Search results for: molecular imprinted polymers

Authors: M. Shahzad Kamal, Abdullah S. Sultan, Usamah A. Al-Mubaiyedh, Ibnelwaleed A. Hussein

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Oil recovery from reservoirs using conventional oil recovery techniques like water flooding is less than 20%. Enhanced oil recovery (EOR) techniques are applied to recover additional oil. Surfactant-polymer flooding is a promising EOR technique used to recover residual oil from reservoirs. Water soluble polymers are used to increase the viscosity of displacing fluids. Surfactants increase the capillary number by reducing the interfacial tension between oil and displacing fluid. Hydrolyzed polyacrylamide (HPAM) is widely used in polymer flooding applications due to its low cost and other desirable properties. HPAM works well in low-temperature and low salinity-environment. In the presence of salts HPAM viscosity decrease due to charge screening effect and it can precipitate at high temperatures in the presence of salts. Various strategies have been adopted to extend the application of water soluble polymers to high-temperature high-salinity (HTHS) reservoir. These include addition of monomers to acrylamide chain that can protect it against thermal hydrolysis. In this work, rheological properties of various water soluble polymers were investigated to find out suitable polymer and surfactant-polymer systems for HTHS reservoirs. Polymer concentration ranged from 0.1 to 1 % (w/v). Effect of temperature, salinity and polymer concentration was investigated using both steady shear and dynamic measurements. Acrylamido tertiary butyl sulfonate based copolymer showed better performance under HTHS conditions compared to HPAM. Moreover, thermoviscosifying polymer showed excellent rheological properties and increase in the viscosity was observed with increase temperature. This property is highly desirable for EOR application.

Keywords: rheology, polyacrylamide, salinity, enhanced oil recovery, polymer flooding

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Authors: Ashkan Forootan, Reza Rashedi

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Polyethylene has wide usage areas such as blow molding, pipe, film, cable insulation. However, regardless to its growing applications, it has some constraints such as the limited 70C operating temperature. Polyethylene thermo setting procedure whose molecules are knotted and 3D-molecular-network formed , is developed to conquer the above problem and to raise the applicable temperature of the polymer. This paper reports the cross-linking for two different molecular weight grades of LLDPE by adding 0.5, 1, and 2% of DCP (Dicumyl Peroxide). DCP was chosen for its prevalence among various cross-linking agents. Structural parameters such as molecular weight, melt flow index, comonomer, number of branches,etc. were obtained through the use of relative tests as Gel Permeation Chromatography and Fourier Transform Infra Red spectrometer. After calculating the percentage of gel content, properties of the pure and cross-linked samples were compared by thermal and mechanical analysis with DMTA and FTIR and the effects of cross-linking like viscous and elastic modulus were discussed by using various structural paprameters such as MFI, molecular weight, short chain branches, etc. Studies showed that cross-linked polymer, unlike the pure one, had a solid state with thermal mechanical properties in the range of 110 to 120C and this helped overcome the problem of using polyethylene in temperatures near the melting point.

Keywords: LLDPE, cross-link, structural parameters, DCP, DMTA, GPC

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Authors: Strahinja Z. Kovačević, Lidija R. Jevrić, Sanja O. Podunavac Kuzmanović

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The relationship between antibacterial activity of eighteen different substituted benzimidazole derivatives and their molecular characteristics was studied using chemometric QSAR (Quantitative Structure–Activity Relationships) approach. QSAR analysis has been carried out on inhibitory activity towards Staphylococcus aureus, by using molecular descriptors, as well as minimal inhibitory activity (MIC). Molecular descriptors were calculated from the optimized structures. Principal component analysis (PCA) followed by hierarchical cluster analysis (HCA) and multiple linear regression (MLR) was performed in order to select molecular descriptors that best describe the antibacterial behavior of the compounds investigated, and to determine the similarities between molecules. The HCA grouped the molecules in separated clusters which have the similar inhibitory activity. PCA showed very similar classification of molecules as the HCA, and displayed which descriptors contribute to that classification. MLR equations, that represent MIC as a function of the in silico molecular descriptors were established. The statistical significance of the estimated models was confirmed by standard statistical measures and cross-validation parameters (SD = 0.0816, F = 46.27, R = 0.9791, R2CV = 0.8266, R2adj = 0.9379, PRESS = 0.1116). These parameters indicate the possibility of application of the established chemometric models in prediction of the antibacterial behaviour of studied derivatives and structurally very similar compounds.

Keywords: antibacterial, benzimidazole, molecular descriptors, QSAR

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Authors: Nawel Ouennoughi, Kamel Daoud

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During recent years, new pharmaceutical dosage forms were developed in the research laboratories and which consists of encapsulating one or more active molecules in a polymeric envelope. Several techniques of encapsulation allow obtaining the microparticles or the nanoparticles containing one or several polymers. In the industry, microencapsulation is implemented to fill the following objectives: to ensure protection, the compatibility and the stabilization of an active matter in a formulation, to carry out an adapted working, to improve the presentation of a product, to mask a taste or an odor, to modify and control the profile of release of an active matter to obtain, for example, prolonged or started effect. To this end, we focus ourselves on the encapsulation of the antidiabetic. It is an oral hypoglycemic agent belonging to the second generation of sulfonylurea’s commonly employed in the treatment of type II non-insulin-dependent diabetes in order to improve profile them dissolution. Our choice was made on the technique of encapsulation by complex coacervation with two types of polymers (gelatin and the gum Arabic) which is a physicochemical process. Several parameters were studied at the time of the formulation of the microparticles and the nanoparticles: temperature, pH, ratio of polymers etc. The microparticles and the nanoparticles obtained were characterized by microscopy, laser granulometry, FTIR and UV-visible spectrophotometry. The profile of dissolution obtained for the microparticles showed an improvement of the kinetics of dissolution compared to that obtained for the active ingredient.

Keywords: coacervation, gum Arabic, microencapsulation, gelatin

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Authors: Emad A. Jaffar Al-Mulla

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In this study, a biopolymer-based nanocomposite was successfully prepared through melt blending technique. Two biodegradable polymers, polycaprolactone and starch, environmental friendly and obtained from renewable, easily available raw materials, have been chosen. Fatty hydrazide, synthesized from palm oil, has been used as a surfactant to modify montmorillonite (natural clay) for preparation of polycaprolactone/starch nanocomposite. X-ray diffraction and transmission electron microscopy were used to characterize nanocomposite formation. Compatibility of the blend was improved by adding 3% weight modified clay. Higher biodegradability and thermal stability of nanocomopeite were also observed compared to those of the polycaprolactone/starch blend. This product will solve the problem of plastic waste, especially disposable packaging, and reduce the dependence on petroleum-based polymers and surfactants.

Keywords: polycaprolactone, starch, biodegradable, nanocomposite

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Authors: Alireza Rahimi, Abdolreza Farhadian, Arash Tajik, Elaheh Sadeh, Avni Berisha, Esmaeil Akbari Nezhad

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Although natural polymers have been shown to have some inhibitory properties on sour corrosion, they are not considered very effective green corrosion inhibitors. Accordingly, effective corrosion inhibitors should be developed based on natural resources to mitigate sour corrosion in the oil and gas industry. Here, Arabic gum was employed as an eco-friendly precursor for the synthesis of innovative polyurethanes designed as highly efficient corrosion inhibitors for sour oilfield solutions. A comprehensive assessment, combining experimental and computational analyses, was conducted to evaluate the inhibitory performance of the inhibitor. Electrochemical measurements demonstrated that a concentration of 200 mM of the inhibitor offered substantial protection to mild steel against sour corrosion, yielding inhibition efficiencies of 98% and 95% at 25 ºC and 60 ºC, respectively. Additionally, the presence of the inhibitor led to a smoother steel surface, indicating the adsorption of polyurethane molecules onto the metal surface. X-ray photoelectron spectroscopy results further validated the chemical adsorption of the inhibitor on mild steel surfaces. Scanning Kelvin probe microscopy revealed a shift in the potential distribution of the steel surface towards negative values, indicating inhibitor adsorption and corrosion process inhibition. Molecular dynamic simulation indicated high adsorption energy values for the inhibitor, suggesting its spontaneous adsorption onto the Fe (110) surface. These findings underscore the potential of Arabic gum as a viable resource for the development of polyurethanes under mild conditions, serving as effective corrosion inhibitors for sour solutions.

Keywords: environmental effect, Arabic gum, corrosion inhibitor, sour corrosion, molecular dynamics simulation

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Authors: Adishirin Mammadov

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Polymers and polymer composites play vital roles in diverse industries, including food and beverage packaging, transportation innovations, and medical advancements. However, the advancements in polymer technology bring certain risks, particularly concerning water and soil pollution due to the presence of polymers. The creation of new polymers is a critical aspect of this field. While the primary focus is on improving their physical and chemical properties, ensuring their ecological compatibility is equally important. An advanced method for developing innovative polymer types involves integrating fillers with diverse characteristics, offering advantages such as cost reduction and improved quality indicators. In the conducted research, efforts were made to enhance environmental aspects by employing waste fillers. Specifically, low-density polyethylene (LDPE) was used as the polymer, and waste from cocoon factories was chosen as the filler. Following a process of cleaning, drying, and crushing the filler to specific dimensions, it was incorporated into polyethylene through a mechanical-chemical method under laboratory conditions. The varied rheological properties of the resulting polyethylene compositions examined at temperatures ranging from 145 to 165 degrees Celsius. These compositions demonstrated different rheological properties at various temperature intervals. Achieving homogeneity in the obtained compositions is crucial in the polymers mechanochemical process. Beyond rheological properties, swelling rates in different environments and percentages of mass loss at different temperatures learned using the differential thermal analysis method. The research revealed that, to a certain extent, the physico-chemical properties of polyethylene were not significantly affected by the polymer compositions. This suggests that incorporating cocoon waste enables cost reduction in composite production while positively impacting the environment.

Keywords: polyethylene, polymer, composites, filler, reology

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Authors: W. Soufi, F. Boukli Hacene, S. Ghalem

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Alzheimer's disease (AD) is a neurodegenerative disease that leads to a progressive and permanent deterioration of nerve cells. This disease is progressively accompanied by an intellectual deterioration leading to psychological manifestations and behavioral disorders that lead to a loss of autonomy. It is the most frequent of degenerative dementia. Alzheimer's disease (AD), which affects a growing number of people, has become a major public health problem in a few years. In the context of the study of the mechanisms governing the evolution of AD disease, we have found that natural flavonoids are good acetylcholinesterase inhibitors that reduce the rate of ßA secretion in neurons. This work is to study the inhibition of acetylcholinesterase (AChE) which is an enzyme involved in Alzheimer's disease, by methods of molecular modeling. These results will probably help in the development of an effective therapeutic tool in the fight against the development of Alzheimer's disease. Our goal of the research is to study the inhibition of acetylcholinesterase (AChE) by molecular modeling methods.

Keywords: Alzheimer's disease, acetylcholinesterase, flavonoids, molecular modeling

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Authors: Sophio Kobauri, Tengiz Kantaria, Temur Kantaria, David Tugushi, Nina Kulikova, Ramaz Katsarava

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Nanosized environmentally responsive materials are of special interest for various applications, including targeted drug to a considerable potential for treatment of many human diseases. The important technological advantages of nanoparticles (NPs) usage as drug carriers (nanocontainers) are their high stability, high carrier capacity, feasibility of encapsulation of both hydrophilic or hydrophobic substances, as well as a high variety of possible administration routes, including oral application and inhalation. NPs can also be designed to allow controlled (sustained) drug release from the matrix. These properties of NPs enable improvement of drug bioavailability and might allow drug dosage decrease. The targeted and controlled administration of drugs using NPs might also help to overcome drug resistance, which is one of the major obstacles in the control of epidemics. Various degradable and non-degradable polymers of both natural and synthetic origin have been used for NPs construction. One of the most promising for the design of NPs are amino acid-based biodegradable polymers (AABBPs) which can clear from the body after the fulfillment of their function. The AABBPs are composed of naturally occurring and non-toxic building blocks such as α-amino acids, fatty diols and dicarboxylic acids. The particles designed from these polymers are expected to have an improved bioavailability along with a high biocompatibility. The present work deals with a systematic study of the preparation of NPs by cost-effective polymer deposition/solvent displacement method using AABBPs. The influence of the nature and concentration of surfactants, concentration of organic phase (polymer solution), and the ratio organic phase/inorganic (water) phase, as well as of some other factors on the size of the fabricated NPs have been studied. It was established that depending on the used conditions the NPs size could be tuned within 40-330 nm. As the next step of this research an evaluation of biocompatibility and bioavailability of the synthesized NPs has been performed, using two stable human cell culture lines – HeLa and A549. This part of study is still in progress now.

Keywords: amino acids, biodegradable polymers, nanoparticles (NPs), non-toxic building blocks

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Authors: Athena Nguyen, Rojin Belganeh

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Detecting and identifying differences in like polymer materials are key factors in deformulation, comparative analysis as well as reverse engineering. Pyrolysis-GC/MS is an easy solid sample introduction technique which expands the application areas of gas chromatography and mass spectrometry. The Micro-furnace pyrolyzer is directly interfaced with the GC injector preventing any potential of cold spot, carryover, and cross contamination. This presentation demonstrates the study of two similar polymers by performing different mode of operations in the same system: Evolve gas analysis (EGA), Flash pyrolysis, Thermal desorption analysis, and Heart-cutting analysis. Unknown polymer materials and their chemical compositions are identified.

Keywords: gas chromatography/mass spectrometry, pyrolysis, pyrolyzer, thermal desorption-GC/MS

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Authors: Aliyu Adamu, Fahrul Huyop, Roswanira Abdul Wahab, Mohd Shahir Shamsir

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Halogenated organic compounds occur in huge amount in biosphere. This is attributable to the diverse use of halogen-based compounds in the synthesis of various industrially important products. Halogenated compound is toxic and may persist in the environment, thereby causing serious health and environmental pollution problems. L-2-haloacid dehalogenases (EC 3.8.1.2) catalyse the specific cleavage of carbon-halogen bond in L-isomers of halogenated compounds, which consequently reverse the effects of environmental halogen-associated pollution. To enhance the efficiency and utility of these enzymes, this study investigates the catalytic amino acid residues and the molecular functional mechanism of DehL, by classical molecular dynamic simulations, MM-PBSA and ab initio fragments molecular orbital (FMO) calculations. The results of the study will serve as the basis for the molecular engineering of the enzyme.

Keywords: DehL, Functional mechanism, Catalytic residues, L-2-haloacid dehalogenase

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Authors: Sophio Kobauri, Tengiz Kantaria, Temur Kantaria, David Tugushi, Nina Kulikova, Ramaz Katsarava

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Polymeric disperse systems such as nanoparticles (NPs) are of high interest for numerous applications in contemporary medicine and nanobiotechnology to a considerable potential for treatment of many human diseases. The important technological advantages of NPs usage as drug carriers (nanocontainers) are their high stability, high carrier capacity, feasibility of encapsulation of both hydrophilic or hydrophobic substances, as well as a high variety of possible administration routes, including oral application and inhalation. NPs can also be designed to allow controlled (sustained) drug release from the matrix. These properties of NPs enable improvement of drug bioavailability and might allow drug dosage decrease. The targeted and controlled administration of drugs using NPs might also help to overcome drug resistance, which is one of the major obstacles in the control of epidemics. Various degradable and non-degradable polymers of both natural and synthetic origin have been used for NPs construction. One of the most promising for the design of NPs are amino acid-based biodegradable polymers (AABBPs) which can clear from the body after the fulfillment of their function. The AABBPs are composed of naturally occurring and non-toxic building blocks such as α-amino acids, fatty diols and dicarboxylic acids. The particles designed from these polymers are expected to have an improved bioavailability along with a high biocompatibility. The present work deals with a systematic study of the preparation of NPs by cost-effective polymer deposition/solvent displacement method using AABBPs. The influence of the nature and concentration of surfactants, concentration of organic phase (polymer solution), and the ratio organic phase/inorganic(water) phase, as well as of some other factors on the size of the fabricated NPs have been studied. It was established that depending on the used conditions the NPs size could be tuned within 40-330 nm. At the next step of this research was carried out an evaluation of biocompability and bioavailability of the synthesized NPs using a stable human cell culture line – A549. It was established that the obtained NPs are not only biocompatible but they stimulate the cell growth.

Keywords: amino acids, biodegradable polymers, bioavailability, nanoparticles

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Authors: F. Boukli Hacene, W. Soufi, S. Ghalem

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Glaucoma disease is a progressive degenerative optic neuropathy, with irreversible visual field deficits and high eye pressure being one of the risk factors. Sulfonamides are carbonic anhydrase-II inhibitors that aim to decrease the secretion of aqueous humor by direct inhibition of this enzyme at the level of the ciliary processes. These drugs present undesirable effects that are difficult to accept by the patient. In our study, we are interested in the inhibition of carbonic anhydrase-II by different natural ligands (curcumin analogues) using molecular modeling methods using molecular operating environment (MOE) software to predict their interaction with this enzyme.

Keywords: carbonic anhydrase-II, curcumin analogues, drug research, molecular modeling

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Authors: N. V. Klassen, A. A. Vasin, A. M. Likhter, K. A. Voronin, A. V. Mariasevskaya, I. M. Shmit’ko

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Regular patterning in mixtures of bio-polymers (chitosan and collagen) and nanoparticles in water suspensions has been found by means of optical microscopy. The patterning was created either by external electrical field of moderate amplitude (200–1000 v/cm) or spontaneously. Simultaneously with the patterning pushing out of water drops mixed with nanoparticles to the external regions was observed. These phenomena are explained by interactions of charged bio-polymers and nanoparticles with external and internal electrical fields as well as with the regions of decreased dielectrical permittivity surrounding nano-objects in water which possesses anomalously high dielectrical permittivity. Electrical charges of opposite signs of the nano-objects induce their mutual attraction whereas dipole moments created around these nano-objects by the electrical fields are pushing these particles to the regions with lower fields. Due to this reason, non-homogeneities of dielectrical permittivity around nano-objects immersed into water suspension induces mutual repulsion of the objects. This spatial decrease of this repulsion with the inter-particle distances is more sharp than that of the Coulomb attraction. So, at longer distances, the attractions are stronger whereas at shorter distances the repulsion prevails. At a certain distance these two forces compensate each other creating the equilibrium state of the mixture of nano-objects with opposite charges. When the groups of positive and negative nano-objects consist from identical particles, quasi-periodical pattern of the suspension is observed like mesoscopic two-dimensional super-crystal. These results can clarify the mechanisms of healing of internal organs with direct or alternative electrical fields.

Keywords: bio-polymers, chitosan, collagen, nanoparticles, Coulomb attraction, polarization repulsion, periodical patterning, electrical low frequency resonances

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Authors: Haneef Ur Rehman, Afsheen Aman, Abdul Hameed Baloch, Shah Ali Ul Qader

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Pectinase is a heterogeneous group of enzymes that catalyze the hydrolysis of pectin substances and widely has been used in food and textile industries. In current study, pectinase from B. licheniformis KIBGE-IB21 was immobilized within different polymers (calcium alginate beads, polyacrylamide gel and agar-agar matrix) to enhance its catalytic properties. Polyacrylamide gel was found to be most promising one and gave maximum (89%) immobilization yield. While less immobilization yield was observed in case of calcium alginate beads that only retained 46 % activity. The reaction time for maximum pectinolytic activity was increased from 5.0 to 10 minutes after immobilization. The temperature of pectinase for maximum enzyme activity was increased from 45 °C to 50 °C and 55 °C when it was immobilized within agar-agar and calcium alginate beads, respectively. The optimum pH of pectinase didn’t alter when it was immobilized within polyacrylamide gel and calcium alginate beads, but in case of agar-agar it was changed from pH 10 to pH 9.0. Thermal stability of pectinase was improved after immobilization and immobilized pectinase showed higher toleration against different temperatures as compared to free enzyme. It can be concluded that the entrapment is a simple, single step and promising procedure to immobilized pectinase within different synthetic and non-synthetic polymers and enhanced its catalytic properties.

Keywords: pectinase, characterization immobilization, polyacrylamide, agar-agar, calcium alginate beads

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Authors: Ainoa Guinart, Maria Korpidou, Daniel Doellerer, Cornelia Palivan, Ben L. Feringa

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Stimuli responsive systems arise from the need to meet unsolved needs of current molecular drugs. Our study presents the design of a delivery system with high spatiotemporal control and tuneable release profiles. We study the incorporation of a hydrophobic synthetic molecular motor into PDMS-b-PMOXA block copolymer vesicles to create a self-assembled system. We prove their successful incorporation and selective activation by low powered visible light (λ 430 nm, 6.9 mW). We trigger the release of a fluorescent dye with high release efficiencies over sequential cycles (up to 75%) with the ability to turn on and off the release behaviour on demand by light irradiation. Low concentrations of photo-responsive units are proven to trigger release down to 1 mol% of molecular motor. Finally, we test our system in relevant physiological conditions using a lung cancer cell line and the encapsulation of an approved drug. Similar levels of cell viability are observed compared to the free-given drugshowing the potential of our platform to deliver functional drugs on demand with the same efficiency and lower toxicity.

Keywords: molecular motor, polymer, drug delivery, light-responsive, cancer, selfassembly

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Authors: Kaining Zhang, Lang Chen, Danyang Liu, Jianying Lu, Kun Yang, Junying Wu

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In order to solve the problem of a large amount of simulation and limited simulation scale in the first-principle molecular dynamics simulation of energetic material detonation reaction, we established an artificial intelligence model for analyzing and predicting the detonation reaction mechanism of CL-20 based on the first-principle molecular dynamics simulation of the multiscale shock technique (MSST). We employed principal component analysis to identify the dominant charge features governing molecular reactions. We adopted the K-means clustering algorithm to cluster the reaction paths and screen out the key reactions. We introduced the neural network algorithm to construct the mapping relationship between the charge characteristics of the molecular structure and the key reaction characteristics so as to establish a calculation method for predicting detonation reactions based on the charge characteristics of CL-20 and realize the rapid analysis of the reaction mechanism of energetic materials.

Keywords: energetic material detonation reaction, first-principle molecular dynamics simulation of multiscale shock technique, neural network, CL-20

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Authors: Sukanya Devi Ramachandran, Vaishnavi Muralidharan, Kavya Chandrasekaran

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Polycaprolactone is polymer belonging to the polyester family that has noticeable characteristics of biodegradability and biocompatibility which is essential for medical applications. Polycaprolactone is produced by the ring opening polymerization of the monomer epsilon-Caprolactone (ε-CL) which is a closed ester, comprising of seven-membered ring. This process is normally catalysed by metallic components such as stannous octoate. It is difficult to remove the catalysts after the reaction, and they are also toxic to the human body. An alternate route of using enzymes as catalysts is being employed to reduce the toxicity. Lipase enzyme is a subclass of esterase that can easily attack the ester bonds of ε-CL. This research paper throws light on the extraction of lipase from germinating sunflower seeds and the activity of the biocatalyst in the polymerization of ε-CL. Germinating Sunflower seeds were crushed with fine sand in phosphate buffer of pH 6.5 into a fine paste which was centrifuged at 5000rpm for 10 minutes. The clear solution of the enzyme was tested for activity at various pH ranging from 5 to 7 and temperature ranging from 40oC to 70oC. The enzyme was active at pH6.0 and at 600C temperature. Polymerization of ε-CL was done using toluene as solvent with the catalysis of lipase enzyme, after which chloroform was added to terminate the reaction and was washed in cold methanol to obtain the polymer. The polymerization was done by varying the time from 72 hours to 6 days and tested for the molecular weight and the conversion of the monomer. The molecular weight obtained at 6 days is comparably higher. This method will be very effective, economical and eco-friendly to produce as the enzyme used can be regenerated as such at the end of the reaction and can be reused. The obtained polymers can be used for drug delivery and other medical applications.

Keywords: lipase, monomer, polycaprolactone, polymerization

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Authors: Souhir Abid

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The growing interest in vegetal biomass as an alternative for fossil resources has stimulated the development of numerous classes of monomers. Polymers from renewable resources have attracted an increasing amount of attention over the last two decades, predominantly due to two major reasons (i) firstly environmental concerns, and (ii) secondly the use of monomers from renewable feedstock is a steadily growing field of interest in order to reduce the amount of petroleum consumed in the chemical industry and to open new high-value-added markets to agriculture. Furanic polymers have been considered as alternative environmentally friendly polymers. In our earlier work, modifying furanic polyesters by incorporation of amide functions along their backbone, lead to a particular class of polymer ‘poly(ester-amide)s’, was investigated to combine the excellent mechanical properties of polyamides and the biodegradability of polyesters. As a continuation of our studies on this family of polymer, a series of furanic poly(ester-amide)s bearing sulfonate groups in the main chain were synthesized from 5,5’-Isopropylidene-bis(ethyl 2-furoate), dimethyl 5-sodiosulfoisophthalate, ethylene glycol and hexamethylene diamine by melt polycondensation using zinc acetate as a catalyst. In view of the complexity of the NMR spectrum analysis of the resulting sulfonated poly(ester-amide)s, we found that it is useful to prepare initially the corresponding homopolymers: sulfonated polyesters and polyamides. Structural data of these polymers will be used as a basic element in 1H NMR characterization. The hydrolytic degradation in acidic aqueous conditions (pH = 4,35 ) at 37 °C over the period of four weeks show that the mechanism of the hydrolysis of poly(ester amide)s was elucidated in relation with the microstructure. The strong intermolecular hydrogen bonding interactions between amide functions and water molecules increases the hydrophilicity of the macromolecular chains and consequently their hydrolytic degradation.

Keywords: furan, hydrolytic degradation, polycondensation, poly(ester amide)

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Authors: Abishek Rajkumar

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Antibiotic resistance can occur naturally given the selective pressure placed on antibiotics. Within a large population of bacteria, there is a significant chance that some of those bacteria can develop resistance via mutations or genetic recombination. However, a growing public health concern has arisen over the fact that antibiotic resistance has increased significantly over the past few decades. This is because humans have been over-consuming and producing antibiotics, which has ultimately accelerated the antibiotic resistance seen in these bacteria. The product of all of this is an ongoing race between scientists and the bacteria as bacteria continue to develop resistance, which creates even more demand for an antibiotic that can still terminate the newly resistant strain of bacteria. This paper will focus on a myriad of aspects of antibiotic resistance in bacteria starting with how it occurs on a molecular level and then focusing on the antibiotic concentrations and how they affect the resistance and fitness seen in bacteria.

Keywords: antibiotic, molecular, mutation, resistance

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Authors: Boukli Hacene Faiza, Soufi Wassila, Ghalem Said

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The oral antidiabetics drugs such as alpha glucosidase inhibitors present undesirable effects like acarbose. Flavonoids are class of molecules widely distributed in plants, for this reason we are interested in our work to study the inhibition in silico of alpha glucosidase by natural ligands ( flavonoids analogues) using molecular modeling methods using MOE (Molecular Operating Environment) software to predict their interaction with this enzyme with score energy, ADME /T tests and druglikeness properties experiments. Two flavonoids Beicalein and Apigenin have high binding affinity with alpha glucosidase with lower IC50 supposed potent inhibitors.

Keywords: alpha glucosidase, flavonoides analogues, drug research, molecular modeling

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Authors: Sanja O. Podunavac-Kuzmanović, Strahinja Z. Kovačević, Lidija R. Jevrić

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Prion is a protein substance whose certain form is considered as infectious agent. It is presumed to be the cause of the transmissible spongiform encephalopathies (TSEs). The protein it is composed of, called PrP, can fold in structurally distinct ways. At least one of those 3D structures is transmissible to other prion proteins. Prions can be found in brain tissue of healthy people and have certain biological role. The structure of prions naturally occurring in healthy organisms is marked as PrPc, and the structure of infectious prion is labeled as PrPSc. PrPc may play a role in synaptic plasticity and neuronal development. Also, it may be required for neuronal myelin sheath maintenance, including a role in iron uptake and iron homeostasis. PrPSc can be considered as an environmental pollutant. The main aim of this study was to carry out the molecular modeling and calculation of molecular descriptors (lipophilicity, physico-chemical and topological descriptors) of structurally diverse compounds which can be considered as anti-prion agents. Molecular modeling was conducted applying ChemBio3D Ultra version 12.0 software. The obtained 3D models were subjected to energy minimization using molecular mechanics force field method (MM2). The cutoff for structure optimization was set at a gradient of 0.1 kcal/Åmol. The Austin Model 1 (AM-1) was used for full geometry optimization of all structures. The obtained set of molecular descriptors is applied in analysis of similarities and dissimilarities among the tested compounds. This study is an important step in further development of quantitative structure-activity relationship (QSAR) models, which can be used for prediction of anti-prion activity of newly synthesized compounds.

Keywords: chemometrics, molecular modeling, molecular descriptors, prions, QSAR

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Authors: Tareg M. Elsunaki, Suleiman A. Arafa, Mohamed A. Abd-Alla

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New interesting thermal stable polyesters containing 1-methyl-4-piperidone moiety in the main chain have been synthesized. These polyesters were synthesized by interfacial polycondensation technique of 3,5-bis(4-hydroxybenzylidene)-1-methyl-4-piperidone (I) and 3,5-bis(4-hydroxy-3-methoxy benzyli-dene)-1-methyl-4-piperidone (II) with terphthaloyl, isophthaloyl, 4,4'-diphenic, adipoyl and sebacoyl dichlorides. The yield and the values of the reduced viscosity of the produced polyesters were found to be affected by the type of an organic phase. In order to characterize these polymers, the necessary model compounds (A), (B) were prepared from (I), (II) respectively and benzoyl chloride. The structure of monomers (I), (II), model compounds and resulting polyesters were confirmed by IR, elemental analysis and 1HNMR spectroscopy. The various characteristic of the resulting polymers including solubility, thermal properties, viscosity and X-ray analysis were also studied.

Keywords: synthesis, characterization, new polyesters, chemistry

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Authors: Maryam Rahimi, Maryam Moslehishad, Seyede Marzieh Hosseini

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In this study, preparation of spray dried Carum copticum essential oil (CCEO)-loaded microcapsules by maltodextrin and its blending with two other natural biodegradable polymers, gum Arabic (GA) or modified starch (MS) were investigated. Addition of these polymers to maltodextrin resulted in the encasement of encapsulation efficiency (EE). The highest EE (78.22±0.34%) and total phenolic (TP) content (83.86±1.72 mg GAE/100g) was related to MD-MS microcapsules. CCEO-loaded microcapsules showed spherical surface, good antioxidant and antimicrobial properties. In addition, sensory tests confirmed the possible application of CCEO-loaded microcapsules as natural food additives.

Keywords: carum copticum, essential oil, encapsulation, spray drying, sensory evaluation, antioxidants

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Authors: Pierluigi Tosi, Ed de Jong, Gerard van Klink, Luc Vincent, Alice Mija

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During the last decades renewable and low-cost resources have attracted increasingly interest. Carbohydrates can be derived by lignocellulosic biomasses, which is an attractive option since they represent the most abundant carbon source available in nature. Carbohydrates can be converted in a plethora of industrially relevant compounds, such as 5-hydroxymethylfurfural (HMF) and levulinic acid (LA), within acid catalyzed dehydration of sugars with mineral acids. Unfortunately, these acid catalyzed conversions suffer of the unavoidable formation of highly viscous heterogeneous poly-disperse carbon based materials known as humins. This black colored low value by-product is made by a complex mixture of macromolecules built by covalent random condensations of the several compounds present during the acid catalyzed conversion. Humins molecular structure is still under investigation but seems based on furanic rings network linked by aliphatic chains and decorated by several reactive moieties (ketones, aldehydes, hydroxyls, …). Despite decades of research, currently there is no way to avoid humins formation. The key parameter for enhance the economic viability of carbohydrate conversion processes is, therefore, increasing the economic value of the humins by-product. Herein are presented new humins based polymeric materials that can be prepared starting from the raw by-product by thermal treatment, without any step of purification or pretreatment. Humins foams can be produced with the control of reaction key parameters, obtaining polymeric porous materials with designed porosity, density, thermal and electrical conductivity, chemical and electrical stability, carbon amount and mechanical properties. Physico chemical properties can be enhanced by modifications on the starting raw material or adding different species during the polymerization. A comparisons on the properties of different compositions will be presented, along with tested applications. The authors gratefully acknowledge the European Community for financial support through Marie-Curie H2020-MSCA-ITN-2015 "HUGS" Project.

Keywords: by-product, humins, polymers, valorization

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Authors: Abdulmannan Fadel

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Arabinoxylan is a non-starch polysaccharide (NSP), which is one of the most important polysaccharides contained within cereal grains. Wheat endosperm pentosan and rice bran contain a significant amount of arabinoxylan (7% in rice bran and 10-12% in wheat endosperm pentosan). Several methods have been used for arabinoxylan extraction with varying degrees of success e.g. enzymatic and alkaline treatment. Yet, the use of extrusion alone as a pre-treatment to increase the yield and reduce the molecular weight in wheat endosperm pentosan and rice bran has not been investigated. The samples (wheat pentosan and rice bran) were extruded using a Twin-screw extruder at a range of screw speeds (80 and 160 rpm) and barrel temperatures range (80 to 140°C) with a throughput of 30 Kg hr-1 and moisture content of 25%. Arabinoxylans were extracted with water and the extraction yield and molecular weight was determined using size exclusion high-pressure liquid chromatography system. It was found that increasing screw speed from 80 rpm to 160 rpm, did not effect the extraction yield (p < 0.05) of arabinoxylan from either the wheat endosperm pentosan or the rice bran. However, the molecular weight of the extracted arabinoxylans from pentosan was found to decrease with increasing screw speed in wheat endosperm pentosan. These low molecular weight arabinoxylans have been suggested as immunomodulators.

Keywords: arabinoxylans, extrusion, wheat endosperm pentosan, rice bran

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Authors: A.Cifarelli, L. Boggioni, F. Bertini, L. Magon, M. Pitalieri, S. Losio

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Nowadays, the growing environmental awareness and the dwindling of fossil resources stimulate the polyurethane (PU) industry towards renewable polymers with low carbon footprint to replace the feed stocks from petroleum sources. The main challenge in this field consists in replacing high-performance products from fossil-fuel with novel synthetic polymers derived from 'green monomers'. The bio-polyols from plant oils have attracted significant industrial interest and major attention in scientific research due to their availability and biodegradability. Triglycerides rich in unsaturated fatty acids, such as soybean oil (SBO) and linseed oil (ELO), are particularly interesting because their structures and functionalities are tunable by chemical modification in order to obtain polymeric materials with expected final properties. Unfortunately, their use is still limited for processing or performance problems because a high functionality, as well as OH number of the polyols will result in an increase in cross-linking densities of the resulting PUs. The main aim of this study is to evaluate soy and linseed-based polyols as precursors to prepare prepolymers for the production of polyurethane foams (PUFs) or waterborne-polyurethanes (WPU) used as coatings. An effective reaction route is employed for its simplicity and economic impact. Indeed, bio-polyols were synthesized by a two-step method: epoxidation of the double bonds in vegetable oils and solvent-free ring-opening reaction of the oxirane with organic acids. No organic solvents have been used. Acids with different moieties (aliphatic or aromatics) and different length of hydrocarbon backbones can be used to customize polyols with different functionalities. The ring-opening reaction requires a fine tuning of the experimental conditions (time, temperature, molar ratio of carboxylic acid and epoxy group) to control the acidity value of end-product as well as the amount of residual starting materials. Besides, a Lewis base catalyst is used to favor the ring opening reaction of internal epoxy groups of the epoxidized oil and minimize the formation of cross-linked structures in order to achieve less viscous and more processable polyols with narrower polydispersity indices (molecular weight lower than 2000 g/mol⁻¹). The functionality of optimized polyols is tuned from 2 to 4 per molecule. The obtained polyols are characterized by means of GPC, NMR (¹H, ¹³C) and FT-IR spectroscopy to evaluate molecular masses, molecular mass distributions, microstructures and linkage pathways. Several polyurethane foams have been prepared by prepolymer method blending conventional synthetic polyols with new bio-polyols from soybean and linseed oils without using organic solvents. The compatibility of such bio-polyols with commercial polyols and diisocyanates is demonstrated. The influence of the bio-polyols on the foam morphology (cellular structure, interconnectivity), density, mechanical and thermal properties has been studied. Moreover, bio-based WPUs have been synthesized by well-established processing technology. In this synthesis, a portion of commercial polyols is substituted by the new bio-polyols and the properties of the coatings on leather substrates have been evaluated to determine coating hardness, abrasion resistance, impact resistance, gloss, chemical resistance, flammability, durability, and adhesive strength.

Keywords: bio-polyols, polyurethane foams, solvent free synthesis, waterborne-polyurethanes

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Authors: Hafiz Md. HasanBabu, Khandaker Mohammad Mohi Uddin, Md. IstiakJaman Ami, Rahat Hossain Faisal

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Computing in biomolecular programming performs through the different types of reactions. Proteins and nucleic acids are used to store the information generated by biomolecular programming. DNA (Deoxyribose Nucleic Acid) can be used to build a molecular computing system and operating system for its predictable molecular behavior property. The DNA device has clear advantages over conventional devices when applied to problems that can be divided into separate, non-sequential tasks. The reason is that DNA strands can hold so much data in memory and conduct multiple operations at once, thus solving decomposable problems much faster. Programmable Logic Array, abbreviated as PLA is a programmable device having programmable AND operations and OR operations. In this paper, a DNA PLA is designed by different molecular operations using DNA molecules with the proposed algorithms. The molecular PLA could take advantage of DNA's physical properties to store information and perform calculations. These include extremely dense information storage, enormous parallelism, and extraordinary energy efficiency.

Keywords: biological systems, DNA computing, parallel computing, programmable logic array, PLA, DNA

Procedia PDF Downloads 90

Authors: Nurul Huda Baharuddin, Nik Meriam Nik Sulaiman, Mohammed Kheireddine Aroua

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The effects of pH, polymer concentration, and metal ions feed concentration for four selected heavy metals Zn (II), Pb (II), Cr (III) and Cr (VI) were tested by using Polymer Enhanced Ultrafiltration (PEUF). An alternative biopolymer namely unmodified starch is proposed as a binding reagent in consequences, as compared to commonly used water-soluble polymers namely polyethylene glycol (PEG) and polyethyleneimine (PEI) in the removal of selected four heavy metal ions. The speciation species profiles of four selected complexes ions namely Zn (II), Pb (II), Cr (III) and Cr (VI) and the present of hydroxides ions (OH-) in variously charged ions were investigated by available software at certain pH range. In corresponds to identify the potential of complexation behavior between metal ion-polymers, potentiometric titration studies were obtained at first before carried out experimental works. Experimental works were done using ultrafiltration systems obtained by laboratory ultrafiltration bench scale equipped with 10 kDa polysulfone hollow fiber membrane. Throughout the laboratory works, the rejection coefficient and permeate flux were found to be significantly affected by the main operating parameter, namely the effects of pH, polymer composition and metal ions concentrations. The interaction of complexation between two binding polymers namely unmodified starch and PEG were occurred due to physical attraction of metal ions to the polymer on the molecular surface with high possibility of chemical occurrence. However, these selected metal ions are mainly complexes by polymer functional groups whenever there is interaction with PEI polymer. For study of single metal ions solutions, Zn (II) ions' rejections approaching over 90% were obtained at pH 7 for each tested polymer. This behavior was similar to Pb (II), Cr (III) and Cr (VI); where the rejections were obtained at lower acidic pH and increased at neutral pH of 7. Different behavior was found by Cr (VI) ions where a high rejection was only achieved at acidic pH region with PEI. Polymer concentration and metal ions concentration are found to have a significant effect on rejections. For mixed metal ion solutions, the behavior of metal ion rejections was similar to single metal ion solutions for investigation on the effects of pH. Rejection values were high at pH 7 for Zn (II) pH 7 for Zn (II) and Cr (III) ions, corresponding to higher rejections with unmodified starch. Pb (II) ions obtained high rejections when tested with PEG whenever carried out in mixed metal ion solutions. High Cr (VI) ions' rejection was found with PEI in single and mixed metal ions solutions at neutral pH range. The influence of starch’s granule structure towards the rejections of these four selected metal ions is found to be attracted in a non-ionic manner. No significant effects on permeate flux were obtained when tested at different pH ranges, polymer concentrations and metal ions feed either by single or mixtures metal ions solutions. Canizares Model was employed as the theoretical model to predict permeate flux and metal ions retention on the study of heavy metal ions removal.

Keywords: polyethyleneimine, polyethylene glycol, polymer-enhanced ultrafiltration, unmodified starch

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Authors: Asho Ali

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Tuberculosis is a disease of grave concern which infects one-third of the global population. The high incidence of tuberculosis is further compounded by the increasing emergence of drug resistant strains including multi drug resistant (MDR). Global incidence MDR-TB is ~4%. Molecular epidemiological studies, based on the assumption that patients infected with clustered strains are epidemiologically linked, have helped understand the transmission dynamics of disease. It has also helped to investigate the basis of variation in Mycobacterium tuberculosis (MTB) strains, differences in transmission, and severity of disease or drug resistance mechanisms from across the globe. This has helped in developing strategies for the treatment and prevention of the disease including MDR.

Keywords: Mycobcaterium tuberculosis, molecular epidemiology, drug resistance, disease

Procedia PDF Downloads 366