Excellence in Research and Innovation for Humanity

International Science Index

Commenced in January 1999 Frequency: Monthly Edition: International Abstract Count: 46013

Chemical and Molecular Engineering

Acid-Responsive Polymer Conjugates as a New Generation of Corrosion Protecting Materials
Protection of metals is a critical issue in industry. The annual cost of corrosion in the world is estimated to be about 2.5 trillion dollars and continuously increases. Therefore, there is a need for developing novel protection approaches to improve corrosion protection. We designed and synthesized smart polymer/corrosion inhibitor conjugates as new generations of corrosion protecting materials. Firstly, a polymerizable acrylate derivative of 8-hydroxyquinoline (8HQ), an effective corrosion inhibitor, containing acid-labile β-thiopropionate linkage was prepared in three steps. Then, it was copolymerized with ethyl acrylate in the presence of 1,1′-azobis(cyclohexanecarbonitrile) (ABCN) by radical polymerization. Nanoparticles with an average diameter of 140 nm were prepared from the polymer conjugate by the miniemulsion-solvent evaporation process. The release behavior of 8HQ from the the nanoparticles was studied in acidic (pH 3.5) and neutral media (pH 7.0). The release profile showed a faster release of 8HQ in acidic medium in comparison with neutral medium. Indeed 100% of 8HQ was released after 14 days in acidic medium whereas only around 15% of 8HQ was released during the same period at neutral pH. Therefore, the polymer conjugate nanoparticles are suitable materials as additives or to form coatings on metal substrates for corrosion protection.
Preparation of Polyethersulfone/Graphene Oxide Microcellular Foam by Using Supercritical CO₂
Cell size and cell density heavily influence the properties of polymeric foams and are therefore important to control. By using nanoparticles in polymers and supercritical fluids as foaming agent, it is possible to create microcellular foams with a controlled morphology. In this study, graphene oxide (GO) was synthesized through the oxidization of graphite, and was characterized by XRD and FTIR techniques to confirm the chemical structure of the synthesized GO. Consequently, GO was used as nanoparticle to prepare a polyethersulfone (PES) nanocomposite. Moreover, dry ice was used as the source of supercritical CO₂ in foam production. Microcellular foams were prepared from PES/GO nanocomposites, and scanning electron microscopy (SEM) was used to study cell morphology and the effect that the GO particles had on the morphology of the foams.
Stripping of Flavour-Active Compounds from Aqueous Food Streams: Effect of Liquid Matrix on Vapour-Liquid Equilibrium in a Beer-like Solution
In brewing industries, stripping is a downstream process to separate volatiles from beer. Due to physiochemical similarities between flavour components, the selectivity of this method is not favourable. Besides, the presence of non-volatile compounds such as proteins and carbohydrates may affect the separation of flavours due to their retaining properties. By using a stripping column with structured packing coupled with a gas chromatography, in this work, the overall mass transfer coefficient along with their corresponding equilibrium data was investigated for a model solution consist of water, ethanol, ethyl acetate and isoamyl acetate. Static headspace analysis also was employed to derive equilibrium data for flavours in the presence of beer dry matter. As it was expected ethanol and dry matter showed retention properties; however, the effect of viscosity in mass transfer coefficient was discarded due to the fact that the viscosity of solution decreased during stripping. The effect of ethanol and beer dry matter were mapped to be used for designing stripping could.
Manganese Imidazole Complexes: Electrocatalytic Hydrogen Production
Hydrogen is one of the most abundant elements present on earth’s crust and considered to be the simplest element in existence. It is not found naturally as a gas on earth and thus has to be manufactured. Hydrogen can be produced from a variety of sources, i.e., water, fossil fuels, or biomass and it is a byproduct of many chemical processes. It is also considered as a secondary source of energy commonly referred to as an energy carrier. Though hydrogen is not widely used as a fuel, it still has the potential for greater use in the future as a clean and renewable source of energy. Electrocatalysis is one of the important source for the production of hydrogen which could contribute to this prominent challenge. Metals such as platinum and palladium are considered efficient for hydrogen production but with limited applications. As a result, a wide variety of metal complexes with earth abundant elements and varied ligand environments have been explored for the electrochemical production of hydrogen. In nature, [FeFe] hydrogenase enzyme present in DesulfoVibrio desulfuricans and Clostridium pasteurianum catalyses the reversible interconversion of protons and electrons into dihydrogen. Since the first structure for the enzyme was reported in 1990s, a range of iron complexes has been synthesized as structural and functional mimics of the enzyme active site. Mn is one of the most desirable element for sustainable catalytic transformations, immediately behind Fe and Ti. Only limited number manganese complexes have been reported in the last two decades as catalysts for proton reduction. Furthermore, redox reactions could be carried out in a facile manner, due to the capability of manganese complexes to be stable at different oxidation states. Herein are reported, four µ2-thiolate bridged manganese complexes [Mn₂(CO)₆(μ-S₂N₄C₁₄H₁₀)] 1, [Mn₂(CO)7(μ- S₂N₄C₁₄H₁₀)] 2, Mn₂(CO)₆(μ-S₄N₂C₁₄H₁₀)] 3 and [Mn₂(CO)(μ- S₄N₂C₁₄H₁₀)] 4 have been synthesized and characterized. The cyclic voltammograms of the complexes displayed irreversible reduction peaks in the range - 0.9 to -1.3 V (vs. Fc⁺/Fc in acetonitrile at 0.1 Vs⁻¹). The complexes were catalytically active towards proton reduction in the presence of trifluoroacetic acid as seen from electrochemical investigations.
Poly (Hydroxyurethanes): Environmentally Benign Adhesive Materials
The environmentally friendly synthetic methods that conform to the principles of green chemistry have been paid much attention for years. It is commonly agreed that 'chemical products should be designed to effect their desired function while minimizing their toxicity.' A field the principle can be applied to is polyurethane chemistry. In order to avoid the use of carcinogenic and mutagenic isocyanates and toxic phosgene in their synthesis, the non-isocyanate polyurethanes are considered ‘the green solution’ for industry. They contain primary and secondary hydroxyls that are able to form strong intra- and intermolecular hydrogen bonds that contribute to mechanical properties of a polymer. In the present work, a series of poly(hydroxyurethanes) was synthesized via polyaddition of diglycerol carbonate to diamines bearing C2-C12 carbon chains or m-xylylenediamine moiety. Their structures were confirmed by FTIR spectroscopy. The obtained poly(hydroxyurethanes) exhibited thermoplastic character and were examined as hot-melt adhesives. Rheological experiments showed that the carbon chain structure affected the flow curves. The viscosities varied from 100 mPa•s to 2400 mPa•s at 120°C. The investigated poly(hydroxyurethanes) in form of 0.5-mm thick film were used in bonding of solid beech wood specimens prepared according to EN 205 European standard. Experiments revealed bondline tensile shear strength ranging from 1.5 to 7.9 MPa, respectively, for butyl and m-xylylene repeating units. The adhesives were also applied for veneering of particleboard with a commercial PVC veneer. The non-isocyanate polyurethanes were shown to have sufficient strengths for this purpose (0.8–1.3 MPa in pull-off test). The results proved that poly(hydroxyurethanes) might be considered as an environmentally friendly alternative to traditional polyurethanes and are likely to become significant adhesive materials in the future. However, tuning of their structure and properties is still a challenge.
Selective Separation of Flavour Active Compounds from Aqueous Food Streams: Experimental Investigation of Frictional Diffusion (FricDif) Concept for Beer-like Solution
Control over the concentration of flavours in beverages offers opportunities in not only improving consumers’ experience, through off-flavour removal, but also introducing new products by adjusting on-flavours. Stripping is used as a downstream process to control flavour active compounds in brewing industries. However, due to physiochemical similarities, targeting single component to be separated is almost unfeasible and effluent gas from stripping column always carries a spectrum of components with similar characteristics. For instance, separation of methional as an off-flavour result in loss of isoamyl acetate which is so called on-flavour. In the current processes, stripped phase from stripping column is condensed and undergoes further separation step(s), such as adsorption, to recover the lost flavours. In this work, we investigated the possibility of compound separation before condensation stage. Considering loss of volatile compounds in beer during stripping process, the partial pressure of components in the gas phase; however, will not be equal because of the simple fact that their concentrations in the liquid phase are different. This creates higher driving force and consequently higher diffusivity in free gas space for some species. Bringing this gas mixture into contact with a pure gas, such as CO2, through porous medium results a net flux of transfer of flavour from upstream to downstream in different velocity. In this system, if we impose a reverse convective flow, through slightly elevated pressure on downstream, transfer of species with low mass transfer velocity theoretically stops except the one with higher velocity. This is the basic principle of Frictional Diffusion method briefly named FricDiff. This concept has been applied along with Maxwell-Stefan theory to examine this method for a beer-like solution consists of ethanol, water, ethyl acetate, isoamyl alcohol and isoamyl acetate. This model showed that in a hydrophobic membrane with 1-micrometer pore size and 1-millimeter thickness, there is a pressure window where we can remove all volatiles while retaining isoamyl acetate. This was examined through a gas membrane module and experimental results proved the feasibility of the concept.
Ultrasound Assisted Cooling Crystallization of Lactose Monohydrate
A-lactose monohydrate is widely used in the pharmaceutical industries as an inactive substance that acts as a vehicle or a medium for a drug or other active substance. It is a byproduct of dairy industries, and the recovery of lactose from whey not only boosts the improvement of economics of whey utilization but also causes a reduction in pollution as lactose recovery can reduce the biological oxygen demand (BOD) of whey by more than 80%. In the present study, effect of process parameters such as initial lactose concentration (30-50 % w/w), sonication amplitude (20-40%), sonication time (2-6 hours), and crystallization temperature (10-20 °C) were studied for the recovery of lactose in ultrasound assisted cooling crystallization. In comparison with cooling crystallization, the use of ultrasound enhanced the lactose recovery by 39.17% (w/w). The parameters were optimized for the lactose recovery using Taguchi Method. The optimum conditions found were initial lactose concentration at level 3 (50% w/w), amplitude of sonication at level 2 (40%), the sonication time at level 3 (6 hours), and crystallization temperature at level 1 (10 °C). The maximum recovery was found to be 85.85% at the optimum conditions. Sonication time and the initial lactose concentration were found to be significant parameters for the lactose recovery.
Poly(acrylamide-co-itaconic acid) Nanocomposite Hydrogels and Its Use in the Removal of Lead in Aqueous Solution
Lead (Pb²⁺), a cation, is a prime constituent of the majority of the industrial effluents such as mining, smelting and coal combustion, Pb-based painting and Pb containing pipes in water supply systems, paper and pulp refineries, printing, paints and pigments, explosive manufacturing, storage batteries, alloy and steel industries. The maximum permissible limit of lead in the water used for drinking and domesticating purpose is 0.01 mg/L as advised by Bureau of Indian Standards, BIS. This becomes the acceptable 'safe' level of lead(II) ions in water beyond which, the water becomes unfit for human use and consumption, and is potential enough to lead health problems and epidemics leading to kidney failure, neuronal disorders, and reproductive infertility. Superabsorbent hydrogels are loosely crosslinked hydrophilic polymers that in contact with aqueous solution can easily water and swell to several times to their initial volume without dissolving in aqueous medium. Superabsorbents are kind of hydrogels capable to swell and absorb a large amount of water in their three-dimensional networks. While the shapes of hydrogels do not change extensively during swelling, because of tremendously swelling capacity of superabsorbent, their shape will broadly change.Because of their superb response to changing environmental conditions including temperature pH, and solvent composition, superabsorbents have been attracting in numerous industrial applications. For instance, water retention property and subsequently. Natural-based superabsorbent hydrogels have attracted much attention in medical pharmaceutical, baby diapers, agriculture, and horticulture because of their non-toxicity, biocompatibility, and biodegradability. Novel superabsorbent hydrogel nanocomposites were prepared by graft copolymerization of acrylamide and itaconic acid in the presence of nanoclay (laponite), using methylene bisacrylamide (MBA) and potassium persulfate, former as a crosslinking agent and the second as an initiator. The superabsorbent hydrogel nanocomposites structure was characterized by FTIR spectroscopy, SEM and TGA Spectroscopy adsorption of metal ions on poly (AAm-co-IA). The equilibrium swelling values of copolymer was determined by gravimetric method. During the adsorption of metal ions on polymer, residual metal ion concentration in the solution and the solution pH were measured. The effects of the clay content of the hydrogel on its metal ions uptake behavior were studied. The NC hydrogels may be considered as a good candidate for environmental applications to retain more water and to remove heavy metals.
Volumetric Properties of Binary Mixtures of Glycerol +1-Butanol or +2-Butanol at Several Temperatures
Densities of glycerol + 1-butanol or 2-butanol mixtures were measured over the temperature range 293.15 to 303.15 K at atmospheric pressure, over the entire composition range, with a vibrating tube densimeter. Excess molar volumes, apparent and partial molar volumes of glycerol and butanol, thermal isobaric expansivities of the mixture and partial molar expansivities of the components were calculated. The excess molar volumes of the mixtures are negative at all temperatures, and deviations from ideality increase with increasing temperature. Excess molar volumes were fitted to the Redlich–Kister equation. Partial molar volumes of glycerol decrease with increasing butanol concentration.
Li Salt Rich Separator for Li-Ion Batteries
The objective of this study is to quantify the impact (benefits and drawbacks) of a specific coated film on a conventional polyolefin separator. The coated film is based on a PVdF based layer containing lithium salt in judicious concentration. After having developed a protocol for elaborating Li salt rich polymeric solution, some characterization were performed. The electrical behavior in cycling of coated separators shows that no negative effect is observed compared to the neat separator. At last trials with pilot coating machines were performed to demonstrate the feasibility of coating a separator at industrial level. Whatever the coating technologies used, the process appear promising but requires improvements.
Thiourea Modified Cadmium Sulfide Film for Solar Cell Application
Cadmium sulfide (Cds) thin films were chemically deposited at room temperature, from aqueous ammonia solution using CdCl₂ (Cadmium chloride) as a Cd²⁺ and CS(NH₂)₂ (Thiourea) as S² ion sources. ‘as-deposited’ films were uniform, well adherent to the glass substrate, secularly reflective and yellowish in color. The ‘as-deposited ’Cds layers grew with nano-crystalline in nature and exhibit cubic structure, with blue-shift in optical band gap. The films were annealed in air atmosphere for two hours at different temperatures and further characterized for compositional, structural, morphological and optical properties. The XRD and SEM studies clearly revealed the systematic changes in morphological and structural form of Cds films with an improvement in the crystal quality. The annealed films showed ‘red-shift’ in the optical spectra after thermal treatment. The Thiourea modified CdS film could be good to provide solar cell application.
Investigate the Influence of Gas Sparger Design on the Hydrodynamics of Bubble Column in Bubbly Flow
Bubble column has been used in many application due to easy construction, low cost, and high rate of mass, and heat transfer. Experiments were conducted to investigate the effect of gas sparger type on the hydrodynamics of the bubble column (0.094 m in diameter and 1 m in height) at superficial gas velocity 0.48, 0.96, 1.44, 2.4, and 4.8 cm/s (homogenous flow). Three sparger type were used (perforated plate sparger, cross sparger, and ring sparger). Measurements of the local gas holdup, gas-liquid interfacial area, and mean bubble chord length were conducted by using a fiber optical probe. Radial and axial profile of these parameters at (r/R: 0, ± 0.575, and ± 0.787) and at (x/H: 0.2, 0.3, and 0.5) respectively. It was observed that gas holdup, interfacial area, and chord length depend on superficial gas velocity in linear relation. Perforated plate sparger was the best type that gave the high value of gas holdup and interfacial area as well as broad distribution of mean chord length at all range of the gas velocity. This work results of are of clear interest in better understand the effect of sparger type on bubble column hydrodynamics.
Cadmium Separation from Aqueous Solutions by Natural Biosorbents
Removal of metal ions from different wastewaters has become important due to their effects on living beings. Cadmium is one of the heavy metals found in different industrial wastewaters. There are many conventional methods available to remove heavy metals from wastewaters like adsorption, membrane separations, precipitation, electrolytic methods, etc. and all of them have their own advantages and disadvantages. The present work deals with the use of natural biosorbents (chitin and chitosan) to separate cadmium ions from aqueous solutions. The adsorption data were fitted with different isotherms and kinetics models. Amongst different adsorption isotherms used to fit the adsorption data, the Freundlich isotherm showed better fits for both the biosorbents. The kinetics data of adsorption of cadmium showed better fit with pseudo-second order model for both the biosorbents. Chitosan, the derivative from chitin, showed better performance than chitin. The separation results are encouraging.
Green Extraction of Patchoulol from Patchouli Leaves Using Ultrasound-Assisted Ionic Liquids
Green extraction techniques are fast paving ways into various industrial sectors due to the stringent governmental regulations leading to the banning of toxic chemicals’ usage and also due to the increasing health/environmental awareness. The present work describes the ionic liquids based sonication method for selectively extracting patchoulol from the leaves of patchouli. 1-Butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF4) and N,N,N,N’,N’,N’-Hexaethyl-butane-1,4-diammonium dibromide (dicationic ionic liquid - DIL) were selected for extraction. Ultrasound assisted ionic liquid extraction was employed considering concentration of ionic liquid (4–8 %, w/w), ultrasound power (50–150 W for [Bmim]BF4 and 20–80 W for DIL), temperature (30–50 oC) and extraction time (30–50 min) as major parameters influencing the yield of patchoulol. Using the Taguchi method, the parameters were optimized and analysis of variance (ANOVA) was performed to find the most influential factor in the selected extraction method. In case of [Bmim]BF4, the optimum conditions were found to be: 4 % (w/w) ionic liquid concentration, 50 W power, 30 oC temperature and extraction time of 30 min. The yield obtained under the optimum conditions was 3.99 mg/g. In case of DIL, the optimum conditions were obtained as 6 % (w/w) ionic liquid concentration, 80 W power, 30 oC temperature and extraction time of 40 min, for which the yield obtained was 4.03 mg/g. Temperature was found to be the most significant factor in both the cases. Extraction time was the insignificant parameter while extracting the product using [Bmim]BF4 and in case of DIL, power was found to be the least significant factor affecting the process. Thus, a green method of recovering patchoulol is proposed.
Rb-Modified Few-Layered Graphene for Gas Sensing Application
In the present investigation, we demonstrated the fabrication of few-layers of graphene sheets with alkali metal i.e. Rb-G using chemical route method. The obtained materials were characterized by means of chemical, structural and electrical techniques, using the ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and 4 points probe, respectively. The XRD studies were carried out to understand the phase of the samples where we found a sharp peak of Rb-G at 26.470. UV-Spectroscopy of Graphene and Rb-modified graphene samples shows the absorption peaks at ~248 nm and ~318 nm respectively. These analyses show that this modified material can be useful for gas sensing applications and to be used in diverse areas.
Adsorbed Probe Molecules on Surface for Analyzing the Properties of Cu/SnO2 Supported Catalysts
The interaction of CO, H2 and LPG with Cu-dosed SnO2 catalysts was studied by means of Fourier transform infrared spectroscopy (FTIR). With increasing Cu loading, pronounced and progressive red shifts of the C–O stretching frequency associated with molecular CO adsorbed on the Cu/SnO2 component were observed. This decrease in n(CO) correlates with enhancement of CO dissociation at higher temperatures on Cu promoted SnO2 catalysts under conditions, where clean Cu is almost ineffective. In the conclusion, the capability of our technique is discussed, and a technique for enhancing the sensitivity in our technique is proposed.
Fe-Doped Graphene Nanoparticles for Gas Sensing Applications
In the present inspection, we indicate the falsification of Fe-doped graphene nanoparticles by modified Hummers method. Structural and physiochemical properties of the resulting pallets were explored with the help of ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD) and scanning electron microscopy (SEM), Photoluminescence spectroscopy (PL) for graphene sample exhibits absorption peaks ~248nm. Pure graphene shows PL peak at 348 nm. After doping of Fe with graphene the PL peak shifted from 348 nm to 332 nm. The oxidation degree, i.e. the relative amount of oxygen functional groups was estimated from the relative intensities of the oxygen related bands (ORB) in the FTIR measurements. These analyses show that this modified material can be useful for gas sensing applications and to be used in diverse areas.
Silica Nanoparticles Exposure Induces Oxidative Stress and Inflammation in Mrc-5 Human Lung Fibroblasts
Silica nanoparticles (SiO₂-NPs) are widely used in consumer products such as paints, plastics, insulation materials, tires, concrete production, as well as in medicine as drug and gene delivery systems and for imaging procedures. Environmental human exposure to them occurs during utilization of these products, in a time-dependent manner, the uptake being by topic and inhalation route especially. SiO₂-NPs enter cells and induce membrane damage, oxidative stress and inflammatory reactions in a concentration dependent manner. In this study, MRC-5 cells (human fetal lung fibroblasts) were exposed to amorphous SiO₂-NPs at a dose of 62.5 μg/ml for 24, 48 and 72 hours. The size distribution of NPs was a lognormal function, in the range 3-14 nm. A time dependent decrease of total reduced glutathione concentration by 36%, 50%, and 78% and an increase of NO level by 62%, 32%, respectively 24% compared to control were noticed. An up-regulation of NF-kB expression by 20%, 50% respectively 10% and of Nrf-2 by 139%, 58% and 16% compared to control after 24, 48 and 72 hours was noticed also. The expression of IL-1β, IL-6, IL-8 and COX-2 were up-regulated in a time-dependent manner. Also, the expression of MMP-2 and MMP-9 were down-regulated after 48 and 72 hours, whereas their activities raised in a time-dependent manner. Exposure of cells to NPs up-regulated the expression of inducible NO synthase,as previously was shown, and probably this is the reason for the increased level of NO, that can react with the thiol groups of reduced glutathione molecules, diminishing its concentration. Nrf2 is a transcription factor translocated in nucleus, under oxidative stress, where downstream gene expression activates in order to modulate the adaptive intracellular response against oxidative stress. The cross-talk between Nrf2 and NF-kB activities regulates the inflammatory processes. The activation of NF-kB could activate up-regulation of IL-1β, IL-6 and IL-8. The increase of COX-2 expression could be correlated with IL-1β one. Also, probably in response to the pro-inflammatory cytokines, MMP-2 and MMP-9 were induced and activated. In conclusion, the exposure of MRC-5 cells to SiO₂-NPs generated inflammation in a time-dependent manner.
Improvement on the Specific Activities of Immobilized Enzymes by Poly (Ethylene Oxide) Surface Modification
Covalent immobilization of enzymes on solid supports is an alternative approach to biocatalysis with the added benefits of simple enzyme removal, improved stability, and adaptability to automation and high-throughput applications. Nevertheless, immobilized enzymes generally suffer from reduced activities compared to their soluble counterparts. One major factor leading to activity loss is the intrinsic hydrophobic property of the supporting material surface, which could result in the conformational change/confinement of enzymes. We report a strategy of utilizing flexible poly (ethylene oxide) (PEO) moieties as to improve the surface hydrophilicity of solid supports used for enzyme immobilization. DNA modifying enzymes were covalently conjugated to PEO-coated magnetic-beads. Kinetics studies proved that the activities of the covalently-immobilized DNA modifying enzymes were greatly enhanced by the PEO modification on the bead surface.
Kinetic and Mechanistic Study on the Degradation of Typical Pharmaceutical and Personal Care Products in Water by Using Carbon Nanodots/C₃N₄ Composite and Ultrasonic Irradiation
PPCPs (pharmaceutical and personal care products) in water, as an environmental pollutant, becomes an issue of increasing concern. Therefore, the techniques for degradation of PPCPs has been a hotspot in water pollution control field. Since there are several disadvantages for common degradation techniques of PPCPs, such as low degradation efficiency for certain PPCPs (ibuprofen and Carbamazepine) this proposal will adopt a combined technique by using CDs (carbon nanodots)/C₃N₄ composite and ultrasonic irradiation to mitigate or overcome these shortages. There is a significant scientific problem that the mechanism including PPCPs, major reactants, and interfacial active sites is not clear yet in the study of PPCPs degradation. This work aims to solve this problem by using both theoretical and experimental methodologies. Firstly, optimized parameters will be obtained by evaluating the kinetics and oxidation efficiency under different conditions. The competition between H₂O₂ and PPCPs with HO• will be elucidated, after which the degradation mechanism of PPCPs by the synergy of CDs/C₃N₄ composite and ultrasonic irradiation will be proposed. Finally, a sonolysis-adsorption-catalysis coupling mechanism will be established which is the theoretical basis and technical support for developing new efficient degradation techniques for PPCPs in the future.
Extraction of Natural Colorant from the Flowers of Flame of Forest Using Ultrasound
An impetus towards green consumerism and implementation of sustainable techniques, consumption of natural products and utilization of environment-friendly techniques have gained accelerated acceptance. Butein, a natural colorant, has many medicinal properties apart from its use in dyeing industries. Extraction of butein from the flowers of flame of forest was carried out using ultrasonication bath. Solid loading (2 – 6 g), extraction time (30 – 50 min), volume of solvent (30 – 50 mL) and types of solvent (methanol, ethanol, and water) have been studied to maximize the yield of butein using the Taguchi method. The highest yield of butein 4.67 % (w/w) was obtained using 4 g of plant material, 40 min of extraction time and 30 mL volume of methanol as a solvent. The present method provided a greater reduction in extraction time compared to the conventional method of extraction. Hence, the outcome of the present investigation could further be utilized to develop the method at a higher scale.
Influence of Strong Optical Feedback on Frequency Chirp and Lineshape Broadening in High-Speed Semiconductor Laser
Directly-modulated semiconductor lasers, including edge-emitting and vertical-cavity surface-emitting lasers, have received considerable interest recently for use in data transmitters in cost-effective high-speed data centers, metro, and access networks. Optical feedback has been proved as an efficient technique to boost the modulation bandwidth and enhance the speed of the semiconductor laser. However, both the laser linewidth and frequency chirping in directly-modulated lasers are sensitive to both intensity modulation and optical feedback. These effects along width fiber dispersion affect the transmission bit rate and distance in single-mode fiber links. In this work, we continue our recent research on directly-modulated semiconductor lasers with modulation bandwidth in the millimeter-wave band by introducing simultaneous modeling and simulations on both the frequency chirping and lineshape broadening. The lasers are operating under strong optical feedback. The model takes into account the multiple reflections of laser reflections of laser radiation in the external cavity. The analyses are given in terms of the chirp-to-modulated power ratio, and the results are shown for the possible dynamic states of continuous wave, period-1 oscillation, and chaos.
Reactive Blending of Thermoplastic Starch, Ethylene-1-Butene Rubber, and Chitosan
Thermoplastic starch (TPS) was prepared by melt-blending of cassava starch with glycerol (70/30 wt%/wt%) at 130 ◦C for 10 min. Chitosan (CTS) was used as a compatibilizer. TPS/CTS blend was melt-blended with maleic anhydride grafted ethylene-1-butene rubber (EB-MAH) in the composition of 80/20 respectively. Addition of CTS in TPS/EB-MAH blend decreased particles size of EB-MAH rubber to 1µm in TPS matrix. Mechanical properties, solubility, swelling property, morphology, and water contact angle of TPS/EB-MAH blend were improved by CTS incorporation. FTIR confirmed a reaction had occurred between amino groups (-NH2) of CTS and the MAH groups of EB-MAH. This reaction and the enhanced miscibility between TPS and CTS improved morphology and properties of the TPS/EB-MAH/CTS blend.
The Synthesis and Characterization of Highly Soluble Perylene Dyes for Digital Textile Printing
Digital textile printing (DTP) is a process of printing a pattern or image directly designed on a fabric by using an ink-jet injection method. The inks for DTP can be classified into a water-soluble ink and a solvent ink depending on the kinds of fibers used. Digital textile printing has many advantages as follows; firstly, it shortens the whole process time due to the elimination of screen plate manufacturing process. Secondly, it is an eco-friendly textile printing process that can reduce the environmental pollution such as waste-water. Finally, it is ideal for short runs, customized designs, and one of a kind prints. In this study, three scarlet acid dyes were designed and synthesized which have high color strength and color purity. The suitable ink formulation recipes were also studied in order to apply the synthesized dyes for high-speed DTP. The three scarlet acid dyes were modified from perylene precursors, respectively. The perylene dyes have high tinctorial strength and superior light/heat stability. In order to improve the low water solubility of perylene dyes, sulfonic acid groups were introduced at the bay positions of perylene moiety. In addition, the different functional groups were introduced at the terminal positions of the perylene moiety for improving the light fastness and the optical properties of the dyes. Consequently, the prepared scarlet inks with perylene dyes were successfully applied for DTP.
An Inorganic Nanofiber/Polymeric Microfiber Network Membrane for High-Performance Oil/Water Separation
It has been highly desired to develop a high-performance membrane for separating oil/water emulsions with the combined features of high water flux, high oil separation efficiency, and high mechanical stability. Here, we demonstrated a design for high-performance membranes constructed with ultra-long titanate nanofibers (over 30 µm in length)/cellulose microfibers. An integrated network membrane was achieved with these ultra-long nano/microfibers, contrast to the non-integrated membrane constructed with carbon nanotubes (5 µm in length)/cellulose microfibers. The morphological properties of the prepared membranes were characterized by A FEI Quanta 400 (Hillsboro, OR, United States) environmental scanning electron microscope (ESEM). The hydrophilicity, underwater oleophobicity and oil adhesion property of the membranes were examined using an advanced goniometer (Rame-hart model 500, Succasunna, NJ, USA). More specifically, the hydrophilicity of membranes was investigated by analyzing the spreading process of water into membranes. A filtration device (Nalgene 300-4050, Rochester, NY, USA) with an effective membrane area of 11.3 cm² was used for evaluating the separation properties of the fabricated membranes. The prepared oil-in-water emulsions were poured into the filtration device. The separation process was driven under vacuum with a constant pressure of 5 kPa. The filtrate was collected, and the oil content in water was detected by a Shimadzu total organic carbon (TOC) analyzer (Nakagyo-ku, Kyoto, Japan) to examine the separation efficiency. Water flux (J) of the membrane was calculated by measuring the time needed to collect some volume of permeate. This network membrane demonstrated good mechanical flexibility and robustness, which are critical for practical applications. This network membrane also showed high separation efficiency (99.9%) for oil/water emulsions with oil droplet size down to 3 µm, and meanwhile, has high water permeation flux (6.8 × 10³ L m⁻² h⁻¹ bar⁻¹) at low operation pressure. The high water flux is attributed to the interconnected scaffold-like structure throughout the whole membrane, while the high oil separation efficiency is attributed to the nanofiber-made nanoporous selective layer. Moreover, the economic materials and low-cost fabrication process of this membrane indicate its great potential for large-scale industrial applications.
Magnetodielectric Studies of Substituted La₂NiMnO₆ Double Perovskites
The La₂NiMnO₆ has been extensively studied for its ferromagnetic and magneto-dielectric properties. The La₂NiMnO₆ double perovskite is modified by partial substitution at B site by Fe transition metal. The La₂Ni₁₋ₓFeₓMnO₆ powder samples were synthesized by hydroxide co-precipitation method. The precipitate was dried and fine griended to form powder and pellet samples (2cm dia.) using hydraulic press. The powder and pellet samples of La₂Ni₁₋ₓFeₓMnO₆ were calcined at high temperature 1200°C to form a pure and stable composition. The nano polar regions (NPR) around Ni²⁺ or Mn⁴⁺ ions due to the cationic antisite disorder gives dielectric relaxation through their mutual interaction. The magneto-dielectric behavior is observed in substituted La₂NiMnO₆ shows Maxwell-Wagner and Debye relaxation due to grain boundary, interface and antisite defects. The magneto-dielectric properties of substituted La₂NiMnO₆ pellet sample were probed by Impedance spectroscopy measurements. The structural and magnetic investigations were also carried out by XRD, FESEM and VSM measurements of substituted La₂NiMnO₆ of powder samples. The synthesized La₂Ni₁₋ₓFeₓMnO₆ powder samples are polycrystalline and ferromagnetic in nature. The La₂Ni₁₋ₓFeₓMnO₆ samples exhibit ferromagnetic disorder with transition temperature near room temperature.
Influence of Deposition Temperature on Supercapacitive Properties of Reduced Graphene Oxide on Carbon Cloth: New Generation of Wearable Energy Storage Electrode Material
Flexible electrode material with high surface area and good electrochemical properties is the current trend captivating the researchers across globe for application in the next generation energy storage field. In the present work, crumpled sheet like reduced graphene oxide grown on carbon cloth by the hydrothermal method with a series of different deposition temperatures at fixed time. The influence of the deposition temperature on the structural, morphological, optical and supercapacitive properties of the electrode material was investigated by XRD, RAMAN, XPS, TEM, FE-SEM, UV-VISIBLE and electrochemical characterization techniques.The results show that the hydrothermally synthesized reduced graphene oxide on carbon cloth has sheet like mesoporous structure. The reduced graphene oxide material at 160°C exhibits the best supercapacitor performance, with a specific capacitance of 443 F/g at scan rate 5mV/sec. Moreover, stability studies show 97% capacitance retention over 1000 CV cycles. This result shows that hydrothermally synthesized RGO on carbon cloth is the potential electrode material and would be used in the next-generation wearable energy storage systems. The detailed analysis and results will be presented at the conference.
Synthesis, Characterization and Gas Sensing Applications of Perovskite CaZrO3 Nanoparticles
Calcium Zirconate (CaZrO3) has high protonic conductivities at elevated temperature in water or hydrogen atmosphere. Undoped calcium zirconate acts as a p-type semiconductor in air. In this paper, we reported synthesis of CaZrO3 nanoparticles via modified molecular precursor method. The precursor calcium zirconium oxalate (CZO) was synthesized by exchange reaction between freshly generated aqueous solution of sodium zirconyl oxalate and calcium acetate at room temperature. The controlled pyrolysis of CZO in air at 700°C for one hour resulted in the formation nanocrystalline CaZrO3 powder. CaZrO3 obtained by the present method was characterized by Simultaneous thermogravimetry and differential thermogravimetry (TG-DTA), X-ray diffraction (XRD), infra-red spectroscopy and transmission electron microscopy (TEM). The pellets of synthesized CaZrO3 fabricated, sintered at 1000°C for 5 hr and tested as sensors for NO2 and NH3 gases.
Synthesis and Characterization of CaZrTi2O7 from Tartrate Precursor Employing Microwave Heating Technique
Zirconolite (CaZrTi2O7) is one of the three major phases in the synthetic ceramic 'SYNROC' which is used for immobilization of high-level nuclear waste and also acts as photocatalytic and photophysical properties. In the present work the nanocrystalline CaZrTi2O7 was synthesized from Calcium Zirconyl Titanate tartrate precursor (CZTT) employing two different heating techniques such as Conventional heating (Muffle furnace) and Microwave heating (Microwave Oven). Thermal decomposition of the CZTT precursors in air yielded nanocrystalline CaZrTi2O7 powder as the end product. The products obtained by annealing the CZTT precursor using both heating method were characterized using simultaneous TG-DTA, FTIR, XRD, SEM, TEM, NTA and thermodilatometric study. The physical characteristics such as crystallinity, morphology and particle size of the product obtained by heating the CZTT precursor at the different temperatures in a Muffle furnace and Microwave oven were found to be significantly different. The microwave heating technique considerably lowered the synthesis temperature of CaZrTi2O7. The influence of microwave heating was more pronounced as compared to Muffle furnace heating. The details of the synthesis of CaZrTi2O7 from CZTT precursor are discussed.
Degradable Aliphatic Polycarbonate-Surfactants Based on mPEG, CO₂ and 1,2-Butylene Oxide
Carbon dioxide (CO₂) is a renewable carbon source which is easily available in high purity and is utilised as a comonomer in the direct ring-opening-polymerisation (ROP) of epoxides to obtain aliphatic polycarbonates (APCs). In the scope of this work degradable aliphatic polycarbonate surfactants (mPEG-b-PBC) were synthesised via catalytic polymerisation of CO₂ and 1,2-butylene oxide (BO) starting from mono methoxy poly(ethylene glycol) (mPEG) as macro-initiator. The polymerisation proceeded at low temperatures and high CO₂ pressure utilising the binary catalytic system (R, R)-(salcy)-CoCl/ [PPN]Cl. Surfactants with varying PBC block lengths and HLB values between 9-19 were synthesised. The polymers were characterised by NMR, FT-IR spectroscopy and SEC exhibiting molecular weights between 1,900–4,100 g mol⁻¹ and dispersities (Ð = Mw/Mn) between 1.07-1.18. Furthermore the thermal properties, such as Tg and Tm, as well as the critical micellation concentration (CMC) were determined. In addition, the surfactants enhanced the solubilization capacity of medium-chain surfactants in microemulsions and can, therefore, be used as efficiency boosters for microemulsions in small doses. The polycarbonate surfactants were characterised to full extent and show promising results concerning the stabilization of microemulsions.