Search results for: dissolution kinetics

Authors: Sajjad Hussain, Sabir Khan, Maria Del Pilar Taboada Sotomayor

Abstract:

This work demonstrates the synthesis of magnetic molecularly imprinted polymers (MMIPs) for determination of a selected pesticide (ametryne) using high performance liquid chromatography (HPLC). Computational simulation can assist the choice of the most suitable monomer for the synthesis of polymers. The (MMIPs) were polymerized at the surface of Fe3O4@SiO2 magnetic nanoparticles (MNPs) using 2-vinylpyradine as functional monomer, ethylene-glycol-dimethacrylate (EGDMA) is a cross-linking agent and 2,2-Azobisisobutyronitrile (AIBN) used as radical initiator. Magnetic non-molecularly imprinted polymer (MNIPs) was also prepared under the same conditions without analyte. The MMIPs were characterized by scanning electron microscopy (SEM), Brunauer, Emmett and Teller (BET) and Fourier transform infrared spectroscopy (FTIR). Pseudo first order and pseudo second order model were applied to study kinetics of adsorption and it was found that adsorption process followed the pseudo first order kinetic model. Adsorption equilibrium data was fitted to Freundlich and Langmuir isotherms and the sorption equilibrium process was well described by Langmuir isotherm mode. The selectivity coefficients (α) of MMIPs for ametryne with respect to atrazine, ciprofloxacin and folic acid were 4.28, 12.32, and 14.53 respectively. The spiked recoveries ranged between 91.33 and 106.80% were obtained. The results showed high affinity and selectivity of MMIPs for pesticide ametryne in the food samples.

Keywords: molecularly imprinted polymer, pesticides, magnetic nanoparticles, adsorption

Procedia PDF Downloads 466

Authors: M. Agostini, A. Sonato, G. Greco, M. Travagliati, G. Ruffato, E. Gazzola, D. Liuni, F. Romanato, M. Cecchini

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Since their first demonstration in the early 1980s, surface plasmon resonance (SPR) sensors have been widely recognized as useful tools for detecting chemical and biological species, and the interest of the scientific community toward this technology has known a rapid growth in the past two decades owing to their high sensitivity, label-free operation and possibility of real-time detection. Recent works have suggested that a turning point in SPR sensor research would be the combination of SPR strategies with other technologies in order to reduce human handling of samples, improve integration and plasmonic sensitivity. In this light, microfluidics has been attracting growing interest. By properly designing microfluidic biochips it is possible to miniaturize the analyte-sensitive areas with an overall reduction of the chip dimension, reduce the liquid reagents and sample volume, improve automation, and increase the number of experiments in a single biochip by multiplexing approaches. However, as the fluidic channel dimensions approach the micron scale, laminar flows become dominant owing to the low Reynolds numbers that typically characterize microfluidics. In these environments mixing times are usually dominated by diffusion, which can be prohibitively long and lead to long-lasting biochemistry experiments. An elegant method to overcome these issues is to actively perturb the liquid laminar flow by exploiting surface acoustic waves (SAWs). With this work, we demonstrate a new approach for SPR biosensing based on the combination of microfluidics, SAW-induced mixing and the real-time phase-interrogation grating-coupling SPR technology. On a single lithium niobate (LN) substrate the nanostructured SPR sensing areas, interdigital transducer (IDT) for SAW generation and polydimethylsiloxane (PDMS) microfluidic chambers were fabricated. SAWs, impinging on the microfluidic chamber, generate acoustic streaming inside the fluid, leading to chaotic advection and thus improved fluid mixing, whilst analytes binding detection is made via SPR method based on SPP excitation via gold metallic grating upon azimuthal orientation and phase interrogation. Our device has been fully characterized in order to separate for the very first time the unwanted SAW heating effect with respect to the fluid stirring inside the microchamber that affect the molecules binding dynamics. Avidin/biotin assay and thiol-polyethylene glycol (bPEG-SH) were exploited as model biological interaction and non-fouling layer respectively. Biosensing kinetics time reduction with SAW-enhanced mixing resulted in a ≈ 82% improvement for bPEG-SH adsorption onto gold and ≈ 24% for avidin/biotin binding—≈ 50% and 18% respectively compared to the heating only condition. These results demonstrate that our biochip can significantly reduce the duration of bioreactions that usually require long times (e.g., PEG-based sensing layer, low concentration analyte detection). The sensing architecture here proposed represents a new promising technology satisfying the major biosensing requirements: scalability and high throughput capabilities. The detection system size and biochip dimension could be further reduced and integrated; in addition, the possibility of reducing biological experiment duration via SAW-driven active mixing and developing multiplexing platforms for parallel real-time sensing could be easily combined. In general, the technology reported in this study can be straightforwardly adapted to a great number of biological system and sensing geometry.

Keywords: biosensor, microfluidics, surface acoustic wave, surface plasmon resonance

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Authors: Qiming Wang

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Dynamic polymer networks (DPNs) crosslinked by dynamic bonds have received intensive attention because of their special crack-healing capability. Diverse DPNs have been synthesized using a number of dynamic bonds, including dynamic covalent bond, hydrogen bond, ionic bond, metal-ligand coordination, hydrophobic interaction, and others. Despite the promising success in the polymer synthesis, the fundamental understanding of their self-healing mechanics is still at the very beginning. Especially, a general analytical model to understand the interfacial self-healing behaviors of DPNs has not been established. Here, we develop polymer-network based analytical theories that can mechanistically model the constitutive behaviors and interfacial self-healing behaviors of DPNs. We consider that the DPN is composed of interpenetrating networks crosslinked by dynamic bonds. bonds obey a force-dependent chemical kinetics. During the self-healing process, we consider the The network chains follow inhomogeneous chain-length distributions and the dynamic polymer chains diffuse across the interface to reform the dynamic bonds, being modeled by a diffusion-reaction theory. The theories can predict the stress-stretch behaviors of original and self-healed DPNs, as well as the healing strength in a function of healing time. We show that the theoretically predicted healing behaviors can consistently match the documented experimental results of DPNs with various dynamic bonds, including dynamic covalent bonds (diarylbibenzofuranone and olefin metathesis), hydrogen bonds, and ionic bonds. We expect our model to be a powerful tool for the self-healing community to invent, design, understand, and optimize self-healing DPNs with various dynamic bonds.

Keywords: self-healing polymers, dynamic covalent bonds, hydrogen bonds, ionic bonds

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Authors: Kruti Jaruriya

Abstract:

Distribution of arsenic (As) and its compound and related toxicology are serious concerns. This is particularly so since millions worldwide are suffering from toxicity due to drinking of As-contaminated groundwater. The Bengal delta plain, formed by the Ganga– Padma–Meghna–Brahmaputra river basin, covering several districts of West Bengal, India and Bangladesh is considered as the worst As affected alluvial basin. However, some equally affected, if not more, areas are emerging in upper Brahmaputra plains. The present study was carried out to examine As contamination trends in the worst affected part of Assam, India. Arsenic (As) mobilization to the groundwater of Brahmaputra floodplains was investigated in Titabor, Jorhat District, located in the North Eastern part of India. The groundwater and the aquifer geochemistry were characterized. The groundwater is characterized by high dissolved Fe, Mn, and HCO-3 and low concentrations of NO-3 and SO2-4 indicating anoxic conditions prevailing in the groundwater. Fifty groundwater samples collected from shallow and deep tubewells of Titabor, Jorhat district (Assam) were examined. Along with total As, examination of concentration levels of other key parameters, viz., pH, EC, Fe, Mn , Mg2+, Ca2+, Na+, K+, PO43- , HCO-3 , NO3- ,Cl - and SO42- was also carried out. In respect to the permissible guideline of World Health Organization (WHO: As 0.01 ppm, Fe 1.0 ppm, and Mn 0.3 ppm for potable water), the range of As concentration in the groundwater varied from 0.014 to 0.604 mg/L with mean concentration 0.184 mg/L. The present study showed that out of the 50 groundwater samples,100%, 54%, and 42% were found contaminated with higher metal contents (for total As, Fe, and Mn, respectively). The results of hydrogeochemical study revealed that the reductive dissolution of MnOOH and FeOOH represents an important mechanism of arsenic release in the study area along with major cations playing an important role in leaching of As into the groundwater. Arsenic released by oxidation of pyrite, as water levels are drawn down and air enters the aquifer, contributes negligibly to the problem of As pollution. Identification of the mechanism of As release to groundwater helps to provide a framework to guide the placement of new water wells so that they will have acceptable concentrations of As.

Keywords: arsenic, assam, brahmaputra floodplain, groundwater, hydrogeochemistry

Procedia PDF Downloads 287

Authors: C. R. Danielle, S. Erik, T. Patrick, M. Hugh

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In the last decade there has been an increase in demand for fine grinding due to the depletion of coarse-grained orebodies and an increase of processing fine disseminated minerals and complex orebodies. These ores have provided new challenges in concentrator design because fine and ultra-fine grinding is required to achieve acceptable recovery rates. Therefore, the correct design of a grinding circuit is important for minimizing unit costs and increasing product quality. The use of ball mills for grinding in fine size ranges is inefficient and, therefore, vertical stirred grinding mills are becoming increasingly popular in the mineral processing industry due to its already known high energy efficiency. This work presents a hypothesis of a methodology to predict the product size distribution of a vertical stirred mill using a Bond ball mill. The Population Balance Model (PBM) was used to empirically analyze the performance of a vertical mill and a Bond ball mill. The breakage parameters obtained for both grinding mills are compared to determine the possibility of predicting the product size distribution of a vertical mill based on the results obtained from the Bond ball mill. The biggest advantage of this methodology is that most of the minerals processing laboratories already have a Bond ball mill to perform the tests suggested in this study. Preliminary results show the possibility of predicting the performance of a laboratory vertical stirred mill using a Bond ball mill.

Keywords: bond ball mill, population balance model, product size distribution, vertical stirred mill

Procedia PDF Downloads 254

Authors: Sabir Khan, Sajjad Hussain, Ademar Wong, Maria Del Pilar Taboada Sotomayor

Abstract:

The present work aims to develop magnetic molecularly imprinted polymers (MMIPs) for determination of a selected pesticide (ametryne) using high-performance liquid chromatography (HPLC). Computational simulation can assist the choice of the most suitable monomer for the synthesis of polymers. The (MMIPs) were polymerized at the surface of Fe3O4@SiO2 magnetic nanoparticles (MNPs) using 2-vinylpyradine as functional monomer, ethylene-glycol-dimethacrylate (EGDMA) is a cross-linking agent and 2,2-Azobisisobutyronitrile (AIBN) used as radical initiator. Magnetic non-molecularly imprinted polymer (MNIPs) was also prepared under the same conditions without analyte. The MMIPs were characterized by scanning electron microscopy (SEM), Brunauer, Emmett and Teller (BET) and Fourier transform infrared spectroscopy (FTIR). Pseudo first-order and pseudo second order model were applied to study kinetics of adsorption and it was found that adsorption process followed the pseudo-first-order kinetic model. Adsorption equilibrium data was fitted to Freundlich and Langmuir isotherms and the sorption equilibrium process was well described by Langmuir isotherm mode. The selectivity coefficients (α) of MMIPs for ametryne with respect to atrazine, ciprofloxacin and folic acid were 4.28, 12.32 and 14.53 respectively. The spiked recoveries ranged between 91.33 and 106.80% were obtained. The results showed high affinity and selectivity of MMIPs for pesticide ametryne in the food samples.

Keywords: molecularly imprinted polymer, pesticides, magnetic nanoparticles, adsorption

Procedia PDF Downloads 443

Authors: H. Aljabiry, L. Bailey, S. Young

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Qatar is a desert with an average temperature 37⁰C, reaching over 40⁰C during summer. Precipitation is uncommon and mostly in winter. Qatar depends on desalination for drinking water and on groundwater and recycled water for irrigation. Water consumption and network leakage per capita in Qatar are amongst the highest in the world; re-use of treated wastewater is extremely limited with only 14% of treated wastewater being used for irrigation. This has led to the country disposing of unwanted water from various sources in lagoons situated around the country, causing concern over the possibility of environmental pollution. Accordingly, our hypothesis underpinning this research is that the quality and quantity of water in lagoons is having an impact on the groundwater reservoirs in Qatar. Lagoons (n = 14) and wells (n = 55) were sampled for both summer and winter in 2018 (summer and winter). Water, adjoining soil and plant samples were analysed for multiple elements by Inductively Coupled Plasma Mass Spectrometry. Organic and inorganic carbon were measured (CN analyser) and the major anions were determined by ion chromatography. Salinization in both the lagoon and the wells was seen with good correlations between Cl⁻, Na⁺, Li, SO₄, S, Sr, Ca, Ti (p-value < 0.05). Association of heavy metals was observed of Ni, Cu, Ag, and V, Cr, Mo, Cd which is due to contamination from anthropological activities such as wastewater disposal or spread of contaminated dust. However, looking at each elements none of them exceeds the Qatari regulation. Moreover, gypsum saturation in the system was observed in both the lagoon and wells water samples. Lagoons and the water of the well are found to be of a saline type as well as Ca²⁺, Cl⁻, SO₄²⁻ type evidencing both gypsum dissolution and salinization in the system. Moreover, Maps produced by Inverse distance weighting showed an increasing level of Nitrate in the groundwater in winter, and decrease chloride and sulphate level, indicating recharge effect after winter rain events. While E. coli and faecal bacteria were found in most of the lagoons, biological analysis for wells needs to be conducted to understand the biological contamination from lagoon water infiltration. As a conclusion, while both the lagoon and the well showed the same results, more sampling is needed to understand the impact of the lagoons on the groundwater.

Keywords: groundwater quality, lagoon, treated wastewater, water management, wastewater treatment, wetlands

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Authors: Nesrine Benarous, Hassiba Bougueria, Nabila Moussa Slimane, Aouatef Cherouana

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Crystal polymorphism is important for the synthesis of more potent and bioactive pharmaceutical compounds, including their different properties, such as packing arrangement and conformation. In fact, polymorphism plays a vital role in drug development. Different parameters affect the crystallization and give their degree of freedom. Severalproperties affected polymorphism, like kinetics, thermodynamics, spectroscopy, and mechanical property. Various techniques are used for characterizing polymorphs, are crystallography, morphology, phase transitions, molecular motion, and chemical environment. In this work, crystal structures of two polymorphs (I and II) of the Schiff base (SB) title compound were prepared by condensation reaction. The crystal structures of both polymorphs were determined by single X-ray analysis. The two polymorphs crystallize in two different space groups: P21/c for I and Pbca for II. The dihedral angles between the two phenyl rings are 4.81º for I and 82.27º for II. Both crystal structures are built on the basis of moderate and weak hydrogen bonds, 𝜋-stacking, and halogen⋯halogeninteractions. On the other hand, Hirshfeld surface (HS) analysis indicates that the most important contributions to the crystal packing for the two polymorphs are from Cl⋯H/H⋯Cl, H⋯H, and N⋯H/H⋯N contacts. These are followed by C⋯H/H⋯C for compound I and C⋯C and by C⋯H/H⋯C contacts for compound II. Afterwards, the in vitro antibacterial activity revealed that the SB have been found effective against G- bacteria Klebsiella pneumonia andG+ bacteria Staphylococcus aureuswith MIC value of14.37μg/mL. Moreover, the SBexhibited moderate toxicity against Brine Shrimp with LC50 value of 44.19μg/mL.

Keywords: polymorph, crystal structure, hirshfeld surface analysis, in vitro antibacterial activity, toxicity

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Authors: Zohreh Fallah, Edward P. L. Roberts

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One of the big challenges for produced water treatment is removing oil from water in the form of emulsified droplets which are not easily separated. An attractive approach is adsorption, as it is a simple and effective process. However, adsorbents must be regenerated in order to make the process cost effective. Several sorbents have been tested for treating oily wastewater. However, some issues such as high energy consumption for activated carbon thermal regeneration have been reported. Due to their significant electrical conductivity, Graphite Intercalation Compounds (GIC) were found to be suitable to be regenerated electrochemically. They are non-porous materials with low surface area and fast adsorptive capacity which are useful for removal of low concentration of organics. An innovative adsorption/regeneration process has been developed at the University of Manchester in which adsorption of organics are done by using a patented GIC adsorbent coupled with subsequent electrochemical regeneration. The oxidation of adsorbed organics enables 100% regeneration so that the adsorbent can be reused over multiple adsorption cycles. GIC adsorbents are capable of removing a wide range of organics and pollutants; however, no comparable report is available for removal of emulsified oil in produced water using abovementioned process. In this study the performance of this technology for the removal of emulsified oil in wastewater was evaluated. Batch experiments were carried out to determine the adsorption kinetics and equilibrium isotherm for both real produced water and model emulsions. The amount of oil in wastewater was measured by using the toluene extraction/fluorescence analysis before and after adsorption and electrochemical regeneration cycles. It was found that oil in water emulsion could be successfully treated by the treatment process and More than 70% of oil was removed.

Keywords: adsorption, electrochemical regeneration, emulsified oil, produced water

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Authors: Nisreen Agha

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Investigation of representative core samples under the petrological microscope reveals common petrographic and mineralogical characteristics with distinct faunal assemblages, allowing establishing of the microfacies associations and deducing the paleoenvironmental trends of the Paleocene Farrud and Mabruk rock units. Recognition of the early and post-diagenetic processes, particularly dolomitization and micritization, as well as dissolution and precipitation of spary drusy calcite as a new morphism process affecting the reservoir rocks, is established. The microfacies trends detected from the investigation of 46 core samples from Farrud member (Lower Paleocene) representing six wells; QQQ1-11, GG1-11, LLL1-11, RRR1-11, RRR40-11, and RRR45-11 indicate that the deposition was started within the realm of shallow supratidal and intertidal subenvironments followed by deeper environments of the shelf bays with maximum sea level during inner shelf environment where fossiliferous bioclastic packstone dominated. The microfacies associations determined in 8 core samples from two wells LLL1and RRR40 representing Mabruk Member (Upper Paleocene), indicate paleoenvironmental trends marked by sea level fluctuations accompanied with a relatively marine shelf bay conditions intervened with short-lived shallow intertidal and supratidal warm coastal sedimentation. As a result, dolostone, evaporitic dismicrites, and gypsiferous dolostone of supratidal characters were deposited. They reflect rapid oscillation of the sea level marked by drop land-ward shift of the sea shore deposition prevailed by supratidal gypsiferous dolostone and numerous ferruginous materials as clouds straining many parts of dolomite and surrounded the micritized fossils. This situation ends the deposition of the Farrud Member in most of the studied wells. On the other hand, the facies in the northern part of the Concession -11 field indicates deposition in a deeper marine setting than in the southern facies.

Keywords: Farrud and Mabruk members, paleocene, microfacies associations, diagenesis, sea level oscillation, depositional environments

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Authors: Parth Mehta, Vedasri Bai Khavala, Prabhu Rajagopal, Tiju Thomas

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There is an increasing need for alternative clean fuels, and hydrogen (H₂) has long been considered a promising solution with a high calorific value (142MJ/kg). However, the storage of H₂ and expensive processes for its generation have hindered its usage. Sodium borohydride (NaBH₄) can potentially be used as an economically viable means of H₂ storage. Thus far, there have been attempts to optimize the life of NaBH₄ (half-life) in aqueous media by stabilizing it with sodium hydroxide (NaOH) for various pH values. Other reports have shown that H₂ yield and reaction kinetics remained constant for all ratios of H₂O to NaBH₄ > 30:1, without any acidic catalysts. Here we highlight the importance of pH and H₂O: NaBH₄ ratio (80:1, 40:1, 20:1 and 10:1 by weight), for NaBH₄ stabilization (half-life reaction time at room temperature) and corrosion minimization of H₂ reactor components. It is interesting to observe that at any particular pH>10 (e.g., pH = 10, 11 and 12), the H₂O: NaBH₄ ratio does not have the expected linear dependence with stability. On the contrary, high stability was observed at the ratio of 10:1 H₂O: NaBH₄ across all pH>10. When the H₂O: NaBH₄ ratio is increased from 10:1 to 20:1 and beyond (till 80:1), constant stability (% degradation) is observed with respect to time. For practical usage (consumption within 6 hours of making NaBH₄ solution), 15% degradation at pH 11 and NaBH₄: H₂O ratio of 10:1 is recommended. Increasing this ratio demands higher NaOH concentration at the same pH, thus requiring a higher concentration or volume of acid (e.g., HCl) for H₂ generation. The reactions are done with tap water to render the results useful from an industrial standpoint. The observed stability regimes are rationalized based on complexes associated with NaBH₄ when solvated in water, which depend sensitively on both pH and NaBH₄: H₂O ratio.

Keywords: hydrogen, sodium borohydride, stability optimization, H₂O:NaBH₄ ratio

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Authors: Parinaz Tavakoli Zaniani, Dimitrios Balomenos

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Mitochondrial reactive oxygen species (mROS) play a crucial role in macrophage pro-inflammatory activation, although a detailed understanding of the mechanism and kinetics by which mROS drive signaling molecules is still lacking. In general, it is thought that NF-κB activation drives mROS and general ROS production. Here, We performed a detailed kinetic analysis of mROS production during macrophage activation. We found early mROS generation after LPS (lipopolysaccharide) stimulation. Remarkably as early as 5 minutes, mROS signaling promoted initial NF-κB, MAPK activation and pro-inflammatory cytokine production, as established through inhibition or quenching of mROS. On the contrary, NF-κB inhibition had no effect on mROS production. Our findings point to a mechanism by which mROS increase TRAF-6 ubiquitination and, thus NF-κB activity. mROS inhibition reduced LPS-induced lethality in an in vivo septic shock model by controlling pro-inflammatory cytokine production. Overall, our research provides novel insights into the role of mROS as a primary messenger in the pathway of macrophage and as a regulator of inflammatory responses. We found that early mROS production promotes initial NF-κB, and MAPK activation by regulating TRAF-6 ubiquitination and that mROS inhibition can reduce LPS-induced inflammatory cytokines and lethality in a septic shock model. These findings might lead to novel immunotherapeutic strategies targeting early mROS production and control of extreme inflammation in the context of sepsis and other inflammatory diseases.

Keywords: mitochondria, reactive oxygen species, nuclear factor κB, lipopolysaccharide, macrophages

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Authors: Deepika Biswas

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Acinetobacter baumannii, a hospital-acquired pathogen, causes nosocomial infections including pneumonia, urinary tract infection, and secondary meningitis. Carbapenem is most effective antibiotics against it. Its increased resistance to carbapenems has been a rising global concern. Antibiotics such as carbapenem are unable to use on hospital setups to eradicate A. baumannii, hence different concentrations of disinfectants including phenol; sodium hypochlorite and ethanol are increasingly being used. The objective of the present study is to find an effective concentration of above disinfectants against carbapenem-resistant strain RS307 of A. baumannii. Growth kinetics of RS307 has been determined using UV-Vis spectrophotometer in the presence and absence of disinfectants in triplicate and its standard deviation has also been calculated which make the results more reliable. Differential growth curves were plotted, which showed the effective concentration among all the concentrations of phenol, sodium hypochlorite and ethanol. On disc diffusion assay, antimicrobial effect was observed by comparing all the concentrations of disinfectants to check its synergy with imipenem, most effective carbapenem. All the results collectively revealed that 0.5% phenol, 0.5% sodium hypochlorite, and 70% ethanol could preferably be used as disinfectant for hospital setup against the carbapenem-resistant strain of A. baumannii. SDS PAGE analysis showed differential expression in the protein profile of A. baumannii after treatment. The present study highlighted that few disinfectants even in low concentration had shown better antimicrobial activity hence may be recommended for regular use in the hospitals, which will be cost effective and less harmful.

Keywords: Acenatobacter bomunii, phenol, sodium hypoclirite, ethanol, carbapenem resistance, disinfectant

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Authors: Tachita Vlad-Bubulac, Ionela-Daniela Carja, Diana Serbezeanu, Corneliu Hamciuc, Vicente Javier Forrat Perez

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The present work describes the preparation of new organophosphorus compounds with high content of phosphorus followed by the incorporation of these compounds into epoxy resin systems in order to investigate the phosphorus effect in terms of thermal stability, flame-retardant and mechanical properties of modified epoxy resins. Thus, two new organophosphorus compounds have been synthesized and fully characterized. 6-Oxido-6H-dibenz[c,e][1,2]oxaphosphorinyl-phenylcarbinol has been prepared by the addition reaction of P–H group of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to carbonyl group of benzaldehyde. By treating the phenylcarbinol derivative with POCl3 a new phosphorus compound was obtained, having a content of 12.227% P. The organophosphorus compounds have been purified by recrystallization while their chemical structures have been confirmed by melting point measurements, FTIR and HNMR spectroscopies. In the next step various flame-retardant epoxy resins with different content of phosphorus have been prepared starting from a commercial epoxy resin and using dicyandiamide (DICY) as a latent curing agent in the presence of an accelerator. Differential scanning calorimetry (DSC) has been applied to investigate the behavior and kinetics of curing process of thermosetting systems. The results showed that the best curing characteristic and glass transition temperature are obtained at a ratio of epoxy resin: DICY: accelerator equal to 94:5:1. The thermal stability of the phosphorus-containing epoxy resins was investigated by thermogravimetric analysis in nitrogen and air, DSC, SEM and LOI test measurements.

Keywords: epoxy resins, flame retardant properties, phosphorus-containing compounds, thermal stability

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Authors: Andres Diaz Garcia, Ana Maria Ceballos Rojas, Duvan Albeiro Millan Montano

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This paper describes the initial technological development stages in the area of liquid fermentation required to reach the quantities of biomass of the biofertilizer microorganism Rhizobium sp. strain B02, for the application of the unitary stages downstream at laboratory scale. In the first stage, the adjustment and standardization of the fermentation process in conventional batch mode were carried out. In the second stage, various fed-batch and continuous fermentation strategies were evaluated in 10L-bioreactor in order to optimize the yields in concentration (Colony Forming Units/ml•h) and biomass (g/l•h), to make feasible the application of unit operations downstream of process. The growth kinetics, the evolution of dissolved oxygen and the pH profile generated in each of the strategies were monitored and used to make sequential adjustments. Once the fermentation was finished, the final concentration and viability of the obtained biomass were determined and performance parameters were calculated with the purpose of select the optimal operating conditions that significantly improved the baseline results. Under the conditions adjusted and standardized in batch mode, concentrations of 6.67E9 CFU/ml were reached after 27 hours of fermentation and a subsequent noticeable decrease was observed associated with a basification of the culture medium. By applying fed-batch and continuous strategies, significant increases in yields were achieved, but with similar concentration levels, which involved the design of several production scenarios based on the availability of equipment usage time and volume of required batch.

Keywords: biofertilizer, liquid fermentation, Rhizobium sp., standardization of processes

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Authors: Hongtao Zhu, Dezhi Sun

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Nitrogen and phosphorus are essential nutrients for biomass growth. But excessive nitrogen and phosphorus can contribute to accelerated eutrophication of lakes and rivers. Constructed wetland is an efficient and eco-friendly wastewater treatment technology with low operating cost and low-energy consumption. Because of high affinity with ammonium ion, zeolite, as a common substrate, is applied in constructed wetlands worldwide. Another substrate seen commonly for constructed wetlands is steel slag, which has high contents of Ca, Al, or Fe, and possesses a strong affinity with phosphate. Due to the excellent ammonium removal ability of zeolite and phosphate removal ability of steel slag, they were considered to be combined in the substrate bed of a constructed wetland in order to enhance the simultaneous removal efficiencies of nitrogen and phosphorus. In our early tests, zeolite and steel slag were combined with each other in order to simultaneously achieve a high removal efficiency of ammonium-nitrogen and phosphate-phosphorus. However, compared with the results when only zeolite was used, the removal efficiency of ammonia was sharply decreased when zeolite and steel slag were used together. The main objective of this study was to establish an overview of the interaction of steel slag and zeolite on ammonium nitrogen removal. The CaO dissolution from slag, as well as the effects of influencing parameters (i.e. pH and Ca2+ concentration) on the ammonium adsorption onto zeolite, was systematically studied. Modeling results of Ca2+ and OH- release from slag indicated that pseudo-second order reaction had a better fitness than pseudo-first order reaction. Changing pH value from 7 to 12 would result in a drastic reduction of the ammonium adsorption capacity on zeolite, from the peak at pH7. High Ca2+ concentration in solution could also inhibit the adsorption of ammonium onto zeolite. The mechanism for steel slag inhibiting the ammonium adsorption capacity of zeolite includes: on one hand, OH- released from steel slag can react with ammonium ions to produce molecular form ammonia (NH3∙H2O), which would cause the dissociation of NH4+ from zeolite. On the other hand, Ca2+ could replace the NH4+ ions to adhere onto the surface of zeolite. An innovative substrate filling configuration that zeolite and steel slag are placed sequentially was proposed to eliminate the disadvantageous effects of steel slag. Experimental results showed that the novel filling configuration was superior to the other two contrast filling configurations in terms of ammonium removal.

Keywords: ammonium nitrogen, constructed wetlands, steel slag, zeolite

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Authors: Milena Trevisan Pelegrino, Bruna De Araujo Lima, Mônica H. M. Do Nascimento, Christiane B. Lombello, Marcelo Brocchi, Amedea B. Seabra

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Nitric oxide (NO) is a small molecule involved in a wide range of physiological and pathophysiological processes, including vasodilatation, control of inflammatory pain, wound healing, and antibacterial activities. As NO is a free radical, the design of drugs that generates therapeutic amounts of NO in controlled spatial and time manners is still a challenge. In this study, the NO donor S-nitrosoglutathione (GSNO) was incorporated into the thermoresponsive Pluronic F-127 (PL) - chitosan (CS) hydrogel, in an easy and economically feasible methodology. CS is a polysaccharide with known antimicrobial and biocompatibility properties. Scanning electron microscopy, rheology and differential scanning calorimetry techniques were used for hydrogel characterization. The results demonstrated that the hydrogel has a smooth surface, thermoresponsive behavior, and good mechanical stability. The kinetics of NO release and GSNO diffusion from GSNO-containing PL/CS hydrogel demonstrated a sustained NO/GSNO release, in concentrations suitable for biomedical applications, at physiological and skin temperatures. The GSNO-PL/CS hydrogel demonstrated a concentration-dependent toxicity to Vero cells, and antimicrobial activity to Pseudomonas aeruginosa (minimum inhibitory concentration and minimum bactericidal concentration values of 0.5 µg·mL-1 of hydrogel, which correspondents to 1 mmol·L-1 of GSNO). Interesting, the concentration range in which the NO-releasing hydrogel demonstrated antibacterial effect was not found toxic to Vero mammalian cell. Thus, GSNO-PL/CS hydrogel is suitable biomaterial for topical NO delivery applications.

Keywords: antimicrobial, chitosan, biocompatibility, S-nitrosothiols

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Authors: Zakaria Boual, Abdellah Kemassi, Toufik Chouana, Philippe Michaud, Mohammed Didi Ould El Hadj

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In order to investigate the prebiotic potential of oligosaccharides prepared by chemical hydrolysis of water-soluble polysaccharides (WSP) from Zizyphus lotus leaves, the effect of oligosaccharides on bacterial growth was studied. The chemical composition of WSP was evaluated by colorimetric assays revealed the average values: 7.05±0.73% proteins and 86.21±0.74% carbohydrates, among them 64.81±0.42% are neutral sugar and the rest 16.25±1.62% are uronic acids. The characterization of monosaccharides was determined by high performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) was found to be composed of galactose (23.95%), glucose (21.30%), rhamnose (20.28%), arabinose (9.55%), and glucuronic acid (22.95%). The effects of oligosaccharides on the growth of lactic acid bacteria were compared with those of fructo-oligosaccharide (RP95). The oligosaccharides concentration was 1g/L of man rogosa sharpe broth. Bacterial growth was assessed during 2, 4.5, 6.5, 9, 12, 16 and 24 h by measuring the optical density of the cultures at 600 nm (OD600) and pH values. During fermentation, pH in broth cultures decreased from 6.7 to 5.87±0.15. The enumeration of lactic acid bacteria indicated that oligosaccharides led to a significant increase in bacteria (P≤0.05) compared to the control. The fermentative metabolism appeared to be faster on RP95 than on oligosaccharides from Zizyphus lotus leaves. Both RP95 and oligosaccharides showed clear prebiotic effects, but had differences in fermentation kinetics because of to the different degree of polymerization. This study shows the prebiotic effectiveness of oligosaccharides, and provides proof for the selection of leaves of Zizyphus lotus for use as functional food ingredients.

Keywords: Zizyphus lotus, polysaccharides, characterization, prebiotic effects

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Authors: Tania Ali Soomro

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In 1839, the British, after the annexation of the port city of Karachi, established a new urban centre consisting of various quarters and introduced new settlements there. These quarters were out of the boundaries of fortified native old area and now contain much of the oldest parts of the city and signify the colonial history of Karachi, in particular the Saddar Bazaar and the neighboring areas of Kharadar and Mithadar. These quarters bestow a mix of functional typology built in a hybrid form of construction - an adaptation of the western architectural attributes to regional requirements and characteristics. This approach is referred to as the Anglo Vernacular, Colonial or the Domestic Gothic architectural form. This research paper investigates the historical and architectural value of one such property: the Empress Market designed by then Municipal Architect, Ar. James Strachan in 1889 as a commemorative monument for the jubilee of Her Majesty the Queen Victoria; Empress of British India, at that time. This paper presents information on the present conservation status of the market building and highlights its role as a catalyst to the community interconnection. This building has survived to present day and functioned well, despite undergoing numerous transformations. A detailed analysis of the bio-degradation (Natural-Chemical dissolution of material) and the bio-deterioration (Manmade-Negative state change of the material) of the building, based on the examination of the prevailing causes of these bio-alterations is carried out, and is presented in form of a damage atlas containing both the categories of bio-alteration/ changes occurred to the building over the time. The research methodology followed in this paper starts with the available archival analysis, physical observation, photographic documentation, the statistics review and the interviews with the direct and indirect stakeholders. The results and findings of this research portray that these bio-alterations and changes are the essential part of the life cycle of Empress Market building which illustrate the historic development of the premise and therefore ought to be given due importance (depending upon their condition) while developing the conservation plan for the building.

Keywords: British colonial architecture, bio-alteration, bio-degradation, bio-deterioration, domestic gothic architectural form

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Authors: Emily Schlebes, Christian Hundhausen, Jens W. Fischer

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The glycosaminoglycan hyaluronan (HA) is a major component of the extracellular matrix, typically produced by fibroblasts of the connective tissue but also by immune cells. Here, we investigated the capacity of human peripheral blood CD8 T cells from healthy donors to produce HA and to express HA receptors as well as HA degrading enzymes. Further, we evaluated the effect of pharmacological HA inhibition on CD8 T cell function. Using immunocytochemistry together with quantitative PCR analysis, we found that HA synthesis is rapidly induced upon antibody-induced T cell receptor (TCR) activation and almost exclusively mediated by HA synthase 3 (HAS3). TCR activation also resulted in the upregulation of HA receptors CD44, hyaluronan-mediated motility receptor (HMMR), and layilin (LAYN), although kinetics and strength of expression varied greatly between subjects. The HA-degrading enzymes HYAL1 and HYAL2 were detected at low levels and induced by cell activation in some individuals. Interestingly, expression of HAS3, HA receptors, and hyaluronidases were modulated by the proinflammatory cytokines IL-6 and IL-1bβ in most subjects. To assess the functional role of HA in CD8 T cells, we performed carboxyfluorescein succinimidyl ester (CFSE) based proliferation assays and cytokine analysis in the presence of the HA inhibitor 4- Methylumbelliferone (4-MU). Despite significant inter-individual variation with regard to the effective dose, 4-MU resulted in the inhibition of CD8 T cell proliferation and reduced release of TNF-α and IFN-γ. Collectively, these data demonstrate that human CD8 T cells respond to TCR stimulation with a synthesis of HA and expression of HA-related genes. They further suggest that HA inhibition may be helpful in interfering with pathogenic T cell activation in human disease.

Keywords: CD8 T cells, extracellular matrix, hyaluronan, hyaluronan synthase 3

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Authors: Vidhula Ahire, Amit Kumar, K. P. Mishra, Gauri Kulkarni

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Herbal polyphenols have gained significance because of their increasing promise in prevention and treatment of cancer. Therefore, development of a dietary compound as an effective radiosensitizer and a radioprotector is highly warranted for cervical cancer patients undergoing therapy. This study describes the cytotoxic effects of the flavonoid, ellagic acid (EA) when administered either alone or in combination with gamma radiation on cervical cancer HeLa cells in vitro. Apoptotic index and proliferation were measured by using trypan blue assay. Reproductive cell death was analyzed by clonogenic assay. Propidium iodide staining for flowcytometry was performed to analyze cell cycle modulation. Nuclear and mitochondrial changes were studied with specific dyes. DNA repair kinetics was analyzed by immunofluorescence assay. Evaluation and comparison of EA effects were performed with other clinically used breast cancer drugs. When tumor cells were exposed to 2 and 4 Gy of irradiation in presence of EA (10 μM), it yielded a synergistic cytotoxic effect on cervical cancer cells whereas in NIH3T3 cells it reversed the injury caused by irradiation and abetted in the regaining of normal healthy cells. At 24h ~25foci/cell was observed and 2.6 fold decrease in the mitochondrial membrane potential. Up to 40% cell were arrested in the G1 phase and 20-36% cells exhibited apoptosis. Our results demonstrate the role of increased apoptosis and cell cycle modulation in the mechanism of EA mediated radiosensitization of cervical cancer cells and thus advocating EA as an adjuvant for preclinical trials in cancer chemo- radiotherapy.

Keywords: cervical cancer, ellagic acid, sensitization, radiation therapy

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Authors: Preeti Pal, Anjali Pal

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Chitosan is an effective sorbent for removal of contaminants from wastewater. However, the ability of pure chitosan is specific because of its cationic charge. It causes repulsion in the removal process of various cationic charged molecules. The present study has been carried out for the successful removal of Pb²⁺ ions from aqueous solution by modified chitosan beads. Surface modification of chitosan (CS) beads was performed by using the anionic surfactant (AS), sodium dodecyl sulfate (SDS). Micelle aggregation property of SDS has been utilized for the formation of bilayer over the CS beads to produce surfactant modified chitosan (SMCS) beads. Prepared adsorbents were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) in order to find out their composition and surface morphology. SMCS beads, when compared to the pure CS beads, showed three times higher adsorption. This higher adsorption is believed to be due to the adsolubilization of Pb²⁺ ions on SDS bilayer. This bilayer provides more adsorption sites for quick and effective removal of Pb²⁺ ions from the aqueous phase. Moreover, the kinetic and adsorption isotherm models were employed to the obtained data for the description of the lead adsorption processes. It was found that the removal kinetics follows pseudo-second order model. Adsorption isotherm data fits well to the Langmuir model. The maximum adsorption capacity obtained is 100 mg/g at the dosage of 0.675 g/L for 50 mg/L of Pb²⁺. The adsorption capacity is subject to increase with increasing the Pb²⁺ ions concentration in the solution. The results indicated that the prepared hydrogel beads are efficient adsorbent for removal of Pb²⁺ ions from the aqueous medium.

Keywords: adsolubilisation, anionic surfactant, bilayer, chitosan, Pb²⁺

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Authors: H. Boukhatem, L. Djouadi, H. Khalaf, R. M. Navarro, F. V. Ganzalez

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Synthetic organic dyes are used in various industries, such as textile industry, leather tanning industry, paper production, hair dye production, etc. Wastewaters containing these dyes may be harmful to the environment and living organisms. Therefore, it is very important to remove or degrade these dyes before discharging them into the environment. In addition to standard technologies for the degradation and/or removal of dyes, several new specific technologies, the so-called advanced oxidation processes (AOPs), have been developed to eliminate dangerous compounds from polluted waters. AOPs are all characterized by the same chemical feature: production of radicals (•OH) through a multistep process, although different reaction systems are used. These radicals show little selectivity of attack and are able to oxidize various organic pollutants due to their high oxidative capacity (reduction potential of HO• Eo = 2.8 V). Heterogeneous photocatalysis, as one of the AOPs, could be effective in the oxidation/degradation of organic dyes. A major advantage of using heterogeneous photocatalysis for this purpose is the total mineralization of organic dyes, which results in CO2, H2O and corresponding mineral acids. In this study, nanomaterials based on montmorillonite and CuxCd1-xS with different Cu concentration (0.3 < x < 0.7) were utilized for the degradation of the commercial cationic textile dye Methylene blue (MB), used as a model pollutant. The synthesized nanomaterials were characterized by fourier transform infrared (FTIR) and thermogravimetric-differential thermal analysis (TG–DTA). Test results of photocatalysis of methylene blue under UV-Visible irradiation show that the photoactivity of nanomaterials montmorillonite/ CuxCd1-xS increases with the increasing of Cu concentration. The kinetics of the degradation of the MB dye was described with the Langmuir–Hinshelwood (L–H) kinetic model.

Keywords: heterogeneous photocatalysis, methylene blue, montmorillonite, nanomaterial

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Authors: Geetanjali Yadav, Arpit Mishra, Parthsarathi Ghosh, Ramkrishna Sen

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The world is facing problems of increasing global CO2 emissions, climate change and fuel crisis. Therefore, several renewable and sustainable energy alternatives should be investigated to replace non-renewable fuels in future. Algae presents itself a versatile feedstock for the production of variety of fuels (biodiesel, bioethanol, bio-hydrogen etc.) and high value compounds for food, fodder, cosmetics and pharmaceuticals. Microalgae are simple microorganisms that require water, light, CO2 and nutrients for growth by the process of photosynthesis and can grow in extreme environments, utilize waste gas (flue gas) and waste waters. Mixing, however, is a crucial parameter within the culture system for the uniform distribution of light, nutrients and gaseous exchange in addition to preventing settling/sedimentation, creation of dark zones etc. The overarching goal of the present study is to improve photobioreactor (PBR) design for enhancing dissolution of CO2 from ambient air (0.039%, v/v), pure CO2 and coal-fired flue gas (10 ± 2%) into microalgal PBRs. Computational fluid dynamics (CFD), a state-of-the-art technique has been used to solve partial differential equations with turbulence closure which represents the dynamics of fluid in a photobioreactor. In this paper, the hydrodynamic performance of the PBR has been characterized and compared with that of the conventional bubble column PBR using CFD. Parameters such as flow rate (Q), mean velocity (u), mean turbulent kinetic energy (TKE) were characterized for each experiment that was tested across different aeration schemes. The results showed that the modified PBR design had superior liquid circulation properties and gas-liquid transfer that resulted in creation of uniform environment inside PBR as compared to conventional bubble column PBR. The CFD technique has shown to be promising to successfully design and paves path for a future research in order to develop PBRs which can be commercially available for scale-up microalgal production.

Keywords: computational fluid dynamics, microalgae, bubble column photbioreactor, flue gas, simulation

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Authors: Y. S. Shen, B. H. Liao

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This study aimed to develop the design equation of a laminar-falling-film-slurry (LFFS) type photoreactor for the treatment of organic wastewaters containing isopropyl alcohol (IPA) by VUV-based advanced oxidation processes (AOPs). The photoreactor design equations were established by combining with the chemical kinetics of the photocatalytic system, light absorption model within the photoreactor, and was used to predict the decomposition of IPA in aqueous solutions in the photoreactors of different geometries at various operating conditions (volumetric flow rate, oxidants, catalysts, solution pH values, UV light intensities, and initial concentration of pollutants) to verify its rationality and feasibility. By the treatment of the LFFS-VUV only process, it was found that the decomposition rates of IPA in aqueous solutions increased with the increase of volumetric flow rate, VUV light intensity, dosages of TiO2 and H2O2. The removal efficiencies of IPA by photooxidation processes were in the order: VUV/H2O2>VUV/TiO2/H2O2>VUV/TiO2>VUV only. In VUV, VUV/H2O2, VUV/TiO2/H2O2 processes, integrating with the reaction kinetic equations of IPA, the mass conservation equation and the linear light source model, the photoreactor design equation can reasonably to predict reaction behaviors of IPA at various operating conditions and to describe the concentration distribution profiles of IPA within photoreactors.The results of this research can be useful basis for the future application of the homogeneous and heterogeneous VUV-based advanced oxidation processes.

Keywords: isopropyl alcohol, photoreactor design, VUV, AOPs

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Authors: Amanda C. Q. M. Vieira, Cybelly M. Melo, Camila B. M. Figueirêdo, Giovanna C. R. M. Schver, Salvana P. M. Costa, Magaly A. M. de Lyra, Ping I. Lee, José L. Soares-Sobrinho, Pedro J. Rolim-Neto, Mônica F. R. Soares

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Epiisopiloturine (EPI) is a drug candidate that is extracted from Pilocarpus microphyllus and isolated from the waste of Pilocarpine. EPI has demonstrated promising schistosomicidal, leishmanicide, anti-inflammatory and antinociceptive activities, according to in vitro studies that have been carried out since 2009. However, this molecule shows poor aqueous solubility, which represents a problem for the release of the drug candidate and its absorption by the organism. The purpose of the present study is to investigate the extent of enhancement of kinetic solubility of a solid solution (SS) of EPI in hipromellose phthalate HP-55 (HPMCP), an enteric polymer carrier. SS was obtained by the solvent evaporation methodology, using acetone/methanol (60:40) as solvent system. Both EPI and polymer (drug loading 10%) were dissolved in this solvent until a clear solution was obtained, and then dried in oven at 60ºC during 12 hours, followed by drying in a vacuum oven for 4 h. The results show a considerable modification in the crystalline structure of the drug candidate. For instance, X-ray diffraction (XRD) shows a crystalline behavior for the EPI, which becomes amorphous for the SS. Polarized light microscopy, a more sensitive technique than XRD, also shows completely absence of crystals in SS sample. Differential Scanning Calorimetric (DSC) curves show no signal of EPI melting point in SS curve, indicating, once more, no presence of crystal in this system. Interaction between the drug candidate and the polymer were found in Infrared microscopy, which shows a carbonyl 43.3 cm-1 band shift, indicating a moderate-strong interaction between them, probably one of the reasons to the SS formation. Under sink conditions (pH 6.8), EPI SS had its dissolution performance increased in 2.8 times when compared with the isolated drug candidate. EPI SS sample provided a release of more than 95% of the drug candidate in 15 min, whereas only 45% of EPI (alone) could be dissolved in 15 min and 70% in 90 min. Thus, HPMCP demonstrates to have a good potential to enhance the kinetic solubility profile of EPI. Future studies to evaluate the stability of SS are required to conclude the benefits of this system.

Keywords: epiisopiloturine, hipromellose phthalate HP-55, pharmaceuticaltechnology, solubility

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Authors: Lakshmidevi Rajendran, Bharathidasan Kanniappan, Gopi Raja, Muthukumar Karuppan

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This study investigates the feasibility of fed-batch mixotrophic cultivation of microalgae Scenedesmus sp. in a 3-litre airlift photobioreactor under standard operating conditions. The results of this study suggest the algae species may serve as an excellent feed for aquatic species using organic byproducts. Microalgae Scenedesmus sp., was cultured using a synthetic wastewater by stepwise addition of crude glycerol concentration ranging from 2-10g/l under fed-batch mixotrophic mode for a period of 15 days. The attempts were made with the stepwise addition of crude glycerol as a carbon source in the initial growth phase to evade the inhibitory nature of high glycerol concentration on the growth of Scenedesmus sp. Crude glycerol was chosen since it is readily accessible as byproduct from biodiesel production sectors. Highest biomass concentration was achieved to be 2.43 g/l at the crude glycerol concentration of 6g/l after 10 days which is 3 fold times the increase in the biomass concentration compared with the control medium without the addition of glycerol. Biomass growth data obtained for the microalgae Scenedesmus sp. was fitted well with the modified Logistic equation. Substrate utilization kinetics was also employed to model the biomass productivity with respect to the various crude glycerol concentration. The results indicated that the supplement of crude glycerol to the mixotrophic culture of Scenedesmus sp., enhances the biomass concentration, chlorophyll and lutein productivity. Thus the application of fed-batch mixotrophic cultivation with stepwise addition of crude glycerol to Scenedesmus sp., provides a subtle way to reduce the production cost and improvisation in the large-scale cultivation along with biochemical compound synthesis.

Keywords: airlift photobioreactor, crude glycerol, microalgae Scenedesmus sp., mixotrophic cultivation, lutein production

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Authors: Charalampos N. Bompas, Eleni Poulou-Sidiropoulou, Martina Samiotaki, Alexios Vlamis-Gardikas

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Ιn all living organisms, antioxidant defenses are orchestrated by the thioredoxin (Trx) and glutaredoxin (Grx) systems. The Trx system of Escherichia coli (E. coli) is comprised of Trx1 and Trx2, both reduced by thioredoxin reductase (TrxR). The Grx system consists of four Grxs (Grx1, Grx2, Grx3, and Grx4), all reduced by glutathione (GSH) except for Grx4, which is reduced by TrxR. Under normal conditions, the GSH reductase of the Grx system keeps GSH at its reduced state. NADPH+ provides the electrons for all reductions in the Trx and Grx systems. Although the role of the E. coli Trx system is widely known, the function of the Grx system reflects the main property of Grx1, which is the reduction of ribonucleotide reductase Ia (RRIa). E. coli Grx3 (encoded by grxC) may also reduce RRIa in vitro but with slow kinetics. The molecule may account for up to 0.4% of total soluble protein and has been the subject of extensive structural studies. Its biological function, however, remains unknown. Herein, affinity chromatography with monothiol Grx3 serving as bait was used to detect the interactions of Grx3 with other proteins. Different types of interactions were identified (covalent, weak, and strong non-covalent) that suggested novel functions for Grx3. In silico approaches were employed to validate selected interactions. In addition, total protein extracts from the null mutant for grxC and the wild-type strain were compared. The overall findings suggest that Grx3 is involved in various metabolic processes, protein synthesis, and stress responses, expanding the recognized functions of Grx3 beyond the possible reduction of RRIa.

Keywords: escherichia coli, glutaredoxin 3, interactome, thiol-disulfide oxidoreductase

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Authors: Xiao L Dai, Wen X Wei, Shuo Wang, Jia B Li, Yan Wei

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Heavy oil pollution generated from both natural and anthropogenic sources could cause significant damages to the ecological environment, due to the toxicity of some of its constituents. Nowadays, microbial remediation is becoming a promising technology to treat oil pollution owing to its low cost and prevention of secondary pollution; microorganisms are key players in the process. Compared to the free microorganisms, immobilized microorganisms possess several advantages, including high metabolic activity rates, strong resistance to toxic chemicals and natural competition with the indigenous microorganisms, and effective resistance to washing away (in open water system). Many immobilized microorganisms have been successfully used for bioremediation of heavy oil pollution. Considering the broad choices, low cost, simple process, large specific surface area and less impact on microbial activity, modified zeolite were selected as a bio-carrier for bacteria immobilization. Three strains of heavy oil-degrading bacteria Bacillus sp. DL-13, Brevibacillus sp. DL-1 and Acinetobacter sp. DL-34 were immobilized on the modified zeolite under mild conditions, and the bacterial load (bacteria /modified zeolite) was 1.12 mg/g, 1.11 mg/g, and 1.13 mg/g, respectively. SEM results showed that the bacteria mainly adsorbed on the surface or punctured in the void of modified zeolite. The heavy oil degradation efficiency of immobilized bacteria was 62.96%, higher than that of the free bacteria (59.83%). The heavy oil degradation process of immobilized bacteria accords with the first-order reaction equation, and the reaction rate constant is 0.1483 d⁻¹, which was significantly higher than the free bacteria (0.1123 d⁻¹), suggesting that the immobilized bacteria can rapidly start up the heavy oil degradation and has a high activity of heavy oil degradation. The results suggested that immobilized bacteria are promising technology for bioremediation of oil pollution.

Keywords: heavy oil pollution, microbial remediation, modified zeolite, immobilized bacteria

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Authors: Laroussi Chaabane, Emmanuel Beyou, Amel El Ghali, Mohammed Hassen V. Baouab

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The functionalization of graphene oxide sheets by ethylenediamine (EDA) was accomplished followed by the grafting of bis(2-pyridylmethyl)amino group (BPED) onto the activated graphene oxide sheets in the presence of chloroacetylchloride (CAC) produced the martial [(Go-EDA-CAC)-BPED]. The physic-chemical properties of [(Go-EDA-CAC)-BPED] composites were investigated by Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPs), Scanning electron microscopy (SEM) and Thermogravimetric analysis (TGA). Moreover, [(Go-EDA-CAC)-BPED] was used for removing M(II) (where M=Cu, Ni and Co) ions from aqueous solutions using a batch process. The effect of pH, contact time and temperature were investigated. More importantly, the [(Go-EDA-CAC)-BPED] adsorbent exhibited remarkable performance in capturing heavy metal ions from water. The maximum adsorption capacity values of Cu(II), Ni(II) and Co(II) on the [(GO-EDA-CAC)-BPED] at the pH of 7 is 3.05 mmol.g⁻¹, 3.25 mmol.g⁻¹ and 3.05 mmol.g⁻¹ respectively. To examine the underlying mechanism of the adsorption process, pseudo-first, pseudo-second-order, and intraparticle diffusion models were fitted to experimental kinetic data. Results showed that the pseudo-second-order equation was appropriate to describe the three metal ions adsorption by [(Go-EDA-CAC)-BPED]. Adsorption data were further analyzed by the Langmuir, Freundlich, and Jossensadsorption approaches. Additionally, the adsorption properties of the [(Go-EDA-CAC)-BPED], their reusability (more than 10 cycles) and durability in the aqueous solutions open the path to removal of metal ions (Cu(II), Ni(II) and Co(II) from water solution. Based on the results obtained, we conclude that [(Go-EDA-CAC)-BPED] can be an effective and potential adsorbent for removing metal ions from an aqueous solution.

Keywords: graphene oxide, bis(2-pyridylmethyl)amino, adsorption kinetics, isotherms

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