectable after overnight incubation, indicating an autodegradative gel process activated by the pH. Absence of matrix cytotoxicity and a reduction of the levofloxacin toxicity after encapsulation were observed in mammalian CHO-K1 cell cultures. These properties make the system a potent and versatile tool for antibiotic oral delivery targeted to intestine, enhancing the drug bioavailability to eradicate bacterial biofilm and avoiding possible intestinal obstructions.

Sensitivity of porcine epidemic diarrhea virus (PEDV) to pH and heat treatment in the presence or absence of porcine plasma

Emergence of porcine epidemic diarrhea virus (PEDV) resulted in massive neonatal mortality in the North-American and Asian pork industry. Measures to prevent its geographical spread are of utmost importance to safeguard susceptible porcine populations. The major infection route is direct or indirect faecal-oral contact. Adequate biosafety measures should be in place at all levels of the swine production chain, including feed and feed ingredients. Present study aimed to investigate the sensitivity of PEDV to thermal inactivation at neutral and alkaline pH in presence or absence of porcine plasma. Cell culture medium and porcine plasma at different pH (7.2, 9.2, 10.2) and temperature conditions (4°C, 40°C, 44°C, 48°C) were inoculated to a final titer of 5.5 log10 TCID50 PEDV/ml, incubated for up to 120min and the residual infectivity was determined by endpoint dilution assay. Irrespective of presence of plasma, PEDV was not sensitive to pH 7.2–10.2 at 4°C. At moderate temperatures (≥40°C), both alkaline pH and presence of plasma potentiated thermal inactivation. Inactivation of 8 log10 TCID50/ml plasma within 30min (8D value<30min) by moderate pH and temperature would denote potential industrial processing conditions that ensure safety towards PEDV while limiting denaturation of bioactive components. Virus-spiked plasma required heat treatment of 40°C and alkalinization to pH 9.2 to achieve 8 log10 reduction within such time. At pH 10.2 and 48°C, the 8D value was 4.6min in plasma and 15.2min in MEM. Here we propose heat-alkalinity-time (HAT) pasteurization as a highly efficient method to inactivate PEDV during industrial processing of porcine plasma.

Development of liquid oral sustained release formulations of nateglinide: In vitro and in vivo evaluation

The objective of this work was to develop calcium free alginate and alginate/chitosan in situ gelling systems of nateglinide. Nateglinide dispersions containing alginate or alginate-chitosan were prepared in presence or absence of calcium chloride. The viscosity, gelling capacity and drug release were monitored before evaluating the hypoglycemic effect of selected formulations. In situ gel formation was achieved at gastric pH in presence and absence of calcium ion. Chitosan increased the gelling capacity and reduced the rate of drug release in gastric and intestinal phase. The in vivo results revealed extended hypoglycemic effect after administration of calcium free formulations compared to aqueous suspension of the drug. In absence of calcium ions an acid gel was formed as a result of inter and intra-molecular hydrogen bonding with the protonated carboxylic groups playing an important role. This gel dissolves readily in the intestinal conditions. Addition of chitosan strengthened the gel via polyelectrolyte complexation between alginate and chitosan. This gel maintained its strength irrespective to the pH. In conclusion calcium free alginate based in situ gelling system was able to sustain the release of nateglinide with the efficacy being enhanced in presence of chitosan.

Photoluminescence, photocatalytic and antibacterial activities of CeO2·CuO·ZnO nanocomposite fabricated by co-precipitation method

A novel tri-metallic oxide nanocomposite CeO2·CuO·ZnO has been synthesized by a simple co-precipitation method. The nanocomposite has been characterized by XRD, SEM, EDS, FTIR and PL spectra. The crystallite size of the CeO2·CuO·ZnO was calculated using XRD data. The crystallite size of the CeO2·CuO·ZnO mixed metal oxide annealed at 600°C is found to be in range of 15.34–44.81nm, with an average size of 29.51nm. Excitation at different wavelengths showed PL in UV and visible regions. It has been found that PL behavior of CeO2·CuO·ZnO is excitation wavelength dependent. This flexible PL property is conflicting to well-known Kasha’s rule of excitation wavelength dependence of emission spectrum. The catalyst shows better photo-catalytic dye degradation efficiency in slightly alkaline pH in presence of H2O2. Nanocomposite CeO2·CuO·ZnO was found to be effective against pathogenic bacteria.

Reversible hydrophobic ion-paring complex strategy to minimize acylation of octreotide during long-term delivery from PLGA microparticles

Acylation of peptide has been reported for a number of peptides and proteins during release from polymers comprising of lactide and glycolide. We hypothesize that reversible hydrophobic ion-pairing (HIP) complex may minimize octreotide acylation during release. Sodium dodecyl sulfate (SDS), dextran sulfate A (DSA, Mw 9–20kDa) and dextran sulfate B (DSB, Mw 36–50kDa) were selected as ion-pairing agents to prepare reversible HIP complex with octreotide. Complexation efficiency was optimized with respect to the mole ratio of ion-pairing agent to octreotide to achieve 100% complexation of octreotide. Dissociation studies suggested that DSA-octreotide and DSB-octreotide complexes dissociate completely at physiological pH in presence of counter ions unlike SDS-octreotide complex. DSA-octreotide and DSB-octreotide complex encapsulated PLGA microparticles (DSAMPs and DSBMPs) were prepared using the S/O/W emulsion method. Entrapment efficiencies for DSAMPs and DSBMPs were 74.7±8.4% and 81.7±6.3%, respectively. In vitro release of octreotide was performed by suspending MPs in gel. A large fraction of peptide was released in chemically intact form and <7% was acylated from DSAMPs and DSBMPs in gel over 55 days. Therefore, HIP complexation could be a viable strategy to minimize acylation of peptides and proteins during extended release from lactide and glycolide based polymers.

Photocatalytic degradation of polycyclic aromatic hydrocarbon benzo[a]pyrene by iron oxides and identification of degradation products

Photocatalytic decay profiles of polycyclic aromatic hydrocarbon (PAH) benzo[a]pyrene (B[a]P) have been investigated on various synthesized iron oxides and on soil surfaces under a set of diverse conditions. Samples were analysed using the developed HPLC procedure. Results of the present study demonstrate fastest photodisintegration of B[a]P on goethite followed by haematite, magnetite, akaganeite and maghemite, respectively. The effect of soil pH, irradiation wavelength and iron oxide and oxalic acid dose on the degradation of B[a]P was evaluated. The studies revealed enhancement in photodegradation in the presence of oxalic acid due to the occurrence of fenton like reaction. The results showed faster B[a]P degradation under short wavelength UV radiation. Rate constants in acidic, neutral and alkaline soils under optimum dissipation conditions were 1.11×10−2, 7.69×10−3 and 9.97×10−3h−1, respectively. The study indicates that iron oxides along with oxalic acid are effective photocatalyst for the remediation of benzo[a]pyrene contaminated soil surfaces. The degradation products of B[a]P in the soils of different pH in presence of goethite were identified and degradation pathways proposed. Peaks due to toxic metabolites such as diones, diols and epoxides disappear after 120h in all the three soils.